The transdifferentiation of regulatory T and Th17 cells in autoimmune/inflammatory diseases and its potential implications in pregnancy complications

In the past decades, studies have shown that a balance between regulatory T cells (Tregs) and T helper 17 (Th17) cells plays a major role in autoimmune/inflammatory diseases as well as pregnancy complications. Decreased number and function of Tregs, and increased number of Th17 cells which often have an opposed effect of Tregs, are associated with these conditions. Recently, the plasticity of Tregs and Th17 cells has been reported to be involved in the pathogenesis of autoimmune/inflammatory diseases. Hence, we summarize the current knowledge of Tregs and Th17 cells plasticity with an emphasis on their reciprocal transdifferentiation in autoimmune/inflammatory diseases. Moreover, the regulators of the Tregs-to-Th17 cells transdifferentiation are discussed as well. Finally, by reviewing the immuno-inflammatory status of pregnancy complications, such as preeclampsia and unexplained recurrent pregnancy losses, a possibility of Tregs-to-Th17 cells transdifferentiation as an underlying immune-pathology of these conditions is discussed.