Ameliorative effects of Paulownia tomentosa flower absolute on atopic dermatitis-related responses in mast cells and keratinocytes and its chemical composition

Abstract

Paulownia tomentosa (PT) exhibits diverse biological activities, including anti-inflammatory and antioxidant effects; however, its potential effects on atopic dermatitis (AD) are unclear. The present study examined the effects of PT flower absolute (PTFAb) on AD-related responses, particularly mast cell activation and keratinocyte barrier-related responses. PTFAb was isolated from PT flowers using a solvent extraction method and its chemical composition was analyzed by gas chromatography/mass spectrometry, through which 13 components were identified. In vitro biological tests on rat basophilic leukemia cells (RBL-2H3 cells; a commonly used mast cell model) and human epidermal keratinocytes (HaCaT cells) were performed using water-soluble tetrazolium salt, 5-bromo-2′-deoxyuridine incorporation, Boyden chamber, immunoblotting and enzyme-linked immunosorbent assay methods. All experiments were conducted on cells at nontoxic PTFAb concentrations. PTFAb reduced the expression of the v-soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins vesicle-associated membrane protein (VAMP)7 and VAMP8 in RBL-2H3 cells. In RBL-2H3 cells stimulated with anti-dinitrophenyl (DNP)-immunoglobulin E and DNP-bovine serum albumin, PTFAb suppressed the release of β-hexosaminidase and histamine (indicators of mast cell degranulation), and the phosphorylation of spleen tyrosine kinase, phosphatidylinositol 3-kinase and protein kinase B. PTFAb also induced proliferation, migration, and type I and IV collagen synthesis. Furthermore, PTFAb upregulated tumor necrosis factor-α (TNF-α)-reduced filaggrin expression and the expression of hyaluronan synthase (HAS)-2 and HAS-3 in HaCaT cells, and reduced TNF-α-increased intercellular adhesion molecule-1 expression in HaCaT cells. In conclusion, PTFAb may exert inhibitory effects on mast cell degranulation-related responses and potentiate skin barrier-related responses, suggesting its potential to modulate AD-related cellular responses or skin barrier function.