Correlations between 4β-hydroxycholesterol and hepatic and intestinal CYP3A4: protein expression, microsomal ex vivo activity, and in vivo activity in patients with a wide body weight range

Abstract

Purpose Variability in cytochrome P450 3A4 (CYP3A4) metabolism is mainly caused by non-genetic factors, hence providing a need for accurate phenotype biomarkers. Although 4β-hydroxycholesterol (4βOHC) is a promising endogenous CYP3A4 biomarker, additional investigations are required to evaluate its ability to predict CYP3A4 activity. This study investigated the correlations between 4βOHC concentrations and hepatic and intestinal CYP3A4 protein expression and ex vivo microsomal activity in paired liver and jejunum samples, as well as in vivo CYP3A4 phenotyping (midazolam) in patients with a wide body weight range.

Methods The patients (n=96; 78 with obesity and 18 normal or overweight individuals) were included from the COCKTAIL study (NCT02386917). Plasma samples for analysis of 4βOHC and midazolam concentrations, and liver (n=56) and jejunal (n=38) biopsies were obtained. The biopsies for determination of CYP3A4 protein concentration and microsomal activity were obtained during gastric bypass or cholecystectomy. In vivo CYP3A4 phenotyping was performed using semi-simultaneous oral (1.5 mg) and intravenous (1.0 mg) midazolam.

Results 4βOHC concentrations were positively correlated with hepatic microsomal CYP3A4 activity (ρ=0.53, p<0.001), and hepatic CYP3A4 concentrations (ρ=0.30, p=0.027), but not with intestinal CYP3A4 concentrations (ρ=0.18, p=0.28) or intestinal microsomal CYP3A4 activity (ρ=0.15, p=0.53). 4βOHC concentrations correlated weakly with midazolam absolute bioavailability (ρ= −0.23, p=0.027) and apparent oral clearance (ρ=0.28, p=0.008), but not with systemic clear ance (ρ= −0.03, p=0.81).

Conclusion These fndings suggest that 4βOHC concentrations refect hepatic, but not intestinal, CYP3A4 activity. Further studies should investigate the potential value of 4βOHC as an endogenous biomarker for individual dose requirements of intravenously administered CYP3A4 substrate drugs.