Background: We previously demonstrated that morphologic defects of ileal Paneth cells correlate with multiple susceptible genetic variants, the presence of granuloma, and clinical outcome in Crohn's disease. These studies were performed using uninvolved areas of resection specimens. To develop Paneth cell phenotype as a prognostic biomarker in Crohn's disease, further characterization is necessary. Specifically, effects of disease activity, phenotype duration, and the minimal crypt number that would allow for accurate Paneth cell phenotyping are unknown.
Methods: We compared Paneth cell phenotypes in (1) 46 cases with paired involved and uninvolved sections; (2) 36 cases with multiple ileal resections over time; (3) "virtual biopsies" by randomly selecting 10 to 60 crypts from 85 surgical cases where 250 crypts had been analyzed; and (4) 26 cases with resection and biopsy performed within 1 year.
Results: In paired resection specimens, the Paneth cell phenotypes in the uninvolved areas correlated with those seen in involved areas (P < 0.0001) and also predicted the presence of granuloma (P = 0.042). Importantly, the Paneth cell phenotype remained stable over time (P < 0.0001). By mathematical analyses, a minimum of 40 crypts was required to generate results equivalent to those using resection specimens. Finally, there was good correlation in Paneth cell phenotypes in biopsy specimens and resection specimens obtained within 1 year (P = 0.0004).
Conclusions: Accurate Paneth cell phenotypes can be assessed using biopsy materials with the caveat that sufficient well-oriented crypts exist in the specimen. This advance will extend the potential clinical application of this novel stratification platform.