New Anti-Fibrotic Strategies for Keloids: Insights From Single-Cell Multi-Omics.

Keloids are complex pathological skin scars characterised by excessive growth of fibrous tissue and abnormal accumulation of extracellular matrix (ECM). Despite various treatment options available, the treatment of keloids remains a major clinical challenge due to high recurrence rates and inconsistent therapeutic outcomes. By collecting three keloid tissues and three normal skin samples and utilising single-cell RNA sequencing (scRNA-seq), we delved into the cellular heterogeneity and molecular mechanisms of keloids. Our study identified multiple fibroblast subpopulations within keloid tissue. Enrichment and cell-cell communication analyses revealed that POSTN-positive mesenchymal fibroblasts (POSTN+ mesenchymal fibs) are more prevalent in keloids and exhibit higher transforming growth factor β (TGF-β) signalling activity, potentially playing a central role in excessive fibrosis. In contrast, IGFBP2-positive fibroblasts (IGFBP2+ fibs) are more abundant in normal skin, insensitive to TGF-β and Periostin signalling, and possess anti-fibrotic potential, possibly related to limited tissue repair and regenerative capacity. Trajectory analysis inferred the differentiation states and patterns of different fibroblast subpopulations. Additionally, we explored the heterogeneity of endothelial cells, finding an endothelial cell subpopulation (EC10) exhibiting mesenchymal activation characteristics, which may work with specific fibroblasts to promote abnormal angiogenesis and endothelial-to-mesenchymal transition processes. Spatial transcriptomics analysis has shown that the proportion of IGFBP2+ fibroblasts relatively increases in acne keloidalis after hormonal treatment, further demonstrating their value as potential therapeutic targets. Ultimately, we separated these two subpopulations using flow cytometry, highlighting their opposing roles in the secretion of the ECM. These findings provide new insights into the pathogenesis of keloids and lay the theoretical foundation for the development of innovative anti-fibrotic treatment strategies.