CD226调控自然杀伤细胞参与小鼠肥胖的作用机制研究

Mechanism of CD226-dependant NK cell regulation in mouse obesity

目的观察CD226基因敲除(KO)对高脂饲养的肥胖小鼠相关指标的影响,分析CD226KO肥胖小鼠脾脏各主要免疫细胞的构成,探讨CD226分子参与高脂饮食诱导肥胖的免疫学机制。方法野生型(WT)和CD226KO小鼠随机分为高脂和正常饮食两组,饲喂14周,建立2型糖尿病模型。通过流式细胞术分析小鼠脾脏及外周血的免疫细胞构成。体外试验使用pshRNA-CD226慢病毒感染NK92-MI细胞,qPCR法检测Foxp3、TNF-α及IFN-γ表达水平。结果CD226KO可以降低肥胖小鼠血糖水平和血清胰岛素含量,下调胰岛素抵抗指数(HOMA-IR),上调胰岛素敏感指数(HOMA-IS);减少胰岛组织的代偿性增生,上调胰岛β细胞功能指数(HOMA-β);CD226KO显著降低小鼠脾脏NK细胞比例;但CD3^- CD49b^+ CD25^+ Foxp3^+调节性NK细胞(NKreg)比例明显增加。敲除CD226可以显著上调NK92-MI细胞Foxp3表达,下调TNF-α及IFN-γ表达。结论CD226KO减轻肥胖小鼠胰岛素抵抗,提高胰岛β细胞数量及功能;其作用机制可能与上调Foxp3^+ NKreg比例相关。

Objective To investigate the effects of CD226 knockout(KO)on obese mice fed with high fat diet and to analyze the composition of immune cells in CD226KO obese mice for further elucidating the immunological mechanism of CD226 involved in high fat diet-induced obesity.Methods Both wild-type(WT)and CD226KO mice were randomly divided into two groups,high-fat and normal diet groups,and fed for 14 weeks to establish the type 2 diabetes model.Immune cells in mouse spleen and peripheral blood were analyzed by flow cytometry.In in vitro experiments,NK92-MI cells were infected with pshRNA-CD226 lentivirus to silence CD226 expression,and then qPCR was performed to detect the expression of Foxp3,TNF-α and IFN-γ at mRNA level.Results In the high-fat diet groups,CD226KO mice had lower blood glucose,serum insulin and HOMA-IR than WT mice,but higher HOMA-IS and HOMA-β.CD226KO could reduce compensatory hyperplasia of islet tissue,and significantly down-regulate the proportion of spleen NK cells in mice.The proportion of CD3^- CD49b^+ CD25^+ Foxp3^+ regulatory NK cells(NKreg)increased significantly in CD226KO mice.CD226KO could significantly increase Foxp3 expression in NK92-MI cells and decrease the expression of TNF-α and IFN-γ.Conclusions CD226KO can alleviate insulin resistance,increase the number of islet β-cell and improve islet β-cell function in obese mice.The mechanism might be related to the up-regulation of Foxp3^+ NKreg ratio.