Pathological changes of the anatomical structure and markers of the limbal stem cell niche due to inflammation

Purpose: The corneoscleral limbus is the site of corneal epithelial stem cells (SC). The aim of this study is to evaluate the expression of different SC markers in the normal human limbus and to determine how this is affected by inflammation. Methods: Corneoscleral specimens from healthy and inflamed donor eyes were examined by immunohistochemistry/immunofluorescence for p63, vimentin, laminin 5, integrin alpha 6, beta 1, beta 4, ABCG2, desmoglein 3, connexin 43, N-cadherin, and cytokeratins 12 and 15. The distribution and anatomic structure of the limbal crypts and the percentage of SC marker antigens in healthy donors were analyzed. In inflamed tissues, we evaluated the anatomic structure of the limbal epithelial crypt (LEC) and the positivity for SC markers. Results: In normal limbus, the niche structures were distributed differently. The variability of their number correlated with the percentage of p63 positivity. Integrin beta 1 staining directly correlated with p63 positivity while the remaining proteins were variably and widely distributed. Double staining for p63 and vimentin did not reveal any co-localization. In inflamed eyes, the basal cells in the crypts were "stretched" and surrounded by inflammatory cells, and only a few SC markers were still present. Conclusions: Diseases involving the limbus may result in marked changes of expression of SC markers within the LEC and also alter the crypt structure.