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. Author manuscript; available in PMC: 2011 Jun 6.
Published in final edited form as: Toxicol Appl Pharmacol. 2009 Apr 9;237(3):317–330. doi: 10.1016/j.taap.2009.04.002

Figure 4.

Figure 4

Large-scale drug-cytokine mix hepatotoxicity study in primary human hepatocytes demonstrates the utility of cytokine co-treatment approach for identifying idiosyncratic hepatotoxic drugs. Primary human hepatocytes were cultured, treated, and assayed for LDH release (at 24 hours post-treatment) as described in Methods. Ninety drugs (see Table S3) were each dosed at seven non-zero concentrations (2.5× serial dilutions from a high concentration of 150 μM) in the presence or absence of a cytokine mix containing TNF, IL-1α, IL-6, and LPS. The differential between + and - cytokine mix co-treatment for each drug dose was calculated and is plotted in the heatmaps (see Figure S17 for raw data and additional details). The heatmaps are split into hepatotoxic (DILI classes P1, O1, and P2; left) and not or minimally hepatotoxic (DILI classes O2, N3, N2, and N1; right) drug groups, with these DILI classes sorted in order of decreasing hepatotoxicity (see Tables 1 and S1 for additional details). Note that DILI class P2 is substantially comprised of drugs with idiosyncratic hepatotoxicities in humans. Within each DILI class, drugs are sorted in order of 100*Cmax value (a physiologically relevant dosing limit). Drug 100*Cmax values are plotted in an overlayed line plot, with values exceeding 150 μM not shown. Individual drug doses that exhibited supra-additive drug-cytokine mix synergy (see Methods and Table 1) at concentrations less than their drug’s 100*Cmax limit are highlighted with gray boxes. Drugs with one or more dose exhibiting drug-cytokine mix supra-additive toxicity synergy at less than their 100*Cmax concentration are listed in red font. A representative DILI P2 drug (chlorpromazine) displaying drug-cytokine mix synergy at dosing concentrations less than 100*Cmax is shown in the expanded plot at the bottom right (data presented mean ± SEM of two biological samples). TPCA-1, a small molecule IKK inhibitor (IKKi), was used (at ten-fold lower concentrations than are noted by the axis labels for the other drugs) as a positive control for drug-cytokine mix synergy, but is not labeled in red as its Cmax is unknown.