P37 <i>In silico</i> predicted tetrapeptide matrikines promote proliferation and profoundly modulate the transcriptome of cultured human keratinocytes

Abstract Introduction and aims The topical application of exogenous putative peptide matrikines can induce beneficial remodelling in the aged human dermis. We have shown that the identity of new bioactive matrikines can be predicted by the in silico digestion of dermal extracellular matrix (ECM) proteins by skin proteases. Two of these matrikine peptides modified with a palmitoyl chain, P1 (Pal-GPKG) and P7 (Pal-LSVD) in combination, modulated gene expression in cultured human dermal fibroblasts and induced deposition of fibrillin microfibrils in photoaged skin of human participants. Here we test the hypothesis that these matrikines can also modulate the behaviour and transcriptome of cultured primary human keratinocytes, thereby providing potential off-target epidermal benefits. Methods Normal human epidermal keratinocytes (NHEKs) from three donors were sourced from a commercial supplier (White female donors aged 51–58 years, n = 3, facial skin). Peptides P1 and P7 in a 1 : 1 ratio were solubilized in 0.05% w/v dimethyl sulfoxide (DMSO). The ability of the peptides to modulate cell proliferation was assessed using live cell imaging while treatment effects on the cellular transcriptome were assessed by RNA sequencing 12 h after exposure to the peptide combination or DMSO control. Results Compared with the DMSO control, peptide treatment significantly modulated proliferation for all three donor cells (P &amp;lt; 0.001). Treatment also significantly modulated the transcriptome. More than 2000 genes were differentially expressed with fold changes ≥ 2 compared with DMSO (Padj &amp;lt; 0.05; upregulation 1522 genes, downregulation 736 genes) across all three donors. Significantly modulated pathways included those involved in DNA replication, cell cycle checkpoints and differentiation of epithelial tissue. Discussions Small peptides with homology to ECM protein sequences differentially affect the behaviour and transcriptome of epithelial cells highlighting their potential activity in the epidermis. Such effects may have implications for exogenous topical treatments and also in vivo dermal to epidermal cell signalling.