Atorvastatin improved ulcerative colitis in association with gut microbiota-derived tryptophan metabolism

Aims: Atorvastatin is a commonly used cholesterol-lowering drug that possesses non-canonical anti-inflammatory properties. However, the precise mechanism underlying its anti-inflammatory effects remains unclear. Materials and methods: The acute phase of ulcerative colitis (UC) was induced using a 5 % dextran sulfate sodium (DSS) solution for 7 consecutive days and administrated with atorvastatin (10 mg/kg) from day 3 to day 7. mRNA-seq, histological pathology, and inflammatory response were determined. Intestinal microbiota alteration, tryptophan, and its metabolites were analyzed through 16S rRNA sequencing and untargeted metabolomics. Key findings: Atorvastatin relieved the DSS-induced UC in mice, as evidenced by colon length, body weight, disease activity index score and pathological staining. Atorvastatin treatment reduced the level of pro_x0002_inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α). Atorvastatin also relieved the intestinal microbiota disorder caused by UC and decreased the proliferation of pernicious microbiota such as Akkermansia and Bacteroides. Atorvastatin dramatically altered tryptophan metabolism and increased the fecal contents of tryptophan, indolelactic acid (ILA), and indole-3-acetic acid (IAA). Furthermore, atorvastatin enhanced the expression level of aryl hydrocarbon receptor (AhR) and interleukin-22 (IL-22) and further promoted the expression level of intestinal tight junction proteins, such as ZO-1 and occludin, in colitis mice. Significance: These findings indicated that atorvastatin could alleviate UC by regulating intestinal flora disorders, promoting microbial tryptophan metabolism, and repairing the intestinal barrier. To investigate the function of atorvastatin on ulcerative colitis, female C57BL/6 J mice were used as experimental animals. The normal group was treated by gavage with the vehicle alone (0.5% CMC-Na).The model group was treated by gavage with 5 % DSS solution for consecutive 7 days. The atorvastatin group was treated by gavage with 10 mg/ kg atorvastatin. Atorvastatin was administered strictly once daily for 5 days in a volume of 0.2 mL from day 3 to day 7. We then performed gene expression profiling analysis using data obtained from RNA-seq.