Isoniazid-induced cell death is precipitated by underlying mitochondrial complex I dysfunction in mouse hepatocytes.
Isoniazid (INH) is an antituberculosis drug that has been associated with idiosyncratic liver injury in susceptible patients. The underlying mechanisms are still unclear, but there is growing evidence that INH and/or its major metabolite, hydrazine, may interfere with mitochondrial function. However, hepatic mitochondria have a large reserve capacity, and minor disruption of energy homeostasis does not necessarily induce cell death. We explored whether pharmacologic or genetic impairment of mitochondrial complex I may amplify mitochondrial dysfunction and precipitate INH-induced hepatocellular injury. We found that INH (≤ 3000 μM) did not induce cell injury in cultured mouse hepatocytes, although it decreased hepatocellular respiration and ATP levels in a concentration-dependent fashion. However, coexposure of hepatocytes to INH and nontoxic concentrations of the complex I inhibitors rotenone (3 μM) or piericidin A (30 nM) resulted in massive ATP depletion and cell death. Although both rotenone and piericidin A increased MitoSox-reactive fluorescence, Mito-TEMPO or N-acetylcysteine did not attenuate the extent of cytotoxicity. However, preincubation of cells with the acylamidase inhibitor bis-p-nitrophenol phosphate provided protection from hepatocyte injury induced by rotenone/INH (but not rotenone/hydrazine), suggesting that hydrazine was the cell-damaging species. Indeed, we found that hydrazine directly inhibited the activity of solubilized complex II. Hepatocytes isolated from mutant Ndufs4(+/-) mice, although featuring moderately lower protein expression levels of this complex I subunit in liver mitochondria, exhibited unchanged hepatic complex I activity and were therefore not sensitized to INH. These data indicate that underlying inhibition of complex I, which alone is not acutely toxic, can trigger INH-induced hepatocellular injury.
['Lee|Kang Kwang|KK|', 'Fujimoto|Kazunori|K|', 'Zhang|Carmen|C|', 'Schwall|Christine T|CT|', 'Alder|Nathan N|NN|', 'Pinkert|Carl A|CA|', 'Krueger|Winfried|W|', 'Rasmussen|Theodore|T|', 'Boelsterli|Urs A|UA|']
D000818:Animals D000995:Antitubercular Agents D015153:Blotting, Western D019069:Cell Respiration D056486:Chemical and Drug Induced Liver Injury D042967:Electron Transport Complex I D022781:Hepatocytes D006834:Hydrazines D007538:Isoniazid D051379:Mice D008810:Mice, Inbred C57BL D018345:Mice, Knockout D008928:Mitochondria
Complex I Isoniazid INH Hydrazine Mitochondria Rotenone Piericidin A Complex II ALT AST Alanine aminotransferase Aspartate aminotransferase BNPP Bis-p-nitrophenyl phosphate DILI Drug-induced liver injury ETC Electron transport chain HzN Isoniazid (isonicotinic acid hydrazide) LDH Lactate dehydrogenase Ndufs4 OCR OXPHOS Oxidative phosphorylation Oxygen consumption rate PA ROT TCA Tricarboxylic acid