Ameliorative Effect of Melittin Encoded DNA Plasmid in an Ovalbumin-induced Murine Model of Allergy

Melittin is a natural toxin used in traditional medicine as an anti-inflammatory drug. It seems that the anti-inflammatory properties of melittin are caused by suppressing the expression of inflammatory genes and inhibiting signaling pathways. However, the use of melittin is limited due to instability, rapid degradation, and impurity. The aim of this study was to investigate the intranasal administration of a melittin-encoded plasmid as a new melittin delivery method for allergic diseases. After the induction of a mouse model of allergic rhinitis, mice received intranasal melittin plasmid. After the final challenge with allergen and allergic symptom assessment, the required samples were collected and transforming growth factor-beta (TGF-β), interferon-gamma (IFN-γ), and interleukin-4 (IL-4) cytokine levels, serum levels of ovalbumin-specific immunoglobulin (Ig) E, and histopathological changes were assessed. In addition to investigating the immune response, the effect of melittin on the expression level of genes involved in apoptosis was also investigated. The melittin plasmid significantly improved nasal symptoms and decreased eosinophil infiltration into the nasal mucosa. Moreover, melittin decreased the expression levels of IL-4 and TGF-β in nasal lavage fluid, while IFN-γ expression was increased. Regarding the expression level of genes involved in apoptosis, melittin led to an increase in BAX mRNA expression. These results suggest intranasal administration of a plasmid encoding melittin can suppress nasal symptoms, eosinophil infiltration, and immunomodulation of the immune response, which can be considered a promising approach in the treatment of inflammatory diseases.