[Recombinant cIL-18-binding protein as an antagonist to cIL-18 enhanced PBMCs secreting IFN-gamma].

OBJECTIVE: Interleukin-18 (IL-18) is a proinflammatory cytokines that plays a key role of immune regulation through activating the Th 1 cell and NK cell secreting interferon-gamma (IFN-gamma). IL-18-binding proteins(IL-18BP) secreted in human and mouse can antagonise the activity of IL-18. The homologue gene of IL-18BP from fowlpox virus genome was predicted and identified of its expressed protein, to use as an antagonist to IL-18 guiding disease. METHODS: The cIL-18BP gene was isolated from the genome of fowlpox vaccine virus by PCR through a pair of special primers and cloned into vectors pPICZalphaA, then expressed in yeast GS115. The biologic activity of recombinant proteins binding with cIL-18 was measured, inhibiting the activity of cIL-18 enhancing relative cells secreting IFN-gamma was confirmed through ELISA. RESULTS: The cIL-18BP gene was cloned from fowlpox virus and acquired high performance expression in yeast systems induced with methanol identified by SDS-PAGE. Recombinant cIL-18BP purified can bind specifically with recombinant cIL-18 determined by ELISA test. cIL-18BP can antagonise the activity of cIL-18 with determining the IFN-gamma concentration secreting in PBMCs and MSB1 cells stimulated by cIL-18 respectively. CONCLUSION: The experiment indicates that recombinant cIL-18BP can inhibit the activity of cIL-18 stimulating related immune cells secreting IFN-gamma. Deletion of the cIL-18BP from virus may improve the safety and immunogenicity of fowlpox virus vaccine.

Inhibition of JNK signalling mediates PPARα-dependent protection against intrahepatic cholestasis by fenofibrate.

BACKGROUND AND PURPOSE: Fenofibrate, a PPARα agonist, is the most widely prescribed drug for treating hyperlipidaemia. Although fibrate drugs are reported to be beneficial for cholestasis, their underlying mechanism has not been determined. EXPERIMENTAL APPROACH: Wild-type mice and Pparα-null mice were pretreated orally with fenofibrate for 3 days, following which α-naphthylisothiocyanate (ANIT) was administered to induce cholestasis. The PPARα agonist WY14643 and JNK inhibitor SP600125 were used to determine the role of PPARα and the JNK pathway, respectively, in cholestatic liver injury. The same fenofibrate regimen was applied to investigate its beneficial effects on sclerosing cholangitis in a DDC-induced cholestatic model. KEY RESULTS: Fenofibrate, 25 mg·kg-1 twice a day, totally attenuated ANIT-induced cholestasis and liver injury as indicated by biochemical and histological analyses. This protection occurred in wild-type, but not in Pparα-null, mice. Alterations in bile acid synthesis and transport were found to be an adaptive response rather than a direct effect of fenofibrate. WY14643 attenuated ANIT-induced cholestasis and liver injury coincident with inhibition of JNK signalling. Although SP600125 did not affect cholestasis, it inhibited liver injury in the ANIT model when the dose of fenofibrate used was ineffective. Fenofibrate was also revealed to have a beneficial effect in the sclerosing cholangitis model. CONCLUSIONS AND IMPLICATIONS: These data suggest that the protective effects of fenofibrate against cholestasis-induced hepatic injury are dependent on PPARα and fenofibrate dose, and are mediated through inhibition of JNK signalling. This mechanism of fenofibrate protection against intrahepatic cholestasis may offer additional therapeutic opportunities for cholestatic liver diseases.

Protective effects of green tea polyphenols on human HepG2 cells against oxidative damage of fenofibrate.

The aim of this work was to investigate the protective effects of green tea polyphenols on the cytotoxic effects of hypolipidemic agent fenofibrate (FF), a peroxisome proliferator (PP), in human HepG2 cells. The results showed that high concentrations of FF induced human HepG2 cell death through a mechanism involving an increase of reactive oxygen species (ROS) and intracellular reduced glutathione (GSH) depletion. These effects were partially prevented by antioxidant green tea polyphenols. The elevated expression of PP-activated receptors alpha (PPARalpha) in HepG2 cells induced by FF was also decreased by treatment with green tea polyphenols. In conclusion, this result demonstrates that oxidative stress and PPARalpha are involved in FF cytotoxicity and green tea polyphenols have a protective effect against FF-induced cellular injury. It may be beneficial for the hyperlipidemic patients who were administered the hypolipidemic drug fenofibrate to drink tea or use green tea polyphenols synchronously during their treatment.