Roles of cholesterol and bile salts in the pathogenesis of gallbladder hypomotility and inflammation: cholecystitis is not caused by cystic duct obstruction

Gallbladder dysfunction caused by MYPT1 ablation triggers cholestasis-induced hepatic fibrosis in mice

BACKGROUND

The incidence of gallbladder diseases is as high as 20%, but whether gallbladder diseases contribute to hepatic disorders remains unknown.

METHODS

Here, we established an animal model of gallbladder dysfunction and assessed the role of a diseased gallbladder in cholestasis-induced hepatic fibrosis (CIHF).

RESULTS

Mice with smooth muscle-specific deletion of Mypt1, the gene encoding the main regulatory subunit of myosin light chain phosphatase (myosin phosphatase target subunit 1 [MYPT1]), had apparent dysfunction of gallbladder motility. This dysfunction was evidenced by abnormal contractile responses, namely, inhibited cholecystokinin 8-mediated contraction and nitric oxide-resistant relaxation. As a consequence, the gallbladder displayed impaired bile filling and biliary tract dilation comparable to the alterations in CIHF. Interestingly, the mutant animals also displayed CIHF features, including necrotic loci by the age of 1 month and subsequently exhibited progressive fibrosis and hyperplastic/dilated bile ducts. This pathological progression was similar to the phenotypes of the animal model with bile duct ligation and patients with CIHF. The characteristic biomarker of CIHF, serum alkaline phosphatase activity, was also elevated in the mice. Moreover, we observed that the myosin phosphatase target subunit 1 protein level was able to be regulated by several reagents, including lipopolysaccharide, exemplifying the risk factors for gallbladder dysfunction and hence CIHF.

CONCLUSIONS

We propose that gallbladder dysfunction caused by myosin phosphatase target subunit 1 ablation is sufficient to induce CIHF in mice, resulting in impairment of the bile transport system.

Lysimachia christinae polysaccharide attenuates diet-induced hyperlipidemia via modulating gut microbes-mediated FXR-FGF15 signaling pathway

Polysaccharides are one of the most abundant and active components of Lysimachia christinae (L. christinae), which is widely adopted for attenuating abnormal cholesterol metabolism; however, its mechanism of action remains unclear. Therefore, we fed a natural polysaccharide (NP) purified from L. christinae to high-fat diet mice. These mice showed an altered gut microbiota and bile acid pool, which was characterized by significantly increased Lactobacillus murinus and unconjugated bile acids in the ileum. Oral administration of the NP reduced cholesterol and triglyceride levels and enhanced bile acid synthesis via cholesterol 7α-hydroxylase. Additionally, the effects of NP are microbiota-dependent, which was reconfirmed by fecal microbiota transplantation (FMT). Altered gut microbiota reshaped bile acid metabolism by modulating bile salt hydrolase (BSH) activity. Therefore, bsh genes were genetically engineered into Brevibacillus choshinensis, which was gavaged into mice to verify BSH function in vivo. Finally, adeno-associated-virus-2-mediated overexpression or inhibition of fibroblast growth factor 15 (FGF15) was used to explore the farnesoid X receptor-fibroblast growth factor 15 pathway in hyperlipidemic mice. We identified that the NP relieves hyperlipidemia by altering the gut microbiota, which is accompanied by the active conversion of cholesterol to bile acids.

MAFLD and Celiac Disease in Children

Celiac disease (CD) is an immune-mediated systemic disorder elicited by the ingestion of gluten whose clinical presentation ranges from the asymptomatic form to clinical patterns characterized by multiple systemic involvement. Although CD is a disease more frequently diagnosed in patients with symptoms of malabsorption such as diarrhea, steatorrhea, weight loss, or failure to thrive, the raised rate of overweight and obesity among general pediatric and adult populations has increased the possibility to diagnose celiac disease in obese patients as well. Consequently, it is not difficult to also find obesity-related disorders in patients with CD, including "metabolic associated fatty liver disease" (MAFLD). The exact mechanisms linking these two conditions are not yet known. The going assumption is that a gluten-free diet (GFD) plays a pivotal role in determining an altered metabolic profile because of the elevated content of sugars, proteins, saturated fats, and complex carbohydrates, and the higher glycemic index of gluten-free products than gluten-contained foods, predisposing individuals to the development of insulin resistance. However, recent evidence supports the hypothesis that alterations in one of the components of the so-called "gut-liver axis" might contribute to the increased afflux of toxic substances to the liver triggering the liver fat accumulation and to the subsequent hepatocellular damage. The aim of this paper was to describe the actual knowledge about the factors implicated in the pathogenesis of hepatic steatosis in pediatric patients with CD. The presented review allows us to conclude that the serological evaluations for CD with anti-transglutaminase antibodies, should be a part of the general workup in the asymptomatic patients with "non-alcoholic fatty liver disease" (NAFLD) when metabolic risk factors are not evident, and in the patients with steatohepatitis when other causes of liver disease are excluded.

Canine extrahepatic biliary disease: what have we learned?

Extrahepatic biliary disease in dogs is commonly encountered in clinical practice worldwide. Diseases in this segment of the biliary tract are diverse and can manifest with mild clinical signs or can be life-threatening. In the last decade there have been advances in diagnostic tests, imaging modalities and therapeutic interventions as well as the identification of novel prognostic variables that could improve outcomes in dogs with extrahepatic biliary disease. Therefore, the objective of this review was to summarise clinically relevant updates of extrahepatic biliary disease in dogs.

Mendelian randomization rules out the causal relationship between serum lipids and cholecystitis

Background

The relationship between serum lipids and cholecystitis is still under investigation. To examine the causal effect of serum lipids on cholecystitis using the Mendelian randomization method.

Methods

We conducted univariable Mendelian randomization (MR) analyses using summary statistics from two independent genome-wide association studies (GWAS) on serum lipids (n = 132,908) and cholecystitis (n = 361,194). Mainly, the inverse-variance weighted (IVW) method was utilized to combine each SNP’s causal estimation, and the MR-Egger was adopted as a complementary method, together with the weighted median. Cochrane’s Q value was employed to appraise heterogeneity. The MR-Egger intercept and MR-PRESSO were used to detect the horizontal pleiotropy.

Results

Our univariable results displayed a minor protective effect of serum low-density lipoprotein (LDL) cholesterol (OR [95% CI] = 0.9984483 [0.9984499, 0.9984468]; p = 0.008) on cholecystitis. No significant causal effect of total cholesterol (TC) (OR [95% CI] = 0.9994228 [0.9994222, 0.9994233]; p = 0.296), triglycerides (OR [95% CI] = 0.9990893 [0.9990882, 0.9990903]; p = 0.238) and high-density lipoprotein (HDL) cholesterol (OR [95% CI] = 0.9997020 [0.9997017, 0.9997023]; p = 0.565) was found on cholecystitis.

Conclusion

These findings suggest that LDL cholesterolhas a slight protective effect on cholecystitis, which can be easily affected by confounding factors. TC, triglycerides and HDL cholesterol don’t have causal effect on cholecystitis. The protective effect of serum lipids on cholecystitis, though possible, remain less certain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-01082-y.

Serum 25-hydroxyvitamin D concentrations in dogs with gallbladder mucocele

Gallbladder mucocele (GBM) is a common biliary disorder in dogs. Gallbladder hypokinesia has been proposed to contribute to its formation and progression. The specific cause of gallbladder stasis in dogs with GBM as well as viable treatment options to resolve dysmotility remains unknown. Vitamin D deficiency is one of the many potential causes of gallbladder hypokinesia in humans and repletion results in complete resolution of stasis. Improving our understanding of the relationship between serum vitamin D and GBM could help identify dogs as a model for humans with gallbladder hypokinesia. Furthermore, this relationship could provide insight into the pathogenesis of GBM and support the need for future studies to investigate vitamin D as a novel treatment target. Therefore, goals of this study were i) to determine if serum 25-hydroxyvitamin(OH)D concentrations were decreased in dogs with GBM, ii) if serum 25(OH)D concentrations were different in clinical versus dogs subclinical for GBM, and iii) to determine if serum 25(OH)D concentrations could predict the ultrasonographic type of GBM. Sixty-two dogs (clinical, n = 26; subclinical, n = 36) with GBM and 20 healthy control dogs were included in this prospective observational study. Serum 25(OH)D concentrations were measured with a competitive chemiluminescence immunoassay. Overall, dogs with GBM had lower serum 25(OH)D concentrations than control dogs (P = 0.004). Subsequent subgroup analysis indicated that this difference was only significant in the subclinical group compared to the control dogs (P = 0.008), and serum 25(OH)D concentrations did not significantly differ between dogs clinical for GBM versus subclinical or control dogs, indicating that inflammatory state in clinical dogs was not the major constituent of the observed findings. Decreasing serum 25(OH)D concentrations, but not clinical status, was associated with a more advanced developmental stage of GBM type determined by ultrasonography. Our results indicate that vitamin D has a role in dogs with GBM. Additional studies are needed to assess if reduced vitamin D in dogs with GBM is a cause or effect of their biliary disease and to investigate if vitamin D supplementation could be beneficial for dogs with GBM.

Identification of a new genetic variant associated with cholecystitis: A multicenter genome-wide association study

BACKGROUND

The genomic landscape of gallbladder disease remains poorly understood. We sought to examine the association between genetic variants and the development of cholecystitis.

METHODS

The Biobank of a large multi-institutional health care system was used. All patients with cholecystitis were identified using International Statistical Classification of Diseases, 10th Revision, codes and genotyped across six batches. To control for population stratification, data were restricted to that from individuals of European genomic ancestry using a multidimensional scaling approach. The association between single nucleotide polymorphisms and cholecystitis was evaluated with a mixed linear model-based analysis, controlling for age, sex, and obesity. The threshold for significance was set at 5 × 10.

RESULTS

Of 24,635 patients (mean ± SD age, 60.1 ± 16.7 years; 13,022 females [52.9%]), 900 had cholecystitis (mean ± SD age, 65.4 ± 14.3 years; 496 females [55.1%]). After meta-analysis, three single nucleotide polymorphisms on chromosome 5p15 exceeded the threshold for significance (p < 5 × 10). The phenotypic variance of cholecystitis explained by genetics and controlling for sex and obesity was estimated to be 17.9%.

CONCLUSION

Using a multi-institutional genomic Biobank, we report that a region on chromosome 5p15 is associated with the development of cholecystitis that can be used to identify patients at risk.

LEVEL OF EVIDENCE

Prognostic and epidemiological, Level III.

Kinetics of Gallbladder Emptying During Cholecystokinin Cholescintigraphy as an Indicator of In Vivo Hormonal Sensitivity

Cholecystokinin cholescintigraphy is used clinically to quantify gallbladder ejection fraction as an indicator of functional gallbladder disorder. It can also provide the opportunity to quantify an individual's responsiveness to the physiologic stimulant of gallbladder contraction, cholecystokinin, which is a major regulator of appetite and postprandial satiety. Methods: In the current work, we use cholecystokinin cholescintigraphy to quantify the kinetics of gallbladder emptying, including average and peak rates, in response to a standard cholecystokinin infusion. Results: We demonstrated that patients with no gallstones or biliary obstruction who empty their gallbladders completely in response to cholecystokinin, having an ejection fraction greater than 80%, exhibit a broad range of sensitivity to this hormone. Three distinct kinetic profiles were observed, with those most sensitive to cholecystokinin achieving the earliest peak and the fastest rate of gallbladder emptying, whereas those least sensitive to cholecystokinin have the latest peak and the slowest rate of emptying. Conclusion: Patients can have abnormal cholecystokinin stimulus-activity coupling as an effect of endogenous negative allosteric modulation by membrane cholesterol. This was predicted in ex vivo studies but has not, to our knowledge, previously been demonstrated in vivo. This type of kinetic analysis provides a tool to quantify cholecystokinin responsiveness in patients and identify patients who might benefit from a drug that would positively modulate cholecystokinin action to improve their appetite regulation and to better control their weight.

Acute acalculous cholecystitis in children

Acute acalculous cholecystitis (AAC) is the inflammatory disease of the gallbladder in the absence of gallstones. AAC is estimated to represent at least 50% to 70% of all cases of acute cholecystitis during childhood. Although this pathology was originally described in critically ill or post-surgical patients, most pediatric cases have been observed during several infectious diseases. In addition to cases caused by bacterial and parasitic infections, most pediatric reports after 2000 described children developing AAC during viral illnesses (such as Epstein-Barr virus and hepatitis A virus infections). Moreover, some pediatric cases have been associated with several underlying chronic diseases and, in particular, with immune-mediated disorders. Here, we review the epidemiological aspects of pediatric AAC, and we discuss etiology, pathophysiology and clinical management, according to the cases reported in the medical literature.

Pharmacological effects of nanoencapsulation of human-based dosing of probucol on ratio of secondary to primary bile acids in gut, during induction and progression of type 1 diabetes

INTRODUCTION

The ratio of secondary to primary bile acids changes during Type 1 Diabetes (T1D) development and these effects might be ameliorated by using cholesterol lowering drugs or hydrophilic bile acids. Probucol is a cholesterol-lowering drug, while ursodeoxycholic acid is a hydrophilic bile acid. This study investigated whether nanoencapsulated probucol with ursodeoxycholic acid altered bile acid ratios and the development of diabetes.

METHODS

Balb/c mice were divided into three groups and gavaged daily with either free probucol, nanoencapsulated probucol or nanoencapsulated probucol with ursodeoxycholic acid for seven days. Alloxan was injected and once T1D was confirmed the mice continued to receive daily gavages until euthanasia. Blood, tissues, faeces and urine were collected for analysis of insulin and bile acids.

RESULTS AND CONCLUSIONS

Nanoencapsulated probucol-ursodeoxycholic acid resulted in significant levels of insulin in the blood, lower levels of secondary bile acids in liver and lower levels of primary bile acids in brain, while ratio of secondary to primary bile acids remains similar among all groups, except in the faeces. Findings suggests that nanoencapsulated probucol-ursodeoxycholic acid may exert a protective effect on pancreatic β-cells and reserve systemic insulin load via modulation of bile acid concentrations in the liver and brain.

Effect of prednisolone administration on gallbladder emptying rate and gallbladder bile composition in dogs

OBJECTIVE To investigate effects of prednisolone administration on gallbladder emptying rate and gallbladder bile composition in dogs. ANIMALS 6 healthy Beagles. PROCEDURES Prednisolone was administered (2 mg/kg, SC, once daily for 2 weeks) to each dog and tapered over 2 weeks. Gallbladder emptying rate and bile composition were evaluated before and after administration of prednisolone for 2 weeks as well as 1 week after cessation of prednisolone administration. RESULTS Gallbladder emptying rate decreased significantly after prednisolone administration (median, 27%; range, 0% to 38%), compared with rate before administration (median, 59%; range, 29% to 68%), but then increased 1 week after cessation of administration (median, 45%; range, 23% to 48%). Gallbladder bile mucin concentration decreased significantly after prednisolone administration (median, 8.8 mg/dL; range, 6.2 to 11.3 mg/dL), compared with concentration before administration (median, 13.1 mg/dL; range, 10.7 to 21.7 mg/dL), but then increased 1 week after cessation of administration (median, 14.3 mg/dL; range, 9.6 to 26.7 mg/dL). Gallbladder taurochenodeoxycholic acid concentration decreased significantly after prednisolone administration (8.1 mmol/L; range, 6.8 to 15.2 mmol/L), compared with concentration before administration (median, 27.2 mmol/L; range, 22.0 to 31.9 mmol/L), but then increased 1 week after cessation of administration (median, 26.4 mmol/L; range, 15.1 to 31.5 mmol/L). CONCLUSIONS AND CLINICAL RELEVANCE A lower gallbladder emptying rate caused by prednisolone administration may be involved in the pathogenesis of gallbladder disease in dogs. Further studies are required to determine the clinical importance of lower gallbladder bile mucin concentrations caused by glucocorticoid administration in the pathogenesis of gallbladder disease in dogs.

Effect of a high-fat-high-cholesterol diet on gallbladder bile acid composition and gallbladder motility in dogs

OBJCTIVE To investigate the effects of dietary lipid overload on bile acid metabolism and gallbladder motility in healthy dogs. ANIMALS 7 healthy Beagles. PROCEDURES In a crossover study, dogs were fed a high-fat-high-cholesterol diet (HFCD) or a low-fat diet (LFD) for a period of 2 weeks. After a 4-month washout period, dogs were fed the other diet for 2 weeks. Before and at the end of each feeding period, the concentrations of each of the gallbladder bile acids, cholecystokinin (CCK)-induced gallbladder motility, and bile acid metabolism-related hepatic gene expression were examined in all dogs. RESULTS The HFCD significantly increased plasma total cholesterol concentrations. The HFCD also increased the concentration of taurochenodeoxycholic acid and decreased the concentration of taurocholic acid in bile and reduced gallbladder contractility, whereas the LFD significantly decreased the concentration of taurodeoxycholic acid in bile. Gene expression analysis revealed significant elevation of cholesterol 7α-hydroxylase mRNA expression after feeding the HFCD for 2 weeks, but the expression of other genes was unchanged. CONCLUSIONS AND CLINICAL RELEVANCE Feeding the HFCD and LFD for 2 weeks induced changes in gallbladder bile acid composition and gallbladder motility in dogs. In particular, feeding the HFCD caused an increase in plasma total cholesterol concentration, an increase of hydrophobic bile acid concentration in bile, and a decrease in gallbladder sensitivity to CCK. These results suggested that similar bile acid compositional changes and gallbladder hypomotility might be evident in dogs with hyperlipidemia.

The expression of hepatic carboxypeptidase E is decreased in patients with cholesterol gallstone

BACKGROUND/AIMS

Decreased carboxypeptidase E (CPE) expression is associated with numerous pathophysiological conditions. This study aimed to investigate the potential function of hepatic CPE in cholesterol gallstone formation.

PATIENTS AND METHODS

Patients with cholesterol gallstone (CGS group) and patients without cholesterol gallstones (non-CGS group) were enrolled. The serum total cholesterol, triglyceride, and biliary composition were analyzed. Eight liver samples from two patients without CGS and six patients with CGS were subjected to cDNA microarray analysis. Hepatic CPE expression was detected by quantitative real-time polymerase chain reaction (qRT-PCR), Western blot, and immunohistochemical analysis. Plasma CCK level was measured by ELISA.

RESULTS

cDNA microarray identified CPE as a gene downregulated in the CGS group. RT-PCR showed that CPE mRNA level was lower in CGS group than in control (P < 0.05, t-test). Moreover, Western blot and immunohistochemistry analysis showed that CPE protein level was significantly lower in CGS group than in the control group. In addition, plasma CCK level was lower in CGS group than in the control group. A positive correlation was found between serum CCK level and hepatic CPE mRNA level (r2 = 0.713, P = 0.003).

CONCLUSIONS

Down-expression of liver CPE may reduce the secretion of serum CCK and contribute to the formation of cholesterol gallstone.

Ursodeoxycholic acid and diets higher in fat prevent gallbladder stones during weight loss: a meta-analysis of randomized controlled trials

BACKGROUND & AIMS

The prevalence of gallstones is increasing in association with the obesity epidemic, but rapid weight loss also increases the risk of stone formation. We conducted a systematic review of the efficacy of strategies to prevent gallbladder stones in adults as they lose weight.

METHODS

Randomized controlled trials of nonsurgical strategies to prevent gallstones were identified by electronic and manual searches. Our final analysis included 13 trials, comprising 1836 participants undergoing weight loss through dieting (8 trials) or bariatric surgery (5 trials). The trials compared ursodeoxycholic acid (UDCA) or high-fat weight loss diets with control interventions. We performed random-effects meta-analyses and evaluated heterogeneity and bias with subgroup, sensitivity, regression, and sequential analysis.

RESULTS

UDCA reduced the risk of ultrasound-verified gallstones compared with control interventions (risk ratio, 0.33; 95% confidence interval [CI], 0.18-0.60; number needed to treat, 9). This effect was significantly larger in trials of diets alone (risk ratio, 0.17; 95% CI, 0.11-0.25) than in trials of patients who underwent bariatric surgery (risk ratio, 0.42; 95% CI, 0.21-0.83) (test for subgroup differences, P =.03). UDCA reduced the risk of cholecystectomy for symptomatic stones (risk ratio, 0.20; 95% CI, 0.07-0.53). Diets high in fat content also reduced gallstones, compared with those with low fat content (risk ratio, 0.09; 95% CI, 0.01-0.61). The meta-analyses were confirmed in trials with a low risk of bias but not in sequential analysis. No additional beneficial or harmful outcomes were identified.

CONCLUSIONS

On the basis of a meta-analysis of randomized controlled trials, during weight loss, UDCA and/or higher dietary fat content appear to prevent formation of gallstones.

An analysis of the role of the indigenous microbiota in cholesterol gallstone pathogenesis

BACKGROUND AND AIMS

Cholesterol gallstone disease is a complex process involving both genetic and environmental variables. No information exists regarding what role if any the indigenous gastrointestinal microbiota may play in cholesterol gallstone pathogenesis and whether variations in the microbiota can alter cholesterol gallstone prevalence rates.

METHODS

Genetically related substrains (BALB/cJ and BALB/cJBomTac) and (BALB/AnNTac and BALB/cByJ) of mice obtained from different vendors were compared for cholesterol gallstone prevalence after being fed a lithogenic diet for 8 weeks. The indigenous microbiome was altered in these substrains by oral gavage of fecal slurries as adults, by cross-fostering to mice with divergent flora at <1 day of age or by rederiving into a germ-free state.

RESULTS

Alterations in the indigenous microbiome altered significantly the accumulation of mucin gel and normalized gallbladder weight but did not alter cholesterol gallstone susceptibility in conventionally housed SPF mice. Germ-free rederivation rendered mice more susceptible to cholesterol gallstone formation. This susceptibility appeared to be largely due to alterations in gallbladder size and gallbladder wall inflammation. Colonization of germ-free mice with members of altered Schaedler flora normalized the gallstone phenotype to a level similar to conventionally housed mice.

CONCLUSIONS

These data demonstrate that alterations in the gastrointestinal microbiome may alter aspects of cholesterol gallstone pathogenesis and that in the appropriate circumstances these changes may impact cholesterol cholelithogenesis.