The cystathionine β-synthase/hydrogen sulfide pathway contributes to microglia-mediated neuroinflammation following cerebral ischemia

•Microglial CBS and H2S production were rapidly reduced under ischemic conditions.•CBS overexpression enhanced microglial H2S production and M2 polarization.•H2S donors promoted microglial M2 polarization under ischemic conditions.•CBS overexpression & H2S donors rescued ischemia-reduced microglial AMPK activation.•H2S effects on microglial polarization was abolished by AMPK inhibition. The mechanisms underlying neuroinflammation following cerebral ischemia remain unclear. Hydrogen sulfide (H2S), a newly identified gasotransmitter, has been reported to regulate inflammation. In the current study, we investigated whether the endogenous H2S production pathway contributed to microglia-mediated neuroinflammation following stroke. We used a mouse middle cerebral artery occlusion (MCAO) model and an in vitro cellular model to mimic ischemia-induced microglial neuroinflammation. Expression of the H2S synthase cystathionine β-synthase (CBS) and H2S synthetic activity were rapidly decreased in the ischemic brain tissue following MCAO. Consistently, when cultured microglia were polarized toward a pro-inflammatory phenotype with conditioned medium collected from neurons that had been subjected to oxygen-glucose deprivation (OGD neuron CM), they displayed reduced CBS expression and H2S production. Enhancing H2S bioavailability either by overexpressing CBS or by supplementing with exogenous H2S donors promoted a shift in microglial polarization from ischemia-induced pro-inflammatory phenotypes toward anti-inflammatory phenotypes. Mechanistically, microglia that were exposed to OGD neuron CM displayed reduced activation of AMP-activated protein kinase (AMPK), which was rescued by overexpressing CBS or by supplementing with H2S donors. Moreover, the promoting effects of H2S donors on microglial anti-inflammatory polarization were abolished by an AMPK inhibitor or CaMKKβ inhibitor. Our results suggested that reduced CBS-H2S-AMPK cascade activity contributed to microglia-mediated neuroinflammation following stroke. Targeting the CBS-H2S pathway is a promising therapeutic approach for ischemic stroke.