Inhibition of human immunodeficiency virus type 1 infection in macrophages by an alpha-v integrin blocking antibody

Macrophages are key cells for HIV infection and HIV spreading inside the organism. Macrophages cultured in vitro can be successfully infected after differentiation with cytokines such as macrophage colony stimulating factor (M-CSF). In the monocyte to macrophage differentiation process with M-CSF, αv-integrins are upregulated concomitantly with the capacity of HIV to generate a productive virus infection. In the present study we show that an anti-αv antibody, 17E6, inhibited HIV-1 infection of primary macrophages. The effect of 17E6 on HIV-1 BaL replication in acutely infected macrophages was dose-dependent, with a 50% effective concentration (EC50) of 17 ± 2 μg/ml in the absence of cytotoxicity. Similarly, a monoclonal antibody targeting the αvβ6 integrin (14D9.F8) also inhibited HIV-1 BaL infection in this cell type. 17E6 reduced the detection of HIV-1 BaL proviral DNA in acutely infected macrophages, but was completely ineffective against HIV-1 BaL production in chronically infected macrophages, suggesting that 17E6 inhibited HIV infection at an early stage of the virus cycle. Finally, a small molecular weight antagonist of the αvβ6 integrin, EMD 409849, reduced HIV replication at subtoxic concentrations. Therefore, our results suggest that αv-containing integrins could play a role in HIV replication in macrophages and suggest that small-molecular-weight compounds might interfere with HIV replication in macrophages through the interaction with αv integrins.