Gut microbiota profile in children affected by atopic dermatitis and evaluation of intestinal persistence of a probiotic mixture

Abstract

Atopic dermatitis (AD) has been hypothesised to be associated with gut microbiota (GM) composition. We performed a comparative study of the GM profile of 19 AD children and 18 healthy individuals aimed at identifying bacterial biomarkers associated with the disease. The effect of probiotic intake (Bifidobacterium breve plus Lactobacillus salivarius) on the modulation of GM and the probiotic persistence in the GM were also evaluated. Faecal samples were analysed by real-time PCR and 16S rRNA targeted metagenomics. Although the probiotics, chosen for this study, did not shape the entire GM profile, we observed the ability of these species to pass through the gastrointestinal tract and to persist (only B. breve) in the GM. Moreover, the GM of patients compared to CTRLs showed a dysbiotic status characterised by an increase of Faecalibacterium, Oscillospira, Bacteroides, Parabacteroides and Sutterella and a reduction of short-chain fatty acid (SCFA)-producing bacteria (i.e., Bifidobacterium, Blautia, Coprococcus, Eubacterium and Propionibacterium). Taken togheter these results show an alteration in AD microbiota composition with the depletion or absence of some species, opening the way to future probiotic intervention studies.

Figure 1

Beta-diversity analysis of AD and CTRL groups. The plots show the first two principal axes for PCoA using Bray-Curtis (A), unweighted UniFrac (B) and weighted UniFrac (C) algorithms. P-values were obtained by PERMANOVA.

Figure 2

Alpha-diversity measures of Observed, Chao1 and Shannon indexes. Boxes represent the median, 25th and 75th percentiles for AD (time points are indicated) and CTRL groups.

Figure 3

Mann–Whitney-based OTU distribution. The bar graphs represent the average distribution of the OTUs by phylum (A), family (B) and genus/species (C) levels. Only statistically significant OTUs are plotted (p-values were corrected by the Holm method).

Figure 4

ROC curve plots. The areas under the ROC curves (AUROC) represent the specificity and sensitivity of the 17 selected OTUs to discriminate the T₀ AD and CTRL groups.

Figure 5

Histograms of B. breve and L. salivarius levels at different time points. Median values differences between B. breve (blue bar) and L. salivarius (green bar) levels expressed as molecules/ul at each point of the time-course. P-values were obtained using the Mann–Whitney U test.