Dendritic epidermal T cells regulate skin antimicrobial barrier function
Amanda S. MacLeod, Saskia Hemmers, Olivia Garijo, Marianne Chabod, Kerri Mowen, Deborah A. Witherden, Wendy L. Havran
Amanda S. MacLeod, Saskia Hemmers, Olivia Garijo, Marianne Chabod, Kerri Mowen, Deborah A. Witherden, Wendy L. Havran
View: Text | PDF
Research Article Immunology

Dendritic epidermal T cells regulate skin antimicrobial barrier function

Abstract

The epidermis, the outer layer of the skin, forms a physical and antimicrobial shield to protect the body from environmental threats. Skin injury severely compromises the epidermal barrier and requires immediate repair. Dendritic epidermal T cells (DETC) reside in the murine epidermis where they sense skin injury and serve as regulators and orchestrators of immune responses. Here, we determined that TCR stimulation and skin injury induces IL-17A production by a subset of DETC. This subset of IL-17A–producing DETC was distinct from IFN-γ producers, despite similar surface marker profiles. Functionally, blocking IL-17A or genetic deletion of IL-17A resulted in delayed wound closure in animals. Skin organ cultures from Tcrd–/–, which lack DETC, and Il17a–/– mice both exhibited wound-healing defects. Wound healing was fully restored by the addition of WT DETC, but only partially restored by IL-17A–deficient DETC, demonstrating the importance of IL-17A to wound healing. Following skin injury, DETC-derived IL-17A induced expression of multiple host-defense molecules in epidermal keratinocytes to promote healing. Together, these data provide a mechanistic link between IL-17A production by DETC, host-defense, and wound-healing responses in the skin. These findings establish a critical and unique role of IL-17A–producing DETC in epidermal barrier function and wound healing.

Authors

Amanda S. MacLeod, Saskia Hemmers, Olivia Garijo, Marianne Chabod, Kerri Mowen, Deborah A. Witherden, Wendy L. Havran

×

Figure 2

IL-17A production by a subset of DETC requires TCR stimulation.

Options: View larger image (or click on image) Download as PowerPoint
IL-17A production by a subset of DETC requires TCR stimulation. (A) DETC...
(A) DETC upregulate Il17a upon TCR stimulation in vitro. Sorted Vγ3+ DETC express Il17a following activation by plate-bound anti-CD3ε (10 μg/ml). (B) Freshly isolated and sorted Vγ3+ DETC were stimulated with plate-bound anti-CD3ε (10 μg/ml), and IL-17A, IL-17F, and IL-22 protein was measured by ELISA. Data are shown as mean ± SEM from quadruplicate measurements and are representative of 3–4 independent experiments. ***P ≤ 0.001. (C) CsA inhibits anti-CD3ε–mediated IL-17A production in DETC. Cells are gated on Vγ3+Thy1.2+. (D) Stimulation with IL-1β and IL-23 alone does not induce IL-17A in DETC. Sorted Vγ3+ DETC were stimulated with IL-1β, IL-23, or the combination thereof in the presence or absence of suboptimal anti-CD3ε, and IL-17A secretion was assayed by ELISA. Data are shown as mean ± SEM from duplicates. (E) JAML costimulation increases IL-17A in DETC. ELISA analysis for IL-17A from culture supernatants of DETC stimulated with antibody against suboptimal doses of CD3 alone, CD3 and JAML, or JAML alone. Data are shown as mean ± SEM from duplicates. (F) DETC upregulate RORγt upon TCR stimulation. Freshly isolated DETC were stimulated with anti-CD3ε (10 μg/ml) for 3 hours, and RORγt levels were measured by flow cytometry. (G) A subset of RORγt+ DETC produces IL-17A. RORγt and IL-17A expression were assessed by flow cytometry in freshly isolated epidermal cell suspensions that were stimulated with anti-CD3ε (10 μg/ml). Cells are gated on Vγ3+Thy1.2+.