Phd in ENDOCRINOLOGICAL SCIENCES

Thesis title: Platelet Hypermetabolism and Dysfunction Across the Spectrum of Metabolic Dysfunction-Associated Steatotic Liver Disease: A Sex-Stratified Analysis

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing health concern given its rising global prevalence, limited diagnostic and therapeutic tools, and strong association with cardiovascular disease. Platelets have been implicated in MASLD pathogenesis; however, the drivers and functional characteristics of platelet dysregulation across the MASLD spectrum remain insufficiently defined. Methods: We conducted a cross-sectional study to characterize platelet metabolic and functional states in MASLD. The study included age-matched individuals with simple steatosis/MASL (n=42), steatohepatitis/MASH (n=28), metabolic dysfunction-associated cirrhosis (n=16), and controls without steatosis (n=23). Platelet phenotype was assessed through an integrated evaluation of routine hematological parameters, soluble and surface markers of platelet activation, platelet mitochondrial status, and functional platelet responses. Platelet-related parameters were analyzed both as absolute values and, when appropriate, after normalization for platelet count or platelet size indices. Analyses were also stratified by biological sex. Results: We found that platelet alterations are detectable across the entire MASLD spectrum and evolve with disease progression. In early MASLD platelets displayed markers of alpha-granule secretion, including increased circulating platelet-derived CD40L together with reduced surface CD40L expression. In MASH group, platelet phenotype was characterized by increased CD42b expression, altered CD44 profile, enhanced mitochondrial activity, and impaired integrin activation under basal conditions and after selected agonist stimulation, indicating a state of platelet activation associated with functional dysregulation. In cirrhosis, platelet abnormalities were accompanied by a higher proportion of dysfunctional mitochondria, suggesting progressive impairment of platelet bioenergetic homeostasis in advanced disease. Sex-stratified analyses showed that several alterations were more evident in males, particularly in MASH, where lower platelet counts together with higher normalized soluble CD40L and CD42b expression suggested enhanced platelet activation and possible hepatic sequestration. Conclusions: In MASLD, platelets exhibit stage-specific alterations involving activation, metabolic reprogramming, and functional impairment. These findings support a relevant role for platelet dysregulation in MASLD pathophysiology and highlight the value of integrated platelet phenotyping, including sex-stratified analysis, for improving mechanistic understanding and identifying potential translational biomarkers.