MicroRNA-mediated regulation of T helper cell differentiation and plasticity

CD4(+) T helper (T-H) cells regulate appropriate cellular and humoral immune responses to a wide range of pathogens and are central to the success of vaccines. However, their dysregulation can cause allergies and autoimmune diseases. The CD4(+) T cell population is characterized not only by a range of distinct cell subsets, such as T(H)1, T(H)2 and T(H)17 cells, regulatory T cells and T follicular helper cells - each with specific functions and gene expression programmes - but also by plasticity between the different T-H cell subsets. In this Review, we discuss recent advances and emerging ideas about how microRNAs - small endogenously expressed oligonucleotides that modulate gene expression - are involved in the regulatory networks that determine T-H cell fate decisions and that regulate their effector functions.