545 Skin Organoids derived from NCSTN mutated patient-induced pluripotent stem cells recapitulate Hidradenitis Suppurativa pathogenic hallmarks

Abstract

Hidradenitis Suppurativa (HS) is an inflammatory skin disease started by hair follicle epithelial stem cells that proliferate in an uncontrolled manner, forming a keratin plug in the follicle and interconnected tendrils in the dermis. These processes are accompanied by the infiltration of neutrophils and Th17 cells in HS skin lesions. Mutations in the NCSTN gene have been associated with HS, but the lack of in vitro models for pilosebaceous unit hinders the study of its role in disease pathogenesis. We have thus developed skin organoids from induced pluripotent stem cells (iPSCs) obtained from an HS patient with a nonsense mutation in NCSTN. We corrected the mutation using the CRISPR-Cas9 technique to obtain an iPSC isogenic line as a control. RNA-seq analysis comparing mutated and non-mutated skin organoids showed an enrichment of deregulated genes implicated in keratinocyte proliferation and differentiation. We also observed a significant higher expression of some cytokine and chemokine genes in mutated organoids, including IL1a, IL18, CCL20 and S100A7, which are responsible for neutrophils and Th17 activation in HS skin. 3D-imaging of hair follicles organoids showed a less organised structure confirming a differentiation defect. An increased number of layers and a thicker epithelium were observed in reconstructed mutated skin from organoid-isolated cells, confirming an impairment in proliferation and differentiation of mutated keratinocytes. In conclusion, IPSCs-derived skin organoids showed that an HS-associated mutation in NCSTN results in an alteration of hair follicle stem cell differentiation and expression of inflammatory proteins responsible for HS hallmarks.