Experimental melanin-induced uveitis: experimental model of human acute anterior uveitis

Experimental melanin-protein-induced uveitis (EMIU), which is also known as experimental autoimmune anterior uveitis, was first described in 1993 by Broekhuyse et al. This experimental uveitis may be induced in certain inbred and outbred rat strains by immunization with bovine ocular melanin. The inflammation shares clinical features with human acute anterior uveitis. The duration of the first episode is approximately 1 month. Spontaneous recovery to a near normal clinical state is the rule, but multiple recurrences are common. Slit-lamp biomicroscopic examination reveals a florid anterior-chamber reaction, with formation of a retro-iridal empyema, fibrin clots and posterior synechiae. At a microscopic level, leukocytic infiltration is first observed in the anterior uvea. Although this tissue remains the site of maximum inflammation throughout an attack, in severe cases, limbitis, vitritis and choroiditis are also observed. Abrogation of EMIU occurs after treatment with anti-CD4 antibody, indicating that the uveitis is controlled by CD4-positive T cells. Several research groups have used EMIU to investigate various aspects of the pathogenesis of acute anterior uveal inflammation, including the participation of different leukocyte subsets, the expression of cell adhesion molecules, cytokines, chemokines and nitric oxide, the role of complement and the impact of apoptosis. In addition, EMIU has also been used to evaluate various biologic interventions with potential implications for the treatment of human disease.