Tropomyosin expression in the ileal pouch: a relationship with the development of pouchitis in ulcerative colitis.
OBJECTIVE
Human tropomyosin isoform 5 (hTM5) is a cytoskeletal protein expressed in normal epithelial cells, predominantly in the colon. An autoimmune response toward hTM5 has been reported in ulcerative colitis (UC). Whether hTM5 expression in the ileum is involved in pouchitis is unknown. We assessed hTM5 expression on ileal epithelial cells at surgery and subsequently on development of pouchitis in UC.


METHODS
In a prospective longitudinal study, 28 UC patients undergoing ileal pouch procedures were included. Biopsy samples were taken from the rectum at surgery, as well as from the ileal pouch at surgery and at 6 months. The specimens were stained by immunoperoxidase using the anti-hTM5 monoclonal antibody CG3. Pouchitis was assessed by the Pouchitis Disease Activity Index and hTM5 expression on a scale of 0-3.


RESULTS
At surgery, in rectal samples, hTM5 expression was strong in all epithelial cells including the luminal surface, whereas in ileal samples hTM5 was not expressed or focally expressed only in the goblet cells. At 6 months, the ileum was found to have undergone morphological changes, becoming similar to the colon and showing shortening or reduced number of villi. These changes were associated with a diffuse hTM5 staining in the goblet cells and in the nongoblet epithelial cells lining the crypts and the lumen. The hTM5 score was related to the Pouchitis Disease Activity Index at 6 months (r = 0.82; p = 0.01).


CONCLUSIONS
Expression of hTM5 shows a different pattern in the ileal pouch in UC after surgery. This event is associated with morphological changes of the ileum toward colonic epithelium, related to the development of pouchitis.
Biancone
Livia
L
Cattedra di Gastroenterologia, Dipartamento de Medicina Interna, and Center of Excellence for the Study of the Genomic Risk of Complex Multifactorial Diseases, Università di Roma Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
Palmieri
Giampiero
G
Lombardi
Antonella
A
Colantoni
Alfredo
A
Tonelli
Francesco
F
Das
Kiron Moy
KM
Pallone
Francesco
F
D000911:Antibodies, Monoclonal; D003093:Colitis, Ulcerative / Q000378:metabolism* / Q000473:pathology / Q000601:surgery*; D006801:Humans; D007082:Ileum / Q000378:metabolism* / Q000473:pathology; D007124:Immunoenzyme Techniques; D008137:Longitudinal Studies; D019449:Pouchitis / Q000209:etiology*; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D014335:Tropomyosin / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D014335:Tropomyosin