Ma Chunling, Yang Xiaomin, Lv Qiulan, Yan Zhimei, Chen Zeqing, Xu Daxing, Liu Xiu, Yang Wan, Xing Shichao
Medical Research Center, the Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, 266000, P. R. China.
Department of Obstctrics, the Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, 266000, P. R. China.
Iran J Basic Med Sci. 2020 Jun;23(6):744-750. doi: 10.22038/ijbms.2020.44948.10482.
Hyperuricemia is a risk for cardiovascular and metabolic diseases, but the mechanism is ambiguous. Increased intestinal permeability is correlated with metabolic syndrome risk factors. Intestinal epithelial cells play a pivotal role in maintaining intestinal permeability. Uric acid is directly eliminated into intestinal lumen, however, the mechanism and effect of uric acid on intestinal epithelial cells is poorly explored. Here we carried out an analysis to identify the effect and mechanism of uric acid on intestinal epithelial cells.
IEC-6 was exposed to different concentrations of uric acid to simulate the effect of uric acid on intestinal epithelial cells. Cell viability was determined by MTS assay. Protein content and mRNA were assessed using Western blotting and Q-PCR, respectively. Intracellular ROS was determined using flow-cytometry and fluorescence microscopy. Mitochondrial membrane potential was detected by immunofluorescence using a mitochondrial membrane potential assay kit with JC-1. Small interfering RNA transfection was used to suppress the expression of TLR4.
We found soluble uric acid alone increased the release of ROS, depolarized the mitochondrial membrane potential, up-regulated TSPO, increased the expression of TLR4 and NLRP3, and then activated NLRP3 inflammasome and NF-κB signaling, which further resulted in lower expression of tight junction protein and exerted adverse effects on intestinal epithelial cells. Furthermore, the elevated IL-1β could be restored by silencing of TLR4, indicating soluble uric acid induces inflammation via the TLR4/NLRP3 pathway.
Soluble uric acid exerted detrimental effect on intestinal epithelial cells through the TLR4/NLRP3 pathway.
高尿酸血症是心血管和代谢性疾病的一个危险因素，但其机制尚不明确。肠道通透性增加与代谢综合征风险因素相关。肠道上皮细胞在维持肠道通透性方面起关键作用。尿酸可直接排入肠腔，然而，尿酸对肠道上皮细胞的作用机制和影响尚未得到充分研究。在此，我们进行了一项分析，以确定尿酸对肠道上皮细胞的作用及其机制。
将IEC-6细胞暴露于不同浓度的尿酸中，以模拟尿酸对肠道上皮细胞的影响。采用MTS法测定细胞活力。分别使用蛋白质免疫印迹法和定量聚合酶链反应评估蛋白质含量和信使核糖核酸。使用流式细胞术和荧光显微镜测定细胞内活性氧。使用线粒体膜电位检测试剂盒（JC-1）通过免疫荧光检测线粒体膜电位。使用小干扰RNA转染抑制Toll样受体4（TLR4）的表达。
我们发现，单独的可溶性尿酸会增加活性氧的释放，使线粒体膜电位去极化，上调外周型苯二氮䓬受体（TSPO），增加TLR4和NOD样受体蛋白3（NLRP3）的表达，进而激活NLRP3炎性小体和核因子κB信号通路，这进一步导致紧密连接蛋白表达降低，并对肠道上皮细胞产生不利影响。此外，通过沉默TLR4可恢复白细胞介素-1β（IL-1β）的升高，表明可溶性尿酸通过TLR4/NLRP3途径诱导炎症。
可溶性尿酸通过TLR4/NLRP3途径对肠道上皮细胞产生有害作用。
