Glycosaminoglycans (GAGs), which include chondroitin sulfate (CS), dermatan sulfates (DS), heparan sulfate (HS), heparin (H), keratan sulfate (KS), and hyaluronic acid (HA), are a group of linear, polyanionic heteropolysaccharides. The GAGs chains, except for those of hyaluronic acid, are covalently attached to core proteins, forming proteoglycans (PGs). PGs/GAGs are present at the cellular level as elements of the cell membrane and intracellular granules. They are also components of the ground substance of the extracellular matrix. These macromolecules are involved in cell adhesion, migration, and proliferation. Alterations in GAGs metabolism may influence the pathogenesis of many disorders, including Graves' disease. Graves' disease is an autoimmune thyroid pathology characterized by hyperthyroidism, thyroid hyperplasia, as well as ophthalmopathy and/or pretibial myxedema. The pathogenesis of these extrathyroidal manifestations involves fibroblast activation and increased glycosaminoglycan synthesis and accumulation. Disturbances in GAGs metabolism in tissue are associated with qualitative and quantitative GAGs alterations in Graves' patients' serum and urine. Although the mechanisms leading to the development of orbital and/or skin complications in the course of Graves' disease have not been fully elucidated, it is postulated that they depend on both immunological disturbances and the hyperthyroid state.
Summary: The alterations in GAGs metabolism connected with Graves' disease could lead to systemic changes in the proprieties of the extracellular matrix.