**3.6 Apoptosis and thyrocyte oxidative stress induced by TSHR antibodies**

The induction of cell proliferation via stimulating- monoclonal antibodies (mAbs) shown in thyrocyte stimulation studies with TSHR-mAbs that have been conducted with cAMP. Some neutral monoclonal antibodies (mAbs) have been identified as stimulating multiple stress signals and apoptosis induced. These antibodies are responsible for activation of multiple oncogenes, including p53, p73 and Reactive oxygen species (ROS). In addition, endoplasmic reticulum stress protein (gp98) is induced and the expression of heat shock proteins (p27 and p107), hemaoxygenase (HO) and superoxide dismutase (SOD) is further activated and supported.These data support stress signals in the thyroid cells of Graves' Disease.

A morphologic staining (annexin V and propidium iodide) and a quantitative flow cytometry test [42] confirmed the cell death caused by apoptosis, and is likely to confirm the previously described histological evidence that thyroid tissue apoptosis is found in GD patients. These observations have revealed that stress signaling cascades have been involved although oxidative stress alone or cell-specific signaling molecules induced such apoptosis remain unclear. These results also indicated the ability of neutral TSHR monoclonal antibodies (TSHR-mAbs), which is known to activate inborn and bystander immune reactivity via DNA release from apoptotic cells [43], to aggravate the local infiltration in a thyroid. This same phenomenon may be associated with Graves' orbitopathy as these cells were abundantly expressed by activation-induced fibroblast death.

#### **3.7 Humoral immunity**

The GD Rodents have shown humoral immunity against other TSHRimmunized antigens, unless outbred animals like hamsters have been used, to show intrathyroid infiltrate. This implies that GD is an intricate genetic disorder, usually associated with autoimmune thyroiditis. AITD is not known for the presence of pendrin antibodies, sodium iodides symporters [44, 45], thyroxine, triiodothyronin [46], tubulin, megalin, calmo-modulin and DNA, or DNA-related proteins [47–49]. The IGF-1 receptor is widespread in B cells and in fibroblast from GD patients, although over-expressed. In activation of the thyrocyte, synergism between antibodies to TSHR and the IGF-1 receptor was suggested. That requires further research as TSH and IGF-1 or insulin are commonly known to induce proliferation of thyroid cells.
