Abstract [Download PDF] [Read Full Text]
Insulin-like growth factor-1 (IGF-1) participates in the regulation of the biological activity of cells.Researches showed that the serum IGF-1 level is significantly raised in the patients with Graves diseases.Thyroid associated ophthalmopathy (TAO) is one of Graves diseases, and orbital adipose cells are the target cells of thyroid autoantigens.However, whether IGF-1 is associated with TAO is still unclear.
This study was to investigate the expressions of IGF-1 in both circulating blood and orbital adipose tissue in TAO patients.
A retrospective cohort study was performed.Eighty-six TAO patients were enrolled in West China Hospital of Sichuan University from August 2009 to February 2014.According to the clinical activity score criteria(CAS), the patients were divided into active stage (CAS≥4, 35 patients) and inactive stage (CAS<4, 51 patients). Eighty-six health adult persons were enrolled as the controls.The periphery blood of 3 ml was collected from each subject to detect the serum IGF-1 level by ELISA.Orbital adipose tissues were obtained during the surgery from 35 TAO patients and 35 patients with benign orbital tumor or orbital adipose prolapse from August 2009 to February 2014.The histopathological examination of orbital adipose tissue was carried out to evaluate the pathological characteristics, and the expression of IGF-1 in orbital adipose tissue was assessed by immunochemistry.This study protocol was approved by Ethic Committee of West China Hospital of Sichuan University, and informed consent was obtained from each subject before entering the cohort.
The mean serum IGF-1 level was (0.862±0.026)ng/ml in the TAO patients, and that in the normal controls was (0.767± 0.480)ng/ml, without significant difference between them (P=0.281). The mean serum IGF-1 level was (0.877±0.355)ng/ml and (0.803±0.031)ng/ml in active stage and inactive stage of patients, respectively, and no significant difference was found between them (P=0.834). IGF-1 expression located in cellular membrane and cytoplasm.The expressing intensity of IGF-1 in orbital adipocytes was significantly enhanced in the TAO patients with the positive rate of 74.29%, and that in the controls was 45.46%, showing a statistical difference between the two groups (χ2=5.289, P=0.021).
Serum IGF-1 level dose not rise in TAO patients, but the expression of IGF-1 in orbital adipocytes up-regulates, indicating that mature orbital adipocytes of TAO are regulated mainly by IGF-1.