Academic literature on the topic 'PAMPs and DAMP'

Abstract Peptidoglycan (PG) derived commonly from Gram-positive bacteria, is one of pathogen-associated molecular pattern (PAMP). Incubating hemocytes of shrimp in PG caused degranulation, changes in cell size, reduction in the percentage of cell viability, necrosis of hemocytes, and released intracellular molecules containing damage-associated molecular pattern (DAMP) that is well known in mammals and teleosts. Incubating shrimp hemocytes in PAMP, DAMP or the mixture of PAMPs plus DAMPs all induced significant increases in phenoloxidase (PO) activity and respiratory burst (RB, release of superoxide anion) in vitro. The PO activity and RB induced by the mixture of DAMP-PAMP were much greater than that induced by DAMP alone or PAMP alone. In conclusion, the mixture of DAMP-PAMP cause enhancement in eliciting innate immunity of shrimp. This is the first study to confirm that cell necrosis caused by PAMPs releases intracellular molecules, DAMPs, and the mixture of DAMP-PAMP elicit the innate immunity in an invertebrate.

AbstractDamage-associated molecular patterns (DAMPs) are danger signals (or alarmins) alerting immune cells through pattern recognition receptors (PRRs) to begin defense activity. Moreover, DAMPs are host biomolecules that can initiate a noninflammatory response to infection, and pathogen-associated molecular pattern (PAMPs) perpetuate the inflammatory response to infection. Many DAMPs are proteins that have defined intracellular functions and are released from dying cells after tissue injury or chemo-/radiotherapy. In the tumor microenvironment, DAMPs can be ligands for Toll-like receptors (TLRs) expressed on immune cells and induce cytokine production and T-cell activation. Moreover, DAMPs released from tumor cells can directly activate tumor-expressed TLRs that induce chemoresistance, migration, invasion, and metastasis. Furthermore, DAMP-induced chronic inflammation in the tumor microenvironment causes an increase in immunosuppressive populations, such as M2 macrophages, myeloid-derived suppressor cells (MDSCs), and regulatory T cells (Tregs). Therefore, regulation of DAMP proteins can reduce excessive inflammation to create an immunogenic tumor microenvironment. Here, we review tumor-derived DAMP proteins as ligands of TLRs and discuss their association with immune cells, tumors, and the composition of the tumor microenvironment.

Abstract Pathogen-associated molecular patterns (PAMPs) have the capacity to couple inflammatory gene expression to changes in macrophage metabolism, both of which influence subsequent inflammatory activities. Similar to their microbial counterparts, several self-encoded damage-associated molecular patterns (DAMPs) induce inflammatory gene expression. However, whether this symmetry in host responses between PAMPs and DAMPs extends to metabolic shifts is unclear. Here we report that the self-encoded oxidized phospholipid oxPAPC alters the metabolism of macrophages exposed to lipopolysaccharide (LPS). While cells activated by LPS rely exclusively on glycolysis, macrophages exposed to oxPAPC also use mitochondrial respiration, feed the Krebs cycle with glutamine and favor the accumulation of oxaloacetate in the cytoplasm: this metabolite potentiates IL-1beta production, resulting in hyperinflammation. Similar metabolic adaptions occur in vivo in hypercholesterolemic mice and human subjects. Drugs that interfere with oxPAPC-driven metabolic changes reduce atherosclerotic plaque formation in mice, thereby underscoring the importance of DAMP-mediated activities in pathophysiological conditions.

High mobility group box 1 protein (HMGB1), a highly conserved nuclear DNA-binding protein, is a “damage-associated molecular pattern” molecule (DAMP) implicated in both stimulating and inhibiting innate immunity. As reviewed here, HMGB1 is an oxidation-reduction sensitive DAMP bearing three cysteines, and the post-translational modification of these residues establishes its proinflammatory and anti-inflammatory activities by binding to different extracellular cell surface receptors. The redox-sensitive signaling mechanisms of HMGB1 also occupy an important niche in innate immunity because HMGB1 may carry other DAMPs and pathogen-associated molecular pattern molecules (PAMPs). HMGB1 with DAMP/PAMP cofactors bind to the receptor for advanced glycation end products (RAGE) which internalizes the HMGB1 complexes by endocytosis for incorporation in lysosomal compartments. Intra-lysosomal HMGB1 disrupts lysosomal membranes thereby releasing the HMGB1-transported molecules to stimulate cytosolic sensors that mediate inflammation. This HMGB1-DAMP/PAMP cofactor pathway slowed the development of HMGB1-binding antagonists for diagnostic or therapeutic use. However, recent discoveries that HMGB1 released from neurons mediates inflammation via the TLR4 receptor system, and that cancer cells express fully oxidized HMGB1 as an immunosuppressive mechanism, offer new paths to targeting HMGB1 for inflammation, pain, and cancer.

TNIP1 protein is a widely expressed, cytoplasmic inhibitor of inflammatory signaling initiated by membrane receptors such as TLRs which recognize pathogen-associated and damage-associated molecular patterns (PAMPs and DAMPs). Keratinocyte TNIP1 deficiency sensitizes cells to PAMPs and DAMPs promoting hyperresponsive expression and secretion of cytokine markers (e.g., IL-8 and IL-6) relevant to cases of chronic inflammation, like psoriasis, where TNIP1 deficiency has been reported. Here, we examined the impact of TNIP1 deficiency on gene expression and cellular responses (migration and viability) relevant to acute inflammation as typically occurs in wound healing. Using siRNA-mediated TNIP1 expression knockdown in cultured HaCaT keratinocytes, we investigated TNIP1 deficiency effects on signaling downstream of TLR3 agonism with low-concentration poly (I:C), a representative PAMP/DAMP. The combination of TNIP1 knockdown and PAMP/DAMP signaling disrupted expression of specific keratinocyte differentiation markers (e.g., transglutaminase 1 and involucrin). These same conditions promoted synergistically increased expression of wound-associated markers (e.g., S100A8, TGFβ, and CCN2) suggesting potential benefit of increased inflammatory response from reduced TNIP1 protein. Unexpectedly, poly (I:C) challenge of TNIP1-deficient cells restricted reepithelialization and reduced cell viability. In these cells, there was not only increased expression for genes associated with inflammasome assembly (e.g., ASC, procaspase 1) but also for A20, a TNIP1 partner protein that represses cell-death signaling. Despite this possibly compensatory increase in A20 mRNA, there was a decrease in phospho-A20 protein, the form necessary for quenching inflammation. Hyperresponsiveness to poly (I:C) in TNIP1-deficient keratinocytes was in part mediated through p38 and JNK pathways. Taken together, we conclude that TNIP1 deficiency promotes enhanced expression of factors associated with promoting wound healing. However, the coupled, increased potential priming of the inflammasome and reduced compensatory activity of A20 has a net negative effect on overall cell recovery potential manifested by poor reepithelialization and viability. These findings suggest a previously unrecognized role for TNIP1 protein in limiting inflammation during successful progression through early wound healing stages.

The activation of innate immune receptors by pathogen-associated molecular patterns (PAMPs) is central to host defense against infections. On the other hand, these receptors are also activated by immunogenic damage-associated molecular patterns (DAMPs), typically released from dying cells, and the activation can evoke chronic inflammatory or autoimmune disorders. One of the best known receptors involved in the immune pathogenesis is Toll-like receptor 7 (TLR7), which recognizes RNA with single-stranded structure. However, the causative DAMP RNA(s) in the pathogenesis has yet to be identified. Here, we first developed a chemical compound, termed KN69, that suppresses autoimmunity in several established mouse models. A subsequent search for KN69-binding partners led to the identification of U11 small nuclear RNA (U11snRNA) as a candidate DAMP RNA involved in TLR7-induced autoimmunity. We then showed that U11snRNA robustly activated the TLR7 pathway in vitro and induced arthritis disease in vivo. We also found a correlation between high serum level of U11snRNA and autoimmune diseases in human subjects and established mouse models. Finally, by revealing the structural basis for U11snRNA’s ability to activate TLR7, we developed more potent TLR7 agonists and TLR7 antagonists, which may offer new therapeutic approaches for autoimmunity or other immune-driven diseases. Thus, our study has revealed a hitherto unknown immune function of U11snRNA, providing insight into TLR7-mediated autoimmunity and its potential for further therapeutic applications.

In the current concept of bacterial infections, pathogen-associated molecular patterns (PAMPs) derived from pathogens and damage-associated molecular patterns (DAMPs) released from damaged/necrotic host cells are crucial factors in induction of innate immune responses. However, the implication of DAMPs in apical and marginal periodontitis is unknown. Serum amyloid A (SAA) is a DAMP that is involved in the development of various chronic inflammatory diseases, such as rheumatoid arthritis. In the present study, we tested whether SAA is involved in the pathogenesis of periapical lesions, using human periapical surgical specimens and mice deficient in SAA and Toll-like receptors (TLR). SAA1/2 was locally expressed in human periapical lesions at the mRNA and protein levels. The level of SAA protein appeared to be positively associated with the inflammatory status of the lesions. In the development of mouse periapical inflammation, SAA1.1/2.1 was elevated locally and systemically in wild-type (WT) mice. Although SAA1.1/2.1 double-knockout and SAA3 knockout mice had redundant attenuation of the extent of periapical lesions, these animals showed strikingly improved inflammatory cell infiltration versus WT. Recombinant human SAA1 (rhSAA1) directly induced chemotaxis of WT neutrophils in a dose-dependent manner in vitro. In addition, rhSAA1 stimulation significantly prolonged the survival of WT neutrophils as compared with nonstimulated neutrophils. Furthermore, rhSAA1 activated the NF-κB pathway and subsequent IL-1α production in macrophages in a dose-dependent manner. However, TLR2/TLR4 double deficiency substantially diminished these SAA-mediated proinflammatory responses. Taken together, the SAA-TLR axis plays an important role in the chronicity of periapical inflammation via induction of inflammatory cell infiltration and prolonged cell survival. The interactions of PAMPs and DAMPs require further investigation in dental/oral inflammation.

ABSTRACTTrichinella spiralisis a highly destructive parasitic nematode that invades and destroys intestinal epithelial cells, injures many different tissues during its migratory phase, and occupies and transforms myotubes during the final phase of its life cycle. We set out to investigate the role in immunity of innate receptors for potential pathogen- or danger-associated molecular patterns (PAMPs or DAMPs). Focusing on the MyD88-dependent receptors, which include Toll-like receptors (TLRs) and interleukin-1 (IL-1) family members, we found that MyD88-deficient mice expelled worms normally, while TLR2/4-deficient mice showed accelerated worm expulsion, suggesting that MyD88 was active in signaling pathways for more than one receptor during intestinal immunity. A direct role for PAMPs in TLR activation was not supported in a transactivation assay involving a panel of murine and human TLRs. Mice deficient in the IL-1 family receptor for the DAMP, IL-33 (called ST2), displayed reduced intestinal Th2 responses and impaired mast cell activation. IL-33 was constitutively expressed in intestinal epithelial cells, where it became concentrated in nuclei within 2 days of infection. Nuclear localization was an innate response to infection that occurred in intestinal regions where worms were actively migrating. Th2 responses were also compromised in the lymph nodes draining the skeletal muscles of ST2-deficient mice, and this correlated with increased larval burdens in muscle. Our results support a mechanism in which the immune system recognizes and responds to tissue injury in a way that promotes Th2 responses.

Abstract In allogeneic hematopoietic stem cell transplantation (alloHCT), recipient conditioning releases Pathogen- and Damage-Associated Molecular Patterns (PAMPs and DAMPs) that generate pro-inflammatory antigen-presenting cells (APC) that secrete IL-12 to initiate donor Type 1 T helper (Th1) responses causing graft-vs-host-disease (GVHD). Yet, other mechanisms exist to initiate alloimmune responses, as recipients with disrupted APC PAMP/DAMP signaling or lacking IL-12 develop GVHD. We used IL-33 receptor, ST2, deficient B6 mice as T cell donors into BALB/c recipients to test the hypothesis that the DAMP IL-33 bypasses APC and acts directly on donor CD4+ T cells to mediate early alloreactive T cells activation and differentiation. In our model, we transferred equal ratios of B6 Cd4-Cre x St2fl/fl (ST2ko) and Cd4-Cre (ST2wt) T cells into irradiated BALB/c recipients with and without IL-12 blockade. Donor T cells in the secondary lymphoid organs (SLOs) were characterized at days 1–3, 5, and 7 post alloHCT. We established that IL-33 DAMP functions involve the direct stimulation of donor CD4+ T cells, which promoted IL-12-independent Type 1 T helper cell (Th1) differentiation and expansion. We demonstrated that IL-33 is induced by recipient irradiation in PDPN+CD31− fibroblastic reticular cells (FRC) of the SLOs as early as 1 day post-radiation to increase alloreactive CD4+ T cell numbers. Mechanistically, IL-33 amplified CD4+ T cell TCR signaling in response to alloantigen to enhance Th1 cell activation and differentiation, while inhibiting regulatory molecule (i. e. IL-10 and Foxp3) expression. Thus, IL-33 is an unappreciated costimulatory signal in Th1 generation and a promising early target to prevent acute GVHD after alloHCT. Supported by NIH F30AI147437 and T32 CA082084 (GKD), NIH R01HL122489, R01AR073527, R56AI13927 (HRT)

Intradermal infections with C. albicans are eliminated by neutrophils recruited at the site of infection with an unknown mechanism. To dissect how neutrophils are recruited at the site of infection, we analyzed the involvement of PRR that recognize C. albicans (TLR4, TLR2, Dectin1 and Dectin2) as well as CARD9, activated downstream Dectins, and MyD88 that transduces the signal derived from TLRs. WT, PRR-deficient and CARD9-deficient mice did not show any defect in neutrophil recruitment after C. albicans intradermal injection. Diversely, MyD88-deficient mice do not recruit neutrophils after C. albicans skin infection. Since MyD88 is involved in IL-1 signaling, we tested the role of IL-1β and IL-1α, two vasoactive cytokines, in the initiation of inflammation and neutrophil recruitment. In vitro and in vivo studies revealed that both IL-1β and IL-1α were involved in this process. IL-1α is constitutively expressed in epithelial, endothelial and stromal cells and can be released through proteolytic cleavage or cell death, enhancing the production of CXCL1, a chemokine with neutrophil chemoattractant activity. We confirmed that CXCL1 production in vivo depends on IL-1α release. We concluded that PRRs were not involved in the initiation of the inflammatory process during primary Candida skin exposure. Diversely, the initiation of the inflammatory process during primary infection can be due to the unspecific release of alarmins (like IL-1α) by distressed cells, considered like DAMP, stimulating neutrophils recruitment at the site of infection. To investigate whether DAMPs and PAMPs could have distinct roles in neutrophil recruitment during microbial infections, we have used models of skin infection with different types of pathogens: a fungus, C. albicans, a Gram-positive bacterium Staphylococcus aureus and a Gram-negative, Pseudomonas aeruginosa.<br>Intradermal infections with C. albicans are eliminated by neutrophils recruited at the site of infection with an unknown mechanism. To dissect how neutrophils are recruited at the site of infection, we analyzed the involvement of PRR that recognize C. albicans (TLR4, TLR2, Dectin1 and Dectin2) as well as CARD9, activated downstream Dectins, and MyD88 that transduces the signal derived from TLRs. WT, PRR-deficient and CARD9-deficient mice did not show any defect in neutrophil recruitment after C. albicans intradermal injection. Diversely, MyD88-deficient mice do not recruit neutrophils after C. albicans skin infection. Since MyD88 is involved in IL-1 signaling, we tested the role of IL-1β and IL-1α, two vasoactive cytokines, in the initiation of inflammation and neutrophil recruitment. In vitro and in vivo studies revealed that both IL-1β and IL-1α were involved in this process. IL-1α is constitutively expressed in epithelial, endothelial and stromal cells and can be released through proteolytic cleavage or cell death, enhancing the production of CXCL1, a chemokine with neutrophil chemoattractant activity. We confirmed that CXCL1 production in vivo depends on IL-1α release. We concluded that PRRs were not involved in the initiation of the inflammatory process during primary Candida skin exposure. Diversely, the initiation of the inflammatory process during primary infection can be due to the unspecific release of alarmins (like IL-1α) by distressed cells, considered like DAMP, stimulating neutrophils recruitment at the site of infection. To investigate whether DAMPs and PAMPs could have distinct roles in neutrophil recruitment during microbial infections, we have used models of skin infection with different types of pathogens: a fungus, C. albicans, a Gram-positive bacterium Staphylococcus aureus and a Gram-negative, Pseudomonas aeruginosa.

L’inflammation est le mécanisme de base du système immunitaire. Dans le cas de pathologie inflammatoire cette inflammation persiste et devient délétère pour l’organisme. Les causes de cette persistance peuvent être variées. L’une de ces causes est la présence de molécules induisant l’inflammation. Elles peuvent être d’origine exogène comme les PAMP (Pathogen-Associated Molecular Pattern). Ce sont des molécules issues des pathogènes (LPS, peptidoglycanes, ADN CpG) capables d’activer le système immunitaire. Ces molécules peuvent également être d’origine endogène comme les DAMP (Damage Associated Molecular Pattern). Ce sont des molécules libérées par les cellules en état de danger (HMGB1, HSP60) pour prévenir et activer le système immunitaire. La présence de récepteurs (TLR2, TLR4, RAGE) capable de reconnaitre ces PAMP et DAMP est également nécessaire pour pouvoir induire une inflammation. Mes travaux explorent les mécanismes moléculaires et cellulaires des PAMP et des DAMP, dans l’installation et le maintien de l’inflammation dans le cadre des maladies inflammatoires. Pour cela mon étude se focalise sur les mécanismes de reconnaissance et d’induction de l’inflammation par les PAMP et DAMP. Nous avons ainsi mis en évidence certains mécanismes cellulaires et moléculaires dans la réponse inflammatoire liés aux DAMP et PAMP. Nous nous sommes également intéressé aux récepteurs impliqués dans ces différents mécanismes et avons même mis en évidence un potentiel nouveau récepteur CD93. Nous émettons l’hypothèse que CD93 pourrait avoir un rôle dans les pathologies inflammatoires par cette capacité à lier les DAMP et PAMP<br>Inflammation is the basic mechanism of the immune system. In the case of inflammatory pathologies this inflammation persists and becomes deleterious to the organism. Many reasons can explain this persistance. One of these causes is the presence of inflammatory-inducing molecules. They may have exogenous origin such as PAMP (Pathogen Associated Molecular Pattern). They are derived from pathogens (LPS, peptidoglycans, CpG DNA ...), and are able to activate the immune system. These molecules can also have endogenous origin such as the DAMP (Damage Associated Molecular Pattern). They are released by stress cells (HMGB1, HSP60, S100 ...) to prevent and activate the immune system. The presence of receptors (TLR2, TLR4, RAGE ...) capable of recognizing these PAMPs and DAMPs is also necessary in order to elicit inflammation.My work explores the contribution of PAMPs and DAMPs to inflammatory diseases at molecular and cellular levels. To this end, my study focuses on recognition and induction of inflammation by PAMPs and DAMPs.We have thus demonstrated cellular and molecular mechanisms in the inflammatory response related to DAMP and PAMP. We were also interested in the receptors involved in these mechanisms and even showed a new potential receptor. We hypothesize that CD93 may have a role in inflammatory pathologies by his ability to bind DAMPs and PAMPs. Thus CD93, HMGB1, HSP60 and LPS could be potential therapeutic targets concerning inflammatory diseases

L’acné vulgaris est une maladie inflammatoire chronique affectant l’unité pilosébacée. Elle démarre le plus souvent à l’adolescence et résulte en des lésions pouvant être inflammatoires (papules, nodules) ou non inflammatoires (comédons ouverts ou fermés). Cette pathologie a fait l’objet de nombreuses études et quatre facteurs majeurs ont été décrits : une hyperkératinisation, un excès de la production de sébum, la mise en place d’une réponse inflammatoire et la colonisation du follicule pileux par la bactérie Propionibacterium acnes. Ce dernier point est l’un des plus débattu et le rôle de cette bactérie dans la pathologie reste encore mal compris, en particulier son interaction avec le système immunitaire. En effet, cette bactérie supposée commensale est suspectée d’être reconnue comme un pathogène dans le contexte de l’acné. L’objectif principal de mes travaux de thèse était de mieux comprendre le la perception de P.acnes par le système immunitaire. Pour cela nous avons tout d’abord établi une caractérisation phénotypique et fonctionnelle des cellules immunitaires présentes dès les premiers stades de l’apparition de la lésion (microkyste et papule), à partir de biopsies de la peau de patients acnéiques. Nous avons utilisé deux méthodes complémentaires : la cytométrie en flux et la microscopie confocale. Nos résultats indiquent un recrutement important des populations lymphocytaires Th17, des cellules dendritiques conventionnelles de type 2 (cDC2) et des mastocytes, mais également leurs activations à un stade très précoce. Nous avons ensuite observé in vivo la localisation et les interactions de ces populations par microscopie confocale et avons pu mettre en évidence la présence de mastocytes producteurs d’IL-17. Cette étude sur des biopsies de patients nous a permis de montrer l'implication des mastocytes dans l'acné et nous a conduits à étudier in vitro les mécanismes biologiques sous-jacents. Nous avons donc mis en place des modèles basés sur l’isolation et la culture de mastocytes primaires dans le but d’étudier les interactions avec P.acnes et les mécanismes impliqués dans la production d'IL-17 par les mastocytes. Dans un second axe de recherche, nous avons étudié l’impact d’une eau thermale sur des cellules dendritiques humaines. Nos résultats montrent que cette eau thermale réduit l’expression des marqueurs de différenciation et de maturation des cellules dendritiques après qu’elles aient été stimulées. En conclusion, mon travail de thèse nous a permis de découvrir l’implication des mastocytes dans la pathogénèse de l’acné comme source importante d’IL-17 aux stades précoces (microkyste et papule) de la formation de la lésion acnéique<br>Acne vulgaris is a chronic inflammatory disease affecting the pilosebaceous unit. It usually begins in adolescence and results in lesions that can be inflammatory (papules, nodules) or non-inflammatory (open or closed comedones). This condition has been the topic of many studies and four major factors have been described: hyperkeratinization, excessive sebum production, the development of an inflammatory response and colonization of the hair follicle by the bacteria Propionibacterium acnes. This last point is one of the most debated and the role of this bacterium in the pathology is still poorly understood, especially concerning the role played by immune response. Indeed, this supposedly commensal bacterium is suspected of being recognized as a pathogen in the context of acne. The main objective of my thesis work was to better understand the "dialogue" established between the immune system and P.acnes. To do this, we first established a phenotypic and functional characterization of the immune cells present at the early stages of the lesion's development (microcyst and papule), based on skin biopsies of acne patients. We used two different but complementary methods: flow cytometry and confocal microscopy. Our results indicate a significant recruitment of Th17 lymphocyte populations, conventional dendritic cells 2 (cDC2) and mast cells, but also their activation at a very early stage. We then observed in vivo the localization of these cells and their interactions by confocal microscopy. This analysis allowed us to highlight the presence of mast cells producing IL-17. This study on patients’ biopsies revealed the involvement of mast cells in acne and led us to study in vitro the underlying biological mechanisms. We therefore set up models based on primary mast cell isolation and culture to study interactions with P.acnes and the mechanisms involved in the production of IL-17 by mast cells. In a second research axis, we studied the impact of spring thermal water on human dendritic cells. Our results show that this thermal water reduces the expression of markers of differentiation and maturation of dendritic cells after they have been stimulated. In conclusion, my thesis work led to the discovery of mast cells' involvement in acne pathogenesis as an important source of IL-17 in the early stages (microcyst and papule) of acne lesion formation

[French below]TLRs are the sentinels of our cells, they are located at the cell surface and alert the whole immune system of the presence of viruses or bacteria. They detect pathogens by recognizing their molecular patterns; this recognition is specific in order to avoid self-recognition, but they need some degree of promiscuity to remedy to pathogen heterogeneity or mutations. Promiscuity is generally defined as an indiscriminate association with molecules regardless their structure and is the contrary of specificity proper of the classic paradigm of key-lock receptor activation. My thesis results demonstrate that TLR4 and TLR2 are more promiscuous than what was believed and that this promiscuity leads to the recognition of cationic lipids and cardiolipins.Cationic lipids lipopolyamines are synthetic molecules nucleic acid nanocarriers proposed to be used for gene therapy, which consists in replacing a gene that is functioning improperly. This thesis demonstrates that lipopolyamines activate TLR2 by forming conserved and/or alternative H-bonds with TLR residues, simulating the recognition of bacterial lipopeptides and inducing pro-inflammatory cytokines secretion; which is deleterious when we aim to use these nanocarriers in the context of gene therapy. We propose the use of unsaturated cationic lipids to avoid TLR2 recognition. TLR activation could be useful instead to prepare one-component vaccine adjuvants, for which both antigen carrier and TLR activation are needed to turn on the immune system and produce antibodies. The second chapter of this thesis investigates the pro-inflammatory properties of other cationic lipids and describes new lipopolyamines able to activate both TLR2 and TLR4. The study of their adjuvanticity properties showed that they are as efficient as the aluminium salts in stimulating antibodies production.The promiscuity of TLR2 and TLR4 raised questions about the presence of endogenous TLR modulators, often countered by contamination concerns. In the third chapter, we investigate the pro- and anti-inflammatory properties of cardiolipin (CL). CL is a tetra-acylated diphosphatidylglycerol located in the inner mitochondrial membrane. Its fatty acid chain length and degree of unsaturation vary depending on species, tissue and pathological conditions. Here we show that unsaturated cardiolipin acts as a competitive TLR4 antagonist by occupying the binding site of LPS and that unsaturations discriminate between TLR4 antagonistic and agonistic activity. Under physiological conditions, mammalian CL chains are unsaturated, whereas there is an increase of saturated CL in patients affected by the Barth Syndrome. Hence we suggest that unsaturated CL could negatively regulate the inflammation during cell damage or death, via TLR4 inhibition. By contrast, saturated CLs may be involved in the inflammatory state associated with the disease. Finally, our study provides new understandings of the mechanism of TLR4 regulation and extends the library of TLR4 agonists and antagonists to molecules of easier synthesis, lower price and higher biocompatibility compared to LPS-based structures.<br>Resumé en français Les récepteurs Toll-like (TLRs) sont des protéines transmembranaires qui constituent la première barrière de notre système immunitaire inné. Ils détectent la présence de bactéries et virus et alertent l’organisme via la sécrétion de molécules pro-inflammatoires appelés cytokines. Parmi les TLRs, TLR2 and TLR4 reconnaissent respectivement des lipides spécifiques aux bactéries, les lipopeptides et les lipopolysaccharides bactériens LPS. La reconnaissance de motifs moléculaires spécifiques aux pathogènes et absents dans notre organisme est essentiel afin d’éviter une réponse immunitaire venant du soi. Le but de notre thèse était de démontrer que les récepteurs Toll-like possèdent une certaine plasticité et peuvent reconnaître des ligands non identifiés jusqu’ici tels les lipides cationiques et la cardiolipine. Les lipides cationiques sont des molécules synthétiques utilisées comme agents de transfection. Notre travail démontre que les lipides cationiques dont la tête polaire est constituée par des polyamines peuvent mimer les propriétés des ligands naturels et induire la sécrétion de cytokines pro-inflammatoire via l’activation des TLRs. Cette interaction implique des interactions entre la chaine principale de la protéine et les lipides sans intervention des chaines latérales. Cette réaction inflammatoire est contre-indiquée en thérapie génique et nous proposons donc de remplacer les chaines acylées saturées par des chaines insaturées pour la synthèse des nouveaux agents de transfection non-immunogénique. D’autre part, l’activation des TLRs par des agents de transfections active le système immunitaire inné, ce qui permet l’activation du système adaptatif et la production d’anticorps. Nous avons étudié une large gamme des lipides cationiques et identifié des nouveaux activateurs á la fois de TLR2 et de TLR4. L’étude de leurs propriétés adjuvantes a démontré que les lipides cationiques sont des adjuvants comparables aux sels d’aluminium en terme de production d’anticorps. La cardiolipine est un lipide localisé dans la membrane des mitochondries et des bactéries. Le domaine hydrophobe est constitué de quatre chaines acylées qui chez les mammifères sont insaturées. Il a été démontré que la cardiolipine extracellulaire inhibe la sécrétion de cytokines induite par LPS. Notre travail de thèse démontre que cet effet inhibiteur est du à la capacité de la cardiolipine à bloquer le site de liaison du LPS. Le travail démontre aussi que lorsque les chaines acylées sont saturées, c’est le cas dans le Syndrome de Barth, la cardiolipine devient un activateur de TLR4 en interagissant avec TLR4 de façon similaire à LPS. Ce dernier résultat pourrait expliquer l’aspect inflammatoire du Syndrome de Barth et élargie la librairie de ligands de TLR4 á des molécules de structure plus simple et plus aisées à synthétiser que les dérivés de LPS et qui pourraient être utilisés comme adjuvants ou anti-inflammatoires.<br>Doctorat en Sciences<br>info:eu-repo/semantics/nonPublished

Increasing evidence implicates the presence of bacteria in intrauterine tissues as an important risk factor for spontaneous preterm labor. Epigenetic alterations of innate immunity genes may increase the mother’s sensitivity to subclinical levels of bacteria. This study examined the presence of TET2, TLR-2, and TLR-9 in intrauterine tissue, and evaluated whether epigenetic alterations of these genes, as well as IL-8, changed their expression in human decidual tissue and a macrophage cell culture. Immunohistochemicalstaining was used to detect the presence of these proteins in intrauterine tissue. Gene expression changes were evaluated in stimulated monocytes and macrophages. Fluorescence immunohistochemistry was used to track translocation of TET2 in stimulated monocytes and macrophages. Secreted IL-8 concentration was detected with ELISA. Decidual expression of TET2, TLR-2, and TLR-9 increased in the order TNL < TL < sPTL < iPTL. This study found that TET2, TLR-2, TLR-9, and IL-8 are regulated by epigenetic mechanisms. This study was the first to report activation of TET2 involves its translocation from the cytosol to the nucleus in macrophages.

Utilizzando Arabidopsis thaliana come organismo modello ho effettuato studi in vivo per capire quali sono i meccanismi che controllano l'integrita' dell'apparato del Golgi in una prima parte della tesi di dottorato. In una seconda parte ho effettuato degli studi per capire gli eventi di dinamica subcellulare che intervengono nell'immunita' innata delle piante mediati da PAMP (Pathogen-Associated Molecular Patterns) e DAMP (Damage -Associated Molecular Patterns).

Mikroglia sind residente Makrophagen-artige Zellen des Zentralnervensystems (ZNS), die das Gewebe kontinuierlich auf Anzeichen homöostatischer Störungen überwachen. Als die wesentlichen immunkompetenten Effektorzellen im Hirnparenchym exprimieren sie eine Vielzahl von Rezeptoren für pathogen-assoziierte molekulare Strukturmuster (pathogen-associated molecular patterns, PAMPs). Zu diesen Rezeptoren zählt der Toll-like receptor (TLR) 4, der nicht nur Reaktionen der Mikroglia auf bakterielle Infektionen, sondern auch auf Gewebe Schädigungen ermöglicht. Stimulation des TLR4 mit bakteriellem Lipopolysaccharid (LPS) und endogenen schädigung-sassoziierten molekularen Strukturen (damage-associated molecular patterns, DAMPs), die durch Gewebebeeinträchtigung freigesetzt werden, löst sowohl TRIF- als auch MyD88-abhängige Signalkaskaden aus. Die damit induzierte Freisetzung von Zytokinen und Chemokinen rekrutiert und instruiert periphere Immunzellen für eine Protektion und unterstützende Geweberegeneration des ZNS. Wir zeigen hier, dass der TLR4-Korezeptor CD14 ein essenzieller gate keeper für die Generierung von Immunantworten im ZNS ist, die durch LPS oder E. coli-Verabreichung, aber auch durch mechanisches Trauma und ischämischen Schlaganfall ausgelöst werden. In gewissem Gegensatz zu extraneuralen Makrophagen nutzen Mikroglia CD14 zur Erlangung einer extremen Sensitivität gegenüber sehr geringen LPS-Mengen. Gleichzeitig schützt CD14 Mikroglia vor überschießenden Reaktionen auf hohe LPS-Dosen und verhindert dabei insbesondere die exzessive Produktion von CXCL1, eines chemoattraktiven Signals für neutrophile Granulozyten. Entsprechend unterstützt CD14 die ZNS-Rekrutierung von Monozyten und Neutrophilen durch niedrige LPS-Dosen, während es die verstärkte Einwanderung von Neutrophilen durch hohe Dosen von LPS oder E. coli verhindert. Als eine besonders wichtige Funktion beschreiben wir dabei die absolute CD14-Abhängigkeit DAMP-ausgelöster und TLR4-vermittelter Immunreaktionen. CD14-Defizienz (unter cd14-/--Bedingungen) oder CD14 Blockade (durch Antikörper) löschen mikrogliale Reaktionen, die durch Plasma-Fibronektin (als repräsentatives DAMP-Molekül) ausgelöst werden können, komplett aus und beeinträchtigen die Leukozyten-Infiltration nach ZNS-Trauma. Bei einer ischämischen ZNS-Schädigung weisen cd14-/--Mäuse im Gehirn nicht nur weniger Monozyten auf, sondern gleichzeitig ein vergrößertes Infarktvolumen. Wir konnten für Interferon (IFN) b eine Schlüsselfunktion in der CD14-vermittelten Eindämmung der CXCL1-Synthese darstellen, die auf eine negative CD14/TLR4-TRIF-IFNβ-INAR1-Jak- Rückkopplung für MyD88-getriebene Chemokine schließen lässt. Obwohl CD14 somit TLR4-vermittelte Reaktionen auf infektiöse und nicht-infektiöse Agenzien orchestriert, wird seine Expression durch verschiedene TLR-Liganden und Zytokine reguliert. Letztlich unterliegen damit CD14-kontrollierte Funktionen selbst einer komplexen Kontrolle durch ZNS-residente und eingewanderte periphere Zellen. Diese Regulationen können über die Einbeziehung oder den Ausschluss der Kapazitäten des TLR4-Komplexes für eine Schadenserkennung während der ZNS-Reaktionen in unterschiedlichsten pathologischen Szenarien entscheiden.

Le placenta est l’organe central de la grossesse et son bon fonctionnement est essentiel pour mener à une grossesse à terme sans complication. L’inflammation joue un rôle très important dans les différentes étapes de la grossesse, de l’implantation à l’accouchement. Lorsque cette inflammation est débalancée au niveau du placenta, cela peut causer plusieurs altérations de ses fonctions. L’inflammation peut être induite par deux différents stimuli, soient par une intervention externe, donc infectieux (via les Pathogen-Associated Molecular Patterns, PAMPs) ou de façon endogène (via les Damage-Associated Molecular Patterns, DAMPs). L’augmentation de l’inflammation est aussi associée avec les complications de la grossesse, qui touchent 5-12% de toutes les grossesses et qui peuvent mener à des conséquences dévastatrices sur la santé de la mère et du nouveau-né. Ces complications comprennent la prééclampsie (PE), l’accouchement prématuré (AP) et le retard de croissance intra-utérin (RCIU). Malgré que ces pathologies aient des étiologies différentes, elles partagent un facteur commun qui joue un rôle essentiel soit, l’inflammation. Dans le but de mieux comprendre le rôle et les effets de l’inflammation sur le placenta humain et dans les complications de la grossesse, nous avons évalué les effets d’un PAMP (LPS) et d’un DAMP (IL-1) classiques dans un modèle d’explants placentaires humains et nous avons réalisé une étude transcriptomique non biaisée de placentas issus de chaque pathologie. Tout d’abord, nous avons démontré que le LPS induisait une plus grande quantité de cytokines pro-inflammatoire comparativement à l’IL-1 et que l’inhibition de la voie de signalisation de l’IL-1 par son antagoniste (IL-1Ra) diminuait leur expression et leur sécrétion. De plus, le LPS induisait une augmentation de la mort cellulaire dans les explants et la prolifération des cellules de Hofbauer, macrophages placentaires. Par la suite, l’étude du transcriptome de placentas provenant de complications de la grossesse (PE, AP et RCIU) a permis de constater que les pathologies ne forment pas de groupes (clusters) basés sur l’expression globale des gènes comparativement placentas issus de grossesses sans complication qui se regroupaient majoritairement ensemble. Il a été possible d’identifier les gènes significativement différents dans chaque pathologie et l’ontologie génique de ceux-ci. Nous avons identifié 198 gènes communs à toutes les complications de la grossesse qui sont majoritairement associés à des processus inflammatoires tels que l’interaction entre les cellules lymphoïdes et non lymphoïdes, l’activation leucocytaire et la régulation de la production de cytokines. Enfin, en plus de confirmer les modulations connues de certains gènes dans chaque complication de la grossesse, nous avons été en mesure d’identifier de nouveaux gènes qui n’avaient jamais été associés avec les pathologies, tels que FUT9, SLAMF7 et TGM3. En conclusion, les travaux présentés dans cette thèse démontrent que l’inflammation induite par le LPS et l’IL-1 n’a pas les mêmes effets au niveau du placenta. L’inflammation est une composante commune aux différentes complications de la grossesse et une meilleure compréhension des processus inflammatoires modulés dans chaque pathologie pourrait permettre le développement de nouvelles approches thérapeutiques. Des travaux futurs pourraient s’intéresser au potentiel prolifératif des cellules de Hofbauer et à l’investigation des nouveaux gènes identifiés par les résultats transcriptomiques.<br>The placenta is the central organ of pregnancy and its adequate functioning is essential to ensure term delivery without complications. Inflammation plays a key role in every step of pregnancy, from implantation to delivery. When this inflammation is unbalanced in the placenta, it can alter its functions. Inflammation can be induced by two different stimuli, either by external intervention like an infection (with Pathogen-Associated Molecular Patterns, PAMPs), or endogenously (with Damage-Associated Molecular Patterns, DAMPs). Increased inflammation is also associated with pregnancy complications and they affect 5-12% of all pregnancies and can have deleterious effects on maternal and infant health. These complications include preeclampsia (PE), preterm birth (PTB) and intrauterine growth restriction (IUGR). Even if these pathologies have different etiologies, they share a common factor that plays an essential role, inflammation. In order to better understand the role and the effects of inflammation on the human placenta and in pregnancy complications, we have evaluated the effects of classical PAMP (LPS) and DAMP (IL-1) on human placental explant model and we have realized an unbiased transcriptomic study of the placentas from each pregnancy complication. First of all, we demonstrated that LPS induced a higher production of pro-inflammatory cytokines compared to IL-1 and by inhibiting the IL-1 pathway using its antagonist (IL-1Ra), we decreased their expression and their secretion. Moreover, LPS treatment induced more cell death in the explants and proliferation of Hofbauer cells, macrophages of the placenta. Thereafter, transcriptomic study of placentas from pregnancy complications (PE, PTB and IUGR) allowed us to demonstrate that the pathologies were not clustering together based on their global gene expression compared to placentas from uncomplicated pregnancies which the majority of them were clustering together. It was possible to identify genes that were significantly modulated in each pathology and their gene ontology. We identified 198 genes common to all pregnancy complications and they were mostly related to inflammatory processes like interaction between lymphoid and non-lymphoid cells, leukocyte activation and regulation of cytokine production. Finally, in addition to confirming gene modulations previously known in each pregnancy complications, we were able to identify new genes that have never been associated with the pathologies such as FUT9, SLAMF7 and TGM3. To conclude, the work presented in this thesis show that inflammation induced by LPS and IL-1 did not have the same effect on the placenta. Inflammation is a key component to pregnancy complications and a better understanding of the inflammatory processes modulated in every pathology could help the development of new therapeutic strategies. Future work could investigate the proliferative potential of the Hofbauer cells and explore the new genes identified by the transcriptomic results.

Infection continues to be a leading cause of intensive care unit death. The host response to infection can be seen as a pattern recognition receptor (PRR)-mediated dysregulation of the immune system following pathogen invasion in which a careful balance between inflammatory and anti-inflammatory responses is vital. A measured and rapid response to microbial invasion is essential to health. The same immunological and coagulation systems that protect against localized infection can act to our disadvantage when these systems are activated systemically during generalized microbial infection. Toll-like receptors (TLR), the inflammasomes and other PRRs initiate the host response after recognition of pathogen-associated-molecular-patterns (PAMPs) or endogenous danger-associated-molecular-patterns (DAMPs). The systemic host response to infection will result in activation of coagulation, downregulation of physiological anticoagulant mechanisms, and inhibition of fibrinolysis. Further dissection of the role of host–pathogen interactions, the cytokine response, the coagulation cascade and their multidirectional interactions in sepsis should lead towards the development of new therapeutic approaches in the critically ill who are faced with infection.

Covid-19 is the causative agent of a beta coronavirus that causes severe inflammatory pneumonia, so excessive inflammation is considered a risk factor for the disease. In Covid-19 disease, an inflammatory response develops in the body. It has been reported as a result of various studies that this response causes damage to various organs and tissues, especially the lungs. According to reports, cytokine storms are largely responsible for death in such patients. Some of the consequences of severe inflammation and cytokine storms include acute respiratory distress syndrome, acute lung injury, and multiple organ dysfunction syndromes. Many studies are showing that there may be various agents to prevent or treat these effects of Covid-19 disease. Some of these agents are phenolic compounds. Phenolic compounds are the most abundant substances in vegetables and fruits. Inflammasomes, their function. It has been stated that phenolic compounds inhibit inflammation by inhibiting cytosolic multiprotein complexes that assemble in response to cytosolic pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs) to form active forms of IL-1β and IL-18. It suggested that Apigenin, Resveratrol, Morin, and Silymarin an anti-inflammatory, antioxidant, anti-viral, and anti-microbial compound could be a potential therapeutic agent for severe inflammation from Covid-19.

INTRODUÇÃO: O inflamassoma é um complexo multiproteico formado no citosol em resposta aos PAMPs e DAMPs. Sua função é gerar as formas ativas das citocinas IL-1β e IL-18 que, antes de serem liberadas das células, são clivadas pela caspase-1, tornando-se ativas para promoverem a resposta inflamatória. A ativação do inflamassoma tem como consequência a piroptose, uma forma inflamatória de morte celular programada de macrófagos caracterizada pelo inchaço das células, perda da integridade da membrana plasmática e liberação de citocinas pró-inflamatórias (IL-1β, IL-18, TNF-α, IL-6 e IL-8). OBJETIVO: Avaliar o papel do inflamassoma na COVID-19. MATERIAL E MÉTODOS: Para realizar a coleta das informações, foram consideradas publicações no idioma inglês que abordassem o tema “Ativação dos inflamassomas na COVID-19” na plataforma MEDLINE (PubMed). Foram usadas as seguintes palavras-chave: “COVID-19”, “inflammasomes”, “inflammation”, “innate immunity”. RESULTADOS: Os estudos estão em acordo acerca da relação entre a magnitude da ativação do inflamassoma e a COVID-19 grave. Os autores relatam que a defesa inicial inata é importante na resposta dos pacientes contra o SARS-CoV-2. Porém, o encontro de níveis elevados de caspase-1, de IL-1β e de IL-18, estão associados à gravidade da doença e ao desfecho clínico insatisfatório. A piroptose desencadeada pela infecção pelo SARS-CoV-2 e a consequente liberação de LDH e de citocinas pró-inflamatórias, detectados no soro dos pacientes, sugere envolvimento do inflamassoma na tempestade de citocinas. Além disso, pacientes com a forma grave da doença contêm um número maior do inflamassoma de NLRP3, indicando presença de inflamassomas ativos em casos letais de COVID-19. CONCLUSÃO: Os resultados sugerem que os inflamassomas participam da fisiopatologia da COVID-19. No entanto, ainda é necessária a determinação dos mecanismos exatos pelos quais o SARS-CoV-2 aciona o inflamassoma, pois esse complexo multiproteico pode ser um marcador valioso da gravidade da doença e um potencial alvo para estratégias terapêuticas eficazes contra a COVID-19.

Introdução: A doença Parkinsoniana (DP) é uma doença neurodegenerativa, que afeta mais de 1% da população, na idade de 60 anos, em indivíduos com mais de 85 anos, essa prevalência chega a 5%. Além do avanço da idade sobre o risco de desenvolver essa patologia, o gênero, principalmente o masculino, aparece como fator de predisposição para a doença. Na sintomatologia observa-se manifestações tanto motoras/não-motoras que incluem desde tremores, rigidez, dificuldade na execução de movimentos voluntários, a lentificação dos movimentos, instabilidade postural e também sintomas neuropsiquiátricos como a associação de distúrbios do humor e sono, demência, entre outros. Objetivo: Este estudo teve como objetivo correlacionar aspectos imunológicos da patologia da DP. Metodologia: Foi realizada uma revisão bibliográfica obtida por meio de banco de dados PUBMED/SCIELO nos anos de 2014-2021 encontrados nas referidas bases de dados. Resultados: Estudos recentes revelaram que a doença de Parkinson correlaciona fatores imunológicos, sendo fator crucial no risco da enfermidade. O processo imunoinflamatório dessa doença é devido a citocinas/quimicinas pró-inflamatórias, como: TNF, IL-1β, IL-2, I-6, IFN-γ, que estão envolvidos nesse mecanismo, fazendo com que o paciente tenha diminuição de neurônios dopaminérgicos e um aumento da micróglia (células gliais pequenas), até morte celular neuroanal na substância negra, provocando neurodegeneração e inflamação. Essas quimiocinas/citocinas e alguns receptores presentes na resposta imune da DP, é caracterizadamente marcada pela oscilação entre linfócitos T efetores e reguladores, fazendo assim com que o paciente tenha estado inflamatório da doença e sua progressão. Os PAMPs e/ou DAMPs são mediadores pró e anti-inflamatório, então quando ocorre um desequilíbrio, pode desencadear um processo inflamatório crônico. Drogas que agem sobre os TLR (TOLL-LIKE), é utilizada para o tratamento de esclerose e foco principal na fiscalização da dor, tem alvo terapêutico contra essa neuroinflamação que objetiva diminuir a ativação das células gliais, junto a isso, diminuir também a neuroinflamação. Conclusão: Em suma, os artigos pesquisados correlacionou aspectos imunológicos, onde mediadores inflamatótios foram identificados pacientes com altos níveis de citocinas e quimiocinas pró-inflamatórias no desenvolvimento da DP. Foi discutido também sobre a TLR que tem como objetivo fazer com que as células gliais e a neuroinflamacao sejam diminuídas.