CCR10+ ILC2s with ILC1-like properties exhibit a protective function in severe allergic asthma.

BACKGROUND: We previously showed that patients with severe allergic asthma have high numbers of circulating ILC2s expressing CCR10. METHOD: Herein, CCR10+ ILC2s were further analyzed in the blood of healthy individuals or patients with allergic and non-allergic asthma. Characteristics of human CCR10+ and CCR10- ILC2s were assessed by flow cytometry as well as single-cell multiplex RT-qPCR. The role of CCR10+ ILC2s in asthma pathophysiology was studied in allergen-treated mice. RESULTS: When compared to healthy controls, CCR10+ ILC2s are enriched in the blood of both allergic and non-allergic severe asthmatic patients, and these cells are recruited to the lungs. Plasma concentrations of the CCR10 ligand CCL27 are significantly increased in severe asthmatics when compared to non-asthmatic patients. CCR10+ ILC2s secrete little TH 2 cytokines, but exhibit ILC1-like properties, including a capacity to produce IFN-γ. Also, single-cell analysis reveals that the CCR10+ ILC2 subset is enriched in cells expressing amphiregulin. CCR10+ ILC2 depletion, as well as blocking of IFN-γ activity, exacerbates airway hyperreactivity in allergen-challenged mice, providing evidence for a protective role of these cells in allergic inflammation. CONCLUSIONS: Frequencies of circulating CCR10+ ILC2s and CCL27 plasma concentrations represent candidate markers of asthma severity. The characterization of CCR10+ ILC2s in human samples and in mouse asthma models suggests that these cells downregulate allergic inflammation through IFN-γ production.

Sialylated Fetuin-A as a candidate predictive biomarker for successful grass pollen allergen immunotherapy.

BACKGROUND: Eligibility to immunotherapy is based on the determination of IgE reactivity to a specific allergen by means of skin prick or in vitro testing. Biomarkers predicting the likelihood of clinical improvement during immunotherapy would significantly improve patient selection. METHODS: Proteins were differentially assessed by using 2-dimensional differential gel electrophoresis and label-free mass spectrometry in pretreatment sera obtained from clinical responders and nonresponders within a cohort of 82 patients with grass pollen allergy receiving sublingual immunotherapy or placebo. Functional studies of Fetuin-A (FetA) were conducted by using gene silencing in a mouse asthma model, human dendritic cell in vitro stimulation assays, and surface plasmon resonance. RESULTS: Analysis by using quantitative proteomics of pretreatment sera from patients with grass pollen allergy reveals that high levels of O-glycosylated sialylated FetA isoforms are found in patients exhibiting a strong decrease in rhinoconjunctivitis symptoms after sublingual immunotherapy. Although FetA is involved in numerous inflammatory conditions, its potential role in allergy is unknown. In vivo silencing of the FETUA gene in BALB/c mice results in a dramatic upregulation of airway hyperresponsiveness, lung resistance, and TH2 responses after allergic sensitization to ovalbumin. Both sialylated and nonsialytated FetA bind to LPS, but only the former synergizes with LPS and grass pollen or mite allergens to enhance the Toll-like receptor 4-mediated proallergic properties of human dendritic cells. CONCLUSIONS: As a reflection of the patient's inflammatory status, pretreatment levels of sialylated FetA in the blood are indicative of the likelihood of clinical responses during grass pollen immunotherapy.

A regulatory dendritic cell signature correlates with the clinical efficacy of allergen-specific sublingual immunotherapy.

BACKGROUND: Given their pivotal role in the polarization of T-cell responses, molecular changes at the level of dendritic cells (DCs) could represent an early signature indicative of the subsequent orientation of adaptive immune responses during immunotherapy. OBJECTIVE: We sought to investigate whether markers of effector and regulatory DCs are affected during allergen immunotherapy in relationship with clinical benefit. METHODS: Differential gel electrophoresis and label-free mass spectrometry approaches were used to compare whole proteomes from human monocyte-derived DCs differentiated toward either regulatory or effector functions. The expression of those markers was assessed by using quantitative PCR in PBMCs from 79 patients with grass pollen allergy enrolled in a double-blind, placebo-controlled clinical study evaluating the efficacy of sublingual tablets in an allergen exposure chamber over a 4-month period. RESULTS: We identified several markers associated with DC1 and/or DC17 effector DCs, including CD71, FSCN1, IRF4, NMES1, MX1, TRAF1. A substantial phenotypic heterogeneity was observed among various types of tolerogenic DCs, with ANXA1, Complement component 1 (C1Q), CATC, GILZ, F13A, FKBP5, Stabilin-1 (STAB1), and TPP1 molecules established as shared or restricted regulatory DC markers. The expression of 2 of those DCs markers, C1Q and STAB1, was increased in PBMCs from clinical responders in contrast to that seen in nonresponders or placebo-treated patients. CONCLUSION: C1Q and STAB1 represent candidate biomarkers of early efficacy of allergen immunotherapy as the hallmark of a regulatory innate immune response predictive of clinical tolerance.

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. RESULTS: Bifidobacterium adolescentis, B. bifidum and B. longum induced h-DC maturation and polarized naïve CD4(+) T cells toward interferon-γ and interleukin-10 production. B. bifidum increased CD25(high), Foxp3(+) cells within CD4(+) T lymphocytes and was the most potent inducer of interferon-γ in Th2-skewed peripheral blood mononuclear cells and h-DC T-cell cocultures. It also induced a significant decrease in airway hyperresponsiveness in BALB/c mice sensitized to ovalbumin. Sublingual administration of B. bifidum together with recombinant Bet v 1 enhanced tolerance induction in BALB/c mice sensitized to birch pollen, with a downregulation of both airway hyperresponsiveness, lung inflammation and Bet v 1-specific Th2 responses. CONCLUSIONS: Due to its capacity to reorient established Th2 responses toward Th1/regulatory T-cell profiles, B. bifidum represents a valid candidate adjuvant for specific immunotherapy of type I allergies.

Expression and characterization of natural-like recombinant Der p 2 for sublingual immunotherapy.

BACKGROUND: Recombinant allergens with a native conformation represent an alternative to natural extracts for immunotherapy and diagnostic purposes. METHODS: We produced the Der p 2 mite allergen in Pichia pastoris and Escherichia coli. After purification by cation exchange chromatography, recombinant molecules were compared to their natural counterpart based upon structural (disulfide bonds, secondary structure, thermal stability) and immunological properties (antibody reactivity, basophil and T cell activation, tolerance induction in a murine sublingual immunotherapy model). RESULTS: The Der p 2.0101 isoform was confirmed to be prevalent in Dermatophagoides pteronyssinus extracts. It was then produced as a secreted molecule in P. pastoris or refolded from E. coli inclusion bodies. The yeast-expressed rDer p 2 molecule exhibits a natural-like disulfide bridge distribution and secondary structure, whereas the E. coli-derived rDer p 2 presents some heterogeneity in cysteine bonds and a lower stability following thermal stress. The two recombinant as well as natural Der p 2 molecules exhibit comparable IgE recognition and activate basophil and CD4+ T cells. Sublingual immunotherapy of nDer p 2- sensitized mice using either one of the rDer p 2 molecules efficiently decreases airway hyperresponsiveness as well as Th2 responses. CONCLUSIONS: Natural and recombinant Der p 2 molecules produced in P. pastoris and E. coli exhibit comparable immunological properties despite distinct structural features. Natural-like cysteine pairing is a critical parameter to identify stable, well-folded and homogenous proteins appropriate for immunotherapy and diagnostic purposes.

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. Lactococcus lactis NCC 2287 was given to mice via the drinking water during sensitization (prevention phase) or after sensitization (management phase). RESULTS: Lactococcus lactis NCC 2287 administration to sensitized mice strikingly reduced allergic manifestations in the management phase upon challenge, when compared to control mice. No preventive effect was observed with the strain. Lactococcus lactis NCC 2287 significantly decreased relative expression levels of the Th-2 cytokine, IL-13, and associated chemokines CCL11 (eotaxin-1) and CCL17 (TARC) in the ileum. No effect was observed in the jejunum. CONCLUSION/SIGNIFICANCE: These results taken together designate Lactococcus lactis NCC 2287 as a candidate probiotic strain appropriate in the management of allergic symptoms.

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." High responding MoDCs stimulated via TLR4 and TLR7/8 induce naive allogeneic CD4(+) T cell to secrete sequentially IL-10 and IFN-gamma, and eventually IL-17A, whereas low responding MoDCs only stimulate IFN-gamma production. Both TLR7 and TLR8 play a central role in this phenomenon: TLR4 triggering with LPS up-regulates TLR7 expression on human MoDCs from high responders, silencing of either TLR7 or TLR8 mRNAs inhibits cytokine production in LPS plus R848-treated MoDCs, and plasmacytoid DCs constitutively expressing high levels of TLR7 induce the production of IL-10, IFN-gamma, and IL-17A by naive T cells when stimulated with R848 alone. Collectively, our results illustrate the synergy between TLR4 and TLR7/8 in controlling the sequential production of regulatory and proinflammatory cytokines by naive CD4(+) T cells. The observed polymorphism in DC responses to such TLR-mediated stimuli could explain differences in the susceptibility to infectious pathogens or autoimmune diseases within the human population.

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. Forms with mutation in Der p 1 catalytic site were also engineered. Purified chimeras were characterized by immunoblotting, circular dichroism, disulfide bond mapping, basophil and T lymphocyte stimulation assays. RESULTS: Four fusion proteins were expressed in E. coli as inclusion bodies, whereas only chimeras comprising proDer p 1 were obtained in yeast. All such hybrids formed polymers and aggregates, and yeast-expressed chimeras were unstable. Circular dichroism analysis performed after refolding of bacteria expressed chimeras encompassing mature Der p 1 confirmed partial folding, consistent with the occurrence of both correct and inappropriate intramolecular disulfide bonds. All fusion molecules were recognized by Der p 1- and Der p 2-specific human IgEs, monoclonal and polyclonal antibodies. Fusion proteins activate basophils from mite-allergic patients and trigger the proliferation of specific CD4+ T cells, albeit to a lower level when compared to individual allergens. CONCLUSIONS: Production of multiple Der p 1-Der p 2 fusion proteins exhibiting partial folding and proper antigenic properties has been achieved. Nonetheless, significant solubility and stability issues currently limit the application of such chimeras for immunotherapy or diagnostic.

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. The induction of regulatory T cells (T(reg)) was evaluated using phenotypic and functional assays. T-cell proliferation in cervical lymph nodes (LNs) was assessed following intravenous transfer of CFSE-labelled OVA-specific T cells and FACS analysis. RESULTS: A combination of 1,25-dihydroxyvitamin D3 plus dexamethasone (VitD3/Dex) as well as Lactobacillus plantarum were found to induce IL-10 production by human and murine dendritic cells (DCs). The former inhibits LPS-induced DC maturation, whereas L. plantarum induces DC maturation. Following stimulation with VitD3/Dex-pretreated DCs, CD4+ naïve T cells exhibit a T(reg) profile. In contrast, a Th1/T(reg) pattern of differentiation is observed in the presence of DCs treated with L. plantarum. Both adjuvants significantly enhance SLIT efficacy in mice, in association with either induction of Foxp3+ T(reg) cells (for VitD3/Dex) or proliferation of OVA-specific T cells in cervical LNs (for L. plantarum). CONCLUSIONS: Both VitD3/Dex and L. plantarum polarize naïve T cells towards IL-10-expressing T cells, through distinct mechanisms. As adjuvants, they both enhance SLIT efficacy in a murine asthma model.

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. Sublingual administration in ovalbumin-sensitized mice of L. helveticus, but not L. casei, reduced airways hyperresponsiveness, bronchial inflammation and proliferation of specific T cells in cervical lymph nodes. Thus, probiotics acting as a Th1/possibly Treg, but not Th1 adjuvant, potentiate tolerance induction via the sublingual route.

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. Sublingual administration of OM-294-BA-MP plus the antigen enhances tolerance induction in BALB/c mice with established asthma to ovalbumin with an impact on both airways hyperresponsiveness and lung inflammation. Given its Th1/Treg polarizing properties, OM-294-BA-MP is a valid candidate for sublingual allergy vaccines.