Characterization of gut microbiota in obese and normal-weight children : Preliminary data

CHARACTERIZATION OF GUT MICROBIOTA IN OBESE AND NORMAL-WEIGHT CHILDREN - PRELIMINARY DATA- Alessandra Riva1, Francesca Borgo1, Benedetta Mariani11,2, Elvira Verduci1,2, Enrica Riva1,2, Giulia Morace1, Elisa Borghi1 1Department of Health Sciences, Università degli Studi di Milano, via di Rudinì, 8 –Milan, Italy; 2UOC Pediatria, A.O. San Paolo, via di Rudinì, 8 – 20142 Milan, Italy. 2797/2800 caratteri spazi inclusi Introduction Children obesity could negatively impact on child’s health and wellbeing. There is increasing evidence that our gut microbiota plays a critical role in energy balance and metabolism. The microbiota is established during the first year of life and is affected by mode of delivery and breastfeeding. Shift in the relative proportions of gut microbial communities has been correlated with intestinal dysbiosis and associated with obesity. The aim of our study was to characterize and compare the gut microbiota of obese and healthy children and to determine if changes in microbial populations may be used as biomarkers for the onset of obesity. Material and methods Thirty children (13 males/17 females, 9-15 y) were enrolled from the pediatric Department of San Paolo hospital in Milan from December 2013 to May 2014 and grouped in 8 obese (O), 5 over-weight (OW), 3 under-weight (UW), and 14 normal-weight (NW), the last used as control group. Children’s BMI was calculated by reported weight/height2 (kg/m2), and the conditions of obesity, OW, UW and NW were classified according to Cole. Fecal samples were analyzed by V2-V3 PCR amplification of 16S rRNA followed by DGGE analysis and sequencing. Real-Time PCR was performed to quantify Bacteroides, Bifidobacterium and Lactobacillus genera. Fecal calprotectin, as an indicator of intestinal inflammation, was measured by a commercial ELISA assay. Results Analysis of DGGE profiles showed two main clusters (50% similarity). One represented by only a severe obese child (BMI 35.8), the other group included 4 sub-clusters without significant differences among the BMI groups. Bacterial quantification (genomes/g feces, mean value) revealed no differences in Bacteroides (NW:1.28E+11; O:1.54E+11), Lactobacillus (NW:5.76E+09; O:1.97E+09) and Bifidobacterium (NW:2.95E+09; O:3.42E+09) genera. Fecal calprotectin was increased in 37.5% of obese patients (cut-off: 100 mg/kg). Discussion and conclusion DGGE profiles demonstrated high microbial species heterogeneity. A lower microbial biodiversity was highlighted in the subject with severe obesity, born by caesarean section and fed with formula milk. In some cases, we observed correlations among genotypic profile, type of childbirth and breastfeeding. In agreement with the literature, real time studies did not show significant quantitative differences in individual community. The increase of fecal calprotectin could suggest a low-grade inflammation in obese children. These preliminary data are suggestive of a possible role of the microbiota in the onset of obesity. An increase in the number of studied children and the search for other microorganisms as Akkermansia muciniphila, Enterobacteriaceae, Fecalibacterium prausnizii, and yeasts are necessary to a better understanding.