TSHR and thromboangiitis obliterans: In TAO, immune tolerance to TSHR, which is specifically recognized by helper T cells and leads to their activation, secreting massive amounts of inflammatory factors and cytokines, is lost; activated helper T cells promote fat formation and hyaluronic acid production and cause connective tissue remodeling, leading to different degrees of orbital fat and extraocular muscle swelling (Smith and Hegedüs, 2017).