CCL2/CCR2 modulates HIV-associated ischemic stroke by regulating blood brain barrier monocyte recruitment

ABSTRACT HIV infection results in increased susceptibility to ischemic stroke by enhancing the injury volume and decreasing post-stroke recovery. Stroke is the second leading cause of death worldwide with a mortality rate higher than 5 million deaths per year. However, the specific factors involved in HIV-induced potentiation of ischemic stroke

have not been defined. Inflammatory chemokine CCL2 is known to play a crucial role in HIV infection by acting via the CCR2 receptor, inducing inflammatory responses, including the release of CCL5, and enhancing the blood brain barrier (BBB) disruption during ischemic stroke. Importantly, it has been shown that astrocytes are

responsible for the exacerbated CCL2 release post-ischemic stroke. The central hypothesis of this proposal is that astrocyte-specific CCL2/CCR2 signaling modulates HIV-associated stroke severity and functional recovery by regulating monocyte recruitment to the BBB, inflammasome activation, and modulating

innate immune responses. Consistent with this hypothesis, the Specific Aims are: 1) To evaluate the hypothesis that astrocyte-derived CCL2 plays a critical role in the recruitment of proinflammatory HIV-infected monocytes/macrophages into the brain, BBB breakdown, and potentiation of ischemic stroke injury in HIV

infection. 2) To evaluate the hypothesis that therapeutic targeting of the CCR2 and CCR5 receptors protects against ischemic stroke in HIV-infected brain and accelerates functional recovery via astrocyte-specific innate immunity mechanisms. The proposed research will involve a novel conditional and astrocyte-specific CCL2-deficient mice, namely,

CCL2flox/flof;GFAP-Cre conditional knockout mice generated in our lab. Mice will be infected with a mouse adapted to HIV strain called EcoHIV. We will investigate whether conditional ablation of CCL2 in astrocytes can reduce exacerbated neuroinflammatory response. Moreover, we will therapeutically target the CCL2 signaling in

humanized mouse model of HIV infection by using the dual CCR2/CCR5 inhibitor cenicriviroc, which can prevent BBB dysregulation through NLRP3 inflammasome inhibition. Next, we will assess both the acute and long-term effects of cenicriviroc on ischemic stroke outcomes. This proposal is conceptually innovative by being the first to

study mechanism-targeted therapeutic approaches for BBB protection in the context of stroke in HIV infection. The results of this proposal will significantly contribute to a better understanding of the interplay between the recruitment and infiltration of monocyte subsets into the ischemic brain and the severity of ischemic stroke

outcomes in HIV patients. The findings resulting from this proposal will help to establish associated pathways that may be identified as promising new therapeutic targets.