Anti-allergic function of α-Tocopherol is mediated by suppression of PI3K-PKB activity in mast cells in mouse model of allergic rhinitis

Allergol Immunopathol (Madr). Jul-Aug 2020;48(4):395-400. doi: 10.1016/j.aller.2019.11.005. Epub 2020 Apr 23.

Abstract

Background: Alpha-Tocopherol (α-TCP), one major form of vitamin E, has been known as a treatment for airway allergic inflammation. However, the role and mechanism of α-TCP in treating allergic rhinitis remains unclear.

Objective: In this study we examined the inhibitory function of α-TCP in a mouse model of allergic rhinitis.

Methods: Allergic phenotype was examined by hematoxylin and eosin staining. Total IgE, OVA-specific IgE, OVA-specific IgG1 and OVA-specific IgG2a levels were examined by ELISA. mRNA expression was measured by qPCR, protein levels were examined by Western Blot.

Results: Histological analysis of the nasal membranes revealed that there was a significant reduction in inflammatory cells appearance in cross-sections in alpha-TCP treatment of Ovalbumin (OVA)-sensitized mice compared to OVA sensitized animals. In addition, eosinophils were significantly reduced in nasal mucosa of alpha-TCP treatment of OVA-sensitized mice compared to the OVA group. Lower total IgE, OVA-specific IgE, OVA-specific IgG1 and OVA-specific IgG2a levels were found in alpha-TCP treatment of OVA-sensitized mice compared to the OVA group. Furthermore, we found that the subepithelial distribution of tryptase positive mast cells was reduced in the alpha-TCP treatment of OVA-sensitized mice. More importantly, the PI3K-PKB pathway was suppressed by α-TCP in mast cells.

Conclusions: Our results demonstrated that α-TCP-mediated suppression of PI3K-PKB activity in mast cells is a potential mechanism of anti-allergic function of α-TCP.

Keywords: Allergic rhinitis; Animal model; OVA; PI3K-PKB; α-TCP.