Adipose Tissue, Bile Acids, and Gut Microbiome Species Associated With Gallstones After Bariatric Surgery

Gallstones after bariatric surgery: mechanisms and prophylaxis

Gallstones represent a common yet often underappreciated complication following bariatric surgery, with reported incidence rates ranging widely from 10.4% to 52.8% within the first postoperative year. Multiple factors contribute to gallstone formation in this setting, including intraoperative injury to the hepatic branch of the vagus nerve, alterations in bile composition, reduced food intake, shifts in gastrointestinal hormone levels, and dysbiosis of the gut microbiota. Notably, the risk of cholelithiasis varies by surgical procedure, with sleeve gastrectomy (SG) generally associated with a lower incidence compared to Roux-en-Y gastric bypass (RYGB). Prophylactic cholecystectomy during bariatric surgery may benefit patients with preexisting gallstones, whereas preserving the hepatic branch of the vagus is an important technical consideration, particularly in RYGB, to mitigate postoperative gallstone risk. Pharmacological interventions, such as ursodeoxycholic acid (UDCA), have demonstrated efficacy in preventing gallstones and reducing subsequent cholecystectomy rates. However, consensus is lacking on the optimal dosing, duration, and administration frequency of UDCA across different bariatric procedures. Additionally, dietary measures, such as moderate fat intake or fish oil supplementation, have shown promise in alleviating lithogenic processes. Emerging evidence supports the use of probiotics as a safe and patient-friendly adjunct or alternative to UDCA, given their ability to improve gut dysbiosis and reduce gallstone formation. Further high-quality studies are needed to define standardized prophylactic strategies that balance efficacy with patient adherence, offering personalized gallstone prevention protocols in the era of widespread bariatric surgery.

Relationship between Abnormal Lipid Metabolism and Gallstone Formation

Cholelithiasis is a common biliary system disease with a high incidence worldwide. Abnormal lipid metabolism has been shown to play a key role in the mechanism of gallstones. Therefore, recent research literature on the genes, proteins, and molecular substances involved in lipid metabolism during the pathogenesis of gallstones has been conducted. This study aimed to determine the role of lipid metabolism in the pathogenesis of gallstones and provide insights for future studies using previous research in genomics, metabolomics, transcriptomics, and other fields.

Cholelithiasis, Gut Microbiota and Bile Acids after Bariatric Surgery-Can Cholelithiasis Be Prevented by Modulating the Microbiota? A Literature Review

BACKGROUND

Cholelithiasis is one of the more common complications following bariatric surgery. This may be related to the rapid weight loss during this period, although the exact mechanism of gallstone formation after bariatric surgery has not been fully elucidated.

METHODS

The present literature review focuses on risk factors, prevention options and the impact of the gut microbiota on the development of gallbladder stones after bariatric surgery.

RESULTS

A potential risk factor for the development of cholelithiasis after bariatric surgery may be changes in the composition of the intestinal microbiota and bile acids. One of the bile acids-ursodeoxycholic acid-is considered to reduce the concentration of mucin proteins and thus contribute to reducing the formation of cholesterol crystals in patients with cholelithiasis. Additionally, it reduces the risk of both asymptomatic and symptomatic gallstones after bariatric surgery. Patients who developed gallstones after bariatric surgery had a higher abundance of Ruminococcus gnavus and those who did not develop cholelithiasis had a higher abundance of Lactobacillaceae and Enterobacteriaceae.

CONCLUSION

The exact mechanism of gallstone formation after bariatric surgery has not yet been clarified. Research suggests that the intestinal microbiota and bile acids may have an important role in this.

Intestinal microbiota and biliary system diseases

Introduction

The incidence of biliary system diseases has been continuously increasing in the past decade. Biliary system diseases bring a heavy burden to humanity and society. However, the specific etiology and pathogenesis are still unknown. The biliary system, as a bridge between the liver and intestine, plays an indispensable role in maintaining the physiological metabolism of the body. Therefore, prevention and treatment of biliary diseases are crucial. It is worth noting that the microorganisms participate in the lipid metabolism of the bile duct, especially the largest proportion of intestinal bacteria.

Methods

We systematically reviewed the intestinal microbiota in patients with gallstones (GS), non-calculous biliary inflammatory, and biliary tract cancer (BTC). And searched Pubmed, Embase and Web of science for research studies published up to November 2023.

Results

We found that the abundance of Faecalibacterium genus is decreased in GS, primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC) and BTC. Veillonella, Lactobacillus, Streptococcus and Enterococcus genus were significantly increased in PSC, PBC and BTC. Interestingly, we found that the relative abundance of Clostridium was generally reduced in GS, PBC and BTC. However, Clostridium was generally increased in PSC.

Discussion

The existing research mostly focuses on exploring the mechanisms of bacteria targeting a single disease. Lacking comparison of multiple diseases and changes in bacteria during the disease process. We hope to provide biomarkers forearly diagnosis of biliary system diseases and provide new directions for the mechanism of intestinal microbiota in biliary diseases.

Long-term complications of significant weight loss: lessons learned from bariatric surgery

The increasing prevalence of worldwide obesity calls for a comprehensive understanding of available treatment options. Bariatric surgery remains a very effective obesity treatment, showing substantial effects on obesity-related complications, including type 2 diabetes mellitus and cardiovascular disease, mainly related to significant long-term weight loss. Besides the benefits, weight loss can lead to some deleterious consequences, such as gallstones, constipation, muscle mass loss, bone fractures, vitamin deficiencies, peripheral neural palsy, suicide, eating disorders, alcohol dependency syndrome, and increased divorce. Those consequences may also be seen after long-term effective pharmacotherapy for obesity. Understanding these risks will lead to improved awareness and successful treatment with both surgical and nonsurgical treatments.

The Black Box Orchestra of Gut Bacteria and Bile Acids: Who Is the Conductor?

Over the past decades the potential role of the gut microbiome and bile acids in type 2 diabetes mellitus (T2DM) has been revealed, with a special reference to low bacterial alpha diversity. Certain bile acid effects on gut bacteria concern cytotoxicity, or in the case of the microbiome, bacteriotoxicity. Reciprocally, the gut microbiome plays a key role in regulating the bile acid pool by influencing the conversion and (de)conjugation of primary bile acids into secondary bile acids. Three main groups of bacterial enzymes responsible for the conversion of bile acids are bile salt hydrolases (BSHs), hydroxysteroid dehydrogenases (HSDHs) and enzymes encoded in the bile acid inducible (Bai) operon genes. Interventions such as probiotics, antibiotics and fecal microbiome transplantation can impact bile acids levels. Further evidence of the reciprocal interaction between gut microbiota and bile acids comes from a multitude of nutritional interventions including macronutrients, fibers, prebiotics, specific individual products or diets. Finally, anatomical changes after bariatric surgery are important because of their metabolic effects. The heterogeneity of studies, diseases, bacterial species and (epi)genetic influences such as nutrition may challenge establishing specific and detailed interventions that aim to tackle the gut microbiome and bile acids.