Oral myeloid cells uptake allergoids coupled to mannan driving Th1/Treg responses upon sublingual delivery in mice

Background: Allergen-specific immunotherapy (AIT) is the only available treatment for allergic diseases that can induce specific immune tolerance to allergens. The key mechanisms involved in this process include changes in allergen-specific regulatory T (Treg) cells. Methods:We studied 25 allergic rhinitis patients undergoing subcutaneous house dust mite-specific immunotherapy. Peripheral blood mononuclear cells were studied before and after 10, 30 weeks, and 3 years of AIT. Der p 1-specific T regulatory cell responses were investigated by characterization of Der p 1-MHC class II tetramerpositive cells and correlated with nasal symptom score. Results: Twelve of 25 AIT patients matched with their MHC class II expression to the Der p 1 peptide-MHC class II tetramers. A significant increase in the numbers of Der p 1-specific FOXP3 + Helios + CD25 + CD127 − Treg cells after 30 weeks was observed, which slightly decreased after 3 years of AIT. In contrast, Der p 1-specific immunoglobulin-like transcript 3 (ILT3) + CD25 + Treg cells decreased substantially from baseline after 3 years of AIT. ILT3 + Treg cells displayed compromised suppressive function and low FOXP3 expression. In addition, Der p 1-specific IL-10 and IL-22 responses have increased after 30 weeks, but only IL-10 + Der p 1-specific Treg cells remained present at high frequency after 3 years of AIT. Increased number of FOXP3 + Helios + and IL-10 + and decreased ILT3 + Treg cell responses correlated with improved allergic symptoms. Conclusion: The results indicate that AIT involves upregulation of the activated allergen-specific Treg cells and downregulation of dysfunctional allergen-specific Treg cell subset. Correction of dysregulated Treg cells responses during AIT is associated with improved clinical response. K E Y W O R D Sallergen-specific T cells, antigen-specific immunotherapy, house dust mite allergy, Treg Abbreviations: AIT, antigen-specific immunotherapy; AR, allergic rhinitis; HDM, house dust mite; ILT3, immunoglobulin-like transcript 3; Treg, T regulatory.

Section: Discussionsupporting

confidence: 91%

Der p 1‐specific regulatory T‐cell response during house dust mite allergen immunotherapy

Boonpiyathad

Sokołowska

Morita

et al. 2019

“…Recent findings have shown that allergoids conjugated to nonoxidized mannan from Saccharomyces cerevisiae are next‐generation vaccines targeting DCs through CLRs. These vaccines are candidates for AIT of allergic diseases as they promote the generation of Treg cells by mechanisms partially depending on programmed death‐ligand 1 (PD‐1) and IL‐10 in both humans and mice . Phase II clinical trials for grass‐pollen and house dust mite allergens are currently ongoing …”

Section: C‐type Lectin Receptorsmentioning

confidence: 99%

Innate immunity in allergy

Maeda

Caldez

Akira

2019

Innate immune system quickly responds to invasion of microbes and foreign substances through the extracellular and intracellular sensing receptors, which recognize distinctive molecular and structural patterns. The recognition of innate immune receptors leads to the induction of inflammatory and adaptive immune responses by activating downstream signaling pathways. Allergy is an immune‐related disease and results from a hypersensitive immune response to harmless substances in the environment. However, less is known about the activation of innate immunity during exposure to allergens. New insights into the innate immune system by sensors and their signaling cascades provide us with more important clues and a framework for understanding allergy disorders. In this review, we will focus on recent advances in the innate immune sensing system.

“…9,10 In mice, subcutaneous or sublingual immunization with PM increases the frequency of splenic FOXP3 + Treg cells and induces healthy immune responses to allergens. 9,11,13 All these beneficial effects depend on the structural integrity of the conjugated mannan. 9,[12][13][14] Aluminium hydroxide (alum) remains the most widely used adjuvant in AIT.…”

Section: Introductionmentioning

confidence: 99%

Alum impairs tolerogenic properties induced by allergoid‐mannan conjugates inhibiting mTOR and metabolic reprogramming in human DCs

Benito-Villalvilla

Soria

Pérez‐Diego

et al. 2019

Self Cite

Background Polymerized allergoids conjugated to mannan (PM) are suitable vaccines for allergen‐specific immunotherapy (AIT). Alum remains the most widely used adjuvant in AIT, but its way of action is not completely elucidated. The better understanding of the mechanisms underlying alum adjuvanticity could help to improve AIT vaccine formulations. Objective We sought to investigate the potential influence of alum in the tolerogenic properties imprinted by PM at the molecular level. Methods Flow cytometry, ELISAs, cocultures, intracellular staining and suppression assays were performed to assess alum and PM effects in human dendritic cells (DCs). BALB/c mice were immunized with PM alone or adsorbed to alum. Allergen‐specific antibodies, splenocyte cytokine production and splenic forkhead box P3 (FOXP3)+ regulatory T (Treg) cells were quantified. Metabolic and immune pathways were also studied in human DCs. Results Alum decreases PD‐L1 expression and IL‐10 production induced by PM in human DCs and increases pro‐inflammatory cytokine production. Alum impairs PM‐induced functional FOXP3+ Treg cells and promotes Th1/Th2/Th17 responses. Subcutaneous immunization of mice with PM plus alum inhibits in vivo induction of Treg cells promoted by PM without altering the capacity to induce functional allergen‐specific blocking antibodies. Alum inhibits mTOR activation and alters metabolic reprogramming by shifting glycolytic pathways and inhibiting reactive oxygen species (ROS) production in PM‐activated DCs, impairing their capacity to generate functional Treg cells. Conclusion We uncover novel mechanisms by which alum impairs the tolerogenic properties induced by PM, which might well contribute to improve the formulation of novel vaccines for AIT.