The clinical manifestations of Graves' ophthalmopathy (GO) stem from a combination of increased orbital fat and extraocular muscle volume within the orbital space. Fibroblasts residing within these tissues are thought to be targets of autoimmune attack in the disease. Thyrotropin receptor (TSHr) mRNA and functional protein have been demonstrated in orbital fibroblasts from both normal individuals and GO patients, with higher levels present in the latter. Autoantibodies directed against TSHr or the insulin-like growth factor-1 (IGF-1) receptor have been implicated in GO pathogenesis. Evidence from our laboratory suggests that monoclonal TSHr autoantibodies (TRAbs) are potent stimulators of adipogenesis in GO orbital cells. Therefore, it is possible that circulating TRAbs in Graves' patients both stimulate overproduction of thyroid hormones and increase orbital adipose tissue volume. Antibodies to the IGF-1 receptor appear to impact GO pathogenesis through recruitment and activation of T-cells and stimulation of hyaluronan production, processes that play key roles in the development of inflammation and increased orbital tissue swelling. Although originally thought to represent another causative agent, antibodies to extraocular muscles are now generally thought to be secondary to extraocular muscle inflammation and damage.
Primary Hyperparathyroidism is asymptomatic in most patients (PHPT). We report a case of PHPT in a young male patient. He presented with severe pancreatitis due to hypercalcemia and multiple bone lesions resulting in pathological fractures. The patients recovered rapidly after parathyroidectomy.
Increased Thy-1 expression in GO orbital tissues and cultures is likely a consequence of the orbital disease process, reflecting both the presence of increased numbers of Thy-1-positive cells and higher expression on those cells. Adipogenesis itself does not appear to impact Thy-1 expression. Increased expression of this protein in GO could represent an adaptive response to cell injury, in effect limiting disease progression within the orbital adipose/connective tissues.
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