[Changes in the proliferation and apoptosis of colonic epithelial cells in correlation with histologic activity of...

The imbalance of epithelial cell kinetics in ulcerative colitis can lead to several gastrointestinal disorders such as ulcers or neoplasias. The changes of epithelial cell kinetics caused by the inflammatory process have not been fully and uniformly described. Aim of the study was to compare the rate of epithelial cell apoptosis and proliferation within colonic crypts considering the histological activity of ulcerative colitis.

Formalin fixed paraffin embedded biopsy specimens from mild, moderate, and severe active inflammation of ulcerative colitis and from normal colonic tissue were observed. Number of cases (apoptosis/proliferation): normal: 8/10; mild UC: 8/10; moderate: 8/8; severe: 12/8. For detecting apoptosis the TUNEL-POD-DAB method, and for proliferation the PCNA (PC-10)-Biotin-Streptavidin-AEC method were used, constrained with haematoxylin. Using light microscope, at least 500 crypt epithelial cells were encountered axially in whole, well-orientated colonic crypts per each specimen.

The number of TUNEL positive epithelial cells were significantly higher in moderate and severe active inflammation compared to each other and to normal (p < 0.0001). Between mild inflammation and normal significant alteration was not found. The number of PCNA positive cells were significantly higher in each groups of inflammation compared to normal or each other.

These results demonstrate that there is a strong correlation between the histological activity of ulcerative colitis and elevated crypt epithelial cell turnover, although the alterations in proliferation develop in the earlier stages of inflammation.