A new review of published research into irritable bowel syndrome has revealed that the digestive disorder is associated with changes in the immune system and the permeability of the intestinal wall.
Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders diagnosed by doctors and its various symptoms often have a severe impact on patients' lives. Sadly, a lack of understanding of what causes and maintains the condition has hampered the development of effective treatments so those affected are often left doing their best to manage their symptoms with minimal medical assistance.
Recognizing this knowledge gap regarding the etiology of IBS - and also that recent studies have pointed to the involvement of immune activation - a team of scientists at Clermont University, France, undertook a review of published medical studies. The focus of the study was to determine whether immune activation and increased intestinal permeability (colloquially known as leaky gut syndrome) were more common among IBS patients than in healthy individuals.
The French team of scientists searched the medical literature for studies that had compared IBS patients to healthy control participants. The search parameters were designed to specifically bring up studies which had looked at changes in immune markers and intestinal permeability.
To ensure a comprehensive overview of the available data was achieved the investigators included studies with a wide range of methodologies. For example, the research analyzed by the scientists included studies that had looked at differences in blood and stool markers between IBS patients and healthy controls, as well as those that looked for physical differences in the GI tract.
After collecting and analyzing of all the data was complete the investigators noted a "modest" association between immune activation and increased intestinal permeability and a diagnosis of IBS.
The overall picture from the studies included in the review was that IBS patients tended to show signs of immune activation more often than healthy individuals. Specifically, increased numbers of lymphocytes (white blood cell's involved in 'adaptive' immunity) and mast cells (which release histamine and other inflammatory chemicals during allergic reactions) were evident in IBS patients. There were also differences in levels of cytokines (immune signaling chemicals) between the two groups - IBS patients tending to show cytokine profiles associated with increased inflammation.
In addition it was seen that increased intestinal permeability was more common in IBS patients.
The reasons for these associations are complex and not entirely clear. Previous research has shown various factors such as small intestinal bacterial overgrowth (SIBO), food sensitivities, dietary habits and psychological stress are all possible contributors in individual IBS patients.
The researchers noted that although there was a general picture of immune activation and increased intestinal permeability in IBS patients, there was wide variability and each individual was unique.
Given the above it may well be that no single treatment will ever be effective for the majority of IBS patients but rather each patient should be thoroughly assessed and treatment tailored to their specific needs.
Source: Matricon J Meleine M Gelot A Piche T Dapoigny M Muller E Ardid D (2012) Review article: associations between immune activation, intestinal permeability and the irritable bowel syndrome Alimentary Pharmacology & Therapeutics doi: 10.1111/apt.12080. [Epub ahead of print]
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