To identify sex-specific proteomic biomarkers associated with incident ischemic stroke (IS) in the Atherosclerosis Risk in Communities (ARIC) study.

ARIC participants without prior stroke at the time of proteomic profiling (Visit 2, 1990-1992) were included. Cox proportional hazards models adjusted for age, race/center, body mass index, eGFR Creatinine Cystatin, smoking, diabetes, hypertension, coronary heart disease were used to identify proteins associated with incident IS through Visit 5 (2011-2013). Proteins significant in women were then tested in men, and sex-by-protein interaction analyses were performed.

Among 11668 ARIC participants (6497 women, 5171 men), 13 proteins (among a total of 4955) were significantly associated with incident IS in women (Bonferroni threshold p<1x10^-5). Among these, only CILP2, an extracellular matrix glycoprotein, was also associated with lower IS risk men (women adjusted Hazard Ratio (aHR) 0.81, 95% CI 0.73-0.9; men aHR 0.78, 0.69-0.87). Two proteins showed significant sex interaction (p<0.05/13): GPNMB, a transmembrane glycoprotein expressed in macrophages and microglia, was associated with higher IS risk in women (aHR 1.23, 1.11–1.35 vs men 0.99, 0.89-1.1), while CST6, a cysteine protease inhibitor, was associated with lower risk (aHR 0.82, 0.74-0.91 vs men 1.02, 0.91-1.16).

In ARIC participants, proteomic analysis identified both shared and sex-specific biomarkers of incident IS. CILP2 was associated with lower IS risk in both sexes, while GPNMB and CST6 showed women-specific associations, implicating inflammatory and lysosomal pathways in sex-related stroke risk. Notably, none of the statistically significant associations involved sex hormone-related proteins. These findings should be confirmed in independent cohorts to validate their generalizability and potential clinical and mechanistic relevance.