Irritable bowel syndrome (IBS) is the most prevalent functional gastrointestinal (GI) disorder, which presents with abdominal pain and changes in the bowel habits. Although the exact cause of IBS remains uncertain, some studies have shown that the inflammation and cytokine imbalance may act as potential etiological factors. The aim of our study is to compare the serum levels of interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor-alpha (TNF-α) in patients with IBS with the healthy controls. The other aim of this study is to evaluate possible association between above-mentioned cytokines and IBS subtypes.

Seventy-four IBS patients diagnosed based on Rome III criteria and 75 gender and age-matched healthy controls were included in this study. Cytokines were measured in the serum using enzyme-linked immunosorbent assays (ELISA).

Patients were classified into groups of IBS with diarrhea (IBS-D): 34, IBS with constipation (IBS-C): 29, and IBS with mixed symptoms (IBS-M): 11. The serum levels of IL-6, IL-8 and TNF-α were significantly higher in patients with IBS as compared to controls (P<0.001). There was no difference in serum levels of cytokines based on IBS subtypes.

Higher serum level of IL-6, IL-8 and TNF-α in IBS suggests an important role of cytokines as immune mediators in the pathogenesis of this functional GI disorder. To understand any association between cytokines and IBS subtypes, further investigations with larger sample sizes are desired.