探討蓮蓬對反式、反式-2,4-癸二烯醛誘導肺纖維母細胞過度增生與分化之抑制作用

反式、反式-2,4-癸二烯醛(trans, trans-2,4-decadienal , tt-DDE)是烹飪油煙中主要醛類，源自於油酸和其他不飽和脂肪酸氧化。在過去文獻中，人類支氣管上皮細胞暴露tt-DDE會導致DNA損傷、細胞毒性和氧化壓力；然而，tt-DDE對肺纖維母細胞(lung fibroblasts)的毒性作用仍不清楚。已知富含槲皮素-3-葡萄醣醛酸(quercetin-3-glucuronide, Q3G)的蓮蓬萃取物(lotus seedpod extracts, LSE)已被證實具有抗氧化、抗衰老、抗糖化和保肝活性，近期Q3G也證實具保護肺纖維母細胞免於細菌脂多醣的損傷，故本研究除了旨在探討tt-DE對肺纖維母細胞的影響，也針對LSE及 Q3G可能的護肺潛力進行分析。首先利用tt-DDE鼻腔給藥建立發炎性肺損傷小鼠模式，結果顯示LSE及Q3G發揮更優於臨床肺炎治療藥物dexamethasone (Dex)能改善tt-DDE損傷的肺功能指標，對於肺水腫和支氣管肺泡灌洗液中的總蛋白濃度（發炎細胞浸潤的標誌）也有降低的效果。肺組織病切染色顯示LSE及Q3G能改善tt-DDE所致肺組織結構異常、肺泡破壞指數及纖維化表徵，且減少肺組織細胞增生因子Ki-67和α-平滑肌動蛋白(alpha-smooth muscle actin,α-SMA)的表現，代表LSE及Q3G改善tt-DDE促進細胞過度增生(hyperplasia)和纖維母細胞-肌纖維母細胞轉化(fibroblast to myofibroblast transition, FMT)作用。此外，以tt-DDE處理MRC-5細胞以探討LSE的護肺分子機制，無細胞毒性劑量的LSE 表現出改善tt-DDE誘導的細胞增生和細胞週期(cell cyle) S期比例提升，並進一步抑制FMT的過程。這些結果證明富含Q3G的LSE校正細胞週期運行和FMT調節分子，進而抑制肺纖維化過程中肌纖維細胞的增生和分化，也為tt-DDE致肺毒性作用提供潛在機制。

Trans, trans-2,4-decadienal (tt-DDE) is the predominant aldehyde found in cooking oil fumes, originating from the oxidation of oleic acid and other unsaturated fatty acids. Exposure of tt-DDE to human bronchial epithelial cells has been reported to cause DNA damages, cytotoxicity, and oxidative stress. However, the toxic effect of tt-DDE on lung fibroblasts s is still unknown. Lotus seedpod extracts (LSE), rich in quercetin-3-glucuronide (Q3G), has been indicated to possess antioxidant, anti-age, anti-glycative, and hepatoprotective activities. Recently, it has been demonstrated that the protective effects of Q3G on human lung fibroblasts MRC-5 cells from lipopolysaccharide. This study aimed to investigate the effects of tt-DDE exposure on lung fibroblasts, and the possible lung-protective potentials of LSE and Q3G against tt-DDE’s toxicity. Firstly, tt-DDE exposed intranasally to mice was demonstrated to impair pulmonary functions and cause weight loss, which were rescued by LSE and Q3G. In vivo, LSE and Q3G significantly alleviated the development of lung injury, which may result from inhibiting the tt-DDE-induced lung edema accompanying interstitial pneumonia and total protein concentration in bronchoalveolar lavage fluid (BALF), a hallmark of inflammatory cell infiltration. Histologically, there was a dose-correlated decrease in the tt-DDE-induced lung injury and fibrotic lesion under LSE supplements. LSE treatments apparently alleviated the tt-DDE-mediated an increase in expression of Ki-67, a known marker of cell hyperplasia, along with that of alpha-smooth muscle actin (α-SMA), representing cell differentiation and fibroblast-to-myofibroblast transition (FMT). Furthermore, MRC-5 were treated with tt-DDE to investigate the lung-protective effects of LSE intervention. Noncytotoxic doses of LSE exhibited the capability on inhibition of cell hyperplasia induced by tt-DDE with a decrease on S phase of cell cycle, and further downregulated FMT process. These data imply that Q3G-enriched LSE regulates the cell cycle progression and FMT, which in turn led to reduce hyperplasia and differentiation of lung fibroblasts in pulmonary fibrogenesis, and also provide a mechanism for lung-toxic effect of tt-DDE.