Targeting Toll-like receptor 7 (TLR7) is known to have a potential therapeutic effect on experimental allergic asthma, but the exact mechanism is incompletely understood. To investigate the potential therapeutic effect of TLR7 agonist (TLR7a) a new versatile TLR7 agonist conjugated to Der f 1 was synthesized and evaluated in vivo here. It was confirmed that the course of airway hyperresponsiveness (AHR) and eosinophilia of the TLR7a vaccine-treated mice were limited. Levels of specific IgG1, IgG2a and IgE antibodies of these mice were changed obviously compared with that of the model mice. The expression of T helper 2 cytokine, interleukin (IL)-4, production in bronchoalveolar lavage fluid (BALF) and splenocytes were significantly decreased, while the levels of IFN-γ, IL-12 and IL-10 were increased after the treatment of TLR7a vaccine. In addition, Muc5 expression and goblet cells were significantly decreased in the lung tissue of asthma model mice treated with TLR7a plus Der f 1. These results suggest that the TLR7a-Der f 1 vaccine exhibits interesting therapeutic potency in suppressing allergic asthma and could be used a new agent in the treatment of allergic diseases.
Keywords: Allergic asthma; Der f-1; TLR7 agonist; adjuvant; dust mite; immunotherapy.