Enhanced expressions and activations of leukotriene C4synthesis enzymes in D-galactosamine/lipopolysaccharide-induced rat fulminant hepatic failure model

AIM： To investigate the expression and activity of leukotriene C4 （LTC4） synthesis enzymes and their underlying relationship with cysteinyl leukotriene （cys-LT） generation in a rat fulminant hepatic failure （FHF） model induced by D-galactosamine/lipopolysaccharide （D-GaIN/ LPS）. METHODS： Rats were treated with D-GaIN （300 mg/kg） plus LPS （0.1 mg/kg） for 1, 3, 6, and 12 h. Enzyme immunoassay was used to determine the hepatic cys-LT content. Reverse transcription-polymerase chain reaction （RT-PCR）, Western blot or immunohistochemical assay were employed to assess the expression or location of LTC4 synthesis enzymes, which belong to membrane associated proteins in eicosanoid and glutathione （MAPEG） metabolism superfamily. Activity of LTC4 synthesis enzymes was evaluated by determination of the products of LTA4 after incubation with liver microsomes using high performance liquid chromatography （HPLC）. RESULTS： Livers were injured after treatment with D-GaIN/LPS, accompanied by cys-LT accumulation at the prophase of liver injury. Both LTC4 synthase （LTC4S） and microsomal glutathione-S-transferase （mGST） 2 were expressed in the rat liver, while the latter was specifically located in hepatocytes. Their mRNA and protein expressions were up-regulated at an earlier phase after treatment with D-GaIN/LPS. Meantime, a higher activity of LTC4 synthesis enzymes was detected, although theactivity of LTC4S played the main role in this case. CONCLUSION： The expression and activity of both LTC4S and mGST2 are up regulated in a rat FHF model, which are, at least, partly responsible for cys-LT hepatic accumulation.

Association between leukotriene C_4 synthase A_(444)C polymorphism and asthma in Chinese Han population in Beijing

Leukotrienes （LTs） are synthesized from membrane derived arachidonic acid.Downstream of 5-lipoxygenase in the arachidonic acid cascade, leukotriene C4 synthase （LTC4S） catalyses the conjugation of leukotriene A4 （LTA4） with reduced glutathione to form LTC4, then LTC4 convert to active metabolites LTD4 and LTE4. LTC4, LTD4 and LTE4, which are called cysteinyl leukotrienes （CysLTs）, are potent proinflammatory mediators of asthma. LTC4S is the key enzyme involved in the formation of CysLTs. There is a polymorphism of adenine （A） to cytosine （C） transversion at -444 locus in the promoter region of the LTC4S gene, A-444C.^1 This allelic variant results in an extra recognition site for the Ap-2 transcription factor and is associated with an increased LTC4S transcription rate.^2 Some studies in other countries suggest that LTC4S A-444C polymorphism is associated with asthmatic severity and clinical response to leukotriene receptor antagonist.^3-5 Little is known about the frequency of the LTC4S gene variant in the Chinese population. In this study, we evaluated the association of LTC4S A-444C polymorphism with susceptibility to asthma, severity of asthma and clinical response to a leukotriene receptor antagonist, montelukast, in Chinese Han people in Beijing.

The Anti-Inflammatory Effect of Cheongseoikki-Tang Ethanol Extract on Allergic Reactions Mediated by Bone Marrow-Derived Mast Cells

Objective： Cheongseoikki-tang （CIT, Korean）, also called Qingshu Yiqi decoction（清署益气汤）and Seisho-ekki-to （Japanese）, is well known as an effective traditional combination of herbs for treating cardiovascular diseases. This study was to research its effects on bone marrow-derived mast cell （BMMC）-mediated allergy and inflammation mechanisms. Methods： In this study, the biological effect of Cheongseoikki-tang ethanol extract （CITE） was evaluated, focusing on its effects on the production of allergic mediators by phorbol 12-myfistate 13-acetate （PMA） plus calcium ionophore A23187 （A23187）-stimulated BMMCs. These allergic mediators included intedeukin-6 （IL-6）, prostaglandin D2 （PGD2）, leukotfiene （34 （LTC4）, and β-hexosaminidase （13-hex）. Results： Our data revealed that CITE inhibited the production of IL-6, PGD2,/TC4, and 15-hex induced by PMA plus A23187 （P〈0.05）. Conclusion： These findings indicate that CITE has the potential for use in the treatment of allergy.