Effect of rh-leptin on the differentiation of orbital preadipocytes in thyroid associated ophthalmopathy

Background Thyroid-associated ophthalmopathy (TAO) is characterized by increased amount of orbital fat tissue.Leptin is a specific adipocytokine,and it may play an important role in the pathogenesis of TAO.Objective The present study investigates the effect of rh-leptin on the differentiation of orbital preadipocytes in subjects suffering from thyroid-associated ophthalmopathy (TAO).Methods The orbital fatty tissue was obtained from 7 patients with TAO during orbital decompression surgery.Orbital preadipocytes were cultured using the explant method and differentiated cells were identified with oil red staining.The subcultured preadipocytes were incubated with different concentrations of rh-leptin,and no rh-leptin was added in the control group.The average optical density of cytoplasm/nucleolus in differentiated adipocytes was measured by oil-red staining to evaluate the influence of different concentrations of rh-leptin on lipid formation of orbital adipocytes.Results Cultured preadipocytes in vitro were identified to be of mesenchymal origin by immunohistochemical staining.The average optical density of cytoplasm/nucleolus was 1.07±0.22,0.80±0.17,0.56±0.11,0.25±0.10,and 0.17±0.08,respectively in the control group,10μg/L of leptin group,50μg/L of leptin group,100μg/L of leptin group and 500μg/L of leptin group,showing a significant difference among the five groups (F=20.64,P=0.00).Compared to the control group,the lipid formation of orbital adipocytes gradually declined in various concentrations of rh-leptin (P＜0.05,P＜0.01).Conclusion Rh-leptin may suppress the differentiation and lipid formation of TAO orbital preadipocytes in vitro in a dose-dependent manner.Leptin may be a feedback modulator in TAO pathogenesis. Key words: thyroid associated ophthalmopathy; leptin; preadipocyte; cell differentiation