弓形虫诱导巨噬细胞COX-2的表达增加PGE2合成

目的 探讨弓形虫侵染巨噬细胞过程中前列腺素E2(PGE2)的产生途径。方法 用LPS及弓形虫作用于小鼠RAW264．7巨噬细胞系。用气相色谱、ELISA方法分别检测培养上清液中PGE2及花生四烯酸(AA)含量；用RT—PCR及Western blot方法分别检测环加氧酶—l(COX—1)、环加氧酶—2(COX—2)的mRNA及蛋白质表达水平；特异性抑制剂阻断作用于细胞后检测PGE2含量，COX—l／COX—2的mRNA及蛋白质表达。结果 PGE2的合成在弓形虫侵染巨噬细胞4—8h开始升高，12--l6h后达到饱和水平；COX—2mRNA表达在4—8h出现最高峰，在特异性COX—2抑制剂Nimesulide及Indomethacin作用下其表达水平下降，而蛋白质表达水平不受影响。COX—l的mRNA及蛋白质表达在抑制剂处理前后及不同的时间点都末见明显变化。结论 弓形虫可能通过诱导巨噬细胞表达COX—2增加PGE2的合成。

TOXOPLASMA GONDII INDUCES PROSTAGLANDIN E2 SYNTHESIS IN MACROPHAGES VIA CYCLOOXYGENASE-2 PATHWAY

Objective To explore prostaglandin E 2 (PGE 2) production pathway in Toxoplasma gondii-infected macrophage RAW264.7 cell line.Methods Cells were incubated with Toxoplasma gondii tachyzoites and lipopolysaccharides (LPS). Prostaglandin synthesis and arachidonic acid in supernants were detected with ELISA and gas chromatogram. Expression of cyclooxygenase-1/cyclooxygenase-2 (COX-1/COX-2) mRNA and protein following stimulation with LPS or infection of Toxoplasma gondii were evaluated with RT-PCR and Western blot in presence or absence of peculiar antagonists of PGE 2 production. Results PGE 2 synthesis of macrophages began at 4-8 h after invasion with Toxoplasma gondii and saturated at 12-16 h. Expression of COX-2 mRNA peaked at 4-8 h, and diminished in presence of both indomethacin and nimesulide, COX-2 protein expression was not affected by them. Expression of COX-1 mRNA and protein were constant and not affected by either indomethacin or nimesulide. Conclusion Toxoplasma gondii may induce macrophages prostaglandin E 2 synthesis via cyclooxygenase-2 pathway.