Cytochrome P450 Activity Research Articles

CncC-Keap1-P450s pathway is involved in the detoxification of emamectin benzoate in the spongy moth Lymantria dispar

The detoxification of insecticides in insects is dependent on the expression and activity of multiple detoxification enzymes. As an important modulator of detoxification enzymes, the CncC-Keap1 pathway was involved in the detoxification of various pesticides. However, whether the CncC-Keap1 pathway is involved in the detoxification of emamectin benzoate (EMB) is unclear. In this study, we cloned the LdCncC and LdKeap1 from spongy moths (Lymantria dispar). Our results showed that EMB exposure induced oxidative stress, and activated the CncC-Keap1 pathway at mRNA and protein levels. Removing ROS by N-acetylcysteine remarkably decreased H2O2 levels and restored the expression of LdCncC and LdKeap1. The silencing LdCncC, not LdKeap1, by dsRNA significantly decreased the cytochrome P450 activities, and increased the sensitivity of larvae to EMB. Besides, the expression of CYP6B7v1, CYP321A7 and CYP4S4v1 were significantly decreased after silencing LdCncC. Notably, the knockdown of CYP6B7v1, CYP321A7 or CYP4S4v1 significantly increased the mortality induced by EMB exposure. Therefore, we proposed that activation of CncC-Keap1 pathway induced by ROS increased the detoxification of EMB in spongy moths by regulating the expression of CYP6B7v1, CYP321A7 and CYP4S4v1. Our study strengthened the understanding of the detoxification of EMB from the perspective of CncC-Keap1-P450s pathway.

Extending the shelf life of HLM chips through freeze-drying of human liver microsomes immobilized onto thiol-ene micropillar arrays.

Microfluidic flow reactors functionalized with immobilized human liver microsomes (HLM chips) represent a powerful tool for drug discovery and development by enabling mechanism-based enzyme inhibition studies under flow-through conditions. Additionally, HLM chips may be exploited in streamlined production of human drug metabolites for subsequent microfluidic in vitro organ models or as metabolite standards for drug safety assessment. However, the limited shelf life of the biofunctionalized microreactors generally poses a major barrier to their commercial adaptation in terms of both storage and shipping. The shelf life of the HLM chips in the wetted state is ca. 2-3 weeks only and requires cold storage at 4 °C. In this study, we developed a freeze-drying method for lyophilization of HLMs that are readily immobilized inside microfluidic pillar arrays made from off-stoichiometric thiol-ene polymer. The success of lyophilization was evaluated by monitoring the cytochrome P450 and UDP-glucuronosyltransferase enzyme activities of rehydrated HLMs for several months post-freeze-drying. By adapting the freeze-drying protocol, the HLM chips could be stored at room temperature (protected from light and moisture) for at least 9 months (n = 2 independent batches) and up to 16 months at best, with recovered enzyme activities within 60-120% of the non-freeze-dried control chips. This is a major improvement over the cold-storage requirement and the limited shelf life of the non-freeze-dried HLM chips, which can significantly ease the design of experiments, decrease energy consumption during storage, and reduce the shipping costs with a view to commercial adaptation.

The role of polymorphic cytochrome P450 gene (CYP2B6) in B-chronic lymphocytic leukemia (B-CLL) incidence and outcome among Egyptian patients.

Cytochromes P450 (CYPs) play a prominent role in catalyzing phase I xenobiotic biotransformation and account for about 75% of the total metabolism of commercially available drugs, including chemotherapeutics. The gene expression and enzyme activity of CYPs are variable between individuals, which subsequently leads to different patterns of susceptibility to carcinogenesis by genotoxic xenobiotics, as well as differences in the efficacy and toxicity of clinically used drugs. This research aimed to examine the presence of the CYP2B6*9 polymorphism and its possible association with the incidence of B-CLL in Egyptian patients, as well as the clinical outcome after receiving cyclophosphamide chemotherapy. DNA was isolated from whole blood samples of 100 de novo B-CLL cases and also from 100 sex- and age-matched healthy individuals. The presence of the CYP2B6*9 (G516T) polymorphism was examined by PCR-based allele specific amplification (ASA). Patients were further indicated for receiving chemotherapy, and then they were followed up. The CYP2B6*9 variant indicated a statistically significant higher risk of B-CLL under different genetic models, comprising allelic (T-allele vs. G-allele, OR = 4.8, p < 0.001) and dominant (GT + TT vs. GG, OR = 5.4, p < 0.001) models. Following cyclophosphamide chemotherapy, we found that the patients with variant genotypes (GT + TT) were less likely to achieve remission compared to those with the wild-type genotype (GG), with a response percentage of (37.5% vs. 83%, respectively). In conclusion, our findings showed that the CYP2B6*9 (G516T) polymorphism is associated with B-CLL susceptibility among Egyptian patients. This variant greatly affected the clinical outcome and can serve as a good therapeutic marker in predicting response to cyclophosphamide treatment.

Impact of IL-6 and IL-10 genotypes on tacrolimus dose requirements in kidney transplant recipients: Monte Carlo analysis.

Introduction: IL-6 and IL-10 may affect the activity of cytochrome P450 (CYP) 3A enzymes involved in tacrolimus (Tac) metabolism. Moreover, the effect of IL-6 and IL-10 on Tac pharmacokinetics may differ with respect to the genetic variations in their genes.Aim: To examine the influence of IL-6 and IL-10 gene polymorphisms on Tac dose requirements and exposure over a 5-year period following kidney transplantation. Univariate and standard multivariate linear regression and Monte Carlo analysis were performed to investigate potential covariates influencing Tac dose-adjusted trough concentration (C0/D) in various post-transplantation periods.Materials & methods: IL-6 (-174G>C), IL-10 (-1082G>A, -819C>T and -592C>A) genotype, Tac daily dose, C0, C0/D and intrapatient variability data were collected from 113 patients.Results: Multivariate regression analysis and accompanied Monte Carlo simulation underscore the importance of considering IL-6 -174G>C and IL-10 -1082G>A gene polymorphisms, alongside Tac metabolic phenotype and post-transplantation period, when tailoring Tac dosage regimen.Conclusion: This study provides valuable insights regarding the individualized adjustment of Tac treatment in various post-transplantation periods.

A decellularized matrix enriched collagen microscaffold for a 3D in vitro liver model.

The development of liver scaffolds retaining their three-dimensional (3D) structure and extra-cellular matrix (ECM) composition is essential for the advancement of liver tissue engineering. We report the design and validation of an alginate-based platform using a combination of decellularized matrices and collagen to preserve the functionality of liver cells. The scaffolds were characterized using SEM and fluorescence microscopy techniques. The proliferation and functional behaviours of hepatocellular carcinoma HuH7 cells were observed. It was found that the decellularized skin scaffold with collagen was better for maintaining the growth of cells in comparison to other decellularized matrices. In addition, we observed a significant increase in the functional profile once exogenous collagen was added to the liver matrix. Our study also suggests that a cirrhotic liver model should have a different matrix composition as compared to a healthy liver model. When primary rat hepatocytes were used for developing a healthy liver model, the proliferation studies with hepatocytes showed a decellularized skin matrix as the better option, but the functionality was only maintained in a decellularized liver matrix with addition of exogenous collagen. We further checked if these platforms can be used for studying drug induced toxicity observed in the liver by studying the activation of cytochrome P450 upon drug exposure of the cells growing in our model. We observed a significant induction of the CYP1A1 gene on administering the drugs for 6 days. Thus, this platform could be used for drug-toxicity screening studies using primary hepatocytes in a short span of time. Being a microscaffold based system, this platform offers some advantages, such as smaller volumes of samples, analysing multiple samples simultaneously and a minimal amount of decellularized matrix in the matrix composition, making it an economical option compared to a completely dECM based platform.

Schisandra chinensis in Liver Disease: Exploring the Mechanisms and Therapeutic Promise of an Ancient Chinese Botanical

Background: Schisandra chinensis is a traditional Chinese herbal medicine that has been used for centuries for liver health. The active lignans in Schisandra, including schisandrin and gomisins, have exhibited anti-inflammatory, antioxidant, and hepatoprotective properties in preliminary studies. With rising rates of chronic liver diseases globally, there is interest in the potential therapeutic role of Schisandra. Purpose: To comprehensively review the current evidence for Schisandra chinensis in treating liver injury and disease and synthesize implications for future human research. Main body: Schisandra extracts decreased inflammatory cytokines and oxidative stress markers and increased endogenous antioxidant activity in animal models, suggesting utility in mitigating liver inflammation and damage. Additional preclinical studies demonstrated attenuated liver enzyme levels, necrosis, and fibrosis progression in chemical-induced hepatotoxicity with Schisandra treatment. Enhanced cytochrome P450 activity, glutathione production, and glycogen synthesis were also observed, improving detoxification and regeneration capacity. Small human trials in hepatitis and nonalcoholic fatty liver disease showed improved liver enzymes and symptoms with Schisandra supplementation but were limited in quality and sample size. Conclusion: Schisandra chinensis has biologically relevant mechanisms that warrant further human research on its role as a hepatoprotective phytotherapy. Well-designed, large-scale clinical trials are needed to establish efficacy and safety for liver disease applications.

Comprehensive Transcriptomic and Metabolomic Analysis Revealed the Functional Differences in Pigeon Lactation between Male and Female during the Reproductive Cycle.

Lactation is a unique reproductive behavior in pigeons, with the crop serving as the organ responsible for secreting pigeon milk. Both male and female pigeons can produce crop milk and rear their offspring through a division of labor. Since the time of the secretion of pigeon crop milk is different in the process of feeding the young, whether the metabolism and formation of pigeon milk use the same mechanism is a very interesting scientific question. However, the metabolic dynamics and underlying genetic mechanisms involved in the formation of pigeon crop milk remain unclear, particularly during the incubation-feeding reproductive cycle. In this study, we integrated lactation-associated metabolism and transcriptome data from the crop tissues of both male and female pigeons during the brooding and feeding stages. We mapped the changes in metabolites related to milk formation in the crop tissues during these stages. Through metabolome profiling, we identified 1413 metabolites among 18 crop tissues. During the breeding cycles, the concentrations of estrone, L-ergothioneine, and L-histidine exhibited the most dynamic changes in females. In contrast, estrone, L-anserine, 1-methylhistidine, homovanillate, oxidized glutathione, and reducing glutathione showed the most dynamic changes in males. Gender-specific differences were observed in the metabolome, with several metabolites significantly differing between males and females, many of which were correlated with cytokine binding, immunity, and cytochrome P450 activity. Using this dataset, we constructed complex regulatory networks, enabling us to identify important metabolites and key genes involved in regulating the formation of pigeon milk in male and female pigeons, respectively. Additionally, we investigated gender-associated differences in the crop metabolites of pigeons. Our study revealed differences in the modulation of pigeon crop milk metabolism between males and females and shed light on the potential functions of male and female pigeon milk in the growth, development, and immunity of young pigeons, an area that has not been previously explored. In conclusion, our results provide new insights into the metabolic regulation of pigeon crop milk formation during the brooding and breeding stages. Furthermore, our findings lay the foundation for the accurate development of artificial pigeon milk.

Steamed daylily flower (Hemerocallis fulva L.) protected cardiac and hepatic cells against ethanol induced apoptotic and oxidative damage.

Our previous study examined the phytochemical composition and bio-activities of raw daylily flower (Hemerocallis fulva L.). However, this plant food is usually served via heat process such as cooking in a soup. This study aimed to investigate the phytochemical profile and biofunctions of steamed daylily flower (SDF). The content of total phenolic acids, total flavonoids, total carotenoids, total anthocyanins and total triterpenoids in SDF aqueous extract was assessed. Normal cardiac and hepatic cells, H9c2 and L-02 cells, were used to evaluate the protective effects of SDF against ethanol. SDF concentrations of 0.25%, 0.5%, and 1% were applied to treat H9c2 or L-02 cells for 48 h at 37 °C initially, followed by exposure to ethanol at 150 mM for 24 h at 37 °C. Results showed that the content of assessed phytochemicals was in the range of 1019-2045 mg/100 g dry weight. Flavonoids and triterpenoids were two major detected phytochemicals in SDF. SDF treatments at 0.5% and 1% increased the viability of H9c2 cells, but at three concentrations enhanced the survival of L-02 cells. SDF at 0.5% and 1% up-regulated Bcl-2 messenger RNA (mRNA) expression and down-regulated Bax mRNA expression. Ethanol increased reactive oxygen species production, decreased glutathione content, as well as lowered glutathione peroxidase and catalase activities. SDF treatments reversed these changes. SDF at 0.5% and 1% reduced the activity of cytochrome P450 2E1 and nicotinamide adenine dinucleotide phosphate oxidase, limited p47phox mRNA expression, as well as enhanced factor E2-related factor 2 and heme oxygenase-1 mRNA expression. SDF at three concentrations decreased gp91phox mRNA expression. In conclusion, these novel findings indicated that SDF aqueous extract was rich in phytochemicals and provided anti-apoptotic and anti-oxidative actions to protect cardiac and hepatic cells against ethanol. Thus, SDF might be considered as a functional food with multiple bio-activities.

Combination of melt-electrospun poly-ε-caprolactone scaffolds and hepatocyte-like cells from footprint-free hiPSCs to create 3D biohybrid constructs for liver tissue engineering

The liver is a vital organ with numerous functions, including metabolic functions, detoxification, and the synthesis of secretory proteins. The increasing prevalence of liver diseases requires the development of effective treatments, models, and regenerative approaches. The field of liver tissue engineering represents a significant advance in overcoming these challenges. In this study, 3D biohybrid constructs were created by combining hepatocyte-like cells (HLCs) derived from patient-specific footprint-free human induced pluripotent stem cells (hiPSCs) and 3D melt-electrospun poly-ε-caprolactone (PCL) scaffolds. First, a differentiation procedure was established to obtain autologous HCLs from hiPSCs reprogrammed from renal epithelial cells using self-replicating mRNA. The obtained cells expressed hepatocyte-specific markers and exhibited important hepatocyte functions, such as albumin synthesis, cytochrome P450 activity, glycogen storage, and indocyanine green metabolism. Biocompatible PCL scaffolds were fabricated by melt-electrospinning and seeded with pre-differentiated hepatoblasts, which uniformly attached to the fibers of the scaffolds and successfully matured into HLCs. The use of patient-specific, footprint-free hiPSC-derived HLCs represents a promising cell source for personalized liver regeneration strategies. In combination with biocompatible 3D scaffolds, this innovative approach has a broader range of applications spanning liver tissue engineering, drug testing and discovery, and disease modeling.

Maternal obesity impacts fetal liver androgen signalling in a sex-specific manner

BackgroundMaternal obesity (MO) increases fetal androgen concentrations, the prevalence of macrosomia, and predisposes offspring to metabolic dysfunction in later life, especially males. These risks may be, in part, the result of increased liver-specific androgen signalling pathway activity in utero. Androgen signalling activity can be suppressed by androgen metabolism via cytochrome P450 (CYP) isoenzymes (CYP2B6, CYP3A) or through inhibition of the full-length androgen receptor (AR-FL) via the antagonistic isoform, AR-45. We hypothesised MO impairs CYP enzyme activity and AR-45 expression in male fetal livers, thereby enhancing activity of androgen signalling pathways. MethodsNine months prior to pregnancy, nulliparous female baboons were assigned to either ad libitum control or high fat diet. At 165 day (d) gestation (term, 180 d) fetal liver was collected (n = 6/sex/group). CYP activity was quantified using functional assays; subcellular AR expression was measured using Western blot. ResultsCYP2B6 and CYP3A activity, and nuclear expression of AR-45, was reduced in MO males only. Nuclear AR-45 expression was inversely related with fetal body weight of MO males only. ConclusionsReduced CYP2B6 and CYP3A activity in conjunction with decreased nuclear AR-45 expression may enhance liver androgen signalling in males from MO pregnancies, thereby increasing the risk of macrosomia, as well as metabolic dysfunction in later life.

Microfluidic Fabrication of MicroRNA-Induced Hepatocyte-Like Cells/Human Umbilical Vein Endothelial Cells-Laden Microgels for Acute Liver Failure Treatment.

Acute liver failure (ALF) is a critical life-threatening disease that occurs due to a rapid loss in hepatocyte functions. Hepatocyte transplantation holds great potential for ALF treatment, as it rapidly supports liver biofunctions and enhances liver regeneration. However, hepatocyte transplantation is still limited by renewable and ongoing cell sources. In addition, intravenously injected hepatocytes are primarily trapped in the lungs and have limited efficacy because of the rapid clearance in vivo. Here, we designed a Y-shaped DNA nanostructure to deliver microRNA-122 (Y-miR122), which could induce the hepatic differentiation and maturation of human mesenchymal stem cells. mRNA sequencing analysis revealed that the Y-miR122 promoted important hepatic biofunctions of the induced hepatocyte-like cells including fat and lipid metabolism, drug metabolism, and liver development. To further improve hepatocyte transplantation efficiency and therapeutic effects in ALF treatment, we fabricated protective microgels for the delivery of Y-miR122-induced hepatocyte-like cells based on droplet microfluidic technology. When cocultured with human umbilical vein endothelial cells in microgels, the hepatocyte-like cells exhibited an increase in hepatocyte-associated functions, including albumin secretion and cytochrome P450 activity. Notably, upon transplantation into the ALF mouse model, the multiple cell-laden microgels effectively induced the restoration of liver function and enhanced liver regeneration. Overall, this study presents an efficient approach from the generation of hepatocyte-like cells to hepatocyte transplantation in ALF therapy.

Molecular Mechanisms of the Regulation of Liver Cytochrome P450 by Brain NMDA Receptors and via the Neuroendocrine Pathway—A Significance for New Psychotropic Therapies

Recent investigations have highlighted the potential utility of the selective antagonist of the NMDA receptor GluN2B subunit for addressing major depressive disorders. Our previous study showed that the systemic administration of the antagonist of the GluN2B subunit of the NMDA receptor, the compound CP-101,606, affected liver cytochrome P450 expression and activity. To discern between the central and peripheral mechanisms of enzyme regulation, our current study aimed to explore whether the intracerebral administration of CP-101,606 could impact cytochrome P450. The injection of CP-101,606 to brain lateral ventricles (6, 15, or 30 µg/brain) exerted dose-dependent effects on liver cytochrome P450 enzymes and hypothalamic or pituitary hormones. The lowest dose led to an increase in the activity, protein, and mRNA level of CYP2C11 compared to the control. The activities of CYP2A, CYP2B, CYP2C11, CYP2C6, CYP2D, and protein levels of CYP2B, CYP2C11 were enhanced compared to the highest dose. Moreover, CP-101,606 increased the CYP1A protein level coupled with elevated CYP1A1 and CYP1A2 mRNA levels, but not activity. The antagonist decreased the pituitary somatostatin level and increased the serum growth hormone concentration after the lowest dose, while independently decreasing the serum corticosterone concentration of the dose. The findings presented here unveil a novel physiological regulatory mechanism whereby the brain glutamatergic system, via the NMDA receptor, influences liver cytochrome P450. This regulatory process appears to involve the endocrine system. These results may have practical applications in predicting alterations in cytochrome P450 activity and endogenous metabolism, and potential metabolic drug–drug interactions elicited by drugs that cross the blood–brain barrier and affect NMDA receptors.

Drug-drug interaction between paxlovid and tacrolimus in a patient with myasthenia gravis and SARS-CoV-2 infection

Patients with both myasthenia gravis (MG) and SARS-CoV-2 infection face treatment challenges due to potential drug interactions. One common immunosuppressant for MG, Tacrolimus, is primarily metabolized by the cytochrome P450. However, Paxlovid, an antiviral medication, inhibits cytochrome P450 activity, which can lead to increased Tacrolimus levels and potential toxicity when the two drugs are combined. In this case report, we present the case of a 39-year-old woman with early-onset MG who was initially treated with Tacrolimus. Later, she received Paxlovid for SARS-CoV-2 infection, which resulted in a sudden spike in Tacrolimus levels due to the drug interaction. This case emphasizes the importance of personalized treatment plans and close monitoring of drug interactions in patients with multiple health conditions. Clinicians should exercise vigilance regarding potential Tacrolimus interactions and regularly monitor blood levels to prevent adverse effects. Caution and close monitoring of Tacrolimus levels are essential when administering Paxlovid to patients on Tacrolimus therapy.

Pharmacokinetic and pharmacodynamic drug-drug interaction of Nomilin with atorvastatin in hyperlipidemic mice

Atorvastatin (Atv) is widely used to lower cholesterol levels and treat hyperlipidemia in clinical application. Nomilin (Nom) is a kind of limonoids, which is found and isolated from the citrus herbs of Rutaceae family, which are widely used as patent medicines, functional foods, and nutritional supplements in many countries. In previous studies, Nom has the effect of anti-obesity and curing other metabolic diseases. Nevertheless, in recent years, the drug-drug interaction (DDI) caused by the administration of drugs with synergistic effects have raised worldwide concerns. To investigate the DDI of Nom and Atv in vivo, the pharmacokinetic studies were performed with using C57BL/6 mice. The plasma concentrations of Nom and Atv were measured after oral administration of different drug combinations by a simple and sensitive UHPLC-MS/MS method. The experimental mice were randomly divided into five groups, including control group, model group, administered Nom individually group, administered Atv individually group and co-administered of Nom and Atv group. The lipid levels including total cholesterol (TC), triglycerides (TG), high density lipoproteins-cholesterol (HDL-C), low density lipoproteins-cholesterol (LDL-C) were measured for pharmacodynamic study. The hepatic microsomal Cytochrome P450 (CYP1A2, CYP2E1 and CYP3A11) activities were probed using cocktail assay. The gene and protein expressions of CYP3A11 were detected via qPCR and Western blot method. The results shown that the area under the plasma concentration-time curve (AUC) of Atv in administered Atv individually group was 69.30 ± 15.45 ng/mL × h, while that of combined Nom with Atv group was 42.37 ± 10.15 ng/mL × h (p＜0.05). The degree of reduction in lipid levels of mice treated with co-administration of Atv and Nom was less than that of mice treated with Atv alone. In addition, Nom could cause an increased hepatic microsomal CYP3A11 activity significantly, and induce the gene levels and protein expressions of CYP3A11 elevated in mice livers. In conclusion, Nom could up-regulate CYP3A11 activity, thereby impacting on the pharmacokinetic profile and pharmacodynamic effect of Atv. The findings provide more insight for the use risk of these two drugs to treat hyperlipidemia diseases.

Larvicidal activity and biochemical effect of some essential oils and indoxacarb against peach fruit fly, Bactrocera zonata (Diptera: Tephritidae)

Bactrocera zonata (Saunders) (Diptera: Tephritidae) is an important insect pest of fruits in Egypt. The desire for fresh fruits free of insecticides drives the adoption of environmentally friendly biopesticides to manage pests. The current study sought to estimate the toxicity and biochemical alterations of 3rd larval instar of B. zonata affected by clove, neemazal T/S, garlic, ginger and orange oils compared with indoxacarb at LC50 under laboratory conditions. Results after 24 h of treatment indicated that neemazal T/S is more toxic than other tested oils compared with higher toxicity of indoxacarb with LC50 values of 86.09, 174.72, 4514.38, 7224.01, 9387.73 and 2590.2 μg/mL for indoxacarb, neemazal T/S, ginger, clove, garlic and orange oils, respectively. Moreover, after 24 h of treatment, the larval content of digestive enzymes drastically decreased. All compounds caused a remarkable reduction in protease (except clove oil), aspartate aminotransferase (AST), alanine aminotransferase (ALT), phenol oxidase enzyme, α-esterase (except indoxacarb and neemazal T/S) and β-esterase (except ginger oil and neemazal T/S) activity. Also, total carbohydrates, total lipids and total proteins take the same trend. All treatments at LC50 increased the activity of cytochrome p450 and glutathione-s-transferase against 3rd larval instar of B. zonata compared with control. Our findings recommended that the tested botanicals could be an effective substitute for conventional insecticides as well as their safety for human beings and beneficial organisms.

The effect of brain serotonin deficit (TPH2-KO) on the expression and activity of liver cytochrome P450 enzymes in aging male Dark Agouti rats

BackgroundLiver cytochrome P450 (CYP) greatly contributes to the metabolism of endogenous substances and drugs. Recent studies have demonstrated that CYP expression in the liver is controlled by the central nervous system via hormonal pathways. In particular, the expression of hepatic CYPs is negatively regulated by the brain serotoninergic system. The present study aimed to investigate changes in the function of the main liver drug-metabolizing CYP enzymes as a result of serotonin depletion in the brain of aging rats, caused by knockout of brain tryptophan hydroxylase gene (TPH2-KO).MethodsThe hepatic CYP mRNA (qRT-PCR), protein level (Western blotting) and activity (HPLC), and serum hormone levels (ELISA) were measured in Dark Agouti wild-type (WT) male rats (mature 3.5-month-old and senescent 21-month-old) and in TPH2-KO senescent animals.ResultsThe expression/activity of the studied CYPs decreased with age in the liver of wild-type rats. The deprivation of serotonin in the brain of aging males decreased the mRNA level of most of the studied CYPs (CYP1A/2A/2B/3A), and lowered the protein level of CYP2C11 and CYP3A. In contrast, the activities of CYP2C11, CYP3A and CYP2C6 were increased. The expression of cytochrome b5 decreased in aging rats, but increased in TPH2-deficient senescent animals. The serum concentration of growth hormone declined in the aged and further dropped down in TPH2-deficient senescent rats.ConclusionsRat liver cytochrome P450 functions deteriorate with age, which may impair drug metabolism. The TPH2 knockout, which deprives brain serotonin, affects cytochrome P450 expression and activity differently in mature and senescent male rats.

Cytochrome P450 activity in rheumatoid arthritis patients during continuous IL-6 receptor antagonist therapy

BackgroundInflammation suppresses cytochrome P450 (CYP) enzyme activity, and single-dose interleukin 6 receptor antagonists (anti-IL-6R) reverse this effect. Here, we assess the impact of continuous anti-IL-6R therapy in patients with rheumatoid arthritis.MethodsIn a clinical pharmacokinetic trial, the Basel cocktail was administered before and after 3 and 12 weeks of anti-IL-6R therapy to assess CYP enzyme activity (registered in the ClinicalTrials.gov database (identifier NCT04842981) on April 13th, 2021). In a retrospective study, the 4β-hydroxycholesterol/cholesterol ratio was measured as a biomarker for CYP3A4 activity before and after 3 and 6 months of anti-IL-6R therapy. The control group was patients initiating a tumor necrosis factor alfa (TNF-α) inhibitor.ResultsIn the clinical pharmacokinetic trial (n = 3), midazolam metabolic ratio (CYP3A4) was inconclusive due to the limited sample size. Midazolam AUC and Cmax indicate a weak impact on CYP3A4 activity after 3 weeks of anti-IL-6R therapy compared to baseline (AUC geometric mean ratio (GMR): 0.80, 95% CI: 0.64–0.99 and Cmax GMR: 0.58, 95% CI: 0.37–0.91), which returns to baseline levels after 12 weeks of therapy (AUC GMR 1.02, 95% CI: 0.72–1.46 and Cmax GMR 1.03, 95% CI 0.72–1.47). No effect on the 4β-hydroxycholesterol/cholesterol ratio was observed in the retrospective study.ConclusionBased on sparse data from three patients, continuous anti-IL-6R therapy seems to cause an acute but transient increase in CYP3A4 activity in rheumatoid arthritis patients, which may be due to a normalization of the inflammation-suppressed CYP activity. Further studies are warranted to understand the mechanism behind this putative transient effect.Trial registration Registered in the ClinicalTrials.gov database (identifier NCT04842981) on April 13th, 2021.

Drug interaction potential of high-dose rifampicin in patients with pulmonary tuberculosis.

Accumulating evidence supports the use of higher doses of rifampicin for tuberculosis (TB) treatment. Rifampicin is a potent inducer of metabolic enzymes and drug transporters, resulting in clinically relevant drug interactions. To assess the drug interaction potential of higher doses of rifampicin, we compared the effect of high-dose rifampicin (40 mg/kg daily, RIF40) and standard-dose rifampicin (10 mg/kg daily, RIF10) on the activities of major cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp). In this open-label, single-arm, two-period, fixed-order phenotyping cocktail study, adult participants with pulmonary TB received RIF10 (days 1-15), followed by RIF40 (days 16-30). A single dose of selective substrates (probe drugs) was administered orally on days 15 and 30: caffeine (CYP1A2), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A), and digoxin (P-gp). Intensive pharmacokinetic blood sampling was performed over 24 hours after probe drug intake. In all, 25 participants completed the study. Geometric mean ratios (90% confidence interval) of the total exposure (area under the concentration versus time curve, RIF40 versus RIF10) for each of the probe drugs were as follows: caffeine, 105% (96%-115%); tolbutamide, 80% (74%-86%); omeprazole, 55% (47%-65%); dextromethorphan, 77% (68%-86%); midazolam, 62% (49%-78%), and 117% (105%-130%) for digoxin. In summary, high-dose rifampicin resulted in no additional effect on CYP1A2, mild additional induction of CYP2C9, CYP2C19, CYP2D6, and CYP3A, and marginal inhibition of P-gp. Existing recommendations on managing drug interactions with rifampicin can remain unchanged for the majority of co-administered drugs when using high-dose rifampicin. Clinical Trials registration number NCT04525235.

Pharmacokinetic analysis of acute and dietary exposure to piperonyl butoxide in the mouse

Piperonyl butoxide (PBO) is a popular insecticide synergist present in thousands of commercial, agricultural, and household products. PBO inhibits cytochrome P450 activity, impairing the ability of insects to detoxify insecticides. PBO was recently discovered to also inhibit Sonic hedgehog signaling, a pathway required for embryonic development, and rodent studies have demonstrated the potential for in utero PBO exposure to cause structural malformations of the brain, face, and limbs, or more subtle neurodevelopmental abnormalities. The current understanding of the pharmacokinetics of PBO in mice is limited, particularly with respect to dosing paradigms associated with developmental toxicity. To establish a pharmacokinetic (PK) model for oral exposure, PBO was administered to female C57BL/6J mice acutely by oral gavage (22–1800 mg/kg) or via diet (0.09 % PBO in chow). Serum and adipose samples were collected, and PBO concentrations were determined by HPLC-MS/MS. The serum concentrations of PBO were best fit by a linear one-compartment model. PBO concentrations in visceral adipose tissue greatly exceeded those in serum. PBO concentrations in both serum and adipose tissue decreased quickly after cessation of dietary exposure. The elimination half-life of PBO in the mouse after gavage dosing was 6.5 h (90 % CI 4.7–9.5 h), and systemic oral clearance was 83.3 ± 20.5 mL/h. The bioavailability of PBO in chow was 41 % that of PBO delivered in olive oil by gavage. Establishment of this PK model provides a foundation for relating PBO concentrations that cause developmental toxicity in the rodent models to Sonic hedgehog signaling pathway inhibition.

Adverse outcome pathway exploration of furan-induced liver fibrosis in rats: Genotoxicity pathway or oxidative stress pathway through CYP2E1 activation?

Furan is a widespread endogenous contaminant in heat-processed foods that can accumulate rapidly in the food chain and has been widely detected in foods, such as wheat, bread, coffee, canned meat products, and baby food. Dietary exposure to this chemical may bring health risk. Furan is classified as a possible category 2B human carcinogen by the International Agency for Research on Cancer, with the liver as its primary target organ. Hepatic fibrosis is the most important nontumoral harmful effect of furan and also an important event in the carcinogenesis of furan. Although the specific mechanism of furan-induced liver fibrosis is still unclear, it may involve oxidative stress and genetic toxicity, in which the activation of cytochrome P450 2E1 (CYP2E1) may be the key event. Thus, we conducted a study using an integrating multi-endpoint genotoxicity platform in 120-day in vivo subchronic toxicity test in rats. Results showed that the rats with activated CYP2E1 exhibited DNA double-strand breaks in D4, gene mutations in D60, and increased expression of reactive oxygen species and nuclear factor erythroid 2-related factor 2 in D120. Necrosis, apoptosis, hepatic stellate cell activation, and fibrosis also occurred in the liver, suggesting that furan can independently affect liver fibrosis through oxidative stress and genotoxicity pathways. Point of Departure (PoD) was obtained by benchmark-dose (BMD) method to establish health-based guidance values. The human equivalent dose of PoD derived from BMDL05 was 2.26 μg/kg bw/d. The findings laid a foundation for the safety evaluation and risk assessment of furan and provided data for the further construction and improvement of the adverse outcome pathway network in liver fibrosis.