A novel peanut allergy immunotherapy: Plant-based enveloped Ara h 2 Bioparticles activate dendritic cells and polarize T cell responses to Th1.

INTRODUCTION

As the only market-authorized allergen immunotherapy (AIT) for peanut allergy is accompanied by a high risk of side effects and mainly induces robust desensitization without sustained efficacy, novel treatment options are required. Peanut-specific plant-derived Bioparticles (BPs) surface expressing Ara h 2 at high density have been shown to be very hypoallergenic. Here, we assessed the dendritic cell (DC)-activating and T cell polarization capacity of these peanut-specific BPs.

METHODS

Route and kinetics of BP uptake were studied by (imaging) flow cytometry using monocyte-derived DCs incubated with fluorescently-labelled Ara h 2 BPs or natural Ara h 2 (nAra h 2) in the presence or absence of inhibitors that block pathways involved in macropinocytosis, phagocytosis, and/or receptor-mediated uptake. DC activation was monitored by flow cytometry (maturation marker expression) and ELISA (cytokine production). T cell polarization was assessed by co-culturing DCs exposed to Ara h 2 BPs or nAra h 2 with naïve CD4 T cells, followed by flow cytometry assessment of intracellular IFNγ (Th1) and IL-13 (Th2), and CD25CD127Foxp3 regulatory T cells (Tregs). The suppressive activity of Tregs was tested using a suppressor assay.

RESULTS

Ara h 2 BPs were taken up by DCs through actin-dependent pathways. They activated DCs demonstrated by an induced expression of CD83 and CD86, and production of TNFα, IL-6, and IL-10. BP-treated DCs polarized naïve CD4 T cells towards Th1 cells, while reducing Th2 cell development. Furthermore, BP-treated DCs induced reduced the frequency of Foxp3 Tregs but did not significantly affect T cell IL-10 production or T cells with suppressive capacity. In contrast, DC activation and Th1 cell polarization were not observed for nAra h 2.

CONCLUSION

Ara h 2 BPs activate DCs that subsequently promote Th1 cell polarization and reduce Th2 cell polarization. These characteristics mark Ara h 2 BPs as a promising novel candidate for peanut AIT.