Effects and Significance of Dicliptera chinensis Polysaccharide on the Expression of Transforming Growth Factor β1/Connective Tissue Growth Factor Pathway in the Masseter and Head and Neck Skin of Rats With Radiation-Induced Fibrosis.

PURPOSE: To investigate whether Dicliptera chinensis polysaccharide (DCP) can alleviate radiation-induced fibrosis of masseter and head and neck skin. METHODS: SD rats were divided into the control, the irradiation (IR), the IR + low dose DCP (200 mg/kg), and the IR + high dose DCP (400 mg/kg) groups. The head and neck of rats in the last 3 groups received a single dose of 18 Gy X-ray. At 1st, 2nd, 4th week (w) after radiation, haematoxylin and eosin staining were performed on masseter and skin to observe the histopathological changes; immunohistochemistry staining was performed to observe the pathological changes of the skin; Masson staining was performed on masseter and skin to observe the collagen deposition; western blot analysis was used on masseter to calculate the relative transforming growth factor β1 (TGF-β1), connective tissue growth factor (CTGF) expressions; ELISA was used to detect the contents of TGF-β1 and CTGF in skin and the contents of type I and type III collagens in masseter and skin. RESULTS: In terms of skin, compared to the IR group, the IR + high-dose DCP group exhibited relatively smaller changes in skin structure, lower levels of TGF-β1 and CTGF; thinner skin thickness was observed at the 4th w after radiation; and the positive rates of collagen fibre and the optical densities of type I and type III collagens were lower at the 2nd and 4th w. For the masseter, compared to the IR group, the morphological changes were improved and the expression levels of TGF-β1 and CTGF proteins decreased in the 2 DCP dose groups at 2nd and 4th w. CONCLUSION: DCP can reduce the formation and accumulation of type I and type III collagens after IR and ameliorate radiation-induced fibrosis of masseter and skin by down-regulating the expressions of TGF-β1 and CTGF.