Evaluation of Human Hepatocytes Under Prolonged Culture in a Novel Medium for the Maintenance of Hepatic Differentiation: Results with the Model Pro-inflammatory Cytokine Interleukin 6

Abstract

A major challenge for the evaluation of cytokine-induced down regulation of CYP gene expression in primary cultured hepatocytes is the spontaneous decrease in expression of the genes with culture duration. Based on our recent discovery that hepatocytes cultured for 7 days in a novel medium, Li's Differentiation Maintenance Medium (LDMM), would retain gene expression for markers of differentiation and most CYP isoforms at levels similar to those of the first day of culture, we examined the effects of the prototypical pro-inflammatory cytokine IL-6 in the "LDMM-stabilized (LS)" human hepatocyte model. The LS-human hepatocyte cultures were found to be responsive to IL-6 induction of the inflammatory gene marker, C-reactive protein (CRP), suggesting the expression of IL-6 receptors and the subsequent signaling pathways. Results from two independent laboratories with human hepatocytes from three donors demonstrated dose-dependent down regulation of the gene expression of several CYPs, i.e. 1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4. The results suggest that the LS-human hepatocytes may represent a physiologically relevant experimental model for mechanistic investigation of the down-regulatory effects of inflammatory cytokines.

Potential Effects of COVID-19 on Cytochrome P450-Mediated Drug Metabolism and Disposition in Infected Patients

“…Following treatment with 1 ng/ml IL-6 for 24 h, CYP3A4 levels were decreased by 47% of the normal levels [40]. Compared to CYP2B6 and CYP3A4, the suppression of CYP2C9 expression is more resilient as it required 5 ng/ml IL-6 to lower the expression [40] by 65% [40]. The average EC 50 values for IL-6-driven downregulation of CYP3A4, CYP2B6, and CYP2C9 are 1.2, 1.9, and 3.6 ng/ml, respectively [40].…”

“…A study on human hepatocytes demonstrated that IL-6-mediated downregulation of CYP enzymes is a concentration-dependent phenomenon. Following treatment with 1 ng/ml IL-6 for 24 h, CYP3A4 levels were decreased by 47% of the normal levels [40]. Compared to CYP2B6 and CYP3A4, the suppression of CYP2C9 expression is more resilient as it required 5 ng/ml IL-6 to lower the expression [40] by 65% [40].…”

“…Compared to CYP2B6 and CYP3A4, the suppression of CYP2C9 expression is more resilient as it required 5 ng/ml IL-6 to lower the expression [40] by 65% [40]. The average EC 50 values for IL-6-driven downregulation of CYP3A4, CYP2B6, and CYP2C9 are 1.2, 1.9, and 3.6 ng/ml, respectively [40]. Interindividual variability was observed in the extent of CYP downregulation by IL-6 exposure [41].…”

“…Since IL-6 downregulates the major drug-metabolizing CYP enzymes (e.g., CYP2B6, CYP2C9, and CYP3A4), administration of agents for comorbidities could be detrimental to COVID-19 patients. CYP3A4 suppression is extremely sensitive to IL-6 elevation and gets downregulated even with a minor increase in IL-6 as quickly as within 24 h [40]. Similarly, CYP2C9 is also downregulated by IL-6 at higher concentrations.…”

Moderate correlation between systemic IL‐6 responses and CRP with trough concentrations of voriconazole

“…Recently, a significant correlation between CRP and VCZ trough concentrations was reported . As in vitro studies have demonstrated that IL‐6 and other upstream proinflammatory cytokines downregulate CYP2C19 and CYP3A4 gene expression , downregulation of these CYP enzymes by elevated concentrations of IL‐6 might cause an increase in VCZ trough concentrations.…”