Gut Microbiota and Obesity

Intestinal microbiota is composed by symbiotic innocuous bacteria and potential pathogens also called pathobionts. The human gut normally hosts roughly 1014 bacterial organisms of up to 1000 different species. The genome size of this microbial organ, collectively named microbiome, exceeds the size of the human nuclear genome by 2 orders of magnitude

Impact of passive smoke and/or atopy on adenoid immunoglobulin production in children

The adenoids are exposed to a wide number and variety of microbes, environmental pollutants, and food antigens. Atopy and passive smoke may significantly affect immune responses, mainly in children. The aim of the present study was to investigate whether passive exposure to tobacco smoke and/or atopy could affect immunoglobulin production by adenoidal lymphocytes in a cohort of children presenting with adenoid hypertrophy. A total of 277 children (151 males and 126 females; median age 5.5 years), with adenoidal hypertrophy requiring adenoidectomy and or adeno-tonsillectomy, were consecutively enrolled in the study. Adenoid mononuclear cells were in vitro stimulated with LPS or CpG. When considering both the presence of smoke exposure and atopy, we observed that the CpG-induced decrease in IgA and IgM production was significantly associated with this combination of risk factors. In the T-independent immunoglobulin production assay we found a positive association between the two risk factors and IgA and IgM production. In particular, the presence of both risk factors, showed a significant increase in IgA and IgM production after stimulation. In conclusion, this is the first study that investigated the in vitro adenoidal B cell response after different stimuli in children, also evaluating possible exposure to passive smoke and/or an atopic condition

Fecal Clostridiales distribution and short-chain fatty acids reflect bowel habits in irritable bowel syndrome

Irritable bowel syndrome (IBS), a common functional gastrointestinal disorder, is classified according to bowel habits as IBS with constipation (IBS-C), with diarrhea (IBS-D), with alternating constipation and diarrhea (IBS-M), and unsubtyped (IBS-U). The mechanisms leading to the different IBS forms are mostly unknown. This study aims to evaluate whether specific fecal bacterial taxa and/or short-chain fatty acids (SCFAs) can be used to distinguish IBS subtypes and are relevant for explaining the clinical differences between IBS subcategories. We characterized five fecal samples collected at 4-weeks intervals from 40 IBS patients by 16S rRNA gene profiling and SCFA quantification. Finally, we investigated the potential correlations in IBS subtypes between the fecal microbial signatures and host physiological and clinical parameters. We found significant differences in the distribution of Clostridiales OTUs among IBS subtypes and reduced levels of SCFAs in IBS-C compared to IBS-U and IBS-D patients. Correlation analyses showed that the diverse representation of Clostridiales OTUs between IBS subtypes was associated with altered levels of SCFAs; furthermore, the same OTUs and SCFAs were associated with the fecal cytokine levels and stool consistency. Our results suggest that intestinal Clostridiales and SCFAs might serve as potential mechanistic biomarkers of IBS subtypes and represent therapeutic targets

HLA-DQ genetics in children with celiac disease: A meta-analysis suggesting a two-step genetic screening procedure starting with HLA-DQ β chains

Background: Specific HLA-DQ genes have been recognized as necessary - but not sufficient - factors for the occurrence of Celiac Disease (CD). Through a meta-analysis, evaluating the distribution of CD-related HLA genotypes in children, we aimed at providing insights for a potential widened screening strategy. Methods: After a systematic search on the association between class II HLA genes and CD in children, 46 publications were obtained and assessed for eligibility. A total of 13 eligible studies were submitted to data extraction and analysis (10 case-control studies and 3 cohort studies). Case-control studies collectively enrolled 740 CD patients and 943 controls. Results: In the population-stratified analysis, the following alleles conferred a significantly increased risk for CD: HLA-DQB1*02 (odds ratio [OR]=10.28) and HLA-DQB1*03:02 (OR=2.24). By drafting a risk gradient to develop CD according to HLA genetic background, the highest risk is confirmed to exist for DQ2/DQ2 homozygous subjects, regardless of the ethnicities (OR=5.4). Actually, the genotype DQ2/β2 showed basically the same risk (OR=5.3). Indeed, no differences have been found in CD risk between DQ2/β2 and DQ2/DQ2, as well as between DQ8/β2 and DQ2/DQ8, and between β2/DQX and DQ2/X. Conclusion: The HLA-DQB1*02:01 allele is present in more than 90% CD children. In the perspective of a widened pediatric population screening for CD, a double-step process might be suggested: HLA-DQB1*02:01 might be investigated first and, only if this result is positive, children might be candidate for a prospective serologic screening, as a second step