Metagenomics of pigmented and cholesterol gallstones: the putative role of bacteria

Characterization of biliary and duodenal microbiota in patients with primary and recurrent choledocholithiasis

Purpose

To explore the biliary and duodenal microbiota features associated with the formation and recurrence of choledocholithiasis (CDL).

Methods

We prospectively recruited patients with primary (P-CDL, n = 29) and recurrent CDL (R-CDL, n = 27) for endoscopic retrograde cholangiopancreatography (ERCP). Duodenal mucosa (DM), bile and bile duct stones (BDS) samples were collected in P- and R-CDL patients. DM samples were also collected in 8 healthy controls (HC). The microbiota profile analysis was performed with 16S rRNA gene sequencing.

Results

Short-course antibiotic application before ERCP showed no significant effects in alpha and beta diversities of the biliary and duodenal microbiota in CDL. Alpha diversity showed no difference between DM and bile samples in CDL. The duodenal microbial richness and diversity was lower in both P- and R-CDL than HC. The biliary microbiota composition showed a high similarity between P- and R-CDL. Fusobacterium and Enterococcus were higher abundant in DM, bile, and BDS samples of R-CDL than P-CDL, as well as Escherichia and Klebsiella in bile samples of R-CDL. The enriched duodenal and biliary bacteria in CDL were closely associated with cholecystectomy, inflammation and liver dysfunction. The bile-associated microbiota of R-CDL expressed enhanced capacity of D-glucuronide and D-glucuronate degradation, implicating an elevated level of β-glucuronidase probably produced by enriched Escherichia and Klebsiella in bile.

Conclusions

The duodenal microbiota was in an imbalance in CDL. The duodenal microbiota was probably the main source of the biliary microbiota and was closely related to CDL formation and recurrence. Enterococcus, Fusobacterium, Escherichia and Klebsiella might contribute to CDL recurrence.

Clinical trials

The study was registered at the Chinese Clinical Trial Registry (https://www.chictr.org.cn/index.html, ChiCTR2000033940).

Supplementary Information

The online version contains supplementary material available at 10.1007/s13755-023-00267-2.

Investigating the influence of the gut microbiome on cholelithiasis: unveiling insights through sequencing and predictive modeling

BACKGROUND

Cholelithiasis is one of the most common disorders of hepatobiliary system. Gut bacteria may be involved in the process of gallstone formation and are, therefore considered as potential targets for cholelithiasis prediction.

OBJECTIVE

To reveal the correlation between cholelithiasis and gut bacteria.

METHODS

Stool samples were collected from 100 cholelithiasis and 250 healthy individuals from Huzhou Central Hospital; The 16S rRNA of gut bacteria in the stool samples was sequenced using the third-generation Pacbio sequencing platform; Mothur v.1.21.1 was used to analyze the diversity of gut bacteria; Wilcoxon rank-sum test and linear discriminant analysis of effect sizes (LEfSe) were used to analyze differences in gut bacteria between patients suffering from cholelithiasis and healthy individuals; Chord diagram and Plot-related heat maps were used to analyze the correlation between cholelithiasis and gut bacteria; six machine algorithms were used to construct models to predict cholelithiasis.

RESULTS

There were differences in the abundance of gut bacteria between cholelithiasis and healthy individuals, but there were no differences in their community diversity. Increased abundance of Costridia, Escherichia flexneri, and Klebsiella pneumonae were found in cholelithiasis, while Bacteroidia, Phocaeicola, and Phocaeicola vulgatus were more abundant in healthy individuals. The top four bacteria that were most closely associated with cholelithiasis were Escherichia flexneri, Escherichia dysenteriae, Streptococcus salivarius, and Phocaeicola vulgatus. The cholelithiasis model based on CatBoost algorithm had the best prediction effect (sensitivity: 90.48%, specificity: 88.32%, and AUC: 0.962).

CONCLUSION

The identification of characteristic gut bacteria may provide new predictive targets for gallstone screening. As being screened by the predictive model, people at high risk of cholelithiasis can determine the need for further testing, thus enabling early warning of cholelithiasis.

Gallbladder microbial species and host bile acids biosynthesis linked to cholesterol gallstone comparing to pigment individuals

Gallstones are crystalline deposits in the gallbladder that are traditionally classified as cholesterol, pigment, or mixed stones based on their composition. Microbiota and host metabolism variances among the different types of gallstones remain largely unclear. Here, the bile and gallstone microbial species spectra of 29 subjects with gallstone disease (GSD, 24 cholesterol and 5 pigment) were revealed by type IIB restriction site-associated DNA microbiome sequencing (2bRAD-M). Among them (21 subjects: 18 cholesterol and 3 pigment), plasma samples were subjected to liquid chromatography-mass spectrometry (LC-MS) untargeted metabolomics. The microbiome yielded 896 species comprising 882 bacteria, 13 fungi, and 1 archaeon. Microbial profiling revealed significant enrichment of Cutibacterium acnes and Microbacterium sp005774735 in gallstone and Agrobacterium pusense and Enterovirga sp013044135 in the bile of cholesterol GSD subjects. The metabolome revealed 2296 metabolites, in which malvidin 3-(6''-malonylglucoside), 2-Methylpropyl glucosinolate, and ergothioneine were markedly enriched in cholesterol GSD subjects. Metabolite set enrichment analysis (MSEA) demonstrated enriched bile acids biosynthesis in individuals with cholesterol GSD. Overall, the multi-omics analysis revealed that microbiota and host metabolism interaction perturbations differ depending on the disease type. Perturbed gallstone type-related microbiota may contribute to unbalanced bile acids metabolism in the gallbladder and host, representing a potential early diagnostic marker and therapeutic target for GSD.

The role of bacteria in gallstone formation

Gallstones are a prevalent biliary system disorder that is particularly common in women. They can lead to various complications, such as biliary colic, infection, cholecystitis, and even gallbladder cancer. However, the etiology of gallstones remains incompletely understood. The significant role of bacteria in gallstone formation has been demonstrated in recent studies. Certain bacteria not only influence bile composition and the gallbladder environment but also actively participate in stone formation by producing enzymes such as β-glucuronidase and mucus. Therefore, this review aimed to analyze the mechanisms involving the types and quantities of bacteria involved in gallstone formation, providing valuable references for understanding the etiology and clinical treatment of gallstones.

Insight into the mechanism of gallstone disease by proteomic and metaproteomic characterization of human bile

Introduction

Cholesterol gallstone disease is a prevalent condition that has a significant economic impact. However, the role of the bile microbiome in its development and the host's responses to it remain poorly understood.

Methods

In this study, we conducted a comprehensive analysis of microbial and human bile proteins in 40 individuals with either gallstone disease or gallbladder polyps. We employed a combined proteomic and metaproteomic approach, as well as meta-taxonomic analysis, functional pathway enrichment, and Western blot analyses.

Results

Our metaproteomic analysis, utilizing the lowest common ancestor algorithm, identified 158 microbial taxa in the bile samples. We discovered microbial taxa that may contribute to gallstone formation, including β-glucuronidase-producing bacteria such as Streptococcus, Staphylococcus, and Clostridium, as well as those involved in biofilm formation like Helicobacter, Cyanobacteria, Pseudomonas, Escherichia coli, and Clostridium. Furthermore, we identified 2,749 human proteins and 87 microbial proteins with a protein false discovery rate (FDR) of 1% and at least 2 distinct peptides. Among these proteins, we found microbial proteins crucial to biofilm formation, such as QDR3, ompA, ndk, pstS, nanA, pfIB, and dnaK. Notably, QDR3 showed a gradual upregulation from chronic to acute cholesterol gallstone disease when compared to polyp samples. Additionally, we discovered other microbial proteins that enhance bacterial virulence and gallstone formation by counteracting host oxidative stress, including sodB, katG, rbr, htrA, and ahpC. We also identified microbial proteins like lepA, rtxA, pckA, tuf, and tpiA that are linked to bacterial virulence and potential gallstone formation, with lepA being upregulated in gallstone bile compared to polyp bile. Furthermore, our analysis of the host proteome in gallstone bile revealed enhanced inflammatory molecular profiles, including innate immune molecules against microbial infections. Gallstone bile exhibited overrepresented pathways related to blood coagulation, folate metabolism, and the IL-17 pathway. However, we observed suppressed metabolic activities, particularly catabolic metabolism and transport activities, in gallstone bile compared to polyp bile. Notably, acute cholelithiasis bile demonstrated significantly impaired metabolic activities compared to chronic cholelithiasis bile.

Conclusion

Our study provides a comprehensive metaproteomic analysis of bile samples related to gallstone disease, offering new insights into the microbiome-host interaction and gallstone formation mechanism.

Characteristics and metabolic potential of biliary microbiota in patients with giant common bile duct stones

Background

Endoscopic retrograde cholangiopancreatography (ERCP) is an effective minimally invasive operation for the management of choledocholithiasis, while successful extraction is hampered by large diameter of stones. Emerging studies have revealed the close correlation between biliary microbiota and common bile duct stones (CBDS). In this study, we aimed to investigate the community characteristics and metabolic functions of biliary microbiota in patients with giant CBDS.

Methods

Eligible patients were prospectively enrolled in this study in First Affiliated Hospital of Soochow University from February 2022 to October 2022. Bile samples were collected through ERCP. The microbiota was analyzed using 16S rRNA sequencing. Metabolic functions were predicted by PICRUSTs 2.0 calculation based on MetaCyc database. Bile acids were tested and identified using ultra performance liquid chromatography-tandem mass spectrometry.

Results

A total of 26 patients were successfully included into final analysis, 8 in giant stone (GS) group and 18 in control group. Distinct biliary microbial composition was identified in patients with giant CBDS, with a significantly higher abundance of Firmicutes at phylum level. The unique composition at genus level mainly consisted of Enterococcus, Citrobacter, Lactobacillus, Pyramidobacter, Bifidobacterium and Shewanella. Pyramidobacter was exclusively found in GS group, along with the absence of Robinsoniella and Coprococcus. The contents of free bile acids were significantly higher in GS group, including cholic acid (98.39μmol/mL vs. 26.15μmol/mL, p=0.035), chenodesoxycholic acid (54.69μmol/mL vs. 5.86μmol/mL, p=0.022) and ursodeoxycholic acid (2.70μmol/mL vs. 0.17μmol/mL, p=0.047). Decreasing tendency of conjugated bile acids were also observed. Metabolic pathways concerning cholelithiasis were abundant in GS group, including geranylgeranyl diphosphate biosynthesis, gluconeogenesis, glycolysis and L-methionine biosynthesis.

Conclusions

This study demonstrated the community structure and metabolic potential of biliary microbiota in patients with giant CBDS. The unique biliary microbial composition holds valuable predictive potential for clinical conditions. These findings provide new insights into the etiology of giant CBDS from the perspective of biliary microbiota.

Effect of Clostridium butyricum on the formation of primary choledocholithiasis based on intestinal microbiome and metabolome analysis

AIMS

To investigate the function and probable mechanism of Clostridium butyricum in the development of choledocholithiasis.

METHODS AND RESULTS

The lithogenic diet group and the lithogenic diet + C. butyricum group were used to develop the choledocholithiasis model. During the experiment, C. butyricum suspension was administered to the rats in the lithogenic diet + C. butyricum group. The findings demonstrated that the C. butyricum intervention decreased the Firmicutes/Bacteroidetes ratio in the colon of experimental animals given a lithogenic diet. The relative levels of Desulfovibrio (0.93%) and Streptococcus (0.38%) fell, whereas Lactobacillus (22.36%), Prevotella (14.09%), and bacteria that produce short-chain fatty acids increased. Finally, 68 distinct metabolic products were found based on nontargeted metabonomics, and 42 metabolic pathways associated to the various metabolites were enriched.

CONCLUSIONS

We found that C. butyricum decreased the development of choledocholithiasis. It keeps the equilibrium of the rat's gut microbiome intact and lowers the danger of bacterial infections of the gastrointestinal and biliary systems. It is hypothesized that by controlling lipid metabolism, it may also have an impact on the development of cholelithiasis.

Fungal infections and the fungal microbiome in hepatobiliary disorders

Liver and biliary diseases affect more than a billion people worldwide, with high associated morbidity and mortality. The impact of the intestinal bacterial microbiome on liver diseases has been well established. However, the fungal microbiome, or mycobiome, has been overlooked for a long time. Recently, several studies have shed light on the role of the mycobiome in the development and progression of hepatobiliary diseases. In particular, the fungal genus Candida has been found to be involved in the pathogenesis of multiple hepatobiliary conditions. Herein, we compare colonisation and infection, describe mycobiome findings in the healthy state and across the various hepatobiliary conditions, and point toward communalities. We detail how quantitation of immune responses to fungal antigens can be employed to predict disease severity, e.g. using antibodies to Saccharomyces cerevisiae or specific anti-Candida albicans antibodies. We also show how fungal products (e.g. beta-glucans, candidalysin) activate the host's immune system to exacerbate liver and biliary diseases. Finally, we describe how the gut mycobiome can be modulated to ameliorate hepatobiliary conditions.

Gastrointestinal microbiome and cholelithiasis: Current status and perspectives

Cholelithiasis is a common digestive disease affecting 10% to 15% of adults. It imposes significant global health and financial burdens. However, the pathogenesis of cholelithiasis involves several factors and is incompletely elucidated. In addition to genetic predisposition and hepatic hypersecretion, the pathogenesis of cholelithiasis might involve the gastrointestinal (GI) microbiome, consisting of microorganisms and their metabolites. High-throughput sequencing studies have elucidated the role of bile, gallstones, and the fecal microbiome in cholelithiasis, associating microbiota dysbiosis with gallstone formation. The GI microbiome may drive cholelithogenesis by regulating bile acid metabolism and related signaling pathways. This review examines the literature implicating the GI microbiome in cholelithiasis, specifically gallbladder stones, choledocholithiasis, and asymptomatic gallstones. We also discuss alterations of the GI microbiome and its influence on cholelithogenesis.

Gastrointestinal microbiome and cholelithiasis: Current status and perspectives

Cholelithiasis is a common digestive disease affecting 10% to 15% of adults. It imposes significant global health and financial burdens. However, the pathogenesis of cholelithiasis involves several factors and is incompletely elucidated. In addition to genetic predisposition and hepatic hypersecretion, the pathogenesis of cholelithiasis might involve the gastrointestinal (GI) microbiome, consisting of microorganisms and their metabolites. High-throughput sequencing studies have elucidated the role of bile, gallstones, and the fecal microbiome in cholelithiasis, associating microbiota dysbiosis with gallstone formation. The GI microbiome may drive cholelithogenesis by regulating bile acid metabolism and related signaling pathways. This review examines the literature implicating the GI microbiome in cholelithiasis, specifically gallbladder stones, choledocholithiasis, and asymptomatic gallstones. We also discuss alterations of the GI microbiome and its influence on cholelithogenesis.

Effect of sphincter of Oddi dysfunction on the abundance of biliary microbiota (biliary microecology) in patients with common bile duct stones

Objective

Biliary calculi, a common benign disease of the gastrointestinal tract, are affected by multiple factors, including diet, lifestyle, living environment, and personal and genetic background. Its occurrence is believed to be related to a change in biliary microbiota. Approximately 10%-20% of symptomatic patients with cholecystolithiasis have choledocholithiasis, resulting in infection, abdominal pain, jaundice, and biliary pancreatitis. This study aimed to determine whether a dysfunction in the sphincter of Oddi, which controls the outflow of bile and separates the bile duct from the intestine, leads to a change in biliary microbiota and the occurrence of biliary calculi.

Methods

Forty patients with cholecystolithiasis and choledocholithiasis were prospectively recruited. Bile specimens were obtained, and biliary pressure was measured during and after surgery. The collected specimens were analyzed with 16S rRNA gene to characterize the biliary microbiota. The risk factors of common bile duct calculi were analyzed numerically combined with the pressure in the sphincter of Oddi.

Results

Different biliary microbiota were found in all cases. Patients with sphincter of Oddi dysfunction had significantly increased biliary microbiota as well as significantly higher level of systemic inflammation than patients with normal sphincter of Oddi.

Conclusions

The systemic inflammatory response of patients with sphincter of Oddi dysfunction is more severe, and their microbial community significantly differs from that of patients with normal sphincter of Oddi, which makes biliary tract infection more likely; furthermore, the biliary tract of patients with sphincter of Oddi dysfunction has more gallstone-related bacterial communities.

The Role of the Gallbladder, the Intestinal Barrier and the Gut Microbiota in the Development of Food Allergies and Other Disorders

The microbiota present in the gastrointestinal tract is involved in the development or prevention of food allergies and autoimmune disorders; these bacteria can enter the gallbladder and, depending on the species involved, can either be benign or cause significant diseases. Occlusion of the gallbladder, usually due to the presence of calculi blocking the bile duct, facilitates microbial infection and inflammation, which can be serious enough to require life-saving surgery. In addition, the biliary salts are secreted into the intestine and can affect the gut microbiota. The interaction between the gut microbiota, pathogenic organisms, and the human immune system can create intestinal dysbiosis, generating a variety of syndromes including the development of food allergies and autoimmune disorders. The intestinal microbiota can aggravate certain food allergies, which become severe when the integrity of the intestinal barrier is affected, allowing bacteria, or their metabolites, to cross the intestinal barrier and invade the bloodstream, affecting distal body organs. This article deals with health conditions and severe diseases that are either influenced by the gut flora or caused by gallbladder obstruction and inflammation, as well as putative treatments for those illnesses.

The Intratumoral Bacterial Metataxonomic Signature of Hepatocellular Carcinoma

Microbiota is implicated in hepatocellular carcinoma (HCC). The spectrum of intratumoral microbiota associated with HCC progression remains elusive. Fluorescence in situ hybridization revealed that microbial DNAs were distributed in the cytosol of liver hepatocytes and erythrocytes. Viable anaerobic or aerobic bacteria were recovered in HCC tissues by fresh tissue culture. We performed a comprehensive DNA sequencing of bacterial 16S rRNA genes in 156 samples from 28 normal liver, 64 peritumoral, and 64 HCC tissues, and the DNA sequencing yielded 4.2 million high-quality reads. Both alpha and beta diversity in peritumor and HCC microbiota were increased compared to normal controls. The most predominant phyla in HCC were Patescibacteria, Proteobacteria, Bacteroidota, Firmicutes, and Actinobacteriota. phyla of Proteobacteria, Firmicutes, and Actinobacteriota, and classes of Bacilli and Actinobacteria, were consistently enriched in peritumor and HCC tissues, while Gammaproteobacteria was especially abundant in HCC tissues compared to normal controls. Streptococcaceae and Lactococcus were the marker taxa of HCC cirrhosis. The Staphylococcus branch and Caulobacter branch were selectively enriched in HBV-negative HCCs. The abundance of Proteobacteria, Gammaproteobacteria, Firmicutes, Actinobacteriota, and Saccharimonadia were associated with the clinicopathological features of HCC patients. The inferred functions of different taxa were changed between the microbiota of normal liver and peritumor/HCC. Random forest machine learning achieved great discriminative performance in HCC prediction (area under the curve [AUC] = 1.00 in the training cohort, AUC = 0.950 for top five class signature, and AUC = 0.943 for the top 50 operational taxonomy units [OTUs] in the validation cohort). Our analysis highlights the complexity and diversity of the liver and HCC microbiota and established a specific intratumoral microbial signature for the potential prediction of HCC. IMPORTANCE Gut microbiome is an important regulator of hepatic inflammation, detoxification, and immunity, and contributes to the carcinogenesis of liver cancer. Intratumoral bacteria are supposed to be closer to the tumor cells, forming a microenvironment that may be relevant to the pathological process of hepatocellular carcinoma (HCC). However, the presence of viable intratumoral bacteria remains unclear. It is worth exploring whether the metataxonomic characteristics of intratumoral bacteria can be used as a potential marker for HCC prediction. Here, we present the first evidence of the existence of viable intratumoral bacteria in HCC using the tissue culture method. We revealed that microbial DNAs were distributed in the cytosol of liver hepatocytes and erythrocytes. We analyzed the diversity, structure, and abundance of normal liver and HCC microbiota. We built a machine learning model for HCC prediction using intratumoral bacterial features. We show that specific taxa represent potential targets for both therapeutic and diagnostic interventions.

A systematic review on omics data (metagenomics, metatranscriptomics, and metabolomics) in the role of microbiome in gallbladder disease

Microbiotas are the range of microorganisms (mainly bacteria and fungi) colonizing multicellular, macroscopic organisms. They are crucial for several metabolic functions affecting the health of the host. However, difficulties hamper the investigation of microbiota composition in cultivating microorganisms in standard growth media. For this reason, our knowledge of microbiota can benefit from the analysis of microbial macromolecules (DNA, transcripts, proteins, or by-products) present in various samples collected from the host. Various omics technologies are used to obtain different data. Metagenomics provides a taxonomical profile of the sample. It can also be used to obtain potential functional information. At the same time, metatranscriptomics can characterize members of a microbiome responsible for specific functions and elucidate genes that drive the microbiotas relationship with its host. Thus, while microbiota refers to microorganisms living in a determined environment (taxonomy of microorganisms identified), microbiome refers to the microorganisms and their genes living in a determined environment and, of course, metagenomics focuses on the genes and collective functions of identified microorganisms. Metabolomics completes this framework by determining the metabolite fluxes and the products released into the environment. The gallbladder is a sac localized under the liver in the human body and is difficult to access for bile and tissue sampling. It concentrates the bile produced in the hepatocytes, which drains into bile canaliculi. Bile promotes fat digestion and is released from the gallbladder into the upper small intestine in response to food. Considered sterile originally, recent data indicate that bile microbiota is associated with the biliary tract’s inflammation and carcinogenesis. The sample size is relevant for omic studies of rare diseases, such as gallbladder carcinoma. Although in its infancy, the study of the biliary microbiota has begun taking advantage of several omics strategies, mainly based on metagenomics, metabolomics, and mouse models. Here, we show that omics analyses from the literature may provide a more comprehensive image of the biliary microbiota. We review studies performed in this environmental niche and focus on network-based approaches for integrative studies.

Evaluation of gallstone classification and their diagnosis through serum parameters as emerging tools in treatment: a narrative review

The treatment of gallstones is a matter of real concern as they may cause gallbladder cancer if not properly attended to. Evaluating the classification of gallstones can give major clues in their treatment as it will decide their aetiology, chemical composition, and pathogenesis. Also, serum parameters have emerged as an efficient tool for diagnosing gallstones. They can be probed to evaluate different biochemicals and the changes in their levels in gallstone patients which can be correlated with early prediction of the formation of gallstones. In the present review, a thorough search of the available literature was done starting from the earliest approaches for the classification of gallstones up to the recent advancements. The alteration in the level of serum parameters was also studied in gallstone patients so that it can act as a potential diagnostic tool for early detection of gallstone formation. The earliest classification of gallstones was done in 1896 by Nauyn. He classified them into pure cholesterol stones, laminated cholesterol stones, ordinary gallbladder stones, mixed bilirubin stones, and rare forms. The most recent classification of gallstones was done by Peter et al in 2020 and they classified them as pure, mixed, composite cholesterol, carbonate stones, black and brown pigment stones. The altered of levels of serum parameters was analyzed by Reuben (1985) and in recent times by Peter et al (2020). The various serum parameters studied were as RDW-CV test (red blood cell distribution width), PCT (prolactin) test, MPV (mean platelet count), LYM (lymphocyte) test, and EOS (eosinophil and eosinophil count test). Also, we discussed some practical considerations for gallstones that can be taken into account for gallstone prevention and diagnosis. Further research is required to detect gallstone type in the gallbladder by using the alteration in the levels of serum parameters.

Clinico-epidemiology and aetiopathogenesis of gallstone disease in the South Asian region: a scoping review protocol

INTRODUCTION

Pathogenesis of gallstones (GS) is multifactorial and is influenced by numerous environmental and genetic risk factors. As a result, clinico-epidemiology and aetiopathogenesis of GS vary in different populations. Understanding the aetiopathogenesis of GS for different populations is imperative in control and prevention of GS disease and its associated complications. This protocol describes the methodology of a scoping review which focuses on synthesising the most updated knowledge on GS disease in South Asia.

METHODS AND ANALYSIS

The scoping review proposed in this protocol will be guided by Arksey and O'Malley's framework and the Joanna Briggs Institute Reviewers' Manual. Accordingly, population, concept and context strategy will be used to formulate the scoping review question, eligibility criteria and search strategy. In the search, electronic databases, MEDLINE/PubMed, ScienceDirect, Scopus, Cochrane library, CINAHL, Trip, and Google scholar, as well as various grey literature sources will be used in synthesising and presenting the findings on clinico-epidemiology and aetiopathogenesis of GS disease in South Asia.

ETHICS AND DISSEMINATION

As secondary data will be used in the study, ethical approval will not be required. The scoping review proposed by this protocol will accurately summarise the current knowledge on GS disease in South Asia based on published and unpublished literature on the field. Thus, the evidence presented in the review will be important for healthcare providers to make decisions on the control and prevention of GS disease and as well as to identify future research priorities on GS disease in South Asia.

Patients with Primary and Secondary Bile Duct Stones Harbor Distinct Biliary Microbial Composition and Metabolic Potential

Introduction

Cholelithiasis has a high incidence worldwide and limited treatment options due to its poorly understood pathogenesis. Furthermore, the role of biliary microbiota in cholelithiasis remains understudied. To address these questions, we performed microbial sequencing from biliary samples from primary bile duct stone (PBDS) and secondary bile duct stone (SBDS) patients.

Results

We analyzed in total 45 biliary samples, including those from cholelithiasis patients with PBDS or SBDS and people with other digestive diseases. 16S rRNA sequencing showed the bacteria family Alcaligenaceae increased in relative abundance in the lithiasis group compared with the non-lithiasis group. In addition, the PBDS group showed significantly lower bacterial diversity than SBDS, with Propionibacteriaceae, Sphingomonadaceae, and Lactobacillaceae as the most significant bacteria families decreased in relative abundance. We further performed whole metagenomic shotgun sequencing (wMGS) and found increased ability of biofilm synthesis and the ability to sense external stimuli in PBDS based on functional annotation of mapped reads. From genome-resolved analysis of the samples, we identified 36 high-quality draft bacterial genome sequences with completion ≥70% and contamination ≤10%. Most of these genomes were classified into Proteobacteria, Firmicutes, or Actinobacteria.

Conclusions

Our findings indicated that there is a subtle impact on biliary microbiome from cholelithiasis while the difference is more pronounced between the PBDS and SBDS. It was revealed that the diversity of biliary microbiota in PBDS is lower, while some metabolic pathways are up-regulated, including those linked to higher incidence of different types of cancer, providing new insights for the understanding of cholelithiasis with different origin.

Biliary Diseases from the Microbiome Perspective: How Microorganisms Could Change the Approach to Benign and Malignant Diseases

Recent evidence regarding microbiota is modifying the cornerstones on pathogenesis and the approaches to several gastrointestinal diseases, including biliary diseases. The burden of biliary diseases, indeed, is progressively increasing, considering that gallstone disease affects up to 20% of the European population. At the same time, neoplasms of the biliary system have an increasing incidence and poor prognosis. Framing the specific state of biliary eubiosis or dysbiosis is made difficult by the use of heterogeneous techniques and the sometimes unwarranted invasive sampling in healthy subjects. The influence of the microbial balance on the health status of the biliary tract could also account for some of the complications surrounding the post-liver-transplant phase. The aim of this extensive narrative review is to summarize the current evidence on this topic, to highlight gaps in the available evidence in order to guide further clinical research in these settings, and, eventually, to provide new tools to treat biliary lithiasis, biliopancreatic cancers, and even cholestatic disease.

The value of bacterial metagenomic analysis in post-surgical examination of gallstones

Gallstone disease is one of the most common causes of hospitalization for gastrointestinal diseases in the world. Recent studies have examined the presence of bacteria in the formation of stones. Our main goal was to determine the overall composition of gallstone microflora. Gallstones were obtained from 24 patients during laparoscopic cholecystectomy from which DNA were extracted. Composition of bacterial flora was evaluated on 16 s rDNA sequencing technique. In the vast majority of samples, bacteria were present, and four groups could be differentiated regarding the flora. Overall composition shows that 87% of the stones were cholesterol/mixed type of gallstone. Additionally, potentially harmful microorganisms (Streptococcus, Clostridium and Kocuria) that could cause post-surgery complications were identified in several patients. The obtained results indicate that this technique may be useful in analyzing the type of stones and in pinpointing the presence of pathogenic bacteria.

Gallbladder stone formation in Iraqi patients is associated with bacterial infection and HLA class II-DRB1 antigens

Background

Gallbladder stone is recently increased among the Iraqi society due to many risk factors such as bacterial infection and some HLA class II antigens.

Aim(s)

This study investigates the types of bacterial infection and HLA-DRB1 antigens' ratio that may be correlated with gallbladder stone formation. Setting and Design: The study included 45 patients and the same number of healthy individuals as a control group. Patients were with multiple gallstones. Gallstone bacterial culture was demonstrated to diagnose viable bacteria. HLA-DRB1 alleles' frequency was investigated using sequence-specific oligonucleotide probes (PCR-SSOP).

Results

Irrespective of gallstone type and size, different types of living viable bacteria were isolated from the cores of the studied gallstones in 80% of the studied cases versus 20% of sterile gallstones. Gram-negative bacteria cultures were the dominant (89.3%), including Escherichia coli, Klebsiella spp., Proteus spp., Acinetobacter spp., and Enterobacter spp. Mixed infection of Gram-positive and negative bacteria was noted: Escherichia coli and Enterococus spp. and the others of Escherichia coli and Acitobacter spp., and Klebsiella spp. and Pseudomonas spp. Gram-positive bacteria cultures were also detected at lower rate (10.7%) including Staphylococci spp. The frequency of HLA-DRB1*03:01, HLA-DRB1*4:03, HLA-DRB1*13:22, and HLA-DRB1*15:10 alleles was significantly elevated in patients compared to the healthy control group.

Conclusion

Results ensured the viability of the bacteria isolated from the core of gallstones and showed positive correlation between gallbladder stone and different bacterial infection. In addition, HLA-DRB1 alleles were significantly high in patients compared to healthy control group suggesting them as risk factors (P < 0.05).

Biliary Microbial Structure of Gallstone Patients With a History of Endoscopic Sphincterotomy Surgery

The biliary microbiota is related to the pathogenesis of human bile duct stones. However, the extent to which a history of invasive endoscopic sphincterotomy (EST) affects the biliary bacterial community remains largely unknown. We collected bile samples from the common bile duct of 100 choledocholithiasis patients. We performed 16S rRNA sequencing to investigate and compare the biliary microbial community. The patients without antibiotic treatment (AT) were grouped into three clusters based on their biliary microbial compositions. The patients with a history of EST were significantly enriched in one cluster mainly consisting of gastrointestinal bacteria compared with the other two clusters consisting of oral and environmental bacteria. The β-diversities of patients with and without EST were also significantly different, whereas the α-diversities were comparable. The only significantly enriched bacterial genus associated with a history of EST was Pyramidobacter, while eight other genera were significantly decreased. For patients with AT, seven of these genera maintained their association with EST, including Pyramidobacter. However, after AT, the difference in β-diversities was diminished. EST induced a marked shift in the biliary microbial composition. A cluster of biliary bacteria was associated with a history of EST, and Pyramidobacter was specific to EST.

In vitro analysis of gallstone formation in the presence of bacteria

AIM

In our previous study, we have isolated different genera of bacteria from gallstones and this intrigued us to study their role in gallstone formation. The isolates exhibited certain biliary activities like urease activity, slime production, and β-glucuronidase production. We aimed to investigate the role of these factors in the formation of gallstone in in vitro conditions at a supersaturated concentration of cholesterol.

METHODOLOGY

To mimic bile in in vitro state, Brilliant Green Bile Broth (BGBB) media having a composition similar to human bile was used. Four different experimental sets were prepared, each having nine flasks with varying concentrations of cholesterol and CaCO3 (calcium carbonate). Test sets I, II, III, and IV were inoculated with Salmonella, Enterococcus, Helicobacter, and Neisseria respectively, which were isolated from gallstone itself. Out of these four bacteria, only Helicobacter did not possess slime activity. A control set was also established which was devoid of bacteria. The control also had nine flasks with different concentrations of cholesterol and CaCO3. All the sets were incubated in the incubator shaker at 37 °C and 80 revolution per minutes (RPM) for 20 days.

RESULT

It was observed that the sets having bacteria had a less nucleation time as compared to the control (F = 5.274; p < 0.001). Solidification of gallstone was observed only in the set with bacteria having slime activity (sets I, II, and IV).

CONCLUSION

The slime activity of bacteria leads to solidification of gallstones, whereas the other activities accelerate the nucleation of gallstone formation enhancing the severity of the disease.

Gallstone Disease and Microbiome

Gallstone disease (GSD) has, for many years, remained a high-cost, socially significant public health problem. Over the past decade, a number of studies have been carried out—both in humans and in animal models—confirming the role of the microbiota in various sections of the gastrointestinal tract as a new link in the etiopathogenesis of GSD. The microbiome of bile correlates with the bacterial composition of saliva, and the microbiome of the biliary tract has a high similarity with the microbiota of the duodenum. Pathogenic microflora of the oral cavity, through mechanisms of immunomodulation, can affect the motility of the gallbladder and the expression of mucin genes (MUC1,Muc3, MUC4), and represent one of the promoters of stone formation in the gallbladder. The presence of H. pylori infection contributes to the formation of gallstones and affects the occurrence of complications of GSD, including acute and chronic cholecystitis, cholangitis, pancreatitis. Intestinal bacteria (Clostridium, Bifidobacterium, Peptostreptococcus, Bacteroides, Eubacterium, and Escherichia coli) participating in the oxidation and epimerization of bile acids can disrupt enterohepatic circulation and lead to the formation of gallstones. At the same time, cholecystectomy due to GSD leads to the further transformation of the composition of the microbiota in various parts of the gastrointestinal tract, increasing the risk of developing stomach cancer and colorectal cancer. Further research is required to determine the possibility of using the evaluation of the composition of the microbiota of the gastrointestinal and biliary tracts as an early diagnostic marker of various gastroenterological diseases.