Gene-Specific Effects of Inflammatory Cytokines on Cytochrome P450 2C, 2B6 and 3A4 mRNA Levels in Human Hepatocytes

Abstract

ABSTRACT:Cytochromes P450 (P450s) are down-regulated in hepatocytes in response to inflammation and infection. This effect has been extensively studied in animal models, but significantly less is known about responses in humans and even less about responses in the absence of inducing agents. This article focuses on the effects of bacterial lipopolysaccaride (LPS), interleukin-6 (IL-6), tumor necrosis factor-␣ (TNF), interferon ␥ (IFN), transforming growth factor-␤ (TGF) and interleukin-1␤ (IL-1) on expression of CYP2B6 and the CYP2C mRNAs in human hepatocytes. These effects were compared with responses of the better studied and more abundant CYP3A4. CYP3A4 and CYP2C8 were down-regulated by all cytokine treatments. CYP2C18, which is expressed at very low levels in liver, was unaffected by cytokine treatments. The other CYP2Cs and CYP2B6 showed cytokine-specific effects. CYP2C9 and CYP2C19 showed almost identical response patterns, being downregulated by IL-6 and TGF but not significantly affected by LPS, TNF, IFN, or IL-1. CYP2B6 mRNA responded only to IL-6 and IFN. IL-6 down-regulated the mRNAs of all P450s studied. Western blot analysis of P450 protein expression supported the mRNA data to a large extent, although some inconsistencies were observed. Our results show that human CYP2C8, 2C9, 2C18, 2C19, 2B6, and 3A4 responses to inflammation are independently regulated and indicate that this fine control may have a critical effect on human drug responses in disease states.The liver responds to inflammation and infection by increasing levels of acute-phase proteins and concurrently down-regulates liverspecific proteins involved in drug metabolism (Morgan, 1997;Renton, 2004;Aitken et al., 2006). Cytochromes P450 (P450s) are the major drug-metabolizing enzymes in the liver and are significantly down-regulated by infection and inflammatory stimuli (Morgan, 1997;Aitken et al., 2006). The rapid down-regulation of P450 mRNAs (Morgan, 1997) has led to a focus on transcription as the primary mechanism of these effects, and this view is supported by the size and speed of transcriptional down-regulation as demonstrated in rats in vivo (Cheng et al., 2003). In humans, this down-regulation is associated with decreased drug clearance (Kraemer et al., 1982;Rivory et al., 2002;Carcillo et al., 2003;Renton, 2004) and can result in increased incidence of drug toxicity (Kraemer et al., 1982).Three lines of evidence support a major role of inflammatory cytokines as the mediators of P450 regulation in the liver during inflammation. First, cytokines can down-regulate P450 expression in cultures of rodent and human hepatocytes (Abdel-Razzak et al., 1993;Morgan, 1997;Sunman et al., 2004;Aitken et al., 2006). Second, mice with null mutations in cytokine or cytokine receptor genes display diminished P450 down-regulation in response to some inflammatory stimuli (Siewert et al., 2000;Ashino et al., 2004). Third, P450-dependent drug clearance has been correlated inversely with plasma interleukin-6 (IL-6) in patients with tumors (Rivory et al...

Expression analysis of apolipoprotein E and its associated genes in gastric cancer

“…ANKH is a transmembrane protein that transports intracellular pyrophosphate to the extracellular milieu (33) and has been demonstrated to be overexpressed in bladder cancer (34) and small cell lung cancer cell lines (35). CYP450 has been shown to be downregulated in hepatocytes in response to inflammation and infection (36). Local chronic inflammation is hypothesized to contribute to tumorigenesis, particularly in gastric cancer that is associated with H. pylori infection (37).…”

ICH E14 Q&A(R2) document: commentary on the further updated recommendations on thorough QT studies

“…IL-6 has also been reported to down-regulate the mRNAs of all P450s studied. In the study reported by Aitken & Morgan [11], IL-1 downregulated CYP2C8 and CYP3A4 mRNA expression by 75 and 95%, respectively, but had no effect on CYP2C9 or CYP2C19. In contrast, IL-6 caused a decrease in CYP2B6, CYP2C8, CYP2C9, CYP2C19 and CYP3A4 mRNA expressions.…”

Effect of Lipopolysaccharide on the Xenobiotic-Induced Expression and Activity of Hepatic Cytochrome P450 in Mice

“…[4][5][6][7] Morgan and colleagues reported that the mRNA levels and enzymatic activities of CYPs are downregulated in mice treated with lipopolysaccharide (LPS), 8,9) a toxic component of Gram-negative bacterial cell walls. LPS activates lymphocytes, macrophages, and neutrophils, and it initiates the synthesis of pro-inflammatory cytokines, including tumor necrosis factor (TNF)α, interleukin (IL)-1β, and IL-6.…”