Tacrolimus is a calcineurin inhibitor that is most often used as an immunosuppressive drug for organ transplant patients in order to reduce the activity of the immune system lowering the risk of organ rejection. Tacrolimus is administered orally or through a topical treatment which allows the drug to be absorbed into the bloodstream. Tacrolimus enters T-cells through the ABC or SLC transporters like ABCB1 and works by forming a complex with FKBP12 with inhibits calcineurin with leads to reduced T cell signal transduction and IL-2 transcription. IL-2 is an important mediator for T-cell activation, differentiation and migration which is through mTOR signalling. Lower IL-2 production and signal transduction leads to less activated immune cells leading to a weaker immune system. Tacrolimus also inhibits the transcription for genes encoding IL-3,4,5, GM-SCF, and TNF as well which are also involved in T cell activation. Organ transplant patients take tacrolimus after allogenic organ transplant for liver, kidney, heart, small bowel, pancreas, lung, trachea, skin, cornea and limb transplant.

Tacrolimus Pathway References