老年小鼠CD11b^＋GR-1^＋髓源性抑制细胞免疫功能特点及机制研究

Study on characteristics and immune mechanisms of CD11b^＋GR-1^＋ myeloid-derived suppressor cells in elderly mice

目的 以健康青年小鼠为对照,探讨健康老年小鼠CD11b^＋ GR 1^＋髓源性抑制细胞（MDSCs）免疫功能特点及机制. 方法 随机选取健康C57BL/6青年鼠（1～2月龄）和老年鼠（＞18月龄）各20只,采用免疫磁珠分选法获得足量健康青年鼠、老年鼠脾脏CD11b＋ GR-1＋ MDSCs,运用溴脱氧尿嘧啶核苷-酶联免疫吸附实验（BrdU Elisa）测定青年鼠、老年鼠CD11b^＋ GR-1^＋ MDSCs对T细胞增殖的影响.通过Transwcll小室共培养实验及实时荧光定量PCR法检测青年鼠、老年鼠CD11b^＋ GR 1^＋ MDSCs免疫抑制功能的差异. 结果 与青年鼠比较,老年鼠MDSCs能明显抑制T细胞增殖（t=8.67,P＜0.001）,而这一作用可被Transwell明显逆转（t=6.93,P＜0.001）;与青年鼠比较,老年鼠MDSCs的精氨酸酶-1、诱导型一氧化氮合成酶、活性氧、白介素-10、白介素-13和转化生长因子-β基因表达量明显增高（t值分别为9.04、4.86、7.04、6.92、4.51、5.46,P＜0.05或P＜0.01）. 结论 健康老年小鼠CD11b^＋ GR-1^＋ MDSCs可通过细胞-细胞间接触抑制和分泌免疫抑制性介质两种途径显著抑制T细胞增殖.

Objective To study characteristics and immune mechanisms of CD11b^＋ GR-1^＋ myeloid-derived suppressor cells （CD11b^＋ GR 1^＋ MDSCs） in elderly mice,as compared with those of healthy young mice.Methods Totally 20 healthy C57BL/6 young mice （aged 1-2 months） and 20 elderly mice （aged over 18 months） were randomly chosen and splenetic CD11b^＋ GR-1^＋ MDSCs were sorted with the MDSCs Isolation Kit.In vitro assays,the effects of young and elderly CD1 1b^＋ GR-1^＋ MDSCs on the proliferation of T cells were determined by Brdu Elisa.Transwell co-culture and real-timePCR were used to identify the mechanisms of different immune suppressive functions of CD11b＋GR 1＋ MDSCs sorted from young mice and elderly mice.Results Compared with young MDSCs,elderly MDSCs could evidently suppress the proliferation of T cells （t=8.67,P〈0.001）,and this function could be reversed by trans-well co-culture （t=6.93,P〈0.001）.The results of realtime PCR revealed that,compared with young MDSCs,elderly MDSCs expressed higher levels of arginase-1 （ARG-1）,inducible nitric oxide synthase （iNOS）,reactive oxygen species （ROS）,interleukin 10 （IL-10）,IL13 and transforming growth factor （TGF）-β （t=9.04,4.86,7.04,6.92,4.51,5.46,respectively,P〈0.05 or P〈0.01）.Conclusions CD11b^＋GR-1^＋ MDSCs sorted from healthy elderly mice can evidently suppress the proliferation of T cells through cell-cell contact and secretion of suppressive medium.