Aminooxy-Acetic Acid Inhibits Experimental Autoimmune Uveitis by Modulating the Balance between Effector and Regulatory Lymphocyte Subsets

Purpose: A small molecular compound, aminooxy-acetic acid (AOA), has been shown to modulate experimental autoimmune encephalomyelitis (EAE). The current study was designed to investigate whether AOA has a similar effect on the development of experimental autoimmune uveitis (EAU) and to further explore underlying mechanisms of this drug.

Methods: EAU was induced in C57BL/6J mice by immunization with interphotoreceptor retinoid-binding protein peptide 651-670 (IRBP 651-670). AOA (500pg or 750 mu g) or vehicle was administered by intraperitoneal injection from day 10 to 14 after EAU induction. The severity was assessed by clinical and histological scores. The integrity of the blood retinal barrier was detected with Evans Blue. Frequencies of splenic Th1, Th17 and Foxp3(+) Treg cells were examined by flow cytometry. The production of cytokines was tested by ELISA. The mRNA expression of IL-17, IFN-gamma and IL-10 was detected by RT-PCR. The expression of p-Stat1 and NF-kappa B was detected by Western Blotting.

Results: AOA was found to markedly inhibit the severity of EAU, as determined by clinical and histopathological examinations. AOA can relieve the leakage of blood retinal barrier (BRB). Functional studies found a decreased frequency of Th1 and Th17 cells and an increased frequency of Treg cells in EAU mice as compared with controls. Further studies showed that AOA not only downregulated the production of the proinflammatory cytokines including IFN-gamma and IL-17 but also upregulated the expression of an anti-inflammatory cytokine such as IL-10, which might be caused by inhibiting the expressions of p-Stat1 and NF-kappa B.

Conclusion: This study shows that AOA inhibits the severity and development of EAU by modulating the balance between regulatory and pathogenic lymphocyte subsets.