The replication of human immunodeficiency virus type 1 in macrophages is enhanced after phagocytosis of apoptotic cells.

Clearance of apoptotic cells increases macrophage secretion of antiinflammatory mediators and might modulate viral replication in human immunodeficiency virus (HIV) type 1-infected macrophages. To study this, primary macrophages were infected with HIV-1 and exposed to apoptotic cells. It was found that phagocytosis of apoptotic cells potently enhanced HIV-1 growth. The peptide Arg-Gly-Asp-Ser, which binds to integrin receptors, inhibited the uptake of apoptotic cells and the subsequent enhancement of HIV-1 replication. Viral replication was preceded by increased secretion of transforming growth factor (TGF)-beta1 and partially reverted by anti-TGF-beta1 antibodies. Moreover, anti-TGF-beta1 antibodies inhibited HIV-1 replication in macrophages not exposed to apoptotic cells. A positive correlation was observed between TGF-beta1 production and HIV-1 growth, and the addition of TGF-beta1 amplified HIV-1 replication in macrophages from low TGF-beta1 producers. The findings suggest that TGF-beta1 favors HIV-1 replication in macrophages and that the clearance of apoptotic cells by HIV-1-infected macrophages contributes to persistent viremia in patients infected with HIV-1.