IgA 是黏膜上主要的抗體形式，約佔活體抗體總?的7 成，而位在黏膜上的分?型 IgA（secretory IgA, sIgA）可在第一時間中和病原感染上皮細胞的機會，因此可以有效 地減低病原的感染及下?過敏的發生。以往許多研究?針對中草藥及其組成份活化全身 性免疫反應進?分析，少有研究針對中草藥誘發黏膜免疫反應，尤其是誘發sIgA 進? 分析，而由我們?用分子影像導引之轉?體學平台進?分析之前驅結果中，發現黃耆 （Astragalus membranaceus）可以特?性地活化肺部IgA 的生合成，因此本計畫的主要 目標為分析黃耆及其活性成分增強肺黏膜sIgA 生合成的機轉，並探究將其應用於增強 疫苗黏膜免疫反應之可?性。本計畫擬執?三?，分成下?三個項目執?：（一）分析 黃耆增強肺sIgA 表現之細胞及分生機轉：由前驅試驗中發現，黃耆可以活化肺部nuclear factor-κB 的活性，並增加抗體RNA 及蛋白質的含?，我們認為黃耆是藉由活化轉?起 始的步驟，而增加抗體的生合成，因此本計畫先構築可以報導sIgA（heavy chain）基因 啟動子活性的質體，藉由啟動子的剪裁、elelctrophoretic mobility-shift assay、西方雜合 法等分生試驗，分析黃耆活化sIgA 啟動子轉?起始之主要反應位置、轉?因子的種? 及相關之訊息傳導?徑。（二）以sIgA 啟動子分析系統導引黃耆活性物質的分?：我 們擬分析黃耆之三?皂?、黃酮?、多醣?和胜?蛋白質?成分活化sIgA 啟動子之效 用，再視?同成份進?分?、純化、鑑定結構，而取得純化合物後，擬進一步追蹤純化 合物增強肺部sIgA 表現之分生機轉。（三）黃耆及其活性物質增強疫苗肺部黏膜免疫 反應之應用研究：我們選取呼吸道重要傳染病—??性感冒及肺結核為標的，探究黃耆 及其活性物質是否可以?激?感疫苗及卡介苗在肺黏膜產生專一性的sIgA，增加針劑疫 苗在黏膜的保護?，並探究黃耆及其活性物質之活體機轉。經由本研究的執?，預期可 發現黃耆增強sIgA 表現的活性成份並釐清其機轉，未?應可進一步發展為增強黏膜免 疫反應或併合傳染病疫苗使用之中草藥重要產品的基礎。
IgA is the most abundant immunoglobulin (Ig) in the body that comprises at least 70% of all Ig produced in mammals. IgA is also the principal class of antibodies in secretions and has a critical role in mucosal immunity. Secretary IgA (sIgA) is constitutively released into the lumen via the transport system of the mucosal epithelia and, in turn, prevents invading pathogens from binding to mucosal epithelial cells and neutralizes their toxins. Several studies have shown that medicinal herbs and their constituents exhibit therapeutic effects by stimulating systemic immunity. However, in our preliminary study based on the molecular imaging-guided transcriptomic analysis, we found that Astragalus membranaceus specifically increased the RNA and protein levels of IgA in lung. Therefore, the specific aims of this project are to elucidate and to evaluate the mechanisms and application of A. membranaceus and its constituents on the sIgA production in lung. Items of this project will be: (1) Analysis of the molecular mechanisms of A. membranaceus on the IgA (heavy chain, IgH) gene transcription. We proposed that A. membranaceus might activate the transcriptional initiation of IgH genes. The promoter of IgH gene will be cloned, and promoter activity affected by A. membranaceus will be analyzed. Further nested deletion of promoter will be used to analyze the signal transduction pathway and transcription factors involved in the A. membranaceus regulation. (2) Analysis of active constituents of A. membranaceus based on IgH promoter/reporter system. The polysaccharides, flavonoids, saponins, and polypeptides from A. membranaceus will be analyzed to find which components might be responsible for the activation of IgH promoter. (3) Application of A. membranaceus and its constituents on the improvement of mucosal immunity induced by vaccine. The improvement of mucosal immunity, especially the specific and general IgA titers, of influenza vaccine and BCG, will be evaluated. In conclusion, we will elucidate the molecular mechanisms of A. membranaceus and its constituents on the regulation of IgA production. The application of A. membranaceus and its constituents on the improvement of mucosal immunity of vaccines in lung will be further evaluated.
