Increase in chromogranin A- and serotonin-positive cells in pouch mucosa of patients with ulcerative colitis undergoing proctocolectomy

Background: Inflammatory bowel disease (IBD) is associated with neuroendocrine cell hyperplasia. Aims: We investigated neuroendocrine cells in J-pouches of patients with ulcerative colitis undergoing restorative proctocolectomy and ileal pouch-anal anastomosis. Methods: Sections from pouch biopsies of 17 patients and ileal biopsies of 17 active IBD patients and 16 controls were processed by immunohistochemistry for chromogranin A (CgA) and serotonin. Mucosal tryptophan hydroxylase (TpH)-1 and serotonin-selective reuptake transporter (SERT) transcripts were measured by quantitative RT-PCR. TpH-1 and SERT transcripts were detected in pouch biopsies cultured with infliximab or its isotype control, while interleukin (IL)-6 and IL-8 were measured in biopsy supernatants. Results: A significant increase in CgA-positive cells and serotonin-positive cells was observed in both pouch and IBD ileum compared to control ileum. Significantly raised transcripts of TpH-1, but not SERT, were found in IBD ileum in comparison to control ileum, with no significant difference between pouch and IBD ileum. Infliximab had no influence on ex vivo pouch expression of TpH-1 and SERT, nor on the production of IL-6 and IL-8. Conclusion: We here demonstrated neuroendocrine cell hyperplasia in pouch mucosa. Further studies are needed to clarify the pathophysiological implication of this finding.