Human serum proteomics reveals extracellular vesicle-mediated metabolic-adhesive signaling and suppression of adaptive immunity in E-cigarette users

Background: While the toxicological impact of combustible cigarette smoke is well characterized, the systemic biological consequences of electronic cigarette use remain poorly understood. As serum contains secreted and vesicle-associated proteins, it provides a window into early biological responses to vaping. We performed serum proteomics to determine how vaping shapes the biology of extracellular vesicles (EVs), metabolic stress pathways, and immune function in humans. Methods: Serum from adult e-cigarette users and non-vaper controls underwent LC-MS/MS proteomics followed by Gene Set Enrichment Analysis (GSEA) across GO Biological Process (BP), Cellular Component (CC), Molecular Function (MF), KEGG, and curated MSigDB C2 secretome/EV signatures. Results: Our results demonstrate that serum from human vapers showed increased expression of glycolytic and oxidative stress-adaptive enzymes (GPI, PKM, IDH1, SOD2), along with significant upregulation of Hypoxia up-regulated protein 1 (HYOU1), indicating engagement of a hypoxia-responsive/ER stress metabolic program. Concordantly, GSEA revealed enrichment of glycolysis, carbon metabolism, ribonucleoside metabolism, and precursor metabolite generation. Cellular component analysis identified strong enrichment of extracellular vesicle, secretory vesicle, membrane-enclosed lumen, and curated secretome signatures, accompanied by upregulation of ECM-cytoskeletal remodeling pathways, including focal adhesion, ECM-receptor interaction, and actin filament organization. These EV-linked pathways were supported by increased abundance of EV-associated adhesion molecules and immunomodulatory factors, including the Neural cell adhesion molecule L1-like protein (CHL1) and the integrins ITGB1 and ITGB2 , which are known to be packaged into EVs during epithelial or immune stress. In parallel, immune-related pathways, including adaptive immune response, immunoglobulin-mediated immunity, and antigen binding, were the only processes negatively enriched, indicating selective suppression of humoral immunity. Conclusions: Chronic e-cigarette use induces a coordinated serum phenotype characterized by hypoxia/ER stress-induced metabolic reprogramming, enhanced extracellular vesicle and adhesion signaling, and downregulation of adaptive immune mechanisms. These findings suggest that metabolic stress-driven EV secretion may contribute to altered immune communication and weakened antibody-mediated responses in e-cigarette users.