Serum fatty acid profile in subjects with irritable bowel syndrome

Metabolic biomarkers in irritable bowel syndrome diagnosis

Irritable bowel syndrome (IBS) is a chronic gastrointestinal (GI) disorder characterized by altered bowel habits and abdominal discomfort during defecation. It significantly impacts life quality and work productivity for those affected. Global data suggests a slightly higher prevalence in females than in males. Today, unambiguous diagnosis of IBS remains challenging due to the absence of a specific biochemical, histopathological, or radiological test. Current diagnosis relies heavily on thorough symptom evaluation. Efforts by the Rome committees have established standardized diagnostic criteria (Rome I-IV), improving consistency and clinical applicability. Recent studies in this framework, seem to have successfully employed metabolomics techniques to identify distinct metabolite profiles in breath and stool samples of IBS patients, differentiating them from healthy controls and those with other functional GI disorders, such as inflammatory bowel disease (IBD). Building on this success, researchers are investigating the presence of similar metabolites in easily accessible biofluids such as urine, potentially offering a less invasive diagnostic approach. Accordingly, this review focuses on key metabolites specifically detected in IBS patients' biological specimens, with a focus on urinary metabolites, using various methods, particularly mass spectrometry (MS)-based techniques, including gas chromatography-MS (GC-MS), liquid chromatography-tandem MS (LC-MS/MS), and capillary electrophoresis-MS (CE-MS) metabolomics assays. These findings may make provision for a new set of non-invasive biomarkers for IBS diagnosis and management.

A Mendelian randomization study on the effects of plasma lipids on irritable bowel syndrome and functional dyspepsia

Although functional gastrointestinal disorder (FGID) is a common clinical condition, its risk factors remain unclear. We performed a Mendelian randomization study to explore the association between plasma lipids and the risk of FGID. Instrumental variables closely related to six plasma lipids were obtained from the corresponding genome-wide association studies, and summary-level data on FGID, including irritable bowel syndrome (IBS) and functional dyspepsia (FD), were extracted from the FinnGen study. The primary inverse variance weighted method and other supplementary analyses were used to evaluate the causal relationship between diverse plasma lipids and FGID. For each increase in the standard deviation of triglyceride levels, there was a 12.0% increase in the risk of IBS rather than that of FD. Low- and high-density lipoprotein cholesterol, total cholesterol, apolipoprotein A, and apolipoprotein B levels were not associated with the risk of IBS or FD. Through this study, we identified the causal role of triglycerides in the pathogenesis of IBS, which could benefit further basic and clinical research.

Colonic mucosal biopsy location can not affect the results of mucosal metabolomics and mucosal microbiota analysis in IBS

Objective

To compare and analyze the mucosal metabolites and mucosal microbiota of different parts of colon in patients with IBS.

Methods

A total of 10 patients with IBS-D and six healthy controls (HC) were enrolled. All enrolled participants underwent two biopsies of the ileocecal and sigmoid colon during colonoscopy. Metabolomic profiling of one piece of tissue was conducted using desorption electrospray ionization-mass spectrometry (DESI-MS), and the gut flora of the other piece was examined using 16S rRNA sequencing. The metabolic profiles and flora of the ileocecal and sigmoid colonic mucosa in each group were further analyzed in this study.

Results

(1) Principal components analysis (PCA) indicated that mucosal metabolites did not differ in different parts of the colon in either the IBS-D or HC groups. (2) In the mucosal microbiome analyses, no differences between the microbiota of the two parts of the colon were found by using Principal Co-ordinates Analysis (PCoA). In IBS group, comparing with sigmoid mucosa, the chao1 richness indice was higher and the Shannon index was lower in the ileocecal mucosa (p = 0.40, p = 0.22). However, in the HC group, microbiome analysis of the ileocecal mucosa showed lower values for Chao 1 and Shannon indices than those of the sigmoid colon mucosa (p = 0.06, p = 0.86). (3) Compared with the HC group, 1,113 metabolic signal peaks were upregulated, whereas 594 metabolites were downregulated in the IBS-D samples. Moreover, the PCA of the metabolites showed significant separation between the IBS-D and HC groups. (4) Chao1 expression was significantly higher in the mucosal microbiota with IBS-D than in the HC (p = 0.03). The Shannon index was lower in IBS-D, but the difference was not statistically significant (p = 0.53). PCoA revealed a significant difference in the microflora structure between the IBS-D and HC groups.

Conclusion

The mucosal metabolic profile and mucosal flora structure of the colon were similar, despite different locations in IBS and healthy subjects. IBS had abnormal colonic mucosal metabolism and flora disturbances.

Non-pharmacologic strategies for the management of intestinal inflammation

Inflammatory bowel diseases, irritable bowel syndrome, and mucositis are characterized by intestinal inflammation, but vary according to their pathological mechanisms, severity, location, and etiology. Significant intestinal inflammation that occurs in these diseases induces weight loss, nutritional depletion, and gastrointestinal tract dysfunction. Nutritional support is important in alleviating symptoms and improving patients' quality of life. In this review, we summarize some nutritional components used to manage intestinal disorders. These include fatty acids, probiotics, parabiotics, postbiotics, prebiotics, synbiotics, and low FODMAP (LFD) diets. These components and LFD diets have been studied and clinical trials have been designed to develop new strategies to alleviate intestinal inflammation and improve the quality of life. Clinical trials on their use in intestinal inflammation do not allow firm conclusions to be drawn mainly because of the heterogeneity of the dose used and the study design or their inconclusive results. However, in the majority of cases, the use of omega-3, probiotics, parabiotics, postbiotics, prebiotics, synbiotics, and LFD improve the health.

Utilizing machine learning with knockoff filtering to extract significant metabolites in Crohn's disease with a publicly available untargeted metabolomics dataset

Metabolomic data processing pipelines have been improving in recent years, allowing for greater feature extraction and identification. Lately, machine learning and robust statistical techniques to control false discoveries are being incorporated into metabolomic data analysis. In this paper, we introduce one such recently developed technique called aggregate knockoff filtering to untargeted metabolomic analysis. When applied to a publicly available dataset, aggregate knockoff filtering combined with typical p-value filtering improves the number of significantly changing metabolites by 25% when compared to conventional untargeted metabolomic data processing. By using this method, features that would normally not be extracted under standard processing would be brought to researchers' attention for further analysis.

Application of metabolomics to the study of irritable bowel syndrome

The pathophysiology of irritable bowel syndrome and the detection of biomarkers of specific mechanisms and/or predictors of therapeutic response remain elusive. This roadblock reflects, in large part, the complexity and heterogeneity of the disorder. Recently, there has been growing evidence of a dietary and/or microbiome interaction with the host that may trigger symptoms in a subset of patients. While a number of techniques are available to examine these potential interactions, "omic" approaches such as metabolomics are becoming more widely used. Metabolomics measures hundreds and potentially thousands of known and unknown small molecule chemicals (metabolites) to provide a unique look into mechanisms that underlie symptom generation and potential predictors of therapeutic response. In this issue of the journal, Lee et al use nuclear magnetic resonance (NMR) to demonstrate the value of this approach to study IBS. This review examines the use of metabolomics to better understand IBS, focusing on what has been learned to date, practical and technical considerations, its potential for future research and how the study by Lee et al have contributed to these concepts.

Chain length of dietary fatty acids determines gastrointestinal motility and visceromotor function in mice in a fatty acid binding protein 4-dependent manner

Purpose

We hypothesize that different types of dietary fatty acids (FAs) affect gastrointestinal (GI) motility and visceromotor function and that this effect can be regulated by the fatty acid binding protein 4 (FABP4).

Methods

Mice were fed for 60 days with standard diet (STD), STD with 7% (by weight) coconut oil, rich in medium-chain FAs (MCFAs) (COCO), or with 7% evening primrose oil, rich in long-chain FAs (LCFAs) (EPO). In each group, half of the mice received FABP4 inhibitor, BMS309403 (1 mg/kg; i.p.) twice a week. Body weight (BW) and food intake were measured; well-established tests were performed to characterize the changes in GI motility and visceral pain. White adipose tissue and colonic samples were collected for cell culturing and molecular studies.

Results

COCO significantly increased GI transit, but not colonic motility. COCO and EPO delayed the onset of diarrhea, but none affected the effect of loperamide. EPO reduced BW and increased the visceromotor response (VMR) to colorectal distension (CRD). COCO and EPO reduced differentiation of preadipocytes. Treatment with BMS309403: (1) reversed the effects induced by COCO in physiological conditions and in mouse models of diarrhea; (2) prevented the effects of EPO on BW, VMR to CRD and castor oil-induced diarrhea; (3) affected proliferation of preadipocytes; (4) changed the expression of Fabp4 in colonic and adipocyte samples from COCO and EPO.

Conclusion

Modifying dietary intake of MCFAs and LCFAs may be used to control GI motility or visceral pain and thus modulate the symptoms of functional GI disorders. The effect is dependent on the expression of FABP4.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-02094-2) contains supplementary material, which is available to authorized users.

Comparison of the metabolomic profiles of irritable bowel syndrome patients with ulcerative colitis patients and healthy controls: new insights into pathophysiology and potential biomarkers

BACKGROUND

Evaluation of the metabolomic profile of patients with irritable bowel syndrome offers an opportunity to identify novel pathophysiological targets and biomarkers that could discriminate this disorder from related conditions.

AIM

To identify potential urinary biomarkers that discriminate irritable bowel syndrome patients from ulcerative colitis patients in remission and healthy controls and to explore the pathophysiology of irritable bowel syndrome using a metabolomic approach.

METHODS

Urine samples were collected from 39 irritable bowel syndrome patients, 53 ulcerative colitis patients in clinical remission and 21 healthy controls. Urinary metabolites were identified and quantified using direct infusion/liquid chromatography tandem mass spectrometry and gas-chromatography mass spectrometry.

RESULTS

Patients with irritable bowel syndrome had a unique urinary metabolome that could separate them from ulcerative colitis patients with an area under the curve = 0.99 (95% confidence interval 0.95-1.00). The most important metabolites for this separation were a group of amino acids and organic acids. In addition, subjects with irritable bowel syndrome could be discriminated from healthy controls using their metabolic fingerprints. Irritable bowel syndrome patients had lower urinary Phosphatidyl choline acyl-alkyl C38:6, dopamine and p-hydroxybenzoic acid than healthy controls. Levels of some urinary metabolites including histamine correlated significantly with irritable bowel syndrome symptom severity scores.

CONCLUSIONS

Irritable bowel syndrome patients have a unique urinary metabolomic profile compared to ulcerative colitis patients in clinical remission or healthy subjects. These data suggest that metabolomic profiling may provide important insights into pathophysiology and testable biomarkers to discriminate irritable bowel syndrome from other disorders that can mimic this condition and can be used to assess its severity and identify potential novel pathophysiological pathways.

Dietary Habits and Abdominal Pain-related Functional Gastrointestinal Disorders: A School-based, Cross-sectional Analysis in Greek Children and Adolescents

Background/Aims

The abdominal pain-related functional gastrointestinal disorders (AP-FGIDs) affect a significant proportion of the pediatric population and consist 1 of the most frequent causes for seeking medical advice. In this study, we aimed to assess the relation of dietary habits with the likelihood of AP-FGIDs.

Methods

This was a school-based, cross-sectional study approved by the Greek Government authorities, after obtaining informed consent by the legal representatives of the children. Diagnoses of AP-FGIDs were based on the Greek official translation of the Rome III questionnaire. Demographic, socioeconomic and dietary data were collected through self-reporting or parent-reporting questionnaires. Associations between the probability of AP-FGIDs and dietary practices were assessed after adjusting for known confounders through a multiple logistic regression analysis.

Results

A total of 1365 children (147 AP-FGIDs and 1218 controls, 52.4% females, mean age: 12.8 ± 2.8 years) were included. Multiple regression analysis identified the following statistically significant confounders: victimization, the presence of a person with a severe health problem at home, female sex, engaging in limited physical exercise, and living in a single adult family. Subsequently, logistic regression, adjusted for the abovementioned confounders, showed that reduced fish and increased junk food consumption were related to a higher likelihood of AP-FGIDs.

Conclusions

Children with AP-FGIDs report excessive junk-food and reduced fish intake compared to controls. Further studies are needed in order to clarify the nature of this observation.

Fatty acid components in Asian female patients with irritable bowel syndrome

Abdominal pain is one of the key symptoms of irritable bowel syndrome (IBS). Studies have indicated an increase in the incidence of IBS in Asia. However, yet the pathophysiology of this disease remains unknown. Women are more likely to develop the condition than men, especially the constipation-predominant type. Essential fatty acid (EFA) malnutrition is one of several theories discussing the mechanism of IBS.The authors hypothesized that significant EFA deficiency may cause abdominal pain in patients with IBS. However, because patterns in the oral intake of EFAs differ between cultures, the authors narrowed this study to examine the nutritional status of Asian female patients with IBSThe authors investigated Asian female patients with IBS and compared them with a group of healthy controls. Thirty patients with IBS and 39 healthy individuals were included in this study. The participants' age, height, weight, and waist size were recorded. The 24-item Hamilton Depression Rating Scale was documented. Both erythrocyte and plasma fatty acid content were analyzed through gas-liquid chromatography.The authors found that patients with IBS exhibited significantly higher scores for depression, higher proportions of plasma saturated fatty acids and monounsaturated fatty acids, and lower proportions of docosahexaenoic acid and total omega-3 polyunsaturated fatty acids in plasma are associated with IBS in Asian female patients. Further study is indicated to confirm the causality of this association.

Polyunsaturated Fatty Acids and Their Derivatives: Therapeutic Value for Inflammatory, Functional Gastrointestinal Disorders, and Colorectal Cancer

Polyunsaturated fatty acids (PUFAs) are bioactive lipids which modulate inflammation and immunity. They gained recognition in nutritional therapy and are recommended dietary supplements. There is a growing body of evidence suggesting the usefulness of PUFAs in active therapy of various gastrointestinal (GI) diseases. In this review we briefly cover the systematics of PUFAs and their metabolites, and elaborate on their possible use in inflammatory bowel disease (IBD), functional gastrointestinal disorders (FGIDs) with focus on irritable bowel syndrome (IBS), and colorectal cancer (CRC). Each section describes the latest findings from in vitro and in vivo studies, with reports of clinical interventions when available.

Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults

Studies reporting blood levels of the omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were systematically identified in order to create a global map identifying countries and regions with different blood levels. Included studies were those of healthy adults, published in 1980 or later. A total of 298 studies met all inclusion criteria. Studies reported fatty acids in various blood fractions including plasma total lipids (33%), plasma phospholipid (32%), erythrocytes (32%) and whole blood (3.0%). Fatty acid data from each blood fraction were converted to relative weight percentages (wt.%) and then assigned to one of four discrete ranges (high, moderate, low, very low) corresponding to wt.% EPA+DHA in erythrocyte equivalents. Regions with high EPA+DHA blood levels (>8%) included the Sea of Japan, Scandinavia, and areas with indigenous populations or populations not fully adapted to Westernized food habits. Very low blood levels (≤4%) were observed in North America, Central and South America, Europe, the Middle East, Southeast Asia, and Africa. The present review reveals considerable variability in blood levels of EPA+DHA and the very low to low range of blood EPA+DHA for most of the world may increase global risk for chronic disease.

[Correlation of the microbiota and intestinal mucosa in the pathophysiology and treatment of irritable bowel, irritable eye, and irritable mind syndrome]

Accumulating clinical evidence supports co-morbidity of irritable bowel, irritable eye and irritable mind symptoms. Furthermore, perturbation of the microbiota-host symbiosis (dysbiosis) is considered a common pathogenic mechanism connecting gastrointestinal, ocular and neuropsychiatric symptoms. Consequently, maintaining or restoring microbiota-host symbiosis represents a new approach to treat these symptoms or to prevent their relapses. Current treatment approach assigned a primary role to live probiotics alone or in combination with prebiotics to enhance colonization of beneficial bacteria and to strengthen the symbiosis. However, several papers showed major benefits of heat-killed probiotics as compared to their live counterparts on both intestinal and systemic symptoms. Recently, in addition to killing probiotics, in a proof of concept study lysates (fragments) of probiotics in combination with vitamins A, B, D and omega 3 fatty acids were successfully tested. These findings suggested a conceptual change in the approach addressed to both the microbiota and host as targets for intervention.

DHA serum levels were significantly higher in celiac disease patients compared to healthy controls and were unrelated to depression

Objectives

Celiac disease (CD), a genetically predisposed intolerance for gluten, is associated with an increased risk of major depressive disorder (MDD). We investigated whether dietary intake and serum levels of the essential n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA) found in fatty fish play a role in this association.

Methods

Cross-sectional study in 71 adult CD patients and 31 healthy volunteers, matched on age, gender and level of education, who were not using n-3 PUFA supplements. Dietary intake, as assessed using a 203-item food frequency questionnaire, and serum levels of EPA and DHA were compared in analyses of covariance, adjusting for potential confounders. Serum PUFA were determined using gas chromatography.

Results

Mean serum DHA was significantly higher in CD patients (1.72 mass%) than controls (1.28 mass%) after multivariable adjustment (mean diff. 0.45 mass%; 95% CI: 0.22–0.68; p = 0.001). The mean intake of EPA plus DHA did not differ between CD patients and controls after multivariable adjustment (0.15 and 0.22 g/d, respectively; p = 0.10). There were no significant differences in intake or serum levels of EPA and DHA between any of the CD patient groups (never depressed, current MDD, minor/partially remitted MDD, remitted MDD) and controls.

Conclusions

Patients on a long term gluten-free diet had similar intakes of EPA plus DHA compared to controls. Contrary to expectations, DHA serum levels were significantly higher in CD patients compared to healthy controls and were unrelated to MDD status.

Bifidobacterium breve with α-linolenic acid and linoleic acid alters fatty acid metabolism in the maternal separation model of irritable bowel syndrome

The aim of this study was to compare the impact of dietary supplementation with a Bifidobacterium breve strain together with linoleic acid & α-linolenic acid, for 7 weeks, on colonic sensitivity and fatty acid metabolism in rats. Maternally separated and non-maternally separated Sprague Dawley rats (n = 15) were orally gavaged with either B. breve DPC6330 (10(9) microorganisms/day) alone or in combination with 0.5% (w/w) linoleic acid & 0.5% (w/w) α-linolenic acid, daily for 7 weeks and compared with trehalose and bovine serum albumin. Tissue fatty acid composition was assessed by gas-liquid chromatography and visceral hypersensitivity was assessed by colorectal distension. Significant differences in the fatty acid profiles of the non-separated controls and maternally separated controls were observed for α-linolenic acid and arachidonic acid in the liver, oleic acid and eicosenoic acid (c11) in adipose tissue, and for palmitoleic acid and docosahexaenoic acid in serum (p<0.05). Administration of B. breve DPC6330 to MS rats significantly increased palmitoleic acid, arachidonic acid and docosahexaenoic acid in the liver, eicosenoic acid (c11) in adipose tissue and palmitoleic acid in the prefrontal cortex (p<0.05), whereas feeding B. breve DPC6330 to non separated rats significantly increased eicosapentaenoic acid and docosapentaenoic acid in serum (p<0.05) compared with the NS un-supplemented controls. Administration of B. breve DPC6330 in combination with linoleic acid and α-linolenic acid to maternally separated rats significantly increased docosapentaenoic acid in the serum (p<0.01) and α-linolenic acid in adipose tissue (p<0.001), whereas feeding B. breve DPC6330 with fatty acid supplementation to non-separated rats significantly increased liver and serum docosapentaenoic acid (p<0.05), and α-linolenic acid in adipose tissue (p<0.001). B. breve DPC6330 influenced host fatty acid metabolism. Administration of B. breve DPC6330 to maternally separated rats significantly modified the palmitoleic acid, arachidonic acid and docosahexaenoic acid contents in tissues. The effect was not observed in non-separated animals.

Perceived food hypersensitivity: a review of 10 years of interdisciplinary research at a reference center

Perceived food hypersensitivity is a prevalent, but poorly understood condition. In this review article, we summarize narratively recent literature including results of our 10 years' interdisciplinary research program dealing with such patients. The patients (more than 400) included in our studies were all adults referred to a university hospital because of gastrointestinal complaints self-attributed to food hypersensitivity. Despite extensive examinations, food allergy was seldom diagnosed. The majority of the patients fulfilled the diagnostic criteria for irritable bowel syndrome. In addition, most suffered from several extra-intestinal health complaints and had considerably impaired quality of life. However, psychological factors could explain only approximately 10% of the variance in the patients' symptom severity and 90% of the variance thus remained unexplained. Intolerance to low-digestible carbohydrates was a common problem and abdominal symptoms were replicated by carbohydrate ingestion. A considerable number of patients showed evidence of immune activation by analyses of B-cell activating factor, dendritic cells and "IgE-armed" mast cells. Multiple factors such as immune activation, disturbed intestinal fermentation, enteric dysmotility, post-infectious changes and "local" allergy in the gut as well as psychological disturbances may play a role in the pathophysiology of perceived food hypersensitivity. Hence, our results support the view that management of these patients should be interdisciplinary.