Pharmacological modulation of the Wnt/β-catenin pathway inhibits the proliferation of long-lived latently-infected memory CD4+ T-cells in ART-suppressed SIV-infected macaques

The major obstacle to human immunodeficiency type 1 (HIV-1) eradication is a reservoir of latently-infected cells that persists despite long-term antiretroviral therapy (ART) and is maintained through cellular proliferation. Long-lived memory CD4+ T-cells with high self-renewal capacity such as central memory T-cells (CM) and T memory stem cells (SCM) are major contributors to the viral reservoir in HIV-infected individuals on ART. The Wnt/β-catenin signaling pathway regulates the balance between self-renewal and differentiation of SCM and CM T-cells and pharmacological manipulation of this pathway offers an opportunity to interfere with the proliferation of latently-infected cells. Here, we evaluated in vivo a novel approach to inhibit self-renewal of SCM and CM CD4+ T-cells in the rhesus macaque (RM) model of SIV infection. We used an inhibitor of the Wnt/β-catenin pathway, PRI-724, that blocks the interaction between the co-activator CREB binding protein (CBP) and β-catenin, resulting in the cell fate decision to differentiate rather than proliferate. Our study shows that PRI-724 treatment of ART-suppressed SIVmac251-infected RMs: (i) was well tolerated, with blood counts, liver enzymes, and renal function within normal limits and no alteration of tri-lineage hematopoiesis observed in bone marrow, (ii) resulted in decreased proliferation of SCM and CM T-cells, (iii) modified the SCM and CM CD4+ T-cell transcriptome towards a profile of more differentiated memory T-cells, and (iv) reduced SIV-DNA levels in CM and TFH CD4+ T-cells in the lymph nodes, but did not decrease the overall viral reservoir size. This work is the first demonstration in vivo that pharmacological modulation can effectively target T cell stemness in long-lived memory CD4+ T-cells, and represents a potential strategy to reduce HIV persistence. Examination of CD4+ T-cell subsets under treatment with PRI-724, 8 macaques were treated and 4 were untreated as controls.