The power of this strategy has been demonstrated in a variety of preclinical models [24–27] directed at combating mucosal inflammation using the production of immunomodulatory molecules, and the applicability of such a strategy for human disease was convincingly shown in a clinical trial of Lactococcus lactis producing interleukin-10 to treat Crohn's disease [28]. This evidence concerns the gene IL10 and Crohn disease.