Enterohepatic circulation of bile acids after cholecystectomy

The bile-gut axis and metabolic consequences of cholecystectomy

Cholelithiasis and cholecystitis affect individuals of all ages and are often treated by surgical removal of the gallbladder (cholecystectomy), which is considered a safe, low-risk procedure. Nevertheless, recent findings show that bile and its regulated storage and excretion may have important metabolic effects and that cholecystectomy is associated with several metabolic diseases postoperatively. Bile acids have long been known as emulsifiers essential to the assimilation of lipids and absorption of lipid-soluble vitamins, but more recently, they have also been reported to act as metabolic signaling agents. The nuclear receptor, farnesoid X receptor (FXR), and the G protein-coupled membrane receptor, Takeda G protein-coupled receptor 5 (TGR5), are specific to bile acids. Through activation of these receptors, bile acids control numerous metabolic functions. Cholecystectomy affects the storage and excretion of bile acids, which in turn may influence the activation of FXR and TGR5 and their effects on metabolism including processes leading to metabolic conditions such as metabolic dysfunction-associated steatotic liver disease and metabolic syndrome. Here, with the aim of elucidating mechanisms behind cholecystectomy-associated dysmetabolism, we review studies potentially linking cholecystectomy and bile acid-mediated metabolic effects and discuss possible pathophysiological mechanisms behind cholecystectomy-associated dysmetabolism.

Associations of cholecystectomy with metabolic health changes and incident cardiovascular disease: a retrospective cohort study

Although some studies conducted about the risk of cholecystectomy and cardiovascular disease, there was a limit to explaining the relationship. We investigated the short-term and long-term relationship between cholecystectomy and cardiovascular disease, and evidence using the elements of the metabolic index as an intermediate step. It was a retrospective cohort study and we used the National Health Insurance Service database of South Korea between 2002 and 2015. Finally, 5,210 patients who underwent cholecystectomy and 49,457 at 1:10 age and gender-matched controls of subjects were collected. The main results was estimated by Multivariate Cox proportional hazard regression to calculate the hazard ratio (HR) with 95% confidence interval (CI) for risk of cardiovascular disease after cholecystectomy. Regarding short-term effects of cholecystectomy, increased risk of cardiovascular disease (aHR 1.35, 95% CI 1.15-1.58) and coronary heart disease (aHR 1.77, 95% CI 1.44-2.16) were similarly seen within 2 years of surgery. When analyzing the change in metabolic risk factors, cholecystectomy was associated with a change in systolic blood pressure (adjusted mean [aMean]: 1.51, 95% CI: [- 1.50 to - 4.51]), total cholesterol (aMean - 14.14, [- 20.33 to 7.95]) and body mass index (aMean - 0.13, [- 0.37 to 0.11]). Cholecystectomy patients had elevated risk of cardiovascular disease in the short-term, possibly due to the characteristics of the patient before surgery. The association of cholecystectomy and cardiovascular disease has decreased after 2 years in patients who underwent cholecystectomy, suggesting that because of improvement of metabolic health, cholecystectomy-associated elevation of cardiovascular disease risk may be ameliorated 2 years after cholecystectomy.

Does postcholecystectomy increase the risk of colorectal cancer?

With the increasing number of cholecystectomy and the high proportion of colorectal cancer in malignant tumors, the question of whether cholecystectomy is a risk factor for colorectal disease has been widely concerned. After reviewing the literature at home and abroad, the authors will summarize the research progress of the correlation between the occurrence of colorectal tumors after cholecystectomy, in order to provide help for the prevention and treatment of colorectal tumors.

Cholecystectomy-induced secondary bile acids accumulation ameliorates colitis through inhibiting monocyte/macrophage recruitment

Although post-cholecystectomy (PC) patients usually have gastrointestinal complications and a higher risk of colorectal cancer, previous studies undetected a heightened risk of inflammatory bowel disease. Thus, we tried to investigate cholecystectomy's impact and pathophysiological mechanism on murine colitis models and clarify the association among fecal bile acids (BAs), mucosal bacterial microbiota, and immune cells in the PC patients. One month or three months after cholecystectomy, mice have induced colitis and tested BAs and fecal microbiota analysis. Next, mice were treated with various cholecystectomy-accumulated bile acids in drinking water for three months before inducing colitis. All 14 paired PC patients and healthy subjects were enrolled for BAs and mucosal microbiota analysis. Cholecystectomy ameliorated DSS-induced murine colitis, accelerated mucosal repair, and induced a significant shifting of fecal microbiota and BAs profiles under colitis status, which featured a higher relative abundance of species involved in BAs metabolism and increased secondary BAs concentrations. Cholecystectomy-associated secondary BAs (LCA, DCA, and HDCA) also ameliorated DSS-induced colitis and accelerated mucosal repair in mice. Cholecystectomy and specific secondary BAs treatments inhibited monocytes/macrophages recruitment in colitis mice. In vitro, cholecystectomy-associated secondary BAs also downregulated monocytes chemokines in the THP-1 derived macrophages through activation of the LXRα-linked signaling pathway. The alterations of mucosal microbiota and fecal BAs profiles were found in the PC patients, characterized as increased species with potential immuno-modulating effects and secondary BAs, which were negatively associated with peripheral monocytes levels. Cholecystectomy-induced secondary bile acids accumulation ameliorated colitis through inhibiting monocyte/macrophage recruitment, which might be mediated by the LXRα-related signaling pathway. Cholecystectomy, after 3 months follow-up, has an immune-regulatory role in murine colitis, preliminarily explaining that no increased risk of IBD had been reported in the PC patients, which still warrants further studies.

Distinctive Clinical Correlates of Small Intestinal Bacterial Overgrowth with Methanogens

BACKGROUND AND AIMS

Most patients with small intestinal bacterial overgrowth (SIBO) produce hydrogen by fermentation of dietary carbohydrates; however, ∼30% of patients with SIBO are colonized with Archaea, anaerobic organisms that produce methane. SIBO is associated with a plethora of symptoms and conditions, but their diagnostic significance is unclear. We aimed to determine if specific symptoms and conditions are associated with methanogenic SIBO.

METHODS

This study received institutional review board approval (IRB00059873). In this retrospective cross-sectional study, we queried a database of glucose breath tests conducted for suspected SIBO at our tertiary care medical center, which included data on the presence or absence of gastrointestinal symptoms and conditions often associated with SIBO. All patients had undergone a standardized breath testing protocol.

RESULTS

In a cohort of 1461 patients, 33.1% were SIBO positive; of these, 49.8% produced only hydrogen, 38.8% produced only methane, and 11.4% produced both gases. The following factors distinguished patients with hydrogen-producing SIBO, but not methanogenic SIBO, from SIBO-negative patients: vitamin B₁₂ deficiency (odds ratio, 1.44; confidence interval [CI], 1.01-2.06; P = .046), Roux-en-Y gastric bypass (odds ratio, 2.14; CI, 1.09-4.18; P = .027), cholecystectomy (odds ratio, 1.42; CI, 1.06-1.91; P = .020), and diabetes (odds ratio, 1.59; CI, 1.13-2.24; P = .008). The absence of vitamin B₁₂ deficiency was the sole discriminating factor between methanogenic and hydrogenic SIBO (odds ratio, 0.57; CI, 0.34-0.97; P = .038).

CONCLUSIONS

Patients with SIBO caused by methane-producing Archaea display a different spectrum of associated symptoms and clinical conditions compared with patients with SIBO caused by hydrogen-producing bacteria, particularly a lower incidence of vitamin B₁₂ deficiency.

Complex impacts of gallstone disease on metabolic syndrome and nonalcoholic fatty liver disease

BACKGROUND

Patients with gallstone disease (GSD) often have highly co-occurrence with metabolic syndrome (MetS) and Nonalcoholic fatty liver disease (NAFLD) both associated with insulin resistance (IR). Meanwhile, highly prevalence of NAFLD was found in patients who received cholecystectomy. However, the associations of GSD with MetS, NAFLD is inconsistent in the published literature. And risk of cholecystectomy on NAFLD is unclear.

METHODS

We searched the Medline EMBASE and WOS databases for literature that met our study topic. To be specific, studies with focus on associations between GSD and MetS/NAFLD, and risk evaluation on cholecystectomy and NAFLD incidence were enrolled for further analysis. The random effect model was used to calculate the combined relative ratio (RR) and odds ratio (OR)and 95% confidence interval (CI).

RESULTS

Seven and six papers with focus on connections between GSD and NAFLD/MetS prevalence. Correspondingly, seven papers with focus on risk of cholecystectomy on NAFLD occurrence were also enrolled into meta-analysis. After pooling the results from individual study, patients with GSD had higher risk of MetS (OR:1.45, 95%CI: 1.23-1.67, I² = 41.1%, P=0.165). Risk of GSD was increased by 52% in NAFLD patients (pooled OR:1.52, 95%CI:1.24-1.80). And about 32% of increment on NAFLD prevalence was observed in patients with GSD (pooled OR: 1.32, 95%CI:1.14-1.50). With regard to individual MetS components, patients with higher systolic blood pressure were more prone to develop GSD, with combined SMD of 0.29 (96%CI: 0.24-0.34, P<0.05). Dose-response analysis found the GSD incidence was significantly associated with increased body mass index (BMI) (pooled OR: 1.02, 95%CI:1.01-1.03) in linear trends. Patients who received cholecystectomy had a higher risk of post-operative NAFLD (OR:2.14, 95%CI: 1.43-2.85), P<0.05). And this impact was amplified in obese patients (OR: 2.51, 95%CI: 1.95-3.06, P<0.05).

CONCLUSION

Our results confirmed that controls on weight and blood pressure might be candidate therapeutic strategy for GSD prevention. And concerns should be raised on de-novo NAFLD after cholecystectomy.

Cholecystectomy and subsequent risk of Parkinson's disease: a nationwide retrospective cohort study

Growing evidence has suggested that the gut-brain axis plays an important role in the pathogenesis of Parkinson's disease (PD), and that this role is mediated by the interactions between bile acids (BAs) and intestinal microbiota. Given that cholecystectomy can lead to alterations in BAs and gut microbiota, we investigated whether cholecystectomy is linked to a higher risk of PD. We constructed a cohort of patients with an operation code of cholecystectomy from 2010 to 2015 (n = 161,838) and age- and sex-matched control subjects without cholecystectomy (n = 286,135) using the National Health Insurance Service database. Incident PD was traced over a maximum observation period of 7 years. We identified 1404 incident PD cases during 1,631,265 person-years of follow-up. The cholecystectomy group showed an elevated risk of PD compared to the control group, even after adjusting for potential confounding factors (adjusted hazard ratio [HR] 1.14, 95% confidence interval [CI] 1.02-1.27). When the data were split by sex, the risk elevation was significant in men (adjusted HR 1.22, 95% CI 1.06-1.41), but not in women (adjusted HR 1.03, 95% CI 0.88-1.22). Our results provide evidence that cholecystectomy is associated with an increased risk of developing PD. This association differed between men and women, suggesting sex-specific effects of cholecystectomy on the risk of PD.

Cholecystectomy as a risk factor for metabolic dysfunction-associated fatty liver disease: unveiling the metabolic and chronobiologic clues behind the bile acid enterohepatic circulation

Metabolic dysfunction-associated fatty liver disease (MAFLD) is highly prevalent worldwide. Recent clinical and experimental studies have addressed the association between cholecystectomy and MAFLD, confirming that cholecystectomy is an independent risk factor for MAFLD. In this review, we describe the epidemiologic evidence that links cholecystectomy to MAFLD, and discuss the possible mechanisms behind these connections, in order to unveil the metabolic and chronobiologic signals conveyed by the waves of the bile acid enterohepatic circulation.

Regulation of autophagy by bile acids and in cholestasis - CholestoPHAGY or CholeSTOPagy

Autophagy is a lysosomal degradation pathway in which the cell self-digests its own components to provide nutrients in harsh environmental conditions. It also represents an opportunity to rid the cell of superfluous and damaged organelles, misfolded proteins or invaded microorganisms. Liver autophagy contributes to basic hepatic functions such as lipid, glycogen and protein turnover. Deregulated hepatic autophagy has been linked to many liver diseases including alpha-1-antitrypsin deficiency, alcoholic and non-alcoholic fatty liver diseases, hepatitis B and C infections, liver fibrosis as well as liver cancer. Recently, bile acids and the bile acid receptor FXR have been implicated in the regulation of hepatic autophagy, which implies a role of autophagy also for cholestatic liver diseases. This review summarizes the current evidence of bile acid mediated effects on autophagy and how this affects cholestatic liver diseases. Although detailed studies are lacking, we suggest a concept that the activity of autophagy in cholestasis depends on the disease stage, where autophagy may be induced at early stages ("cholestophagy") but may be impaired in prolonged cholestatic states ("cholestopagy").

Bacterial Alterations in Post-Cholecystectomy Patients Are Associated With Colorectal Cancer

Background: Although increasing evidences showed a correlation between cholecystectomy and the prevalence rate of colorectal cancer (CRC), and shed light on gut microbiota in colorectal pathogenesis, only a few studies focused on microbial alterations after cholecystectomy, and its sequent role in carcinogenesis and progression of CRC has not been reported. Thus, we aimed to investigate the bacterial alterations and tried to clarify their clinical significance.

Methods: 104 subjects were enrolled and divided into post-cholecystectomy patients (PC, n = 52) and healthy controls (HC, n = 52). To investigate the bacterial role in carcinogenesis, PC patients were further separated into preCA_CRC (patients with precancerous lesions and/or CRC, n = 9) and non-CA (patients without precancerous lesions and CRC, n = 43) based on the histopathology. Qualified stool samples were collected for 16S rRNA gene sequencing to analyze the bacterial profile.

Results: Our data showed noteworthy compositional and abundant alterations of bacterial microbiota in PC patients, characterized as Bacteroides ovatus, Prevotella copri, and Fusobacterium varium remarkably increased; Faecalibacterium prausnitzii, Roseburia faecis, and Bifidobacterium adolescentis significantly decreased. Additionally, the duration after cholecystectomy was the critical factor that affected bacterial composition. Machine learning-based analysis showed a pivotal role of Megamonas funiformis in discriminating PC from HC subjects and involving in the progression of CRC.

Conclusions: The bacterial dysbiosis may associate with CRC in PC patients, and the duration after cholecystectomy was highlighted as an important factor. Altered bacterial microbiota was likely to play a pivotal role in related-disease in the long-term follow-up of PC patients.

The gallbladder and vermiform appendix influence the assemblage of intestinal microorganisms

Surgical procedures for the symptomatic removal of the gallbladder and the vermiform appendix have been posited to adversely shift the assemblage of the intestinal microbiome increasing the risk of disease. The associated mechanisms have been linked with dysbiosis of the gut microbiota. Cholecystectomy causes changes of bile acid compositions and bile secretion patterns as bile acids interact with the intestinal microbiota in a bidirectional capacity. An appendectomy precludes the further recolonization of the proximal colon with a commensal biofilm that could maintain a stable intestinal microbiome. Epidemiological studies indicate that there is an increased risk of disease rather than causality following a cholecystectomy and appendectomy. This narrative review summarizes studies that report on the role that bile salts and the appendix, contribute to the assemblage of the intestinal microbiome in health and disease.

A Physiology-Based Model of Bile Acid Distribution and Metabolism Under Healthy and Pathologic Conditions in Human Beings

BACKGROUND & AIMS

Disturbances of the enterohepatic circulation of bile acids (BAs) are seen in a number of clinically important conditions, including metabolic disorders, hepatic impairment, diarrhea, and gallstone disease. To facilitate the exploration of underlying pathogenic mechanisms, we developed a mathematical model built on quantitative physiological observations across different organs.

METHODS

The model consists of a set of kinetic equations describing the syntheses of cholic, chenodeoxycholic, and deoxycholic acids, as well as time-related changes of their respective free and conjugated forms in the systemic circulation, the hepatoportal region, and the gastrointestinal tract. The core structure of the model was adapted from previous modeling research and updated based on recent mechanistic insights, including farnesoid X receptor-mediated autoregulation of BA synthesis and selective transport mechanisms. The model was calibrated against existing data on BA distribution and feedback regulation.

RESULTS

According to model-based predictions, changes in intestinal motility, BA absorption, and biotransformation rates affected BA composition and distribution differently, as follows: (1) inhibition of transintestinal BA flux (eg, in patients with BA malabsorption) or acceleration of intestinal motility, followed by farnesoid X receptor down-regulation, was associated with colonic BA accumulation; (2) in contrast, modulation of the colonic absorption process was predicted to not affect the BA pool significantly; and (3) activation of ileal deconjugation (eg, in patents with small intestinal bacterial overgrowth) was associated with an increase in the BA pool, owing to higher ileal permeability of unconjugated BA species.

CONCLUSIONS

This model will be useful in further studying how BA enterohepatic circulation modulation may be exploited for therapeutic benefits.

Computed Tomography Measurements of Hepatic Steatosis in Cholelitihiasis and Cholecystectomy Cases Using Unenhanced Images

INTRODUCTION

Computed tomography (CT) measurements of hepatic steatosis can be performed using unenhanced CT images. The purpose of this study was to assess the occurrence of hepatic steatosis using unenhanced CT images for patients undergoing cholecystectomy or having cholelithiasis.

METHODS

A total of 143 unenhanced CT cases from a single centre were retrospectively examined. The CT number of liver, ratio of CT number of liver to spleen, and CT number of liver minus CT number of spleen were measured in three groups: (1) patients undergoing cholecystectomy, (2) patients having cholelithiasis, and (3) control group. Abdominal circumference, anterior subcutaneous fat tissue thickness, and body mass index were obtained.

RESULTS

Mean CT number of liver was significantly different between the group of patients with cholecystectomy and cholelithiasis and the control group (P < .001) and also between cases of cholecystectomy and cholelithiasis (P = .041), with the lowest CT number of liver in the cholecystectomy group. The mean CT number of liver minus CT number of spleen and mean CT number (liver/spleen) ratios, evaluated separately for both lobes, were not different comparing the cholelithiasis and cholecystectomy groups. The mean CT number of liver minus CT number of spleen and mean CT number (liver/spleen) ratios differed significantly between the control group and both patient groups (P < .001). Positive correlations were identified between abdominal circumference, subcutaneous fat depth, body mass index, and liver size and hepatic steatosis.

CONCLUSION

There was an increased occurrence of hepatic steatosis in patients who have undergone a cholecystectomy compared with patients treated for cholelithiasis and the control group.

Cholecystectomy versus central obesity or insulin resistance in relation to the risk of nonalcoholic fatty liver disease: the third US National Health and Nutrition Examination Survey

BACKGROUND

Cholecystectomy, central obesity, and insulin resistance (IR) are established risk factors for nonalcoholic fatty liver disease (NAFLD). We aimed to examine the relative contributions and combined association of cholecystectomy and central obesity/IR with NAFLD risk.

METHODS

We conducted a cross-sectional analysis of data from the third National Health and Nutrition Examination Survey (NHANES III), in which ultrasonography was performed. Odds ratios (ORs) and 95% confidence intervals for NAFLD were estimated using logistic regression.

RESULTS

Cholecystectomy associated with a higher prevalence of NAFLD compared with gallstones among both centrally obese and non-centrally-obese subjects. Gallstones associated with a higher prevalence of NAFLD only in the presence of central obesity. In centrally obese participants, the OR increased from 2.67 (2.15-3.32) for participants without gallstone disease to 6.73 (4.40-10.29) for participants with cholecystectomy. In participants with cholecystectomy, the OR increased from 2.57 (1.35-4.89) for participants without central obesity to 6.73 (4.40-10.29) for centrally obese counterparts. We observed a modest increase in the risk of NAFLD with cholecystectomy compared with a large increase in the risk with IR or metabolic syndrome.

CONCLUSION

The magnitude of the NAFLD risk contributed by cholecystectomy was similar to central obesity in combined analyses. The magnitude of the association with IR or metabolic syndrome was greater than with cholecystectomy.

Isolation and Characterization of Lactobacillus spp. from Kefir Samples in Malaysia

Kefir is a homemade, natural fermented product comprised of a probiotic bacteria and yeast complex. Kefir consumption has been associated with many advantageous properties to general health, including as an antioxidative, anti-obesity, anti-inflammatory, anti-microbial, and anti-tumor moiety. This beverage is commonly found and consumed by people in the United States of America, China, France, Brazil, and Japan. Recently, the consumption of kefir has been popularized in other countries including Malaysia. The microflora in kefir from different countries differs due to variations in culture conditions and the starter media. Thus, this study was aimed at isolating and characterizing the lactic acid bacteria that are predominant in Malaysian kefir grains via macroscopic examination and 16S ribosomal RNA gene sequencing. The results revealed that the Malaysian kefir grains are dominated by three different strains of Lactobacillus strains, which are Lactobacillus harbinensis, Lactobacillusparacasei, and Lactobacillus plantarum. The probiotic properties of these strains, such as acid and bile salt tolerances, adherence ability to the intestinal mucosa, antibiotic resistance, and hemolytic test, were subsequently conducted and extensively studied. The isolated Lactobacillus spp. from kefir H maintained its survival rate within 3 h of incubation at pH 3 and pH 4 at 98.0 ± 3.3% and 96.1 ± 1.7% of bacteria growth and exhibited the highest survival at bile salt condition at 0.3% and 0.5%. The same isolate also showed high adherence ability to intestinal cells at 96.3 ± 0.01%, has antibiotic resistance towards ampicillin, penicillin, and tetracycline, and showed no hemolytic activity. In addition, the results of antioxidant activity tests demonstrated that isolated Lactobacillus spp. from kefir G possessed high antioxidant activities for total phenolic content (TPC), total flavonoid content (TFC), ferric reducing ability of plasma (FRAP), and 1,1-diphenyl-2-picryl-hydrazine (DPPH) assay compared to other isolates. From these data, all Lactobacillus spp. isolated from Malaysian kefir serve as promising candidates for probiotics foods and beverage since they exhibit potential probiotic properties and antioxidant activities.

Clinical and Pathogenetic Parallels of Nonalcoholic Fatty Liver Disease and Gallstone Disease

Aim:to analyze the data that has so far been accumulated on the pathogenetic association of gallstone disease (GD) and non-alcoholic fatty liver disease (NAFLD), as well as to assess the effect of cholecystectomy on the NAFLD course.

Key findings.The relationship between GD and NAFLD is very complex and seems to be mutually aggravating. There is no doubt that there is an increased risk of GB in NAFLD patients, which is primarily associated with common pathogenetic mechanisms. These include central and peripheral insulin resistance, changes in the expression of transcription factors (liver X-receptor and farnesoid X-receptor) and the bile acid membrane receptors (TGR5). Conversely, the effect of GD on the NAFLD course is assumed, although the pathogenetic factors of this association are still unknown. In recent years, convincing data has emerged concerning the role of cholecystectomy in the NAFLD progression, which may be connected with the development of small intestinal bacterial overgrowth, as well as with the disruption of the endocrine balance and the signal function of bile acids.

Conclusion.The connection between NAFLD, GD and cholecystectomy is complex and multifaceted. The study of this connection will allow new methods of treatment to be developed.

The Impact of Cholecystectomy on the Gut Microbiota: A Case-Control Study

Cholecystectomy alters the bile flow into the intestine and the enterohepatic circulation of the bile acids; this may affect the gut microbiota. We assessed the gut microbiota composition of patients who had undergone cholecystectomy and compared with those who had not. From a cohort of 1463 adult participants who underwent comprehensive health screening examinations, 27 subjects who had undergone cholecystectomy (cholecystectomy group) and 81 age- and sex-matched subjects who had not (control group) were selected. Clinical parameters were collected and compared. Microbial composition was determined by 16S rRNA gene sequencing of DNA extracted from fecal samples. We evaluated differences in the overall microbial composition and in the abundance of taxa. The two groups were comparable with respect to clinical characteristics and laboratory results. The actual number of taxa observed in a sample (observed features) was significantly lower in the cholecystectomy group than in the control group (p = 0.042). The beta diversity of Jaccard distance index was significantly different between the two groups (p = 0.027). Blautia obeum and Veillonella parvula were more abundant in the cholecystectomy group. The difference in the diversity of the gut microbiota between the cholecystectomy and control groups was subtle. However, B. obeum and V. parvula, which have azoreductase activity, were more abundant in the cholecystectomy group. The impact of such changes in the gut microbiota on health remains to be determined.

The characteristics of small intestinal bacterial overgrowth in patients with gallstone diseases

BACKGROUND AND AIM

Small intestinal bacterial overgrowth (SIBO) might be prevalent in gallstone disease, including cases involving cholecystectomy and gallstones. The study aimed to investigate the prevalence and characteristics of SIBO in patients with gallstone disease.

METHODS

This prospective study evaluated 265 patients for gallstone disease (200, gallstones; 65, cholecystectomy) and 39 healthy controls. Laboratory data, abdominal ultrasonography, and glucose breath test (GBT) with bowel symptom questionnaire were performed.

RESULTS

Glucose breath test positivity (+) in patients with gallstone disease (36.6%) was significantly higher than that in controls (20.5%). GBT+ in the gallstone group (40.5%) was significantly higher than that in the control or cholecystectomy group (24.6%). The number of patients with gallstone, tend to be higher in the GBT (H₂ )+, (CH₄ )+, and (mixed)+ groups (56 [28.0%], 11 [5.5%], and 14 [7.00%]), respectively. Gallbladder disease was independently associated with fatty liver, metabolic syndrome, and SIBO. Of 97 GBT+ patients, 70 (72.1%), 12 (12.4%), and 15 (15.5%) were in the GBT (H₂ )+, (CH₄ )+, and (mixed)+ groups, respectively. GBT (CH₄ )+ or GBT (mixed)+ were significantly associated with the gallstone group compared with the cholecystectomy group. The GBT (mixed)+ group had higher total symptom scores than the GBT- group for hard stool and urgency tendency, or the GBT (H₂ )+ group in hard stool and loose stool tendency. Gallstone was the only independent factor for SIBO in patients with gallstone diseases.

CONCLUSIONS

Small intestinal bacterial overgrowth is common among patients with gallstone. Especially, CH₄ or mixed-type SIBO seems to be prevalent and to worsen intestinal symptoms.

Cholecystectomy and risk of metabolic syndrome

The gallbladder physiologically concentrates and stores bile during fasting and provides rhythmic bile secretion both during fasting and in the postprandial phase to solubilize dietary lipids and fat-soluble vitamins. Bile acids (BAs), major lipid components of bile, play a key role as signaling molecules in modulating gene expression related to cholesterol, BA, glucose and energy metabolism. Cholecystectomy is the most commonly performed surgical procedure worldwide in patients who develop symptoms and/or complications of cholelithiasis of any type. Cholecystectomy per se, however, might cause abnormal metabolic consequences, i.e., alterations in glucose, insulin (and insulin-resistance), lipid and lipoprotein levels, liver steatosis and the metabolic syndrome. Mechanisms are likely mediated by the abnormal transintestinal flow of BAs, producing metabolic signaling that acts without gallbladder rhythmic function and involves the BAs/farnesoid X receptor (FXR) and the BA/G protein-coupled BA receptor 1 (GPBAR-1) axes in the liver, intestine, brown adipose tissue and muscle. Alterations of intestinal microbiota leading to distorted homeostatic processes are also possible. According to this view, cholecystectomy, via BA-induced changes in the enterohepatic circulation, is a risk factor for the metabolic abnormalities and becomes another “fellow traveler” with, or another risk factor for the metabolic syndrome.

In Silico Analysis Identifies Intestinal Transit as a Key Determinant of Systemic Bile Acid Metabolism

Bile acids fulfill a variety of metabolic functions including regulation of glucose and lipid metabolism. Since changes of bile acid metabolism accompany obesity, Type 2 Diabetes Mellitus and bariatric surgery, there is great interest in their role in metabolic health. Here, we developed a mathematical model of systemic bile acid metabolism, and subsequently performed in silico analyses to gain quantitative insight into the factors determining plasma bile acid measurements. Intestinal transit was found to have a surprisingly central role in plasma bile acid appearance, as was evidenced by both the necessity of detailed intestinal transit functions for a physiological description of bile acid metabolism as well as the importance of the intestinal transit parameters in determining plasma measurements. The central role of intestinal transit is further highlighted by the dependency of the early phase of the dynamic response of plasma bile acids after a meal to intestinal propulsion.

Nonalcoholic fatty liver disease, cholesterol gallstones, and cholecystectomy: new insights on a complex relationship

PURPOSE OF REVIEW

Gallstone disease (GSD) and nonalcoholic fatty liver disease (NAFLD often coexist in a given patient and both conditions are associated to obesity and insulin resistance. The relationship between GSD and NAFLD is complex and bidirectional. In the present review, we summarize the existing information on the complex link between GSD and NAFLD and the potential implications for patient care.

RECENT FINDINGS

Several clinical studies and systematic reviews have addressed the association between NAFLD and GSD underscoring that NAFLD is an independent risk factor for GSD. Conversely, GSD has been found also to be an independent risk factor for NAFLD with GSD potentially being linked to greater disease severity. In addition to the data showing association of NAFLD and GSD, recent evidence has also showed that cholecystectomy may itself be a risk factor for NAFLD development. The complex and bidirectional relationship between these diseases is partially explained by a number of common pathogenic links but the precise underlying mechanisms of the association of GSD and NAFLD need to be better delineated. Also, although the mechanisms of the promotional effect of cholecystectomy on NAFLD development are unknown, recent findings unveiling new aspects of gallbladder physiology and endocrine actions of bile acids provide a framework to advance research in this field.

SUMMARY

In this review, we address the different aspects of the complex association between NAFLD and GSD. The potential underlying mechanisms and recent information on endocrine actions of bile acids and the gallbladder are reviewed.

The relation between gallstone disease and cardiovascular disease

Gallstone disease (GD) is a common digestive disorder that shares many risk factors with cardiovascular disease (CVD). CVD is an important public health issue that encompasses a large percentage of overall mortality. Several recent studies have suggested an association between GD and CVD, while others have not. In this report, we present a meta-analysis of cohort studies to assess the association between GD and CVD. We included eight studies published from 1980 to 2017, including nearly one million participants. The pooled relative risk (RR, 95% confidence interval [CI]) from the random-effects model associates with GD is 1.23 (95% CI: 1.17-1.30) for fatal and nonfatal CVD events. The pooled RR from the random-effects model of CVD events in female patients with GD is 1.24 (95% CI: 1.16-1.32). In male GD patients, the pooled RR from the random-effects model for CVD is 1.18 (95% CI: 1.06-1.31). Our meta-analysis demonstrates a substantially increased risk of fatal and nonfatal CVD events among patients with a medical history of GD. We suggest that interested investigators should further pursue the subject. In addition, both male and female patients with GD have a risk of CVD, and women have a higher risk than men.

Effect of cholecystectomy on hepatic fat accumulation and insulin resistance in non-obese Hispanic patients: a pilot study

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is highly prevalent worldwide. Experimental studies have shown that cholecystectomy (XGB) increases hepatic fat content in mice and appears associated to NAFLD in large retrospective population-based studies. The aim of this study was to prospectively assess the effects of XGB on hepatic fat content (HFC) and insulin resistance (IR) in non-obese, middle aged Hispanic subjects.

METHODS

Twenty-six gallstone patients undergoing elective XGB and 16 control subjects with normal livers and gallbladders at ultrasonography were prospectively followed 24 months for changes in HFC and IR. Clinical, biochemical determinations and hepatic imaging were performed at baseline and 24 months after surgery. MRI technique quantified HFC in four hepatic segments. IR was assessed by the Homeostasis Model Assessment (HOMA_-IR) index.

RESULTS

Initial body mass index (BMI) was 25.6 ± 0.4 and 24.3 ± 1.0 in the control and XGB groups of subjects, respectively. Serum insulin level increased from 8.1 ± 0.7 to 10.0 ± 1.9 (μU/ml) 24 months after surgery in XGB patients (p < 0.05); no significant changes were detected in control individuals. Median HOMA_-IR index increased from 1.31 (interquartile range, 1.01-1.68) to 2.20 (interquartile range, 1.57 - 2.60) 24 months after XGB, (p < 0.003). Median HOMA_-IR index of control subjects remained unchanged at the end of the study. Serum apoB concentration increased from 61.5 ± 3.4 to 79.0 ± 7.8 (μg/ml) in XGB patients (p < 0.03). Serum apoB levels remained within normal ranges in both periods of the study in control subjects. HFC significantly increased in 2 of the 4 segments 24 months after XGB: right posterior hepatic lobe (from 5.3 ± 0.2% to 6.0 ± 0.2%, p > 0.04) and right anterior hepatic lobe (from 5.8 ± 0.2% to 6.6 ± 0.3%, p < 0.02). The average HFC of the four hepatic segments studied slightly increased from 5.4 ± 0.2 to 5.8 ± 0.3 2 years after XGB (p < 0.03). No significant changes were found in HFC in the control subjects at the end of the study.

CONCLUSIONS

Elective XGB increases HFC, HOMA_-IR index and serum apoB concentration. These results support the notion that XGB is a risk factor non-alcoholic fatty liver disease and other IR - associated disease conditions.

Cholecystectomy Causes Ultrasound Evidence of Increased Hepatic Steatosis

BACKGROUND

Cholecystectomy might contribute to the development of hepatic steatosis through metabolic changes. The biologic alteration of the enterohepatic circulation of bile acids and the alteration of the metabolic activity of bile acid that follows cholecystectomy may contribute to hepatic steatosis. This prospective study was conducted to clarify the possibility of steatosis development after cholecystectomy.

METHODS

From October 2013 to July 2014, 82 consecutive patients with a presumptive diagnosis of gallbladder disease were cholecystectomized. Liver parenchymal steatosis was measured using ultrasound and the hepatic steatosis index.

RESULTS

In all 82 patients, the hepatic steatosis index was found to be significantly correlated with the US fatty liver grade (Spearman's correlation r (2) = 0.331, P < 0.001). A total of 62 patients were followed up for 3 months. Comparison with the initial grade showed that 12 (18.5 %) patients had worsened from normal to mild (n = 10), from mild to moderate (n = 1), and from mild to severe (n = 1). The other patients stayed at their initial grade except one patient who improved (from moderated to mild). Analysis of laboratory findings showed that white blood cell count, aspartate transaminase, alanine transaminase level, and total bilirubin level were decreased. However, serum albumin and high-density lipoprotein cholesterol levels significantly increased.

CONCLUSIONS

Hepatic steatosis significantly developed 3 months after cholecystectomy. Therefore, cholecystectomy might be considered a risk factor for hepatic steatosis, but the relationship should be confirmed with long-term follow-up from a large group of patients.

Functions of the Gallbladder

The gallbladder stores and concentrates bile between meals. Gallbladder motor function is regulated by bile acids via the membrane bile acid receptor, TGR5, and by neurohormonal signals linked to digestion, for example, cholecystokinin and FGF15/19 intestinal hormones, which trigger gallbladder emptying and refilling, respectively. The cycle of gallbladder filling and emptying controls the flow of bile into the intestine and thereby the enterohepatic circulation of bile acids. The gallbladder also largely contributes to the regulation of bile composition by unique absorptive and secretory capacities. The gallbladder epithelium secretes bicarbonate and mucins, which both provide cytoprotection against bile acids. The reversal of fluid transport from absorption to secretion occurs together with bicarbonate secretion after feeding, predominantly in response to an adenosine 3',5'-cyclic monophosphate (cAMP)-dependent pathway triggered by neurohormonal factors, such as vasoactive intestinal peptide. Mucin secretion in the gallbladder is stimulated predominantly by calcium-dependent pathways that are activated by ATP present in bile, and bile acids. The gallbladder epithelium has the capacity to absorb cholesterol and provides a cholecystohepatic shunt pathway for bile acids. Changes in gallbladder motor function not only can contribute to gallstone disease, but also subserve protective functions in multiple pathological settings through the sequestration of bile acids and changes in the bile acid composition. Cholecystectomy increases the enterohepatic recirculation rates of bile acids leading to metabolic effects and an increased risk of nonalcoholic fatty liver disease, cirrhosis, and small-intestine carcinoid, independently of cholelithiasis. Among subjects with gallstones, cholecystectomy remains a priority in those at risk of gallbladder cancer, while others could benefit from gallbladder-preserving strategies. © 2016 American Physiological Society. Compr Physiol 6:1549-1577, 2016.

Cholecystectomy and Liver Disease in Short Bowel Syndrome

BACKGROUND

Recently, an association has been proposed between cholecystectomy and various liver diseases. Our aim was to determine whether cholecystectomy in short bowel patients influences the risk of liver disease.

METHODS

We reviewed 422 adults: 182 underwent cholecystectomy prior to short bowel, 102 after developing short bowel, and 138 patients still had the gallbladder in place.

RESULTS

Compared to pre and post short bowel, gallbladder patients were significantly less likely to have obesity (18 % and 21 % vs 9 %), central line infections (59 % and 69 % vs 46 %), intestine <60 cm (30 % and 39 % vs 26 %), and require parenteral nutrition >1 year (72 % and 77 % vs 64 %). The incidence of fatty liver was similar (31, 26, and 25 %). Fibrosis/cirrhosis was less common in the gallbladder group (26 % and 36 % vs 16 %). Frequency of end-stage liver disease was similar (15, 22, and 11 %). On multivariate analysis, cholecystectomy, parenteral nutrition >1 year, line infection, and intestine <60 cm were predictors of fibrosis/cirrhosis. Parenteral nutrition >1 year, line infection, and intestine <60 cm were predictors of end-stage liver disease.

CONCLUSIONS

Cholecystectomy does not appear to increase the incidence of liver disease in short bowel patients overall. Fibrosis/cirrhosis occurs significantly less frequently in patients with an intact gallbladder.

Relationship of hepatic fibrosis, cirrhosis, and mortality with cholecystectomy in patients with hepatitis C virus infection

OBJECTIVES

Studies have suggested that cholecystectomy is a risk factor for nonalcoholic fatty liver disease, but it is not known whether cholecystectomy is a risk factor for the progression of other chronic liver diseases such as hepatitis C virus (HCV) infection. The aim of this study was to assess whether cholecystectomy is associated with an increase in fibrosis, cirrhosis, and cirrhosis-related complications in patients with chronic HCV infection.

METHODS

Among a total of 3989 HCV-positive patients at the VA North Texas Health Care System, we retrospectively reviewed the records of 88 patients who had undergone cholecystectomy between 1998 and 2013, followed up for a median of 4.9 years. We compared the outcomes of these patients with those of two age-matched, race-matched, and sex-matched cohorts: a cohort consisting of 129 HCV-positive patients without gallbladder disease (GBD) and a second cohort consisting of 178 HCV-positive patients with GBD who had not undergone cholecystectomy. Demographics, presence of metabolic syndrome, alcohol use, laboratory data, and clinical progression of liver disease were compared at study entry and 5 years later.

RESULTS

Controlling for multiple factors associated with increase in liver fibrosis, analyses confirmed that a there was an increase in the proportion of patients who developed cirrhosis [odds ratio (OR)=3.24, 95% confidence interval (CI) 1.57-6.68, P=0.001] and ascites (OR=3.01, 95% CI 1.14-7.97, P=0.026) as well as in the incidence of death (OR=6.29, 95% CI 2.13-18.59, P=0.001) 5 years after cohort entry among HCV-positive patients with cholecystectomy compared with HCV-positive controls. The HCV-positive patient group with previous cholecystectomy showed an increased incidence of cirrhosis (OR=2.43, 95% CI 1.34-4.41, P=0.004), hepatocellular carcinoma (OR=2.85, 95% CI 1.11-7.36, P=0.030), and death (OR=3.31, 95% CI 1.50-7.28, P=0.003) 5 years after cohort entry compared with HCV-positive controls with GBD who had not undergone cholecystectomy.

CONCLUSION

Cholecystectomy among HCV-positive patients is associated an increased incidence of fibrosis, cirrhosis, and its complications (ascites, hepatocellular carcinoma, and death) compared with HCV-positive controls and HCV-positive patients with GBD who have not undergone cholecystectomy.

Cholecystectomy does not significantly increase the risk of fatty liver disease

AIM: To investigate the relationship between cholecystectomy and fatty liver disease (FLD) in a Chinese population.

METHODS: A total of 32428 subjects who had voluntarily undergone annual health checkups in the Second Affiliated Hospital of Nanjing Medical University from January 2011 to May 2013 were included in this study. Basic data collection, physical examination, laboratory examination, and abdominal ultrasound examination were performed.

RESULTS: Subjects undergoing cholecystectomy were associated with greater age, female sex, higher body mass index, and higher levels of systolic blood pressure, diastolic blood pressure, fasting plasma glucose, total cholesterol, and triglycerides. However, no significant differences were found in high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase, albumin, and serum uric acid. The overall prevalence of FLD diagnosed by ultrasonography was high at 38.4%. The prevalence of FLD was significantly higher for subjects who had undergone cholecystectomy (46.9%) than those who had not undergone cholecystectomy (38.1%; χ² test, P < 0.001). Cholecystectomy was positively associated with FLD (OR = 1.433, 95%CI: 1.259-1.631). However, after adjusting for possible factors associated with FLD, multivariate regression analysis showed that the association between cholecystectomy and FLD was not statistically significant (OR = 1.096; 95%CI: 0.939-1.279).

CONCLUSION: According to our study results, cholecystectomy may not be a significant risk factor for FLD.

Metabolic effects of cholecystectomy: gallbladder ablation increases basal metabolic rate through G-protein coupled bile acid receptor Gpbar1-dependent mechanisms in mice

Background & Aims

Bile acids (BAs) regulate energy expenditure by activating G-protein Coupled Bile Acid Receptor Gpbar1/TGR5 by cAMP-dependent mechanisms. Cholecystectomy (XGB) increases BAs recirculation rates resulting in increased tissue exposure to BAs during the light phase of the diurnal cycle in mice. We aimed to determine: 1) the effects of XGB on basal metabolic rate (BMR) and 2) the roles of TGR5 on XGB-dependent changes in BMR.

Methods

BMR was determined by indirect calorimetry in wild type and Tgr5 deficient (Tgr5^-/-) male mice. Bile flow and BAs secretion rates were measured by surgical diversion of biliary duct. Biliary BAs and cholesterol were quantified by enzymatic methods. BAs serum concentration and specific composition was determined by liquid chromatography/tandem mass spectrometry. Gene expression was determined by qPCR analysis.

Results

XGB increased biliary BAs and cholesterol secretion rates, and elevated serum BAs concentration in wild type and Tgr5^-/- mice during the light phase of the diurnal cycle. BMR was ~25% higher in cholecystectomized wild type mice (p <0.02), whereas no changes were detected in cholecystectomized Tgr5^-/- mice compared to wild-type animals.

Conclusion

XGB increases BMR by TGR5-dependent mechanisms in mice.

Metabolic profiling of bile acids in human and mouse blood by LC-MS/MS in combination with phospholipid-depletion solid-phase extraction

To obtain a more comprehensive profile of bile acids (BAs) in blood, we developed an ultrahigh performance liquid chromatography/multiple-reaction monitoring-mass spectrometry (UPLC-MRM-MS) method for the separation and detection of 50 known BAs. This method utilizes phospholipid-depletion solid-phase extraction as a new high-efficiency sample preparation procedure for BA assay. UPLC/scheduled MRM-MS with negative ion electrospray ionization enabled targeted quantitation of 43 and 44 BAs, respectively, in serum samples from seven individuals with and without fasting, as well as in plasma samples from six cholestatic gene knockout mice and six age- and gender-matched wild-type (FVB/NJ) animals. Many minor BAs were identified and quantitated in the blood for the first time. Method validation indicated good quantitation precision with intraday and interday relative standard deviations of ≤9.3% and ≤10.8%, respectively. Using a pooled human serum sample and a pooled mouse plasma sample as the two representative test samples, the quantitation accuracy was measured to be 80% to 120% for most of the BAs, using two standard-substance spiking approaches. To profile other potential BAs not included in the 50 known targets from the knockout versus wild-type mouse plasma, class-specific precursor/fragment ion transitions were used to perform UPLC-MRM-MS for untargeted detection of the structural isomers of glycine- and taurine-conjugated BAs and unconjugated tetra-hydroxy BAs. As a result, as many as 36 such compounds were detected. In summary, this UPLC-MRM-MS method has enabled the quantitation of the largest number of BAs in the blood thus far, and the results presented have revealed an unexpectedly complex BA profile in mouse plasma.

Cholecystectomy and NAFLD: does gallbladder removal have metabolic consequences?

Pathogenesis of nonalcoholic fatty liver (NAFLD) disease and gallbladder (GB) disease secondary to cholesterol gallstones is complex, yet both conditions share similar associated risk factors, most of them related to the metabolic syndrome. Cholecystectomy, the best treatment for GB disease, is one of the most performed abdominal surgeries worldwide. In this issue of the American Journal of Gastroenterology, Ruhl and Everhart, using data from the Third United States National Health and Nutrition Examination Survey (1988-1994), show that NAFLD is associated with cholecystectomy (odds ratio (OR)=2.4; 1.8-3.3), but not with gallstones (OR=1.1; 0.84-1.4). This finding suggests that cholecystectomy may itself represent a risk factor for NAFLD, which is in line with the recently undisclosed role of the GB and bile acids in systemic metabolic regulation. Thus, cholecystectomy may not be innocuous and may have a major impact on public health by contributing to NAFLD development.

Relationship of non-alcoholic fatty liver disease with cholecystectomy in the US population

OBJECTIVES

Other than weight-related conditions, risk factors for non-alcoholic fatty liver disease (NAFLD) are not well defined. We investigated the association of gallstones and cholecystectomy with NAFLD in a large, national, population-based study.

METHODS

Among adult participants in the third US National Health and Nutrition Examination Survey, 1988-1994, ultrasonography for gallstone disease was performed, and videotapes were subsequently evaluated for NAFLD. Odds ratios (ORs) for the association of gallstone disease with NAFLD were calculated using logistic regression analysis to adjust for common associated factors.

RESULTS

Among 12,232 participants without viral hepatitis or significant alcohol intake, the prevalence of gallstones was 7.4%, cholecystectomy 5.6%, and NAFLD 20.0%. Participants with cholecystectomy had higher age-sex-adjusted prevalence of NAFLD (48.4%) than those with gallstones (34.4%) or without gallstone disease (17.9%) (P<0.01 for all comparisons). Controlling for numerous factors associated with both NAFLD and gallstone disease, multivariate-adjusted analysis confirmed the association of NAFLD with cholecystectomy (OR=2.4; 95% confidence interval (CI): 1.8-3.3), but not with gallstones (OR=1.1; 95% CI: 0.84-1.4).

CONCLUSIONS

The association of NAFLD with cholecystectomy, but not with gallstones, indicates that cholecystectomy may itself be a risk factor for NAFLD.

New understandings about gallbladder function

The function of the gallbladder is to store and concentrate bile. Due to the high incidence of diseases such as gallstones, cholecystectomy has become one of the most common surgical procedures. Although cholecystectomy is a successful treatment for most patients, the loss of gallbladder function may contribute to chronic diarrhea and increase the incidence of proximal colon cancer, pancreatic cancer, hepatocellular carcinoma and esophageal adenocarcinoma. With the development of endoscopic technology and introduction of drugs that may prevent recurrence of gallstones, cholecystolithotomy with gall bladder preservation has become another choice for symptomatic gallstones, and it preserves the function of the gallbladder after the removal of gallstones. This may avoid the complications associated with the loss of gallbladder function.

Colesevelam hydrochloride: evidence for its use in the treatment of hypercholesterolemia and type 2 diabetes mellitus with insights into mechanism of action

Colesevelam hydrochloride is a molecularly engineered, second-generation bile acid sequestrant demonstrating enhanced specificity for bile acids which has been approved for use as adjunctive therapy to diet and exercise as monotherapy or in combination with a β-hydroxymethylglutaryl-coenzyme A reductase inhibitor for the reduction of elevated low-density lipoprotein cholesterol in patients with primary hypercholesterolemia. It is also the only lipid-lowering agent currently available in the United States which has been approved for use as adjunctive therapy in patients with type 2 diabetes mellitus whose glycemia remains inadequately controlled on therapy with metformin, sulfonylurea, or insulin. With the recent emphasis upon drug safety by the Food and Drug Administration and various consumer agencies, it is fitting that the role of nonsystemic lipid-lowering therapies such as bile acid sequestrants – with nearly 90 years of in-class, clinically safe experience – should be reexamined. This paper presents information on the major pharmacologic effects of colesevelam, including a discussion of recent data derived from both in vitro and in vivo rodent and human studies, which shed light on the putative mechanisms involved.

Pronounced variation in bile acid synthesis in humans is related to gender, hypertriglyceridaemia and circulating levels of fibroblast growth factor 19

BACKGROUND

Bile acid (BA) synthesis is essential in cholesterol and lipid homoeostasis.

METHODS

Serum samples from 435 normal and 23 cholecystectomized subjects were obtained after overnight fasting and assayed for markers of BA and cholesterol synthesis, as well as cholesterol absorption. We determined whether BA synthesis was related to fibroblast growth factor 19 (FGF19; a circulating metabolic regulator that is thought to inhibit BA synthesis), gender, age and serum lipids.

RESULTS

Bile acid synthesis varied more than 9-fold in normal individuals and was 29% higher in men than in women. Whilst low-density lipoprotein cholesterol increased with age, BA and cholesterol synthesis were stable. BA production was positively correlated with serum triglycerides (TGs), and 35% of individuals with a high level (>95th percentile) of BA synthesis had hypertriglyceridaemia (HTG) (>95th percentile). Serum FGF19 levels varied by 7-fold in normal individuals and were related inversely to BA synthesis but were not related to gender, plasma lipids or history of cholecystectomy.

CONCLUSIONS

Bile acid synthesis has a wide inter-individual variation, is lower in women than in men and is correlated positively with serum TGs. High BA production is frequently linked to HTG. Age-related hypercholesterolaemia is not associated with changes in BA or cholesterol production, nor to an increase in cholesterol absorption. In humans, the circulating level of FGF19 may regulate hepatic BA production under fasting conditions.

Cholecystectomy increases hepatic triglyceride content and very-low-density lipoproteins production in mice

BACKGROUND & AIMS

Bile acid (BA) pool size remains unchanged after cholecystectomy (XGB) but it circulates faster, exposing the enterohepatic system to an increased flux of BA. Triglyceride (TG) and BA metabolisms are functionally inter-related. We investigated whether ablation of the gallbladder (GB) modifies hepatic TG metabolism.

METHODS

Male mice were subjected to XGB and fed a normal diet. In some experiments, mice received a 1% nicotinic acid diet to block lipolysis. Parameters of BA and TG metabolism, and microsomal triglyceride transfer protein (MTTP) activity were measured 1-2 months after XGB. Serum parameters, hepatic lipids and mRNA expression of genes of lipid metabolism were determined.

RESULTS

BA pool size and synthesis were normal, but biliary BA secretion doubled during the diurnal light phase in XGB mice. Serum and hepatic TG concentrations increased 25% (P<0.02), and hepatic very-low-density lipoproteins (VLDL)-TG and apoB-48 productions increased 15% (P<0.03) and 50% (P<0.01), respectively, after XGB. Feeding a 1% nicotinic acid did normalize VLDL production. MTTP activity increased 15% (P<0.005) after XGB. Hepatic free fatty acid (FFA) synthesis and content, and mRNA levels of lipid metabolism-related genes remained normal in XGD mice.

CONCLUSIONS

XGB increased serum and hepatic TG levels, and VLDL production, which were restored to normal by nicotinic acid. The results suggest that FFA flux from adipose tissue to the liver is increased in XGB mice. They support the hypothesis that the GB has a role in the regulation of hepatic TG metabolism and that XGB may favour the accumulation of fat in the liver.

Diseases of the gallbladder and biliary tree

Most disorders of the biliary system are associated with increased activity of parenchymal transaminases (alanine aminotransferase, aspartate aminotransferase) and cholestatic enzymes (alkaline phosphatase and gamma glutamyl transferase) with or without hyperbilirubinemia or jaundice. While parenchymal liver disease is most common in the dog, inflammatory disorders involving the small- and medium-sized bile ducts and zone 1 (periportal) hepatocytes predominate in the cat. Historically, the incidence of disorders restricted to the gallbladder is low in both species; however, with routine diagnostic use of abdominal ultrasonography, the incidence of gallbladder mucoceles and cholelithiasis has increased. Extrahepatic bile duct obstruction is a well-recognized syndrome because of its association with pancreatitis and obvious jaundice. Less common disorders of the biliary system include a cadre of diverse conditions, including necroinflammatory processes, cholelithiasis, malformations, neoplasia, and an emerging syndrome of gallblader dysmotility.

The comparison of the risk factors and clinical manifestations of proximal and distal colorectal cancer

PURPOSE

Colorectal cancers in the proximal or distal site have distinct clinical characteristics. In this study, the authors compared the risk factors of proximal and distal colorectal cancer.

METHODS

A 16-page questionnaire was administered to 529 patients with colorectal cancer before operation. Cancers were classified as proximal or distal relative to the splenic flexure. Of these 529 patients, 6 patients were excluded because of the presence of synchronous colorectal cancers. Data of the 523 patients were analyzed.

RESULTS

Total numbers of proximal and distal cancers were 123 and 400. The proportion of patients with Type 2 diabetes was significantly higher for distal cancer (P = 0.034), whereas a greater proportion of patients with proximal cancer had a gallstone history (P = 0.005). Multivariate analysis revealed Type 2 diabetes to be a risk factor for distal colorectal cancer (P = 0.027) and cholelithiasis to be a risk factor for proximal cancer (P = 0.049). The odds ratio for distal colorectal cancer among males with Type 2 diabetes was 4.1 (95 percent confidence interval, 1.4-12.1). On the other hand, a gallstone history was more associated with proximal colon cancer, especially in females (odds ratio = 5.5; 95 percent confidence interval, 1.4-20.9).

CONCLUSIONS

A comparison of the risk factors of proximal and distal colorectal cancer showed that Type 2 diabetes is associated with distal colorectal cancer in males and that cholelithiasis is associated with proximal colon cancer in females.

Cholecystectomy and the risk of colorectal cancer

OBJECTIVES

Cholecystectomy has been implicated as a possible risk factor for colorectal cancer. However, the clinical evidence and the underlying mechanism for this association are still inconclusive. We conducted a population-based study to further clarify this association.

METHODS

We conducted a retrospective cohort study among all patients aged 40 yr or older in the General Practice Research Database from the United Kingdom. We excluded patients with <1 yr of colorectal cancer-free database follow-up as well as those patients who developed colorectal cancer within 1 yr after their cholecystectomies. Crude and adjusted incidence rate ratios (IRRs) were determined using Poisson regression.

RESULTS

The incidence rate of colorectal cancer among cholecystectomy patients (n = 55,960) was 119 (95% CI: 106-133) per 100,000 person-years, compared to 86 (95% CI: 83-90) per 100,000 person-years among patients without a cholecystectomy (n = 574,668). Among the covariates examined, only sex and age were significant confounders and were included in the adjusted analyses. The adjusted IRR of colorectal cancer associated with cholecystectomy was 1.32 (95% CI: 1.16-1.48, p < 0.001). The positive association was present for colon cancer (adjusted IRR 1.51, 95% CI: 1.30-1.74, p < 0.001), but not for rectal cancer (adjusted IRR 1.00, 95% CI: 0.85-1.17, p= 0.99). The pattern of association was similar in men versus women. A similar association with colon cancer was observed for cholelithiasis.

CONCLUSIONS

Cholecystectomy is associated with a modestly increased risk of colon cancer but not for rectal cancer. Lithogenic bile could be the underlying mechanism.

Effect of the type of dietary fat on biliary lipid composition and bile lithogenicity in humans with cholesterol gallstone disease

OBJECTIVE

The effect of the type of dietary fat on bile lipids and lithogenicity is unclear. This study compared the effects of two dietary oils that differed in fatty acid profile on biliary lipid composition in humans.

METHODS

Female patients who had cholesterol gallstones and were scheduled for elective cholecystectomy were studied. For 30 d before surgery, subjects were kept on diets that contained olive oil (olive oil group, n = 9) or sunflower oil (sunflower oil group, n = 9) as the main source of fat. Gallbladder bile and stones were sampled at surgery. After cholecystectomy, duodenal samples were collected by nasoduodenal intubation during fasting and after administration of mixed liquid meals that included the corresponding dietary oil. Duodenal and gallbladder bile samples were analyzed for cholesterol, phospholipids, and total bile acids by established methods. Individual bile acid conjugates in gallbladder bile were measured by high-performance liquid chromatography. Gallstones were analyzed by semiquantitative polarizing light microscopy.

RESULTS

Despite marked differences in the absolute concentration of biliary lipids and total lipid content, manipulation of dietary fat ingestion did not influence the cholesterol saturation or the profile of individual bile acids in gallbladder bile obtained from patients who had gallstones. All but one subject had mixed cholesterol stones. A cholesterol saturation index of hepatic bile in fasted cholecystectomized patients was similar in both dietary groups and indicative of supersaturation. In response to the test meal, the cholesterol saturation index decreased significantly in patients given the olive oil diet, reaching values lower than one at 120 min postprandially. In contrast, hepatic bile secreted by patients who consumed sunflower oil appeared supersaturated (cholesterol saturation index >1.5) throughout the experiment.

CONCLUSIONS

Our results suggest that the type of dietary fat habitually consumed can influence bile composition in humans. In gallbladder, this influence was noted in the presence of more concentrated bile in the olive oil group. However, this was not translated into a modification of cholesterol saturation, which is likely due to the fact that cholesterol gallstones were present by the time the dietary intervention started. The finding that a typical postprandial variation in hepatic bile lithogenicity occurred only in olive oil patients was revealing. While keeping in mind the methodologic limitations of this part of the study, some gastrointestinal and metabolic mechanisms for this effect are discussed.

Intestinal absorption of the bile acid analogue 75Se-homocholic acid-taurine is increased in primary biliary cirrhosis, and reverts to normal during ursodeoxycholic acid administration

BACKGROUND

Whether ileal absorption of bile acid is up or downregulated in chronic cholestasis is still debated, and most evidence has come from animal studies.

AIMS

To compare ileal bile acid absorption in patients with primary biliary cirrhosis (PBC) and in healthy control subjects, and to assess the effect of ursodeoxycholic acid (UDCA).

PATIENTS

We studied 14 PBC patients before and during (n=11) UDCA administration, 14 healthy control subjects, and 14 Crohn's disease patients (as disease controls).

METHODS

We used cholescintigraphy to measure retention in the enterohepatic circulation over five successive days of the bile acid analogue (75)Se-homocholic acid-taurine ((75)SeHCAT) as an index of ileal bile acid absorption. Results were expressed as (75)SeHCAT fractional turnover rate (FTR) and t(1/2)12.

RESULTS

(75)SeHCAT FTR was 0.19 (0.11)/day, 0.34 (0.11)/day (p<0.001), and 0.83 (0.32)/day in PBC patients, healthy controls (p<0.0001), and Crohn's patients (p<0.001), respectively, which increased to 0.36 (0.16)/day in PBC patients during UDCA treatment (p<0.005). (75)SeHCAT t(1/2)12 was 4.8 (2.1) days in PBC patients, 2.2 (0.5) days (p<0.001) in healthy controls, and 1.0 (0.5) days (p<0.001) in Crohn's disease patients. (75)SeHCAT t(1/2)12 decreased to 2.2 (0.93) days (p< 0.001) in PBC patients during UDCA treatment.

CONCLUSIONS

Our results support the concept that ileal bile acid absorption is upregulated in PBC patients, and that this effect may contribute towards damaging the cholestatic liver. This upregulation of bile acid absorption is abolished by UDCA.

Review article: the 'mechanical pumps' and the enterohepatic circulation of bile acids--defects in coeliac disease

Bile acid pool size is maintained relatively constant at about 3-5 g in healthy subjects by two mechanisms, enterohepatic circulation and de novo synthesis of bile acids. This latter mechanism compensates for the daily faecal loss (about 0.2-0.6 g) of bile acids, whereas the bulk of the pool is conserved by the former mechanism. The driving forces of the enterohepatic circulation are constituted by chemical pumps, including intestinal absorption and hepatic uptake, and by mechanical pumps, including gall-bladder and intestinal motility. The latter provide the main propulsive forces for bile acids to reach the site of intestinal absorption, and by contrast with the very rapid chemical pumps, mechanical pumps have storage capacity for the bile acid pool and therefore comprise the slow limb of the enterohepatic circulation. In coeliac disease, a disease classically described as a malabsorption syndrome associated with mucosal atrophy of the small intestine, both gall-bladder and small intestinal motor functions are impaired, and in this article we review the mechanisms involved in these defects, how they influence the enterohepatic circulation of bile acids, and the evidence supporting the concept that both the gall-bladder and the small intestinal motor functions represent the main factors affecting the kinetics of the enterohepatic circulation.

Methylprednisolone administration in primary biliary cirrhosis increases cholic acid turnover, synthesis, and deoxycholate concentration in bile

As immunosuppressive agents, corticosteroids may be considered an appropriate treatment for primary biliary cirrhosis, even if bone loss and other side effects may occur. We studied biliary lipid metabolism in 10 nonicteric patients, with histologically proven primary biliary cirrhosis (stage I-IV). We administered methylprednisolone (24 mg daily) for 30 days to ascertain its effects on biliary lipid metabolism, which are largely still unknown. All patients underwent a 30-day drug-washout period before entering the trial. The following parameters were studied before and after methylprednisolone treatment: serum biochemistry; cholic acid pool size, kinetics and synthesis; biliary lipid secretion; biliary bile acid pattern; biliary lipid molar percentage; and cholesterol saturation index. Methylprednisolone induced a statistically significant (Wilcoxon rank test) increase in cholic acid turnover (from 0.26+/-0.04 to 0.50+/-0.05 K/day, P = 0.005) and synthesis (from 0.42+/-0.12 to 0.78+/-0.11 mmol/day, P = 0.04), and in bile deoxycholic acid molar percentage (from 19.4+/-2.7 to 30.6+/-4.4% molar, P = 0.01). On the other hand, a significant decrease in biliary cholesterol molar percentage (from 7.9+/-0.7 to 6.4+/-0.5% molar, P = 0.005), cholesterol saturation index (from 1.11+/-0.11 to 0.95+/-0.07, P = 0.05), and biliary cholesterol secretion (from 64.7+/-5.4 to 53.0+/-4.5 micromol/hr, P = 0.005) was observed. These findings show that short-term administration of methylprednisolone in patients with primary biliary cirrhosis does not induce expansion of the cholic acid pool but increases cholic acid synthesis and turnover, as well as intestinal production of deoxycholic acid. If long-term treatment is considered, the beneficial immunosuppressive effects of corticosteroids have to be weighed against the hepatotoxic properties of deoxycholic acid.

Cholecystectomy in patients with normal gallbladder function did not alter characteristics in duodenal motility which was not correlated to size of bile acid pool

Nine gallstone patients with normal gallbladder function as assessed by hepatobiliary scintigraphy were included. Fasting and postprandial duodenal motility were studied before and one month after an uncomplicated laparoscopic cholecystectomy. An ambulatory continuous pressure recording was obtained from 5 PM to 8 AM with a sampling frequency of 4 Hz. At 6 PM, the patients received a 1400-kJ standard meal. The size of the bile acid pool after cholecystectomy was measured according to the dilution principle using [C14]cholic acid as the marker. Preoperatively the migrating motor complex (MMC) cycle was 0.48/hr (quartiles 0.42-0.68) compared to 0.68/hr (0.43-0.77) postoperatively. This difference was not significant. An increase in the MMC cycle frequency was observed postoperatively in three patients, and a decrease was seen in four patients. The migration velocity was 5.61 cm/min (4.26-8.01) preoperatively and 7.16 cm/min (4.79-9.71) postoperatively, a difference that was not significant. The time period from meal ingestion to appearance of phase III was 297 min (218-431) at the preoperative examination and 443 min (192-494) at the postoperative examination. This difference was not significant. The size of the bile acid pool after cholecystectomy was 3.68 mmol (2.69-8.47) and was not significantly correlated to the frequency of the MMC cycle or the time period from food ingestion to phase III activity. It is concluded that in gallstone patients with a normally functioning gallbladder, cholecystectomy does not alter duodenal motility, which was not correlated to the size of the bile acid pool.

Sluggish small bowel motility is involved in determining increased biliary deoxycholic acid in cholesterol gallstone patients

OBJECTIVE

Our aim was to establish whether small intestine transit time is defective in subjects with cholesterol gallstones.

METHODS

We enrolled 10 patients (eight women, two men; mean age, 48.7 yr; mean body mass index [BMI], 22.4 Kg/m2) with recently diagnosed cholelithiasis, with no liver pathology, who were not taking any drugs, and 11 comparable healthy volunteers (eight women, three men; mean age, 46.2 yr; mean BMI, 22.7 Kg/m2), who served as controls. All subjects underwent orocecal (by starch breath test technique and serum assays of salazopyrin), oroileal (by serum assays of tauroursodeoxycholic acid), and duodenoileal (by serum assays of taurocholic acid) transit times; cholesterol saturation index; and bile acid composition and gallbladder motility studies (by ultrasound). For serum assays, blood samples were collected over a period of 7 h. Gallbladder motility and orocecal transit time were evaluated simultaneously.

RESULTS

All four means of assessing transit time gave longer times in cholesterol gallstone patients than in controls: orocecal transit time (salazopyrin) = 366 +/- 13 vs 258 +/- 16 min, p < 0.0005; orocecal transit time (starch breath test) = 415 +/- 139 vs 290 +/- 15 min, p < 0.01; duodenoileal transit time: 272 +/- 23 vs 205 +/- 23 min, p < 0.03; and oroileal transit time: 308 +/- 18 vs 230 +/- 19 min, p < 0.009. Cholesterol gallstone patients showed an increase in percent molar biliary deoxycholic acid (30% +/- 4.5% vs 16% +/- 1.3%, p < 0.02) and a decrease in percent molar cholic acid 32% +/- 2.2% vs 40% +/- 1.3%, p < 0.03) and chenodeoxycholic acid (34% +/- 3% vs 41% +/- 1.8%, p < 0.03), compared with controls; patients also had greater percent molar biliary cholesterol. A linear relationship (r2 = 0.6324, p = 0.0012) between biliary deoxycholic acid and small bowel transit time was found. Residual gallbladder volumes were larger in cholesterol gallstone patients (11.38 +/- 1.27 vs 7.55 +/- 0.39 ml, p < 0.04), whereas basal gallbladder volumes, although higher, did not reach statistical significance (24.25 +/- 2.41 vs 19.98 +/- 1.63 ml; p = ns).

CONCLUSIONS

This study confirms that patients with cholesterol gallstones have delayed small bowel transit, defective gallbladder motor function, and increased biliary deoxycholic acid. Delayed small bowel transit may contribute to supersaturation of bile with cholesterol by increasing deoxycholic acid production.

Risk of colorectal cancer and other cancers in patients with gall stones

BACKGROUND

The occurrence of gall stones has repeatedly been associated with an increased risk for cancer of the colon, but risk associated with cholecystectomy remains unclear.

AIMS

To evaluate the hypothesis in a nationwide cohort of more than 40,000 gall stone patients with complete follow up including information of cholecystectomy and obesity.

PATIENTS

In the population based study described here, 42,098 patients with gall stones in 1977-1989 were identified in the Danish Hospital Discharge Register.

METHODS

These patients were linked to the Danish Cancer Registry to assess their risks for colorectal and other cancers during follow up to the end of 1992.

RESULTS

The analysis showed a modest increase in the number of cancers at all sites combined (n = 3940; RR, 1.07; 95% confidence intervals (CI), 1.0 to 1.1). A weak association was found for cancer of the colon (n = 360; RR, 1.09; 95% CI 1.0 to 1.2), which remained unchanged when analysed by sex, anatomical subsite, and duration of follow up. Multivariate analysis with adjustment for cholecystectomy and clinically defined obesity did not change these estimates to any significant extent. Excess risks were found for cancers of the pancreas and the small intestine. A non-significant increased risk for breast cancer was seen in women five years after initial discharge for gall stones.

CONCLUSION

A borderline significant association was seen between gall stones and cancer of the colon, and for cancer of pancreas and small intestine as well as for breast cancer in women.