Atorvastatin induces bile acid-synthetic enzyme Cyp7a1 by suppressing FXR signaling in both liver and intestine in mice

Sanye tablet regulates gut microbiota and bile acid metabolism to attenuate hepatic steatosis

ETHNOPHARMACOLOGICAL RELEVANCE

Sanye Tablet (SYT), a patent traditional Chinese prescription, is commonly used in treating type 2 diabetes mellitus and hyperlipidemia. Both clinical and animal studies suggest that SYT effectively regulates lipid metabolism. However, its mode of action on hepatic steatosis has yet to be fully elucidated.

AIM OF STUDY

This study investigates the lipid-regulating effects and underlying mechanism of SYT in high-fat diet (HFD)-induced hepatic steatosis mice.

MATERIAL AND METHODS

The inhibitory effects of SYT on developing hepatic steatosis were investigated in HFD-fed C57BL/6N mice. Biochemical markers, including total cholesterol (TC) and triglycerides (TG), were measured using specific kits. Hepatic histological alterations were determined by Hematoxylin and Eosin (H&E) and Oil Red O staining. Hepatic, fecal, and systemic bile acids (BAs) profiles were detected by UPLC-MS. mRNA and protein levels of BAs synthesis-related enzymes and critical nodes of farnesoid X receptor (FXR)/fibroblast growth factor 15 (FGF15)/fibroblast growth factor receptor 4 (FGFR4) signaling were detected. Fecal microbial composition was analyzed by 16S rRNA gene sequencing and the antimicrobial activity of SYT was further evaluated in vitro.

RESULTS

SYT alleviated HFD-induced hepatic steatosis by decreasing TG and TC levels, relieving hepatocyte ballooning, and promoting hepatic BAs synthesis. Moreover, SYT significantly increased the levels of taurine-conjugated BAs in the liver and feces, which in turn inhibited the FXR/FGF15/FGFR4 signaling. Consequently, the hepatic BAs synthesis-related enzyme expression was promoted to reduce lipid accumulation. Notably, SYT remodeled the gut microbiota composition of HFD-fed mice, especially inhibiting the growth of bile salt hydrolase (BSH)-producing bacteria, such as Lactobacillus murinus, Lactobacillus johnsonii, and Enterococcus faecalis.

CONCLUSION

The findings illustrated that SYT prevented hepatic steatosis by improving hepatic lipid accumulation, which is reflected in modulating the gut-liver axis. SYT corrects BAs profile, restores perturbed FXR/FGF15/FGFR4 signaling and promotes hepatic BAs synthesis, which is associated with modulation on certain BSH-producing bacteria.

Personalized statin therapy: Targeting metabolic processes to modulate the therapeutic and adverse effects of statins

Statins are widely used for treating lipid disorders and cardiovascular diseases. However, the therapeutic efficiency and adverse effects of statins vary among different patients, which numerous clinical and epidemiological studies have attributed to genetic polymorphisms in statin-metabolizing enzymes and transport proteins. The metabolic processes of statins are relatively complex, involving spontaneous or enzyme-catalyzed interconversion between more toxic lactone metabolites and active acid forms in the liver and bloodstream, influenced by multiple factors, including the expression levels of many metabolic enzymes and transporters. Addressing the variable statin therapeutic outcomes is a pressing clinical challenge. Transcription factors and epigenetic modifications regulate the metabolic enzymes and transporters involved in statin metabolism and disposition and, therefore, hold promise as 'personalized' targets for achieving optimized statin therapy. In this review, we explore the potential for customizing therapy by targeting the metabolism of statin medications. The biochemical bases of adverse reactions to statin drugs and their correlation with polymorphisms in metabolic enzymes and transporters are summarized. Next, we mainly focus on the regulatory roles of transcription factors and epigenetic modifications in regulating the gene expression of statin biochemical machinery. The recommendations for future therapies are finally proposed by targeting the central regulatory factors of statin metabolism.

Trimethylamine N-oxide in cardiovascular disease: Pathophysiology and the potential role of statins

Cardiovascular diseases are one of the leading causes of mortality and morbidity worldwide, with the total number of cases increasing to 523 million in 2019. Despite the advent of new drugs, cardiovascular mortality has increased at an alarming rate of 53.7 % from 12.1 million deaths in 1990. Recently, the role of gut microbiome metabolites, such as Trimethylamine N-Oxide (TMAO), in the pathogenesis of cardiovascular disease (CVD) has attracted significant attention. The gut microbiome is critical in various physiological processes including metabolism, immune function, and inflammation. Elevated TMAO levels are associated with atherosclerosis, heart failure, arrhythmia, and atrial fibrillation. TMAO accelerates atherosclerosis by promoting vascular inflammation and reducing reverse cholesterol transport, which leads to lipid accumulation and vessel narrowing. Previous research has indicated that a Mediterranean diet rich in fiber and phytochemicals can reduce TMAO levels by limiting precursors and fostering beneficial gut microbiota. Prebiotics and probiotics also decrease TMAO, while drugs such as meldonium, aspirin, and antibiotics have shown promise. However, recent studies have demonstrated major potential for the use of statins in reducing TMAO levels. Statin therapy can significantly reduce TMAO levels independent of their cholesterol-lowering effects. This reduction may involve direct interactions with the gut microbiome, changes in cholesterol metabolism, and changes in bile acid composition. This review aims to comprehensively evaluate the therapeutic potential of statins in reducing TMAO levels to improve CV outcomes.

Intestinal FXR deficiency induces dysregulation of xanthine oxidase and accounts for sex difference in hyperuricemia

Overproduction of uric acid caused by increased expression and/or enhanced activity of xanthine oxidase (XO) is one of the major etiologies of hyperuricemia, which had a significant sex differences. As an important enzyme involved in production of reactive oxygen species and uric acid, activity of XO is highly correlated with hyperuricemia and its complications. However, the mechanisms underlying XO dysregulation remain unclear, and sex difference in the prevalence of hyperuricemia has been well known. To explore the potential role of intestinal farnesoid X receptor (FXR) on XO regulation and production, and the mechanisms of sex differences in this pathological process. Two hundred and sixty-one dyslipidemia participants and intestine-specific FXR-knockout mice were used to study the relationship between the intestinal FXR and the serum uric acid level. Western blotting, quantitative real-time PCR, and dual-luciferase reporter assay, were applied to clarify the regulatory role of FXR deficiency on XO. Special inhibitors, agonists, siRNA, sex hormones were used to investigate the mechanism of sex difference in FXR deficiency induced hyperuricemia in cell and animal model. Serum fibroblast growth factor 19 (FGF19) levels were lower in hyperuricemia patients in a sex difference manner. Increased local TNFα level driven by intestinal FXR deficiency/inhibition induced overexpression and hyperactivity of intestinal XO, leading to elevated intestinal uric acid synthesis, and subsequently resulting in hyperuricemia. We found that estrogens inhibited XO expression and activity, whereas androgens enhanced XO activity, leading to the sex difference in FXR deficiency induced hyperuricemia. Infliximab treatment eliminated the sex difference in uric acid levels in intestinal FXR-knockout mice. This study demonstrated the role of intestinal FXR in the pathogenesis of hyperuricemia, and partially elucidated the mechanisms underlying the sex differences of hyperuricemia.

Modulation of the Serum Metabolome by the Short-Chain Fatty Acid Propionate: Potential Implications for Its Cholesterol-Lowering Effect

(1) Background: Dyslipidemia represents a major risk factor for atherosclerosis-driven cardiovascular disease. Emerging evidence suggests a close relationship between cholesterol metabolism and gut microbiota. Recently, we demonstrated that the short-chain fatty acid (SCFA) propionate (PA) reduces serum cholesterol levels through an immunomodulatory mechanism. Here, we investigated the effects of oral PA supplementation on the human serum metabolome and analyzed changes in the serum metabolome in relation to the cholesterol-lowering properties of PA. (2) Methods: The serum metabolome of patients supplemented with either placebo or propionate orally for 8 weeks was assessed using a combination of flow injection analysis-tandem (FIA-MS/MS) as well as liquid chromatography (LC-MS/MS) and mass spectrometry using a targeted metabolomics kit (MxP®Quant 500 kit: BIOCRATES Life Sciences AG, Innsbruck, Austria). A total of 431 metabolites were employed for further investigation in this study. (3) Results: We observed a significant increase in distinct bile acids (GCDCA: fold change = 1.41, DCA: fold change = 1.39, GUDCA: fold change = 1.51) following PA supplementation over the study period, with the secondary bile acid DCA displaying a significant negative correlation with the serum cholesterol levels. (4) Conclusions: Oral supplementation with PA modulates the serum metabolome with a particular impact on the circulatory bile acid profile. Since cholesterol and bile acid metabolism are interconnected, the elevation of the secondary bile acid DCA may contribute to the cholesterol-lowering effect of PA.

Pharmacological modulation of cholesterol 7α-hydroxylase (CYP7A1) as a therapeutic strategy for hypercholesterolemia

Despite the availability of many therapeutic options, the prevalence of hypercholesterolemia remains high. There exists a significant unmet medical need for novel drugs and/or treatment combinations to effectively combat hypercholesterolemia while minimizing adverse reactions. The modulation of cholesterol 7α-hydroxylase (CYP7A1) expression via perturbation of the farnesoid X receptor (FXR) - dependent pathways, primarily FXR/small heterodimer partner (SHP) and FXR/ fibroblast growth factor (FGF)-19/ fibroblast growth factor receptor (FGFR)-4 pathways, presents as a potential option to lower cholesterol levels. This paper provides a comprehensive review of the important role that CYP7A1 plays in cholesterol homeostasis and how its expression can be exploited to assert differential control of bile acid synthesis and cholesterol metabolism. Additionally, the paper also summarizes the current therapeutic options for hypercholesterolemia, and positions modulators of CYP7A1 expression, namely FGFR4 inhibitors and FXR antagonists, as emerging and distinct pharmacological agents to complement and diversify the treatment regime. Their mechanistic and clinical considerations are also extensively described to interrogate the benefits and risks associated with using FXR-mediating agents, either singularly or in combination with recognised agents such as statins to target hypercholesterolemia.

Unveiling the relationship between gut microbiota and heart failure: Recent understandings and insights

Gut microbiota, which comprises a broad range of bacteria inhabiting the human intestines, plays a crucial role in establishing a mutually beneficial relationship with the host body. Dysbiosis refers to the perturbations in the composition or functioning of the microbial community, which can result in a shift from a balanced microbiota to an impaired state. This alteration has the potential to contribute to the development of chronic systemic inflammation. Heart failure (HF) is a largely prevalent clinical condition that has been demonstrated to have variations in the gut microbiome, indicating a potential active involvement in the pathogenesis and advancement of the disease. The exploration of the complex interplay between the gut microbiome and HF presents a potential avenue for the discovery of innovative biomarkers, preventive measures, and therapeutic targets. This review aims to investigate the impact of gut bacteria on HF.

A gut feeling of statin

Statins, known as HMG-CoA reductase inhibitors, are widely utilized to reduce blood cholesterol levels and possess pleiotropic effects, including the influence on inflammation and macrophage proliferation. Despite their significant impact in diminishing the incidence of cardiovascular events and mortality, individual responses to statin therapy vary considerably. Understanding this variability is essential for optimizing treatment outcomes and minimizing adverse effects. The gut microbiota, a complex ecosystem of microorganisms within the gastrointestinal tract, plays a critical role in human health and disease. Emerging evidence has linked the gut microbiota to drug metabolism and response, with the potential to modulate the efficacy of statin therapy and its side effects. This review provides a comprehensive overview of the interaction between the gut microbiota and statins. It discusses how the gut microbiota can influence the therapeutic effects and side effects of statins and examines the mechanisms by which the gut microbiota affect statin response and cardiovascular diseases.

Regulation of cholesterol metabolism during high fatty acid-induced lipid deposition in calf hepatocytes

Cholesterol in the circulation is partly driven by changes in feed intake, but aspects of cholesterol metabolism during development of fatty liver are not well known. The objective of this study was to investigate mechanisms of cholesterol metabolism in calf hepatocytes challenged with high concentrations of fatty acids (FA). To address mechanistic insights regarding cholesterol metabolism, liver samples were collected from healthy control dairy cows (n = 6; 7-13 d in milk) and cows with fatty liver (n = 6; 7-11 d in milk). In vitro, hepatocytes isolated from 3 healthy female calves (1 d old) were challenged with or without a mix of 1.2 mM FA to induce metabolic stress. In addition, hepatocytes were processed with 10 µmol/L of the cholesterol synthesis inhibitor simvastatin or 6 µmol/L of the cholesterol intracellular transport inhibitor U18666A with or without the 1.2 mM FA mix. To evaluate the role of cholesterol addition, hepatocytes were treated with 0.147 mg/mL methyl-β-cyclodextrin (MβCD + FA) or 0.147 mg/mL MβCD with or without 10 and 100 µmol/L cholesterol before incubation with FA (CHO10 + FA and CHO100 + FA). In vivo data from liver biopsies were analyzed by 2-tailed unpaired Student's t-test. Data from in vitro calf hepatocytes were analyzed by one-way ANOVA. Compared with healthy cows, blood plasma total cholesterol and plasma low-density lipoprotein cholesterol content in cows with fatty liver was markedly lower, whereas the hepatic total cholesterol content did not differ. In contrast, compared with healthy controls, the triacylglycerol content in the liver and the content of FA, β-hydroxybutyrate, and aspartate aminotransferase in the plasma of cows with fatty liver were greater. The results revealed that both fatty liver in vivo and challenge of calf hepatocytes with 1.2 mM FA in vitro led to greater mRNA and protein abundance of sterol regulatory element binding transcription factor 1 (SREBF1) and fatty acid synthase (FASN). In contrast, mRNA and protein abundance of sterol regulatory element binding transcription factor 2 (SREBF2), acyl coenzyme A-cholesterol acyltransferase, and ATP-binding cassette subfamily A member 1 (ABCA1) were lower. Compared with the FA group, the cholesterol synthesis inhibitor simvastatin led to greater protein abundance of microsomal triglyceride transfer protein and mRNA abundance of SREBF2, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), ACAT2, and lower ABCA1 and FASN protein abundance. In contrast, compared with the FA group, the cholesterol intracellular transport inhibitor U18666A + FA led to greater total cholesterol concentration and greater protein and mRNA abundance of FASN. Compared with the MβCD + FA group, the addition of 10 µmol/L cholesterol led to greater concentration of cholesteryl ester and excretion of apolipoprotein B100, and greater protein and mRNA abundance of ABCA1 and microsomal triglyceride transfer protein, and lower concentration of malondialdehyde. Overall, a reduction in cholesterol synthesis promoted FA metabolism in hepatocytes likely to relieve the oxidative stress caused by the high FA load. The data suggest that maintenance of normal cholesterol synthesis promotes very low-density lipoprotein excretion and can reduce lipid accumulation and oxidative stress in dairy cows that experience fatty liver.

Effects of Atorvastatin on Bile Acid Metabolism in High-fat Diet-fed ApoE -/- Mice

ABSTRACT

Statins are considered as the cornerstone of the prevention and treatment of atherosclerotic cardiovascular disease, where pleiotropic effects are thought to contribute greatly in addition to the lipid-lowering effect. Bile acid metabolism has been gradually reported to be involved in the antihyperlipidemic and antiatherosclerotic effects of statins, but with inconsistent results and few studies carried out on animal models of atherosclerosis. The study aimed to examine the possible role of bile acid metabolism in the lipid-lowering and antiatherosclerotic effects of atorvastatin (ATO) in high-fat diet-fed ApoE -/- mice. The results showed that the levels of liver and faecal TC as well as ileal and faecal TBA were significantly increased in mice of the model group after 20 weeks of high-fat diet feeding compared with the control group, with significantly downregulated mRNA expression of liver LXR-α, CYP7A1, BSEP, and NTCP. ATO treatment further increased the levels of ileal and faecal TBA and faecal TC, but no obvious effect was observed on serum and liver TBA. In addition, ATO significantly reversed the mRNA levels of liver CYP7A1 and NTCP, and no obvious changes were observed in the expression of LXR-α and BSEP. Our study suggested that statins may enhance the synthesis of bile acids and facilitate the reabsorption of bile acids from the ileum via portal into the liver, possibly through the upregulation of the expression of CYP7A1 and NTCP. The results are helpful in enriching the theoretical basis for the clinical use of statins and have good translational value.

The Implication of the Gut Microbiome in Heart Failure

Heart failure is a worldwide health problem with important consequences for the overall wellbeing of affected individuals as well as for the healthcare system. Over recent decades, numerous pieces of evidence have demonstrated that the associated gut microbiota represent an important component of human physiology and metabolic homeostasis, and can affect one's state of health or disease directly, or through their derived metabolites. The recent advances in human microbiome studies shed light on the relationship between the gut microbiota and the cardiovascular system, revealing its contribution to the development of heart failure-associated dysbiosis. HF has been linked to gut dysbiosis, low bacterial diversity, intestinal overgrowth of potentially pathogenic bacteria and a decrease in short chain fatty acids-producing bacteria. An increased intestinal permeability allowing microbial translocation and the passage of bacterial-derived metabolites into the bloodstream is associated with HF progression. A more insightful understanding of the interactions between the human gut microbiome, HF and the associated risk factors is mandatory for optimizing therapeutic strategies based on microbiota modulation and offering individualized treatment. The purpose of this review is to summarize the available data regarding the influence of gut bacterial communities and their derived metabolites on HF, in order to obtain a better understanding of this multi-layered complex relationship.

Effects of Yinzhihuang on Alleviating Cyclosporine A-Induced Cholestatic Liver Injury via Farnesoid X Receptor-Mediated Regulation of Transporters and Enzymes in Vitro and in Vivo

Yinzhihuang (YZH), a traditional Chinese medicine prescription, was widely used to treat cholestasis. Cholestatic liver injury limited the use of the immunosuppressive drug cyclosporine A (CsA) in preventing organ rejection after solid organ transplantation. Clinical evidences suggested that YZH could enhance bile acids and bilirubin clearance, providing a potential therapeutic strategy against CsA-induced cholestasis. Nevertheless, it remains unclear whether YZH can effectively alleviate CsA-induced cholestatic liver injury, as well as the molecular mechanisms responsible for its hepatoprotective effects. The purpose of the present study was to investigate the hepatoprotective effects of YZH on CsA-induced cholestatic liver injury and explore its molecular mechanisms in vivo and vitro. The results demonstrated that YZH significantly improved the CsA-induced cholestatic liver injury and reduced the level of liver function markers in serum of Sprague-Dawley (SD) rats. Targeted protein and gene analysis indicated that YZH increased bile acids and bilirubin efflux into bile through the regulation of multidrug resistance-associated protein 2 (Mrp2), bile salt export pump (Bsep), sodium taurocholate cotransporting polypeptide (Ntcp) and organic anion transporting polypeptide 2 (Oatp2) transport systems, as well as upstream nuclear receptors farnesoid X receptor (Fxr). Moreover, YZH modulated enzymes involved in bile acids synthesis and bilirubin metabolism including Cyp family 7 subfamily A member 1 (Cyp7a1) and uridine 5'-diphosphate (UDP) glucuronosyltransferase family 1 member A1 (Ugt1a1). Furthermore, the active components geniposidic acid, baicalin and chlorogenic acid exerted regulated metabolic enzymes and transporters in LO2 cells. In conclusion, YZH may prevent CsA-induced cholestasis by regulating the transport systems, metabolic enzymes, and upstream nuclear receptors Fxr to restore bile acid and bilirubin homeostasis. These findings highlight the potential of YZH as a therapeutic intervention for CsA-induced cholestasis and open avenues for further research into its clinical applications.

Effects of SLCO1B1 Genetic Variant on Metabolite Profile in Participants on Simvastatin Treatment

Organic-anion-transporting polypeptide 1B1 (OATP1B1), encoded by the solute carrier organic anion transporter family member 1B1 gene (SLCO1B1), is highly expressed in the liver and transports several endogenous metabolites into the liver, including statins. Previous studies have not investigated the association of SLCO1B1 rs4149056 variant with the risk of type 2 diabetes (T2D) or determined the metabolite signature of the C allele of SLCO1B1 rs4149056 (SLCO1B1 rs4149056-C allele) in a large randomly selected population. SLCO1B1 rs4149056-C inhibits OATP1B1 transporter and is associated with increased levels of blood simvastatin concentrations. Our study is to first to show that SLCO1B1 rs4149056 variant is not significantly associated with the risk of T2D, suggesting that simvastatin has a direct effect on the risk of T2D. Additionally, we investigated the effects of SLCO1B1 rs4149056-C on plasma metabolite concentrations in 1373 participants on simvastatin treatment and in 1368 age- and body-mass index (BMI)-matched participants without any statin treatment. We found 31 novel metabolites significantly associated with SLCO1B1 rs4149056-C in the participants on simvastatin treatment and in the participants without statin treatment. Simvastatin decreased concentrations of dicarboxylic acids, such as docosadioate and dodecanedioate, that may increase beta- and peroxisomal oxidation and increased the turnover of cholesterol into bile acids, resulting in a decrease in steroidogenesis due to limited availability of cholesterol for steroid synthesis. Our findings suggest that simvastatin exerts its effects on the lowering of low-density lipoprotein (LDL) cholesterol concentrations through several distinct pathways in the carriers of SLCO1B1 rs4149056-C, including dicarboxylic acids, bile acids, steroids, and glycerophospholipids.

Targets of statins intervention in LDL-C metabolism: Gut microbiota

Increasing researches have considered gut microbiota as a new “metabolic organ,” which mediates the occurrence and development of metabolic diseases. In addition, the liver is an important organ of lipid metabolism, and abnormal lipid metabolism can cause the elevation of blood lipids. Among them, elevated low-density lipoprotein cholesterol (LDL-C) is related with ectopic lipid deposition and metabolic diseases, and statins are widely used to lower LDL-C. In recent years, the gut microbiota has been shown to mediate statins efficacy, both in animals and humans. The effect of statins on microbiota abundance has been deeply explored, and the pathways through which statins reduce the LDL-C levels by affecting the abundance of microbiota have gradually been explored. In this review, we discussed the interaction between gut microbiota and cholesterol metabolism, especially the cholesterol-lowering effect of statins mediated by gut microbiota, via AMPK-PPARγ-SREBP1C/2, FXR and PXR-related, and LPS-TLR4-Myd88 pathways, which may help to explain the individual differences in statins efficacy.

Relation of Statin Use to Gut Microbial Trimethylamine N-Oxide and Cardiovascular Risk

Accumulating evidence suggests that statins can influence the microbiota. We investigated the effects of statin therapy on circulating levels of atherogenic gut microbial metabolite, trimethylamine N-oxide (TMAO), and subsequent clinical outcomes. We examined the effects of statin use on plasma TMAO in patients who are statin-naive with dyslipidemia previously enrolled in 2 intervention studies, International Medical Innovations (n = 79) and Advances in Atorvastatin Research Group (n = 27) in a post hoc analysis. A propensity score matching model stratified by statin use was used to validate the associations between statin use, plasma TMAO, and major adverse cardiovascular events across 4,007 patients who underwent elective coronary angiography. In the International Medical Innovations cohort, at 4 weeks, statin use was associated with decreased plasma TMAO (p = 0.03) and a return to baseline after statin discontinuation. In both intervention cohorts, patients with higher baseline TMAO (predefined cutoff 6.18 μM) showed significant reductions in TMAO (all p <0.05). Propensity score matching on statin use (1,196 patient-pairs) revealed lower plasma TMAO (p = 0.002) with statin use. An adjusted cox regression model including statin use, TMAO, and cholesterol showed preserved association of statin use and TMAO but not cholesterol with major adverse cardiovascular events (p = 0.005, p <0.001, p = 0.24, respectively). A likelihood ratio test showed improved model fit (p <0.001) with the addition of TMAO. In conclusion, our findings demonstrate that statin therapy significantly decreases plasma TMAO levels, suggesting the potential contribution of a statin-mediated reduction of TMAO production in cardiovascular benefits in addition to improved lipid profile and attenuated inflammation.

Survival Benefit of Statin with Anti-Angiogenesis Efficacy in Lung Cancer-Associated Pleural Fluid through FXR Modulation

Simple Summary

Our previous works showed that pleural fluid from lung cancer significantly induced endothelial proliferation, migration, and angiogenesis. Since endothelial metabolism was a key step in angiogenesis, we investigated the role of bile acid signaling and FXR expression in pleural angiogenesis. Elevated bile acid levels in lung-cancer-associated pleural fluid (LCPF) were characterized with positive FXR staining in pleural microvessels. We then confirmed the inhibitory effect of an FXR antagonist on LCPF-induced endothelial migration and angiogenesis. Due to the elevated protein expression in the cholesterol metabolism caused by LCPF, lipid-lowering agents with the efficacy needed to counteract LCPF-regulated angiogenesis were evaluated. Statin showed the potent efficacy needed to suppress LCPF-induced endothelial proliferation, migration, and angiogenesis through FXR inhibition. Following that, Kaplan–Meier analysis showed the survival benefit of statin exposure in patients with lung adenocarcinoma with LCPF. Our results suggest that targeting endothelial FXR signaling with statin treatment could ameliorate the angiogenesis activity of LCPF.

Abstract

Lung cancer-related pleural fluid (LCPF) presents as a common complication with limited treatment. Beyond its function in lipid digestion, bile acid was identified as a potent carcinogen to stimulate tumor proliferation. Previous research indicated a correlation between serum bile acid levels and the risk of developing several gastrointestinal cancers. Our study identified elevated bile acid levels in LCPF and increased farnesoid X receptor (FXR) expression as bile acid nuclear receptors in pleural microvessels of lung adenocarcinoma. Additionally, LCPF stimulated the expression of proteins involved in bile acid synthesis and cholesterol metabolism in HUVECs including CYP7A1, StAR, HMGCR, and SREBP2. LCPF-induced endothelial motility and angiogenesis were counteracted by using β-muricholic acid as an FXR antagonist. Moreover, we investigated the efficacy of cholesterol-lowering medications, such as cholestyramine, fenofibrate, and atorvastatin, in regulating LCPF-regulated angiogenesis. Along with suppressing endothelial proliferation and angiogenesis, atorvastatin treatment reversed cholesterol accumulation and endothelial junction disruption caused by LCPF. Statin treatment inhibited LCPF-induced endothelial FXR expression as well as the downstream proteins RXR and SHP. Based on the positive findings of suppressing endothelial angiogenesis, our group further incorporated the effect of statin on clinical patients complicated with LCPF. A Kaplan–Meier analysis revealed the clinical benefit of statin exposure in patients with lung adenocarcinoma with LCPF. Conclusively, our study demonstrated the ability of statin to alleviate LCPF-induced angiogenesis in patients with LCPF via FXR modulation.

Molecular Regulation of Bile Acid Homeostasis

Bile acids have been known for decades to aid in the digestion and absorption of dietary fats and fat-soluble vitamins in the intestine. The development of gene knockout mice models and transgenic humanized mouse models have helped us understand other functions of bile acids, such as their role in modulating fat, glucose, and energy metabolism, and in the molecular regulation of the synthesis, transport, and homeostasis of bile acids. The G-protein coupled receptor TGR5 regulates the bile acid induced alterations of intermediary metabolism, whereas the nuclear receptor FXR regulates bile acid synthesis and homeostasis. However, this review indicates that unidentified factors in addition to FXR must exist to aid in the regulation of bile acid synthesis and homeostasis. SIGNIFICANCE STATEMENT: This review captures the present understanding of bile acid synthesis, the role of bile acid transporters in the enterohepatic circulation of bile acids, the role of the nuclear receptor FXR on the regulation of bile acid synthesis and bile acid transporters, and the importance of bile acids in activating GPCR signaling via TGR5 to modify intermediary metabolism. This information is useful for developing drugs for the treatment of various hepatic and intestinal diseases, as well as the metabolic syndrome.

Role of the gut microbiome in cardiovascular drug response: The potential for clinical application

Response to cardiovascular drugs can vary greatly between individuals, and the role of the microbiome in this variability is being increasingly appreciated. Recent evidence indicates that bacteria and other microbes are responsible for direct and indirect effects on drug efficacy and toxicity. Pharmacomicrobiomics aims to uncover variability in drug response due to microbes in the human body, which may alter drug disposition through microbial metabolism, interference by microbial metabolites, or modification of host enzymes. In this review, we present recent advances in our understanding of the interplay between microbes, host metabolism, and cardiovascular drugs. We report numerous cardiovascular drugs with evidence of, or potential for, gut-microbe interactions. However, the effects of gut microbiota on many cardiovascular drugs are yet uninvestigated. Finally, we consider potential clinical applications for the described findings.

A gene-diet interaction controlling relative intake of dietary carbohydrates and fats

OBJECTIVE

Preference for dietary fat vs. carbohydrate varies markedly across free-living individuals. It is recognized that food choice is under genetic and physiological regulation, and that the central melanocortin system is involved. However, how genetic and dietary factors interact to regulate relative macronutrient intake is not well understood.

METHODS

We investigated how the choice for food rich in carbohydrate vs. fat is influenced by dietary cholesterol availability and agouti-related protein (AGRP), the orexigenic component of the central melanocortin system. We assessed how macronutrient intake and different metabolic parameters correlate with plasma AGRP in a cohort of obese humans. We also examined how both dietary cholesterol levels and inhibiting de novo cholesterol synthesis affect carbohydrate and fat intake in mice, and how dietary cholesterol deficiency during the postnatal period impacts macronutrient intake patterns in adulthood.

RESULTS

In obese human subjects, plasma levels of AGRP correlated inversely with consumption of carbohydrates over fats. Moreover, AgRP-deficient mice preferred to consume more calories from carbohydrates than fats, more so when each diet lacked cholesterol. Intriguingly, inhibiting cholesterol biosynthesis (simvastatin) promoted carbohydrate intake at the expense of fat without altering total caloric consumption, an effect that was remarkably absent in AgRP-deficient mice. Finally, feeding lactating C57BL/6 dams and pups a cholesterol-free diet prior to weaning led the offspring to prefer fats over carbohydrates as adults, indicating that altered cholesterol metabolism early in life programs adaptive changes to macronutrient intake.

CONCLUSIONS

Together, our study illustrates a specific gene-diet interaction in modulating food choice.

A case of infantile Alagille syndrome with severe dyslipidemia: a new insight into lipid metabolism and therapeutics

Alagille syndrome (AGS) is an autosomal dominant genetic disorder characterized by congenital heart disease, hepatic cholestasis, dyslipidemia, and characteristic facies since infancy. Cholestatic hypercholesterolemia in patients diagnosed with AGS is occasionally refractory and resistant to conventional treatments. We report the case of a 4-month-old boy diagnosed with AGS and refractory dyslipidemia due to cholestatic liver disease. He had repeated episodes of cyanosis due to pulmonary artery atresia since birth and underwent a Blalock-Taussig shunt procedure at age 3 months. At age 4 months, cholestatic hyperbilirubinemia deteriorated to a serum total bilirubin level of 19.9 mg/dL. At age 12 months, a laboratory test revealed severe dyslipidemia (serum total cholesterol, 1796 mg/dL; serum triglycerides [TGs], 635 mg/dL), and the presence of xanthomas. A pathogenic variant of the JAG1 gene (c.1326G > A, p.Trp442X) was detected through genetic testing. Oral ursodeoxycholate normalized hyperbilirubinemia with a subtle improvement in dyslipidemia. Combination therapy with pravastatin and fenofibrate did not successfully improve dyslipidemia. At age 20 months, altering pravastatin to atorvastatin was effective in normalizing serum cholesterol and TGs with no adverse events.

Combination therapy with atorvastatin and fenofibrate was successful in improving refractory dyslipidemia in a child with AGS. Atorvastatin is a well-known strong statin that can lower serum cholesterol, and fenofibrate can lower serum TG levels. We propose that atorvastatin be taken into consideration for the treatment of persistent hyperlipidemia in patients diagnosed with AGS, because atorvastatin upregulates bile acid synthesis and lipoprotein scavenging, and inhibits intrinsic cholesterol production.

RNA-Seq unveiled section-specific host response to lack of gut microbiota in mouse intestine

To identify host responses induced by commensal microbiota in intestine, transcriptomes of four sections of the intestine were compared between germ-free (GF) mice and conventional (CV) controls using RNA-Seq. Cuffdiff revealed that jejunum had the highest number of differentially expressed genes (over 2000) between CV and GF mice, followed by large intestine (LI), duodenum, and ileum. Gene set association analysis identified section-specific alterations in pathways associated with the absence of commensal microbiota. For example, in GF mice, cytochrome P450 (Cyp)-mediated xenobiotic metabolism was preferably down-regulated in duodenum and ileum, whereas intermediary metabolism pathways such as protein digestion and amino acid metabolism were preferably up-regulated in duodenum, jejunum, and LI. In GF mice, carboxypeptidase A1 (Cpa1), which is important for protein digestion, was the top most up-regulated gene within the entire transcriptome in duodenum (53-fold) and LI (142-fold). Conversely, fatty acid binding protein 6 (Fabp6/Ibabp), which is important for bile acid intestinal reabsorption, was the top most down-regulated gene in jejunum (358-fold), and the drug-metabolizing enzyme Cyp1a1 was the top most down-regulated gene in ileum (40-fold). Section-specific host transcriptomic response to the absence of intestinal microbiota was also observed for other important physiological pathways such as cell junction, the absorption of small molecules, bile acid homeostasis, and immune response. In conclusion, the present study has revealed section-specific host gene transcriptional alterations in GF mice, highlighting the importance of intestinal microbiota in facilitating the physiological and drug responses of the host intestine.

Circulating bile acids concentration is predictive of coronary artery disease in human

Synthetized by the liver and metabolized by the gut microbiota, BA are involved in metabolic liver diseases that are associated with cardiovascular disorders. Animal models of atheroma documented a powerful anti-atherosclerotic effect of bile acids (BA). This prospective study examined whether variations in circulating BA are predictive of coronary artery disease (CAD) in human. Consecutive patients undergoing coronary angiography were enrolled. Circulating and fecal BA were measured by high pressure liquid chromatography and tandem mass spectrometry. Of 406 screened patients, 80 were prospectively included and divided in two groups with (n = 45) and without (n = 35) CAD. The mean serum concentration of total BA was twice lower in patients with, versus without CAD (P = 0.005). Adjusted for gender and age, this decrease was an independent predictor of CAD. In a subgroup of 17 patients, statin therapy doubled the serum BA concentration. Decreased serum concentrations of BA were predictors of CAD in humans. A subgroup analysis showed a possible correction by statins. With respect to the anti-atherosclerotic effect of BA in animal models, and their role in human lipid metabolism, this study describe a new metabolic disturbance associated to CAD in human.

Can manipulation of gut microbiota really be transformed into an intervention strategy for cardiovascular disease management?

Recent advancement in manipulation techniques of gut microbiota either ex vivo or in situ has broadened its plausible applicability for treating various diseases including cardiovascular disease. Several reports suggested that altering gut microbiota composition is an effective way to deal with issues associated with managing cardiovascular diseases. However, actual translation of gut microbiota manipulation-based techniques into cardiovascular-therapeutic approach is still questionable. This review summarized the evidence on challenges, opportunities, recent development, and future prospects of gut microbiota manipulation for targeting cardiovascular diseases. Initially, issues associated with current cardiovascular diseases treatment strategy, association of gut microbiota with cardiovascular disease, and its influence on cardiovascular drugs were discussed, followed by applicability of gut microbiota manipulation as a cardiovascular disease intervention strategy along with its challenges and future prospects. Despite the fact that the gut microbiota is rugged, interventions like probiotics, prebiotics, synbiotics, fecal microbiota transplantation, fecal virome transplantation, antibiotics, diet changes, and exercises could manipulate it. Advanced techniques like administration of engineered bacteriophages and bacteria could also be employed. Intensive exploration revealed that if sufficiently controlled approach and proper monitoring were applied, gut microbiota could provide a compelling answer for cardiovascular therapy.

Impact of non-antibiotic drugs on the human intestinal microbiome

INTRODUCTION

The gut microbiota is composed of trillions of microbial cells and viruses that interact with hosts. The composition of the gut microbiota is influenced by several factors including age, diet, diseases, or medications. The impact of drugs on the microbiota is not limited to antibiotics and many non-antibiotic molecules significantly alter the composition of the intestinal microbiota.

AREAS COVERED

This review focuses on the impact of four of the most widely prescribed non-antibiotic drugs in the world: Proton-pump inhibitors, metformin, statins, and non-steroidal anti-inflammatory. We conducted a systematic review by searching online databases including Medline, Web of science, and Scopus for indexed articles published in English until February 2021. We included studies assessing the intestinal microbiome alterations associated with proton pump inhibitors (PPIs), metformin, statins, and nonsteroidal anti-inflammatory drugs (NSAIDs). Only studies using culture-independent molecular techniques were included.

EXPERT OPINION

The taxonomical signature associated with non-antibiotic drugs are not yet fully described, especially in the field of metabolomic. The identification of taxonomic profiles associated a specific molecule provides information on its mechanism of action through interaction with the intestinal microbiota. Many side effects could be related to the dysbiosis induced by these molecules.

Plasma Bile Acid Profile in Patients with and without Type 2 Diabetes

A paucity of information currently exists on plasma bile acid (BA) profiles in patients with and without type 2 diabetes mellitus (T2DM). We assayed 14 plasma BA species in 224 patients with T2DM and in 102 nondiabetic individuals with metabolic syndrome. Plasma BA levels were measured with ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) technique. Multivariable linear regression analyses were undertaken to assess associations between measured plasma BA species and T2DM status after adjustment for confounding factors. The presence of T2DM was significantly associated with higher plasma concentrations of both primary BAs (adjusted-standardized β coefficient: 0.279, p = 0.005) and secondary BAs (standardized β coefficient: 0.508, p < 0.001) after adjustment for age, sex, adiposity measures, serum alanine aminotransferase and use of statins or metformin. More specifically, the presence of T2DM was significantly associated with higher levels of plasma taurochenodeoxycholic acid, taurodeoxycholic acid, glycochenodeoxycholic acid, hyodeoxycholic acid, glycodeoxycholic acid, glycolithocholic acid, deoxycholic acid, taurochenodeoxycholic acid, taurodeoxycholic acid, glycochenodeoxycholic acid and glycodeoxycholic acid (adjusted-standardized β coefficients ranging from 0.315 to 0.600; p < 0.01 or less), as well as with lower plasma levels of cholic acid (adjusted-standardized β coefficient: −0.250, p = 0.013) and taurocholic acid (adjusted-standardized β coefficient: −0.309, p = 0.001). This study shows that there are marked differences in plasma BA profiles between patients with and without T2DM. Further research will be needed to better understand how these differences in plasma BA profiles may interplay with the pathophysiology of T2DM.

Atorvastatin Modulates Bile Acid Homeostasis in Mice with Diet-Induced Nonalcoholic Steatohepatitis

Bile acids (BA) play a significant role in the pathophysiology of nonalcoholic steatohepatitis (NASH). The present study evaluates the modulation of bile acid metabolomics by atorvastatin, a cholesterol-lowering agent commonly used to treat cardiovascular complications accompanying NASH. NASH was induced in mice by 24 weeks of consuming a high–saturated fat, high-fructose, and high-cholesterol diet (F), with atorvastatin administered orally (20 mg/kg/day) during the last three weeks. Biochemical and histological analyses confirmed the effectiveness of the F diet in inducing NASH. Untreated NASH animals had significantly reduced biliary secretion of BA and increased fecal excretion of BA via decreased apical sodium-dependent bile salt transporter (Asbt)-mediated reabsorption. Atorvastatin decreased liver steatosis and inflammation in NASH animals consistently with a reduction in crucial lipogenic enzyme stearoyl–coenzyme A (CoA) desaturase-1 and nuclear factor kappa light chain enhancer of activated B-cell pro-inflammatory signaling, respectively. In this group, atorvastatin also uniformly enhanced plasma concentration, biliary secretion and fecal excretion of the secondary BA, deoxycholic acid (DCA). However, in the chow diet–fed animals, atorvastatin decreased plasma concentrations of BA, and reduced BA biliary secretions. These changes stemmed primarily from the increased fecal excretion of BA resulting from the reduced Asbt-mediated BA reabsorption in the ileum and suppression of synthesis in the liver. In conclusion, our results reveal that atorvastatin significantly modulates BA metabolomics by altering their intestinal processing and liver synthesis in control and NASH mice.

Co-administration of obeticholic acid and simvastatin protects against high-fat diet-induced non-alcoholic steatohepatitis in mice

Non-alcoholic steatohepatitis (NASH) has no approved therapy. The farnesoid X nuclear receptor (FXR) agonist obeticholic acid (OCA) has shown promise as a drug for NASH, but can adversely affect plasma lipid profiles. Therefore, the present study aimed to investigate the effects and underlying mechanisms of OCA in combination with simvastatin (SIM) in a high-fat diet (HFD)-induced model of NASH. C57BL/6J mice were fed with a HFD for 16 weeks to establish the NASH model. The mice were randomly divided into the following five groups: HFD, HFD + OCA, HFD + SIM, HFD + OCA + SIM and control. After 16 weeks, the mice were sacrificed under anesthesia. The ratios of liver weight to body weight (Lw/Bw) and of abdominal adipose tissue weight to body weight were calculated. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol, triglycerides and low-density lipoprotein were measured. Liver sections were stained with hematoxylin and eosin. The protein levels of FXR, small heterodimeric partner (SHP) and cytochrome P450 family 7 subfamily A member 1 (CYP7A1) in the liver were detected by western blotting, while the mRNA levels of FXR, SHP, CYP7A1, bile salt export pump, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), sterol regulatory element binding protein-1 (SREBP1) and fatty acid synthase (FASN) were examined by reverse transcription-quantitative polymerase chain reaction. The administration of OCA with or without SIM reduced the liver inflammation score compared with those of the HFD and HFD + SIM groups, with no significant difference between the HFD + OCA and HFD + OCA + SIM groups. The steatosis score followed similar trends to the inflammation score. In HFD-fed mice, OCA combined with SIM prevented body weight gain compared with that in HFD and HFD + OCA groups, and reduced the Lw/Bw ratio compared with that in the HFD and HFD + SIM groups. In addition to preventing HFD-induced increases of ALT and AST, the combination of OCA and SIM reduced the mRNA levels of IL-6, TNF-α, SREBP1 and FASN. On the basis of these results, it may be concluded that the strategy of combining OCA with SIM represents an effective pharmacotherapy for NASH.

Atorvastatin Induces FXR and CYP7A1 Activation as a Result of the Sequential Action of PPARγ/PGC-1α/HNF-4α in Hep3B Cells

Backgrounds/Aims

PPARγ, farnesoid X receptor (FXR) and CYP7A1 are associated with solubility of bile. This study was performed to understand a mechanism and interactions of statin-induced PPARγ, PGC-1α and HNF-4α related to the statin-induced activation of FXR and CYP7A1, and verify whether the mevalonate pathway is involved in the mechanism.

Methods

MTT assays were performed using cultured human Hep3B cells to determine the effect of atorvastatin on the cell proliferation. Expression levels of indicated proteins were measured using Western blotting assays by inhibiting the protein expression or not.

Results

Atorvastatin increased expression of PPARγ, PGC-1α, HNF-4α, FXR, and CYP7A1 in Hep3B cells. PPARγ ligand of troglitazone upregulated the expression of PGC-1α, HNF-4α, FXR, and CYP7A1 in Hep3B cells. Silencing of PPARγ, PGC1α, and HNF4α using respective siRNA demonstrated that atorvastatin-induced FXR and CYP7A1 activation required sequential action of PPARγ /PGC-1α/HNF-4α. The silencing of PPARγ completely inhibited atorvastatin-induced PGC-1α expression, and the PGC1α silencing partially inhibited atorvastatin-induced PPARγ expression. The inhibition of HNF4α did not affect atorvastatin-induced PPARγ expression, but partially inhibited atorvastatin-induced PGC-1α expression. Besides, mevalonate completely reversed the effect of atorvastatin on PPARγ, PGC-1α, HNF-4α, FXR, and CYP7A1.

Conclusions

Atorvastatin induces FXR and CYP7A1 activation as a result of sequential action of PPARγ/PGC-1α/HNF-4α in human hepatocytes. We propose that atorvastatin enhances solubility of cholesterol in bile by simultaneously activating of FXR and CYP7A1.

Development and Validation of a Highly Sensitive LC-MS/MS Method for the Analysis of Bile Acids in Serum, Plasma, and Liver Tissue Samples

Bile acids control lipid homeostasis by regulating uptake from food and excretion. Additionally, bile acids are bioactive molecules acting through receptors and modulating various physiological processes. Impaired bile acid homeostasis is associated with several diseases and drug-induced liver injury. Individual bile acids may serve as disease and drug toxicity biomarkers, with a great demand for improved bile acid quantification methods. We developed, optimized, and validated an LC-MS/MS method for quantification of 36 bile acids in serum, plasma, and liver tissue samples. The simultaneous quantification of important free and taurine- and glycine-conjugated bile acids of human and rodent species has been achieved using a simple workflow. The method was applied to a mouse model of statin-induced myotoxicity to assess a possible role of bile acids. Treatment of mice for three weeks with 5, 10, and 25 mg/kg/d simvastatin, causing adverse skeletal muscle effects, did not alter plasma and liver tissue bile acid profiles, indicating that bile acids are not involved in statin-induced myotoxicity. In conclusion, the established LC-MS/MS method enables uncomplicated sample preparation and quantification of key bile acids in serum, plasma, and liver tissue of human and rodent species to facilitate future studies of disease mechanisms and drug-induced liver injury.

Gut microbiome: A possible common therapeutic target for treatment of atherosclerosis and cancer

Human gut microbiota is a dynamic and variable system that can change over time and in response to different diets and treatments. There is currently no doubt that gut microbiota can provide interesting therapeutic opportunities, since it can metabolize biologically active molecules, drugs, and their precursors, and control their bioavailability. Moreover, it can produce both beneficial and dangerous metabolites that influence host's health. In this review, we summarize the current knowledge on the involvement of gut microbiota in two chronic human pathologies that represent the greatest challenges of modern medicine: atherosclerosis and cancer. Interesting parallels are observed between the mechanisms and possible treatment approaches of these pathologies. Some of the common effects of therapeutic agents targeting both pathologies, such as anti-inflammatory activity, are partially mediated by the gut microbiota. We will discuss the effects of common drugs (metformin, statins and aspirin) and various nutraceuticals on gut microbiota and outline the pathways of microbial involvement in mediating the pleiotropic beneficial effects of these agents in atherosclerosis and cancer.

Interactions between Atorvastatin and the Farnesoid X Receptor Impair Insulinotropic Effects of Bile Acids and Modulate Diabetogenic Risk

Bile acids such as chenodeoxycholic acid (CDC) acutely enhance insulin secretion via the farnesoid X receptor (FXR). Statins, which are frequently prescribed for patients with type 2 diabetes who suffer from dyslipidemia, are known for their diabetogenic risk and are reported to interact with the FXR. Our study investigates whether this interaction is relevant for beta cell signaling and plays a role for negative effects of statins on glycemic control. Experiments were performed with islets and islet cells from C57BL/6N wild-type and FXR-knockout (KO) mice. Culturing islets with atorvastatin (15 µM) for 24 hours decreased glucose-stimulated insulin secretion by approximately 30% without affecting ATP synthesis. Prolonged exposure for 7 days lowered the concentration necessary for impairment of insulin release to 150 nM. After 24-hour culture with atorvastatin, the ability of CDC (500 nM) to elevate [Ca2+]c was diminished and the potentiating effect on insulin secretion was completely lost. Mevalonate largely reduced the negative effect of atorvastatin. Nuclear activity of FXR was reduced by atorvastatin in a mouse FXR reporter assay. The atorvastatin-induced decrease in insulin release was also present in FXR-KO mice. Although not a prerequisite, FXR seems to influence the degree of damage caused by atorvastatin depending on its interaction with CDC: Preparations responding to CDC with an increase in insulin secretion under control conditions were less impaired by atorvastatin than preparations that were nonresponsive to CDC. Extended stimulation of FXR by the synthetic agonist GW4064, which is suggested to induce translocation of FXR from the cytosol into the nucleus, increased the inhibitory effect of atorvastatin. In conclusion, atorvastatin inhibits insulin release and prevents positive effects of bile acids on beta cell function. Both interactions may contribute to progression of type 2 diabetes mellitus. SIGNIFICANCE STATEMENT: This study shows that the diabetogenic risk of statins is coupled to the activity of farnesoid X receptor (FXR)-dependent signaling pathways in beta cells. On the one hand, statins abolish the insulinotropic effects of bile acids and on the other hand, FXR determines the level of impairment of islet function by the statin.

Effect of Cytochrome P450 7A1 (CYP7A1) Polymorphism on Lipid Responses to Simvastatin Treatment

BACKGROUND

Identifying patients with high risk of low response to statin therapy is important for optimization of lipid-lowering therapy. Cholesterol 7α-hydroxylase, a rate-limiting enzyme encoded by cytochrome P450 7A1 (CYP7A1) gene, is considered to be associated with statin efficacy. This study aimed to investigate the association between a novel CYP7A1 single nucleotide polymorphism rs3824260 and statin treatment response for hypercholesteremic patients in Chinese Han population.

METHODS

A total of 336 subjects were prescribed with simvastatin for 12 weeks after enrollment. Plasma lipid parameters were measured at enrollment and after 12-week simvastatin treatment separately. Subjects were classified into high- and low-response groups depending on their total cholesterol, low-density lipoprotein cholesterol (LDL-C) and TG changes and increase or reduction groups according to their high-density lipoprotein cholesterol (HDL-C) levels changing after simvastatin treatment. The CYP7A1 rs3824260 was genotyped from blood samples with a SNaPshot assay.

RESULTS

At baseline, the LDL-C level and TG level were significantly higher in the AA genotype, while the HDL-C level was significantly higher in the GG genotype of CYP7A1 rs3824260. Patients carrying AA genotype are at an increased risk of low response for LDL-C reduction (odds ratio = 2.295, 95% confidence interval = 1.164-4.524, P = 0.016). Furthermore, the GG genotype of rs3824260 was significantly associated with a high risk of HDL-C reduction response after simvastatin therapy (odds ratio = 2.240, 95% confidence interval = 1.137-4.413, P = 0.025).

CONCLUSIONS

The CYP7A1 gene polymorphism rs3824260 is related to inappropriate response of simvastatin treatment for hypercholesterolemia patients in Chinese Han population.

Gut Microbiome and Response to Cardiovascular Drugs

The gut microbiome is emerging as an important contributor to both cardiovascular disease risk and metabolism of xenobiotics. Alterations in the intestinal microbiota are associated with atherosclerosis, dyslipidemia, hypertension, and heart failure. The microbiota have the ability to metabolize medications, which can results in altered drug pharmacokinetics and pharmacodynamics or formation of toxic metabolites which can interfere with drug response. Early evidence suggests that the gut microbiome modulates response to statins and antihypertensive medications. In this review, we will highlight mechanisms by which the gut microbiome facilitates the biotransformation of drugs and impacts pharmacological efficacy. A better understanding of the complex interactions of the gut microbiome, host factors, and response to medications will be important for the development of novel precision therapeutics for targeting CVD.

Statins increase Lp(a) plasma level: is this clinically relevant?

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Combined Effect of Diosgenin Along with Ezetimibe or Atorvastatin on the Fate of Labelled Bile Acid and Cholesterol in Hypercholesterolemic Rats

We analyzed the effect of diosgenin, administered with atorvastatin or ezetimibe, on the fate of ³H(G)-taurocholic acid or 26-¹⁴C-cholesterol in hypercholesterolemic rats. Male Wistar rats received a hypercholesterolemic diet (HD), HD + atorvastatin (HD+ATV), HD + ezetimibe (HD+EZT), HD + diosgenin (HD+DG), HD+ATV+EZT, or HD+ATV+DG for 40 days. We also included a control normal group (ND). The labelled compounds were administered on day 30. The animals were placed in metabolic cages for daily feces collection. At day 40 the rats were sacrificed. Lipid extracts from blood, liver, spinal cord, testicles, kidneys, epididymis, intestine, and feces were analyzed for radioactivity. Cholesterol activity was the highest in the liver in HD rats. DG diminished one half of this activity in HD+DG and HD+ATV+DG groups in comparison with the HD group. HD+ATV rats showed four to almost ten-fold cholesterol activity in the spinal cord compared with the ND or HD rats. Fecal elimination of neutral steroids was approximately two-fold higher in the HD+DG and HD+ATV+DG groups. Taurocholic acid activity was four to ten-fold higher in HD+DG intestine as compared to the other experimental groups. Taurocholic activity in the liver of HD and HD+DG groups was two and a half higher than in ND. Our results show that the combination of DG and ATV induced the highest cholesterol reduction in the liver and other tissues.

Non-surgical treatment of cholesterol gallstones: An update on recent developments

Cholesterol gallstones (CS) are a common disease of the digestive system. The imbalance of cholesterol and bile acid metabolism tends to result in the deposition of cholesterol crystals, which is the basis of gallstone formation. Current guidelines recommend cholecystectomy for CS patients with any symptoms. Nevertheless, there are still some patients without surgical indications, surgical conditions, or surgical consent, who may be benefit from non-surgical treatment. However, there are not too many tips for non-surgical treatment of CS in latest guidelines, nor sufficient attention paid form clinicians. This paper reviews the relevant recent literature on non-surgical treatment of CS, with an aim to help clinicians be familiar with non-surgical treatment of CS.

FXR activation by obeticholic acid or nonsteroidal agonists induces a human-like lipoprotein cholesterol change in mice with humanized chimeric liver

Obeticholic acid (OCA) is a selective farnesoid X receptor (FXR) agonist that regulates bile acid and lipid metabolism. FXR activation induces distinct changes in circulating cholesterol among animal models and humans. The mechanistic basis of these effects has been elusive because of difficulties in studying lipoprotein homeostasis in mice, which predominantly package circulating cholesterol in HDLs. Here, we tested the effects of OCA in chimeric mice whose livers are mostly composed (≥80%) of human hepatocytes. Chimeric mice exhibited a human-like ratio of serum LDL cholesterol (LDL-C) to HDL cholesterol (HDL-C) at baseline. OCA treatment in chimeric mice increased circulating LDL-C and decreased circulating HDL-C levels, demonstrating that these mice closely model the cholesterol effects of FXR activation in humans. Mechanistically, OCA treatment increased hepatic cholesterol in chimeric mice but not in control mice. This increase correlated with decreased SREBP-2 activity and target gene expression, including a significant reduction in LDL receptor protein. Cotreatment with atorvastatin reduced total cholesterol, rescued LDL receptor protein levels, and normalized serum LDL-C. Treatment with two clinically relevant nonsteroidal FXR agonists elicited similar lipoprotein and hepatic changes in chimeric mice, suggesting that the increase in circulating LDL-C is a class effect of FXR activation.

Assessment of serum bile acid profiles as biomarkers of liver injury and liver disease in humans

To assess the potential of individual bile acids (IBA) and their profiles as mechanistic biomarkers of liver injury for humans in real world situations, we interrogated samples collected under minimum controlled conditions (ie subjects were not fasted). Total bile acids (TBA) have been considered to be biomarkers of liver injury for decades, and more recently, monitoring of IBA has been proposed for differentiation of variety of etiologies of liver injury. We established a LC-MS/MS methodology to analyze nine IBA, generated reference ranges, and examined effects of age, gender, and ethnicity for each IBA. Furthermore, we evaluated the ability of IBA and their profiles to detect hepatic injury in subjects with a broad range of liver impairments. To date, our study utilized the largest total cohort of samples (N = 645) that were divided into 2 groups, healthy or liver impaired, to evaluate IBA as biomarkers. The TBA serum levels in the Asian ethnic group trended higher when compared to other ethnic groups, and the serum concentrations of IBA, such as glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), chenodeoxycholic acid (CDCA), and taurochenoxycholic acid (TCDCA) were significantly increased. To our knowledge, this report is the first to describe ethnic differences in serum concentrations of IBAs. In patients with hepatic impairments, with the exception of deoxycholic acid (DCA), the concentrations of IBAs were significantly elevated when compared with healthy subjects. The conjugated bile acids displayed greater differences between healthy subjects and subjects with hepatic impairments than non-conjugated bile acids. Furthermore, the subjects with hepatic impairments exhibited distinct profiles (signatures) of IBAs that clustered subjects according the nature of their liver impairments. Although additional studies are needed, our data suggested that the analysis of IBA has the potential to become useful for differentiation of various forms of liver injury.

Atorvastatin Treatment Modulates the Gut Microbiota of the Hypercholesterolemic Patients

Hypercholesterolemia is one of the most important risk factors for development of cardiovascular diseases. The composition of gut microbiota (total microbes residing in the gut) impacts on cholesterol and lipid metabolism. On the contrary, alterations in gut microbiota in response to hypercholesterolemia or drug treatment with atorvastatin (a cholesterol-lowering agent) are rarely investigated. We performed 16S rDNA amplicon sequencing to evaluate the gut bacterial community of 15 untreated hypercholesterolemic patients (HP) and 27 atorvastatin-treated hypercholesterolemic patients (At-HP) and compared with 19 healthy subjects (HS). In total, 18 different phyla were identified in the study groups. An increase in relative abundance of Proteobacteria was observed in the HP group compared with At-HP and HS groups. The atherosclerosis-associated genus Collinsella was found at relatively higher abundance in the HP group. The anti-inflammation-associated bacteria (Faecalibacterium prausnitzii, Akkermansia muciniphila, and genus Oscillospira) were found in greater abundance, and proinflammatory species Desulfovibrio sp. was observed at decreased abundance in the drug-treated HP group compared with the untreated HP group. Relative abundances of the Bilophila wadsworthia and Bifidobacterium bifidum (bile acid-associated species) were decreased in the At-HP group. The At-HP and HS clustered separately from HP in the principal coordinate analysis. Decreased bacterial diversity was observed in the atorvastatin-treated group. In conclusion, these data suggest that atorvastatin treatment of patients with hypercholesterolemia may selectively restore the relative abundance of several dominant and functionally important taxa that were disrupted in the HP. Further studies are required to investigate the putative modifying effects of hypocholesterolemic drugs on functionality of gut microbiota, and the potential downstream effects on human health.

Cranberry anthocyanin as an herbal medicine lowers plasma cholesterol by increasing excretion of fecal sterols

BACKGROUND

Interest in using herbal medicines to treat the hypercholesterolemia is increasing. Cranberry extract could decrease plasma cholesterol, however, the active ingredients and the underlying mechanisms remain largely unknown.

HYPOTHESIS

The present study was to test the hypothesis that cranberry anthocyanins (CrA) were at least one of the active ingredients responsible for the cholesterol-lowering activity of cranberry fruits via a mechanism of increasing fecal sterol excretion.

METHODS

Forty-four hamsters were randomly divided into five groups and fed one of the five diets, namely a non-cholesterol control diet (NCD), a high-cholesterol control diet (HCD), a HCD diet supplemented with a low dose of 1% CrA (CL), a HCD diet supplemented with a high dose of 2% CrA (CH), and a HCD diet supplemented with 0.5% cholestyramine as a positive control drug (P-CTL), respectively, for six weeks. Plasma lipoprotein cholesterol was quantified using the enzymatic kits, while the gene expressions of transporters, enzymes and receptors involved in cholesterol absorption and metabolism were quantified using the quantitative RT-PCR. Fecal sterols were quantified using gas chromatography (GC).

RESULTS

Plasma total cholesterol and aorta atherosclerotic plaque decreased dose-dependently with the increasing amounts of CrA added into diets. This was accompanied by a dose-dependent increase in excretion of both neutral and acidic sterols. CrA had no effect on the mRNA levels of intestinal Niemann-Pick C1 like 1 protein (NPC1L1), acyl CoA:cholesterol acyltransferase2 (ACAT2), microsomal triacylglycerol transport protein (MTP), and ATP binding cassette transporter 5 (ABCG5) as well as hepatic cholesterol-7α-hydroxylase (CYP7A1), 3-Hydroxy-3-methylglutaryl reductase (HMG-CoA-R), sterol regulatory element binding protein 2 (SREBP2), LDL receptor (LDL-R), and Liver X receptor alpha (LXRα).

CONCLUSION

CrA as an herbal medicine could favorably modify the lipoprotein profile in hamsters fed a high cholesterol diet by enhancing excretion of fecal neutral and acidic sterols, most likely not mediated by interaction with genes of transporters, enzymes and proteins involved in cholesterol absorption and metabolism.

RNA-Seq Profiling of Intestinal Expression of Xenobiotic Processing Genes in Germ-Free Mice

Intestinal bacteria can affect xenobiotic metabolism through both direct bacterial enzyme-catalyzed modification of the xenobiotics and indirect alterations of the expression of host genes. To determine how intestinal bacteria affect the expression of host xenobiotic-processing genes (XPGs), the mRNA profiles of 303 XPGs were characterized by RNA sequencing in four intestinal sections and compared with that in the liver from adult male conventional (CV) and germ-free (GF) mice. Fifty-four XPGs were not expressed in the intestine of either CV or GF mice. The GF condition altered the expression of 116 XPGs in at least one intestinal section but had no effect on 133 XPGs. Many cytochrome P450 family members such as Cyp1a, Cyp2b10, Cyp2c, and most Cyp3a members, as well as carboxylesterase (Ces) 2a were expressed lower in the intestine of GF than CV mice. In contrast, GF mice had higher intestinal expression of some phase I oxidases (alcohol dehydrogenase 1, aldehyde dehydrogenase a1l1 and 4a1, as well as flavin monooxygenase 5) and phase II conjugation enzymes (UDP-glucuronosyltransferase 1a1, and sulfotransferase 1c2, 1d1, and 2b1). Several transporters in the intestine, such as bile acid transporters (apical sodium-dependent bile acid transporter, organic solute transporter α and β), peptide transporter 1, and multidrug and toxin extrusion protein 1, exhibited higher expression in GF mice. In conclusion, lack of intestinal bacteria alters the expression of a large number of XPGs in the host intestine, some of which are section specific. Cyp3a is downregulated in both the liver and intestine of GF mice, which probably contributes to altered xenobiotic metabolism.

Statin therapy causes gut dysbiosis in mice through a PXR-dependent mechanism

BACKGROUND

Statins are a class of therapeutics used to regulate serum cholesterol and reduce the risk of heart disease. Although statins are highly effective in removing cholesterol from the blood, their consumption has been linked to potential adverse effects in some individuals. The most common events associated with statin intolerance are myopathy and increased risk of developing type 2 diabetes mellitus. However, the pathological mechanism through which statins cause these adverse effects is not well understood.

RESULTS

Using a murine model, we describe for the first time profound changes in the microbial composition of the gut following statin treatment. This remodelling affected the diversity and metabolic profile of the gut microbiota and was associated with reduced production of butyrate. Statins altered both the size and composition of the bile acid pool in the intestine, tentatively explaining the observed gut dysbiosis. As also observed in patients, statin-treated mice trended towards increased fasting blood glucose levels and weight gain compared to controls. Statin treatment affected the hepatic expression of genes involved in lipid and glucose metabolism. Using gene knockout mice, we demonstrated that the observed effects were mediated through pregnane X receptor (PXR).

CONCLUSION

This study demonstrates that statin therapy drives a profound remodelling of the gut microbiota, hepatic gene deregulation and metabolic alterations in mice through a PXR-dependent mechanism. Since the demonstrated importance of the intestinal microbial community in host health, this work provides new perspectives to help prevent the statin-associated unintended metabolic effects.

Atorvastatin alters the expression of genes related to bile acid metabolism and circadian clock in livers of mice

Aim

Atorvastatin is a HMG-CoA reductase inhibitor used for hyperlipidemia. Atorvastatin is generally safe but may induce cholestasis. The present study aimed to examine the effects of atorvastatin on hepatic gene expression related to bile acid metabolism and homeostasis, as well as the expression of circadian clock genes in livers of mice.

Methods

Adult male mice were given atorvastatin (10, 30, and 100 mg/kg, po) daily for 30 days, and blood biochemistry, histopathology, and gene expression were examined.

Results

Repeated administration of atorvastatin did not affect animal body weight gain or liver weights. Serum enzyme activities were in the normal range. Histologically, the high dose of atorvastatin produced scattered swollen hepatocytes, foci of feathery-like degeneration, together with increased expression of Egr-1 and metallothionein-1. Atorvastatin increased the expression of Cyp7a1 in the liver, along with FXR and SHP. In contract, atorvastatin decreased the expression of bile acid transporters Ntcp, Bsep, Ostα, and Ostβ. The most dramatic change was the 30-fold induction of Cyp7a1. Because Cyp7a1 is a circadian clock-controlled gene, we further examined the effect of atorvastatin on clock gene expression. Atorvastatin increased the expression of clock core master genes Bmal1 and Npas2, decreased the expression of clock feedback genes Per2, Per3, and the clock targeted genes Dbp and Tef, whereas it had no effect on Cry1 and Nr1d1 expression.

Conclusion

Repeated administration of atorvastatin affects bile acid metabolism and markedly increases the expression of the bile acid synthesis rate-limiting enzyme gene Cyp7a1, together with alterations in the expression of circadian clock genes.

Liver carcinogenesis by FOS-dependent inflammation and cholesterol dysregulation

Hepatocellular cancers arise in a background of liver damage and inflammation. Bakiri et al. describe the function of the transcription factor c-Fos/AP-1 using mouse models and human data. c-Fos affects cholesterol and bile acid metabolism and induces DNA damage and inflammation, thus promoting liver cancer.

Human hepatocellular carcinomas (HCCs), which arise on a background of chronic liver damage and inflammation, express c-Fos, a component of the AP-1 transcription factor. Using mouse models, we show that hepatocyte-specific deletion of c-Fos protects against diethylnitrosamine (DEN)-induced HCCs, whereas liver-specific c-Fos expression leads to reversible premalignant hepatocyte transformation and enhanced DEN-carcinogenesis. c-Fos–expressing livers display necrotic foci, immune cell infiltration, and altered hepatocyte morphology. Furthermore, increased proliferation, dedifferentiation, activation of the DNA damage response, and gene signatures of aggressive HCCs are observed. Mechanistically, c-Fos decreases expression and activity of the nuclear receptor LXRα, leading to increased hepatic cholesterol and accumulation of toxic oxysterols and bile acids. The phenotypic consequences of c-Fos expression are partially ameliorated by the anti-inflammatory drug sulindac and largely prevented by statin treatment. An inverse correlation between c-FOS and the LXRα pathway was also observed in human HCC cell lines and datasets. These findings provide a novel link between chronic inflammation and metabolic pathways important in liver cancer.

Remote Sensing between Liver and Intestine: Importance of Microbial Metabolites

Recent technological advancements including metagenomics sequencing and metabolomics have allowed the discovery of critical functions of gut microbiota in obesity, malnutrition, neurological disorders, asthma, and xenobiotic metabolism. Classification of the human gut microbiome into distinct "enterotypes" has been proposed to serve as a new paradigm for understanding the interplay between microbial variation and human disease phenotypes, as many organs are affected by gut microbiota modifications during the pathogenesis of diseases. Gut microbiota remotely interacts with liver and other metabolic organs of the host through various microbial metabolites that are absorbed into the systemic circulation.

PURPOSE OF REVIEW

The present review summarizes recent literature regarding the importance of gut microbiota in modulating the physiological and pathological responses of various host organs, and describes the functions of the known microbial metabolites that are involved in this remote sensing process, with a primary focus on the gut microbiota-liver axis.

RECENT FINDINGS

Under physiological conditions, gut microbiota modulates the hepatic transcriptome, proteome, and metabolome, most notably down-regulating cytochrome P450 3a mediated xenobiotic metabolism. Gut microbiome also modulates the rhythmicity in liver gene expression, likely through microbial metabolites, such as butyrate and propionate that serve as epigenetic modifiers. Additionally, the production of host hormones such as primary bile acids and glucagon like peptide 1 is altered by gut microbiota to modify intermediary metabolism of the host.

SUMMARY

Dysregulation of gut microbiota is implicated in various liver diseases such as alcoholic liver disease, non-alcoholic steatohepatitis, liver cirrhosis, cholangitis, and liver cancer. Gut microbiota modifiers such as probiotics and prebiotics are increasingly recognized as novel therapeutic modalities for liver and other types of human diseases.

Glutamine attenuates obstructive cholestasis in rats via farnesoid X receptor–mediated regulation of Bsep and Mrp2

To investigate the protective effect of glutamine (Gln) against obstructive cholestasis in association with farnesoid X receptor (FXR) activation, an obstructive cholestasis model was established in male Sprague–Dawley rats by bile duct ligation (BDL). Serum biomarkers and hematoxylin plus eosin staining were used to identify the degree of hepatic injury in the rats with obstructive cholestasis after Gln treatment. Immunohistochemistry, real-time PCR, Western blot, cultured primary rat hepatocytes with FXR knockdown, and dual-luciferase reporter assay were performed to elucidate the mechanisms underlying Gln hepatoprotection. We found that Gln treatment protected against obstructive cholestasis induced by BDL through reducing hepatocyte injury. Upregulation of the hepatic efflux transporters small heterodimer partner (Shp), bile salt export pump (Bsep), and multidrug resistance–associated protein 2 (Mrp2), and inhibition of the hepatic uptake transporter Na+/taurocholate cotransporting polypeptide (Ntcp) and the bile acid synthesis enzyme cholesterol 7α-hydroxylase (Cyp7a1) expression were observed in rats with BDL treated with Gln in vivo. Furthermore, the regulatory effect of Gln on Bsep and Mrp2 expression was abrogated after FXR knockdown in rat primary cultured hepatocytes. Luciferase assay HepG2 cells also illustrated FXR was a direct target for Gln treatment. In conclusion, the regulation of Bsep and Mrp2 expression mediated by FXR might be an important mechanism for Gln against obstructive cholestasis.

Simvastatin promotes NPC1-mediated free cholesterol efflux from lysosomes through CYP7A1/LXRα signalling pathway in oxLDL-loaded macrophages

Statins, 3‐hydroxyl‐3‐methylglutaryl coenzyme A reductase inhibitors, are the first‐line medications prescribed for the prevention and treatment of coronary artery diseases. The efficacy of statins has been attributed not only to their systemic cholesterol‐lowering actions but also to their pleiotropic effects that are unrelated to cholesterol reduction. These pleiotropic effects have been increasingly recognized as essential in statins therapy. This study was designed to investigate the pleiotropic actions of simvastatin, one of the most commonly prescribed statins, on macrophage cholesterol homeostasis with a focus on lysosomal free cholesterol egression. With simultaneous nile red and filipin staining, analysis of confocal/multi‐photon imaging demonstrated that simvastatin markedly attenuated unesterified (free) cholesterol buildup in macrophages loaded with oxidized low‐density lipoprotein but had little effect in reducing the sizes of cholesteryl ester‐containing lipid droplets; the reduction in free cholesterol was mainly attributed to decreases in lysosome‐compartmentalized cholesterol. Functionally, the egression of free cholesterol from lysosomes attenuated pro‐inflammatory cytokine secretion. It was determined that the reduction of lysosomal free cholesterol buildup by simvastatin was due to the up‐regulation of Niemann‐Pick C1 (NPC1), a lysosomal residing cholesterol transporter. Moreover, the enhanced enzymatic production of 7‐hydroxycholesterol by cytochrome P450 7A1 and the subsequent activation of liver X receptor α underscored the up‐regulation of NPC1. These findings reveal a novel pleiotropic effect of simvastatin in affecting lysosomal cholesterol efflux in macrophages and the associated significance in the treatment of atherosclerosis.