M2型巨噬细胞在糖尿病小鼠同种异体胰岛移植中的抗排斥作用

目的：探讨腹膜腔来源的M2型巨噬细胞对糖尿病小鼠同种异体胰岛移植的抗排斥作用。方法：体外分 离诱导C57BL/6小鼠腹膜腔M2型和M0型细胞，流式细胞术鉴定巨噬细胞表型。链脲佐菌素(streptozotocin，STZ)诱导 C57BL/6雄性小鼠的糖尿病模型作为受体，分离BALB/c小鼠胰岛细胞移植于C57BL/6糖尿病小鼠左肾包膜下。将移植 后糖尿病小鼠随机分为3组，每组8只。于胰岛移植术后1，3，7 d分别经尾静脉输注PBS(islet+PBS组)、2.5×106个M0型 巨噬细胞(islet+M0组)，2.5×106个M2型巨噬细胞(islet+M2组)。移植术后取尾静脉血监测受体血糖水平的变化，记录 胰岛存活时间，并于移植后10 d每组随机抽取2只小鼠处死取左肾做病理学检查，观察移植物形态结构和胰岛素表达 水平。结果：Islet+PBS组、islet+M0组和islet+M2组移植物的中位存活时间分别为6.5(4~10)，7.5(4~10)和24(>15) d；与 islet+PBS组和islet+M0组比较，islet+M2组移植物调节血糖正常水平时间和中位存活时间明显延长(P<0.01)。病理学检 查结果显示islet+M2组胰岛移植10 d后移植物结构完整，胰岛素染色阳性；而islet+PBS组和islet+M0组胰岛移植物均被 排斥，胰岛素染色阴性，局部见大量淋巴细胞浸润。结论：腹膜腔来源的M2型巨噬细胞能减轻受体对胰岛移植物的 免疫排斥反应，延长胰岛移植物的存活时间，从而提高受体对血糖的耐受能力。

Effect of M2 macrophage against rejection on islet allografts in diabetic mice

Objective: To explore the possibility of using peritoneal alternatively activated M2 macrophages to prevent rejection aft er islet allotransplantation in a murine model. Methods: Peritoneal monocytes from C57BL/6 mice were induced and modulated to M2 and M0 macrophages in vitro, then the phenotype of macrophage was assessed by fl ow cytometry. C57BL/6 mice were induced diabetic by streptozotocin (STZ) injection and transplanted with islets isolated from BALB/c mice under the left kidney capsule. The recipients were randomly divided to 3 groups (n=8). A total of 2.5×106 M2 macrophages were injected intravenously at 0, 3, 7 d after transplantation in islet+M2 group; 2.5×106 M0 macrophages were injected intravenously at 0, 3, 7 d after transplantation in islet+M0 group; the mice in islet+PBS group were injected with PBS. Blood glucose was monitored after transplantation. On day 10 after transplantation, 2 recipients in each group were randomly selected and sacrificed, and the left kidneys were resected for pathological examination. Results: Achievement of euglycemia was significantly prolonged after islet transplantation in the islet+M2 group than that in the other two groups (P<0.01). The median survival time of islet allografts in the islet+PBS group, the islet+M0 group, and the islet+M2 group were 6.5 (4–10), 7.5 (4– 10), and 24(﹥15) d, respectively. Pathological examination also showed that the grafts in islet+M2 group remained an intact structure with positive insulin stain and no apparent lymphocytes infiltration, while the graft was rejected in other 2 groups with negative insulin stain and massive lymphocytes infiltration. Conclusion: Peritoneal alternatively activated M2 macrophages can prevent rejection after islet allotransplantation, prolong the survival time of islet allografts and enhance the tolerance of the recipient to blood glucose in mice.