Senolytic Therapy for Cerebral Ischemia-Reperfusion Injury

Ischemic stroke is one of the leading causes of death, and even timely treatment can result in severe disabilities. Reperfusion of the ischemic stroke region and restoration of the blood supply often lead to a series of cellular and biochemical consequences, including generation of reactive oxygen species (ROS), expression of inflammatory cytokines, inflammation, and cerebral cell damage, which is collectively called cerebral ischemia-reperfusion (IR) injury. Since ROS and inflammatory cytokines are involved in cerebral IR injury, injury could involve cellular senescence. Thus, we investigated whether senolytic therapy that eliminates senescent cells could be an effective treatment for cerebral IR injury. To determine whether IR induces neural cell senescence in vitro, astrocytes were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). OGD/R induced astrocyte senescence and senescent cells in OGD/R-injured astrocytes were effectively eliminated in vitro by ABT263, a senolytic agent. IR in rats with intraluminal middle cerebral artery occlusion induced cellular senescence in the ischemic region. The senescent cells in IR-injured rats were effectively eliminated by intravenous injections of ABT263. Importantly, ABT263 treatment significantly reduced the infarct volume and improved neurological function in behavioral tests. This study demonstrated, for the first time, that senolytic therapy has therapeutic potential for cerebral IR injury.

PTP1B inhibitor alleviates deleterious microglial activation and neuronal injury after ischemic stroke by modulating ER stress-autophagy axis via PERK signaling in microglia

Background : Cerebral ischemia/reperfusion (IR) after ischemic stroke causes microglial activation which lead to neuronal injury. Protein tyrosine phosphatase 1B (PTP1B) emerges to be a positive regulator of neuroinflammation, yet the effect of its inhibition on microglial activation as well as cerebral IR injury is largely unknown. Here we explored whether PTP1B inhibitor sc-222227 attenuates microglial activation and mitigates neuronal injury after cerebral IR injury. Methods : Cerebral IR injury rat model was induced by transient middle cerebral artery occlusion (MCAO) and reperfusion. PTP1B inhibitor sc-222227 was administered intracerebroventricularly 0.5 h before IR injury. Neurological deficits, infarct volume and brain water content were examined. In vitro IR injury model were established by oxygen glucose deprivation/reoxygenation (OGD/R) in rat primary microglia. PTP1B protein level, microglial activation, neuroinflammation, endoplasmic reticulum (ER) stress, autophagy and neuronal apoptosis were detected in vivo and/or in vitro using western blot, immunohistochemistry, immunofluorescence, ELISA and real-time PCR assay. Protein interaction were assessed by proximity ligation assay. Results : PTP1B expression were significantly increased after cerebral IR injury in vivo, and the enhancement was most prominent in microglia. PTP1B inhibitor reduced IR-induced microglial activation both in vitro and in vivo, and further attenuated IR-induced microglial ER stress and autophagy in rat. In vitro experiment showed PTP1B inhibitor mitigated OGD/R-induced microglial activation through inhibiting ER stress-dependent autophagy, whose effect was partly abolished by PERK activator CCT020312. The protein interaction between PTP1B and phosphorylated PERK were significantly increase in response to OGD/R in primary microglia. Finally, PTP1B inhibitor reduced neuronal apoptosis and improved neurologic function after cerebral IR injury in rat. Conclusions : PTP1B inhibitor ameliorated neuronal injury and neurologic deficits following cerebral IR injury via attenuating deleterious microglial activation and subsequent neuroinflammation through modulating ER stress-autophagy axis in microglia. Treatment targeting microglial PTP1B might be a potential therapeutic strategy for ischemic stroke treatment.