Immune mechanisms that shape the blood brain barrier in people living with HIV and cocaine use disorder

PROJECT SUMMARY/ABSTRACT The blood brain barrier (BBB), formed by vascular endothelial and supporting cells, functions to regulate blood- brain exchange of substances and cells, and to protect the central nervous system (CNS) from neurotoxins and pathogens. Building on our efforts toward ameliorating HIV-associated CNS complications and achieving HIV cure, we now must address the growing evidence that BBB impairment is associated with acute and/or repeated cocaine use . Cocaine misuse (intranasal, intravenous, inhalation) is common among people living with HIV (PLWH) and viral reservoirs in brain can be seeded by infected immune cells that penetrate the BBB . As the field pursues new strategies to mitigate CNS consequences of HIV infection in the context of substance use, and achieve cure, it will be critical to define the mechanisms by which HIV-infected cells and cocaine impact BBB integrity and the subsequent consequences on both the viral reservoir and cognition in PLWH. We propose a central model wherein historical cocaine misuse causes a persistent deficit in BBB integrity that underlies cognitive impairment in PLWH. In this model, PLWH with historical cocaine use disorder (CUDH) 1) have higher prevalence of CCR2+ALCAM+ intermediate monocytes that harbor HIV proviral DNA and migrate to the brain, and 2) this higher prevalence of CCR2+ALCAM+ intermediate monocytes results in increased transmigration across the BBB disrupting BBB permeability and tight junctions (TJ). In vivo studies in humans have not assessed CUDH and long-term BBB integrity in PLWH. The recent development of the Water-extraction-with-phase- contrast-arterial-spin-tagging (WEPCAST) MRI sequence facilitates in vivo measurement of BBB permeability to small molecules without contrast. We propose using WEPCAST MRI to assess BBB integrity in vivo in 175 PLWH with CUDH and 75 PLWH without CUDH. We will determine the effect of immune cell phenotypes, HIV proviral DNA burden and in vitro alterations to BBB TJ on in vivo BBB integrity in PLWH with and without CUDH. Aim 1: Determine the contribution of immune cell phenotypes to BBB permeability in PLWH with and without CUDH. We will assess BBB permeability via WEPCAST in relation to monocyte and T cell phenotypes implicated in transmigration of activated cells across the BBB. Aim 2: Determine the contribution of immune cells harboring HIV proviral DNA to BBB permeability in PLWH with and without CUDH. We will assess HIV proviral DNA via the Intact proviral DNA assay (IPDA) in monocytes and CD4 T cells in relation to BBB permeability via WEPCAST. Aim 3: Determine mechanisms by which monocytes that harbor HIV proviral DNA increase BBB permeability in PLWH with CUDH. We will assess BBB permeability using an in vitro model of the BBB to elucidate how HIV infected monocytes shape BBB tight junctions. Our in vivo study utilizing a noninvasive BBB integrity measure combined with immunophenotyping, reservoir analysis and a mechanistic approach to determine the effect on BBB TJ are highly innovative. Data will provide support for addressing BBB integrity in PLWH with CUDH and guide investigation of therapeutics aimed to promote BBB health in substance use disorders.