Abstract WMP73: Peripheral T Cells From MCAO Mice Contribute to Microglial Polarization

Both resident microglia and infiltrated peripheral T cells have been proved to play important roles in the pathology of stroke. It is well accepted that activated microglia exert dual roles, including pro-inflammatory (M1) and anti-inflammatory (M2) functions. However, the mechanism regulating microglial polarization remains elusive. T cells are recruited into the ischemic area within 24 h after stroke, which also exhibit pro-inflammatory (Th1, Th17) and anti-inflammatory (Th2, Treg) functions. The interaction between microglia and T cells after stroke is barely understood, which may be served as modifiers of pathobiology in stroke. Here we described the role of T cells in the microglial polarization in mouse experimental stroke. We isolated T cells from spleens of MCAO mice at 24 h and 72 h, respectively, and then added to cultured microglia for 24 h. Our results indicated that splenic T cells obtained at 24 h after MCAO selectively promoted microglia polarize to a pro-inflammatory (M1) state, while T cells obtained at 72 h, favored microglia polarize to an anti-inflammatory (M2) state. The results of flow cytometry showed that Th1 and Th17 cells increased at 24 h after MCAO while Th2 and Treg cells increased at 72 h after MCAO. This study implicates that distinct subtypes of T cells contribute differentially to microglial polarization after stroke onset. Therefore, treatments aiming at modulating the ratios of T cells to anti-inflammatory cells have the potential to induce microglial polarize to M2 phenotype and improve the outcome of ischemic stroke.