P2X7R: A potential key regulator of acute gouty arthritis

ObjectivesAcute gouty arthritis is an inflammatory disease resulting from the precipitation of long-term hyperuricemia-induced monosodium urate (MSU) crystals in joints, which stimulates the production of interleukin-1beta (IL-1β) and initiates an inflammatory reaction. However, some patients having MSU crystals in the joints never develop acute gouty arthritis, indicating that other predisposing factors are required for the disease onset. This review described the mechanism of production of IL-1β by MSU crystals and other possible factors during a gout attack.MethodsThe relevant English literature on IL-1β secretion stimulated by MSU crystals and other possible factors during acute gouty arthritis flares was searched and carefully reviewed.ResultsMSU crystals lead to the onset of acute gouty arthritis mainly through the activation of Toll-like receptors (TLRs) and NACHT-LRR-PYD-containing protein 3 (NALP3) inflammasome signaling and downstream IL-1β production. The predisposing factors of acute gouty arthritis, such as strenuous exercise, cold, alcolholism, and overeating have a common characteristic inducing dramatic changes of adenosine triphosphate (ATP) in the body. The ATP changes can activate the purinergic receptor P2X ligand-gated ion channel 7 (P2X7R) signaling system to regulate IL-1β secretion.ConclusionsWe hypothesize that acute gouty arthritis is induced by two synergistic effects; one is the stimulation of MSU crystals and the other is the activation of P2X7R signaling pathways by extracellular ATP changes, which together lead to the production of IL-1β and the initiation of acute gouty arthritis. This hypothesis will provide a new avenue for the prevention and treatment of acute gouty arthritis.