FSP1 acts as an endogenous inhibitor of endothelial ferroptosis and vascular leakage in sepsisNew research identifies protein pathways that may protect against sepsis

Sepsis, defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, remains a global health challenge characterized by high mortality and limited therapeutic options. Recent evidence identifies ferroptosis—an iron-dependent form of regulated cell death driven by the lethal accumulation of lipid peroxides—as a pivotal mechanism underlying sepsis-induced organ damage. Ferroptosis Suppressor Protein 1 (FSP1) has emerged as a critical endogenous inhibitor of ferroptosis that operates independently of the canonical GPX4/glutathione system. This review provides a comprehensive overview of recent research on FSP1 in the context of sepsis-associated organ injury. We detail the multifaceted molecular mechanisms through which FSP1 inhibits ferroptosis, including the canonical FSP1-CoQ10-NAD(P)H axis, the non-canonical vitamin K cycle, ESCRT-III-mediated membrane repair, and the newly characterized vitamin B2-dependent metabolic stability pathway. Furthermore, we highlight the newly discovered STING-FSP1 signaling axis, where cGAS-STING activation transcriptionally represses FSP1, thereby driving endothelial ferroptosis and vascular leakage during sepsis. Additionally, potentially conserved pathways extrapolated from other acute injury models (e.g., ALKBH5, CD36, and SENP3) are discussed to propose novel research directions. The organ-specific roles and protective mechanisms of FSP1 in sepsis-induced injuries of the lungs, heart, liver, kidneys, and brain are systematically summarized. Finally, we evaluate the prospects and challenges of targeting FSP1-related pathways, such as Nrf2 activation and STING inhibition, as potential therapeutic strategies for sepsis. Overall, This review aims to provide new insights into the “inflammation-cell death” cascade in sepsis and offer a theoretical foundation for developing FSP1-targeted interventions to suppress ferroptosis.