From killers to hoplites: neutrophils in skin barrier defense

Neutrophils are traditionally known as short-lived pathogen-killing cells, but recent work published in Nature by Hidalgo and colleagues uncovers a novel role for neutrophils in maintaining skin integrity. Using transcriptomics, imaging, and genetic models, the study reveals that skin-infiltrating neutrophils produce collagen, particularly COL3A1, to regulate tissue mechanics and form matrix-rich "shields" that prevent pathogen entry. Collagen production by these specialized neutrophils in the skin was TGFβ-dependent and essential for wound protection, as its disruption led to disorganized skin architecture and increased bacterial invasion. This work redefines neutrophils as dynamic matrix-builders in barrier tissues, offering new insights into immune-tissue crosstalk and advancing our understanding of wound healing and host defense.