Faecalibacterium prausnitzii phylotypes in type two diabetic, obese, and lean control subjects.

Faecalibacterium prausnitzii is one of the main butyrate producers in the healthy human gut. Information on its genetic diversity is lacking, although two genetic phylotypes have been differentiated. In the present study, F. prausnitzii phylotypes were examined in faeces of obese and type two diabetes with similar eating behaviour compared to a lean control group. The purpose of the study was to analyse if an excessive butyrate production induced by different F. prausnitzii phylotypes discriminates between obese developing type two diabetes or not. The faecal samples were analysed for the total abundance of F. prausnitzii 16S rRNA copies, fragment lengths polymorphism, high resolution melt curve analysis (HRM) and the butyryl-CoA:acetate CoA-transferase gene copies and melt curve variances. The diabetic group was found to differ significantly from the lean control group in the results of qPCR, butyryl-CoA:acetyate CoA-transferase gene melt curve, and HRM. F. prausnitzii phylotypes differed in obese with and without developed diabetes type two. Different phylotypes of F. prausnitzii may lead to differences in the inflammatory genesis in the host. F. prausnitzii phylotypes may have an influence on developing type two diabetes and might also act as starting points for prevention and therapy of obesity associated disease.

Microbiota and epigenetic regulation of inflammatory mediators in type 2 diabetes and obesity.

Metabolic syndrome is associated with alterations in the structure of the gut microbiota leading to low-grade inflammatory responses. An increased penetration of the impaired gut membrane by bacterial components is believed to induce this inflammation, possibly involving epigenetic alteration of inflammatory molecules such as Toll-like receptors (TLRs). We evaluated changes of the gut microbiota and epigenetic DNA methylation of TLR2 and TLR4 in three groups of subjects: type 2 diabetics under glucagon-like peptide-1 agonist therapy, obese individuals without established insulin resistance, and a lean control group. Clostridium cluster IV, Clostridium cluster XIVa, lactic acid bacteria, Faecalibacterium prausnitzii and Bacteroidetes abundances were analysed by PCR and 454 high-throughput sequencing. The epigenetic methylation in the regulatory region of TLR4 and TLR2 was analysed using bisulfite conversion and pyrosequencing. We observed a significantly higher ratio of Firmicutes/ Bacteroidetes in type 2 diabetics compared to lean controls and obese. Major differences were shown in lactic acid bacteria, with the highest abundance in type 2 diabetics, followed by obese and lean participants. In comparison, F. prausnitzii was least abundant in type 2 diabetics, and most abundant in lean controls. Methylation analysis of four CpGs in the first exon of TLR4 showed significantly lower methylation in obese individuals, but no significant difference between type 2 diabetics and lean controls. Methylation of seven CpGs in the promoter region of TLR2 was significantly lower in type 2 diabetics compared to obese subjects and lean controls. The methylation levels of both TLRs were significantly correlated with body mass index. Our data suggest that changes in gut microbiota and thus cell wall components are involved in the epigenetic regulation of inflammatory reactions. An improved diet targeted to induce gut microbial balance and in the following even epigenetic changes of pro-inflammatory genes may be effective in the prevention of metabolic syndrome.

Regulation of TLR4, p38 MAPkinase, IκB and miRNAs by inactivated strains of lactobacilli in human dendritic cells.

Strain specific properties of probiotics in providing supportive health effects in the immune system and the gastrointestinal tract have been widely investigated in vivo and in vitro. However, the underlying responsible mechanism is poorly described. By unravelling the probiotic-induced responses in a complex network of interacting signalling pathways, we investigated the effect of heat-inactivated Lactobacillus rhamnosus GG (LGG) and Lactobacillus delbrueckii subsp. bulgaricus (L.del) on the expression of TLR4 and signalling factors such as p38 MAPK and I?B at transcription level in human monocyte-derived dendritic cells (DCs). Our findings demonstrated that even inactivated probiotic strains can affect TLR4 expression in a down-regulatory direction as with lipopolysaccharides after 12 hours. LGG significantly down-regulated expression of p38 while I?B expression was significantly reduced in L.del-treated DCs. Moreover, we found these Lactobacillus strains could even modify the immune response at post-transcriptional level by modifying miRNAs expression. Based on our results LGG induced a significant down-regulatory effect on miR-146a expression which is known as a novel fine negative regulator of immune response targeting NFκB. On the other hand, miR-155 was up-regulated by LGG which is consistent with down-regulation of p38 and in LGG-treated DCs. These findings provide genetic and epigenetic explanations for the responsible underlying mechanisms by which probiotics influence immune response by targeting DCs.