Responses of immune organs following cerebral ischemic stroke.

Background Stroke is a leading cause of death and disability worldwide. Recently, brain secondary damage has been hypothesized to be a key aggravating element in an ischemic cascade. However, the interaction between cerebral infarction and immune organs has yet to be fully understood. In this study, we investigated the changes in the rat brain, spleen, thymus, mesenteric lymph node, and liver at 3, 7, and 13 days after transient middle cerebral artery occlusion (tMCAO) by immunohistochemistry. Material and methods Rat models of stroke were made by tMCAO. Functional assessment was performed 3 h, and 1, 3, 5, 7, 9, 11, and 13 days after MCAO. Rat organs were harvested for 2,3,5-triphenyltetrazolium chloride staining and Immunohistochemistry. Results The CD8α+ T cells was found to decrease in the spleen, thymus, mesenteric lymph node, and liver, whereas it increased in the brain. Those of Iba1+ and CD68+ macrophages were decreased in the spleen, thymus, and mesenteric lymph node, whereas they were elevated in the brain and liver. Ki67+ cells showed the same characteristics as macrophages, and increased numbers of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive apoptotic cells were found in the spleen, mesenteric lymph node, liver, and brain. Conclusions The present results demonstrated that stroke is a systemic disease, which not only affects the brain, but also induces responses of immune organs. On the basis of these results, a systemic treatment might be a good strategy for clinical stroke care.