Regulatory T cells in autoimmune kidney diseases and transplantation

Regulatory T (T reg ) cells that express the transcription factor forkhead box protein P3 (FOXP3) are naturally present in the immune system and have roles in the maintenance of immunological self-tolerance and immune system and tissue homeostasis. T reg cells suppress T cell activation, expansion and effector functions by various mechanisms, particularly by controlling the functions of antigen-presenting cells. They can also contribute to tissue repair by suppressing inflammation and facilitating tissue regeneration, for example, via the production of growth factors and the promotion of stem cell differentiation and proliferation. Monogenic anomalies of T reg cells and genetic variations of T reg cell functional molecules can cause or predispose patients to the development of autoimmune diseases and other inflammatory disorders, including kidney diseases. T reg cells can potentially be utilized or targeted to treat immunological diseases and establish transplantation tolerance, for example, by expanding natural T reg cells in vivo using IL-2 or small molecules or by expanding them in vitro for adoptive T reg cell therapy. Efforts are also being made to convert antigen-specific conventional T cells into T reg cells and to generate chimeric antigen receptor T reg cells from natural T reg cells for adoptive T reg cell therapies with the aim of achieving antigen-specific immune suppression and tolerance in the clinic.