Cytochrome P2E1 (CYP2E1) Gene Polymorphism as a Potential Prognostic Biomarker in Colorectal Cancer

BACKGROUND

Colon cancer is the most common type of gastrointestinal cancer. Genetic factors have been shown to have a role in the development of colorectal cancers. The aim of this study was to assess the expression of Cytochrome P2E1 (CYP2E1) gene polymorphism as a potential prognostic biomarker in the diagnosis, treatment, and prognosis evaluation of patients with colorectal cancer.

METHODS

in this cross-sectional study, all of our 100 patients with colorectal cancer who underwent surgical operation were included. DNA was extracted from the tumor specimens to assess Cytochrome P2E1 (CYP2E1) Gene polymorphism by Conventional-PCR. RFLP-PCR method was used for RsaI polymorphism evaluation. Patients' characteristics were also recorded and their associations with CYP2E1 were assessed.

RESULTS

One hundred tumor specimens were assessed. In total, 88 had wild-type, 8 had purely a 96 bp insertion in CYP2E1, and 4 were partially mutated by a single allele insertion. Generally, 10% of samples had positive results for the RsaI polymorphism. There were no statistically significant associations between CYP2E1 gene polymorphism and number of lymph nodes removed during the operation (P = 0.353), number of positive lymph nodes (P = 0.668), tumor specificity including mucinous or non-mucinous (P = 0.053), tumor invasion (P = 0.074), grading (P = 0.898), differentiation (P = 0.941), tumor location (P = 0.42) or staging (P = 0.182).

CONCLUSION

There was no association between RsaI type CYP2E1 polymorphism and colorectal cancer risk. Our study does not support the use of this biomarker to evaluate the prognosis of colon cancer.

Chronotoxicity of Acrylamide in Mice Fed a High-Fat Diet: The Involvement of Liver CYP2E1 Upregulation and Gut Leakage

Acrylamide (ACR) is produced under high-temperature cooking of carbohydrate-rich foods via the Maillard reaction. It has been reported that ACR has hepatic toxicity and can induce liver circadian disorder. A high fat diet (HFD) could dysregulate liver detoxification. The current study showed that administration of ACR (100 mg/kg) reduced the survival rate in HFD-fed mice, which was more pronounced when treated during the night phase than during the day phase. Furthermore, ACR (25 mg/kg) treatment could cause chronotoxicity in mice fed a high-fat diet, manifested as more severe mitochondrial damage of liver during the night phase than during the day phase. Interestingly, HFD induced a higher CYP2E1 expressions for those treated during the night phase, leading to more severe DNA damage. Meanwhile, the expression of gut tight junction proteins also significantly decreases at night phase, leading to the leakage of LPSs and exacerbating the inflammatory response at night phase. These results indicated that a HFD could induce the chronotoxicity of ACR in mice liver, which may be associated with increases in CYP2E1 expression in the liver and gut leak during the night phase.

The CYP2E1 inhibitor Q11 ameliorates LPS-induced sepsis in mice by suppressing oxidative stress and NLRP3 activation

Sepsis is an infection-induced, multi-organ system failure with a pathophysiology related to inflammation and oxidative stress. Increasing evidence indicates that cytochrome P450 2E1 (CYP2E1) is involved in the incidence and development of inflammatory diseases. However, a role for CYP2E1 in lipopolysaccharide (LPS)-induced sepsis has not been completely explored. Here we use Cyp2e1 knockout (cyp2e1-/-) mice to determine if CYP2E1 could be a therapeutic target for sepsis. We also evaluated the ability of Q11, a new specific CYP2E1 inhibitor, to prevent and ameliorate LPS-induced sepsis in mice and in LPS-treated J774A.1 and RAW264.7 cells. Cyp2e1 deletion significantly reduced hypothermia, multi-organ dysfunction and histological abnormalities in LPS-treated mice; consistent with this finding, the CYP2E1 inhibitor Q11 significantly prolonged the survival time of septic mice and ameliorated multi-organ injury induced by LPS. CYP2E1 activity in liver correlated with indicators of multi-organ injury, such as the level of lactate dehydrogenase (LDH) and blood urea nitrogen (BUN) (P<0.05). Q11 significantly suppressed the expression of NLRP3 in tissues after LPS injection; in vitro studies revealed that activation of NLRP3 signaling and increase of ROS was attenuated by Q11 in LPS-stimulated macrophages, which was reflected by reduced expression of caspase-1 and formation of ASC specks. Overall, our results indicate that Q11 improves the survival of mice with LPS-induced sepsis and attenuates sepsis-induced multiple-organ injury, suggesting that CYP2E1 could be a therapeutic target for sepsis.

CYP2E1 C-1054T and 96-bp I/D genetic variations and risk of gestational diabetes mellitus in chinese women: a case-control study

BACKGROUND

Cytochrome P450 2E1 (CYP2E1) plays a key role in the metabolism of xenobiotic and endogenous low-molecular-weight compounds. This study aimed to determine if the genetic variations of 96-bp insertion/deletion (I/D) and C-1054T (rs2031920) in CYP2E1 were associated with the risk of gestational diabetes mellitus (GDM).

METHODS

CYP2E1 polymorphisms were genotyped in a case-control study of 1,134 women with uncomplicated pregnancies and 723 women with GDM. The effects of genotype on the clinical, metabolic, and oxidative stress indices were assessed.

RESULTS

The CYP2E1 C-1054T variant was associated with an increased risk of GDM based on the genotype, recessive, dominant, and allele genetic models (P < 0.05). The TT + CT genotype remained a significant predictive factor for GDM risk after correcting for maternal age and pre-pregnancy body mass index (OR = 1.277, 95% CI: 1.042-1.563, P = 0.018). Moreover, fasting insulin concentrations and homeostatic model assessment of insulin resistance were significantly higher in GDM patients carrying the T allele than in those with the CC genotype (P < 0.05). Furthermore, the combined genotype II + ID/TT + CT of the 96-bp I/D and C-1054T polymorphisms further increased the risk of GDM when the combined genotype DD/CC was set as the reference category (OR = 1.676, 95% CI: 1.182-2.376, P = 0.004).

CONCLUSIONS

The T allele of the C-1054T polymorphism and its combination with the I allele of the 96-bp I/D variation in CYP2E1 are associated with an increased risk of GDM in the Chinese population. The - 1054T allele may be associated with more serious insulin resistance in patients.

Phenylalanine Residues in the Active Site of CYP2E1 Participate in Determining the Binding Orientation and Metabolism-Dependent Genotoxicity of Aromatic Compounds

The composition of amino acids forming the active site of a CYP enzyme is impactful in its substrate selectivity. For CYP2E1, the role of PHE residues in the formation of effective binding orientations for its aromatic substrates remains unclear. In this study, molecular docking and molecular dynamics analysis were performed to reflect the interactions between PHEs in the active site of human CYP2E1 and various aromatic compounds known as its substrates. The results indicated that the orientation of 1-methylpyrene (1-MP) in the active site was highly determined by the presence of PHEs, PHE478 contributing to the binding free energy most significantly. Moreover, by building a random forest model the relationship between each of 19 molecular descriptors of polychlorinated biphenyl (PCB) compounds (from molecular docking, quantum mechanics, and physicochemical properties) and their human CYP2E1-dependent mutagenicityas established mostly in our lab, was investigated. The presence of PHEs did not appear to significantly modify the electronic or structural feature of each bound ligand (PCB), instead, the flexibility of the conformation of PHEs contributed substantially to the effective binding energy and orientation. It is supposed that PHE residues adjust their own conformation to permit a suitablly shaped cavity for holding the ligand and forming its orientation as favorable for a biochemical reaction. This study has provided some insights into the role of PHEs in guiding the interactive adaptation of the active site of human CYP2E1 for the binding and metabolism of aromatic substrates.

Synergistic effects of combined treatment of 1,2-dichloroethane and high-dose ethanol on liver damage in mice and the related mechanisms

Our previous studies have shown that the metabolism of 1,2-dichloroethane (1,2-DCE) mediated by CYP2E1 could result in oxidative damage in the liver of mice. In the current study, we further investigated the effects of combined treatment with 1,2-DCE and high dose ethanol on liver and the mechanisms since both of them can be metabolized by CYP2E1 in the liver. There are several novel findings in the current study. First, combined treatment of mice with 1,2-DCE and high-dose ethanol could synergistically upregulate both protein and mRNA levels of CYP2E1, which might aggravate liver damage through CYP2E1-mediated oxidative stress. Second, the combined treatment could also synergistically trigger NLRP3 inflammasome activation and inflammatory responses in the liver. Third, the combined treatment synergistically upregulated the antioxidant defence systems in response to oxidative stress, however the compensatory mechanisms of antioxidant defence systems appeared to be insufficient to protect liver damage in the mice. Finally, the upregulated CYP2E1 expression was confirmed by using its specific inhibitor to play the crucial roles in liver damage in the mice during the combined treatment.

Indole-3-carbinol ameliorated the thioacetamide-induced hepatic encephalopathy in rats

Indole-3-carbinol (I3C) is reported to have hepatic and neuroprotective properties. However, the I3C role in the protection of the liver and brain in the pathological condition of hepatic encephalopathy has not been investigated. Therefore, in the present study, we have assessed the hepatic and neuroprotective roles of I3C against thioacetamide (TAA)- induced hepatic encephalopathy in Wistar rats. TAA (300mg/kg) was intraperitoneally administered to Wistar rats to induce hepatic encephalopathy. The elevated levels of ammonia in the blood, liver, and brain were substantially lowered by I3C treatment (25, 50, and 100mg/kg, oral, 7 days). I3C significantly ameliorated the TAA-induced liver dysfunction by decreasing the alanine transaminase, aspartate transaminase, and alkaline phosphatase enzymes and reduced the elevated cytochrome P4502E1 (CYP2E1) activity in the liver and brain. Further, I3C alleviated mitochondrial dysfunction and oxidative stress in the brain. I3C treatment improved the anti-inflammatory cytokine interleukin (IL)-10 while reducing inflammatory cytokines such as tumor necrosis factor-1 and IL-6 in hepatic encephalopathy rats. I3C reduced the levels of apoptotic indicators mediated by the mitochondria, including cytochrome c, caspase 9, and caspase 3. Concurrently, I3C mitigated the liver and brain histological abnormalities in hepatic encephalopathy rats. Therefore, the present study concluded that the I3C protected the liver and brain from TAA-induced hepatic encephalopathy injury by inhibiting CYP2E1 enzyme activity and decreasing ammonia, oxidative stress, inflammation, and apoptosis. The present study provides preclinical validation of I3C use as hepatic and neuroprotective for hepatic encephalopathy management.

Generation and Characterization of CYP2E1-Overexpressing HepG2 Cells to Study the Role of CYP2E1 in Hepatic Hypoxia-Reoxygenation Injury

The mechanisms of hepatic ischemia/reperfusion (I/R) injury, which occurs during liver transplantation or surgery, are poorly understood. The purpose of the current study was to generate and characterize a HepG2 cell line with a stable overexpression of CYP2E1 to investigate the role of the enzyme in hypoxia/reperfusion (H/R) injury in an ex vivo setting. GFP-tagged CYP2E1 and control clones were developed, and their gene expression and protein levels of GFP and CYP2E1 were determined using RT-PCR and ELISA/Western blot analysis, respectively. Additionally, the CYP2E1 catalytic activity was determined by UPLC-MS/MS analysis of 6-hydroxychlorzoxazone formed from the chlorzoxazone substrate. The CYP2E1 and control clones were subjected to hypoxia (10 h) and reoxygenation (0.5 h), and cell death and reactive oxygen species (ROS) generation were quantitated using LDH and flow cytometry, respectively. Compared with the control clone, the selected CYP2E1 clone showed a 720-fold increase in CYP2E1 expression and a prominent band in the western blot analysis, which was associated with a 150-fold increase in CYP2E1 catalytic activity. The CYP2E1 clone produced 2.3-fold more ROS and 1.9-fold more cell death in the H/R model. It is concluded that the constitutive CYP2E1 in the liver may play a detrimental role in hepatic I/R injury.

Association of Interactions between Metabolic 'Caretaker' Genes, p53, MDM2, and Tobacco Use with the Risk of Oral Cancer: A Multifactor Dimensionality Reduction Approach

BACKGROUND

The present study investigated the association of interactions between gene polymorphisms in metabolic 'caretaker' genes (Phase I: CYP1A1, CYP2E1; Phase II: GSTM1, GSTT1), the cell cycle regulatory gene, p53, along with its negative controller, MDM-2, and the environment variable (tobacco). A nonparametric model, multifactor dimensionality reduction (MDR), was applied to analyse these interactions.

MATERIALS AND METHODS

This case-control study was carried out on 242 subjects. Genomic DNA was extracted from peripheral blood lymphocytes.11 gene variants with an exposure variable (tobacco use) were analysed using MDR to identify the best locus model for gene-gene and gene-environment interactions. Statistical significance was evaluated using a 1000-fold permutation test using MDR permutation testing software (version 1.0 beta 2). The value of p<0.05 was considered statistically significant.

RESULTS

The best three-locus model for gene-gene interaction included two of the p53 gene polymorphisms; rs17878362 (intron 3) and rs1042522 (exon 4) and rs6413432 in the Phase I gene, CYP2E1(DraI). The three-locus model to evaluate the gene-environment interaction included two intronic polymorphisms of the p53 gene, that is, rs17878362 (intron 3) and rs1625895 (intron 6), and rs4646903 in the Phase I gene CYP1A1*2C. The interaction graphs revealed independent main effects of the tobacco and p53 polymorphism, rs1042522 (exon 4), and a significant additive interaction effect between rs17878362 (intron 3) and rs1042522 (exon 4).

CONCLUSIONS

The nonparametric approach highlighted the potential role of tobacco use and variations in the p53 gene as significant contributors to oral cancer risk. The findings of the present study will help implement preventive strategies in both tobacco use and screening using a molecular pathology approach.

Stabilization of glutathione redox dynamics and CYP2E1 by green synthesized Moringa oleifera-mediated zinc oxide nanoparticles against acrylamide induced hepatotoxicity in rat model: Morphometric and molecular perspectives

The terrible reality is that acrylamide (AA) is a common food contaminant found in a wide variety of commonly consumed foods. This research involves the advancement of a more dependable technique for the bio-fabrication of zinc oxide nanoparticles (ZNPs) through the green method using Moringa Oleifera extract (MO-ZNPs) as an efficient chelating agent for acrylamide (AA). The effects of AA on glutathione redox dynamics, liver function, lipid profile, and zinc residues in Sprague Dawley rats are investigated. Finally, the microarchitecture and immunohistochemical staining of Caspase-3 and CYP2E1 were determined in the liver tissue of rats. Four separate groups, including control, MO-ZNPs (10 mg/kg b.wt), AA (20 mg/kg b.wt), and AA + MO-ZNPs for 60 days. The results revealed a suppressed activity of glutathione redox enzymes (GSH, GPX,and GSR) on both molecular and biochemical levels. Also, AA caused elevated liver enzymes, hepatosomatic index, and immunohistochemical staining of caspase-3 and CYP2E1 expression. MO-ZNPs co-treatment, on the other hand, stabilized glutathione-related enzyme gene expression, normalized hepatocellular enzyme levels, and restored hepatic tissue microarchitectures. It could be assumed that MO-ZNPs is a promising hepatoprotective molecule for alleviating AA-induced hepatotoxicity. We witnessed changes in glutathione redox dynamics to be restorative. Glutathione and cytochrome P450 2E1 play crucial roles in AA detoxification, so maintaining a healthy glutathione redox cycle is necessary for disposing of AA toxicity.

CYP2E1 overexpression protects COS-7 cancer cells against ferroptosis

Ferroptosis is a recently described form of regulated cell death initiated by the iron-mediated one-electron reduction of lipid hydroperoxides (LOOH). Cytochrome P450 2E1 (CYP2E1) induction, a consequence of genetic polymorphisms or/and gene induction by xenobiotics, may promote ferroptosis by contributing to the cellular pool of LOOH. However, CYP2E1 induction also increases the transcription of anti-ferroptotic genes that regulate the activity of glutathione peroxidase 4 (GPX4), the main ferroptosis inhibitor. Based on the above, we hypothesize that the impact of CYP2E1 induction on ferroptosis depends on the balance between pro- and anti-ferroptotic pathways triggered by CYP2E1. To test our hypothesis, ferroptosis was induced with class 2 inducers (RSL-3 or ML-162) in mammalian COS-7 cancer cells that don't express CYP2E1 (Mock cells), and in cells engineered to express human CYP2E1 (WT cells), and the impact on viability, lipid peroxidation and GPX4 was assessed. CYP2E1 overexpression protected COS-7 cancer cells against ferroptosis, evidenced by an increase in the IC50 and a decrease in lipid ROS in WT versus Mock cells after exposure to class 2 inducers. CYP2E1 overexpression produced an 80% increase in the levels of the GPX4 substrate glutathione (GSH). Increasing GSH in Mock cells protected cells against ferroptosis by ML-162. Depleting GSH, or inhibiting Nrf2 in WT cells reverted the protective effect mediated by CYP2E1, causing a decrease in the IC50 and an increase in lipid ROS after exposure to ML-162. These results show that CYP2E1 overexpression protects COS-7 cancer cells against ferroptosis, an effect probably mediated by Nrf2-dependent GSH induction.

Transgenic Zebrafish Expressing Rat Cytochrome P450 2E1 (CYP2E1): Augmentation of Acetaminophen-Induced Toxicity in the Liver and Retina

Metabolic activation is the primary cause of chemical toxicity including hepatotoxicity. Cytochrome P450 2E (CYP2E) is involved in this process for many hepatotoxicants, including acetaminophen (APAP), one of the most common analgesics and antipyretics. Although the zebrafish is now used as a model for toxicology and toxicity tests, the CYP2E homologue in zebrafish has not been identified yet. In this study, we prepared transgenic zebrafish embryos/larvae expressing rat CYP2E1 and enhanced green fluorescent protein (EGFP) using a β-actin promoter. Rat CYP2E1 activity was confirmed by the fluorescence of 7-hydroxycoumarin (7-HC), a metabolite of 7-methoxycoumarin that was specific for CYP2 in transgenic larvae with EGFP fluorescence (EGFP [+]) but not in transgenic larvae without EGFP fluorescence (EGFP [-]). APAP (2.5 mM) caused reduction in the size of the retina in EGFP [+] larvae but not in EGFP [-] larvae, while APAP similarly reduced pigmentation in both larvae. APAP at even 1 mM reduced the liver size in EGFP [+] larvae but not in EGFP [-] larvae. APAP-induced reduction of liver size was inhibited by N-acetylcysteine. These results suggest that rat CYP2E1 is involved in some APAP-induced toxicological endpoints in the retina and liver but not in melanogenesis of the developing zebrafish.

Molecular mechanism for the involvement of CYP2E1/NF-κB axis in bedaquiline-induced hepatotoxicity

Bedaquiline (BDQ) is a new class of anti-tubercular (anti-TB) drugs and is currently reserved for multiple drug resistance (MDR-TB). However, after receiving fast-track approval, its clinical studies demonstrate that its treatment is associated with hepatotoxicity and labeled as 'boxed warning' by the USFDA. No data is available on BDQ to understand the mechanism for drug-induced liver injury (DILI), a severe concern for therapeutic failure/unbearable tolerated toxicities leading to drug resistance. Therefore, we performed mechanistic studies to decipher the potential of BDQ at three dose levels (80 to 320 mg/kg) upon the repeated dose administration orally using a widely used mice model for TB. Results of BDQ treatment at the highest dose level showed that substantial increase of hepatic marker enzymes (SGPT and SGOT) in serum, oxidative stress marker levels (MDA and GSH) in hepatic tissue, and pro-inflammatory cytokine levels (TNF-α, IL-6, and IL-1β) in serum compared to control animals. Induction of liver injury situation was further evaluated by Western blotting for various protein expressions linked to oxidative stress (SOD, Nrf2, and Keap1), inflammation (NF-ĸB and IKKβ), apoptosis (BAX, Bcl-2, and Caspase-3) and drug metabolism enzymes (CYP3A4 and CYP2E1). The elevated plasma level of BDQ and its metabolite (N-desmethyl BDQ) were observed, corresponding to BDQ doses. Histopathological examination and SEM analysis of the liver tissue corroborate the above-mentioned findings. Overall results suggest that BDQ treatment-associated generation of its cytotoxic metabolite could act on CYP2E1/NF-kB pathway to aggravate the condition of oxidative stress, inflammation, and apoptosis in the liver and precipitating hepatotoxicity.

Effects of chronic cirrhosis induced by intraperitoneal thioacetamide injection on the protein content and Michaelis-Menten kinetics of cytochrome P450 enzymes in the rat liver microsomes

Chronic intraperitoneal injection of thioacetamide (TAA) in rats has been used as an animal model of human cirrhosis to study the effects of the disease on drug metabolism. However, TAA inhibits P450 enzymes directly and independently of cirrhosis. We investigated the effects of chronic cirrhosis in rats, induced by 10 weeks of intraperitoneal TAA, on the P450 enzymes after a 10-day washout period to eliminate TAA. Liver histology and serum biomarkers of hepatic function confirmed cirrhosis in all animals. Microsomal total P450 content, P450 reductase activity and ethoxycoumarin O-deethylase activity, a general marker of P450 activity, were significantly reduced by 30%-50% in cirrhotic animals. Additionally, the protein content and Michaelis-Menten kinetics of the activities of CYP2D, CYP2E1 and CYP3A were investigated. Whereas cirrhosis reduced the microsomal protein contents of CYP2D and CYP3A by 70% and 30%, respectively, the protein contents of CYP2E1 were not affected. However, the activities of all the tested isoenzymes were substantially lower in the cirrhotic livers. It is concluded that the TAA model of cirrhosis that incorporates a 10-day washout period after intraperitoneal injection of the chemical to rats produces isoenzyme-selective reductions in the P450 proteins or activities, which are independent of the direct inhibitory effects of TAA.

Elucidation of Natural Components of Gardenia thunbergia Thunb. Leaves: Effect of Methanol Extract and Rutin on Non-Alcoholic Fatty Liver Disease

The rising prevalence of non-alcoholic fatty liver disease NAFLD has strained the healthcare system. Natural products could solve this problem, so the current study focused on the impact of G. thunbergia Thunb. against this ailment. LC-ESI-MS/MS revealed the phytochemical profile of the methanol extract from Gardenia thunbergia leaves (GME). Forty-eight compounds were tentatively identified, and stigmasterol, fucosterol, ursolic acid, and rutin were isolated. The separation of the last three compounds from this plant had not before been achieved. The anti-NAFLD effect of the methanol extract of the leaves of G. thunbergia, and its major metabolite, rutin, was assessed in mice against high-fructose diet (HFD)-induced obesity. Male mice were allocated into nine groups: (1) saline (control), (2) 30% fructose (diseased group), (3) HFD, and 10 mg/kg of simvastatin. Groups 4-6 were administered HFD and rutin 50, 75, and 100 mg/kg. Groups (7-9) were administered HFD and methanol extract of leaves 100, 200, and 300 mg/kg. Methanol extract of G. thunbergia leaves at 200 mg/kg, and rutin at 75 mg/kg significantly reduced HFD-induced increments in mice weight and hepatic damage indicators (AST and ALT), steatosis, and hypertrophy. The levels of total cholesterol, LDL-C, and triglycerides in the blood decreased. In addition, the expressions of CYP2E1, JNK1, and iNOS in the diseased mice were downregulated. This study found that GME and rutin could ameliorate NAFLD in HFD-fed mice, with results comparable to simvastatin, validating G. thunbergia's hepatoprotective effects.

Toxic effect of carpet dust on the biochemical indices and histological structure of the lung in rats: the potential role of cytochrome P450 2E1 and extracellular signal-regulated kinase/mitogen-activated protein kinase pathways

Background: Carpet dust exposure in the carpet industry causes various respiratory hazards that lead to permanent loss of lung function. This study investigated the potentially toxic effects of knotted and tufted carpet dust on rat lungs and the possible involvement of cytochrome P450 2E1 (CYP2E1) and extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathways in the induced toxicity, as well as histological changes in the lung induced by carpet dust.Methods: This study divided 48 adult rats into six groups: group I was the control group, group II (vehicle group) received phosphate buffer saline (50 µL/rat), groups III and IV received knotted dust (2.5 and 5 mg/kg, respectively), and groups V and VI received tufted dust (2.5 and 5 mg/kg, respectively). All treatments were intranasally administered once a day for 7 days.Results: Both dust types significantly decreased the lung content of GSH compared with the control. Significantly elevated malondialdehyde (MDA) and nitric oxide (NO) lung contents were observed with an increased CYP2E1, interleukin (IL)-6, nuclear factor kappa B (NF-κβ), and ERK/MAPK. The histological lung structure was moderately affected with a moderately increased number of CD68-positive macrophages in the lung parenchyma of knotted dust-exposed rats, whereas tufted dust exposure severely affected the lung tissue with significantly increased CD68-positive macrophages.Conclusions: Carpet dust exposure could induce oxidative stress and inflammatory response in the lung tissue via induction of CYP2E1 that stimulates ERK/MAPK signalling pathway proteins, resulting in elevated MDA, NO and IL-6 levels in the lung tissue with suppressed GSH content. Tufted dust could possess a more toxic response than knotted ones.

Nrf2-/- regulated lung DNA demethylation and CYP2E1 DNA methylation under PM2.5 exposure

Cytochrome P450 (CYP450) can mediate fine particulate matter (PM_2.5) exposure leading to lung injury. Nuclear factor E2-related factor 2 (Nrf2) can regulate CYP450 expression; however, the mechanism by which Nrf2^-/- (KO) regulates CYP450 expression via methylation of its promoter after PM_2.5 exposure remains unclear. Here, Nrf2^-/- (KO) mice and wild-type (WT) were placed in a PM_2.5 exposure chamber (PM) or a filtered air chamber (FA) for 12 weeks using the real-ambient exposure system. The CYP2E1 expression trends were opposite between the WT and KO mice following PM_2.5 exposure. After exposure to PM_2.5, CYP2E1 mRNA and protein levels were increased in WT mice but decreased in KO mice, and CYP1A1 expression was increased after exposure to PM_2.5 in both WT and KO mice. CYP2S1 expression decreased after exposure to PM_2.5 in both the WT and KO groups. We studied the effect of PM_2.5 exposure on CYP450 promoter methylation and global methylation levels in WT and KO mice. In WT and KO mice in the PM_2.5 exposure chamber, among the methylation sites examined in the CYP2E1 promoter, the CpG2 methylation level showed an opposite trend with CYP2E1 mRNA expression. The same relationship was evident between CpG3 unit methylation in the CYP1A1 promoter and CYP1A1 mRNA expression, and between CpG1 unit methylation in the CYP2S1 promoter and CYP2S1 mRNA expression. This data suggests that methylation of these CpG units regulates the expression of the corresponding gene. After exposure to PM_2.5, the expression of the DNA methylation markers ten-eleven translocation 3 (TET3) and 5-hydroxymethylcytosine (5hmC) was decreased in the WT group but significantly increased in the KO group. In summary, the changes in CYP2E1, CYP1A1, and CYP2S1 expression in the PM_2.5 exposure chamber of WT and Nrf2^-/- mice might be related to the specific methylation patterns in their promoter CpG units. After exposure to PM_2.5, Nrf2 might regulate CYP2E1 expression by affecting CpG2 unit methylation and induce DNA demethylation via TET3 expression. Our study revealed the underlying mechanism for Nrf2 to regulate epigenetics after lung exposure to PM_2.5.

Phenylpropionic acid produced by gut microbiota alleviates acetaminophen-induced hepatotoxicity

The gut microbiota affects hepatic drug metabolism. However, gut microbial factors modulating hepatic drug metabolism are largely unknown. In this study, using a mouse model of acetaminophen (APAP)-induced hepatotoxicity, we identified a gut bacterial metabolite that controls the hepatic expression of CYP2E1 that catalyzes the conversion of APAP to a reactive, toxic metabolite. By comparing C57BL/6 substrain mice from two different vendors, Jackson (6J) and Taconic (6N), which are genetically similar but harbor different gut microbiotas, we established that the differences in the gut microbiotas result in differential susceptibility to APAP-induced hepatotoxicity. 6J mice exhibited lower susceptibility to APAP-induced hepatotoxicity than 6N mice, and such phenotypic difference was recapitulated in germ-free mice by microbiota transplantation. Comparative untargeted metabolomic analysis of portal vein sera and liver tissues between conventional and conventionalized 6J and 6N mice led to the identification of phenylpropionic acid (PPA), the levels of which were higher in 6J mice. PPA supplementation alleviated APAP-induced hepatotoxicity in 6N mice by lowering hepatic CYP2E1 levels. Moreover, PPA supplementation also reduced carbon tetrachloride-induced liver injury mediated by CYP2E1. Our data showed that previously known PPA biosynthetic pathway is responsible for PPA production. Surprisingly, while PPA in 6N mouse cecum contents is almost undetectable, 6N cecal microbiota produces PPA as well as 6J cecal microbiota in vitro, suggesting that PPA production in the 6N gut microbiota is suppressed in vivo. However, previously known gut bacteria harboring the PPA biosynthetic pathway were not detected in either 6J or 6N microbiota, suggesting the presence of as-yet-unidentified PPA-producing gut microbes. Collectively, our study reveals a novel biological function of the gut bacterial metabolite PPA in the gut-liver axis and presents a critical basis for investigating PPA as a modulator of CYP2E1-mediated liver injury and metabolic diseases.

Evaluation of Supervised Machine Learning Algorithms and Computational Structural Validation of Single Nucleotide Polymorphisms Related to Acute Liver Injury with Paracetamol

AIMS

To identify single nucleotide polymorphisms (SNPs) of paracetamol-metabolizing enzymes that can predict acute liver injury.

BACKGROUND

Paracetamol is a commonly administered analgesic/antipyretic in critically ill and chronic renal failure patients and several SNPs influence the therapeutic and toxic effects.

OBJECTIVE

To evaluate the role of machine learning algorithms (MLAs) and bioinformatics tools to delineate the predictor SNPs as well as to understand their molecular dynamics.

METHODS

A cross-sectional study was undertaken by recruiting critically ill patients with chronic renal failure and administering intravenous paracetamol as a standard of care. Serum concentrations of paracetamol and the principal metabolites were estimated. Following SNPs were evaluated: CYP2E1*2, CYP2E1_-1295G>C, CYP2D6*10, CYP3A4*1B, CYP3A4*2, CYP1A2*1K, CYP1A2*6, CYP3A4*3, and CYP3A5*7. MLAs were used to identify the predictor genetic variable for acute liver failure. Bioinformatics tools such as Predict SNP2 and molecular docking (MD) were undertaken to evaluate the impact of the above SNPs with binding affinity to paracetamol.

RESULTS

CYP2E1*2 and CYP1A2*1C genotypes were identified by MLAs to significantly predict hepatotoxicity. The predictSNP2 revealed that CYP1A2*3 was highly deleterious in all the tools. MD revealed binding energy of -5.5 Kcal/mol, -6.9 Kcal/mol, and -6.8 Kcal/mol for CYP1A2, CYP1A2*3, and CYP1A2*6 against paracetamol. MD simulations revealed that CYP1A2*3 and CYP1A2*6 missense variants in CYP1A2 affect the binding ability with paracetamol. In-silico techniques found that CYP1A2*2 and CYP1A2*6 are highly harmful. MD simulations revealed CYP3A4*2 (A>G) had decreased binding energy with paracetamol than CYP3A4, and CYP3A4*2(A>T) and CYP3A4*3 both have greater binding energy with paracetamol.

CONCLUSION

Polymorphisms in CYP2E1, CYP1A2, CYP3A4, and CYP3A5 significantly influence paracetamol's clinical outcomes or binding affinity. Robust clinical studies are needed to identify these polymorphisms' clinical impact on the pharmacokinetics or pharmacodynamics of paracetamol.

Association between CYP2E1 C-1054T and 96-bp I/D genetic variations and the risk of polycystic ovary syndrome in Chinese women

PURPOSE

To investigate the association of cytochrome P450 2E1 (CYP2E1) C-1054T (rs2031920) and 96-bp I/D genetic variations with the risk of polycystic ovary syndrome (PCOS), and to estimate the effects of genotypes on the clinical, metabolic, hormonal, and oxidative stress indicators.

METHODS

This case-control study included 762 control women and 1034 patients with PCOS. Genotypes were determined using polymerase chain reaction and/or restriction fragment length polymorphism analysis. Clinical and biochemical parameters were also analyzed.

RESULTS

Frequencies of the TT + CT genotype (35.4 vs. 28.9%) and T allele (19.6 vs. 16.0%) of the CYP2E1 C-1054T polymorphism were significantly higher in the PCOS group than in the control group (OR = 1.350, 95% CI 1.103-1.652, P = 0.004 for the dominant model). Genotype TT + CT remained a significant predictor of PCOS in a logistic regression model including age, body mass index (BMI), and recruitment year of participants (OR = 1.345, 95% CI 1.071-1.688, P = 0.011). No statistical differences were found in the genotype and allele frequencies of CYP2E1 96-bp I/D polymorphism. However, the combined genotype DD/TT + CT was related to an increased risk of PCOS when the DD/CC wild-type combined genotype was used as a reference. Patients with the I allele of 96-bp I/D polymorphism had a lower BMI but higher plasma apolipoprotein B and oxidized low-density lipoprotein cholesterol levels than those with the DD genotype.

CONCLUSION

CYP2E1 C-1054T, but not 96-bp I/D, genetic polymorphism is associated with an increased risk of PCOS in Chinese women.

Study of the Association of Single Nucleotide Polymorphisms in Candidate Genes With Sevoflurane

The susceptibility of different individuals to anesthetics varies widely, and sevoflurane is no exception. We hypothesized that polymorphisms in genes involved in pharmacokinetics and pharmacodynamics may explain this variation. A total of 151 individuals undergoing otorhinolaryngology surgery were included. The influence of genetic polymorphisms on sevoflurane sensitivity were investigated through SNaPshot technology. Individuals carrying KCNK2 rs6686529 G > C, MTRR rs3733784 TT, rs2307116 GG, or rs1801394 AA polymorphisms had a higher sensitivity to the sedative effect of sevoflurane than those without those polymorphisms. The univariate linear regression analysis indicated that MTRR rs3733784 TT, rs2307116 GG, and rs1801394 AA were potentially significant predictors of higher sensitivity to the sedative effect of sevoflurane. Moreover, CYP2E1 rs3813867 G > C and rs2031920 C > T, GABRG1 rs279858 T > C, KCNK3 rs1275988 CC, GRIN2B rs1806201 GG, MTRR rs2307116 G > A, and rs1801394 A > G were associated with a higher sensitivity to the cardiovascular effect of sevoflurane. Our results suggested that 9 single nucleotide polymorphisms in genes involved in metabolizing enzymes, transport proteins, target proteins of sevoflurane and folate metabolism may help to explain individual differences in the susceptibility to the sedative or cardiovascular effect of sevoflurane.

Amelioration of Hepatic Steatosis by the Androgen Receptor Inhibitor EPI-001 in Mice and Human Hepatic Cells Is Associated with the Inhibition of CYP2E1

Nonalcoholic fatty liver disease (NAFLD) is recognized as a metabolic disease characterized by hepatic steatosis. Despite the growing burden of NAFLD, approved pharmacological treatment is lacking. As an inhibitor of androgen receptor (AR), EPI-001 is being explored for the treatment of prostate cancer. This study aimed to investigate the potential of EPI-001 for treating NAFLD in free fatty acids (FFAs)-induced human hepatic cells and high-fat-high-sugar (HFHS)-feeding mice. Our results showed that EPI-001 reduced lipid accumulation in hepatic cells and ameliorated hepatic steatosis in mouse livers. Further exploration suggested that the effect of EPI-001 was associated with CYP2E1-mediated reduction of reactive oxygen species (ROS). This provides encouraging evidence for further studies on EPI-001 therapy for NAFLD.

Silymarin Protects against Acute Liver Injury Induced by Acetaminophen by Downregulating the Expression and Activity of the CYP2E1 Enzyme

Previous studies have shown that silymarin protects against various types of drug-induced liver injury, but whether the protective mechanism of silymarin against acetaminophen-induced liver injury is related to the CYP2E1 enzyme remains unclear. In this study, we investigated the effect of silymarin on the activity and expression of CYP2E1 in vitro and in vivo. The results of in vitro studies showed that silymarin not only inhibited the activity of CYP2E1 in human and rat liver microsomes but also reduced the expression of CYP2E1 in HepG2 cells. In vivo studies showed that silymarin pretreatment significantly reduced the conversion of chlorzoxazone to its metabolite 6-OH-CLX and significantly increased the t_1/2, area under the curve (AUC) and mean residence time (MRT) of chlorzoxazone. In addition, silymarin pretreatment significantly inhibited the upregulation of Cyp2e1 expression, reduced the production of 3-cysteinylacetaminophen trifluoroacetic acid salt (APAP-CYS), and restored the liver glutathione level. The results of our study show that silymarin plays an important protective role in the early stage of acetaminophen-induced acute liver injury by reducing the activity and expression of CYP2E1, reducing the generation of toxic metabolites, and alleviating liver injury.

Altered DNA methylation of CYP2E1 gene in schizophrenia patients with tardive dyskinesia

BACKGROUND

About 20-30% of patients with schizophrenia develop tardive dyskinesia (TD). Oxidative stress is one potential causes of TD. CYP2E1 is considered as an oxidative stress-related gene, however, no study has been reported on the DNA methylation levels of the CYP2E1 in schizophrenia or TD.

METHODS

A total of 35 schizophrenia patients with TD, 35 schizophrenia patients without TD (NTD), and 35 health controls (HCs) were collected in Beijing, China. DNA was extracted from peripheral blood samples. The promoter methylation levels of CYP2E1 were detected using pyrosequencing. The generalized linear model (GLM) was used to examine the methylation levels of three CpG sites among three diagnostic groups (TD vs. NTD vs. HC).

RESULTS

The average methylation levels were 8.8 ± 10.0, 14.5 ± 11.9 and 15.1 ± 11.3 in TD, NTD and HC groups, respectively. The F-test in GLM revealed overall differences in the average of methylation levels of three CpG sites among three diagnostic groups (p = 0.0227) and in the third CpG site (p = 0.0026). Furthermore, the TD group had lower average methylation levels than HC and NTD groups (p = 0.0115 and 0.0268, respectively). Specifically, TD group showed lower methylation levels in the third CpG site than HC and NTD groups (p = 0.0012 and 0.0072, respectively). Additionally, associations of the methylation levels with clinical features in the TD group were observed using Spearman correlation analysis.

CONCLUSION

This study provides the first evidence of DNA methylation levels in the promoter of CYP2E1 gene associated with schizophrenia and TD. The abnormal DNA methylation might serve as a potential mechanism for TD.

Mechanistic Considerations in 1,4-Dioxane Cancer Risk Assessment

The risk assessment of many carcinogens involves extrapolation across large exposure differences between the dose levels used in animal studies and the much lower human exposures. This is true for 1,4-dioxane which has a consistent liver carcinogenic effect in both genders of rats and mice. These data have been applied to risk assessment assuming a linear low dose extrapolation in some cases but non-linear or threshold models have been used in others. This choice hinges on our understanding of the 1,4-dioxane cancer mechanism. While 1,4-dioxane is not genotoxic in standard test batteries and has non-linear toxicokinetics, the mechanism for its carcinogenic effect remains unknown and is an active area of research. This review summarizes the possible modes of action for this chemical, data gaps and application to risk assessment. We find that the cytotoxicity/hyperplasia and metabolic saturation hypotheses do not explain the carcinogenic response and do not take into account 1,4-dioxane's induction of its own metabolism, leading to less likelihood for saturation during chronic exposure. There is evidence for other mechanisms, especially oxidative stress associated with the induction of CYP2E1 and in vivo genotoxicity that is not seen in vitro. The dose response for these effects needs further exploration compared to the time course and dose response for 1,4-dioxane-induced carcinogenesis. An additional consideration is the manner in which these 1,4-dioxane effects may augment naturally occurring and disease-related processes that contribute to the increasing rate of human liver cancer. These factors add to the rationale for using a non-threshold linear approach for extrapolating to low dose for this carcinogen, which is consistent with the default for carcinogens which do not have a clearly defined mode of action.