Neutrophil extracellular traps and their histones promote Th17 cell differentiation directly via TLR2

Neutrophils perform critical functions in the innate response to infection, including through the production of neutrophil extracellular traps (NETs) - web-like DNA structures which are extruded from neutrophils upon activation. Elevated levels of NETs have been linked to autoimmunity but this association is poorly understood. By contrast, IL-17 producing Th17 cells are a key player in various autoimmune diseases but are also crucial for immunity against fungal and bacterial infections. Here we show that NETs, through their protein component histones, directly activate T cells and specifically enhance Th17 cell differentiation. This modulatory role of neutrophils, NETs and their histones is mediated downstream of TLR2 in T cells, resulting in phosphorylation of STAT3. The innate stimulation of a specific adaptive immune cell subset provides an additional mechanism demonstrating a direct link between neutrophils, NETs and T cell autoimmunity. Neutrophils are critical in the immune response to infective agents and have multiple effector strategies including the production of extracellular traps termed NETs. Here the authors show a link between NET production and Th17 differentiation which mechanistically occurs downstream of TLR2 signalling.

Automated summary

This study reveals the mechanism by which neutrophil extracellular traps (NETs) directly activate T cells and specifically enhance Th17 cell differentiation. This suggests a direct link between neutrophils, NETs, and T cell autoimmunity.