Topical hypochlorite ameliorates NF-κB-mediated skin diseases in mice

Nuclear factor-kappa B (NF-kappa B) regulates cellular responses to inflammation and aging, and alterations in NF-kappa B signaling underlie the pathogenesis of multiple human diseases. Effective clinical therapeutics targeting this pathway remain unavailable. In primary human keratinocytes, we found that hypochlorite (HOC1) reversibly inhibited the expression of CCL2 and SOD2, two NF-kappa B-dependent genes. In cultured cells, HOC inhibited the activity of inhibitor of NF-kappa B kinase (IKK), a key regulator of NF-kappa B activation, by oxidizing cysteine residues Cys114 and Cys115. In NF-kappa B reporter mice, topical HOC1 reduced LPS-induced NF-kappa B signaling in skin. We further evaluated topical HOC use in two mouse models of NF-kappa B-driven epidermal disease. For mice with acute radiation dermatitis, topical HOC1 inhibited the expression of NF-kappa B-dependent genes, decreased disease severity, and prevented skin ulceration. In aged mice, topical HOC attenuated age-dependent production of p16(INK4a) and expression of the DNA repair gene Rad50. Additionally, skin of aged HOCl-treated mice acquired enhanced epidermal thickness and proliferation, comparable to skin in juvenile animals. These data suggest that topical HOC reduces NF-kappa B-mediated epidermal pathology in radiation dermatitis and skin aging through IKK modulation and motivate the exploration of HOC1 use for clinical aims.