The relationship between adherens junction and tight junction and clinical symptoms in patients with diarrhea predominant irritable bowel syndrome

Abstract

Objective: To investigate the association between adherens junction proteins E-cadherin and β-catenin and tight junction protein claudin-2 and clinical symptoms in patients with diarrhea predominant irritable bowel syndrome (IBS-D). Methods: Cecal biopsy tissues were collected from IBS-D patients (n=26) according to Rome Ⅲ criterion and healthy controls (n=26). The duration of symptoms, abdominal pain score and mean weekly bowel movements were recorded. Colorectal dilatation combined with restraint stress were applied to establish visceral hypersensitivity rat model. Abdominal contraction reflex (AWR) was applied to assess the visceral sensitivity in rats. The stool frequency within 1 hour was recorded after establishing the rat model. The expression of E-cadherin、β-catenin and claudin-2 were assessed by Western blot and immunofluorescence microscopy. Intercellular ultrastructure was observed by transmission electron microscopy. Results: Compared with the healthy controls, the protein expression of E-cadherin and β-catenin in cecal epithelium in IBS-D patients were significantly lower (P=0.015 and P=0.005, respectively), while claudin-2 was significantly higher (P=0.000). Reduced E-cadherin and β-catenin expression was associated high abdominal pain score (r=-0.463, P=0.017 and r=-0.407, P=0.039). The lower expression of β-catenin was associated with longer duration of symptoms (r=-0.458, P=0.019). The protein expression of E-cadherin and ß-catenin in the cecal epithelium of the visceral hypersensitivity rats were significantly lower (P=0.004 and P=0.003, respectively), while claudin-2 was significantly higher (P=0.008). Reduced E-cadherin and ß-catenin expression was associated high visceral sensitivity in IBS-D rats (r=-0.639, P=0.047 and r=-0.888, P=0.001). Conclusions: Intercellular ultrastructure alterations well as cecal β-catenin and E-cadherin protein expression decrease and are associated with high abdominal pain score in IBS-D patients and hypersensitivity rats. β-catenin is further associated with prolonged duration of symptoms in IBS-D patients. The expression of E-cadherin and β-catenin may play a vital role in visceral sensitivity and intestinal barrier dysfunction in IBS-D.