Defects in the immune system in individuals with irritable bowel syndrome (IBS) is the major reason why sufferers have ongoing issues with pain, and one reason why some painkillers do not provide satisfactory relief to these patients, according to a recent study by researchers in Australia.

IBS is a functional gastrointestinal (GI) disorder leading to bowel changes, pain and discomfort. It is estimated that IBS affects 3% to 20% of the adult population; however, only 5% to 7% of adults have been diagnosed, according to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.   Clinicians have further classified IBS into four subtypes based on a person’s usual stool consistency: IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), mixed IBS (IBS-M) and unsubtyped IBS (IBS-U).  Unexplained GI pain is common to all four subtypes and often has the greatest impact on quality of life.

Scientists in the Nerve-Gut Research Laboratory at the University of Adelaide in Australia obtained blood samples from more than 100 people, half with IBS and half without the condition in order to determine if substance that mediate pain were different in the two groups.  Specifically they analyzed the amount of endorphins and immune mediators that play a role in controlling pain, and found that these chemicals were deficient in subjects with IBS.

The researchers demonstrated that the mechanisms involved in GI pain, and the differences between the immune pain response in healthy people and in those with IBS are different. The gut contains immune effector cells that normally release opioid chemicals that block pain, but production and release of these opioid chemicals is defective in patients with IBS.  Researchers hope that targeted treatment strategies can now be developed to specifically relieve pain associated with IBS.

Reference:  Published online in Brain, Behavior, and Immunity (2014 July [Epub ahead of print]).

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