Coordinated cytochrome P450 expression in mouse liver and intestine under different dietary conditions during liver regeneration after partial hepatectomy

Pregnane X receptor activation induces liver enlargement and regeneration and simultaneously promotes the metabolic activity of CYP3A1/2 and CYP2C6/11 in rats

Human pregnane X receptor (PXR) is critical for regulating the expression of key drug-metabolizing enzymes such as CYP3A and CYP2C. Our recent study revealed that treatment with rodent-specific PXR agonist pregnenolone-16α-carbonitrile (PCN) significantly induced hepatomegaly and promoted liver regeneration after two-thirds partial hepatectomy (PHx) in mice. However, it remains unclear whether PXR activation induces hepatomegaly and liver regeneration and simultaneously promotes metabolic function of the liver. Here, we investigated the metabolism activity of CYP1A2, CYP3A1/2 and CYP2C6/11 during PXR activation-induced liver enlargement and regeneration in rats after cocktail dosing of CYP probe drugs. For PCN-induced hepatomegaly, a notable increase in the metabolic activity of CYP3A1/2 and CYP2C6/11, as evidenced by the plasma exposure of probe substrates and the AUC ratios of the characteristic metabolites to its corresponding probe substrates. The metabolic activity of CYP1A2, CYP3A1/2 and CYP2C6/11 decreased significantly after PHx. However, PCN treatment obviously enhanced the metabolic activity of CYP2C6/11 and CYP3A1/2 in PHx rats. Furthermore, the protein expression levels of CYP3A1/2 and CYP2C6/11 in liver were up-regulated. Taken together, this study demonstrates that PXR activation not only induces hepatomegaly and liver regeneration in rats, but also promotes the protein expression and metabolic activity of the PXR downstream metabolizing enzymes such as CYP3A1/2 and CYP2C6/11 in the body.

Temporal Dynamics of Metabolic Acquisition in Grafted Engineered Human Liver Tissue

Liver disease affects millions globally, and end-stage liver failure is only cured by organ transplant. Unfortunately, there is a growing shortage of donor organs as well as inequitable access to transplants across populations. Engineered liver tissue grafts that supplement or replace native organ function can address this challenge. While engineered liver tissues have been successfully engrafted previously, the extent to which these tissues express human liver metabolic genes and proteins remains unknown. Here, it is built engineered human liver tissues and characterized their engraftment, expansion, and metabolic phenotype at sequential stages post-implantation by RNA sequencing, histology, and host serology. Expression of metabolic genes is observed at weeks 1-2, followed by the cellular organization into hepatic cords by weeks 4-9.5. Furthermore, grafted engineered tissues exhibited progressive spatially restricted expression of critical functional proteins known to be zonated in the native human liver. This is the first report of engineered human liver tissue zonation after implantation in vivo, which can have important translational implications for this field.

Gut inflammation and adaptive immunity amplify acetaminophen toxicity in bowel and liver

BACKGROUND AND AIM

Prevention of liver failure arising from accidental or deliberate paracetamol (acetaminophen [APAP]) overdose remains a vexed health problem despite well-publicized guidelines for its early detection and treatment. It is recognized that the gut may aggravate liver pathology, via the gut-liver axis. The main aim of this study was to assess the role of the colon in APAP-induced liver toxicity.

METHODS

Liver necrosis and colitis were studied following sublethal doses of APAP administered intraperitoneally to C57Bl/6 wild-type (WT) mice, as well as to C57Bl/6 Winnie mice, which develop a spontaneous colitis caused by a SNP in Muc2, and WT mice with acute DSS-induced colitis. Repeated APAP exposure was studied in WT and Rag1 ko mice that lack mature T and B lymphocytes.

RESULTS

APAP overdose resulted in significant colonic injury in WT mice (P < 0.05), which resolved by 24 h. Underlying colitis was not associated with liver necrosis, but colitis exacerbated APAP-induced liver injury and extended APAP-colonic injury. Prior APAP exposure exacerbated both APAP-liver and APAP-colonic injury more so in WT than Rag1 ko mice. APAP impaired barrier function with increased intestinal permeability and associated bacterial translocation to the liver and spleen in mice with the Winnie phenotype.

CONCLUSIONS

This study identifies novel roles for APAP in causing colitis, the amplification of APAP-liver toxicity where there is underlying colitis, and involvement of immune memory in APAP-toxicity. The latter could be key for decoding the poorly understood but important clinical entity of chronic APAP liver failure.

Alterations of Cytochrome P450-Mediated Drug Metabolism during Liver Repair and Regeneration after Acetaminophen-Induced Liver Injury in Mice

Acetaminophen (APAP)-induced liver injury (AILI) is the leading cause of acute liver failure in the United States, but its impact on metabolism, therapeutic efficacy, and adverse drug reactions (ADRs) of co- and/or subsequent administered drugs are not fully investigated. The current work explored this field with a focus on the AILI-mediated alterations of cytochrome P450-mediated drug metabolism. Various levels of liver injury were induced in mice by treatment with APAP at 0, 200, 400, and 600 mg/kg. Severity of liver damage was determined at 24, 48, 72, and 96 hours by plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), microRNA miR122, and tissue staining. The expression and activities of CYP3A11, 1A2, 2B10, 2C29, and 2E1 were measured. Sedation efficacy and ADRs of midazolam, a CYP3A substrate, were monitored after APAP treatment. ALT, AST, and miR122 increased at 24 hours after APAP treatment with all APAP doses, whereas only groups treated with 200 and 400 mg/kg recovered back to normal levels at 72 and 96 hours. The expression and activity of the cytochromes P450 significantly decreased at 24 hours with all APAP doses but only recovered back to normal at 72 and 96 hours with 200 and 400, but not 600, mg/kg of APAP. The alterations of cytochrome P450 activities resulted in altered sedation efficacy and ADRs of midazolam, which were corrected by dose justification of midazolam. Overall, this work illustrated a low cytochrome P450 expression window after AILI, which can decrease drug metabolism and negatively impact drug efficacy and ADRs. SIGNIFICANCE STATEMENT: The data generated in the mouse model demonstrated that expression and activities of cytochrome P450 enzymes and correlated drug efficacy and ADRs are altered during the time course of liver repair and regeneration after liver is injured by treatment with APAP. Dose justifications based on predicted changes of cytochrome P450 activities can achieve desired therapeutic efficacy and avoid ADRs. The generated data provide fundamental knowledge for translational research to drug treatment for patients during liver recovery and regeneration who have experienced AILI.

Variation in Expression of Cytochrome P450 3A Isoforms and Toxicological Effects: Endo- and Exogenous Substances as Regulatory Factors and Substrates

The CYP3A subfamily, which includes isoforms CYP3A4, CYP3A5, and CYP3A7 in humans, plays important roles in the metabolism of various endogenous and exogenous substances. Gene and protein expression of CYP3A4, CYP3A5, and CYP3A7 show large inter-individual differences, which are caused by many endogenous and exogenous factors. Inter-individual differences can cause negative outcomes, such as adverse drug events and disease development. Therefore, it is important to understand the variations in CYP3A expression caused by endo- and exogenous factors, as well as the variation in the metabolism and kinetics of endo- and exogenous substrates. In this review, we summarize the factors regulating CYP3A expression, such as bile acids, hormones, microRNA, inflammatory cytokines, drugs, environmental chemicals, and dietary factors. In addition, variations in CYP3A expression under pathological conditions, such as coronavirus disease 2019 and liver diseases, are described as examples of the physiological effects of endogenous factors. We also summarize endogenous and exogenous substrates metabolized by CYP3A isoforms, such as cholesterol, bile acids, hormones, arachidonic acid, vitamin D, and drugs. The relationship between the changes in the kinetics of these substrates and the toxicological effects in our bodies are discussed. The usefulness of these substrates and metabolites as endogenous biomarkers for CYP3A activity is also discussed. Notably, we focused on discrimination between CYP3A4, CYP3A5, and CYP3A7 to understand inter-individual differences in CYP3A expression and function.

Assessing the severity of laparotomy and partial hepatectomy in male rats-A multimodal approach

This study assessed the postoperative severity after three different visceral surgical interventions in rats by using objective parameters pertaining to various disciplines. The objective was to evaluate whether the degree of severity increases with the invasiveness of the intervention and whether this is in accordance with the EU Directive 2010/63. 136 adult male WistarHan rats were assigned to three groups: Sham-laparotomy (Sham) [7 days post-surgical survival time]; 50% partial hepatectomy (PH); 70% PH [PH groups with 1, 3, or 7 days post-surgical survival times]. Post-surgical severity assessment was performed via several multimodal assessment tools: I) model-specific score sheet focusing on body weight, general condition, spontaneous behavior, and the animals' willingness to move as well as on wound healing; II) Open Field tests evaluating the total distance and velocity an animal moved within 10 minutes and its rearing behavior during the test; III) telemetric data analyzing heart rate and blood pressure; and IV) analysis of blood (AST, ALT, and hemogram) and fecal samples (fecal corticosterone metabolites). Significant differences among the experimental groups and models were observed. We demonstrated that the Open Field test can detect significant changes in severity levels. Sham-laparotomy and removal of 50% of the liver mass were associated with comparable severity (mild-moderate); the severity parameters returned to baseline levels within seven days. Removal of 70% of the liver tissue seemed to be associated with a moderate severity grade and entailed a longer recovery period (>7 days) for complete regeneration. We recommend the use of Open Field tests as part of multimodal objective severity assessment.