Abstract T P222: Fasl Mutation Facilitates Double Negative T Cell Accumulation And Modulates Microglia Activation In Ischemic Stroke

Abstract

Background: The crosstalk between T lymphocyte and microglia plays an important role in ischemia reperfusion injury. The FasL mutation Gld mice had emerged the advantages in neuroprotection after MCAO. Double negative (DN) CD4(-)CD8(-) T lymphocytes were accumulated in peripheral blood and spleen of Gld mice. The objectives of this study were to explore the crosstalk between DN T cells and microglia in Gld mice after ischemic stroke. Method: The subtypes of T lymphocytes and microglia in brain tissue after cerebral ischemia were measured by flow cytometry and immunofluorescence. In vitro, different subtypes of T lymphocyte were co-cultured with primary microglia undergoing different treatments. ELISA and Real-time PCR were used to quantify the cytokines and chemokines. Results: DN T lymphocytes were obviously accumulated in ischemic regions in Gld mice after MCAO 3 days, the percentage of CD4+ or CD 8+ T lymphocyte were lightly decreased in Gld mice, compared with wild type B6 mice. Meanwhile, the activation of microglia in ischemic tissue was alleviated in Gld mice. Compared to wild type mice, a shift to alternative activated microglia (M2) rather than classical activated microglia (M1) was observed in Gld mice. In vitro, different T lymphocyte subtypes isolated from spleen in Gld mice showed various effect on primary microglia. Primary microglia underwent a shift to M2 microglia when co-cultured with CD4+ T lymphocytes and DN T lymphocytes, while switched a shift to M1 microglia when co-cultured with CD8+ T lymphocytes. Besides, pro-inflammation cytokines like IL-1β, TNF-α and MCP-1 secreted by microglia and T lymphocytes were decreased, anti-inflammation cytokines such as IL-4, IL-10 and TGF-βwere increased when primary microglia were co-cultured with CD4+ T lymphocytes and DN T lymphocytes. Conclusion: It’s showed that DN T lymphocytes were accumulated in ischemic brain tissue in Gld mice,which improved the outcome of stroke in Gld mice. The neuroprotective mechanism may be referred to the immunoregulation of DN T lymphocytes on microglia via promoting switching to alternative activated microglia and alleviating inflammation. The new understanding on DN T lymphocyte may provide additional views on post-stroke immune regulation.