Pseudomonas aeruginosa elastase stimulates ERK signaling pathway and enhances IL-8 production by alveolar epithelial cells in culture.
OBJECTIVE
Bacterial products as well as the host airway inflammatory responses contribute to the pathogenesis of Pseudomonas infections. We sought to determine if Pseudomonas elastase (PE) induces mitogen-activated protein (MAP) kinase activity in association with interleukin-8 (IL-8) production by alveolar epithelial cells.


METHODS
We utilized Western blot analysis to detect phosphorylation of signaling intermediates and ELISA was used to measure IL-8 production.


RESULTS
We found that PE induces phosphorylation of the extracellular signal-regulated (ERK1/2) proteins of the MAPK pathway in A549 epithelial cells. Similar results were obtained using primary cultures of rabbit alveolar type II epithelial cells. PE also enhanced IL-8 production, which was abolished in the presence of the ERK activation inhibitor U0126.


CONCLUSIONS
We conclude that PE activates the ERK1/2 arm of the MAPK pathway and that activation of this pathway results in enhanced IL-8 production. The results demonstrate that PE may augment pulmonary inflammation via cellular signaling that regulates expression of IL-8.
Azghani
A O
AO
The University of Texas Health Center, Department of Specialty Care Services, 119 37 US Highway 271, Tyler, Tx 75708, USA. ali.azghani@uthct.edu
Baker
J W
JW
Shetty
S
S
Miller
E J
EJ
Bhat
G J
GJ
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis*; D010196:Pancreatic Elastase / Q000494:pharmacology*; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011817:Rabbits; D015398:Signal Transduction / Q000187:drug effects*; D013268:Stimulation, Chemical
D016209:Interleukin-8; D020928:Mitogen-Activated Protein Kinases; D017027:Protein Tyrosine Phosphatases; D010196:Pancreatic Elastase