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IBS-D shows unique immune cell exhaustion vs. other subtypes
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Patients with diarrhea-predominant irritable bowel syndrome appear to share a similar “exhaustion” in their T-cells during a symptom flare, differentiating them from other IBS subtypes, according to a letter published in Gut.
“For the first time, we’ve discovered that in patients with irritable bowel syndrome associated with diarrhea, their T-cells seem to be ‘out of puff’ or run down,” Patrick A. Hughes, PhD, of Adelaide Medical School and the South Australian Health and Medical Research Institute, said in a press release. “These normally active immune cells are less responsive to stimulation, secreting fewer mediators and dividing less. This type of response is often observed in chronic infections.”
Hughes and colleagues performed a longitudinal study to compare the immune function of 11 IBS patients when they were free of symptoms and when they experienced a symptom flare (mean age, 59 years; 10 women; 5 with IBS-D, 4 with IBS-A and 2 with IBS-C). The researchers analyzed blood samples and self-reported questionnaires from the participants throughout the yearlong study period.
They found that cytokine secretion and proliferative capacity were comparable in both the presence and absence of symptoms when analyzing all IBS subtypes together. However, after stratifying subtypes, only IBS-D patients showed reductions in both interferon- concentrations and proliferation of T helper cells during symptom flares.
Increased stress hormone production could explain the reduced T cell responsiveness, but this would be expected in all IBS subtypes during a symptom flare, the researchers wrote, adding that “alternatively, T cells may already be in an exhausted state and therefore less responsive to stimulation in IBS-D only, possibly due to a subclinical infection.”
While immune function is determined by the tissue environment, it remains uncertain whether the intestinal tissue of IBS patients would show similar results due to the difficulty in repeated intestinal tissue sampling, they noted.
“This is an important discovery, particularly as it helps to further distinguish between the different types of irritable bowel syndrome,” Hughes said in the press release. “This may eventually help us to better understand how to diagnose and treat the disease.”
Hughes and colleagues concluded that researchers should consistently provide IBS subtype and symptom profile data at the time of tissue sampling to accurately characterize immune profiles in IBS. – by Adam Leitenberger
Disclosures: The researchers report no relevant financial disclosures.
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