The aim of this study was to investigate the effects of 24-week synbiotic supplementation on chronic inflammation and the gut microbiota in obese patients with type 2 diabetes. We randomized 88 obese patients with type 2 diabetes to one of two groups for 24 weeks: control or synbiotic (Lacticaseibacillus paracasei strain Shirota (previously Lactobacillus casei strain Shirota) and Bifidobacterium breve strain Yakult, and galactooligosaccharides). The primary endpoint was the change in interleukin-6 from baseline to 24 weeks. Secondary endpoints were evaluation of the gut microbiota in feces and blood, fecal organic acids, high-sensitivity C-reactive protein, lipopolysaccharide-binding protein, and glycemic control. Synbiotic administration for 24 weeks did not significantly affect changes in interleukin-6 from baseline to 24 weeks (0.35 ± 1.99 vs. −0.24 ± 1.75 pg/mL, respectively). Relative to baseline, however, at 24 weeks after synbiotic administration there were positive changes in the counts of Bifidobacterium and total lactobacilli, the relative abundances of Bifidobacterium species such as Bifidobacterium adolescentis and Bifidobacterium pseudocatenulatum, and the concentrations of acetic and butyric acids in feces. No significant changes in inflammatory markers were found in the synbiotic group compared to the control group. However, synbiotic administration at least partially improved the gut environment in obese patients with type 2 diabetes.

Summary: We previously suggested that gut bacteria may be involved in the onset of Kawasaki disease (KD). In this study, we evaluated the production of heat shock proteins (hsps) and superantigens (sAgs) by microorganisms isolated from the jejunal mucosa of 19 children with KD in the acute phase and from 15 age‐matched control children. We identified 13 strains of Gram‐negative microbes from patients with KD; these microbes produced large amounts of hsp60 and induced pro‐inflammatory cytokine production by peripheral blood mononuclear cells. The Gram‐negative microbes also elicited endogenous hsp60 production, leading to the secretion of anti‐inflammatory intereukin‐10 (IL‐10). We also identified 18 strains of Gram‐positive cocci that had superantigenic properties and which induced the expansion of Vβ2 T cells in vitro. All bacteria identified in this study were antibiotic resistant. These data suggest that sAg and hsps produced by gut bacteria might be involved in KD.

Human intestinal microbiota are influenced by various factors viz. diet, environment, age, gender, geographical, and socioeconomic situation, etc. among which diet has the most profound impact. However, studies investigating this impact have mostly included subjects from diverse geographic/socioeconomic backgrounds and hence the precise effects of dietary factors on gut microbiota composition remain largely confounded. Herein, with an aim to evaluate the association between dietary habits, specifically yogurt consumption, and the gut microbiota in healthy young adults sharing similar age, lifestyle routine, geographical setting, etc., we conducted a cross-sectional study wherein 293 collegiate freshmen answered a questionnaire about their frequency of yogurt consumption over the last 2 months and provided stool specimens for microbiota analysis. Fecal microbiota were analyzed by highly sensitive reverse-transcription-quantitative-PCR assays targeting bacterial 16S rRNA molecules. Fecal organic acids were measured by HPLC. Overall, the gut microbiota were predominated (97.1 ± 8.6%) by Clostridium coccoides group, Clostridium leptum subgroup, Bacteroides fragilis group, Bifidobacterium and Atopobium cluster. Interestingly, after adjusting the data for yogurt consumption, females were found to have higher total bacterial (P = 0.013) and Bifidobacterium (P = 0.046) count and fecal pH (P = 0.007) and lower fecal concentration of total organic acids (P = 0.030), succinic acid (P = 0.007) and formic acid (P = 0.046) as compared to males. Altogether, yogurt consumption showed positive linear association with Lactobacillus and Lactobacillus gasseri subgroup in both male and female subjects; however, several gender-specific disparities were also detected in this yogurt-microbiota association. Yogurt consumption demonstrated a negative association with L. sakei subgroup, Enterobacteriaceae and Staphylococcus in males but shared a positive association with L. casei subgroup and succinic acid in female subjects. The study manifests the association between yogurt consumption and gut microbiota in a healthy homogeneous cohort and show how this association can differ by host gender. The findings should be helpful for prospective studies investigating the diet–microbiome interaction in human health and disease.

Clostridium perfringens is a widespread pathogen, but the precise quantification of this subdominant gut microbe remains difficult due to its low fecal count (particularly in asymptomatic subjects) and also due to the presence of abundant polymerase-inhibitory substances in human feces. Also, information on the intestinal carriage of toxigenic C. perfringens strains in healthy subjects is sparse. Therefore, we developed a sensitive quantitative real-time PCR assays for quantification of C. perfringens in human feces by targeting its α-toxin and enterotoxin genes. To validate the assays, we finally observed the occurrence of α-toxigenic and enterotoxigenic C. perfringens in the fecal microbiota of healthy Japanese infants and young adults. The plc-specific qPCR assay was newly validated, while primers for 16S rRNA and cpe genes were retrieved from literature. The assays were validated for specificity and sensitivity in pre-inoculated fecal samples, and were finally applied to quantify C. perfringens in stool samples from apparently healthy infants (n 124) and young adults (n 221). The qPCR assays were highly specific and sensitive, with a minimum detection limit of 103 bacterial cells/g feces. Alpha-toxigenic C. perfringens was detected in 36 % infants and 33 % adults, with counts ranging widely (103-107 bacterial cells/g). Intriguingly, the mean count of α-toxigenic C. perfringens was significantly higher in infants (6.0 ± 1.5 log10 bacterial cells/g), as compared to that in adults (4.8 ± 1.2). Moreover, the prevalence of enterotoxigenic C. perfringens was also found to be significantly higher in infants, as compared to that in adults. The mean enterotoxigenic C. perfringens count was 5.9 ± 1.9 and 4.8 ± 0.8 log10 bacterial cells/g in infants and adults, respectively. These data indicate that some healthy infants and young adults carry α-toxigenic and enterotoxigenic C. perfringens at significant levels, and may be predisposed to related diseases. Thus, high fecal carriage of toxigenic C. perfringens in healthy children warrants further investigation on its potential sources and clinical significance in these subjects. In summary, we present a novel qPCR assay for sensitive and accurate quantification of α-toxigenic and enterotoxigenic C. perfringens in human feces, which should facilitate prospective studies of the gut microbiota.

The concept of the gut-brain axis (GBA) has existed for more than 3 decades [1]. Gastrointestinal motor and sensory components send messages to the central nervous system (CNS), and the return response to the intestine is the definition of the GBA [2]. Nutrition affects microbiota colonization and gut metabolites, which can influence brain development and function through neural, immunological, and endocrine pathways [3]. The brain is the central component of the GBA and includes connections between the cerebral cortex, the limbic system, the hypothalamic-pituitary axis, and the brain system. The limbic system receives input from other brain regions including the hippocampus, which is responsible for a range of behaviors [4]. The peripheral components of the GBA communicate with the CNS through the enteric, autonomic, and sympathetic nervous systems [5, 6]. The enteric nervous system, which resides within the intestinal wall, communicates with the brain via the vagus nerve, dorsal root, and nodose ganglia [5]. The hypothalamic-pituitary axis, the autonomic nervous system, and the sympathetic nervous system are integrated peripheral components of the GBA [7]. The afferent vagus nerve is a major retrograde signaling system from the gut to the brain [8]. The efferent vagus nerve-based cholinergic anti-inflammatory pathway regulates the balance between tumor necrosis factor-α and other cytokines secreted by macrophages in response to stress signals in the gut [9]. This inflammation can result in the loss of intestinal epithelial barrier function, which allows bacterial invasion. Bacterial invasion leads to an increase in intestinal permeability and activation of immune and somatic cells through pathogen-associated molecular patterns including lipopolysaccharides (LPS, endotoxin), which are recognition receptors that trigger inflammation in the gut [6]. Signals sent through the systemic and intestinal immune system via the GBA cause alterations in brain function and disease. During a state of stress, hormone and neuropeptide secretion in the gut ultimately invokes cortisol release from the adrenal gland via signals though the hypothalamus. The GBA influences intestinal immune cells via norepinephrine and neuropeptide messengers, such as vasoactive intestinal peptide, and these modulate the function of dendritic cells and T cells located throughout the wall of the intestine and in secondary lymphoid tissues, such as Peyer’s patches.