CCR5

C-C chemokine receptor type 5 (CCR5, CD195) is a seven-transmembrane Gαi-coupled receptor activated by CCL3, CCL4, CCL5, CCL8 and CCL14, expressed on activated and memory T cells, monocytes, macrophages, dendritic cells and NK cells. CCR5 is pivotal in two biomedical arenas. First, it is the principal co-receptor, together with CD4, for R5-tropic HIV-1 strains during transmission and early infection; the naturally occurring CCR5-Δ32 deletion confers profound resistance to HIV, an observation that inspired maraviroc, an approved CCR5 antagonist for antiretroviral therapy, and the celebrated CCR5-edited (Berlin/London patient) stem-cell cures. Second, CCR5 recruits inflammatory cells to sites of tissue injury: it drives T-cell and macrophage infiltration in rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis and transplant rejection, and CCR5 signaling in neurons and microglia worsens outcomes after stroke and in Alzheimer's disease models. Beyond HIV, CCR5 blockade is being repurposed for immunooncology, as CCR5+ myeloid cells foster metastatic niches.