Expression of apoptosis-related proteins in rat with induced colitis.
OBJECTIVE
Inflammatory bowel diseases (IBD) evoke a damage-repair process accompanied by the activation of apoptotic genes. Data on transglutaminase (TG) expression in apoptotic cells in inflamed colonic epithelium has not been reported, although TG cross-links proteins within typical apoptotic bodies in various cell lines. In an experimental model of colitis we investigated the expression of different markers of apoptosis related to the degree and development of colonic inflammation.


METHODS
Two studies were performed: (a) Colitis was induced by the administration of 2,4,6-trinitrobenzen sulfonic acid (TNBS) at a dose of 10 or 20 mg per rat in 50% ethanol, and the rats were killed 1 week later; (b) Colitis was induced by 20 mg TNBS and the rats were killed 3 days, 1, 2, and 4 weeks thereafter. The colon of rats was macroscopically assessed, and biopsies were histologically assessed and immunoprobed for FasL, FasR, p53 and tTG. Cell death was detected by TUNEL, and TG activity was assayed on colon homogenates.


RESULTS
Study A: According to enhanced TUNEL positivity, FasR/FasL and p53 expression increased depending on the severity of the colitis. Study B showed increased p53 expression at day 3 while FasR/FasL coexpression peaked at 1 week. In both studies tTG was mainly expressed in the extracellular matrix of damaged tissue and in the submucosa.


CONCLUSIONS
Our findings suggest that expression of apoptosis markers is related to the degree of colitis and show that apoptosis is sustained by both p53 and FasR/FasL pathways, depending on the phase of colitis development. Moreover, the lack of TG staining in typical apoptotic bodies may account for a perturbation of the cross-linked apoptotic envelope that may be an important determinant in the development of immune response in ulcerative colitis.
D'Argenio
Giuseppe
G
Cattedra di Gastroenterologia, Facoltà di Medicina, Università di Napoli Federico II, Via Pansini 5, Napoli, Italy. dargenio@unina.it
Farrace
Maria Grazia
MG
Cosenza
Vittorio
V
De Ritis
Francesca
F
Della Valle
Nicola
N
Manguso
Francesco
F
Piacentini
Mauro
M
D000818:Animals; D000954:Antigens, Surface; D017209:Apoptosis; D015415:Biomarkers / Q000032:analysis; D001706:Biopsy; D003092:Colitis / Q000235:genetics* / Q000503:physiopathology* / Q000662:veterinary; D004195:Disease Models, Animal; D053222:Fas Ligand Protein; D020287:In Situ Nick-End Labeling; D008024:Ligands; D008297:Male; D008562:Membrane Glycoproteins; D051381:Rats; D017208:Rats, Wistar; D011503:Transglutaminases / Q000032:analysis* / Q000096:biosynthesis / Q000494:pharmacology; D014302:Trinitrobenzenesulfonic Acid / Q000008:administration & dosage / Q000009:adverse effects; D016159:Tumor Suppressor Protein p53 / Q000032:analysis / Q000096:biosynthesis; D019014:fas Receptor / Q000032:analysis / Q000096:biosynthesis
D000954:Antigens, Surface; D015415:Biomarkers; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D008024:Ligands; D008562:Membrane Glycoproteins; D016159:Tumor Suppressor Protein p53; D019014:fas Receptor; D014302:Trinitrobenzenesulfonic Acid; D011503:Transglutaminases