Cholesterol Saturation Of Bile Research Articles

The association between trajectory of serum cholesterol, statin dosage, and the risk of recurrent biliary stone diseases

BackgroundStatins may reduce the risk of recurrent gallstone disease by decreasing bile cholesterol saturation and pathogenicity. However, limited studies have investigated this issue. This study aimed to assess whether statin doses and serum cholesterol levels were associated with a decreased risk of recurrent biliary stone diseases after the first event index, with a follow-up time of 15 years. MethodsBased on the Chang Gung Research Database (CGRD) between January 1, 2001, and December 31, 2020, we enrolled 68,384 patients with the International Classification of Diseases, Ninth and Tenth Revision codes of choledocholithiasis. After exclusions, 32,696 patients were divided into non-statin (<28 cDDD, cumulative defined daily doses) (n = 27,929) and statin (≥28 cDDD) (n = 4767) user groups for analysis. Serum cholesterol trajectories were estimated using group-based trajectory modeling (n = 8410). ResultsThe statin users had higher Charlson Comorbidity Index (CCI) scores than the non-statin users. Time-dependent Cox regression analysis showed that statin use >365 cDDD was associated with a significantly lower risk of recurrent biliary stones (adjusted hazard ratio [aHR] = 0.28, 95% CI, 0.24–0.34; p < 00.0001), acute pancreatitis (aHR = 0.24, 95% CI, 0.17–0.32, p < 00.0001), and cholangitis (aHR = 0.28, 95% CI, 0.25–0.32, p < 00.0001). Cholecystectomy was also a protective factor for recurrent biliary stones (aHR = 0.41, 95% CI, 0.37–0.46; p < 00.0001). The higher trajectory serum cholesterol group (Group 3) had a lower risk trend for recurrent biliary stones (aHR = 0.79, p = 0.0700) and a lower risk of cholangitis (aHR = 0.79, p = 0.0071). ConclusionThis study supports the potential benefits of statin use and the role of cholecystectomy in reducing the risk of recurrent biliary stone diseases.

Effects of Biliary Phospholipids on Cholesterol Crystallization and Growth in Gallstone Formation.

The prevalence of cholesterol gallstone disease is increasing, primarily due to the global epidemic of obesity associated with insulin resistance, and this trend leads to a considerable healthcare, financial, and social burden worldwide. Although phospholipids play an essential role in maintaining cholesterol solubility in bile through both mixed micelles and vesicles, little attention has been paid to the impact of biliary phospholipids on the pathogenesis of cholesterol gallstone formation. A reduction or deficiency of biliary phospholipids results in a distinctly abnormal metastable physical-chemical state of bile predisposing to supersaturation with cholesterol. Changes in biliary phospholipid concentrations influence cholesterol crystallization by yielding both liquid crystalline and "anhydrous" crystalline metastable intermediates, evolving into classical parallelogram-shaped cholesterol monohydrate crystals in supersaturated bile. As a result, five distinct crystallization pathways, A-E, have been defined, mainly based on the prime habits of liquid and solid crystals in the physiological or pathophysiological cholesterol saturation of gallbladder and hepatic bile. This review concisely summarizes the chemical structures and physical-chemical properties of biliary phospholipids and their physiological functions in bile formation and cholesterol solubility in bile, as well as comprehensively discusses the latest advances in the role of biliary phospholipids in cholesterol crystallization and growth in gallstone formation, largely based on the findings from clinical and animal studies and in vitro experiments. The insights gleaned from uncovering the cholelithogenic mechanisms are expected to form a fundamental framework for investigating the hitherto elusive events in the earliest stage of cholesterol nucleation and crystallization. This may help to identify better measures for early diagnosis and prevention in susceptible subjects and effective treatment of patients with gallstones.

Curcumin Supplementation Ameliorates Bile Cholesterol Supersaturation in Hamsters by Modulating Gut Microbiota and Cholesterol Absorption.

Curcumin is a polyphenol that has been shown to have prebiotic and cholesterol-lowering properties. This study aimed to investigate the impact of curcumin on bile cholesterol supersaturation and the potential mechanistic role of intestinal microbiota and cholesterol absorption. Male hamsters (n = 8) were fed a high-fat diet (HFD) supplemented with or without curcumin for 12 weeks. Results showed that curcumin significantly decreased cholesterol levels in the serum (from 5.10 to 4.10 mmol/L) and liver (from 64.60 to 47.72 nmol/mg protein) in HFD-fed hamsters and reduced the bile cholesterol saturation index (CSI) from 1.64 to 1.08 due to the beneficial modifications in the concentration of total bile acids (BAs), phospholipids and cholesterol (p < 0.05). Gut microbiota analysis via 16S rRNA sequencing revealed that curcumin modulated gut microbiota, predominantly increasing microbiota associated with BA metabolism and short-chain fatty acid production, which subsequently up-regulated the expression of hepatic cholesterol 7-alpha hydroxylase and increased the synthesis of bile acids (p < 0.05). Furthermore, curcumin significantly down-regulated the expression of intestinal Niemann–Pick C1-like protein 1(NPC1L1) in hamsters and reduced cholesterol absorption in Caco-2 cells (p < 0.05). Our results demonstrate that dietary curcumin has the potential to prevent bile cholesterol supersaturation through modulating the gut microbiota and inhibiting intestinal cholesterol absorption.

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

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

Protective effect of Juniperus Communis extract by inhibition of Pro-nucleating agents in lithogenic diet induced cholelithiasis in mice

Backgroundgallstone disease or cholelithiasis is a disease caused by change in bile secretions and cholesterol saturation to form crystal and blockage in bile duct. Aimthe aim of present study evaluate protective effect of Juniperus Communis extract by inhibition of Pro-nucleating agents in lithogenic diet induced cholelithiasis in mice. Material and methodsMice fed with diet containing 1% cholesterol and 0.5% for six weeks resulted in cholesterol super saturation in gallbladder bile, which promoted the formation of cholesterol gallstones (CGS). In this study, methanolic extract of J. Communis (MEJC) were examined for their antilithogenic potential along with lithogenic (LG) diet for seven weeks. ResultsJ. Communis extracts were reduced the CGS incidence by 15–39%, the effect being a maximum in the methanol extract group. The extract markedly reduced biliary cholesterol. The cholesterol: phospholipids ratio which was 1.56 in the LG diet group was reduced to 0.92–0.97 in the J. Communis extracts groups. Serum and liver cholesterol was decreased by feeding J. Communis extracts to the LG diet. ConclusionJ. Communis extracts exerted antilithogenic influence by decreasing the cholesterol hyper-secretion into bile and increasing the bile acid output thus decreasing the formation of lithogenic bile in experimental mice.

Correlation between Serum Iron, Serum Ferritin and Bile Cholesterol Level in Gallstone Disease

Introduction: The cholesterol stones are formed by super-saturation of the bile with cholesterol. Iron deficiency alters activity of several hepatic enzymes, leading to increased cholesterol saturation of bile in gall bladder thus promoting cholesterol crystallisation. Iron has a role in gallstone pathogenesis and ferritin is the most specific marker for iron levels in the body, but there are less studies which depict correlation between serum iron, serum ferritin and bile cholesterol. Aim: To study the correlation between serum iron, serum ferritin and bile cholesterol level in gallstone patients. Materials and Methods: The observational study was conducted in the Department of Surgery. The study population was 45 patients with gallstone disease. Serum iron, Serum ferritin and Bile cholesterol contents were analysed. Serum cholesterol levels were estimated using Folch method and estimation of bile cholesterol was done by Enzopak kit.Statistical analysis was done by using descriptive and inferential statistics using chi square test and software used in the analysis were SPSS 24.0 version and p&lt;0.05 was considered as level of significance. Results: A positive but negligible correlation between serum iron and serum ferritin was observed (Pearson’s correlation coefficient of 0.247). Negative correlation between serum iron vs serum cholesterol and serum ferritin vs serum cholesterol was observed. Conclusion: It can be concluded that a low value of serum iron and serum ferritin is a risk factor for cholelithiasis, whereas, if the value of bile cholesterol increases then there is a high probability of cholelithiasis.

Serum iron and serum ferritin levels in cholelithiasis: a randomized study

Background: The role of iron in the pathogenesis of gallstone disease has not been well established so far. Iron deficiency has been shown to alter the activity of several hepatic enzymes, leading to increased cholesterol saturation of bile in gall bladder and hence promoting cholesterol crystallization.Serum iron, total iron binding capacity and transferrin saturation are not good indicators of iron status in individuals. In infection free situation, serum ferritin is an ideal indicator for diagnosis of iron deficiency.Methods: The study was conducted as a prospective study in the department of Surgery. The study population was divided into two groups; Case group with 200 patients with gallstone disease and control group with 50 patients without gallstone disease. Serum iron and ferritin contents of both groups will be analyzed and compared with each other.Results: In this study the gallstones are more prevalent in female population than males in ratio of 5.4:1. Serum iron in males was low in 41.93% not comparable 20.8% of control suggesting that low serum iron is not associated with Cholelithiasis in male. In males, serum ferritin was low in 64.5% of cases and 16.66% of controls. Serum ferritin levels were normal in 35.50% of cases and 66.66% of controls and above normal in 16.66% of controls suggesting that low serum ferritin is associated with gall stones in males. In this study, low serum iron was seen in 23.07% of females comparable to 23% low serum iron in control females and low ferritin was seen in 35.50% of female cases as compare to 15.38% of controls.Conclusions: It was concluded that a low body store of serum iron is a risk factor for cholelithiasis in females and serum iron, serum ferritin may be used as marker of iron store so that low serum iron status could be diagnosed at early stage.

Laparoscopic Common Bile Duct Exploration for Choledocholithiasis During a Pregnancy: a Case Report

SummaryIn population studies, gallstones are found in 6.5% to 8.4% of nulliparous women, and in 18.4% to 19.3% of women with two to three or more pregnancies (7). Approximately 1 in 500 to 1 in 635 women will require non-obstetrical abdominal surgery during their pregnancies. Pregnancy induced physiological hormonal changes are associated with a decrease of gallbladder motility and increased cholesterol saturation of bile, leading to biliary stone formation (12,6,8). Surgical approach nowadays is the method of choice in the management of symptomatic gallstone disease during pregnancy, preferably if possible surgery should be postponed to second trimester (7,8).Preoperative radiologic imaging using magnetic resonance cholangiopancreatography is the golden standard for patients with suspected choledocholithiasis, however, its application during pregnancy is limited (9). Therapeutic endoscopic retrograde cholangiopancreatography (ERCP) may be used before, during or after laparoscopic cholecystectomy when it is indicated, but unfortunately, its application during pregnancy is associated with considerable number of complications concerning mother and fetus. Alternative approach has been developed and recommended for patients with the common bile duct (CBD) stones providing laparoscopic common bile duct exploration (LCBDE). Intraoperative cholangiography or intraoperative ultrasound (IOUS) are the methods currently used for detection of the CBD stones during laparoscopic cholecystectomy, however, IOUS can be considered as the method of choice during pregnancy (3).IOUS is a dynamic imaging modality that provides interactive and timely information during surgical procedures. Because the transducer is in direct contact with the organ being examined, high-resolution images can be obtained that are not degraded by air, bone, or overlying soft tissue (1).

Abdominal visceral fat accumulation measured by computed tomography associated with an increased risk of gallstone disease.

Visceral adiposity is a strong determinant of insulin resistance, which decreases cholecystokinin response sensitivity, and increases cholesterol saturation in the gallbladder bile; thus, it potentially relates to gallstone disease development. We aimed to investigate whether visceral fat measured by computed tomography (CT) is a risk factor for gallstone disease. A cohort of 717 participants undergoing CT and ultrasonography was analyzed. The associations between body mass index (BMI), visceral adipose tissue (VAT) area, subcutaneous adipose tissue (SAT) area, and gallstone disease were analyzed adjusted for age, sex, hypertension, diabetes, and dyslipidemia. In multivariate analysis, gallstone disease was significantly associated with VAT and SAT areas for both categorical data and trend (P for trend < 0.001, 0.009), but not body mass index (BMI). Among patients with BMI < 25, gallstone disease remained significantly associated with VAT area (P for trend 0.021) and SAT area (P for trend 0.005). Interactions between the obesity indices and being elderly on the risk of gallstone disease were found; specifically BMI (P = 0.005), SAT (P < 0.001), and VAT (P = 0.154). A significant association between all obesity indices and gallstone disease was seen in patients aged < 65 but not among those aged ≥ 65. However, no significant association was noted between the obesity indices and sex. CT-measured adipose tissue, rather than BMI, was a better predictor for risk of gallstone disease. This finding applies to younger people or even those with normal body weight, suggesting the importance of abdominal visceral fat accumulation in the development of gallstone disease.

Correlation of retinol binding protein 4 with metabolic indexes of glucose and lipid, bile cholesterol saturation index

To measure retinol binding protein 4 (RBP4) levels in serum and bile and to analyze their relationship with insulin resistance, dyslipidemia or cholesterol saturation index (CSI). A total of 60 patients with gallstone were divided into a diabetes group (n=30) and a control group (n=30). The concentrations of RBP4 in serum and bile were detected by enzyme-linked immunosorbent assay (ELISA). Enzyme colorimetric method was used to measure the concentration of biliary cholesterol, bile acid and phospholipid. Biliary CSI was calculated by Carey table. Partial correlation and multiple linear regression analysis were used to evaluate the correlation between the RBP4 levels in serum or bile and the above indexes. The RBP4 concentrations in serum and bile in the diabetes group were significantly elevated compared with those in the control group (both P<0.01). There was no significant difference in the serum total bile acid (TBA), serum triglyceride (TG), serum high-density lipoprotein (HDL), bile TBA, bile total cholesterol (TC) , bile phospholipids and bile CSI between the 2 groups (all P>0.05); but the serum TC, low density lipoprotein (LDL), fasting blood glucose (FBG), fasting insulin (FINS), and homeostasis model assessment for insulin resistance (HOMA-IR) in the diabetes group were significantly increased compared to those in the control group (all P<0.05). The partial correlation analysis, which was adjusted by age, showed that the bile RBP4 was positively correlated with body mass index (BMI), waist circumference (WC), FINS, FBG, TC, LDL and HOMA-IR (r=0.283, 0.405, 0.685, 0.667, 0.553, 0.424 and 0.735, respectively), and the serum RBP4 was also positively correlated with the WC, FINS, FBG, TC, LDL and HOMA-IR (r=0.317, 0.734, 0.609, 0.528, 0.386 and 0.751, respectively). Stepwise multivariate linear regression analysis suggested that the HOMA-IR, BMI and WC were independently correlated with the level of bile RBP4 (multiple regression equation: Ybile RBP4=2.372XHOMA-IR+0.420XBMI+0.178XWC-26.813), and the serum RBP4 level was correlated with the HOMA-IR and WC independently (multiple regression equation: Yserum RBP4=2.832XHOMA-IR +0.235XWC-20.128). Multiple regression equations showed that HOMA-IR was the strongest correlation factor with RBP4. RBP4 concentrations in serum and bile in the diabetes group are significantly higher than those in the control group. HOMA-IR, BMI and WC are independently correlated with the level of bile RBP4. HOMA-IR and WC are independently correlated with the serum RBP4 level. HOMA-IR is the strongest correlation factor with RBP4. RBP4 might play an important role in the course of gallstone formation in Type 2 diabetes mellitus.

Postmenopausal Estrogen Therapy and Risk of Gallstone Disease: A Population-Based Case–Control Study

Female gender and increasing age are key risk factors for gallstone disease; therefore, postmenopausal women are at high risk. Estrogen increases cholesterol saturation of bile and may further increase gallstone risk, but population-based evidence is sparse. Our objective was to examine the association between postmenopausal estrogen therapy and risk of gallstone disease and the impact of duration of treatment and use of opposing progestin. We conducted a population-based case-control study. Cases were postmenopausal women (defined as aged ≥45years) with gallstone disease identified in the period 1996-2010. For each case, we selected ten population controls matched to cases by age and sex. We defined exposure as any use of estrogen (opposed and unopposed by progestin). Cases/controls were categorized as current estrogen users if their last prescription was redeemed <90days before gallstone diagnosis (or corresponding date for controls); all other users were categorized as former users. The reference group consisted of cases/controls with no/rare estrogen use. Medical databases covering the population of Northern Denmark (2.4 million inhabitants through the period 1996-2010). We used conditional logistic regression to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of gallstone disease in women treated with estrogen. The ORs were adjusted for relevant comorbidity, other drugs known to influence gallstone risk, and parity. We identified 16,386 cases with gallstone disease and 163,860 controls. A total of 1,425 cases (8.7%) and 8,930 controls (5.4%) were current estrogen users, yielding an adjusted OR for gallstone disease of 1.74 (95% CI 1.64-1.85) compared with non-users. The corresponding adjusted OR for former users was 1.35 (95% CI 1.28-1.42). The results suggested a duration response for current users. Use of unopposed estrogen was associated with higher adjusted ORs than estrogen opposed by progestin. Postmenopausal estrogen therapy was associated with increased risk of gallstone disease in current and former estrogen users. Use of unopposed estrogen was associated with higher risk than use of estrogen opposed by progestin; this finding needs to be confirmed and explored further in future studies.

Lipid Lowering Drugs and Gallstones: A Therapeutic Option?

Cholelithiasis is a common disease worldwide. The majority of gallstones can occur when the bile is supersaturated with cholesterol. Dyslipidaemia, obesity, insulin resistance are associated with an increased risk for cholesterol gallstone formation as well as with vascular risk. Statins and ezetimibe are used to treat dyslipidaemia and appear to have some effect on bile composition and cholesterol gallstone formation. Statin (e.g. pravastatin, simvastatin, fluvastatin and lovastatin) monotherapy or combined with ursodeoxycholic acid (UDCA) have shown reductions in bile cholesterol saturation, preventing gallstone formation and even dissolving pre-existing stones. However, this effect was not consistently reported in all studies. Statin use has also been associated with a reduced risk for cholecystectomy in 2 large epidemiological studies. Ezetimibe was shown to have a beneficial action against cholelithiasis in animal studies but data in humans - although promising - are very limited. The effect of these drugs on gallstone disease warrants further investigation in large human trials. We also consider the links between cholelithiasis, vascular risk and the use of lipid lowering drugs.

Niemann‐Pick C2 Protein Expression Regulates Lithogenic Diet‐Induced Gallstone Formation and Dietary Cholesterol Metabolism in Mice

Niemann-Pick C2 protein (NPC2) is a lysosomal soluble protein that is highly expressed in the liver; it binds to cholesterol and is involved in intracellular cholesterol trafficking, allowing the exit of lysosomal cholesterol obtained via the lipoprotein endocytic pathway. Thus, this protein may play an important role in controlling hepatic cholesterol transport and metabolism. The aim of this work was to study the relevance of NPC2 protein expression in hepatic cholesterol metabolism, biliary lipid secretion and gallstone formation by comparing NPC2 hypomorph [NPC2 (h/h)] and wild-type mice fed control, 2% cholesterol, and lithogenic diets. NPC2 (h/h) mice exhibited resistance to a diet-induced increase in plasma cholesterol levels. When consuming the chow diet, we observed increased biliary cholesterol and phospholipid secretions in NPC2 (h/h) mice. When fed the 2% cholesterol diet, NPC2 (h/h) mice exhibited low and high gallbladder bile cholesterol and phospholipid concentrations, respectively. NPC2 (h/h) mice fed with the lithogenic diet showed reduced biliary cholesterol secretion, gallbladder bile cholesterol saturation, and cholesterol crystal and gallstone formation. This work indicates that hepatic NPC2 expression is an important factor in the regulation of diet-derived cholesterol metabolism and disposal as well as in diet-induced cholesterol gallstone formation in mice.

Bile acids: chemistry, pathochemistry, biology, pathobiology, and therapeutics.

Bile acids and bile alcohols in the form of their conjugates are amphipathic end products of cholesterol metabolism with multiple physiological functions. The great variety of bile acids and bile alcohols that are present in vertebrates are tabulated. Bile salts have an enterohepatic circulation resulting from efficient vectorial transport of bile salts through the hepatocyte and the ileal enterocyte; such transport leads to the accumulation of a pool of bile salts that cycles between the liver and intestine. Bile salt anions promote lipid absorption, enhance tryptic cleavage of dietary proteins, and have antimicrobial effects. Bile salts are signaling molecules, activating nuclear receptors in the hepatocyte and ileal enterocyte, as well as an increasing number of G-protein coupled receptors. Bile acids are used therapeutically to correct deficiency states, to decrease the cholesterol saturation of bile, or to decrease the cytotoxicity of retained bile acids in cholestatic liver disease.

Body mass index, alcohol, tobacco and symptomatic gallstone disease: a Swedish twin study

Both genetic and environmental factors are involved in the pathogenesis of gallstone disease (GD). We aimed to examine the association between symptomatic GD and overweight (body mass index, BMI, 25-30 kg m(-2)), obesity (BMI > 30 kg m(-2)), alcohol, smoking and smoke-free tobacco by analysing a large twin population. The Swedish Twin Registry (STR) was linked to the Swedish Hospital Discharge and Causes of Death Registries for GD and GD-surgery related diagnoses. Weight, height, use of alcohol, smoking and smoke-free tobacco were provided by STR and analysed for possible associations by conditional logistic regression. Overweight and obesity were associated with a significantly higher risk for symptomatic GD in the whole study population (OR 1.86 and OR 3.38; CI: 1.52-2.28 and 2.28-5.02 respectively). High alcohol consumption was associated with a lower risk for GD in the whole population (OR 0.62; CI: 0.51-0.74) with no difference between discordant monozygotic and dizygotic twins (OR 1.08 and OR 0.96; CI: 0.82-1.42 and 0.79-1.16). Smoking or smoke-free tobacco was not correlated with GD. Consistent with epidemiological studies, we found positive associations between BMI and the development of symptomatic GD. High alcohol consumption was associated with a decreased risk against GD. Tobacco use has no impact on GD.

Genetic evidence that apolipoprotein E4 is not a relevant susceptibility factor for cholelithiasis in two high-risk populations

Apolipoprotein E (apoE) isoforms are genetic determinants of interindividual variations in lipid metabolism. To assess whether apoE is a genetic risk factor for cholesterol gallstone disease (GD), we analyzed apoE variants in populations from Chile and Germany, two countries with very high prevalence rates of this disease. ApoE genotypes were determined in Chilean gallstone patients (n = 117) and control subjects (n = 122) as well as in German gallstone patients (n = 184) and matched controls (n = 184). In addition, we studied apoE variants in subgroups of Chilean patients with strong differences in their susceptibility to acquire gallstones: 50 elderly subjects without gallstones in spite of well-known risk factors for this disease (gallstone-resistant) and 32 young individuals with gallstones but without risk factors (gallstone-susceptible). Furthermore, correlation analysis of apoE genotypes with cholesterol crystal formation times, biliary cholesterol saturation index (CSI), and gallstone cholesterol contents was performed in 81 cholecystectomized patients. In this study analyzing the largest sample set available, apoE4 genotype was not associated with an increased frequency of GD in either population. Moreover, in the Chilean population after adjusting for risk factors such as gender, age, body mass index, serum lipids, and glucose, the odds ratio for the association of the apoE4 allele and GD was significantly (P < 0.05) <1. Also, genotypes were not correlated with cholesterol crystal formation time, CSI, or gallstone cholesterol content. In contrast to previous smaller studies, apoE polymorphisms were not associated with susceptibility to cholesterol GD in high-risk populations.

Gallbladder bile composition in patients with Crohn’s disease

To further elucidate the pathogenesis and mechanisms of the high risk of gallstone formation in Crohn's disease. Gallbladder bile was obtained from patients with Crohn's disease who were admitted for elective surgery (17 with ileal/ileocolonic disease and 7 with Crohn's colitis). Fourteen gallstone patients served as controls. Duodenal bile was obtained from ten healthy subjects before and after the treatment with ursodeoxycholic acid. Bile was analyzed for biliary lipids, bile acids, bilirubin, crystals, and crystal detection time (CDT). Cholesterol saturation index was calculated. The biliary concentration of bilirubin was about 50% higher in patients with Crohn's disease than in patients with cholesterol gallstones. Ten of the patients with Crohn's disease involving ileum and three of those with Crohn's colitis had cholesterol saturated bile. Four patients with ileal disease and one of those with colonic disease displayed cholesterol crystals in their bile. About 1/3 of the patients with Crohn's disease had a short CDT. Treatment of healthy subjects with ursodeoxycholic acid did not increase the concentration of bilirubin in duodenal bile. Several patients with Crohn's disease, with or without ileal resection/disease had gallbladder bile supersaturated with cholesterol and short CDT and contained cholesterol crystals. The biliary concentration of bilirubin was also increased in patients with Crohn's colitis probably not due to bile acid malabsorption. Several factors may be of importance for the high risk of developing gallstones of both cholesterol and pigment types in patients with Crohn's disease.

Gallbladder Na+/H+ exchange activity is up‐regulated prior to cholesterol crystal formation

Gallbladder Na+ and H2O absorption are increased prior to gallstone formation and may promote cholesterol nucleation. Na+/H+ exchange (NHE) isoforms NHE2 and NHE3 are involved in gallbladder Na+ transport in prairie dogs. We examined whether increased gallbladder Na+ absorption observed during early gallstone formation is the result of NHE up-regulation. Native gallbladder and primary cultures of gallbladder epithelial cells (GBECs) harvested from prairie dogs fed nonlithogenic (CON) or 1.2% cholesterol diet for varying lengths of time to induce cholesterol-saturated bile (PreCRYS), cholesterol crystals (CRYS), or gallstones (GS) were used. NHE activity was assessed by measuring dimethylamiloride-inhibitable 22Na+ uptake under H+ gradient in primary GBECs. HOE-694 was used to determine NHE2 and NHE3 contributions. NHE protein and mRNA expression were examined by Western and Northern blots, respectively. Gallbladder total NHE activity was 25.1 +/- 1.3 nmol mg protein(-1) min(-1) in the control and increased during gallstone formation peaking at the PreCRYS stage (98.4 +/- 3.9 nmol mg protein(-1) min(-1)). There was a shift in NHE activity from NHE2 to NHE3 as the animals progressed from no stones through the PreCRYS and CRYS stages to gallstones. The increase in NHE activity was partly caused by an increased Vmax without any change in K(Na)m. Both NHE2 and NHE3 protein increased moderately during the PreCRYS stage without increases in mRNA expression. Increased gallbladder Na+ absorption observed prior to crystal formation is in part caused by an increase NHE activity which is not fully accounted for by an increase in NHE proteins and mRNA levels but may be explained by enhanced localization in the membranes and/or altered regulation of NHE.

Leptin-resistant obese mice do not form biliary crystals on a high cholesterol diet 1,2

Human obesity is associated with leptin resistance and cholesterol gallstone formation. Previously, we demonstrated that leptin-resistant (Lep(db)) obese mice fed a low cholesterol diet have enlarged gallbladders, but a decreased cholesterol saturation index, despite elevated serum cholesterol. Obese humans, however, consume a high cholesterol diet. Therefore, we hypothesized that on a high cholesterol diet, leptin-resistant mice would have cholesterol saturated bile and would form biliary crystals. Eight-week old female lean control (n = 70) and leptin-resistant (n = 72) mice were fed a 1% cholesterol diet for 4 weeks. All animals then had cholecystectomies. Bile was collected, grouped into pools to determine cholesterol saturation index (CSI), and examined for cholesterol crystals. Serum cholesterol and leptin were also measured. Gallbladder volumes for Lep(db) mice were enlarged compared with the lean mice (35.8 microl versus 19.1 microl, P < 0.001), but the CSI for the Lep(db) mice was lower than for the lean animals (0.91 versus 1.15, P < 0.03). The obese animals did not form cholesterol crystals, whereas the lean animals averaged 2.2 crystals per high-powered field (hpf) (P < 0.001). Serum cholesterol and leptin were also elevated (P < 0.001) in the obese animals. These data suggest that Lep(db) obese mice fed a high cholesterol diet have increased gallbladder volume and decreased biliary cholesterol saturation and crystal formation despite elevated serum cholesterol compared with lean control mice. We conclude that the link among obesity, diet, and gallstone formation may not require hypersecretion of biliary cholesterol and may be related to the effects of diabetes, hyperlipidemia, or both on gallbladder motility.

Leptin-resistant obese mice do not form biliary crystals on a high cholesterol diet

Introduction: Human obesity is associated with leptin resistance, elevated serum lipids, hepatic steatosis, and cholesterol gallstone formation. We have previously demonstrated that leptin-resistant (Lepdb) obese mice fed a low cholesterol diet have enlarged gallbladders, but a decreased cholesterol saturation index, despite marked hepatic steatosis and elevated serum cholesterol. However, obese humans typically consume a high cholesterol diet and are prone to form gallstones. Therefore, we tested the hypothesis that on a high cholesterol diet, leptin-resistant obese mice would have large gallbladders, cholesterol saturated bile, and would readily form biliary crystals. Methods: Eight week old female lean control (C57BL/6J, n = 70) and leptin-resistant (Lepdb, n = 72) mice were fed a 1% cholesterol diet for four weeks. At 12 weeks, all animals were fasted overnight and underwent cholecystectomies. Gallbladder volume (μl) was measured and grouped into 7 lean control and 12 Lepdb pools for determination of cholesterol saturation index (CSI). Bile was examined for cholesterol crystals under polarized light microscopy (#/hpf). Serum cholesterol (mg/dl) and leptin levels (ng/ml) also were measured. Results were analyzed using the Student’s t-test. TABLE—ABSTRACT P57GB volCSICrystalsSerum XOLLeptinLean19.1 ± 0.91.15 ± .102.2 ± 0.5131 ± 76 ± 0Lepdb35.8 ± 2.2∗0.91 ± .10†0.0 ± 0.0∗278 ± 10∗229 ± 8∗∗P < 0.001.†P < 0.03 vs C57b lean controls.Conclusions: These data suggest that leptin-resistant obese mice fed a high cholesterol diet have 1) increased gallbladder volume, 2) decreased biliary cholesterol saturation and crystal formation despite 3) elevated serum cholesterol compared to lean control mice. Therefore, we conclude that the link among obesity, diet, and gallstone formation does not require hypersecretion of biliary cholesterol and may be related to gallbladder stasis.