Jun Kim Ph.D.
As a major mechanism of cellular defense in the immune system, inflammation usually protects the body from pathogens by inhibiting their growth and actively removing them by recruiting immune cells. However, when it goes beyond a tolerable limit it can damage the body. Dysregulated inflammation has been implicated in different diseases such as autoimmune disease and cancer. In addition to small intestine bacterial overgrowth (SIBO) and gut motility, inflammation is another important concept in irritable bowel syndrome (IBS). It was mentioned here that IBS does not produce the destructive inflammation that is found in inflammatory bowel disease (IBD). However, studies do suggest less severe dysregulation of inflammation[1]. This article will discuss some of the recent findings for the association between inflammation and IBS, and the potential benefits of probiotics for IBS through regulating inflammation.
Although routine examinations do not show significant inflammatory abnormalities in IBS patients, more sensitive and quantitative analyses have indicated alterations[2]. Studies have shown low-grade inflammation throughout the small intestine and the colon in IBS patients[3–5]. They exhibit increase of certain immune cells, such as mast cells, lymphocytes, dendritic cells[6, 7]. Also, increased level of inflammatory molecules, including interleukins and histamine, have been detected, which is known to cause alteration in gut motility and sensory perception [4, 8]. The reported evidence for the association between inflammation and IBS suggest that treating low-level inflammation may improve IBS symptoms. Based on this idea different clinical studies have been conducted, but currently benefits of this approach do not seem to be clear [9, 10]. As discussed in a previous article, this may be due to the fact there are multiple causes for IBS and an approach that acts though multiple mechanisms may be required.
A study that investigated the Bifidobacterium infantis probiotic on rats showed that the treatment may have had a role in reducing proinflammatory markers [11]. O’Mahony et al. performed a study where the patients diagnosed with IBS were treated with B. infantis [12]. This treatment group showed a significant reduction in the symptoms of IBS. Also an inflammatory marker (the interleukin-10/-12 ratio), which is abnormal in IBS patients in the proinflammatory state, was normalized in the treatment group, suggesting that the mechanism of action of this particular probiotic may involve an immune-modulating effect.
IBS is a multifactorial disorder, and some of the potential causes were discussed in this article and the two previous articles on IBS (IBS + Gut Motility). Currently, the relationship between the factors contributing to IBS is not clear, and treating only one of the factors may lead to limited efficacy. In this regard, probiotics treatment may be a particularly important option to be investigated as it has been demonstrated to act through a number of different mechanisms.
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