Microbiota and Immune microEnvironment in Pouchitis: Randomized Controlled Trial Oral Administration of Lactobacillus Casei DG After Ileostomy Closure in Ileal Pouch Mucosa

Study aims

The working hypothesis is that a disruption of gut microbiota homeostasis, either spontaneous or caused by the deregulation of the innate immunity machinery within the pouch mucosa, contributes to the onset of chronic/relapsing pouchitis. Taking into account that bacterial colonization of the pouch mucosa can be ideally studied since its generation, this can be considered as an ideal model to study the interplay between gut microbiota and innate immune system. Therefore, the goal of this Research Unit is to establish how dysbiosis and innate immunity machinery dysfunction are established and how this disfunction contributes to the onset and maintenance of pouchitis. To address these relevant pathophysiological issues in light of their therapeutic implications, we plan to perform a randomized double-blind study probiotics vs placebo in patients who will undergo colectomy and subsequent ileal pouch-anal anastomosis to enrolling the patients at the time of ileostomy colure to:

1. evaluate composition and pathogenic properties of the microbiota that colonizes the pouch mucosa after ileostomy closure;
2. determine how expression and activation status of the innate immunity system in different cell types and anatomical districts of pouch mucosa relate to ileostomy closure;
3. follow-up the clinical outcome of anal pouches in light of microbiota-innate immune system interplay.

Study design In a two year period we calculated to enrol at least 32 patients who will be randomized at ileostomy closure in a group receiving placebo (16 patients) and in a group receiving lactobacillus casei GD oral supplementation for 8 weeks (16 patients). Mucosa samples will be harvested at ileostomy closure and at pouch endoscopy at 8 weeks and at 12 months.We will consider eligible candidates all patients with UC who will undergo restorative proctocolectomy with ileal pouch anal anastomosis and that will attend our outpatient's clinic for routine endoscopic and clinical follow-up. Patients with cuffitis (inflammation of the rectal mucosa remnant) or Crohn's disease of the pouch (with perianal fistulae or with inflammation of the afferent ileal limb), as well as patients who will have received antibiotic or probiotic therapy during the previous 30 days will be excluded from the study. Patients with PDAI>7 will be considered as overt pouchitis. The protocol will comply with the principles of the amended Declaration of Helsinki.

Each patient will be provided with detailed information about the study aims and methodology and will be asked to give written, informed consent prior to enrolment. During this period patients will be asked to undergo pouch endoscopy with mucosal biopsies, faecal and blood sampling at three following time: a) before ileostomy closure, b) 2 months after ileostomy closure, c) 12 months after ileostomy closure (or before, in case of overt pouchitis). Based on clinical, endoscopic and histological criteria and PDAI we will assess the disease severity [5]. Based on histological and endoscopic acute inflammation as well as clinical symptoms, patients with a total PDAI >7 will be classified as having acute pouchitis.