Hepatic cytochrome P450 down-regulation during aseptic inflammation in the mouse is interleukin 6 dependent

The role of sinusoidal endothelial cells and TIMP1 in the regulation of fibrosis in a novel human liver 3D NASH model

BACKGROUND

The prevalence of NAFLD is rapidly increasing. NAFLD can progress to NASH, fibrosis, cirrhosis, and HCC, which will soon become the main causes of liver transplantation. To date, no effective drug for NASH has been approved by the Food and Drug Administration. This is partly due to the lack of reliable human in vitro models. Here, we present a novel human liver spheroid model that can be used to study the mechanisms underlying liver fibrosis formation and degradation.

METHODS AND RESULTS

Such spheroids, which contain hepatocytes, stellate cells, KC, and LSECs, spontaneously develop fibrosis that is exacerbated by treatment with free fatty acids. Conditioned medium from activated LSECs caused similar activation of fibrosis in spheroids containing primary human hepatocyte and NPCs, indicating the action of soluble mediators from the LSECs. Spheroids containing LSECs treated with free fatty acids produced tissue inhibitor of metalloproteinases inhibitor 1, a matrix metalloproteinases inhibitor important for fibrosis progression. Tissue inhibitor of metalloproteinases inhibitor 1 knockdown using siRNA led to a reduction in collagen and procollagen accumulation, which could be partially rescued using a potent matrix metalloproteinases inhibitor. Interestingly, tissue inhibitor of metalloproteinases inhibitor 1 was found to be expressed at higher levels, specifically in a subtype of endothelial cells in the pericentral region of human fibrotic livers, than in control livers.

CONCLUSION

Potential anti-NASH drugs and compounds were evaluated for their efficacy in reducing collagen accumulation, and we found differences in specificity between spheroids with and without LSECs. This new human NASH model may reveal novel mechanisms for the regulation of liver fibrosis and provide a more appropriate model for screening drugs against NASH.

A Case Report of a Patient with Soaring Clozapine Levels after Developing a Urinary Tract Infection

Clozapine is an antipsychotic medicine used to treat mental illnesses that is resistant to therapy. It can induce dose-dependent adverse effects such as increased susceptibility to infections and hematological irregularities. In this case report, we present a 37-year-old woman with schizoaffective disorder who experienced clozapine side effects following a moderate urinary tract infection (UTI). Her serum clozapine levels and side effects were increased throughout her UTI but resolved once the UTI was managed conservatively. We reviewed clozapine's pharmacokinetic properties to understand why serum levels rose during infection. While we could not definitely explain the mechanism of elevation, we emphasize the importance of monitoring serum clozapine levels and keeping watchful for adverse effects, as well as heightened scrutiny, evaluation for recent infections, and regular monitoring of patients.

Attenuation of phenobarbital-induced cytochrome P450 expression in carbon tetrachloride-induced hepatitis in mice models

Certain pathological conditions, such as inflammation, are known to affect basal cytochrome P450 (CYP) expression by modulating transcriptional regulation, and the pharmacokinetics of drugs can vary among patients. However, changes in drug-induced CYP expression under pathological conditions have not been elucidated in detail. Here, we investigated the effects of hepatic inflammation and injury on phenobarbital-induced expression of CYP isoforms in mice. Phenobarbital was administered once as a CYP inducer in the carbon tetrachloride-induced hepatitis model mice. The mRNA expression levels of Cyp3a11 and Cyp2b10 in the liver and small intestine were measured using reverse transcription polymerase chain reaction. The enzymatic activity of CYP3A in liver S9 was evaluated using midazolam as the substrate. Phenobarbital increased the mRNA expression of Cyp3a11 and Cyp2b10 in the liver of healthy mice, but not in the small intestine. Increased mRNA expression of hepatic Cyp3a11 and Cyp2b10 by phenobarbital was significantly suppressed in the hepatitis model mice. Hepatitis also suppressed the increased CYP3A enzymatic activity induced by phenobarbital in liver S9, consistent with the results of Cyp3a11 mRNA expression. These results suggest that the inducibility of CYP by phenobarbital may vary in patients with hepatitis, indicating that pharmacokinetic drug-drug interactions can be altered under certain pathological conditions.

Natural deletion of mouse carboxylesterases Ces1c/d/e impacts drug metabolism and metabolic syndrome development

Mammalian carboxylesterase 1 enzymes can hydrolyze many xenobiotic chemicals and endogenous lipids. We here identified and characterized a mouse strain (FVB/NKI) in which three of the eight Ces1 genes were spontaneously deleted, removing Ces1c and Ces1e partly, and Ces1d entirely. We studied the impact of this Ces1c/d/e deficiency on drug and lipid metabolism and homeostasis. Ces1c/d/e-/- mice showed strongly impaired conversion of the anticancer prodrug irinotecan to its active metabolite SN-38 in plasma, spleen and lung. Plasma hydrolysis of the oral anticancer prodrug capecitabine to 5-DFCR was also profoundly reduced in Ces1c/d/e-/- mice. Our findings resolved previously unexplained FVB/NKI pharmacokinetic anomalies. On a medium-fat diet, Ces1c/d/e-/- female mice exhibited moderately higher body weight, mild inflammation in gonadal white adipose tissue (gWAT), and increased lipid load in brown adipose tissue (BAT). Ces1c/d/e-/- males showed more pronounced inflammation in gWAT and an increased lipid load in BAT. On a 5-week high-fat diet exposure, Ces1c/d/e deficiency predisposed to developing obesity, enlarged and fatty liver, glucose intolerance and insulin resistance, with severe inflammation in gWAT and increased lipid load in BAT. Hepatic proteomics analysis revealed that the acute phase response, involved in the dynamic cycle of immunometabolism, was activated in these Ces1c/d/e-/- mice. This may contribute to the obesity-related chronic inflammation and adverse metabolic disease in this strain. While Ces1c/d/e deficiency clearly exacerbated metabolic syndrome development, long-term (18-week) high-fat diet exposure overwhelmed many, albeit not all, observed phenotypic differences.

The Combination of a Human Biomimetic Liver Microphysiology System with BIOLOGXsym, a Quantitative Systems Toxicology (QST) Modeling Platform for Macromolecules, Provides Mechanistic Understanding of Tocilizumab- and GGF2-Induced Liver Injury

Biologics address a range of unmet clinical needs, but the occurrence of biologics-induced liver injury remains a major challenge. Development of cimaglermin alfa (GGF2) was terminated due to transient elevations in serum aminotransferases and total bilirubin. Tocilizumab has been reported to induce transient aminotransferase elevations, requiring frequent monitoring. To evaluate the clinical risk of biologics-induced liver injury, a novel quantitative systems toxicology modeling platform, BIOLOGXsym™, representing relevant liver biochemistry and the mechanistic effects of biologics on liver pathophysiology, was developed in conjunction with clinically relevant data from a human biomimetic liver microphysiology system. Phenotypic and mechanistic toxicity data and metabolomics analysis from the Liver Acinus Microphysiology System showed that tocilizumab and GGF2 increased high mobility group box 1, indicating hepatic injury and stress. Tocilizumab exposure was associated with increased oxidative stress and extracellular/tissue remodeling, and GGF2 decreased bile acid secretion. BIOLOGXsym simulations, leveraging the in vivo exposure predicted by physiologically-based pharmacokinetic modeling and mechanistic toxicity data from the Liver Acinus Microphysiology System, reproduced the clinically observed liver signals of tocilizumab and GGF2, demonstrating that mechanistic toxicity data from microphysiology systems can be successfully integrated into a quantitative systems toxicology model to identify liabilities of biologics-induced liver injury and provide mechanistic insights into observed liver safety signals.

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.

Effects of Pro-Inflammatory Cytokines on Hepatic Metabolism in Primary Human Hepatocytes

Three decades of hepatocyte transplantation have confirmed such a cell-based approach as an adjunct or alternative treatment to solid organ transplantation. Donor cell survival and engraftment were indirectly measured by hepatospecific secretive or released metabolites, such as ammonia metabolism in urea cycle defects. In cases of sepsis or viral infection, ammonia levels can significantly and abruptly increase in these recipients, erroneously implying rejection. Pro-inflammatory cytokines associated with viral or bacterial infections are known to affect many liver functions, including drug-metabolizing enzymes and hepatic transport activities. We examined the influence of pro-inflammatory cytokines in primary human hepatocytes, isolated from both normal donors or patients with metabolic liver diseases. Different measures of hepatocyte functions, including ammonia metabolism and phase 1-3 metabolism, were performed. All the hepatic functions were profoundly and significantly suppressed after exposure to concentrations of from 0.1 to 10 ng/mL of different inflammatory cytokines, alone and in combination. Our data indicate that, like phase I metabolism, suppression of phase II/III and ammonia metabolism occurs in hepatocytes exposed to pro-inflammatory cytokines in the absence of cell death. Such inflammatory events do not necessarily indicate a rejection response or loss of the cell graft, and these systemic inflammatory signals should be carefully considered when the immunosuppressant regiment is reduced or relieved in a hepatocyte transplantation recipient in response to such alleged rejection.

Dietary intervention improves health metrics and life expectancy of the genetically obese Titan mouse

Suitable animal models are essential for translational research, especially in the case of complex, multifactorial conditions, such as obesity. The non-inbred mouse (Mus musculus) line Titan, also known as DU6, is one of the world’s longest selection experiments for high body mass and was previously described as a model for metabolic healthy (benign) obesity. The present study further characterizes the geno- and phenotypes of this non-inbred mouse line and tests its suitability as an interventional obesity model. In contrast to previous findings, our data suggest that Titan mice are metabolically unhealthy obese and short-lived. Line-specific patterns of genetic invariability are in accordance with observed phenotypic traits. Titan mice also show modifications in the liver transcriptome, proteome, and epigenome linked to metabolic (dys)regulations. Importantly, dietary intervention partially reversed the metabolic phenotype in Titan mice and significantly extended their life expectancy. Therefore, the Titan mouse line is a valuable resource for translational and interventional obesity research.

This study further characterizes the non-inbred Titan (also known as DU6) mouse line, which could be a useful model for obesity research.

The Role of Cytochrome P450 Enzymes in COVID-19 Pathogenesis and Therapy

Coronavirus disease 2019 (COVID-19) has become a new public health crisis threatening the world. Dysregulated immune responses are the most striking pathophysiological features of patients with severe COVID-19, which can result in multiple-organ failure and death. The cytochrome P450 (CYP) system is the most important drug metabolizing enzyme family, which plays a significant role in the metabolism of endogenous or exogenous substances. Endogenous CYPs participate in the biosynthesis or catabolism of endogenous substances, including steroids, vitamins, eicosanoids, and fatty acids, whilst xenobiotic CYPs are associated with the metabolism of environmental toxins, drugs, and carcinogens. CYP expression and activity are greatly affected by immune response. However, changes in CYP expression and/or function in COVID-19 and their impact on COVID-19 pathophysiology and the metabolism of therapeutic agents in COVID-19, remain unclear. In this analysis, we review current evidence predominantly in the following areas: firstly, the possible changes in CYP expression and/or function in COVID-19; secondly, the effects of CYPs on the metabolism of arachidonic acid, vitamins, and steroid hormones in COVID-19; and thirdly, the effects of CYPs on the metabolism of therapeutic COVID-19 drugs.

IL-6 Revisited: From Rheumatoid Arthritis to CAR T Cell Therapy and COVID-19

The diverse biological activity of interleukin-6 (IL-6) contributes to the maintenance of homeostasis. Emergent infection or tissue injury induces rapid production of IL-6 and activates host defense through augmentation of acute-phase proteins and immune responses. However, excessive IL-6 production and uncontrolled IL-6 receptor signaling are critical to pathogenesis. Over the years, therapeutic agents targeting IL-6 signaling, such as tocilizumab, a humanized anti-IL-6 receptor antibody, have shown remarkable efficacy for rheumatoid arthritis, Castleman disease, and juvenile idiopathic arthritis, and their efficacy in other diseases is continually being reported. Emerging evidence has demonstrated the benefit of tocilizumab for several types of acute inflammatory diseases, including cytokine storms induced by chimeric antigen receptor T-cell therapy and coronavirus disease 2019 (COVID-19). Here, we refocus attention on the biology of IL-6 and summarize the distinct pathological roles of IL-6 signaling in several acute and chronic inflammatory diseases. Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Toxic clozapine level as first indication of severe, acute infection

Background

Clozapine levels can be influenced by many factors, including pharmacogenomic variability, pharmacokinetic drug interactions, and infection/inflammation. The concentration-to-dose ratio (C/D), a measure of a medication's rate of metabolism and clearance, may increase during an acute infection due to decreased medication metabolism and clearance.

Case Report

A 56-year-old White man was restarted on clozapine and titrated up to 350 mg/d with therapeutic steady-state levels (C/D 1.11) on hospital day (HD) 69. At this time, he was also being treated for COPD exacerbation. For the next month, he continued to complain of cough, but vital signs and chest x-ray remained normal. Labs were unremarkable except for occasional leukocytosis that would resolve on repeat evaluation. A routine clozapine level drawn on HD 104, resulted on day 108 and showed clozapine toxicity with C/D 4.05, although the patient was asymptomatic. After receipt of labs on day 109, showing elevated WBC count, he was immediately sent to the emergency room where he was admitted for treatment of pneumonia. On return to the state hospital, the patient was continued on 100 mg clozapine and titrated to 200 mg/d based on low drug levels. He continued to do well on 200 mg/d clozapine with C/D averaging 1.13 (range, 0.75-1.52).

Discussion

Acute infection and illness can lead to significantly increased clozapine levels and toxicity, even if symptoms of toxicity are minimal or absent. This appears to be the first report of a toxic level being the first indication of severe medical illness.

Transcriptomic Analyses Reveal 2 and 4 Family Members of Cytochromes P450 (CYP) Involved in LPS Inflammatory Response in Pharynx of Ciona robusta

Cytochromes P450 (CYP) are enzymes responsible for the biotransformation of most endogenous and exogenous agents. The expression of each CYP is influenced by a unique combination of mechanisms and factors including genetic polymorphisms, induction by xenobiotics, and regulation by cytokines and hormones. In recent years, Ciona robusta, one of the closest living relatives of vertebrates, has become a model in various fields of biology, in particular for studying inflammatory response. Using an in vivo LPS exposure strategy, next-generation sequencing (NGS) and qRT-PCR combined with bioinformatics and in silico analyses, compared whole pharynx transcripts from naïve and LPS-exposed C. robusta, and we provide the first view of cytochrome genes expression and miRNA regulation in the inflammatory response induced by LPS in a hematopoietic organ. In C. robusta, cytochromes belonging to 2B,2C, 2J, 2U, 4B and 4F subfamilies were deregulated and miRNA network interactions suggest that different conserved and species-specific miRNAs are involved in post-transcriptional regulation of cytochrome genes and that there could be an interplay between specific miRNAs regulating both inflammation and cytochrome molecules in the inflammatory response in C. robusta.

Inflammation Induces Changes in the Functional Expression of P-gp, BCRP, and MRP2: An Overview of Different Models and Consequences for Drug Disposition

The ATP-binding cassette (ABC) transporters play a key role in drug pharmacokinetics. These membrane transporters expressed within physiological barriers can be a source of pharmacokinetic variability. Changes in ABC transporter expression and functionality may consequently affect the disposition of substrate drugs, resulting in different drug exposure. Inflammation, present in several acute and chronic diseases, has been identified as a source of modulation in drug transporter expression leading to variability in drug response. Its regulation may be particularly dangerous for drugs with a narrow therapeutic index. In this context, numerous in vitro and in vivo models have shown up- or downregulation in the expression and functionality of ABC transporters under inflammatory conditions. Nevertheless, the existence of contradictory data and the lack of standardization for the models used have led to a less conclusive interpretation of these data.

The Central Role of Cytochrome P450 in Xenobiotic Metabolism-A Brief Review on a Fascinating Enzyme Family

Human Cytochrome P450 (CYP) enzymes constitute a superfamily of membrane-bound hemoproteins that are responsible for the metabolism of a wide variety of clinically, physiologically, and toxicologically important compounds. These heme-thiolate monooxygenases play a pivotal role in the detoxification of xenobiotics, participating in the metabolism of many structurally diverge compounds. This short-review is intended to provide a summary on the major roles of CYPs in Phase I xenobiotic metabolism. The manuscript is focused on eight main topics that include the most relevant aspects of past and current CYP research. Initially, (I) a general overview of the main aspects of absorption, distribution, metabolism, and excretion (ADME) of xenobiotics are presented. This is followed by (II) a background overview on major achievements in the past of the CYP research field. (III) Classification and nomenclature of CYPs is briefly reviewed, followed by (IV) a summary description on CYP’s location and function in mammals. Subsequently, (V) the physiological relevance of CYP as the cornerstone of Phase I xenobiotic metabolism is highlighted, followed by (VI) reviewing both genetic determinants and (VI) nongenetic factors in CYP function and activity. The last topic of the review (VIII) is focused on the current challenges of the CYP research field.

Disease-drug and drug-drug interaction in COVID-19: Risk and assessment

COVID-19 is announced as a global pandemic in 2020. Its mortality and morbidity rate are rapidly increasing, with limited medications. The emergent outbreak of COVID-19 prompted by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) keeps spreading. In this infection, a patient's immune response plays pivotal role in the pathogenesis. This inflammatory factor was shown by its mediators that, in severe cases, reach the cytokine at peaks. Hyperinflammatory state may sparks significant imbalances in transporters and drug metabolic machinery, and subsequent alteration of drug pharmacokinetics may result in unexpected therapeutic response. The present scenario has accounted for the requirement for therapeutic opportunities to relive and overcome this pandemic. Despite the diminishing developments of COVID-19, there is no drug still approved to have significant effects with no side effect on the treatment for COVID-19 patients. Based on the evidence, many antiviral and anti-inflammatory drugs have been authorized by the Food and Drug Administration (FDA) to treat the COVID-19 patients even though not knowing the possible drug-drug interactions (DDI). Remdesivir, favipiravir, and molnupiravir are deemed the most hopeful antiviral agents by improving infected patient’s health. Dexamethasone is the first known steroid medicine that saved the lives of seriously ill patients. Some oligopeptides and proteins have also been using. The current review summarizes medication updates to treat COVID-19 patients in an inflammatory state and their interaction with drug transporters and drug-metabolizing enzymes. It gives an opinion on the potential DDI that may permit the individualization of these drugs, thereby enhancing the safety and efficacy.

Malaria-induced Alterations of Drug Kinetics and Metabolism in Rodents and Humans

BACKGROUND

Infections and inflammation lead to a downregulation of drug metabolism and kinetics in experimental animals. These changes in the expression and activities of drug-metabolizing enzymes may affect the effectiveness and safety of pharmacotherapy of infections and inflammatory conditions.

OBJECTIVE

In this review, we addressed the available evidence on the effects of malaria on drug metabolism activity and kinetics in rodents and humans.

RESULTS

An extensive literature review indicated that infection by Plasmodium spp consistently decreased the activity of hepatic Cytochrome P450s and phase-2 enzymes as well as the clearance of a variety of drugs in mice (lethal and non-lethal) and rat models of malaria. Malaria-induced CYP2A5 activity in the mouse liver was an exception. Except for paracetamol, pharmacokinetic trials in patients during acute malaria and in convalescence corroborated rodent findings. Trials showed that, in acute malaria, clearance of quinine, primaquine, caffeine, metoprolol, omeprazole, and antipyrine is slower and that AUCs are greater than in convalescent individuals.

CONCLUSION

Notwithstanding the differences between rodent models and human malaria, studies in P. falciparum and P. vivax patients confirmed rodent data showing that CYP-mediated clearance of antimalarials and other drugs is depressed during the symptomatic disease when rises in levels of acute-phase proteins and inflammatory cytokines occur. Evidence suggests that inflammatory cytokines and the interplay between malaria-activated NF-kB-signaling and cell pathways controlling phase 1/2 enzyme genes transcription mediate drug metabolism changes. The malaria-induced decrease in drug clearance may exacerbate drug-drug interactions, and the occurrence of adverse drug events, particularly when patients are treated with narrow-margin-of-safety medicines.

[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.

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.

Pharmacokinetics of omeprazole in rats with dextran sulfate sodium-induced ulcerative colitis

Omeprazole is a commonly used drug in patients with ulcerative colitis (UC). This study investigated the pharmacokinetics of omeprazole in rats with UC induced by dextran sulfate sodium (DSS). The pharmacokinetics of intravenously administered omeprazole (20 mg/kg) was investigated in normal and UC rats using LC-MS/MS. The formation of 5-OH omeprazole, a main metabolite of omeprazole, in rat liver microsomes (RLMs) from normal and UC rats was compared. The protein levels of CYP1A2, CYP2D1, and CYP3A1 in the liver were measured by Western blot. Compared with normal rats, UC rats had increased plasma concentrations of omeprazole, resulting in an increased AUC_0-240 min and decreased CL. DSS treatment decreased the formation rate of 5-OH omeprazole in RLMs but did not change the affinity of the enzymes. The V_max and CL_int of RLMs from UC rats were 62% and 48% those of RLMs from normal rats, respectively. The hepatic CYP1A2 and CYP3A1 protein levels in UC rats were 42.6 and 45.2% lower than those in normal rats, respectively; however, the protein levels of CYP2D1 in the two groups were similar. The activity and expression of some hepatic CYP450 isoforms were decreased by UC, leading to changes in the pharmacokinetics of omeprazole.

Hepatotoxicity of decabromodiphenyl ethane (DBDPE) and decabromodiphenyl ether (BDE-209) in 28-day exposed Sprague-Dawley rats

Decabromodiphenyl ether (BDE-209) and its substitute decabromodiphenyl ethane (DBDPE) are heavily used in various industrial products as flame retardant. They have been found to be persistent in the environment and have adverse health effects in humans. Although some former studies have reported toxic effects of BDE-209, the study of DBDPE's toxic effects is still in its infancy, and the effects of DBDPE on hepatotoxicity are also unclear. This study aimed to evaluate and compare the hepatotoxicity induced by BDE-209 and DBDPE using a rat model. Sprague-Dawley rats were administered DBDPE or BDE-209 (5, 50, 500 mg/kg bodyweight) intragastrically once a day for 28 days. Twenty-four hours after the end of treatment, the rats were sacrificed, and body liver weight, blood biochemical parameters, liver pathology, oxidative stress, inflammation, pregnane X receptor (PXR), constitutive androstane receptor (CAR), and changes in cytochrome P450 (CYP3A) enzymes were measured. Our results showed that both BDE-209 and DBDPE could cause liver morphological changes, induce oxidative stress, increase γ-glutamyl transferase and glucose levels in serum, and down-regulate PXR, CAR, and CYP3A expression. In addition, BDE-209 was found to increase liver weight and the ratio of liver/body weight, lead to elevated total bilirubin and indirect bilirubin levels in serum, and induce inflammation. The present study indicated that BDE-209 and DBDPE may interfere with normal metabolism in rats through oxidative stress and inflammation, which inhibit PXR and CAR to induce the expression of CYP3A enzymes, and finally produce hepatotoxic effects and cause liver damage in rats. Comparatively, our results show that the damage caused by BDE-209 was more serious than that caused by DBDPE.

Disrupted hepatic pentose phosphate pathway directly participates in and indirectly promotes CYP3A reduction: A new strategy for CYP3A-mediated drug hepatotoxicity

BACKGROUND AND PURPOSE

Hepatic CYP450s play an important role in drug-induced hepatotoxicity. They are altered in liver diseases and in many non-liver diseases, such as extra-hepatic tumours. Consequently, CYP450-mediated abnormal drug exposure increases the incidence and extent of hepatotoxicity. This risk is often underestimated because the mechanisms underlying decreases in hepatic CYP450s in extra-hepatic tumours remain unclear.

EXPERIMENTAL APPROACH

We used Balb/c nude mice with s.c. transplanted 4T1, LoVo and HepG2 tumours to model extra-hepatic tumours. Decreased levels of CYP3A were evaluated by qPCR, western blotting, and metabolic activity. LC-Q/TOF-MS and GC-MS were used in combination for analysing liver metabolomics. The contribution of the pentose phosphate pathway (PPP) to decreased CYP3A was assessed using menadione and silencing of glucose-6-phosphate dehydrogenase.

KEY RESULTS

CYP3A activity was inhibited at early stages of tumour growth when no significant inflammatory response was observed. The PPP was predominately disrupted at this non-inflammatory stage. Disruption of the PPP directly inhibited CYP3A through the chk2/p53/p65 pathway at the non-inflammatory stage, but at the later inflammatory stage, it indirectly potentiated the subsequent IL-6-mediated CYP3A decrease. Recovery of the PPP with menadione at the non-inflammatory stage, reversed the decreased CYP3A. Similar reversal was obtained with the IL-6 inhibitor, tocilizumab. Such modulation of the PPP to alleviate CYP3A-mediated drug hepatotoxicity was validated with dasatinib in vivo.

CONCLUSIONS AND IMPLICATIONS

PPP modulation at early, non-inflammatory stages might provide a novel and distinctive approach to manage drug hepatotoxicity mediated by decreased CYP3A.

Eicosanoids derived from cytochrome P450 pathway of arachidonic acid and inflammatory shock

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Septic shock, the most common form of vasodilatory shock, is a subset of sepsis in which circulatory and cellular/metabolic abnormalities are severe enough to increase mortality. Inflammatory shock constitutes the hallmark of sepsis, but also a final common pathway of any form of severe long-term tissue hypoperfusion. The pathogenesis of inflammatory shock seems to be due to circulating substances released by pathogens (e.g., bacterial endotoxins) and host immuno-inflammatory responses (e.g., changes in the production of histamine, bradykinin, serotonin, nitric oxide [NO], reactive nitrogen and oxygen species, and arachidonic acid [AA]-derived eicosanoids mainly through NO synthase, cyclooxygenase, and cytochrome P450 [CYP] pathways, and proinflammatory cytokine formation). Therefore, refractory hypotension to vasoconstrictors with end-organ hypoperfusion is a life threatening feature of inflammatory shock. This review summarizes the current knowledge regarding the role of eicosanoids derived from CYP pathway of AA in animal models of inflammatory shock syndromes with an emphasis on septic shock in addition to potential therapeutic strategies targeting specific CYP isoforms responsible for proinflammatory/anti-inflammatory mediator production.

Interleukin-6 selectively induces drug metabolism to potentiate the genotoxicity of dietary carcinogens in mammary cells

Breast cancer is the most commonly diagnosed malignancy in females, the etiology being multifactorial and includes the role of lifestyle exposure to DNA-damaging chemicals such as dietary carcinogens benzo (a) pyrene (BaP) and 2-amino-1-methyl-6-phenylimidazo [4, 5-b] pyridine (PhIP). Both compounds require cytochrome P450 (CYP)-mediated metabolic activation to DNA-damaging species, and both induce transcriptional responses through the nuclear receptors Aryl hydrocarbon receptor (AhR) and estrogen receptor α (ERα). BaP and PhIP are mammary carcinogens in rodents. Clinically, circulating IL-6 expression is linked with poor prognosis of cancer and 35% of the deaths in breast cancer are linked with inflammation. The objective of this work was to investigate the molecular toxicology and local activation of BaP and PhIP in the presence of IL-6. Our laboratory has previously reported that miR27b can regulate CYP1B1 expression in colorectal cells, here we have investigated if this mechanism is working in mammary cell models, MCF-7 and MDA-MB-231 cells. Treatment (24 h) of cells with BaP (10 nM-10 µM) and PhIP (100 nM-100 µM) significantly induced genetic damage (micronuclei formation) in a dose-dependent manner in both cell lines. This effect was potentiated in the presence of human IL-6 at concentrations reported to be expressed in clinical breast cancer. On its own, IL-6 treatment failed to induce micronuclei frequency above the control levels in these cells. Compared to BaP or PhIP treatment alone, IL-6 plus BaP or PhIP selectively induced CYP1B1 significantly in both cell lines. Additionally, miR27b expression was downregulated by IL-6 treatments and transfection with miR27b inhibitor confirmed that miR27b is a regulator of CYP1B1 in both cell lines. These data show that BaP- and PhIP-induced DNA damage in mammary cells is potentiated by the inflammatory cytokine IL-6 and that inflammation-induced CYP expression, specifically CYP1B1 via miR27b, is responsible for this effect.

The regulation of drug-metabolizing enzymes and membrane transporters by inflammation: Evidences in inflammatory diseases and age-related disorders

Drug-metabolizing enzymes (DMEs) and membrane transporters play important roles in the absorption, distribution, metabolism, and excretion processes that determine the pharmacokinetics of drugs. Inflammation has been shown to regulate the expression and function of these drug-processing proteins. Given that inflammation is a common feature of many diseases, in this review, the general mechanisms for inflammation-mediated regulation of DMEs and transporters are described. Also, evidences regarding the aberrant expression of these drug-processing proteins in several inflammatory diseases and age-related disorders are provided.

Tocilizumab in Giant Cell Arteritis

Giant cell arteritis is a granulomatous immune-mediated vasculitis of medium and large vessels. It most commonly affects white females over the age of 50 and is the most common primary vasculitis in the United States. Treatment of this disease has classically been with high-dose corticosteroids, but this therapy has been associated with severe morbidity and mortality. Tocilizumab, a humanized monoclonal antibody targeting the interleukin-6 receptor, has been used with great efficacy and safety in rheumatoid arthritis and systemic-onset juvenile idiopathic arthritis. As interleukin-6 has been shown to be a key cytokine in giant cell arteritis, the use of an inhibiting agent has been explored. In the 15 case reports/series that were reviewed, most patients were given tocilizumab due to refractory giant cell arteritis and/or intolerance to glucocorticoid therapy, and most experienced remission of symptoms. At this time, there are only 2 randomized control trials to evaluate the efficacy and safety of tocilizumab use in giant cell arteritis. The phase II trial by Villiger et al and the GiACTA trial both showed that tocilizumab greatly increased the rate of sustained remission in giant cell arteritis over the course of 1 year. The most common adverse events were similar to those seen with use in rheumatoid arthritis: infections, neutropenia, and increases in lipids and liver function test enzymes. Based on the results of numerous case studies and the 2 randomized control trials, tocilizumab is the first agent to be approved by the Food and Drug Administration for treatment of giant cell arteritis.

Effects and Mechanism of Nano-Copper Exposure on Hepatic Cytochrome P450 Enzymes in Rats

Although nano-copper is currently used extensively, the adverse effects on liver cytochrome P450 (CYP450) enzymes after oral exposure are not clear. In this study, we determined the effects and mechanisms of action of nano- and micro-copper on the expression and activity of CYP450 enzymes in rat liver. Rats were orally exposed to micro-copper (400 mg/kg), Cu ion (100 mg/kg), or nano-copper (100, 200 and 400 mg/kg) daily for seven consecutive days. Histopathological, inflammatory and oxidative stress were measured in the livers of all rats. The mRNA levels and activity of CYP450 enzymes, as well as the mRNA levels of select nuclear receptors, were determined. Exposure to nano-copper (400 mg/kg) induced significant oxidative stress and inflammation relative to the controls, indicated by increased levels of interleukin (IL)-2, IL-6, interferon (IFN)-γ, macrophage inflammatory protein (MIP-1), total antioxidant capacity (T-AOC), malondialdehyde (MDA), inducible nitric oxide synthase (iNOS) and nitric oxide (NO) after exposure. The levels of mRNA expression of pregnane X receptor (PXR), constitutive androstane receptor (CAR) and aryl hydrocarbon receptor (AHR) were significantly decreased in 400 mg/kg nano-copper treated rats. Nano-copper activated the expression of the NF-kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription (STAT)3 signaling pathways. Nano-copper decreased the mRNA expression and activity of CYP 1A2, 2C11, 2D6, 2E1 and 3A4 in a dose-dependent manner. The adverse effects of micro-copper are less severe than those of nano-copper on the CYP450 enzymes of rats after oral exposure. Ingestion of large amounts of nano-copper in animals severely affects the drug metabolism of the liver by inhibiting the expression of various CYP450 enzymes, which increases the risk of drug-drug interactions in animals.

Exercise Is Medicine, But Does It Interfere With Medicine?

Exercise frequently is prescribed therapeutically, either on its own or combined with drugs. A drug's absorption, distribution, metabolism, and excretion can be affected by the user's anatomy and physiology, which are both changed by the myriad of complex adaptations to acute and chronic exercise. This article reviews the research that suggests exercise may influence a drug's plasma concentration, and thus its efficacy and safety.

Effects of dextran sulfate sodium induced experimental colitis on cytochrome P450 activities in rat liver, kidney and intestine

Dextran sulfate sodium (DSS) induced experimental colitis presents a histologic resemblance to human ulcerative colitis (UC). Altered cytochrome P450s (CYPs) have been reported in this model and patients with UC. In this study, six CYPs activities were quantitatively determined in microsomes of liver (RLMs), kidney (RRMs) and intestine (RIMs) from rats with colitis at acute (5% DSS for 7 days, UCA) and remission (7-day DSS treatment followed by 7-day cessation, UCR) phases and compared with normal rats. Generally, CYPs activities varied with isoform, organ, and disease status. Hepatic CYP1A2, 2B1, 2C6/11, 2E1 and 3A1/2 activities were reduced by acute colitis and completely or partially restored after DSS was halted. Although DSS treatment decreased the V_max of renal CYP2C6/11 and increased that of CYP2D2, their CL_{int, in vitro} were comparable among normal, acute and remission stages. DSS treatment changed the kinetics of CYP3A1/2-mediated nifedipine metabolism in RRMs from biphasic to classical kinetics. Notably, CYP2D2 activity was elevated in liver and kidney in acute UC, while enhanced in liver and decreased in kidney in remission. In intestine, CYP3A1/2 activity was increased in UCA and further enhanced after DSS withdrawal. These findings highlight the necessity of quantifying enzyme activity for precision drug therapy.

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.

Never deem lightly the "less harmful" low-molecular-weight PAH, NPAH, and OPAH - Disturbance of the immune response at real environmental levels

The upcoming energy structure optimization and the implementation of strict emissions control will effectively alleviated the pollution of high-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. Compared to HMW PAHs, the immune response to low-molecular-weight (LMW) PAHs is recognized as "less harmful", despite the high proportions of these substances. The present study intends to investigate the effects of several of the most abundant LMW PAHs on macrophages RAW264.7 at environmentally relevant doses. The data assembled herein showed that Fluoranthene (Fluo, PAH) formed a π-π interaction with the Phe12 residue of AhR while inhibiting the transcription of CYP1A1 and CYP1B1, and ultimately induced the inflammatory cytokines in RAW264.7. The 1-Nitropyrene (1-Nitro, NPAH) formed both a π-π interaction and a hydrogen bond with AhR, stimulated CYP1A1transcription, while suppressed the cytokine levels. Additionally, the inflammation potency caused by TPAHs was highly correlated with the cytotoxic potency rather than the oxidative stress potency. When stimulated by LPS, the transcription of IL-6 was inhibited by Fluo, and 1-Nitro suppressed both IL-6 and TNFα transcription. Furthermore, only 1-Nitro gave a significant inhibition on phagocytosis. The effects of 9-Fluorenone (9-Fluo, OPAH) on macrophages remained insignificant throughout the study since the low affinity for AhR, which resulted in low cytotoxicity. Collectively, this study suggested that LMW PAHs tended to cause mild inflammation when they bind without activating AhR. During infection, AhR ligands caused immunosuppression and this potency for TPAHs may be higher in AhR activator than that in AhR inactivator.

Pharmacokinetics and Dosing of Anti-infective Drugs in Patients on Extracorporeal Membrane Oxygenation: A Review of the Current Literature

PURPOSE

Extracorporeal membrane oxygenation (ECMO) is a cardiopulmonary bypass device that is used to temporarily support the most critically ill of patients with respiratory and/or cardiac failure. Infection and its sequelae may be an indication for ECMO or infections may be acquired while on ECMO and are associated with a mortality >50%. Effective therapy requires optimal dosing. However, optimal dosing can be different in patients on ECMO because the ECMO circuit can alter drug pharmacokinetics. This review assessed the current literature for pharmacokinetic data and subsequent dosing recommendations for anti-infective drugs in patients on ECMO.

METHODS

We searched the PubMed and Embase databases (1965 to February 2016) and included case reports, case series, or studies that provided pharmacokinetic data for anti-infective drugs including antibiotics, antifungals, and antivirals being used to treat patients of all age groups on ECMO. Pharmacokinetic parameters and dosing recommendations based on these data are presented.

FINDINGS

The majority of data on this topic comes from neonatal studies of antibiotics from the 1980s and 1990s. These studies generally demonstrate a larger volume of distribution due to ECMO and therefore higher doses are needed initially. More adult data are now emerging, but with a predominance of case reports and case series without comparison with critically ill controls. The available pharmacokinetic analyses do suggest that volume of distribution and clearance are unchanged in the adult population, and therefore dosing recommendations largely remain unchanged. There is a lack of data on children older than 1 year of age. The data support the importance of therapeutic drug monitoring when available in this population of patients.

IMPLICATIONS

This review found reasonably robust dosing recommendations for some drugs and scant or no data for other important anti-infectives. In order to better determine optimal dosing for patients on ECMO, a systematic approach is needed. Approaches that combine ex vivo ECMO experiments, animal studies, specialized pharmacokinetic modeling, and human clinical trials are being developed.

Gender differences in murine pulmonary responses elicited by cellulose nanocrystals

Background

Cellulose-based materials have been used for centuries to manufacture different goods derived from forestry and agricultural sources. In the growing field of nanocellulose applications, its uniquely engineered properties are instrumental for inventive products coming to competitive markets. Due to their high aspect ratio and stiffness, it is speculated that cellulose nanocrystals (CNC) may cause similar pulmonary toxicity as carbon nanotubes and asbestos, thus posing a potential negative impact on public health and the environment.

Methods

The present study was undertaken to investigate the pulmonary outcomes induced by repeated exposure to respirable CNC. C57BL/6 female and male mice were exposed by pharyngeal aspiration to CNC (40 μg/mouse) 2 times a week for 3 weeks. Several biochemical endpoints and pathophysiological outcomes along with gene expression changes were evaluated and compared in the lungs of male and female mice.

Results

Exposure to respirable CNC caused pulmonary inflammation and damage, induced oxidative stress, elevated TGF-β and collagen levels in lung, and impaired pulmonary functions. Notably, these effects were markedly more pronounced in females compared to male mice. Moreover, sex differences in responses to pulmonary exposure to CNC were also detected at the level of global mRNA expression as well as in inflammatory cytokine/chemokine activity.

Conclusions

Overall, our results indicate that there are considerable differences in responses to respirable CNC based on gender with a higher pulmonary toxicity observed in female mice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-016-0140-x) contains supplementary material, which is available to authorized users.

Suppression of Hepatic Cyp1a2 by Total Ginsenosides in Lipopolysaccharide-Treated Mice and Primary Mouse Hepatocytes

The roots of Panax ginseng (ginseng) have been extensively used in traditional Chinese medicine. However, herb-drug interactions between ginseng and other co-administered drugs are not fully understood concerning the effect of ginseng on drug metabolism and clearance. The current study aimed to elucidate the effect of total ginsenosides, a typical ginseng extract, on the regulation of Cyp1a2, a key enzyme to regulate drug metabolism under the normal and inflammatory conditions in mice. Female C57BL/6J mice treated with vehicle and lipopolysaccharide (LPS) were intragastrically administered ginseng extract for 7 days before hepatic P450 expression was analyzed. Primary mouse hepatocytes were also employed to further explore the effects of total ginsenosides on Cyp1a2 expression. The results showed that total ginsenosides in P. ginseng extract exhibited a concentration-dependent suppression on Cyp1a2 mRNA and protein level in both mice and primary mouse hepatocytes. Notably, the inhibitory effects of total ginsenosides on Cyp1a2 mRNA and protein expression were further enhanced following LPS treatment. Therefore, future research is warranted to investigate the role of ginsenosides in the regulation of hepatic CYP450s. Moreover, consumption of ginseng as food or supplement should be monitored for patients on combinational therapy, especially those with inflammatory diseases.

Reduced acute myocardial ischemia-reperfusion injury in IL-6-deficient mice employing a closed-chest model

Objective and design

We examined the role of IL-6 in the temporal development of cardiac ischemia–reperfusion injury employing a closed-chest I/R model.

Materials/methods

Infarction, local and systemic inflammation, neutrophil infiltration, coagulation and ST elevation/resolution were compared between wild-type (WT) and IL-6-deficient (IL-6^−/−) mice after 1 h ischemia and 0, ½, 3, and 24 h reperfusion.

Results

IL-6 deficiency reduced infarct size at 3 h reperfusion (28.8 ± 4.5 % WT vs 17.6 ± 2.5 % IL-6^−/−), which reduction persisted and remained similar at 24 h reperfusion (25.1 ± 3.0 % WT vs 14.6 ± 4.4 % IL-6^−/−). Serum Amyloid A was reduced at 24 h reperfusion only (57.5 ± 4.9 WT vs 24.8 ± 5.6 ug/ml IL-6^−/− mice). Cardiac cytokines (IL-6, IL-1β and TNFα) peaked at 3 h reperfusion, but IL-1β and TNFα levels were unaffected by IL-6 deficiency. Significant neutrophil influx was only detected at 24 h reperfusion and was similar for WT and IL-6^−/−. Tissue factor peaked at 24 h reperfusion, whereas fibrin/fibrinogen peaked at 3 h reperfusion and was completely resolved at 24 h reperfusion; both coagulation factors were unaltered by IL-6 deficiency. Prolonged ST elevation was observed during ischemia that completely resolved for both genotypes at early reperfusion.

Conclusions

The data suggest that, in the absence of major surgical intervention, IL-6 contributes to the development of infarct size in the early phase of reperfusion; this contribution did not depend on neutrophil influx, IL-1β and TNFα, tissue factor and fibrin.

Regulation of drug-metabolizing enzymes by local and systemic liver injuries

INTRODUCTION

Drug metabolism and disposition are critical in maintaining the chemical and functional homeostasis of xenobiotics/drugs and endobiotics. The liver plays an essential role in drug metabolism and disposition due to its abundant expression of drug-metabolizing enzymes (DMEs) and transporters. There is growing evidence to suggest that many hepatic and systemic diseases can affect drug metabolism and disposition by regulating the expression and/or activity of DMEs and transporters in the liver.

AREAS COVERED

This review focuses on the recent progress on the regulation of DMEs by local and systemic liver injuries. Liver ischemia and reperfusion (I/R) and sepsis are used as examples of local and systemic injury, respectively. The reciprocal effect of the expression and activity of DMEs on animals' sensitivity to local and systemic liver injuries is also discussed.

EXPERT OPINION

Local and systemic liver injuries have a major effect on the expression and activity of DMEs in the liver. Understanding the disease effect on DMEs is clinically important due to the concern of disease-drug interactions. Future studies are necessary to understand the mechanism by which liver injury regulates DMEs. Human studies are also urgently needed in order to determine whether the results in animals can be replicated in human patients.

Expression of hepatic cytochrome P450 in a mouse model of ulcerative colitis changes with pathological conditions

BACKGROUND AND AIM

The expression levels of cytochrome P450 (CYP) in the liver were analyzed over time in dextran sulfate sodium (DSS)-induced ulcerative colitis mouse model, from the initial active stage to the remission stage, to investigate the relationship between the changes in pathological conditions and CYP expression levels.

METHODS

DSS solution was given to mice for 10 days, after which water without DSS was provided for 40 days. Pathological conditions and CYP expression levels were examined over time. The mechanism for variation in CYP expression was also analyzed.

RESULTS

The mRNA expression levels of CYP (CYP3A11, CYP1A2, CYP2C29, CYP2D9, and CYP2E1) decreased as pathological conditions worsened and reached their lowest levels on day 10 of DSS treatment. Pathological conditions improved following the discontinuation of DSS, and CYP expression levels normalized by day 50. Blood lipopolysaccharide levels, the hepatic expression of inflammatory cytokines, and the nuclear translocation of pregnane X receptor and constitutive androstane receptor in the liver exhibited patterns similar to the observed variations in CYP expression levels.

CONCLUSION

The capacity for metabolizing drugs that are substrates of CYP decreases during the active stage of ulcerative colitis but subsequently improves during the remission stage. This decrease in CYP expression was likely caused by the observed reduction in the levels of nuclearly localized pregnane X receptor and constitutive androstane receptor, and the increase in the production of inflammatory cytokines triggered by lipopolysaccharides.

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.

A systematic comparison of the impact of inflammatory signaling on absorption, distribution, metabolism, and excretion gene expression and activity in primary human hepatocytes and HepaRG cells

Inflammatory processes are associated with compromised metabolism and elimination of drugs in the liver, largely mediated by proinflammatory cytokines, such as interleukin-6. The Hepa-RG cell line is an established surrogate for primary human hepatocytes (PHH) in drug metabolism and toxicity studies. However, the impact of inflammatory signaling on HepaRG cells has not been well characterized. In this study, the response of primary human hepatocytes and HepaRG cells to interleukin (IL)-6 was comparatively analyzed. For this purpose, broad-spectrum gene expression profiling, including acute-phase response genes and a large panel of drug-metabolizing enzyme and transporter (DMET) genes as well as their modifiers and regulators, was conducted in combination with cytochrome P450 (P450) activity measurements. Exposure of PHH and HepaRG cells to IL-6 resulted in highly similar coordinated reduction of DMET mRNA, including major ATP-binding cassette transporters (ABCs), P450s, glutathione S-transferases (GSTs), uridine diphosphate glucuronosyltransferases (UGTs), and solute carriers (SLCs). Enzyme activities of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP3A4 were reduced upon 48-72 hours exposure to IL-6 in PHH and HepaRG. However, although these effects were not significant in PHH due to large interindividual donor variability, the impact on HepaRG was more pronounced and highly significant, thus emphasizing the advantage of HepaRG as a more reproducible model system. Exposure of HepaRG cells to interleukin-1β and tumor necrosis factor α resulted in similar effects on gene expression and enzyme activities. The present study emphasizes the role of proinflammatory cytokines in the regulation of drug metabolism and supports the use of HepaRG in lieu of PHH to minimize subject variability.

Acute and chronic effects of IL-22 on acetaminophen-induced liver injury

Acetaminophen (APAP)-induced liver injury (AILI) accounts for half of the acute liver failure cases in the United States. A better understanding of the underlying mechanisms of AILI is necessary for the development of novel antidotes. We found that pretreatment with IL-22 protected mice from APAP-mediated hepatotoxicity. The protection was dependent on STAT3, as IL-22 failed to reduce APAP hepatotoxicity in liver-specific STAT3 knockout mice. In contrast to the acute exposure to IL-22, the endogenous chronic overexpression of IL-22 in IL-22 transgenic (TG) mice or IL-22 adenovirus treatment for 6 wk resulted in a markedly increased susceptibility to AILI. Furthermore, the hepatic expression levels of cytochrome 2E1 (Cyp2E1) and Cyp1A2 were much higher in IL-22TG mice. Ablation of Cyp2E1 but not hepatic STAT3 abolished AILI and protein-adduct formation in IL-22TG mice. Finally, hepatic expression of HNF-1α, a transcriptional factor that is known to control Cyp2E1 expression, was elevated in IL-22TG mice compared with wild-type mice. Upregulation of hepatic Cyp2E1 was only observed in mice with constitutive overexpression of IL-22 but not with short-term treatment with one dose of IL-22 or multiple doses of IL-22 for 2 wk. In conclusion, short-term acute IL-22 exposure protects mice against AILI through STAT3 activation; however, chronic constitutive overexpression of IL-22 exacerbates AILI by increasing Cyp2E1 and toxic reactive APAP metabolite production. These findings may not only enhance our understanding of the effects of chronic inflammation on AILI in patients with liver disease, but are also helpful to identify novel therapeutic targets for the treatment of AILI.

Cancer, inflammation, and therapy: effects on cytochrome p450-mediated drug metabolism and implications for novel immunotherapeutic agents

Immune system activation through innate and adaptive systemic mechanisms is critical for protection from pathogens and other antigens. However, uncontrolled systemic inflammation may occur as a consequence of acute and chronic conditions and has multiple clinically relevant effects. Inflammation and cancer are fundamentally linked during development, invasion, and metastasis, yet, paradoxically, many cancers evade immune system detection. Components of cancer inflammation include chemokines, prostaglandins, and cytokines, and these have been shown to downregulate cytochrome P450 (CYP) enzyme activity. Recently, promising novel anticancer agents that upregulate immune responses have entered into clinical practice and have shown high response rates. These agents, either alone or in combinations, may cause systemic immune-related adverse events, with potential clinical implications for use of concurrent agents metabolized by CYP and other pathways. In this article, the authors focus on what is known about inflammation, cancer, and CYP-mediated drug metabolism; discuss clinical and pharmacologic data regarding novel immunomodulators; and consider their potential interactions with concurrent agents.

Turpentine oil induced inflammation decreases absorption and increases distribution of phenacetin without altering its elimination process in rats

Plasma concentrations and pharmacokinetics of phenacetin, a CYP1A2 substrate were determined in normal and experimentally induced inflamed rats by turpentine oil to know the role of inflammation on the pharmacokinetics of phenacetin and formation of its active metabolite (paracetamol) by CYP1A2 in wistar albino rats, weighing about 200-250 g that were randomly divided into two groups consisting six in each group. Rats in group I (control) received phenacetin (150 mg kg(-1), PO) where as group II received phenacetin 12 h after induction of inflammation by turpentine oil (0.4 mL, i.m). Blood samples were collected from retro orbital plexus at pre-determined time intervals prior to and at 0.166, 0.33, 0.67, 1.5, 2, 4, 8 and 12 h post-administration of phenacetin. Plasma was separated and analyzed for phenacetin and its metabolite paracetamol by HPLC assay. Based on plasma concentrations of phenacetin and its metabolite paracetamol, the pharmacokinetic parameters were determined by compartmental methods. C(max) of phenacetin was significantly (p < 0.01) decreased to 19.50 ± 2.74 μg mL(-1) in inflamed conditions compared to 38.13 ± 2.20 μg mL(-1) obtained in normal rats. Except, for significant (p < 0.001) increase in volume of distribution at steady state (V(dss)) from 2.87 ± 0.37 to 8.03 ± 1.26 L kg(-1) and increased the rate of absorption with shorter absorption half-life (t(1/2ka)) for phenacetin in inflammation. None of the pharmacokinetic parameters of either phenacetin or its metabolite paracetamol were affected. It can be concluded that turpentine oil induced inflammation has no role on the activity of CYP1A2 in rats, as the plasma concentrations and pharmacokinetic parameters of paracetamol were found unaltered.

Tocilizumab in pediatric rheumatology: the clinical experience

During the last two decades, clinical use of novel biological therapy has led to increased mechanistic understanding of complex rheumatological diseases. Conversely, basic and translational studies have led to development of new and varied therapeutic agents. These new medications which "target" specific steps in one or more immune pathways have the potential to control disease symptoms, improve quality of life and long-term prognosis, and perhaps in some, restore immunological tolerance. Use of these agents in clinical trials, combined with post-marketing surveillance, has revealed both the benefits and the undesirable side-effects of biological disease-modifying anti-rheumatic drugs (DMARDs). In this review we focus on the use of tocilizumab, a monoclonal antibody directed against the IL6 receptor (IL6R), which potently inhibits IL-6/IL6R signaling.

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.