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 α (TNF‑α), 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‑α, 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‑α 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‑α 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‑α, 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‑α 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.