13-hydroxy-9-11-octadecadienoic-acid and Asthma

The mechanisms underlying asthmatic airway epithelial injury are not clear. 12/15-lipoxygenase (an ortholog of human 15-LOX-1), which is induced by IL-13, is associated with mitochondrial degradation in reticulocytes at physiological conditions. In this study, we showed that 12/15-LOX expressed in nonepithelial cells caused epithelial injury in asthma pathogenesis. While 12/15-LOX overexpression or IL-13 administration to naïve mice showed airway epithelial injury, 12/15-LOX knockout/knockdown in allergic mice reduced airway epithelial injury. The constitutive expression of 15-LOX-1 in bronchial epithelia of normal human lungs further indicated that epithelial 15-LOX-1 may not cause epithelial injury. 12/15-LOX expression is increased in various inflammatory cells in allergic mice. Though non-epithelial cells such as macrophages or fibroblasts released 12/15-LOX metabolites upon IL-13 induction, bronchial epithelia didn't release. Further 12-S-HETE, arachidonic acid metabolite of 12/15-LOX leads to epithelial injury. These findings suggested 12/15-LOX expressed in non-epithelial cells such as macrophages and fibroblasts leads to bronchial epithelial injury.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 3T3 Cells; Animals; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Asthma; Blotting, Western; Cell Line; Cytochromes c; Epithelium; Fibroblasts; Humans; Immunohistochemistry; Interleukin-13; Lactones; Linoleic Acids; Lung; Macrophages; Male; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Electron, Transmission; Mitochondria; Sesquiterpenes, Eudesmane

We showed recently that IL-4 causes mitochondrial dysfunction in allergic asthma. IL-4 is also known to induce 12/15-lipoxygenase (12/15-LOX), a potent candidate molecule in asthma. Because vitamin E (Vit-E) reduces IL-4 and inhibits 12/15-LOX in vitro, here we tested the hypothesis that Vit-E may be effective in restoring key mitochondrial dysfunctions, thus alleviating asthma features in an experimental allergic murine model. Ovalbumin (OVA)-sensitized and challenged male BALB/c mice showed the characteristic features of asthma such as airway hyperresponsiveness (AHR), airway inflammation, and airway remodeling. In addition, these mice showed increase in the expression and metabolites of 12/15-LOX, reduction in the activity and expression of the third subunit of mitochondrial cytochrome-c oxidase, and increased cytochrome c in lung cytosol, which indicate that OVA sensitization and challenge causes mitochondrial dysfunction. Vit-E was administered orally to these mice, and 12/15-LOX expression, key mitochondrial functions, ultrastructural changes of mitochondria in bronchial epithelia, and asthmatic parameters were determined. Vit-E treatment reduced AHR, Th2 response including IL-4, IL-5, IL-13, and OVA-specific IgE, eotaxin, transforming growth factor-beta1, airway inflammation, expression and metabolites of 12/15-LOX in lung cytosol, lipid peroxidation, and nitric oxide metabolites in the lung, restored the activity and expression of the third subunit of cytochrome-c oxidase in lung mitochondria and bronchial epithelia, respectively, reduced the appearance of cytochrome c in lung cytosol, and also restored mitochondrial ultrastructural changes of bronchial epithelia. In summary, these findings show that Vit-E reduces key mitochondrial dysfunctions and alleviates asthmatic features.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Airway Remodeling; Animals; Anti-Asthmatic Agents; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Cytochromes c; Disease Models, Animal; Electron Transport Complex IV; Goblet Cells; Hyperplasia; Hypersensitivity; Immunoglobulin E; Interleukin-13; Interleukin-4; Interleukin-5; Linoleic Acids; Lung; Male; Mice; Mice, Inbred BALB C; Mitochondria; Ovalbumin; Oxidative Stress; Pulmonary Fibrosis; Transforming Growth Factor beta1; Vitamin E