[K. pneumoniea endotoxin induced mice beta-defensin-4 mRNA expression and its signaling transduction].
OBJECTIVE
To investigate the in vivo effects of Klebsiella pneumoniae endotoxin(LPS) on beta-defensin expression and the relevant signaling transduction pathway.


METHODS
A LPS tolerant mouse C3H/HeJ with a point mutation at Toll-like receptor-4 (TLR4) gene and its wild type strain C3H/HeN were used in this study. C3H/HeJ and C3H/HeN were injected with 4 mg/kg of LPS intraperitoneally. The tracheas, lungs and kidneys of the C3H/HeJ and C3H/HeN were collected respectively at different LPS-treated time points, and the total RNA of each sample was extracted. The expression of mice beta-defensin-3 and/or beta-defensin-4 mRNA in these tissues was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The sequence of cDNA amplified from the lung of C3H/HeN treated by LPS for 24 h was analyzed. By using western blot, p-I kappa B alpha (phosphorylated I kappa B alpha) and I kappa B alpha of in the lungs of C3H/HeJ and C3H/HeN were detected at different time points after treatment with LPS or without LPS.


RESULTS
1. beta-defensin-4 mRNA was detected in the lungs of C3H/HeN after 24 h treatment with LPS. In contrast, no signal was determined in C3H/HeJ mice with LPS treatment and the C3H/HeN mice without LPS treatment. 2. Compared with the control, increas of the p-I kappa B alpha was observed in the lungs of C3H/HeN at 4 h after treatment with LPS, while both the p-I kappa B alpha and I kappa B alpha contents showed a tendency to go down at 8 h after treatment and dramatically decreased at 24 h. But there were no changes in the of p-I kappa B alpha and I kappa B alpha content the lungs of C3H/HeJ under the same conditions.


CONCLUSIONS
K. pneumoniea endotoxin could induce the expression of beta-defensin-4 mRNA in the lung of C3H/HeN, and TLR4-mediated NF-kappa B activation signaling pathway may be responsible for this event.
Cai
S
S
Research Unit of Infection and Immunity, School of Basic Medical Sciences, WCUMS, Chengdu 610041, China.
Du
J
J
Chen
X
X
Huang
N
N
Wang
L
L
Ma
X
X
Kiyoyuki
K
K
Fumihiko
N
N
Wang
B
B
Takaiki
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D007711:Klebsiella pneumoniae; D008070:Lipopolysaccharides; D008168:Lung / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D023083:beta-Defensins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics
D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D023083:beta-Defensins