Figure 6. IL-1α release by necrotic hepatocytes and IL-1R signaling promote IL-6 production, compensatory proliferation and hepatocarcinogenesis.

(A) Concentrations of IL-1α and IL-1β in supernatants of live hepatocytes (no necrosis), necrotic hepatocytes (1 × 10⁶ cells per ml) lysed by one (1× necrosis) or three (3× necrosis) cycles of freezing and thawing were measured by ELISA. Results are means ± SEM (n=3). (B) IL-1α in venous blood collected 4 hrs after DEN injection was determined by ELISA. Results are means ± SEM (n=4). *, p<0.05 vs. control mice (F/F). (C) Mice were fed either BHA-supplemented (0.7%) or regular chow for 2 days prior to DEN injection. IL-1α and IL-6 in venous blood collected 4 hrs after DEN injection were determined by ELISA. Results are means ± SEM (n=3). *, p<0.05 vs. control. (D) Roles of IL-1R and MyD88 in IL-6 induction. Mice were injected with DEN and liver RNA was extracted at the indicated times. IL-6 mRNA was quantified by real time Q-PCR. Results are means ± SEM (n=4). *, p<0.05 vs. control mice. (E, F) Effects of IL-1R ablation on inflammation and compensatory proliferation. Extent of neutrophil infiltration (E) and compensatory proliferation (F) were determined by MPO assay (results show fluorescent intensity) and BrdU labeling, respectively, 48 hrs after DEN injection. Results are means ± SEM (n=4). *, p<0.05 vs. control mice (WT). (G) Anakinra inhibits compensatory proliferation and IL-6 production. PBS or Anakinra (1 g/kg/day) were given for 2 days starting at the time of DEN injection. Hepatocyte proliferation was measured by BrdU incorporation at 48 hrs while serum IL-6 was measured at 6 hrs after DEN administration. Results are means ± SEM (n=3). *, p<0.05 vs. control. (H) Tumor multiplicity (>0.5mm) and maximal tumor sizes (diameters) in livers of male Il1r^−/− (n=12) and WT (n=14) mice. Results are means ± SEM. *, p<0.05 vs. control mice (WT).