17-18-epoxy-5-8-11-14-eicosatetraenoic-acid and Asthma

Asthma is characterized by airway inflammation and obstruction with eosinophil infiltration into the airway. Arachidonic acid, an omega-6 fatty acid, is metabolized into cysteinyl leukotriene with pro-inflammatory properties for allergic inflammation, whereas the omega-3 fatty acid eicosapentaenoic acid (EPA) and its downstream metabolites are known to have anti-inflammatory effects. In this study, we investigated the mechanism underlying the counter-regulatory roles of EPA in inflamed lungs.. Male C57BL6 mice were sensitized and challenged by ovalbumin (OVA). After EPA treatment, we evaluated the cell count of Bronchoalveolar lavage fluid (BALF), mRNA expressions in the lungs by q-PCR, and the amounts of lipid mediators by liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based lipidomics. We investigated the effect of the metabolite of EPA by in vivo and in vitro studies.. Eicosapentaenoic acid treatment reduced the accumulation of eosinophils in the airway and decreased mRNA expression of selected inflammatory mediators in the lung. Lipidomics clarified the metabolomic profile in the lungs. Among EPA-derived metabolites, 12-hydroxy-17,18-epoxyeicosatetraenoic acid (12-OH-17,18-EpETE) was identified as one of the major biosynthesized molecules; the production of this molecule was amplified by EPA administration and allergic inflammation. Intravenous administration of 12-OH-17,18-EpETE attenuated airway eosinophilic inflammation through downregulation of C-C chemokine motif 11 (CCL11) mRNA expression in the lungs. In vitro, this molecule also inhibited the release of CCL11 from human airway epithelial cells stimulated with interleukin-4.. These results demonstrated that EPA alleviated airway eosinophilic inflammation through its conversion into bioactive metabolites. Additionally, our results suggest that 12-OH-17,18-EpETE is a potential therapeutic target for the management of asthma.

Topics: Animals; Anti-Inflammatory Agents; Arachidonic Acids; Asthma; Disease Models, Animal; Eosinophilia; Inflammation; Lung; Male; Mice; Mice, Inbred C57BL

Protein kinase C variants (PKCs) have been involved in the control of airway smooth muscle (ASM) tone, and abnormalities in PKC-dependent signaling have been associated with respiratory diseases such as asthma. In this study, the role of atypical PKCζ in airway hyperresponsiveness was investigated, using an in-vitro model of TNFα-treated human bronchi and an in vivo guinea pig model of chronic asthma. Our results demonstrated that PKCζ-specific inhibition produced a significant increase in isoproterenol sensitivity in TNFα-treated bronchi and ovalbumin (OVA)-sensitized guinea pig bronchi. The role of epoxy-eicosanoids, known to exert anti-inflammatory effects in lung, on PKCζ expression and activity in these models was evaluated. An enhanced PKCζ protein expression was delineated in TNFα-treated bronchi when compared with control (untreated) and epoxy-eicosanoid-treated bronchi. Measurements of Ca(2+) sensitivity, performed in TNFα-treated bronchi, demonstrated that treatment with myristoylated (Myr) PKCζ peptide inhibitor resulted in significant reductions of pCa-induced tension. Epoxy-eicosanoid treatments had similar effects on Ca(2+) sensitivity in TNFα-treated bronchi. In control and epoxy-eicosanoid-treated bronchi, the phosphorylated forms of p38MAPK and CPI-17 were significantly decreased compared with the TNFα-treated bronchi. An enhanced expression of PKCζ was ascertained in our in-vivo model of allergic asthma. Hence an increased Ca(2+) sensitivity could be explained by the phosphorylation of p38-MAPK, which in turn leads to phosphorylation and activation of the CPI-17 regulatory protein. This process was reversed upon treatment with the Myr-PKCζ-peptide inhibitor. The present data provide relevant evidence regarding the role of PKCζ in human and rodent models of airways inflammation.

Topics: Adrenergic beta-2 Receptor Agonists; Animals; Arachidonic Acids; Asthma; Biomechanical Phenomena; Bronchi; Bronchial Hyperreactivity; Bronchodilator Agents; Calcium; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Guinea Pigs; Humans; Intracellular Signaling Peptides and Proteins; Male; Muscle Contraction; Muscle Proteins; Muscle Relaxation; Muscle, Smooth; Ovalbumin; p38 Mitogen-Activated Protein Kinases; Phosphoprotein Phosphatases; Phosphorylation; Pneumonia; Protein Kinase C; Protein Kinase Inhibitors; Tissue Culture Techniques; Tumor Necrosis Factor-alpha; Up-Regulation