CYP3A Activity and Expression in Nonalcoholic Fatty Liver Disease

Abstract

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of liver disease in the Western world, given its association with obesity, type 2 diabetes, and dyslipidemia. Medications are widely used in NAFLD to manage comorbid conditions, and there is significant interest in developing new drug therapies to treat the disease. Despite this, little is known about the effects of NAFLD on drug metabolism. We examined the activity and expression of the major drug-metabolizing enzyme subfamily, CYP3A, in subjects with NAFLD as well as in mouse and cellular models. CYP3A activity was determined in healthy volunteers and subjects with biopsy-proven NAFLD by oral midazolam phenotyping and measurement of plasma 4b-hydroxycholesterol, an endogenous metabolic biomarker. CYP3A4 transcriptional activity, metabolic activity, and expression were also assessed in a mouse and cellular model of NAFLD. Subjects with nonalcoholic steatohepatitis (NASH) had 2.4-fold higher plasma midazolam levels compared with controls. Plasma 4b-hydroxycholesterol was 51% and 37% lower than controls in subjects with simple steatosis and NASH, respectively. Fibrosis was associated with 57% lower plasma 4b-hydroxycholesterol levels than controls. Furthermore, hepatic CYP3A4 mRNA expression in NASH was 69% lower than control livers. CYP3A4 gene luciferase activity in the livers of NAFLD mice was 38% lower than that of controls. Lipidloaded Huh7 human hepatoma cells had a 38% reduction in CYP3A4 activity and 80% lower CYP3A4 mRNA expression compared with the control. CYP3A activity is reduced in human NAFLD in addition to mouse and in vitro cell models of the disease.

A Fibroblast Growth Factor 21–Pregnane X Receptor Pathway Downregulates Hepatic CYP3A4 in Nonalcoholic Fatty Liver Disease

“…Many medications used by patients with NAFLD are eliminated from the body by the intestinal and hepatic enzyme CYP3A4 (Guengerich, 1999). We reported that in vivo CYP3A activity in subjects with biopsy-proven NAFLD was reduced in both simple steatosis and NASH, and that CYP3A4 mRNA levels were lower in NASH liver biopsies than in normal liver (Woolsey et al, 2015). Furthermore, we found similar reductions in CYP3A4 expression in mouse and cultured human hepatoma models of the disease (Woolsey et al, 2015).…”

“…We reported that in vivo CYP3A activity in subjects with biopsy-proven NAFLD was reduced in both simple steatosis and NASH, and that CYP3A4 mRNA levels were lower in NASH liver biopsies than in normal liver (Woolsey et al, 2015). Furthermore, we found similar reductions in CYP3A4 expression in mouse and cultured human hepatoma models of the disease (Woolsey et al, 2015). However, the underlying molecular mechanisms involved had yet to be determined.…”

“…Liver biopsy samples and fasting plasma were collected from patients with biopsy-proven NAFLD as reported by Beaton et al (2013). NAFLD disease staging into simple steatosis and NASH was defined using a histologic NAFLD activity score as described previously (Woolsey et al, 2015). Normal human liver samples were obtained through the Liver Tissue Cell Distribution System (Minneapolis, MN; funded by National Institutes of Health Contract #N01-DK-7-0004/HHSN267200700004C).…”

“…Female, 5-week-old C57BL/6 mice (Jackson Laboratory, Bar Harbor, MA) were fed a normal diet (ND) (2018 Teklad Global 18% protein rodent diet; Harlan Laboratories, Madison, WI) or a high-fat diet (HFD) (TD.88137 adjusted calories diet 42% from fat; Harlan Laboratories) for 4 weeks to induce simple steatosis (Woolsey et al, 2015). Subsequently, PXR-GFP expression plasmid was transfected into the livers of mice by hydrodynamic, tail vein delivery (25 mg of DNA in 2 ml of saline administered over 10 seconds).…”

In the overnight dexamethasone suppression test, 1.0 mg loading is superior to 0.5 mg loading for diagnosing subclinical adrenal Cushing’s syndrome based on plasma dexamethasone levels determined using liquid chromatography-tandem mass spectrometry

“…Recently, Woolsey et al [29] showed that CYP3A4 activity was significantly reduced in human NAFLD as well as in mouse and cell culture models of NAFLD. Thus, mild liver dysfunction resulting from NAFLD may be present in some SCS patients and may delay DEX metabolism via reduced CYP3A4 function [30].…”