Blomia tropicalis mite is highly prevalent in tropical and subtropical regions and it is associated with allergic diseases such as rhinitis and asthma.

A new study published in the Journal of Leukocyte Biology evaluated the effect of CpG-ODN – a specific synthetic toll like receptors (TLR)-9 agonist, on the development of experimental asthma induced by Blomia tropicalis extract—a relevant source of aeroallergens.

The findings revealed that among different protocols of Blomia tropicalis extract sensitization, subcutaneous sensitization in the presence of alum adjuvant induced the highest Th2 responses, including high IgE levels. On the other hand, adsorption of CpG to Blomia tropicalis extract/alum attenuated the airway hyperreactivity, infiltration of inflammatory cells including eosinophils, and IL-5 content in bronchoalveolar lavage. Additionally, lung peribronchial inflammatory infiltrate, mucus production and IL-5-producing CD3+ CD4+ T cells were significantly reduced in the Blomia tropicalis extract/alum+CpG group. In fact, CpG inhibited total IgE production, as well as active systemic or cutaneous anaphylaxis reactions. Moreover, the inhibition of pulmonary Th2 responses was associated with increased IL-10 production, but not with IFN-γ production.

The results underscored the mechanisms of allergy attenuation by CpG and indicated the potential use of alum-based formulation with CpG to treat allergic processes.