Effect of intestinal microbiota transplantation on cerebral ischemia reperfusion injury in aged mice via inhibition of IL-17

Objectives This study investigates the effects and mechanisms of intestinal microbiota transplantation on cerebral ischemia reperfusion injury in aged mice. Methods We constructed a middle cerebral artery occlusion model after fecal microbiota transplantation from young C57 mice to aged C57 mice for 30 consecutive days via enema. The neurological deficit score, cerebral infarction volume, fecal flora composition, and IL-17 levels in the colon, brain, and serum were evaluated in young mice, aged mice, and aged mice that received fecal microbiota transplantation. Moreover, we administered rIL-17A through caudal vein injection to verify its effect on cerebral ischemia reperfusion injury in aged mice. Results We find that aged mice exhibited larger cerebral infarction volume and more severe neurological deficit than young mice after middle cerebral artery occlusion. Bacteroidetes increased and firmicutes decreased significantly in the feces of aged mice after microbiota transplantation. Furthermore, the transplanted mice showed improved neurological function and reduced infarction volume after middle cerebral artery occlusion compared with the control aged mice. We also find that the neuroprotective effect of the microbiota transplantation was reversed by pre-treatment of rIL-17A. Conclusion In summary, intestinal microbiota transplantation can alleviate cerebral ischemia reperfusion injury in aged mice by restoring their microbiota environment and inhibiting IL-17 in the gut, serum, and brain tissue.