Multi-omic analysis reveals retinoic acid molecular drivers for dermal fibrosis and regenerative repair in the skin.

Skin fibrosis is driven by fibroblast activation and excessive extracellular matrix deposition. To ascertain the fibroblast subpopulation(s) responsible for instigating fibrosis, we employed an established murine bleomycin skin fibrosis model. We characterized both the fibrotic and remodeling phases of dermal fibrosis through a multi-omic approach. Using an unsupervised machine learning algorithm that quantifies 294 fiber features, we identified precise time points of fibrosis and regeneration. Single-cell transcriptomic and epigenomic sequencing then identified a Cyp26b1-expressing fibroblast subpopulation responsible for dermal fibrosis. The same fibroblast subtype was mapped to Visium spatial transcriptomic data. We further mapped the fibrotic subtypes to protein spatial data. To ascertain the functional impact of the fibroblast subpopulations, transplant delivery analysis showed their ability to drive skin fibrosis. Lastly, we identified a small molecular inhibitor of Cyp26b1 (talarozole) that prevents and rescues dermal fibrosis. Conclusively, we establish an atlas of the fibrotic and regenerative biological drivers of skin fibrosis.