A sympathetic-eosinophil axis orchestrates psychological stress to exacerbate skin inflammation

Psychological stress is believed to exacerbate dermatitis, yet the neurobiological mechanisms linking stress to immune processes remain elusive. We identified a subset of prodynorphin-positive (Pdyn⁺) noradrenergic sympathetic neurons in mice that specifically innervate hairy skin, mediating stress-induced exacerbation of skin inflammation in an eosinophil-dependent manner. Genetic ablation of Pdyn⁺ sympathetic neurons or eosinophils mitigated stress-evoked worsening of inflammation in atopic dermatitis-like mice, whereas optogenetic activation of these neurons precipitated inflammation through eosinophils. Pdyn⁺ sympathetic neurons recruited eosinophils through the CCL11-CCR3 axis and activated them through the adrenergic receptor beta2 (Adrb2) in inflamed skin. Our findings reveal a neuroimmunological mechanism underlying psychological stress-induced exacerbation of dermatitis, emphasizing the Pdyn⁺ sympathetic-eosinophil axis as a crucial interface between the brain and skin inflammation, with potential therapeutic implications.