Protective effects of SRT1720 via the HNF1α/FXR signalling pathway and anti-inflammatory mechanisms in mice with estrogen-induced cholestatic liver injury

Involvement of SIRT1-mediated aging in liver diseases

Liver disease is a significant global health issue, responsible for millions of deaths annually. Aging, characterized by the gradual decline in cellular and physiological functions, impairs tissue regeneration, increases susceptibility to liver diseases, and leads to a decline in liver health. Silent information regulator 1 (SIRT1), a NAD⁺-dependent deacetylase, has emerged as a pivotal factor in modulating age-related changes in the liver. SIRT1 preserves liver function by regulating essential aging-related pathways, including telomere maintenance, epigenetic modifications, cellular senescence, intercellular communication, inflammation, and mitochondrial function. Notably, SIRT1 levels naturally decline with age, contributing to liver disease progression and increased vulnerability to injury. This review summarizes the regulatory role of SIRT1 in aging and its impact on liver diseases such as liver fibrosis, alcoholic associated liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD), and metabolic dysfunction-associated steatohepatitis (MASH), hepatocellular carcinoma (HCC). We also discuss emerging therapeutic approaches, including SIRT1 activators, gene therapy, and nutritional interventions, which are evaluated for their potential to restore SIRT1 function and mitigate liver disease progression. Finally, we highlight future research directions to optimize SIRT1-targeted therapies for clinical applications in age-related liver conditions.

Role of gut microbiota and fecal metabolites in the protective effect of soybean pulp-rich diet against estrogen-induced cholestasis in rats

This study was designed to explore the role of gut microbiota and its metabolites in the treatment of estrogen-induced cholestasis (EIC) in rats with a soybean pulp-rich diet and to clarify the effects of daidzein (DAI), a principal active ingredient of soybean pulp. The findings demonstrated that the soybean pulp-rich diet could relieve cholestasis by decreasing the levels of total bile acids (TBA) and alkaline phosphatase and enhancing the bile flow rate. Through gut microbiota and metabolomics analyses, it was revealed that this diet might alter the abundances of certain bacterial taxa including Akkermansia, Bacteroides, and Turicibacter, thus influencing lipid metabolism, tryptophan metabolism, and steroid metabolism, which led to disparities between the groups fed with and without the soybean pulp-rich diet. Moreover, the soybean pulp-rich diet could modulate the abundances of Prevotella spp. and Tyzzerella, reducing EIC by regulating lipid metabolism and short-chain fatty acids synthesis. Notably, DAI treatment significantly alleviated the abnormalities in serum TBA, alanine aminotransferase, and aspartate aminotransferase levels and mitigated the liver tissue damage in the EIC model. In summary, during cholestasis, variations in gut microbiota and metabolite profiles occurred. The intervention of soybean pulp affected the abundances of bacteria (such as Prevotella spp. and Tyzzerella) and regulated lipid metabolism-related pathways. Importantly, DAI was identified as a crucial component for the protective effects associated with the soybean pulp diet.

Protective effects of cilostazol via the HNF1α/FXR signalling pathway and anti-apoptotic mechanisms in a rat model of estrogen-induced intrahepatic cholestasis

Currently, there is a lack of targeted medications for estrogen-induced intrahepatic cholestasis (EIC) and the primary objective in managing this condition is to safeguard liver function. Consequently, this study was conducted to examine the pharmacological efficacy of cilostazol (CTZ) in the management of EIC and explore its underlying mechanisms through the use of an animal model. Thirty female Sprague-Dawley rats were divided into five groups of six animals each: Normal group, 17-ethinylestradiol (EE)-induced intrahepatic cholestasis group, EE + ursodeoxycholic acid (UDCA)-treated group, EE + CTZ (5 mg/kg)-treated group, and EE + CTZ (10 mg/kg)-treated group. It was found that the therapeutic efficacy of UDCA and low dosage of CTZ (5 mg/kg) was comparable. Nevertheless, when CTZ was administered at a dose of 10 mg/kg, it resulted in the normalization of all liver function parameters, oxidative stress, and pro-inflammatory markers, together with improvement in the histopathological derangements and hepatocytic apoptosis. These effects were mediated through the activation of the hepatocyte nuclear factor-1 alpha (HNF1α)/Farnesoid X receptor (FXR) pathway with subsequent down-regulation of the bile acids (BAs) synthesis enzyme; cholesterol 7α-hydroxylase (CYP7A1), and up-regulation of the BAs-metabolizing enzyme; cytochrome P450 (CYP)3A1 and the bile salt export pump; BSEP. Therefore, the administration of CTZ in a dose-dependent manner can protect against EIC through regulating the HNF1α/FXR pathway and anti-apoptotic mechanisms. This implies that CTZ exhibits considerable promise as a therapeutic agent for the treatment of cholestatic liver disorders.

Role of sodium taurocholate cotransporting polypeptide (NTCP) in HBV-induced hepatitis: Opportunities for developing novel therapeutics

Hepatitis B is an infectious disease caused by the HBV virus. It presents a significant challenge for treatment due to its chronic nature and the potential for developing severe complications, including hepatocirrhosis and hepatocellular carcinoma. These complications not only cause physical and psychological distress to patients but also impose substantial economic and social burdens on both individuals and society as a whole. The internalization of HBV relies on endocytosis and necessitates the involvement of various proteins, including heparin sulfate proteoglycans, epidermal growth factor receptors, and NTCP. Among these proteins, NTCP is pivotal in HBV internalization and is primarily located in the liver's basement membrane. As a transporter of bile acids, NTCP also serves as a receptor facilitating HBV entry into cells. Numerous molecules have been identified to thwart HBV infection by stifling NTCP activity, although only a handful exhibit low IC50 values. In this systematic review, our primary focus dwells on the structure and regulation of NTCP, as well as the mechanism involved in HBV internalization. We underscore recent drug breakthroughs that specifically target NTCP to combat HBV infection. By shedding light on these advances, this review contributes novel insights into developing effective anti-HBV medications.

Sex-Dependent Differences in Cholestasis: Why Estrogen Signaling May Be a Key Pathophysiological Driver

Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are cholestatic liver diseases that have significant clinical impact with debilitating symptoms and mortality. While PBC is predominantly seen in perimenopausal and postmenopausal women, men who are diagnosed with PBC have worse clinical outcomes and all-cause mortality. In contrast, 60% to 70% of patients with PSC are men; the data indicate that female sex may be an independent factor against PSC-related complications. These findings suggest a sex-dependent biological basis for these differences. Estrogen has been implicated in the pathogenesis of intrahepatic cholestasis of pregnancy and may induce cholestasis through a variety of interactions. However, it is unclear why some sexual dimorphic features may provide a protective effect despite known estrogen models that induce cholestasis. This article provides a brief introductory background and discusses the sexual dimorphism in clinical presentation in PSC and PBC. It also explores the role of estrogen signaling in pathogenesis and how it relates to intrahepatic cholestasis of pregnancy. Studies have already targeted certain molecules involved in estrogen signaling, and this review discusses these studies that identify estrogen-related receptor, estrogen receptor-α, estrogen receptor-β, farnesoid X receptor, and mast cells as possible targets, in addition to long noncoding RNA H19-induced cholestasis and sexual dimorphism. It also explores these interactions and their role in the pathogenesis of PBC and PSC.

Geniposide alleviated bile acid-associated NLRP3 inflammasome activation by regulating SIRT1/FXR signaling in bile duct ligation-induced liver fibrosis

BACKGROUND

Geniposide (GE), the active compound derived from Gardeniae Fructus, possesses valuable bioactivity for liver diseases, but GE effects on bile duct ligation (BDL)-induced cholestasis remain unclear. This study aimed to elucidate the influence of GE on BDL-induced liver fibrosis and to investigate the underlying mechanisms.

METHODS

GE (25 or 50 mg/kg) were intragastrical administered to C57BL/6 J mice for two weeks to characterize the hepatoprotective effect of GE on BDL-induced liver fibrosis. NLRP3 inflammasome activation was detected in vivo, and BMDMs were isolated to explore whether GE directly inhibited NLRP3 inflammasome activation. Serum bile acid (BA) profiles were assessed utilizing UPLC-MS/MS, and the involvement of SIRT1/FXR pathways was identified to elucidate the role of SIRT1/FXR in the hepaprotective effect of GE. The veritable impact of SIRT1/FXR signaling was further confirmed by administering the SIRT1 inhibitor EX527 (10 mg/kg) to BDL mice treated with GE.

RESULTS

GE treatment protected mice from BDL-induced liver fibrosis, with NLRP3 inflammasome inhibition. However, development in vitro experiments revealed that GE could not directly inhibit NLRP3 activation under ATP, monosodium urate, and nigericin stimulation. Further mechanistic data showed that GE activated SIRT1, which subsequently deacetylated FXR and restored CDCA, TUDCA, and TCDCA levels, thereby contributing to the observed hepaprotective effect of GE. Notably, EX527 treatment diminished the hepaprotective effect of GE on BDL-induced liver fibrosis.

CONCLUSION

This study first proved the hepaprotective effect of GE on liver fibrosis in BDL mice, which was closely associated with the restoration of BA homeostasis and NLRP3 inflammasome inhibition. The activation of SIRT1 and the subsequent FXR deacetylation restored the BA profiles, especially CDCA, TUDCA, and TCDCA contents, which was the main contributor to NLRP3 inhibition and the hepaprotective effect of GE. Overall, our work provides novel insights that GE as well as Gardeniae Fructus might be the potential attractive candidate for ameliorating BDL-induced liver fibrosis.

Suppression of SIRT1/FXR signaling pathway contributes to oleanolic acid-induced liver injury

Oleanolic acid (OA) is a pentacyclic triterpenoid compound used clinically for acute and chronic hepatitis. However, high dose or long-term use of OA causes hepatotoxicity, which limits its clinical application. Hepatic Sirtuin (SIRT1) participates in the regulation of FXR signaling and maintains hepatic metabolic homeostasis. This study was designed to determine whether SIRT1/FXR signaling pathway contributes to the hepatotoxicity caused by OA. C57BL/6J mice were administered with OA for 4 consecutive days to induce hepatotoxicity. The results showed that OA suppressed the expression of FXR and its downstream targets CYP7A1, CYP8B1, BSEP and MRP2 at both mRNA and protein levels, breaking the homeostasis of bile acid leading to hepatotoxicity. However, treatment with FXR agonist GW4064 noticeably attenuated hepatotoxicity caused by OA. Furthermore, it was found that OA inhibited protein expression of SIRT1. Activation of SIRT1 by its agonist SRT1720 significantly improved OA-induced hepatotoxicity. Meanwhile, SRT1720 significantly reduced the inhibition of protein expression of FXR and FXR-downstream proteins. These results suggested that OA may cause hepatotoxicity through SIRT1 dependent suppression of FXR signaling pathway. In vitro experiments confirmed that OA suppressed protein expressions of FXR and its targets through inhibition of SIRT1. It was further revealed that silencing of HNF1α with siRNA significantly weakened regulatory effects of SIRT1 on the expression of FXR as well as its target genes. In conclusion, our study reveals that SIRT1/FXR pathway is crucial in OA-induced hepatotoxicity. Activation of SIRT1/HNF1α/FXR axis may represent a novel therapeutic target for ameliorating OA and other herb-induced hepatotoxicity.

iNKT17 cells play a pathogenic role in ethinylestradiol-induced cholestatic hepatotoxicity

IL-17 is closely associated with inflammation in intrahepatic cholestasis (IHC). Targeting IL-17 ameliorates IHC in mice. Invariant natural killer T (iNKT) cells are predominantly enriched in the liver and they mediate drug-induced liver injury through their secreted cytokines. However, whether iNKT17 cells are involved in ethinylestradiol (EE)-induced IHC remains unclear. In the present study, the administration of EE (10 mg/kg in vivo and 6.25 μM in vitro) promoted the activation and expansion of iNKT17 cells, which contributed to a novel hepatic iNKT17/Treg imbalance. iNKT cell-deficient Jα18-/- mice and the RORγt inhibitor digoxin (20 μg) alleviated EE-induced cholestatic hepatotoxicity and downregulated the IL-17 signalling pathway. In contrast, the co-administration of EE with recombinant IL-17 (1 μg) to Jα18-/- mice induced cholestatic hepatotoxicity and increased the infiltration of hepatic neutrophils and monocytes. Importantly, the administration of IL-17-/- iNKT cells (3.5 × 105) to Jα18-/- mice resulted in the attenuation of hepatotoxicity and the recruitment of fewer hepatic neutrophils and monocytes than the adoptive transfer of wild-type iNKT cells. These results indicated that iNKT17 cells could exert pathogenic effects. The recruitment and activation of iNKT17 cells could be attributed to the high level of CXCR3 expression on their surface. CXCL10 deficiency ameliorated EE-induced cholestatic liver damage, reduced hepatic CXCR3+ iNKT cells and inhibited RORγt expression. These findings suggest that iNKT17 cells play a key role in EE-induced cholestatic liver injury via CXCR3-mediated recruitment and activation. Our study provides new insights and therapeutic targets for cholestatic diseases.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Activation of natural killer T cells contributes to Th1 bias in the murine liver after 14 d of ethinylestradiol exposure

BACKGROUND

As the main component of oral contraceptives (OCs), ethinylestradiol (EE) has been widely applied as a model drug to induce murine intrahepatic cholestasis. The clinical counterpart of EE-induced cholestasis includes women who are taking OCs, sex hormone replacement therapy, and susceptible pregnant women. Taking intrahepatic cholestasis of pregnancy (ICP) as an example, ICP consumes the medical system due to its high-risk fetal burden and the impotency of ursodeoxycholic acid in reducing adverse perinatal outcomes.

AIM

To explore the mechanisms and therapeutic strategies of EE-induced cholestasis based on the liver immune microenvironment.

METHODS

Male C57BL/6J mice or invariant natural killer T (iNKT) cell deficiency (Jα18-/- mice) were administered with EE (10 mg/kg, subcutaneous) for 14 d.

RESULTS

Both Th1 and Th2 cytokines produced by NKT cells increased in the liver skewing toward a Th1 bias. The expression of the chemokine/chemokine receptor Cxcr6/Cxcl16, toll-like receptors, Ras/Rad, and PI3K/Bad signaling was upregulated after EE administration. EE also influenced bile acid synthase Cyp7a1, Cyp8b1, and tight junctions ZO-1 and Occludin, which might be associated with EE-induced cholestasis. iNKT cell deficiency (Jα18-/- mice) robustly alleviated cholestatic liver damage and lowered the expression of the abovementioned signaling pathways.

CONCLUSION

Hepatic NKT cells play a pathogenic role in EE-induced intrahepatic cholestasis. Our research improves the understanding of intrahepatic cholestasis by revealing the hepatic immune microenvironment and also provides a potential clinical treatment by regulating iNKT cells.

Regulation of the HBV Entry Receptor NTCP and its Potential in Hepatitis B Treatment

Hepatitis B virus (HBV) is a globally prevalent human DNA virus responsible for more than 250 million cases of chronic liver infection, a condition that can lead to liver inflammation, cirrhosis, and hepatocellular carcinoma. Sodium taurocholate co-transporting polypeptide (NTCP), a transmembrane protein highly expressed in human hepatocytes and a mediator of bile acid transport, has been identified as the receptor responsible for the cellular entry of both HBV and its satellite, hepatitis delta virus (HDV). This has led to significant advances in our understanding of the HBV life cycle, especially the early steps of infection. HepG2-NTCP cells and human NTCP-expressing transgenic mice have been employed as the primary cell culture and animal models, respectively, for the study of HBV, and represent valuable approaches for investigating its basic biology and developing treatments for infection. However, the mechanisms involved in the regulation of NTCP transcription, translation, post-translational modification, and transport are still largely elusive. Improvements in our understanding of NTCP biology would likely facilitate the design of new therapeutic drugs for the prevention of the de novo infection of naïve hepatocytes. In this review, we provide critical findings regarding NTCP biology and discuss important questions that remain unanswered.

Farnesoid X receptor (FXR) agonists induce hepatocellular apoptosis and impair hepatic functions via FXR/SHP pathway

Farnesoid X receptor (FXR) plays an indispensable role in liver homeostasis and has been a promising drug target for hepatic diseases. However, the concerns of undesired biological actions limit the clinical applications of FXR agonists. To reveal the intrinsic mechanism of FXR agonist-induce hepatotoxicity, two typical FXR agonists with different structures (obeticholic acid (OCA) and Px-102) were investigated in the present study. By detecting MMP, ROS, and ATP and analyzing the fate of cells, we found that both OCA and Px-102 reduced the mitochondrial function of hepatocytes and promoted cell apoptosis. Gene ablation or inhibition of FXR or SHP ameliorated the cytotoxicities of OCA and Px-102, which indicated the adverse actions of FXR/SHP activation including down-regulation of phosphorylation of PI3K/AKT and functional hepatic genes. The dose-related injurious effects of OCA (10 mg/kg and 30 mg/kg) and Px-102 (5 mg/kg and 15 mg/kg) on the liver were confirmed on a high-fat diet mouse model. The decrease of hepatocyte-specific genes and augmenter of liver regeneration in the liver caused by OCA or Px-102 suggested an imbalance of liver regeneration and a disruption of hepatic functions. Exploration of intestinally biased FXR agonists or combination of FXR agonist with apoptosis inhibitor may be more beneficial strategies for liver diseases.

The Pathological Mechanisms of Estrogen-Induced Cholestasis: Current Perspectives

Estrogens are steroid hormones with a wide range of biological activities. The excess of estrogens can lead to decreased bile flow, toxic bile acid (BA) accumulation, subsequently causing intrahepatic cholestasis. Estrogen-induced cholestasis (EIC) may have increased incidence during pregnancy, and within women taking oral contraception and postmenopausal hormone replacement therapy, and result in liver injury, preterm birth, meconium-stained amniotic fluid, and intrauterine fetal death in pregnant women. The main pathogenic mechanisms of EIC may include deregulation of BA synthetic or metabolic enzymes, and BA transporters. In addition, impaired cell membrane fluidity, inflammatory responses and change of hepatocyte tight junctions are also involved in the pathogenesis of EIC. In this article, we review the role of estrogens in intrahepatic cholestasis, and outlined the mechanisms of EIC, providing a greater understanding of this disease.

Metformin impairs bile acid homeostasis in ethinylestradiol-induced cholestasis in mice

Metformin, an oral antidiabetic drug, recently demonstrated a reducing effect on bile acids (BA) plasma concentrations in one patient with intrahepatic cholestasis of pregnancy (ICP) by unknown mechanism. Therefore, the aim of the present study was to examine the effect of metformin on BA homeostasis and related molecular pathways in the liver and intestine using a mouse model of ICP. The cholestasis was induced in female C57BL/6 mice by repeated administration of ethinylestradiol (10 mg/kg BW s.c.) and/or metformin (150 mg/kg BW orally) over 5 consecutive days with subsequent bile collection and molecular analysis of samples. We demonstrated that metformin significantly increased the rate of bile secretion in control mice. This increase was BA dependent and was produced both by increased liver BA synthesis via induced cholesterol 7α-hydroxylase (Cyp7a1) and by increased BA reabsorption in the ileum via induction of the apical sodium-dependent BA transporter (Asbt). In contrast, metformin further worsened ethinylestradiol-induced impairment of bile secretion. This reduction was also BA dependent and corresponded with significant downregulation of Bsep, and Ntcp, major excretory and uptake transporters for BA in hepatocytes, respectively. The plasma concentrations of BA were consequently significantly increased in the metformin-treated mice. Altogether, our data indicate positive stimulation of bile secretion by metformin in the intact liver, but this drug also induces serious impairment of BA biliary secretion, with a marked increase in plasma concentrations in estrogen-induced cholestasis. Our results imply that metformin should be used with caution in situations with hormone-dependent cholestasis, such as ICP.

Effect of fucoidan on ethanol-induced liver injury and steatosis in mice and the underlying mechanism

BACKGROUND

Alcoholic liver disease is caused as a result of chronic alcohol consumption. In this study, we used an alcoholic liver injury mouse model to investigate the effect of fucoidan on ethanol-induced liver injury and steatosis and the underlying mechanisms.

METHODS

All mice were randomly divided into four groups: 1) control group, 2) model group, 3) diammonium glycyrrhizinate treatment group (200 mg/kg body weight), and 4) fucoidan treatment group (300 mg/kg body weight). Administration of ethanol for 8 weeks induced liver injury and steatosis in mice.

RESULTS

Fucoidan treatment decreased serum alanine aminotransferase activity, serum total cholesterol levels, and hepatic triglyceride levels, and improved the morphology of hepatic cells. Fucoidan treatment upregulated the expression of AMPKα1, SIRT1, and PGC-1α and inhibited the expression of ChREBP and HNF-1α. The levels of hepatic IL-6 and IL-18 were significantly decreased in the fucoidan group. Further, the levels of cytochrome P450-2E1 (CYP2E1), glucose-regulated protein (GRP) 78, and 3-nitrotyrosine (3-NT) in hepatic tissues were reduced in the fucoidan group as compared to the model group. Fucoidan significantly reversed the reduction of ileac Farnesoid X receptor (FXR) and fibroblast growth factor 15 (FGF15) levels induced by alcohol-feeding and reduced CYP7A1 (cholesterol 7α-hydroxylase) expression and total bile acid levels in the liver tissue. In addition, fucoidan regulated the structure of gut flora, with increased abundance of Prevotella and decreased abundance of Paraprevotella and Romboutsia as detected by 16S rDNA high-throughput sequencing.

CONCLUSION

Fucoidan inhibited alcohol-induced steatosis and disorders of bile acid metabolism in mice through the AMPKα1/SIRT1 pathway and the gut microbiota-bile acid-liver axis and protected against alcohol-induced liver injury in vivo.

An insight into the mechanism and molecular basis of dysfunctional immune response involved in cholestasis

Cholestasis is one of the most common clinical symptom of liver diseases. If patients do not receive effective treatment, cholestasis can evolve into liver fibrosis, cirrhosis and ultimately liver failure requiring liver transplantation. Currently, only ursodeoxycholic acid, obeticholic acid and bezafibrate are FDA-approved drugs, thereby requiring a breakthrough in new mechanisms and therapeutic development. Inflammation is one of the common complications of cholestasis. Hepatic accumulation of toxic hydrophobic bile acids is a highly immunogenic process involving both resident and immigrating immune cells. And the resulting inflammation may further aggravate hepatocyte injury. Though, great investigations have been made in the immune responses during cholestasis, the relationship between immune responses and cholestasis remains unclear. Moreover, scarce reviews summarize the immune responses during cholestasis and the efficacy of therapies on immune response. The main purpose of this paper is to review the existing literature on dysfunctional immune response during cholestasis and the effect of treatment on immune response which may provide an insight for researchers and drug development.

The road ahead for health and lifespan interventions

Aging is a modifiable risk factor for most chronic diseases and an inevitable process in humans. The development of pharmacological interventions aimed at delaying or preventing the onset of chronic conditions and other age-related diseases has been at the forefront of the aging field. Preclinical findings have demonstrated that species, sex and strain confer significant heterogeneity on reaching the desired health- and lifespan-promoting pharmacological responses in model organisms. Translating the safety and efficacy of these interventions to humans and the lack of reliable biomarkers that serve as predictors of health outcomes remain a challenge. Here, we will survey current pharmacological interventions that promote lifespan extension and/or increased healthspan in animals and humans, and review the various anti-aging interventions selected for inclusion in the NIA's Interventions Testing Program as well as the ClinicalTrials.gov database that target aging or age-related diseases in humans.

Picroside II protects against cholestatic liver injury possibly through activation of farnesoid X receptor

BACKGROUD

Cholestasis, accompanied by the accumulation of bile acids in body, may ultimately cause liver failure and cirrhosis. There have been limited therapies for cholesteric disorders. Therefore, development of appropriate therapeutic drugs for cholestasis is required. Picroside II is a bioactive component isolated from Picrorhiza scrophulariiflora Pennell, its mechanistic contributions to the anti-cholestasis effect have not been fully elucidated, especially the role of picroside II on bile acid homeostasis via nuclear receptors remains unclear.

PURPOSE

This study was designed to investigate the hepatoprotective effect of picroside II against alpha-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury and elucidate the mechanisms in vivo and in vitro.

METHODS

The ANIT-induced cholestatic mouse model was used with or without picroside II treatment. Serum and bile biochemical indicators, as well as liver histopathological changes were examined. siRNA, Dual-luciferase reporter, quantitative real-time PCR and Western blot assay were used to demonstrate the farnesoid X receptor (FXR) pathway in the anti-cholestasis effects of picroside II in vivo and in vitro.

RESULTS

Picroside II exerted hepatoprotective effect against ANIT-induced cholestasis by impaired hepatic function and tissue damage. Picroside II increased bile acid efflux transporter bile salt export pump (Bsep), uptake transporter sodium taurocholate cotransporting polypeptide (Ntcp), and bile acid metabolizing enzymes sulfate transferase 2a1 (Sult2a1) and UDP-glucuronosyltransferase 1a1 (Ugt1a1), whereas decreased the bile acid synthesis enzymes cholesterol 7α-hydroxylase (Cyp7a1) and oxysterol 12α-hydroxylase (Cyp8b1). In addition, expression of FXR and the target gene Bsep was increased, whereas aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR), peroxisome proliferator-activated receptor alpha (PPARα) and their corresponding target genes were not significantly influenced by picroside II under cholestatic conditions. Furthermore, regulation of transporters and enzymes involved in bile acid homeostasis by picroside II were abrogated by FXR silencing in mouse primary cultured hepatocytes. Dual-luciferase reporter assay performed in HepG2 cells demonstrated FXR activation by picroside II.

CONCLUSION

Our findings demonstrate that picroside II exerts protective effect on ANIT-induced cholestasis possibly through FXR activation that regulates the transporters and enzymes involved in bile acid homeostasis. Picroside II might be an effective approach for the prevention and treatment of cholestatic liver diseases.

Baicalin Protects Against 17α-Ethinylestradiol-Induced Cholestasis via the Sirtuin 1/Hepatic Nuclear Receptor-1α/Farnesoid X Receptor Pathway

Estrogen-induced cholestasis (EIC) is characterized by impairment of bile flow and accumulated bile acids (BAs) in the liver, always along with the liver damage. Baicalin is a major flavonoid component of Scutellaria baicalensis, and has been used in the treatment of liver diseases for many years. However, the role of baicalin in EIC remains to be elucidated. In this study, we demonstrated that baicalin showed obvious hepatoprotective effects in EIC rats by reducing serum biomarkers and increasing the bile flow rate, as well as by alleviating liver histology and restoring the abnormal composition of hepatic BAs. In addition, baicalin protected against estrogen-induced liver injury by up-regulation of the expression of hepatic efflux transporters and down-regulation of hepatic uptake transporters. Furthermore, baicalin increased the expression of hepatic BA synthase (CYP27A1) and metabolic enzymes (Bal, Baat, Sult2a1) in EIC rats. We showed that baicalin significantly inhibited hepatic inflammatory responses in EIC rats through reducing elevated levels of TNF-α, IL-1β, IL-6, and NF-κB. Finally, we confirmed that baicalin maintains hepatic BA homeostasis and alleviates inflammation through sirtuin 1 (Sirt1)/hepatic nuclear receptor-1α (HNF-1α)/farnesoid X receptor (FXR) signaling pathway. Thus, baicalin protects against estrogen-induced cholestatic liver injury, and the underlying mechanism involved is related to activation of the Sirt1/HNF-1α/FXR signaling pathway.

The Beneficial Roles of SIRT1 in Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is a major cause of acute liver failure (ALF) as a result of accumulated drugs in the human body metabolized into toxic agents and helps generate heavy oxidative stress, inflammation, and apoptosis, which induces necrosis in hepatocytes and ultimately damages the liver. Sirtuin 1 (SIRT1) is said to have multiple vital roles in cell proliferation, aging, and antistress systems of the human body. The levels of SIRT1 and its activation precisely modulate its critical role in the interaction between multiple step procedures of DILI. The nuclear factor kappa-light-chain-enhancer of activated B cell- (NF-κB-) mediated inflammation signaling pathway, reactive oxygen species (ROS), DNA damage, mitochondrial membrane potential collapse, and endoplasmic reticulum (ER) stress also contribute to aggravate DILI. Apoptosis is regarded as the terminal reaction followed by multiple signaling cascades including caspases, p53, and mitochondrial dysfunction which have been said to contribute in DILI. The SIRT1 activator is regarded as a potential candidate for DILI, because the former could inhibit signaling of p53, NF-κB, and ER stress. On the other hand, overexpression of SIRT1 also enhances the activation of antioxidant responses via Kelch-like ECH-associated protein 1- (Keap1-) nuclear factor- (erythroid-derived 2-) like 2 (Nrf2) signaling. The current manuscript will highlight the mechanism of DILI and the interaction of SIRT1 with various cytoplasmic factors leading to DILI along with the summary of potent SIRT1 agonists.

Hepatoprotective potential of standardized Ficus species in intrahepatic cholestasis rat model: Involvement of nuclear factor-κB, and Farnesoid X receptor signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Ficus is an important commercial crop not only for its nutritive value but also, for its medicinal value. Several Ficus species have been traditionally used in the Egypt, Indian and Chinese as carminative, astringent, antibacterial, hepatoprotective, and hypolipidemic agents.

AIM OF THE STUDY

To standardize and compare the possible hepatoprotective potential of the ethanolic extract of leaves of five tested Ficus species namely: Ficus mysorensis Roth ex Roem. & Schult, Ficus pyriformis Hook. & Arn., Ficus auriculata Lour., Ficus trigonata L., and Ficus spragueana Mildbr. & Burret in the intrahepatic cholestasis rat model induced by 17α-Ethinylestradiol (EE) and to explore the mechanism of action with respect to their phytochemical constituents.

MATERIALS AND METHODS

Determination of the total phenolic and flavonoid contents, chromatographic examination and acute oral toxicity test were performed on the tested Ficus extracts. Animals were divided into 8 groups. Group 1, served as control for 2 weeks. Group 2, untreated cholestatic rats. Groups 3-8, pretreated with Ficus extracts (100 mg/Kg/day, p.o) or ursodeoxycholic acid (as reference drug) for 2 weeks and injected by EE in the last 5 days. Serum liver function test, 5'-nucleotidase (5'-N), total bile acids (TBA), total cholesterol (T.C) and phospholipids were assayed. Also, hepatic Na⁺/K⁺-ATPase, nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), hepatocyte growth factor (HGF), hemeoxygenase-1 (HO-1), and markers of oxidative stress were investigated. Furthermore, molecular docking study was performed to explore the ability of the major constituents of Ficus to interact with Farnesoid X receptor (FXR).

RESULTS

Four phenolic compounds (gallic, chlorogenic acid, caffeic acids and rutin) were identified. Chlorogenic acid and rutin represented the major constituents of Ficus extracts. Simultaneous administration of Ficus extracts with EE effectively: i- preserved liver function, TBA, T.C and phospholipids, ii- suppressed the pro-inflammatory cytokines (NF-κB and TNF-α), iii- enhanced hepatic regeneration (HGF) and antioxidant defense system. Furthermore, molecular docking reveals that rutin and chlorogenic acid effectively act as FXR agonists.

CONCLUSION

Among the tested extracts, Ficus spragueana Mildbr. & Burret enriched with phenolics exhibited a pronounced hepatoprotective activity and may provide a new therapeutic approach for estrogen-induced cholestasis.

Anti-inflammatory, anti-oxidative stress and novel therapeutic targets for cholestatic liver injury

Cholestasis is a pathological process in which bile drainage is poor for a variety of reasons. Many studies have shown that cholestatic liver injury is a neutrophil-mediated inflammatory response, and oxidative stress induced by neutrophils is the main mechanism of liver cell death. The literature summarizes the bile acid signaling pathway, the neutrophil chemotaxis recruitment process during cholestasis, and the oxidative stress damage produced by neutrophil activation, summarizes the latest research progress. Sphingosine-1-phosphate receptor (S1PR) is a potential therapeutic target for cholestasis that reduces neutrophil aggregation without inhibiting systemic immune status. Early growth response factor 1 (Egr-1) may play a central role in the inflammation induced by cholestasis, and it is also a potential therapeutic target to inhibit the inflammation induced by cholestasis. Strengthening the antioxidant system of hepatocytes to cope with oxidative stress of neutrophils is a feasible treatment for cholestatic liver injury.

Calculus Bovis Sativus Improves Bile Acid Homeostasis via Farnesoid X Receptor-Mediated Signaling in Rats With Estrogen-Induced Cholestasis

Cholestatic diseases are characterized by toxic bile acid (BA) accumulation, and abnormal BA composition, which subsequently lead to liver injury. Biochemical synthetic Calculus Bovis Sativus (CBS) is derived from natural Calculus Bovis, a traditional Chinese medicine, which has been used to treat hepatic diseases for thousands of years. Although it has been shown that CBS administration to 17α-ethinylestradiol (EE)-induced cholestatic rats improves bile flow and liver injury, the involved underlying mechanism is largely unknown. In this study, we showed that CBS administration to EE-induced cholestatic rats significantly decreased serum and hepatic BA levels and reversed hepatic BA composition. DNA microarray analysis suggested that the critical pathways enriched by CBS treatment were bile secretion and primary BA synthesis. These findings led us to focus on the effects of CBS on regulating BA homeostasis, including BA transport, synthesis and metabolism. CBS enhanced hepatic BA secretion by inducing efflux transporter expression and inhibiting uptake transporter expression. Moreover, CBS reduced BA synthesis by repressing the expression of BA synthetic enzymes, CYP7A1 and CYP8B1, and increased BA metabolism by inducing the expression of metabolic enzymes, CYP3A2, CYP2B10, and SULT2A1. Mechanistic studies indicated that CBS increased protein expression and nuclear translocation of hepatic and intestinal farnesoid X receptor (FXR) to regulate the expression of these transporters and enzymes. We further demonstrated that beneficial effects of CBS administration on EE-induced cholestatic rats were significantly blocked by guggulsterone, a FXR antagonist. Therefore, CBS improved BA homeostasis through FXR-mediated signaling in estrogen-induced cholestatic rats. Together, these findings suggested that CBS might be a novel and potentially effective drug for the treatment of cholestasis.

Hepatoprotection of auraptene from the peels of citrus fruits against 17α-ethinylestradiol-induced cholestasis in mice by activating farnesoid X receptor

Auraptene protects against estrogen-induced cholestasis in mice.

Intraperitoneal injection of the SIRT1 activator SRT1720 attenuates the progression of experimental osteoarthritis in mice

Objectives

This study aimed to examine the effects of SRT1720, a potent SIRT1 activator, on osteoarthritis (OA) progression using an experimental OA model.

Methods

Osteoarthritis was surgically induced by destabilization of the medial meniscus in eight-week-old C57BL/6 male mice. SRT1720 was administered intraperitoneally twice a week after surgery. Osteoarthritis progression was evaluated histologically using the Osteoarthritis Research Society International (OARSI) score at four, eight, 12 and 16 weeks. The expression of SIRT1, matrix metalloproteinase 13 (MMP-13), a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), cleaved caspase-3, PARP p85, and acetylated nuclear factor (NF)-κB p65 in cartilage was examined by immunohistochemistry. Synovitis was also evaluated histologically. Primary mouse epiphyseal chondrocytes were treated with SRT1720 in the presence or absence of interleukin 1 beta (IL-1β), and gene expression changes were examined by real-time polymerase chain reaction (PCR).

Results

The OARSI score was significantly lower in mice treated with SRT1720 than in control mice at eight and 12 weeks associated with the decreased size of osteophytes at four and eight weeks. The delayed OA progression in the mice treated with SRT1720 was also associated with increased SIRT1-positive chondrocytes and decreased MMP-13-, ADAMTS-5-, cleaved caspase-3-, PARP p85-, and acetylated NF-κB p65-positive chondrocytes and decreased synovitis at four and eight weeks. SRT1720 treatment partially rescued the decreases in collagen type II alpha 1 (COL2A1) and aggrecan caused by IL-1β, while also reducing the induction of MMP-13 by IL-1β in vitro.

Conclusion

The intraperitoneal injection of SRT1720 attenuated experimental OA progression in mice, indicating that SRT1720 could be a new therapeutic approach for OA.Cite this article: K. Nishida, T. Matsushita, K. Takayama, T. Tanaka, N. Miyaji, K. Ibaraki, D. Araki, N. Kanzaki, T. Matsumoto, R. Kuroda. Intraperitoneal injection of the SIRT1 activator SRT1720 attenuates the progression of experimental osteoarthritis in mice. Bone Joint Res 2018;7:252-262. DOI: 10.1302/2046-3758.73.BJR-2017-0227.R1.

Integrating Drug's Mode of Action into Quantitative Structure-Activity Relationships for Improved Prediction of Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is complex in mechanism. Different drugs could undergo different mechanisms but result in the same DILI type, while the same drug could lead to different DILI types via different mechanisms. Therefore, predicting a drug's potential for DILI should take its underlying mechanisms into consideration. To achieve that, we constructed a novel approach by incorporating the drug's Mode of Action (MOA) into Quantitative Structure-Activity Relationship (QSAR) modeling. This MOA-DILI approach was examined using a data set of 333 drugs. The drugs were first grouped according to their MOA profiles (positive or negative in each MOA) based on the Tox21 qHTS assays. QSAR models for individual MOA assays were developed and subsequently combined to obtain the MOA-DILI model. A hold-out testing strategy (222 drugs for training and 111 drugs as a test set) was employed, which yielded a predictive accuracy of 0.711. The MOA-DILI model was directly compared with the standard QSAR approach using the same hold-out strategy, and the QSAR model yielded an accuracy of 0.662. To minimize the random chance in splitting training/test sets, the hold-out testing process was repeated 1000 times, and the observed difference in prediction accuracy between MOA-DILI and QSARs was statistically significant (P value <0.0001). Out of 17 MOAs used, four assays (i.e., antioxidant response elements, PPAR-gamma, estrogen receptor, and thyroid receptor assays) contributed most to the improved prediction of the MOA-DILI model over QSARs. In conclusion, the MOA-DILI approach has the potential to significantly improve predictive outcomes and to reveal complex relationships between MOAs and DILI, all of which would be helpful in developing DILI predictive models in drug screening and for risk assessment of industrial chemicals.