CLDN2 and Crohn ileitis: VSL#3- and TNF-specific modulation of claudin-2 and occludin in young, ileitis-prone SAMP mice was further confirmed by in vivo experiments on isolated ileal loops in which either VSL#3-CM or TNF was injected, followed by epithelial immunolocalization of the aforementioned TJ proteins (Fig. 4).