Expression and Clinical Significance of Elafin in Inflammatory Bowel Disease

Background: The expression of elafin in inflammatory bowel disease (IBD) is controversial. Here, we detected the expression of elafin in the peripheral blood and colonic mucosa of patient with IBD and then explored its role and value in assessing the activity and severity of IBD. Materials and Methods: Sixty-eight patients with IBD were selected as an experimental group. The control group included 38 healthy individuals. The expression of elafin mRNA in peripheral blood leukocytes and in serum was detected by qRT-PCR and enzyme-linked immunosorbent assay, respectively. The inflamed and noninflamed tissues were collected by colonoscopy. The expression of elafin in the intestinal mucosa was determined by immunohistochemistry staining and qRT-PCR. The expression of elafin between groups and among each stage of IBD was compared. The correlations of elafin expression with erythrocyte sedimentation rate and C-reactive protein were determined by Spearman's correlation analysis and with clinical disease activity indices (Best Crohn's Disease Activity Index and modified Mayo scores) by Pearson's correlation analysis. Results: Elafin mRNA levels decreased significantly in active ulcerative colitis (UC) but increased in remission UC. However, in Crohn's disease (CD), we did not detect the aforementioned significant differences. Although serum IL-8 levels increased, serum elafin concentrations decreased both in UC and in CD, but the differences among stages were not significant. The expression of elafin in the inflamed colonic mucosa in both CD and UC was lower than that in the normal mucosa in controls and lower than that in the noninflamed mucosa in IBD. Moreover, the relative expression of elafin mRNA in peripheral blood leukocytes in UC was negatively correlated with erythrocyte sedimentation rate, C-reactive protein, and modified Mayo scores, and in CD, it was negatively correlated with Best Crohn's Disease Activity Index scores. Conclusions: Elafin decreased in active patients with IBD and was negatively correlated with disease activity, suggesting that elafin may play a protective role and could be used as an index to evaluate disease activity in IBD.