Promoting effects of insulin-like growth factor-1 on proliferation of orbital fibroblasts derived from thyroid associated ophthalmopathy

Background

Thyroid associated ophthalmopathy (TAO) is an autoimmune disease.Current research on the pathogenesis focuses on common autoantigen.Insulin-like growth factor-1 receptor (IGF-1R) is necessary for the function of IGF-1 , also IGF-1 plays an important role in signaling pathway of thyroid stimulating hormone receptor (TSHR).

Objective

This study was to investigate the effects of IGF-1 on the proliferation, expression of IGF-1R and TSHR on cultured orbital fibroblasts (OFs) derived from TAO.

Methods

Human orbital tissue was obtained from 17 TAO patients who received orbital adipectomy and 4 normal controls who received cosmetic surgery in West China Hospital from March 2016 to June 2016.OFs were cultured by explant culture with DMEM/F12 containing 5% fetal bovine serum and identified by immunochemistry.The OFs were treated with different concentrations of IGF-1.IGF-1 at different concentrations (0, 50, 100, 125 μg/L) was added into the medium, respectively, and the proliferation of the cells (absorbancy) was detected by MTS.The percentages of IGF-1R and TSHR expressions in the cells were assayed by flow cytometry.

Results

Cultured cells appeared to be spindle-like in shape and grew well with abundant cytoplasm.The characteristics of the cells derived from TAO patients were consistant with normal ones.The cells showed the positive response for vimentin and absent respose for desmin, S-100, myoglobin and cytokeratin.The proliferative values of OFs were gradually elevated with the increase of IGF-1 dose in both TAO group and normal group (F_group=219.639, P<0.001; F_{concentration}=17.752, P<0.001) with the optimal effects in 100 μg/L IGF-1.The expression levels of IGF-1R in the OFs were (0.009 1±0.008 7)%, (0.095 3±0.023 3)%, (0.083 7±0.022 7)% and (0.070 9± 0.024 1)% in the TAO group, and those in the normal group were (0.002 3± 0.000 6)%, (0.009 3±0.001 2)%, (0.007 3±0.001 5)% and (0.008 3±0.001 2)% after treatment of 50, 100, 125 μg/L IGF-1.The expression levels of IGF-1R were significantly higher after treatment of 50, 100 and 125 μg/L IGF-1 than those treatment of 0 μg/L IGF-1 in both TAO group and normal group, and the expression levels of IGF-1R in the OFs were significantly increased in the TAO group compared with the normal group (all at P<0.05). No statistical difference was seen in the TSHR expression between the TAO group and normal group after treatment of 0, 50, 100 and 125 μg/L IGF-1(F_group=0.133, P>0.05; F_{concentration}= 0.004, P>0.05).

Conclusions

IGF-1 can promote the proliferation of OFs and up-regulate the expression of IGF-1R in OFs.However, IGF-1 dose not play a regulating effect on the expression of TSHR in OFs.

Thyroid associated ophthalmopathy; Fibroblasts, orbit/metabolisms; Insulin-like growth factor-1/metabolism; Receptor, insulin-like growth factor-1/metabolism; Receptors, thyrotropin/metabolism; Cell proliferation/drug effects; Cells, cultured