Cross-sectional comparison of the platelet phenotype in patients at different stages of metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide. It is a spectrum of diseases driven by inflammation ranging from simple steatosis to steatohepatitis, cirrhosis and/or hepatocellular carcinoma. One of the features of advanced liver disease is thrombocytopenia, to the extent that the platelet count is included in the FIB-4 index, a clinical score that estimates liver fibrosis. However, the functional status of circulating platelets in the various stages of liver disease is still under discussion. Thus, the objective of my PhD project was to characterize the phenotypic profile of platelets and to identify platelet pro-inflammatory features at different stages of the disease, useful for improving early diagnosis or treatment. We enrolled a total of 66 MASLD patients (n=37 steatosis, n=18 steatohepatitis, n=11cirrhosis), and n=18 age-matched subjects, overweight or obese, without evidence of steatosis. Already in patients with simple steatosis we detected reduced expression of CD40L and P-selectin on the platelet surface and concomitant increase of their cleaved ectodomain in plasma. In patients with more advanced stages of the disease, as the platelet count dropped, we observed that the remaining platelets in circulation had increased fibrinogen binding, increased mitochondrial dysfunction and increased phosphatidylserine exposure, a marker of cell death. Consistently we observed that platelets from patients with metabolic dysfunction-related cirrhosis express components of the pyroptosis-associated NLRP3 inflammasome and increased levels of the inflammatory cytokine IL-18. Thus, our data suggests that platelets are innate immune sensors that exposed to excessive lipids and endotoxin from the dysfunctional gut can undergo lytic pro-inflammatory forms of programmed cell death and contribute to the inflammation that drives liver disease progression. Future studies will investigate how to use platelets as early biomarkers and how to interfere with platelet-induced inflammation in MASLD patients.