15-keto-5-8-11-13-eicosatetraenoic-acid and Hypertension--Pulmonary

Pulmonary arterial hypertension (PAH) is a progressive condition in which remodeling of the pulmonary vasculature plays an important role. The vascular remodeling involves pulmonary arterial smooth muscle cell (PASMC) proliferation and apoptosis, which is affected by several arachidonic acid metabolites. 15-oxo-Eicosatetraenoic acid (15-oxo-ETE) is one of the metabolites. However, the biological role of 15-oxo-ETE in PASMCs remains unknown. Here we show evidence for the modulation of PASMC apoptosis by 15-oxo-ETE. We found that 15-oxo-ETE increased rat and human PASMC viability. Consistently, 15-oxo-ETE attenuated nuclear fragmentation and DNA strand breaks, decreased caspase-3 activity, reduced mitochondrial depolarization, and increased Bcl-2 expression. Interestingly, the anti-apoptotic effect of 15-oxo-ETE was lost when the Akt intracellular signaling pathway was blocked. Taken together, we have established that 15-oxo-ETE protects PASMCs against apoptosis through the Akt pathway. These results suggest that 15-oxo-ETE seems to be a potential agent for PAH controls by preventing unwanted PASMC death.

Topics: Animals; Apoptosis; Arachidonic Acids; Caspase 3; Cell Survival; Cells, Cultured; Chromones; Culture Media, Serum-Free; Female; Humans; Hypertension, Pulmonary; Morpholines; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Pulmonary Artery; Rats; Rats, Wistar; Signal Transduction; Transcriptional Activation

We have established that 15-hydroxyeicosatetraenoic acid is an important factor in regulation of pulmonary vascular remodeling (PVR) associated with hypoxia-induced pulmonary hypertension (PH), which is further metabolized by 15-hydroxyprostaglandin dehydrogenase (15-PGDH) to form 15-ketoeicosatetraenoic acid (15-KETE). However, the role of 15-PGDH and 15-KETE on PH has not been identified. The purpose of this study was to investigate whether 15-PGDH/15-KETE pathway regulates hypoxia-induced PVR in PH and to characterize the underlying mechanisms. To accomplish this, Immunohistochemistry, Ultra Performance Liquid Chromatography, Western blot, bromodeoxyuridine incorporation and cell cycle analysis were preformed. Our results showed that the levels of 15-PGDH expression and endogenous 15-KETE were drastically elevated in the lungs of humans with PH and hypoxic PH rats. Hypoxia stimulated pulmonary arterial smooth muscle cell (PASMC) proliferation, which seemed to be due to the increased 15-PGDH/15-KETE. 15-PGDH/15-KETE pathway was also capable of stimulating the cell cycle progression and promoting the cell cycle-related protein expression. Furthermore, 15-KETE-promoted cell cycle progression and proliferation in PASMCs depended on protease-activated receptor 2 (PAR-2). ERK1/2 signaling was likely required for 15-PGDH/15-KETE-induced PAR-2 expression under hypoxia. Our study indicates that 15-PGDH/15-KETE stimulates the cell cycle progression and proliferation of PASMCs involving ERK1/2-mediated PAR-2 expression, and contributes to hypoxia-induced PVR.

Topics: Animals; Arachidonic Acids; Cell Cycle; Cell Cycle Proteins; Cell Hypoxia; Cell Proliferation; Cells, Cultured; Eicosapentaenoic Acid; Extracellular Signal-Regulated MAP Kinases; Humans; Hydroxyprostaglandin Dehydrogenases; Hypertension, Pulmonary; Lung; Male; MAP Kinase Signaling System; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Pulmonary Artery; Random Allocation; Rats; Rats, Wistar; Receptor, PAR-2; RNA Interference; RNA, Small Interfering; Vascular Remodeling