CCR1

CCR1, or C-C chemokine receptor type 1, is a human chemokine receptor belonging to the family of G protein-coupled receptors. It is part of the CC chemokine receptor group and is encoded by the CCR1 gene. The receptor is expressed on various leukocytes, including monocytes, subsets of T lymphocytes, eosinophils, basophils, and mast cells, and its expression can be upregulated in inflammatory conditions.

CCR1 binds several CC chemokines, notably CCL3 (MIP-1α), CCL3L1, CCL5 (RANTES), CCL7 (MCP-3), CCL14 (MCP-4), and CCL15 (MIP-1δ). Ligand binding activates Gi protein signaling, leading to intracellular calcium mobilization, inhibition of adenylyl cyclase, and downstream pathways such as MAP kinases, which promote chemotaxis and cell activation. Through these signals, CCR1 directs the recruitment of myeloid cells and certain T cells to sites of inflammation, contributing to host defense and tissue homeostasis.

Clinical and research relevance: dysregulation of CCR1 signaling has been linked to chronic inflammatory and autoimmune diseases, including rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis, and has been implicated in cancer-associated inflammation in experimental models. Therapeutically, CCR1 has been explored as a target for anti-inflammatory therapy, with several small-molecule antagonists evaluated in preclinical and clinical studies. Outcomes have been variable, reflecting redundancy within the chemokine network and compensatory pathways.

Structure and nomenclature: like other chemokine receptors, CCR1 is a seven-transmembrane G protein-coupled receptor. In immunology resources, CCR1 is sometimes referred to by the CD191 designation. Genetic variation in CCR1 and its ligands can influence receptor expression and function, shaping individual inflammatory responses.