Effect of Mycoplasma pneumoniae lysate on interleukin-8 gene expression in human respiratory epithelial cells.
OBJECTIVE
Mycoplasma pneumoniae is a common cause of lower respiratory disease. Several studies have suggested that respiratory infection by M pneumoniae is associated with reactive airway disease and asthma. Interleukin (IL)-8 has been suggested to have a role in the pathogenesis of the allergic inflammation of bronchial asthma, and is well known to be expressed in bronchial epithelial cells.


METHODS
An examination was carried out into the effect of M pneumoniae lysate (MPL) and the role of mitogen-activated protein kinases (MAPKs) and extracellular signal-regulated kinase (ERK) on IL-8 expression in human lung epithelial cells. A549 cells were seeded at a density of 5 x 10(4) cells per well and incubated in basal medium for a further 24 h. IL-8 levels were determined by an enzyme-linked immunosorbent assay. MAPK phosphorylation was assessed by Western blotting.


RESULTS
In A549 cells, MPL induced IL-8 release in a time- and dose-dependent manner. Pretreatment with PD 98059, which blocks the activation of MAPK/ERK kinase 1, inhibited MPL-induced IL-8 production by 64.4% at 25 micromol/L. Stimulation of A549 cells by MPL also caused an increase in the activity of ERK, compared with the nonstimulated cells. The MPL stimulation had no effect on the activities of p38.


CONCLUSIONS
These observations suggest that activation of ERK by MPL may be one of the mechanisms that result in an increase of the production of IL-8.
Department of Pediatrics, Yonsei University College of Medicine, Youngdong Severance Hospital, PO Box 1217, Seoul 135-270, Korea.
Myung Hyun
MH
Sohn
Kyung Eun
KE
Lee
Sung Yon
SY
Choi
Byoung Chul
BC
Kwon
Myung Woong
MW
Chang
Kyu-Earn
KE
Kim
D015153:Blotting, Western; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics* / Q000378:metabolism; D008168:Lung / Q000378:metabolism*; D048748:MAP Kinase Kinase Kinase 3 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009177:Mycoplasma pneumoniae / Q000201:enzymology*; D010766:Phosphorylation; D011014:Pneumonia / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016209:Interleukin-8; D020928:Mitogen-Activated Protein Kinases; D048748:MAP Kinase Kinase Kinase 3