Gap junctions (GJ) are known to be involved in spontaneous wound healing in rodent skin. We analyzed the staining patterns of the GJ proteins Cx26, Cx30, and Cx43 in human cutaneous wound healing and compared ex vivo spontaneous wound healing to non-healing wounds (chronic leg ulcers) and to ex vivo accelerated wound healing after transplantation of cultured keratinocytes. We demonstrate a loss of Cx43 staining at the wound margins during initial wound healing and after transplantation of keratinocytes. In contrast, Cx43 remains present at the margins of most non-healing wounds. We show a subsequent induction of Cx26 and Cx30 near the wound margins in spontaneous wound healing and-even earlier-after the transplantation of keratinocytes. The cells at the wound margins remain negative until the commencement of epidermal regeneration. Cx26/30 are present at the wound margins of most non-healing wounds. Cx stainings are absent in the transplanted keratinocytes during early wound healing, but there is a subsequent induction. Our results suggest that the downregulation of Cx43 is an important event in human wound healing. We discuss the assumption that direct cell-cell communication via GJ contribute to the acceleration of wound healing after the transplantation of keratinocytes.

The signaling pathways that sustain the disease process of chronic rhinosinusitis with nasal polyps (CRSwNP) remain poorly understood. We sought to determine the expression levels of Wnt signaling genes in CRSwNP and to study the role of the Wnt pathway in inflammation and epithelial remodeling in the nasal mucosa. Microarrays and real time-quantitative polymerase chain reaction comparing gene expression in matched NPs and inferior turbinates revealed that WNT2B, WNT3A, WNT4, WNT7A, WNT7B, and FZD2 were up-regulated and that FZD1, LRP5, LRP6, and WIF1 were down-regulated in NPs. Immunolabeling showed robust expression of Wnt ligands, nuclear β-catenin, and Axin-2 in NP tissue, suggesting that Wnt/β-catenin signaling is activated in NPs. We used primary human nasal epithelial cell (HNEpC) cultures to test the functional consequences of Wnt pathway activation. Monolayer HNEpCs treated with recombinant human WNT (rhWNT) 3A, but not with rhWNT4, had altered epithelial morphology and decreased adhesion, without loss of viability. We found that neither rhWNT3A nor rhWNT4 treatment induced proliferation. The expression and release of inflammatory cytokines IL-6 and granulocyte-macrophage colony-stimulating factor were increased after rhWNT3A exposure of HNEpCs. When differentiated at an air-liquid interface, rhWNT3A- and WNT agonist-, but not rhWNT4-treated HNEpCs, had abnormal epithelial architecture, failed to undergo motile ciliogenesis, and had defective noncanonical Wnt (planar cell polarity) signaling. On the basis of these results, we propose a model in which Wnt/β-catenin signaling sustains mucosal inflammation and leads to a spectrum of changes consistent with those seen during epithelial remodeling in NPs.