CpG-ODNs and Budesonide Act Synergistically to Improve Allergic Responses in Combined Allergic Rhinitis and Asthma Syndrome Induced by Chronic Exposure to Ovalbumin by Modulating the TSLP-DC-OX40L Axis

The experimental model of combined allergic rhinitis and asthma syndrome (CARAS) has shown that CpG oligodeoxynucleotides (CpG-ODNs) are potential inhibitors of type 2 helper cell-driven inflammatory responses. Currently available CpG-ODNs modestly inhibit allergic responses in CARAS, while a combination strategy for upper airway treatment by co-administration of CpG-ODNs and glucocorticoids may show good efficacy. This study aimed to assess the therapeutic effects of CpG-ODNs combined with budesonide (BUD) on upper and lower-airway inflammation and remodeling in mice with CARAS induced by chronic exposure to ovalbumin (OVA), exploring the possible underlying molecular mechanisms. A BALB/c mouse model of chronic CARAS was established by systemic sensitization and repeated challenge with OVA. Treatment with CpG-ODNs or BUD by intranasal administration was started 1 h after OVA challenge. Then, nasal mucosa and lung tissues were fixed and stained for pathologic analysis. The resulting immunologic variables and TSLP-DC-OX40L axis parameters were evaluated. Both CpG-ODNs and BUD intranasal administration are effective on reducing Th2-type airway inflammation and tissue remodeling. Co-administration of CpG-ODNs and BUD was more effective than each monotherapy in attenuating upper and lower-airway inflammation as well as airway remodeling in chronic CARAS. Notably, combination of CpG-ODNs with BUD modulated the TSLP-DC-OX40L axis, as demonstrated by decreased TSLP production in the nose and lung, alongside decreased TSLPR and OX40L in DC. Intranasal co-administration of CpG-ODNs and BUD synergistically alleviates airway inflammation and tissue remodeling in experimental chronic CARAS, through shared cellular pathways, as a potent antagonist of the TSLP-DC-OX40L axis.