γδT cells and adipocyte IL-17RC control fat innervation and thermogenesis

The sympathetic nervous system innervates peripheral organs to regulate their function and maintain homeostasis, whereas target cells also produce neurotrophic factors to promote sympathetic innervation(1,2). The molecular basis of this bi-directional communication remains to be fully elucidated. Here we use thermogenic adipose tissue as a model system to show that T cells, specifically γδT cells, play a critical role in promoting sympathetic innervation, at least in part through driving TGFβ1 expression in parenchymal cells via IL-17 Receptor C. Adipose-specific ablation of IL-17 Receptor C reduces TGFβ1 expression in adipocytes, impairs local sympathetic innervation and causes obesity and other metabolic phenotypes consistent with defective thermogenesis; innervation can be fully rescued by restoring TGFβ1 expression. Ablating γδT cells and the IL-17 Receptor C signaling pathway also impairs sympathetic innervation in salivary glands and the lung. These findings demonstrate T cell/parenchymal cell coordination to regulate sympathetic innervation.