Relaxin-2 drives regenerative healing and suppresses scar formation

Abstract

Fibrotic scarring is a pervasive and unresolved challenge in medicine, leading to permanent disfigurement, impaired mobility, and severe disruption of basic skin functions including elasticity, barrier protection, and thermoregulation. Despite its far-reaching personal, clinical, and economic impact, affecting hundreds of millions worldwide after surgery, trauma, and burns, no effective treatments exist to halt or reverse pathological scar formation. Scarring results from uncontrolled TGF-b1 signaling, which drives excessive deposition of extracellular matrix (ECM) proteins such as collagen-I/III and accumulation of alpha-smooth muscle actin (alpha-SMA), producing rigid, dysfunctional tissue. Here, we present a mechanistically guided approach targeting this unmet clinical need, leveraging the natural antifibrotic peptide hormone relaxin-2 (RLX-2) to actively remodel dermal architecture. RLX-2 signals via its G-protein coupled receptor RXFP1, upregulating matrix metalloproteinases (MMPs) and inhibiting aberrant ECM production. In TGF-b1-activated dermal fibroblasts across 2D and 3D in vitro models, ex vivo healthy and scarred human skin samples - cultured under physiological and pathological tension - and in an in vivo murine burn wound model, RLX-2 robustly suppresses fibrosis, restores regenerative tissue features, and rescues dermal architecture. Importantly, RLX-2 achieves this result without compromising the normal wound healing process, highlighting its potential as a transformative therapy for both prevention and reversal of pathological scarring.