Background and Aims MicroRNAs (miRNAs) are small non-coding RNAs, which regulate gene expression and are thus of interest as diagnostic markers, and as clues to etiology and targets of intervention. This pilot study examined whether circulating miRNAs are differentially expressed in patients with IBS. Methods miRNA microarrays (Nanostring) were run on the whole blood of 43 participants. Results hsa-miR-150 and hsa-miR-342-3p were found to be significantly elevated (FDR adjusted p ≤ 0.05, ≥1.6 fold change) in IBS patients compared to healthy controls. Neither of these miRNAs showed any relationship to race or sex. hsa-miR-150 is associated with inflammatory bowel disorders and pain, and interacts with a protein kinase (AKT2) through which it may affect inflammatory pathways. hsa-miR-342-3p is predicted to interact with mRNAs involved in pain signaling, colonic motility, and smooth muscle function. Conclusions This preliminary study reports the association of two miRNAs, detected in whole blood, with IBS. These miRNAs link to pain and inflammatory pathways both of which are thought to be dysregulated in IBS. Larger samples sizes are needed to confirm their importance and potential as biomarkers.

Irritable bowel syndrome (IBS) is a poorly understood disorder characterized by persistent symptoms, including visceral pain. Studies have demonstrated oral microbiome differences in inflammatory bowel diseases suggesting the potential of the oral microbiome in the study of non-oral conditions.In this exploratory study we examine whether differences exist in the oral microbiome of IBS participants and healthy controls, and whether the oral microbiome relates to symptom severity.The oral buccal mucosal microbiome of 38 participants was characterized using PhyloChip microarrays. The severity of visceral pain was assessed by orally administering a gastrointestinal test solution. Participants self-reported their induced visceral pain. Pain severity was highest in IBS participants (P = 0.0002), particularly IBS-overweight participants (P = 0.02), and was robustly correlated to the abundance of 60 OTUs, 4 genera, 5 families and 4 orders of bacteria (r2 > 0.4, P < 0.001). IBS-overweight participants showed decreased richness in the phylum Bacteroidetes (P = 0.007) and the genus Bacillus (P = 0.008). Analysis of β-diversity found significant separation of the IBS-overweight group (P < 0.05). Our oral microbial results are concordant with described fecal and colonic microbiome-IBS and -weight associations. Having IBS and being overweight, rather than IBS-subtypes, was the most important factor in describing the severity of visceral pain and variation in the microbiome. Pain severity was strongly correlated to the abundance of many taxa, suggesting the potential of the oral microbiome in diagnosis and patient phenotyping. The oral microbiome has potential as a source of microbial information in IBS.

The purpose of the study was to examine the interrelationships among stress, eating behavior, and adiposity in a cohort of normal- and overweight individuals. Clinical markers of physiological stress (fasting serum cortisol) and adiposity (body mass index [BMI] and percent body fat) were obtained from participants selected for a natural history protocol ( n = 107). Self-reported data on eating behavior (using the Three-Factor Eating Questionnaire subscales such as Cognitive Restraint, Disinhibition, and Hunger) and psychological stress (via the Perceived Stress Scale) were evaluated. Demographic information was incorporated using principal component analysis, which revealed sex- and weight-based differences in stress, adiposity, and eating behavior measures. Following a cross-sectional and descriptive analysis, significant correlations were found between the Disinhibition and Hunger eating behavior subscales and measures of adiposity including BMI ( r = .30, p = .002 and r = .20, p = .036, respectively) and percent body fat ( r = .43, p = .000 and r = .22, p = .022, respectively). Relationships between stress measures and eating behavior were also evident in the analysis. Disinhibition and Hunger correlated positively with perceived stress ( r = .32, p .001 and r = .26, p = .008, respectively). However, Disinhibition varied inversely with serum cortisol levels ( r = -.25, p = .009). Future studies are warranted to better understand this paradox underlying the effects of perceived and physiological stress on eating behavior.