Possible Involvement of the Mucosal Claudin Expression in the Healing of a Refractory Ileocecal Ulcer in a Patient with Crohn's Disease Successfully Treated with Infliximab.

An impaired intestinal barrier exposes the microbiota to gut immune cells, triggering cytokine responses that cause Crohn's disease (CD). Barrier dysfunction is a prerequisite for CD development. However, the effects of biological therapies on barrier integrity remain poorly understood. We aimed to present a case of CD refractory to adalimumab and risankizumab. Treatment with infliximab improved refractory ulcers, and this effect was associated with alterations in the mucosal mRNA expression of claudins, cell-cell adhesion molecules that contribute to the maintenance of barrier integrity. These findings suggested that infliximab induces CD remission by regulating the expression of claudin.