ABSTRACT
Aim To study the effect of circulating mi-crovesicles containing miR-27 a on blood brain barrier tight junction injury of ischemia stroke mice and its mechanism. Methods The middle cerebral artery occlusion mouse model was established, and the mi-crovesicles in the supernatant of 2 h of ischemic stroke brain tissues were separated by centrifugal ultrafiltra-tion method. The transmission electron microscopy was used to observe microvesicle morphology, and the di-ameter of microvesicles was detected. Based on the 2 h ischemia stroke mouse model, mice were injected via femoral vein with microvesicles at 5 mg · kg-1 . TTC staining was applied to detect infarction volume of is-chemia brain, while HE staining was applied to detect the expression change of tight junction protein occludin and claudin-5 . Western blot was subjected to detect occludin, claudin-5, TLR4, NF-κB and p38 protein expression. ELISA method was used to measure the contents of cytokines IL-1β and TNF-α. Results The microvesicle shape was approximately circular bi-lateral membrane structure, with an average diameter of 160 nm, which conformed to the morphological char-acteristics of microvesicles. Compared with the ische-mic stroke group, injection of microvesicles could ag-gravate the damage of brain tissues in ischemic mice, further increase the infarct volume and reduce the posi-tive staining areas of occludin and claudin-5 in ische-mia brain tissues. Meanwhile, the protein expressions of occludin and claudin-5 further decreased, and fur-ther up-regulated TLR4 and phosphorylation of NF-κB and p38 compared with the ischemia stroke group. Al-so, more content of IL-1βand TNF-αwere detected in ischemia stroke group injected with microvesicles com-pared with those in ischemia stroke group with signifi-cant difference, while the injection of antagomir-27a could alleviate brain damage and reduce the activation of TLR4, NF-κB and p38 in ischemia stroke mice. Conclusions Microvesicles containing miR-27 a could significantly attenuate brain injury in ischemia stroke mice, while aggravate the tight junction damage of ischemia brain. The mechanism might be correlated with the up-regulation of the expression of TLR4 , the phosphorylation of NF-κB, p38, and the release of cy-tokines IL-1β and TNF-α.