Gallstone Formation Follows a Different Trajectory in Bariatric Patients Compared to Nonbariatric Patients

Since obese patients form cholesterol gallstones very rapidly after bariatric surgery, in patients who did not form gallstones during preceding years, we hypothesized that gallstone formation follows a different trajectory in bariatric patients compared to nonbariatric patients. We therefore analyzed the lipid composition of gallbladder bile derived from 18 bariatric gallstone patients and 17 nonbariatric gallstone patients (median (IQR) age, 46.0 (28.0–54.0) years; 33 (94%) female) during laparoscopic cholecystectomy using an enzymatic and lipidomics approach. We observed a higher concentration of total lipids (9.9 vs. 5.8 g/dL), bile acids (157.7 vs. 81.5 mM), cholesterol (10.6 vs. 5.4 mM), and phospholipids (30.4 vs. 21.8 mM) in bariatric gallstone patients compared to nonbariatric gallstone patients. The cholesterol saturation index did not significantly differ between the two groups. Lipidomics analysis revealed an interesting pattern. Enhanced amounts of a number of lipid species were found in the gallbladder bile of nonbariatric gallstone patients. Most striking was a fivefold higher amount of triglyceride. A concomitant ninefold increase of apolipoprotein B was found, suggesting secretion of triglyceride-rich lipoproteins (TRLs) at the canalicular pole of the hepatocyte in livers from nonbariatric gallstone patients. These findings suggest that gallstone formation follows a different trajectory in bariatric patients compared to nonbariatric patients. Impaired gallbladder emptying might explain the rapid gallstone formation after bariatric surgery, while biliary TRL secretion might contribute to gallstone formation in nonbariatric patients.

Characterization of The Microbiome In Bile From Normal Human Gallbladders

Background: Scientists previously believed that bacteria could not grow in bile, which is rich in bacteriostatic compounds such as bile acids. Therefore, the biliary tract was considered to be a sterile environment. However, high-throughput (i.e., amplicon) sequencing analysis methods have recently been used to discover the bacterial flora in gallbladder bile in brain-dead patients with normal gallbladders. In a bacterial flora analysis targeting the 16S ribosomal gene, a specific flora was present in the bile of normal gallbladders. However, these results were not obtained from truly healthy individuals. Therefore, the aim of this study was to analyze the microbial flora of bile collected from pathologically normal gallbladders that were surgically removed from patients with hepatobiliary pancreatic diseases who had normal liver function.Results: All 12 bile samples obtained from the gallbladders had negative culture results, although a bacterial flora was detected in all samples via 16S ribosome gene analysis. The composition of the bacterial flora was very simple, and the Firmicutes, Proteobacteria, and Actinobacteria phyla were identified in all samples. Based on 16S rRNA gene profile analysis, the composition ratio accounted for more than 80% of the total number of reads. The Anaerobacillus, Delftia, Bacillus, Ralstonia, Ochrobactrum, Acidovorax, and Curvibacter genera were detected in all 12 samples. Based on 16S rRNA gene profile analysis, at the genus level, Anaerobacillus and Delftia accounted for 58.62%–87.63% of the identified bacteria in each sample. Conclusions: In this study, the bacterial flora in the gallbladder bile was not diverse. Contrary to previous reports, few bacteria belonging to the Bacteroidetes phylum were detected. The functional significance of the gallbladder bacterial flora requires further investigation.

Free fatty acids and triglyceride change in the gallbladder bile of gallstone patients with pancreaticobiliary reflux

Background Pancreaticobiliary reflux (PBR) causes chronic inflammation of the gallbladder mucosa and changes in the bile components, which are known to promote gallstone formation. This study aimed to investigate the bile biochemistry changes in gallstone patients with PBR and provide new clues for research on the involvement of PBR in gallstone formation. Methods Patients undergoing surgery for gallstones between December 2020 and May 2021 were eligible for inclusion. The bile biochemistry (including amylase, lipase, triglyceride, cholesterol, free fatty acids [FFAs], alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase [ALP], and γ-glutamyl transferase [γ-GT]) of the included gallstone patients was analysed to determine correlations with PBR. Results In this study, 144 gallstone patients who underwent surgery were enrolled. Overall, 15.97 % of the patients had an increased bile amylase level, which was associated with older age and significantly higher bile levels of ALP, lipase, triglyceride, and FFAs. Positive correlations were observed between amylase and lipase, triglyceride, FFAs levels in the gallbladder bile. However, the bile levels of triglyceride, FFAs, and lipase were positively correlated with each other only in the PBR group and showed no significant correlation in the control (N) group. In addition, elevated bile FFAs levels were found to be an independent risk factor for gallbladder wall thickening. Conclusions In conclusion, PBR-induced increase in FFAs and triglyceride in the gallbladder bile is a cause of gallstone formation, and an increase in bile ALP suggests the presence of cholestasis in PBR.

Liver X Receptor β regulates bile volume and the expression of Aquaporins and Cystic Fibrosis Transmembrane Conductance Regulator in the gallbladder

The gallbladder is considered an important organ in maintaining digestive and metabolic homeostasis. Given that therapeutic options for gallbladder diseases are often limited to cholecystectomy, understanding gallbladder pathophysiology is essential in developing novel therapeutic strategies.Since Liver X Receptor β (LXRβ), an oxysterol-activated transcription factor, is strongly expressed in gallbladder cholangiocytes, the aim was to investigate LXRβ physiological function in the gallbladder. Thus, we studied the gallbladders of WT and LXRβ-/- male mice using immunohistochemistry, electron-microscopy, qRT-PCR, bile duct cannulation, bile and blood biochemistry and duodenal pH measurements.LXRβ-/- mice presented a large gallbladder bile volume with high duodenal mRNA levels of the Vasoactive Intestinal Polypeptide (Vip), a strong mediator of gallbladder relaxation. LXRβ-/- gallbladders, showed lower mRNA and protein expression of Aquaporin-1, Aquaporin-8 and Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). A cystic fibrosis-resembling phenotype was evident in the liver showing higher serum cholestatic markers and the presence of reactive cholangiocytes. For LXRβ being a transcription factor, we identified 8 putative binding sites of LXR on the promoter and enhancer of the Cftr gene, suggesting Cftr as a novel LXRβ regulated gene. In conclusion LXRβ was recognized as a regulator of gallbladder bile volume through multiple mechanisms involving CFTR and Aquaporins.

Astragalus Polysaccharides Ameliorate Diet-Induced Gallstone Formation by Modulating Synthesis of Bile Acids and the Gut Microbiota

Cholesterol gallstone (CG) disease has relationships with several metabolic abnormalities. Astragalus polysaccharides (APS) have been shown to have multiple benefits against metabolic disorders. We attempted to uncover the effect and mechanism of action of APS on diet-induced CG formation in mice. Animals were fed a chow diet or lithogenic diet (LD) with or without APS supplementation. The effect of APS on CG formation was evaluated. The level of individual bile acids (BAs) in gallbladder bile and ileum were measured by liquid chromatography-tandem mass spectrometry. Real-time reverse transcription-quantitative polymerase chain reaction and western blotting were used to assess expression of the genes involved in BA metabolism and the enterohepatic circulation. Cecal contents were collected to characterize microbiota profiles. APS ameliorated LD-induced CG formation in mice. APS reduced the level of total cholesterol, bile acid hydrophobicity index and cholesterol saturation index in gallbladder bile. The protective effect of APS might result from reduced absorption of cholic acid in the intestine and increased hepatic BA synthesis. APS relieved the LD-induced activation of the intestinal farnesoid X receptor and decreased ileal expression of fibroblast growth factor 15. In the liver, expression of cytochrome P450 (Cyp) enzyme Cyp7a1 and Cyp7b1 was increased, whereas expression of adenosine triphosphate-binding cassette (Abc) transporters Abcg5 and Abcg8 was decreased by APS. APS improved the diversity of the gut microbiota and increased the relative abundance of the Bacteroidetes phylum. APS had demonstratable benefits against CG disease, which might be associated with enhanced BA synthesis and improved gut microbiota. Our results suggest that APS may be a potential strategy for the prevention of CG disease.