Relationship Between Mucosa-associated Microbiota and Inflammatory Parameters in the Ileal Pouch After Restorative Proctocolectomy for Ulcerative Colitis

Background: Our aim was to assess the relationship between the ileal-pouch microbiota and inflammatory parameters in patients operated on for ulcerative colitis.

Methods: In this cross-sectional study, 32 consecutive outpatients returning for follow-up endoscopy were recruited. Pouch biopsies were obtained during endoscopy for culture of bacteria adherent to the mucosa, histology, and analysis of local inflammation (IL-1β, IL-6, and TNFα by immunometric assay; and toll-like receptor [TLR] 2 and 4 mRNA by quantitative real-time PCR). Fecal samples were collected for analysis of lactoferrin by ELISA.

Results: Granulocyte and monocyte mucosal infiltration correlated directly with mucosal Bacteriodiaceae spp. counts. Clostridiaceae spp. counts showed a direct correlation with mucosal ulceration and number of daily stools. In patients with pouchitis, Enterococcaceae spp. counts were less than in healthy patients. Enterobacteriaceae spp., Streptococcaceae spp. and Enterococcaceae spp. counts correlated inversely with immune cell infiltration. TLR-2 and TLR-4 mRNA, and mucosal levels of IL-1β levels all correlated directly with Veilonella spp. counts.

Conclusion: Bacteriodaceae spp. and, Clostridiaceae spp. may be associated with inflammation of the pouch mucosa. Conversely, Enterococcaceae spp., and possibly Enterobacteriaceae spp. and Streptococcaceae spp., may have an active role in maintaining immunologic homeostasis within the pouch mucosa.