Inhibition of miR-497-5p improves keratinocyte function upon skin exposure to sulfur mustard

Sulfur mustard (SM) is a hazardous chemical warfare agent. Exposure to SM results in various pathologies including skin lesions and impaired wound healing. To date, there are no effective treatments available. Here we discover that the miRNA miR-497-5p is induced in epidermal cells by SM and mediates keratinocyte dysfunction. Transcriptome analysis using RNA-seq in normal human epidermal keratinocytes (NHEK) revealed that SM evoked differential expression of 1,896 mRNAs and 25 miRNAs with many of these RNAs known to be involved in keratinocyte function and wound healing. We demonstrated that keratinocyte differentiation and proliferation were efficiently regulated by miRNAs induced in skin cells after exposure to SM. The inhibition of miR-497-5p counteracted SM-induced premature differentiation and inhibition of proliferation in NHEK. In addition, we showed that microneedle-mediated transdermal application of lipid-nanoparticles containing miR-497-5p inhibitor improved the healing of human skin biopsies upon exposure to SM. Our findings expand the current understanding of SM-associated molecular toxicology in keratinocytes and highlight miR-497-5p as feasible clinical target for specific skin therapy in SM-exposed patients and beyond. Overall design: Normal human epidermal keratinocytes (NHEK) were left untreated or exposed to sulfur mustard (SM) at 10 µM and 30 µM or vehicle control (ethanol) (n = 4). After 24 hours of cultivation, mRNA and miRNA were isolated and subjected to RNA-seq analysis.