Macrophage Polarization in AIDS: Dynamic Interface between Anti-Viral and Anti-Inflammatory Macrophages during Acute and Chronic Infection.

Monocyte and macrophage inflammation in parenchymal tissues during acute and chronic HIV and SIV infection plays a role in early anti-viral immune responses and later in restorative responses. Macrophage polarization is observed in such responses in the central nervous system (CNS) and the heart and cardiac vessels that suggest early responses are M1 type antiviral responses, and later responses favor M2 restorative responses. Macrophage polarization is unique to different tissues and is likely dictated as much by the local microenvironment as well as other inflammatory cells involved in the viral responses. Such polarization is found in HIV infected humans, and the SIV infected animal model of AIDS, and occurs even with effective anti-retroviral therapy. Therapies that directly target macrophage polarization in HIV infection have recently been implemented, as have therapies to directly block traffic and accumulation of macrophages in tissues.