The deletion of the estrogen receptor α gene reduces susceptibility to estrogen-induced cholesterol cholelithiasis in female mice

Global, regional, and national burden of gallbladder and biliary diseases from 1990 to 2019

BACKGROUND

Gallbladder and biliary diseases (GABDs) are a major public health issue.

AIM

To analysis the cause-specific incidence, prevalence, and years lived with disability (YLDs) and its temporal trends of GABDs at the global, regional, and national level. Data on GABD were available from the Global Burden of Disease study 2019.

METHODS

The estimated annual percentage change (EAPC) was used to quantify temporal trend in GABD age-standardized incidence rates (ASIRs), age-standardized prevalence rate (ASPR), and age-standardized YLD rate (ASYR) by region, sex. We analyzed the relationship between the GABD burden and country development level using the human development index (HDI).

RESULTS

In 2019, the incident cases of GABD were 52003772, with an ASIR of 63432/100000 population. Globally, the number of incident cases and ASIR of GABD increased 97% and 58.9% between 1990 and 2019. Although, the ASPR and ASYR decreased from 1990 to 2019, the number of prevalent and YLDs cases increased. The highest ASIR was observed in Italy, and the highest ASPR and ASYR was observed in United Kingdom. The highest burden of GABD was found in low-SDI region, and the burden in female was significantly higher than males. A generally negative correlation (ρ = -0.24, P < 0.05) of GABD with the EAPC and human development index (HDI) (in 2021) were observed for ASIR. What's more, no correlation in ASPR (ρ = -0.06, P = 0.39) and ASYR (ρ = -0.07, P = 0.36) of GABD with the EAPC and HDI (in 2021) were observed, respectively.

CONCLUSION

GABD remain a major global public health challenge; however, the burden of GABD varies geographically. Globally, the number of incident cases and ASIR of GABD increased between 1990 and 2019. The results of our study provide insight into the global disease burden of GABD and may assist policymakers in formulating effective policies to mitigate modifiable risk factors.

Activation of Estrogen Receptor G Protein-Coupled Receptor 30 Enhances Cholesterol Cholelithogenesis in Female Mice

BACKGROUND AND AIMS

Estrogen is an important risk factor for cholesterol gallstone disease because women are twice as likely as men to form gallstones. The classical estrogen receptor α (ERα), but not ERβ, in the liver plays a critical role in the formation of estrogen-induced gallstones in female mice. The molecular mechanisms underlying the lithogenic effect of estrogen on gallstone formation have become more complicated with the identification of G protein-coupled receptor 30 (GPR30), an estrogen receptor.

APPROACH AND RESULTS

We investigated the biliary and gallstone phenotypes in ovariectomized female GPR30^-/- , ERα^-/- , and wild-type mice injected intramuscularly with the potent GPR30-selective agonist G-1 at 0 or 1 μg/day and fed a lithogenic diet for 8 weeks. The activation of GPR30 by G-1 enhanced cholelithogenesis by suppressing expression of cholesterol 7α-hydroxylase, the rate-limiting enzyme for the classical pathway of bile salt synthesis. These metabolic abnormalities led to an increase in biliary cholesterol concentrations in company with hepatic hyposecretion of biliary bile salts, thereby inducing cholesterol-supersaturated gallbladder bile and accelerating cholesterol crystallization. G-1 also impairs gallbladder emptying, leading to sluggish gallbladder motility and promoting the development of biliary sludge in the early stage of gallstone formation. The prevalence rates of gallstones were 80% in wild-type and ERα^-/- mice treated with G-1 compared to 10% in wild-type mice receiving no G-1. However, no gallstones were formed in GPR30^-/- mice treated with G-1.

CONCLUSIONS

GPR30 produces additional lithogenic actions, working independently of ERα, to increase susceptible to gallstone formation in female mice; both GPR30 and ERα are potential therapeutic targets for cholesterol gallstone disease, particularly in women and patients exposed to high levels of estrogen.

A novel GPER antagonist protects against the formation of estrogen-induced cholesterol gallstones in female mice

Many clinical studies and epidemiological investigations have clearly demonstrated that women are twice as likely to develop cholesterol gallstones as men, and oral contraceptives and other estrogen therapies dramatically increase that risk. Further, animal studies have revealed that estrogen promotes cholesterol gallstone formation through the estrogen receptor (ER) α, but not ERβ, pathway. More importantly, some genetic and pathophysiological studies have found that G protein-coupled estrogen receptor (GPER) 1 is a new gallstone gene, Lith18, on chromosome 5 in mice and produces additional lithogenic actions, working independently of ERα, to markedly increase cholelithogenesis in female mice. Based on computational modeling of GPER, a novel series of GPER-selective antagonists were designed, synthesized, and subsequently assessed for their therapeutic effects via calcium mobilization, cAMP, and ERα and ERβ fluorescence polarization binding assays. From this series of compounds, one new compound, 2-cyclohexyl-4-isopropyl-N-(4-methoxybenzyl)aniline (CIMBA), exhibits superior antagonism and selectivity exclusively for GPER. Furthermore, CIMBA reduces the formation of 17β-estradiol-induced gallstones in a dose-dependent manner in ovariectomized mice fed a lithogenic diet for 8 weeks. At 32 μg/day/kg CIMBA, no gallstones are found, even in ovariectomized ERα (-/-) mice treated with 6 μg/day 17β-estradiol and fed the lithogenic diet for 8 weeks. In conclusion, CIMBA treatment protects against the formation of estrogen-induced cholesterol gallstones by inhibiting the GPER signaling pathway in female mice. CIMBA may thus be a new agent for effectively treating cholesterol gallstone disease in women.

G Protein-Coupled Estrogen Receptor, GPER1, Offers a Novel Target for the Treatment of Digestive Diseases

There are gender differences between men and women in many physiological functions and diseases, which indicates that female sex hormones may be important. Traditionally, estrogen exerts its biological activities by activating two classical nuclear estrogen receptors, ESR1 and ESR2. However, the roles of estrogen in the regulation of physiological functions and the pathogenesis of diseases become more complicated with the identification of the G protein-coupled estrogen receptor (GPER1). Although many GPER1-specific ligands have been developed, the therapeutic mechanisms of exclusively targeting GPER1 are not yet well understood. Translational applications and clinical trial efforts for the identified GPER1 ligands have been focused primarily on the reproductive, cardiovascular, nervous, endocrine, and immune systems. More recently, research found that GPER1 may play an important role in regulating the digestive system. Cholesterol gallstone disease, a major biliary disease, has a higher prevalence in women than in men worldwide. Emerging evidence implies that GPER1 could play an important role, independent of the classical ESR1, in the pathophysiology of cholesterol gallstones in women. This review discusses the complex signaling pathways of three estrogen receptors, highlights the development of GPER1-specific ligands, and summarizes the latest advances in the role of GPER1 in the pathogenesis of gallstone formation.

The Hepatobiliary System: An Overview of Normal Function and Diagnostic Testing in Pregnancy

Pregnancy is associated with physiological adaptions that affect every organ system. Changes in liver function in pregnancy have important effects on nutrient metabolism, protein synthesis, and the biotransformation of substances in preparation for excretion. A clear understanding of the anatomic and functional changes of the hepatobiliary system is necessary for the diagnosis and evaluation of disease, as well as understanding how these changes predispose women to pregnancy-specific hepatic conditions. In this review, the effect of gestational changes in hepatobiliary function on laboratory tests and the role of diagnostic imaging of the liver and gallbladder in pregnancy will be discussed.

Mouse models of gallstone disease

PURPOSE OF REVIEW

The establishment of mouse models of gallstones, and the contribution of mouse models to genetic studies of gallstone disease, as well as the latest advances in the pathophysiology of gallstones from mouse experiments are summarized.

RECENT FINDINGS

The combined uses of genomic strategies and phenotypic studies in mice have successfully led to the identification of many Lith genes, which pave the way for the discovery of human LITH genes. The physical-chemical, genetic, and molecular biological studies of gallstone disease in mice with knockout or transgene of specific target genes have provided many novel insights into the complex pathophysiological mechanisms of this very common hepatobiliary disease worldwide, showing that interactions of five primary defects play a critical role in the pathogenesis of cholesterol gallstones. Based on mouse studies, a new concept has been proposed that hepatic hypersecretion of biliary cholesterol is induced by multiple Lith genes, with insulin resistance as part of the metabolic syndrome interacting with cholelithogenic environmental factors to cause the phenotype.

SUMMARY

The mouse model of gallstones is crucial for elucidating the physical-chemical and genetic mechanisms of cholesterol crystallization and gallstone formation, which greatly increase our understanding of the pathogenesis of this disease in humans.

Helicobacter pylori and 17β-estradiol induce human intrahepatic biliary epithelial cell abnormal proliferation and oxidative DNA damage

BACKGROUND

Biliary cancers are more common in females, and previous studies have suggested that Helicobacter pylori (H. pylori) exists in the biliary system. However, the effects of H. pylori infection and estrogen on the biological behaviors of human biliary epithelium mucosa remain unknown. The present study aimed to clarify their effects on the proliferation, apoptosis, migration and oxidative DNA damage of a human intrahepatic biliary epithelial cell (HIBEC) line in vitro.

METHODS

HIBECs were co-cultured with 17β-estradiol (at 10^-9 mol/L, 10^-7 mol/L, and 10^-5 mol/L) and H. pylori (at MOI=0.5:1, 1:1, and 2:1) and continuously passaged until the 15th generation (approximately 45 days). Then, the following assays were performed. HIBEC proliferation was measured using the CCK-8 assay, plate clone-formation assay and by determining Ki-67 expression with immunocytochemistry; cell apoptosis and migration were investigated using Annexin-V/PI and transwell assays, respectively; and reactive oxygen species (ROS) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) production were detected by flow cytometry and immunofluorescence staining combined with confocal laser scanning microscopy, respectively. The results were the basis for evaluating the level of oxidative stress and the related DNA damage in HIBECs.

RESULTS

HIBECs maintained a normal morphology and vitality when treated with 17β-estradiol (at 10^-9 mol/L) and H. pylori (at MOI=0.5:1 and 1:1). 17β-estradiol at 10^-7 mol/L and 10^-5 mol/L and H. pylori at MOI=2:1, by contrast, caused cell death. Compared with controls, HIBECs treated with 17β-estradiol (10^-9 mol/L) and H. pylori (MOI=1:1) had a higher up-regulation of proliferation, Ki-67 expression, clone formation, migration activity and the expression of ROS and 8-OHdG and exhibited a down-regulation of apoptosis. The above effects were further increased when 17β-estradiol and H. pylori were combined (P<0.05).

CONCLUSIONS

H. pylori and 17β-estradiol, separately or in combination, promoted cell proliferation and suppressed apoptosis of HIBECs in vitro. The above phenomena might be related to oxidative stress and its subsequent DNA damage with H. pylori and 17β-estradiol.

Is the oral contraceptive or hormone replacement therapy a risk factor for cholelithiasis: A systematic review and meta-analysis

BACKGROUND

Association between exogenous estrogen intake and cholelithiasis risk has been reported in several epidemiological studies, including oral contraceptive (OC) and hormone replacement therapy (HRT), while the results were controversial. This study aimed to perform a comprehensive meta-analysis of this issue.

METHODS

PUBMED, EMBASE, and Cochrane library database were searched up to October 2016. Two reviewers independently extracted data from eligible studies, relative risks (RRs), and/or odds ratios (ORs) with 95% confidence intervals (95% CIs) for the highest versus lowest categories of intake were adopted. Either a fixed- or a random-effects model was adopted to estimate overall RRs or ORs. Besides, subgroup and publication bias analyses were applied to explain the heterogeneity. An original study was also conducted to verify our conclusion.

RESULTS

A total of 19 studies with approximately 556,620 participants were included in this meta-analysis. The pooled RR of cholelithiasis for the highest versus the lowest categories was 1.59 (95% CI: 1.44-1.75), indicating that exogenous estrogen was positive associated with the intake of exogenous estrogen. However, the pooled RR of OC intake and cholelithiasis risk was 1.19 (95% CI: 0.97-1.45), and the RR for HRT was 1.79 (95% CI: 1.61-2.00).

CONCLUSION

The HRT was positively associated with the cholelithiasis risk, and the OC will not increase the risk of cholelithiasis.

Lack of endogenous cholecystokinin promotes cholelithogenesis in mice

BACKGROUND

Celiac disease is an autoimmune enteropathy caused by a permanent intolerance to dietary gluten in genetically predisposed individuals. Cholecystokinin (CCK) release from the proximal small intestine and gallbladder emptying in response to a fatty meal are greatly reduced in celiac patients before they start the gluten-free diet, showing a genetic predisposition to gallstones.

METHODS

To elucidate the complex pathophysiological mechanisms determining the biliary characteristic of celiac disease, we investigated the effect of the absence of endogenous CCK on cholesterol crystallization and gallstone formation in mice fed a lithogenic diet for 28 days.

KEY RESULTS

Fasting gallbladder volumes were increased and the response of gallbladder emptying to the high-fat diet was impaired in CCK knockout (KO) mice compared to wild-type mice. Because of the absence of CCK, small intestinal transit time was prolonged and intestinal cholesterol absorption was increased. During 28 days of feeding, elevated biliary cholesterol concentrations and gallbladder stasis promoted the growth and agglomeration of solid cholesterol crystals into microlithiasis and stones. Thus, cholesterol crystallization and gallstone formation were accelerated in CCK KO mice. In contrast, daily intraperitoneal administration of CCK-8 reduced gallstone formation in CCK KO mice even on the lithogenic diet.

CONCLUSIONS & INFERENCES

The lack of endogenous CCK enhances susceptibility to gallstones by impairing gallbladder contractile function and small intestinal motility function. These findings show that celiac disease is an important risk factor for gallstone formation and the gallbladder motility function should be routinely examined by ultrasonography and gallbladder stasis should be prevented in celiac patients.

The cholecystokinin-1 receptor antagonist devazepide increases cholesterol cholelithogenesis in mice

BACKGROUND

A defect in gallbladder contraction function plays a key role in the pathogenesis of gallstones. The cholecystokinin-1 receptor (CCK-1R) antagonists have been extensively investigated for their therapeutic effects on gastrointestinal and metabolic diseases in animal studies and clinical trials. However, it is still unknown whether they have a potential effect on gallstone formation.

DESIGN

To study whether the CCK-1R antagonists enhance cholelithogenesis, we investigated cholesterol crystallization, gallstone formation, hepatic lipid secretion, gallbladder emptying function and intestinal cholesterol absorption in male C57BL/6J mice treated by gavage with devazepide (4 mg/day/kg) or vehicle (as controls) twice per day and fed the lithogenic diet for 21 days.

RESULTS

During 21 days of feeding, oral administration of devazepide significantly accelerated cholesterol crystallization and crystal growth to microlithiasis, with 40% of mice forming gallstones, whereas only agglomerated cholesterol monohydrate crystals were found in mice receiving vehicle. Compared to the vehicle group, fasting and postprandial residual gallbladder volumes in response to the high-fat meal were significantly larger in the devazepide group during cholelithogenesis, showing reduced gallbladder emptying and bile stasis. Moreover, devazepide significantly increased hepatic secretion of biliary cholesterol, but not phospholipids or bile salts. The percentage of intestinal cholesterol absorption was higher in devazepide-treated mice, increasing the bioavailability of chylomicron-derived cholesterol in the liver for biliary hypersecretion into bile. These abnormalities induced supersaturated bile and rapid cholesterol crystallization.

CONCLUSIONS

The potent CCK-1R antagonist devazepide increases susceptibility to gallstone formation by impairing gallbladder emptying function, disrupting biliary cholesterol metabolism and enhancing intestinal cholesterol absorption in mice.