Differential Effects Of Pyrrolidine Dithiocarbamate On Lipopolysaccharide-induced Liver Injury In Two Different Models Of Fulminant Hepatitis

Mice primed with Bacillus Calmette-Guerin (BCG) were challenged with lipopolysaccharide (LPS) to induce acute liver injury, with macrophages infiltration and massive release of tumor necrosis factor alpha (TNF-α). Mice were co-injected with d-galactosamine (GalN) and LPS to induce TNF-α-mediated apoptotic liver injury. Nuclear factor kappa B (NF-κB) activation might play important roles on LPS-induced liver injury in two different models of fulminant hepatitis. Pyrrolidine dithiocarbamate (PDTC) is an inhibitor of NF-κB activation. The present study was to investigate the effects of PDTC on LPS-induced liver injury in two different models of fulminant hepatitis.To explore the effects of PDTC on BCG/LPS-induced acute liver injury, mice were randomly divided into six groups. All mice except control groups were infected intravenously (i.v.) with BCG (2.5 mg, suspended in 0.2 mL saline). Ten days later, mice in BCG/LPS group were injected with LPS (0.2 mg/kg, i.p.). Mice in BCG/LPS+ PDTC group were injected with two doses of PDTC, one (100 mg/kg, i.p.) at 24 h before LPS and the other at 2 h before LPS (0.2 mg/kg, i.p.). Mice in control groups were intraperitoneally (i.p.) administrated with LPS (0.2 mg/kg), PDTC (100 mg/kg) or saline. Fifteen mice in each group were observed for animal survival within 72 h after LPS treatment. Six mice in each group were sacrificed 1.5 h after LPS administration for collecting blood serum and isolating livers. The expression of hepatic TNF-α, IL-1βand IL-6 mRNA were determined by RT-PCR. Hepatic NF-κB binding activity was measured using EMSA. Serum TNF-αlevel was analyzed by ELISA. Twelve mice in each group were sacrificed 6 h after LPS treatment. Blood serum was collected for measurement of alanine aminotransferase (ALT) and nitrate plus nitrite. Livers were dissected for glutathione (GSH) measurement and histological examination. Results showed that administration of LPS to mice primed with BCG resulted in 40% mortality, elevated serum ALT activity, induced hepatic necrosis and massive macrophages infiltration. BCG/LPS treatment triggered hepatic NF-κB binding activity, up-regulated expression of hepatic TNF-α, decreased hepatic GSH level, and increased serum NO production. PDTC pretreatment significantly inhibited hepatic NF-κB binding activity, down-regulated expression of hepatic TNF-α, attenuated BCG/LPS-induced hepatic GSH depletion and NO production. Correspondingly, PDTC pretreatment markedly reduced BCG/LPS-induced increase in serum ALT activity, attenuated hepatic inflammation and necrosis, and decreased mortality.To investigate the effects of PDTC on GalN/LPS-induced acute liver injury, all mice were randomly divided into six groups. Mice in GalN/LPS group were co-injected with GalN (600 mg/kg, i.p.) and LPS (20μg/kg, i.p.). Mice in PDTC+GalN/LPS were injected with two doses of PDTC, one (100 mg/kg, i.p.) at 24 h before LPS and the other at 2 h before LPS (20μg/kg, i.p.). Mice in control groups were treated with LPS (20μg/kg, i.p.), GalN (600 mg/kg, i.p.), PDTC (100 mg/kg, i.p.) or saline. Ten mice in each group were observed for animal survival within 72 h after LPS treatment. Six mice in each group were sacrificed 1.5 h after LPS for collecting blood serum and isolating livers. The expression of hepatic TNF-α, IL-1βand IL-6 mRNA was determined by RT-PCR. Hepatic NF-κB binding activity was measured using EMSA. Serum TNF-αlevel was analyzed by ELISA. Twelve mice in each group were sacrificed 6 h after LPS treatment. Blood serum was collected for measurement of ALT and nitrate plus nitrite. Livers were dissected for measurements of GSH content, caspase-3 activity and hepatocellular apoptosis and histological examination. Results showed that co-injection of GalN and LPS led to 90% mortality, increased serum ALT activity and hepatic caspase-3 activity, triggered hepatocellular apoptosis and massive macrophages infiltration, decreased hepatic GSH level, and increased NO production. PDTC pretreatment significantly inhibited GalN/LPS-induced expression of hepatic TNF-αand attenuated hepatic GSH depletion and NO production. In contrast, PDTC aggravated GalN/LPS-triggered hepatocellular apoptosis, increased serum ALT activity, exacerbated hepatic hemorrhage and necrosis, and accelerated death.Taken together, our results suggest that PDTC plays differential effects on LPS-induced liver injury in two different models of fulminant hepatitis. PDTC pretreatment protects mice against BCG/LPS-induced acute liver injury via inhibiting NF-κB activation and TNF-αrelease. Conversely, PDTC aggravates GalN/LPS-induced acute liver injury through repressing NF-κB-mediated anti-apoptotic effect in hepatocytes.