Background:
Immunological mechanism of action of allergoids remains poorly understood. Previous models of allergenicity and immunogenicity have yielded sub-optimal knowledge of these immunotherapeutic vaccine products. Novel single-cell RNA-seq technology offers a bridge to this gap in knowledge.
Objective:
To identify the underpinning tolerogenic molecular and cellular mechanisms of depigmented-polymerized Phleum pratense extract.
Methods
The molecular mechanisms underlying native Phleum pratense (Phl p), depigmented Phl p (DPG-Phl p), and depigmented-polymerized (DPG-POL-Phl p) allergoid were investigated using scRNA-seq. Allergen-specific Th2A, Tfh and IL-10+ Breg cells were quantified by flow cytometry in PBMCs from 16 grass pollen allergics (GPA) and 8 non-atopic controls (NAC). The ability of Phl p, DPG-Phl p and DPG-POL-Phl p to elicit FcεRI and FcεRII-mediated IgE responses was measured by basophil activation test and IgE-FAB assay.
Results:
ScRNA-seq analysis revealed that DPG-POL-Phl p downregulated genes associated with Th2 signaling, induced functional Tregs exhibiting immunosuppressive roles through CD52 and Siglec-10, modulated genes encoding immunoproteasome that dysregulate the processing and presentation of antigens to T cells and promoted a shift from IgE towards an IgA1 and IgG responses. In GPA, DPG-POL-Phl p exhibited reduced capacity to elicit proliferation of Th2A, IL-4+ Tfh and IL-21+ Tfh cells whilst being the most prominent at inducing CD19+CD5hiIL-10+ and CD19+CD5hiCD38intCD24intIL-10+ Breg cell subsets compared to Phl p (all, P<.05). Furthermore, DPG-POL-Phl p demonstrated a hypoallergenic profile through basophil activation and histamine release compared to Phl p (31.54-fold, P<.001).
Conclusions:
ScRNA-seq provides an in-depth resolution of the mechanisms underlying the tolerogenic profile of DPG-POL-Phl p.