Article

Association Between Nonalcoholic Hepatic Steatosis and Hepatic Cytochrome P-450 3A Activity

Division of Clinical Pharmacology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association (Impact Factor: 7.9). 04/2007; 5(3):388-93. DOI: 10.1016/j.cgh.2006.12.021
Source: PubMed

ABSTRACT

Comorbidities associated with nonalcoholic fatty liver often require therapy with medications (eg, statins) metabolized by cytochrome P-450 3A (CYP3A). There is significant interindividual variability in CYP3A expression. However, human studies that systematically examined the relationship between hepatic steatosis and hepatic CYP3A activity are lacking.
The relationship of hepatic CYP3A activity with several variables including hepatic steatosis, CYP3A4 protein content, CYP3A4 mRNA expression, CYP3A5 genotype, and its mRNA expression was investigated in human liver samples (n = 49). CYP3A activity was quantified from liver microsomes by using testosterone as a probe, and hepatic steatosis was defined to be present if >5% of hepatocytes had large globules of intracellular fat displacing the nucleus.
The mean +/- standard error hepatic CYP3A activity of the study group was 3156 +/- 2794 pmol x min(-1) x mg(-1) of protein, and it was not associated with age, gender, medicinal use, CYP3A5 or pregnane xenobiotic receptor mRNA expression, or CYP3A5 genotype. Twenty-four liver samples with steatosis had significantly lower hepatic CYP3A activity than 25 liver samples without steatosis (1978 +/- 299 vs 4287 +/- 659 pmol x min(-1) x mg(-1) of protein; P = .003). This difference persisted even after controlling for relevant covariates in the multivariate analysis (P = .04). However, CYP3A4 protein content was not different between the 2 groups (6 +/- 1.3 vs 8.5 +/- 2.2 pmol/mg protein; P = .3). There was a significant negative relationship between severity of steatosis and hepatic CYP3A activity (P = .01).
Hepatic steatosis is associated with decreased hepatic CYP3A activity in humans via post-translational mechanism. Further studies are needed to confirm our findings.

0 Followers
 · 
18 Reads
    • "Notably, obesity and NAFLD in rodents and humans are associated with different alterations in the activity of hepatic enzymes involved in drug metabolism including cytochromes P450 (CYPs), UDP-glucuronosyltransferases and transporters (Brill et al., 2012; Canet et al., 2015). More specifically, these dysmetabolic disorders are associated with higher CYP2E1 activity, lower CYP3A4 activity and increased capacity of glucuronide conjugation for different drugs such as APAP and lorazepam (Aubert et al., 2011; Brill et al., 2012; Chalasani et al., 2003; Emery et al., 2003; Kolwankar et al., 2007; Woolsey et al., 2015). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Obesity and nonalcoholic fatty liver disease (NAFLD) can increase susceptibility to hepatotoxicity induced by some xenobiotics including drugs, but the involved mechanisms are poorly understood. For acetaminophen (APAP), a role of hepatic cytochrome P450 2E1 (CYP2E1) is suspected since the activity of this enzyme is consistently enhanced during NAFLD. The first aim of our study was to set up a cellular model of NAFLD characterized not only by triglyceride accumulation but also by higher CYP2E1 activity. To this end, human HepaRG cells were incubated for one week with stearic acid or oleic acid, in the presence of different concentrations of insulin. Although cellular triglycerides and the expression of lipid-responsive genes were similar with both fatty acids, CYP2E1 activity was significantly increased only by stearic acid. CYP2E1 activity was reduced by insulin and this effect was reproduced in cultured primary human hepatocytes. Next, APAP cytotoxicity was assessed in HepaRG cells with or without lipid accretion and CYP2E1 induction. Experiments with a large range of APAP concentrations showed that the loss of ATP and glutathione was almost always greater in the presence of stearic acid. In cells pretreated with the CYP2E1 inhibitor chlormethiazole, recovery of ATP was significantly higher in the presence of stearate with low (2.5 mM) or high (20 mM) concentrations of APAP. Levels of APAP-glucuronide were significantly enhanced by insulin. Hence, HepaRG cells can be used as a valuable model of NAFLD to unveil important metabolic and hormonal factors which can increase susceptibility to drug-induced hepatotoxicity.
    No preview · Article · Dec 2015 · Toxicology and Applied Pharmacology
  • Source
    • "In fact, it is known that the expression of CYPs is altered in the liver of humans and animal models with diabetes mellitus, obesity and/or hepatic steatosis . With regard to humans, decreased CYP3A activity is associated with hepatic steatosis (Kolwankar et al., 2007). Moreover, CYP3A activity and CYP3A4 mRNA level are reduced and CYP2E1 activity is increased in the liver of subjects with diabetes (Dostalek et al., 2011). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Pathophysiological and nutritional conditions often affect the expression of drug-metabolizing enzymes. SHR/NDmcr-cp (cp/cp) rats (SHR/NDcp) are highly suitable as a metabolic syndrome (MS) model. Nevertheless, little is known about the expression profile of cytochrome P450 (CYP) in the liver of SHR/NDcp. We thus attempted to clarify the expression profile of CYP genes and the effect of fish oil (FO) on this profile in the liver of SHR/NDcp. Lower levels of CYP3A2 mRNA and CYP3A activity (testosterone 6β-hydroxylation) were distinctive features in SHR/NDcp compared with their controls (Wistar Kyoto rats (WKY), spontaneously hypertensive rats (SHR), stroke-prone SHR and lean littermates of SHR/NDcp). Differently from CYP3A2, the expression of other CYP isoforms was largely unchanged in SHR/NDcp. The changes in CYP profile observed in SHR/NDcp are similar to those of patients with diabetes and simple hepatic steatosis. Feeding on FO at a high dose (18.8% in the diet) up-regulated CYP3A2 gene expression and CYP3A activity in the liver; the extent of these increases was greater in SHR/NDcp than in WKY and lean littermates of SHR/NDcp. This effect was not observed with FO at a normal dose (5% in the diet). These results indicate that, in the context of the CYP profile, SHR/NDcp is an animal model that is suitable for studying MS and imply that FO intake is critical in determining the efficacy or adverse effects of drugs in patients with MS.
    Preview · Article · Jan 2015
  • Source
    • "As with most drug–drug interaction studies, healthy volunteers, rather than patients, were enrolled in this study. MVC is primarily metabolized by the liver and therefore exposures have the potential to be higher in HIV/HCV coinfected patients with hepatic impairment, as hepatic damage and disease may affect CYP enzyme activity.27–32 A study conducted in HIV-negative subjects with hepatic impairment demonstrated that MVC exposures in subjects with mild (Child-Pugh class A) and moderate (Child-Pugh class B) hepatic impairment had a geometric mean 25% (mild) and 46% (moderate) greater AUClast and a 11% (mild) and 32% (moderate) greater Cmax relative to subjects with normal hepatic function33 after a single dose of MVC 300 mg. "
    [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the effects of boceprevir (BOC) and telaprevir (TVR) on the pharmacokinetics (PK) of maraviroc (MVC) in healthy volunteers. In this open-label, fixed-sequence study, 14 volunteers received MVC 150 mg twice-daily (BID) alone for 5 days (Period 1), followed by MVC+BOC 800 mg three-times-daily (TID) and MVC+TVR 750 mg TID, each for 10 days in Periods 2 and 3, respectively, with a ≥10-day wash-out. PK was analyzed on Day 5 of Period 1 and Day 10 of Periods 2 and 3. Safety was also assessed. Ratios of the adjusted geometric means (90% confidence intervals) for MVC area under the curve from pre-dose to 12 hours, maximum plasma concentration, and plasma concentration at 12 hours were 3.02 (2.53-3.59), 3.33 (2.54-4.36), and 2.78 (2.40-3.23), respectively, for MVC+BOC versus MVC alone, and 9.49 (7.94-11.34), 7.81 (5.92-10.32), and 10.17 (8.73-11.85), respectively, for MVC+TVR versus MVC alone. PK profiles for MVC+BOC or TVR were consistent with historic values for BOC and TVR monotherapy. Adverse event incidence was higher with MVC+BOC and MVC+TVR versus MVC alone. Dysgeusia (50%) and pruritus (29%) occurred most commonly with MVC+BOC, and fatigue (46%) and headache (31%) with MVC+TVR. There were no serious adverse events. MVC exposures were significantly increased with BOC or TVR, therefore MVC should be dosed at 150 mg BID when co-administered with these newly approved hepatitis C protease inhibitors. No dose adjustment for BOC or TVR is warranted with MVC. MVC+BOC or TVR was generally well tolerated with no unexpected safety findings.
    Full-text · Article · Dec 2013 · JAIDS Journal of Acquired Immune Deficiency Syndromes
Show more