Abstract
HIV-associated neurocognitive disorders (HAND) affect 30%-50% of individuals living with HIV on combination antiretroviral therapy, with Alzheimer 's-like pathology as a potent comorbidity of HAND. Our previous studies have implicated hypoxia-inducible factor-1 alpha (HIF-1α) as a central regulator of HIV-1 Tat-mediated amyloid production in astrocytes, which are further released via astrocyte-derived extracellular vesicles (ADEVs), inducing synaptodendritic injury and Alzheimer's-like pathology in naive mice. Based on this premise, we hypothesized that ADEVs carrying HIF-1α-targeting small interfering RNA (siRNA) would alleviate HIV-1-induced Alzheimer's-like pathology and neurodegeneration in CD34+ NSG HIV-infected humanized mice. Intranasally administered mCherry-TSG101-tagged ADEVs in mice demonstrated efficacy of brain delivery, especially to the hippocampus and cortex. In CD34+ NSG mice infected with HIV-1, intranasal delivery of HIF-1α siRNA-loaded ADEVs suppressed HIF-1α, reduced amyloid precursor protein (APP), AβmoC64, Aβ fibrils, and hyperphosphorylated tau (pTau), dampened glial activation as indicated by reduced GFAP and IBA1 expression, and partially restored synaptic proteins, which were dysregulated due to HIV-1 infection. Trends of improvement were also observed in behavioural deficits in spatial memory, anxiety-like behaviour, and sensorimotor gating induced by HIV-1. These findings position HIF-1α as a pivotal mediator of HIV-associated Alzheimer's-like pathology and neurodegeneration in the CD34+ NSG mice and underscore the promising role of ADEV-mediated HIF-1α siRNA delivery as a non-invasive therapeutic strategy for HAND.