Reduced hydration regulates pro-inflammatory cytokines via CD14 in barrier function-impaired skin

Damage to epidermis results in loss of barrier function and resultant pathological inflammatory signaling, triggering further damage to the skin. Here we investigate transcriptomic datasets generated from varied skin pathologies associated with disrupted epidermis and pinpoint CD14/S100 signaling as a conserved pathway upregulated in dermatopathologies characterized by a compromised epidermal barrier. We show that dermatitic and fibrotic tissues of humans and mouse models, which are associated with compromised epidermal barrier, demonstrate upregulation of CD14 and S100 proteins, damage-associated molecular patterns (DAMPs), in the epidermis. In vitro stratified keratinocyte cultures exposed to reduced hydration conditions show upregulated CD14/S100 family genes and pro-inflammatory gene expression, as well as decreased barrier gene expression. Knockdown and overexpression of CD14 in stratified keratinocyte cultures suppresses and induces expression, respectively, of S100 family genes and CXCL8. Taken together, these data suggest that upregulation of CD14 and/or S100 family genes in pathological epidermis results in potentiated inflammatory signaling, leading to diminished epidermal barrier function that may yield further inflammation. Future strategies to target CD14 may be utilized to dampen the response to epithelial injury for conditions of the skin and other organs.