Asking the Right Questions With Animal Models: Methionine- and Choline-Deficient Model in Predicting Adverse Drug Reactions in Human NASH

Unravelling the complexities of non-alcoholic steatohepatitis: The role of metabolism, transporters, and herb-drug interactions

Nonalcoholic fatty liver disease (NAFLD) is a mainstream halting liver disease with high prevalence in North America, Europe, and other world regions. It is an advanced form of NAFLD caused by the amassing of fat in the liver and can progress to the more severe form known as non-alcoholic steatohepatitis (NASH). Until recently, there was no authorized pharmacotherapy reported for NASH, and to improve the patient's metabolic syndrome, the focus is mainly on lifestyle modification, weight loss, ensuring a healthy diet, and increased physical activity; however, the recent approval of Rezdiffra (Resmetirom) by the US FDA may change this narrative. As per the reported studies, there is an increased articulation of uptake and efflux transporters of the liver, including OATP and MRP, in NASH, leading to changes in the drug's pharmacokinetic properties. This increase leads to alterations in the pharmacokinetic properties of drugs. Furthermore, modifications in Cytochrome P450 (CYP) enzymes can have a significant impact on these properties. Xenobiotics are metabolized primarily in the liver and constitute liver enzymes and transporters. This review aims to delve into the role of metabolism, transport, and potential herb-drug interactions in the context of NASH.

Pharmacokinetic Effects of Different Models of Nonalcoholic Fatty Liver Disease in Transgenic Humanized OATP1B Mice

Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 (collectively, OATP1B) transporters encoded by the solute carrier organic anion transporter (SLCO) genes mediate uptake of multiple pharmaceutical compounds. Nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease (NAFLD), decreases OATP1B abundance. This research characterized the pathologic and pharmacokinetics effects of three diet- and one chemical-induced NAFLD model in male and female humanized OATP1B mice, which comprises knock-out of rodent Oatp orthologs and insertion of human SLCO1B1 and SLCO1B3. Histopathology scoring demonstrated elevated steatosis and inflammation scores for all NAFLD-treatment groups. Female mice had minor changes in SLCO1B1 expression in two of the four NAFLD treatment groups, and pitavastatin (PIT) area under the concentration-time curve (AUC) increased in female mice in only one of the diet-induced models. OATP1B3 expression decreased in male and female mice in the chemical-induced NAFLD model, with a coinciding increase in PIT AUC, indicating the chemical-induced model may better replicate changes in OATP1B3 expression and OATP substrate disposition observed in NASH patients. This research also tested a reported multifactorial pharmacokinetic interaction between NAFLD and silymarin, an extract from milk thistle seeds with notable OATP-inhibitory effects. Males showed no change in PIT AUC, whereas female PIT AUC increased 1.55-fold from the diet alone and the 1.88-fold from the combination of diet with silymarin, suggesting that female mice are more sensitive to pharmacokinetic changes than male mice. Overall, the humanized OATP1B model should be used with caution for modeling NAFLD and multifactorial pharmacokinetic interactions. SIGNIFICANCE STATEMENT: Advanced stages of NAFLD cause decreased hepatic OATP1B abundance and increase systemic exposure to OATP substrates in human patients. The humanized OATP1B mouse strain may provide a clinically relevant model to recapitulate these observations and predict pharmacokinetic interactions in NAFLD. This research characterized three diet-induced and one drug-induced NAFLD model in a humanized OATP1B mouse model. Additionally, a multifactorial pharmacokinetic interaction was observed between silymarin and NAFLD.

Hedan tablet ameliorated non-alcoholic steatohepatitis by moderating NF-κB and lipid metabolism-related pathways via regulating hepatic metabolites

Non-alcoholic steatohepatitis (NASH) is a severe form of fatty liver disease. If not treated, it can lead to liver damage, cirrhosis and even liver cancer. However, advances in treatment have remained relatively slow, and there is thus an urgent need to develop appropriate treatments. Hedan tablet (HDP) is used to treat metabolic syndrome. However, scientific understanding of the therapeutic effect of HDP on NASH remains limited. We used HDP to treat a methionine/choline-deficient diet-induced model of NASH in rats to elucidate the therapeutic effects of HDP on liver injury. In addition, we used untargeted metabolomics to investigate the effects of HDP on metabolites in liver of NASH rats, and further validated its effects on inflammation and lipid metabolism following screening for potential target pathways. HDP had considerable therapeutic, anti-oxidant, and anti-inflammatory effects on NASH. HDP could also alter the hepatic metabolites changed by NASH. Moreover, HDP considerable moderated NF-κB and lipid metabolism-related pathways. The present study found that HDP had remarkable therapeutic effects in NASH rats. The therapeutic efficacy of HDP in NASH mainly associated with regulation of NF-κB and lipid metabolism-related pathways via arachidonic acid metabolism, glycine-serine-threonine metabolism, as well as steroid hormone biosynthesis.

Time-Restricted Feeding Ameliorates Methionine-Choline Deficient Diet-Induced Steatohepatitis in Mice

Non-alcoholic steatohepatitis (NASH) is an inflammatory form of non-alcoholic fatty liver disease (NAFLD), closely associated with disease progression, cirrhosis, liver failure, and hepatocellular carcinoma. Time-restricted feeding (TRF) has been shown to decrease body weight and adiposity and improve metabolic outcomes; however, the effect of TRF on NASH has not yet been fully understood. We had previously reported that inositol polyphosphate multikinase (IPMK) mediates hepatic insulin signaling. Importantly, we have found that TRF increases hepatic IPMK levels. Therefore, we investigated whether there is a causal link between TRF and IPMK in a mouse model of NASH, i.e., methionine- and choline-deficient diet (MCDD)-induced steatohepatitis. Here, we show that TRF alleviated markers of NASH, i.e., reduced hepatic steatosis, liver triglycerides (TG), serum alanine transaminase (ALT) and aspartate aminotransferase (AST), inflammation, and fibrosis in MCDD mice. Interestingly, MCDD led to a significant reduction in IPMK levels, and the deletion of hepatic IPMK exacerbates the NASH phenotype induced by MCDD, accompanied by increased gene expression of pro-inflammatory chemokines. Conversely, TRF restored IPMK levels and significantly reduced gene expression of proinflammatory cytokines and chemokines. Our results demonstrate that TRF attenuates MCDD-induced NASH via IPMK-mediated changes in hepatic steatosis and inflammation.

Aqueous extract of Polygala japonica Houtt. ameliorated nonalcoholic steatohepatitis in mice through restoring the gut microbiota disorders and affecting the metabolites in feces and liver

BACKGROUND

Polygala japonica Houtt. (PJ) has been demonstrated with several biological potentials such as lipid-lowering and anti-inflammatory effects. However, the effects and mechanisms of PJ on nonalcoholic steatohepatitis (NASH) remain unclear.

PURPOSE

The aim of this study was to evaluate the effects of PJ on NASH and illustrate the mechanism based on modulating gut microbiota and host metabolism.

MATERIALS AND METHODS

NASH mouse model was induced using methionine and choline deficient (MCD) diet and orally treated with PJ. The therapeutic, anti-inflammatory, and anti-oxidative effects of PJ on mice with NASH were firstly assessed. Then, the gut microbiota of mice was analyzed using 16S rRNA sequencing to assess the changes. Finally, the effects of PJ on the metabolites in liver and feces were explored by untargeted metabolomics.

RESULTS

The results indicated that PJ could improve hepatic steatosis, liver injury, inflammatory response, and oxidative stress in NASH mice. PJ treatment also affected the diversity of gut microbiota and changed the relative abundances of Faecalibaculum. Lactobacillus, Muribaculaceae, Dubosiella, Akkermansia, Lachnospiraceae_NK4A136_group, and Turicibacter in NASH mice. In addition, PJ treatment modulated 59 metabolites both in liver and feces. Metabolites involved in histidine, and tryptophan metabolism pathways were identified as the key metabolites according to the correlation analysis between differential gut microbiota and metabolites.

CONCLUSION

Our study demonstrated the therapeutic, anti-inflammatory and anti-oxidative potentials of PJ on NASH. The mechanisms of PJ treatment were related to the improvement of gut microbiota dysbiosis and the regulation of histidine and tryptophan metabolism.

A new NASH model in aged mice with rapid progression of steatohepatitis and fibrosis

Non-alcoholic fatty liver disease (NAFLD) has a high prevalence worldwide, with a significant proportion of patients progressing into non-alcoholic steatohepatitis (NASH) and further into cirrhosis and hepatocellular carcinoma (HCC). Most of the current animal models of NASH have limitations, such as incompatibility with human pathogenesis characteristics or long induction periods, which severely limit the development of new drugs and preclinical studies for NASH. We investigated the progression of NASH and fibrosis, as well as metabolic indicators, at different time points in aged mice induced by the Gubra Amylin NASH (GAN) diet, a high-fat, high-sugar, high-cholesterol diet, and attempted to establish a rapid and useful mouse model of NASH. Young and aged C57BL/6 mice were induced on a normal chow or GAN diet for 12 and 21 weeks, respectively. After 12 weeks of induction, aged mice developed NASH, including hepatic steatosis, lobular inflammation and hepatic ballooning, and the phenotype was more severe compared with young mice. After 21 weeks of induction, aged mice developed hepatic fibrosis, which greatly shortened the induction time compared with young mice. Furthermore, analysis of immune cell infiltration in the liver by flow cytometry elucidated the changes of multiple immune cells during the pathogenesis of NASH. These findings suggest that aged mice may develop NASH and fibrosis more rapidly under GAN diet induction, which may significantly shorten the period for preclinical studies of NASH.

Extraction, characterization, and anti-nonalcoholic steatohepatitis activity of a (1,3) (1,6)-β-D-glucan from the Polyporus umbellatus (Pers.) Fries

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease characterized by inflammation and hepatic steatosis that may coincide with fibrotic activity. To date, no pharmacological agents have been approved for NASH treatment. Here, a homogeneous (1,3),(1,6)-β-D-glucan (PUP-W-1, Mw: 41.07 kDa) was successfully purified from Polyporus umbellatus (Pers.) Fries sclerotia and characterized. The analysis showed that the PUP-W-1 backbone consisted of a repeating chain of eight →3)-β-D-Glcp-(1 → units, with branched chains of four β-D-Glcp residues, joined by repeating 1,6-linkage units at the O-6 position of the backbone. The pharmacological effects of PUP-W-1 treatment in the context of NASH pathogenesis were explored using a methionine choline-deficient (MCD) diet-induced murine steatohepatitis model. The MCD model mice exhibited pronounced steatohepatitis, inflammatory activity, steatosis, stellate cell activation, and mild fibrotic activity. Treatment of the mice for three weeks with PUP-W-1 prevented the development of NASH due to the suppression of inflammation, lipid accumulation, and fibrosis. As suggested by these findings, PUP-W-1 may hold promise as a natural drug candidate or precursor for the treatment of NASH.

Predicting disruptions to drug pharmacokinetics and the risk of adverse drug reactions in non-alcoholic steatohepatitis patients

The liver plays a central role in the pharmacokinetics of drugs through drug metabolizing enzymes and transporters. Non-alcoholic steatohepatitis (NASH) causes disease-specific alterations to the absorption, distribution, metabolism, and excretion (ADME) processes, including a decrease in protein expression of basolateral uptake transporters, an increase in efflux transporters, and modifications to enzyme activity. This can result in increased drug exposure and adverse drug reactions (ADRs). Our goal was to predict drugs that pose increased risks for ADRs in NASH patients. Bibliographic research identified 71 drugs with reported ADRs in patients with liver disease, mainly non-alcoholic fatty liver disease (NAFLD), 54 of which are known substrates of transporters and/or metabolizing enzymes. Since NASH is the progressive form of NAFLD but is most frequently undiagnosed, we identified other drugs at risk based on NASH-specific alterations to ADME processes. Here, we present another list of 71 drugs at risk of pharmacokinetic disruption in NASH, based on their transport and/or metabolism processes. It encompasses drugs from various pharmacological classes for which ADRs may occur when used in NASH patients, especially when eliminated through multiple pathways altered by the disease. Therefore, these results may inform clinicians regarding the selection of drugs for use in NASH patients.

Salvia miltiorrhiza Bge. (Danshen) in the Treating Non-alcoholic Fatty Liver Disease Based on the Regulator of Metabolic Targets

Non-alcoholic fatty liver disease (NAFLD) is rapidly prevalent due to its strong association with increased metabolic syndrome such as cardio- and cerebrovascular disorders and diabetes. Few drugs can meet the growing disease burden of NAFLD. Salvia miltiorrhiza Bge. (Danshen) have been used for over 2,000 years in clinical trials to treat NAFLD and metabolic syndrome disease without clarified defined mechanisms. Metabolic targets restored metabolic homeostasis in patients with NAFLD and improved steatosis by reducing the delivery of metabolic substrates to liver as a promising way. Here we systematic review evidence showing that Danshen against NAFLD through diverse and crossing mechanisms based on metabolic targets. A synopsis of the phytochemistry and pharmacokinetic of Danshen and the mechanisms of metabolic targets regulating the progression of NAFLD is initially provided, followed by the pharmacological activity of Danshen in the management NAFLD. And then, the possible mechanisms of Danshen in the management of NAFLD based on metabolic targets are elucidated. Specifically, the metabolic targets c-Jun N-terminal kinases (JNK), sterol regulatory element-binding protein-1c (SREBP-1c), nuclear translocation carbohydrate response element–binding protein (ChREBP) related with lipid metabolism pathway, and peroxisome proliferator-activated receptors (PPARs), cytochrome P450 (CYP) and the others associated with pleiotropic metabolism will be discussed. Finally, providing a critical assessment of the preclinic and clinic model and the molecular mechanism in NAFLD.

Qingrequzhuo capsule alleviated methionine and choline deficient diet-induced nonalcoholic steatohepatitis in mice through regulating gut microbiota, enhancing gut tight junction and inhibiting the activation of TLR4/NF-κB signaling pathway

Qingrequzhuo capsule (QRQZ), composed of Morus alba L., Coptis chinensis Franch., Anemarrhena asphodeloides Bunge, Alisma plantago-aquatica subsp. orientale (Sam.) Sam., Citrus × aurantium L., Carthamus tinctorius L., Rheum palmatum L., Smilax glabra Roxb., Dioscorea oppositifolia L., Cyathula officinalis K.C.Kuan, has been used to treat nonalcoholic steatohepatitis (NASH) in clinic. However, the mechanism of QRQZ on NASH remains unclear. Recent studies have found that the dysfunction of gut microbiota could impair the gut barrier and induce the activation of TLR4/NF-kB signaling pathway, and further contribute to the inflammatory response in NASH. Modulating the gut microbiota to reduce inflammation could prevent the progression of NASH. In this study, a mouse model of NASH was generated by methionine and choline deficient diet (MCD) and treated with QRQZ. First, we evaluated the therapeutic effects of QRQZ on liver injury and inflammation in the NASH mice. Second, the changes in the gut microbiota diversity and abundance in each group of mice were measured through 16S rRNA sequencing. Finally, the effects of QRQZ on gut mucosal permeability, endotoxemia, and liver TLR4/NF-kB signaling pathway levels were examined. Our results showed that QRQZ significantly reduced the lipid accumulation in liver and the liver injury in NASH mice. In addition, QRQZ treatment decreased the levels of inflammatory cytokines in liver. 16S rRNA sequencing showed that QRQZ affected the diversity of gut microbiota and a f f e c t e d t h e r e l a t i v e a b u n d a n c e s o f D u b o s i e l l a , Lachnospiraceae_NK4A136_group, and Blautiain NASH mice. Besides, QRQZ could increase the expression of tight junction proteins (zonula occludens-1 and occludin) in gut and decrease the lipopolysaccharide (LPS) level in serum. Western blot results also showed that QRQZ treatment decreased the protein expression ofTLR4, MyD88 and the phosphorylation of IkB and NF-kBp65 and qPCR results showed that QRQZ treatment down-regulated the gene expression of interleukin (IL)-1b, IL-6, and tumor necrosis factor (TNF)-a in liver. In conclusion, our study demonstrated that QRQZ could reduce the lipid accumulation and inflammatory response in NASH model mice. The mechanisms of QRQZ on NASH were associated with modulating gut microbiota, thereby inducing the tight junction of gut barrier, reducing the endotoxemia and inhibiting the activation of TLR4/NFkB signaling pathway in liver.

Exogenous Drug Disposition as a Diagnostic Biomarker Strategy for Non-Alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is the progressive form of non-alcoholic fatty liver disease (NAFLD) and is diagnosed by a liver biopsy. Due to the invasiveness of a biopsy, the majority of patients with NASH are undiagnosed. Additionally, the prevalence of NAFLD and NASH creates the need for a simple screening method to differentiate patients with NAFLD versus NASH. Non-invasive strategies for diagnosing NAFLD versus NASH have been developed, typically relying on imaging techniques and endogenous biomarker panels. However, each technique has limitations, and none can accurately predict the associated functional impairment of drug metabolism and disposition. The function of several drug metabolizing enzymes and drug transporters have been described in NASH that impacts drug pharmacokinetics. The aim of this review is to give an overview of the existing non-invasive strategies to diagnose NASH, and to propose a novel strategy based on altered pharmacokinetics using an exogenous biomarker whose disposition and elimination pathways are directly impacted by disease progression. Altered disposition of safe and relatively inert exogenous compounds may provide the sensitivity and specificity needed to differentiate patients with NAFLD and NASH to facilitate a direct indication of hepatic impairment on drug metabolism and prevent subsequent adverse drug reactions. Significance Statement This review provides an overview of the main non-invasive techniques (imaging and panels of biomarkers) used to diagnose non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) along with a biopsy. Pharmacokinetic changes have been identified in NASH and this review proposes a new approach to predict NASH and the related risk of adverse drug reactions, based on the assessment of drug elimination disruption using exogenous biomarkers.

Val-Val-Tyr-Pro protects against non-alcoholic steatohepatitis in mice by modulating the gut microbiota and gut-liver axis activation

Val‐Val‐Tyr‐Pro (VVYP) peptide is one of the main active components of Globin digest (GD). Our previous studies indicated that VVYP could protect against acetaminophen and carbon tetrachloride‐induced acute liver failure in mice and decrease blood lipid level. However, the effects and underlying mechanisms of VVYP in the treatment of non‐alcoholic steatohepatitis (NASH) have not been discovered. Our present study was designed to investigate the preventive effect of VVYP on NASH and its underlying specific mechanisms. We found that VVYP inhibited the cytotoxicity and lipid accumulation in L‐02 cells that were exposed to a mixture of free fatty acid (FFA). VVYP effectively alleviated the liver injury induced by methionine‐choline‐deficient (MCD) diet, demonstrated by reducing the levels of serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST)/triglycerides (TG)/non‐esterified fatty acids (NEFA) and improving liver histology. VVYP decreased expression levels of lipid synthesis‐related genes and reduced levels of the proinflammation cytokines in the liver of mice fed by MCD diet. Moreover, VVYP inhibited the increased level of LPS and reversed the liver mitochondria dysfunction induced by MCD diet. Meanwhile, VVYP significantly increased the abundance of beneficial bacteria such as Eubacteriaceae, coriobacteriacease, Desulfovibrionaceae, S24‐7 and Bacteroidia in high‐fat diet (HFD)‐fed mice, however, VVYP reduced the abundance of Lactobacillus. Moreover, VVYP conferred the protective effect of intestinal barrier via promoting the expression of the mucins and tight junction (TJ)‐associated genes and inhibited subsequent liver inflammatory responses. These results indicated that the protective role of VVYP on NASH is mediated by modulating gut microbiota imbalance and related gut‐liver axis activation. VVYP might be a promising drug candidate for NASH.

Non-alcoholic fatty liver disease to metabolic dysfunction-associated fatty liver disease: Conceptual changes for clinicians, researchers and patients

Non-alcoholic fatty liver disease (NAFLD) is now the most common etiology of chronic liver disease threatening global public health. However, the name "NAFLD" is no longer appropriate with the change of time. Recently, a new term, "metabolic dysfunction-associated fatty liver disease" has been proposed by an international panel of experts, which implies profound conceptual changes in terms of its metabolism-related etiology and disease heterogeneity. In this article we discuss the specific conceptual changes that clinicians, researchers and patients must absorb.

Transporter Activity Changes in Nonalcoholic Steatohepatitis: Assessment with Plasma Coproporphyrin I and III

Expression and functional changes in the organic anion transporting polypeptide (OATP)-multidrug resistance-associated protein (MRP) axis of transporters are well reported in patients with nonalcoholic steatohepatitis (NASH). These changes can impact plasma and tissue disposition of endo- and exogenous compounds. The transporter alterations are often assessed by administration of a xenobiotic or by transporter proteomic analysis from liver biopsies. Using gene expression, proteomics, and endogenous biomarkers, we show that the gene expression and activity of OATP and MRP transporters are associated with disease progression and recovery in humans and in preclinical animal models of NASH. Decreased OATP and increased MRP3/4 gene expression in two cohorts of patients with steatosis and NASH, as well as gene and protein expression in multiple NASH rodent models, have been established. Coproporphyrin I and III (CP I and III) were established as substrates of MRP4. CP I plasma concentration increased significantly in four animal models of NASH, indicating the transporter changes. Up to a 60-fold increase in CP I plasma concentration was observed in the mouse bile duct-ligated model compared with sham controls. In the choline-deficient amino acid-defined high-fat diet (CDAHFD) model, CP I plasma concentrations increased by >3-fold compared with chow diet-fed mice. In contrast, CP III plasma concentrations remain unaltered in the CDAHFD model, although they increased in the other three NASH models. These results suggest that tracking CP I plasma concentrations can provide transporter modulation information at a functional level in NASH animal models and in patients. SIGNIFICANCE STATEMENT: Our analysis demonstrates that multidrug resistance-associated protein 4 (MRP4) transporter gene expression tracks with nonalcoholic steatohepatitis (NASH) progression and intervention in patients. Additionally, we show that coproporphyrin I and III (CP I and III) are substrates of MRP4. CP I plasma and liver concentrations increase in different diet- and surgery-induced rodent NASH models, likely explained by both gene- and protein-level changes in transporters. CP I and III are therefore potential plasma-based biomarkers that can track NASH progression in preclinical models and in humans.

Si-Wei-Qing-Gan-Tang Improves Non-Alcoholic Steatohepatitis by Modulating the Nuclear Factor-κB Signal Pathway and Autophagy in Methionine and Choline Deficient Diet-Fed Rats

Si-Wei-Qing-Gan-Tang (SWQGT) is a Chinese medicine formula that is widely used as a folk remedy of herbal tea for the treatment of chronic hepatitis, like non-alcoholic steatohepatitis (NASH), around Ganzhou City (Jiangxi province, China). However, the underlying mechanisms of this formula against NASH are still unknown. This study aimed to explore the effect and mechanisms of SWQGT against NASH. A network pharmacology approach was used to predict the potential mechanisms of SWQGT against NASH. Then a rat model of NASH established by feeding the methionine and choline deficient (MCD) diet was used to verify the effect and mechanisms of SWQGT on NASH in vivo. SWQGT (1 g/kg/d and 3 g/kg/d) were given by intragastric administration. Body weight, liver weight, serum biochemical indicators, liver triglyceride and total cholesterol were all measured. Tumor necrosis factor-α (TNF-α), Interleukin (IL)-1β, IL-6 levels in the livers were evaluated using ELISA. Hematoxylin and eosin (HE) and Oil Red O staining were used to determine histology, while western blot was used to assess the relative expression levels of the nuclear factor-κB (NF-κB) pathway- and autophagy-related proteins. Functional and pathway enrichment analyses revealed that SWQGT obviously influenced inflammation-related signal pathways in NASH. Furthermore, in vivo experiment showed that SWQGT caused a reduction in liver weight and liver index of MCD diet-fed rats. The formula also helped to reduce hepatomegaly and improve pathological liver changes and hepatic steatosis. SWQGT likewise reduced liver TNF-α, IL-1β, and IL-6 levels and down-regulated p-NF-κB p65, p-p38 MAPK, p-MEK1/2, p-ERK1/2, p-mTOR, and p62, while up-regulating p-ULK1 and LC3II protein expression levels. SWQGT could improve NASH in MCD diet-fed rats, and this effect may be associated with its down-regulation of NF-κB and activation of autophagy.

Gender differences in diet-induced steatotic disease in Cyp2b-null mice

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease; however, progression to nonalcoholic steatohepatitis (NASH) is associated with most adverse outcomes. CYP2B metabolizes multiple xeno- and endobiotics, and male Cyp2b-null mice are diet-induced obese (DIO) with increased NAFLD. However, the DIO study was not performed long enough to assess progression to NASH. Therefore, to assess the role of Cyp2b in fatty liver disease progression from NAFLD to NASH, we treated wildtype (WT) and Cyp2b-null mice with a normal diet (ND) or choline-deficient, L-amino acid-defined high fat diet (CDAHFD) for 8 weeks and determined metabolic and molecular changes. CDAHFD-fed WT female mice gained more weight and had greater liver and white adipose tissue mass than their Cyp2b-null counterparts; males experienced diet-induced weight loss regardless of genotype. Serum biomarkers of liver injury increased in both CDAHFD-fed female and male mice; however CDAHFD-fed Cyp2b-null females exhibited significantly lower serum ALT, AST, and ASP concentrations compared to WT mice, indicating Cyp2b-null females were protected from liver injury. In both genders, hierarchical clustering of RNA-seq data demonstrates several gene ontologies responded differently in CDAHFD-fed Cyp2b-null mice compared to WT mice (lipid metabolism > fibrosis > inflammation). Oil Red O staining and direct triglycerides measurements confirmed that CDAHFD-fed Cyp2b-null females were protected from NAFLD. CDAHFD-fed Cyp2b-null mice showed equivocal changes in fibrosis with transcriptomic and serum markers suggesting less inflammation due to glucocorticoid-mediated repression of immune responses. In contrast to females, CDAHFD-fed Cyp2b-null males had higher triglyceride levels. Results indicate that female Cyp2b-null mice are protected from NAFLD while male Cyp2b-null mice are more susceptible to NAFLD, with few significant changes in NASH development. This study confirms that increased NAFLD development does not necessarily lead to progressive NASH. Furthermore, it indicates a role for Cyp2b in fatty liver disease that differs based on gender.

Neutralizing antibody against osteopontin attenuates non-alcoholic steatohepatitis in mice

Previously, we reported that an extracellular matrix protein, osteopontin (OPN), is involved in various autoimmune diseases using a neutralizing polyclonal antibody against OPN generated in rabbits. However, the antibody cannot be used for long-term mouse models of chronic inflammatory disease because of the induction of antibodies against anti-OPN rabbit IgG. In this study, we generated a new antibody, anti-mouse OPN mouse IgG (35B6). 35B6 inhibited the cell adhesion of mouse and human OPN to Chinese Hamster Ovary (CHO) cells or CHO cells expressing α4 or α9 integrin. It was reported that OPN is highly expressed and has an important role in a chronic liver disease, non-alcoholic steatohepatitis (NASH). 35B6 injection twice a week for 8 weeks attenuated liver inflammation and fibrosis in a NASH mouse model, suggesting 35B6 is beneficial for the treatment of NASH. 35B6 was preferable to the rabbit anti-OPN antibody for investigating the in vivo function of OPN in mouse models of long-term disease.

Preclinical investigation of potential use of thymidine phosphorylase-targeting tracer for diagnosis of nonalcoholic steatohepatitis

INTRODUCTION

Although liver biopsy is the gold standard for the diagnosis of nonalcoholic steatohepatitis (NASH), it has several problems including high invasiveness and sampling errors. Therefore, the development of alternative methods to overcome these disadvantages is strongly required. In this study, we evaluated the potential use of our tracer targeting thymidine phosphorylase (TYMP), 5-[¹²³I]iodo-6-[(2-iminoimidazolidinyl)methyl]uracil ([¹²³I]IIMU) for the diagnosis of NASH.

METHODS

The mice used as the NASH model (hereafter, NASH mice) were prepared by feeding a methionine- and choline-deficient diet for 4 weeks. A control group was similarly given a control diet. The expression levels of the TYMP gene and protein in the liver were examined by real-time reverse-transcription polymerase chain reaction and western blot analyses. The localizations of [¹²⁵I]IIMU and the TYMP protein in the liver were examined by autoradiography and immunohistochemical staining, respectively. Finally, the mice were injected with [¹²³I]IIMU and single-photon emission tomography (SPECT) imaging was conducted.

RESULTS

The hepatic expression levels of TYMP were significantly lower in the NASH mice than in the control mice at both mRNA and protein levels, suggesting that a decrease in TYMP level could be an indicator of NASH. [¹²⁵I]IIMU was uniformly distributed in the liver of the control mice, whereas it showed a patchy distribution in that of the NASH mice. The localization of [¹²⁵I]IIMU was visually consistent with that of the TYMP protein in the liver of the control and NASH mice. SPECT analysis indicated that the hepatic accumulation of [¹²³I]IIMU in the NASH mice was significantly lower than that in the control mice [SUV (g/ml): 4.14 ± 0.87 (Control) vs 2.31 ± 0.29 (NASH)].

CONCLUSIONS

[¹²³I]IIMU may provide a noninvasive means for imaging TYMP expression in the liver and may be applicable to the diagnosis of NASH.

Drug-induced liver injury in obesity and nonalcoholic fatty liver disease

Obesity is commonly associated with nonalcoholic fatty liver (NAFL), a benign condition characterized by hepatic lipid accumulation. However, NAFL can progress in some patients to nonalcoholic steatohepatitis (NASH) and then to severe liver lesions including extensive fibrosis, cirrhosis and hepatocellular carcinoma. The entire spectrum of these hepatic lesions is referred to as nonalcoholic fatty liver disease (NAFLD). The transition of simple fatty liver to NASH seems to be favored by several genetic and environmental factors. Different experimental and clinical investigations showed or suggested that obesity and NAFLD are able to increase the risk of hepatotoxicity of different drugs. Some of these drugs may cause more severe and/or more frequent acute liver injury in obese individuals whereas others may trigger the transition of simple fatty liver to NASH or may worsen hepatic lipid accumulation, necroinflammation and fibrosis. This review presents the available information regarding drugs that may cause a specific risk in the context of obesity and NAFLD. These drugs, which belong to different pharmacological classes, include acetaminophen, halothane, methotrexate, rosiglitazone and tamoxifen. For some of these drugs, experimental investigations confirmed the clinical observations and unveiled different pathophysiological mechanisms which may explain why these pharmaceuticals are particularly hepatotoxic in obesity and NAFLD. Because obese people often take several drugs for the treatment of different obesity-related diseases, there is an urgent need to identify the main pharmaceuticals that may cause acute liver injury on a fatty liver background or that may enhance the risk of severe chronic liver disease.

Hepatic metabolomics reveals that liver injury increases PCB 126-induced oxidative stress and metabolic dysfunction

The deleterious effects of PCB 126 are complex, and the role of the liver in modifying toxic insult is not well understood. We utilized metabolomics approaches to compare liver metabolites significantly affected by PCB 126 in control mice and a diet induced liver injury mouse model. In this 14-week study, mice were fed either an amino acid supplemented control diet (CD) or a methionine-choline deficient diet (MCD) which promoted nonalcoholic steatohepatitis (NASH) and were subsequently exposed to PCB 126. The liver metabolome was profiled by a global metabolomic analysis using LC-MS. There were clear differences between PCB 126 exposed and control mice in the hepatic metabolomic profiles (216 and 266 metabolites were altered in CD-fed and MCD-fed mice respectively after PCB 126 exposure). PCB 126 modulated glycerophospholipid metabolism, glutathione metabolism, and CoA biosynthesis pathways irrespective of diet; indicating that the disturbance in lipid metabolism and thiol metabolites are general markers of PCB 126 exposure irrespective of liver health. Additionally, metabolites associated with oxidative stress and mitochondrial dysfunction were greatly elevated in PCB 126 exposed mice with compromised livers (e.g., 4-hydroxy-nonenal glutathione, oxylipids, uric acid, and acylcarnitines). Moreover, PCB 126 exposure downregulated redox genes, and the effect was more pronounced in liver injury mice. In conclusion, this study demonstrates that PCB 126 could induce oxidative stress and metabolic dysfunction, and pre-existing liver injury can markedly modify PCB 126-induced metabolic changes. Using metabolic profiling, this study suggests mechanism of enhanced PCB 126 toxicity under liver injury settings.