Rifampicin exacerbates isoniazid‐induced toxicity in human but not in rat hepatocytes in tissue‐like cultures

Abstract

Background and purpose: Rifampicin has been extensively reported to exacerbate the hepatotoxicity of isoniazid in patients with tuberculosis. However, this was controversially claimed by previous reports using rat models. This study evaluated the effect of rifampicin on isoniazid-induced hepatocyte toxicity by using human and rat hepatocytes in tissue-like culture. Experimental approach: Hepatocytes in tissue-like gel entrapment were used to examine isoniazid toxicity, as shown by cell viability, intracellular glutathione content and albumin secretion. For demonstration of the differential effects of rifampicin on human and rat hepatocytes, induction by rifampicin of cytochrome P450 (CYP) 2E1, a major enzyme associated with isoniazid hepatotoxicity, was detected by 4-nitrocatechol formation and RT-PCR analysis. Key results: Rifampicin (12 mM) enhanced isoniazid-induced toxicity in human hepatocytes but not in rat hepatocytes. Enhanced CYP 2E1 enzymic activity and mRNA expression were similarly detected in human hepatocytes but not in rat hepatocytes. Both rat and human hepatocytes in gel entrapment were more sensitive to isoniazid treatment compared with the corresponding hepatocytes in a monolayer culture. Conclusions and implications:The difference in induction of CYP 2E1 by rifampicin between rat and human hepatocytes accounted for the difference in exacerbation of isoniazid hepatocyte toxicity by rifampicin, with more significant toxicity in gel entrapment than in monolayer cultures. Thus, human hepatocytes in tissue-like cultures (gel entrapment) could be an effective model for hepatotoxicity research in vitro, closer to the in vivo situation.

Role of Reactive Metabolites in Drug-Induced Hepatotoxicity

“…Precisely how such a reactive intermediate induces hepatocyte damage remains to be elucidated, as do the reasons for the increased incidence of hepatotoxicity when combination therapy is used. However, it has been found that rifampicin exacerbates INH-induced toxicity in human though not in rat hepatocytes (Shen et al 2008). In another study, GST-T1 homozygous null polymorphism was found to be a risk factor for antituberculosis drug-induced hepatotoxicity in humans (Leiro et al 2008).…”

Protective Effects of Kaempferol on Isoniazid- and Rifampicin-Induced Hepatotoxicity

“…A few studies have shown that hepatic CYP2E1 activity highly correlates with INH-induced hepatotoxicity (15,17). Previous studies have described that the synergistic effects of RIF contribute to INH-induced hepatotoxicity, probably through the induction of CYP2E1, amidase, or other enzymes (17,(24)(25)(26)(27).…”

Effects of the antimycobacterial compound 2-phenoxy-1-phenylethanone on rat hepatocytes and formation of metabolites

“…By contrast, they found that in gel entrapment cultures, isoniazid was toxic to both rat and human hepatocytes, especially the latter. This previous study by Shen et al (2008) demonstrates that primary human hepatocytes in gel entrapment culture would be a more effective model for the prediction of drug hepatotoxicity, as well as drug-drug interactions, by establishing a good correlation between in vitro and in vivo test systems. Comparative studies using hepatic models are the most useful for demonstrating species differences in the metabolism of a given drug candidate (Lewis et al, 1998;Lin, 1998;Bun et al, 1999), and are of great value in the judicious and justifiable selection of animals for subsequent pharmacokinetic and toxicological studies.…”

“…However, there is still the hypothesis that this could be due to the rapid loss of liver-specific functions of the rat hepatocyte monolayers, especially of CYP450 activity. To resolve this question, new studies can be proposed, using primary human hepatocytes in tissuelike gel entrapment culture or rat hepatocytes entrapped in collagen gel as well as cytocompatible hollow fibers, which maintain liver-specific functions at higher levels and for a long time (Shen et al, 2008). Shen et al (2008) showed that rat and human hepatocytes in monolayer cultures treated with the antituberculosis drug isoniazid did not show any decrease in cell viability or decrease in GSH content.…”

“…To resolve this question, new studies can be proposed, using primary human hepatocytes in tissuelike gel entrapment culture or rat hepatocytes entrapped in collagen gel as well as cytocompatible hollow fibers, which maintain liver-specific functions at higher levels and for a long time (Shen et al, 2008). Shen et al (2008) showed that rat and human hepatocytes in monolayer cultures treated with the antituberculosis drug isoniazid did not show any decrease in cell viability or decrease in GSH content. By contrast, they found that in gel entrapment cultures, isoniazid was toxic to both rat and human hepatocytes, especially the latter.…”