Imbalance of tumor necrosis factor-α, interleukin-8 and interleukin-10 production evokes barrier dysfunction, severe abdominal symptoms and psychological disorders in patients with irritable bowel syndrome-associated diarrhea

The present study aimed to explore the correlation between cytokine expression of tumor necrosis factor a (TNF-alpha), interleukin (IL)-8 and IL-10 with occludin production, abdominal symptoms and psychological factors in patients with irritable bowel syndrome-associated diarrhea (IBS-D). A total of 42 IBS-D patients and 20 healthy controls were included, which were recruited from QiLu Hospital in China. ELISA and immunohistochemical analysis were performed for evaluating the cytokines (TNF-alpha, IL-8 and IL-10) and occludin protein levels in the peripheral blood mononuclear cells (PBMCs) of all subjects. In addition, the abdominal symptoms and psychological status were assessed in IBS-D patients. Levels of TNF-alpha and IL-8 in the PBMCs of patients with IBS-D were significantly higher than those in the controls (P<0.001 and P=0.007, respectively), while IL-10 levels were significantly reduced in patients with IBS-D (P=0.047). Occludin production was significantly reduced in patients with IBS-D as compared with that in the controls (P<0.001). In patients with IBS-D, levels of TNF-alpha and IL-8 were negatively correlated with occludin levels (r=-0.34, P=0.028; r=-0.52, P<0.001, respectively). IL-10 showed a negative correlation with occludin production (r=0.05, P=0.748). Furthermore, TNF-alpha, IL-8 and IL-10 levels were significantly correlated with symptoms scores (r=0.74, P<0.001; r=0.55, P<0.001; r=-0.80, P<0.001, respectively) in patients with IBS-D. Within the IBS-D group, TNF-a expression was significantly increased in patients with a self-rating depression scale (SDS) score >= 50 (P=0.004) as compared with that in patients with an SDS score <50. Furthermore, IL-8 was significantly increased in IBS-D patients with a self-rating anxiety scale (SAS) or SDS score >= 50 (P=0.016, P=0.008, respectively) as compared with that in patients scoring <50. In conclusion, the results of the present study suggested that in IBS-D, an imbalance of cytokine production evoked colonic epithelial barrier dysfunction, abdominal symptoms and psychological disorders.