Abstract

Minocycline attenuates HIV infection and reactivation in human CD4+ T cells

G. Szeto¹, S. Barber², R. Siliciano³, J. Clements<sup>1

1</sup>Johns Hopkins University School of Medicine, Department of Molecular and Comparative Pathobiology, Baltimore, United States, ²Booz Allen Hamilton, Rockville, United States, ³Johns Hopkins University School of Medicine, Department of Medicine, Baltimore, United States

Background: In our SIV-macaque model of HIV CNS disease, minocycline reduces inflammation, CNS disease and virus replication in the brain. Based on these observations, minocycline is currently in multi-center clinical trials to treat HIV CNS disease. In this study, we examine minocycline’s effect on HIV in human CD4+ T cells and their response to activation by co-stimulation.
Methods: CD4+ T lymphocytes were selected from PBMCs using magnetic-beads. Resting CD4+HLADR- T cells were isolated using bead depletion and cell sorting. FACS analysis assessed expression of GFP, markers of activation and proliferation. Real-time RT-PCR was used to quantitate HIVgag mRNA in supernatants.
Results: Minocycline causes a dose-dependent decrease in single-cycle infectivity of a psuedotyped HIV-GFP in CD4+ T cells. In a post-integration CD4+ T cell model of latency, minocycline reduces the expression of reporter GFP from reactivating cells, but not the frequency of reactivation in the population.
Minocycline treatment of CD4+ T cells significantly reduces the response to CD3/CD28 co-stimulation. Treated cells show attenuated progression of activation, including failure to down-regulate CD69 and CD45RA, and failure to up-regulate many activation/proliferation markers, including CD25 and LFA-I. Further, minocycline decreases cytokine production by activated cells and CD28 surface expression, suggesting minocycline may reduce the ability of CD4+ T cells to receive co-stimulatory signals.
Similar effects on activation/proliferation are seen in HIV-infected, resting CD4+HLADR- T cells isolated from patients on suppressive HAART regimens. Minocycline treatment decreases HIV gag mRNA in pooled supernatants after activation of these resting cells by co-stimulation, frequently below the limit of detection for the assay.
Conclusions: Our observations suggest that minocycline attenuates both HIV reactivation and spread by decreasing the responsiveness of human CD4+ T cells to activation signals. These data suggest minocycline may be useful as an adjunctive therapy in patients on HAART.
Supported by NIH MH070306, NS055648.