PRObiotic VSL#3® for Maintenance of Clinical and Endoscopic REMission in Ulcerative Colitis

This is a Phase II a, parallel-groups, randomized, double-blind, placebo-controlled, single-center, dose finding study in subjects with UC in remission. Two different oral doses of VSL#3® added to standard therapy (5-ASA) will be investigated compared to standard therapy (5-ASA) plus placebo (in a 1:1:1 ratio). All patients will receive standard therapy for maintaining remission. 39 subjects will be randomly assigned to 1 of the 3 treatment arms for the 12-month treatment period as following: * group A: 13 patients will receive mesalamine 2.4 g/day in once daily administration plus VSL#3® 450 billion sachet, two sachets per day for 12 months (900 billion of bacteria per day) * group B: 13 patients will receive mesalamine 2.4 g/day in once daily administration plus VSL#3® 450 billion sachet, two sachets twice a day (1800 billion of bacteria per day) for 12 months * group C: 13 patients will receive mesalamine 2.4 g/day in once daily administration plus placebo for 12 months. Subject participation in this study will be approximately 20 months which includes up to a 8-week screening period, a 12-month treatment period, and a 6-month follow-up period. At the conclusion of the 12-month treatment period, subjects will continue in the 6-month follow-up period (telephone contact conducted after 6 months).