綠茶多酚EGCG抑制Sphingosine 1-Phosphate 誘導頰黏膜纖維母細胞 CTGF 表現之研究

Abstract

結締組織生長因子 (connective tissue growth factor，CTGF) 與許多人類的疾病，如肺臟、肝臟、腎臟及牙齦的纖維化有關，在這些疾病中CTGF都有增加的情況。目前認為導致口腔黏膜下纖維化症 (oral submucous fibrosis，OSF) 的主因為檳榔中的檳榔素 (arecoline) 和檳榔中的粗糙纖維在嚼食的過程中對頰黏膜所造成的物理性創傷長時間慢性刺激口腔黏膜所形成。先前的研究也指出檳榔素可刺激人類頰黏膜纖維母細胞 (human buccal mucosa fibroblasts) 大量表現CTGF，且嚼食檳榔者其組織切片的免疫螢光化學染色也可見到有大量CTGF的表現。 鞘氨醇磷酸脂 (Sphingosine-1-phosphate，S1P) 是一種低分子量的溶血磷脂質 (lysophopholipid，LPL) ，由血小板製造，在傷口癒合的過程中會被血小板釋放至受傷的組織內，具有減少血管通透性進而達到穩定血管的作用，近來的研究顯示特發性肺纖維化 (idiopathic pulmonary fibrosis, IPF) 的病人S1P有顯著的增加，除此之外S1P也與腎臟及肝臟的纖維化有關。在嚼食檳榔的過程中對頰黏膜所造成的物理性創傷吸引血小板的聚集並且釋放出S1P， 可能與口腔黏膜下纖維化症的形成有關。 本研究發現人類頰黏膜纖維母細胞在S1P的刺激下，具有隨濃度及時間表現CTGF的特性，JNK抑制劑SP600125可以抑制S1P誘發CTGF的表現，綠茶中的茶多酚EGCG可藉由抑制JNK pathway來達到抑制S1P誘發頰黏膜纖維母細胞的CTGF表現。期望未來可以利用EGCG，藉由抑制CTGF的表現來治療或抑制口腔黏膜下纖維化症的發生及進展。

Connective tissue growth factor (CTGF) overexpression has been widely shown to be associated with many human diseases such as pulmonary, renal, hepatic, and gingival fibrosis. OSF is the result of persistent chemical irritation and microtrauma to oral mucosa from areca nut (AN). Previous immunohistochemical studies showed overexpression of CTGF protein in OSF tissues. In vitro study showed that arecoline enhanced CTGF expression in normal buccal mucosa fibroblasts. Sphingosine-1-phosphate (S1P) is a low-molecular weight lysophospholipid (LPL) stored in platelets. S1P is released by platelets upon stimulation and was engaged in wound healing and coagulation process by decreasing vascular permeability and enhancing vascular stabilization. S1P is elevated in patients with IPF (idiopathic pulmonary fibrosis), correlates with the lung function and mediates EMT (epithelial to mesenchymal transition). Recent evidence suggests that S1P also plays an important role in renal fibrosis, pulmonary fibrosis and liver fibrosis. Microtrauma could lead to the release of S1P. In our study, S1P can induce CTGF overexpression in normal buccal mucosa fibroblasts in a time- and dose-dependent manner and can be inhibited by JNK inhibitor SP600125. We also find green tea extracts, EGCG, can down-regulate CTGF expression by attenuating JNK pathway. In the future, our expectation is to find out a drug that can reverse or inhibit the fibrotic process during the development of oral submucous fibrosis.