Cytotoxic Synergy Between Cytokines and NSAIDs Associated With Idiosyncratic Hepatotoxicity Is Driven by Mitogen-Activated Protein Kinases.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most frequent causes of idiosyncratic, drug-induced liver injury (IDILI). Mechanisms of IDILI are unknown, but immune responses are suspected to underlie them. In animal models of IDILI, the cytokines tumor necrosis factor-alpha (TNFα) and interferon-gamma (IFNγ) are essential to the pathogenesis. Some drugs associated with IDILI interact with cytokines to kill hepatocytes in vitro, and mitogen-activated protein kinases (MAPKs) might play a role. We tested the hypothesis that caspases and MAPKs are involved in NSAID/cytokine-induced cytotoxicity. NSAIDs that are acetic acid (AA) derivatives and associated with IDILI synergized with TNFα in causing cytotoxicity in HepG2 cells, and IFNγ enhanced this interaction. NSAIDs that are propionic acid (PA) derivatives and cause IDILI that is of less clinical concern also synergized with TNFα, but IFNγ was without effect. Caspase inhibition prevented cytotoxicity from AA and PA derivative/cytokine treatment. Treatment with a representative AA or PA derivative induced activation of the MAPKs c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38. Inhibition of either JNK or ERK reduced cytotoxicity from cytokine interactions with AA derivatives. In contrast, an ERK inhibitor potentiated cytotoxicity from cytokine interactions with PA derivatives. An AA derivative but not a PA derivative enhanced IFNγ-mediated activation of STAT-1, and this enhancement was ERK-dependent. These findings raise the possibility that some IDILI reactions result from drug/cytokine synergy involving caspases and MAPKs and suggest that, even for drugs within the same pharmacologic class, synergy with cytokines occurs by different kinase signaling mechanisms.