Source: Gut  |  Posted 9 years ago

Patients with acute gastroenteritis who develop irritable bowel syndrome (IBS) have an enhanced peripheral inflammatory response in comparison with infected patients who do not develop IBS.

An international team of researchers from Singapore, Canada and the United Kingdom say that the observed higher expression of interleukin-1beta (IL-1beta) messenger RNA (mRNA) is in keeping with clinical observations that patients with more severe infective gastroenteritis are more likely to develop post-infectious IBS (PI-IBS). At the same time, the response contrasts with previous work that suggested behavioural factors predicted the development of PI-IBS, say the investigators, led by Dr. K-A. Gee of National University Hospital in Singapore.

The pathways may not be mutually exclusive, say the researchers: "On the contrary, there is growing evidence that behavioural and peripheral inflammatory processes converge to influence disease expression, and supporting examples are available in animal-based studies."

Approximately 25% of patients with infectious diarrhoea develop chronic bowel disturbances that resemble IBS, they explain. Expressions of IL-1beta and its receptor antagonist (IL-1ra) were measured in eight patients who developed PI-IBS and in seven patients who did not. The aim was to see if an inflammatory process underpins the pathogenesis of PI-IBS. A group of 18 healthy volunteers who had not had acute gastroenteritis in the previous two years acted as normal controls.

Sequential rectal biopsy samples were taken during and three months after acute gastroenteritis. Reverse transcriptase-polymerase chain reaction was used to assay IL-1beta and IL-1ra gene expressions. The level of expression was quantified by optical densitometry.

PI-IBS patients had significantly greater expression of IL-1beta mRNA than did patients who returned to normal bowel habits aster infection. As well, increases in IL-1beta mRNA was seen in the PI-IBS patients three months post-infection.

Patients who did not develop PI-IBS did not have significantly different IL-1beta mRNA expression from healthy controls at three months. Patients who developed PI-IBS did.

There were no significant changes in IL-1ra expression in any of the three groups at three months, the investigators note.