Identification of CX3CR1 mononuclear phagocyte subsets involved in HIV-1 and SIV colorectal transmission.

The difficulty to unambiguously identify the various subsets of mononuclear phagocytes (MNPs) of the intestinal has hindered our understanding of the initial events occurring after mucosal exposure to HIV-1. Here, we compared the composition and function of MNP subsets at steady-state and following and viral exposure in human and macaque colorectal tissues. Combined evaluation of CD11c, CD64, CD103, and CX3CR1 expression allowed to differentiate MNPs subsets common to both species. Among them, CD11c CX3CR1 cells expressing CCR5 migrated inside the epithelium following and exposure of colonic tissue to HIV-1 or SIV. In addition, the predominant population of CX3CR1 macrophages present at steady-state partially shifted to CX3CR1 macrophages as early as three days following SIV rectal challenge of macaques. Our analysis identifies CX3CR1 MNPs as novel players in the early events of HIV-1 and SIV colorectal transmission.