Purpose: Polymorphism and mutations of human leukocyte antigens (HLAs) and calreticulin are risk factors for uveitis. Here, we sought to determine the therapeutic effects of Clarstatin, a cyclic peptide antagonist of the HLA shared-epitope-calreticulin interaction, in experimental autoimmune uveitis (EAU) models.
Methods: Mice were injected with Clarstatin intraperitoneally and its effect was compared to that of corticosteroid. EAU was evaluated clinically and histologically. Ocular infiltration of CD45+ hematopoietic cells and splenocyte CD4+ expression were determined using immunofluorescence and flow cytometry (fluorescence-activated cell sorting [FACS]). ELISA was used to measure the ocular level of the proinflammatory cytokines.
Results: Clarstatin significantly ameliorated the severity of EAU in the C57BL/6J mild and the B10.RIII severe mice models. There was a significant dose and time-dependent decrease, in the range of 30% to 80%, in the clinical score (P < 0.05), histological score (P < 0.05), and number of retinal and spleen CD45+ cells (P < 0.05 and P < 0.001, respectively), a comparable effect to corticosteroid. Clarstatin reduced the intraocular levels of interleukin 6 (IL-6; P < 0.05) and monocyte chemoattractant protein-1 (MCP-1; P < 0.01) by 41% and 59%, respectively.
Conclusions: Systemic delivery of Clarstatin significantly improved mild and severe EAU. Its potential anti-inflammatory therapeutic effects represent a novel mode of treatment in ocular inflammation. It may also be a relevant treatment modality in systemic autoimmune conditions in which calreticulin plays a role in their pathogenesis.