CD8 signaling in microglia/macrophage M1 polarization in a rat model of cerebral ischemia (original) (raw)
Related papers
PLoS ONE, 2013
The inflammatory response following ischemic stroke is dominated by innate immune cells: resident microglia and bloodderived macrophages. The ambivalent role of these cells in stroke outcome might be explained in part by the acquisition of distinct functional phenotypes: classically (M1) and alternatively activated (M2) macrophages. To shed light on the crosstalk between hypoxic neurons and macrophages, an in vitro model was set up in which bone marrow-derived macrophages were co-cultured with hippocampal slices subjected to oxygen and glucose deprivation. The results showed that macrophages provided potent protection against neuron cell loss through a paracrine mechanism, and that they expressed M2-type alternative polarization. These findings raised the possibility of using bone marrow-derived M2 macrophages in cellular therapy for stroke. Therefore, 2 million M2 macrophages (or vehicle) were intravenously administered during the subacute stage of ischemia (D4) in a model of transient middle cerebral artery occlusion. Functional neuroscores and magnetic resonance imaging endpoints (infarct volumes, blood-brain barrier integrity, phagocytic activity assessed by iron oxide uptake) were longitudinally monitored for 2 weeks. This cell-based treatment did not significantly improve any outcome measure compared with vehicle, suggesting that this strategy is not relevant to stroke therapy.
The role of microglia and myeloid immune cells in acute cerebral ischemia
Frontiers in Cellular Neuroscience, 2015
The immune response to acute cerebral ischemia is a major contributor to stroke pathobiology. The inflammatory response is characterized by the participation of brain resident cells and peripheral leukocytes. Microglia in the brain and monocytes/neutrophils in the periphery have a prominent role in initiating, sustaining and resolving post-ischemic inflammation. In this review we aim to summarize recent literature concerning the origins, fate and role of microglia, monocytes and neutrophils in models of cerebral ischemia and to discuss their relevance for human stroke.
Dominant role of microglial and macrophage innate immune responses in human ischemic infarcts
Brain Pathology
Inflammatory mechanisms, involving granulocytes, T-cells, B-cells, macrophages and activated microglia, have been suggested to play a pathogenic role in experimental models of stroke and may be targets for therapeutic intervention. However, knowledge on the inflammatory response in human stroke lesions is limited. Here, we performed a quantitative study on the inflammatory reaction in human ischemic infarct lesions. We found increased numbers of T-lymphocytes, mainly CD8 1 cells, but not of B-lymphocytes. Their number was very low in comparison to that seen in inflammatory diseases of the central nervous system and they did not show signs of activation. Polymorphonuclear leukocytes were present in meninges and less prominently in the perivascular space in early lesions, but their infiltration into the lesioned tissue was sparse with the exception of a single case. Microglia were lost in the necrotic core of fresh lesions, their number was increased in the surrounding penumbra, apparently due to proliferation. Using TMEM119 as a marker for the resident microglia pool, macrophages in lesions were in part derived from the original microglia pool, depending on the lesion stage. Most microglia and macrophages revealed a proinflammatory activation pattern, expressing molecules involved in phagocytosis, oxidative injury, antigen presentation and iron metabolism and had partially lost the expression of P2RY12, an antigen expressed on homeostatic ("resting") microglia in rodents. At later lesion stages, the majority of macrophages showed intermediate activation patterns, expressing pro-inflammatory and anti-inflammatory markers. Microglia in the normal white matter of controls and stroke patients were already partly activated toward a pro-inflammatory phenotype. Our data suggest that the direct contribution of lymphocytes and granulocytes to active tissue injury in human ischemic infarct lesions is limited and that stroke therapy that targets pro-inflammatory microglia and macrophage activation may be effective.
Distinguishing features of microglia-and monocyte-derived macrophages after stroke
Acta Neuropathol, 2018
After stroke, macrophages in the ischemic brain may be derived from either resident microglia or infiltrating monocytes. Using bone marrow (BM)-chimerism and dual-reporter transgenic fate mapping, we here set out to delimit the responses of either cell type to mild brain ischemia in a mouse model of 30 min transient middle cerebral artery occlusion (MCAo). A discriminatory analysis of gene expression at 7 days post-event yielded 472 transcripts predominantly or exclusively expressed in blood-derived macrophages as well as 970 transcripts for microglia. The differentially regulated genes were further collated with oligodendrocyte, astrocyte, and neuron transcriptomes, resulting in a dataset of microglia-and monocyte-specific genes in the ischemic brain. Functional categories significantly enriched in monocytes included migration, proliferation, and calcium signaling, indicative of strong activation. Whole-cell patch-clamp analysis further confirmed this highly activated state by demonstrating delayed outward K + currents selectively in invading cells. Although both cell types displayed a mixture of known phenotypes pointing to the significance of 'intermediate states' in vivo, blood-derived macrophages were generally more skewed toward an M2 neuroprotective phenotype. Finally, we found that decreased engraftment of blood-borne cells in the ischemic brain of chimeras reconstituted with BM from Selplg −/− mice resulted in increased lesions at 7 days and worse post-stroke sensorimotor performance. In aggregate, our study establishes crucial differences in activation state between resident microglia and invading macrophages after stroke and identifies unique genomic signatures for either cell type.
Stroke, 2000
Background and Purpose —The purpose of this study was (1) to examine the contribution of microglia and macrophages with their interleukin-1β production and (2) to assess the vulnerability and response of oligodendrocytes in cerebral infarction. Methods —Male Wistar rats were subjected to permanent occlusion of the left middle cerebral artery. Expansion of ischemic infarction and response of oligodendrocytes were investigated together with accumulation of inflammatory cells, production of interleukin-1β, and disruption of the blood-brain barrier. Apoptotic cell death was inferred from fragmented DNA and the expression of proapoptotic Bax protein. Results —During expansion of infarction, amoeboid microglia and extravasation of serum albumin were observed not only in the infarcted area but also in the adjacent surviving area, whereas macrophages accumulated along the boundary and granulocytes migrated into the center of the infarction. Both amoeboid microglia and macrophages produced i...
European Journal of Neuroscience, 1998
Cerebral ischaemia leads to profound glial activation and leukocyte infiltration into the infarct area. In this study, we provide evidence for a dual macrophage response in focal ischaemic lesions of the rat brain. We show that a considerable proportion of macrophages in the ischaemic lesions express the CD8αβ heterodimer to date only described on CD8ϩ T cells. As known from other lesion paradigms, CD4ϩ macrophages were also present. Interestingly, CD8-and CD4-expressing macrophages formed two non-overlapping subpopulations. CD8ϩ macrophages reached their maximum during the first week with pronounced downregulation thereafter whereas CD4ϩ cells persisted at high levels into the second week. In contrast to cerebral ischaemia, macrophages in the spleen and in Wallerian degeneration after optic nerve axotomy expressed CD4, but not CD8. In experimental autoimmune encephalomyelitis, CD8 was mainly associated with T cells and very weakly detectable on some ramified cells resembling activated microglia. In conclusion, we show that cerebral ischaemia triggers an unusual inflammatory response characterized by the appearance of CD8ϩ/CD4-macrophages that might exert specific functions in the pathogenesis of ischaemic brain damage.
2000
Background and Purpose-The purpose of this study was (1) to examine the contribution of microglia and macrophages with their interleukin-1 production and (2) to assess the vulnerability and response of oligodendrocytes in cerebral infarction. Methods-Male Wistar rats were subjected to permanent occlusion of the left middle cerebral artery. Expansion of ischemic infarction and response of oligodendrocytes were investigated together with accumulation of inflammatory cells, production of interleukin-1, and disruption of the blood-brain barrier. Apoptotic cell death was inferred from fragmented DNA and the expression of proapoptotic Bax protein. Results-During expansion of infarction, amoeboid microglia and extravasation of serum albumin were observed not only in the infarcted area but also in the adjacent surviving area, whereas macrophages accumulated along the boundary and granulocytes migrated into the center of the infarction. Both amoeboid microglia and macrophages produced interleukin-1, an inflammatory cytokine, during an early ischemic period. Furthermore, macrophages within the infarcted tissue expressed Bax protein and subsequently showed fragmented nuclear DNA. Oligodendrocytes were detected in the infarcted area even after 24 hours following middle cerebral artery occlusion, but they subsequently developed fragmented DNA. A week after onset of ischemia, oligodendrocytes were found to be accumulated in the intact area bordered with the infarct together with reactive astrocytes. Conclusions--Our results suggest the importance of amoeboid microglia, macrophages, and their interleukin-1 production in gradual expansion of cerebral infarction. Resident oligodendrocytes may be resistant to ischemic insults, and oligodendrocytes accumulated at the border of the infarction may participate in tissue repair after cerebral infarction.
Acta neuropathologica communications, 2018
The central nervous system (CNS) contains several types of immune cells located in specific anatomic compartments. Macrophages reside at the CNS borders surrounding the brain vessels, in leptomeningeal spaces and the choroid plexus, where they interact with the vasculature and play immunological surveillance and scavenging functions. We investigated the phenotypic changes and role of these macrophages in response to acute ischemic stroke. Given that CD163 expression is a hallmark of perivascular and meningeal macrophages in the rat and human brain, we isolated CD163 brain macrophages by fluorescence activated cell sorting. We obtained CD163 cells from control rats and 16 h following transient middle cerebral artery occlusion, after verifying that infiltration of CD163 peripheral myeloid cells is negligible at this acute time point. Transcriptome analysis of the sorted CD163 cells identified ischemia-induced upregulation of the hypoxia inducible factor-1 pathway and induction of gene...
Research Square (Research Square), 2022
Background Cerebral ischemia triggers in ammatory changes, and early complications and unfavorable outcomes of endovascular thrombectomy for brain occlusion promote the recruitment of various cell types to the ischemic area. Although phenotype-speci c monocytes/macrophages appear to play a role, the detailed effects remain unclear. To test our hypothesis that post-ischemic phase-dependent modulation of macrophages may represent a potential therapy against ischemic brain damage, we studied the signi cance of inducing anti-in ammatory M2-type, but not pro-in ammatory M1-type, macrophages after brain ischemia. Methods Seven-week-old male Wistar rats subjected to middle cerebral artery occlusion-reperfusion (MCAO-R) were treated for 7 days with an activator of M2-type macrophages, Gc-protein macrophage-activating factor (GcMAF), in the acute (day 0-6) or subacute (day 7-13) phase after ischemia induction and compared with vehicle-treated control rats. Results In MCAO-R rats, brain damage expansion elicited by increased mRNA levels of interleukin (IL)-6 and IL-1β abated on day 7. Acute-phase GcMAF treatment augmented anti-in ammatory CD163 + M2-type-and proin ammatory CD16 + M1-type macrophages, resulting in no bene cial effects. During days 7-14, GcMAF injection increased only CD163 + M2-type macrophages accompanied by elevated mRNA levels of arginase-1 and IL-4. M2-type macrophages co-localized with CD36 + phagocytic cells led to clearance of the infarct area which was abrogated by clodronate-liposomes. Finally, the expression of survival-related molecules on day 28 was augmented in the infarct border, suggesting that activation of M2-type macrophages in the subacute post-ischemia phase may play a therapeutic role. Conclusion Our ndings require further studies to assess the time-dependent therapeutic signi cance of M2-typemacrophages against cerebral ischemia.
Journal of Cerebral Blood Flow & Metabolism, 2000
The proinflammatory cytokine tumor necrosis factor (TNF) is known to be expressed in brain ischemia; however, its cellular and temporal appearance is not fully settled. In this study, nonradioactive in situ hybridization for murine TNF mRNA was performed on brain sections from adult C57×129 mice at 6 hours, 12 hours, 24 hours, 2 days, 5 days, or 10 days (six to eight mice per group) after induction of permanent focal cerebral ischemia. Cortical infarct volumes were estimated, and TNF mRNA-expressing cells were counted within the infarct and infarct border using Cast-Grid analysis. At 12 hours, a peak of 19.2 ± 5.1 TNF mRNA-expressing cells/mm2 was counted, contrasting two to three times lower values at 6 and 24 hours (6.4 ± 4.6 and 9.2 ± 3.4 cells/mm2, respectively) and <2 cells/ mm2 at 48 hours and later stages. The TNF mRNA-expressing cells were distributed along the entire rostrocaudal axis of the cortical infarcts and occasionally within the caudate putamen. At all time point...