Pathogenesis of juvenile idiopathic arthritis associated uveitis: the known and unknown.

Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatic disease and the most prevalent systemic disorder in children with uveitis. The current prevailing opinion is that JIA is a multifactorial, genetically predisposed autoimmune disorder that can be influenced by environmental factors and infections; the specific pathogenesis of JIA-associated uveitis is not understood, however, nor has the relationship between the eye and joint inflammation been established. Nevertheless, subtypes of JIA that are associated with uveitis, oligoarthritis, polyarticular rheumatoid factor negative, and psoriatic arthritis appear to have common pathogenicity. We summarize our current knowledge regarding the pathogenesis of JIA-associated uveitis and discuss the possible role of immune responses and cytokine involvement, genetic associations, and the influence of external triggers in this disease-an association that is supported by data obtained from arthritis research and experimental uveitis models.