1型糖尿病小鼠肠道潘氏细胞的杀菌功能改变

Changes in bactericidal function of intestinal Paneth cells in type 1 diabetic mice

目的探讨1型糖尿病小鼠肠道潘氏细胞杀菌功能的改变。方法采用腹腔注射链脲菌素的方法诱导1型糖尿病小鼠模型,8周龄小鼠分为正常对照组(Control组)、糖尿病组(UDM组)和糖尿病胰岛素治疗组(IDM组)。采用菌落培养法评估肠道细菌增殖情况及对外来大肠埃希菌的杀灭能力。利用免疫组织化学法和蛋白免疫印迹法检测潘氏细胞内溶菌酶的表达情况。结果与Control组比较,UDM组回肠末端有氧细菌总量增加(UDM组:5.66±0.80 lg CFUs/g,Control组:4.70±0.81 lg CFUs/g,P<0.05),厌氧细菌总量也增加(UDM组:6.71±1.37 lg CFUs/g,Control组:5.25±1.16 lg CFUs/g,P<0.05);UDM组肠上皮每个隐窝内潘氏细胞数目增多(UDM组:5.75±1.00个,Control组:4.46±0.96个,P<0.05),但溶菌酶的蛋白质表达下降。IDM组与Control组比较,潘氏细胞数目、溶菌酶的蛋白质表达、肠道的细菌总量比较差异无统计学意义。结论 1型糖尿病小鼠肠道防御能力下降,与潘氏细胞分泌溶菌酶不足有关,而胰岛素替代治疗可以恢复潘氏细胞溶菌酶的表达及肠道的防御能力。

Objective To investigate the changes in the bactericidal function of intestinal Paneth ceils in type 1 diabetes mellitus （T1DM） mouse models. Methods TIDM mouse models were established by intraperitoneal injection of streptozocin （ STZ ）. The 8-week-aged mice were divided into the control （ Control）, STZ-induced diabetic mice （UDM） and insulin-treated diabetic mice （IDM） groups. Bacterial culture was performed to evaluate the bacterial proliferation in the intestine and the bactericidal ability to eliminate for- eign Escheriehia coli. The expression level of lysozyme in intestinal Paneth cells was detected by immunohistochemistry and western blot. Results Compared to the Control group, the aerobe load of terminal ileum in the UDM group was significantly increased （UDM group： 5.66 ±0. 80 lg CFUs/g, Control group： 4. 70 ±0. 81 lg CFUs/g, P 〈0. 05）, so was the anaerobe load （UDM group： 6. 71 ± 1.37 lg CFUs/g, Control group： 5.25 ± 1.16 lg CFUs/g, P 〈 0. 05 ） and the quantity of Paneth cells in each crypt of intestinal epithelial cells （ UDM group： 5.75 ~ 1.00 per crypt, Control group： 4. 46 ±0. 96 per crypt, P 〈 0. 05）. However, the ex- pression level of lysozyme in the UDM group was decreased compared with that in the control group. No significant difference was noted between the IDM and control groups in terms of the quantity of Paneth cells, the expression level of lysozyme and overall bacterial load in the intestine. Conclusions The intestinal bactericidal function of the T1DM mice was decreased, which may result from the insufficient secretion of lysozyme by the Paneth cells. The insulin treatment can enhance the expression of lysozyme and restore the bactericidal function of the intestine in the TIDM mice.