Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias (IPLA)-Consejo Superior de Investigaciones Científicas (CSIC), Villaviciosa, Spain.
Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain.
Front Immunol. 2019 Aug 2;10:1819. doi: 10.3389/fimmu.2019.01819. eCollection 2019.
Cow's milk protein allergy (CMPA) is the most common allergy in the first year of life. Non-IgE mediated CMPA is characterized by digestive symptoms and tolerance development before the age of three. Gut microbiota composition in early life has been associated with food allergy. The ingestion of different foods/nutrients may mark different shifts in the microbial colonization of the infant intestine as well as the consumption of probiotics. To analyze changes in microbiota composition and metabolic and cytokine profiles in fecal samples from infants with non-IgE mediated CMPA after successful milk challenges, tolerance acquisition, and increasing dairy introduction in their diet. Twelve children with CMPA, aged between 1 and 2 years old, were recruited for the study. Participants were initially consuming hypoallergenic hydrolyzed formulas (four of them supplemented with the probiotic GG), before being exposed to a standardized oral challenge (SOC) with cow's milk. Fecal samples were collected before, 1 week, and 1 month after performing the SOC. Changes in gut microbiota were determined by high-throughput amplicon sequencing of the 16S rRNA gene. Levels of lactobacilli were also determined by quantitative PCR (qPCR). Microbial metabolites were analyzed by chromatographic methods and fecal cytokines related to the Th1/Th2 balance were determined by immunoassay. Lactic acid bacteria significantly increased in infants who outgrew non-IgE CMPA, after the introduction of milk. Microbial metabolites derived from the fermentation of proteins, such as branched chain fatty acids, and -cresol, diminished. After the SOC, some cytokines related to inflammation (TNF-α, IFN-γ) increased. Accompanying the introduction of an unrestricted diet, we found significant differences in fecal microbial composition, metabolites, and cytokines between infants who did not consume the probiotic GG and those that did. These findings indicate that the introduction of intact milk proteins is followed by modifications in the infant gut environment through changes in immune mediators, microbiota, and its metabolic end-products. Consumption of probiotics during CMPA may contribute to gut homeostasis by fine-tuning these profiles.
牛奶蛋白过敏（CMPA）是生命第一年最常见的过敏。非 IgE 介导的 CMPA 的特征是在三岁之前出现消化症状和耐受发展。生命早期的肠道微生物群组成与食物过敏有关。不同食物/营养素的摄入可能标志着婴儿肠道微生物定植的不同转变，以及益生菌的消耗。为了分析非 IgE 介导的 CMPA 婴儿在成功进行牛奶挑战、获得耐受和增加乳制品摄入后，粪便样本中微生物群组成、代谢和细胞因子谱的变化。
研究纳入了 12 名年龄在 1 至 2 岁之间的 CMPA 儿童。参与者最初食用低敏水解配方（其中 4 名补充了益生菌 GG），然后接受标准化的口服牛奶挑战（SOC）。在进行 SOC 之前、1 周和 1 个月收集粪便样本。通过高通量扩增子测序 16S rRNA 基因来确定肠道微生物群的变化。通过定量 PCR（qPCR）测定乳杆菌的水平。通过色谱方法分析微生物代谢物，并通过免疫测定法测定与 Th1/Th2 平衡相关的粪便细胞因子。
在引入牛奶后，非 IgE CMPA 消退的婴儿中，乳酸菌显著增加。来源于蛋白质发酵的微生物代谢物，如支链脂肪酸和 -甲酚，减少。在 SOC 后，一些与炎症相关的细胞因子（TNF-α、IFN-γ）增加。伴随着无限制饮食的引入，我们发现未食用益生菌 GG 的婴儿和食用益生菌 GG 的婴儿之间的粪便微生物组成、代谢物和细胞因子存在显著差异。
这些发现表明，完整牛奶蛋白的引入通过改变免疫介质、微生物群及其代谢终产物，导致婴儿肠道环境发生改变。CMPA 期间益生菌的消耗可能通过微调这些谱来促进肠道内稳态。
