The role of Kupffer cells after major liver surgery

Effect of dichloromethylene diphosphonate on liver regeneration following thioacetamide-induced necrosis in rats

AIM: To study the effect of dichloromethylene diphosphonate (DMDP), a selective Kupffer cell toxicant in reference to liver damage and postnecrotic liver regeneration in rats induced by sublethal dose thioacetamide (TA).

METHODS: Rats, intravenously (iv) pre-treated with a single dose of DMDP (10 mg/kg), were intraperitoneally (ip) injected with TA 6.6 mmol/kg (per 500 mg/kg body weight). Hepatocytes were isolated from rats at 0, 24, 48 and 72 h following TA intoxication and blood and liver samples were obtained. To evaluate the mechanisms involved in the postnecrotic regenerative state, DNA distribution and ploidy time course were assayed in isolated hepatocytes. Circulating cytokine tumor necrosis factor-alpha (TNF-α) was assayed in serum and determined by reverse transcriptase-polymerase chain reaction in liver extract.

RESULTS: The effect of DMDP induced noticeable changes in postnecrotic regeneration, causing an increased percentage of hepatocytes in the cell cycle S phase. The increase at 24 h in S₁ population in rats pretreated with DMDP + TA was significantly (P < 0.05) different compared with that of the TA group (18.07% vs 8.57%). Hepatocytes increased their proliferation as a result of these changes. Also, TNF-α expression and serum level were increased in rats pre-treated with DMDP. Thus, DMDP pre-treatment reduced TA-induced liver injury and accelerated postnecrotic liver regeneration.

CONCLUSION: These results demonstrate that Kupffer cells are involved in TA-induced liver, as well as in postnecrotic proliferative liver states.

Increased systemic and brain cytokine production and neuroinflammation by endotoxin following ethanol treatment

BACKGROUND

Cytokines and alcohol share a common modulation of inflammation and hormones as well as being implicated in multiple diseases, but the mechanisms are poorly understood. The purpose of this study was to investigate the interaction of liver, serum and brain cytokines as well as whether ethanol would potentiate endotoxin (Lipopolysaccharide, LPS) responses once ethanol had cleared.

METHODS

Male C57BL/6J mice were treated intragastrically with water (control) or ethanol (5 g/kg, i.g., 25% ethanol, w/v), with volumes matched, for 1 day or daily for 10 days. Mice were then injected intraperitoneally with saline (control) or LPS (3 mg/kg, i.p.) in saline 24 hrs after the last dose of ethanol. Gene expression and protein synthesis of proinflammatory cytokines and anti-inflammatory cytokine, oxidative enzymes, microglial activation and inhibition of neurogenesis were examined using real-time PCR, ELISA, and immunohistochemistry.

RESULTS

LPS increased proinflammatory cytokines (TNFalpha, MCP-1, IL-1beta) several fold in liver, brain and serum at 1 hr. Ethanol is known to increase liver cytokines and alter the risk of multiple chronic diseases. Ten daily doses of ethanol increased brain and liver TNFalpha, and pretreatment with ethanol potentiated LPS-induced increases in TNFalpha, MCP-1, IL-1beta in liver, serum and brain. Proinflammatory cytokine levels in liver and serum returned to basal levels within a day, whereas brain proinflammatory cytokines remained elevated for long periods. IL-10, an anti-inflammatory cytokine, is reduced in brain by ethanol and LPS, while brain proinflammatory cytokines remain increased, whereas liver IL-10 is increased when proinflammatory cytokines have returned to control levels. Activation of brain microglia indicated by morphological changes, reduced neurogenesis and increased brain expression of COX-2 and gp91phox NADPH oxidase subunit mRNA were found in the 10 daily doses of ethanol-pretreated LPS group.

CONCLUSION

Acute increases in serum cytokines induce long lasting increases in brain proinflammatory cytokines. Ten daily doses of ethanol exposure results in persistent alterations of cytokines and significantly increases the magnitude and duration of central and peripheral proinflammatory cytokines and microglial activation. Ethanol induced differential anti-inflammatory cytokine IL-10 responses in liver and brain could cause long lasting disruption of cytokine cascades that could contribute to protection or increased risk of multiple chronic diseases.