金黄色葡萄球菌诱导小鼠乳腺纤维化模型TGF-β1的表达

Expression of TGF-beta 1 in mice mammary gland fibrosis model induced by Staphylococcus aureus

为探究金黄色葡萄球菌(S.aureus)引起乳腺纤维化的致病分子机制,本研究以不同剂量(10~4 cfu/m L、10~6cfu/m L、10~8cfu/m L、10^(10)cfu/m L)的S.aureus感染哺乳期BALB/c小鼠乳腺组织,观察小鼠临床症状和病理组织学变化,筛选建立小鼠乳腺纤维化模型的S.aureus感染剂量。感染小鼠后分别于感染后1 d、3 d、5 d、7 d、14 d、21 d采集小鼠乳腺组织,通过病理组织学观察、免疫组化染色、荧光定量PCR、western blot等方法,研究乳腺纤维化、TGF-β1的表达分布状况,检测TGF-β1的m RNA的转录和蛋白表达水平。结果显示108 cfu/m L S.aureus感染哺乳期小鼠21 d时出现乳腺组织纤维化,确定其为建立小鼠乳腺纤维化模型的感染菌剂量。10~8 cfu/m L S.aureus感染小鼠乳腺组织后,TGF-β1主要由巨噬细胞(感染后1 d、3 d、5 d)、乳腺成纤维细胞(感染后1 d、3 d、5 d、7 d、14 d、21 d)及乳腺上皮细胞(感染后7 d、14 d、21 d)表达;在感染后3 d～7 d时小鼠乳腺组织中TGF-β1的表达先升高后降低,感染后14 d、21 d时其表达再次升高,并显著高于对照组(p<0.01)。本研究表明通过S.aureus感染小鼠乳腺可以建立小鼠乳腺纤维化模型,并能够促进感染后小鼠巨噬细胞、乳腺成纤维细胞、乳腺上皮细胞中TGF-β1的表达,TGF-β1在小鼠乳腺纤维化的发生发展过程中具有重要的促进作用。

To investigate the pathogenic mechanism of mammary gland fibrosis which induced by Staphylococcus aureus, mammary glands of lactating BALB/c mice were infected with S.aureus at 10 4, 10 6, 10 8 , 10 10 cfu/mL, respectively, and the optimum concentration of the bacteria was choosen for establishment of mice mammary gland fibrosis model. Mice were sacrificed at days 1, 3, 5, 7, 14 and 21 days after S.aureus infection and the mammary glands of the mice were collected to make pathological sections. The mammary fibrosis was observed by histopathological, and TGF-β1 in the mammary gland tissue was detected by immunohistochemieal staining, quantitative real-time PCR and western blot. The results indicated that mammary gland fibrosis was established by I0s cfu/mL S.aureus-infected group at 21days post infection. TGF-β1 could be detected in maerophage （1, 3, 5 days）, mammary fibroblasts （1, 3, 5, 7, 14, 21 days） and mammary epithelial cells （7, 14, 21 days）. The expression of TGF-β1 increased in initial stage then declined at 7 days post infection, and increased again from 14 days to 21 days post infection with significant difference compared with the control group （p〈0.01）. The study showed that mammary gland fibrosis model was established by S.aureus-infected lactating mice and TGF-β1 could be induced from macrophages, fibroblasts, mammary epithelial cells, which indicated that TGF-β 1 could play a key role in mammary gland fibrosis in mice