Targeting beta-catenin to disrupt the T memory stem cell reservoir

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 DESCRIPTION (provided by applicant): ABSTRACT While antiretroviral therapy (ART) greatly reduces the mortality and morbidity of HIV infection, viral rebound quickly ensues if ART is stopped. As such, a cure remains a key priority in HIV/AIDS research. The main obstacle to curing HIV infection is the persistent reservoir of latently infected cells that causes rebound of viremia if ART is interrupted. Recent work demonstrates that CD4+ T memory stem cells (TSCM) - a subset of memory CD4+ T cells that exhibits enhanced self-renewal as well as the ability to differentiate into more mature memory subsets - may represent a key component of the reservoir of latently infected memory CD4+ T cells that persists in ART-treated HIV-infected individuals. The objective of this proposal is to test a novel therapeutic intervention aimed at selectively blocking the self- renewal of the long-lived CD4+ TSCM reservoir, thereby disrupting overall virus persistence in memory CD4+ T cells. We hypothesize that phylogenetically-conserved, stem cell-specific signaling pathways that regulate the "stemness" (i.e., multipotency, self-renewal, long-term persistence) of hematopoietic stem cells and are active in CD4+ TSCM are essential to promote long-term viral persistence under ART. We propose to pharmacologically target the Wnt/beta-catenin pathway to interfere with the self-renewal and drive the differentiation of latently infected CD4+ TSCM. We will determine the impact of this immunological intervention on (i) the size and anatomic distribution of the virus reservoir and (ii) the kinetics of viral rebound once ART is interrupted.Of note, this approach is not dependent on the induction of virus reactivation. This work will be carried out in SIV-infected, ART-suppressed rhesus macaques (RMs), in whom we can test novel interventions and perform more rigorous and invasive sampling than would be possible in HIV-infected humans. In Aim 1, we will test the selective beta-catenin inhibitor PRI-724 in healthy RMs to define an optimal dosing strategy for both biological signal of efficacy as well as toxicity. In Aim 2, we will investigate the impact of beta-catenin inhibition in reducing the size f memory CD4+ T cell reservoirs in SIV-infected ART-suppressed RMs. In Aim 3, we will perform a functional analysis of the impact of beta-catenin inhibition on virus reservoirs by analyzing the dynamics of viral rebound after treatment interruption. The proposed studies are highly innovative and will provide critical new information on the biology of viral persistence in memory CD4+ T cells. The results of this project may lead to a translational research program focusing on novel CD4+ TSCM specific strategies for HIV eradication that has the potential to have a transformative impact on HIV treatment and cure.