The cathelicidin anti-microbial peptide LL-37 is involved in re-epithelialization of human skin wounds and is lacking in chronic ulcer epithelium

This pioneering study investigated the role of the antimicrobial peptide LL-37 (human cathelicidin) in the cutaneous wound healing process, comparing peptide expression in normal acute wounds versus non-healing chronic ulcers. Using human skin biopsies, immunohistochemistry, and in vitro wound models, the researchers characterized the expression kinetics of LL-37.

The results revealed that LL-37 expression is strongly induced after skin injury, with a production peak at 48 hours post-wounding. The peptide was detected predominantly in keratinocytes at the wound edge that were actively migrating to re-epithelialize the defect. This induction was transient, normalizing after wound closure.

In striking contrast, samples from chronic venous ulcers showed significantly low or undetectable levels of LL-37 in the epithelium at lesion borders. This deficiency correlated with the inability of these wounds to complete the re-epithelialization process, suggesting that the absence of LL-37 is a contributing factor to chronicity.

The authors proposed that LL-37 acts not only as an antimicrobial agent in the wound but also as an autocrine/paracrine growth factor that stimulates keratinocyte migration and proliferation. This dual function — protection against infection and promotion of healing — positions LL-37 as a therapeutic candidate for refractory chronic ulcers.