- 學位論文
麩醯胺對高糖合併內毒素感染下人類臍靜脈內皮細胞發炎反應之影響
Effects of glutamine on inflammation at high glucose level with endotoxin infection condition in human umbilical vein endothelial cells
摘要
糖尿病是目前常見的慢性代謝疾病之一，而體內的高糖環境則是導致糖尿病併發症發生的重要因子。血液中的葡萄糖可經由葡萄糖轉運子-1 (glucose transporter-1) 進入血管內皮細胞進行代謝，但當細胞無法代謝過多的葡萄糖時，則會產生氧化壓力與氧化傷害，使內皮細胞損傷導致發炎。糖尿病患者體內長期處於慢性發炎之環境，亦會導致細胞損傷，會活化核轉錄因子nuclear factor (NF) - κB，進而激活細胞凋亡路徑，造成內皮細胞凋亡。因高血糖所引發體內之發炎、氧化壓力、內皮細胞損傷之反應，會使糖尿病患者為感染高風險群，可能導致敗血症而死亡。麩醯胺 (GLN) 被視為體內免疫營養素，也是體內合成抗氧化物質glutathione的成分之一，可維持生物體內細胞與器官之功能並降低體內氧化壓力之傷害。 本研究使用人類臍靜脈內皮細胞 (human umbilical vein endothelial cells, HUVECs)，於正常 (5.5 mM) 與高濃度 (11 mM & 22 mM) 的葡萄糖環境下培養24小時後，再給予300 μM 、600 μM 或1000 μM GLN培養12小時，之後再給予細菌內毒素 (lipopolysaccharide, LPS) 刺激四小時，結果發現iNOS、eNOS mRNA在高糖環境下的表現顯著高於控制組；而經LPS刺激後其培養液中NO與IL-8濃度以及p65、IL-1β、IL-8 mRNA的表現顯著高於未刺激LPS組；並且在高糖 (22 mM) 環境中，培養液中NO與IL-8濃度以及iNOS、eNOS、p65、IL-1β、IL-8 mRNA的表現皆會隨著GLN的濃度增加而有下降的趨勢。因此給予高糖合併感染細菌毒素刺激之內皮細胞麩醯胺的補充，可能可藉由調控p65 mNRA 的表現量而降低促發炎因子，減緩對人類臍帶內皮細胞的傷害。
並列摘要
Diabetes mellitus is a common chronic metabolic disease； hyperglycemia is a widely accepted participant in the development and progression of diabetes and its complications. Blood glucose is via glucose transporter-1 (GLUT1) into endothelial cells proceed to metabolism, however excess blood glucose generated oxidative stress and oxidative injury leading to endothelial cell damage, finally presents a chronic inflammatory. Previous reports have indicated that diabetes is a long-term and low grade chronic inflammation leading to cell damage. It may through activate nuclear factor-κB (NF-κB) and apoptotic pathway resulting in apoptosis of endothelial cells.. High glucose induced inflammation, oxidative stress and endothelial damage increase risk of infection for diabetic patients, leading to infect sepsis and death. Glutamine (GLN) is not only an immune nutrient but also a component to synthesize an antioxidant: glutathione. It can maintain normal function of cellsand reduce damage of oxidative stress. Thus, we used human umbilical vein endothelial cells (HUVEC) as a cell model to investigate whether GLN treatment could ameliorate the inflammatory responses in high glucose condition with or without endotoxin stimulation. HUVEC incubated in 5.5 mM glucose (NG) 11 mM glucose (HG-1) or 22 mM glucose (HG-2) for 24 hours, then treated with 300 μM、600 μM or 1000 μM GLN for 12 hours, finally stimulated with lipopolysaccharide (LPS) for 4 hours. The results showed that iNOS and eNOS mRNA in HG groups are significantly higher than NG group. NO and IL-8 secreation and p65, IL-1β and IL-8 mRNA expression are significantly increased after stimulation with LPS in HG groups. High dose GLN treatment lead to decrease NO and IL-8 levels, as well as down-regulating p65, IL-1β and IL-8 mRNA expression, especially in HG group. But GLN did not affect the apoptosis pathway of endothelial cell. These results suggest that, GLN can ameliorate pro-inflammatory factors expression of HUVEC in high glucose combined with LPS condition.
參考文獻
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