Effects of Calcineurin Inhibitors on Intestinal Barrier in Caco-2 Cells

One of the side effects of calcineurin inhibitors, such as tacrolimus (FK506) and cyclosporin A (CsA), is intestinal mucosal damage leading to ulceration and bleeding. However, it remains to be elucidated whether these side effects are direct effects of calcineurin inhibitors on intestinal epithelial cells (IECs). To determine whether IECs are directly damaged by calcineurin inhibitors, we analyzed the effects of calcineurin inhibitors on the intestinal barrier in Caco-2 cells, a human intestinal cell line. Treatment of Caco-2 with calcineurin inhibitors such as FK506, CsA, and deltamethrin inhibited expression of zonula occludens-1, a tight junction protein, and increased permeability of Lucifer Yellow. These effects were observed in confluent cells, but not clear in subconfluent cells. Our findings suggest that calcineurin inhibitors can directly damage IECs.