P013 Characterization of enterochromaffin cells in pouchitis after proctocolectomy with ileal pouch-anal anastomosis for ulcerative colitis
P. Giuffrida1, A. Vanoli2, E. Biletta2, G. Sampietro3, O. Luinetti2, R. Manca2, G. Bergamaschi1, D. Bagordo1, C. Salvatore1, C. Alvisi1, P. Fociani4, E. Solcia1, G.R. Corazza1, A. Di Sabatino*1
1Fondazione IRCCS Policlinico San Matteo, University of Pavia, First Department of Medicine, Pavia, Italy, 2Fondazione IRCCS Policlinico San Matteo, University of Pavia, Department of Molecular Medicine, Pavia, Italy, 3Luigi Sacco University Hospital, Surgery Division, Department of Clinical Sciences, Milan, Italy, 4Luigi Sacco University Hospital, Chair of Pathology, Milan, Italy
Serotonin-producing enterochromaffin (EC) cells are the prevalent neuroendocrine cell type in the gut. EC cells are characterised by the expression of the pan-neuroendocrine marker chromogranin A (CgA). Several immune-mediated gastrointestinal disorders, including inflammatory bowel disease (IBD), are associated with EC cell hyperplasia. We here characterised EC cells in patients with pouchitis after proctocolectomy with ileal pouch-anal anastomosis for ulcerative colitis (UC).
Serial sections from 17 patients affected by pouchitis and from ileum of 13 IBD patients (5 Crohn's ileitis and 8 UC backwash ileitis) and 11 control subjects were processed for the immunohistochemical detection of CgA and serotonin. Mucosal tryptophan hydroxylase (TpH)-1 and serotonin-selective reuptake transporter (SERT) transcripts were measured by quantitative RT-PCR.
We observed an increase in CgA-positive cells in both patients affected by pouchitis and those with IBD ileitis compared to control subjects, with no difference between pouchitis and IBD ileitis. No change was found for EC cells amongst pouchitis and the other two groups, whereas IBD patients with ileitis have higher EC cells than control subjects. Moreover, we detected an increase in CgA-positive and serotonin-negative cells, calculated by subtracting the number of CgA-positive cells from the number of EC cells, in pouchitis in comparison to IBD ileitis and control subjects. Raised transcripts of mucosal TpH-1, but not SERT, were found in IBD ileitis in comparison to control subjects, without significant difference amongst pouchitis and the other two groups.
We show hyperplasia of neuroendocrine cells in the mucosa of both pouchitis patients and those with IBD ileitis. EC cells and TpH-1 transcripts are increased in the mucosa of IBD patients with ileitis, but not in pouchitis patients. Hyperplasia of neuroendocrine cells seems to be due to other cell types in pouchitis. Further studies are underway to ascertain what is the cell type/s causing neuroendocrine cell hyperplasia in pouchitis.