The larger necrotic lesions were characterized by massive

death of hepatocytes in the liver. The scoring was confirmed by an independent Selleckchem Ceritinib “blinded” observer. Detailed Materials and Methods can be found in the Supporting Information. IL12 is one of the primary inflammatory cytokines and it is known that administration of recombinant IL12 protein induces liver toxicity.6 Electroporation-mediated delivery of IL12-encoding DNA (pIL12) rather than delivery of the recombinant protein has several advantages, such as inducing systemic production of the cytokine over time, thereby better mimicking the proinflammatory environment during liver pathogenesis. To establish an in vivo model to study cytokine-mediated liver toxicity by way of gene therapy, pIL12 was administered into muscles followed by electroporation.27

Robust expression of IL12 and IFN-γ protein were detected in the blood (Fig. 1A,B), suggesting that IL12 is biologically functional. Because both IL12 and IFN-γ enhance liver toxicity, we determined whether systemic introduction of Selleckchem IWR-1 IL12 DNA by way of electroporation induced liver toxicity. Liver histology confirmed that delivery of pIL12 but not control DNA induced typical lesions of IL12-induced hepatotoxicity (Fig. 1C). These lesions were mainly seen in the liver but not in other major organs (Supporting Fig. 1). Because infection- or proinflammatory cytokine-induced liver toxicity is resolved over time after initial injury, we hypothesized that the recovery is due to induction of naturally occurring key inhibitors against proinflammatory cytokines. Indeed, others have shown previously that an antiinflammatory cytokine such as IL10 is required during liver regeneration.28 Using microarrays, we identified that IL12 induces IL30, the p28 subunit of IL27, but does not induce the expression of EBI3,

the other subunit of IL27 (unpubl. data). Indeed, IL12 gene therapy induced IL30 Oxaprozin at a maximum level of 200 pg/mL on day 8 (Fig. 2A). To determine the primary cell source from which IL30 was induced by IL12, B cells, macrophages, dendritic cells (DCs), monocytes, and T cells were tested because the former three types of cells are known sources for IL27 production, whereas the T cells were used as a negative control.29 Irrespective of the cell types, no pronounced induction of IL30 by IL12 treatment was found in any of the cells (Supporting Fig. 2A), suggesting an intermediate molecule. Because IFN-γ is the primary IL12-induced cytokine, and a recent study showed IFN-γ induces IL30 expression in macrophages in vitro,5, 30 we tested whether IFN-γ acts as an IL12-effector cytokine for inducing IL30 expression.