Modulation of the KYN pathway activity in kidney transplant recipients. The figure presents possible effects of immunosuppressive treatment on IDO activity, as well as other methods of KYN pathway modifications, through the impact on urinary microbiota (left) or local IDO transfection (right). CsA, cyclosporine A; CTLA4-lg, cytotoxic T-lymphocyte associated protein 4 fusion protein; GCS, glucocorticosteroids; IDO, indoleamine-2,3-dioxygenase; MMF, mycophenolate mofetil; mTORi, mammalian target of rapamycin inhibitor; TAC, tacrolimus. Created with https://www.BioRender.com (accessed on 1 August 2024).