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Cyclooxygenase (COX)-2 has been shown to be involved in regulating basal airway function, bacterial LPS-induced airway hyperresponsiveness (AHR) and lung inflammation, and bleomycin-induced lung fibrosis; however, the cellular source of COX-2 that underlies these effects is unknown. We generated mice with alveolar type II (ATII) cell-specific knockdown of COX-2 (AT2CC-/-), to examine the role of ATII cell-derived prostaglandins (PGs) in these processes. Specific knockdown of COX-2 was confirmed by real-time RT-PCR and Western blot analyses. LC/MS/MS analysis showed that ATII cells produced PGs. Basal airway responsiveness of AT2CC-/- mice was decreased compared to that of wild-type (WT) mice. LPS-induced hypothermic response, infiltration of inflammatory cells into the airway, and lung inflammation were enhanced in AT2CC-/- mice relative to WT controls; however, LPS-induced AHR and proinflammatory cytokine and chemokine expression were similar between the genotypes. After 21 d of bleomycin administration, AT2CC-/- mice behaved in a manner similar to WT mice. Thus, ATII cell-derived COX-2 plays an important role in regulating basal airway function and LPS-induced lung inflammation, but does not play a role in bleomycin-induced fibrosis. These findings provide insight into the cellular source of COX-2 related to these lung phenotypes.--Cheng, J., Dackor, R. T., Bradbury, J. A., Li, H., DeGraff, L. M., Hong, L. K., King, D., Lih, F. B., Gruzdev, A., Edin, M. L., Travlos, G. S., Flake, G. P., Tomer, K. B., Zeldin, D. C. Contribution of alveolar type II cell-derived cyclooxygenase-2 to basal airway function, lung inflammation, and lung fibrosis. [ABSTRACT FROM AUTHOR]

Prostaglandin E2 (PGE2) is a lipid mediator that is produced via the metabolism of arachidonic acid by cyclooxygenase enzymes. In the lung, PGE2 acts as an anti-inflammatory factor and plays an important role in tissue repair processes. Although several studies have examined the role of PGE2 in the pathogenesis of pulmonary fibrosis in rodents, results have generally been conflicting, and few studies have examined the therapeutic effects of PGE2 on the accompanying lung dysfunction. In this study, an established model of pulmonary fibrosis was used in which 10-12-wk-old male C57BL/6 mice were administered a single dose (1.0 mg/kg) of bleomycin via oropharyngeal aspiration. To test the role of prostaglandins in this model, mice were dosed, via surgically implanted minipumps, with either vehicle, PGE2 (1.32 μg/h), or the prostacyclin analog iloprost (0.33 μg/h) beginning 7 days before or 14 days after bleomycin administration. Endpoints assessed at 7 days after bleomycin administration included proinflammatory cytokine levels and measurement of cellular infiltration into the lung. Endpoints assessed at 21 days after bleomycin administration included lung function assessment via invasive (FlexiVent) analysis, cellular infiltration, lung collagen content, and semiquantitative histological analysis of the degree of lung fibrosis (Ashcroft method). Seven days after bleomycin administration, lymphocyte numbers and chemokine C-C motif ligand 2 expression were significantly lower in PGE2- and iloprost-treated animals compared with vehicle-treated controls (P < 0.05). When administered 7 days before bleomycin challenge, PGE2 also protected against the decline in lung static compliance, lung fibrosis, and collagen production that is associated with 3 wk of bleomycin exposure. However, PGE2 had no therapeutic effect on these parameters when administered 14 days after bleomycin challenge. In summary, PGE2 prevented the decline in lung static compliance and protected against lung fibrosis when it was administered before bleomycin challenge but had no therapeutic effect when administered after bleomycin challenge. [ABSTRACT FROM AUTHOR]

AbstractAim:To test the hypothesis that the epoxyeicosatrienoic acid (EET)-induced transactivation of EGF-R depends on the activation of metalloproteinases and the subsequent release of HB-EGF in cancer cells.Methods:Exogenous 14,15-EET were added to four human-derived cancer cell lines Tca-8113, A549, HepG2, and MDA-MB-231, or these same cell lines were transfected with a mutant CYP epoxygenase (CYP102 F87V, an active 14,15-epoxygenase). The effects of elevated EET levels on the phosphorylation of tyrosine residues in the EGF receptor and on ERK1/2 activation were then assessed.Results:Both the addition of 14,15-EET and the transfection of cells with CYP102 F87V markedly increased the phosphorylation of the tyrosine residues of EGF-R and ERK1/2, an effect that was blocked by a selective EGF-R tyrosine kinase inhibitor (tyrphostin AG1478), a broad-spectrum metalloproteinase inhibitor (1,10-phenanthroline), and an inhibitor of HB-EGF release (CRM197) in Tca-8113 cells. In addition, AG1478, 1,10-phenanthroline, and CRM197 also inhibited the tyrosine phosphorylation of EGF-R and ERK1/2 that was induced by 14,15-EET in the A549, HepG2, and MDA-MB-231 cell lines.Conclusion:These results suggest that the EET-induced transactivation of EGF-R depends on activation of metalloproteinases and the subsequent release of HB-EGF in cancer cell lines. [ABSTRACT FROM AUTHOR]