Abstract
Autophagy is a highly conserved recycling pathway that promotes cell survival during periods of stress. We previously reported that induction of autophagy through the inhibition of the mechanistic target of rapamycin (MTOR) inhibits HIV replication in human macrophages and CD4+ T lymphocytes (T cells). However, the inhibition of MTOR has modulatory effects beyond autophagy that might affect viral replication. Here, we examined the effect on HIV replication of trehalose, a non-toxic, non-reducing disaccharide that induces autophagy through an MTOR independent mechanism. Treatment of HIV-infected macrophages and T cells with trehalose inhibited infection in a dose dependent manner. Uninfected and HIV-infected macrophages and T cells treated with trehalose exhibited increased markers of autophagy including LC3B lipidation with further accumulation following bafilomycin A1 treatment, and increased levels of LAMP1, LAMP2 and RAB7 proteins required for lysosomal biogenesis and fusion. Moreover, the inhibition of HIV by trehalose was significantly reduced by knockdown of ATG5 Additionally, trehalose down-regulated the expression of CCR5 in T cells, and CD4 in both T cells and macrophages which reduced HIV entry in these cells. Our data demonstrate that the naturally occurring sugar, trehalose, at doses safely achieved in humans inhibits HIV through two mechanisms: 1) decreased entry through the down-regulation of CCR5 in T-cells, and decreased CD4 expression in both T-cells and macrophages; and 2) degradation of intracellular HIV through the induction of MTOR independent autophagy. These findings demonstrate that cellular mechanisms can be modulated to inhibit HIV entry and intracellular replication using a naturally occurring, non-toxic sugar.Importance: Induction of autophagy through inhibition of MTOR has been shown to inhibit HIV replication. However, inhibition of MTOR has cellular effects that may alter HIV infection through other mechanisms. Here, we examined the HIV inhibitory effects of the MTOR independent inducer of autophagy, trehalose. Of note, we identified that in addition to the inhibition of the intracellular replication of HIV by autophagy, trehalose decreased viral entry in human primary macrophages and CD4+ T-cells through the down-regulation of CCR5 in T cells, and CD4 in both T cells and macrophages. Thus, we have shown that trehalose uniquely inhibits HIV replication through inhibition of viral entry and intracellular degradation in the two most important target cells for HIV infection.
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