Increased Platelet S100A8/S100A9 Associated with Vasculitis in Granulomatosis with Polyangiitis (GPA)

Granulomatosis with polyangiitis (GPA), formerly known as Wegener's Granulomatosis, is characterized by vasculitis that predominantly affects small- and medium-sized blood vessels in the sinuses, lungs, and kidneys. In addition to vascular inflammation, GPA is also characterized by an increased risk of thrombosis. The role of platelets in GPA pathogenesis remains incompletely understood. We aimed to better understand the changes in platelet gene expression and function in patients with GPA. Forty-two patients diagnosed with GPA (n=9 with active GPA and n=33 with GPA in remission) and 25 healthy, age-, gender-, and race-matched donors were enrolled. Patients with GPA showed typical disease manifestations, with an average Birmingham Vasculitis Activity Score of 1.6 (Mean±SD 1.6±3.5). One sixth of GPA patients (7/42) had a history of thrombosis. When stimulated with thrombin receptor activating peptide (TRAP, 50nM), platelets from patients with GPA showed significantly increased expression of P-selectin as compared to healthy controls (P-selectin+% Mean±SEM: Healthy 15.50±1.84 vs GPA 25.71±16.05, P