Overlapping irritable bowel syndrome and inflammatory bowel disease: less to this than meets the eye?

Acute colitis chronically alters immune infiltration mechanisms and sensory neuro-immune interactions

OBJECTIVE

Little is understood regarding how disease progression alters immune and sensory nerve function in colitis. We investigated how acute colitis chronically alters immune recruitment and the impact this has on re-activated colitis. To understand the impact of disease progress on sensory systems we investigated the mechanisms underlying altered colonic neuro-immune interactions after acute colitis.

DESIGN

Inflammation was compared in mouse models of health, acute tri-nitrobenzene sulphonic acid (TNBS) colitis, Remission and Reactivated colitis. Cytokine concentrations were compared by ELISA in-situ and in explanted colon tissue. Colonic infiltration by CD11b/F4-80 macrophage, CD4 T_HELPER (T_H) and CD8 T_CYTOTOXIC (T_C) and α₄β₇ expression on mesenteric lymph node (MLN) T_H and T_C was determined by flow cytometry. Cytokine and effector receptor mRNA expression was determined on colo-rectal afferent neurons and the mechanisms underlying cytokinergic effects on high-threshold colo-rectal afferent function were investigated using electrophysiology.

RESULTS

Colonic damage, MPO activity, macrophage infiltration, IL-1β and IL-6 concentrations were lower in Reactivated compared to Acute colitis. T_H infiltration and α₄β₇ expression on T_H MLN was increased in Remission but not Acute colitis. IFN-γ concentrations, T_H infiltration and α₄β₇ expression on T_H and T_C MLN increased in Reactivated compared to Acute colitis. Reactivated explants secreted more IL-1β and IL-6 than Acute explants. IL-6 and TNF-α inhibited colo-rectal afferent mechanosensitivity in Remission mice via a BK_Ca dependent mechanism.

CONCLUSIONS

Acute colitis persistently alters immune responses and afferent nerve signalling pathways to successive episodes of colitis. These findings highlight the complexity of viscero-sensory neuro-immune interactions in painful remitting and relapsing diseases.

Irritable bowel syndrome and inflammatory bowel disease overlap syndrome: pieces of the puzzle are falling into place

Irritable bowel syndrome (IBS), a common gastrointestinal disorder involving the gut-brain axis, and inflammatory bowel disease (IBD), a chronic relapsing inflammatory disorder, are both increasing in incidence and prevalence in Asia. Both have significant overlap in terms of symptoms, pathophysiology, and treatment, suggesting the possibility of IBS and IBD being a single disease entity albeit at opposite ends of the spectrum. We examined the similarities and differences in IBS and IBD, and offer new thoughts and approaches to the disease paradigm.

The prevalence of irritable bowel syndrome-type symptoms in paediatric inflammatory bowel disease, and the relationship with biochemical markers of disease activity

BACKGROUND

A large proportion (25-46%) of adults with inflammatory bowel disease in remission has symptoms of irritable bowel syndrome (IBS), which are thought to reflect ongoing inflammation. Data on paediatric inflammatory bowel disease patients are lacking.

AIM

To investigate (i) the prevalence of IBS-type symptoms in paediatric inflammatory bowel disease patients in remission and (ii) the relationship of IBS-type symptoms with biochemical markers of disease activity.

METHODS

This cross-sectional study included all patients (<18 years) with Crohn's disease or ulcerative colitis attending the out-patient clinic of one of three Dutch hospitals between March 2014 and June 2015. Clinical disease activity was determined using the abbreviated-PCDAI or PUCAI. Biochemical disease activity was assessed using faecal calprotectin and serum CRP. IBS-symptoms were assessed using physician-administered Rome III-questionnaires.

RESULTS

We included 184 patients (92 female; mean age: 14.5 years) (Crohn's disease: 123, ulcerative colitis: 61). The prevalence of IBS-type symptoms in children with inflammatory bowel disease in clinical remission was 6.4% (95% CI: 2.5-11.1%; Crohn's disease: 4.5%; ulcerative colitis: 10.8%). Prevalence of IBS-type symptoms in children with faecal calprotectin <250 μg/g was 16.1% (95% CI: 7.6-25.8%; Crohn's disease: 16.7%; ulcerative colitis: 10.8%). No difference in faecal calprotectin or CRP was found between patients in clinical remission with or without IBS-type symptoms (faecal calprotectin: IBS+ median 58 μg/g, IBS- 221 μg/g, P = 0.12; CRP: IBS+ median 1.4 mg/L, IBS- 1.1 mg/L, P = 0.63).

CONCLUSIONS

The prevalence of IBS-type symptoms in children with inflammatory bowel disease is highly dependent on the definition of remission. Nonetheless, the prevalence is much lower than that previously reported in studies in adult inflammatory bowel disease patients. IBS-type symptoms appear to be unrelated to gastrointestinal inflammation.