Harnessing Innate Immunity to Control the Neuroinflammatory HIV Reservoir - HIV-1 infects CD4+ T-cells, macrophages (MΦ) and microglia (MG) and affects all organs that are infiltrated by permissive cells establishing viral reservoirs, including the brain. Even if treated with combined anti-retroviral therapy (cART) neurocognitive impairment (NCI) develops in about 50% of people with HIV (PWH). HIV-1 triggers an interferon (IFN) response and type I IFNs (IFNα/β) can in principle control HIV-infection of CD4+ T- cells and MΦ by interfering with several stages of the viral lifecycle. IFNβ exerts anti-viral and anti-inflammatory effects and appears to at least transiently control HIV infection in the brain and periphery. We and others observed that the endogenous, protective HIV/SIV-induced IFNβ response in the brain is transient but it is unclear why and how HIV overcomes the IFN response. However, we also found: 1) Treatment of infected MΦs with IFNβ diminished HIV-1 production; 2) The ISG IRF7 exerts negative feedback on IFNβ expression;, 3) IFNβ protected neurons from toxins of HIV-stimulated MΦ; 4) An intranasal IFNβ treatment prevented neuronal damage in a transgenic mouse model of NeuroHIV; 5) We identified the interferon-stimulated gene (ISG) CCL4 as a critical mediator of neuroprotection by IFNβ and found that astrocytes are the major source. Based on this data, we hypothesize that IFNβ treatment in conjunction with cART can be utilized to restrict HIV- infection or resurgence, formation of reservoirs and persistence in the brain as well as neuronal injury. To test our hypothesis, we will employ primary human peripheral blood cells (PBMC), iPSC-derived MG, astrocytes, 2D CNS and a novel microfluidic 3D CNS-on-a-chip tissue culture model, the latter including neurons, astrocytes, microglia, pericytes, brain endothelial and immune cells spatially organized in a Mimetas device (Mimetas Co, Gaithersburg, MD). We will use novel dynamic single cell imaging, transcriptomic and functional approaches, to examine cell type specific effects of IFNβ relevant to viral infection and restriction, neuroinflammation and neuronal toxicity and protection in the presence and absence of cART. Three Specific Aims (SA) are proposed: 1. Dissect the impact of IFNβ on HIV-infected microglia and PBMC with and without cART; 2. Define the role of astrocytes in the neuroprotective IFNβ response to HIV with and without cART, and 3. Assess in a novel 3D Blood/BBB/CNS-on-a-chip model, if IFNβ treatment can restrict HIV-1 infection, reservoir formation and neurotoxicity in the presence and absence of cART. The Specific Aims will test the hypothesis that IFNβ can restrict HIV-1 infection and reservoir formation in CD4+ T-cells, MΦ and MG, prevent HIV- and cART induced injury to neurons and the blood-brain-barrier, and suppress resurgence of an established HIV infection when cART is interrupted. The Specific Aims will test the mechanisms of IFNβ action with and without cART in a cell type-specific approach, including induction of anti-viral and anti-inflammatory ISGs and neurotrophic factors, activation of the pro-survival kinases Akt and ERK1/2, and suppression or reduced activity of infection-, inflammation- and neurotoxicity-promoting factors, such as p38 MAPK and NFkB.
