Differences in gut microbiota and fecal bile acids between Caucasian and Hispanic children and young adults with ulcerative colitis.

Ulcerative Colitis (UC) is an inflammatory bowel disease (IBD) that has been associated with gut dysbiosis. Changes in the gut microbiome lead to changes in bile acids (BA) metabolism, which changes the BA profiles in patients with UC. We conducted this study to investigate the differences in bile acids and gut microbiota between Hispanic and Caucasian children and young adults with UC. Twenty-seven Caucasian and 20 Hispanic children and young adults with UC were enrolled in the study. BAs were extracted from the subjects' stool samples and analyzed by liquid chromatography-mass spectrometry. Microbial DNA was also extracted from the stool samples to perform 16s rRNA amplicon sequencing. The median levels of cholic acid and taurolithocholic acid were found to be significantly higher in Hispanic children and young adults with UC compared to their Caucasian counterparts. The abundance of the gut microbiota that metabolizes BAs such as Proteobacteria, Pseudomonadaceae, Pseudomonas, Ruminococcus gnavus, and Escherichia coli were also all significantly higher in Hispanic children and young adults as well. The distinct BA profile that we found in Hispanic children and young adults with UC, in addition to the unique composition of their gut microbiome, provide them with a protective gut environment against inflammation, which is contrary to the common believe that Hispanics have worse IBD.

Decreased secondary faecal bile acids in children with ulcerative colitis and Clostridioides difficile infection.

BACKGROUND: Patients with ulcerative colitis (UC) have an increased risk of Clostridioides difficile infection (CDI). There is a well-documented relationship between bile acids and CDI. AIMS: To evaluate faecal bile acid profiles and gut microbial changes associated with CDI in children with UC. METHODS: This study was conducted at Children's Hospital Los Angeles. Faecal bile acids and gut microbial genes related to bile acid metabolism were measured in 29 healthy children, 23 children with mild to moderate UC without prior CDI (UC group), 16 children with mild to moderate UC with prior CDI (UC+CDI group) and 10 children without UC with prior CDI (CDI group). RESULTS: Secondary faecal bile acids, especially lithocholic acid (3.296 vs 10.793, P ≤ 0.001) and ursodeoxycholic acid (7.414 vs 10.617, P ≤ 0.0001), were significantly lower in children with UC+CDI when compared to UC alone. Secondary faecal bile acids can predict disease status between these groups with 84.6% accuracy. Additionally, gut microbial genes coding for bile salt hydrolase, 7α-hydroxysteroid dehydrogenase and 7α/ß-dehydroxylation were all diminished in children with UC+CDI compared to children with UC alone. CONCLUSIONS: Bile acids can distinguish between children with UC based on their prior CDI status. Bile acid profile changes can be explained by gut microbial genes encoding for bile salt hydrolase, 7α-hydroxysteroid dehydrogenase and 7α/ß-dehydroxylation. Bile acid profiles may be helpful as biomarkers to identify UC children who have had CDI and may serve as future therapeutic targets.