In:
BMC Microbiology, Springer Science and Business Media LLC, Vol. 7, No. 1 ( 2007-12)
Abstract:
Legionella pneumophila is a facultative intracellular bacterium, capable of replicating within the phagosomes of macrophages and monocytes, but little is known about its interaction with human lung epithelial cells. We investigated the effect of L. pneumophila on the expression of interleukin-8 (IL-8) in human A549 alveolar and NCI-H292 tracheal epithelial cell lines. Results Infection of L. pneumophila strain, but not heat-killed strain, resulted in upregulation of IL-8. IL-8 mRNA expression was induced immediately after the infection and its signal became gradually stronger until 24 h after infection. On the other hand, IL-8 expression in A549 cells infected with L. pneumophila lacking a functional type IV secretion system was transient. The IL-8 expression was slightly induced at 16 h and increased at 24 h after infection with flagellin-deficient Legionella . Activation of the IL-8 promoter by L. pneumophila infection occurred through the action of nuclear factor-κB (NF-κB). Transfection of dominant negative mutants of NF-κB-inducing kinase, IκB kinase and IκB inhibited L. pneumophila -mediated activation of IL-8 promoter. Treatment with hsp90 inhibitor suppressed L. pneumophila -induced IL-8 mRNA due to deactivation of NF-κB. Conclusion Collectively, these results suggest that L. pneumophila induces activation of NF-κB through an intracellular signaling pathway that involves NF-κB-inducing kinase and IκB kinase, leading to IL-8 gene transcription, and that hsp90 acts as a crucial regulator in L. pneumophila -induced IL-8 expression, presumably contributing to immune response in L. pneumophila . The presence of flagellin and a type IV secretion system are critical for Legionella to induce IL-8 expression in lung epithelial cells.
Type of Medium:
Online Resource
ISSN:
1471-2180
DOI:
10.1186/1471-2180-7-102
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2007
detail.hit.zdb_id:
2041505-9
SSG:
12
