title: Involvement of phospholipase A2 in Pseudomonas aeruginosa-mediated PMN transepithelial migration.
abstract: Inflammation resulting from bacterial infection of the respiratory mucosal surface during pneumonia and cystic fibrosis contributes to pathology. A major consequence of the inflammatory response is recruitment of polymorphonuclear cells (PMNs) to the infected site. To reach the airway, PMNs must travel through several cellular and extracellular barriers, via the actions of multiple cytokines, chemokines, and adhesion molecules. Using a model of polarized lung epithelial cells (A549 or Calu-3) grown on Transwell filters and human PMNs, we have shown that Pseudomonas aeruginosa induces PMN migration across lung epithelial barriers. The process is mediated by epithelial production of the eicosanoid hepoxilin A(3) (HXA(3)) in response to P. aeruginosa infection. HXA(3) is a PMN chemoattractant metabolized from arachidonic acid (AA). Given that release of AA is believed to be the rate-limiting step in generating eicosanoids, we investigated whether P. aeruginosa infection of lung epithelial cells resulted in an increase in free AA. P. aeruginosa infection of A549 or Calu-3 monolayers resulted in a significant increase in [(3)H]AA released from prelabeled lung epithelial cells. This was partially inhibited by PLA(2) inhibitors ONO-RS-082 and ACA as well as an inhibitor of diacylglycerol lipase. Both PLA(2) inhibitors dramatically reduced P. aeruginosa-induced PMN transmigration, whereas the diacylglycerol lipase inhibitor had no effect. In addition, we observed that P. aeruginosa infection caused an increase in the phosphorylation of cytosolic PLA(2) (cPLA(2)), suggesting a mechanism whereby P. aeruginosa activates cPLA(2) generating free AA that may be converted to HXA(3), which is required for mediating PMN transmigration.
authors.affiliation: Mucosal Immunology Laboratories, Massachusetts General Hospital, 3503 Charlestown, MA 02129, USA. Bphurley@partners.org
authors.forename: Bryan P
authors.initials: BP
authors.lastname: Hurley
authors.forename: Natecia L
authors.initials: NL
authors.lastname: Williams
authors.forename: Beth A
authors.initials: BA
authors.lastname: McCormick
mesh_terms: D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D016718:Arachidonic Acid / Q000378:metabolism; D002460:Cell Line; D016764:Cell Polarity; D002630:Chemotactic Factors / Q000096:biosynthesis; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D054513:Group IV Phospholipases A2; D006801:Humans; D008168:Lung / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020556:Neutrophil Infiltration / Q000187:drug effects; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054467:Phospholipases A2; D010766:Phosphorylation; D011552:Pseudomonas Infections / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D002630:Chemotactic Factors; D004791:Enzyme Inhibitors; D016718:Arachidonic Acid; C038243:8-hydroxy-11,12-epoxyeicosa-5,9,14-trienoic acid; D010741:Phospholipases A; D054513:Group IV Phospholipases A2; D054467:Phospholipases A2; D015126:8,11,14-Eicosatrienoic Acid