Bifidobacterium bifidum NCC 453 promotes tolerance induction in murine models of sublingual immunotherapy.

Background: Enhancing clinical efficacy remains a major goal in allergen-specific immunotherapy. In this study, we tested three strains of bifidobacteria as candidate adjuvants for sublingual allergy vaccines.

Methods: Probiotic candidates were evaluated in human monocyte-derived dendritic cell (h-DC) maturation and CD4(+) T-cell polarization in vitro models and further tested in murine models of sublingual immunotherapy in BALB/c mice sensitized to either ovalbumin or birch pollen.

Lactococcus lactis NCC 2287 alleviates food allergic manifestations in sensitized mice by reducing IL-13 expression specifically in the ileum.

Objective: Utilizing a food allergy murine model, we have investigated the intrinsic antiallergic potential of the Lactococcus lactis NCC 2287 strain.

Methods: BALB/c mice were sensitized at weekly intervals with ovalbumin (OVA) plus cholera toxin (CT) by the oral route for 7 weeks. In this model, an oral challenge with a high dose of OVA at the end of the sensitization period leads to clinical symptoms.

Induction of allergen-specific tolerance via mucosal routes.

Allergen-specific immunotherapy is the only curative treatment of allergies against insect venom, house dust mites, tree/grass pollens, or cat dander. Subcutaneous immunotherapy is successful to reorient the immune system and re-establish long-term tolerance. However, major drawbacks for using this route include: repeated injections, as well as the risk of anaphylaxis.

Identification of a new phenotype of tolerogenic human dendritic cells induced by fungal proteases from Aspergillus oryzae.

We characterized a new pathway to induce tolerogenic dendritic cells (DCs) following treatment of human monocyte-derived DCs with proteases from the fungus Aspergillus oryzae (ASP). ASP-treated DCs (ASP-DCs) exhibit a CD80(-)CD83(-)CD86(-)Ig-like transcript (ILT)2(-)ILT3(-)ILT4(+) phenotype, do not secrete cytokines or chemokines, and express tolerogenic markers such as glucocorticoid-induced leucine zipper, NO synthetase-2, retinaldehyde dehydrogenase-1 or retinaldehyde dehydrogenase-2. When cocultured with naive CD4(+) T cells, ASP-DCs induce an anergic state that can be reversed by IL-2.

Recombinant fusion proteins assembling Der p 1 and Der p 2 allergens from Dermatophagoides pteronyssinus.

Background: Fusion proteins assembling multiple allergens can be engineered by recombinant DNA technologies in order to produce tools for diagnostic and immunotherapeutic purposes. Herein, we developed and characterized chimeras assembling Der p 1 and Der p 2 allergens as potential candidate vaccines against house dust mite allergy.

Methods: Fusion proteins encompassing Der p 2 with either mature or proDer p 1 were expressed in Escherichia coli or Pichia pastoris.

Lactic acid bacteria as adjuvants for sublingual allergy vaccines.

We compared immunomodulatory properties of 11 strains of lactic acid bacteria as well as their capacity to enhance sublingual immunotherapy efficacy in a murine asthma model. Two types of bacterial strains were identified, including: (i) potent inducers of IL-12p70 and IL-10 in dendritic cells, supporting IFN-gamma and IL-10 production in CD4+ T cells such as Lactobacillus helveticus; (ii) pure Th1 inducers such as L. casei.

Early onset of action of a 5-grass-pollen 300-IR sublingual immunotherapy tablet evaluated in an allergen challenge chamber.

Background: The efficacy and safety of a 5-grass-pollen sublingual immunotherapy (SLIT) tablet (Stallergènes SA, Antony, France) have been evaluated in clinical studies during the pollen season. The allergen challenge chamber (ACC) has been developed as a pharmacodynamic assessment tool to control the environmental allergens and to avoid all problems associated with unpredictable pollen seasons.

Objective: We sought to evaluate the onset of action and efficacy of 300-IR (index of reactivity) SLIT tablets by using an ACC.

Human dendritic cells stimulated via TLR7 and/or TLR8 induce the sequential production of Il-10, IFN-gamma, and IL-17A by naive CD4+ T cells.

Depending upon which TLRs are triggered, dendritic cells (DCs) may orient the differentiation of naive CD4(+) T cells toward either Th1, Th2, regulatory T cells, or the recently defined Th17 lineage. In this study, we report that a dual stimulation of TLR4 and TLR7/8 with LPS plus R848 leads human monocyte-derived DCs (MoDCs) to produce multiple pro- and anti-inflammatory cytokines, including IL-10, IL-12, and IL-23. Surprisingly, a significant variability in the up-regulation of these cytokines is observed in DCs obtained from various healthy donors, with approximately one of three being "high responders.

Oral dendritic cells mediate antigen-specific tolerance by stimulating TH1 and regulatory CD4+ T cells.

Background: A detailed characterization of oral antigen-presenting cells is critical to improve second-generation sublingual allergy vaccines.

Objective: To characterize oral dendritic cells (DCs) within lingual and buccal tissues from BALB/c mice with respect to their surface phenotype, distribution, and capacity to polarize CD4(+) T-cell responses.

Methods: In situ analysis of oral DCs was performed by immunohistology.

Activation of natural regulatory T cells by IgG Fc-derived peptide "Tregitopes".

We have identified at least 2 highly promiscuous major histocompatibility complex class II T-cell epitopes in the Fc fragment of IgG that are capable of specifically activating CD4(+)CD25(Hi)FoxP3(+) natural regulatory T cells (nT(Regs)). Coincubation of these regulatory T-cell epitopes or "Tregitopes" and antigens with peripheral blood mononuclear cells led to a suppression of effector cytokine secretion, reduced proliferation of effector T cells, and caused an increase in cell surface markers associated with T(Regs) such as FoxP3. In vivo administration of the murine homologue of the Fc region Tregitope resulted in suppression of immune response to a known immunogen.

Assessment of Bet v 1-specific CD4+ T cell responses in allergic and nonallergic individuals using MHC class II peptide tetramers.

In this study, we used HLA-DRB1*0101, DRB1*0401, and DRB1*1501 peptide tetramers combined with cytokine surface capture assays to characterize CD4(+) T cell responses against the immunodominant T cell epitope (peptide 141-155) from the major birch pollen allergen Bet v 1, in both healthy and allergic individuals. We could detect Bet v 1-specific T cells in the PBMC of 20 birch pollen allergic patients, but also in 9 of 9 healthy individuals tested. Analysis at a single-cell level revealed that allergen-specific CD4(+) T cells from healthy individuals secrete IFN-gamma and IL-10 in response to the allergen, whereas cells from allergic patients are bona fide Th2 cells (producing mostly IL-5, some IL-10, but no IFN-gamma), as corroborated by patterns of cytokines produced by T cell clones.

Single cell assessment of allergen-specific T cell responses with MHC class II peptide tetramers: methodological aspects.

Background: We report herein critical methodological principles for assessing, at a single cell level, allergen-specific T cell responses using MHC class II peptide tetramers.

Methods: We developed MHC class II peptide tetramers to monitor T cell responses against the immunodominant Bet v 1(141-155) peptide in individuals with either an HLA-DRB1*0101, DRB1*0401 or DRB1*1501 background. In vitro stimulation was performed with serially truncated versions of the Bet v 1(141-155) epitope chemically conjugated to the Ii-Key peptide.

A synthetic triacylated pseudo-dipeptide molecule promotes Th1/TReg immune responses and enhances tolerance induction via the sublingual route.

In this study, we tested two triacylated pseudo-dipeptidic molecules, OM-197-MP-AC and OM-294-BA-MP as candidate adjuvants for allergy vaccines. Both molecules induce human dendritic cell (h-DC) maturation and polarize naïve T cells toward the Th1 type with IFNgamma production. Only OM-294-BA-MP induces IL10 gene expression both in monocyte-derived DCs and CD4+ naïve T cells.

IL-10-inducing adjuvants enhance sublingual immunotherapy efficacy in a murine asthma model.

Background: IL-10-inducing adjuvants could enhance the efficacy of allergy vaccines in establishing allergen-specific tolerance. The aim of this study was to identify such adjuvants using in vitro cultures of human and murine cells and to evaluate them in a therapeutic murine model of sublingual immunotherapy (SLIT).

Methods: Adjuvants stimulating IL-10 gene expression by human or murine immune cells were tested sublingually in BALB/c mice sensitized to ovalbumin (OVA), assessing the reduction in airway hyperresponsiveness (AHR) by whole-body plethysmography.

Improvement of sublingual immunotherapy efficacy with a mucoadhesive allergen formulation.

Background: Sublingual immunotherapy is a noninvasive and efficacious treatment of type I respiratory allergies. A murine model of sublingual immunotherapy is needed to understand better the immune mechanisms involved in successful immunotherapy and to assess second-generation candidate vaccines.

Objective: Herein, we developed a therapeutic murine model of sublingual immunotherapy in which we document the value of mucoadhesive formulations to enhance treatment efficacy.

Suspension-cultured BY-2 tobacco cells produce and mature immunologically active house dust mite allergens.

The replacement of crude allergen extracts by selected allergens currently represents a major goal for the improvement of allergy diagnosis and immunotherapy. Indeed, the development of molecularly defined vaccines would facilitate both standardization and enhance batch-to-batch reproducibility as well as treatment specificity. In this study, we have investigated the potential of tobacco plant cells to produce biologically active forms of the two major allergens from the house dust mite.

Novel ways for immune intervention in immunotherapy: mucosal allergy vaccines.

Allergen-specific immunotherapy is currently the only curative treatment for allergy. Subcutaneous immunotherapy (SCIT) has been successfully used to treat patients who are allergic to insect venom, house dust mites, or tree or grass pollens. In the context of potentially severe, albeit infrequent, side effects associated with SCIT, mucosal routes of administration are being investigated to conduct allergenic desensitization.

Trypanosoma cruzi down-regulates lipopolysaccharide-induced MHC class I on human dendritic cells and impairs antigen presentation to specific CD8(+) T lymphocytes.

Trypanosoma cruzi, the etiological agent of Chagas' disease, may persist for many years in its mammalian host. This suggests escape from the immune response and particularly a suboptimal CD8(+) T cell response, since these cells are involved in infection control. In this report, we show that T.