Effect of TUDCA on the artery which suffered from the atherosclerosis in ApoE-/- mice

Cholesterol efflux capacity dysfunction in macrophages is thought to be important in atherosclerosis. However, the molecular mechanism underlying this dysfunction remains unclear. Our previous analysis found that the increase of endoplasmic reticulum stress in macrophages during atherosclerotic plaque formation. Here we extended our analysis to ApoE-/- mice fed a high fat diet, some of which were treated with tauroursodeoxycholic acid (TUDCA) and collected the arteries of mice among these three groups (NFD, HFD and HFD+TUDCA) to perform the Bulk-RNA sequencing. There was significantly high expression of matrix metalloproteinase family (MMP9, MMP25, MMP8, MMP12, MMP13 and MMP3), CD68, inflammasome (IL1b, IL18bp, ifi44, ifi204 and Nlrp3), ER stress (Hspa5) and cholesterol transporters (ABCA1 and ABCG1) in the HFD group compared with the NFD group, however, TUDCA rescued the high expression of the above DEGs to different degrees. As shown by the expression levels of ifi204, Nlrp3, Il1b, and Il18, inflammasome activation was evident in the arteries of the HFD group compared to the NFD group. The ER stress inhibitor TUDCA not only decreased expression of the ER stress-related gene Hspa5 but also down-regulated inflammasome activation (as seen with the expression levels of ifi204, ifi44, NLRP3 and IL1b) in the artery of TUDCA treated mice compared with mice without drugs. Male ApoE-/- mice (8 weeks old, n =60) were obtained from HFK Bioscience Company (Beijing, China). All the ApoE-/- mice were randomly divided into 3 groups: Group 1: control group (normal fat diet, NFD); Group 2: high-fat diet (HFD); Group 3: HFD + TUDCA. A random number table was used for mouse randomization. Group 1 mice were fed with a diet of 5% fat without cholesterol, whereas the other groups were fed with an HFD (16% fat and 0·25% cholesterol). After 8 weeks of HFD feeding, one group of HFD-treated mice was intragastric administration with 1000 mg/kg of TUDCA once daily (HFD+TUDCA group) for 4 weeks, whereas the NFD-treated mice and other group of HFD-treated mice were treated with an equal volume of saline (NFD or HFD group) for 4 weeks. After 4 weeks of TUDCA or saline treatment, the mice were anaesthetized intraperitoneally with 3% pentobarbital sodium (40 mg/kg) and sacrificed. The aortic tissues from the ascending aorta to the ileal bifurcation were immediately gathered for bulk-RNA sequencing.