β-catenin mediates the inflammatory cytokine expression induced by the Der p 1 house dust mite allergen.

The modulations of β-catenin were analyzed during the inflammatory response induced by the Der p 1 house dust mite allergen. Der p 1 induced the dose-dependent expression of inflammatory cytokines, including interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in THP-1 human monocytic cells. The mRNA expression levels of β-catenin were not altered, however protein levels increased following Der p 1 treatment, demonstrating that β-catenin was modulated by post-transcriptional processes. It was also revealed that nuclear β-catenin levels were significantly increased while cytoplasmic β-catenin levels were reduced, which demonstrated the nuclear translocation of β-catenin by the Der p 1 allergen. Glycogen synthase kinase 3β (GSK3β), a regulator of β-catenin stability, was demonstrated to be phosphorylated following Der p 1 treatment. When β-catenin was knocked down by the transfection of its small interfering RNA (siRNA), inflammatory cytokine expression as well as nuclear factor-κB (NF-κB) activity, which were induced by Der p 1 treatment, were all significantly reduced. The results demonstrated that Der p 1-induced inflammatory responses were mediated by β-catenin.