To see the other types of publications on this topic, follow the link: Microglie – Physiologie.
Journal articles on the topic 'Microglie – Physiologie'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Microglie – Physiologie.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Lyons, Susan A., Andrea Pastor, Carsten Ohlemeyer, Oliver Kann, Frank Wiegand, Konstantin Prass, Felix Knapp, Helmut Kettenmann, and Ulrich Dirnagl. "Distinct Physiologic Properties of Microglia and Blood-Borne Cells in Rat Brain Slices After Permanent Middle Cerebral Artery Occlusion." Journal of Cerebral Blood Flow & Metabolism 20, no. 11 (November 2000): 1537–49. http://dx.doi.org/10.1097/00004647-200011000-00003.
Full textAbstract:
The authors investigated the time course of leukocyte infiltration compared with microglial activation in adult rat brain slices after permanent middle cerebral artery occlusion (MCAO). To distinguish peripheral leukocytes from microglia, the blood cells were prelabeled in vivo with Rhodamine 6G (Rhod6G) IV before induction of ischemia. At specific times after infarct, invading leukocytes, microglia, and endothelial cells were labeled in situ with isolectin (IL)B4-FITC (ILB4). Six hours after MCAO only a few of the ILB4+ cells were colabeled by Rhod6G. These cells expressed the voltage-gated inwardly and outwardly rectifying K+ currents characteristic of macrophages. The majority of the ILB4+ cells were Rhod6G− and expressed a lack of voltage-gated channels, recently described for ramified microglial cells in brain slices, or exhibited only an inward rectifier current, a unique marker for cultured (but unstimulated) microglia. Forty-eight hours after MCAO, all blood-borne and the majority of Rhod6G− cells expressed outward and inward currents indicating that the intrinsic microglial population exhibited physiologic features of stimulated, cultured microglia. The ILB4+/Rhod6G− intrinsic microglial population was more abundant in the border zone of the infarct and their morphology changed from radial to ameboid. Within this zone, the authors observed rapidly migrating cells and recorded this movement by time-lapse microscopy. The current findings indicate that microglial cells acquire physiologic features of leukocytes at a later time point after MCAO.
2
Eyo, Ukpong B., and Long-Jun Wu. "Bidirectional Microglia-Neuron Communication in the Healthy Brain." Neural Plasticity 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/456857.
Full textAbstract:
Unlike other resident neural cells that are of neuroectodermal origin, microglia are resident neural cells of mesodermal origin. Traditionally recognized for their immune functions during disease, new roles are being attributed to these cells in the development and maintenance of the central nervous system (CNS) including specific communication with neurons. In this review, we highlight some of the recent findings on the bidirectional interaction between neurons and microglia. We discuss these interactions along two lines. First, we review data that suggest that microglial activity is modulated by neuronal signals, focusing on evidence that (i) neurons are capable of regulating microglial activation state and influence basal microglial activities; (ii) classic neurotransmitters affect microglial behavior; (iii) chemotactic signals attract microglia during acute neuronal injury. Next, we discuss some of the recent data on how microglia signal to neurons. Signaling mechanisms include (i) direct physical contact of microglial processes with neuronal elements; (ii) microglial regulation of neuronal synapse and circuit by fractalkine, complement, and DAP12 signaling. In addition, we discuss the use of microglial depletion strategies in studying the role of microglia in neuronal development and synaptic physiology. Deciphering the mechanisms of bidirectional microglial-neuronal communication provides novel insights in understanding microglial function in both the healthy and diseased brain.
3
Wong, Wai T., Minhua Wang, and Wei Li. "Regulation of microglia by ionotropic glutamatergic and GABAergic neurotransmission." Neuron Glia Biology 7, no. 1 (February 2011): 41–46. http://dx.doi.org/10.1017/s1740925x11000123.
Full textAbstract:
Recent studies have indicated that constitutive functions of microglia in the healthy adult central nervous system (CNS) involve immune surveillance, synapse maintenance and trophic support. These functions have been related to the ramified structure of ‘resting’ microglia and the prominent motility in their processes that provide extensive coverage of the entire extracellular milleu. In this review, we examine how external signals, and in particular, ionotropic neurotransmission, regulate features of microglial morphology and process motility. Current findings indicate that microglial physiology in the healthy CNS is constitutively and reciprocally regulated by endogenous ionotropic glutamatergic and GABAergic neurotransmission. These influences do not act directly on microglial cells but indirectly via the activity-dependent release of ATP, likely through a mechanism involving pannexin channels. Microglia in the ‘resting’ state are not only dynamically active, but also constantly engaged in ongoing communication with neuronal and macroglial components of the CNS in a functionally relevant way.
4
Peggion, Caterina, Roberto Stella, Paolo Lorenzon, Enzo Spisni, Alessandro Bertoli, and Maria Lina Massimino. "Microglia in Prion Diseases: Angels or Demons?" International Journal of Molecular Sciences 21, no. 20 (October 20, 2020): 7765. http://dx.doi.org/10.3390/ijms21207765.
Full textAbstract:
Prion diseases are rare transmissible neurodegenerative disorders caused by the accumulation of a misfolded isoform (PrPSc) of the cellular prion protein (PrPC) in the central nervous system (CNS). Neuropathological hallmarks of prion diseases are neuronal loss, astrogliosis, and enhanced microglial proliferation and activation. As immune cells of the CNS, microglia participate both in the maintenance of the normal brain physiology and in driving the neuroinflammatory response to acute or chronic (e.g., neurodegenerative disorders) insults. Microglia involvement in prion diseases, however, is far from being clearly understood. During this review, we summarize and discuss controversial findings, both in patient and animal models, suggesting a neuroprotective role of microglia in prion disease pathogenesis and progression, or—conversely—a microglia-mediated exacerbation of neurotoxicity in later stages of disease. We also will consider the active participation of PrPC in microglial functions, by discussing previous reports, but also by presenting unpublished results that support a role for PrPC in cytokine secretion by activated primary microglia.
5
Abdul, Yasir, Sarah Jamil, Lianying He, Weiguo Li, and Adviye Ergul. "Endothelin-1 (ET-1) promotes a proinflammatory microglia phenotype in diabetic conditions." Canadian Journal of Physiology and Pharmacology 98, no. 9 (September 2020): 596–603. http://dx.doi.org/10.1139/cjpp-2019-0679.
Full textAbstract:
Diabetes increases the risk and severity of cognitive impairment, especially after ischemic stroke. It is also known that the activation of the endothelin (ET) system is associated with cognitive impairment and microglia around the periinfarct area produce ET-1. However, little is known about the effect of ET-1 on microglial polarization, especially under diabetic conditions. We hypothesized that (i) ET-1 activates microglia to the proinflammatory M-1-like phenotype and (ii) hypoxia/ lipopolysaccharide (LPS) activates the microglial ET system and promotes microglial activation towards the M-1 phenotype in diabetic conditions. Microglial cells (C8B4) cultured under normal-glucose (25 mmol/L) conditions and diabetes-mimicking high-glucose (50 mmol/L) conditions for 48 h were stimulated with ET-1, cobalt chloride (200 μmol/L), or LPS (100 ng/mL) for 24 h. PPET-1, ET receptor subtypes, and M1/M2 marker gene mRNA expression were measured by RT-PCR. Secreted ET-1 was measured by ELISA. A high dose of ET-1 (1 μmol/L) increases the mRNA levels of ET receptors and activates the microglia towards the M1 phenotype. Hypoxia or LPS activates the ET system in microglial cells and shifts the microglia towards the M1 phenotype in diabetic conditions. These in vitro observations warrant further investigation into the role of ET-1-mediated activation of proinflammatory microglia in post-stroke cognitive impairment in diabetes.
6
Eder, Claudia. "Ion channels in microglia (brain macrophages)." American Journal of Physiology-Cell Physiology 275, no. 2 (August 1, 1998): C327—C342. http://dx.doi.org/10.1152/ajpcell.1998.275.2.c327.
Full textAbstract:
Microglia are immunocompetent cells in the brain that have many similarities with macrophages of peripheral tissues. In normal adult brain, microglial cells are in a resting state, but they become activated during inflammation of the central nervous system, after neuronal injury, and in several neurological diseases. Patch-clamp studies of microglial cells in cell culture and in tissue slices demonstrate that microglia express a wide variety of ion channels. Six different types of K+ channels have been identified in microglia, namely, inward rectifier, delayed rectifier, HERG-like, G protein-activated, as well as voltage-dependent and voltage-independent Ca2+-activated K+ channels. Moreover, microglia express H+ channels, Na+ channels, voltage-gated Ca2+ channels, Ca2+-release activated Ca2+ channels, and voltage-dependent and voltage-independent Cl− channels. With respect to their kinetic and pharmacological properties, most microglial ion channels closely resemble ion channels characterized in other macrophage preparations. Expression patterns of ion channels in microglia depend on the functional state of the cells. Microglial ion channels can be modulated by exposure to lipopolysaccharide or various cytokines, by activation of protein kinase C or G proteins, by factors released from astrocytes, by changes in the concentration of internal free Ca2+, and by variations of the internal or external pH. There is evidence suggesting that ion channels in microglia are involved in maintaining the membrane potential and are also involved in proliferation, ramification, and the respiratory burst. Further possible functional roles of microglial ion channels are discussed.
7
Zhang, Xiang, Yiming Wang, Hongquan Dong, Ying Xu, and Shu Zhang. "Induction of Microglial Activation by Mediators Released from Mast Cells." Cellular Physiology and Biochemistry 38, no. 4 (2016): 1520–31. http://dx.doi.org/10.1159/000443093.
Full textAbstract:
Background/Aims: Microglia are the resident immune cells in the brain and play a pivotal role in immune surveillance in the central nervous system (CNS). Brain mast cells are activated in CNS disorders and induce the release of several mediators. Thus, brain mast cells, rather than microglia, are the “first responders” due to injury. However, the functional aspects of mast cell-microglia interactions remain uninvestigated. Methods: Conditioned medium from activated HMC-1 cells induces microglial activation similar to co-culture of microglia with HMC-1 cells. Primary cultured microglia were examined by flow cytometry analysis and confocal microscopy. TNF- alpha and IL-6 were measured with commercial ELISA kits. Cell signalling was analysed by Western blotting. Results: In the present study, we found that the conditioned medium from activated HMC-1 cells stimulated microglial activation and the subsequent production of the pro-inflammatory factors TNF-α and IL-6. Co-culture of microglia and HMC-1 cells with corticotropin-releasing hormone (CRH) for 24, 48 and 72 hours increased TNF-α and IL-6 production. Antagonists of histamine receptor 1 (H1R), H4R, proteinase-activated receptor 2 (PAR2) or Toll-like receptor 4 (TLR4) reduced HMC-1-induced pro-inflammatory factor production and MAPK and PI3K/AKT pathway activation. Conclusions: These results imply that activated mast cells trigger microglial activation. Interactions between mast cells and microglia could constitute a new and unique therapeutic target for CNS inflammation-related diseases.
8
Lopez-Lopez, Andrea, Begoña Villar-Cheda, Aloia Quijano, Pablo Garrido-Gil, María Garcia-Garrote, Carmen Díaz-Ruiz, Ana Muñoz, and José L. Labandeira-Garcia. "NADPH-Oxidase, Rho-Kinase and Autophagy Mediate the (Pro)renin-Induced Pro-Inflammatory Microglial Response and Enhancement of Dopaminergic Neuron Death." Antioxidants 10, no. 9 (August 25, 2021): 1340. http://dx.doi.org/10.3390/antiox10091340.
Full textAbstract:
Dysregulation of the tissue renin–angiotensin system (RAS) is involved in tissue oxidative and inflammatory responses. Among RAS components, renin, its precursor (pro)renin and its specific receptor (PRR) have been less investigated, particularly in the brain. We previously showed the presence of PRR in neurons and glial cells in the nigrostriatal system of rodents and primates, including humans. Now, we used rat and mouse models and cultures of BV2 and primary microglial cells to study the role of PRR in microglial pro-inflammatory responses. PRR was upregulated in the nigral region, particularly in microglia during the neuroinflammatory response. In the presence of the angiotensin type-1 receptor blocker losartan, to exclude angiotensin-related effects, treatment of microglial cells with (pro)renin induces the expression of microglial pro-inflammatory markers, which is mediated by upregulation of NADPH-oxidase and Rho-kinase activities, downregulation of autophagy and upregulation of inflammasome activity. Conditioned medium from (pro)renin-treated microglia increased dopaminergic cell death relative to medium from non-treated microglia. However, these effects were blocked by pre-treatment of microglia with the Rho-kinase inhibitor fasudil. Activation of microglial PRR enhances the microglial pro-inflammatory response and deleterious effects of microglia on dopaminergic cells, and microglial NADPH-oxidase, Rho-Kinase and autophagy are involved in this process.
9
He, Mingfeng, Hongquan Dong, Yahui Huang, Shunmei Lu, Shu Zhang, Yanning Qian, and Wenjie Jin. "Astrocyte-Derived CCL2 is Associated with M1 Activation and Recruitment of Cultured Microglial Cells." Cellular Physiology and Biochemistry 38, no. 3 (2016): 859–70. http://dx.doi.org/10.1159/000443040.
Full textAbstract:
Background/Aims: Microglia are an essential player in central nervous system inflammation. Recent studies have demonstrated that the astrocytic chemokine, CCL2, is associated with microglial activation in vivo. However, CCL2-induced microglial activation has not yet been studied in vitro. The purpose of the current study was to understand the role of astrocyte-derived CCL2 in microglial activation and to elucidate the underlying mechanism(s). Methods: Primary astrocytes were pre-treated with CCL2 siRNA and stimulated with TNF-α. The culture medium (CM) was collected and added to cultures of microglia, which were incubated with and without CCR2 inhibitor. Microglial cells were analyzed by quantitative RT-PCR to determine whether they polarized to the M1 or M2 state. Microglial migratory ability was assessed by transwell migration assay. Results: TNF-α stimulated the release of CCL2 from astrocytes, even if the culture media containing TNF-α was replaced with fresh media after 3 h. CM from TNF-α-stimulated astrocytes successfully induced microglial activation, which was ascertained by increased activation of M1 and enhanced migration ability. In contrast, CM from astrocytes pretreated with CCL2 siRNA showed no effect on microglial activation, compared to controls. Additionally, microglia pre-treated with RS102895, a CCR2 inhibitor, were resistant to activation by CM from TNF-α-stimulated astrocytes. Conclusion: This study demonstrates that the CCL2/CCR2 pathway of astrocyte-induced microglial activation is associated with M1 polarization and enhanced migration ability, indicating that this pathway could be a useful target to ameliorate inflammation in the central nervous system.
10
Lai, Aaron Y., and Kathryn G. Todd. "Microglia in cerebral ischemia: molecular actions and interactionsThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigator's Forum." Canadian Journal of Physiology and Pharmacology 84, no. 1 (January 2006): 49–59. http://dx.doi.org/10.1139/y05-143.
Full textAbstract:
The precise role of microglia in stroke and cerebral ischemia has been the subject of debate for a number of years. Microglia are capable of synthesizing numerous soluble and membrane-bound biomolecules, some known to be neuroprotective, some neurotoxic, whereas others have less definitive bioactivities. The molecular mechanisms through which microglia activate these molecules have thus become an important area of ischemia research. Here we provide a survey review that summarizes the key actions of microglial factors in cerebral ischemia including complement proteins, chemokines, pro-inflammatory cytokines, neurotrophic factors, hormones, and proteinases, as well several important messenger molecules that play a part in how these factors respond to extracellular signals during ischemic injuries. We also provide some new perspectives on how microglial intracellular signaling may contribute to the seemingly contradictory roles of several microglial effector molecules.
11
Zhang, Yu, Weida Gao, Kongbin Yang, Haiquan Tao, and Haicheng Yang. "Salt-Inducible Kinase 1 (SIK1) is Induced by Alcohol and Suppresses Microglia Inflammation via NF-κB Signaling." Cellular Physiology and Biochemistry 47, no. 4 (2018): 1411–21. http://dx.doi.org/10.1159/000490831.
Full textAbstract:
Background/Aims: Alcohol consumption has been shown to cause neuroinflammation and increase a variety of immune-related signaling processes. Microglia are a crucial part of alcohol-induced neuroinflammation and undergo apoptosis. Even though the importance of these inflammatory processes in the effects of alcohol-related neurodegeneration have been established, the mechanism of alcohol-induced microglia apoptosis is unknown. In prior research, we discovered that alcohol increases expression of salt-inducible kinase 1 (SIK1) in rodent brain tissue. In this study, we sought to determine what role SIK1 expression plays in alcohol-induced neuroinflammation as well as whether and by what mechanism it regulates microglia apoptosis. Methods: Adult C57BL/6 mice were divided into four groups and for 3 weeks treated with either 0%, 5%, 10%, or 15% alcohol during 3 hour periods. The mice were sacrificed and their brains excised for analysis. Additionally, primary microglia were isolated from neonatal mice. SIK1 expression in alcohol-treated brain tissue and microglia was analyzed via RT-PCR and western blotting. TUNEL staining, caspase-3, and caspase-9 activity assays were performed to evaluate microglial apoptosis. Cell fluorescence staining and NF-κB luciferase activity assays were used to evaluate the effects of SIK1 expression on the NF-κB signaling pathway. Results: SIK1 expression was increased in the brains of mice that consumed alcohol, and this effect was seen in mouse primary microglia. SIK1 knockdown in microglia increased alcohol-induced apoptosis in these cells. Furthermore, SIK1 reduced NF-κB signaling pathway factors, and SIK1 knockdown in microglia promoted alcohol-induced NF-κB activity. TUNEL staining, caspase-3, and caspase-9 activity assays consistently revealed that alcohol-induced microglial apoptosis was inhibited by depletion of p65. Finally, we determined that NF-κB signaling is required for alcohol-induced, SIK1-mediated apoptosis in microglia. Conclusion: This study establishes for the first time not only that SIK1 is crucial to regulating alcohol-induced microglial apoptosis, but also that the NF-κB signaling pathway is required for its activity. Overall, our results help elucidate mechanisms of alcohol-induced neuroinflammation.
12
Carey, Sean David, Sarah Alshawi, Mondona McCann, and Kathleen Maguire-Zeiss. "4395 alpha-Synuclein Induced Reactive Gliosis." Journal of Clinical and Translational Science 4, s1 (June 2020): 2. http://dx.doi.org/10.1017/cts.2020.52.
Full textAbstract:
OBJECTIVES/GOALS: Reactive gliosis is a hallmark of neurodegenerative disease and is characterized by the release of pro-inflammatory cytokines and physiologic changes to glial cells. Our work identifies a novel inflammatory glial-glial cell interaction and role for mGluR5 that has the potential to provide novel insight into the mechanisms of neurodegeneration. METHODS/STUDY POPULATION: Cell Culture: Mouse primary astrocytes and microglia were isolated from P0-P3 C57BL/6 or Cx3cr1GFP/+ mice.1Treatment: Glia were treated with oligomeric α-synuclein 1μg/mL or mGluR5 agonist CHPG 100 μM.2,3ELISA: Glia culture media was collected and analyzed according to the manufacturer. qRT-PCR: TaqMan™ probes were used according to manufacturer on extracted glia mRNA. ICC: Microglia were labeled with 1:750 Rb x Iba1 (Wako) and 1:500 Alexa Fluor 488 Gt x Rb. Phagocytosis Assay: Primary glia were treated with α-synuclein or astrocyte-conditioned culture media for 24-48hrs. For treatment of microglia with conditioned media, astrocytes were washed with PBS and fresh media was added to prevent carry over of α-synuclein to microglia. The number of fluorescent microbeads per microglia was quantified. RESULTS/ANTICIPATED RESULTS: Mouse primary cortical astrocytes simulated with α-synuclein aggregates adopt a reactive A1 phenotype independent of microglial stimulation. This A1 phenotype is characterized by release of pro-inflammatory cytokines including Complement Component 3 and the monocyte chemoattractant CCL2. Reactive astrocyte media induces a phagocytic phenotype in primary mouse microglia. Along with this, α-synuclein-directed microglial phagocytosis was attenuated with the addition of the mGluR5 agonist CHPG. DISCUSSION/SIGNIFICANCE OF IMPACT: Our findings suggest that oligomeric α-synuclein is capable of inducing a reactive phenotype in astrocytes independent of microglia and implicate crosstalk between glia as an important mediator of inflammation and microglial phagocytosis in synucleinopathies.
13
Nam, Kyong Nyon, Hoon-Ji Jung, Mi-Hyun Kim, Chulhun Kang, Woo-Sang Jung, Ki-Ho Cho, and Eunjoo H. Lee. "Chunghyuldan attenuates brain microglial inflammatory response." Canadian Journal of Physiology and Pharmacology 87, no. 6 (June 2009): 448–54. http://dx.doi.org/10.1139/y09-028.
Full textAbstract:
Microglial cells are the prime effectors in immune and inflammatory responses of the central nervous system (CNS). During pathological conditions, the activation of these cells helps restore CNS homeostasis. However, chronic microglial activation endangers neuronal survival through the release of various proinflammatory molecules and neurotoxins. Thus, negative regulators of microglial activation have been considered as potential therapeutic candidates to target stroke and neurodegenerative diseases. Chunghyuldan, a combinatorial drug consisting of Scutellariae Radix, Coptidis Rhizoma, Phellodendri Cortex, Gardeniae Fructus, and Rhei Rhizoma, has an inhibitory effect on stroke recurrence in patients with small-vessel disease. It has also been reported to confer antihypertensive, antihyperlipidemic, and antiinflammatory effects. The aim of this study was to examine whether Chunghyuldan suppresses microglial activation. Chunghyuldan was effective at inhibiting LPS-induced nitric oxide (NO) release from rat brain microglia. Real-time reverse transcriptase PCR analysis revealed that pretreatment of rat brain microglia with Chunghyuldan attenuated the LPS-induced expression of mRNAs encoding inducible NO synthase, tumor necrosis factor (TNF)-α, interleukin-1β, and cyclooxygenase-2. In rat brain microglia, Chunghyuldan reduced the LPS-stimulated production of TNF-α and prostaglandin E2. In addition, Chunghyuldan significantly decreased LPS-induced phosphorylation of the ERK1/2 and p38 signaling proteins. These results suggest that Chunghyuldan provide neuroprotection by reducing the release of various proinflammatory molecules from activated microglia.
14
Nikodemova, Maria, Alissa L. Small, Rebecca S. Kimyon, and Jyoti J. Watters. "Age-dependent differences in microglial responses to systemic inflammation are evident as early as middle age." Physiological Genomics 48, no. 5 (May 2016): 336–44. http://dx.doi.org/10.1152/physiolgenomics.00129.2015.
Full textAbstract:
Whereas age increases microglial inflammatory activities and impairs their ability to effectively regulate their immune response, it is unclear at what age these exaggerated responses begin. We tested the hypotheses that augmented microglial responses to inflammatory challenge are present as early as middle age and that repeated stimulation of primed microglia in vivo would reveal microglial senescence. Microglial gene expression was investigated in a mouse model of repeated systemic inflammation induced by intraperitoneal injection of bacterial lipopolysaccharide (LPS). Following LPS, microglia from middle-aged mice (9–10 mo) displayed larger increases in Tnfα, Il-6, and Il-1β gene expression compared with young adults (2 mo). Similar results were observed in the spleens of middle-aged mice, indicating that exaggeration of both central and peripheral immune responses are already evident at early middle age. Interestingly, despite greater proinflammatory responses to the first LPS challenge in the aged mice, there were no age-dependent differences in either microglia or spleen following a subsequent LPS dose, suggesting that animals at this age retain the ability to effectively control their immune response following repeated challenge. The exacerbated microglial immune response to systemic inflammation at early middle age suggests that the CNS may be vulnerable to age-dependent alterations earlier than previously appreciated.
15
Li, Xuepei, Junwen Guan, Zhou Jiang, Shuting Cheng, Wang Hou, Junjie Yao, and Zhengrong Wang. "Microglial Exosome miR-7239-3p Promotes Glioma Progression by Regulating Circadian Genes." Neuroscience Bulletin 37, no. 4 (February 2, 2021): 497–510. http://dx.doi.org/10.1007/s12264-020-00626-z.
Full textAbstract:
AbstractGlioma-associated microglial cells, a key component of the tumor microenvironment, play an important role in glioma progression. In this study, the mouse glioma cell line GL261 and the mouse microglia cell line BV2 were chosen. First, circadian gene expression in glioma cells co-cultured with either M1 or M2 microglia was assessed and the exosomes of M2-polarized and unpolarized BV-2 microglia were extracted. Subsequently, we labeled the exosomes with PKH67 and treated GL261 cells with them to investigate the exosome distribution. GL261 cell phenotypes and related protein expression were used to explore the role of M2 microglial exosomes in gliomas. Then a specific miR-7239-3p inhibitor was added to verify miR-7239-3p functions. Finally, the mouse subcutaneous tumorigenic model was used to verify the tumorigenic effect of M2 microglial exosomes in vivo. Our results showed that in gliomas co-cultured with M2 microglia, the expression of the BMAL1 protein was decreased (P < 0.01), while the expression of the CLOCK protein was increased (P < 0.05); opposite results were obtained in gliomas co-cultured with M1 microglia. After treatment with M2 microglial exosomes, the apoptosis of GL261 cells decreased (P < 0.001), while the viability, proliferation, and migration of GL261 cells increased. Increased expression of N-cadherin and Vimentin, and decreased E-cadherin expression occurred upon treatment with M2 microglial exosomes. Addition of an miR-7239-3p inhibitor to M2 microglial exosomes reversed these results. In summary, we found that miR-7239-3p in the glioma microenvironment is recruited to glioma cells by exosomes and inhibits Bmal1 expression. M2 microglial exosomes promote the proliferation and migration of gliomas by regulating tumor-related protein expression and reducing apoptosis.
16
Chagas, Luana da Silva, Poliana Capucho Sandre, Natalia Cristina Aparecida Ribeiro e Ribeiro, Henrique Marcondes, Priscilla Oliveira Silva, Wilson Savino, and Claudio A. Serfaty. "Environmental Signals on Microglial Function during Brain Development, Neuroplasticity, and Disease." International Journal of Molecular Sciences 21, no. 6 (March 19, 2020): 2111. http://dx.doi.org/10.3390/ijms21062111.
Full textAbstract:
Recent discoveries on the neurobiology of the immunocompetent cells of the central nervous system (CNS), microglia, have been recognized as a growing field of investigation on the interactions between the brain and the immune system. Several environmental contexts such as stress, lesions, infectious diseases, and nutritional and hormonal disorders can interfere with CNS homeostasis, directly impacting microglial physiology. Despite many encouraging discoveries in this field, there are still some controversies that raise issues to be discussed, especially regarding the relationship between the microglial phenotype assumed in distinct contexts and respective consequences in different neurobiological processes, such as disorders of brain development and neuroplasticity. Also, there is an increasing interest in discussing microglial–immune system cross-talk in health and in pathological conditions. In this review, we discuss recent literature concerning microglial function during development and homeostasis. In addition, we explore the contribution of microglia to synaptic disorders mediated by different neuroinflammatory outcomes during pre- and postnatal development, with long-term consequences impacting on the risk and vulnerability to the emergence of neurodevelopmental, neurodegenerative, and neuropsychiatric disorders.
17
Colton, C. A., M. Jia, M. X. Li, and D. L. Gilbert. "K+ modulation of microglial superoxide production: involvement of voltage-gated Ca2+ channels." American Journal of Physiology-Cell Physiology 266, no. 6 (June 1, 1994): C1650—C1655. http://dx.doi.org/10.1152/ajpcell.1994.266.6.c1650.
Full textAbstract:
A variety of cytoactive factors produced during injury and inflammation are known to activate the central nervous system (CNS) macrophage, the microglia. Since extracellular potassium levels are known to rise rapidly at sites of injury in the CNS, we examined the possibility that changes in extracellular potassium could mediate changes in microglial function. The effect of an increase in potassium concentration on microglial superoxide anion production was studied in cultured neonatal rat microglia. Rather than directly inducing superoxide anion production, exposure to media containing 25 and 55 mM potassium enhanced the production of superoxide induced by phorbol 12-myristate 13-acetate. This potentiation was blocked by nifedipine, a voltage-gated calcium channel blocker. Treatment of the microglia with BAY K 8644, an agonist for voltage-gated calcium channels, produced an enhancement of superoxide levels similar to that of potassium. Because these data indicated the presence of a voltage-gated calcium channel, we also examined whole cell current in cultured microglia. A small, voltage-dependent inward calcium current was seen that was increased by exposure of the microglia to BAY K 8644. The presence of a small but finite calcium influx via these channels may be an important factor in the regulation of intracellular microglial events such as activation of the NADPH oxidase and the consequent production of superoxide anion.
18
Schilling, Tom, Fred N. Quandt, Vladimir V. Cherny, Wei Zhou, Uwe Heinemann, Thomas E. Decoursey, and Claudia Eder. "Upregulation of Kv1.3 K+ channels in microglia deactivated by TGF-β." American Journal of Physiology-Cell Physiology 279, no. 4 (October 1, 2000): C1123—C1134. http://dx.doi.org/10.1152/ajpcell.2000.279.4.c1123.
Full textAbstract:
Microglial activation is accompanied by changes in K+ channel expression. Here we demonstrate that a deactivating cytokine changes the electrophysiological properties of microglial cells. Upregulation of delayed rectifier (DR) K+channels was observed in microglia after exposure to transforming growth factor-β (TGF-β) for 24 h. In contrast, inward rectifier K+ channel expression was unchanged by TGF-β. DR current density was more than sixfold larger in TGF-β-treated microglia than in untreated microglia. DR currents of TGF-β-treated cells exhibited the following properties: activation at potentials more positive than −40 mV, half-maximal activation at −27 mV, half-maximal inactivation at −38 mV, time dependent and strongly use-dependent inactivation, and a single channel conductance of 13 pS in Ringer solution. DR channels were highly sensitive to charybdotoxin (CTX) and kaliotoxin (KTX), whereas α-dendrotoxin had little effect. With RT-PCR, mRNA for Kv1.3 and Kir2.1 was detected in microglia. In accordance with the observed changes in DR current density, the mRNA level for Kv1.3 (assessed by competitive RT-PCR) increased fivefold after treatment of microglia with TGF-β.
19
Azam, Shofiul, Md Ezazul Haque, In-Su Kim, and Dong-Kug Choi. "Microglial Turnover in Ageing-Related Neurodegeneration: Therapeutic Avenue to Intervene in Disease Progression." Cells 10, no. 1 (January 14, 2021): 150. http://dx.doi.org/10.3390/cells10010150.
Full textAbstract:
Microglia are brain-dwelling macrophages and major parts of the neuroimmune system that broadly contribute to brain development, homeostasis, ageing and injury repair in the central nervous system (CNS). Apart from other brain macrophages, they have the ability to constantly sense changes in the brain’s microenvironment, functioning as housekeepers for neuronal well-being and providing neuroprotection in normal physiology. Microglia use a set of genes for these functions that involve proinflammatory cytokines. In response to specific stimuli, they release these proinflammatory cytokines, which can damage and kill neurons via neuroinflammation. However, alterations in microglial functioning are a common pathophysiology in age-related neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, Huntington’s and prion diseases, as well as amyotrophic lateral sclerosis, frontotemporal dementia and chronic traumatic encephalopathy. When their sentinel or housekeeping functions are severely disrupted, they aggravate neuropathological conditions by overstimulating their defensive function and through neuroinflammation. Several pathways are involved in microglial functioning, including the Trem2, Cx3cr1 and progranulin pathways, which keep the microglial inflammatory response under control and promote clearance of injurious stimuli. Over time, an imbalance in this system leads to protective microglia becoming detrimental, initiating or exacerbating neurodegeneration. Correcting such imbalances might be a potential mode of therapeutic intervention in neurodegenerative diseases.
20
von Maydell, Djuna, and Mehdi Jorfi. "The interplay between microglial states and major risk factors in Alzheimer’s disease through the eyes of single-cell RNA-sequencing: beyond black and white." Journal of Neurophysiology 122, no. 4 (October 1, 2019): 1291–96. http://dx.doi.org/10.1152/jn.00395.2019.
Full textAbstract:
Microglia constitute ~10–20% of glial cells in the adult human brain. They are the resident phagocytic immune cells of the central nervous system and play an integral role as first responders during inflammation. Microglia are commonly classified as “HM” (homeostatic), “M1” (classically activated proinflammatory), or “M2” (alternatively activated). Multiple single-cell RNA-sequencing studies suggest that this discrete classification system does not accurately and fully capture the vast heterogeneity of microglial states in the brain. In fact, a recent single-cell RNA-sequencing study showed that microglia exist along a continuous spectrum of states. This spectrum spans heterogeneous populations of homeostatic and neuropathology-associated microglia in both healthy and Alzheimer’s disease (AD) mouse brains. Major risk factors, such as sex, age, and genes, modulate microglial states, suggesting that shifts along the trajectory might play a causal role in AD pathogenesis. This study provides important insight into the cellular mechanisms of AD and underlines the potential of novel cell-based therapies for AD.
21
Wu, Long-Jun, and Min Zhuo. "Resting Microglial Motility Is Independent of Synaptic Plasticity in Mammalian Brain." Journal of Neurophysiology 99, no. 4 (April 2008): 2026–32. http://dx.doi.org/10.1152/jn.01210.2007.
Full textAbstract:
Microglia are well known for their roles in brain injuries and infections. However, there is no function attributes to resting microglia thus far. Here we performed a combination of simultaneous electrophysiology and time-lapse confocal imaging in green fluorescent protein–labeled microglia in acute hippocampal slices. In contrast to CA1 neurons, microglia showed no spontaneous or evoked synaptic currents. Neither glutamate- nor GABA-induced current/chemotaxis of microglia was detected. Strong tetanic stimulation of Schaffer-collateral pathways that induce CA1 long-term potentiation did not affect microglial motilities. Our results suggest that microglia are highly reserved for neuronal protective function but not synaptic plasticity in the brain.
22
Kettenmann, Helmut, Uwe-Karsten Hanisch, Mami Noda, and Alexei Verkhratsky. "Physiology of Microglia." Physiological Reviews 91, no. 2 (April 2011): 461–553. http://dx.doi.org/10.1152/physrev.00011.2010.
Full textAbstract:
Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed “resting microglia.” Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the “activated microglial cell.” This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
23
Wang, Hong-Mei, Ting Zhang, Jian-Kang Huang, Jing-Yan Xiang, Jing-jiong Chen, Jian-Liang Fu, and Yu-Wu Zhao. "Edaravone Attenuates the Proinflammatory Response in Amyloid-β-Treated Microglia by Inhibiting NLRP3 Inflammasome-Mediated IL-1β Secretion." Cellular Physiology and Biochemistry 43, no. 3 (2017): 1113–25. http://dx.doi.org/10.1159/000481753.
Full textAbstract:
Background/Aims: Microglial activation is an important pathological feature in the brains of patients with Alzheimer’s disease (AD), and amyloid-β (Aβ) peptides play a crucial role in microglial activation. In addition, edaravone (EDA) was recently shown to suppress oxidative stress and proinflammatory cytokine production in APPswePS1dE9 (APP/PS1) mice. However, the mechanism by which EDA inhibits the Aβ-induced proinflammatory response in microglia is poorly understood. Methods: The mitochondrial membrane potential (∆ψm) was evaluated using JC-1 staining. Intracellular reactive oxygen species (ROS) and mitochondrial ROS levels were detected using CM-H2DCFDA and MitoSOXTM Red, respectively. The levels of CD11b, NLRP3, pro-caspase-1 and manganese superoxide dismutase (SOD-2) were observed by western blotting, and the levels of interleukin-1beta (IL-1β) in culture supernatants were quantified using an ELISA kit. Results: Aβ induced microglia activation and mitochondrial dysfunction. In addition, mitochondrial dysfunction was associated with ROS accumulation and activation of the NLRP3 inflammasome. Importantly, Aβ induced activation of the NLRP3 inflammasome, leading to caspase-1 activation and IL-1β release in microglia. Moreover, EDA obviously attenuated the depolarization of ∆ψm, reduced mitochondria-derived ROS production and increased SOD-2 activity, resulting in the suppression of NLRP3 inflammasome-mediated IL-1β secretion in Aβ-treated microglia. Conclusion: EDA is a mitochondria-targeted antioxidant and exhibits anti-inflammatory effects on Aβ-treated microglia.
24
Osipova, Elena D., Oxana V. Semyachkina-Glushkovskaya, Andrey V. Morgun, Natalia V. Pisareva, Natalia A. Malinovskaya, Elizaveta B. Boitsova, Elena A. Pozhilenkova, et al. "Gliotransmitters and cytokines in the control of blood-brain barrier permeability." Reviews in the Neurosciences 29, no. 5 (July 26, 2018): 567–91. http://dx.doi.org/10.1515/revneuro-2017-0092.
Full textAbstract:
AbstractThe contribution of astrocytes and microglia to the regulation of neuroplasticity or neurovascular unit (NVU) is based on the coordinated secretion of gliotransmitters and cytokines and the release and uptake of metabolites. Blood-brain barrier (BBB) integrity and angiogenesis are influenced by perivascular cells contacting with the abluminal side of brain microvessel endothelial cells (pericytes, astrocytes) or by immune cells existing (microglia) or invading the NVU (macrophages) under pathologic conditions. The release of gliotransmitters or cytokines by activated astroglial and microglial cells is provided by distinct mechanisms, affects intercellular communication, and results in the establishment of microenvironment controlling BBB permeability and neuroinflammation. Glial glutamate transporters and connexin and pannexin hemichannels working in the tight functional coupling with the purinergic system serve as promising molecular targets for manipulating the intercellular communications that control BBB permeability in brain pathologies associated with excessive angiogenesis, cerebrovascular remodeling, and BBB-mediated neuroinflammation. Substantial progress in deciphering the molecular mechanisms underlying the (patho)physiology of perivascular glia provides promising approaches to novel clinically relevant therapies for brain disorders. The present review summarizes the current understandings on the secretory machinery expressed in glial cells (glutamate transporters, connexin and pannexin hemichannels, exocytosis mechanisms, membrane-derived microvesicles, and inflammasomes) and the role of secreted gliotransmitters and cytokines in the regulation of NVU and BBB permeability in (patho)physiologic conditions.
25
Twig, Gilad, Solomon A. Graf, Mark A. Messerli, Peter J. S. Smith, Seung H. Yoo, and Orian S. Shirihai. "Synergistic amplification of β-amyloid- and interferon-γ-induced microglial neurotoxic response by the senile plaque component chromogranin A." American Journal of Physiology-Cell Physiology 288, no. 1 (January 2005): C169—C175. http://dx.doi.org/10.1152/ajpcell.00308.2004.
Full textAbstract:
Activation of the microglial neurotoxic response by components of the senile plaque plays a critical role in the pathophysiology of Alzheimer's disease (AD). Microglia induce neurodegeneration primarily by secreting nitric oxide (NO), tumor necrosis factor-α (TNFα), and hydrogen peroxide. Central to the activation of microglia is the membrane receptor CD40, which is the target of costimulators such as interferon-γ (IFNγ). Chromogranin A (CGA) is a recently identified endogenous component of the neurodegenerative plaques of AD and Parkinson's disease. CGA stimulates microglial secretion of NO and TNFα, resulting in both neuronal and microglial apoptosis. Using electrochemical recording from primary rat microglial cells in culture, we have shown in the present study that CGA alone induces a fast-initiating oxidative burst in microglia. We compared the potency of CGA with that of β-amyloid (βΑ) under identical conditions and found that CGA induces 5–7 times greater NO and TNFα secretion. Coapplication of CGA with βΑ or with IFNγ resulted in a synergistic effect on NO and TNFα secretion. CD40 expression was induced by CGA and was further increased when βΑ or IFNγ was added in combination. Tyrphostin A1 (TyrA1), which inhibits the CD40 cascade, exerted a dose-dependent inhibition of the CGA effect alone and in combination with IFNγ and βΑ. Furthermore, CGA-induced mitochondrial depolarization, which precedes microglial apoptosis, was fully blocked in the presence of TyrA1. Our results demonstrate the involvement of CGA with other components of the senile plaque and raise the possibility that a narrowly acting agent such as TyrA1 attenuates plaque formation.
26
Fernández-Mendívil, Cristina, Miguel A. Arreola, Lindsay A. Hohsfield, Kim N. Green, and Manuela G. Lopez. "Aging and Progression of Beta-Amyloid Pathology in Alzheimer’s Disease Correlates with Microglial Heme-Oxygenase-1 Overexpression." Antioxidants 9, no. 7 (July 21, 2020): 644. http://dx.doi.org/10.3390/antiox9070644.
Full textAbstract:
Neuroinflammation and oxidative stress are being recognized as characteristic hallmarks in many neurodegenerative diseases, especially those that portray proteinopathy, such as Alzheimer’s disease (AD). Heme-oxygenase 1 (HO-1) is an inducible enzyme with antioxidant and anti-inflammatory properties, while microglia are the immune cells in the central nervous system. To elucidate the brain expression profile of microglial HO-1 in aging and AD-progression, we have used the 5xFAD (five familial AD mutations) mouse model of AD and their littermates at different ages (four, eight, 12, and 18 months). Total brain expression of HO-1 was increased with aging and such increase was even higher in 5xFAD animals. In co-localization studies, HO-1 expression was mainly found in microglia vs. other brain cells. The percentage of microglial cells expressing HO-1 and the amount of HO-1 expressed within microglia increased progressively with aging. Furthermore, this upregulation was increased by 2–3-fold in the elder 5xFAD mice. In addition, microglia overexpressing HO-1 was predominately found surrounding beta-amyloid plaques. These results were corroborated using postmortem brain samples from AD patients, where microglial HO-1 was found up-regulated in comparison to brain samples from aged matched non-demented patients. This study demonstrates that microglial HO-1 expression increases with aging and especially with AD progression, highlighting HO-1 as a potential biomarker or therapeutic target for AD.
27
Brawek, Bianca, Maryna Skok, and Olga Garaschuk. "Changing Functional Signatures of Microglia along the Axis of Brain Aging." International Journal of Molecular Sciences 22, no. 3 (January 22, 2021): 1091. http://dx.doi.org/10.3390/ijms22031091.
Full textAbstract:
Microglia, the innate immune cells of the brain, are commonly perceived as resident macrophages of the central nervous system (CNS). This definition, however, requires further specification, as under healthy homeostatic conditions, neither morphological nor functional properties of microglia mirror those of classical macrophages. Indeed, microglia adapt exceptionally well to their microenvironment, becoming a legitimate member of the cellular brain architecture. The ramified or surveillant microglia in the young adult brain are characterized by specific morphology (small cell body and long, thin motile processes) and physiology (a unique pattern of Ca2+ signaling, responsiveness to various neurotransmitters and hormones, in addition to classic “immune” stimuli). Their numerous physiological functions far exceed and complement their immune capabilities. As the brain ages, the respective changes in the microglial microenvironment impact the functional properties of microglia, triggering further rounds of adaptation. In this review, we discuss the recent data showing how functional properties of microglia adapt to age-related changes in brain parenchyma in a sex-specific manner, with a specific focus on early changes occurring at middle age as well as some strategies counteracting the aging of microglia.
28
Samuels, Stuart E., Jeffrey B. Lipitz, Gerhard Dahl, and Kenneth J. Muller. "Neuroglial ATP release through innexin channels controls microglial cell movement to a nerve injury." Journal of General Physiology 136, no. 4 (September 27, 2010): 425–42. http://dx.doi.org/10.1085/jgp.201010476.
Full textAbstract:
Microglia, the immune cells of the central nervous system, are attracted to sites of injury. The injury releases adenosine triphosphate (ATP) into the extracellular space, activating the microglia, but the full mechanism of release is not known. In glial cells, a family of physiologically regulated unpaired gap junction channels called innexons (invertebrates) or pannexons (vertebrates) located in the cell membrane is permeable to ATP. Innexons, but not pannexons, also pair to make gap junctions. Glial calcium waves, triggered by injury or mechanical stimulation, open pannexon/innexon channels and cause the release of ATP. It has been hypothesized that a glial calcium wave that triggers the release of ATP causes rapid microglial migration to distant lesions. In the present study in the leech, in which a single giant glial cell ensheathes each connective, hydrolysis of ATP with 10 U/ml apyrase or block of innexons with 10 µM carbenoxolone (CBX), which decreased injury-induced ATP release, reduced both movement of microglia and their accumulation at lesions. Directed movement and accumulation were restored in CBX by adding ATP, consistent with separate actions of ATP and nitric oxide, which is required for directed movement but does not activate glia. Injection of glia with innexin2 (Hminx2) RNAi inhibited release of carboxyfluorescein dye and microglial migration, whereas injection of innexin1 (Hminx1) RNAi did not when measured 2 days after injection, indicating that glial cells’ ATP release through innexons was required for microglial migration after nerve injury. Focal stimulation either mechanically or with ATP generated a calcium wave in the glial cell; injury caused a large, persistent intracellular calcium response. Neither the calcium wave nor the persistent response required ATP or its release. Thus, in the leech, innexin membrane channels releasing ATP from glia are required for migration and accumulation of microglia after nerve injury.
29
Ashwell, K. W. S., H. Holländer, W. Streit, and J. Stone. "The appearance and distribution of microglia in the developing retina of the rat." Visual Neuroscience 2, no. 5 (May 1989): 437–48. http://dx.doi.org/10.1017/s0952523800012335.
Full textAbstract:
AbstractWe have examined the development of microglia in the rat retina, using a peroxidase-conjugated lectin derived from Griffonia simplicifolia. Retinas were studied from animals aged from E(embryonic day)12, just after the invagination of the optic cup and prior to the closure of the optic fissure, to adulthood. The lectin also proved a sensitive label for the endothelial cells of the developing retina. Our results provide some support for the view that microglia are derived from the monocyte-macrophage series of blood cells. At E12, most labeled cells were found at the vitreal surface, suggesting that they had come from the hyaloid circulation, while some had entered the retina and appeared to be migrating towards its ventricular surface. From E14 to early postnatal ages, most labeled cells had processes and resembled the amoeboid microglial cells described in silver carbonate staining studies (Ling, 1982). The number of labeled cells rose from about 700 to E14 to a peak of about 27,000 at P(postnatal day)7, and fell to about 19,600 by P12. As early as E16, a regularity was apparent in the distribution of microglial cells over the surface of the retina, the cells tending to avoid each other. Microglial cells are found throughout the thickness of the very young retina, but as the layers of the retina differentiate, they are increasingly restricted to the inner half of the retina. Our findings indicate that microglia enter the retina well before the period of neuronal death, making it unlikely that they invade the retina solely in response to cell death. Our results confirm however that, once in the retina, microglia become associated with, and appear to phagocytose, the pyknotic debris which appears during the period of neuronal death. They also become closely associated with the retinal vasculature. In the adult, the intensity of the labeling of microglia was much reduced. Those cells which were labeled appeared more differentiated, resembling the “resting microglia” described in earlier studies.
30
Miao, Hongsheng, Runming Li, Cong Han, Xiuzhen Lu, and Hang Zhang. "Minocycline promotes posthemorrhagic neurogenesis via M2 microglia polarization via upregulation of the TrkB/BDNF pathway in rats." Journal of Neurophysiology 120, no. 3 (September 1, 2018): 1307–17. http://dx.doi.org/10.1152/jn.00234.2018.
Full textAbstract:
Intracerebral hemorrhage (ICH) is a devastating disease worldwide with increasing mortality. The present study investigated whether minocycline was neuroprotective and induced M2 microglial polarization via upregulation of the TrkB/BDNF pathway after ICH. ICH was induced via injection of autologous blood into 150 Sprague-Dawley rats. A selective TrkB antagonist [N2–2-2-oxoazepan-3-yl amino] carbonyl phenyl benzo (b) thiophene-2-carboxamide (ANA 12)] and agonist [ N-[2-(5-hydroxy-1H-indol-3-yl) ethyl]-2-oxopiperidine-3-carboxamide (HIOC)] were used to investigate the mechanism of minocycline-induced neuroprotection. Minocycline improved ICH-induced neurological deficits and reduced M1 microglia marker protein (CD68, CD16) expression as well as M2 microglial polarization (CD206 and arginase 1 protein). Minocycline administration enhanced microglia-neuron cross talk and promoted the proliferation of neuronal progenitor cells, such as DCX- and Tuj-1-positive cells, 24 h after ICH. Minocycline also increased M2 microglia-derived brain-derived neurotrophic factors (BDNF) and the upstream TrkB pathway. ANA 12 reversed the neuroprotective effects of minocycline. HIOC exhibited the same effects as minocycline and accelerated neurogenesis after ICH. This study demonstrated for the first time that minocycline promoted M2 microglia polarization via upregulation of the TrkB/BDNF pathway and promoted neurogenesis after ICH. This study contributes to our understanding of the therapeutic potential of minocycline in ICH. NEW & NOTEWORTHY The present study gives several novel points: 1) Minocycline promotes neurogenesis after intracerebral hemorrhage in rats. 2) Minocycline induces activated M1 microglia into M2 neurotrophic phenotype. 3) M2 microglia secreting BDNF remodel the damaged neurocircuit.
31
Ronaldson, Patrick T., and Thomas P. Davis. "Regulation of blood–brain barrier integrity by microglia in health and disease: A therapeutic opportunity." Journal of Cerebral Blood Flow & Metabolism 40, no. 1_suppl (September 14, 2020): S6—S24. http://dx.doi.org/10.1177/0271678x20951995.
Full textAbstract:
The blood–brain barrier (BBB) is a critical regulator of CNS homeostasis. It possesses physical and biochemical characteristics (i.e. tight junction protein complexes, transporters) that are necessary for the BBB to perform this physiological role. Microvascular endothelial cells require support from astrocytes, pericytes, microglia, neurons, and constituents of the extracellular matrix. This intricate relationship implies the existence of a neurovascular unit (NVU). NVU cellular components can be activated in disease and contribute to dynamic remodeling of the BBB. This is especially true of microglia, the resident immune cells of the brain, which polarize into distinct proinflammatory (M1) or anti-inflammatory (M2) phenotypes. Current data indicate that M1 pro-inflammatory microglia contribute to BBB dysfunction and vascular “leak”, while M2 anti-inflammatory microglia play a protective role at the BBB. Understanding biological mechanisms involved in microglia activation provides a unique opportunity to develop novel treatment approaches for neurological diseases. In this review, we highlight characteristics of M1 proinflammatory and M2 anti-inflammatory microglia and describe how these distinct phenotypes modulate BBB physiology. Additionally, we outline the role of other NVU cell types in regulating microglial activation and highlight how microglia can be targeted for treatment of disease with a focus on ischemic stroke and Alzheimer’s disease.
32
Zhang, Ying, Jia Yan, Rong Hu, Yu Sun, Yiwen Ma, Zhifeng Chen, and Hong Jiang. "Microglia are Involved in Pruritus Induced by DNFB via the CX3CR1/p38 MAPK Pathway." Cellular Physiology and Biochemistry 35, no. 3 (2015): 1023–33. http://dx.doi.org/10.1159/000373929.
Full textAbstract:
Background/Aims: Pruritus, also known as itch, is a common, unpleasant sensation that can be difficult to treat. Frequently, chronic itch is associated with the development of neuropathic pain resulting from nerve injury or insult. Previous studies have shown the involvement of spinal microglia in the development of neuropathic pain, but their role in chronic pruritus is unclear. Methods: For this study, we constructed a model of chronic pruritus in mice using repeated applications of 2, 4-dinitrofluorobenzene (DNFB) and showed prolonged scratching behavior in treated mice that continued for at least 7 d after the final DNFB treatment. Results: Scratching was accompanied by activation of spinal microglia and both were reduced by an inhibitor of microglial activity. We also showed that microglial activation entailed increased signaling in the p38 MAPK pathway, and treatment with a p38 inhibitor reduced scratching in DNFB-treated mice. We also examined the role of fractalkine/CX3CR1 signaling in the development of DNFB-induced pruritus and showed that intrathecal administration of antiserum against either CX3CR1or FKN inhibited p38 activity and decreased scratching. Conclusion: Our results suggest that microglia are involved in pruritus induced by DNFB via FKN/CX3CR1/p38MAPK pathways similar to those participating in the development of neuropathic pain.
33
Zhang, Xiang, Hongquan Dong, Susu Zhang, Shunmei Lu, Jie Sun, and Yanning Qian. "Enhancement of LPS-Induced Microglial Inflammation Response via TLR4 Under High Glucose Conditions." Cellular Physiology and Biochemistry 35, no. 4 (2015): 1571–81. http://dx.doi.org/10.1159/000373972.
Full textAbstract:
Background: Microglia activation mediated by toll-like receptor 4 (TLR4) plays an important role in neuroinflammation and postoperative cognitive dysfunction (POCD). Diabetes mellitus (DM) has been recently suggested as an independent risk factor for POCD. In this study, we investigate the potential exacerbation of the inflammatory response in primary microglia due to high glucose conditions. Methods: Primary microglial cells were exposed to normal glucose (25 mmol/L) and high glucose (35 mmol/L) levels alone or with lipopolyscaccharide (LPS 0, 2, 5, 10 ng/mL). The pro-inflammatory response of the cells was assessed by measuring changes in cytokine levels and the evaluation of associated signaling pathways. Results: Neither high glucose nor low LPS (≤5ng/ml) alone had an effect on TNF-a and IL-6 levels, but the combination of low LPS and high glucose stimulated the inflammatory response. Analyses of the associated signaling pathways demonstrated that high glucose enhanced the LPS-induced microglial activation via the TLR4/JAK2/STAT3 pathway. Conclusion: This study demonstrates that high glucose, one of the key abnormalities characteristic of DM, can augment LPS-induced microglial activation and inflammatory cytokine levels through the TLR4/JAK2/STAT3 pathway, offering new insight into the pathophysiological relationship between DM and POCD.
34
Zeng, Xianzhang, Hongliang Ren, Yana Zhu, Ruru Zhang, Xinxin Xue, Tao Tao, and Hongjie Xi. "Gp91phox (NOX2) in Activated Microglia Exacerbates Neuronal Damage Induced by Oxygen Glucose Deprivation and Hyperglycemia in an in Vitro Model." Cellular Physiology and Biochemistry 50, no. 2 (2018): 783–97. http://dx.doi.org/10.1159/000494243.
Full textAbstract:
Background/Aims: Peri-operative cerebral ischemia reperfusion injury is one of the most serious peri-operative complications that can be aggravated in patients with diabetes. A previous study showed that microglia NOX2 (a NADPH oxidase enzyme) may play an important role in this process. Here, we investigated whether increased microglial derived gp91phox, also known as NOX2, reduced oxygen glucose deprivation (OGD) after induction of hyperglycemia (HG). Methods: A rat neuronal-microglial in vitro co-culture model was used to determine the effects of gp91phox knockdown on OGD after HG using six treatment groups: A rat microglia and neuron co-culture model was established and divided into the following six groups: high glucose + scrambled siRNA transfection (HG, n = 5); HG + gp91phoxsiRNA transfection (HG-gp91siRNA, n = 5); oxygen glucose deprivation + scrambled siRNA transfection (OGD, n = 5); OGD + gp91phoxsiRNA transfection (OGD-gp91siRNA, n = 5); HG + OGD + scrambled siRNA transfection (HG-OGD, n = 5); and HG + OGD + gp91phoxsiRNA transfection (HG-OGD-gp91siRNA, n = 5). The neuronal survival rate was measured by the MTT assay, while western blotting was used to determine gp91phox expression. Microglial derived ROS and neuronal apoptosis rates were analyzed by flow cytometry. Finally, the secretion of cytokines, including IL-6, IL-8, TNF-α, and 8-iso-PGF2α was determined using an ELISA kit. Results: Neuronal survival rates were significantly decreased by HG and OGD, while knockdown of gp91phox reversed these rates. ROS production and cytokine secretion were also significantly increased by HG and OGD but were significantly inhibited by knockdown of gp91phoxsiRNA. Conclusion: Knockdown of gp91phoxsiRNA significantly reduced oxidative stress and the inflammatory response, and alleviated neuronal damage after HG and OGD treatment in a rat neuronal-microglial co-culture model.
35
Bernhardi, R. V., and J. G. Nicholls. "Transformation of leech microglial cell morphology and properties following co-culture with injured central nervous system tissue." Journal of Experimental Biology 202, no. 6 (March 15, 1999): 723–28. http://dx.doi.org/10.1242/jeb.202.6.723.
Full textAbstract:
When the leech central nervous system (CNS) is injured, microglial cells migrate to the site of the lesion. It is possible that the injured CNS releases diffusible substances that alter the properties of microglial cells; to investigate this, microglial cells were cultured in the presence of injured or uninjured CNS tissue. Grown on Concanavalin A (Con-A), 75 % of microglial cells are rounded in shape and are avoided by growing neurites. However, when chains of leech ganglia with damaged connectives were cultured on Con-A next to microglial cells, many of the microglial cells changed their morphology. The number of rounded cells present decreased to 48 %, 4 % became spindle-shaped and 48 % had an intermediate form. In addition, the presence of crushed ganglionic chains allowed more growth of neurites across microglial cells than occurred under control conditions, although round-shaped microglia were still avoided by growing neurites. Similar changes in microglial cells were produced in cells plated on Con-A in the presence of conditioned medium from crushed ganglionic chains. Hence, a diffusible substance from injured CNS tissue caused the morphology of the microglial cells plated on Con-A to become more like that of microglia plated on laminin, on which only 22 % of the cells are rounded while the remainder are spindle-shaped and are readily crossed by neurites. Changes in morphology were not observed when microglial cells were cultured with frozen and crushed ganglionic chains or with uncrushed chains. These experiments demonstrate that substances released from damaged leech CNS cause microglial cells plated on Con-A to change their morphology and the way in which they interact with growing neurites.
36
Zhang, Jianfeng, Junfeng Wu, Weichen Zeng, Kai Yao, Hengbing Zu, and Yongfei Zhao. "Function of Thymosin Beta-4 in Ethanol-Induced Microglial Activation." Cellular Physiology and Biochemistry 38, no. 6 (2016): 2230–38. http://dx.doi.org/10.1159/000445578.
Full textAbstract:
Background/Aims: Neuroinflammation mediated by activated microglia may play a pivotal role in a variety of central nervous system (CNS) pathologic conditions, including ethanol-induced neurotoxicity. The purpose of this study was to investigate the function of Tβ4 in ethanol-induced microglia activation. Methods: Quantitative real-time PCR was conducted to assess the expression of Tβ4 and miR-339-5p. Western blot analysis was used to measure the expression of Tβ4, phosphorylated p38, ERK, JNK, Akt, and NF-κB p65. The concentration of TNF-α and IL-1β was determined using ELISA. NO concentration was measured using a nitric oxide colorimetric BioAssay Kit. Double immunofluorescence was performed to determine Tβ4 expression, in order to assess microglial activation in neonatal mouse FASD model. Results: Increased Tβ4 expression was observed in ethanol treated microglia. Knockdown of Tβ4 enhanced ethanol-induced inflammatory mediators tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) and nitric oxide (NO) in BV-2 cells was performed. Exogenous Tβ4 treatment significantly inhibited expression and secretion of these inflammatory mediators. Tβ4 treatment attenuated p38, ERK MAPKs, and nuclear factor-kappa B (NF-κB) pathway activation, and enhanced miR-339-5p expression induced by ethanol exposure in microglia. A neonatal mouse fetal alcohol spectrum disorders (FASD) model showed that Tβ4 expression in the microglia of the hippocampus was markedly enhanced, while Tβ4 treatment effectively blocked the ethanol-induced increase in inflammatory mediators, to the level expressed in vehicle-treated control animals. Conclusion: This study is the first to demonstrate the function of Tβ4 in ethanol-induced microglia activation, thus contributing to a more robust understanding of the role of Tβ4 treatment in CNS disease.
37
Yu, Yong-Peng, Xiang-Lin Chi, and Li-Jun Liu. "Corrigendum to “A Hypothesis: Hydrogen Sulfide Might Be Neuroprotective against Subarachnoid Hemorrhage Induced Brain Injury”." Scientific World Journal 2020 (September 27, 2020): 1–11. http://dx.doi.org/10.1155/2020/8364250.
Full textAbstract:
Gases such as nitric oxide (NO) and carbon monoxide (CO) play important roles both in normal physiology and in disease. Recent studies have shown that hydrogen sulfide (H2S) protects neurons against oxidative stress and ischemia-reperfusion injury and attenuates lipopolysaccharides (LPS) induced neuroinflammation in microglia, exhibiting anti-inflammatory and antiapoptotic activities. The gas H2S is emerging as a novel regulator of important physiologic functions such as arterial diameter, blood flow, and leukocyte adhesion. It has been known that multiple factors, including oxidative stress, free radicals, and neuronal nitric oxide synthesis as well as abnormal inflammatory responses, are involved in the mechanism underlying the brain injury after subarachnoid hemorrhage (SAH). Based on the multiple physiologic functions of H2S, we speculate that it might be a promising, effective, and specific therapy for brain injury after SAH.
38
Yu, Yong-Peng, Xiang-Lin Chi, and Li-Jun Liu. "A Hypothesis: Hydrogen Sulfide Might Be Neuroprotective against Subarachnoid Hemorrhage Induced Brain Injury." Scientific World Journal 2014 (February 23, 2014): 1–9. http://dx.doi.org/10.1155/2014/432318.
Full textAbstract:
Gases such as nitric oxide (NO) and carbon monoxide (CO) play important roles both in normal physiology and in disease. Recent studies have shown that hydrogen sulfide (H2S) protects neurons against oxidative stress and ischemia-reperfusion injury and attenuates lipopolysaccharides (LPS) induced neuroinflammation in microglia, exhibiting anti-inflammatory and antiapoptotic activities. The gas H2S is emerging as a novel regulator of important physiologic functions such as arterial diameter, blood flow, and leukocyte adhesion. It has been known that multiple factors, including oxidative stress, free radicals, and neuronal nitric oxide synthesis as well as abnormal inflammatory responses, are involved in the mechanism underlying the brain injury after subarachnoid hemorrhage (SAH). Based on the multiple physiologic functions of H2S, we speculate that it might be a promising, effective, and specific therapy for brain injury after SAH.
39
Tuan, L., C. Tsao, and L. Lee. "0285 Preventative Voluntary Exercise Ameliorate Synaptic-Pruning Defects on Sleep-Deprived Adolescent." Sleep 43, Supplement_1 (April 2020): A108. http://dx.doi.org/10.1093/sleep/zsaa056.283.
Full textAbstract:
Abstract Introduction Since adolescent is a critical period for brain development, adequate sleep during this period is essential to cognitive performance as well as the psychological health in later life. Emerging evidence on sleep-deprived animal models has detailed the impacts of sleep loss on the developing brain. For instance, our previous study demonstrated that 72 h sleep deprivation (SD) disrupted microglia-mediated synaptic refinement in the dentate gyrus (DG). Physical exercise is proved to counteract the harmful consequences of various stress or neurodegenerative models by modulating microglial function. Therefore, we hypothesized that physical exercise might be a preventive intervention to rescue the failure of synaptic pruning and microglial function after SD in adolescent mice. Methods C57/BL6 male mice 3 weeks were assigned to the home cage (HC), home cage with voluntary exercise (HC+VE), sleep deprivation (SD), or sleep deprivation with voluntary exercise (SD+VE) group. In the groups with VE, a running wheel was placed in the cage 11 days before the SD paradigm. Following 72 h SD, animals were subjected to a short-term memory test or sacrificed directly for further examination. Results Our results showed that impaired memory performance was reversed in sleep-deprived mice after VE. Also, the SD+VE group exhibited less dendritic spine density compared to the SD group, implying VE rescue the synaptic pruning defect after SD. Greater microglia phagocytic ability, characterized by increased internalized postsynaptic materials and lysosomal structure within individual microglia, were observed in the SD+VE compared to the SD group. We also investigated the mRNA expression of microglia-specific receptors critical to developmental synaptic refinement and found an upregulation of CX3CR1 expression in both HC+VE and SD+VE compared to sedentary groups. Conclusion Here we provided evidence featuring that developmental VE significantly alleviated the SD-induced memory defects. Moreover, the SD-induced synaptic pruning impairment and microglial maladaptation were also prevented by the VE regimen, suggesting that physical exercise is a possible therapeutic interventions to the cognitive performance as well as the developmental trajectories to the adolescent brain under the influence of sleep insufficiency. Support Supported by the Ministry of Science and Technology of the Republic of China (Grant number: 104-2314-B-002-129-MY4).
40
Kaiser, Sandra, Sibylle Frase, Lisa Selzner, Judith-Lisa Lieberum, Jakob Wollborn, Wolf-Dirk Niesen, Niels Alexander Foit, Dieter Henrik Heiland, and Nils Schallner. "Neuroprotection after Hemorrhagic Stroke Depends on Cerebral Heme Oxygenase-1." Antioxidants 8, no. 10 (October 19, 2019): 496. http://dx.doi.org/10.3390/antiox8100496.
Full textAbstract:
(1) Background: A detailed understanding of the pathophysiology of hemorrhagic stroke is still missing. We hypothesized that expression of heme oxygenase-1 (HO-1) in microglia functions as a protective signaling pathway. (2) Methods: Hippocampal HT22 neuronal cells were exposed to heme-containing blood components and cell death was determined. We evaluated HO-1-induction and cytokine release by wildtype compared to tissue-specific HO-1-deficient (LyzM-Cre.Hmox1 fl/fl) primary microglia (PMG). In a study involving 46 patients with subarachnoid hemorrhage (SAH), relative HO-1 mRNA level in the cerebrospinal fluid were correlated with hematoma size and functional outcome. (3) Results: Neuronal cell death was induced by exposure to whole blood and hemoglobin. HO-1 was induced in microglia following blood exposure. Neuronal cells were protected from cell death by microglia cell medium conditioned with blood. This was associated with a HO-1-dependent increase in monocyte chemotactic protein-1 (MCP-1) production. HO-1 mRNA level in the cerebrospinal fluid of SAH-patients correlated positively with hematoma size. High HO-1 mRNA level in relation to hematoma size were associated with improved functional outcome at hospital discharge. (4) Conclusions: Microglial HO-1 induction with endogenous CO production functions as a crucial signaling pathway in blood-induced inflammation, determining microglial MCP-1 production and the extent of neuronal cell death. These results give further insight into the pathophysiology of neuronal damage after SAH and the function of HO-1 in humans.
41
Alves, C. Henrique, Rosa Fernandes, Ana Raquel Santiago, and António Francisco Ambrósio. "Microglia Contribution to the Regulation of the Retinal and Choroidal Vasculature in Age-Related Macular Degeneration." Cells 9, no. 5 (May 14, 2020): 1217. http://dx.doi.org/10.3390/cells9051217.
Full textAbstract:
The retina is a highly metabolically active tissue with high-level consumption of nutrients and oxygen. This high metabolic demand requires a properly developed and maintained vascular system. The retina is nourished by two systems: the central retinal artery that supplies the inner retina and the choriocapillaris that supplies the outer retina and retinal pigment epithelium (RPE). Pathological neovascularization, characterized by endothelial cell proliferation and new vessel formation, is a common hallmark in several retinal degenerative diseases, including age-related macular degeneration (AMD). A limited number of studies have suggested that microglia, the resident immune cells of the retina, have an important role not only in the pathology but also in the formation and physiology of the retinal vascular system. Here, we review the current knowledge on microglial interaction with the retinal vascular system under physiological and pathological conditions. To do so, we first highlight the role of microglial cells in the formation and maintenance of the retinal vasculature system. Thereafter, we discuss the molecular signaling mechanisms through which microglial cells contribute to the alterations in retinal and choroidal vasculatures and to the neovascularization in AMD.
42
Kim, Hyo Geun, Ji-Young Kim, Wei-Wan Whang, and Myung Sook Oh. "Neuroprotective effect of Chunghyuldan from amyloid beta oligomer induced neuroinflammation in vitro and in vivo." Canadian Journal of Physiology and Pharmacology 92, no. 6 (June 2014): 429–37. http://dx.doi.org/10.1139/cjpp-2013-0229.
Full textAbstract:
Microglia-mediated inflammation is a major pathological mechanism contributing to Alzheimer’s disease (AD), and has been proposed as a potential therapeutic target. Chunghyuldan (CHD; Qingxue-dan in Chinese and Daio-Orengedokuto in Japanese) possesses wide-ranging biological effects, including anti-hyperlipidemic, anti-stroke, anti-inflammatory, and antioxidant activities that could affect neurological functions. In this study, we examined the effects of CHD in in-vitro and in-vivo models of AD induced by the oligomeric form of amyloid-beta (Aβ oligomer), which acts directly on microglia-mediated neuroinflammation to result in neuronal damage and cognitive impairment. CHD at 0.1–100 μg·mL−1 significantly protected PC12 cells and rat primary hippocampal cells from Aβ oligomer1–42 toxicity. In addition, CHD at 1–10 μg·mL−1 inhibited Aβ oligomer1–42 induced production of nitric oxide, tumor necrosis factor-α, and interleukin-1β in microglial cells. In an in-vivo AD model, administration of CHD (50 mg·(kg body mass)−1, for 5 days, per oral) inhibited the activation of astrocytes and microglia in the dentate gyrus and neuronal damage in the CA1 of the ipsilateral hippocampus. Moreover, CHD ameliorated cognitive impairment induced by Aβ oligomer1–42 toxicity. These results demonstrate the neuroprotective effects of CHD through inhibition of microglia-mediated neuroinflammation in in-vitro and in-vivo AD-like models induced by Aβ oligomer1–42 toxicity.
43
Wang, Yanhe, Zhiyuan Yin, Lixiong Gao, Dayu Sun, Xisu Hu, Langyue Xue, Jiaman Dai, et al. "Curcumin Delays Retinal Degeneration by Regulating Microglia Activation in the Retina of rd1 Mice." Cellular Physiology and Biochemistry 44, no. 2 (2017): 479–93. http://dx.doi.org/10.1159/000485085.
Full textAbstract:
Background/Aims: Retinitis pigmentosa (RP) is characterized by degeneration of photoreceptors, and there are currently no effective treatments for this disease. However, curcumin has shown neuroprotectant efficacy in a RP rat and swine model, and thus, may have neuroprotective effects in this disease. Methods: Immunofluorescence staining, electroretinogram recordings, and behavioral tests were used to analyze the effects of curcumin and the underlying mechanism in retinal degeneration 1 (rd1) mice. Results: The number of apoptotic cells in the retina of rd1 mice at postnatal day 14 significantly decreased with curcumin treatment and visual function was improved. The activation of microglia and secretion of chemokines and matrix metalloproteinases in the retina were inhibited by curcumin. These effects were also observed in a co-culture of BV2 microglial cells and retina-derived 661W cells. Conclusions: Curcumin delayed retinal degeneration by suppressing microglia activation in the retina of rd1 mice. Thus, it may be an effective treatment for neurodegenerative disorders such as RP.
44
Kumar, Sanjay, Brennetta J. Crenshaw, Sparkle D. Williams, Courtnee’ R. Bell, Qiana L. Matthews, and Brian Sims. "Cocaine‐Specific Effects on Exosome Biogenesis in Microglial Cells." Neurochemical Research 46, no. 4 (February 8, 2021): 1006–18. http://dx.doi.org/10.1007/s11064-021-03231-2.
Full textAbstract:
AbstractCocaine is a highly addictive stimulant and a well-known drug, with multiple effects on physiology. Cocaine can have direct effects on all cell types in the brain, including microglia. Microglia can be activated by other conditions, such as infection, inflammation, or injury. However, how cocaine regulates microglia and the influence of cocaine on microglial-derived exosomes remains unknown. Exosomes are nanovesicles that are responsible for intercellular communications, signaling, and trafficking necessary cargo for cell homeostasis. In this study, we hypothesized that cocaine affects exosome biogenesis and composition in BV2 microglial cells. BV2 microglial cells were cultured in exosome-depleted RPMI-1640 media and were treated according to the experimental designs. We observed that cell viability decreased by 11% at 100 µM cocaine treatment but was unaffected at other concentrations. After treatments, the exosomes were isolated from the condition media. Purified exosomes were characterized and quantified using transmission electron microscope (TEM) and nanoparticle tracking analysis (NTA). By NTA, there was a significant decrease in particles/mL after cocaine treatment. There was a 39.5%, 58.1%, 32.3% and 28.1% decrease in particles/mL at 100 nM, 1 μM, 10 μM and 100 μM cocaine, respectively. The characterization of exosomes and exosomal protein was performed by western/dot blot analyses. Tetraspanins CD11b, CD18 and CD63 were relatively unchanged after cocaine treatment. The heat shock proteins (Hsps), Hsp70 and Hsp90, were both significantly increased at 10 μM and 100 μM, but only hsp70 was significantly increased at 10 nM. The Rab proteins were assessed to investigate their role in cocaine-mediated exosomal decrease. Rab11 was significantly decreased at 10 nM, 100 nM, 1 μM, 10 μM and 100 μM by 15%, 28%, 25%, 38% and 22%, respectively. Rab27 was decreased at all concentrations but only significantly decreased at 100 nM, 1 μM and 100 μM cocaine by 21%, 24% and 23%, respectively. Rab35 had no significant changes noted when compared to control. Rab7 increased at all cocaine concentrations but only a significant increase in expression at 100 nM and 10 μM by 1.32-fold and 1.4-fold increase. Cocaine was found to alter exosome biogenesis and composition in BV2 microglial cells. Western and dot blot analyses verified the identities of purified exosomes, and the specific protein compositions of exosomes were found to change in the presence of cocaine. Furthermore, cocaine exposure modulated the expression of exosomal proteins, such as Hsps and Rab GTPases, suggesting the protein composition and formation of microglial-derived exosomes were regulated by cocaine.
45
Jiang, Mei, Hairong Wang, Mingming Jin, Xuelian Yang, Haifeng Ji, Yufeng Jiang, Hanwen Zhang, et al. "Exosomes from MiR-30d-5p-ADSCs Reverse Acute Ischemic Stroke-Induced, Autophagy-Mediated Brain Injury by Promoting M2 Microglial/Macrophage Polarization." Cellular Physiology and Biochemistry 47, no. 2 (2018): 864–78. http://dx.doi.org/10.1159/000490078.
Full textAbstract:
Background/Aims: Recent studies have indicated that exosomes secreted from adipose-derived stem cells (ADSCs) have important effects in the treatment of ischemic injury. However, the treatment mechanism is unclear. This study aimed to investigate whether ADSC-derived exosomes enriched with microRNA (miR)-30d-5p have a protective effect on acute ischemic stroke (AIS). Methods: In the current study, inflammatory factors and miR-30d-5p expression were assessed in 70 subjects with AIS and 35 healthy controls. Exosomes were characterized by transmission electron microscopy and further examined using nanoparticle tracking analyses. A rat model of AIS and an in vitro model of oxygen- and glucose-deprived (OGD) primary microglia were established to study the protective mechanism of exosomes from miR-30d-5p-overexpressing ADSCs in ischemia-induced nerve injury. Results: The results showed that following AIS, the expression of inflammatory cytokines increased, while the anti-inflammatory cytokines IL-4, IL-10, and miR-30d-5p decreased both in patients and in animal models. Moreover, in vitro studies demonstrated that suppression of autophagy significantly reduced the OGD-induced inflammatory response. In addition, exosome treatment was more effective in suppressing the inflammatory response by reversing OGD-induced and autophagy-mediated microglial polarization to M1. Furthermore, in vivo studies showed that exosomes derived from ADSCs significantly decreased the cerebral injury area of infarction by suppressing autophagy and promoting M2 microglia/macrophage polarization. Conclusions: Our results suggest that miR-30d-5p-enhanced ADSC-derived exosomes prevent cerebral injury by inhibiting autophagy-mediated microglial polarization to M1.
46
Jung, Yieun, So-Hee Ahn, Hyunju Park, Sang Hui Park, Kyungsun Choi, Chulhee Choi, Jihee Lee Kang, and Youn-Hee Choi. "MCP-1 and MIP-3α Secreted from Necrotic Cell-Treated Glioblastoma Cells Promote Migration/Infiltration of Microglia." Cellular Physiology and Biochemistry 48, no. 3 (2018): 1332–46. http://dx.doi.org/10.1159/000492092.
Full textAbstract:
Background/Aims: Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. The defining characteristics of GBM are diffuse infiltration of tumor cells into normal brain parenchyma, rapid growth, a high degree of infiltration of microglia and macrophages, and the presence of necrosis. Microglia/macrophages are frequently found in gliomas and they extensively infiltrate GBM tissue, up to 30% of total tumor mass. However, little is known about the effect of necrotic cells (NCs) on microglia infiltration in GBM and the tumor-infiltrating microglia-induced factors in GBMs. Methods: In this study, to address whether necrosis or necrosis-exposed GBM cells affect the degree of microglia/macrophage infiltration, migration and invasion/infiltration assays were performed. Culture supernatants and nuclear extracts of CRT-MG cells treated or untreated with necrotic cells were analyzed using a chemokine array and electrophoretic mobility shift assay, respectively. Results: The presence of NCs promoted the migration/infiltration of microglia, and GBM cell line CRT-MG cells exposed to NCs further enhanced the migration and infiltration of HMO6 microglial cells. Treatment with NCs induced mRNA and protein expression of chemokines such as <unterline>M</unterline>onocyte <unterline>C</unterline>hemoattractant <unterline>P</unterline>rotein-1 (CCL2/MCP-1) and <unterline>M</unterline>acrophage <unterline>I</unterline>nflammatory <unterline>P</unterline>rotein-3α (CCL20/MIP-3α) in CRT-MG cells. In particular, CCL2/MCP-1 and CCL20/MIP-3α were significantly increased in NC-treated CRT-MG cells. NCs induced DNA binding of the transcription factors <unterline>N</unterline>uclear <unterline>F</unterline>actor (NF)-κB and <unterline>A</unterline>ctivator <unterline>P</unterline>rotein 1 (AP-1) to the CCL2/MCP-1 and CCL20/MIP-3α promoters, leading to increased CCL2/MCP-1 and CCL20/MIP-3α mRNA and protein expression in CRT-MG cells. Conclusion: These results provide evidence that NCs induce the expression of CCL2/MCP-1 and CCL20/MIP-3α in glioblastoma cells through activation of NF-κB and AP-1 and facilitate the infiltration of microglia into tumor tissues.
47
Summy-Long, Joan Y., and Sanmei Hu. "Peripheral osmotic stimulation inhibits the brain's innate immune response to microdialysis of acidic perfusion fluid adjacent to supraoptic nucleus." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 297, no. 5 (November 2009): R1532—R1545. http://dx.doi.org/10.1152/ajpregu.00340.2009.
Full textAbstract:
During the brain's innate immune response microglia, astroglia and ependymal cells resolve/repair damaged tissue and control infection. Released interleukin-1β (IL-1β) reaching cerebroventricles stimulates circumventricular organs (CVOs; subfornical organ, SFO; organum vasculosum lamina terminalis, OVLT), the median preoptic nucleus (MePO), and magnocellular and parvocellular neurons in the supraoptic (SON) and paraventricular (PVN) nuclei. Hypertonic saline (HS) also activates these osmosensory CVOs and neuroendocrine systems, but, in contrast to IL-1β, inhibits the peripheral immune response. To examine whether the brain's innate immune response is attenuated by osmotic stimulation, sterile acidic perfusion fluid was microdialyzed (2 μl/min) in the SON area of conscious rats for 6 h with sterile HS (1.5 M NaCl) injected subcutaneously (15 ml/kg) at 5 h. Immunohistochemistry identified cytokine sources (IL-1β+; OX-42+ microglia) and targets (IL-1R+; inducible cyclooxygenase, COX-2+; c-Fos+) near the probe, in CVOs, MePO, ependymal cells, periventricular hypothalamus, SON, and PVN. Inserting the probe stimulated magnocellular neurons (c-Fos+; SON; PVN) via the MePO (c-Fos+), a response enhanced by HS. Microdialysis activated microglia (OX-42+; amoeboid/hypertrophied; IL-1β+) in the adjacent SON and bilaterally in perivascular areas of the PVN, periventricular hypothalamus and ependyma, coincident with c-Fos expression in ependymal cells and COX-2 in the vasculature. These microglial responses were attenuated by HS, coincident with activating parvocellular and magnocellular neuroendocrine systems and elevating circulating IL-1β, oxytocin, and vasopressin. Acidosis-induced cellular injury from microdialysis activated the brain's innate immune response by a mechanism inhibited by peripheral osmotic stimulation.
48
Gallenga, Carla Enrica, Maria Lonardi, Sofia Pacetti, Sara Silvia Violanti, Paolo Tassinari, Francesco Di Virgilio, Mauro Tognon, and Paolo Perri. "Molecular Mechanisms Related to Oxidative Stress in Retinitis Pigmentosa." Antioxidants 10, no. 6 (May 26, 2021): 848. http://dx.doi.org/10.3390/antiox10060848.
Full textAbstract:
Retinitis pigmentosa (RP) is an inherited retinopathy. Nevertheless, non-genetic biological factors play a central role in its pathogenesis and progression, including inflammation, autophagy and oxidative stress. The retina is particularly affected by oxidative stress due to its high metabolic rate and oxygen consumption as well as photosensitizer molecules inside the photoreceptors being constantly subjected to light/oxidative stress, which induces accumulation of ROS in RPE, caused by damaged photoreceptor’s daily recycling. Oxidative DNA damage is a key regulator of microglial activation and photoreceptor degeneration in RP, as well as mutations in endogenous antioxidant pathways involved in DNA repair, oxidative stress protection and activation of antioxidant enzymes (MUTYH, CERKL and GLO1 genes, respectively). Moreover, exposure to oxidative stress alters the expression of micro-RNA (miRNAs) and of long non-codingRNA (lncRNAs), which might be implicated in RP etiopathogenesis and progression, modifying gene expression and cellular response to oxidative stress. The upregulation of the P2X7 receptor (P2X7R) also seems to be involved, causing pro-inflammatory cytokines and ROS release by macrophages and microglia, contributing to neuroinflammatory and neurodegenerative progression in RP. The multiple pathways analysed demonstrate that oxidative microglial activation may trigger the vicious cycle of non-resolved neuroinflammation and degeneration, suggesting that microglia may be a key therapy target of oxidative stress in RP.
49
Lim, Ji-Youn, Donggeun Sul, Bang Yeon Hwang, Kwang Woo Hwang, Ki-Yeol Yoo, and So-Young Park. "Suppression of LPS-induced inflammatory responses by inflexanin B in BV2 microglial cells." Canadian Journal of Physiology and Pharmacology 91, no. 2 (February 2013): 141–48. http://dx.doi.org/10.1139/cjpp-2012-0242.
Full textAbstract:
Microglia are a type of resident macrophage that functions as an inflammation modulator in the central nervous system. Over-activation of microglia by a range of stimuli disrupts the physiological homeostasis of the brain, and induces inflammatory response and degenerative processes, such as those implicated in neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Therefore, we investigated the possible anti-inflammatory mechanisms of inflexanin B in murine microglial BV2 cells. Lipopolysaccharide (LPS) activated BV2 cells and induced the production of pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E2 (PGE2), and cytokines (interleukins-1β and -6, and tumour necrosis factor α). The LPS-induced production of pro-inflammatory mediators was associated with the enhancement of nuclear factor-kappaB (NF-κB) nuclear translocation and the activation of mitogen-activated protein kinase (MAPK) including ERK1/2 and JNK. Conversely, pretreatment of cells with inflexanin B (10 and 20 μg/mL) significantly reduced the production of pro-inflammatory mediators. This was accompanied with the reduced nuclear translocation of NF-κB and reduced activation of MAPKs. These results suggest that inflexanin B attenuated the LPS-induced inflammatory process by inhibiting the activation of NF-κB and MAPKs.
50
Stokes, Jennifer A., Tara E. Arbogast, Esteban A. Moya, Zhenxing Fu, and Frank L. Powell. "Minocycline blocks glial cell activation and ventilatory acclimatization to hypoxia." Journal of Neurophysiology 117, no. 4 (April 1, 2017): 1625–35. http://dx.doi.org/10.1152/jn.00525.2016.
Full textAbstract:
Ventilatory acclimatization to hypoxia (VAH) is the time-dependent increase in ventilation, which persists upon return to normoxia and involves plasticity in both central nervous system respiratory centers and peripheral chemoreceptors. We investigated the role of glial cells in VAH in male Sprague-Dawley rats using minocycline, an antibiotic that inhibits microglia activation and has anti-inflammatory properties, and barometric pressure plethysmography to measure ventilation. Rats received either minocycline (45mg/kg ip daily) or saline beginning 1 day before and during 7 days of chronic hypoxia (CH, PiO2 = 70 Torr). Minocycline had no effect on normoxic control rats or the hypercapnic ventilatory response in CH rats, but minocycline significantly ( P < 0.001) decreased ventilation during acute hypoxia in CH rats. However, minocycline administration during only the last 3 days of CH did not reverse VAH. Microglia and astrocyte activation in the nucleus tractus solitarius was quantified from 30 min to 7 days of CH. Microglia showed an active morphology (shorter and fewer branches) after 1 h of hypoxia and returned to the control state (longer filaments and extensive branching) after 4 h of CH. Astrocytes increased glial fibrillary acidic protein antibody immunofluorescent intensity, indicating activation, at both 4 and 24 h of CH. Minocycline had no effect on glia in normoxia but significantly decreased microglia activation at 1 h of CH and astrocyte activation at 24 h of CH. These results support a role for glial cells, providing an early signal for the induction but not maintenance of neural plasticity underlying ventilatory acclimatization to hypoxia.NEW & NOTEWORTHY The signals for neural plasticity in medullary respiratory centers underlying ventilatory acclimatization to chronic hypoxia are unknown. We show that chronic hypoxia activates microglia and subsequently astrocytes. Minocycline, an antibiotic that blocks microglial activation and has anti-inflammatory properties, also blocks astrocyte activation in respiratory centers during chronic hypoxia and ventilatory acclimatization. However, minocycline cannot reverse ventilatory acclimatization after it is established. Hence, glial cells may provide signals that initiate but do not sustain ventilatory acclimatization.