| 摘要: | 懸浮微粒（Particulate Matter, PM）是一種重要的空氣污染物，由懸浮在空氣中的各種複雜有機或是無機成分混合組成。PM會通過呼吸系統進入肺部造成肺部損傷，甚至PM可能藉由粘膜纖毛運輸系統從肺部進入人體腸道，而這也被認為和腸道發炎有關。已經有研究指出，PM的暴露和腸道不良反應有關，包括發炎反應、腸道通透性增加和腸道上皮細胞增生。然而PM與腸道發炎的關係與相關分子機制仍未釐清，因此在本次研究中，我們想要探討PM對結腸上皮（WiDr）細胞的不良反應的分子機制。結果發現，在暴露後的不同時間，PM誘導細胞內ROS的產生，使得細胞內抗氧化酵素NQO-1以及HO-1表現增加，以及發炎反應的活化，其中包括了NF-κB途徑中p65和IκBα的磷酸化，並伴隨著促進發炎的細胞激素IL-8蛋白質表現的增加，而抗氧化劑可以抑制PM引起的發炎反應，因此我們推測PM引起的ROS可以活化NF-κB所調控的發炎途徑。同時我們也利用BrdU分析，確認PM的暴露會引起腸道細胞發生細胞增殖，以及AKT磷酸化的發生，而抗氧化劑與AKT抑制劑都可以抑制PM引起的細胞增生。最後，我們發現PM處理下，細胞自噬（Autophagy）相關的蛋白質LC3-II、Beclin1以及P62的表現量增加，抗氧化劑以及Autophagy的抑制劑3MA會減少PM引起的發炎反應以及細胞增生。總結而言，暴露PM可能會對腸道造成損傷，主要藉由在結腸上皮細胞中引起ROS增加進而造成發炎反應、抗氧化機制活化、細胞增殖以及細胞自噬的產生。;Particulate Matter (PM), as the main air pollutants, is a mixture composed of inorganic and organic components in the air. PM can enter the lungs through the respiratory system and cause lung damage. Also, PM may enter the human intestines from the lungs via the mucociliary transport system, which is also considered to be related to intestinal inflammation. Several studies report that PM exposure is associated with intestinal diseases, including inflammation, increased intestinal permeability and epithelial cell proliferation. However, it is still unclear the relationship and molecular mechanisms between PM and intestinal adverse effects. In this study, we would like to clarify the molecular mechanisms underlying adverse effects associated PM in human colonic epithelial (WiDr) cells. Our result sowed that PM increased the levels of ROS leading to antioxidant enzymes NQO-1 and HO-1 productions, and NF-κB mediated inflammatory response activation. The phosphorylation of p65 and IκBα occurred and then triggered sequentially downstream inflammatory cytokine IL-8 production after PM exposure in WiDr cells. Antioxidants N-acetylcysteine (NAC) pretreatment can reduce the PM-induced IL-8 production. Therefore, our results indicated that ROS involved in PM-induced NF-κB inflammation pathway in colonic epithelial cells. Meanwhile, we found that PM exposure increased intestinal cell proliferation by using BrdU analysis. AKT phosphorylation was also increased after PM exposure. AKT inhibitor, MK2206, pretreatment reduced the PM-increased cell proliferation. Finally, we found that under PM treatment, the expression of autophagy-related proteins LC3-II, Beclin1, and P62 increased. Antioxidants and Autophagy inhibitor 3-Methyladenine (3MA) can reduce IL-8 production and cell proliferation after PM treatment. In summary, PM exposure may cause adverse effects to the intestinal epithelial cells through ROS mediated inflammation, activation of antioxidant mechanisms, cell proliferation, and the production of autophagy. Taken together, our result will help to clarify the underlying molecular mechanisms of adverse effects induced by PM, which may provide scientific evidences to reduce the impacts of PM on public health in the future. |
