Double Knock–Out Mice; CXCR3 and CCR5 Deficiency Develop Experimental Autoimmune Uveitis

Abstract

Purpose: : Chemokines are supposed to be a key component of the leukocyte recruitment process. CXCR3 and CCR5 are chemokine receptors preferentially expressed in T helper cells type 1 (Th1). Last year, we reported CXCR3–deficient mice (CXCR3KO) developed more severe disease than wild–type C57BL/6 mice in experimental autoimmune uveitis (EAU). In this study, we investigated whether EAU is inducible in CXCR3 and CCR5 deficient (double knock–out, DKO) mice.

Methods: : EAU was induced by immunizing wild–type C57BL/6 mice (n=25) and DKO C57BL/6 mice (n=15) with specific immunodominant peptides of human interphotoreceptor retinoid binding protein (hIRBP–p) with complete Freund's adjuvant (CFA). Fundoscopic evaluation of EAU was performed and the disease severity was scored at day 21. At day 22, all mice were sacrificed and the eyes were harvested for histopathological grading. Statistical analyses were performed by Mann–Whitney’s U–test.

Results: : Clinically, EAU developed in both wild–type and DKO mice. Fundoscopy revealed that 64% of wild–type mice developed EAU with average clinical EAU–score of 0.9±1.3 (average ± standard error), as compared to 87% of DKO mice with EAU–score of 2.3±1.8. DKO mice had significantly more severe diseases than wild–type mice (p<0.01). Histopathological analyses of the eye tissues revealed more severe infiltration of granulocytes in eyes of DKO mice than eyes of wild–type mice. Histopathological grading of disease in DKO mice was significantly higher than those of wild–type mice (0.8±1.1 vs. 2.7±1.8, p<0.01).

Conclusions: : Deficiency of CXCR3 and CCR5 in vivo did not prevent the development of EAU. That, rather, aggravated ocular inflammation. We thought this might be due to strong compensational mechanism of granulocytes for impairment of Th1 cells.

Keywords: autoimmune disease • inflammation • uveitis-clinical/animal model