Biliary Elimination of Pemetrexed Is Dependent on Mrp2 in Rats: Potential Mechanism of Variable Response in Nonalcoholic Steatohepatitis

Alterations of valsartan pharmacokinetics in a rodent model of metabolic dysfunction-associated steatohepatitis

Valsartan (VAL) is commonly prescribed for patients with cardiovascular disease (CVD) to lower blood pressure, reduce heart failure risk, and prevent heart attacks or strokes by blocking the effects of angiotensin II. Many patients with CVD also suffer from metabolic dysfunction-associated steatohepatitis (MASH), which disrupts several xenobiotic transporters, affecting the pharmacokinetics of numerous drugs. Medications used in patients to treat comorbidities associated with MASH may be subject to this altered disposition and potential toxicity. This study aimed to assess how MASH alters the pharmacokinetics of VAL using a rodent model that mimics human MASH. MASH was induced in rats via a methionine- and choline-deficient (MCD) diet. Rats received VAL-a substrate of organic anion-transporting polypeptide (OATP) 1B1/1B3 and reported for multidrug resistance-associated protein-2-(2 mg/kg) through intravenous injection to isolate hepatic transport processes, and bile, serum, and liver concentrations measured using liquid chromatography-tandem mass spectrometry. Consistent with MASH progression, MCD rats presented with more gross pathology, including increased liver-to-body weight ratios, along with macrosteatosis, hepatocyte ballooning, and lobular inflammation. In MCD rats, the expression of Oatp1b2 was significantly reduced, and Mrp2 was internalized, resulting in higher systemic exposure to VAL compared with controls. Additionally, cumulative biliary excretion of VAL was lower in MCD rats. To further assess VAL disposition in MASH, transport kinetics were evaluated in human embryonic kidney 293 cells overexpressing OATP1B1 or OATP1B3, revealing similar affinity for VAL between both transporters. These findings suggest that changes in OATP function in MASH may alter VAL pharmacokinetics, which may have implications for personalized treatments. SIGNIFICANCE STATEMENT: Although expression of drug transporters in metabolic dysfunction-associated steatohepatitis (MASH) has been explored, the combined effect between MASH and genetic loss of transporters on the disposition of sartan drugs has not been determined. This study applied liquid chromatography-tandem mass spectrometry analyses and immunohistological staining to assess drug disposition and identify alterations to drug transporters in rodents on a methionine- and choline-deficient diet. The observations made in this study have significant implications regarding its disposition in the context of hepatic dysfunction associated with MASH.

Nonalcoholic steatohepatitis increases plasma retention of sorafenib-glucuronide in a mouse model by altering hepatocyte hopping

Hepatocyte hopping is the hepatocyte-to-sinusoid-to-hepatocyte shuttling that increases the efficiency of hepatic elimination of xenobiotics. This phenomenon is mediated via efflux of hepatic metabolites by Mrp3 and reuptake by Oatp transporters in sequential hepatocytes until eventual biliary efflux by Mrp2. Sorafenib-glucuronide (SFB-G), the major metabolite of sorafenib (SFB), undergoes hepatocyte hopping, leading to efficient biliary elimination. Nonalcoholic steatohepatitis (NASH) alters the functioning of transporters involved in hepatocyte hopping. The purpose of this study was to quantify the effect of NASH on the three drug disposition processes of hepatocyte hopping. Male FVB and C57BL/6 wild-type (WT), Oatp1a/1b cluster knockout (O-/-), and Mrp2 knockout (Mrp2 -/-) mice were fed a methionine and choline deficient (MCD) diet to induce NASH. Mice were administered 10 mg/kg SFB via oral gavage and concentrations of SFB and SFB-G in plasma quantified using liquid-chromatography tandem mass spectrometry. Compared to WT, plasma area under the concentration-time curve (AUC) of SFB-G increased by 108-fold in the O-/--C group and by 345-fold in the Mrp2 -/--C group. In the WT-NASH group, up-regulation of Mrp3 and decreased Mrp2 function, along with reduced Oatp uptake, elevated SFB-G AUC by 165-fold. SFB-G AUC in the O-/--NASH group increased by 108-fold compared to WT-C (3.2-fold compared to O-/--C). SFB-G AUC in the Mrp2 -/--NASH group increased by 450-fold (1.2-fold compared to Mrp2-/--C). Taken together, the mislocalization of Mrp2 in NASH is a major contributor to the decrease in SFB-G biliary efflux, but decreased Oatp uptake and enhanced sinusoidal efflux also limit the contribution of downstream hepatocytes, resulting in plasma retention that recapitulates the altered pharmacokinetics observed in human NASH.

Citrus depressa Hayata Peel Ameliorates Nonalcoholic Fatty Liver and Modulates the Hepatic Drug-metabolizing Enzymes and Transporters in Rats Fed a High-fat Diet

Citrus depressa Hayata is a small, green citrus fruit native to Taiwan and Japan. The citrus peel contains polymethoxylated flavones, including nobiletin and tangeretin, and might have strong antioxidant and...

Feedback Signaling between Cholangiopathies, Ductular Reaction, and Non-Alcoholic Fatty Liver Disease

Fatty liver diseases, such as non-alcoholic fatty liver disease (NAFLD), are global health disparities, particularly in the United States, as a result of cultural eating habits and lifestyle. Pathological studies on NAFLD have been mostly focused on hepatocytes and other inflammatory cell types; however, the impact of other biliary epithelial cells (i.e., cholangiocytes) in the promotion of NAFLD is growing. This review article will discuss how cholestatic injury and cholangiocyte activity/ductular reaction influence NAFLD progression. Furthermore, this review will provide informative details regarding the fundamental properties of cholangiocytes and bile acid signaling that can influence NAFLD. Lastly, studies relating to the pathogenesis of NAFLD, cholangiopathies, and ductular reaction will be analyzed to help gain insight for potential therapies.

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.

Interaction of Oatp1b2 expression and nonalcoholic steatohepatitis on pravastatin plasma clearance

The downregulation of hepatic uptake transporters, including those of the OATP family, are a well known consequence of nonalcoholic steatohepatitis (NASH). Prior studies have shown that the combination of NASH and Oatp1b2 knockout synergistically reduces the clearance of pravastatin (PRAV) in the methionine and choline deficient (MCD) mouse model of NASH, and the current study therefore aimed to determine the impact of NASH and genetic heterozygosity of Oatp1b2 on PRAV clearance, modeling the overlap between the 24% of the human population who are heterozygous for non-functioning OATP1B1, and the ~15% with NASH, potentially placing these people at higher risk of statin-induced myopathy. Therefore, male C57BL/6 wild-type (WT), Oatp1b2+/- (HET), and Oatp1b2-/- (KO) mice were fed either a control (methionine and choline sufficient) or methionine and choline-deficient (MCD) diet to induce NASH. After six weeks of feeding, pravastatin was administered via the carotid artery. Blood and bile samples were collected throughout 90 min after PRAV administration. The concentration of PRAV in plasma, bile, liver, kidney, and muscle was determined by liquid chromatography-tandem mass spectrometry. MCD diet did not alter the plasma AUC values of PRAV in either WT or HET mice. However, the MCD diet increased plasma AUC by 4.4-fold in KO mice. MCD diet and nonfunctional Oatp1b2 synergistically increased not only plasma AUC but also the extrahepatic tissue concentration of pravastatin, whereas the partially decreased function of Oatp1b2 and NASH together were insufficient in significantly altering PRAV pharmacokinetics. These data suggest that a single copy of fully functional OATP1B1 in NASH patients may be sufficient to avoid the increase of pravastatin toxicity.

Gene-by-Environment Interaction of Bcrp-/- and Methionine- and Choline-Deficient Diet-Induced Nonalcoholic Steatohepatitis Alters SN-38 Disposition

Disease progression to nonalcoholic steatohepatitis (NASH) has profound effects on the expression and function of drug-metabolizing enzymes and transporters, which provide a mechanistic basis for variable drug response. Breast cancer resistance protein (BCRP), a biliary efflux transporter, exhibits increased liver mRNA expression in NASH patients and preclinical NASH models, but the impact on function is unknown. It was shown that the transport capacity of multidrug resistance protein 2 (MRP2) is decreased in NASH. SN-38, the active irinotecan metabolite, is reported to be a substrate for Bcrp, whereas SN-38 glucuronide (SN-38G) is a Mrp2 substrate. The purpose of this study was to determine the function of Bcrp in NASH through alterations in the disposition of SN-38 and SN-38G in a Bcrp knockout (Bcrp-/- KO) and methionine- and choline-deficient (MCD) model of NASH. Sprague Dawley [wild-type (WT)] rats and Bcrp-/- rats were fed either a methionine- and choline-sufficient (control) or MCD diet for 8 weeks to induce NASH. SN-38 (10 mg/kg) was administered i.v., and blood and bile were collected for quantification by liquid chromatography-tandem mass spectrometry. In Bcrp-/- rats on the MCD diet, biliary efflux of SN-38 decreased to 31.9%, and efflux of SN-38G decreased to 38.7% of control, but WT-MCD and KO-Control were unaffected. These data indicate that Bcrp is not solely responsible for SN-38 biliary efflux, but rather implicate a combined role for BCRP and MRP2. Furthermore, the disposition of SN-38 and SN-38G is altered by Bcrp-/- and NASH in a gene-by-environment interaction and may result in variable drug response to irinotecan therapy in polymorphic patients.

Misregulation of membrane trafficking processes in human nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) remodels the expression and function of genes and proteins that are critical for drug disposition. This study sought to determine whether disruption of membrane protein trafficking pathways in human NASH contributes to altered localization of multidrug resistance-associated protein 2 (MRP2). A comprehensive immunoblot analysis assessed the phosphorylation, membrane translocation, and expression of transporter membrane insertion regulators, including several protein kinases (PK), radixin, MARCKS, and Rab11. Radixin exhibited a decreased phosphorylation and total expression, whereas Rab11 had an increased membrane localization. PKCδ, PKCα, and PKA had increased membrane activation, whereas PKCε had a decreased phosphorylation and membrane expression. Radixin dephosphorylation may activate MRP2 membrane retrieval in NASH; however, the activation of Rab11/PKCδ and PKA/PKCα suggest an activation of membrane insertion pathways as well. Overall these data suggest an altered regulation of protein trafficking in human NASH, although other processes may be involved in the regulation of MRP2 localization.

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

In the past few decades, great conceptual and technological advances have been made in the field of toxicology, but animal model-based research still remains one of the most widely used and readily available tools for furthering our current knowledge. However, animal models are not perfect in predicting all systemic toxicity in humans. Extrapolating animal data to accurately predict human toxicities remains a challenge, and researchers are obligated to question the appropriateness of their chosen animal model. This paper provides an assessment of the utility of the methionine- and choline-deficient (MCD) diet fed animal model in reflecting human nonalcoholic steatohepatitis (NASH) and the potential risks of adverse drug reactions and toxicities that are associated with the disease. As a commonly used NASH model, the MCD model fails to exhibit most metabolic abnormalities in a similar manner to the human disease. The MCD model, on the other hand, closely resembles human NASH histology and reflects signatures of drug transporter alterations in humans. Due to the nature of the MCD model, it should be avoided in studies of NASH pathogenesis, metabolic parameter evaluation, and biomarker identification. But it can be used to accurately predict altered drug disposition due to NASH-associated transporter alterations.

Effect of Liver Disease on Hepatic Transporter Expression and Function

Liver disease can alter the disposition of xenobiotics and endogenous substances. Regulatory agencies such as the Food and Drug Administration and the European Medicines Evaluation Agency recommend, if possible, studying the effect of liver disease on drugs under development to guide specific dose recommendations in these patients. Although extensive research has been conducted to characterize the effect of liver disease on drug-metabolizing enzymes, emerging data have implicated that the expression and function of hepatobiliary transport proteins also are altered in liver disease. This review summarizes recent developments in the field, which may have implications for understanding altered disposition, safety, and efficacy of new and existing drugs. A brief review of liver physiology and hepatic transporter localization/function is provided. Then, the expression and function of hepatic transporters in cholestasis, hepatitis C infection, hepatocellular carcinoma, human immunodeficiency virus infection, nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, and primary biliary cirrhosis are reviewed. In the absence of clinical data, nonclinical information in animal models is presented. This review aims to advance the understanding of altered expression and function of hepatic transporters in liver disease and the implications of such changes on drug disposition.