Indication of immune activation in patients with perceived food hypersensitivity

Effects of varying dietary content of fermentable short-chain carbohydrates on symptoms, fecal microenvironment, and cytokine profiles in patients with irritable bowel syndrome

BACKGROUND

A diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is increasingly recommended for patients with irritable bowel syndrome (IBS). We aimed to investigate the effects of a blinded low-FODMAP vs high-fructo-oligosaccharides (FOS) diet on symptoms, immune activation, gut microbiota composition, and short-chain fatty acids (SCFAs).

METHODS

Twenty patients with diarrhea-predominant or mixed IBS were instructed to follow a low-FODMAP diet (LFD) throughout a 9-week study period. After 3 weeks, they were randomized and double-blindly assigned to receive a supplement of either FOS (FODMAP) or maltodextrin (placebo) for the next 10 days, followed by a 3-week washout period before crossover. Irritable bowel syndrome severity scoring system (IBS-SSS) was used to evaluate symptoms. Cytokines (interleukin [IL]-6, IL-8, and tumor necrosis factor alpha) were analyzed in blood samples, and gut microbiota composition (16S rRNA) and SCFAs were analyzed in fecal samples.

KEY RESULTS

Irritable bowel syndrome symptoms consistently improved after 3 weeks of LFD, and significantly more participants reported symptom relief in response to placebo (80%) than FOS (30%). Serum levels of proinflammatory IL-6 and IL-8, as well as levels of fecal bacteria (Actinobacteria, Bifidobacterium, and Faecalibacterium prausnitzii), total SCFAs, and n-butyric acid, decreased significantly on the LFD as compared to baseline. Ten days of FOS supplementation increased the level of these bacteria, whereas levels of cytokines and SCFAs remained unchanged.

CONCLUSIONS AND INFERENCES

Our findings support the efficacy of a LFD in alleviating IBS symptoms, and show changes in inflammatory cytokines, microbiota profile, and SCFAs, which may have consequences for gut health.

Extra-intestinal symptoms in patients with irritable bowel syndrome: related to high total IgE levels and atopic sensitization?

Objective We have previously found that high levels of total IgE, but not atopic sensitization, was a significant predictor for functional gastrointestinal (GI) symptoms. In this study, we aimed to assess the prevalence of extra-intestinal symptoms in IBS patients, and explore their relation to total IgE levels and atopic sensitization. Materials and methods Seventy-one patients with functional GI complaints were included. Severity of GI symptoms, fatigue and musculoskeletal pain was evaluated using the following questionnaires: IBS-Severity Scoring System (IBS-SSS), Fatigue Impact Scale (FIS), FibroFatigue Scale (FFS), and Visual Analog Scales (VAS) for musculoskeletal pain. Levels of total IgE and specific IgE-antibodies were analyzed. Results Fatigue and musculoskeletal pain were demonstrated in 78.9 and 43.7% of the patients, respectively. IBS-SSS scores were significantly correlated with fatigue scores and musculoskeletal pain. Patients with fatigue and musculoskeletal pain had significantly higher IBS-SSS scores than patients without fatigue and musculoskeletal pain. Total IgE levels were significantly higher in IBS patients compared to a healthy control group from a previous study. However, neither total IgE nor atopic sensitization was significantly associated with extra-intestinal symptoms. Conclusions IBS, fatigue, and musculoskeletal pain were significantly associated. Total IgE levels were higher in IBS patients than healthy controls, but not related to intestinal or extra-intestinal symptom severity. Atopy was not associated with any of the co-morbidities. Thus, the clinical significance of high IgE levels in IBS remains unclear and further studies are warranted to explore a common underlying mechanism for the co-morbid triad of IBS, fatigue, and musculoskeletal pain.

Functional Gastrointestinal Symptoms Are Associated with Higher Serum Total IgE Levels, but Less Atopic Sensitization

BACKGROUND

The relation of gastrointestinal (GI) complaints to IgE-mediated allergy is not well understood. Increased numbers of "IgE-armed" mast cells have been observed in duodenal mucosa of patients with functional GI complaints.

AIMS

To explore whether total IgE and atopic sensitization were associated with functional GI complaints.

METHODS

Levels of serum total and specific IgE and GI complaints were measured in 161 patients and in a general population sample of 478 persons. Standard inhalant allergens were measured in the patient group, and selected inhalant allergens in the general population. GI complaints were assessed by two standardized questionnaires. The associations between GI complaints and total IgE were analyzed in multiple regression models.

RESULTS

GI complaints were positively associated with higher total IgE levels (all: b = 0.028, p = 0.012; patient group: b = 0.038, p = 0.072; general population: b = 0.038, p = 0.005), but negatively associated with atopic sensitization (all: b = -11.256, p = 0.181; patient group: b = -85.667, p < 0.001; general population: b = -14.394, p = 0.083). The relationship between total IgE and GI complaints was consistent among sensitized and non-sensitized persons, among men and women, and across age groups.

CONCLUSION

Serum total IgE was positively associated with GI complaints, while atopic sensitization was inversely associated with GI complaints. This suggests that IgE-mediated immunology plays a role in the pathophysiology of functional GI complaints. The biological mechanisms reflected in higher total IgE levels, but less atopic sensitization, warrant further studies.