Proteome of CD9+ Plasma Small Extracellular Vesicles Differentiates Stages of HPV-Associated Cervical Neoplasia from Normal Epithelium to Invasive Cancer

Human papillomavirus (HPV)-associated cervical lesions remain a significant disease burden and minimally invasive blood-based biomarkers could complement cytology and HPV testing. This study aimed to characterize the proteomic composition of plasma-derived CD9+ small extracellular vesicles (sEVs) across the morphological spectrum of HPV-associated cervical disease, from histologically normal (NILM) through low-grade (LSIL) and high-grade (HSIL) lesions to invasive squamous cell carcinoma (SCC). Plasma samples from 34 women (NILM, LSIL, HSIL, SCC) were pooled per group, and CD9+ sEVs were isolated using an electrochemically controlled immunoaffinity capture method, followed by nanoparticle tracking analysis, transmission electron microscopy, Western blotting, and label-free LC–MS/MS proteomic profiling. The core sEV proteome comprised 258 shared proteins. LSIL showed the most pronounced changes with broad enrichment of complement and coagulation components and acute-phase reactants alongside depletion of immunoglobulin chains and complement C1r-like protein (C1RL). HSIL exhibited few differential proteins, dominated by neutrophil degranulation and retinoid metabolism pathways. SCC demonstrated extensive cargo depletion (22 downregulated proteins) and a nearly sevenfold upregulation of C1RL. Five proteins (including immunoglobulin chains and GPLD1) correlated positively with lesion severity. Pathway analysis consistently implicated platelet activation, lipoprotein remodeling, and insulin-like growth factor signaling. We conclude that plasma CD9+ sEVs carry stage-specific proteomic signatures distinguishing HPV-associated cervical lesions, with C1RL emerging as a candidate biphasic marker warranting further validation.