Integrins are a large family of adhesion receptors that are known to be key signaling molecules in both physiological and pathological processes. Previous studies have demonstrated that the expression of integrin receptors in the pulmonary epithelium can change under various pathological conditions, such as injury, inflammation, or malignant transformation. We hypothesize that integrin expression can be altered by stimulation of lung epithelial cells with an opportunistic bacterial pathogen Pseudomonas aeruginosa. Using the A549 adenocarcinoma cell line that expressed a low level of several integrin subunits we have demonstrated that P. aeruginosa infection in vitro caused a rapid up-regulation of α5, αv, β1, and β4 integrins at both the mRNA and protein level. Neither heat-killed P. aeruginosa strain PAK nor its live isogenic mutants lacking pili or lipopolysaccharide (LPS) core oligosaccharide showed any effect on integrin expression in A549 cells as compared to the use of the wild-type PAK strain. These results establish that up-regulation of integrin expression is dependent on the internalization of live bacteria possessing intact pili and LPS. Gene silencing of integrin-linked kinase in A549 cells caused a significant decrease in the release of proinflammatory cytokines in response to P. aeruginosa stimulation. Although further studies are warranted towards understanding the precise role of integrin receptors in prominent inflammation caused by P. aeruginosa, our findings suggest a possibility of using specific integrin inhibitors for therapy of pulmonary inflammatory conditions caused by pathogenic micro-organisms.
Arnaout MA, Mahalingam B., Xiong JPIntegrin structure, allostery, and bidirectional signaling. Annu Rev Cell Dev Biol2005; 21: 381-410.
2.
Sheppard D.Functions of pulmonary epithelial integrins: from development to disease. Physiol Rev2003; 83: 673-686.
3.
Pilewski JM, Latoche JD, Arcasoy SM, Albelda SMExpression of integrin cell adhesion receptors during human airway epithelial repair in vivo. Am J Physiol1997; 273: L256-L263.
4.
Adachi M., Taki T., Higashiyama M., Kohno N., Inufusa H., Miyake M.Significance of integrin alpha5 gene expression as a prognostic factor in node-negative non-small cell lung cancer. Clin Cancer Res2000; 6: 96-101.
5.
Oshita F., Kameda Y., Hamanaka N. et al. High expression of integrin beta1 and p53 is a greater poor prognostic factor than clinical stage in small-cell lung cancer. Am J Clin Oncol2004; 27: 215-219.
Wang B., Li S., Southern PJ, Cleary PPStreptococcal modulation of cellular invasion via TGF-beta1 signaling. Proc Natl Acad Sci USA2006; 103: 2380-2385.
8.
Crouch Brewer S., Wunderink RG, Jones CB, Leeper Jr KVVentilator-associated pneumonia due to Pseudomonas aeruginosa. Chest1996; 109: 1019-1029.
9.
Berghmans T. , Sculier JP, Klastersky J.A prospective study of infections in lung cancer patients admitted to the hospital. Chest2003; 124: 114-120.
10.
Saiman L., Siegel J.Infection control in cystic fibrosis. Clin Microbiol Rev2004; 17: 57-71.
11.
Lieberman D. , Lieberman D.Pseudomonal infections in patients with COPD: epidemiology and management. Am J Respir Med2003; 2: 459-468.
12.
Pasloske BL , Finlay BB, Paranchych W.Cloning and sequencing of the Pseudomonas aeruginosa PAK pilin gene. FEBS Lett1985; 183: 408-412.
13.
Rahim R., Burrows LL, Monteiro MA, Perry MB, Lam JSInvolvement of the rml locus in core oligosaccharide and O polysaccharide assembly in Pseudomonas aeruginosa. Microbiology2000; 146: 2803-2814.
14.
Wang B., Yurecko RS, Dedhar S., Cleary PPIntegrin-linked kinase is an essential link between integrins and uptake of bacterial pathogens by epithelial cells. Cell Microbiol2006; 8: 257-266.
15.
Chi E., Mehl T., Nunn D., Lory S.Interaction of Pseudomonas aeruginosa with A549 pneumocyte cells. Infect Immun1991; 59: 822-828.
16.
Regueiro V. , Campos MA, Pons J., Alberti S., Bengoechea JAThe uptake of a Klebsiella pneumoniae capsule polysaccharide mutant triggers an inflammatory response by human airway epithelial cells. Microbiology2006; 152: 555-566.
17.
Greene CM, Carroll TP, Smith SG et al. TLR-induced inflammation in cystic fibrosis and non-cystic fibrosis airway epithelial cells. J Immunol2005; 174: 1638-1646.
18.
Ramphal R., Koo L., Ishimoto KS, Totten PA, Lara JC, Lory S.Adhesion of Pseudomonas aeruginosa pilin-deficient mutants to mucin. Infect Immun1991; 59: 1307-1311.
19.
Saiman L., Prince A.Pseudomonas aeruginosa pili bind to asialoGM1 which is increased on the surface of cystic fibrosis epithelial cells. J Clin Invest1993; 92: 1875-1880.
20.
Feldman M., Bryan R., Rajan S. et al. Role of flagella in pathogenesis of Pseudomonas aeruginosa pulmonary infection. Infect Immun1998; 66: 43-51.
21.
Gupta SK, Berk RS, Masinick S., Hazlett LDPili and lipopolysaccharide of Pseudomonas aeruginosa bind to the glycolipid asialo GM1. Infect Immun1994; 62: 4572-4579.
22.
Adamo R., Sokol S., Soong G., Gomez MI, Prince A.Pseudomonas aeruginosa flagella activate airway epithelial cells through asialoGM1 and Toll-like receptor 2 as well as Toll-like receptor 5. Am J Respir Cell Mol Biol2004; 30: 627-634.
23.
DiMango E., Zar HJ, Bryan R., Prince A.Diverse Pseudomonas aeruginosa gene products stimulate respiratory epithelial cells to produce interleukin-8. J Clin Invest1995; 96: 2204-2210.
24.
Hannigan G. , Troussard AA, Dedhar S.Integrin-linked kinase: a cancer therapeutic target unique among its ILK. Nat Rev Cancer2005; 5: 51-63.
25.
Lau GW, Hassett DJ, Britigan BEModulation of lung epithelial functions by Pseudomonas aeruginosa. Trends Microbiol2005; 13: 389-397.
26.
Sadikot RT, Blackwell TS, Christman JW, Prince ASPathogen- host interactions in Pseudomonas aeruginosa pneumonia. Am J Respir Crit Care Med2005; 171: 1209-1223.
27.
Roger P., Puchelle E., Bajolet-Laudinat O. et al. Fibronectin and alpha5beta1 integrin mediate binding of Pseudomonas aeruginosa to repairing airway epithelium. Eur Respir J1999; 13: 1301-1309.
28.
Leroy-Dudal J. , Gagniere H., Cossard E., Carreiras F., Di Martino P.Role of alphavbeta5 integrins and vitronectin in Pseudomonas aeruginosa PAK interaction with A549 respiratory cells. Microbes Infect2004; 6: 875-881.
29.
Barnes RJ, Leung KT, Schraft H., Ulanova M.Chromosomal gfp labelling of Pseudomonas aeruginosa using a mini-Tn7 transposon: application for studies of bacteria-host interactions. Can J Microbiol2008; 54: 48-57.
30.
Valenzuela DM, Groffen J.Four human carcinoma cell lines with novel mutations in position 12 of c-K-ras oncogene. Nucleic Acids Res1986; 14: 843-852.
31.
Pier GBPseudomonas aeruginosa lipopolysaccharide: a major virulence factor, initiator of inflammation and target for effective immunity. Int J Med Microbiol2007; 297: 277-295.
32.
Ichikawa JK , Norris A., Bangera MG et al. Interaction of Pseudomonas aeruginosa with epithelial cells: identification of differentially regulated genes by expression microarray analysis of human cDNAs. Proc Natl Acad Sci USA2000; 97: 9659-9664.
33.
Guillot L., Medjane S., Le-Barillec K. et al. Response of human pulmonary epithelial cells to lipopolysaccharide involves Toll-like receptor 4 (TLR4)-dependent signaling pathways: evidence for an intracellular compartmentalization of TLR4. J Biol Chem2004; 279: 2712-2718.
34.
Speert DP, Loh BA, Cabral DA, Eftekhar F.Opsonin-independent phagocytosis of Pseudomonas aeruginosa. Antibiot Chemother1985; 36: 88-94.
35.
Lee MS, Kim Y-J.Signaling pathways downstream of pattern-recognition receptors and their cross talk. Annu Rev Biochem2007; 76: 13.1-13.34.
36.
Blohmke CJ, Victor RE, Hirschfeld AF et al. Innate immunity mediated by TLR5 as a novel antiinflammatory target for cystic fibrosis lung disease. J Immunol2008; 180: 7764-7773.
37.
Ishibashi Y. , Nishikawa A.Role of nuclear factor-kappa B in the regulation of intercellular adhesion molecule 1 after infection of human bronchial epithelial cells by Bordetella pertussis. Microb Pathog2003; 35: 169-177.
38.
Schmid Y., Grassl GA, Buhler OT, Skurnik M., Autenrieth IB, Bohn E.Yersinia enterocolitica adhesin A induces production of interleukin-8 in epithelial cells. Infect Immun2004; 72: 6780-6789.
39.
Karin M., Delhase M.The I kappa B kinase (IKK) and NF-kappa B: key elements of proinflammatory signalling. Semin Immunol2000; 12: 85-98.
40.
Ulanova M., Puttagunta L., Marcet-Palacios M. et al. Syk tyrosine kinase participates in β1 integrin signaling and inflammatory responses in airway epithelial cells. Am J Physiol2005; 288: L497-L507.
41.
Cho SO, Kim KH, Yoon JH, Kim H.Signaling for integrin alpha5/ beta1 expression in Helicobacter pylori-infected gastric epithelial AGS cells. Ann NY Acad Sci2006; 1090: 298-304.
