The aim of this study was to investigate the gut microbiota in preschool children with and without overweight and obesity. Twenty overweight or obese children and twenty children with BMI within the normal range (age: 4–5 years) were recruited from the south of Sweden. The gut microbiota was accessed by quantitative PCR (qPCR) and terminal restriction fragment length polymorphism and calprotectin was measured in feces. Liver enzymes were quantified in obese/overweight children. The concentration of the gram‐negative family Enterobacteriaceae was significantly higher in the obese/overweight children (P = 0.036), whereas levels of Desulfovibrio and Akkermansia muciniphila‐like bacteria were significantly lower in the obese/overweight children (P = 0.027 and P = 0.030, respectively). No significant differences were found in content of Lactobacillus, Bifidobacterium or the Bacteroides fragilis group. The diversity of the dominating bacterial community tended to be less diverse in the obese/overweight group, but the difference was not statistically significant. Concentration of Bifidobacterium was inversely correlated to alanine aminotransferase (ALT) in obese/overweight children. The fecal levels of calprotectin did not differ between the study groups. These findings indicate that the gut microbiota differed among preschool children with obesity/overweight compared with children with BMI within the normal range.

Background: Mucins are large complex glycoproteins that protect intestinal mucosal surfaces by limiting access of environmental matter to their epithelial cells. Several mucin genes have been described, including MUC3 that is a membrane associated mucin of the small intestine. Increased MUC3 mRNA transcription is induced by incubation of intestinal epithelial cells with a Lactobacillus strain known to be adherent to them. Aims: To determine whether increased epithelial cell MUC3 mucin expression in response to Lactobacillus strains results in increased extracellular secretion of MUC3 mucins and the importance of epithelial cell adherence in modulation of MUC3 mucin expression. Methods: HT29 cells grown to enhance expression of MUC3 mucins were incubated with selected Lactobacillus strains. Spent cell culture medium was collected for detection of secreted MUC3 mucins using dot blot immunoassay with a generated MUC3 antibody. Post-incubation HT29 cell RNA was collected for analysis of MUC3 expression by northern blot analysis using a MUC3 cDNA probe. In vitro binding studies using Lactobacillus strains incubated alone or coincubated with enteropathogenic Escherichia coli strain E2348/69 were used for adherence and inhibition of adherence studies, respectively. Results: Lactobacillus strains with minimal ability to adhere to HT29 cells failed to induce upregulation of mucin gene expression. There was a direct correlation between upregulation of MUC3 mucin mRNA expression and extracellular secretion of MUC3 mucin. The same Lactobacillus strains that increased extracellular secretion of MUC3 mucin led to reduced adherence of enteropathogen E coli E2348/69 during coincubation experiments. Conclusion: Probiotic microbes induce MUC3 mucin transcription and translation with extracellular secretion of the MUC3 mucins. Epithelial cell adherence enhances the effects of probiotics on eukaryotic mucin expression.

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Bacterial diversity of the mucosal biopsies from human jejunum, distal ileum, ascending colon and rectum were compared by analysis of PCR-amplified 16S rDNA clone libraries. A total of 347 clones from the mucosal biopsies were partially sequenced and assigned to six phylogenetic phyla of the domain Bacteria: Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria, Verrucomicrobia, and Actinobacteria. The jejunum sample had least microbial diversity compared to the other samples and a trend towards highest diversity in ascending colon was observed. The clone libraries of distal ileum, ascending colon and rectum were not significantly different from each other (P>0.0043), but they differed significantly from the jejunum library (P=0.001). The population of sequences retrieved from jejunal biopsies was dominated by sequences closely related to Streptococcus (67%), while the population of sequences derived from distal ileum, ascending colon and rectum were dominated by sequences affiliated with Bacteroidetes (27-49%), and Clostridium clusters XIVa (20-34%) and IV (7-13%). The results indicate that the microbial community in jejunum is different from those in distal ileum, ascending colon and rectum, and that the major phylogenetic groups are similar from distal ileum to rectum.