Abstract
Purpose: :
Graves' orbitopathy is a systemic autoimmune disease that is poorly understood. It has been shown that Graves' orbital fibroblasts are phenotypically unique due to increased expression of insulin-like growth factor receptor 1 beta (IGFR1b). The purpose of our study is to determine if there is increased expression of the insulin-like growth factor binding proteins (IGFBP) to further characterize Graves' orbitopathy.
Methods: :
Tissue samples with informed consent were obtained from patients with Graves’ orbitopathy and from patients with no significant past medical history at the Jules Stein Eye Institute. Five Graves' orbitopathy tissue and five normal tissue samples were obtained and analyzed using various biochemical assays including ELISA, western blot, immunostaining, and flow cytometry.
Results: :
Among the seven types of IGFBPs, IGFBP-2 demonstrated significant intensity in the immunostaining of orbital tissue in Graves' patients. There was a notable difference between the stain intensity between Graves' tissue and Normal tissue. IGFBP-2 overexpression in Graves' disease samples was confirmed by using ELISA, western blot and flow cytometry.
Conclusions: :
In the study of Graves' disease, the expression of IGFBPs have not been studied or reported. Previous studies have shown that IGFBP-2 binds to IGF-1 with the greatest affinity among all the IGFBPs. We have found increased expression of IGFBP-2 in tissues of Graves' patients. The overexpression of IGFBP-2 may demonstrate another facet of this complicated disease pathway.
Keywords: autoimmune disease • orbit • growth factors/growth factor receptors