Post-doctoral fellow Boston Children's Hosp., Harvard Med. Sch., Massachusetts, United States
Disclosure(s):
Floris van Dalen: No financial relationships to disclose
Introduction/Rationale: Allergic asthma is caused by hypersensitivity to airborne allergens such as dust mites and pollen. Current treatment includes allergen avoidance, systemic desensitization and symptom relief, none of which provide an effective cure. Thus, there is unmet need for transformative therapies that induce durable, antigen-specific tolerance in asthma.
Methods: Our nanobody-engineering approach co-delivers the allergen and glucocorticoids (dexamethasone) to all antigen-presenting cells (APCs) by targeting major histocompatibility complex class II (MHCII). This co-delivery ensures presentation of the allergen in a tolerogenic context and leads to anergy and/or deletion of allergen-specific B and T lymphocytes.
Results: We have established this approach in an ovalbumin model of allergic asthma. We found that intranasal delivery outperforms retro-orbital injection in a prophylactic setup. In pre-sensitized mice, a single dose of nanobody-adduct was sufficient to intercept the immunoglobulin (Ig) response and reduce allergic airway inflammation. We even see great response in mice treated in between ovalbumin challenges as model for intermittent asthma episodes. We have analyzed systemic and intranasal delivery by positron emission tomography and probed the engaged APC subsets by multiparametric cytofluorometry. We found that intranasal instillation persists in the lung for over 72 hours (PET) and directly engages B cells (flow), particularly pronounced in pre-sensitized mice. To assess the translational potential, we developed nanobody-adducts of house dust mite (HDM) allergen Der P 2 and tested this in patient samples of known HDM allergy.
Conclusion: Allergic asthma is a common disorder affecting >150 million people worldwide, though no curative treatment is available. We established a potent approach to intercept allergic airway inflammation in an ovalbumin mouse model. We will now analyze B cell and other APC subsets by single cell RNA sequencing to delineate the molecular mechanisms of tolerance induction.
