Different fecal microbiotas and volatile organic compounds in treated and untreated children with celiac disease

Abstract

This study aimed at investigating the fecal microbiotas of children with celiac disease (CD) before (U-CD) and after (T-CD) they were fed a gluten-free diet and of healthy children (HC). Brothers or sisters of T-CD were enrolled as HC. Each group consisted of seven children. PCR-denaturing gradient gel electrophoresis (DGGE) analysis with V3 universal primers revealed a unique profile for each fecal sample. PCR-DGGE analysis with group- or genus-specific 16S rRNA gene primers showed that the Lactobacillus community of U-CD changed significantly, while the diversity of the Lactobacillus community of T-CD was quite comparable to that of HC. Compared to HC, the ratio of cultivable lactic acid bacteria and Bifidobacterium to Bacteroides and enterobacteria was lower in T-CD and even lower in U-CD. The percentages of strains identified as lactobacilli differed as follows: HC (ca. 38%) > T-CD (ca. 17%) > U-CD (ca. 10%). Lactobacillus brevis, Lactobacillus rossiae, and Lactobacillus pentosus were identified only in fecal samples from T-CD and HC. Lactobacillus fermentum, Lactobacillus delbrueckii subsp. bulgaricus, and Lactobacillus gasseri were identified only in several fecal samples from HC. Compared to HC, the composition of Bifidobacterium species of T-CD varied, and it varied even more for U-CD. Forty-seven volatile organic compounds (VOCs) belonging to different chemical classes were identified using gas-chromatography mass spectrometry-solid-phase microextraction analysis. The median concentrations varied markedly for HC, T-CD, and U-CD. Overall, the r(2) values for VOC data for brothers and sisters were equal to or lower than those for unrelated HC and T-CD. This study shows the effect of CD pathology on the fecal microbiotas of children.

FIG. 1.

Clustering of DGGE profiles of fecal samples from 21 children (children 1 to 7 and 9 to 22). The V3 universal primers (A) or V6-V8 universal primers (B) were used. Clustering was carried out using the UPGMA method based on the Pearson correlation coefficient. See Materials and Methods for an explanation of the numbered fecal samples.

FIG. 2.

Clustering of DGGE profiles of fecal samples from 21 children (children 1 to 7 and 9 to 22). Primers Lac1 and Lac2GC were used to amplify the Lactobacillus group. Clustering was carried out using the UPGMA method based on the Pearson correlation coefficient. See Materials and Methods for an explanation of the numbered fecal samples.

FIG. 3.

Clustering of DGGE profiles of fecal samples from 21 children (children 1 to 7 and 9 to 22). The g-Bifid primers were used to amplify Bifidobacterium spp. Clustering was carried out using the UPGMA method based on the Pearson correlation coefficient. See Materials and Methods for an explanation of the numbered fecal samples.

FIG. 4.

Plot of the first and second principal components after PCA based on the median data for VOCs of T-CD, U-CD, and HC.