Increased small intestinal apoptosis in coeliac disease

Background-Coeliac disease (CD) mucosa is flattened despite epithelial hyperproliferation. Aims-To establish mechanisms of cell loss in CD. Patients-14 controls, 17 active CD patients, and 16 maintained with gluten free diet. Methods-Programmed cell death was examined in small intestinal biopsy specimens by staining fragmented DNA using terminal uridine deoxynucleotidyl nick end labelling (TUNEL), in comparison with haematoxylin and eosin stained adjacent sections. Double staining with anti-CD45 antibodies determined the origin of apoptotic cells. Apoptosis was graded from 1-3 (<5, 5-20, >20% respectively). Proliferating cells, immunostained by Ki-67 (MIB-1) antibody, were counted. Results-Apoptotic cells were seen rarely by haematoxylin and eosin but more readily by TUNEL. In controls, 1 . 4+/-0 . 2% of epithelial cells were apoptotic (mean grade 1 . 1), mainly located in the upper villus. In active CD, frequent apoptotic cells were distributed throughout the crypt-villus unit (mean grade 2 . 4), decreasing after treatment to 1 . 1 (p<0 . 001) even when still histologically abnormal. CD45 antibodies rarely stained apoptotic cells in active CD. The number of TUNEL positive cells correlated with proliferating cell number (p<0 . 001). Conclusion-Enterocyte apoptosis is greatly increased in untreated CD, correlates with proliferation, and falls to normal with a gluten free diet, before histological improvement. Increased apoptosis may be responsible for villous atrophy in CD.