给予卵清蛋白表位内化受体DEC⁃205抗体单链可变区嵌合蛋白(SD)可抑制小鼠食物过敏

Administration of a single chain variable fragments chimeric protein(SD)of ovalbumin epitopes internalizing receptor DEC⁃205 antibody inhibits food allergy in mice

目的研究卵清蛋白(OVA)表位内化受体DEC⁃205抗体单链可变区嵌合蛋白(SD)对小鼠食物过敏的预防性治疗作用及可能的机制。方法基于食物过敏模型,将小鼠随机分为单纯对照组、PBS组、100μg DEC205受体抗体单链可变区(scFv DEC)处理组、50μg SD处理组、100μg SD处理组,每次接触卵清蛋白(OVA)24 h前给予相应处理。激发后评估小鼠腹泻发生情况,测肛温,ELISA检测血清中OVA特异性IgE、IgG1、IgG2a以及白细胞介素4(IL⁃4)水平,HE染色观察空肠组织嗜酸性粒细胞浸润情况,甲苯胺蓝染色观察肥大细胞浸润情况。分离培养未成熟骨髓来源的树突状细胞(BMDC),分别以10 ng/mL脂多糖(LPS)、50 ng/mL胸腺基质淋巴细胞生成素(TSLP)、1000 ng/mL scFv DEC蛋白、(10、100、1000)ng/mL SD蛋白刺激培养24 h,检测上清中IL⁃10水平。结果与PBS组相比,预防性给予SD蛋白,发生腹泻的小鼠数量明显减少,肛温差显著减小,血清OVA特异性IgE、IgG1、IgG2a以及IL⁃4水平显著降低;空肠组织嗜酸性粒细胞和肥大细胞浸润显著减少,SD体外刺激BMDC培养上清IL⁃10水平显著升高。结论SD通过促进树突状细胞的免疫耐受减轻实验性食物过敏反应。

Objective To investigate the preventive therapeutic effect and possible mechanism of single chain variable fragments chimeric protein(SD)of ovalbumin epitopes internalizing receptor DEC⁃205 antibody on food allergy in mice.Methods Mice were randomly divided to five groups(control,PBS,scFv DEC 100μg,SD 50μg,SD 100μg)and treated for 24 hours before OVA administration.After challenge,the serum level of OVA⁃specific IgE,IgG1,IgG2a and IL⁃4 were detected by ELISA.Infiltration of eosinophils and mast cells in the jejunum was observed by HE staining and toluidine blue staining respectively.The bone marrow of tibia and femur was isolated and cultured to obtain immature dendritic cells(BMDCs),which were further treated with LPS(10 ng/mL),TSLP(50 ng/mL),scFv DEC protein(1000 ng/mL)and SD protein(10,100,1000)ng/mL for 24 hours,and the IL⁃10 level of supernatant was assayed by ELISA.Results Compared with PBS group,the number of SD⁃treated mice with diarrhea was markedly reduced.The difference in rectal temperature and the levels of serum OVA⁃specific IgE,IgG1,IgG2a and IL⁃4 decreased significantly after prophylactic administration of SD;The number of eosinophils and mast cells in jejunum also decreased significantly while the IL⁃10 level in the supernatant of BMDCs increased significantly after SD intervention.Conclusion SD mitigates experimental FA response by fosters the immune tolerance property of dendritic cells.