奶牛乳腺炎主要病原菌对乳腺纤维化重要细胞生长因子及其受体表达作用的研究

(限3000 Characters)：There are more than 20 kinds of common pathogenic bacteria causing bovine mastitis, and Staphylococcus aureus, Streptococcus, and Escherichia coli are major etiologic agents in bovine mastitis in most regions. Bovine mastitis always causes bovine mammary fibrosis, and makes cows eliminated from herd. The project is based on the completed study- - - - The Role of important cytokines in Bovine Mammary fibrosis. We plan to study the effect of the expression of the TGF-β, bFGF and PDGF; the expression of the TβR, bFGFR and PDGFR in bovine mammary epithelial cells and fibroblasts invaded by the main pathogenic bacteria including Staphylococcus aureus, Streptococcus, Escherichia coli in the bovine mastitis in this project, and to study the toll-like receptor expression and its signal transduction pathway in the bovine mammary gland epithelial cells and fibroblasts do by the three kinds of bacteria in vitro, as well as to study the affect of TLRs signaling tranduction pathways for the expression of the three kinds of cell growth factors.Through this project, we will clarify the relation between the main pathogenic bacteria of bovine mastitis and the expression of the several cell growth factor related to mammary gland fibrosis and their receptors . We will clear the role of TLRs signaling pathways for the expression of cell growth factors in bovine mammary gland epithelial cells and fibroblasts invaded by the main pathogenic bacteria causing bovine mastitis. The project further identifies the development process of bovine mammary fibrosis and the pathogenesis. It also provides a foundation for the research of new method and new drug of preventing and controlling bovine mammary fibrosis.

(限400字)：奶牛乳腺炎的常见病原菌有20多种，但多数地区以金黄色葡萄球菌、链球菌和大肠杆菌感染为主。乳腺炎常引起乳腺组织发生纤维化，并导致奶牛淘汰。本项目在已结题的"奶牛乳腺纤维化几种重要细胞因子作用的研究"的基础上，拟通过奶牛乳腺炎几种主要病原菌（金黄色葡萄球菌、链球菌、大肠杆菌）对体外培养的奶牛乳腺上皮细胞和成纤维细胞的作用，探讨奶牛乳腺炎主要病原菌对奶牛乳腺上皮细胞和成纤维细胞TGF-β、bFGF和PDGF及其受体表达的作用，以及对奶牛乳腺上皮细胞和成纤维细胞Toll样受体表达和其信号转导途径的影响，以阐明奶牛乳腺炎主要病原菌与乳腺上皮细胞和成纤维细胞纤维化相关细胞生长因子表达、Toll样受体表达和信号转导途径、生长因子受体表达的相互关系，进一步明确奶牛乳腺纤维化的发生发展过程和发病机理，为奶牛乳腺纤维化防治的新方法和新药物研究提供依据。

病原菌引起的奶牛乳腺炎可导致乳腺纤维化，研究奶牛乳腺纤维化的分子机制具有重要意义。本研究通过S.aureus、S. agalactiae和E.coli作用于体外培养的奶牛乳腺细胞，以及S.aureus诱导的小鼠乳腺纤维化模型，检测相关生长因子及其信号通路的相关受体和转录因子。研究表明：（1）S.aureus能促进奶牛乳腺上皮细胞和成纤维细胞TGF-β1、bFGF、PDGF-BB与其受体以及TLR2和TLR4表达； TLRs-NF-κB和TLRs-AP-1信号转导通路在S.aureus诱导TGF-β1、bFGF和PDGF-BB的表达有重要作用。（2）TGF-β1、PDGF-BB和bFGF作用BMFB后可以促进PI3K和Akt的表达，PI3K/Akt信号通路在TGF-β1、PDGF-BB和bFGF促进α-SMA mRNA转录和COL Ⅰα1的表达具有作用。（3）S.aureus感染小鼠乳腺，能诱导乳腺组织间质的巨噬细胞、上皮细胞、成纤维细胞表达TGF-β1、PDGF-BB、bFGF及受体TβRI、PDGFRβ、FGFR2。TLR2/4-NF-κBp65、TLR2/4-AP-1c-jun信号通路在奶牛乳腺炎S.aureus诱导小鼠乳腺纤维化过程中发挥重要作用。（4）S. agalactiae能促进BMFB的TGF-β1、bFGF、PDGF-BB及其受体的表达，同时也能促进TLR2、TLR4、NF-κB和AP-1蛋白的表达；S. agalactiae促进BMFB Leptin及其长型受体（OB-Rb）的mRNA和蛋白以及α-SMA、COLⅠα1和HA表达量升高，瘦素及其受体OB-Rb升高水平与α-SMA、COLⅠα1和HA升高的趋势基本一致。（5）E.coli促进BMEC和BMFB TGF-β1、bFGF和PDGF及其受体以及TLR2、TLR4的mRNA及蛋白的表达， E.coli促进BMEC和BMFB NF-κB和AP-1的蛋白表达，提示E.coli促进BMEC和BMFB表达促纤维化细胞因子可能与NF-κB和AP-1信号转导通路的激活有关。