CYP3A4 Enzyme Activity Research Articles

Human Pluripotent Stem Cell-Derived Organoids as a Model of Intestinal Xenobiotic Metabolism

Background: The human intestine is the site of absorption and first-pass metabolism for oral intake. Assessment of absorption, distribution, metabolism, excretion, and toxicity (ADMET) of xenobiotics has transformed the understanding of in vivo pharmacology. However, these processes are difficult torecapitulate in vitro. Objective: We have developed a simple protocol for the generation of mature functional intestinal organoids from human pluripotent stem cells (hPSCs)under xenogeneic-free conditions. We sought to characterize transcription level in drug transporters and metabolism and evaluate CYP3A4 catalytic function of the organoids. Methods: Human pluripotent stem cell-derived intestinal organoids were generated and evaluated the expression of drug transporters and metabolizing enzymes. We examined the induction of CYP3A4 and ABCB1 gene expression in the organoids. Furthermore, we analyzed the CYP3A4 enzyme activity of the organoids by the p450-Glo CYP3A4 assay kit with luciferin isopropyl acetal. Results: Stem cell-derived intestinal organoids had an outward polarized intestinal epithelial layer and showed similar expression levels of drug transporters and metabolism genes as the adult healthy intestine. They also exhibited CYP3A4 enzymatic function in vitro. Conclusion: This model provides a novel platform for pharmacological testing and can enhance human ADMET studies in drug development.

Effects of Curcuma comosa Roxb. Extract on the Expression of CYP450s in Immortalized Hepatocyte-like Cells (imHC)

Hepatocytes are the most abundant liver cells that produce biotransformation enzymes, including phase I metabolism enzymes and cytochrome P450s (CYP450s). These enzymes are induced or suppressed by several drugs and chemicals. Here, immortalized hepatocyte-like cells (imHC) were applied as a novel hepatocyte to study the CYP450 enzyme expression induced by a Thai folk herb, Curcuma comosa Roxb. (C. comosa). The results demonstrated that the mRNA expression levels were dependent on cell cultivation conditions, the extract's concentration, and the duration of treatment. In the 3-day cultivation, 1 µg/mL C. comosa extract upregulated the mRNA expression levels of CYP1A1, CYP1A2, CYP2B6, CYP2C9, CYP2D6, CYP2E1 and CYP3A4 in imHC, after treatment for 48 h, which was comparable to the expression levels of those genes in HepG2 cells. In addition, C. comosa increased CYP3A4 protein expression in both imHC and HepG2 cells. Furthermore, 1 µg/mLC. comosa could neutralize erythromycin's inhibitory effect, a specific CYP3A4 inhibitor, on CYP3A4 enzyme activity. In conclusion, imHC exhibited several detoxification enzymes, and this cell could be used to replace hepatic carcinoma cells in hepatotoxic studies. The function of C. comosa as a CYP enzyme-inducing agent indicates a promising treatment for the prevention of drug-induced hepatotoxicity by activating detoxification enzymes.

Panax notoginseng saponins increases the blood concentration of nifedipine by inhibiting CYP3A4 enzyme through PXR- and CAR-Mediated pathway

Objective: To explore the mechanism underlying the effect of Panax notoginseng saponins (PNS) on the pharmacokinetics of nifedipine (NF) in rats. Materials and Methods: Twenty-four rats were randomly divided into blank (BL) group, PNS group, NF group, and PNS + NF group, with six rats in each group. Noncompartmental analysis and t-test were carried out to determine the difference between the pharmacokinetic parameters of NF in different groups. CYP3A4 enzyme activity was calculated using the probe drug method. The mRNA and protein contents of CYP3A4, nuclear receptor CAR, and PXR in rat liver were quantitatively analyzed by qRT-PCR and Western blot. Results: After the rats were treated with the combination of PNS and NF, the plasma concentration, half-life, peak time, and area under the concentration-time curve of NF increased, whereas the clearance rate decreased. The inhibitory effect on CYP3A4 enzyme activity was in the following order: PNS + NF group (strongest) > PNS group > NF group, and BL group (weakest). Similar changes were observed for the inhibitory effect on CYP3A4, CAR, and PXR mRNA and protein content, and the order was as follows: PNS + NF group (weakest)

CYP1A1 Enzymatic Activity Influences Skin Inflammation Via Regulation of the AHR Pathway

The AHR is an environmental sensor and transcription factor activated by a variety of man-made and natural ligands, which has recently emerged as a critical regulator of homeostasis at barrier organs such as the skin. Activation of the AHR pathway downmodulates skin inflammatory responses in animal models and psoriasis clinical samples. In this study, we identify CYP1A1 enzymatic activity as a critical regulator of beneficial AHR signaling in the context of skin inflammation. Mice constitutively expressing Cyp1a1 displayed increased CYP1A1 enzymatic activity in the skin, which resulted in exacerbated immune cell activation and skin pathology, mirroring that observed in Ahr-deficient mice. Inhibition of CYP1A1 enzymatic activity ameliorated the skin immunopathology by restoring beneficial AHR signaling. Importantly, patients with psoriasis displayed reduced activation of the AHR pathway and increased CYP1A1 enzymatic activity compared with healthy donors, suggesting that dysregulation of the AHR/CYP1A1 axis may play a role in inflammatory skin disease. Thus, modulation of CYP1A1 activity may represent a promising alternative strategy to harness the anti-inflammatory effect exerted by activation of the AHR pathway in the skin.

Expression of cytochrome P450 isozyme transcripts and activities in human livers

Individual differences in cytochrome P450 (CYP) enzymes contribute to responses to drugs and environmental chemicals. The expression of CYPs is influenced by sex, age, and ethnicity. Human CYP studies are often conducted with human liver microsomes and liver cells to evaluate chemical induction and drug interactions. However, the basal or constitutive expression of CYP transcripts and enzyme activities in the intact liver are also important in our understanding of individual variation in CYPs. This study utilised 100 human liver samples to profile the constitutive expression of CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4, and 4A11 enzyme activity and transcript levels. The mRNA expression of the CYPs and xenobiotic receptors AhR, CAR, and PXR was examined via qPCR. Results showed that there was greater inter-individual variation in mRNA expression than in enzyme activities, except for CYP2C19. Females had higher CYP3A4 activity than males. Children had lower CYP4A14 activity, while elderly had lower P450 oxidoreductase activity. Compared to Caucasians, Hispanics had higher CYP2C8 activity and higher CYP2B6, CYP2C9, and CYP2C19 mRNA expression, whereas African Americans had lower CYP2D6 mRNA expression. These results add to our understanding of individual variations in xenobiotic metabolism and toxicology.

Phase-1 bioactivation mechanisms of aflatoxin through AhR, CAR and PXR nuclear receptors and the interactions with Nigella sativa seeds and thymoquinone in broilers

Aflatoxins (AFs) are metabolised in two main phases in the liver. Cytochrome p450 enzyme (CYP) 1A1 and CYP2A6 are expressed through AhR, CAR and PXR nuclear receptors in phase-1 biotransformation of AFs. This study is the first to examine phase-1 biotransformation mechanisms of AF and the activity of Nigella sativa seed (NS) and its active ingredient thymoquinone (TQ) on these enzymes and receptors at the molecular level in broilers. Six groups of one day old broiler chicken (20 animals per group) were fed either control feed or a diet containing Aspergillus parasiticus NRRL 2999 culture material (total AFs 2 mg/kg), TQ (300 mg/kg), and NS (5%), either alone or as AF + TQ and AF + NS. Randomly selected from each group, 10 chicks were necropsied, and the livers were removed. Histopathological examination and serum biochemistry results revealed that AF caused hydropic and fatty degenerations, periportal inflammatory infiltrations, acinar arrangement, and biliary duct proliferation in livers and a significant increase at AST, ALT, ALP and GGT levels while significant decreases at serum cholesterol and total protein levels. These aflatoxicosis lesions and deteriorations in biochemistry levels were significantly ameliorated by NS or TQ (p < 0.05). AF was immunohistochemically found to increase strongly the nuclear receptors of AhR, PXR, CAR, and the enzyme activity of CYP1A1 and CYP2A6 responsible for its metabolism, leading to the emergence of toxic effects. Addition of TQ or NS to AF-containing diets improved the negative effects of AF on these receptors and enzymes significantly (p < 0.05). It was concluded that TQ and NS successfully alleviated liver injury by inhibiting or reducing the bioactivation of AF through phase-1 nuclear receptors and CYP-450 enzymes modulation.

Gene Regulatory Network Analysis and Engineering Directs Development and Vascularization of Multilineage Human Liver Organoids.

SUMMARYPluripotent stem cell (PSC)-derived organoids have emerged as novel multicellular models of human tissue development but display immature phenotypes, aberrant tissue fates, and a limited subset of cells. Here, we demonstrate that integrated analysis and engineering of gene regulatory networks (GRNs) in PSC-derived multilineage human liver organoids direct maturation and vascular morphogenesis in vitro. Overexpression of PROX1 and ATF5, combined with targeted CRISPR-based transcriptional activation of endogenous CYP3A4, reprograms tissue GRNs and improves native liver functions, such as FXR signaling, CYP3A4 enzymatic activity, and stromal cell reactivity. The engineered tissues possess superior liver identity when compared with other PSC-derived liver organoids and show the presence of hepatocyte, biliary, endothelial, and stellate-like cell populations in single-cell RNA-seq analysis. Finally, they show hepatic functions when studied in vivo. Collectively, our approach provides an experimental framework to direct organogenesis in vitro by systematically probing molecular pathways and transcriptional networks that promote tissue development.

Possible Herb-Drug Interaction Risk of Some Nutritional and Beauty Supplements on Antiretroviral Therapy in HIV Patients

This study was carried out to assess the drug interaction potential of a variety of beauty and sports/nutritional supplements when co-administered with antiviral drug therapy, especially anti-HIV drugs. Ethanolic extracts of seven dietary supplements (two beauty products, three nutritional protein supplement products and two weight loss/body building products) were examined in human liver cells (HepG2 cells and primary hepatocytes) for their influence on the hepatic metabolism of five antiviral drugs (elvitegravir, rilpivirine, tenofovir, dolutegravir, and cobicistat), all of which are substrates for a key drug metabolizing enzyme CYP3A4. Our results showed that six of the seven supplements caused a 1.5 – 2 fold induction in PXR transcriptional activity in HepG2 cells. PXR regulates the expression of key drug metabolizing enzymes including CYP3A4. Follow up studies indicated a 1.5 – 3 fold induction in CYP3A4 enzyme activity in HepG2 cells treated with these supplements. We further investigated the effects of the supplement on the metabolism of above mentioned anti-viral drugs in HepG2 cells and primary hepatocytes. Of the five drugs, rilpivirine and dolutegravir metabolism was increased by up to 2-folds over the no supplement control by some of the supplements. Our findings indicate that concomitant consumption of these products with anti-HIV drugs may compromise the efficacy of antivirals therapy due to supplement-induced metabolism via induction of CYP3A4 activity.

New Conceptual Toxicokinetic Model to Assess Synergistic Mixture Effects between the Aromatic Hydrocarbon β-Naphthoflavone and the Azole Nocodazole on the CYP1A Biomarker in a Fish Cell Line.

Toxicokinetic interactions with catabolic cytochrome P450 (CYP) enzymes can inhibit chemical elimination pathways and cause synergistic mixture effects. We have created a mathematical bottom-up model for a synergistic mixture effect where we fit a multidimensional function to a given data set using an auxiliary nonadditive approach. The toxicokinetic model is based on the data from a previous study on a fish cell line, where the CYP1A enzyme activity was measured over time after exposure to various combinations of the aromatic hydrocarbon β-naphthoflavone and the azole nocodazole. To describe the toxicokinetic mechanism in this pathway and how that affects the CYP1A biomarker, the model uses ordinary differential equations. Local sensitivity and identifiability analyses revealed that all the 10 parameters estimated in the model were identified uniquely while fitting the model to the data for measuring the CYP1A enzyme activity. The model has a good prediction power and is a promising tool to test the synergistic toxicokinetic interactions between different chemicals.

In Vitro Interaction of AB-FUBINACA with Human Cytochrome P450, UDP-Glucuronosyltransferase Enzymes and Drug Transporters.

AB-FUBINACA, a synthetic indazole carboxamide cannabinoid, has been used worldwide as a new psychoactive substance. Because drug abusers take various drugs concomitantly, it is necessary to explore potential AB-FUBINACA-induced drug–drug interactions caused by modulation of drug-metabolizing enzymes and transporters. In this study, the inhibitory effects of AB-FUBINACA on eight major human cytochrome P450s (CYPs) and six uridine 5′-diphospho-glucuronosyltransferases (UGTs) of human liver microsomes, and on eight clinically important transport activities including organic cation transporters (OCT)1 and OCT2, organic anion transporters (OAT)1 and OAT3, organic anion transporting polypeptide transporters (OATP)1B1 and OATP1B3, P-glycoprotein, and breast cancer resistance protein (BCRP) in transporter-overexpressing cells were investigated. AB-FUBINACA inhibited CYP2B6-mediated bupropion hydroxylation via mixed inhibition with Ki value of 15.0 µM and competitively inhibited CYP2C8-catalyzed amodiaquine N-de-ethylation, CYP2C9-catalyzed diclofenac 4′-hydroxylation, CYP2C19-catalyzed [S]-mephenytoin 4′-hydroxylation, and CYP2D6-catalyzed bufuralol 1′-hydroxylation with Ki values of 19.9, 13.1, 6.3, and 20.8 µM, respectively. AB-FUBINACA inhibited OCT2-mediated MPP+ uptake via mixed inhibition (Ki, 54.2 µM) and competitively inhibited OATP1B1-mediated estrone-3-sulfate uptake (Ki, 94.4 µM). However, AB-FUBINACA did not significantly inhibit CYP1A2, CYP2A6, CYP3A4, UGT1A1, UGT1A3, UGT1A4, UGT1A6, or UGT2B7 enzyme activities at concentrations up to 100 µM. AB-FUBINACA did not significantly inhibit the transport activities of OCT1, OAT1/3, OATP1B3, P-glycoprotein, or BCRP at concentrations up to 250 μM. As the pharmacokinetics of AB-FUBINACA in humans and animals remain unknown, it is necessary to clinically evaluate potential in vivo pharmacokinetic drug–drug interactions induced by AB-FUBINACA-mediated inhibition of CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, OCT2, and OATP1B1 activities.

Gene and Protein Expression in Subjects With a Nystagmus-Associated AHR Mutation.

Recently, a consanguineous family was identified in Israel with three children affected by Infantile Nystagmus and Foveal Hypoplasia, following an autosomal recessive mode of inheritance. A homozygous stop mutation c.1861C > T; p.Q621∗ in the aryl hydrocarbon receptor (AHR) gene (AHR; MIM 600253) was identified that co-segregated with the disease in the larger family. AHR is the first gene to be identified causing an autosomal recessive Infantile Nystagmus-related disease in humans. The goal of this study is to delineate the molecular basis of this newly discovered human genetic disorder associated with a rare AHR gene mutation. The gene and protein expression levels of AHR and selected AHR targets from leukocyte cultures of healthy subjects and the patients were analyzed. We observed significant variation between mRNA and protein expression of CYP1A1, CYP1B1, and TiPARP under rest and AHR-induced conditions. The CYP1A1 enzymatic activity in induced leukocytes also differs significantly between the patients and healthy volunteers. Intriguingly, the heterozygous subjects demonstrate CYP1A1 and TiPARP gene and protein expression similar to homozygous patients. In contrast, CYP1B1 inducibility and expression vary between hetero- and homozygous subjects. Similarity and differences in gene and protein expression between heterozygotes and homozygous patients can give us a hint as to which metabolic pathway/s might be involved in the Nystagmus etiology. Thus, we have a unique human model for AHR deficiency that will allow us the opportunity to study the biochemical basis of this rare human mutation, as well as the involvement of AHR in other physiological processes.

A two-dimensional multiwell cell culture method for the production of CYP3A4-expressing hepatocyte-like cells from HepaRG cells.

Cytochrome P450 enzymes (CYP) function in drug metabolism in the liver. To evaluate numerous drug candidates, a high‐content screening (HCS) system with hepatocyte‐like cells (HLCs) that can replace adult human hepatocytes is required. Human hepatocellular carcinoma HepaRG is the only cell line capable of providing HLCs with high CYP3A4 expression comparable to that in adult hepatocytes after cell differentiation. The aim of this study was to design an ideal multiwell culture system for HLCs using transgenic HepaRG cells expressing the EGFP coding an enhanced green fluorescent protein under CYP3A4 transcriptional regulation. HLCs were matured on five different types of 96‐well black plates. Culturing HLCs on glass‐bottom Optical CVG plates significantly promoted cell maturation and increased metabolic activity by twofold under two‐dimensional (2D) culture conditions, and these features were enhanced by 2% collagen coating. Three plates for three‐dimensional (3D) cell cultures with a gas‐exchangeable fabric or dimethylpolysiloxane membrane bottom formed multiple round colonies, whereas they were ineffective for CYP3A4 expression. Under optimized conditions presented here, HLCs lost responsiveness to nuclear receptor‐mediated transcriptional induction of CYP3A4, suggesting that CYP3A4 transcription has already been fully upregulated. Therefore, HepaRG‐derived HLCs will provide an alternative to human hepatocytes with high levels of CYP3A4 enzyme activity even under 2D culture conditions. This will improve a variety of drug screening methods.

AhR-activating pesticides increase the bovine ABCG2 efflux activity in MDCKII-bABCG2 cells.

In bovine mammary glands, the ABCG2 transporter actively secretes xenobiotics into dairy milk. This can have significant implications when cattle are exposed to pesticide residues in feed. Recent studies indicate that the fungicide prochloraz activates the aryl hydrocarbon receptor (AhR) pathway, increasing bovine ABCG2 (bABCG2) gene expression and efflux activity. This could enhance the accumulation of bABCG2 substrates in dairy milk, impacting pesticide risk assessment. We therefore investigated whether 13 commonly used pesticides in Europe are inducers of AhR and bABCG2 activity. MDCKII cells expressing mammary bABCG2 were incubated with pesticides for up to 72 h. To reflect an in vivo situation, applied pesticide concentrations corresponded to the maximum residue levels (MRLs) permitted in bovine fat or muscle. AhR activation was ascertained through CYP1A mRNA expression and enzyme activity, measured by qPCR and 7-ethoxyresorufin-Ο-deethylase (EROD) assay, respectively. Pesticide-mediated increase of bABCG2 efflux activity was assessed using the Hoechst 33342 accumulation assay. For all assays, the known AhR-activating pesticide prochloraz served as a positive control, while the non-activating tolclofos-methyl provided the negative control. At 10-fold MRL concentrations, chlorpyrifos-methyl, diflufenican, ioxynil, rimsulfuron, and tebuconazole significantly increased CYP1A1 mRNA levels, CYP1A activity, and bABCG2 efflux activity compared to the vehicle control. In contrast, dimethoate, dimethomorph, glyphosate, iprodione, methiocarb and thiacloprid had no impact on AhR-mediated CYP1A1 mRNA levels, CYP1A activity or bABCG2 efflux. In conclusion, the MDCKII-bABCG2 cell model proved an appropriate tool for identifying AhR- and bABCG2-inducing pesticides. This provides an in vitro approach that could reduce the number of animals required in pesticide approval studies.

Detoxification mechanism of Aconiti Lateralis Radix Praeparata combined with dried Rehmanniae Radix based on metabolic enzymes in liver

The enzymes CYP1 A2 and CYP3 A4 were measured by building a &quot;Cocktail&quot; probe drug and the incubation system of liver microsomes. The compatibility of Aconiti Lateralis Radix Praeparata combined with dried Rehmanniae Radix on CYP450 enzyme protein and gene expression was explored from the level of protein and molecular biology. It explored the molecular mechanism of compatibility detoxication of Aconiti Lateralis Radix Praeparata to provide scientific support for clinical safe and effective application of Aconiti Lateralis Radix Praeparata. The CYP450 enzyme activity was determined by using &quot;Cocktail&quot; probe drugs. The content of CYP450 enzyme was measured by CO reduction of differential spectrum method. The mRNA expression of CYP1 A2 and CYP3 A4 enzyme was detected by RT-PCR technology. Compared with the blank group, the CYP1 A2 and CYP3 A4 enzyme activity and mRNA expression were increased in the dried Rehmanniae Radix combined with Aconiti Lateralis Radix Praeparata group with significant differences(P&lt;0.05), while the CYP3 A4 enzyme activity and mRNA expression were no influence in the Aconiti Lateralis Radix Praeparata group. The CYP3 A4 enzyme activity and mRNA expression were increased in the dried Rehmanniae Radix and the dried Rehmanniae Radix combined with Aconiti Lateralis Radix Praeparata group, and there were significant differences(P&lt;0.05). The content of CYP450 enzyme was decreased in the Aconiti Lateralis Radix Praeparata group, contributed to extremely significant difference(P&lt;0.01). The content of CYP450 enzyme was increased in the dried Rehmanniae Radix and the dried Rehmanniae Radix combined with Aconiti Lateralis Radix Praeparata group, and there were significant differences(P&lt;0.05). The CYP1 A2 and CYP3 A4 enzyme activity and gene expression were enhanced after dried Rehmanniae Radix combined with Aconiti Lateralis Radix Praeparata. The metabolism of toxic ingredients of Aconiti Lateralis Radix Praeparata was accelerated to reach an effect of detoxication. The detoxication mechanism of compatibility of Aconiti Lateralis Radix Praeparata was verified from the viewpoint of liver metabolic enzymes.

Prediction of maternal pharmacokinetics using physiologically based pharmacokinetic models: assessing the impact of the longitudinal changes in the activity of CYP1A2, CYP2D6 and CYP3A4 enzymes during pregnancy

Concerns over gestational effects on the disposition of drugs has highlighted the need for a better understanding of drug distribution and elimination during pregnancy. This study aimed at predicting maternal drug kinetics using a physiologically based pharmacokinetic (PBPK) modelling approach focusing on the observed gestational changes in three important Cytochrome P450 metabolizing enzymes, namely, CYP1A2, CYP2D6 and CYP3A4 at different gestational weeks (GWs). The Pregnancy PBPK model within the Simcyp Simulator V19 was used to predict the pharmacokinetics of sensitive probes to these enzymes; namely caffeine, theophylline, metoprolol, propranolol, paroxetine, midazolam, nifedipine and rilpivirine. PBPK model predictions were compared against clinical data collated from multiple studies for each compound to cover a wide spectrum of gestational ages. Pregnancy PBPK model predictions were within 2-fold error and indicated that CYP1A2 activity is approximately 0.70, 0.44 and 0.30 fold of the non-pregnant level at the end of the first, second and third trimesters, respectively. On the other hand, CYP2D6 activity increases by 1.36, 2.16 and 3.10 fold of the non-pregnant level at the end of the first, second and third trimesters, respectively. Likewise, CYP3A4 activity increases by 1.25, 1.75 and 2.32 fold of the non-pregnant level at the end of the first, second and third trimesters, respectively. The enzymes activity have been qualified throughout pregnancy. Quantified changes in drug dosing are most relevant during the third trimester, especially for drugs that are mainly eliminated by CYP1A2, CYP2D6 and CYP3A4 enzymes. The provided functions describing the continuous changes to the activity of these enzymes during pregnancy are important when modelling long term pharmacokinetic studies where longitudinal modelling or time-varying covariates are used.

Indirect co-cultivation of HepG2 with differentiated THP-1 cells induces AHR signalling and release of pro-inflammatory cytokines

HepG2 and THP-1 cells, the latter differentiated by phorbol 12-myristate 13-acetate (PMA), were co-cultured and characterized for typical liver-specific functions, such as xenobiotic detoxification, lipid and cholesterol metabolism. Furthermore, liver injury-associated pathways, such as inflammation, were studied. In general, the co-cultivation of these cells produced a pro-inflammatory system, as indicated by increased levels of cytokines (IL-8, TGF-α, IL-6, GM-CSF, G-CSF, TGF-β, and hFGF) in the respective supernatant. Increased expression levels of target genes of the aryl hydrocarbon receptor (AHR), e.g., CYP1A1, CYP1A2 and CYP1B1, were detected, accompanied by the increased enzyme activity of CYP1A1. Moreover, transcriptome analyses indicated a significant upregulation of cholesterol biosynthesis, which could be reduced to baseline levels by lovastatin. In contrast, total de novo lipid synthesis was reduced in co-cultured HepG2 cells. Key events of the adverse outcome pathway (AOP) for fibrosis were activated by the co-cultivation, however, no increase in the concentration of extracellular collagen was detected. This indicates, that AOP should be used with care. In summary, the indirect co-culture of HepG2/THP-1 cells results in an increased release of pro-inflammatory cytokines, an activation of the AHR pathway and an increased enzymatic CYP1A activity.

Isatidis Folium alleviates acetaminophen-induced liver injury in mice by enhancing the endogenous antioxidant system.

Isatidis Folium (IF) has been clinically combined with acetaminophen (APAP), but the rationality of combinational therapy is still ambiguous. In the present study, the protective effect and related mechanism of IF on APAP-induced hepatotoxicity were evaluated. Hepatic histopathology and blood biochemistry investigations clearly demonstrated that IF could restore APAP-induced hepatotoxicity. Liver distribution study indicated that the hepatoprotective effect of IF on APAP is attributed to the reduction of N-acetyl-p-benzoquinone imine (NAPQI) in liver, which is a known hepatotoxic metabolite of APAP. Further study suggested the reduction is not via decreasing the generation of NAPQI through inhibiting the enzyme activities of CYP 1A2, 2E1, and 3A4 but via accelerating the transformation of NAPQI to NAPQI-GSH by promoting GSH and decreasing GSSG contents in liver. Furthermore, IF significantly enhanced the hepatic activities of GSH-associated enzymes in APAP-treated mice. In summary, IF could alleviate APAP-induced hepatotoxicity by reducing the content of NAPQI via enhancing the level of GSH and the followed generation of NAPQI-GSH which might be ascribed to the upregulation of GSH-associated enzymes.

The sulfate metabolite of 3,3′-dichlorobiphenyl (PCB-11) impairs Cyp1a activity and increases hepatic neutral lipids in zebrafish larvae (Danio rerio)

The environmental contaminant 3,3′-dichlorobiphenyl (PCB-11) is widely detected in environmental samples, and this parent compound along with its metabolites 4-OH-PCB-11 and 4-PCB-11-Sulfate are detected in human serum. Our previous research in zebrafish (Danio rerio) embryos shows exposure to 20 μM PCB-11 inhibits Cyp1a enzyme activity and perturbs lipid metabolism pathways. In this study, wildtype AB embryos underwent acute exposures from 1 to 4 days post fertilization (dpf) to 0.002–20 μM 4-OH-PCB-11 or 0.2–20 μM 4-PCB-11-Sulfate, with and without co-exposures to 100 μg/L benzo[a]pyrene (B[a]P) or 5 nM 3,3′,4,4′,5-pentachlorobiphenyl (PCB-126), and were assessed for in vivo EROD activity and morphometrics. Chronic exposures from 1 to 15 dpf to assess lipid accumulation using Oil-Red-O staining were also conducted with 0.2 μM parent or metabolite compounds, alongside a co-exposure experiment of 0.002–0.2 μM 4-PCB-11-Sulfate and 10 μg/L B[a]P. For acute experiments, 2 and 20 μM 4-OH-PCB-11 was lethal but no Cyp1a or morphological effects were observed at lower concentrations; 20 μM 4-PCB-11-Sulfate significantly lowered the Cyp1a activity of B[a]P and PCB-126 but did not alter morphological development. For chronic experiments, 0.2 μM 4-PCB-11-Sulfate significantly increased lipid accumulation 30% in single exposures and 44% in co-exposures with B[a]P. Further long-term studies would better elucidate the effects of this contaminant, particularly in the context of environmentally-relevant mixtures.

Methamphetamine administration increases hepatic CYP1A2 but not CYP3Aactivity in female guinea pigs.

Methamphetamine use has increased over the past decade and the first use of methamphetamine is most often when women are of reproductive age. Methamphetamine accumulates in the liver; however, little is known about the effect of methamphetamine use on hepatic drug metabolism. Methamphetamine was administered on 3 occassions to female Dunkin Hartley guinea pigs of reproductive age, mimicking recreational drug use. Low doses of test drugs caffeine and midazolam were administered after the third dose of methamphetamine to assess the functional activity of cytochrome P450 1A2 and 3A, respectively. Real-time quantitative polymerase chain reaction was used to quantify the mRNA expression of factors involved in glucocorticoid signalling, inflammation, oxidative stress and drug transporters. This study showed that methamphetamine administration decreased hepatic CYP1A2 mRNA expression, but increased CYP1A2 enzyme activity. Methamphetamine had no effect on CYP3A enzyme activity. In addition, we found that methamphetamine may also result in changes in glucocorticoid bioavailability, as we found a decrease in 11β-hydroxysteroid dehydrogenase 1 mRNA expression, which converts inactive cortisone into active cortisol. This study has shown that methamphetamine administration has the potential to alter drug metabolism via the CYP1A2 metabolic pathway in female guinea pigs. This may have clinical implications for drug dosing in female methamphetamine users of reproductive age.

Clinical pharmacokinetics and pharmacodynamics of ivosidenib in patients with advanced hematologic malignancies with an IDH1 mutation

Isocitrate dehydrogenase (IDH) mutations lead to formation of the oncometabolite 2-hydroxyglutarate (2-HG), which is elevated in several solid and liquid tumors. Ivosidenib (AG-120) is a targeted, potent, oral inhibitor of the mutant IDH1 protein. We describe detailed pharmacokinetics and pharmacodynamics of ivosidenib in patients with advanced hematologic malignancies with an IDH1 mutation treated in a phase I study (ClinicalTrials.gov NCT02074839). Patients received single and multiple oral doses of ivosidenib from 100mgtwice daily to 1200mg once daily (QD) in 28-day continuous cycles. Concentrations of ivosidenib and 2-HG in plasma, and 2-HG in bone marrow, were assessed at routine intervals. Plasma 4β-hydroxycholesterol/cholesterol ratios were assessed as a marker of CYP3A activity. Ivosidenib was rapidly absorbed and slowly eliminated (half-life 72-138h) after single and multiple dosing. Ivosidenib exhibited dose- and time-dependent pharmacokinetics, with exposure increasing sub-proportionally to dose, and clearance increasing with increasing dose. Plasma 2-HG concentrations were maximally and persistently inhibited in the majority of patients receiving 500-mg QD ivosidenib, to concentrations close to those observed in healthy subjects. Ivosidenib pharmacokinetics were not affected by mild or moderate renal impairment, mild hepatic impairment, age, weight, sex, race, or co-administration of weak CYP3A4 inhibitors or inducers. Moderate-to-strong CYP3A4 inhibitors decreased ivosidenib clearance. Ivosidenib also induced CYP3A enzyme activity, with increases in 4β-hydroxycholesterol/cholesterol ratios of 119-168% at 500-mg QD ivosidenib. Ivosidenib 500-mg QD has favorable pharmacokinetic and pharmacodynamic profiles in patients with advanced hematologic malignancies with an IDH1 mutation. ClinicalTrials.gov NCT02074839.