Effect of baicalin on expression of TLR4 in RAW264.7 cells infected by ESBLs Escherichia coli / 中国中药杂志

ABSTRACT

<p><b>OBJECTIVE</b>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.</p><p><b>METHOD</b>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).</p><p><b>RESULT</b>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.</p><p><b>CONCLUSION</b>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.</p>