Endothelial endogenous CSE/H2S inhibits endothelial pyroptosis by activating sirtuin1 to attenuate LPS-induced acute lung injury

Endothelial pyroptosis, a pro-inflammatory programmed cell death, promotes endothelial inflammation and is a pivotal process in the initial stage of acute lung injury (ALI). Hydrogen sulfide (H 2 S), a gasotransmitter primarily dependent on cystathionine γ-lyase (CSE) in the cardiovascular and respiratory systems, plays a protective role during ALI. Nonetheless, the modulatory role and precise molecular mechanism of endothelial endogenous CSE/H 2 S in the pathogenesis of ALI remain elusive. Herein, we prepared an ALI mouse model using intratracheal administration of LPS (5 mg/kg), and lung injury was assessed by evaluating pulmonary edema, inflammatory response, and endothelial pyroptosis. In this model, H 2 S production from pulmonary tissues declined in a time-dependent manner, accompanied by a compensatory elevation of CSE protein levels. Treatment with the H 2 S donor (NaHS) attenuated pulmonary edema, inflammatory cell infiltration, endothelial pyroptosis, and reduced serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Meanwhile, the inducible deletion of CSE in endothelial cells exacerbated these changes. The blocking effect of CSE/H 2 S on endothelial pyroptosis (evidenced by caspase-11 activation and GSDMD-NT formation) was also confirmed in cultured pulmonary microvascular endothelial cells (PMECs). Mechanistically, H 2 S-mediated regulation of sirtuin-1 (SIRT1) expression and activation (via sulfhydration) contributed to the modulatory process. Collectively, we uncovered that endothelial endogenous CSE/H 2 S alleviates endothelial pyroptosis by activating SIRT1, thereby preventing LPS-induced acute lung injury. Graphical In the LPS-induced ALI model, caspase-1-independent pyroptosis was activated. The expression of activated caspase-11 and GSDMD-NT was increased, accompanied by pulmonary edema and inflammatory infiltration. Endothelial CSE/H 2 S deficiency aggravated endothelial pyroptosis and acute lung injury. Mechanistically, endothelial endogenous CSE/H 2 S mediated the expression and activation of sirtuin-1 (SIRT1) via sulfhydration, one of the post-translational modifications. Activated SIRT1 inhibited the activation of caspase-11 and GSDMD-NT to inhibit endothelial pyroptosis, thereby alleviating acute lung injury.