Clinical Significance Of Tryptase And α1-antitrypsin Expression In The Colon Mucosa Of Patients With Diarrhea-predominant Irritable Bowel Syndrome

Aim: To detect the contents of tryptase andα1-antitrypsin in the ascending colonic mucosa in patients with diarrhea-predominant irritable bowel syndrome (IBS-D), and to explore their role in the pathogenesis of this disorder.Methods: Twenty patients with IBS-D fulfilling the Rome III criteria and ten healthy volunteers were included in this study. Three biopsy samples were collected from the ascending colon during the colonoscopy, and then incubated in 2ml HBSS 37℃for 1h. The concentrations of tryptase andα1-antitrypsin in the supernatants were detected by enzyme-linked immunosorbent assay (ELISA). The proteins and mRNA of tryptase andα1-antitrypsin in the mucosa were detected by Western blotting and RT-PCR respectively.The relationship between gastrointestinal symptom rating scale (GSRS) and the contents of tryptase in the ascending colon were also analyzed.Results: The contents of tryptase in ascending colon mucosa supernatants of the IBS-D patients detected by ELISA were (0.070±0.011)ug/g tissue,while in the healthy volunteers were (0.043±0.006) ug/g tissue. There was a significant difference between them( P =0.000). Hower, the mean content ofα1-antitrypsin in the supernatants of the IBS-D patients (2.36±1.05)mg/g tissue detected by ELISA was not different from that in the healthy volunteers (2.68±1.19)mg/g tissue ( P=0.455). The contents of tryptase were positively correlated with GSRS score( r = 0.592, P = 0.008).The relative expression of tryptase mRNA in the ascending colon mucosa of the IBS-D patients detected by RT-PCR was 0.83±0.06,while in the healthy volunteers was 0.23±0.08. The difference has a statistical significance( P =0.000). The relative expression ofα1-antitrypsin mRNA in the ascending colon mucosa of the IBS-D patients detected by RT-PCR was 1.02±0.19,while in the healthy volunteers was 0.97±0.17. There was not a significant difference between them( P =0.413). The relative expression of mRNA of tryptase was positively correlated with GSRS score also( r = 0.520, P = 0.009).The relative expression of tryptase in the ascending colon mucosa of the IBS-D patients detected by Western blotting was 0.53±0.09,while in the healthy volunteers was 0.23±0.08. The difference of the results has statistical sense( P =0.000). The relative expression ofα1-antitrypsin in ascending colon mucosa of the IBS-D patients detected by Western blotting was 0.81±0.15,while in the healthy volunteers was 0.80±0.11. The difference of the results has no statistical sense( P =0.761). The relative expression of tryptase was positively correlated with GSRS score( r = 0.421, P = 0.032).Conclusion: The expression of tryptase in the ascending colon of IBS-D patients increased, but ofα1-antitrypsin not, and this change is related to gastrointestinal symptoms. Therefore, excessive expression of tryptase in the colon may be involved in the pathogenesis of IBS-D.