Involvement of interleukin-6 and tumor necrosis factor alpha in CYP3A11 and 2C29 down-regulation by Bacillus Calmette-Guerin and lipopolysaccharide in mouse liver

Downregulation of the gene expression of Cyp2c29 and Cyp3a11 by cecal ligation and puncture-induced sepsis is associated with interleukin-6

Sepsis is a pathological condition that affects the metabolism of administered drugs, leading to changes in the duration and intensity of their intended efficacies. Proinflammatory cytokines downregulate the expression of cytochrome P450s (P450s). The effects of P450 expression under inflammatory conditions have been studied using prophlogistic substances such as lipopolysaccharide; however, few studies have focused on clinical models of sepsis. Here, we show that cecal ligation and puncture (CLP), an approach for the study of human polymicrobial sepsis, leads to the expression of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor α (TNFα) at 24 h after the CLP operation. Following CLP, IL-6^-/- mice exhibited markedly lower survival than WT mice. In addition, CLP led to the significant downregulation of Cyp2c29 and Cyp3a11 gene expression in IL-1α^-/-/β^-/- (IL-1^-/-) and TNFα^-/- mice as well as in WT mice. In contrast, CLP elicited no significant effect on Cyp3a11 expression in IL-6^-/- mice. Although CLP reduced the Cyp2c29 expression level in IL-6^-/- mice, the expression of Cyp2c29 was lower in CLP-operated WT mice than in CLP-operated IL-6^-/- mice. The reduction in the respective P450 protein levels and activities due to CLP-induced sepsis, reflected in the mRNA expression levels, was abolished by IL-6 depletion. Thus, CLP-induced sepsis downregulates P450 gene expression, particularly Cyp2c expression, and this effect is associated with IL-6 without affecting resistance to CLP-induced sepsis. These findings demonstrate the usefulness of CLP for studying the regulation of P450s and highlight IL-6 as a potential indicator of drug-metabolizing capacity under septic conditions.

Effect of antibiotic-administration period on hepatic bile acid profile and expression of pharmacokinetic-related proteins in mouse liver, kidney, and brain capillaries

Antibiotic administration affects pharmacokinetics through changes in the intestinal microbiota, and bile acids are involved in this regulation. The purpose of the present study was to clarify the effect of different periods of antibiotic administration on the hepatic bile acid profile and expression of pharmacokinetic-related proteins in mouse liver, kidney, and brain capillaries. Vancomycin and polymyxin B were orally administered to mice for either 5- or 25-days. The hepatic bile acid profile of the 25-day treatment group was distinct. In the liver, the protein expression of cytochrome P450 (Cyp)3a11 showed the greatest reduction to 11.4% after the 5-day treatment and further reduced to 7.01% after the 25-day treatment. Similar reductions were observed for sulfotransferase 1d1, Cyp2b10, carboxylesterase 2e, UDP-glucuronosyltransferase (Ugt)1a5, and Ugt1a9. In the kidney and brain capillaries, no drug-metabolizing enzymes or drug transporters were changed with >1.5-fold or <0.66-fold statistical significance in either period. These results suggest that bile acids and metabolizing enzymes in the liver are affected in a period-dependent manner by antibiotic treatment, while the blood-brain barrier and kidneys are less affected. Drug-drug interactions of antibiotics via the intestinal microbiota should be considered by changing drug metabolism in the liver.

CYP2C and CYP2B Mediated Metabolic Activation of Retrorsine in Cyp3a Knockout Mice

Background:

Retrorsine is one of the hepatotoxic pyrrolizidine alkaloids, which could be converted into a highly reactive metabolite, dehydroretrorsine, by CYP3A, and to a lesser extent by CYP2C and CYP2B.

Objective:

We employed Cyp3a knockout (3AKO) mice to investigate whether the absence of CYP3A could attenuate dehydroretrorsine formation and the role of CYP2C and CYP2B in the formation.

Methods:

Blood and liver samples were collected after intragastrical administration of 35 mg/kg retrorsine or saline for seven days in wild-type (WT) and 3AKO mice. Blood pyrrole-protein adducts were semi quantified by high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. The formations of glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (GSH-DHP) and the activities of CYP3A, CYP2B and CYP2C were evaluated in the liver microsomes of WT and 3AKO mice before and after treatment. The metabolic phenotype of retrorsine was determined in human liver microsomes. The gene and protein expression of retrorsine metabolism-related CYP450s in the liver was measured by quantitative real-time PCR method and western blotting method. The serum cytokine level was detected by the ELISA method to reveal the potential mechanism of Cyp3a, Cyp2b and Cyp2c downregulation.

Results:

After an oral administration of 35 mg/kg retrorsine for seven days, the blood exposures of DHP adducts between WT and 3AKO mice were similar, consistent with the comparable formation of GSH-DHP in their liver microsomes. The chemical inhibitor experiment in liver microsomes indicated the predominant role of CYP3A and CYP2C in GSH-DHP formation in WT and 3AKO mice, respectively. Real-time qPCR analysis showed that the expressions of Cyp2b10 and Cyp2cs increased 2.3-161-fold in 3AKO mice, which was consistent with protein changes. The increased CYP2B activity in 3AKO mice supported the potential role of CYP2B in GSH-DHP formation. After a seven-day treatment of retrorsine, the yields of GSH-DHP were lower than the untreated ones in both alleles, accompanied by the decreased mRNA of Cyp3a, Cyp2b and Cyp2c. The increased serum IL6 might mediate the retrorsine-induced downregulation of Cyp450s.

Conclusion:

These data demonstrated the increased transcription of Cyp2c and Cyp2b caused by Cyp3a ablation, which played a vital role in the metabolic activation of retrorsine, and long-term exposure of retrorsine can reduce the CYP450 activities.

[Pharmacokinetic changes related to acute infection. Examples from the SARS-CoV-2 pandemic]

The knowledge of factors of pharmacokinetic variability is important in order to personalize pharmacological treatment, particularly for drugs with a narrow therapeutic range for which pharmacological therapeutic monitoring is recommended. Inflammation is a protective response against acute infections and injuries that contributes to intra- and inter-individual variability in drug exposure by modulating the activity of enzymes involved in drug metabolism, and by altering the binding of drugs to plasma proteins. The understanding of the impact of inflammation on drug metabolism and the related clinical consequences allow to better take into consideration the effect of inflammation on the variability of drug exposure. We first summarized the molecular mechanisms by which inflammation contributes to the inhibition of drug metabolism enzymes. We then presented an updated overview of the consequences of the outcome of acute infectious event on pharmacokinetic exposure of drugs with a narrow therapeutic range and that are substrates of cytochrome P450, and the related clinical consequences. Finally, in the context of the COVID-19 pandemic, we reported examples of drug overexposures in COVID- 19 infected patients.

Potential role of drug metabolizing enzymes in chemotherapy-induced gastrointestinal toxicity and hepatotoxicity

INTRODUCTION

Toxicity of chemotherapy drugs is the leading cause of poor therapeutic outcome in many cancer patients. Gastrointestinal (GI) toxicity and hepatotoxicity are among the most common side effects of current chemotherapies. Emerging studies indicate that many chemotherapy-induced toxicities are driven by drug metabolism, but very few reviews summarize the role of drug metabolism in chemotherapy-induced GI toxicity and hepatotoxicity. In this review, we highlighted the importance of drug metabolizing enzymes (DMEs) in chemotherapy toxicity.

AREAS COVERED

Our review demonstrated that altered activity of DMEs play important role in chemotherapy-induced GI toxicity and hepatotoxicity. Besides direct changes in catalytic activities, the transcription of DMEs is also affected by inflammation, cell-signaling pathways, and/or by drugs in cancer patients due to the disease etiology.

EXPERT OPINION

More studies should focus on how DMEs are altered during chemotherapy treatment, and how such changes affect the metabolism of chemotherapy drug itself. This mutual interaction between chemotherapies and DMEs can lead to excessive exposure of parent drug or toxic metabolites which ultimately cause GI adverse effect.

Regulation of cytochrome P450 enzyme activity and expression by nitric oxide in the context of inflammatory disease

Many hepatic cytochrome P450 enzymes and their associated drug metabolizing activities are down-regulated in disease states, and much of this has been associated with inflammatory cytokines and their signaling pathways. One such pathway is the induction of inducible nitric oxide synthase (NOS2) and generation of nitric oxide (NO) in many tissues and cells including the liver and hepatocytes. Experiments in the 1990s demonstrated that NO could bind to and inhibit P450 enzymes, and suggested that inhibition of NOS could attenuate, and NO generation could mimic, the down-regulation by inflammatory stimuli of not only P450 catalytic activities but also of mRNA expression and protein levels of certain P450 enzymes. This review will summarize and examine the evidence that NO functionally inhibits and down-regulates P450 enzymes in vivo and in vitro, with a particular focus on the mechanisms by which these effects are achieved.

Nrf2 Antioxidative System is Involved in Cytochrome P450 Gene Expression and Activity: A Delay in Pentobarbital Metabolism in Nrf2-Deficient Mice

NF-E2-related factor 2 (Nrf2) is a transcriptional regulator of biologic defense proteins, such as antioxidant proteins and phase II detoxification enzymes. Cytochrome P450 (P450) enzymes have been shown to regulate phase I metabolism of various drugs and are partially regulated by Nrf2; however, the influence of Nrf2 on drug pharmacokinetics is not known. Here, we showed that Nrf2 depletion prolonged the effect of pentobarbital, a sleep-promoting drug. Pretreatment with phenobarbital, a P450 inducer, shortens the sleeping time associated with pentobarbital-induced sedation in wild-type (WT) mice; however, this effect was not observed in Nrf2-/- mice. Furthermore, the blood pentobarbital concentration was higher in Nrf2-/- mice than in WT mice at 30-60 minutes, and the phenobarbital-induced enhancement of its clearance was attenuated in Nrf2-/- mice compared with WT mice. Total P450 content was decreased in Nrf2-/- mouse livers, and the phenobarbital-induced increase in P450 content was lower in Nrf2-/- mice than WT mice. Cyp1a2, Cyp2a5, Cyp2c29, and Cyp2e1 gene expression levels under physiologic conditions and Cyp1a2, Cyp2a5, and Cyp2b10 gene expression levels under phenobarbital-treated conditions were lower in Nrf2-/- mice compared with WT mice. Additionally, pentobarbital metabolism in liver microsomes was attenuated by Nrf2 depletion. Taken together, these findings suggested that Nrf2 influenced pentobarbital pharmacokinetics through the regulation of drug metabolism and P450 gene expression. Thus, Nrf2-mediated regulation of P450 may contribute to the biologic defense against increased reactive oxygen species production. SIGNIFICANCE STATEMENT: NF-E2-related factor 2 (Nrf2) plays a critical role in the cellular defense against oxidative stress. Nrf2-/- mice with reduced ability to eliminate reactive oxygen species (ROS) showed a significant delay in emergence from pentobarbital-induced sleep, which was associated with decreased P450 activities and gene expression. Our findings provide that Nrf2 dysfunction or ROS that exceed a threshold level of the eliminating ability of the Nrf2 system may reduce P450 activity.

Cytochrome P450-mediated drug interactions in COVID-19 patients: Current findings and possible mechanisms

At the end of 2019, the entire world has witnessed the birth of a new member of coronavirus family in Wuhan, China. Ever since, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has swiftly invaded every corner on the planet. By the end of April 2020, almost 3.5 million cases have been reported worldwide, with a death toll of about 250,000 deaths. It is currently well-recognized that patient’s immune response plays a pivotal role in the pathogenesis of Coronavirus Disease 2019 (COVID-19). This inflammatory element was evidenced by its elevated mediators that, in severe cases, reach their peak in a cytokine storm. Together with the reported markers of liver injury, such hyperinflammatory state may trigger significant derangements in hepatic cytochrome P450 metabolic machinery, and subsequent modulation of drug clearance that may result in unexpected therapeutic/toxic response. We hypothesize that COVID-19 patients are potentially vulnerable to a significant disease-drug interaction, and therefore, suitable dosing guidelines with therapeutic drug monitoring should be implemented to assure optimal clinical outcomes.

Regulation of drug-metabolizing enzymes in infectious and inflammatory disease: implications for biologics-small molecule drug interactions

INTRODUCTION

Drug-metabolizing enzymes (DMEs) are primarily down-regulated during infectious and inflammatory diseases, leading to disruption in the metabolism of small molecule drugs (smds), which are increasingly being prescribed therapeutically in combination with biologics for a number of chronic diseases. The biologics may exert pro- or anti-inflammatory effect, which may in turn affect the expression/activity of DMEs. Thus, patients with infectious/inflammatory diseases undergoing biologic/smd treatment can have complex changes in DMEs due to combined effects of the disease and treatment. Areas covered: We will discuss clinical biologics-SMD interaction and regulation of DMEs during infection and inflammatory diseases. Mechanistic studies will be discussed and consequences on biologic-small molecule combination therapy on disease outcome due to changes in drug metabolism will be highlighted. Expert opinion: The involvement of immunomodulatory mediators in biologic-SMDs is well known. Regulatory guidelines recommend appropriate in vitro or in vivo assessments for possible interactions. The role of cytokines in biologic-SMDs has been documented. However, the mechanisms of drug-drug interactions is much more complex, and is probably multi-factorial. Studies aimed at understanding the mechanism by which biologics effect the DMEs during inflammation/infection are clinically important.

Co-culture of Hepatocytes and Kupffer Cells as an In Vitro Model of Inflammation and Drug-Induced Hepatotoxicity

Immune-mediated drug-induced hepatotoxicity is often unrecognized as a potential mode of action due to the lack of appropriate in vitro models. We have established an in vitro rat donor-matched hepatocyte and Kupffer cell co-culture (HKCC) model to study immune-related responses to drug exposure. Optimal cell culture conditions were identified for the maintenance of co-cultures based on cell longevity, monolayer integrity, and cytokine response after lipopolysaccharide (LPS) exposure. Hepatocyte monocultures and HKCCs were then used to test a subset of compounds associated with hepatotoxic effects with or without LPS. Cytokine levels and metabolic activity (cytochrome P450 3A [Cyp3A]) were measured after a 48-h exposure to monitor endotoxin-induced changes in acute phase and functional end points. LPS-activated HKCCs, but not hepatocyte monocultures, treated with trovafloxacin or acetaminophen, compounds associated with immune-mediated hepatotoxicity, showed LPS-dependent decreases in interleukin-6 production with concomitant increases in Cyp3A activity. Differential endotoxin- and model-dependent alterations were observed in cytokine profiles and Cyp3A activity levels that corresponded to specific compounds. These results indicate the utility of the HKCC model system to discern compound-specific effects that may lead to enhanced or mitigate hepatocellular injury due to innate or adaptive immune responses.

Inflammation-induced phenoconversion of polymorphic drug metabolizing enzymes: hypothesis with implications for personalized medicine

Phenoconversion transiently converts genotypic extensive metabolizers (EMs) into phenotypic poor metabolizers (PMs) of drugs, potentially with corresponding changes in clinical response. This phenomenon, typically resulting from coadministration of medications that inhibit certain drug metabolizing enzymes (DMEs), is especially well documented for enzymes of the cytochrome P450 family. Nonclinical evidence gathered over the last two decades also strongly implicates elevated levels of some proinflammatory cytokines, released during inflammation, in down-regulation of drug metabolism, especially by certain DMEs of the P450 family, thereby potentially causing transient phenoconversion. Clinically, phenoconversion of NAT2, CYP2C19, and CYP2D6 has been documented in inflammatory conditions associated with elevated cytokines, such as human immunodeficiency virus infection, cancer, and liver disease. The potential of other inflammatory conditions to cause phenoconversion has not been studied but experimental and anecdotal clinical evidence supports infection-induced down-regulation of CYP1A2, CYP3A4, and CYP2C9 as well. Collectively, the evidence supports a hypothesis that certain inflammatory conditions associated with elevated proinflammatory cytokines may cause phenoconversion of certain DMEs. Since inflammatory conditions associated with elevated levels of proinflammatory cytokines are highly prevalent, phenoconversion of genotypic EM patients into transient phenotypic PMs may be more frequent than appreciated. Since drug pharmacokinetics, and therefore the clinical response, is influenced by DME phenotype rather than genotype per se, phenoconversion (whatever its cause) can have a significant impact on the analysis and interpretation of genotype-focused clinical outcome association studies. There is a risk that focusing on genotype alone may miss important associations between clinical outcomes and DME phenotypes, thus compromising future prospects of personalized medicine.

Selective effects of a therapeutic protein targeting tumor necrosis factor-alpha on cytochrome P450 regulation during infectious colitis: Implications for disease-dependent drug-drug interactions

We studied the impact of administering XPro1595, a novel antagonist of soluble tumor necrosis factor-α(TNFα), on the regulation of hepatic cytochrome P450 enzymes in the Citrobacter rodentium model of infectious colitis. XPro1595 was administered subcutaneously every 3 days throughout the infection, or as a single injection near the peak of infection. When given throughout the infection, XPro1595 selectively blocked the downregulation of Cyp3a11 and 3a25 mRNAs, as well as the induction of Cyp2a4/5, without affecting the downregulation of Cyp4a10, Cyp4a14, Cyp2b10, or flavin-mooxygenase-3. Induction of Cyp3a11, Cyp3a25, Cyp2c29, and Cyp3a13 mRNAs were observed only in XPro1595-treated mice. Administration of a single dose of XPro1595 was relatively ineffective. These results (1) confirm the role of soluble TNFα in hepatic Cyp3a regulation during infectious colitis deduced from studies in TNFα receptor-1 knockout mice; (2) indicate the potential for soluble TNFα -specific antagonists to cause disease-dependent drug–drug interactions; and (3) suggest a novel mechanism by which an anti-inflammatory therapeutic protein can produce an opposite effect to that of the disease by selectively neutralizing one of multiple signals regulating drug-metabolizing enzyme expression. More research is needed to determine whether or not this is applicable to other diseases or disease models.

Hepatic cytochrome P450s, phase II enzymes and nuclear receptors are downregulated in a Th2 environment during Schistosoma mansoni infection

Inflammation and infection downregulate the activity and expression of cytochrome P450s (P450s) and other drug metabolizing enzymes (DMEs) involved in hepatic drug clearance. Schistosoma mansoni infection was reported to cause a downregulation of hepatic P450-dependent activities in mouse liver, but little is known about the specific enzymes affected or whether phase II DMEs are also affected. Here we describe the effect of murine schistosomiasis on the expression of hepatic P450s, NADPH-cytochrome P450 reductase (Cpr), phase II drug metabolizing enzymes, and nuclear receptors at 30 and 45 days postinfection (dpi). Although the hepatic expression of some of these genes was altered at 30 dpi, we observed substantial changes in the expression of the majority of P450 mRNAs and proteins measured, Cpr protein, as well as many of the UDP-glucuronosyltransferases and sulfotransferases at 45 dpi. S. mansoni infection also altered nuclear receptor expression, inducing mRNA levels at 30 dpi and depressing levels at 45 dpi. S. mansoni evoked a T helper 2 (Th2) inflammatory response at 45 dpi, as indicated by the induction of hepatic Th2 cytokine mRNAs [interleukins 4, 5, and 13], whereas the hepatic proinflammatory response was relatively weak. Thus, chronic schistosomiasis markedly and selectively alters the expression of multiple DMEs, which may be associated with Th2 cytokine release. This would represent a novel mechanism of DME regulation in disease states. These findings have important implications for drug testing in infected mice, whereas the relevance to humans with schistosomiasis needs to be determined.

Nuclear receptors in the cross-talk of drug metabolism and inflammation

Inflammation and infection have long been known to affect the activity and expression of enzymes involved in hepatic and extrahepatic drug clearance. Significant advances have been made to elucidate the molecular mechanisms underlying the complex cross-talk between inflammation and drug-metabolism alterations. The emergent role of ligand-activated transcriptional regulators, belonging to the nuclear receptor (NR) superfamily, is now well established. The NRs, pregnane X receptor, constitutive androstane receptor, retinoic X receptor, glucocorticoid receptor, and hepatocyte nuclear factor 4, and the basic helix-loop-helix/Per-ARNT-Sim family member, aryl hydrocarbon receptor, are the main regulators of the detoxification function. According to the panel of mediators secreted during inflammation, a cascade of numerous signaling pathways is activated, including nuclear factor kappa B, mitogen-activated protein kinase, and the Janus kinase/signal transducer and activator of transcription pathways. Complex cross-talk is established between these signaling pathways regulating either constitutive or induced gene expression. In most cases, a mutual antagonism between xenosensor and inflammation signaling occurs. This review focuses on the molecular and cellular mechanisms implicated in this cross-talk.

Consumption of a high-fat diet during pregnancy changes the expression of cytochrome P450 in the livers of infant male mice

It has been recently reported that the consumption of a high-fat diet during pregnancy exerts various effects on fetuses and newborn mice. The purpose of this study was to determine the effects of a high-fat diet during pregnancy on the expression of cytochrome P450 (CYP) in the livers of offspring. Mouse dams were fed a high-fat diet during pregnancy from the time of conception. After their birth, the newborn mice were fed a normal diet until 12 weeks of age. In the livers of the infant male mice that consumed a high-fat diet, the protein expression of CYP3A and CYP2C was decreased, and the protein expression of CYP1A and CYP2E was increased at 6 and 12 weeks of age. However, almost no changes were observed in the CYP proteins at 6 and 12 weeks of age in the livers of the infant female mice that consumed a high-fat diet. The amount of pregnane X receptor (PXR) translocated into the nucleus was reduced in the livers of infant male mice that consumed a high-fat diet. However, there was neither an increase in tumor necrosis factor-α or interleukin-1β nor a decrease in lithocholic acid. These data suggested that CYP3A and CYP2C might decrease as a result of the decrease in the amount of nuclear PXR in infant male mice that consumed a high-fat diet. The results of this study suggested that the consumption of a high-fat diet by pregnant mothers may be one explanation for individual differences in pharmacokinetics.

Selective role for tumor necrosis factor-α, but not interleukin-1 or Kupffer cells, in down-regulation of CYP3A11 and CYP3A25 in livers of mice infected with a noninvasive intestinal pathogen

Hepatic cytochrome P450 (P450) gene and protein expression are modulated during inflammation and infection. Oral infection of C57BL/6 mice with Citrobacter rodentium produces mild clinical symptoms while selectively regulating hepatic P450 expression and elevating levels of proinflammatory cytokines. Here, we explored the role of cytokines in the regulation of hepatic P450 expression by orally infecting tumor necrosis factor-α (TNFα) receptor 1 null mice (TNFR1-/-), interleukin-1 (IL1) receptor null mice (IL1R1-/-), and Kupffer cell depleted mice with C. rodentium. CYP4A mRNA and protein levels and flavin monooxygenase (FMO)3 mRNA expression levels were down-regulated, while CYP2D9 and CYP4F18 mRNAs remained elevated during infection in wild-type, receptor knockout, and Kupffer cell depleted mice. CYPs 3A11 and 3A25 mRNA levels were down-regulated during infection in wild-type mice but not in TNFR1-/- mice. Consistent with this observation, CYPs 3A11 and 3A25 were potently down-regulated in mouse hepatocytes treated with TNFα. Oral infection of IL1R1-/- mice and studies with mouse hepatocytes indicated that IL1 does not directly regulate CYP3A11 or CYP3A25 expression. Uninfected mice injected with clodronate liposomes had a significantly reduced number of Kupffer cells in their livers. Infection increased the Kupffer cell count, which was attenuated by clodronate treatment. The P450 mRNA and cytokine levels in infected Kupffer cell depleted mice were comparable to those in infected mice receiving no clodronate. The results indicate that TNFα is involved in the regulation of CYPs 3A11 and 3A25, but IL1β and Kupffer cells may not be relevant to hepatic P450 regulation in oral C. rodentium infection.

Differential role of Toll-interleukin 1 receptor domain-containing adaptor protein in Toll-like receptor 2-mediated regulation of gene expression of hepatic cytokines and drug-metabolizing enzymes

Pharmacological activities of drugs are impaired during inflammation because of reduced expression of hepatic drug-metabolizing enzyme genes (DMEs) and their regulatory nuclear receptors (NRs): pregnane X receptor (PXR), constitutive androstane receptor (CAR), and retinoid X receptor (RXRα). We have shown that a component of Gram-positive bacteria, lipoteichoic acid (LTA) induces proinflammatory cytokines and reduces gene expression of hepatic DMEs and NRs. LTA is a Toll-like receptor 2 (TLR2) ligand, which initiates signaling by recruitment of Toll-interleukin 1 receptor domain-containing adaptor protein (TIRAP) to the cytoplasmic TIR domain of TLR2. To determine the role of TIRAP in TLR2-mediated regulation of DME genes, TLR2(+/+), TLR2(-/-), TIRAP(+/+), and TIRAP(-/-) mice were given LTA injections. RNA levels of the DMEs (Cyp3a11, Cyp2b10, and sulfoaminotransferase), xenobiotic NRs (PXR and CAR), and nuclear protein levels of the central NR RXRα were reduced ∼ 50 to 60% in LTA-treated TLR2(+/+) but not in TLR2(-/-) mice. Induction of hepatic cytokines (interleukin-1β, tumor necrosis factor-α, and interleukin-6), c-Jun NH(2)-terminal kinase, and nuclear factor-κΒ was blocked in TLR2(-/-) mice. As expected, expression of hepatic DMEs and NRs was reduced by LTA in TIRAP(+/+) but not in TIRAP(-/-) mice. Of interest, cytokine RNA levels were induced in the livers of both the TIRAP(+/+) and TIRAP(-/-) mice, whereas LTA-mediated induction of serum cytokines was attenuated in TIRAP(-/-) mice. LTA-mediated down-regulation of DME genes was attenuated in hepatocytes from TLR2(-/-) or TIRAP(-/-) mice and in small interfering RNA-treated hepatocytes. Thus, the effect of TLR2 on DME genes in hepatocytes was mediated by TIRAP, whereas TIRAP was not involved in mediating the effects of TLR2 on cytokine expression in the liver.

Modulation of hepatic cytochrome P450s by Citrobacter rodentium infection in interleukin-6- and interferon-{gamma}-null mice

After infection with Citrobacter rodentium, murine hepatic cytochrome P450 (P450) mRNAs are selectively regulated. Several serum proinflammatory cytokines are elevated, the most abundant being interleukin-6 (IL6). To elucidate the role of cytokines in the regulation of P450s during infection, we orally infected wild-type, IL6(-/-), or interferon-γ(-/-) [IFNγ(-/-)] female C57BL/6J mice with C. rodentium and analyzed hepatic P450 expression 7 days later. The majority of P450 mRNAs were equally affected by infection in each genotype, indicating that IL6 and IFNγ are not the primary mediators of P450 down-regulation in this disease model. The down-regulation of CYP3A11 and CYP3A13 and induction of CYP2D9 mRNAs were attenuated in the IL6(-/-) mice, suggesting a role of IL6 in the regulation of only these P450s. Similar evidence implicated IFNγ in the regulation of CYP2D9, CYP2D22, CYP3A11, CYP3A25, and CYP4F18 mRNAs in C. rodentium infection and CYP2B9, CYP2D22, and CYP2E1 in the bacterial lipopolysaccharide model of inflammation. This is the first indication of an in vivo role for IFNγ in hepatic P450 regulation in disease states. The deficiency of IL6 or IFNγ affected serum levels of the other cytokines. Moreover, experiments in cultured hepatocytes demonstrated that tumor necrosis factor α (TNFα) is the most potent and efficacious of the cytokines tested in the regulation of murine P450 expression. It is therefore possible that part of the IFNγ(-/-) and IL6(-/-) phenotypes could be attributed to the reduced levels of TNFα and part of the IFNγ(-/-) phenotype could be caused by reduced levels of IL6.

Hepatic flavin-containing monooxygenase gene regulation in different mouse inflammation models

The objective of the study was to investigate the regulation of hepatic flavin-containing monooxygenases (Fmo) Fmo1, Fmo3, Fmo4, and Fmo5 in three different mouse models of inflammation, including treatment with Citrobacter rodentium, lipopolysaccharide (LPS), and dextran sulfate sodium (DSS). Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate the steady-state mRNA levels for the various Fmo isoforms in these mouse models of inflammation during different treatment time courses. Fmo3 mRNA was most significantly down-regulated in C. rodentium-treated female mice. Fmo1, Fmo3, and Fmo5 mRNAs were also found to be down-regulated in LPS models of inflammation. The significant down-regulation of hepatic FMO3 protein during C. rodentium treatment was confirmed with Western blot analysis of liver microsomes from treated animals. Toll-like receptor (TLR) 4 is known to be responsible for LPS signaling in association with several proteins. To investigate whether TLR4 was responsible for regulation of Fmo genes in both LPS and C. rodentium animal models, Fmo mRNA levels in female wild-type (C3H/HeOuJ) and TLR4 mutant (C3H/HeJ) mice were compared in both inflammatory models by real-time RT-PCR. The results showed that Fmo3 down-regulation during C. rodentium infection is independent of TLR4. Whereas TLR4 is likely to play only a partial role in Fmo1 gene regulation in LPS-treated animals, our results show that the down-regulation of Fmo3 and Fmo5 in this model is TLR4-dependent. Unlike cytochrome P450 regulation measured in the same mouse strains, Fmo3 expression was largely refractory to down-regulation in the DSS model of inflammatory colitis.

Tumor necrosis factor alpha partially contributes to lipopolysaccharide-induced downregulation of CYP3A in fetal liver: its repression by a low dose LPS pretreatment

With embryonic development, fetal hepatocytes gradually express various types of cytochromes P450 (CYPs) that play a key role in the detoxification of xenobiotics. In the present study, we showed that maternal lipopolysaccharide (LPS) exposure downregulated cyp3a11 mRNA and CYP3A protein in fetal liver. The increased level of TNF-alpha protein in fetal liver, transferred from either the maternal circulation or amniotic fluid, seems to be associated with LPS-induced downregulation of cyp3a11 mRNA and CYP3A protein in fetal liver. Interestingly, a low dose LPS (10mug/kg) pretreatment attenuated LPS-induced downregulation of cyp3a11 mRNA and CYP3A protein in fetal liver. Correspondingly, a low dose LPS pretreatment attenuated LPS-induced downregulation of pregnane X receptor (pxr) in fetal liver. Additional experiment showed that a low dose LPS pretreatment decreased the level of TNF-alpha in maternal serum and amniotic fluid and counteracted LPS-induced expression of TNF-alpha mRNA in maternal liver and placenta. Although a low dose LPS pretreatment alleviated LPS-induced increase in TNF-alpha in fetal liver, it had little effect on TNF-alpha mRNA in fetal liver. These results suggest that a low dose LPS pretreatment protects fetuses against LPS-induced downregulation of hepatic cyp3a11 and pxr expression through the repression of maternally sourced TNF-alpha production.

Downregulation of drug transport and metabolism in mice bearing extra-hepatic malignancies

There is increasing evidence of a systemic inflammatory response associated with malignancy, which may have an impact on both drug disposition and resistance to cytotoxic therapy. The impact of inflammation on drug disposition was studied in mice bearing a number of common tumour xenografts. C57BL/6 mice were inoculated with tumour xenografts. Hepatic expressions of Cyp3a and drug transporters were analysed at the mRNA, protein and functional levels (Cyp3a only). Circulating serum cytokines and the hepatic expression of acute phase proteins (APPs) were measured. Intratumoral levels of multidrug resistance genes were determined. Tumour xenografts elicited an inflammatory response that coincided with repression in hepatic Cyp3a11 activity and the expression of a number of hepatic drug transporters. With tumour growth, a progressive reduction in hepatic Cyp3a11 mRNA expression was seen. Conversely, an increase in the hepatic APP expression and circulating interleukin (IL)-6 levels was observed. Furthermore, a correlation was seen between increased intratumoral expression of the multidrug resistance gene, Mdr1a, and levels of circulating IL-6. Malignancy results in reduced hepatic drug disposition that correlates with an associated inflammatory response. Reduction of inflammation may improve the clinical outcome for patients receiving chemotherapeutic agents that undergo hepatic metabolism.

Cytotoxic doses of ketoconazole affect expression of a subset of hepatic genes

Ketoconazole is a widely prescribed antifungal drug, which has also been investigated as an anticancer therapy in both clinical and pre-clinical settings. However, severe hepatic injuries were reported to be associated with the use of ketoconazole, even in patients routinely monitored for their liver functions. Several questions concerning ketoconazole-induced hepatic injury remain unanswered, including (1) does ketoconazole alter cytochrome P450 expression at the transcriptional level?, (2) what types of gene products responsible for cytotoxicity are induced by ketoconazole?, and (3) what role do the major metabolites of ketoconazole play in this pathophysiologic process? A mouse model was employed to investigate hepatic gene expression following hepatotoxic doses of ketoconazole. Hepatic gene expression was analyzed using a toxicogenomic microarray platform, which is comprised of cDNA probes generated from livers exposed to various hepatoxicants. These hepatoxicants fall into five well-studied toxicological categories: peroxisome proliferators, aryl hydrocarbon receptor agonists, noncoplanar polychlorinated biphenyls, inflammatory agents, and hypoxia-inducing agents. Nine genes encoding enzymes involved in Phase I metabolism and one Phase II enzyme (glutathione S-transferase) were found to be upregulated. Serum amyloid A (SAA1/2) and hepcidin were the only genes that were downregulated among the 2364 genes assessed. In vitro cytotoxicity and transcription analyses revealed that SAA and hepcidin are associated with the general toxicity of ketoconazole, and might be usefully explored as generalized surrogate markers of xenobiotic-induced hepatic injury. Finally, it was shown that the primary metabolite of ketoconazole (de-N-acetyl ketoconazole) is largely responsible for the hepatoxicity and the downregulation of SAA and hepcidin.

Gene-specific effects of inflammatory cytokines on cytochrome P450 2C, 2B6 and 3A4 mRNA levels in human hepatocytes

Cytochromes P450 (P450s) are down-regulated in hepatocytes in response to inflammation and infection. This effect has been extensively studied in animal models, but significantly less is known about responses in humans and even less about responses in the absence of inducing agents. This article focuses on the effects of bacterial lipopolysaccaride (LPS), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF), interferon gamma (IFN), transforming growth factor-beta (TGF) and interleukin-1 beta (IL-1) on expression of CYP2B6 and the CYP2C mRNAs in human hepatocytes. These effects were compared with responses of the better studied and more abundant CYP3A4. CYP3A4 and CYP2C8 were down-regulated by all cytokine treatments. CYP2C18, which is expressed at very low levels in liver, was unaffected by cytokine treatments. The other CYP2Cs and CYP2B6 showed cytokine-specific effects. CYP2C9 and CYP2C19 showed almost identical response patterns, being down-regulated by IL-6 and TGF but not significantly affected by LPS, TNF, IFN, or IL-1. CYP2B6 mRNA responded only to IL-6 and IFN. IL-6 down-regulated the mRNAs of all P450s studied. Western blot analysis of P450 protein expression supported the mRNA data to a large extent, although some inconsistencies were observed. Our results show that human CYP2C8, 2C9, 2C18, 2C19, 2B6, and 3A4 responses to inflammation are independently regulated and indicate that this fine control may have a critical effect on human drug responses in disease states.

Effects of Ganoderma lucidum Polysaccharide on CYP2E1, CYP1A2 and CYP3A Activities in BCG-Immune Hepatic Injury in Rats

The purpose of the present study was to investigate the effect of Ganoderma lucidum polysaccharide (GLPS), a major active component in Chinese medicinal fungus, on cytochrome P450 metabolic activity in Bacillus Calmette Guérin (BCG)-induced immune hepatic injury in rats. The enzyme kinetics of the probes including chlorzoxazone (CYP2E1), phenacetin (CYP1A2) and nifedipine (CYP3A) were evaluated by HPLC. The results showed that BCG-pretreatment (125 mg/kg) significantly increased serum levels of alanine transaminase (ALT), nitrite and malondialdehyde (MDA), inhibited activities of superoxide dismutase (SOD) and decreased P450 total content in microsomes (p<0.05). Administration of GLPS (50 and 200 mg/kg) reversed above hepatic injury stimulated by BCG in vivo. Moreover, GLPS dose-dependently inhibited activities of CYP2E1, CYP1A2 and CYP3A in hepatic microsomes in vitro, suggesting that inhibition of GLPS on P450 oxidative metabolism might participate in the hepatoprotective mechanism, and also suggested that pharmacokinetics might be changed by drug-herb interaction.

Effect of interleukin-6 neutralization on CYP3A11 and metallothionein-1/2 expressions in arthritic mouse liver

Rheumatoid arthritis is characterized by chronic inflammation of the synovial tissue. We examined the effect of interleukin (IL)-6 neutralization on the expression of cytochrome P450 or metallothionein-1/2 (metallothionein) during chronic phase inflammatory disease using rheumatoid arthritis model mice, human T-cell leukemia virus type I (HTLV-I) transgenic mice. Serum IL-6 concentrations of arthritis-developed HTLV-I transgenic mice were 129.9+/-26.1 pg/ml. Moreover, signal transducer and activator of transcription (STAT) 1/3 phosphorylations was observed in arthritic HTLV-I transgenic mouse livers. CYP3A11 mRNA was more strongly reduced by the development of arthritis in HTLV-I transgenic mouse livers as compared with CYP2C29 or CYP2E1 mRNAs. CYP3A protein and testosterone 6beta-hydroxylation activity also changed in a similar manner to the corresponding CYP3A11 mRNA level. On the other hand, metallothionein mRNA was significantly induced as compared with that of wild-type or non-arthritic mice. CYP3A suppression and metallothionein mRNA overexpression activity seen in the developed arthritic mice returned to the gene conditions of the non-arthritic HTLV-I transgenic mice by IL-6 antibody at 48 h after treatment. The present study has revealed that CYP3A11 and metallothionein expressions are affected by the release of IL-6 by arthritis and its systemic circulation, and neutralization of IL-6 recovered from the down-regulation of CYP3A11 mRNA and the induction of metallothionein mRNA in arthritic HTLV-I transgenic mice.

Regulation of constitutive mouse hepatic cytochromes P450 and growth hormone signaling components by 3-methylcholanthrene

3-Methylcholanthrene (MC) activates the aryl hydrocarbon receptor and increases expression of cytochrome P450 (P450) enzymes such as CYP1A1. MC also decreases expression of CYP2C11, the major hepatic P450 in male rats that is regulated by pulsatile growth hormone (GH) secretion via a pathway partially dependent on signal transducer and activator of transcription 5b (STAT5b). If disruption of this GH signaling pathway is important for MC's ability to suppress CYP2C11 transcription, we hypothesize that MC suppresses other male-specific genes (e.g., mouse Cyp2d9) regulated by pulsatile GH with STAT5b dependence. We examined the time course of MC's effects on hepatic P450s and GH signaling components in male C57BL/6 mice. P450 content, heme content, and NADPH P450 oxidoreductase activity were induced 2.3-, 1.8-, and 1.3-fold, respectively, by MC. MC dramatically induced CYP1A1 mRNA, protein, and catalytic activity. MC caused a 42% decrease in CYP2D9 protein, a 28% decrease in CYP2D9 mRNA, and a 27% decrease in testosterone 16alpha-hydroxylation activity. MC caused a pronounced decrease in CYP3A protein; however, there was no apparent change in testosterone 6beta-hydroxylation activity, and changes in mRNA levels for CYP3A forms were relatively small. Expression of GH receptor and major urinary protein 2, a gene regulated by GH with STAT5b dependence, was decreased by MC at the mRNA level. These results show that MC suppresses mouse Cyp2d9, a pulsatile GH- and STAT5b-dependent male-specific gene, via a pretranslational mechanism that may involve disrupted GH signaling. Mouse CYP3A protein levels are dramatically decreased by MC via a mechanism that is not yet understood.

Protective effect of paeoniflorin on immunological liver injury induced by bacillus Calmette-Guerin plus lipopolysaccharide: modulation of tumour necrosis factor-alpha and interleukin-6 MRNA

1. Paeoniflorin is one of the main effective components of the total glucosides of paeony (TGP) extracted from the root of Paeonia lactiflora which has been used for gynaecological problems and for cramp, pain and giddiness for over 1,500 years in Chinese medicine. Anti-inflammatory, antioxidative, antihepatic injury and immunoregulatory activities of TGP have been extensively proved in our laboratory for many years. Our present study investigates the effects and mechanisms of paeoniflorin on immunological liver injury in mice. 2. A model of immunological liver injury was induced by tail vein injection of bacillus Calmette-Guérin (BCG) and lipopolysaccharide (LPS) in mice. Activities of serum alanine aminotransferase (ALT) were measured by biochemical methods. Hepatic tissue sections were stained with haematoxylin and eosin and examined under a light microscope. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, lipopolysaccharide binding protein (LBP) and CD14 mRNA (messenger ribonucleic acid) expression in mouse liver were determined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR) analysis. 3. Immunological liver injury induced by BCG plus LPS was successfully duplicated. Serum ALT activities were significantly decreased by paeoniflorin. (25, 50, 100 mg/kg). Histological examination demonstrated that paeoniflorin could attenuate the area and extent of necrosis and reduce the immigration of inflammatory cells. The increase in TNF-alpha, LBP and CD14 mRNA expression in mouse liver after BCG and LPS injection was significantly decreased by paeoniflorin (100 mg/kg) and was changed by paeoniflorin (25, 50 mg/kg) at different time-point. The augmentation of IL-6 mRNA in mouse liver was markedly increased by paeoniflorin at 1 h and 3 h after LPS injection. 4. Paeoniflorin could significantly protect against immunological liver injury in mice. TNF-alpha, IL-6, LBP and CD14 mRNA expression in mouse liver may be involved in BCG plus LPS induced liver injury. The protective mechanism of paeoniflorin might be partially related to modulation of TNF-alpha, IL-6, LBP and CD14 mRNA expressions in mouse liver.

Regulation of drug-metabolizing enzymes and transporters in inflammation

Inflammation and infection have long been known to downregulate the activity and expression of cytochrome P450 (CYP) enzymes involved in hepatic drug clearance. This can result in elevated plasma drug levels and increased adverse effects. Recent information on regulation of human CYP enzymes is presented, as are new developments in our understanding of the mechanisms of regulation. Experiments to study the effects of modulating CYP activities on the inflammatory response have yielded possible insights into the physiological consequences, if not the purpose, of the downregulation. Regulation of hepatic flavin monooxygenases, UDP-glucuronosyltransferases, sulfotransferases, glutathione S-transferases, as well as of hepatic transporters during the inflammatory response, exhibits similarities and differences with regulation of CYPs.

Lipopolysaccharide downregulates the expressions of intestinal pregnane X receptor and cytochrome P450 3a11

The pregnane X receptor is a member of the nuclear receptor superfamily, which heterodimerize with the retinoid X receptor, and is an important regulator of cytochrome P450 3A (CYP3A). Lipopolysaccharide (LPS)-induced downregulation of pregnane X receptor and its target gene cyp3a11 has been well characterized in mouse liver. In the present study, we investigated the effects of LPS on the expressions of pregnane X receptor and its target gene cyp3a11 in mouse intestine. Mice were injected intraperitoneally with different doses of LPS (0.1-5.0 mg/kg). Intestinal pregnane X receptor, retinoid X receptor alphalpha and cyp3a11 mRNA were determined using reverse transcription polymerase chain reaction (RT-PCR). Erythromycin N-demethylase (ERND) activity was used as an indicator of CYP3A expression. Results showed that LPS significantly downregulated the expressions of intestinal pregnane X receptor and its heterodimer retinoid X receptor alpha in a dose-dependent manner. Furthermore, LPS repressed the upregulation of cyp3a11 mRNA and ERND catalytic activity in mice pretreated with pregnane X receptor ligand dexamethasone. Additional experiment showed that LPS significantly increased the level of intestinal thiobarbituric acid-reactive substance, which was attenuated by oral administration with either N-acetylcysteine or ascorbic acid. Correspondingly, oral administration with either N-acetylcysteine or ascorbic acid significantly attenuated LPS-induced downregulation of intestinal pregnane X receptor and retinoid X receptor alphalpha. In addition, these antioxidants prevented the repressive effect of LPS on dexamethasone-inducible cyp3a11 mRNA and ERND activity in mouse intestine. Taken together, these results indicate that LPS suppresses the expressions of pregnane X receptor and its target gene cyp3a11 in mouse intestine. LPS-induced downregulation of pregnane X receptor and cyp3a11 in mouse intestine is mediated, at least in part, by oxidative stress.

Hepatic cytochrome P450 gene regulation during endotoxin-induced inflammation in nuclear receptor knockout mice

Inflammatory agents such as lipopolysaccharide (LPS) down-regulate the hepatic expression of many cytochrome P450 (P450) mRNAs and proteins. Previous studies suggested that suppression of some P450 mRNAs could involve the regulation or modulation of the nuclear receptors peroxisome proliferator-activated receptor alpha (PPARalpha) or pregnane X receptor (PXR). To determine the involvement of these receptors in P450 down-regulation, PPARalpha knockout (KO), PXR KO, and appropriate wild-type (WT) mice were administered either saline or 1 mg/kg LPS. Hepatic mRNA and protein expression of several P450 isoforms, interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF) alpha, alpha1-acid glycoprotein (AGP), and fibrinogen (FBG) were examined 16 h later. LPS administration significantly decreased the hepatic expression of CYP1A2, 2A5, 2C29, 2E1, 3A11, 4A10, and 4A14 mRNAs in both groups of PPARalpha and PXR mice, whereas CYP3A13 mRNA was increased slightly in PPARalpha WT and KO mice, but not in PXR mice. Effects of LPS administration on mouse hepatic P450 proteins (probed using rat P450 2C, 3A, 4A, and 2E antibodies) were consistent with mRNA results in most cases. LPS treatment significantly increased IL-1beta, IL-6, TNFalpha, AGP, and FBG mRNA in both PPARalpha and PXR mice, with the greatest effect observed with TNFalpha. Because decreases in P450 mRNA expression were essentially identical in both WT and KO mice for both nuclear receptors, these data indicate that down-regulation of P450 during inflammation does not require the nuclear receptors PPARalpha and PXR.