TJP1 and inflammatory bowel disease: Both in vitro and in vivo experiments have indicated that the expression levels of key TJ and AJ proteins, such as zonula occludens protein 1 (ZO-1), claudin-1, occludin, and E-cadherin, were reduced in experimental models of inflammatory bowel disease but significantly increased following treatment with AHR agonists FICZ or IAld (79).