The snake venom miotoxin (MT)-III is a group IIA secreted phospholipase A2 (sPLA2) with pro-inflammatory activities. Previous studies have demonstrated that MT-III has the ability to stimulate macrophages to release inflammatory lipid mediators derived from arachidonic acid metabolism. Among them, we highlight prostaglandin (PG)E2 produced by the cyclooxygenase (COX)-2 pathway, through activation of nuclear factor (NF)-κB. However, the mechanisms coordinating this process are not fully understood. This study investigates the regulatory mechanisms exerted by other groups of bioactive eicosanoids derived from 12-lipoxygenase (12-LO), in particular 12-hydroxyeicosatetraenoic (12-HETE), on group IIA sPLA2-induced (i) PGE2 release, (ii) COX-2 expression, and (iii) activation of signaling pathways p38 mitogen-activated protein kinases(p38MAPK), protein C kinase (PKC), extracellular signal-regulated kinase 1/2 (ERK1/2), and NF-κB. Stimulation of macrophages with group IIA sPLA2 resulted in release of 12-HETE without modification of 12-LO protein levels. Pre-treatment of these cells with baicalein, a 12-LO inhibitor, decreased the sPLA2-induced PGE2 production, significantly reduced COX-2 expression, and inhibited sPLA2-induced ERK; however, it did not affect p38MAPK or PKC phosphorylation. In turn, sPLA2-induced PGE2 release and COX-2 expression, but not NF-κB activation, was attenuated by pre-treating macrophages with PD98059 an inhibitor of ERK1/2. These results suggest that, in macrophages, group IIA sPLA2-induced PGE2 release and COX-2 protein expression are distinctly mediated through 12-HETE followed by ERK1/2 pathway activation, independently of NF-κB activation. These findings highlight an as yet undescribed mechanism by which 12-HETE regulates one of the distinct signaling pathways for snake venom group IIA sPLA2-induced PGE2 release and COX-2 expression in macrophages.

中文翻译：

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12-HETE是通过蛇毒组IIA磷脂酶A2在分离的腹膜巨噬细胞中诱导的COX-2表达来调节PGE2产生的调节剂。

蛇毒线粒体毒素（MT）-III是IIA类分泌的具有促炎活性的磷脂酶A2（sPLA2）。先前的研究表明，MT-III具有刺激巨噬细胞释放源自花​​生四烯酸代谢的炎性脂质介体的能力。其中，我们重点介绍了环氧化酶（COX）-2途径通过激活核因子（NF）-κB产生的前列腺素（PG）E2。但是，协调此过程的机制尚未完全了解。这项研究调查了源自12-脂氧合酶（12-LO），尤其是12-羟基二十碳四烯酸（12-HETE）的其他生物活性类花生酸对IIA组sPLA2诱导的调控机制（i）PGE2释放，（ii） COX-2的表达，以及（iii）信号通路的激活p38丝裂原活化蛋白激酶（p38MAPK），蛋白C激酶（PKC），细胞外信号调节激酶1/2（ERK1 / 2）和NF-κB。用IIA组sPLA2刺激巨噬细胞导致释放12-HETE，而没有改变12-LO蛋白水平。用黄ical苷（一种12-LO抑制剂）预处理这些细胞，可降低sPLA2诱导的PGE2产生，显着降低COX-2表达，并抑制sPLA2诱导的ERK。但是，它不影响p38MAPK或PKC磷酸化。反过来，通过用ERK1 / 2抑制剂PD98059对巨噬细胞进行预处理，可减弱sPLA2诱导的PGE2释放和COX-2表达，但不会减弱NF-κB激活。这些结果表明，在巨噬细胞中，IIA组sPLA2诱导的PGE2释放和COX-2蛋白表达是通过12-HETE继之以ERK1 / 2途径活化而独立地介导的，而与NF-κB活化无关。