Adverse effects of anti-tuberculosis drugs on HepG2 cell bioenergetics

• Published in: Human & experimental toxicology 2017-06, Vol.36 (6), p.616-625
• Main Authors: Elmorsy, E, Attalla, SM, Fikry, E, Kocon, A, Turner, R, Christie, D, Warren, A, Nwidu, LL, Carter, WG
• Format: Article
• Language: English
• Subjects: Adenine; Adenosine triphosphate; Adenosine Triphosphate - metabolism; Antitubercular Agents - toxicity; ATP; Bioenergetics; Cellular manufacture; Chronic infection; Disease transmission; Drug Interactions; Drugs; Electron microscopy; Electron transport chain; Electron Transport Complex I - metabolism; Electron Transport Complex III - metabolism; Energy Metabolism - drug effects; Exposure; Hep G2 Cells; Hepatotoxicity; Humans; Isoniazid; Isoniazid - toxicity; Lactic acid; Lactic Acid - metabolism; Membrane potential; Membrane Potential, Mitochondrial - drug effects; Mitochondria; NAD; NAD - metabolism; NADH-ubiquinone oxidoreductase; Nicotinamide; Nicotinamide adenine dinucleotide; Pyrazinamide; Pyrazinamide - toxicity; Rifampin; Rifampin - toxicity; Side effects; Studies; Toxicity; Transmission electron microscopy; Tuberculosis; Ultrastructure
• ISSN: 0960-3271; 1477-0903
• DOI: 10.1177/0960327116660751

Tuberculosis (TB) is an intractable chronic infection. Disease treatment with anti-TB drugs remains challenging due to drug-induced hepatotoxicity. The toxicity of the anti-TB drugs rifampicin (RIF), isoniazid (INH) and pyrazinamide (PZA) either alone or in combination was investigated in HepG2 cells. Assays of intracellular adenosine triphosphate (ATP) levels at 4-, 24- and 48-h post-exposure to gradient concentrations of RIF, INH and PZA were conducted. Drug-induced effects on mitochondrial membrane potential (MMP), mitochondrial complex I and complex III activity, nicotinamide adenine dinucleotide (NAD+) levels and cellular lactate production were assessed. Decreased ATP levels were dose-dependent and correlated with drug exposure duration. Approximate 24-h IC50s were 0.5 mM, 70 mM and 84 mM for RIF, INH and PZA, respectively. Twenty-four hours post-drug treatment, reductions of MMP (p = 0.0005), mitochondrial complex I and III activities (p = 0.0001 and p = 0.0003, respectively), NAD+ levels (p = 0.0057) and increased lactate production (p < 0.0001) were observed. Drug combinations used to mimic cumulative drug treatments induced a synergistic inhibition of mitochondrial complex I activity. An assessment of cellular ultrastructure using transmission electron microscopy indicated drug-induced mitophagy. Collectively, our study suggests that hepatotoxicity of commonly employed anti-TB drugs is mediated by their curtailment of mitochondrial function.