C3a is a 77 residue anaphylatoxin that binds to the C3a receptor (C3aR), a class A G protein-coupled receptor. It plays a large role in the immune response. C3a molecules induce responses through the GPCR C3a receptor.

Anaphylatoxins, or complement peptides, are fragments (C3a, C4a and C5a) that are produced as part of the activation of the complement system. [2] Complement components C3, C4 and C5 are large glycoproteins that have important functions in the immune response and host defense. [3]

The pathogenesis of some kidney diseases is closely associated with complement activation, where the C3a/C3a receptor (C3aR) might play a crucial role. C3a/C3aR has dual roles and may exert anti-inflammatory or pro-inflammatory effects depending on …

2015年4月15日 · In this article, we reinvestigate the discovery and original classification of C3a as a proinflammatory mediator and highlight the emerging studies demonstrating anti-inflammatory effects for C3a in the immune response.

C3a is the smaller fragment that is released into the surrounding fluids. C3a can bind to receptors on basophils and mast cells triggering them to release their vasoactive amines (e.g. histamine). Because of the role of these biomarkers in anaphylaxis, C3a is called an anaphylatoxin. C3a is one of the most potent constrictors of smooth muscle ...

C3a drives pro-inflammatory signaling and chemotaxis through binding to its downstream receptor, C3a anaphylatoxin chemotactic receptor (C3aR), and is considered the only ligand for C3aR [51]. As an important neuroinflammation marker, C3aR is highly expressed in microglia and is a key component of the C3/C3a complement cascade response [52,53] .

While there is a body of evidence for its deleterious effects in the acute phase after ischemic injury to the adult brain, C3aR signaling contributes to better outcome in the post-acute and chronic phase after ischemic stroke in adults and in the ischemic immature brain.

2024年11月11日 · C3a is an important component of the complement system, which, through its binding to the C3a receptor, is able to activate a variety of intracellular signaling pathways, thereby affecting cellular function and metabolism.

C3a and C5a anaphylatoxins are cytokine-like polypeptides generated during complement (C) system activation and released at the inflammatory site. They exert several biological activities through binding to the G-protein-coupled receptors C3aR and C5aR, respectively.

Complement component C3 plays a particularly versatile role in this process by keeping the cascade alert, acting as a point of convergence of activation pathways, fueling the amplification of the complement response, exerting direct effector functions, and helping to coordinate downstream immune responses.