GPR18 (G protein-coupled receptor 18) is an orphan receptor belonging to the rhodopsin-like GPCR family, a class of transmembrane proteins involved in diverse physiological processes. Initially identified through genomic studies, GPR18 remains partially characterized, though emerging evidence links it to immune regulation, inflammation resolution, and neuroprotection. Its endogenous ligands may include lipid-derived molecules like resolvin D1 and N-arachidonoyl glycine (NAGly), suggesting roles in modulating cellular responses to injury or infection. GPR18 is expressed in immune cells (e.g., macrophages, microglia), the central nervous system, and peripheral tissues, implicating it in diseases such as metabolic disorders, neurodegenerative conditions, and cancer.
Antibodies targeting GPR18 are critical tools for studying its expression, localization, and signaling mechanisms. They enable detection of receptor distribution in tissues via techniques like immunohistochemistry or flow cytometry and aid in functional studies to clarify ligand-receptor interactions. Therapeutic potential is also being explored, as GPR18 modulation could influence inflammatory pathways or tumor microenvironments. However, challenges persist due to the receptor’s structural complexity and overlapping ligand specificity with related GPCRs. Current research focuses on validating antibody specificity and optimizing their use in preclinical models to advance mechanistic insights and drug development.