Analysis of immune alterations amd their relationship to bacterial infection after stroke

초록

It is now evident that stroke induces systemic immune suppression and cause increase of the susceptibility to secondary infections such as pneumonia and urinary tract infections. Regarding to the systemic immune alterations, stroke induced loss of T lymphocytes and reduction of cytokine production after stroke. However, most studies are focused on early stages of stroke not entire phases of disease. In this study, we analyzed immune alterations, especially T lymphocytes from early to late phase after stroke; 1 and 5 days, 1 and 2 weeks, 2 and 6 months. Results showed that up to 1 week after stroke, total splenocytes and thymocytes were significantly decreased in MCAO mice compared to Sham mice, whereas cell numbers were restored at 2 weeks after stroke. Also, a percentage of CD4+ T cell population was declined both in spleen and blood from MCAO mice. However, a percentage of activated CD4+ T cells were different. In blood, CD44+ CD62L- CD4+ T cell populations were increased whereas these populations were decreased in spleen. In addition, decreased IL-2, 4, 13, and IFN-γ expressions were detected in splenocytes culture media in MCAO mice, when cells were stimulated with α-CD3/CD28 antibodies. Furthermore, thymocytes development was significantly blocked until 1 week after stroke. We also observed bacterial infection in blood from MCAO mice. Therefore, we think that measurement of peripheral CD4+ T cells population might be a useful tool for a prognostic biomarker in stroke.