[Effect of baicalin on expression of TLR4 in RAW264.7 cells infected by ESBLs Escherichia coli].
OBJECTIVE
To investigate the effect and mechanism of baicalin against beta-lactamases Escherichia coli (ESBLs E. coli) mediated by toll-like receptor 4 (TLR4) signal transduction pathway.


METHODS
The RAW264. 7 cells monolayer pretreated with different concentration of baicalin were inoculated with ESBLs E. coli. The expression of TLR4 mRNA and protein were analyzed by semi-quantitative RT-PCR and Immunofluorescence, respectively. The activity of NF-kappaB was detected by Western blot using total cellular protein. The production of TNF-alpha in supernatant was determined by enzyme linked immunosorbnent assay (ELISA).


RESULTS
ESBLs E. coli significantly up-regulated the expression levels of TLR4 mRNA and protein in a time-dependent manner, induced the activation of NF-KB in RAW264. 7, enhanced the production of TNF-alpha in supernatant. Baicalin down-regulated the expression of TLR4 mRNA and protein, decreased the activation of NF-KB in RAW264. 7 cells and reduced the production of TNF-alpha in supernatant in a dose-dependent manner.


CONCLUSIONS
Baicailin could inhibit TLR4 signal transduction pathway. The mechanism of baicalin against ESBLs E. coli may be through inhibiting the expression of TLR4 and its signal transduction pathway.
School of Integrated Chinese and Western Medicine, Anhui University of Traditional Chinese Medicine, Hefei 230038, China. zkdyy0101@163.com
Yun
Y
Yun
Chang-Zhong
CZ
Wang
Li
L
Gui
Zhen-Xing
ZX
Li
D000818:Animals; D002460:Cell Line; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D005419:Flavonoids / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D051379:Mice; D051197:Toll-Like Receptor 4 / Q000235:genetics* / Q000276:immunology
D005419:Flavonoids; D051197:Toll-Like Receptor 4; C038044:baicalin