Plasma-Derived sEVs from HNSCC Patients Differentially Regulate NF-κB Signaling in Macrophages Depending on the HPV Status

Background: Head and neck squamous cell carcinomas (HNSCCs) are highly immunosuppressive, and tumor-associated macrophages constitute a major component of HNSCC tumor microenvironments. Here, we investigate the effects of circulating small extracellular vesicles (sEVs) from HNSCC patients on primary macrophages, to elucidate systemic sEV-mediated immune regulation in HNSCC patients. Methods: sEVs were isolated from plasma by size-exclusion chromatography. Internalization of PKH26-labeled sEVs was demonstrated, and mass spectrometry analysis was performed on HNSCC sEVs and sEV-treated macrophages. NF-κB activation was investigated by Western blot and p65 translocation assay. Downstream, mRNA and protein levels of cytokines and chemotaxis of T cells were investigated. Results: Proteomic analysis revealed time-dependent modulation of the macrophage proteome and NF-κB signaling pathway, which was confirmed by Western blot and p65 translocation assay. sEVs from HNSCC patients negative for human papillomavirus type 16 (HPV) differentially modulated NF-κB signaling and sEV uptake mechanisms compared with sEVs from HPV-positive patients and healthy donors. Conclusions: Circulating sEVs derived from HNSCC patient plasma modulate macrophage proteomic profiles and NF-κB signaling. HPV16 status was associated with differential sEV-mediated macrophage regulation, suggesting a potential role of sEVs in systemic immune modulation in HNSCC.