FAS AND FAS-LIGAND CO-EXPRESSION BY SMALL INTESTINE EPITHELIAL CELLS OF CELIAC PATIENTS.

Abstract

79 There is evidence indicating that the mucosal damage, leading to villus atrophy, observed in celiac disease (CD) is caused by the induction of enterocytes apoptosis (1). Aim. Analyse whether DNA fragmentation of enterocytes correlates with villus atrophy and investigate the mechanisms involved in the apoptotic process. Methods. Frozen duodenal biopsies from untreated CD with villus atrophy (UCD)(n=12) or without villus atrophy [LGE,low-grade enteropathy(n=8)(2), with only patches of villus atrophy], treated CD(TCD)(n=12) and controls(n=17) were analysed for DNA fragmentation [TUNEL method, number of positive cells/100 enterocytes, (3)], and by immunocytochemistry (4) for expression of FAS[mouse MoAb M3 and M38 FAS specific, 1:30, Immunex, Seattle WA,USA(5), undetectable (0-1+) vs high (2+) expression in more than 70% of enterocytes], FAS-Ligand (FAS-L) [rat biotinylated MoAb FAS-L specific 804-009B-T100, 1:50, Alexis Corp, USA (6), undetectable (0-1+) vs high (2+) expression in more than 70% of enterocytes] and Ki67 antigen [1:25 DAKO, Copenhagen, Denmark, number of positive cells/100 crypt enterocytes]. Results. High DNA fragmentation of enterocytes was observed only in UCD [mean 46.6, (SD 19.6) p<0.001 vs 5.5 (6.3) in controls and vs 2.8(2.4) in TCD]; in LGE the pattern was significantly lower than in UCD [1.5(0.7), p<0.001] and high DNA fragmentation was detected only in patches of villus atrophy. Ki67 expression paralleled that of DNA fragmentation[58.2(11.8) in UCD, p<0.001 vs controls 7(5.7), vs TCD 4.0(2) and vs LGE 3.4(1.5)]. High enterocyte FAS expression was observed in 10/12 UCD, in 0/12 TCD (p=0.0003 vs UCD), in 2/17 controls (0.0005 vs UCD) and in 0/8 LGE(p=0.0003 vs UCD). In the latters high FAS expression was only detected in patches of villus atrophy. High enterocyte FAS-L expression was observed in 10/12 UCD (p=0.008 vs controls), 0/12 TCD, 2/17 controls and in 8/8 LGE also in duonedal regions with normal morphology (p<0.01 vs controls). Conclusions. In CD small intestine high DNA fragmentation and Ki67 crypt expression correlate with villus atrophy. Moreover enterocytes of UCD co-express high levels of FAS and FAS-ligand, whilst these two molecules are only weakly expressed in the intestine of TCD as well as in `healthy' individuals. Enterocytes from LGE patients show intense FAS-L expression, but negligible FAS and no DNA fragmentation is observed. In the latters the patches of villus atrophy show, on the contrary the same behaviour as UCD. These results therefore strongly support the notion that FAS and FAS-ligand interaction is involved in the pathogenesis of CD, they also provide the explanation for the normal mucosal architecture observed in LGE celiac patients.