Exploration of molecular interactions between scoparone and associated compounds with Constitutive androstane receptor (CAR) leading to gallstone prevention: an in silico investigation

Scoparone (6, 7 dimethylesculetin) is a biologically active compound derived from the herb Artemisia capillaris having anti-inflammatory, anti-lipemic, and anti-allergic roles. Activation of the constitutive androstane receptor (CAR) in primary hepatocytes of both wild-type and humanized CAR mice by scoparone, accelerates bilirubin and cholesterol clearance in vivo. This can prevent gallstones which is a dreaded gastrointestinal disease. To date, surgery is regarded as the gold standard for treating gallstones. The molecular interactions between scoparone and CAR leading to gallstone prevention are not yet explored. In this study, we have analyzed these interactions through an insilico approach. After extracting the CAR structures (mice and human) from the protein databank and 6, 7-dimethylesuletin from PubChem, energy minimization of both the receptors was done to make them stable followed by docking. Next, a simulation was performed to stabilize the docked complexes. Through docking, H-bonds and pi-pi interactions were found in the complexes, which imply a stable interaction, thus activating the CAR. A similarity search for scoparone was performed and the selected compounds were docked with the CAR receptors. Esculentin acetate and scopoletin acetate interacted with human CAR through pi-alkyl and H-bond respectively. While Fraxidin methyl ether, fraxinol methyl ether, and 6, 7 diethoxycoumarin interacted with mice CAR through H-bond and Pi-Pi T-shaped bonds. The selected complexes were simulated further. Our results are in accordance with the hypothesis in the literature. We have also analyzed the drug likeliness, absorption, non-carcinogenicity, and other properties of scoparone which can support further in vivo studies.Communicated by Ramaswamy H. Sarma.

FXR Signaling-Mediated Bile Acid Metabolism Is Critical for Alleviation of Cholesterol Gallstones by Lactobacillus Strains

Cholesterol gallstone (CGS) disease is characterized by an imbalance in bile acid (BA) metabolism and is closely associated with gut microbiota disorders. However, the role and mechanism by which probiotics targeting the gut microbiota attenuate cholesterol gallstones are still unknown. In this study, Limosilactobacillus reuteri strain CGMCC 17942 and Lactiplantibacillus plantarum strain CGMCC 14407 were individually administered to lithogenic-diet (LD)-fed mice for 8 weeks. Both Lactobacillus strains significantly reduced LD-induced gallstones, hepatic steatosis, and hyperlipidemia. These strains modulated BA profiles in the serum and liver, which may be responsible for the activation of farnesoid X receptor (FXR). At the molecular level, L. reuteri and L. plantarum increased ileal fibroblast growth factor 15 (FGF15) and hepatic fibroblast growth factor receptor 4 (FGFR4) and small heterodimer partner (SHP). Subsequently, hepatic cholesterol 7α-hydroxylase (CYP7A1) and oxysterol 7α-hydroxylase (CYP7B1) were inhibited. Moreover, the two strains enhanced BA transport by increasing the levels of hepatic multidrug resistance-associated protein homologs 3 and 4 (Mrp3/4), hepatic multidrug resistance protein 2 (Mdr2), and the bile salt export pump (BSEP). In addition, both L. reuteri and L. plantarum reduced LD-associated gut microbiota dysbiosis. L. reuteri increased the relative abundance of Muribaculaceae, while L. plantarum increased that of Akkermansia. The changed gut microbiota was significantly negatively correlated with the incidence of cholesterol gallstones and the FXR-antagonistic BAs in the liver and serum and with the FXR signaling pathways. Furthermore, the protective effects of the two strains were abolished by both global and intestine-specific FXR antagonists. These findings suggest that Lactobacillus might relieve CGS through the FXR signaling pathways.

IMPORTANCE Cholesterol gallstone (CGS) disease is prevalent worldwide. None of the medical options for prevention and treatment of CGS disease are recommended, and surgical management has a high rate of recurrence. It has been reported that the factors involved in metabolic syndrome are highly connected with CGS formation. While remodeling of dysbiosis of the gut microbiome during improvement of metabolic syndrome has been well studied, less is known about prevention of CGS formation after regulating the gut microbiome. We used the lithogenic diet (LD) to induce an experimental CGS model in C57BL/6J mice to investigate protection against CGS formation by Limosilactobacillus reuteri strain CGMCC 17942 and Lactiplantibacillus plantarum strain CGMCC 14407. We found that these L. reuteri and L. plantarum strains altered the bile acid composition in mice and improved the dysbiosis of the gut microbiome. These two Lactobacillus strains prevented CGS formation by fully activating the hepatic and ileal FXR signaling pathways. They could be a promising therapeutic strategy for treating CGS or preventing its recurrence.

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

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

Symptomatic gallstones and HIV in black South African women: Changing trends of gallstone disease?

BACKGROUND

The incidence of metabolic disorders in human immunodeficiency virus (HIV) endemic settings is a prevailing burden in developing countries. Cholesterol homeostasis and fat metabolism are altered by HIV and antiretroviral therapy (ART), thereby possibly contributing to complications such as gallstone formation.

OBJECTIVES

The aim of this study was to evaluate established risk factors for the formation of cholesterol gallstones in black South African women living with HIV (WLHIV).

METHOD

A case series study was conducted of all black South African women undergoing cholecystectomy for gallstone disease over a 1-year period at King Edward VIII Hospital, Durban, South Africa. Age, body mass index (BMI), family history of gallstones, oestrogen exposure and lipograms were compared between WLHIV and uninfected women. Categorical variables were tested using either the Fisher's exact test or Pearson's chi-square test. Means were compared using independent t-tests. For non-normally distributed data, the Mann-Whitney U test was used. Statistical tests were two-sided, and p-values of less than 0.05 were considered statistically significant.

RESULTS

A total of 52 patients were assessed, 34 HIV-uninfected and 18 WLHIV. The median age of WLHIV versus the uninfected women was 35 and 50 years, respectively, (p = 0.015). A statistically significant number of uninfected women were in the overweight/obese category (BMI > 25 kg/m2) compared to the normal weight category (BMI < 25 kg/m2) (p < 0.001). The number of obese WLHIV did not reach statistical significance.

CONCLUSION

The age of occurrence of gallstone disease amongst black South African WLHIV was significantly lower and fewer women were obese compared with the uninfected women with gallstone disease. These findings differ from known gallstone risk factors in other populations and in uninfected black South African women. This could be attributed to the metabolic alterations caused by HIV infection itself and/or to the long-term use of ART. Larger cohort studies are required to elucidate the role of HIV and ART in cholestatic disease.

Curcumin inhibits the proteolytic process of SREBP-2 by first inhibiting the expression of S1P rather than directly inhibiting SREBP-2 expression

Many studies have demonstrated that curcumin can downregulate mRNA levels of sterol regulatory element-binding proteins (SREBP-2); however, our study did not find similar results. This study was designed to demonstrate that curcumin inhibits the proteolytic process of SREBP-2 by first inhibiting the expression of membrane-bound transcription factor site-1 protease (S1P) rather than directly inhibiting SREBP-2 expression. After curcumin treatment, Caco-2 cells were collected to observe the dose- and time-dependent dynamics of precursor and mature SREBP-2, transcription factor-specific protein 1 (SP-1), and SREBP cleavage-activating protein (SCAP). After curcumin treatment, SREBP-2 distribution was detected in the cells and S1P protein expression was examined. Curcumin could downregulate mRNA levels of SREBP2, SP-1 and SCAP, but it did not simultaneously downregulate the expression of precursor SREBP-2 (pSREBP-2) and SCAP. Curcumin can inhibit the proteolytic process of SREBP-2, reduce the production of mature SREBP-2 (mSREBP-2), and change the cellular distribution of SREBP-2. The inhibitory effect of curcumin on SP-1 protein expression is short-acting. Curcumin could downregulate the mRNA and protein expression of S1P, but has no obvious inhibitory effect on the mRNA and protein expression of S2P (site-2 protease). Curcumin can inhibit the SREBP-2 proteolytic process to reduce mSREBP-2 which functions as a transcription factor, affecting the regulation of cholesterol metabolism-related genes. Curcumin does not directly inhibit the expression of mSREBP-2 protein, and it has no such inhibitory effect for at least a short period of time, although curcumin does reduce the amount of mSREBP-2 protein. S1P is a key protease in the hydrolysis of pSREBP-2 into mSREBP-2. Therefore, curcumin may decrease the amount of mSREBP-2 by directly inhibiting the expression of S1P mRNA and protein.

Recent advances in understanding and managing cholesterol gallstones

The high prevalence of cholesterol gallstones, the availability of new information about pathogenesis, and the relevant health costs due to the management of cholelithiasis in both children and adults contribute to a growing interest in this disease. From an epidemiologic point of view, the risk of gallstones has been associated with higher risk of incident ischemic heart disease, total mortality, and disease-specific mortality (including cancer) independently from the presence of traditional risk factors such as body weight, lifestyle, diabetes, and dyslipidemia. This evidence points to the existence of complex pathogenic pathways linking the occurrence of gallstones to altered systemic homeostasis involving multiple organs and dynamics. In fact, the formation of gallstones is secondary to local factors strictly dependent on the gallbladder (that is, impaired smooth muscle function, wall inflammation, and intraluminal mucin accumulation) and bile (that is, supersaturation in cholesterol and precipitation of solid crystals) but also to "extra-gallbladder" features such as gene polymorphism, epigenetic factors, expression and activity of nuclear receptors, hormonal factors (in particular, insulin resistance), multi-level alterations in cholesterol metabolism, altered intestinal motility, and variations in gut microbiota. Of note, the majority of these factors are potentially manageable. Thus, cholelithiasis appears as the expression of systemic unbalances that, besides the classic therapeutic approaches to patients with clinical evidence of symptomatic disease or complications (surgery and, in a small subgroup of subjects, oral litholysis with bile acids), could be managed with tools oriented to primary prevention (changes in diet and lifestyle and pharmacologic prevention in subgroups at high risk), and there could be relevant implications in reducing both prevalence and health costs.

Clinical Application of Dual-Energy Spectral Computed Tomography in Detecting Cholesterol Gallstones From Surrounding Bile

RATIONALE AND OBJECTIVE

This study aimed to investigate the clinical value of spectral computed tomography (CT) in the detection of cholesterol gallstones from surrounding bile.

MATERIALS AND METHODS

This study was approved by the institutional review board. The unenhanced spectral CT data of 24 patients who had surgically confirmed cholesterol gallstones were analyzed. Lipid concentrations and CT numbers were measured from fat-based material decomposition image and virtual monochromatic image sets (40-140 keV), respectively. The difference in lipid concentration and CT number between cholesterol gallstones and the surrounding bile were statistically analyzed. Receiver operating characteristic analysis was applied to determine the diagnostic accuracy of using lipid concentration to differentiate cholesterol gallstones from bile.

RESULTS

Cholesterol gallstones were bright on fat-based material decomposition images yielding a 92% detection rate (22 of 24). The lipid concentrations (552.65 ± 262.36 mg/mL), CT number at 40 keV (-31.57 ± 16.88 HU) and 140 keV (24.30 ± 5.85 HU) for the cholesterol gallstones were significantly different from those of bile (-13.94 ± 105.12 mg/mL, 12.99 ± 9.39 HU and 6.19 ± 4.97 HU, respectively). Using 182.59 mg/mL as the threshold value for lipid concentration, one could obtain sensitivity of 95.5% and specificity of 100% with accuracy of 0.994 for differentiating cholesterol gallstones from bile.

CONCLUSIONS

Virtual monochromatic spectral CT images at 40 keV and 140 keV provide significant CT number differences between cholesterol gallstones and the surrounding bile. Spectral CT provides an excellent detection rate for cholesterol gallstones.

Potentiation of anti-cholelithogenic influence of dietary tender cluster beans (Cyamopsis tetragonoloba) by garlic (Allium sativum) in experimental mice

BACKGROUND & OBJECTIVES

Dietary fibre-rich tender cluster beans (Cyamopsis tetragonoloba; CB) are known to exert beneficial cholesterol lowering influence. We examined the influence of a combination of dietary tender CB and garlic (Allium sativum) in reducing the cholesterol gallstone formation in mice.

METHODS

Cholesterol gallstones were induced in Swiss mice by feeding a high-cholesterol diet (HCD) for 10 wk. Dietary interventions were made with 10 per cent CB and 1 per cent garlic included individually or together along with HCD. A total of 100 mice were divided into five groups of 20 mice each.

RESULTS

Dietary CB, garlic and CB+garlic reduced the formation of cholesterol gallstones by 44, 25 and 56 per cent, respectively, lowered cholesterol by 23-48, 16-24, and 24-58 in bile, serum, and liver, respectively. Cholesterol saturation index in bile and cholesterol: phospholipid ratio in circulation and hepatic tissue were significantly lowered by these dietary interventions, with highest beneficial effect from CB+garlic. Activities of hepatic cholesterol metabolizing enzymes were modulated by CB, garlic and CB+garlic. Elevation in lipid peroxides caused by HCD was also countered by these dietary interventions, the combination producing the highest effect.

INTERPRETATION & CONCLUSIONS

The results showed that the prevention of experimentally induced formation of cholesterol gallstones by dietary CB and garlic was due to decreased biliary cholesterol secretion and increased cholesterol saturation index. In addition of anti-lithogenic effect, dietary CB and garlic in combination had a beneficial antioxidant effect.

Castanea sativa Mill. extract contracts gallbladder and relaxes sphincter of Oddi in guinea pig: a natural approach to biliary tract motility disorders

Impaired gallbladder motility is a contributing factor to gallstone formation. Since many drugs delaying intestinal motility inhibit gallbladder emptying, the aim of the present study was to evaluate the effect on gallbladder and sphincter of Oddi motility of a Natural Chestnut Wood Extract (NEC) that reduces intestinal motility. In order to evaluate the effect of the extract in normal- and high-risk gallstone conditions, the investigation was performed using tissues from animals fed normal and lithogenic diet. Fifty guinea pigs were administered either control or lithogenic diet. The spontaneous motility of the gallbladder and sphincter of Oddi were recorded on isolated gallbladder tissues; thereafter, the effect of NEC on motility was tested and compared with carbachol (CCh), potassium chloride (KCl), noradrenaline (NA), and A71623. Compared to controls, the lithogenic diet induced an irregular and disordered motor pattern in both the gallbladder and sphincter of Oddi. NEC increased gallbladder and decreased sphincter of Oddi spontaneous motility independently of cholinergic, adrenergic, and CCK-1 receptor-mediated pathways both in controls and in lithogenic diet-fed animals, although the effect was lower in the latter group. The effect was reversible and mediated by calcium channels. The natural extract of chestnut increasing gallbladder contraction and inducing the relaxation of the sphincter of Oddi can be of benefit in pathological conditions associated with increased transit time at risk of gallstones.

Ursodeoxycholic acid lowers bile lithogenicity by regulating SCP2 expression in rabbit cholesterol gallstone models

Aims: We designed this study to get insight into the disorder of lipid metabolism during cholesterol gallstone formation and evaluate the effect of ursodeoxycholic acid on the improvement of bile lithogenicity and on expression of lipid related genes.

Methods: Rabbit cholesterol gallstone models were induced by high cholesterol diet. Bile, blood and liver tissues were obtained from rabbits after 0, 1, 2, 3, 4 and 5 weeks. Bile and blood lipids were measured enzymatically. 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), cytochrome P450, family 7, subfamily A, polypeptide 1 (CYP7A1) and sterol carrier protein 2 (SCP2) mRNA expressions were detected by using quantitative real-time RT-PCR. Cholesterol saturation index (CSI) was calculated by using Carey table to represent the bile lithogenicity.

Results: Rates of gallstone formation of the 4 and 5 week treatment groups were 100 %, but that of the ursodeoxycholic acid treatment group was only 33.3 %. Expression of HMGCR and SCP2 mRNA in the 4 week group was upregulated and that of CYP7A1 mRNA decreased as compared with the 0 week group. Ursodeoxycholic acid could significantly extend nucleation time of bile and lower CSI. Ursodeoxycholic acid could reduce the expression of SCP2, but couldn't influence expression of HMGCR and CYP7A1.

Conclusions: Abnormal expression of HMGCR, CYP7A1 and SCP2 might lead to high lithogenicity of bile. Ursodeoxycholic acid could improve bile lipids and lower bile lithogenicity, thereby reducing the incidence of gallstones. So it might be a good preventive drug for cholesterol gallstones.

Dissecting the role of insulin resistance in the metabolic syndrome

PURPOSE OF REVIEW

Over 20 years ago, insulin resistance was postulated to play a central role in the pathogenesis of the metabolic syndrome. However, this has been difficult to prove, leading to a great deal of controversy within the field. Recent studies on mice and humans with genetic defects in insulin signaling have allowed us, for the first time, to dissect which features of the metabolic syndrome can be caused by insulin resistance.

RECENT FINDINGS

Liver insulin receptor knockout mice show that hepatic insulin resistance can produce hyperglycemia, increased apolipoprotein B secretion and atherosclerosis, and increased biliary cholesterol secretion and cholesterol gallstones. Many of these changes may be due to disinhibition of the transcription factor, forkhead box O1. Yet, neither liver insulin receptor knockout mice nor humans with insulin receptor mutations develop the hypertriglyceridemia or hepatic steatosis associated with the metabolic syndrome.

SUMMARY

These data point to a central role for insulin resistance in the pathogenesis of the metabolic syndrome, as hyperglycemia, atherosclerosis, and cholesterol gallstones can all be caused by insulin resistance. However, hypertriglyceridemia and hepatic steatosis are not due directly to insulin resistance and should be considered pathogenically distinct features of the metabolic syndrome.