Impact of Obesity on the CCR6-CCL20 Axis in Epidermal γδ T Cells and IL-17A Production in Murine Wound Healing and Psoriasis

Obesity is associated with comorbidities including type 2 diabetes, chronic nonhealing wounds and psoriasis. Normally skin homeostasis and repair is regulated through the production of cytokines and growth factors derived from skin-resident cells including epidermal {gamma}{delta} T cells. However epidermal {gamma}{delta} T cells exhibit reduced proliferation and defective growth factor and cytokine production during obesity and type 2 diabetes. One of the genes modulated in epidermal {gamma}{delta} T cells during obesity and type 2 diabetes is CCR6, which is the receptor for CCL20. CCL20 is elevated in the skin during obesity and type 2 diabetes. Here we identify a subset of murine epidermal {gamma}{delta} T cells that expresses CCR6 in response to activation in vitro and post-wounding or psoriasis induction with imiquimod in vivo. We show that CCL20 stimulates epidermal {gamma}{delta} T cells to produce IL-17 suggesting CCR6 regulates the IL-17 axis as in dermal {gamma}{delta} T cells. Further, epidermal {gamma}{delta} T cells upregulate CCR6 and produce IL-17 during murine models of wound repair and psoriasis. Obesity increases CCR6 and IL-17 expression by epidermal {gamma}{delta} T cells during wound repair but has less of an effect during psoriasis. These findings have novel implications for the regulation of a specific population of IL-17-producing epidermal {gamma}{delta} T cells during skin damage and inflammation.