Functional Bowel Disorders: A Roadmap to Guide the Next Generation of Research

Identifying Novel Subtypes of Functional Gastrointestinal Disorder by Analyzing Nonlinear Structure in Integrative Biopsychosocial Questionnaire Data

Background/Objectives: Given the limited success in treating functional gastrointestinal disorders (FGIDs) through conventional methods, there is a pressing need for tailored treatments that account for the heterogeneity and biopsychosocial factors associated with FGIDs. Here, we considered the potential of novel subtypes of FGIDs based on biopsychosocial information. Methods: We collected data from 198 FGID patients utilizing an integrative approach that included the traditional Korean medicine diagnosis questionnaire for digestive symptoms (KM), as well as the 36-item Short Form Health Survey (SF-36), alongside the conventional Rome-criteria-based Korean Bowel Disease Questionnaire (K-BDQ). Multivariate analyses were conducted to assess whether KM or SF-36 provided additional information beyond the K-BDQ and its statistical relevance to symptom severity. Questions related to symptom severity were selected using an extremely randomized trees (ERT) regressor to develop an integrative questionnaire. For the identification of novel subtypes, Uniform Manifold Approximation and Projection and spectral clustering were used for nonlinear dimensionality reduction and clustering, respectively. The validity of the clusters was assessed using certain metrics, such as trustworthiness, silhouette coefficient, and accordance rate. An ERT classifier was employed to further validate the clustered result. Results: The multivariate analyses revealed that SF-36 and KM supplemented the psychosocial aspects lacking in K-BDQ. Through the application of nonlinear clustering using the integrative questionnaire data, four subtypes of FGID were identified: mild, severe, mind-symptom predominance, and body-symptom predominance. Conclusions: The identification of these subtypes offers a framework for personalized treatment strategies, thus potentially enhancing therapeutic outcomes by tailoring interventions to the unique biopsychosocial profiles of FGID patients.

The Crucial Role of the Interstitial Cells of Cajal in Neurointestinal Diseases

Neurointestinal diseases result from dysregulated interactions between the nervous system and the gastrointestinal (GI) tract, leading to conditions such as Hirschsprung's disease and irritable bowel syndrome. These disorders affect many people, significantly diminishing their quality of life and overall health. Central to GI motility are the interstitial cells of Cajal (ICC), which play a key role in muscle contractions and neuromuscular transmission. This review highlights the role of ICC in neurointestinal diseases, revealing their association with various GI ailments. Understanding the functions of the ICC could lead to innovative perspectives on the modulation of GI motility and introduce new therapeutic paradigms. These insights have the potential to enhance efforts to combat neurointestinal diseases and may lead to interventions that could alleviate or even reverse these conditions.

Glucocorticoid receptor-mediated Nr1d1 chromatin circadian misalignment in stress-induced irritable bowel syndrome

Stress-elevated glucocorticoids cause circadian disturbances and gut-brain axis (GBA) disorders, including irritable bowel syndrome (IBS). We hypothesized that the glucocorticoid receptor (GR/NR3C1) might cause chromatin circadian misalignment in the colon epithelium. We observed significantly decreased core circadian gene Nr1d1 in water avoidance stressed (WAS) BALB/c colon epithelium, like in IBS patients. WAS decreased GR binding at the Nr1d1 promoter E-box (enhancer box), and GR could suppress Nr1d1 via this site. Stress also altered GR binding at the E-box sites along the Ikzf3-Nr1d1 chromatin and remodeled circadian chromatin 3D structures, including Ikzf3-Nr1d1 super-enhancer, Dbp, and Npas2. Intestinal deletion of Nr3c1 specifically abolished these stress-induced transcriptional alternations relevant to IBS phenotypes in BALB/c mice. GR mediated Ikzf3-Nr1d1 chromatin disease related circadian misalignment in stress-induced IBS animal model. This animal model dataset suggests that regulatory SNPs of human IKZF3-NR1D1 transcription through conserved chromatin looping have translational potential based on the GR-mediated circadian-stress crosstalk.

Gut microbiota and irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that poses a significant health concern. Although its etiology remains unknown, there is growing evidence that gut dysbiosis is involved in the development and exacerbation of IBS. Previous studies have reported altered microbial diversity, abundance, and composition in IBS patients when compared to controls. However, whether dysbiosis or aberrant changes in the intestinal microbiota can be used as a hallmark of IBS remains inconclusive. We reviewed the literatures on changes in and roles of intestinal microbiota in relation to IBS and discussed various gut microbiota manipulation strategies. Gut microbiota may affect IBS development by regulating the mucosal immune system, brain-gut-microbiome interaction, and intestinal barrier function. The advent of high-throughput multi-omics provides important insights into the pathogenesis of IBS and promotes the development of individualized treatment for IBS. Despite advances in currently available microbiota-directed therapies, large-scale, well-organized, and long-term randomized controlled trials are highly warranted to assess their clinical effects. Overall, gut microbiota alterations play a critical role in the pathophysiology of IBS, and modulation of microbiota has a significant therapeutic potential that requires to be further verified.

The Stressed Gut: Region-specific Immune and Neuroplasticity Changes in Response to Chronic Psychosocial Stress

Background/Aims

Chronic psychological stress affects gastrointestinal physiology which may underpin alterations in the immune response and epithelial transport, both functions are partly regulated by enteric nervous system. However, its effects on enteric neuroplasticity are still unclear. This study aims to investigate the effects of chronic unpredictable psychological stress on intestinal motility and prominent markers of enteric function.

Methods

Adult male C57BL/6J mice were exposed to 19 day of unpredictable stress protocol schedule of social defeat and overcrowding. We investigated the effects on plasma corticosterone, food intake, and body weight. In vivo gastrointestinal motility was assessed by fecal pellet output and by whole-gastrointestinal transit (using the carmine red method). Tissue monoamine level, neural and glial markers, neurotrophic factors, monoamine signaling, and Toll-like receptor expression in the proximal and distal colon, and terminal ileum were also assessed.

Results

Following chronic unpredictable psychological stress, stressed mice showed increased food intake and body weight gain (P < 0.001), and reduced corticosterone levels (P < 0.05) compared to control mice. Stressed mice had reduced stool output without differences in water content, and showed a delayed gastrointestinal transit compared to control mice (P < 0.05). Stressed mice exhibited decreased mRNA expression of tyrosine hydroxylase (Th), brain-derived neurotrophic factor (Bdnf) and glial cell-derived neurotrophic factor (Gdnf), as well as Toll-like receptor 2 (Tlr2) compared to control (P < 0.05), only proximal colon. These molecular changes in proximal colon were associated with higher levels of monoamines in tissue.

Conclusion

Unpredictable psychological chronic stress induces region-specific impairment in monoamine levels and neuroplasticity markers that may relate to delayed intestinal transit.

Multi-omics for biomarker approaches in the diagnostic evaluation and management of abdominal pain and irritable bowel syndrome: what lies ahead

Reliable biomarkers for common disorders of gut-brain interaction characterized by abdominal pain, including irritable bowel syndrome (IBS), are critically needed to enhance care and develop individualized therapies. The dynamic and heterogeneous nature of the pathophysiological mechanisms that underlie visceral hypersensitivity have challenged successful biomarker development. Consequently, effective therapies for pain in IBS are lacking. However, recent advances in modern omics technologies offer new opportunities to acquire deep biological insights into mechanisms of pain and nociception. Newer methods for large-scale data integration of complementary omics approaches have further expanded our ability to build a holistic understanding of complex biological networks and their co-contributions to abdominal pain. Here, we review the mechanisms of visceral hypersensitivity, focusing on IBS. We discuss candidate biomarkers for pain in IBS identified through single omics studies and summarize emerging multi-omics approaches for developing novel biomarkers that may transform clinical care for patients with IBS and abdominal pain.

Two microbiota subtypes identified in irritable bowel syndrome with distinct responses to the low FODMAP diet

OBJECTIVE

Reducing FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) can be clinically beneficial in IBS but the mechanism is incompletely understood. We aimed to detect microbial signatures that might predict response to the low FODMAP diet and assess whether microbiota compositional and functional shifts could provide insights into its mode of action.

DESIGN

We used metagenomics to determine high-resolution taxonomic and functional profiles of the stool microbiota from IBS cases and household controls (n=56 pairs) on their usual diet. Clinical response and microbiota changes were studied in 41 pairs after 4 weeks on a low FODMAP diet.

RESULTS

Unsupervised analysis of baseline IBS cases pre-diet identified two distinct microbiota profiles, which we refer to as IBSP (pathogenic-like) and IBSH (health-like) subtypes. IBSP microbiomes were enriched in Firmicutes and genes for amino acid and carbohydrate metabolism, but depleted in Bacteroidetes species. IBSH microbiomes were similar to controls. On the low FODMAP diet, IBSH and control microbiota were unaffected, but the IBSP signature shifted towards a health-associated microbiome with an increase in Bacteroidetes (p=0.009), a decrease in Firmicutes species (p=0.004) and normalisation of primary metabolic genes. The clinical response to the low FODMAP diet was greater in IBSP subjects compared with IBSH (p=0.02).

CONCLUSION

50% of IBS cases manifested a 'pathogenic' gut microbial signature. This shifted towards the healthy profile on the low FODMAP diet; and IBSP cases showed an enhanced clinical responsiveness to the dietary therapy. The effectiveness of FODMAP reduction in IBSP may result from the alterations in gut microbiota and metabolites produced. Microbiota signatures could be useful as biomarkers to guide IBS treatment; and investigating IBSP species and metabolic pathways might yield insights regarding IBS pathogenic mechanisms.

The involvement of Pellino-1 downregulation in the modulation of visceral hypersensitivity via the TLR4/NF-κB pathway in the rat fastigial nucleus

Irritable bowel syndrome (IBS) is a common functional bowel disorder whose key characteristics include chronic visceral hypersensitivity (CVH) and abnormal brain-gut interactions. Pellino-1 is an E3 ubiquitin ligase, mediating the degradation or modification of targeted proteins. Some brain regions, such as the fastigial nucleus (FN), may play important roles in CVH; however, the molecular mechanism underlying this phenomenon is not clear. In this study, we assessed the roles of Pellino-1 within the FN in modulating VH by generating a colorectal distention (CRD) model in male Sprague-Dawley rats. Our results showed that the downregulation of Pellino-1 in the fastigial nucleus (FN) was involved in the modulation of visceral hypersensitivity. The expression of Pellino-1 was downregulated in the FN of adult CRD rats compared with control rats, whereas TLR4 and NF-κB were upregulated in the CRD model. To overexpress Pellino-1, a lentivirus specifically expressing Pellino-1 and green fluorescent protein was administered into the FN. The overexpression of Pellino-1 increased the visceral sensitivity of CRD rats, and the expression of TLR4 and NF-κB increased further. After administration of TAK-242 (a specific TLR4 inhibitor), the visceral response to overexpression of Pellino-1 was reversed. Overall, the findings indicated the involvement of the FN in the development of CVH; the downregulation of Pellino-1 in the FN acted through the TLR4/NF-κB pathway to protect against CVH in a CRD rat model.

Efficacy and MicroRNA-Gut Microbiota Regulatory Mechanisms of Acupuncture for Severe Chronic Constipation: Study Protocol for a Randomized Controlled Trial

Background

Severe chronic constipation (SCC) is a common functional gastrointestinal (GI) disorder associated with disruptions in GI motility. Abnormalities between gut microbiota and microRNAs (miRNAs) are implicated in the pathogenesis of GI motility in SCC. Acupuncture has been shown to improve constipation-related symptoms and rebalance the gut microbiota. This protocol proposed a plan to explore the hypothesis that the efficacy of acupuncture is associated with the crosstalk between gut microbes and miRNAs in patients with SCC.

Methods

This trial is designed as a randomized, sham-controlled trial involving 80 patients and 40 healthy volunteers. A total of 80 patients with SCC (≤2 mean spontaneous, complete bowel movements per week [CSBMs]) will be randomly allocated to receive either 16-session acupuncture at true acupoints or non-penetrating sham acupuncture at non-acupoints for 4 weeks. The primary outcome will be the proportion of patients with ≥3 mean weekly CSBMs over weeks 1–4 and 5–8. Secondary efficacy endpoints include bowel movements, stool consistency, degree of straining, and the quality of life. Healthy volunteers will not receive any clinical intervention. Fasting plasma and fecal samples will be analyzed by 16S rRNA third-generation sequencing and miRNA high-throughput sequencing technologies. Finally, a tripartite network analysis will be used to investigate the interactions among clinical efficacy, miRNAs, and intestinal microbiota.

Discussion

From the perspective of microRNA-gut microbiota regulatory mechanisms, our results will partially illuminate the crucial role of fecal miRNAs and intestinal microbiota to understand how acupuncture exerts its anti-constipation role.

Trial registration

This trial is registered with ChiCTR2100048831, registered 18 July 2021; ethical approval has been obtained from the Sichuan Regional Ethics Review of Committee on Traditional Chinese Medicine, approval ID: 2021KL-023.

Delivery Methods of Cognitive Behavior Therapy for Patients With Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is the most commonly diagnosed gastrointestinal disorder and negatively impacts individuals' quality of life. Cognitive behavioral therapy appears effective for reducing symptoms in many irritable bowel syndrome patients. However, the optimal methods to deliver cognitive behavioral therapy and the effective treatment dosage for patients with IBS remain unclear. This article aims to provide an update on cognitive behavioral therapy research in IBS, particularly considering the dose of treatment, route of delivery (in-person vs. web- and telephone-based delivery), and outcome measures. A systematic literature review was conducted using databases of PubMed, CINAHL Complete, and Web of Science from 2008 through 2021. Twelve studies reporting randomized clinical trials comparing cognitive behavioral therapy delivered with in-person, telephone, and web for the management of IBS symptoms among adults with irritable bowel syndrome were found. The dose of treatment varied from 4 to 10 sessions. Six different scales measured various outcomes. No severe adverse reactions to cognitive behavioral therapy were reported. Cognitive behavioral therapy is an effective treatment for IBS symptoms regardless of the dose and the route of treatment. However, it is difficult to compare the effectiveness of these randomized clinical trials due to the various cognitive behavioral therapy protocols, combined routes of therapy delivery, and different outcome measures used.

Chronic psychological stress alters gene expression in rat colon epithelial cells promoting chromatin remodeling, barrier dysfunction and inflammation

Chronic stress is commonly associated with enhanced abdominal pain (visceral hypersensitivity), but the cellular mechanisms underlying how chronic stress induces visceral hypersensitivity are poorly understood. In this study, we examined changes in gene expression in colon epithelial cells from a rat model using RNA-sequencing to examine stress-induced changes to the transcriptome. Following chronic stress, the most significantly up-regulated genes included Atg16l1, Coq10b, Dcaf13, Nat2, Ptbp2, Rras2, Spink4 and down-regulated genes including Abat, Cited2, Cnnm2, Dab2ip, Plekhm1, Scd2, and Tab2. The primary altered biological processes revealed by network enrichment analysis were inflammation/immune response, tissue morphogenesis and development, and nucleosome/chromatin assembly. The most significantly down-regulated process was the digestive system development/function, whereas the most significantly up-regulated processes were inflammatory response, organismal injury, and chromatin remodeling mediated by H3K9 methylation. Furthermore, a subpopulation of stressed rats demonstrated very significantly altered gene expression and transcript isoforms, enriched for the differential expression of genes involved in the inflammatory response, including upregulation of cytokine and chemokine receptor gene expression coupled with downregulation of epithelial adherens and tight junction mRNAs. In summary, these findings support that chronic stress is associated with increased levels of cytokines and chemokines, their downstream signaling pathways coupled to dysregulation of intestinal cell development and function. Epigenetic regulation of chromatin remodeling likely plays a prominent role in this process. Results also suggest that super enhancers play a primary role in chronic stress-associated intestinal barrier dysfunction.

Linking stress and inflammation - is there a missing piece in the puzzle?

Extreme stressful incidents or even prolonged mild stress, whether physiological, psychosocial, or both, has been connected with development of chronic inflammation. Seemingly dissimilar medical conditions have been linked to this inflammatory state with weakened immune response, cancer, and metabolic and psychiatric disorders. Alteration of the gut microbiome is a common feature of these conditions and influences physiological functions throughout the body via bidirectional communication with the nervous, immune, and endocrine systems. Here, we propose that stress sensitivity, whether inborn or acquired, induces alterations in intestinal permeability and the gut microbiome to establish and stabilize chronic inflammatory states. Thus, treatment of chronic inflammation as a component of any disease should also involve the restoration of intestinal tight junction fidelity and a healthy intestinal microbial ecosystem.

LPAR1 regulates enteric nervous system function through glial signaling and contributes to chronic intestinal pseudo-obstruction

Gastrointestinal motility disorders involve alterations to the structure and/or function of the enteric nervous system (ENS) but the causal mechanisms remain unresolved in most cases. Homeostasis and disease in the ENS are processes that are regulated by enteric glia. Signaling mediated through type I lysophosphatidic acid receptors (LPAR1) has recently emerged as an important mechanism that contributes to disease, in part, through effects on peripheral glial survival and function. Enteric glia express LPAR1 but its role in ENS function and motility disorders is unknown. We used a combination of genetic, immunohistochemical, calcium imaging, and in vivo pharmacological approaches to investigate the role of LPAR1 in enteric glia. LPAR1 was enriched in enteric glia in mice and humans and LPA stimulated intracellular calcium responses in enteric glia, subsequently recruiting activity in a subpopulation of myenteric neurons. Blocking LPAR1 in vivo with AM966 attenuated gastrointestinal motility in mice and produced marked enteric neuro- and gliopathy. Samples from humans with chronic intestinal pseudo-obstruction (CIPO), a severe motility disorder, showed reduced glial LPAR1 expression in the colon and ileum. These data suggest that enteric glial LPAR1 signaling regulates gastrointestinal motility through enteric glia and could contribute to severe motility disorders in humans such as CIPO.

Evaluation of a Multidisciplinary Integrated Treatment Approach Versus Standard Model of Care for Functional Gastrointestinal Disorders (FGIDS): A Matched Cohort Study

BACKGROUND

Functional gastrointestinal disorders (FGID) are linked to a variety of potential causes, and treatments include reassurance, life-style (including diet), psychological, or pharmacologic interventions.

AIMS

To assess whether a multidisciplinary integrated treatment approach delivered in a dedicated integrated care clinic (ICC) was superior to the standard model of care in relation to the gastrointestinal symptom burden.

METHODS

A matched cohort of 52 consecutive patients with severe manifestation of FGID were matched with 104 control patients based upon diagnosis, gender, age, and symptom severity. Patients in the ICC received structured assessment and 12-weeks integrated treatment sessions provided as required by gastroenterologist and allied health team. Control patients received standard medical care at the same tertiary center with access to allied health services as required but no standardized interprofessional team approach. Primary outcome was reduction in gastrointestinal symptom burden as measured by the Structured Assessment of Gastrointestinal Symptoms Scale (SAGIS). Secondary outcome was reduction in anxiety and depressive symptoms as measured by the Hospital Anxiety and Depression Scale (HADS).

RESULTS

Mixed models estimated the within ICC change in SAGIS total as -9.7 (95% CI -13.6, -5.8; p < 0.0001), compared with -1.7 (95% CI -4.0, 0.6; p = 0.15) for controls. The difference between groups reached statistical significance, -7.6 (95% CI -11.4, -3.8; p < 0.0001). Total HADS scores in ICC patients were 3.4 points lower post-intervention and reached statistical significance (p = 0.001).

CONCLUSION

This matched cohort study demonstrates superior short-term outcomes of FGID patients in a structured multidisciplinary care setting as compared to standard care.

Irritable bowel syndrome in women: Association between decreased insular subregion volumes and gastrointestinal symptoms

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All insular subregions are smaller in IBS compared to healthy women.

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Insular volume associates with GI symptoms independent of psychiatric comorbidity.

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GI symptoms associate with anterior but not posterior insular volume.

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More nausea associated with smaller dorsal anterior insula bilaterally.

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Insula in major depression is not significantly smaller than in healthy women.

Objective

Irritable bowel syndrome (IBS) is a chronic pain disorder characterized by disturbed interactions between the gut and the brain with depression as a common comorbidity. In both IBS and depression, structural brain alterations of the insular cortices, key structures for pain processing and interoception, have been demonstrated but the specificity of these findings remains unclear. We compared the gray matter volume (GMV) of insular cortex (IC) subregions in IBS women and healthy controls (HC) and examined relations to gastrointestinal (GI) symptoms and glutamate + glutamine (Glx) concentrations. We further analyzed GMV of IC subregions in women with major depression (MDD) compared to HC and addressed possible differences between depression, IBS, IBS with depression and HC.

Design

Women with IBS (n = 75), MDD (n = 41) and their respective HC (n = 39 and n = 43) underwent structural brain MRI. IC subregion volumes were estimated using statistical parametric mapping software. General linear model approaches were applied to IC volumetric data and FDR-corrected partial correlation analyses assessed relations between GMV, GI symptoms and Glx concentrations.

Results

IBS patients had significantly smaller IC subregions than HC in both hemispheres but there was no significant difference between MDD compared with IBS and HC for any insular subregion. In IBS, the dorsal anterior insular volumes were negatively correlated with symptoms of nausea and pain, and the left ventral subregion showed a positive correlation with straining to defecate, while the posterior subregion volumes showed no relation to symptoms. In the anterior insula, concentration of Glx showed positive correlations with GMV bilaterally in HC and with GMV of the right anterior insula in IBS.

Conclusion

As the interoceptive cortex, the insula shows substantial and disease-specific structural differences in patients with chronic interoceptive visceral pain. Particularly changes in the anterior proportions might be related to chronic exposure to or enhanced salience towards adverse interoceptive visceral signals and could be linked to biochemical changes, calling for further multimodal and longitudinal work.

Enteric Microbiota-Mediated Serotonergic Signaling in Pathogenesis of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a chronic functional disorder that affects the gastrointestinal tract. Details regarding the pathogenesis of IBS remain largely unknown, though the dysfunction of the brain-gut-microbiome (BGM) axis is a major etiological factor, in which neurotransmitters serve as a key communication tool between enteric microbiota and the brain. One of the most important neurotransmitters in the pathology of IBS is serotonin (5-HT), as it influences gastrointestinal motility, pain sensation, mucosal inflammation, immune responses, and brain activity, all of which shape IBS features. Genome-wide association studies discovered susceptible genes for IBS in serotonergic signaling pathways. In clinical practice, treatment strategies targeting 5-HT were effective for a certain portion of IBS cases. The synthesis of 5-HT in intestinal enterochromaffin cells and host serotonergic signaling is regulated by enteric resident microbiota. Dysbiosis can trigger IBS development, potentially through aberrant 5-HT signaling in the BGM axis; thus, the manipulation of the gut microbiota may be an alternative treatment strategy. However, precise information regarding the mechanisms underlying the microbiota-mediated intestinal serotonergic pathway related to the pathogenesis of IBS remains unclear. The present review summarizes current knowledge and recent progress in understanding microbiome–serotonin interaction in IBS cases.

Altered metabolism of bile acids correlates with clinical parameters and the gut microbiota in patients with diarrhea-predominant irritable bowel syndrome

BACKGROUND

Bile acids (BAs) have attracted attention in the research of irritable bowel syndrome with predominant diarrhea (IBS-D) due to their ability to modulate bowel function and their tight connection with the gut microbiota. The composition of the fecal BA pool in IBS-D patients is reportedly different from that in healthy populations. We hypothesized that BAs may participate in the pathogenesis of IBS-D and the altered BA profile may be correlated with the gut microbiome.

AIM

To investigate the role of BAs in the pathogenesis of IBS-D and the correlation between fecal BAs and gut microbiota.

METHODS

Fifty-five IBS-D patients diagnosed according to the Rome IV criteria and twenty-eight age-, sex-, and body mass index-matched healthy controls (HCs) were enrolled in this study at the gastroenterology department of China-Japan Friendship Hospital. First, clinical manifestations were assessed with standardized questionnaires, and visceral sensitivity was evaluated via the rectal distension test using a high-resolution manometry system. Fecal primary BAs including cholic acid (CA) and chenodeoxycholic acid (CDCA), secondary BAs including deoxycholic acid (DCA), lithocholic acid (LCA), and ursodeoxycholic acid (UDCA) as well as the corresponding tauro- and glyco-BAs were examined by ultraperformance liquid chromatography coupled to tandem mass spectrometry. The gut microbiota was analyzed using 16S rRNA gene sequencing. Correlations between fecal BAs with clinical features and gut microbiota were explored.

RESULTS

Fecal CA (IBS-D: 3037.66 [282.82, 6917.47] nmol/g, HC: 20.19 [5.03, 1304.28] nmol/g; P < 0.001) and CDCA (IBS-D: 1721.86 [352.80, 2613.83] nmol/g, HC: 57.16 [13.76, 1639.92] nmol/g; P < 0.001) were significantly increased, while LCA (IBS-D: 1621.65 [58.99, 2396.49] nmol/g, HC: 2339.24 [1737.09, 2782.40]; P = 0.002] and UDCA (IBS-D: 8.92 [2.33, 23.93] nmol/g, HC: 17.21 [8.76, 33.48] nmol/g; P = 0.025) were significantly decreased in IBS-D patients compared to HCs. Defecation frequency was positively associated with CA (r = 0.294, P = 0.030) and CDCA (r = 0.290, P = 0.032) and negatively associated with DCA (r = -0.332, P = 0.013) and LCA (r = -0.326, P = 0.015) in IBS-D patients. In total, 23 of 55 IBS-D patients and 15 of 28 HCs participated in the visceral sensitivity test. The first sensation threshold was negatively correlated with CDCA (r = -0.459, P = 0.028) in IBS-D patients. Furthermore, the relative abundance of the family Ruminococcaceae was significantly decreased in IBS-D patients (P < 0.001), and 12 genera were significantly lower in IBS-D patients than in HCs (P < 0.05), with 6 belonging to Ruminococcaceae. Eleven of these genera were negatively correlated with primary BAs and positively correlated with secondary BAs in all subjects.

CONCLUSION

The altered metabolism of BAs in the gut of IBS-D patients was associated with diarrhea and visceral hypersensitivity and might be ascribed to dysbiosis, especially the reduction of genera in Ruminococcaceae.

Histamine-dependent interactions between mast cells, glia, and neurons are altered following early-life adversity in mice and humans

Early-life adversity contributes to the development of functional bowel disorders later in life through unresolved mechanisms. Here, we tested the hypothesis that early-life adversity alters anatomical and functional interactions between mast cells and enteric glia. The effects of early-life stress were studied using the neonatal maternal separation (NMS) stress mouse model. Anatomical relationships between mast cells and enteric glia were assessed using immunohistochemistry and mast cell reporter mice (Mcpt5^Cre;GCaMP5g-tdT). Immunohistochemistry was used to assess the expression of histamine, histamine 1 (H1) receptors, and glial fibrillary acidic protein. Functional responses of glia to mast cell mediators were assessed in calcium imaging experiments using Sox10^CreERT2;GCaMP5g-tdT mice and cultured human enteric glial cells. NMS increases mast cell numbers at the level of the myenteric plexus and their proximity to myenteric ganglia. Myenteric glia respond to mediators released by activated mast cells that are blocked by H1 receptor antagonists in mice and humans and by blocking neuronal activity with tetrodotoxin in mouse tissue. Histamine replicates the effects of mast cell supernatants on enteric glia, and NMS increases histamine production by mast cells. NMS reduces glial responses to mast cell mediators in mouse tissue, while potentiating responses in cultured human enteric glia. NMS increases myenteric glial fibrillary acidic protein expression and reduces glial process length but does not cause neurodegeneration. Histamine receptor expression is not altered by NMS and is localized to neurons in mice, but glia in humans. Early-life stress increases the potential for interactions between enteric glia and mast cells, and histamine is a potential mediator of mast cell-glial interactions through H1 receptors. We propose that glial-mast cell signaling is a mechanism that contributes to enteric neuroplasticity driven by early-life adversity.NEW & NOTEWORTHY Early-life adversity places an individual at risk for developing functional gastrointestinal disorders later in life through unknown mechanisms. Here, we show that interactions between mast cells and glia are disrupted by early-life stress in mice and that histamine is a potential mediator of mast cell-glial interactions.

Intestinal ultrasound as first-line investigation in low-risk gastrointestinal symptoms: a new model of care

BACKGROUND

Functional gut disorders (FGD) are common. Diagnosis is symptom based, although symptoms may be indistinguishable from inflammatory bowel disease. As a result of this, investigations are common, diagnostic yield is low. A streamlined novel model of care may reduce costly investigations.

AIM

To compare a new model of care for patients with low-risk gastrointestinal symptoms to a matched historical cohort.

METHODS

Data were prospectively collected over 12 months. General practitioner referrals for low-risk abdominal symptoms were triaged to a new multidisciplinary clinic structure utilising intestinal ultrasound. Outcomes were compared to the historical model in the preceding 12 months. Duration of care (time from referral to discharge), number of contact episodes and investigations ordered were reviewed.

RESULTS

Thirty-seven patients meeting strict inclusion criteria completed their care. Compared with the historical cohort, colonoscopies reduced from 0.7 to 0.05 per patient (P < 0.0001). Gastroenterology consults reduced from 1.5 to 1.2 (P = 0.303) and dietitian review increased from 0.8 to 1.5 (P < 0.0001). Total contact episodes reduced from 3.2 to 1.8 (P < 0.0001). Duration of care reduced from a median of 252 days to 130 days (interquartile ranges (IQR) 287 and 69, respectively; P < 0.0001). Time from first consultation to discharge reduced from 125 to 42 days (IQR 188 and 63; P < 0.0001).

CONCLUSION

This multidisciplinary approach to care of low-risk abdominal symptoms significantly reduced contact episodes, time in care and invasive investigations. It decreased costly gastroenterology consultation and increased allied health exposure. It demonstrates improved health service outcomes.

The effect of colonic tissue electrical stimulation and celiac branch of the abdominal vagus nerve neuromodulation on colonic motility in anesthetized pigs

BACKGROUND

Knowledge on optimal electrical stimulation (ES) modalities and region-specific functional effects of colonic neuromodulation is lacking. We aimed to map the regional colonic motility in response to ES of (a) the colonic tissue and (b) celiac branch of the abdominal vagus nerve (CBVN) in an anesthetized porcine model.

METHODS

In male Yucatan pigs, direct ES (10 Hz, 2 ms, 15 mA) of proximal (pC), transverse (tC), or distal (dC) colon was done using planar flexible multi-electrode array panels and CBVN ES (2 Hz, 0.3-4 ms, 5 mA) using pulse train (PT), continuous (10 min), or square-wave (SW) modalities, with or without afferent nerve block (200 Hz, 0.1 ms, 2 mA). The regional luminal manometric changes were quantified as area under the curve of contractions (AUC) and luminal pressure maps generated. Contractions frequency power spectral analysis was performed. Contraction propagation was assessed using video animation of motility changes.

KEY RESULTS

Direct colon ES caused visible local circular (pC, tC) or longitudinal (dC) muscle contractions and increased luminal pressure AUC in pC, tC, and dC (143.0 ± 40.7%, 135.8 ± 59.7%, and 142.0 ± 62%, respectively). The colon displayed prominent phasic pressure frequencies ranging from 1 to 12 cpm. Direct pC and tC ES increased the dominant contraction frequency band (1-6 cpm) power locally. Pulse train CBVN ES (2 Hz, 4 ms, 5 mA) triggered pancolonic contractions, reduced by concurrent afferent block. Colon contractions propagated both orally and aborally in short distances.

CONCLUSION AND INFERENCES

In anesthetized pigs, the dominant contraction frequency band is 1-6 cpm. Direct colonic ES causes primarily local contractions. The CBVN ES-induced pancolonic contractions involve central neural network.

Multiomics Study of Gut Bacteria and Host Metabolism in Irritable Bowel Syndrome and Depression Patients

Background and Aims

Irritable bowel syndrome (IBS) and depression have high tendencies of comorbidity. In particular, diarrhea-predominant IBS (IBS-D) and depression exhibit similar fecal microbiota signatures, yet little is known about their pathogenic mechanism. Here, we propose that the differences in structure and composition of IBS-D and depression gut microbiota give rise to different downstream functions, which lead to distinct clinical phenotypes via host metabolism and further influence the interaction of brain–gut axis.

Methods

We performed multiomics study, including fecal metagenome-wide sequencing and serum metabolomics profiling in 65 individuals with IBS-D (n=22), depression (n=15), comorbid patients (n=13), and healthy controls (n=15). We analyzed functional genes contributed by the primary genus and evaluated their correlations with clinical indices and host metabolites.

Results

Metagenomic analysis revealed 26 clusters of orthologous groups of protein (COG) categories consisting of a total of 4,631 functional genes. Trehalose and maltose hydrolase (COG1554) and fucose permease (COG0738) were the most relevant and enriched functional genes in the IBS-D patients; urease accessory proteins UreE (COG2371) was that in the depression patients. Context based genome annotation suggest that an alteration of Escherichia coli and Enterobacter cloacae in IBS-D and depression respectively may be responsible for the enrichment described above. Correlation with host metabolites, such as maltotriose and isomaltose in carbohydrate metabolism and anandamide in neuroactive metabolism, drew further connections between these findings.

Conclusions

These changes led us to propose a connection between genomic signatures and clinical differences observed in IBS-D and depression. Our findings provide further insights into the involvement of gut microbiota in diseases related to brain–gut disorder.

Parental, Perinatal, and Childhood Risk Factors for Development of Irritable Bowel Syndrome: A Systematic Review

Background/Aims

Adverse early life experiences are associated with the development of stroke, cancer, diabetes, and chronic respiratory and ischemic heart diseases. These negative experiences may also play a role in the development of irritable bowel syndrome (IBS)--a functional gastrointestinal disease. This review discusses the research to date on the parental, perinatal, and childhood risk and protective factors associated with the development of IBS.

Methods

A literature search was completed for studies published between 1966 and 2018 that investigated premorbid factors occurring during the perinatal and childhood periods as well as parental factors that were associated with the development of IBS.

Results

Twenty-seven studies fulfilled the review criteria. Risk factors that appeared in more than one study included: (1) parental IBS, substance abuse, parental punishment, and rejection as parental risk factors; (2) low birth weight as a perinatal risk factor; and (3) crowded living conditions in low-income families, childhood anxiety, depression, or child abuse as childhood risk factors. Protective factors for IBS were emotional warmth from the parents and being born to an older mother.

Conclusions

More effort is needed to identify what fetal and maternal factors are associated with low birth weight and IBS. A well-executed prospective birth cohort with a collection of bio-samples and functional data will provide a better understanding of how adversity and the interplay between genetics, epigenetics, and numerous risk factors affect the development of IBS.

Enteric Glia Modulate Macrophage Phenotype and Visceral Sensitivity following Inflammation

Mechanisms resulting in abdominal pain include altered neuro-immune interactions in the gastrointestinal tract, but the signaling processes that link immune activation with visceral hypersensitivity are unresolved. We hypothesized that enteric glia link the neural and immune systems of the gut and that communication between enteric glia and immune cells modulates the development of visceral hypersensitivity. To this end, we manipulated a major mechanism of glial intercellular communication that requires connexin-43 and assessed the effects on acute and chronic inflammation, visceral hypersensitivity, and immune responses. Deleting connexin-43 in glia protected against the development of visceral hypersensitivity following chronic colitis. Mechanistically, the protective effects of glial manipulation were mediated by disrupting the glial-mediated activation of macrophages through the macrophage colony-stimulating factor. Collectively, our data identified enteric glia as a critical link between gastrointestinal neural and immune systems that could be harnessed by therapies to ameliorate abdominal pain.

Therapy of IBS: Is a Low FODMAP Diet the Answer?

Irritable bowel syndrome (IBS) is the most prevalent functional gastrointestinal disorder with a worldwide prevalence of 11%. It is characterized by abdominal pain and altered bowel habits in the absence of underlying unique pathology. The condition is associated with poor quality of life and high use of healthcare resources required for management. The low FODMAP diet (LFD) is a recognized treatment for symptom management of IBS; however, approximately 30% of patients do not respond. The aim of this review was to understand the effectiveness and application of the LFD compared with other dietary and non-dietary interventions. Ten studies were included, eight of which assessed the LFD against other dietary interventions including traditional dietary advice, modified National Institute for Health and Care Excellence guidelines, a high FODMAP diet, gluten-free diet and Mediterranean diet, generalized dietary advice, probiotics, and a sham diet. Two studies compared a LFD to non-diet interventions of gut directed hypnotherapy or yoga. The findings clearly support the LFD as an effective treatment in IBS, and although it highlights the role for microbiota and current psychosocial state, it remains challenging to identify what combination of treatments may be best to ensure a personalized approach and overall higher response rates to IBS therapy.

Sex Hormones, BDNF, Leptin, and TGF-β1 in Females With IBS: A Pilot Investigation

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic gastrointestinal condition predominantly affecting the female sex, and is characterized by brain-gut axis dysregulation. Relevance of hormones along the hypothalamic-pituitary gonadal axis and hypothalamic-pituitary adrenal axis to IBS symptomatology remain unclear, as does the significance of other modulators including brain derived neurotrophic factor (BDNF), leptin, and transforming growth factor βeta 1 (TGF-β1).

METHODS

Females with IBS were compared with female healthy controls (HC) on age, race, hormonal contraceptive use, body mass index, adrenocorticotropic hormone, cortisol, estradiol, follicular stimulating hormone, luteinizing hormone, progesterone, total cholesterol, Center for Epidemiological Studies Depression Scale (CES-D) and Perceived Stress Scale (PSS). BDNF, leptin, and TGF-β1 were quantified using enzyme-linked immunosorbent assay. Descriptive statistics, non-parametric techniques, and regression analyses were performed.

RESULTS

Participants with IBS (n = 12) displayed higher estradiol (p = .027) than did HC (n = 21). Direction of associations among study variables often differed between groups: BDNF and progesterone in HC (r_s = .623) and in IBS (r_s = -.723). The relationship between log (CES-D) and log (estradiol) varied by IBS status (interaction term p = 0.019).

DISCUSSION

Elevated estradiol in participants with IBS, and differential patterns of biological and psychological indices between groups, encourages further inquiry on the relevance of sex hormones, BDNF, leptin, and TGF-β1 to symptoms of IBS. Future research endeavors should conduct longitudinal quantification of sex hormones with subjective symptom assessment to facilitate insight on the pathophysiology and female sex bias in IBS.

Global burden of irritable bowel syndrome: trends, predictions and risk factors

Irritable bowel syndrome (IBS) is one of the most common disorders of gut-brain interaction worldwide, defined according to patterns of gastrointestinal symptoms as described by the Rome diagnostic criteria. However, these criteria, developed with reference to research conducted largely in Western populations, might be limited in their applicability to other countries and cultures. Epidemiological data show a wide variation in the prevalence of IBS globally and more rigorous studies are needed to accurately determine any differences that might exist between countries as well as the potential explanations. The effects of IBS on the individual, in terms of their quality of life, and on health-care delivery and society, in terms of economic costs, are considerable. Although the magnitude of these effects seems to be comparable between nations, their precise nature can vary based on the existence of societal and cultural differences. The pathophysiology of IBS is complex and incompletely understood; genetics, diet and the gut microbiome are all recognized risk factors, but the part they play might be influenced by geography and culture, and hence their relative importance might vary between countries. This Review aims to provide an overview of the burden of IBS in a global context, to discuss future implications for the care of people with IBS worldwide, and to identify key areas for further research.

Improving Patient-Provider Relationships to Improve Health Care

Changes in our health care system have posed challenges for the patient-provider relationship (PPR) and may have negative consequences. For the clinician, due to lower reimbursements from third party payers, and increased administrative tasks such as the electronic medical record (EMR) and certification requirements, clinic visit time is now one-fifth that of decades ago. Clinicians may order diagnostic studies and imaging as a substitute for face to face time as it is seen to save time and increase relative value units (RVUs). As a result, the medical interview is very abbreviated, and the physical examination is disappearing. This occurs at the expense of the physician-patient relationship. Now there is limited time to gather relevant information, to understand the context of the illness, and address patient needs. For the clinician there is reduced satisfaction, loss of the meaningfulness of caring for patients, and possibly increased risk for burnout, and malpractice. This may lead to negative attitudes and behaviors toward patients, particularly for those with nonstructural diagnoses (eg, disorders of gut-brain interaction) which are given lower priority than those with acute or structural illness. In turn, patients experience a diminution in their role in the relationship and respond to adverse clinician behaviors with a lack of connection, frustration, and at times self-blame and stigmatization. To reverse this downward trend and re-establish an effective PPR changes are needed: 1) improving educational methods to provide skills to enhance patient-centered care, 2) incentivizing educators who teach and clinicians who practice patient-centered care, and 3) research support to demonstrate successful outcomes in satisfaction, adherence and clinical outcomes.

Ethnic differences in genetic polymorphism associated with irritable bowel syndrome

Genetic polymorphism is associated with irritable bowel syndrome (IBS) in terms of susceptibility and clinical manifestations. Previous studies have shown that genetic polymorphism might play a key role in the onset and progression of IBS by modulating components of its pathogenesis such as the gut-brain axis, gastrointestinal motility, inflammatory activity, and immune status. Although underlying pathophysiological mechanisms have not been fully clarified, the potential ethnic differences that are present in worldwide genetic studies of IBS deserve attention. This review surveyed numerous studies focusing on IBS-associated single nucleotide polymorphisms, and investigated the ethnic disparities revealed by them. The results demonstrate the need for more attention on ethnic factors in IBS-related genetic studies. Taking ethnic backgrounds into accounts and placing emphasis on disparities potentially ascribed to ethnicity could help lay a solid and generalized foundation for transcultural, multi-ethnic, or secondary analyses in IBS, for example, a meta-analysis. Broader genetic studies considering ethnic factors are greatly needed to obtain a better understanding of the pathophysiological mechanisms of IBS and to improve the prevention, intervention, and treatment of this disease.

Critical evaluation of animal models of visceral pain for therapeutics development: A focus on irritable bowel syndrome

The classification of chronic visceral pain is complex, resulting from persistent inflammation, vascular (ischemic) mechanisms, cancer, obstruction or distension, traction or compression, and combined mechanisms, as well as unexplained functional mechanisms. Despite the prevalence, treatment options for chronic visceral pain are limited. Given this unmet clinical need, the development of novel analgesic agents, with defined targets derived from preclinical studies, is urgently needed. While various animal models have played an important role in our understanding of visceral pain, our knowledge is far from complete. Due to the complexity of visceral pain, this document will focus on chronic abdominal pain, which is the major complaint in patients with disorders of the gut-brain interaction, also referred to as functional gastrointestinal disorders, such as irritable bowel syndrome (IBS). Models for IBS are faced with challenges including a complex clinical phenotype, which is comorbid with other conditions including anxiety, depression, painful bladder syndrome, and chronic pelvic pain. Based upon the multifactorial nature of IBS with complicated interactions between biological, psychological, and sociological variables, no single experimental model recapitulates all the symptoms of IBS. This position paper will contextualize chronic visceral pain using the example of IBS and focus on its pathophysiology while providing a critical review of current animal models that are most relevant, robust, and reliable in which to screen promising therapeutics to alleviate visceral pain and delineate the gaps and challenges with these models. We will also highlight, prioritize, and come to a consensus on the models with the highest face/construct validity.

The gut microbiome as a predictor of low fermentable oligosaccharides disaccharides monosaccharides and polyols diet efficacy in functional bowel disorders

PURPOSE OF REVIEW

Fermentable oligosaccharides disaccharides monosaccharides and polyols (FODMAP) dietary restriction ameliorates irritable bowel syndrome (IBS) symptoms; however, not all individuals with IBS respond. Given the gut microbiome's role in carbohydrate fermentation, investigators have evaluated whether the gut microbiome may predict low FODMAP diet efficacy.

RECENT FINDINGS

Gut microbiome fermentation, even to the same carbohydrate, is not uniform across all individuals with several factors (e.g. composition) playing a role. In both children and adults with IBS, studies are emerging suggesting the gut microbiome may predict low FODMAP diet efficacy. However, there is significant heterogeneity in the approaches (study population, microbiome assessment methods, statistical techniques, etc.) used amongst these studies.

SUMMARY

The gut microbiome holds promise as a predictor of low FODMAP diet efficacy. However, further investigation using standardized approaches to evaluate the microbiome while concomitantly assessing other potential predictors are needed to more rigorously evaluate this area.

SEPSIS. Educational and Best Practice Frontiers. Beyond the Boundaries of Fatality, Enhancing Clinical Skills and Precision Medicine

Dissemination and exploitation of knowledge regarding affordable clinical skills and innovative precision medicine, two current topics in active development in medicine, may contribute to improve also sepsis management. Sepsis is a life-threatening organ dysfunction due to a dysregulated host response to infection. Sepsis is strongly related to all body organs or to systemic diseases and to the quality of the best-practice in use, which is particularly critical in surgical or intervention techniques. Trauma, surgical and mini-invasive procedures, vascular or endoscopic interventions, otolaryngology, obstetrics-gynecological and urological procedures, malnutrition, dental, skin, chronic liver, kidney and respiratory disease are frequently involved. Accordingly, apart from the clinical risk analysis and management of the process of care, the actual factors that may be easily neglected are the techniques used, the personal skills of the health professionals and the quality of the equipment. The quest for biomarkers consistent with the unmet needs of medical doctors and of their patient and the efforts for overcoming bacterial antibiotic resistances are currently the main foci of medical research. In addition, in this regard, research and innovation would benefit from greater knowledge, skills and use of bioinformatics and omics. The caveats related to in-silico approaches must be flagged: algorithms may equally warrant scientific innovations or hide the lack of them; a patient is more than a set of covariates. Epidemiology and prevention includes all the actions suitable for achieving an adequate hygiene and immunization of populations and for safer hospital policies and procedures during Patients’ stays. In any subset, the most unresolved critical point in sepsis is a timely diagnosis. This is impaired by low degrees of suspicion for the possibility of emerging sepsis, by the shortage of use of the simplest microbiological testing but, equally or more, by the insufficient diffusion of non-invasive imaging skills suitable to detect and monitor the emerging sites and sources of infection. In primary care, in emergency facilities, in hospital wards and in intensive care units, inclusion of appropriate knowledge, skills, expertise and imaging equipment must be extended as much as possible. The low cost of UltraSound machines and of increasing bioinformatics literacy by e-learning, makes such investments affordable even in limited-resources contexts. Frontier educational and best practice intervention enhancing affordable clinical skills and innovative precision medicine may lead beyond the boundaries of fatal outcomes in sepsis.

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Gastrointestinal pain

Gastrointestinal (GI) pain - a form of visceral pain - is common in some disorders, such as irritable bowel syndrome, Crohn's disease and pancreatitis. However, identifying the cause of GI pain frequently represents a diagnostic challenge as the clinical presentation is often blurred by concomitant autonomic and somatic symptoms. In addition, GI pain can be nociceptive, neuropathic and associated with cancer, but in many cases multiple aetiologies coexist in an individual patient. Mechanisms of GI pain are complex and include both peripheral and central sensitization and the involvement of the autonomic nervous system, which has a role in generating the symptoms that frequently accompany pain. Treatment of GI pain depends on the precise type of pain and the primary disorder in the patient but can include, for example, pharmacological therapy, cognitive behavioural therapies, invasive surgical procedures, endoscopic procedures and lifestyle alterations. Owing to the major differences between organ involvement, disease mechanisms and individual factors, treatment always needs to be personalized and some data suggest that phenotyping and subsequent individual management of GI pain might be options in the future.

Altered profiles of fecal metabolites correlate with visceral hypersensitivity and may contribute to symptom severity of diarrhea-predominant irritable bowel syndrome

BACKGROUND

Fecal metabolites are associated with gut visceral sensitivity, mucosal immune function and intestinal barrier function, all of which have critical roles in the pathogenesis of irritable bowel syndrome (IBS). However, the metabolic profile and pathophysiology of IBS are still unclear. We hypothesized that altered profiles of fecal metabolites might be involved in the pathogenesis of IBS with predominant diarrhea (IBS-D).

AIM

To investigate the fecal metabolite composition and the role of metabolites in IBS-D pathophysiology.

METHODS

Thirty IBS-D patients and 15 age- and sex-matched healthy controls (HCs) underwent clinical and psychological assessments, including the IBS Symptom Severity System (IBS-SSS), an Italian modified version of the Bowel Disease Questionnaire, the Bristol Stool Form Scale (BSFS), the Hospital Anxiety and Depression Scale, and the Visceral Sensitivity Index. Visceral sensitivity to rectal distension was tested using high-resolution manometry system by the same investigator. Fecal metabolites, including amino acids and organic acids, were measured by targeted metabolomics approaches. Correlation analyses between these parameters were performed.

RESULTS

The patients presented with increased stool water content, more psychological symptoms and increased visceral hypersensitivity compared with the controls. In fecal metabolites, His [IBS-D: 0.0642 (0.0388, 0.1484), HC: 0.2636 (0.0780, 0.3966), P = 0.012], Ala [IBS-D: 0.5095 (0.2826, 0.9183), HC: 1.0118 (0.6135, 1.4335), P = 0.041], Tyr [IBS-D: 0.1024 (0.0173, 0.4527), HC: 0.5665 (0.2436, 1.3447), P = 0.018], Phe [IBS-D: 0.1511 (0.0775, 0.3248), HC: 0.3967 (0.1388, 0.7550), P = 0.028], and Trp [IBS-D: 0.0323 (0.0001, 0.0826), HC: 0.0834 (0.0170, 0.1759), P = 0.046] were decreased in IBS-D patients, but isohexanoate [IBS-D: 0.0127 (0.0060, 0.0246), HC: 0.0070 (0.0023, 0.0106), P = 0.028] was significantly increased. Only Tyr was mildly correlated with BSFS scores in all subjects (r = -0.347, P = 0.019). A possible potential biomarker panel was identified to correlate with IBS-SSS score (R 2 Adjusted = 0.693, P < 0.001). In this regression model, the levels of Tyr, Val, hexanoate, fumarate, and pyruvate were significantly associated with the symptom severity of IBS-D. Furthermore, visceral sensation, including abdominal pain and visceral hypersensitivity, was correlated with isovalerate, valerate and isohexanoate.

CONCLUSION

Altered profiles of fecal metabolites may be one of the origins or exacerbating factors of symptoms in IBS-D via increasing visceral sensitivity.

Tryptophan Metabolites in Irritable Bowel Syndrome: An Overnight Time-course Study

Background/Aims

Patients with irritable bowel syndrome (IBS) often report poor sleep quality. Whether poor sleep is associated with tryptophan (Trp) metabolites is unknown. We compared serum Trp metabolites in women with IBS and healthy controls (HCs) using targeted liquid chromatography mass spectrometry (LC-MS)-based profiling. In IBS only, we explored whether Trp metabolites are associated with IBS symptoms and subjective and objective sleep indices, serum cortisol, plasma adrenocorticotropic hormone (ACTH), and cortisol/ACTH levels.

Methods

Blood samples were obtained every 80 minutes in 21 HCs and 38 IBS subjects following an anticipation-of-public-speaking stressor during a sleep laboratory protocol. Subjects completed symptom diaries for 28 days. Adjacent values of metabolites were averaged to represent 4 time-periods: awake, early sleep, mid-sleep, and mid-to-late sleep. Thirteen of 20 targeted Trp metabolites were identified.

Results

Ten of 13 Trp metabolites decreased across the night, while nicotinamide increased in both groups. A MANOVA omnibus test performed after principal component analysis showed a significant difference in these 13 principal component (P = 0.014) between groups. Compared to HCs, nicotinamide levels were higher and indole-3-lactic acid levels lower in the IBS group. Melatonin and indole-3-acetic acid levels were associated with several subjective/objective sleep measures; decreased stool consistency/frequency and abdominal pain were positively associated with melatonin and serotonin in the IBS group. The kynurenine and kynurenic acid were associated with ACTH (positively) and cortisol/ACTH (negatively).

Conclusions

Nighttime Trp metabolites may provide clues to poor sleep and stress with IBS. Further study of the mechanism of metabolite action is warranted.

Consumption of a Fermented Milk Product Containing Bifidobacterium lactis CNCM I-2494 in Women Complaining of Minor Digestive Symptoms: Rapid Response Which Is Independent of Dietary Fibre Intake or Physical Activity

Background. Minor digestive symptoms are common and dietary approaches such as probiotic administration or fibre and fermentable carbohydrate intake adjustments are often recommended. A Fermented Milk Product (FMP) containing Bifidobacterium animalis subsp. lactis CNCM I-2494 and lactic acid bacteria has been shown to improve digestive symptoms after 4 weeks of consumption, but the speed of onset of this effect and its dependence on fibre intake or physical activity is unknown. To answer these questions, data from two previously published trials on FMP for minor digestive symptoms were combined. Methods. In total, 538 participants provided weekly assessments of bloating, abdominal pain/discomfort, flatulence, borborygmi/rumbling stomach from which a composite score was calculated. At baseline in one study (n = 336), dietary fibre consumption was recorded and physical activity classified as high, moderate or low. The speed of the FMP's effect was assessed by a repeated measure analysis of variance measuring the change from baseline for the composite score of digestive symptoms. Results. FMP consumption resulted in a significant decrease in the composite score of symptoms after only 2 weeks in both studies and the pooled data at week 1 (-0.35 [-0.69, 0.00]; p = 0.05), week 2 (-0.66 [-1.04, -0.27]; p < 0.001), week 3 (-0.49 [-0.89, -0.10]; p = 0.01) and week 4 (-0.46 [-0.88, -0.04]; p = 0.03). The interactions fibre intake-by-product group, physical activity-by-product group and time-by-product group were not statistically significant. Conclusion. FMP consumption leads to a rapid improvement in symptoms which is likely to encourage adherence to this dietary intervention. This effect is independent of dietary fibre and physical activity.

Hypothesis: Caco-2 cell rotational 3D mechanogenomic turing patterns have clinical implications to colon crypts

Colon crypts are recognized as a mechanical and biochemical Turing patterning model. Colon epithelial Caco-2 cell monolayer demonstrated 2D Turing patterns via force analysis of apical tight junction live cell imaging which illuminated actomyosin meshwork linking the actomyosin network of individual cells. Actomyosin forces act in a mechanobiological manner that alters cell/nucleus/tissue morphology. We observed the rotational motion of the nucleus in Caco-2 cells that appears to be driven by actomyosin during the formation of a differentiated confluent epithelium. Single- to multi-cell ring/torus-shaped genomes were observed prior to complex fractal Turing patterns extending from a rotating torus centre in a spiral pattern consistent with a gene morphogen motif. These features may contribute to the well-described differentiation from stem cells at the crypt base to the luminal colon epithelium along the crypt axis. This observation may be useful to study the role of mechanogenomic processes and the underlying molecular mechanisms as determinants of cellular and tissue architecture in space and time, which is the focal point of the 4D nucleome initiative. Mathematical and bioengineer modelling of gene circuits and cell shapes may provide a powerful algorithm that will contribute to future precision medicine relevant to a number of common medical disorders.