The pathogenesis, clinical course, and response to treatment in systemic juvenile idiopathic arthritis (SJIA) differ from other types of juvenile idiopathic arthritis and are similar to other interleukin-1 (IL-1)-mediated diseases.
Interleukin (IL)-1α and IL-1β are proinflammatory cytokines that play a role in many diseases such as rheumatoid arthritis, juvenile rheumatoid arthritis, gout, and periodic inflammatory syndromes, including familial Mediterranean fever and Muckle-Wells syndrome.
Systemic-onset juvenile idiopathic arthritis (JIA) is speculated to follow a biphasic course, with an initial systemic disease phase driven by innate immune mechanisms and interleukin-1β (IL-1β) as a key cytokine and a second chronic arthritic phase that may be dominated by adaptive immunity and cytokines such as IL-17A.
Genomic DNA of 55 Iranian patients with JIA and 140 controls were extracted and typed for IL-1α gene at position -889, IL-1β gene at positions -511 and +3962, IL-1R gene at position Pst-I 1970, and interleikin-1 receptor antagonist (IL-1Ra) gene at position Mspa-I 11100, using polymerase chain reaction with sequence-specific primers method, and compared between patients and controls.
Clinical laboratory data and serum IL-1β of JIA patients were evaluated by medical chart review and enzyme-linked immunosorbent assay (ELISA), respectively.
It also underlines the genetic contribution of IL-1 polymorphisms to the pathogenesis of JIA, as another polymorphism within the IL-1beta may influence the risk of the disease.