15-Lipoxygenase promotes chronic hypoxia-induced pulmonary artery inflammation via positive interaction with nuclear...

Our laboratory has previously demonstrated that 15-lipoxygenase (15-LO)/15-hydroxyeicosatetraenoic acid (15-HETE) is involved in hypoxic pulmonary arterial hypertension. Chronic hypoxia-induced vascular inflammation has been considered as an important stage in the development of pulmonary arterial hypertension. Here, we determined the contribution of 15-HETE in the hypoxia-induced pulmonary vascular inflammation.

Chronic hypoxia-induced monocyte/macrophage infiltration and the expressions of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were analyzed in hypoxic rat model and cultured pulmonary arterial endothelium cells using immunochemistry methods. We found that monocyte/macrophage infiltration and the expressions of intercellular adhesion molecules under hypoxia were markedly inhibited by 15-HETE inhibitors or 15-LO1/2 small interfering RNA. In addition, exogenous 15-HETE enhanced the expression of both adhesion molecules in pulmonary arterial endothelium cells in a time-dependent manner. Hypoxia-induced 15-LO1/2 expression in rat pulmonary arterial endothelium cells was significantly abolished by nuclear factor-κB inhibitors. Meanwhile, nuclear factor-κB activity was enhanced prominently by the 15-LO1/2 product, 15-HETE, suggesting a positive feedback mechanism.

Taken together, our results suggest that chronic hypoxia promotes monocyte infiltration into the vasculature and adhesion molecules upregulation in pulmonary arterial endothelium cells via a positive interaction between 15-LO/15-HETE and nuclear factor-κB. Our study revealed a novel mechanism underlying hypoxia-induced pulmonary arterial inflammation and suggested new therapeutic strategies targeting 15-LO/15-HETE and nuclear factor-κB in the treatment of pulmonary arterial hypertension.