Cytochrome P450 2E1 and hyperglycemia-induced liver injury

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.

Cyp2e1 knockdown attenuates high glucose-induced apoptosis and oxidative stress of cardiomyocytes by activating PI3K/Akt signaling

AIMS

Cyp2e1 is a crucial CYP450 enzyme participating in diabetes and cardiovascular disorder. However, the role of Cyp2e1 in diabetic cardiomyopathy (DCM) has never been reported. Thus, we intended to identify the effects of Cyp2e1 on cardiomyocytes under high glucose (HG) conditions.

METHODS

Identification of differentially expressed genes in DCM and control rats was performed using bioinformatics analysis based on GEO database. The Cyp2e1-knockdown H9c2 and HL-1 cells were established through transfection with si-Cyp2e1. Western blot analysis was performed to determine the expression levels of Cyp2e1, apoptosis-related proteins and PI3K/Akt signaling-associated proteins. TUNEL assay was performed to assess apoptotic rate. Reactive oxygen species (ROS) generation was examined by DCFH2-DA staining assay.

RESULTS

From the bioinformatics analysis, Cyp2e1 was confirmed as an upregulated gene in DCM tissues. In vitro assays proved that Cyp2e1 expression was markedly increased in HG-induced H9c2 and HL-1 cells. Cyp2e1 knockdown attenuated HG-induced apoptosis in both H9c2 and HL-1 cells, as proved by deceased apoptotic rate, relative cleaved caspase-3/caspase-3 level, and caspase-3 activity. Cyp2e1 knockdown reduced ROS generation and elevated the expression level of nuclear Nrf2 in HG-induced H9c2 and HL-1 cells. Increased relative levels of p-PI3K/PI3K and p-Akt/Akt were found in Cyp2e1-knockdown H9c2 and HL-1 cells. Inhibition of PI3K/Akt using LY294002 reversed the inhibitory effects of Cyp2e1 knockdown on cell apoptosis and ROS generation on cardiomyocytes.

CONCLUSIONS

Cyp2e1 knockdown attenuated HG-induced apoptosis and oxidative stress by activating PI3K/Akt signaling in cardiomyocytes. These findings suggested that Cyp2e1 might be potentially used as an effective therapeutic strategy for DCM.

Treatment with omega-3 PUFAs does not increase the risk of CYP2E1-dependent oxidative stress and diabetic liver pathology

An increase in CYP2E1 expression is a key factor in the development of diabetic oxidative liver damage. Long-term treatment with omega-3 PUFAs, which are CYP2E1 substrates, may affect CYP2E1 expression in the liver. In this work, we performed Western blot analysis, biochemical methods, and microscopic ultrastructural studies of the liver in a streptozotocin-induced rat model of type 1 diabetes to investigate whether long-term treatment with omega-3 PUFAs could induce CYP2E1-dependent oxidative stress and diabetic liver pathology. Significant hyperglycemia and lack of natural weight gain were observed in the diabetic rats compared to non-diabetic controls. A 2.5-fold increase in CYP2E1 expression (protein content and activity) was also observed in the diabetic rats. In addition, signs of oxidative stress were found in the liver of the diabetic rats. A significant increase in transaminases and GGT level in blood serum was also observed, which could indicate marked destruction of liver tissue. Diabetic dyslipidemia (increased triacylglycerol levels and decreased HDL-C levels) was found. Treatment of the diabetic animals with an omega-3-enriched pharmaceutical composition of PUFAs had no effect on CYP2E1 levels but contributed to a two-fold decrease in enzyme activity. The intensity of lipid peroxidation also remained close to the diabetic group. However, at the same time, antioxidant protection was provided by induction of antioxidant enzyme activity. Examination of the liver ultrastructure revealed no characteristic signs of diabetic pathology. However, omega-3 PUFAs did not normalize blood glucose levels and serum lipid profile. Thus, long-term treatment of diabetic rats with omega-3 PUFAs does not increase the risk of CYP2E1-dependent oxidative stress and development of liver pathology but prevents some diabetic ultrastructural damage to hepatocytes.

Relative energetics of CH3CH2O, CH3CHOH, and CH2CH2OH radical products from ethanol dehydrogenation

This study has examined the relative energetics of nine stationary points associated with the three different radical isomers generated by removing a H atom from ethanol at the O atom (ethoxy, CH₃CH₂O), the α C atom (CH₃CHOH), and the β C atom (CH₂CH₂OH). For the first time, CCSD(T) geometry optimizations and harmonic vibrational frequency computations with the cc-pVTZ and aug-cc-pVTZ basis sets have been carried out to characterize two unique minima for each isomer along with three transition state structures with C_s symmetry. Explicitly correlated CCSD(T) computations were also performed to estimate the relative energetics of these nine stationary points near the complete basis set limit. These benchmark results were used to assess the performance of various density functional theory (DFT) and wave function theory methods, and they will help guide method selection for future studies of alcohols and their radicals. The structures generated by abstracting H from the α C atom have significantly lower electronic energies (by at least 7 kcal mol^-1) than the CH₃CH₂O and CH₂CH₂OH radicals. Although previously reported as a minimum on the ground-state surface, the ²A″ C_s structure of the ethoxy radical was found to be a transition state in this study with MP2, CCSD(T), and a number of DFT methods. An implicit solvation model used in conjunction with DFT and MP2 methods did not qualitatively change the relative energies of the isomers, but the results suggest that the local minima for the CH₃CHOH and CH₂CH₂OH radicals could become more energetically competitive in condensed phase environments, such as liquid water and ethanol.

Therapeutic Potential of Quercetin: New Insights and Perspectives for Human Health

Quercetin (Que) and its derivatives are naturally occurring phytochemicals with promising bioactive effects. The antidiabetic, anti-inflammatory, antioxidant, antimicrobial, anti-Alzheimer's, antiarthritic, cardiovascular, and wound-healing effects of Que have been extensively investigated, as well as its anticancer activity against different cancer cell lines has been recently reported. Que and its derivatives are found predominantly in the Western diet, and people might benefit from their protective effect just by taking them via diets or as a food supplement. Bioavailability-related drug-delivery systems of Que have also been markedly exploited, and Que nanoparticles appear as a promising platform to enhance their bioavailability. The present review aims to provide a brief overview of the therapeutic effects, new insights, and upcoming perspectives of Que.

Protective Effect of Pomegranate (Punica granatum) Extract against Diabetic Changes in Adult Male Rat Liver: Histological Study

BACKGROUND

Diabetes mellitus could be result from disorders in insulin secretion or receptors, characterized by hyperglycemia. Natural antioxidants including pomegranate have hypoglycemic effect.

AIM OF THE WORK

The present research was designed to evaluate the possible protective role of pomegranate peel extract (PPE) against diabetic-induced hepatic complication.

MATERIALS AND METHODS

Forty-eight male Wistar rats, weighed 200-250 g and aged 3 months, were sorted into four groups: Group 1: Used as control, Group 2: Normal rats received PPE (200 mg/kg bw/day) given orally for 11 consecutive weeks. Group 3: Streptozotocin (STZ)-diabetic rats, injected with 55 mg/kg bw of STZ, and Group 4: Normal rats received PPE for 11 weeks and then rats were injected with STZ (55 mg/kg/bw). Effectiveness of the PPE was assessed by measuring serum glucose and histopathology of liver tissue. Liver enzymes were also assayed. PPE was found to control diabetic hyperglycemia and decrease in body weight. Histological examination showed that pretreatment with PPE provided preservation against diabetes-induced hepatic histological changes (necrotic and apoptosis).

RESULT

Alanine aminotransferase, alanine phosphatase, and aspartate aminotransferase levels were significantly elevated in Group 3 diabetics and decreased in Group 4 which confirmed histological finding.

CONCLUSION

This study confirmed the hypothesized possible protective effect of PPE against diabetic-induced histological and functional alteration of rat liver and advised its use by diabetic patients.

Effect of Linagliptin on the Ratio of Apoptosis Regulators in the Model of Non-Alcoholic Fatty Liver Disease in db/db Mice

We studied the effects of dipeptidyl peptidase 4 (DPP4) inhibitor linagliptin on the expression of apoptosis regulator proteins Bcl-2 and Bad in the liver of db/db mice with genetically determined obesity and type 2 diabetes mellitus. The mice received daily linagliptin or saline (placebo) by gavage from week 10 to week 18 of life. In the liver of non-treated mice, the area positively stained for Bad was greater than the area of Bcl-2 expression, which created the conditions for apoptosis activation in liver at this age. Administration of linagliptin decreased Bad stained area and increased Bcl-2 stained area in the liver cells. At the same time, Bad stained area remained larger in treated mice than the area of Bcl-2 expression area, which attested to partial normalization of pro- and antiapoptotic protein balance.

Molecular mechanism for the influence of gender dimorphism on alcoholic liver injury in mice

It is known that women develop alcoholic liver injury more rapidly and have a lower alcohol toxic threshold than men. However, the detailed molecular mechanisms remain unclear. The precise mechanism responsible for the sex difference needs to be determined. Female and male mice were given ethanol by intragastric infusion every day for 4 weeks. The pathological changes were detected by hematoxylin-eosin, Sirius red, oil red O, periodic acid-Schiff, and Hochest33258 staining in the liver of female and male mice. The related gene and protein expression of hepatocytes stress, proliferation and apoptosis, glycogen synthesis, lipid metabolism, and hepatic fibrosis were also systematically analyzed in the female and male mice. Livers from ethanol-treated female mice had more serious hepatocyte necrosis, liver fibrosis ( P < 0.01), substantial micro/macrovesicular steatosis ( p < 0.01), glycogen consumption ( p < 0.05), and hepatocytes apoptosis ( p < 0.05) than ethanol-treated male mice. The expression of heat shock protein 27 (HSP27), HSP70, proliferating cell nuclear antigen, B-cell lymphoma/leukemia-2 (Bcl-2), and phosphorylated signal transducer and activators of transcription 3 (p-STAT3) was higher in ethanol-treated male mice than ethanol-treated female mice ( P < 0.05 or P < 0.01). But, the expression of Bax (Bcl-2-associated X protein), Caspase 3, CYP2E1 (cytochrome P4502E1), and transforming growth factor βl had the contrary results. Our study suggested that ethanol treatment induced more expression of HSP27 and HSP70, faster hepatocyte proliferation, higher level of glycogen, and interleukin-6 signaling pathway activation, but less hepatocyte apoptosis and CYP2E1 expression in male mice than female mice, which could be helpful to understand the molecular mechanism for the influence of sex difference on alcoholic liver injury.

Establishment of a new animal model of azithromycin-induced liver injury and study the molecular pathological change during the process

The purpose of the present study is to establish a new animal model of azithromycin (AZ)-induced liver injury and study the molecular pathological change during the process. First, mice were respectively injected intraperitoneally with AZ of different high doses. Our results showed that 800 mg/kg AZ injection significantly induced liver injury in the mice, which reflected an ideal process of liver injury and repair. In this study, we analyzed the molecular pathological changes during the process by hematoxylin and eosin staining, immunohistochemistry, Western blot, and quantitative real-time reverse transcription polymerase chain reaction in the liver of mice at 0, 12, 24, 48, and 72 h after 800 mg/kg injection. Our results showed that the expression of heat shock protein 70, proliferating cell nuclear antigen, vascular endothelial growth factor, caspase 3, and cytochrome P450 2E1 were significantly differently expressed during liver injury induced by 800 mg/kg AZ in mice. Our results will be conducive for further study of the pathogenesis and prevention of drug-induced liver injury.

Translational Implications of the Alcohol-Metabolizing Enzymes, Including Cytochrome P450-2E1, in Alcoholic and Nonalcoholic Liver Disease

Fat accumulation (hepatic steatosis) in alcoholic and nonalcoholic fatty liver disease is a potentially pathologic condition which can progress to steatohepatitis (inflammation), fibrosis, cirrhosis, and carcinogenesis. Many clinically used drugs or some alternative medicine compounds are also known to cause drug-induced liver injury, which can further lead to fulminant liver failure and acute deaths in extreme cases. During liver disease process, certain cytochromes P450 such as the ethanol-inducible cytochrome P450-2E1 (CYP2E1) and CYP4A isozymes can be induced and/or activated by alcohol and/or high-fat diets and pathophysiological conditions such as fasting, obesity, and diabetes. Activation of these P450 isozymes, involved in the metabolism of ethanol, fatty acids, and various drugs, can produce reactive oxygen/nitrogen species directly and/or indirectly, contributing to oxidative modifications of DNA/RNA, proteins and lipids. In addition, aldehyde dehydrogenases including the mitochondrial low Km aldehyde dehydrogenase-2 (ALDH2), responsible for the metabolism of acetaldehyde and lipid aldehydes, can be inactivated by various hepatotoxic agents. These highly reactive acetaldehyde and lipid peroxides, accumulated due to ALDH2 suppression, can interact with cellular macromolecules DNA/RNA, lipids, and proteins, leading to suppression of their normal function, contributing to DNA mutations, endoplasmic reticulum stress, mitochondrial dysfunction, steatosis, and cell death. In this chapter, we specifically review the roles of the alcohol-metabolizing enzymes including the alcohol dehydrogenase, ALDH2, CYP2E1, and other enzymes in promoting liver disease. We also discuss translational research opportunities with natural and/or synthetic antioxidants, which can prevent or delay the onset of inflammation and liver disease.

IL-6 trans-signaling plays important protective roles in acute liver injury induced by acetaminophen in mice

Our study was undertaken to evaluate the important role of interleukin-6 (IL-6) trans-signaling in acetaminophen (AAP)-induced liver injury. A soluble gp130 protein (sgp130Fc) exclusively inhibits IL-6 trans-signaling, whereas an IL-6/soluble IL-6 receptor (sIL-6R) fusion protein (hyper-IL-6) mimics IL-6 trans-signaling. Using these tools, we investigated the role of IL-6 trans-signaling in AAP-induced liver injury. Blockade of IL-6 trans-signaling during AAP-induced liver injury remarkably increased the levels of serum aspartate aminotransferase and alanine aminotransferase; lowered the level of serum sIL-6R; aggravated liver injury; inhibited the expression of phosphorylation of STAT3 (pSTAT3), proliferating cell nuclear antigen, vascular endothelial growth factor, and glycogen synthesis; and induced the expression of Caspase3, cytochrome P450 2E1 (CYP2E1), and hepatocyte apoptosis in the liver of mice. In summary, our study suggested that IL-6 trans-signaling plays important protective roles by regulating the hepatocyte proliferation and apoptosis, angiogenesis, CYP2E1 expression, and glycogen metabolism during AAP-induced liver injury in mice.

The role of CYP2E1 in alcohol metabolism and sensitivity in the central nervous system

Ethanol consumption has effects on the central nervous system (CNS), manifesting as motor incoordination, sleep induction (hypnosis), anxiety, amnesia, and the reinforcement or aversion of alcohol consumption. Acetaldehyde (the direct metabolite of ethanol oxidation) contributes to many aspects of the behavioral effects of ethanol. Given acetaldehyde cannot pass through the blood brain barrier, its concentration in the CNS is primarily determined by local production from ethanol. Catalase and cytochrome P450 2E1 (CYP2E1) represent the major enzymes in the CNS that catalyze ethanol oxidation. CYP2E1 is expressed abundantly within the microsomes of certain brain cells and is localized to particular brain regions. This chapter focuses on the discussion of CYP2E1 in ethanol metabolism in the CNS, covering topics including how it is regulated, where it is expressed and how it influences sensitivity to ethanol in the brain.

Genetic polymorphisms in CYP2E1: association with schizophrenia susceptibility and risperidone response in the Chinese Han population

Background

CYP2E1 is a member of the cytochrome P450 superfamily, which is involved in the metabolism and activation of both endobiotics and xenobiotics. The genetic polymorphisms of CYP2E1 gene (Chromosome 10q26.3, Accession Number NC_000010.10) are reported to be related to the development of several mental diseases and to be involved in the clinical efficacy of some psychiatric medications. We investigated the possible association of CYP2E1 polymorphisms with susceptibility to schizophrenia in the Chinese Han Population as well as the relationship with response to risperidone in schizophrenia patients.

Methods

In a case-control study, we identified 11 polymorphisms in the 5' flanking region of CYP2E1 in 228 schizophrenia patients and 384 healthy controls of Chinese Han origin. From among the cases, we chose 130 patients who had undergone 8 weeks of risperidone monotherapy to examine the relationship between their response to risperidone and CYP2E1 polymorphisms. Clinical efficacy was assessed using the Brief Psychiatric Rating Scale (BPRS).

Results

Statistically significant differences in allele or genotype frequencies were found between cases and controls at rs8192766 (genotype p = 0.0048, permutation p = 0.0483) and rs2070673 (allele: p = 0.0018, permutation p = 0.0199, OR = 1.4528 95%CI = 1.1487–1.8374; genotype: p = 0.0020, permutation p = 0.0225). In addition, a GTCAC haplotype containing 5 SNPs (rs3813867, rs2031920, rs2031921, rs3813870 and rs2031922) was observed to be significantly associated with schizophrenia (p = 7.47E-12, permutation p<0.0001). However, no association was found between CYP2E1 polymorphisms/haplotypes and risperidone response.

Conclusions

Our results suggest that CYP2E1 may be a potential risk gene for schizophrenia in the Chinese Han population. However, polymorphisms of the CYP2E1 gene may not contribute significantly to individual differences in the therapeutic efficacy of risperidone. Further studies in larger groups are warranted to confirm our results.

Physiologically Based Pharmacokinetic (PBPK) Modeling of Metabolic Pathways of Bromochloromethane in Rats

Bromochloromethane (BCM) is a volatile compound and a by-product of disinfection of water by chlorination. Physiologically based pharmacokinetic (PBPK) models are used in risk assessment applications. An updated PBPK model for BCM is generated and applied to hypotheses testing calibrated using vapor uptake data. The two different metabolic hypotheses examined are (1) a two-pathway model using both CYP2E1 and glutathione transferase enzymes and (2) a two-binding site model where metabolism can occur on one enzyme, CYP2E1. Our computer simulations show that both hypotheses describe the experimental data in a similar manner. The two pathway results were comparable to previously reported values (V_max⁡ = 3.8 mg/hour, K_m = 0.35 mg/liter, and k_GST = 4.7 /hour). The two binding site results were V_max⁡1 = 3.7 mg/hour, K_m⁡1 = 0.3 mg/hour, CL₂ = 0.047 liter/hour. In addition, we explore the sensitivity of different parameters for each model using our obtained optimized values.

Systematical analysis of impacts of heat stress on the proliferation, apoptosis and metabolism of mouse hepatocyte

Heat stress will stimulate cells of living organisms to generate heat shock proteins (Hsps). In the mouse liver, impacts of heat stress on hepatocyte proliferation, apoptosis and metabolism have not been studied systematically at different temperatures. In this research, the test mice were heated to 40, 42, 44 and 46°C, respectively, for 20 min and recovered at room temperature for 8 h in normal feeding conditions; the control animals were kept at room temperature without heat stress. The expression levels of Hsp70, Pcna, Bax, Bcl2, cytochrome P450 1A2 (CYP1A2), CYP2E1 and analog of CYP3A4 (not reported in mouse before), the parameters reflecting stress strength, cell proliferation, apoptosis and metabolism, were detected by western blotting, immunohistochemistry and semi-quantitative RT-PCR in test and control mice. Haematoxylin-eosin (H&E) staining and TUNEL analysis were further used to study the impacts of heat stress at different temperatures on hepatocellular necrosis and apoptosis. Serum AST and ALT levels, the markers of liver injury, were measured after heat stress at different temperatures. The data show that Hsp70 expression was significantly increased when temperature increased (P < 0.05). At lower temperatures (40 or 42°C), expression of Pcna, CYP1A2 and analog of CYP3A4 were considerably increased (P < 0.05) while hepatocyte necrosis and apoptosis were not induced (P > 0.05). At higher temperatures (44 or 46°C), expression of Pcna was decreased while hepatocyte necrosis and apoptosis were induced (P < 0.05). Expressions of CYP1A2 and analog of CYP3A4 were decreased especially at 46°C (P < 0.05). Expression of CYP2E1 could not be detected to increase at 40°C but was at high levels at 42, 44 and 46°C (P < 0.05). Expressions of AST and ALT were not different between the test mice and control mice at 40°C while they were significantly higher in the test mice than those in the control mice at 42 (P < 0.05), 44 and 46°C (P < 0.01). In conclusion, heat stress at lower temperatures promotes hepatocyte proliferation and improves the metabolic efficiency in mouse liver while heat stress at higher temperatures inhibits hepatocyte proliferation, promotes hepatocyte apoptosis and induces hepatocyte necrosis. This may give a hint to understanding human liver injury in high temperatures. Moreover, it is the first time that the analog of CYP3A4 was detected in mouse hepatocellular cytoplasm. It is worthwhile to dissect its function in future work.