HP and Crohn disease: Tight junctions are in turn regulated by another protein called zonulin, a haptoglobin 2 precursor that represents the mammalian counterpart of the zonula occludens toxin, secreted by Vibrio cholerae [115,116], which has been reported to be involved in both Crohn’s disease and ulcerative colitis, as well as in preventing colonization by intestinal microorganisms [117].