克雷伯氏肺炎杆菌内毒素诱导小鼠β-防御素-4基因表达及其信号传递

K.pneumoniea Endotoxin Induced Mice β-defensin-4 mRNA Expression and Its Signaling Transduction

目的 探讨用克雷伯氏肺炎杆菌内毒素 (L PS)对小鼠 β-防御素表达的影响及其相关的信号传导通路。方法 分别给予 C3H /He J和 C3H /He N小鼠腹腔注射 L PS (4mg/kg) ,于不同时间点采取气管、肺、肾等组织 ,提取总 RNA。用 RT- PCR检测各组织β-防御素 - 3和 /或β-防御素 - 4m RNA的表达 ,并对扩增出的 c DNA片段进行测序 ;同步用 Western blot法检测该两系小鼠肺脏 I-κBα磷酸化情况 (p- I-κBα)和 I-κBα的含量。结果 1经L PS处理 2 4小时后的 C3H/He N小鼠 ,其肺脏表达 β-防御素 - 4m RNA 而 C3H/He J小鼠未见表达 ;2与未给予L PS处理小鼠比较 ,经 L PS处理 4小时后 ,C3H/He N小鼠肺组织 p- I- κBα含量明显增高 ;L PS处理后 8小时 ,p- I-κBα以及 I- κBα含量均呈减少趋势 ;至第 2 4小时 ,p- I- κBα和 I- κBα含量均明显减少。而 C3H/He J小鼠肺组织 p- I-κBα及 I- κBα含量均未见相应变化。结论 克雷伯氏肺炎杆菌内毒素能诱导 C3H/He N小鼠肺 β-防御素 - 4的表达 ;其诱导表达作用与 Toll受体蛋白 - 4介导的

Objective To investigate the in vivo effects of Klebsiella pneumoniae endotoxin(LPS) on β 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 4mg/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 β defensin 3 and/or β 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 24h was analyzed. By using western blot, p IκBα(phosphorylated IκBα) and IκBα 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 β defensin 4 mRNA was detected in the lungs of C3H/HeN after 24h 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 IκBα was observed in the lungs of C3H/HeN at 4h after treatment with LPS, while both the p IκBα and IκBα contents showed a tendency to go down at 8h after treatment and dramatically decreased at 24h.But there were no changes in the of p IκBα and IκBα content the lungs of C3H/HeJ under the same conditions. Conclusion K.pneumoniea endotoxin could induce the expression of β defensin 4 mRNA in the lung of C3H/HeN, and TLR4 mediated NF κB activation signaling pathway may be responsible for this event.