Expression of the mannose receptor CD206 in HIV and SIV encephalitis: a phenotypic switch of brain perivascular macrophages with virus infection.

We examined the expression of the mannose receptor CD206 by perivascular macrophages (PVM) in normal human and monkey brains and in brains of HIV-infected humans and of monkeys infected with simian immunodeficiency virus (SIV). Depletion of brain PVM in SIV-infected monkeys by intrathecal injection of liposome-encapsulated bisphosphonates eliminated CD206-expressing cells in the brain, confirming their perivascular location and phagocytic capacity. In vivo labeling with bromodeoxyuridine in normal uninfected and SIV-infected macaques in combination with CD206 immunostaining revealed a CD206+-to-CD206- shift within pre-existing PVM during SIV brain infection and neuroinflammation. These findings identify CD206 as a unique marker of human and macaque PVM, and underscore the utility of this marker in studying the origin, turnover and functions of these cells in AIDS.