HIV-associated neurocognitive disorders (HAND) remain a major clinical complication in people living with HIV (PLWH), affecting a substantial proportion of individuals despite the widespread use of combination antiretroviral therapy (cART)^[1]. Approximately 30%-50% of PLWH continue to experience varying degrees of neurocognitive impairment, ranging from asymptomatic neurocognitive impairment to HIV-associated dementia^[2,3]. Importantly, substance use disorder (SUD) is a common comorbidity in PLWH and has been recognized as an important modifier of HAND pathogenesis, as drugs of abuse can exacerbate neuroinflammation, disrupt blood-brain barrier (BBB) integrity, and potentiate HIV-mediated neuronal injury. Thus, although cART effectively controls peripheral viral replication, as PLWH continue to age, the combined effects of persistent viral proteins, substance use, and prolonged antiretroviral exposure result in sustained neurocognitive dysfunction and central nervous system injury. This shift has moved the focus away from direct viral toxicity alone toward intercellular communication pathways that amplify neuropathology, with particular emphasis on extracellular vesicles (EVs)^[4,5]. EVs are now widely recognized as key mediators of central nervous system (CNS) signalling because they shuttle proteins, lipids, and nucleic acids among neurons, astrocytes, microglia, pericytes, and endothelial cells, thereby shaping neuroinflammation, synaptic integrity, and BBB function^[6,7].

In neuroHIV, EVs are especially important because they can package viral proteins, inflammatory mediators, and regulatory RNAs that reprogram recipient cell behaviour at a distance. Astrocyte-derived EVs (ADEVs), for example, may carry Tat-associated signals and pathogenic microRNAs that influence microglial activation, neuronal survival, and vascular homeostasis, while microglia-derived EVs (MDEVs) can further disseminate inflammatory signals that exacerbate neuronal injury. EVs also hold strong biomarker potential, as brain-derived vesicles detectable in cerebrospinal fluid (CSF) and blood have been linked to neurocognitive impairment as well as to markers of neuronal and glial injury in PLWH. Together, these findings position EVs as both mechanistic drivers and translational biomarkers of HAND, providing a useful framework for understanding viral persistence, CNS pathology, and disease processes in the era of cART.

This perspective integrates current evidence into a unified, EV-centered model of NeuroHIV pathogenesis. Within this framework, astrocyte-, microglia-, and neuron-derived EVs function as key intermediates that translate the convergent effects of persistent viral proteins, cART exposure, aging, and substance use into cell-type-specific responses across the neurovascular unit. HIV Tat- and opioid-focused EV pathways highlighted below represent well-characterized examples of how these diverse stressors converge on EV signalling to sustain CNS injury. Elucidating these EV-mediated circuits may reveal novel therapeutic targets and enhance biomarker discovery for HAND.

HIV-1 viral proteins, including Tat, gp120, and Nef, contribute directly to neurotoxicity and neuronal injury, and some of these proteins can also be packaged into EVs/exosomes^[15]. Tat has been detected in exosomes released by astrocytes, supporting a role for EV-mediated Tat transfer in neuroHIV pathogenesis^[16]. Nef, a 27-35 kDa accessory protein, has been implicated in viral persistence and neuroimmune dysfunction and can promote neuronal injury through mechanisms involving inflammatory signalling and cytoskeletal remodelling^[17,18]. Several studies have shown that glial cells can package Nef into EVs, although the efficiency appears to depend on the cell type. In one study, Nef-GFP transfection of microglia, astrocytes, and SH-SY5Y cells demonstrated that only microglia released Nef-containing exosomes, and that these vesicles disrupted BBB integrity^[17]. In contrast, another study demonstrated that primary human astrocytes expressing Nef released Nef-containing EVs, and these ADEVs were taken up by neurons, where they induced oxidative stress, neuronal dysfunction, axonal and dendritic degeneration, increased tau expression, and impaired action potential firing^[18].

More broadly, these findings suggest that EV-associated viral proteins could amplify neuroinflammation and neurodegeneration in HIV infection and contribute to HAND pathogenesis.

Therapeutic strategies emerging from these studies centre on targeting EV biogenesis, cargo sorting, miRNA signalling, neurotrophic support, and inflammatory pathways. Inhibition of EV release, for example, with GW4869, has been shown to reduce Tat-induced EV-miR-9 transfer and attenuate microglial migration, highlighting EV secretion machinery as an upstream intervention point. Disrupting selective cargo loading, such as the hnRNP A2/B1-miR-23a interaction in astrocytes, could prevent miR-23a enrichment in ADEVs and protect pericytes without broadly impairing miRNA function. Modulation of HIF-1α further reduces EV biogenesis and amyloid cargo, thereby alleviating synaptodegeneration. Complementing these approaches, miRNA-based therapeutics offer additional precision: target protectors that shield PTEN from miR-9 or miR-23a can restore normal cellular function, while anti-miR-138 strategies may limit microglial activation through TLR7, particularly when delivered via engineered EVs. Engineered EV platforms have also shown promise; for example, miR-124 delivery reduced drug-induced microglial activation, supporting their potential as therapeutic carriers^[23]. Neurotrophic factor supplementation, including PDGF-CC and PDGF-BB^[24], has been shown to rescue neurodegeneration and reverse synaptic deficits, reinforcing their neuroprotective potential. Targeting inflammatory pathways such as NLRP3 and TLR7 represents a promising therapeutic strategy for NeuroHIV, as their inhibition reduces synaptodendritic injury and EV-mediated microglial activation. However, major translational challenges remain. Broad inhibition of EV biogenesis using agents such as GW4869 may disrupt physiological EV functions critical for CNS homeostasis, immune regulation, and tissue repair. Likewise, effective, cell-specific delivery of miRNA therapeutics, neurotrophic factors, and engineered EVs across the BBB remains difficult. Most supporting evidence is derived from in vitro or animal studies, underscoring the need for validation in clinically relevant NeuroHIV models incorporating chronic HIV protein exposure, antiretroviral therapy, aging, and substance-use comorbidities. Accordingly, future therapeutic development should prioritize the precise modulation of pathogenic EV signalling rather than global inhibition of EV biogenesis.

Collectively [Figure 1], these studies support an integrated EV-centered model of NeuroHIV pathogenesis involving three interconnected circuits. In the Tat-ADEV-microglia circuit, HIV-1 Tat stimulates astrocytes to release EV-miR-9 and EV-miR-7. EV-miR-9 promotes microglial migration through PTEN downregulation, whereas EV-miR-7 disrupts neuronal synaptic integrity by suppressing NLGN2. ADEVs also transfer amyloid cargo via HIF-1α-dependent pathways, contributing to Alzheimer’s-like synaptodendritic injury. In the Tat-MDEV-neuron circuit, Tat-activated microglia release NLRP3-enriched EVs that promote neuronal death and synaptic damage. In the opioid-ADEV circuit, morphine enhances hnRNP A2/B1-mediated EV release, enriching miR-23a, miR-138, and miR-29b, which impair pericyte function and BBB integrity, activate microglia through TLR7, and reduce neuronal viability by suppressing PDGF-B, respectively.

Despite these advances, important challenges remain. Most studies rely on bulk EV isolation and conventional markers, limiting the ability to distinguish exosomes from other EV subtypes or assign vesicles to specific CNS cell populations. Future work should integrate orthogonal isolation methods, single-vesicle and spatial profiling, cell-specific EV labelling, and standardized reporting to define cargo-specific mechanisms. Independent validation of key signalling pathways, including the Tat-miR-9-PTEN and morphine-miR-23a axes, across cellular, animal, and human models is also needed.

Clinical translation requires validation of EV-associated miRNAs, including miR-9, miR-7, miR-23a, miR-138, and miR-29b, as biomarkers in cerebrospinal fluid and blood, with correlations to HAND severity, viral suppression, cART exposure, opioid use, and cognitive decline. Future experimental models should better reflect the complexity of NeuroHIV by incorporating viral proteins, antiretroviral therapy, aging, and substance-use comorbidities while defining EV communication within the neurovascular unit. Therapeutic strategies should prioritize selective targeting of pathogenic EV populations or cargo rather than global inhibition of EV biogenesis to preserve physiological CNS communication and improve long-term safety.

EVs are emerging as central mediators of NeuroHIV pathogenesis, linking viral persistence, glial activation, substance-use comorbidity, neurovascular dysfunction, and neuronal injury. Rather than passive byproducts of cellular stress, EVs actively transmit pathogenic signals across the neurovascular unit. Astrocyte-, microglia-, and disease-associated brain-derived EVs transport regulatory miRNAs, inflammatory proteins, viral stress signals, and amyloid cargo that reprogram recipient cells through pathways involving PTEN, NLGN2, TLR7, NLRP3, and PDGF-B. Key EV-associated miRNAs, including miR-9, miR-7, miR-23a, miR-138, miR-29b, and simian immunodeficiency virus encephalitis (SIVE)-associated miR-21, regulate microglial migration, synaptic integrity, BBB function, innate immune activation, and neuronal survival. Opioid exposure further amplifies these effects by enhancing astrocytic μ-opioid receptor signalling, hnRNP A2/B1-dependent miRNA sorting, and EV-mediated disruption of neuronal and vascular homeostasis. This EV-centered framework shifts the understanding of NeuroHIV from isolated cellular events to interconnected networks of intercellular communication and injury propagation. To achieve clinical translation, future studies must resolve EV heterogeneity, define CNS cell-specific EV populations, validate disease-associated cargo signatures in well-characterized patient cohorts, and identify pathogenic EV subsets and therapeutically actionable cargoes. These advances will be essential for developing reliable biomarkers and targeted interventions to mitigate persistent neuroinflammation and neuronal dysfunction despite effective antiretroviral therapy.