Gut microbiota composition and butyrate production in children affected by non-IgE-mediated cow's milk allergy

Abstract

Cow's milk allergy (CMA) is one of the earliest and most common food allergy and can be elicited by both IgE- or non-IgE-mediated mechanism. We previously described dysbiosis in children with IgE-mediated CMA and the effect of dietary treatment with extensively hydrolyzed casein formula (EHCF) alone or in combination with the probiotic Lactobacillus rhamnosus GG (LGG). On the contrary, the gut microbiota in non-IgE-mediated CMA remains uncharacterized. In this study we evaluated gut microbiota composition and fecal butyrate levels in children affected by non-IgE-mediated CMA. We found a gut microbiota dysbiosis in non-IgE-mediated CMA, driven by an enrichment of Bacteroides and Alistipes. Comparing these results with those previously obtained in children with IgE-mediated CMA, we demonstrated overlapping signatures in the gut microbiota dysbiosis of non-IgE-mediated and IgE-mediated CMA children, characterized by a progressive increase in Bacteroides from healthy to IgE-mediated CMA patients. EHCF containg LGG was more strongly associated with an effect on dysbiosis and on butyrate production if compared to what observed in children treated with EHCF alone. If longitudinal cohort studies in children with CMA will confirm these results, gut microbiota dysbiosis could be a relevant target for innovative therapeutic strategies in children with non-IgE-mediated CMA.

Figure 1

Score plot of the sPLS-DA model based on the microbiota composition at genus level of healthy and non-IgE mediated CMA subjects.

Figure 2

Generalized linear model fitting of patient demographic information across relative abundance of Bacteroides (A) and box plots showing the abundance of Bacteroides (B). In panel A, parallel x axis represents the relative contribution value of every factor, as predicted by the GLM model (*p < 0.05). In panel B, boxes represent the interquartile range (IQR) between the first and third quartiles, and the line inside represents the median (2nd quartile). Whiskers denote the lowest and the highest values within 1.5 x IQR from the first and third quartiles, respectively. Asterisks indicate a significant difference as obtained by pairwise Wilcoxon test (p < 0.05).

Figure 3

Pie charts showing the abundance of Bacteroides oligotypes in the different subject categories.

Figure 4

Box plots showing faecal butyrate concentration in  CMA, healthy and treated children (*p < 0.05). For a description of the box plots, see Fig. 2 legend.

Figure 5

Hierarchical McQuitty-linkage clustering of the samples based on the Pearson’s correlation coefficient of the abundance of OTUs present in at least 10% of the samples. Subjects from a previously published study (14) were included. The color scale represents the scaled abundance of each variable, denoted as Z-score, with red indicating high abundance and blue indicating low abundance. Column bars are colored according to the subject categories. Row bar is colored according to the phylum: Actinobacteria, green; Bacteroidetes, red; Firmicutes, navy blue; Proteobacteria, grey; others, orange.

Figure 6

Box plots showing the abundance of Bacteroides in healthy, non-IgE mediated and IgE mediated CMA subjects (*p < 0.05). Subjects from a previously published study were included. For a description of the box plots, see Fig. 2 legend.