Structure and signalling in the IL-17 receptor family

Recent studies defining the structure of and signalling pathways used by receptors of the interleukin-17 family have led to interesting comparisons with the pro-inflammatory signalling pathways that are more commonly associated with innate immune receptors. Sarah Gaffen therefore suggests that T helper 17 cells might act as a bridge between innate and adaptive immunity. Interleukin-17A (IL-17A), the hallmark cytokine of the newly defined T helper 17 (TH17) cell subset, has important roles in protecting the host against extracellular pathogens, but also promotes inflammatory pathology in autoimmune disease. IL-17A and its receptor (IL-17RA) are the founding members of a newly described family of cytokines and receptors that have unique structural features which distinguish them from other cytokine families. Research defining the signal transduction pathways induced by IL-17R family cytokines has lagged behind that of other cytokine families, but studies in the past 2 years have begun to delineate unusual functional motifs and new proximal signalling mediators used by the IL-17R family to mediate downstream events.