(WHS-P3.03) SKINT-1 REGULATES GAMMA DELTA T CELL ACTIVITY DURING WOUND REPAIR
Friday, May 17, 2024
10:30 AM – 11:30 AM East Coast USA Time
Butyrophilin (BTN)-related Skint-1 (Selection and upkeep of intraepithelial T cells 1) molecule is expressed on epidermal keratinocytes and thymic epithelial cells. Skint-1 specifically drives the development of the subtype of gamma delta T (GDT) cells, dendritic epidermal T cells (DETCs) progenitors in the thymus. Importantly, homeostasis and activation of resident epithelial GDT cells are under the control of butyrophilin (BTN) and butyrophilin-like (BTNL) molecules, in humans and mice. However, it is not well understood how Skint-1 influence DETCs function in the epidermis in response to wounding. Interactions between commensal microbiota and the multiple cell types involved in cutaneous wound healing regulate the immune response and promote barrier restoration. In that regard, we have recently shown that Perforin-2 (P-2), novel anti-microbial protein expressed in the skin, is critical for the clearance of intracellular pathogens. We postulated that P-2 contributes to GDT cell activation and recruitment in response to wounding through regulation of Skint-1. We induced full thickness wounds on the dorsal skin of 2- or 10-month-old C57/BL6 WT and P-2 knock-out (KO) mice and assessed healing at days 3 and 6 post wounding. We analyzed re-epithelialization and keratinocyte activation using histomorphometry and keratin-6 staining. We expressed Skint-1 on the HEK-293 cells and co-cultured skin GDT cells in the presence of anti-Skint-1 antibody and measured activation of GDT cells by multicolor flow cytometry. We found that in aged 10-month-old mice, wound re-epithelialization was significantly delayed at day 6 in P-2 KO mice compared to aged WT and young P-2 KO (p < 0.05). The healing delay was accompanied by significantly decreased keratin-6 expression at the wound edge (p < 0.05). Immunofluorescence staining and flow cytometric analysis revealed significant reduction in GDT cells in the wound bed in aged P-2 KO mice (p < 0.05). The GDT cells in the P2 KO background also displayed lower expression of activation markers, including significantly lower mRNA and protein levels of Skint-1 on day 6 post-wounding (p < 0.05). In vitro co-culture experiments confirmed that epithelial Skint-1 induces activation of GDT cells. Our data demonstrate impaired keratinocyte activation and GDT cell infiltration in the absence of P-2 that is more pronounced in aged mice, indicating a novel mechanism relying on the P-2 and Skint-1 in modulating the inflammatory response upon wounding.