Calretinin-Positive Mucosal Innervation (C-mi) as a Potential Biomarker to Predict Fibrosis in Crohn’s Disease (CD): A Pilot Study

Abstract

Abstract Introduction/Objective There is no reliable biomarker to predict the degree of fibrosis in CD. Quantification of C-mi has been used as a surrogate for enteric neural structures in Hirschsprung disease. The quantity of C-mi at the proximal margin may correlate with the degree of fibrosis in resected CD. Methods Ileocolonic resection cases for 20 CD and 3 trauma (control) were retrieved. Cases with severe mucosal inflammation at the margins were excluded. The proximal and distal margin sections were subjected to calretinin immunohistochemistry. Random mucosal images were captured from scanned slides (x200, JPEG), submucosa was edited out, and C-mi was calculated by image processing and analysis. rC-mi was defined as the mean C-mi of proximal margin normalized by that of distal margin. Cases with rC-mi less than the mean rC-mi + 2 SD of the controls were excluded. The maximum thicknesses of submucosa and muscularis propria were measured at the most stenotic site, microscopically. Pearson’s correlation test and Student’s t-test were performed to correlate the parameters and compare the means, respectively. Results A total of 216 images were captured (mean 9.3 images per case; range 7 to 10). The mean rC-mi of CD (1.26) was greater than the controls (mean 0.43) (p<0.05). The mean rC-mi + 2 SD of the control group was 0.91, thus 2 CD cases were excluded from final analysis. The rC-mi of CD showed an inverse relationship with maximum submucosal thickness (mean 3.4 mm, range 0.2 to 5.9) at the site of stenosis (r=-0.47; p<0.05), but not with muscularis propria. Conclusion The rC-mi of CD was inversely correlated with submucosal fibrosis. Altered stromal integrity, impaired intercellular signaling, progressive reduction and loss of telocytes induced by submucosal fibrosis may reduce the regenerative capacity of enteric neural structures in CD. Therefore, a decreasing trend in rC-mi may predict fibrosis progression in CD.