Targeting extracellular caspase-1 attenuates sepsis-induced acute lung injury

Sepsis is a life-threatening systemic inflammatory syndrome frequently complicated by acute lung injury (ALI), which markedly increases mortality. Although caspase-1 is well known for its intracellular functions, its extracellular release and pathological role remain unclear. We recently identified cleaved extracellular caspase-1 (p20) (eCasp-1) as a novel damage-associated molecular pattern released via gasdermin D (GSDMD) pores. Furthermore, we developed a novel 16-amino-acid peptide, compound 16 (C16), designed to specifically disrupt the interaction between eCasp-1 and toll-like receptor 4 (TLR4). In the present study, we aimed to elucidate the dynamic release of eCasp-1 during sepsis and to evaluate the therapeutic potential of C16 for attenuating sepsis-induced ALI and improving survival. Sepsis was induced in mice by cecal ligation and puncture (CLP), and eCasp-1 levels were measured in plasma and peritoneal lavage fluid by Western blot and ELISA assays with or without injection of disulfiram, a GSDMD inhibitor. To evaluate therapeutic efficacy, CLP mice received intraperitoneal injection of vehicle or C16, and systemic inflammation, lung injury, and survival were assessed. We found that eCasp-1 time dependently increased in the plasma and peritoneal lavage fluid in septic mice. We demonstrated that eCasp-1 release during sepsis is associated with GSDMD-dependent membrane permeabilization, as disulfiram markedly reduced its levels in the blood and peritoneal lavage fluid. In septic mice, treatment with C16 significantly reduced systemic inflammatory cytokines and organ injury markers, attenuated ALI, and improved lung histopathological injury. Importantly, C16 treatment significantly improved the survival rate after sepsis. eCasp-1 acts as a key extracellular mediator of inflammatory amplification that drives ALI in sepsis. Targeting eCasp-1 with C16 represents a promising therapeutic strategy to mitigate inflammation and ALI and improve survival in sepsis.