CZL-80,a novel caspase-1 inhibitor,pro⁃motes functional recovery after progressive ischemic stroke

OBJECTIVE Progressive isch⁃emic stroke is characterized by aggravation of neurological dysfunction and poor prognosis.Neuroinflammation is involved in the pathological process of cerebral ischemia.Inflammasomes-activated caspase-1 has thus been considered a promising target for stroke therapy.However,it remains not fully understood how caspase-1 ag⁃gravates progressive functional impairment.We previously identified a novel caspase-1 inhibitor CZL-80,the present study is to explore whether CZL-80 protects against progressive ischemic stroke.METHODS Male C57/BL6 mice and cas⁃pase-1-/-mice were subjected to photothrombotic(PT)-induced cerebral ischemia.CZL-80 was in⁃traperitoneally injected daily during 1-7 d,1-4 d,4-7 d after PT.The grid-walking task and the cyl⁃inder task were used to determine the motor function.RESULTS Mice developed primary and the secondary neurological dysfunction at 1 d and 4-7 d after PT onset.The activation of cas⁃pase-1 peaked at 7 d after ischemic stroke and caspase-1 was mainly derived from activated microglia.Treatment with CZL-80(30 mg·kg-1)during 1-7 d significantly improved motor func⁃tion.Administration of CZL-80 during 1-4 d could not ameliorate motor function loss while administration during 4-7 d after PT onset signifi⁃cantly reduced foot faults and forelimb symme⁃try.Remarkably,treatment with CZL-80 during 4-7 d showed no significant difference in efficacy compared with the its administration during 1-7 d,which indicated a key therapeutic window.More⁃over,the neuroprotective effect of CZL-80 during 4-7 d was available at least until 43 d after isch⁃emic stroke,indicating CZL-80 can improve the long-term neurological function after cerebral ischemia.Furthermore,administration of CZL-80(30 mg·kg-1)during 4-7 d after PT onset in cas⁃pase-1-/-mice failed to improve the motor func⁃tion,which suggested that the neuroprotective effect of CZL-80 was caspase-1-dependent.The results showed that CZL-80 did not inhibit the expression of GSDMD and failed to reduce neu⁃ronal loss after ischemia.These results indicated the effect of CZL-80 was not attributable to inhib⁃it pyroptosis.We further found that CZL-80 signif⁃icantly reduced the number of activated microglia in the peri-infarct brain cortex after ischemic stroke,which might be involved in its neuropro⁃tective effect.CONCLUSION CZL-80,a novel caspase-1 inhibitor,improved motor function after progressive ischemic stroke in mice.The effective therapeutic window of CZL-80 would be 4-7 d after ischemia,when the secondary neuro⁃logical dysfunction occurred.Therefore,the inter⁃vention by targeting caspase-1 in this window phase provides a novel strategy for the function⁃al recovery of stroke survivors.