Dysregulation of complement components associated with inflammation and coagulation in virally suppressed people living with HIV

Although the interplay between the complement system, platelets, and neutrophils has been considered a major contributor to inflammation and thrombogenicity, little attention has been directed toward understanding their roles in people living with human immunodeficiency virus (PLWH). We quantified and compared expression levels of complement components (C2, C3a, C5a, C9), markers for coagulation (vWF-A2, ADAMTS13, tissue factor (TF), protein C, fibrinogen), and neutrophil activation (MPO, MMP-9) in plasma between virally suppressed PLWH (n = 40) and people living without HIV (PLWoH; n = 39). Platelet and activated platelet (CD62P+ cells) counts in the plasma samples were examined by flow cytometry analysis. To determine whether PLWH's plasma promotes neutrophil extracellular traps (NETs) and whether C2 and C5a levels correlate with NET formation, an ex vivo NET assay was performed. PLWH showed significantly altered C2 and C5a levels in plasma that correlated strongly with protein C and MPO. C2 also showed a positive correlation with proinflammatory markers (SSA, SAP, IL-1β, and VEGF). Furthermore, HIV status was a significant predictor of C2 and C5a levels. CD62P expression on platelets was significantly increased in PLWH. In addition, treatment of healthy neutrophils with PLWH's plasmapromoted NET formation, and this effect was inhibited by C5aR antibody treatment and platelet removal. These data suggest that activated platelets and soluble factors, such as higher C5a levels, contribute to NET formation in PLWH. Our findings provide evidence of complement dysregulation associated with inflammation and coagulation in PLWH. Altered soluble factors and platelet activation promote NET formation, potentially driving age-related non-AIDS comorbidities (NACMs).