Rectal afferent hypersensitivity and compliance in irritable bowel syndrome: differences between diarrhoea-predominant and constipation-predominant subgroups.

OBJECTIVES: To evaluate the differences in rectal compliance and sensory thresholds for the urge to defecate and discomfort between irritable bowel syndrome (IBS) subgroups and controls, and to correlate these parameters with rectal symptoms. METHODS: A total of 38 IBS patients [Rome II criteria; 19 diarrhoea-predominant IBS (D-IBS), 16 constipation-predominant IBS (C-IBS), three with alternating diarrhoea and constipation IBS (Alt-IBS)] and 10 controls were studied. A barostat was used to measure rectal compliance and sensory thresholds, in the 'unprepared' rectum. The thresholds for the urge to defecate and discomfort were determined using phasic rectal balloon distension in a double random staircase sequence. RESULTS: D-IBS had significantly lower rectal compliance and threshold for the urge to defecate compared with controls [4 ml/mmHg interquartile range (IQR) 3.99 versus 8.4 ml/mmHg IQR 5.69; P=0.001; 8 mmHg IQR 6 versus 20 mmHg IQR 4; P=0.003]. D-IBS also had significantly lower rectal compliance and threshold for the urge to defecate compared with the C-IBS group (5.8 ml/mmHg IQR 4.61; P=0.027; 16 mmHg IQR 12; P=0.003). The volume at the threshold for discomfort was significantly lower in D-IBS compared with controls (163 ml IQR 99.5 versus 212 ml IQR 147.25; P=0.016). The severity of abdominal pain and rectal symptoms showed a significantly negative correlation with rectal sensory thresholds. CONCLUSION: This study shows that the sensory threshold for the urge to defecate and rectal compliance is significantly lower in D-IBS compared with C-IBS and controls. The consequent inability to tolerate rectal faecal loading may account for the symptoms of the passage of frequent, small-volume stools in D-IBS patients.

Food-specific IgG4 antibody-guided exclusion diet improves symptoms and rectal compliance in irritable bowel syndrome.

OBJECTIVE: Dietary modification improves symptoms in irritable bowel syndrome (IBS). Identification of offending foods by dietary elimination/re-challenge is cumbersome. IgG4 antibodies to common food antigens are elevated in IBS. The aim of this article was to evaluate the effect of exclusion diet based on IgG4 titres on IBS symptoms and rectal sensitivity and compliance. MATERIALS AND METHODS: The study comprised 25 patients with IBS (3 M, 22 F, mean age 43 years, Rome II criteria). IgG4 titres to 16 foods (milk, eggs, cheese, wheat, rice, potatoes, chicken, beef, pork, lamb, soya bean, fish, shrimps, yeast, tomatoes and peanuts) were measured. Foods with titres >250 microg/l were excluded for 6 months. Symptom severity was assessed with a previously validated questionnaire at baseline, at 3 months and at 6 months. Rectal compliance and sensitivity were measured in 12 patients at baseline and at 6 months. RESULTS: IgG4 antibodies to milk, eggs, wheat, beef, pork and lamb were commonly elevated. Significant improvement was reported in pain severity (p < 0.001), pain frequency (p = 0.034), bloating severity (p = 0.001), satisfaction with bowel habits (p = 0.004) and effect of IBS on life in general (p = 0.008) at 3 months. Symptom improvement was maintained at 6 months. Rectal compliance was significantly increased (p = 0.011) at 6 months but the thresholds for urge to defecate/discomfort were unchanged. CONCLUSIONS: Food-specific IgG4 antibody-guided exclusion diet improves symptoms in IBS and is associated with an improvement in rectal compliance.

Food-specific serum IgG4 and IgE titers to common food antigens in irritable bowel syndrome.

INTRODUCTION: Food hypersensitivity is a common perception among irritable bowel syndrome (IBS) patients. Data from dietary elimination and food challenge studies support an etiopathological role of diet in IBS, but there are no well-established tests to identify food hypersensitivity. AIM: To compare IgG4 and IgE titers to common food antigens in IBS and controls. METHOD: One hundred and eight IBS [52 diarrhea-predominant (D-IBS); 32 constipation-predominant (C-IBS); 24 alternating (Alt-IBS)], and 43 controls were included in the study. IgG4 and IgE titers and skin prick testing (SPT) to 16 common foods including milk, eggs, cheese, wheat, rice, potatoes, chicken, beef, pork, lamb, fish, shrimps, soya bean, yeast, tomatoes, and peanuts were measured. RESULTS: IBS had significantly higher IgG4 titers (mug/L) to wheat (395 IQR +/- 1,011 vs 0 IQR +/- 285, p < 0.001), beef (1,079 IQR +/- 930 vs 617 IQR +/- 435, p < 0.001), pork (481 IQR +/- 379 vs 258 IQR +/- 496, p < 0.001), and lamb (241 IQR +/- 460 vs 167 IQR +/- 232, p= 0.009) compared to controls. These differences were maintained across all three subgroups. The antibody titers to potatoes, rice, fish, chicken, yeast, tomato, and shrimps were not significantly different. No significant difference in IgE titers was observed between IBS and controls. SPT was positive for only a single antigen in 5 of 56 patients tested with the same panel of foods. No correlation was seen between the pattern of elevated IgG4 antibody titers and patients' symptoms. CONCLUSION: Serum IgG4 antibodies to common foods like wheat, beef, pork, and lamb are elevated in IBS patients. In keeping with the observation in other atopic conditions, this finding suggests the possibility of a similar pathophysiological role for IgG4 antibodies in IBS.