咖啡及其主要成份綠原酸與咖啡酸抑制糖脂毒性誘導之糖尿性腎臟病變

糖尿病腎病變 (diabetic nephropathy, DN) 是末期腎病的主要原因，為全球所重視之議題，研究指出台灣末期腎病盛行率為世界之冠，亦是糖尿病死亡率主因，顯示我國罹患腎病之嚴重程度。目前研究認為由於糖尿病中長期過高的血糖與游離脂肪酸對胰島 β 細胞造成傷害，導致糖脂毒性，在糖尿病腎病作為重要發病機制。先前研究顯示，咖啡萃取物 (coffee extract, CFE) 、綠原酸 (chlorogenic acid, CGA) 、咖啡酸 (chlorogenic acid, CA) 能夠抑制發炎及抗氧化，因此作為本實驗之介入物。而本研究中，動物實驗採用高脂飲食餵養糖尿病基因小鼠，在高血糖及高血脂的環境下加劇糖脂毒性誘導 DN 病況產生，並以此評估三種介入物之影響。介入物組別三者其血液分析顯示無降血糖作用，而在腎功能指標及血脂指標則有下降的趨勢，腎臟組織切片染色的結果中，亦可觀察到介入物有效減緩腎臟之腎絲球變異與腎小管組織的發炎損傷的情形，同時也顯示介入物能夠顯著改善腎臟組織之糖質堆積及延緩纖維化的發生，並降低腎臟內發炎反應，減少氧化壓力，提升腎臟的抗氧化酵素活性，藉此達到腎臟保護的功效。亦透過西方墨點法，證實本實驗介入物能夠抑制發炎因子的表達。由於腎臟分為皮質 (cortex) 與髓質 (medulla)，因此後續細胞實驗模式採用兩種細胞株，其中一株屬於腎臟皮質的腎絲球系膜細胞 MES-13，另一株則是屬於腎臟髓質的腎小管上皮細胞 NRK-52E，兩株細胞皆使用高糖 (high glucose, HG) 模擬糖尿病之生理環境，並藉由油酸 (oleic acid, OA) 模擬 T2DM 患者因糖脂毒性所造成 DN的環境。透過細胞存活率分析、西方墨點法，以評估介入物是否能夠抑制發炎因子之相關機制，並利用過氧化氫酶活性分析及 DCFDA 染色檢測細胞內活性氧多寡，結果證實 CFE、CGA、CA 皆具有降低細胞氧化壓力，降低發炎因子表現的能力。綜合以上，咖啡萃取物 CFE、CGA、CA 之介入能改善糖脂毒性誘導之糖尿性腎臟病變，未來可以開發富含這些植化素之食品作為預防或延緩糖尿性腎病變的健康產業。

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD) and a major global health concern. Research indicates that Taiwan has the highest prevalence of ESRD worldwide, making it the primary cause of diabetes-related mortality and highlighting the severity of kidney disease in the country. Current studies suggest that prolonged hyperglycemia and elevated free fatty acids in diabetes damage pancreatic β-cells, leading to glucolipotoxicity, which is a key mechanism in the development of diabetic nephropathy. Previous research has shown that coffee extract (CFE), chlorogenic acid (CGA), and caffeic acid (CA) possess anti-inflammatory and antioxidant properties, which form the basis for their use as interventions in this study. In this study, diabetic gene mice were fed a high-fat diet to exacerbate glucolipotoxicity under hyperglycemic and hyperlipidemic conditions, inducing DN. This model was used to evaluate the effects of the three interventions. Blood analysis of the intervention groups showed no hypoglycemic effect, but there was a trend towards improved renal function and lipid profiles. Kidney tissue staining results indicated that the interventions effectively mitigated glomerular abnormalities and inflammatory damage in the renal tubules. Additionally, the interventions significantly reduced renal glycogen accumulation, delayed fibrosis, decreased inflammatory responses, reduced oxidative stress, and enhanced antioxidant enzyme activity in the kidneys, thereby providing renal protection. Western blot analysis confirmed that the interventions inhibited the expression of inflammatory factors. Since the kidney is divided into the cortex and medulla, subsequent cellular experiments utilized two cell lines: MES-13, a glomerular mesangial cell line from the renal cortex, and NRK-52E, a tubular epithelial cell line from the renal medulla. Both cell lines were exposed to high glucose to simulate the diabetic physiological environment and oleic acid to mimic the glucolipotoxic conditions of T2DM-induced DN. Cell viability assays and Western blot analyses were conducted to assess the mechanisms by which the interventions inhibited inflammatory factors. Catalase activity assays and DCFDA staining were used to measure intracellular reactive oxygen species (ROS). The results confirmed that CFE, CGA, and CA reduced cellular oxidative stress and the expression of inflammatory factors. In summary, interventions with coffee extract (CFE), CGA, and CA improved diabetic nephropathy induced by glucolipotoxicity. This suggests the potential for developing foods rich in these phytochemicals to prevent or delay diabetic nephropathy, contributing to the health industry.