Bypassing the compromised mitochondrial electron transport with methylene blue alleviates efavirenz/isoniazid-induced oxidant stress and mitochondria-mediated cell death in mouse hepatocytes

Abstract

Efavirenz (EFV) is an anti-retroviral drug frequently combined with isoniazid (INH) to treat HIV-1/tuberculosis co-infected patients. Both drugs have been associated with idiosyncratic liver injury (DILI), but combined anti-retroviral and anti-tubercular therapy can increase the risk for DILI as compared to either drug class alone. Because both EFV and INH have been implicated in targeting mitochondria, we aimed at exploring whether the two drugs might cause synergistic effects on the electron transport chain. We found that EFV inhibited complex I activity in isolated mouse liver mitochondria (IC50 ˜30 μM), whereas hydrazine, a major metabolite of INH generated by acylamidase-mediated hydrolytic cleavage, inhibited complex II activity (IC50 ˜30 μM). Neither INH alone (≤1000 μM) nor EFV alone (≤30 μM) was able to induce cell injury in cultured mouse hepatocytes. However, combined EFV/INH exposure resulted in increased superoxide formation and peroxynitrite stress, leading to the opening of the cyclosporine A-insensitive mode of the mitochondrial permeability transition (mPT), and necrotic cell death. The peroxynitrite scavengers, CBA or Fe-TMPyP, protected against mPT induction and alleviated cell injury. The acylamidase inhibitor bis-p-nitrophenyl phosphate prevented cell injury, suggesting that hydrazine greatly contributed to the toxicity. Methylene blue, a redox-active alternative electron acceptor/donor that bypasses complex I/II, effectively protected against EFV/INH-induced toxicity. These data demonstrate that, in murine hepatocytes, the mitochondrial electron transport chain is a critical target of combined EFV/INH exposure, and that this drug combination can lead to peroxynitrite stress-induced mPT and hepatocellular necrosis. These results are compatible with the concept that underlying silent mitochondrial dysfunction may be a key susceptibility factor contributing to idiosyncratic drug-induced liver injury.

Targeting mitochondria with methylene blue protects mice against acetaminophen‐induced liver injury

“…It has been previously demonstrated that MB can bypass complex I by accepting electrons from NADH at the flavin NADH‐binding site in complex I (I F ) and transfer them to more‐distal sites of the ETC (e.g., cytochrome c ) . However, it is not known whether MB can also bypass complex II by accepting electrons from succinate in the presence of a chemical inhibitor of complex II.…”

Model‐Based Assessment of Variability in Isoniazid Pharmacokinetics and Metabolism in Patients Co‐Infected With Tuberculosis and HIV: Implications for a Novel Dosing Strategy

“…reported a higher incidence of hepatotoxicity in an African cohort when HIV and TB were treated simultaneously compared with when HIV was treated alone . A mechanism has been proposed, advocating hydrazine as a main inducer of hepatotoxicity during concomitant therapy with efavirenz and INH . Since INH‐induced hepatotoxicity is related to hydrazine and acetyl‐hydrazine, products of INH, ACINH, and INA metabolism, changes in ACINH and INA elimination could result in different toxicity outcomes in patients treated for both HIV and TB.…”

Absence of effect of the antiretrovirals Duovir and Viraday on mitochondrial bioenergetics

“…This leaves, until today, the AR drugs as the only practical and successful treatment for HIV infection. 9,10 Previous studies on nucleoside reverse-transcriptase inhibitors (NRTIs) and nonnucleoside reverse-transcriptase inhibitors (NNRTIs) have shown that they are able to interfere with energy homeostasis and the redox balance in the mitochondria through the inhibition of mitochondrial electron transport at one or several sites of the electron transport chain. 2 While the use of combinations of AR has improved life expectancy of HIV-infected patients and reduced AIDS-related deaths, there has been an increase in morbidity and mortality linked to treatment complications, notably liver and cardiovascular diseases, renal impairment, and hepatocellular carcinoma.…”

“…Antiretroviral therapy (ART) is critical for improved quality of life and long-term survival in HIV patients but it is a lifelong commitment since it does not eradicate HIV reservoirs and is accompanied by viral rebound. 9 This toxicity was mediated through several pathways including adenosine monophosphate-activated protein kinase (AMPK) pathway and complex 1. [3][4][5][6] ART is known to disturb liver cells in various ways, some of which include metabolic abnormalities, central fat accumulation, insulin resistance, vanishing bile duct syndrome, nonalcoholic fatty liver disease, and mitochondrial toxicity.…”