Simian Immunodeficiency Virus-Derived Extracellular Vesicles Induce a Chronic Inflammatory Phenotype in Healthy...

Background/Objectives: Extracellular vesicles (EVs) are key mediators of intercellular communication and are implicated in the neuropathogenesis of HIV-associated brain injury (HABI). However, their direct effects on glial cells, particularly in the context of antiretroviral therapy (ART), remain incompletely understood. Methods: In this study, we investigated how EVs from naïve, Simian Immunodeficiency Virus (SIV)-infected, and SIV-infected ART-treated rhesus macaques impact primary mixed glial cultures. Results: Through multiple, sequential applications mimicking chronic exposure, we found that EVs from SIV-infected animals significantly reduced glial expansion and induced a simplified, reactive astrocyte morphology indicative of neuroinflammatory stress. In contrast, EVs from naïve animals supported glial health. EVs derived from ART-treated animals provided partial protection from SIV-induced effects, yet still suppressed glial proliferation and failed to fully restore normal morphology. Furthermore, cytokine profiling revealed that both SIV and SIV + ART EVs induced a sustained proinflammatory secretory phenotype, characterized by elevated IL-6, IL-8, and IFN-γ. Conclusions: Our findings demonstrate that systemically circulating EVs in SIV infection are potential drivers of glial dysfunction. The persistence of these pathogenic EV effects despite ART suggests a vesicle-mediated mechanism that may contribute to chronic neuroinflammation and cognitive impairment in virally suppressed individuals.