EYE IN GRAVES DISEASE--ROLE OF ORBITAL FIBROBLASTS

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The consequences of Graves' ophthalmopathy include pain, inflammation, disfigurement, diplopia and loss of vision. At present, treatment options for this debilitating condition are palliative at best. Better approaches to management and improved clinical outcome will not likely be developed until there is a better understanding of the pathogenesis. Histological and histochemical evidence suggests that the fibroblast is the target cell in both Graves' ophthalmopathy (GO) and in the associated skin condition, pretibial dermopathy (PTD). In these conditions, an accumulation of glycosaminoglycans in the affected tissues results in the characteristic clinical abnormalities. The central premise of the original funded proposal was that GO and PTD result from disordered regulation of glycosaminoglycan synthesis by orbital and pretibial skin fibroblasts, and that this abnormality is mediated through immunologic events. Studies performed in the past three years' time have supported this premise, and have helped to elucidate the effector pathway leading to these connective tissue manifestations of Graves' disease. However, events initiating this autoimmune reaction in the orbit and pretibial skin are unknown; studies aimed at elucidating these initiating events form the basis of this grant renewal. it is well known that the TSH receptor (TSH-r0 is the thyroid antigen against which circulating autoantibodies are directed in Graves' disease. Our preliminary data suggests that the TSH-r is also expressed on fibroblasts. The hypothesis to be tested y the proposed experiments is that the TSH-r is an important fibroblast antigen in GO. We intend to determine 1) whether fibroblasts from retroocular connective tissue extraocular perimysial tissue, pretibial skin and abdominal skin differ from each other in the quantity or the modulation of their expression of TSH-r RNA or TSH-r protein; 2) whether the fibroblast TSH-r is recognized by lymphocytes from the orbits of patients with GO; 30 the frequency in GO of a mutation in the first position of codon 52 of the TSH-r, and to assess the immunologic and functional consequences of tahe mutation; and 4) whether in vitro interleukin-1-stimulated fibroblast glycosaminoglycan synthesis, cellular proliferation and expression of particular immunomodulatory proteins can be inhibited by specific anti-IL-1 agents. We intend that these proposed studies will enhance the understanding of initiating events in the pathogenesis of GO, and will lay the groundwork for future clinical trials using anti-cytokine agents in the treatment or prevention of GO. We believe that a better understanding of pathogenesis will lead to the development of improved management strategies to help our patients with this debilitating condition.