title: Mechanism of fibroblast inflammatory responses to Pseudomonas aeruginosa elastase.
abstract: Receptor tyrosine kinases, including the epidermal growth factor receptors (EGFR), are able to activate the mitogen-activated protein kinases (MAPK) via several adaptor proteins and protein kinases such as Raf. EGFR can be activated by a variety of extracellular stimuli including neutrophil elastase, but we are aware of no report as to whether Pseudomonas aeruginosa produced elastase (PE) could elicit such signalling through EGFR activation. We sought to test the inference that PE modulates inflammatory responses in human lung fibroblasts and that the process occurs by activation of the EGFR/MAPK pathways. We utilized IL-8 cytokine expression as a pathway-specific end point measure of the fibroblast inflammatory response to PE. Western blot analysis was performed to detect phosphorylation of EGFR and signal transduction intermediates. Northern blot, real-time PCR, and ELISA methods were utilized to determine cytokine gene expression levels. We found that PE induces phosphorylation of the EGFR and the extracellular signal-regulated proteins (ERK1/2) of the MAPK pathway, and nuclear translocation of NF-κB. Furthermore, enzymically active PE enhances IL-8 mRNA and protein secretion. Pretreatment of the cells with specific inhibitors of EGFR, MAPK kinase and NF-κB markedly attenuated the PE-induced signal proteins phosphorylation and IL-8 gene expression and protein secretion. Collectively, the data show that PE produced by Pseudomonas aeruginosa can modulate lung inflammation by exploiting the EGFR/ERK signalling cascades and enhancing IL-8 production in the lungs via NF-κB activation.
authors.affiliation: Department of Biology, University of Texas at Tyler, Tyler, TX, USA.
authors.forename: Ali O
authors.initials: AO
authors.lastname: Azghani
authors.affiliation: Department of Biology, University of Texas at Tyler, Tyler, TX, USA.
authors.forename: Kourtney
authors.initials: K
authors.lastname: Neal
authors.affiliation: Department of Cellular and Molecular Biology and Texas Lung Injury Institute, University of Texas Health Science Center at Tyler, Tyler, TX, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Idell
authors.affiliation: Department of Pediatric Pulmonology, University of Texas Health Science Center at Tyler, Tyler, TX, USA.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Amaro
authors.affiliation: Program in Environmental and Earth Sciences, University of Texas at Arlington, Arlington, TX, USA.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Baker
authors.affiliation: Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, Canada.
authors.forename: Abdelwahab
authors.initials: A
authors.lastname: Omri
authors.affiliation: Department of Cellular and Molecular Biology and Texas Lung Injury Institute, University of Texas Health Science Center at Tyler, Tyler, TX, USA.
authors.forename: Usha R
authors.initials: UR
authors.lastname: Pendurthi
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008666:Metalloendopeptidases / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D021381:Protein Transport; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D016207:Cytokines; D016209:Interleukin-8; D016328:NF-kappa B; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D008666:Metalloendopeptidases; C043859:pseudolysin, Pseudomonas aeruginosa