Basophils drive the resolution and promote wound healing in adult and aged mice.

An active resolution is critical to control the duration of inflammation and limit its pathological consequences. Defects in resolution during wound healing allow the emergence of chronic wounds, a common complication in the elderly. Here, we show that basophils accumulate in perivascular areas at the periphery of mouse skin wounds for at least 3 wk, during both the inflammation and resolution phases of wound healing. Depletion of basophils induces an increased secretion of inflammatory molecules, accumulation and activation of pro-inflammatory leukocytes, and delays the wound healing response. Basophils particularly promote epidermal differentiation towards homeostasis. These properties are particularly driven by basophil-derived IL-4. Unexpectedly, aged mice basophils more potently infiltrate skin wounds to promote inflammation resolution. Thus, basophils are pro-resolution cells during an essential biological process such as skin wound healing. Unraveling basophil pro-resolution properties may reveal new strategies to fight chronic wounds in the elderly.