Background:
Latently HIV-infected CD4+ T cells persist indefinitely through proliferation. We previously showed that inhibition of proliferation and induction of differentiation of the long-lived, self-renewing central (CM) and stem cell memory (SCM) CD4+ T cells can be achieved in ART-treated SIV-infected rhesus macaques (RMs) through modulation of the Wnt pathway. Here, we evaluated a combined approach targeting Wnt and Notch pathways during acute SIV infection of RMs to disrupt viral reservoir establishment.
Methods:
Five RMs were infected i.v. with SIVmac239 before receiving 8 weeks of treatment with the Wnt inhibitor PRI-724 administered subcutaneously daily at 18-20 mg/kg in combination with the Notch inhibitor LY3039478 administered orally at 2.5 mg/kg three times per week. ART was initiated 8 weeks post-infection (wpi) and PBMC were collected longitudinally on ART to FACS sort subpopulations of naïve, SCM, CM, transitional memory (TM) and effector memory (EM) CD4+ T cells. Levels of cell-associated total SIVgag DNA and unintegrated 2-LTR circles were measured by multiplex qPCR in sorted cells. A group of 7 RMs infected with SIVmac239 and treated with ART alone served as controls.
Results:
The combined treatment PRI-724+LY3039478 demonstrated an acceptable safety profile and did not alter plasma viral load dynamics in SIV-infected RMs. After ART initiation, the decay in the SIV 2-LTR circles, that are diluted with proliferation, was greater in the CM (p=0.005 at 12wpi) and TM (p=0.018 at 12wpi, p=0.003 at 20wpi) CD4+ T cells from the PRI-724+LY3039478-treated RMs as compared to controls. The ratio of SIVgag/2-LTR was higher in all subsets of memory CD4+ T cells from the treated RMs versus controls at 8 (p<0.035) and 12wpi (p<0.073). Interestingly, a reduced contribution of CM to the total SIV reservoir in CD4+ T cells was observed in the treated RMs as compared to controls at both 8 and 12wpi (p=0.010 for both). This reduction was attributed to lower levels of SIVgag DNA in CM CD4+ T cells at 12wpi (p=0.048) and decreased frequencies of CM cells within the CD4+ T cell pool at 8 and 12wpi (p=0.004 and 0.018) in PRI-724+LY3039478-treated RMs versus controls.
Conclusions:
This proof-of-concept study suggests that the combined pharmacological modulation of Wnt and Notch pathways during acute SIV infection of RMs impacts viral reservoir seeding by transiently reducing the relative contribution of the CM cells to the peripheral CD4+ T cell compartment and to the pool of the infected CD4+ T cells.