The intestinal proinflammatory immune factor and NF-κB could induce the decrease in claudin-1 expression inflammatory bowel disease (Zhou et al., 2009), and BBR might regulate claudin-4 and claudin-2 expressions other than claudin-1 in claudin family (Amasheh et al., 2010; Li et al., 2014). Here, CLDN2 is linked to inflammatory bowel disease.