Characterization of Fecal Microbiota, Short-Chain Fatty Acids and Lactic Acid Concentrations in 5 - 8-Year-Old Children with Cow Milk Protein Allergy

Background: Cow milk protein allergy (CMPA) has been reported to be associated with the alterations of gut microbiota. However, changes in the fecal microbial community for children aged 5 - 8 years with CMPA have not been clearly elucidated. Objectives: The aim of the study is to assess the differences and relationship between fecal microbiota and levels of fecal short-chain fatty acids (SCFAs) and lactic acid in 5 - 8-year-old children with CMPA, compared with the normal children. Methods: We enrolled 6 CMPA children and 8 healthy children from Harbin children’s hospital (Heilongjiang, China). Total bacterial DNA of all fecal samples was extracted and prepared for bioinformatics analysis by 16S rDNA amplicon sequencing. Lactic acids and SCFAs were measured by the high-performance liquid chromatography (HPLC) technique. Results: Compared with healthy individuals, the fecal microbial community of CMPA children showed a significant increment of Firmicutes and depletion of Proteobacteria (P < 0.05). At the class level, the number of Clostridia was observed to be significantly increased in the CMPA children’s fecal microbiota. Meanwhile, the diversity of Ruminococcaceae and Subdoligranulum was higher in the fecal microbiome of CMPA children than in healthy children (P < 0.05). Furthermore, linear discriminant analysis of effect size (LEfSe) revealed some significantly enriched taxa of CMPA children and control subjects. There are 40 and 5 enriched taxa in the fecal microbiota of children with CMPA and healthy children respectively. The concentration of total SCFAs was lower in feces of CMPA children than in healthy children. Lactic acid had a significantly negative correlation with the abundance of Bacteroides. Conclusions: Alterations in the composition of fecal microbiota and SCFAs in the 5 - 8-year-old children with CMPA may reduce immune function and potentially promote this allergy.