Upregulation of Genes Orchestrating Keratinocyte Differentiation, Including the Novel Marker Gene ID2, by Contact Sensitizers in Human Bulge-Derived Keratinocytes

This study analyzed the molecular responses of human bulge-derived keratinocytes (BDKs) to contact sensitizers and irritants, comparing them to responses in the THP-1 cell line. BDKs showed high reactivity, with the NRF2-mediated signaling pathway upregulated in response to sensitizers. While IL1B and IL8 gene expression was induced by sensitizers in THP-1, these genes were more strongly induced by irritants in BDKs. Notably, genes involved in keratinocyte differentiation, including the novel marker gene ID2, were significantly upregulated by sensitizers in BDKs but not in THP-1. The ID2 gene was suggested as a potential marker to differentiate between sensitizers and irritants in vitro.