Gasdermin D-dependent platelet pyroptosis exacerbates NET formation and inflammation in severe sepsis

Platelets have emerged as key inflammatory cells implicated in the pathology of sepsis, but their contributions to rapid clinical deterioration and dysregulated inflammation have not been defined. Here, we show that the incidence of thrombocytopathy and inflammatory cytokine release was significantly increased in patients with severe sepsis. Platelet proteomic analysis revealed significant upregulation of gasdermin D (GSDMD). Using platelet-specific Gsdmd-deficient mice, we demonstrated a requirement for GSDMD in triggering platelet pyroptosis in cecal ligation and puncture (CLP)-induced sepsis. GSDMD-dependent platelet pyroptosis was induced by high levels of S100A8/A9 targeting toll-like receptor 4 (TLR4). Pyroptotic platelet-derived oxidized mitochondrial DNA (ox-mtDNA) potentially promoted neutrophil extracellular trap (NET) formation, which contributed to platelet pyroptosis by releasing S100A8/A9, forming a positive feedback loop that led to the excessive release of inflammatory cytokines. Both pharmacological inhibition using Paquinimod and genetic ablation of the S100A8/A9–TLR4 signaling axis improved survival in mice with CLP-induced sepsis by suppressing platelet pyroptosis. Su, Chen et al. show that sepsis-derived S100A8/A9 induces GSDMD-dependent platelet pyroptosis via the TLR4/ROS/NLRP3/caspase 1 pathway, leading to the release of ox-mtDNA contributing to neutrophil extracellular traps (NET) formation. NET in turn release S100A8/A9 and accelerate platelet pyroptosis, forming a positive feedback loop, thereby amplifying the production of proinflammatory cytokines. GSDMD deficiency in platelets or pharmacological inhibition of S100A9 using Paquinimod can break this detrimental feedback loop, thus ameliorating excessive NET-mediated inflammation in mouse models of severe sepsis.