免疫健全小鼠胰腺癌发生模型的建立及免疫细胞群的变化

Establishment of pancreatic cancerogenesis model in immunocompetent mice and the changes of immune cell populations

目的建立小鼠胰腺癌发生模型并观察外周血及肿瘤组织中免疫细胞群的变化。方法利用致癌剂二甲基苯葸（DMBA）胰腺内原位包埋的方法建立从慢性胰腺炎（chronic pancreatitis，cP）、胰腺导管内瘤变（pancreatic intraepithelial neoplasma，PanlN）到胰腺癌（pancreatic cancer，PC）的发生模型。共建模60只，8周后处死小鼠。随机选择20只存活小鼠，利用流式细胞计数技术（flowcytometry，FCM）检测外周血及胰腺病变组织中7个免疫细胞群的变化。结果建模8周内共死亡14只（23．3％），存活46只。46只小鼠病变胰腺组织均制备石蜡切片行常规HE染色。46个病变组织中，12例CP（26．1％），11例低级别PanIN（low grade—PanlN，PanIN-1，2，LOPanIN）（23．9％），9例高级别PanIN（highgrade—PanlN，PanIN．3，HG-PanIN）（19．6％）及14例PC（30．4％）。随机选择的20只小鼠中，PC及HG—PdnIN小鼠外周血中髓系来源抑制细胞（myeloidde．rivedsuppressorcells．MDSC）明显高于LG．PanIN及CP小鼠。PC及HG—PanlN小鼠胰腺病变组织中粒细胞、MDSC及M2型肿瘤相关巨噬细胞（tumor associated macmphages，TAM）较LG．PanlN及CP小鼠明显升高，而T淋巴细胞及M1型TAM明显减少。结论利用DMBA胰腺内原位包埋是建立小鼠胰腺癌发生模型的简便易行的方法。胰腺癌在发生过程中，伴随全身及局部的免疫抑制效应，以病变组织内尤为明显，其中MDSC及M2型TAM可能起到关键作用。

Objective To establish the pancreatic cancerogenesis model in mice and to observe the changes of the immune cell populations in peripheral blood and pancreatic lesions. Methods The in situ em- bedding of canerogen dimethylbenzanthracene （DMBA） was adopted to estabhsh the pancreatic cancerogenesis process from chronic pancreatitis（CP）, pancreatic intraepithelial neoplasma （PanlN） to pancreatic cancer. Total- ly 60 C57BI/6J mice were used, and 8 weeks after embedding, the mice were killed. 20 mice were randomized selected, and 7 immune cell populations in the peripheral blood and pancreatic lesions were detected by flow cy- tometery（FCM）. Results During the observational peroid of 8 weeks, 14（23.3%） mice died. Among the 46 sur- vivors, 20 mice were randomized selected for FCM analysis. All of the 46 pancreatic lesions were pathologically analyzed. 12 cases were CP（26.1%）, 11 cases were lower grade PanlN （PanlN-1,2, LG-PanlN） （23.9%）, 9 cas- es were high grade PanIN （PanIN-3, HG-PanIN） （19.6%） and 14 cases were PC. Among the 20 randomized selected mice, 4 cases were CP, 7 cases were LG-PanIN, 4 cases were HG-PanlN and 5 cases were PC. The myeloid derived suppressor ceils （MDSC） of HG-PanIN and CP were significantly more than that of LG-PauIN and CP. In the pancreatic lesions, the granulocytes, MDSC and M2 polarized TAM of HG-PanIN and PC were significantly more than that of LG-PanIN and CP. On the contrary, the T lymphocytes and M1 polarized TAM were significantly decreased. Conclusions In situ embedding of DMBA is a feasible and practical method to establish the spontaneous pancreatic cancerogenesis model in the immunocompetent mice. Pancreatic cancerogenesis can induce systemic and even stronger local immunosuppression, and the MDSC and M2 polarized TAM may play the vital roles.