为研究益生菌缓解食物过敏的作用机制，本实验以牛乳β-乳球蛋白（BLG）为过敏原构建小鼠食物过敏模型，灌服长双歧杆菌BBMN68（BBMN68），采用ELISA方法检测小鼠血清及细胞培养上清中抗体和细胞因子含量，流式细胞术分析小鼠体内树突状细胞（DCs）亚型及CD4+CD25+Foxp3+Treg细胞数量的变化。结果表明，BBMN68调节了BLG小鼠体内的Th1/Th2细胞失衡，缓解了过敏反应。与过敏组小鼠相比，BBMN68显著提高了派氏淋巴结DCs中CD103表达（p<0.05），并降低了CD86和MHC-II表达（p<0.05）；提高了派氏淋巴结，肠系膜淋巴结和脾脏中CD4+CD25+Foxp3+Treg细胞数量，分别增加41.91%，71.16%和61.25%。分离BBMN68组小鼠派氏淋巴结的DCs与BLG过敏小鼠的CD4+T细胞共培养，发现Foxp3+Treg细胞比例显著增加，调节性细胞因子TGF-β和IL-10分泌显著增多（p<0.05）。以上结果说明BBMN68缓解小鼠牛乳β-乳球蛋白过敏的机制与其调节DCs功能，促进其介导的免疫抑制有关。

To clarify the mechanism of probiotics on alleviating food allergy symptoms, bovine β-lactoglobulin (BLG) was used as the allergen to construct a food-allergy mouse model. BALB/c mice were sensitized by oral administration of Bifidobacterium longum BBMN68 (BBMN68). Levels of cytokines and immunoglobulins in the serum and cell culture supernatant were determined by enzyme-linked immunosorbent assay (ELISA), and the changes in the number of CD4+CD25+Foxp3+Treg cells and different subsets of dendritic cells (DCs) were evaluated by flow cytometry. The results showed that BBMN68 alleviated the T-helper 1 (Th1)/T-helper 2 (Th2) imbalance, and reduced hypersensitivity reactions in BLG mice. Compared with the allergy group, the administration of BBMN68 significantly enhanced the expression of CD103 (p < 0.05) and reduced the expression of CD86 and MHC-II (p< 0.05) of DCs in Peyer’s patches (PP). The numbers of CD4+CD25+Foxp3+Treg cells in the lymphocytes from PP, mesenteric lymph node, and spleen were increased by 41.91%, 71.16%, and 61.25%, respectively, compared with those in BLG mice. These DCs modulated with BBMN68 and the CD4+T cells from BLG mice were isolated and cultured together. The results showed an increased proportion of Foxp3+Treg cells and an elevated secretion of regulatory cytokines TGF-β and IL-10 (p < 0.05). These data demonstrated that the mechanism of BBMN68 for reducing BLG allergenicity was associated with the regulation of DC functions and promotion of the DC-mediated immune suppression.

中央在京高校重大成果转化项目“益生菌生产关键技术科技成果转化”；国家科技支撑计划“南方大城市奶牛健康养殖生产技术集成及产业化示范”(2012BAD12B08）