| Abstract: | 心臟缺血(Ischemia)、缺氧(Hypoxia)會造成許多心臟疾病，如心肌梗塞、充血性心臟衰竭(congestive heart failure)、動脈硬化(atherosclerosis)、冠狀阻塞(coronary occlusion)等。心臟缺血會導致心肌細胞減少氧氣的供給進而造成心房顫動 (atrial fibrillation, AF)，使心肌細胞損傷，進而促使心臟重組 (cardiac remodeling)、纖維化(fibrogenesis)，最終導致心衰竭(heart failure)。而有許多文獻指出，心房顫動會增加缺氧(hypoxia)的相關指標及血管新生指標因子的表現，進而促使缺氧誘導因子(hypoxia-inducible factor, HIF)的大量表現。而心房顫動的另一個特徵，則是具有心臟纖維化(cardiac fibrosis)及細胞外基質(exteracelluar matrix, ECM)改變以及心肌細胞肥大(hypertrophy)的特徵。此特徵會促使纖維化的部位會有大量的細胞外基質的沉積。而目前也有研究指出當心肌處與缺氧壓力下，會刺激心臟細胞活化低氧誘導因子來調控相關基因表現，以保護心肌細胞。但是以目前的研究，在心肌缺氧壓力下所導致的心房顫動進而促使心臟重構及纖維化的因果關係中，其作用的相關機轉仍不清楚。而目前本實驗室發現醛固酮(Aldosterone)可以透過已知醛固酮受體(mineralocorticoid receptor, MR)，進而調控下游的MAPK pathway，促使 TGF-β1, collagen type IA, collagen type IIIA及α-SMA等纖維化因子的大量表現。然而，在缺氧環境下，心臟重構與醛固酮受體及腎素-血管收縮素-留鹽激素系統與纖維化的詳細機制仍不清楚。因此，本計畫擬於第一年利用本實驗室已經建立的細胞缺氧系統( hypoxia Incubator chamber 及CoCl2或DMOG刺激)，探討在缺氧環境下，或與醛固酮共同處理下，其醛固酮受體及腎素-血管收縮素-留鹽激素系統及細胞外基質相關成份如collagen type IA, collagen type IIIA, α-SMA及細胞外基質分解蛋白 matrix metalloproteinases (MMPs)的表現為何? 而我們擬於第二年進一步探討缺氧環境下，或與醛固酮共同處理下，心肌細胞其纖維化指標及發炎因子如TGF-β1, CTGF, PAI-1, HSP-47, IL-1, IL-6 及TNF-α等因子的mRNA及其蛋白表現為何 ? 而我們也擬進一步探討其相關訊息傳遞路徑如MAPK pathway的表現。而目前已有文獻指出，一些抗氧化藥物如 NAC或類黃酮對於發炎或纖維化有明顯的抑制效果。因此，本計畫擬於第三年，進一步觀察抗氧化藥物如 NAC或類黃酮對於由缺氧環境下，或與醛固酮共同處理下，所造成心肌細胞的纖維化指標或發炎因子的抑制效果，並進一步探討其相關訊息傳遞路徑。
Ischemia (reduced blood flow) and hypoxia (reduced oxygen) is mainly subject in cardiology, occur in myocardial infarction, congestive heart failure, atherosclerosis, coronary occlusion. The deficient oxygen supply may result in myocardial dysfunction, promote cardiac remodeling and fibrogenesis and leading to development of heart failure on the ventricular level and dysrhythmias like atrial fibrillation, which is raised by selective atrial ischemia. In atrial fibrillation, the increased expression of hypoxic and angiogenic markers were found, and also proven the up-regulation of the HIF pathway and paralleled by fibrogenesis in atrial myocardium. The cardiac remodeling, characterized by cardiac fibrosis, exteracelluar matrix (ECM) deposition and hypertrophy is the important pathological feature of the failing heart. Abundant deposition of ECM is found in the maturation of fibrosis, and the ratio of collagen type I increases in the fibrosis. Moreover, in respond to hypoxia, several HIF-1α-regulated cardioprotective genes have been reported. However, little evidence of a direct relationship between hypoxia and fibrosis marker expression in HL-1 atrial cell lines. In the past year, we found that Aldosterone and mineralocorticoid receptor induced the fibrosis marker through MAPK pathway in the HL-1 atrial cell lines. However, the relationship between hypoxia and fibrosis marker expression in HL-1 atrial cell lines were still unknown. Therefore, in the first year of this study, we propose to analyze the effect of hypoxia (hypoxia Incubator chamber or CoCl2, DMOG treatment) on renin–angiotensin system (RAS) expression in HL-1 atrial cell lines. In the second year of this study, we propose to analyze the mRNA and protein expressions of fibrosis marker and inflammatory markers after hypoxia or aldosterone treatment and further to investigate the signal pathways by hypoxia system. In the third year of this study, we propose to analyze the mRNA and protein expressions of fibrosis marker and inflammatory markers by NAC or flavonoid treatment and further investigate the signal pathways for regulated hypoxia affect fibrosis marker production. |
