Articles de revues : « Macrophages »

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Rodriguez, Eric, Frederic Boudard, Michele Mallié, Jean-Marie Bastide et Madeleine Bastide. « Murine macrophage elastolytic activity induced by Aspergillus fumigatus strains in vitro : evidence of the expression of two macrophage-induced protease genes ». Canadian Journal of Microbiology 43, n^o 7 (1 juillet 1997) : 649–57. http://dx.doi.org/10.1139/m97-092.

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The interaction between Aspergillus fumigatus conidia and murine macrophages of various origins was investigated. Cocultures were carried out between A. fumigatus strains and freshly isolated murine pulmonary alveolar macrophages or two murine macrophage cell-lines: murine alveolar cell-line MALU and murine astrocytoma cell-line J774. By measuring the variation of elastolytic activity in the coculture supernatants with two elastin substrates, we demonstrated that either viable or fixed A. fumigatus or C. albicans yeasts or nonspecific particles induced significant macrophage elastolytic activity. The effect of A. fumigatus supernatant or the purified A. fumigatus galactomannan suggested also the possible involvement of this polysaccharide in macrophage-protease gene expression, release, and activity in invasive aspergillosis. The effect of inhibitory compounds demonstrated the potential implication of a macrophagic metalloprotease and a macrophagic cysteine protease. RNA analysis allowed us to demonstrate the induction of expression of two macrophagic protease genes in stimulated macrophages. Two distinctive mechanisms appeared to be implicated in macrophage protease induction: nonspecific phagocytosis in the earliest times of the coculture and (or) specific galactomannan recognition after its gradual release by the mycelium.Key words: Aspergillus fumigatus, macrophages, proteases, invasive aspergillosis, galactomannan.

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Lu, Yufei, Leiming Guo et Gaofeng Ding. « PD1+ tumor associated macrophages predict poor prognosis of locally advanced esophageal squamous cell carcinoma ». Future Oncology 15, n^o 35 (décembre 2019) : 4019–30. http://dx.doi.org/10.2217/fon-2019-0519.

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Aim: Tumor associated macrophages are the most abundant cancer immune cells. However, little was known about the identity of CD68+PD1+ macrophages as well as the contributions in the prognosis of esophageal squamous cell carcinoma (ESCC). Methods & methods: Immunofluorescence, flowcytometry and RT-PCR were used to analysis PD1+ macrophages in ESCC. Results: CD68+PD1+ macrophages which can express higher M2 markers in cancer tissues, increased about 4.2-times compared with para-cancer tissues. Additionally, PD1high macrophages were significantly correlated with more malignant phenotypes and poor prognosis. PD1 treatment can enhance phagocytosis of cultured macrophages and redirect this macrophage to M1-like phenotype. Conclusion: Thus, our findings overall indicate that CD68+PD1+ macrophages are tumor associated macrophagess in ESCC, which can forecast the prognosis of ESCC.

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Hargarten, Jessica C., Tyler C. Moore, Thomas M. Petro, Kenneth W. Nickerson et Audrey L. Atkin. « Candida albicans Quorum Sensing Molecules Stimulate Mouse Macrophage Migration ». Infection and Immunity 83, n^o 10 (20 juillet 2015) : 3857–64. http://dx.doi.org/10.1128/iai.00886-15.

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The polymorphic commensal fungusCandida albicanscauses life-threatening disease via bloodstream and intra-abdominal infections in immunocompromised and transplant patients. Although host immune evasion is a common strategy used by successful human fungal pathogens,C. albicansprovokes recognition by host immune cells less capable of destroying it. To accomplish this,C. albicanswhite cells secrete a low-molecular-weight chemoattractive stimulant(s) of macrophages, a phagocyte that they are able to survive within and eventually escape from.C. albicansopaque cells do not secrete this chemoattractive stimulant(s). We report here a physiological mechanism that contributes to the differences in the interaction ofC. albicanswhite and opaque cells with macrophages.E,E-Farnesol, which is secreted by white cells only, is a potent stimulator of macrophage chemokinesis, whose activity is enhanced by yeast cell wall components and aromatic alcohols.E,E-farnesol results in up to an 8.5-fold increase in macrophage migrationin vitroand promotes a 3-fold increase in the peritoneal infiltration of macrophagesin vivo. Therefore, modulation of farnesol secretion to stimulate host immune recognition by macrophages may help explain why this commensal is such a successful pathogen.

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Yadav, Mahesh, et Jeffrey S. Schorey. « The β-glucan receptor dectin-1 functions together with TLR2 to mediate macrophage activation by mycobacteria ». Blood 108, n^o 9 (1 novembre 2006) : 3168–75. http://dx.doi.org/10.1182/blood-2006-05-024406.

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AbstractPattern recognition receptors (PRRs) play an essential role in a macrophage's response to mycobacterial infections. However, how these receptors work in concert to promote this macrophage response remains unclear. In this study, we used bone marrow–derived macrophages isolated from mannose receptor (MR), complement receptor 3 (CR3), MyD88, Toll-like receptor 4 (TLR4), and TLR2 knockout mice to examine the significance of these receptors in mediating a macrophage's response to a mycobacterial infection. We determined that mitogen-activated protein kinase (MAPK) activation and tumor necrosis factor-α (TNF-α) production in macrophage infected with Mycobacterium avium or M smegmatis is dependent on myeloid differentiation factor 88 (MyD88) and TLR2 but not TLR4, MR, or CR3. Interestingly, the TLR2-mediated production of TNF-α by macrophages infected with M smegmatis required the β-glucan receptor dectin-1. A similar requirement for dectin-1 in TNF-α production was observed for macrophages infected with M bovis Bacillus Calmette-Guerin (BCG), M phlei, M avium 2151-rough, and M tuberculosis H37Ra. The limited production of TNF-α by virulent M avium 724 and M tuberculosis H37Rv was not dependent on dectin-1. Furthermore, dectin-1 facilitated interleukin-6 (IL-6), RANTES (regulated on activation, normal T expressed and secreted), and granulocyte colony-stimulating factor (G-CSF) production by mycobacteria-infected macrophages. These are the first results to establish a significant role for dectin-1, in cooperation with TLR2, to activate a macrophage's proinflammatory response to a mycobacterial infection.

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Gallego, Carolina, Douglas Golenbock, Maria Adelaida Gomez et Nancy Gore Saravia. « Toll-Like Receptors Participate in Macrophage Activation and Intracellular Control of Leishmania (Viannia) panamensis ». Infection and Immunity 79, n^o 7 (25 avril 2011) : 2871–79. http://dx.doi.org/10.1128/iai.01388-10.

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ABSTRACTToll-like receptors (TLRs) play a central role in macrophage activation and control of parasitic infections. Their contribution to the outcome ofLeishmaniainfection is just beginning to be deciphered. We examined the interaction ofLeishmania panamensiswith TLRs in the activation of host macrophages.L. panamensisinfection resulted in upregulation of TLR1, TLR2, TLR3, and TLR4 expression and induced tumor necrosis factor alpha (TNF-α) secretion by human primary macrophages at comparable levels and kinetics to those of specific TLR ligands. The TLR dependence of the host cell response was substantiated by the absence of TNF-α production in MyD88/TRIF−/−murine bone marrow-derived macrophages and mouse macrophage cell lines in response to promastigotes and amastigotes. Systematic screening of TLR-deficient macrophages revealed that TNF-α production was completely abrogated in TLR4−/−macrophages, consistent with the increased intracellular parasite survival at early time points of infection. TNF-α secretion was significantly reduced in macrophages lacking endosomal TLRs but was unaltered by a lack of TLR2 or MD-2. Together, these findings support the participation of TLR4 and endosomal TLRs in the activation of host macrophages byL. panamensisand in the early control of infection.

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McKenzie, C. G. J., U. Koser, L. E. Lewis, J. M. Bain, H. M. Mora-Montes, R. N. Barker, N. A. R. Gow et L. P. Erwig. « Contribution of Candida albicans Cell Wall Components to Recognition by and Escape from Murine Macrophages ». Infection and Immunity 78, n^o 4 (1 février 2010) : 1650–58. http://dx.doi.org/10.1128/iai.00001-10.

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ABSTRACT The pathogenicity of the opportunistic human fungal pathogen Candida albicans depends on its ability to escape destruction by the host immune system. Using mutant strains that are defective in cell surface glycosylation, cell wall protein synthesis, and yeast-hypha morphogenesis, we have investigated three important aspects of C. albicans innate immune interactions: phagocytosis by primary macrophages and macrophage cell lines, hyphal formation within macrophage phagosomes, and the ability to escape from and kill macrophages. We show that cell wall glycosylation is critically important for the recognition and ingestion of C. albicans by macrophages. Phagocytosis was significantly reduced for mutants deficient in phosphomannan biosynthesis (mmn4Δ, pmr1Δ, and mnt3 mnt5Δ), whereas O- and N-linked mannan defects (mnt1Δ mnt2Δ and mns1Δ) were associated with increased ingestion, compared to the parent wild-type strains and genetically complemented controls. In contrast, macrophage uptake of mutants deficient in cell wall proteins such as adhesins (ece1Δ, hwp1Δ, and als3Δ) and yeast-locked mutants (clb2Δ, hgc1Δ, cph1Δ, efg1Δ, and efg1Δ cph1Δ), was similar to that observed for wild-type C. albicans. Killing of macrophages was abrogated in hypha-deficient strains, significantly reduced in all glycosylation mutants, and comparable to wild type in cell wall protein mutants. The diminished ability of glycosylation mutants to kill macrophages was not a consequence of impaired hyphal formation within macrophage phagosomes. Therefore, cell wall composition and the ability to undergo yeast-hypha morphogenesis are critical determinants of the macrophage's ability to ingest and process C. albicans.

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Wilson, Justin E., Bhuvana Katkere et James R. Drake. « Francisella tularensis Induces Ubiquitin-Dependent Major Histocompatibility Complex Class II Degradation in Activated Macrophages ». Infection and Immunity 77, n^o 11 (24 août 2009) : 4953–65. http://dx.doi.org/10.1128/iai.00844-09.

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ABSTRACT The intracellular bacterium Francisella tularensis survives and replicates within macrophages, ultimately killing the host cell. Resolution of infection requires the development of adaptive immunity through presentation of F. tularensis antigens to CD4+ and CD8+ T cells. We have previously established that F. tularensis induces macrophage prostaglandin E2 (PGE2) production, leading to skewed T-cell responses. PGE2 can also downregulate macrophage major histocompatibility complex (MHC) class II expression, suggesting that F. tularensis-elicited PGE2 may further alter T-cell responses via inhibition of class II expression. To test this hypothesis, gamma interferon (IFN-γ)-activated reporter macrophages were exposed to supernatants from F. tularensis-infected macrophages, and the class II levels were measured. Exposure of macrophages to infection supernatants results in essentially complete clearance of surface class II and CD86, compromising the macrophage's ability to present antigens to CD4 T cells. Biochemical analysis revealed that infection supernatants elicit ubiquitin-dependent class II downregulation and degradation within intracellular acidic compartments. By comparison, exposure to PGE2 alone only leads to a minor decrease in macrophage class II expression, demonstrating that a factor distinct from PGE2 is eliciting the majority of class II degradation. However, production of this non-PGE2 factor is dependent on macrophage cyclooxygenase activity and is induced by PGE2. These results establish that F. tularensis induces the production of a PGE2-dependent factor that elicits MHC class II downregulation in IFN-γ-activated macrophages through ubiquitin-mediated delivery of class II to lysosomes, establishing another mechanism for the modulation of macrophage antigen presentation during F. tularensis infection.

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Careau, Éric, Léa-Isabelle Proulx, Philippe Pouliot, Annie Spahr, Véronique Turmel et Élyse Y. Bissonnette. « Antigen sensitization modulates alveolar macrophage functions in an asthma model ». American Journal of Physiology-Lung Cellular and Molecular Physiology 290, n^o 5 (mai 2006) : L871—L879. http://dx.doi.org/10.1152/ajplung.00219.2005.

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We have previously demonstrated that adoptive transfer of alveolar macrophages from allergy-resistant rats to alveolar macrophage-depleted allergic rats prevents airway hyperresponsiveness development, suggesting an important role for alveolar macrophages in asthma pathogenesis. Given that ovalbumin sensitization can modulate alveolar macrophage cytokine production, we investigated the role of sensitized and unsensitized alveolar macrophages in an asthma model. Alveolar macrophages from unsensitized or sensitized Brown Norway rats were transferred to alveolar macrophage-depleted sensitized rats 24 h before allergen challenge. Airway responsiveness to methacholine and airway inflammation were measured the following day. Methacholine concentration needed to increase lung resistance by 200% was significantly higher in alveolar macrophage-depleted sensitized rats that received unsensitized alveolar macrophages compared with alveolar macrophage-depleted sensitized rats that received sensitized alveolar macrophages. Tumor necrosis factor levels in bronchoalveolar lavage fluid of sensitized rats that received unsensitized alveolar macrophages were significantly lower compared with rats that received sensitized alveolar macrophages. Interestingly, alveolar macrophages of unsensitized animals showed higher phagocytosis activity compared with alveolar macrophages of sensitized rats, suggesting that sensitization modulates alveolar macrophage phagocytosis function. Our data suggest an important role of allergen sensitization on alveolar macrophage function in asthma pathogenesis.

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Shinonaga, Masamichi, Cha Cheng Chang, Noriyuki Suzuki, Masazumi Sato et Takeo Kuwabara. « Immunohistological evaluation of macrophage infiltrates in brain tumors ». Journal of Neurosurgery 68, n^o 2 (février 1988) : 259–65. http://dx.doi.org/10.3171/jns.1988.68.2.0259.

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✓ Peritumoral edema is one of the most serious complications of intracranial neoplasms; however, the exact pathogenesis of this condition is still unknown. To explore the effect of macrophages in brain tumors on the pathogenesis of peritumoral edema, 42 specimens of primary or metastatic brain tumors were studied. Frozen sections were examined by an immunoperoxidase staining technique with anti-Leu-M3 monoclonal antibody. Eight of 14 gliomas demonstrated Leu-M3-positive cell (macrophage) infiltration. The two glioblastomas showed a moderate or marked degree of macrophage infiltration. Twelve of 16 meningiomas demonstrated varying degrees of macrophage infiltration. All six metastatic brain tumors exhibited prominent macrophagesin intra- and peritumoral tissues. Four acoustic neurinomas and two hemangioblastomas showed a slight to moderate degree of macrophage infiltration. Excellent correlation was found between the degree of macrophage infiltration seen on immunoperoxidase staining and the peritumoral edema detected on computerized tomography brain scans of patients with supratentorial tumors, especially meningiomas. Macrophages are known to secrete various substances (including arachidonate metabolites) that may interfere with vascular permeability. These data suggest that macrophages infiltrating brain tumors may play an important role in the pathogenesis of peritumoral edema.

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Fedorov, A. A., N. A. Ermak, T. S. Gerashchenko, E. B. Topolnitskii, N. A. Shefer, E. O. Rodionov et M. N. Stakheyeva. « Polarization of macrophages : mechanisms, markers and factors of induction ». Siberian journal of oncology 21, n^o 4 (3 septembre 2022) : 124–36. http://dx.doi.org/10.21294/1814-4861-2022-21-4-124-136.

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Macrophages are key components of the innate immune system. The variability of the macrophage’s participation in tumor progression, determined by their functional polarization, opens up a wide prospect for modulating their functional profile, primarily in the direction of increasing antitumor activity. The purpose of the study was to provide up-to-date data on the process of macrophage polarization, mechanisms of its regulation, polarization markers and induction factors. Material and methods. A search was made for available literature sources published in Web of Science, Scopus and other databases. more than 160 sources devoted to the study of the process of macrophage polarization were found, of which 121 were included in this review. Results. This review presents data on the molecular mechanisms and gene signatures associated with M1 and M2 polarization of macrophages. We displayed information on metabolic, phenotypic characteristics and cytokine profile of M1- and M2-macrophages, as well as highlighted data on polarization factors and targets of their action. Conclusion. The information presented in the review can serve as an information base for the development of experimental and clinical approaches for editing the functional profile of macrophages in order to control their involvement in various pathological processes.

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Xu, Jiawei, Lanya Fu, Junyao Deng, Jiaqi Zhang, Ying Zou, Liqiang Liao, Xinrui Ma et al. « miR-301a Deficiency Attenuates the Macrophage Migration and Phagocytosis through YY1/CXCR4 Pathway ». Cells 11, n^o 24 (7 décembre 2022) : 3952. http://dx.doi.org/10.3390/cells11243952.

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(1) Background: the miR-301a is well known involving the proliferation and migration of tumor cells. However, the role of miR-301a in the migration and phagocytosis of macrophages is still unclear. (2) Methods: sciatic nerve injury, liver injury models, as well as primary macrophage cultures were prepared from the miR-301a knockout (KO) and wild type (WT) mice to assess the macrophage’s migration and phagocytosis capabilities. Targetscan database analysis, Western blotting, siRNA transfection, and CXCR4 inhibition or activation were performed to reveal miR301a’s potential mechanism. (3) Results: the macrophage’s migration and phagocytosis were significantly attenuated by the miR-301a KO both in vivo and in vitro. MiR-301a can target Yin-Yang 1 (YY1), and miR-301a KO resulted in YY1 up-regulation and CXCR4 (YY1′s down-stream molecule) down-regulation. siYY1 increased the expression of CXCR4 and enhanced migration and phagocytosis in KO macrophages. Meanwhile, a CXCR4 inhibitor or agonist could attenuate or accelerate, respectively, the macrophage migration and phagocytosis. (4) Conclusions: current findings indicated that miR-301a plays important roles in a macrophage’s capabilities of migration and phagocytosis through the YY1/CXCR4 pathway. Hence, miR-301a might be a promising therapeutic candidate for inflammatory diseases by adjusting macrophage bio-functions.

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Bonetti, Justine, Alessandro Corti, Lucie Lerouge, Alfonso Pompella et Caroline Gaucher. « Phenotypic Modulation of Macrophages and Vascular Smooth Muscle Cells in Atherosclerosis—Nitro-Redox Interconnections ». Antioxidants 10, n^o 4 (26 mars 2021) : 516. http://dx.doi.org/10.3390/antiox10040516.

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Monocytes/macrophages and vascular smooth muscle cells (vSMCs) are the main cell types implicated in atherosclerosis development, and unlike other mature cell types, both retain a remarkable plasticity. In mature vessels, differentiated vSMCs control the vascular tone and the blood pressure. In response to vascular injury and modifications of the local environment (inflammation, oxidative stress), vSMCs switch from a contractile to a secretory phenotype and also display macrophagic markers expression and a macrophagic behaviour. Endothelial dysfunction promotes adhesion to the endothelium of monocytes, which infiltrate the sub-endothelium and differentiate into macrophages. The latter become polarised into M1 (pro-inflammatory), M2 (anti-inflammatory) or Mox macrophages (oxidative stress phenotype). Both monocyte-derived macrophages and macrophage-like vSMCs are able to internalise and accumulate oxLDL, leading to formation of “foam cells” within atherosclerotic plaques. Variations in the levels of nitric oxide (NO) can affect several of the molecular pathways implicated in the described phenomena. Elucidation of the underlying mechanisms could help to identify novel specific therapeutic targets, but to date much remains to be explored. The present article is an overview of the different factors and signalling pathways implicated in plaque formation and of the effects of NO on the molecular steps of the phenotypic switch of macrophages and vSMCs.

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DiNapoli, Sarah R., Vanessa M. Hirsch et Jason M. Brenchley. « Macrophages in Progressive Human Immunodeficiency Virus/Simian Immunodeficiency Virus Infections ». Journal of Virology 90, n^o 17 (15 juin 2016) : 7596–606. http://dx.doi.org/10.1128/jvi.00672-16.

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The cells that are targeted by primate lentiviruses (HIV and simian immunodeficiency virus [SIV]) are of intense interest given the renewed effort to identify potential cures for HIV. These viruses have been reported to infect multiple cell lineages of hematopoietic origin, including all phenotypic and functional CD4 T cell subsets. The two most commonly reported cell types that become infectedin vivoare memory CD4 T cells and tissue-resident macrophages. Though viral infection of CD4 T cells is routinely detected in both HIV-infected humans and SIV-infected Asian macaques, significant viral infection of macrophages is only routinely observed in animal models wherein CD4 T cells are almost entirely depleted. Here we review the roles of macrophages in lentiviral disease progression, the evidence that macrophages support viral replicationin vivo, the animal models where macrophage-mediated replication of SIV is thought to occur, how the virus can interact with macrophagesin vivo, pathologies thought to be attributed to viral replication within macrophages, how viral replication in macrophages might contribute to the asymptomatic phase of HIV/SIV infection, and whether macrophages represent a long-lived reservoir for the virus.

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García-Rodas, Rocío, Fernando González-Camacho, Juan Luis Rodríguez-Tudela, Manuel Cuenca-Estrella et Oscar Zaragoza. « The Interaction between Candida krusei and Murine Macrophages Results in Multiple Outcomes, Including Intracellular Survival and Escape from Killing ». Infection and Immunity 79, n^o 6 (21 mars 2011) : 2136–44. http://dx.doi.org/10.1128/iai.00044-11.

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ABSTRACTCandida kruseiis a fungal pathogen of interest for the scientific community for its intrinsic resistance to fluconazole. Little is known about the interaction of this yeast with host immune cells. In this work, we have characterized the outcome of the interaction betweenC. kruseiand murine macrophages. OnceC. kruseiwas internalized, we observed different phenomena. In a macrophage-like cell line,C. kruseisurvived in a significant number of macrophages and induced filamentation and macrophage explosion. Phagocytosis ofC. kruseiled to actin polymerization around the yeast cells at the site of entry. Fluorescent specific staining with anti-Lamp1 and LysoTracker indicated that after fungal internalization, there was a phagolysosome maturation defect, a phenomenon that was more efficient when the macrophages phagocytosed killed yeast cells. Using cell line macrophages, we also observed macrophage fusion after cell division. When we used primary resident peritoneal macrophages in addition to macrophage explosion, we also observed a strong chemotaxis of uninfected macrophages to regions whereC. krusei-infected macrophages were present. We also noticed yeast transfer phenomena between infected macrophages. Primary macrophages inhibited pseudohypha elongation more efficiently than the macrophage-like cell line, suggesting thatC. kruseiinfection was better controlled by the former macrophages. Primary macrophages induced more tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) than the macrophage-like cell line. Our results demonstrate thatC. kruseican exploit the macrophages for replication, although other different outcomes are also possible, indicating that the interaction of this pathogen with phagocytic cells is very complex and regulated by multiple factors.

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Taylor, Sarah A., Shang-Yang Chen, Gaurav Gadhvi, Liang Feng, Kyle D. Gromer, Hiam Abdala-Valencia, Kiwon Nam et al. « Transcriptional profiling of pediatric cholestatic livers identifies three distinct macrophage populations ». PLOS ONE 16, n^o 1 (7 janvier 2021) : e0244743. http://dx.doi.org/10.1371/journal.pone.0244743.

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Background & aims Limited understanding of the role for specific macrophage subsets in the pathogenesis of cholestatic liver injury is a barrier to advancing medical therapy. Macrophages have previously been implicated in both the mal-adaptive and protective responses in obstructive cholestasis. Recently two macrophage subsets were identified in non-diseased human liver; however, no studies to date fully define the heterogeneous macrophage subsets during the pathogenesis of cholestasis. Here, we aim to further characterize the transcriptional profile of macrophages in pediatric cholestatic liver disease. Methods We isolated live hepatic immune cells from patients with biliary atresia (BA), Alagille syndrome (ALGS), and non-cholestatic pediatric liver by fluorescence activated cell sorting. Through single-cell RNA sequencing analysis and immunofluorescence, we characterized cholestatic macrophages. We next compared the transcriptional profile of pediatric cholestatic and non-cholestatic macrophage populations to previously published data on normal adult hepatic macrophages. Results We identified 3 distinct macrophage populations across cholestatic liver samples and annotated them as lipid-associated macrophages, monocyte-like macrophages, and adaptive macrophages based on their transcriptional profile. Immunofluorescence of liver tissue using markers for each subset confirmed their presence across BA (n = 6) and ALGS (n = 6) patients. Cholestatic macrophages demonstrated reduced expression of immune regulatory genes as compared to normal hepatic macrophages and were distinct from macrophage populations defined in either healthy adult or pediatric non-cholestatic liver. Conclusions We are the first to perform single-cell RNA sequencing on human pediatric cholestatic liver and identified three macrophage subsets with distinct transcriptional signatures from healthy liver macrophages. Further analyses will identify similarities and differences in these macrophage sub-populations across etiologies of cholestatic liver disease. Taken together, these findings may allow for future development of targeted therapeutic strategies to reprogram macrophages to an immune regulatory phenotype and reduce cholestatic liver injury.

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Ulndreaj, Antigona, Angela Li, Yonghong Chen, Rickvinder Besla, Shaun Pacheco, Marwan G. Althagafi, Myron I. Cybulsky, Thomas Lindsay, Clinton S. Robbins et John S. Byrne. « Adventitial recruitment of Lyve-1− macrophages drives aortic aneurysm in an angiotensin-2-based murine model ». Clinical Science 135, n^o 10 (mai 2021) : 1295–309. http://dx.doi.org/10.1042/cs20200963.

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Abstract Objective: Aortic macrophage accumulation is characteristic of the pathogenesis of abdominal aortic aneurysm (AAA) but the mechanisms of macrophage accumulation and their phenotype are poorly understood. Lymphatic vessel endothelial receptor-1 (Lyve-1+) resident aortic macrophages independently self-renew and are functionally distinct from monocyte-derived macrophages recruited during inflammation. We hypothesized that Lyve-1+ and Lyve-1− macrophages differentially contribute to aortic aneurysm. Approach and results: Angiotensin-2 and β-aminopropionitrile (AT2/BAPN) were administered to induce AAA in C57BL/6J mice. Using immunohistochemistry (IHC), we demonstrated primarily adventitial accumulation of aortic macrophages, and in association with areas of elastin fragmentation and aortic dissection. Compared with controls, AAA was associated with a relative percent depletion of Lyve-1+ resident aortic macrophages and accumulation of Lyve-1− macrophages. Using CD45.1/CD45.2 parabiosis, we demonstrated aortic macrophage recruitment in AAA. Depletion of aortic macrophages in CCR2−/− mice was associated with reduced aortic dilatation indicating the functional role of recruitment from the bone marrow. Depletion of aortic macrophages using anti-macrophage colony-stimulating factor 1 receptor (MCSF1R)-neutralizing antibody (Ab) reduced the incidence of AAA. Conditional depletion of Lyve-1+ aortic macrophages was achieved by generating Lyve-1wt/cre Csf1rfl/fl mice. Selective depletion of Lyve-1+ aortic macrophages had no protective effects following AT2/BAPN administration and resulted in increased aortic dilatation in the suprarenal aorta. Conclusions: Aortic macrophage accumulation in AAA derives from adventitial recruitment of Lyve-1− macrophages, with relative percent depletion of Lyve-1+ macrophages. Selective targeting of macrophage subtypes represents a potential novel therapeutic avenue for the medical treatment of AAA.

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Deng, Lishuang, Zhijie Jian, Tong Xu, Fengqin Li, Huidan Deng, Yuancheng Zhou, Siyuan Lai, Zhiwen Xu et Ling Zhu. « Macrophage Polarization : An Important Candidate Regulator for Lung Diseases ». Molecules 28, n^o 5 (4 mars 2023) : 2379. http://dx.doi.org/10.3390/molecules28052379.

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Macrophages are crucial components of the immune system and play a critical role in the initial defense against pathogens. They are highly heterogeneous and plastic and can be polarized into classically activated macrophages (M1) or selectively activated macrophages (M2) in response to local microenvironments. Macrophage polarization involves the regulation of multiple signaling pathways and transcription factors. Here, we focused on the origin of macrophages, the phenotype and polarization of macrophages, as well as the signaling pathways associated with macrophage polarization. We also highlighted the role of macrophage polarization in lung diseases. We intend to enhance the understanding of the functions and immunomodulatory features of macrophages. Based on our review, we believe that targeting macrophage phenotypes is a viable and promising strategy for treating lung diseases.

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Yaparla, Amulya, Milan Popovic, Kelsey A. Hauser, Louise A. Rollins-Smith et Leon Grayfer. « Amphibian (Xenopus laevis) Macrophage Subsets Vary in Their Responses to the Chytrid Fungus Batrachochytrium dendrobatidis ». Journal of Fungi 11, n^o 4 (15 avril 2025) : 311. https://doi.org/10.3390/jof11040311.

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The chytrid fungus, Batrachochytrium dendrobatidis (Bd), infects amphibian skin, causing chytridiomycosis, which is a contributing cause of worldwide declines and extinctions of amphibians. Relatively little is known about the roles of amphibian skin-resident immune cells, such as macrophages, in these antifungal defenses. Across vertebrates, macrophage differentiation is controlled through the activation of colony-stimulating factor-1 (CSF1) receptor by CSF1 and interleukin-34 (IL34) cytokines. While the precise roles of these respective cytokines in macrophage development remain to be fully explored, our ongoing studies indicate that frog (Xenopus laevis) macrophages differentiated by recombinant forms of CSF1 and IL34 are functionally distinct. Accordingly, we explored the roles of X. laevis CSF1- and IL34-macrophages in anti-Bd defenses. Enriching cutaneous IL34-macrophages, but not CSF1-macrophages, resulted in significant anti-Bd protection. In vitro analysis of frog macrophage-Bd interactions indicated that both macrophage subsets phagocytosed Bd. However, IL34-macrophages cocultured with Bd exhibited greater pro-inflammatory gene expression, whereas CSF1-macrophages cocultured with Bd showed greater immunosuppressive gene expression profiles. Concurrently, Bd-cocultured with CSF1-macrophages, but not IL34-macrophages, possessed elevated expression of genes associated with immune evasion. This work marks a step forward in our understanding of the roles of frog macrophage subsets in antifungal defenses.

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AlQasrawi, Dania, et Saleh A. Naser. « Nicotine Modulates MyD88-Dependent Signaling Pathway in Macrophages during Mycobacterial Infection ». Microorganisms 8, n^o 11 (17 novembre 2020) : 1804. http://dx.doi.org/10.3390/microorganisms8111804.

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Recently, we reported that cigarette smoking, and especially nicotine, increases susceptibility to mycobacterial infection and exacerbates inflammation in patients with Crohn’s disease (CD). The macrophagic response to Mycobacterium avium subspecies paratuberculosis (MAP) in CD and Mycobacteria tuberculosis (MTB) continues to be under investigation. The role of toll-like-receptors (TLRs) and cytoplasmic adaptor protein (MyD88) in proinflammatory response during Mycobacterial infection has been suggested. However, the mechanism of how nicotine modulates macrophage response during infection in CD and exacerbates inflammatory response remain unclear. In this study, we elucidated the mechanistic role of nicotine in modulating MyD88-dependent/TLR pathway signaling in a macrophage system during mycobacterial infection. The data demonstrated that MAP infection in THP-1 derived macrophages was mediated through TLR2 and MyD88 leading to increase in IL-8 in expression and production. On the other hand, LPS-representing, Gram-negative bacteria mediated macrophage response through TLR4. Blocking TLR2 and TLR4 with antagonists voided the effect of MAP, and LPS, respectively in macrophages and reversed response with decrease in expression of iNOS, TNF-α and IL-8. Interestingly, nicotine in infected macrophages significantly (1) downregulated TLR2 and TLR4 expression, (2) activated MyD88, (3) increased M1/M2 ratio, and (4) increased expression and secretion of proinflammatory cytokines especially IL-8, as seen in CD smokers. We also discovered that blocking macrophages during MAP infection with MyD88 antagonist significantly decreased response which illustrates the key role for MyD88 during infection. Surprisingly, dual treatment of MAP-infected macrophages with MyD88 antagonist and nicotine absolutely impaired immune response and decreased MAP viability, which clearly validate the inflammatory role of nicotine in macrophages through TLR2/MyD88 pathway during infection. This is the first report to describe the mechanism by which nicotine modulates TLR2/MyDD88 and exacerbates inflammation in CD smokers associated with infection.

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Randolph, Gwendalyn J. « Monocyte Trafficking, Inflammation, and Atherosclerosis ». Blood 122, n^o 21 (15 novembre 2013) : SCI—53—SCI—53. http://dx.doi.org/10.1182/blood.v122.21.sci-53.sci-53.

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Abstract Macrophages are central to the progression of atherosclerosis. An increased number of macrophages in plaque are associated with larger, more stenotic lesions. Furthermore, activated plaque macrophages promote rupture, the most significant clinical event affecting mortality. Plaque macrophages derive from monocytes that are recruited from blood. We have thus focused our efforts on understanding the mechanisms that regulate plaque macrophages, with emphasis on how macrophage-burden might be reduced to lower disease risk. We have developed techniques to discern whether macrophage contraction in plaques is due to emigration out of the plaque environment. Although this idea was our leading hypothesis, data obtained in a model of regression carried out in apoE-/- mice indicates that emigration of macrophages does not occur during regression. The idea was based on previous literature that monocyte-derived cells might be removed from sites of acute inflammation by emigrating to local lymph nodes. After finding that emigration of macrophages from resolving plaque in apoE-/- mice was poor, we revisited models of acute inflammation; in particular, thioglycollate-induced peritonitis, where emigration had been claimed to account for macrophage removal. New methodology to improve the quantification of macrophage loss from the peritoneum indicated that, like atherosclerosis, emigration of macrophages was a minor contributor to the contraction of macrophages associated with resolution. Instead, in both settings, macrophage loss was associated with a strong suppression of monocyte recruitment, coupled with ongoing macrophage apoptosis. These data strongly suggest that methods to block monocyte recruitment may provide a viable approach to reversing atherosclerosis. Current efforts focus on integrating the role of monocyte recruitment with local proliferation of macrophages in plaques, investigating macrophage motility in plaques during different disease states, and evaluating contraction of macrophages from plaques using other models of disease regression. Disclosures: No relevant conflicts of interest to declare.

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Li, Wei, Yaomei Wang, Huizhi Zhao, Huan Zhang, Yuanlin Xu, Shihui Wang, Xinhua Guo et al. « Identification, Isolation and Transcriptome Analyses of Mouse, Rat and Man Erythroblastic Island Central Macrophages ». Blood 132, Supplement 1 (29 novembre 2018) : 841. http://dx.doi.org/10.1182/blood-2018-99-114188.

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Abstract Erythroblastic island (EBI), composed of a central macrophage and surrounding erythroid cells, is the first hematopoietic niche discovered for erythropoiesis. Yet, the identity of the central macrophage has so far remained elusive. Based on the previous findings that F4/80, VCAM1 and CD169 are potential mouse central macrophage markers, we first calculated the number of F4/80+VCAM1+CD169+ mouse macrophages in the mouse bone marrow and compared it to the number of Ter119+ erythroblasts. We found that the ratio of F4/80+VCAM1+CD169+ macrophage and erythroblasts is about 1:2. Given the fact that one central macrophage is surrounded by multiple erythroblasts, the above finding suggests that it is unlikely that all the F4/80+VCAM1+CD169+ macrophages are central macrophages. Erythropoietin (Epo) is essential for erythropoiesis. It has been reported that the Epo receptor (Epor) is expressed in peritoneal macrophages. These findings promoted us to speculate that EBI central macrophages may express Epor so that Epo acts on both erythroid cells and the central macrophages simultaneously in the niche to ensure efficient and optimal red cell production. To test this notion, we first examined whether mouse bone marrow and fetal liver macrophages express Epor using the Epor-GFPcre knockin mouse model. We found that ~5% of bone marrow F4/80+ macrophages and ~35% of fetal liver F4/80+ macrophages express Epor-GFP. As negative control, no Epor-GFP macrophages are noted in wild type F4/80+ macrophages. Importantly, ImageStream analyses revealed the native EBIs in bone marrow and fetal liver are formed by Epor+ but not Epor- macrophages. Bioinformatics analyses of RNA-seq data on the sorted Epor+ and Epor- macrophage populations revealed that molecules involved in central macrophage-erythroblast association such as VCAM1, CD169, and molecules known to be important for central macrophage function such as Dnase2a, ferroportin, are highly expressed in Epor+ macrophages. In marked contrast, highly expressed pathways in Epor- macrophages are associated with immune responses including antigen process and presentation. Intriguingly, the immune related pathways are dramatically downregulated in the Epor+ macrophages, suggesting that the Epor+ macrophages in bone marrow and fetal liver have evolved a specialized function in supporting erythropoiesis. To examine whether expression of Epor in EBI central macrophages is a conserved feature across species, we generated Epor-GFPcre knockin rat using the CRISP/Cas9 technology. Using CD163 as rat macrophage marker, we found that a subpopulation of rat bone marrow CD163+ macrophages expresses Epor-GFP. As a negative control, no Epor-GFP macrophages are noted in wild type CD163+ macrophages. To examine whether EPOR is expressed in human EBI central macrophages, antibody specificity for human EPOR is critical. To this end, we employed CRISP/Cas9 approach to knock out EPOR in K562 and Hela cell lines and validated the specificity of a commercially available anti-human EPOR antibody. Using CD163, CD169 as human macrophage markers, we found that EPOR is also expressed in a subpopulation of human macrophages. Moreover, in vitro EBI formation assay revealed that human EPOR+ but not EPOR- macrophages form EBIs with erythroid cells and that the EBI formation is enhanced by EPO. In summary, we for the first time, after discovery of the EBIs 60 years ago, have identified Epor+ macrophages in mouse bone marrow and fetal liver as EBI central macrophages. Our findings provide solid foundation for studying the mechanisms by which erythropoieis is supported EBI central macrophages. A better understanding of such mechanisms will provide extensive new knowledge on basic biology of erythropoiesis. It is also important to understand the pathology of erythropoietic disorders as well as to improve ex vivo erythrocyte production. Disclosures No relevant conflicts of interest to declare.

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Wang, Jianjun, Yongliang Yao, Jing Xiong, Jianhong Wu, Xin Tang et Guangxin Li. « Evaluation of the Inflammatory Response in Macrophages Stimulated with Exosomes Secreted byMycobacterium avium-Infected Macrophages ». BioMed Research International 2015 (2015) : 1–9. http://dx.doi.org/10.1155/2015/658421.

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Exosomes secreted fromMycobacterium avium-infected macrophages contain numerous antigens of bothM. aviumand the host cell and are involved in the induction and expression of the inflammatory responses in macrophages. The interaction between exosomes secreted fromM. avium-infected macrophages and macrophage phagocytosis, cytokine secretion, immunostimulation, and apoptosis was analyzed. Upon stimulation with exosomes secreted fromM. avium-infected macrophages, the phagocytosis of dextran by treated macrophages was increased. Furthermore, the expression of CD40, CD80, CD81, CD86, HLA-DR, and most notably CD195 was enhanced. Additionally, the secretion of IL-6, IL-8, IL-10, IFN-γ, and TNF-αwas increased by stimulated macrophages. Exosome stimulation did not induce macrophage apoptosis when compared with macrophages infected withM. avium. Caspase expression, including that of caspases 3, 6, and 8, was also not altered in exosome stimulated macrophages. Thus exosomes trigger the inflammatory response in macrophages owing to the presence of bacterial antigens but have no effect on macrophage viability.

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Fischer, Carrie D., Jennifer K. Beatty, Stephanie C. Duquette, Douglas W. Morck, Merlyn J. Lucas et André G. Buret. « Direct and Indirect Anti-Inflammatory Effects of Tulathromycin in Bovine Macrophages : Inhibition of CXCL-8 Secretion, Induction of Apoptosis, and Promotion of Efferocytosis ». Antimicrobial Agents and Chemotherapy 57, n^o 3 (7 janvier 2013) : 1385–93. http://dx.doi.org/10.1128/aac.01598-12.

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ABSTRACTRecent evidence indicates that immunomodulation by antibiotics may enhance their clinical efficacy. Specifically, drug-induced leukocyte apoptosis and macrophage efferocytosis have been shown to promote the resolution of inflammation in a variety of disease settings. Tulathromycin is a new macrolide antibiotic for the treatment of bovine respiratory disease. The direct antimicrobial effects of the drug alone do not fully justify its superior clinical efficacy, and we hypothesize that tulathromycin may have immunomodulating properties. We recently reported that tulathromycin promotes apoptosis and inhibits proinflammatory NF-κB signaling in bovine neutrophils. In this study, we investigated the direct and indirect anti-inflammatory effects of tulathromycin in bovine macrophages. The findings indicate that bovine monocyte-derived macrophages and alveolar macrophages readily phagocytose tulathromycin-induced apoptotic neutrophils bothin vitroand in the airways ofMannheimia haemolytica-infected calves. Moreover, tulathromycin promotes delayed, concentration-dependent apoptosis, but not necrosis, in bovine macrophagesin vitro. Activation of caspase-3 and detection of mono- and oligonucleosomes in bovine monocyte-derived macrophages treated with tulathromycin was observed 12 h posttreatment; pretreatment with a pan-caspase inhibitor (ZVAD) blocked the proapoptotic effects of the drug. Lastly, tulathromycin inhibited the secretion of proinflammatory CXCL-8 in lipopolysaccharide (LPS)-stimulated bovine macrophages; this effect was independent of caspase activation or programmed cell death. Taken together, these immunomodulating effects observed in bovine macrophages help further elucidate the mechanisms through which tulathromycin confers anti-inflammatory and proresolution benefits. Furthermore, these findings offer novel insights on how antibiotics may offer anti-inflammatory benefits by modulating macrophage-mediated events that play a key role in inflammation.

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Lu, Chunxia, P. Anil Kumar, Yong Fan, Mark A. Sperling et Ram K. Menon. « A Novel Effect of Growth Hormone on Macrophage Modulates Macrophage-Dependent Adipocyte Differentiation ». Endocrinology 151, n^o 5 (25 février 2010) : 2189–99. http://dx.doi.org/10.1210/en.2009-1194.

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The GH receptor (GHR) is expressed on macrophages. However, the precise role of GH in regulation of macrophage function is unclear. We hypothesized that soluble factors including cytokines produced by macrophages in a GH-dependent manner regulate adipogenesis. We confirmed expression and functional integrity of the GHR in the J774A.1 macrophage cells. Conditioned medium (CM) from macrophages inhibited adipogenesis in a 3T3-L1 adipogenesis assay. CM from GH-treated macrophages decreased the inhibitory effect of CM from macrophages on adipogenesis. This effect on preadipocyte differentiation was active only during the first (early) phase of adipocyte differentiation. CM from stromal vascular compartment macrophages of mice with macrophage-specific deletion of the GHR exhibited more inhibitory effect on 3T3-L1 preadipocyte differentiation compared with CM from stromal vascular compartment macrophages of control mice, indicating that intact GH action in primary macrophages also increases preadipocyte differentiation. GH did not increase IGF-1 expression in macrophages. PCR array analysis identified IL-1β as a candidate cytokine whose expression was altered by GH in macrophages. Levels of IL-1β mRNA and protein were significantly decreased in GH-treated J774A.1 macrophages. Nuclear factor-κB stimulates IL-1β gene expression, and GH induced a significant decrease in the levels of phosphorylated nuclear factor-κB in macrophages. IL-1β is a known inhibitor of adipogenesis, and these results support GH-dependent down-regulation of macrophage IL-1β expression as one mechanism for the observed increase in adipogenesis with CM from GH-treated macrophages. We conclude that GH decreases secretion of IL-1β by the macrophage and thus in a paracrine manner increases adipocyte differentiation. These results provide a novel mechanism for GH’s actions in the control of adipogenesis.

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Cotechini, Tiziana, Aline Atallah et Arielle Grossman. « Tissue-Resident and Recruited Macrophages in Primary Tumor and Metastatic Microenvironments : Potential Targets in Cancer Therapy ». Cells 10, n^o 4 (20 avril 2021) : 960. http://dx.doi.org/10.3390/cells10040960.

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Macrophages within solid tumors and metastatic sites are heterogenous populations with different developmental origins and substantially contribute to tumor progression. A number of tumor-promoting phenotypes associated with both tumor- and metastasis-associated macrophages are similar to innate programs of embryonic-derived tissue-resident macrophages. In contrast to recruited macrophages originating from marrow precursors, tissue-resident macrophages are seeded before birth and function to coordinate tissue remodeling and maintain tissue integrity and homeostasis. Both recruited and tissue-resident macrophage populations contribute to tumor growth and metastasis and are important mediators of resistance to chemotherapy, radiation therapy, and immune checkpoint blockade. Thus, targeting various macrophage populations and their tumor-promoting phenotypes holds therapeutic promise. Here, we discuss various macrophage populations as regulators of tumor progression, immunity, and immunotherapy. We provide an overview of macrophage targeting strategies, including therapeutics designed to induce macrophage depletion, impair recruitment, and induce repolarization. We also provide a perspective on the therapeutic potential for macrophage-specific acquisition of trained immunity as an anti-cancer agent and discuss the therapeutic potential of exploiting macrophages and their traits to reduce tumor burden.

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GREGORY, D. J., et M. OLIVIER. « Subversion of host cell signalling by the protozoan parasiteLeishmania ». Parasitology 130, S1 (mars 2005) : S27—S35. http://dx.doi.org/10.1017/s0031182005008139.

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The protozoaLeishmaniaspp. are obligate intracellular parasites that inhabit the macrophages of their host. Since macrophages are specialized for the identification and destruction of invading pathogens, both directly and by triggering an innate immune response,Leishmaniahave evolved a number of mechanisms for suppressing some critical macrophage activities. In this review, we discuss how various species ofLeishmaniadistort the host macrophage's own signalling pathways to repress the expression of various cytokines and microbicidal molecules (nitric oxide and reactive oxygen species), and antigen presentation. In particular, we describe how MAP Kinase and JAK/STAT cascades are repressed, and intracellular Ca2+and the activities of protein tyrosine phosphatases, in particular SHP-1, are elevated.

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Gautier, Emmanuel L., Stoyan Ivanov, Jesse W. Williams, Stanley Ching-Cheng Huang, Genevieve Marcelin, Keke Fairfax, Peter L. Wang et al. « Gata6 regulates aspartoacylase expression in resident peritoneal macrophages and controls their survival ». Journal of Experimental Medicine 211, n^o 8 (14 juillet 2014) : 1525–31. http://dx.doi.org/10.1084/jem.20140570.

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The transcription factor Gata6 regulates proliferation and differentiation of epithelial and endocrine cells and cancers. Among hematopoietic cells, Gata6 is expressed selectively in resident peritoneal macrophages. We thus examined whether the loss of Gata6 in the macrophage compartment affected peritoneal macrophages, using Lyz2-Cre x Gata6flox/flox mice to tackle this issue. In Lyz2-Cre x Gata6flox/flox mice, the resident peritoneal macrophage compartment, but not macrophages in other organs, was contracted, with only a third the normal number of macrophages remaining. Heightened rates of death explained the marked decrease in peritoneal macrophage observed. The metabolism of the remaining macrophages was skewed to favor oxidative phosphorylation and alternative activation markers were spontaneously and selectively induced in Gata6-deficient macrophages. Gene expression profiling revealed perturbed metabolic regulators, including aspartoacylase (Aspa), which facilitates generation of acetyl CoA. Mutant mice lacking functional Aspa phenocopied the higher propensity to death and led to a contraction of resident peritoneal macrophages. Thus, Gata6 regulates differentiation, metabolism, and survival of resident peritoneal macrophages.

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Dende, Chaitanya, Mihir Pendse, Daniel Propheter, Gabriella Quinn et Lora V. Hooper. « Vitamin A regulates phagocytosis by resident macrophages of the small intestine ». Journal of Immunology 208, n^o 1_Supplement (1 mai 2022) : 113.23. http://dx.doi.org/10.4049/jimmunol.208.supp.113.23.

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Abstract Intestinal Tim4+ CD4+ macrophages are a distinctive macrophage subset that express Tim4, a receptor for phosphatidylserine on dying apoptotic cells, Unlike other macrophage subsets, they do not depend on blood monocytes for their turnover, instead self-maintained in the small intestine. The signal(s) responsible for the self-maintenance and function of Tim4+ CD4+ macrophages is not known. We have discovered that maintenance of the gut resident Tim4+ CD4+ macrophage population depends on dietary vitamin A and its derivative retinoic acid (RA). Retinoic acid receptors, which direct RA-dependent transcription, were required for maintenance of Tim4+ CD4+ macrophages. Chemical blockade of retinoic acid receptor (RAR) signaling and macrophage-specific genetic inactivation of RARs in mice further revealed that macrophage-intrinsic RARα signaling was required for Timd4 expression and maintenance of Tim4+ CD4+ macrophages. Macrophage RARα signaling was furthermore essential for phagocytosis by Tim4+ CD4+ macrophages. Ongoing studies are examining the role of Tim4+ CD4+ macrophages and vitamin A in the clearance of apoptotic intestinal epithelial cells. Our findings reveal that vitamin A provides an essential dietary signal for the maintenance and function of a gut resident macrophage subset. Supported by Welch foundation grant I-1874

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Singh, Gyanesh, U. C. Pachouri, Chirag Chopra, Preeti Bajaj et Pushplata Singh. « Macrophage Gene Therapy : opening novel therapeutic avenues for immune disorders ». F1000Research 4 (6 août 2015) : 495. http://dx.doi.org/10.12688/f1000research.6817.1.

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Macrophages are probably the most important cells of the mammalian immune system, and compromised macrophage function is known to cause several diseases. Their involvement in arthritis, cancer, infections, atherosclerosis, diabetes, and autoimmune disorders is well known. There has been a constantly growing need to transfer therapeutic genes into macrophages. Like most non-macrophage gene therapies,in vitrogene transfer has been attempted much more frequently in case of macrophages. However, primary macrophages are still somewhat recalcitrant to transfection. Macrophage-specific synthetic promoters, which were recently used successfully, can have up to 100-fold higher activity than that of native promoters. Adenovirus, lentivirus, and adeno-associated virus are commonly used for macrophage gene therapy. A number of non-viral methods are also popular for the transfer of exogenous DNA into macrophages. Gene transfer to macrophages using naked DNA has also been successful in a few cases. Macrophages have speciﬁc mechanisms to recognize and respond to bacterial DNA because of the presence of unmethylated CpG dinucleotides, which are rare in eukaryotic DNA. With interesting developments in this area, macrophage gene therapy appears to have great potential for immune therapies.

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Xie, Linglin, M. Teresa Ortega, Silvia Mora et Stephen K. Chapes. « Interactive Changes between Macrophages and Adipocytes ». Clinical and Vaccine Immunology 17, n^o 4 (17 février 2010) : 651–59. http://dx.doi.org/10.1128/cvi.00494-09.

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ABSTRACT Obesity is associated with a proinflammatory state, with macrophage infiltration into adipose tissue. We tested the hypothesis that communication between macrophages and adipocytes affects insulin resistance by disrupting insulin-stimulated glucose transport, adipocyte differentiation, and macrophage function. To test this hypothesis, we cocultured 3T3-L1 adipocytes with C2D macrophages or primary peritoneal mouse macrophages and examined the impacts of macrophages and adipocytes on each other. Adipocytes and preadipocytes did not affect C2D macrophage TNF- α, IL-6, or IL-1 β transcript concentrations relative to those obtained when C2D macrophages were incubated alone. However, preadipocytes and adipocytes increased PEC-C2D macrophage IL-6 transcript levels, while preadipocytes inhibited IL-1 β transcript levels compared to those obtained when PEC-C2D macrophages were incubated in medium alone. We found that adipocyte coculture increased macrophage consumption of tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), and, in some cases, IL-6. C2D macrophages increasingly downregulated GLUT4 transcript levels in differentiated adipocytes. Recombinant TNF-α, IL-1β, and IL-6 also downregulated GLUT4 transcript levels relative to those for the control. However, only IL-6 was inhibitory at concentrations detected in macrophage-adipocyte cocultures. IL-6 and TNF-α, but not IL-1β, inhibited Akt phosphorylation within 15 min of insulin stimulation, but only IL-6 was inhibitory 30 min after stimulation. Lastly, we found that adipocyte differentiation was inhibited by macrophages or by recombinant TNF-α, IL-6, and IL-1β, with IL-6 having the most impact. These data suggest that the interaction between macrophages and adipocytes is a complex process, and they support the hypothesis that the macrophage-adipocyte interaction affects insulin resistance by disrupting insulin-stimulated glucose transport, adipocyte differentiation, and macrophage function.

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Knuth, Anne-Kathrin, Arnaud Huard, Zumer Naeem, Peter Rappl, Rebekka Bauer, Ana Carolina Mota, Tobias Schmid et al. « Apoptotic Cells induce Proliferation of Peritoneal Macrophages ». International Journal of Molecular Sciences 22, n^o 5 (24 février 2021) : 2230. http://dx.doi.org/10.3390/ijms22052230.

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The interaction of macrophages with apoptotic cells is required for efficient resolution of inflammation. While apoptotic cell removal prevents inflammation due to secondary necrosis, it also alters the macrophage phenotype to hinder further inflammatory reactions. The interaction between apoptotic cells and macrophages is often studied by chemical or biological induction of apoptosis, which may introduce artifacts by affecting the macrophages as well and/or triggering unrelated signaling pathways. Here, we set up a pure cell death system in which NIH 3T3 cells expressing dimerizable Caspase-8 were co-cultured with peritoneal macrophages in a transwell system. Phenotype changes in macrophages induced by apoptotic cells were evaluated by RNA sequencing, which revealed an unexpectedly dominant impact on macrophage proliferation. This was confirmed in functional assays with primary peritoneal macrophages and IC-21 macrophages. Moreover, inhibition of apoptosis during Zymosan-induced peritonitis in mice decreased mRNA levels of cell cycle mediators in peritoneal macrophages. Proliferation of macrophages in response to apoptotic cells may be important to increase macrophage numbers in order to allow efficient clearance and resolution of inflammation.

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Misharin, Alexander V., Luisa Morales-Nebreda, Paul A. Reyfman, Carla M. Cuda, James M. Walter, Alexandra C. McQuattie-Pimentel, Ching-I. Chen et al. « Monocyte-derived alveolar macrophages drive lung fibrosis and persist in the lung over the life span ». Journal of Experimental Medicine 214, n^o 8 (10 juillet 2017) : 2387–404. http://dx.doi.org/10.1084/jem.20162152.

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Little is known about the relative importance of monocyte and tissue-resident macrophages in the development of lung fibrosis. We show that specific genetic deletion of monocyte-derived alveolar macrophages after their recruitment to the lung ameliorated lung fibrosis, whereas tissue-resident alveolar macrophages did not contribute to fibrosis. Using transcriptomic profiling of flow-sorted cells, we found that monocyte to alveolar macrophage differentiation unfolds continuously over the course of fibrosis and its resolution. During the fibrotic phase, monocyte-derived alveolar macrophages differ significantly from tissue-resident alveolar macrophages in their expression of profibrotic genes. A population of monocyte-derived alveolar macrophages persisted in the lung for one year after the resolution of fibrosis, where they became increasingly similar to tissue-resident alveolar macrophages. Human homologues of profibrotic genes expressed by mouse monocyte-derived alveolar macrophages during fibrosis were up-regulated in human alveolar macrophages from fibrotic compared with normal lungs. Our findings suggest that selectively targeting alveolar macrophage differentiation within the lung may ameliorate fibrosis without the adverse consequences associated with global monocyte or tissue-resident alveolar macrophage depletion.

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Peng, Yuan, Mengxian Zhou, Hong Yang, Ruyi Qu, Yan Qiu, Jiawen Hao, Hongsheng Bi et Dadong Guo. « Regulatory Mechanism of M1/M2 Macrophage Polarization in the Development of Autoimmune Diseases ». Mediators of Inflammation 2023 (8 juin 2023) : 1–20. http://dx.doi.org/10.1155/2023/8821610.

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Macrophages are innate immune cells in the organism and can be found in almost tissues and organs. They are highly plastic and heterogeneous cells and can participate in the immune response, thereby playing a crucial role in maintaining the immune homeostasis of the body. It is well known that undifferentiated macrophages can polarize into classically activated macrophages (M1 macrophages) and alternatively activated macrophages (M2 macrophages) under different microenvironmental conditions. The directions of macrophage polarization can be regulated by a series of factors, including interferon, lipopolysaccharide, interleukin, and noncoding RNAs. To elucidate the role of macrophages in various autoimmune diseases, we searched the literature on macrophages with the PubMed database. Search terms are as follows: macrophages, polarization, signaling pathways, noncoding RNA, inflammation, autoimmune diseases, systemic lupus erythematosus, rheumatoid arthritis, lupus nephritis, Sjogren’s syndrome, Guillain-Barré syndrome, and multiple sclerosis. In the present study, we summarize the role of macrophage polarization in common autoimmune diseases. In addition, we also summarize the features and recent advances with a particular focus on the immunotherapeutic potential of macrophage polarization in autoimmune diseases and the potentially effective therapeutic targets.

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Xu, Rong, Hong-Fan Sun, David W. Williams, Adam V. Jones, Ali Al-Hussaini, Bing Song et Xiao-Qing Wei. « IL-34 SuppressesCandida albicansInduced TNFαProduction in M1 Macrophages by Downregulating Expression of Dectin-1 and TLR2 ». Journal of Immunology Research 2015 (2015) : 1–7. http://dx.doi.org/10.1155/2015/328146.

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Candida albicansis a fungus that is an opportunistic pathogen of humans. Normally,C. albicansexists as a harmless commensal and does not trigger inflammatory responses by resident macrophages in skin mucosa, which may be caused by a tolerance of skin macrophage toC. albicans. IL-34 is a recently discovered cytokine, constitutively expressed by keratinocytes in the skin. IL-34 binds to the receptor of M-CSF, thereby stimulating tissue macrophage maturation and differentiation. Resident macrophages exhibit phenotypic plasticity and may transform into inflammatory M1 macrophages for immunity or anti-inflammatory M2 macrophages for tissue repair. M1 macrophages produce higher levels of inflammatory cytokines such as TNFαin response toC. albicansstimulation. In this study, it was demonstrated that IL-34 attenuated TNFαproduction by M1 macrophages challenged with heat killed Candida (HKC). The molecular mechanism of IL-34 mediated suppression of HKC induced TNFαproduction by M1 macrophages was by the inhibition of M1 macrophage expression of keyC. albicanspattern recognition receptors (PPRs), namely, Toll-like receptor (TLR) 2 and Dectin-1. The results of this study indicated that constitutive IL-34 expressed by skin keratinocytes might suppress resident macrophage responses toC. albicanscolonisation by maintaining low levels TLR2 and Dectin-1 expression by macrophages.

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Tian, Ying, Sheri E. Kelemen et Michael V. Autieri. « Inhibition of AIF-1 expression by constitutive siRNA expression reduces macrophage migration, proliferation, and signal transduction initiated by atherogenic stimuli ». American Journal of Physiology-Cell Physiology 290, n^o 4 (avril 2006) : C1083—C1091. http://dx.doi.org/10.1152/ajpcell.00381.2005.

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Allograft inflammatory factor-1 (AIF-1) is a cytoplasmic, calcium-binding, inflammation-responsive scaffold protein. Several studies have reported increased AIF-1 expression in activated macrophages and have implicated AIF-1 as a marker of activated macrophages. However, the function of AIF-1 in macrophages and the mechanism whereby it participates in macrophage activation are unknown at this time. Immunohistochemical analysis colocalized AIF-1 expression with CD68-positive macrophages in atherosclerotic human coronary arteries. Subsequent experiments were designed to determine a role for AIF-1 in macrophage activation in response to atherogenic stimuli. Stimulation of human and murine macrophages with oxidized LDL significantly increased AIF-1 expression above basal levels. Stable transfection of AIF-1 small interfering RNA (siRNA) in macrophages reduced AIF-1 protein expression by 79% and reduced macrophage proliferation by 52% ( P < 0.01). Inhibition of proliferation was not due to induction of apoptosis. Sequences that did not knock down AIF-1 expression had no effect on proliferation. AIF-1 siRNA expression reduced macrophage migration by 60% ( P < 0.01). Both proliferation and migration of siRNA-expressing macrophages could be restored by adenoviral expression of AIF-1 ( P < 0.001 and 0.005, respectively), suggesting a tight association between AIF-1 expression and macrophage activation. Phosphorylation of Akt, p44/42 MAPK, and p38 kinase were significantly reduced in siRNA macrophages challenged with oxidized LDL ( P < 0.05). Phosphorylation of p38 kinase was significantly inhibited in siRNA macrophages stimulated with T lymphocyte conditioned medium ( P < 0.05). These data indicate that AIF-1 mediates atherogenesis-initiated signaling and activation of macrophages.

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Hamrick, Terri S., Edward A. Havell, John R. Horton et Paul E. Orndorff. « Host and Bacterial Factors Involved in the Innate Ability of Mouse Macrophages To Eliminate Internalized UnopsonizedEscherichia coli ». Infection and Immunity 68, n^o 1 (1 janvier 2000) : 125–32. http://dx.doi.org/10.1128/iai.68.1.125-132.2000.

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ABSTRACT In an effort to better understand genetic and cellular factors that influence innate immunity, we examined host and bacterial factors involved in the nonopsonic phagocytosis and killing ofEscherichia coli K-12 by mouse macrophages. Unelicited (resident) peritoneal macrophages from five different mouse strains, BALB/c, C57BL/6, CD-1, C3H/HeJ, and C3H/HeN, were employed. Additional macrophage populations were obtained from CD-1 mice (bone marrow-derived macrophages). Also, for BALB/c and C57BL/6 mice, peritoneal macrophages elicited with either thioglycolate or proteose peptone, bone marrow-derived macrophages, and macrophage-like cell lines derived from the two strains were employed. Two E. coli K-12 strains that differed specifically in their abilities to produce type 1 pili containing the adhesive protein FimH were examined. The parameters used to assess macrophage bacteriocidal activity were (i) the killing of internalized (gentamicin-protected)E. coli during the approximately 4-h assay and (ii) the initial rate at which internalized E. coli were eliminated. Data on these parameters allowed the following conclusions: (i) unelicited or proteose peptone-elicited peritoneal macrophages were significantly better at eliminating internalized bacteria than thioglycolate-elicited peritoneal macrophages, bone marrow-derived macrophages, or macrophage cell lines; (ii) the host genetic background had no significant effect upon the ability of unelicited peritoneal macrophages to kill E. coli (even though the mouse strains differ widely in their in vivo susceptibilities to bacterial infection); and (iii) the FimH phenotype had no significant effect uponE. coli survival once the bacterium was inside a macrophage. Additionally, there was no correlation between the bacteriocidal effectiveness of a macrophage population and the number of bacteria bound per macrophage. However, macrophage populations that were the least bacteriocidal tended to bind higher ratios of FimH+ to FimH− E. coli. The effect of gamma interferon, fetal calf serum, and the recombination proficiency of E. coli were examined as factors predicted to influence intracellular bacterial killing. These had no effect upon the rate of E. coli elimination by unelicited peritoneal macrophages.

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Bauerle, Kevin Thomas, Jisu Oh, Amy Elizabeth Riek, Adriana Dusso, Anabel L. Castro-Grattoni, R. Ariel Gomez, Maria L. Sequeira-Lopez et Carlos Bernal-Mizrachi. « Vitamin D Deficiency Induces Macrophage Pro-Inflammatory Phenotype via ER Stress-Mediated Activation of Renin-Angiotensin System ». Journal of the Endocrine Society 5, Supplement_1 (1 mai 2021) : A304—A305. http://dx.doi.org/10.1210/jendso/bvab048.620.

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Abstract Chronic inflammation and local activation of the renin-angiotensin-aldosterone system (RAAS) play a pivotal role in the pathogenesis and progression of diabetic complications. In patients with type 2 diabetes (T2DM), the prevalence of vitamin D deficiency is almost twice that of non-diabetics, and vitamin d deficiency nearly doubles the risk of developing hypertension and cardiovascular complications compared to diabetics with normal vitamin D levels. Interestingly, mice lacking the vitamin D receptor (VDR) in macrophages (KODMAC) develop renin-dependent hypertension, insulin resistance, and inflammation via up-regulation of macrophage ER stress. Macrophages also express all major components of the RAAS system. However, little is known about the regulation of macrophage-generated renin and its role in modulating the sequelae of VDR signaling in macrophage function and cytokine production. This study found that KODMAC macrophages and vitamin D-deficient macrophages have increased expression and secretion of renin, angiotensin II, ACE, and AT1 receptor and that adhesion, migration, and cytokine release were also increased. Inhibition of ER stress in KODMAC macrophages and vitamin D-deficient macrophages with 4-Phenylbutyric acid (PBA) reduced RAS gene expression and macrophage pro-inflammatory phenotype. Renin 1c gene deletion decreased macrophage adhesion, migration, and cytokine release compared to macrophages with disrupted VDR signaling. Notably, disruption of VDR signaling induced peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) expression in macrophages, and upregulation of renin expression in response to vitamin D deficiency was blunted in PCG1α-deficient macrophages. In conclusion, our findings delineate a mechanism by which impaired VDR signaling induces ER stress to drive PGC1α-dependent expression of renin and RAAS hyperactivation, thereby altering macrophage function and cytokine production. These data implicate RAAS as an essential mediator of VDR-mediated macrophage function and support ongoing investigations of VDR and RAAS modulation as therapeutic approaches in the management of T2DM and its complications.

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Torre, Donato, Luisa Gennero, F. M. Baccino, Filippo Speranza, Gilberto Biondi et Agostino Pugliese. « Impaired Macrophage Phagocytosis of Apoptotic Neutrophils in Patients with Human Immunodeficiency Virus Type 1 Infection ». Clinical and Vaccine Immunology 9, n^o 5 (septembre 2002) : 983–86. http://dx.doi.org/10.1128/cdli.9.5.983-986.2002.

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ABSTRACT Dysfunction of neutrophils (polymorphonuclear leukocytes [PMNL]) and macrophagic cells occurs as a consequence of human immunodeficiency virus type 1 (HIV-1) infection. Macrophages contribute to the resolution of early inflammation ingesting PMNL apoptotic bodies. This study investigated macrophage ability to phagocytose PMNL apoptotic bodies in patients with HIV-1 infection in comparison with uninfected individuals and the effect of HIV Nef protein on apoptotic body phagocytosis to determine if phagocytic activity is impaired by HIV infection. Monocytes/macrophages were isolated from 10 HIV-1-infected patients and from five healthy volunteers, whereas PMNL were isolated from healthy volunteers. Macrophage phagocytosis of apoptotic PMNL was determined by staining of apoptotic bodies with fluorescein-conjugated concanavalin A or with fluorescein-labeled phalloidin. Our data show significant impairment of PMNL apoptotic body macrophage phagocytosis in subjects with HIV-1 infection presenting a concentration of CD4+ T lymphocytes of >200/mm3 and in particular in those with <200 CD4+ T lymphocyte cells/mm3. In addition, HIV-1 recombinant Nef protein is able to decrease phagocytosis of apoptotic PMNL from normal human macrophages in a dose-dependent manner. The results of our study suggest that impaired macrophage phagocytosis of PMNL apoptotic bodies may contribute to the persistence of the inflammatory state in HIV-infected subjects, especially during opportunistic infections that are often favored by defective phagocytic activity.

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Aziz, Athar, Laurent Vanhille, Peer Mohideen, Louise M. Kelly, Claas Otto, Youssef Bakri, Noushine Mossadegh, Sandrine Sarrazin et Michael H. Sieweke. « Development of Macrophages with Altered Actin Organization in the Absence of MafB ». Molecular and Cellular Biology 26, n^o 18 (15 septembre 2006) : 6808–18. http://dx.doi.org/10.1128/mcb.00245-06.

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ABSTRACT In the hematopoietic system the bZip transcription factor MafB is selectively expressed at high levels in monocytes and macrophages and promotes macrophage differentiation in myeloid progenitors, whereas a dominant-negative allele can inhibit this process. To analyze the requirement of MafB for macrophage development, we generated MafB-deficient mice and, due to their neonatal lethal phenotype, analyzed macrophage differentiation in vitro, in the embryo, and in reconstituted mice. Surprisingly we observed in vitro differentiation of macrophages from E14.5 fetal liver (FL) cells and E18.5 splenocytes. Furthermore we found normal numbers of F4/80+/Mac-1+ macrophages and monocytes in fetal liver, spleen, and blood as well as in bone marrow, spleen, and peritoneum of adult MafB−/− FL reconstituted mice. MafB−/− macrophages showed intact basic macrophage functions such as phagocytosis of latex beads or Listeria monocytogenes and nitric oxide production in response to lipopolysaccharide. By contrast, MafB−/− macrophages expressed increased levels of multiple genes involved in actin organization. Consistent with this, phalloidin staining revealed an altered morphology involving increased numbers of branched protrusions of MafB−/− macrophages in response to macrophage colony-stimulating factor. Together these data point to an unexpected redundancy of MafB function in macrophage differentiation and a previously unknown role in actin-dependent macrophage morphology.

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Hashimoto, Shin-ichi, Takuji Suzuki, Hong-Yan Dong, Nobuyuki Yamazaki et Kouji Matsushima. « Serial Analysis of Gene Expression in Human Monocytes and Macrophages ». Blood 94, n^o 3 (1 août 1999) : 837–44. http://dx.doi.org/10.1182/blood.v94.3.837.413k02_837_844.

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Monocytes/macrophages serve as sentinels involved in chronic inflammation and the eradication of various pathogens. To define molecularly the differentiation of blood monocytes into macrophages, we conducted serial analysis of gene expression (SAGE) in human blood monocytes/macrophages induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) or M-CSF. SAGE analysis of 57,560, 57,463, and 55,856 tags from monocytes, GM-CSF–, and M-CSF–induced macrophages, respectively, allowed identification of 35,037 different transcripts. Interestingly, the genes with the highest expression during differentiation from monocytes into macrophages were genes involved in lipid metabolism. Both CSF-induced macrophages expressed similar sets of genes except for several genes such as monocyte-derived chemokine (MDC), legumain, prostaglandin D synthetase, and lysosomal sialoglycoprotein. The identification of specific gene expression in human monocytes, GM-CSF–, or M-CSF–induced macrophages provides novel methods to define macrophage subsets and the maturation and activation stage of cells of macrophage lineage and, possibly, to diagnose diseases in which macrophages play a major role. This study represents the first extensive serial analysis of gene expression for any type of human hematopoietic cells.

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Martins, Flávia, Rosa Oliveira, Bruno Cavadas, Filipe Pinto, Ana Patrícia Cardoso, Flávia Castro, Bárbara Sousa et al. « Hypoxia and Macrophages Act in Concert Towards a Beneficial Outcome in Colon Cancer ». Cancers 12, n^o 4 (28 mars 2020) : 818. http://dx.doi.org/10.3390/cancers12040818.

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In colon cancer, the prognostic value of macrophages is controversial, and it is still unknown how hypoxia modulates macrophage–cancer cell crosstalk. To unravel this, co-cultures of human primary macrophages and colon cancer cells were performed at 20% and 1% O2, followed by characterization of both cellular components. Different colon cancer patient cohorts were analyzed for hypoxia and immune markers, and their association with patient overall survival was established. A positive correlation between HIF1A and CD68 in colon cancer patients was identified but, unexpectedly, in cases with higher macrophage infiltration, HIF1A expression was associated with a better prognosis, in contrast to breast, gastric, and lung cancers. Under hypoxia, co-cultures’ secretome indicated a shift towards a pro-inflammatory phenotype. These alterations occurred along with increased macrophage phagocytic activity and decreased SIRPα expression. Cancer cells were more invasive and exhibited higher CD47 expression. We hypothesize that the better prognosis associated with HIF1AHighCD68High tumors could occur due to macrophagic pro-inflammatory pressure. Indeed, we found that tumors HIF1AHighCD68High expressed increased levels of CD8A, which is positively correlated with HIF1A. In conclusion, we show that in colon cancer, hypoxia drives macrophages into a pro-inflammatory phenotype, concomitant with increased infiltration of anti-tumor immune cells, favoring better disease outcome.

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Cummings, Thomas J., Christine M. Hulette, Sandra H. Bigner, Gregory J. Riggins et Roger E. McLendon. « HAM56-Immunoreactive Macrophages in Untreated Infiltrating Gliomas ». Archives of Pathology & ; Laboratory Medicine 125, n^o 5 (1 mai 2001) : 637–41. http://dx.doi.org/10.5858/2001-125-0637-himiui.

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Abstract Context.—Classic diagnostic neuropathologic teachings have cautioned against making the diagnosis of neoplasia in the presence of a macrophage population. The knowledge of macrophage distribution should prove useful when confronted with an infiltrating glioma containing macrophages. Objective.—To identify macrophages in untreated, infiltrating gliomas using the monoclonal antibody HAM56, and to confirm their presence in an untreated glioblastoma multiforme (GBM) with the serial analysis of gene expression (SAGE) method. Methods.—We evaluated the presence of macrophages in 16 cases of untreated, supratentorial infiltrating gliomas with the macrophage monoclonal antibody HAM56. We performed SAGE for one case of GBM and for normal brain tissue. Results.—In World Health Organization (WHO) grade II well-differentiated astrocytoma and oligodendroglioma, HAM56 reactivity was noted only in endothelial cells, and unequivocal macrophages were not identified. In WHO grade III anaplastic astrocytoma and anaplastic oligodendroglioma, rare HAM56-positive macrophages were noted in solid areas of tumor. In WHO grade IV GBM, HAM56-positive macrophages were identified in areas of solid tumor (mean labeling index, 8.6%). In all cases of GBM, nonquantitated HAM56-positive macrophages were identified in foci of pseudopalisading cells abutting necrosis and in foci of microvascular proliferations. In none of the cases were granulomas or microglial nodules found, and there was no prior history of surgical intervention, radiation therapy, chemotherapy, or head trauma in these cases. By SAGE, the macrophage-related proteins osteopontin and macrophage-capping protein were overexpressed 12-fold and eightfold, respectively, in one untreated GBM compared with normal brain tissue. In this case, numerous HAM56-positive macrophages (labeling index, 24.5%) were present in the solid portion of tumor, and abundant nonquantified macrophages were identified in foci of pseudopalisading cells abutting necrosis and in foci of microvascular proliferations. Conclusions.—This study confirms the utility of the monoclonal antibody HAM56 in identifying macrophages within untreated infiltrating gliomas. The overexpression of macrophage-related proteins in one case of GBM as detected by SAGE signifies that macrophages may be present in untreated GBMs.

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Luo, Qianting, Xingyang Li, Wenchao Zhong, Wei Cao, Mingjing Zhu, Antong Wu, Wanyi Chen et al. « Dicalcium silicate-induced mitochondrial dysfunction and autophagy-mediated macrophagic inflammation promotes osteogenic differentiation of BMSCs ». Regenerative Biomaterials, 13 décembre 2021. http://dx.doi.org/10.1093/rb/rbab075.

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Abstract Dicalcium silicate (Ca2SiO4, C2S) has osteogenic potential but induces macrophagic inflammation. Mitochondrial function plays a vital role in macrophage polarization and macrophagic inflammation. The mitochondrial function of C2S-treated macrophages is still unclear. This study hypothesized: (1) the C2S modulates mitochondrial function and autophagy in macrophages to regulate macrophagic inflammation, and (2) C2S-induced macrophagic inflammation regulates osteogenesis. We used RAW264.7 cells as a model of macrophage. The C2S (75-150 μg/mL) extract was used to analyze the macrophagic mitochondrial function and macrophage-mediated effect on osteogenic differentiation of mouse bone marrow-derived mesenchymal stem cells (BMSCs). The results showed that C2S extract (150 μg/mL) induced TNF-α, IL-1β, and IL-6 production in macrophages. C2S extract (150 μg/mL) enhanced reactive oxygen species (ROS) level and intracellular calcium level but reduced mitochondrial membrane potential (MtMP) and ATP production. TEM images showed reduced mitochondrial abundance and altered the mitochondrial morphology in C2S (150 μg/mL)-treated macrophages. Protein level expression of PINK1, Parkin, Beclin1, and LC3 was upregulated but TOMM20 was downregulated. mRNA sequencing and KEGG analysis showed that C2S-induced differentially expressed mRNAs in macrophages were mainly distributed in the essential signaling pathways involved in mitochondrial function and autophagy. The conditioned medium from C2S-treated macrophage (C2S-CM) robustly promoted osteogenic differentiation in BMSCs. In conclusion, our results indicate mitochondrial dysfunction and autophagy as the possible mechanism of C2S-induced macrophagic inflammation. The promotion of osteogenic differentiation of BMSCs by the C2S-induced macrophagic inflammation suggests the potential application of C2S in developing immunomodulatory bone grafts.

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Bo, Haotian, Ulrich Aymard Ekomi Moure, Yuanmiao Yang, Jun Pan, Li Li, Miao Wang, Xiaoxue Ke et Hongjuan Cui. « Mycobacterium tuberculosis-macrophage interaction : Molecular updates ». Frontiers in Cellular and Infection Microbiology 13 (3 mars 2023). http://dx.doi.org/10.3389/fcimb.2023.1062963.

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Mycobacterium tuberculosis (Mtb), the causative agent of Tuberculosis (TB), remains a pathogen of great interest on a global scale. This airborne pathogen affects the lungs, where it interacts with macrophages. Acidic pH, oxidative and nitrosative stressors, and food restrictions make the macrophage’s internal milieu unfriendly to foreign bodies. Mtb subverts the host immune system and causes infection due to its genetic arsenal and secreted effector proteins. In vivo and in vitro research have examined Mtb-host macrophage interaction. This interaction is a crucial stage in Mtb infection because lung macrophages are the first immune cells Mtb encounters in the host. This review summarizes Mtb effectors that interact with macrophages. It also examines how macrophages control and eliminate Mtb and how Mtb manipulates macrophage defense mechanisms for its own survival. Understanding these mechanisms is crucial for TB prevention, diagnosis, and treatment.

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Yi, D. ‐Y, Q. ‐Y Xu, Y. He, X. ‐Q Zheng, T. ‐C Yang et Y. Lin. « Treponema pallidum protein Tp47 induced prostaglandin E2 to inhibit the phagocytosis in human macrophages ». Journal of the European Academy of Dermatology and Venereology, 23 janvier 2024. http://dx.doi.org/10.1111/jdv.19809.

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AbstractBackgroundDuring Treponema pallidum (T. pallidum) infection, the host's immune system actively engages in pursuit and elimination of T. pallidum, while T. pallidum skillfully employs various mechanisms to evade immune recognition. Macrophages exhibit incomplete clearance of T. pallidum in vitro and the underlying mechanism of how T. pallidum resists the attack of macrophage remains unclear.ObjectivesTo investigate the effect of T. pallidum membrane protein Tp47 on the phagocytosis of macrophages.MethodsTHP‐1‐derived macrophages were used to investigate the role of Tp47 in the secretion of Prostaglandin E2 (PGE2) in macrophages and the mechanism by which Tp47 induced the production of PGE2, as well as the impact of PGE2 on the macrophage's phagocytosis.ResultsTp47 (1–10 μg/mL) significantly inhibited the phagocytosis of latex beads and T. pallidum in macrophages (p ≤ 0.05). PGE2 production by macrophages could be induced by Tp47, and the phagocytic function of macrophages could be restored using PGE2 antibody. Tp47 produced PGE2 by activating the PERK/NF‐κB/COX‐2 pathway in macrophages. Inhibitors targeting PERK, NF‐κB and COX‐2, respectively, reduced the level of PGE2 and restored the phagocytic function of macrophages.ConclusionTp47‐induced PGE2 production via the PERK/NF‐κB/COX‐2 pathway contributed to macrophage phagocytosis inhibition, which potentially contributes to immune evasion during the T. pallidum infection.

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Muhammad, Sajjad, Shafqat Rasul Chaudhry, Gergana Dobreva, Michael T. Lawton, Mika Niemelä et Daniel Hänggi. « Vascular Macrophages as Therapeutic Targets to Treat Intracranial Aneurysms ». Frontiers in Immunology 12 (8 mars 2021). http://dx.doi.org/10.3389/fimmu.2021.630381.

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Aneurysmal subarachnoid hemorrhage (aSAH) is a highly fatal and morbid type of hemorrhagic strokes. Intracranial aneurysms (ICAs) rupture cause subarachnoid hemorrhage. ICAs formation, growth and rupture involves cellular and molecular inflammation. Macrophages orchestrate inflammation in the wall of ICAs. Macrophages generally polarize either into classical inflammatory (M1) or alternatively-activated anti-inflammatory (M2)-phenotype. Macrophage infiltration and polarization toward M1-phenotype increases the risk of aneurysm rupture. Strategies that deplete, inhibit infiltration, ameliorate macrophage inflammation or polarize to M2-type protect against ICAs rupture. However, clinical translational data is still lacking. This review summarizes the contribution of macrophage led inflammation in the aneurysm wall and discuss pharmacological strategies to modulate the macrophageal response during ICAs formation and rupture.

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Luque-Campos, Noymar, Felipe A. Bustamante-Barrientos, Carolina Pradenas, Cynthia García, María Jesús Araya, Candice Bohaud, Rafael Contreras-López et al. « The Macrophage Response Is Driven by Mesenchymal Stem Cell-Mediated Metabolic Reprogramming ». Frontiers in Immunology 12 (4 juin 2021). http://dx.doi.org/10.3389/fimmu.2021.624746.

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Mesenchymal stem cells (MSCs) are multipotent adult stromal cells widely studied for their regenerative and immunomodulatory properties. They are capable of modulating macrophage plasticity depending on various microenvironmental signals. Current studies have shown that metabolic changes can also affect macrophage fate and function. Indeed, changes in the environment prompt phenotype change. Therefore, in this review, we will discuss how MSCs orchestrate macrophage’s metabolic plasticity and the impact on their function. An improved understanding of the crosstalk between macrophages and MSCs will improve our knowledge of MSC’s therapeutic potential in the context of inflammatory diseases, cancer, and tissue repair processes in which macrophages are pivotal.

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Xiao, Qiuqun, Jinyan Huang, Xing Wang, Zehong Chen, Weiqi Zhang, Fengjiao Liu, Jiejing Li, Zhimou Yang, Jie Zhan et Yanbin Cai. « Supramolecular Peptide Amphiphile Nanospheres Reprogram Tumor‐associated Macrophage to Reshape the Immune Microenvironment for Enhanced Breast Cancer Immunotherapy ». Small, 15 décembre 2023. http://dx.doi.org/10.1002/smll.202307390.

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AbstractTumor immunotherapy has become a research hotspot in cancer treatment, with macrophages playing a crucial role in tumor development. However, the tumor microenvironment restricts macrophage functionality, limiting their therapeutic potential. Therefore, modulating macrophage function and polarization is essential for enhancing tumor immunotherapy outcomes. Here, a supramolecular peptide amphiphile drug‐delivery system (SPADS) is utilized to reprogram macrophages and reshape the tumor immune microenvironment (TIM) for immune‐based therapies. The approach involved designing highly specific SPADS that selectively targets surface receptors of M2‐type macrophages (M2‐Mφ). These targeted peptides induced M2‐Mφ repolarization into M1‐type macrophages by dual inhibition of endoplasmic reticulum and oxidative stresses, resulting in improved macrophagic antitumor activity and immunoregulatory function. Additionally, TIM reshaping disrupted the immune evasion mechanisms employed by tumor cells, leading to increased infiltration, and activation of immune cells. Furthermore, the synergistic effect of macrophage reshaping and anti‐PD‐1 antibody (aPD‐1) therapy significantly improved the immune system's ability to recognize and eliminate tumor cells, thereby enhancing tumor immunotherapy efficacy. SPADS utilization also induced lung metastasis suppression. Overall, this study demonstrates the potential of SPADS to drive macrophage reprogramming and reshape TIM, providing new insights, and directions for developing more effective immunotherapeutic approaches in cancer treatment.

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van Stijn, Caroline M., Jason Kim et Rajendra K. Tangirala. « Abstract 549 : Adiponectin Modulation of Macrophage Inflammatory and Metabolic Properties is Regulated by Macrophage Polarization Status and Adiponectin Receptor Expression ». Arteriosclerosis, Thrombosis, and Vascular Biology 33, suppl_1 (mai 2013). http://dx.doi.org/10.1161/atvb.33.suppl_1.a549.

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Adiponectin, an adipose-derived adipokine, exerts metabolic, anti-inflammatory and anti-atherogenic effects to ameliorate metabolic syndrome, diabetes and cardiovascular disease. Monocytes/macrophages play a crucial pathogenic role in these inflammatory and metabolic disorders. We identified that macrophage polarization profoundly alters their adiponectin receptor expression and functional responses to adiponectin. We addressed the hypothesis that macrophage activation status which affects adiponectin receptor expression leads to differential adiponectin-mediated inflammatory and metabolic response. Mouse bone marrow macrophages, differentiated into either classically-activated (IFN-γ and LPS) macrophages (M1) or alternatively-activated (IL-10) macrophages (M2), were treated with adiponectin. Our studies revealed that M1 activation substantially suppressed while M2 activation had only a modest effect on the macrophage adiponectin receptor expression. The macrophage activation status also produced contrasting adiponectin effects. Adiponectin significantly increased TNF-α expression in M1 macrophages but had no effect M2 macrophages. In contrast, adiponectin significantly increased anti-inflammatory cytokine, IL-10 in M2 macrophages but had no effect in M1 macrophages. We investigated the adiponectin effect on genes regulating macrophage cholesterol efflux, fatty acid and cholesterol metabolism. Interestingly, adiponectin increased CD36 expression in M1 macrophages but not in M2 macrophages. Similarly, adiponectin increased cholesterol efflux receptor, ABCA1 only in M1 macrophages with no effect in M2 macrophages. Measurement of metabolic gene expression revealed that adiponectin induced HMGCoA reductase levels in M1 macrophages and this effect was absent in M2 macrophages. FAS expression was unaffected by adiponectin in M1 or M2 macrophages. In conclusion, these studies provide important evidence that adiponectin modulation of macrophage inflammatory and atherogenic properties is differentially controlled by macrophage activation status which profoundly affects their pathogenic role in inflammatory and metabolic cardiovascular disease.

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Heaster, Tiffany M., Alexa R. Heaton, Paul M. Sondel et Melissa C. Skala. « Intravital Metabolic Autofluorescence Imaging Captures Macrophage Heterogeneity Across Normal and Cancerous Tissue ». Frontiers in Bioengineering and Biotechnology 9 (20 avril 2021). http://dx.doi.org/10.3389/fbioe.2021.644648.

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Macrophages are dynamic immune cells that govern both normal tissue function and disease progression. However, standard methods to measure heterogeneity in macrophage function within tissues require tissue excision and fixation, which limits our understanding of diverse macrophage function in vivo. Two-photon microscopy of the endogenous metabolic co-enzymes NAD(P)H and flavin adenine dinucleotide (FAD) (metabolic autofluorescence imaging) enables dynamic imaging of mouse models in vivo. Here, we demonstrate metabolic autofluorescence imaging to assess cell-level macrophage heterogeneity in response to normal and cancerous tissue microenvironments in vivo. NAD(P)H and FAD fluorescence intensities and lifetimes were measured for both tissue-resident macrophages in mouse ear dermis and tumor-associated macrophages in pancreatic flank tumors. Metabolic and spatial organization of macrophages were determined by performing metabolic autofluorescence imaging and single macrophage segmentation in mice engineered for macrophage-specific fluorescent protein expression. Tumor-associated macrophages exhibited decreased optical redox ratio [NAD(P)H divided by FAD intensity] compared to dermal macrophages, indicating that tumor-associated macrophages are more oxidized than dermal macrophages. The mean fluorescence lifetimes of NAD(P)H and FAD were longer in dermal macrophages than in tumor-associated macrophages, which reflects changes in NAD(P)H and FAD protein-binding activities. Dermal macrophages had greater heterogeneity in optical redox ratio, NAD(P)H mean lifetime, and FAD mean lifetime compared to tumor-associated macrophages. Similarly, standard markers of macrophage phenotype (CD206 and CD86) assessed by immunofluorescence revealed greater heterogeneity in dermal macrophages compared to tumor-associated macrophages. Ultimately, metabolic autofluorescence imaging provides a novel tool to assess tissue-specific macrophage behavior and cell-level heterogeneity in vivo in animal models.

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