Study on p-hydroxybenzoic acid on rheumatoid arthritis via inhibiting NF-κB/caspase-1 signaling pathway

探究二肽基肽酶-4抑制剂(dipeptidyl peptidase-4 inhibitors，DPP-4i)维格列汀改善糖尿病诱导心肌细胞的炎性损伤作用机制。

体外培养AC16心肌细胞随机分为空白组、棕榈酸(palmitic acid，PA)组、0.1、1、10 μmol·L⁻¹维格列汀组以及西格列汀组(阳性对照组)。采用CCK-8试剂盒检测细胞存活率；Western blotting检测目的蛋白DPP-4、p-NF-κB、IκB的表达情况；ELISA试剂盒检测炎症因子TNF-α和IL-6表达水平；TUNEL试剂盒检测细胞凋亡情况。

AC16人源心肌细胞经PA处理后，细胞形态改变；CCK-8结果显示细胞存活率下降；Western blotting结果显示NF-κB磷酸化增强，且DPP-4蛋白表达升高；ELISA结果显示炎症因子TNF-α和IL-6表达水平上升；TUNEL阳性比例增多，促进心肌细胞凋亡。维格列汀给药后能有效抑制PA诱导的DPP-4蛋白异常表达，改善心肌细胞形态，并下调NF-κB磷酸化水平。ELISA结果显示维格列汀改善PA诱导的炎症因子TNF-α和IL-6表达水平上升，降低TUNEL阳性比例(P<0.05)。

维格列汀可以有效拮抗PA诱导的心肌细胞炎性损伤，通过抑制NF-κB磷酸化水平，降低胞内炎症因子表达水平与抑制细胞凋亡，从而拮抗糖尿病心肌病诱导的心肌损伤。

Genetics of diabetes mellitus and diabetes complications

To explore the mechanism of vildagliptin, a dipeptidyl peptidase 4 inhibitor(DPP-4i), in improving the inflammatory damage of cardiomyocytes induced by diabetes mellitus. The AC16 cardiomyocytes cultured in vitro were randomly divided into blank group, palmitic acid(PA) group, 0.1, 1, 10 μmol·L⁻¹ vildagliptin group, and sitagliptin group (positive control group). The cell viability was detected by CCK-8 kit. The expressions of DPP-4, p-NF-κB and IκB were detected by Western blotting. The expression level of inflammatory cytokines TNF-α and IL-6 were detected by ELISA kit. TUNEL kit was used to detect cell apoptosis. After PA treatment, the cell morphology of AC16 human cardiomyocytes changed, CCK-8 results showed a decrease in cell survival rate, Western blotting results showed increased phosphorylation of NF-κB and increased expression of DPP-4 protein, and ELISA results showed increased expression level of inflammatory factors TNF-α and IL-6. The increase of TUNEL positive ratio promoted apoptosis of cardiomyocytes. After administration of DPP-4i vildagliptin, it could effectively inhibit the abnormal expression of DPP-4 protein induced by PA, improve the morphology of cardiomyocytes, and down-regulate the level of NF-κB phosphorylation. ELISA results showed that vildagliptin could improve the expression level of PA-induced inflammatory factors TNF-α and IL-6, and reduce the proportion of TUNEL positive(P<0.05). Vildagliptin can effectively antagonize PA-induced inflammatory injury of cardiomyocytes, antagonize myocardial injury induced by diabetic cardiomyopathy by inhibiting the phosphorylation level of NF-κB, reducing the expression level of intracellular inflammatory factors and inhibiting apoptosis.