Basophils Play a Protective Role in the Recovery of Skin Barrier Function from Mechanical Injury in Mice

Physical trauma disrupts skin barrier function. How the skin barrier recovers is not fully understood. We evaluated in mice the mechanism of skin barrier recovery after mechanical injury inflicted by tape stripping. Tape stripping disrupted skin barrier function as evidenced by increased transepidermal water loss. We show that tape stripping induces IL-1-, IL-23-, and TCRγδ⁺-dependent upregulation of cutaneous Il17a and Il22 expression. We demonstrate that IL-17A and IL-22 induce epidermal hyperplasia, promote neutrophil recruitment, and delay skin barrier function recovery. Neutrophil depletion improved the recovery of skin barrier function and decreased epidermal hyperplasia. Single-cell RNA sequencing and flow cytometry analysis of skin cells revealed basophil infiltration into tape-stripped skin. Basophil depletion upregulated Il17a expression, increased neutrophil infiltration, and delayed skin barrier recovery. Comparative analysis of genes differentially expressed in tape-stripped skin of basophil-depleted mice and Il17a^-/- mice indicated that basophils counteract the effects of IL-17A on the expression of epidermal and lipid metabolism genes important for skin barrier integrity. Our results demonstrate that basophils play a protective role by downregulating Il17a expression after mechanical skin injury, thereby counteracting the adverse effect of IL-17A on skin barrier function recovery, and suggest interventions to accelerate this recovery.