Interleukin-1α and Interleukin-1β play a central role in the pathogenesis of fulminant hepatic failure in mice

<div><p>Background and aims</p><p>Fulminant hepatitis failure (FHF) is marked by the sudden loss of hepatic function, with a severe life-threatening course in persons with no prior history of liver disease. Interleukin (IL)-1α and IL-1β are key inflammatory cytokines but little is known about their role in the development of FHF. The aim of this study was to assess the involvement of IL-1α and IL-1β in the progression of LPS/GalN-induced FHF.</p><p>Methods</p><p>WT, IL-1α or IL-1β deficient mice were injected with LPS/GalN. Blood and liver tissue were collected at different time points, FHF related pathways were examined.</p><p>Results</p><p>After FHF induction the survival of both IL-1α and IL-1β KO mice was longer than that of WT mice. Lower serum liver enzyme levels, demonstrated reduced hepatic injury in the IL-1α and IL-1βKO mice. Histologically detected liver injury and apoptotic hepatocytes were significantly reduced in the IL-1αand IL-1βKO mice compared to WT mice. Reduced hepatic IkB levels and upregulated NFκB activity in WT mice remained inhibited in IL-1α and IL-1β KO mice. Hepatic expression levels of TNFα and IL-6 were significantly increased in WT mice but not in IL-1α and IL-1β KO mice.</p><p>Conclusions</p><p>IL-1α and IL-1β play a central role in the pathogenesis of LPS/GalN-induced FHF. These interleukins are associated with the activation of NFκB signaling, upregulation of the pro-inflammatory cytokines and liver damage and apoptosis. Since neither IL-1α nor IL-1β depletions completely rescued the phenotype, we believe that IL-1α and IL-1β have a similar and probably complementary role in FHF progression.</p></div

IκB protein levels in the livers of WT IL-1α and IL-1β KO mice after LPS/GalN injection.

<p>WT IL-1α and IL-1β KO mice were injected with LPS/GalN at time point 0. Mice were sacrificed at the indicated time points and proteins were purified from their livers. IκB protein levels were analyzed using western blot analysis.</p

Deficiency of IL-1α or IL-1β delayed FHF-associated liver damage compared to WT mice.

<p>Liver specimens were obtained from WT, IL-1α and IL-1β KO mice, 4 and 5 hours after the injection of LPS/GalN. Representative images of H&E-stained sections are shown. Apoptotic bodies (marked with arrows) were observed in livers of WT mice 4 hours after FHF induction (Fig 3A), while less damage and better preserved liver architecture were seen in IL1α in IL-1β KO mice at the same time post-FHF induction (Fig 3C and E). However, 5h following the injections, hepatic damage was also seen in the livers of the IL-1α and Il-1β KO mice.</p

Significant decrease in apoptosis was detected in the IL-1α or IL-1β deficient mice compared to WT mice after FHF induction.

<p>(A) WT IL-1α and IL-1β KO mice were injected with LPS/GalN at time point 0. Mice were sacrificed at the indicated time points and proteins were purified from their livers. The hepatic expression of the active, cleaved, Caspase 3 was detected using western blot analysis. (B) WT, IL-1α and IL-1β KO mice livers were harvested 5 hours after LPS/GalN injection and imbedded in paraffin blocks. Apoptotic cells were identified using the DeadEndTM flourometric TUNEL system.</p

Hepatic TNF-α and IL-6 expression in WT, IL-1α and IL-1β mice levels after LPS/GalN injection.

<p>WT, IL-1α and IL-1β KO mice were injected with LPS/GalN at time point 0. Mice were sacrificed at the indicated time points and RNA was purified from their livers. Hepatic TNF-α (A) and IL-6 (B) expression levels were evaluated using qRT-PCR (n = 3 in each group at each time point). Results are expressed as mean ± standard error. Differences between groups were assessed using the analysis of variance (T-TEST). Significant differences between the analyzed groups (IL-1α and IL-1β) and the control group (WT) are marked by * and represent Pv<0.05.</p

Alterations in hepatic IL-1α and IL-1β expression in IL-1α and IL-1β KO compare to WT mice after LPS/GalN injection.

<p>WT, IL-1α and IL-1β KO mice were injected with LPS/GalN at time point 0. Mice were sacrificed at the indicated time points and RNA was purified from their livers. Hepatic IL-1α and IL-1β expression levels were evaluated using qRT-PCR (n = 3 in each group at each time point). Results are expressed as mean ± standard error. Differences between groups were assessed using the analysis of variance (T-TEST).</p