Abstract Objective Sepsis-associated coagulopathy (SAC) is a frequent and severe complication of sepsis, closely linked to adverse outcomes, yet its underlying mechanisms remain poorly understood. Given that the collapse of phospholipid asymmetry at the plasma membrane can trigger the coagulation cascade, this study aimed to elucidate the pivotal role of phospholipid metabolism mediated by phospholipid transfer protein (PLTP) in the pathogenesis of SAC. Methods Sepsis patients were prospectively recruited from Peking Union Medical College Hospital (PUMCH) with informed consent for blood collection. Mediation analyses were conducted in two independent cohorts, including sepsis patients from PUMCH and the UK Biobank. In vitro, platelets and monocytes were isolated from peripheral blood by gradient centrifugation and subjected to molecular and cellular assays to validate the mechanistic findings. Results Metabolomic analysis revealed that differential metabolites were significantly enriched in glycerophospholipid and choline metabolism, indicating that dynamic alterations in membrane lipid turnover and signal transduction contribute to coagulation dysfunction. Specific lipid species—phosphatidylserine, cardiolipin, and lysophosphatidylcholine—and their related metabolites exhibited marked abnormalities, suggesting a remodeling of the lipid-inflammation network. Integrated proteomic and metabolomic analyses identified dysregulated PLTP-mediated phospholipid subclass metabolism as a potential intermediary linking the inflammatory storm to the coagulation cascade. Both single-center and UK Biobank cohorts confirmed that PLTP-driven lipid metabolic disturbances significantly influenced SAC development and mediated the relationship between inflammation and coagulopathy. Scanning electron microscopy revealed membrane pore formation in platelets and monocytes from SAC patients, while flow cytometry demonstrated a higher proportion of pyroptotic cells, supporting the involvement of pyroptosis in SAC. Western blotting further showed elevated expression of PLTP and pyroptosis-related molecules, accompanied by enhanced plasma PLTP activity. Liquid chromatography demonstrated distinct phospholipid gradients between intracellular and extracellular compartments of platelets in SAC patients, particularly for phosphatidylserine, cardiolipin, and lysophosphatidylcholine. Conclusion PLTP-mediated disruption of membrane phospholipid asymmetry plays a critical role in inflammation-induced platelet pyroptosis and may represent a key mechanism underlying coagulation dysfunction in sepsis.Figure. Results of the role of phospholipid in SAC via proteomics and metabonomics. A. Heatmap of differential metabolites and proteins between SAC and non-SAC patiens. B. GO and KEGG enrichment of causal factors in SAC, indicated phospholipid metabolism and dynamic alterations in membrane lipid during SAC. C. The lipid and coagulation-related proteins were expressed differently between SAC and non-SAC. This abstract is funded by: National Key R CAMS Innovation Fund for Medical Sciences (CIFMS) 2021-I2M-1-062 from Chinese Academy of Medical Sciences
Liufu et al. (Fri,) studied this question.