Cyclosporin A

Cyclosporin A is a potent immunosuppressant. It forms a complex with cyclophilin D and inhibits the activity of the calcium/calmodulin-dependent protein phosphatase 2B (PP2B, calcineurin). Cyclosporin A prevents the dephosphorylation of nuclear factor of activated T cells (NFAT) transcription factor, leading to disruption of T cell activation and it suppresses proliferation of cytotoxic T cells and inhibits the production of T cell-derived mediators such as interleukin-2 (IL-2). Because of its powerful immunosuppressant activity, cyclosporin A has long been used for the prevention of transplant rejection. Cyclosporin A is an anti-inflammatory compound in the treatment of several inflammatory skin diseases (e.g. atopic dermatitis) and with potential anti-rheumatic activity (rheumatoid arthritis). Cyclosporin A has been described to have antibacterial, antifungal, antiparasitic, autophagic, antiapoptotic and anticancer activity. It inhibits the mitochondrial permeability transition pore (MPTP) from opening, thus inhibiting cytochrome c release.