C5a anaphylatoxin chemotactic receptor 1 (C5AR1) (C5AR1)

The human C5a receptor 1 (C5AR1), also known as CD88, is a high-affinity G protein-coupled receptor (GPCR) that serves as the primary mediator for the potent proinflammatory anaphylatoxin C5a [Wikipedia, https://en.wikipedia.org/wiki/C5a_receptor]. It is predominantly expressed on the surface of myeloid cells, including neutrophils, macrophages, and monocytes, where its activation triggers critical immune responses such as chemotaxis, degranulation, and the release of inflammatory cytokines [NCBI, https://www.ncbi.nlm.nih.gov/gene/728]. Dysregulation of the C5a-C5AR1 axis is a central driver in various inflammatory and autoimmune conditions, most notably ANCA-associated vasculitis, where it promotes necrotizing inflammation of small blood vessels [Tavneos Pro, https://www.tavneospro.com/mechanism-of-action]. Beyond its role in vasculitis, C5AR1 signaling is implicated in the pathogenesis of sepsis, Alzheimer's disease, and the cytokine storm associated with severe COVID-19 [Cusabio, https://www.cusabio.com/target/C5AR1.html]. Therapeutically, C5AR1 is targeted by small-molecule antagonists like avacopan, which selectively block C5a binding to inhibit neutrophil-mediated tissue damage while preserving the upstream complement functions necessary for host defense [BMJ, https://ard.bmj.com/content/77/Suppl_2/64.2]. This targeted approach offers a significant advantage over broad complement inhibition by reducing the risk of life-threatening infections and providing a steroid-sparing alternative for chronic inflammatory diseases [Patsnap, https://patsnap.com/blog/c5ar1-antagonists/]. Clinical monitoring for drugs targeting C5AR1 often includes assessing liver function and monitoring for signs of serious infection [Tavneos Pro, https://www.tavneospro.com/important-safety-information].

Other names

CD88C5ARC5R1C5AComplement component 5a receptor 1C5a anaphylatoxin receptor

Selective antagonism of the C5aR1 receptor, which prevents the binding of the proinflammatory anaphylatoxin C5a, thereby inhibiting neutrophil activation, migration, and the subsequent inflammatory cascade [Patsnap, https://patsnap.com/blog/c5ar1-antagonists/; Tavneos Pro, https://www.tavneospro.com/mechanism-of-action].