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

Colonic mucosal eosinophilia and immunohistochemical expression of COX-2 and NF-kB in patients with irritable bowel syndrome

BACKGROUND

There is growing evidence that eosinophilic infiltration can release mediators which are harmful to the intestinal epithelium in patients with irritable bowel syndrome (IBS). Although cyclooxygenase 2 (COX-2) and nuclear factor-kappa beta (NF-kB) expression had been previously reported to increase in many inflammatory conditions, there is a paucity in data investigating their expressions in IBS. Our aim was to evaluate colonic mucosal eosinophilia and immunohistochemical expression of COX-2 and NF-kB in patients with irritable bowel syndrome.

METHODS

A total of 80 patients who met the inclusion criteria of IBS based on Rome IV symptoms questionnaire were subjected to abdominal ultrasound, laboratory investigations, serum immunoglobulin E (IgE) level assessment and colonoscopic examination. Immunohistochemistry was performed to detect COX-2 and NF-kB expression in colonic biopsies obtained from IBS patients.

RESULTS

Histopathological examination showed that 60 colonic biopsy specimens (75%) showed few mixed inflammatory cells ≤3 cells/ HPF, 12 biopsy specimens (15%) showed eosinophilic infiltration ≥25 eosinophils/HPF and 8 biopsy specimens (10%) showed severe lymphocytic infiltration and aggregation. Colonic eosinophilic infiltrate was significantly higher among patients presented with IBS-D subtype. Serum IgE was significantly higher among patients with colonic eosinophilic infiltrate than the others. In IBS-D patients, colonic mucosa showed positive expression of COX-2 and NF-kB in 52.1% and 81.25% of cases, respectively.

CONCLUSION

Patients with IBS -particularly IBS-D subtype- should undergo colonoscopy and biopsy to exclude underlying inflammatory pathology. Moreover, patients with positive COX-2 and NF-kB need further evaluation and follow-up.

Physiological mechanisms of unexplained (functional) gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) encompass a range of complex conditions with similar clinical characteristics and no overt pathology. Recent recognition of sub-clinical pathologies in FGIDs, in conjunction with physiological and biochemical abnormalities including increased intestinal permeability, microbial profile alterations, differences in metabolites and extra-intestinal manifestations of disease, call into question the designation of these conditions as 'functional'. This is despite significant heterogeneity in both symptom profile and specifics of reported physiological abnormalities hampering efforts to determine defined mechanisms that drive onset and chronicity of symptoms. Instead, the literature demonstrates these conditions are disorders of homeostatic imbalance, with disruptions in both host and microbial function and metabolism. This imbalance is also associated with extraintestinal abnormalities including psychological comorbidities and fatigue that may be a consequence of gastrointestinal disruption. Given the exploitation of such abnormalities will be crucial for improved therapeutic selection, an enhanced understanding of the relationship between alterations in function of the gastrointestinal tract and the response of the immune system is of interest in identifying mechanisms that drive FGID onset and chronicity. Considerations for future research should include the role of sex hormones in regulating physiological functions and treatment responses in patients, as well as the importance of high-level phenotyping of clinical, immune, microbial and physiological parameters in study cohorts. There is opportunity to examine the functional contribution of the microbiota and associated metabolites as a source of mechanistic insight and targets for therapeutic modulation.

Association between Irritable Bowel Syndrome and Allergic Diseases: To Make a Case for Aeroallergen

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease and the most common cause of prolonged abdominal pain and bowel disturbances in the developed world. While initially thought to be functional or psychosomatic in nature, IBS is now recognized as a heterogeneous group of conditions. A subset of IBS patients and patients with allergic diseases share some characteristic inflammatory features. In fact, atopic children show an increased likelihood of developing IBS as adults. Given these findings, a subset of IBS may be suffering from allergy-related gut diseases. In this review, we present the allergy-related comorbidities of IBS, including genetic, environmental, and immunologic factors. We discuss studies demonstrating an increased sensitization of IBS patients to aeroallergens compared to food allergens. We then postulate potential pathophysiological mechanisms underlying both IBS and aeroallergens in the gut, followed by potential implications in the screening and treatment of allergies in IBS patients.

Altered levels of cytokines in patients with irritable bowel syndrome are not correlated with fatigue

Introduction

A considerable number of patients with gastrointestinal complaints attributable to irritable bowel syndrome (IBS) have shown evidence of immune activation. Fatigue is also frequently reported by IBS patients and the condition is considered as a common comorbidity of IBS. Therefore, it is interesting to see whether these two conditions share the same pathophysiological mechanism.

Aims

To investigate the potential role of cytokine profiles in patients with IBS and the relationship between cytokine profiles and fatigue.

Materials and methods

Thirty-eight patients with IBS (32 females, 6 males, age range 18-70 years) and 22 healthy individuals (control group) (17 females, 5 males, age range 24-42 years) were included. IBS was diagnosed according to Rome III criteria, and severity of IBS symptoms and fatigue were evaluated using the Irritable Bowel Syndrome-Severity Scoring System (IBS-SSS) and Fatigue Impact Scale (FIS), respectively. FIS scores of 25 or higher were defined as fatigue. Blood samples were also taken, and the Luminex^® platform (Cytokine Human Ultrasensitive Magnetic 10-Plex Panel) was used for quantifying human cytokines' profile (granulocyte-macrophage colony-stimulating factor, interferon-γ, interleukin [IL]-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, and tumor necrosis factor [TNF]-α) in serum.

Results

The serum levels of IL-5, IL-6, IL-10, and TNF-α were significantly higher in patients with IBS compared to healthy controls (p=0.003, p=0.011, p=0.007, and p=0.02, respectively). Conversely, serum levels of cytokine IL-1β were significantly higher in the control group (p=0.03). The findings were consistent when comparing nonatopic patients with controls. Fatigue was demonstrated in 84.2% of the IBS patients. Scores of IBS-SSS were not significantly correlated with FIS scores (r=0.2, p=0.19), and they were not significantly different in patients with FIS scores >25 compared to patients with FIS scores <25 (p=0.11). None of the cytokine levels were significantly different in IBS patients with FIS scores >25 compared to IBS patients with FIS scores <25. Moreover, the cytokine levels in participants did not vary significantly between patients with diarrhea, constipation, or mixed bowel habits in multiple comparisons of patients.

Conclusions

The cytokines IL-5, IL-6, IL-10, and TNF-α may contribute to the development of IBS. However, serum levels of cytokines were not significantly different in IBS patients with fatigue compared with IBS patients without fatigue. Thus, the significance of cytokine levels may be less important than anticipated in search of common underlying mechanisms, and other factors should be explored in future studies.