Redox Proteomics Mapping of Cysteine Oxidation Events in Sickle Cell Vascular Endothelium: Implications for Pulmonary Hypertension in North Central Nigeria

Pulmonary hypertension is a devastating vasculopathy complicating sickle cell disease, driven in part by nitric oxide depletion and oxidative protein modifications in vascular endothelial cells. This study applies redox proteomics to map cysteine oxidation events in pulmonary vascular endothelial cells from HbSS patients with and without pulmonary hypertension in Kogi and Benue States, North Central Nigeria. A translational case-control design was employed, with 40 HbSS patients with echocardiographically confirmed pulmonary hypertension (TRV greater than 2.5 m/s), 40 HbSS patients without pulmonary hypertension, and 20 HbAA controls. Plasma-derived endothelial extracellular vesicles were isolated by size-exclusion chromatography for proteomics. Cysteine oxidation events including sulfenylation, sulfinylation, and S-nitrosylation were mapped by iodo-dimedone-based chemical proteomic enrichment followed by LC-MS/MS. Nitric oxide bioavailability was assessed by plasma nitrite/nitrate and erythrocyte arginase activity. Serum asymmetric dimethylarginine, an endogenous NOS inhibitor, was measured by ELISA. Key oxidised proteins were validated in patient plasma by targeted SRM-MS. Network analysis identified redox-sensitive protein hubs linking oxidative signalling to vascular dysfunction. This study generates an original redox proteome map of sickle cell pulmonary vasculopathy and proposes novel biochemical targets for pulmonary hypertension prevention in Nigerian HbSS patients. Keywords: redox proteomics, sickle cell disease, pulmonary hypertension, cysteine oxidation, nitric oxide.