C5AR1 and arthritic joint disease: The G-protein-coupled receptor C5a anaphylatoxin chemotactic receptor 1 (C5aR) belongs to the rhodopsin family of seven transmembrane-containing GPCRs and has been a topic of interest in the last couple of decades due to its relevance in several inflammatory pathologies, such as asthma, arthritis, sepsis, and more recently Alzheimer’s disease and cancer1–3.