Uveitis (intraocular inflammatory diseases) is the cause of approximately 10% of severe visual handicap in the United States. Current therapy is based on systemic corticosteroid, with or without second line agents such as cyclosporine A or anti-metabolites. Serious adverse effects of these drugs are the impetus for development of less toxic and more specific therapies for uveitis. Experimental autoimmune uveitis (EAU) is a well-characterized animal model of human uveitis and constitutes a unique experimental system for use in validating efficacy of treatment modalities against uveitis. Our efforts to develop effective anti-uveitis therapies have relied on 2 strategies: (i) Development of dendritic cell vaccine against uveitis: Studies of monkey and rodent EAU have led to identification of the retinal proteins, S-Antigen and IRBP, as putative autoantigen of uveitis. Our approach is to develop a therapeutic vaccine against uveitis based on tolerance induction to S-Antigen, IRBP and/or other putative uveitogens (recoverin, opsin). We had previously shown that STAT pathways are differentially activated as dendritic cells (DC) differentiate from precursor (pDC) to immature (iDC) and finally to mature DC (mDC). In this study, we have used wild-type, STAT1-deficient or STAT6-deficient DC to investigate the role of STAT1 and STAT6 in inducing DC to produce cytokines that promote inflammation (IL-12 and IL-23) or those that have anti-inflammatory functions (IL-10 and IL-27). Our studies reveal that while STAT1 is required for DC maturation and necessary for secretion of the anti-inflammatory cytokines IL-10 and IL-27 by mDC, STAT6 exerts negative regulatory constraints on DC maturation and promotes production of pro-inflammatory cytokines (IL-12 and IL-23). This new understanding now allows for a rational basis for generating DC that selectively produces tolerogenic or immunogenic cytokines. Our ultimate goal is to load highly enriched tolerogenic DCs with immunopathogenic epitopes of IRBP or S-Antigen for use as therapeutic vaccines against uveitis. (ii) Intracellular protein therapy for inhibition of uveitis: Our research over the past few years has documented potential role of SOCS proteins in protection of retinal cells from hypoxia, light damage and inflammation. However, therapeutic value of SOCS proteins is severely limited by technical difficulty of delivering these regulatory proteins inside the cell where their cognate target proteins reside. To circumvent this major huddle constraining therapeutic use of transcription factors and other soluble intracellular proteins, we exploited the new genetic engineering strategy by which proteins can be made deliverable into cells by fusing their coding sequences to 12 amino acid membrane-translocating sequences (MTS). Using this strategy we have generated a membrane-translocating SOCS1 protein, delivered it into macrophage cells and demonstrated its ability to inhibit STAT1 signaling pathway in these cells. We are now characterizing the efficiency of delivery of this protein into retinal cells and its eventual use to inhibit experimental uveitis.
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