α2-3 Sialic acids-decorated allergens exert a tolerogenic effect on CD4 T cells from Der p 2 - allergic patients.

Background: Allergen-specific immunotherapy (AIT) is so far the only disease-modifying therapy for allergy, resulting in a long-lasting tolerance. However, the existing safety concerns and the need for more efficacious alternatives that shorten the duration of treatment have stimulated research into the development of novel alternatives. Some of these novel alternatives involve modifying allergens with molecules that target innate immunomodulatory receptors to suppress the immune activity of immune cells.

Method: Freshly prepared monocyte-derived dendritic cells (moDCs) from mite-allergic and non-atopic volunteers were treated with α2-3 sialic acid-conjugated recombinant Der p 2 ((sia)-Der p 2) and unconjugated Der p 2 in culture and matured with Toll-like receptor (TLR) 1/2 (Pam3CSK4) (Pam3) and 2/4 (lipopolysaccharide) (LPS) agonists, followed by co-culture with autologous CD4+ T cells. Secretion of cytokines in supernatants were measured by ELISA and expression of cell surface and intracellular markers was measured by flow cytometry.

Results: Sia-Der p 2 unlike Der p 2, modulated moDCs from mite-allergic volunteers by reducing expression of CD83 and CXCR5. We also observed that sia-Der p 2-treated moDCs in the presence of Pam3 and LPS significantly suppressed the proportion of CD25+, Ki67+, IL-13+ and IFN-y+ CD4+ T cells of mite-allergic volunteers while Der p 2-treated moDCs did not. Sia-Der p 2-treated moDC did not alter these CD4+ T cell populations in non-atopic volunteers.

Conclusion: Our data suggests that Der p 2 conjugated with α2-3 sialic acids modifies moDCs and promotes the differentiation of allergen specific CD4+ T cells towards a regulatory profile.