ABSTRACT
Studies of brain tissues from people living with HIV (PLWH), as well as HIV/AIDS animal models, showed
increased amyloid-ß (Aß) production and aggregation, amyloid plaques, increased Tau hyperphosphorylation
(pTau) and formation of neurofibrillary tangles-like structures. Importantly, the presence of these Alzheimer’s
Disease (AD)-like pathologies in PLWH is associated with increased neurodegeneration and HIV-associated
neurocognitive impairment (HAND). The mechanisms through which HIV increase Aß production, pTau
pathologies, and induce AD-like central nervous system (CNS) impairment are not known. Although most PLWH
who showed increased CNS amyloid plaques and pTau associated with HAND had been on long-term
antiretroviral therapy (ART), the role of ART in Aß and pTau production, and AD-like pathologies has not been
investigated. Our in-vivo and ex-vivo studies demonstrated that HIV-1 infection significantly increased CNS
levels of Aß42 (the major neurotoxic component of Aß) and pTau, and this was associated with neuronal damage
and blood-brain barrier (BBB) injury. Significantly, we demonstrated that the CCR5 antagonist, maraviroc (MVC),
abrogated HIV-induced production of Aß42 and pTau, prevented HIV-induced damage to neurons and the BBB,
and decreased CNS viral loads. Therefore, we hypothesize that CCR5 plays a major role in the formation
of amyloid plaques and pTau pathology in PLWH and that targeting CCR5 prevents HIV-induced Aß
production, prevents the formation of amyloid plaques and pTau, and abrogates neuronal loss, and
HAND. In these exploratory studies, we will use a validated HIV/AIDS animal model to test this hypothesis and
further investigate the effects of a commonly prescribed antiretroviral (ARV) drug (azidothymidine [AZT]) on HIV-
1-induced amyloidogenesis, pTau and CNS injury (Aim-1), neuroinflammation and Aß clearance (Aim-2), the
metabolism of amyloid precursor proteins (APP) and Tau (Aim-3). These mechanistic studies will help determine
whether HIV induce Aß production by interfering with i) Aß degradation and clearance, ii) APP a-secretase or ß-
secretase pathways; iii) the effectors and pathways associated with HIV-induce pTau, iv) the role of ARV (AZT),
and v) whether CCR5 modulates these effects. Studies in this R21 application are very significant and address
the NIH high priority research areas that focus on “Examining the pathophysiologic mechanisms of HIV-induced
CNS dysfunction in the setting of ART…. and development of novel therapeutic approaches to mitigate CNS
complications of HIV infection.” The CCR5 antagonist MVC is an FDA-approved drug and our study will
determine whether MVC prevents CNS Aß production, formation of amyloid plaques and pTau in the setting of
HIV-infection and ART, and the associated mechanisms. The results will demonstrate the role of CCR5 in HIV-
induced production of Aß and pTau in the CNS and provide new approaches for therapeutically targeting CCR5
to prevent HIV-1-induced amyloidogenesis, pTau pathology, neuronal injury, and neurocognitive impairments.