P27 Transcriptional and epigenetic changes drive increased cellular plasticity in keloid fibroblasts
Stavroula Tekkela, Elena Drudi, Willow Hight-Warburton, Tanya Shaw, Emanuel RognoniAbstract
Introduction and aims
Keloids are difficult-to-manage and poorly understood fibroproliferative scars. There is rapidly growing evidence supporting numerous diverse underlying pathological mechanisms, but clarity is needed to improve treatment strategies. Recently, we discovered that keloid lesions have a cartilage-like composition, suggesting that cell misdifferentiation may underlie this fibrosis-associated phenotype. As the epigenetic landscape controls cell differentiation potential, we hypothesize that keloid fibroblasts have an epigenetically mediated heightened plasticity relative to normal dermal fibroblasts, offering a novel approach for therapeutic modulation.
Methods
Primary keloid disorder fibroblasts (KDFs) and adjacent normal fibroblasts (NDFs) cultured in standard conditions were phenotypically characterized, and analysed with bulk assay for transposase-accessible chromatin using sequencing (ATAC-seq) and RNA sequencing. The link between chromatin organization and cell plasticity was investigated by exposing NDFs and KDFs to chondrocyte and adipocyte differentiation conditions, including manipulation with chromatin remodelling drugs.
Results
Cell phenotyping revealed a district more elongated nuclear size in KDFs vs. NDFs. This is consistent with the ATAC-seq analysis revealing greater chromatin accessibility in KDFs, with enrichment in loci involved in ‘cell plasticity’, ‘cell differentiation’ and ‘embryonic morphogenesis’. Exposure of KDFs and NDFs to adipocyte or chondrocyte differentiation conditions confirmed increased cell plasticity in KDFs. Intriguingly, transcriptomic analysis of adipocyte differentiated cells showed an increased distinct differential gene expression in NDFs that strongly overlap accessible regions in KDFs, suggesting that KDFs are more primed for cell differentiation. Treatments with chromatin-modifying drugs, such as histone deacetylases inhibitor trichostatin A, enhanced amenability to differentiation and expression of traditional fibrotic features in KDFs, whereas histone acetyltransferase inhibitors such as GSK343/garcinol were inhibitory.
Conclusions
In culture, keloid fibroblasts had more accessible chromatin, particularly in genomic regions associated with cell differentiation, suggesting that they are poised to differentiate in response to cues in the wound/scar environment. Epigenetic modifying compounds have the potential to normalize the profibrotic changes.