In this study, we characterized the paracrine interaction between human keratinocytes (HK) and human fibroblasts (HF) which leads to increased expression of SFE.
Medium conditioned by UVB-exposed HK contained increased levels of IL-1伪, GM-CSF, IL-6, TNF伪 and IL-8. While HF cultured with those conditioned medium slightly down-regulated the gene expression of collagen and elastin, they significantly increased their expression of SFE at the transcriptional, translational and enzymatic levels. Neutralizing antibodies to IL-1伪 or GM-CSF significantly abolished the increased expression of SFE at the translational and/or enzymatic levels in HF cultured with those conditioned medium, while neutralizing antibodies to IL-6, IL-8 or TNF伪 had no such effect. The addition of IL-1伪 or GM-CSF, but not TNF伪, IL-6 or IL-8, at concentrations ranging from 1 to 10 nm, significantly stimulated the enzymatic levels of SFE in HF.
The sum of these findings suggests that IL-1伪 and GM-CSF are intrinsic cytokines secreted by UVB-exposed HK that stimulate expression of SFE by HF, leading to UVB-induced wrinkle formation.