Initial immunological changes as predictors for house dust mite immunotherapy response

Immune signatures predict response to house dust mite subcutaneous immunotherapy in patients with allergic rhinitis

BACKGROUND

Identifying predictive biomarkers for allergen immunotherapy response is crucial for enhancing clinical efficacy. This study aims to identify such biomarkers in patients with allergic rhinitis (AR) undergoing subcutaneous immunotherapy (SCIT) for house dust mite allergy.

METHODS

The Tongji (discovery) cohort comprised 72 AR patients who completed 1-year SCIT follow-up. Circulating T and B cell subsets were characterized using multiplexed flow cytometry before SCIT. Serum immunoglobulin levels and combined symptom and medication score (CSMS) were assessed before and after 12-month SCIT. Responders, exhibiting ≥30% CSMS improvement, were identified. The random forest algorithm and logistic regression analysis were used to select biomarkers and establish predictive models for SCIT efficacy in the Tongji cohort, which was validated in another Wisco cohort with 43 AR patients.

RESULTS

Positive SCIT response correlated with higher baseline CSMS, allergen-specific IgE (sIgE)/total IgE (tIgE) ratio, and frequencies of Type 2 helper T cells, Type 2 follicular helper T (TFH2) cells, and CD23+ nonswitched memory B (BNSM) and switched memory B (BSM) cells, as well as lower follicular regulatory T (TFR) cell frequency and TFR/TFH2 cell ratio. The random forest algorithm identified sIgE/tIgE ratio, TFR/TFH2 cell ratio, and BNSM frequency as the key biomarkers discriminating responders from nonresponders in the Tongji cohort. Logistic regression analysis confirmed the predictive value of a combination model, including sIgE/tIgE ratio, TFR/TFH2 cell ratio, and CD23+ BSM frequency (AUC = 0.899 in Tongji; validated AUC = 0.893 in Wisco).

CONCLUSIONS

A T- and B-cell signature combination efficiently identified SCIT responders before treatment, enabling personalized approaches for AR patients.

Mechanisms and Predictive Biomarkers of Allergen Immunotherapy in the Clinic

Allergen immunotherapy (AIT) remains to be the only disease-modifying treatment for IgE-mediated allergic diseases such as allergic rhinitis. It can provide long-term clinical benefits when given for 3 years or longer. Mechanisms of immune tolerance induction by AIT are underscored by the modulation of several compartments within the immune system. These include repair of disruption in epithelial barrier integrity, modulation of the innate immune compartment that includes regulatory dendritic cells and innate lymphoid cells, and adaptive immune compartments such as induction of regulatory T and B cells. Altogether, these are also associated with the dampening of allergen-specific TH2 and T follicular helper cell responses and subsequent generation of blocking antibodies. Although AIT is effective in modifying the immune response, there is a lack of validated and clinically relevant biomarkers that can be used to monitor desensitization, efficacy, and the likelihood of response, all of which can contribute to accelerating personalized medication and increasing patient care. Candidate biomarkers comprise humoral, cellular, metabolic, and in vivo biomarkers; however, these are primarily studied in small trials and require further validation. In this review, we evaluate the current candidates of biomarkers of AIT and how we can implement changes in future studies to help us identify clinically relevant biomarkers of safety, compliance, and efficacy.

Allergen exposure boosts peripheral Th9 responses in patients with local allergic rhinitis

KEY POINTS

Intranasal allergen exposure increases peripheral total Th2 and Th9 cells in patients with local allergic rhinitis (LAR). Peripheral T-cell response seems dominated by Th9 cells in patients with LAR, whereas Th2 responses prevail in patients with allergic rhinitis. Our results identify Th9 cells as potential therapeutic targets for patients with LAR.

Mechanisms of Allergen Immunotherapy and Potential Biomarkers for Clinical Evaluation

Allergen-immunotherapy (AIT) is an efficacious and disease-modifying treatment option for IgE-mediated diseases. Among these allergic rhinitis, insect venom allergy, food allergy, and allergic asthma are the most common candidates for AIT. AIT gives rise to clinical immunotolerance which may last for years after the treatment cessation. Mechanisms of AIT include suppression of allergic inflammation in target tissues and stimulation of the production of blocking antibodies, especially IgG4 and IgA. These mechanisms are followed by a reduction of underlying allergen-specific Th2 cell-driven responses to the allergens. Tolerance induction takes place through the desensitization of effector cells and stimulation of regulatory T cells that show their effects by mechanisms involving cell-cell cross-talk, but also other mechanisms, e.g., by the production of immunomodulatory cytokines such as, e.g., IL-10 and TGF-beta. From a personalized medical perspective, there is a need for clinical biomarkers of value in selecting responders and optimizing patient care during AIT. Also, a deeper understanding of underlying mechanistic processes will improve AIT's future outcomes. In this paper, the current knowledge of mechanisms in AIT is reviewed with a special focus on biomarkers of this therapy.

Allergen immunotherapy: progress and future outlook

INTRODUCTION

Allergy, the immunological hypersensitivity to innocuous environmental compounds, is a global health problem. The disease triggers, allergens, are mostly proteins contained in various natural sources such as plant pollen, animal dander, dust mites, foods, fungi and insect venoms. Allergies can manifest with a wide range of symptoms in various organs, and be anything from just tedious to life-threatening. A majority of all allergy patients are self-treated with symptom-relieving medicines, while allergen immunotherapy (AIT) is the only causative treatment option.

AREAS COVERED

This review will aim to give an overview of the state-of-the-art allergy management, including the use of new biologics and the application of biomarkers, and a special emphasis and discussion on current research trends in the field of AIT.

EXPERT OPINION

Conventional AIT has proven effective, but the years-long treatment compromises patient compliance. Moreover, AIT is typically not offered in food allergy. Hence, there is a need for new, effective and safe AIT methods. Novel routes of administration (e.g. oral and intralymphatic), hypoallergenic AIT products and more effective adjuvants holds great promise. Most recently, the development of allergen-specific monoclonal antibodies for passive immunotherapy may also allow treatment of patients currently not treated or treatable.

Real-world study: drug reduction in children with allergic rhinitis and asthma receiving immunotherapy

Background: The reduction of pharmacological treatment after allergen immunotherapy (AIT) for house dust mites (HDMs) has been little studied in children. Objective: To evaluate the reduction of pharmacological treatment comparing children that receive HDM immunotherapy (AIT group) versus only pharmacotherapy. Methods: A historic cohort of children with rhinitis or asthma was assessed. The main outcome was the frequency of complete drug discontinuation. Results: 100% drug reduction was higher for rhinitis (4-year cumulative incidence: 30 vs 10.7%) and asthma (24.1 vs 10.5%) in the AIT group (n = 987) than in the pharmacotherapy group (n = 2012). Conclusion: Immunotherapy is associated with a significant reduction of pharmacotherapy in children. This is a marker of clinical control and could be associated with positive economic impact.

Single-dose AAV vector gene immunotherapy to treat food allergy

Immunotherapies for patients with food allergy have shown some success in limiting allergic responses. However, these approaches require lengthy protocols with repeated allergen dosing and patients can relapse following discontinuation of treatment. The purpose of this study was to test if a single dose of an adeno-associated virus (AAV) vector can safely prevent and treat egg allergy in a mouse model. AAV vectors expressing ovalbumin (OVA) under an ubiquitous or liver-specific promoter were injected prior to or after epicutaneous sensitization with OVA. Mice treated with either AAV8-OVA vector were completely protected from allergy sensitization. These animals had a significant reduction in anaphylaxis mediated by a reduction in OVA-specific IgE titers. In mice with established OVA allergy, allergic responses were mitigated only in mice treated with an AAV8-OVA vector expressing OVA from an ubiquitous promoter. In conclusion, an AAV vector with a liver-specific promoter was more effective for allergy prevention, but higher OVA levels were necessary for reducing symptoms in preexisting allergy. Overall, our AAV gene immunotherapy resulted in an expansion of OVA-specific FoxP3⁺ CD4⁺ T cells, an increase in the regulatory cytokine IL-10, and a reduction in the IgE promoting cytokine IL-13.

Sequential class switch recombination to IgE and allergen-induced accumulation of IgE+ plasmablasts occur in the nasal mucosa of local allergic rhinitis patients

BACKGROUND

The involvement of allergen-specific (s)IgE in local allergic rhinitis (LAR) has been debated. Here, we investigate the effect of nasal allergen challenge with Dermatophagoides pteronyssinus (NAC-DP) in mucosal and peripheral B-cell subpopulations in LAR patients.

METHODS

Nine LAR, 5 allergic rhinitis (AR), and 5 non-atopic healthy control (HC) individuals were subjected to a 3-day NAC-DP protocol, and nasal biopsies and blood samples were collected before and after provocation. Nasal biopsies were used for immunohistochemistry and gene expression studies, whereas the frequency of lymphocyte subsets and basophil activation test (BAT) were analyzed in blood samples by flow cytometry. sIgG was measured in sera.

RESULTS

NAC-DP induced an increase in IgE⁺ CD38⁺ plasmablasts in the nasal mucosa of LAR patients, but not in AR or HC individuals. Markers of sequential recombination to IgE (εCSR) (from IgG) were observed in 33% of LAR, 20% of AR, and 0% of HC subjects. NAC-DP increased the proportion of peripheral CD19⁺ CD20⁺ CD38⁺ plasmablasts in AR and LAR patients, but not in HC. Expression of the mucosal homing receptor CXCR3 in peripheral CD19⁺ CD20⁺ CD38⁺ plasmablasts from LAR, AR, and HC individuals was 7%, 5%, and 0.5%, respectively. In vitro DP stimulation increased proliferating CD19⁺ CD20⁺ CD38⁺ plasmablasts in LAR and AR patients, but not in HC. Serum DP-sIgG was higher in LAR and AR patients as compared to HC. BAT was positive in 33%, 100%, and 0% of LAR, AR, and HC subjects, respectively.

CONCLUSION

These results suggest that allergen exposure induces the sequential εCSR of IgG⁺ CD19⁺ CD20⁺ CD38⁺ plasmablasts in the nasal mucosa of LAR patients.

Prediction of clinical efficacy of subcutaneous immunotherapy for Artemisia sieversiana pollen allergic rhinitis by serum metabolomics

BACKGROUND/PURPOSE

Specific immunotherapy is the only effective etiological treatment for allergic rhinitis, but subcutaneous immunotherapy has a slow onset and poor compliance. Predicting the clinical efficacy of subcutaneous immunotherapy in advance can reduce unnecessary medical costs and resource waste. This study aimed to identify metabolites that could predict the efficacy of subcutaneous immunotherapy on seasonal allergic rhinitis by serum metabolomics.

METHODS

Patients (n = 43) with Artemisia sieversiana pollen allergic rhinitis were enrolled and treated with subcutaneous immunotherapy for one year. Patients were divided into the ineffective group (n = 10) and effective group (n = 33) according to the therapeutic index. Serum samples were collected before treatment. Metabolomics was determined by liquid chromatography-mass spectrometry combined with gas chromatography-mass spectrometry and analyzed differential compounds and related metabolic pathways.

RESULTS

A total of 129 differential metabolites (P < 0.05) were identified and 4 metabolic pathways, namely taurine and hypotaurine metabolism, pentose and glucuronate interconversions, pentose phosphate pathway, and alanine, aspartate, and glutamate metabolism, were involved.

CONCLUSION

Some metabolites, such as hypotaurine, taurine, and l-alanine, have the potential to become predictive biomarkers for effective subcutaneous immunotherapy.

Allergen-Specific IgE and IgG4 as Biomarkers for Immunologic Changes during Subcutaneous Allergen Immunotherapy

(1) Background: Biomarkers of efficacy for subcutaneous immunotherapy (SCIT) on allergic rhinitis have not been evaluated in details. The present study aims to assess the relevance of measuring of sIgE, sIgG4 and IgE/IgG4 ratio during SCIT in patients with allergic rhinitis; (2) Methods: 20 patients, 13 men and 7 women aged 19 to 58 years, with clinically manifested seasonal and perennial allergic rhinitis were studied. At the initiation and in the end of the three-year course of SCIT serum allergen-specific IgE and IgG4 were measured with ImmunoCAP system. The sIgE/sIgG4 ratio was calculated as a biomarker for immunologic effectiveness; (3) Results: There was a significant increase of sIgG4 antibodies (p < 0.05), while at the end of SCIT for the sIgE levels no significant changes were seen (p > 0.05). Moreover, 90% of patients showed a decrease of the IgE/IgG4 ratio; (4) Conclusions: In most of treated patients with AR, SCIT with Bulgarian allergen products leads to clear immunological changes. After a 3-year of SCIT there is a significant increase in allergen specific IgG4 levels and both decrease of sIgE and IgE/IgG4 ratio. sIgE, sIgG4 and IgE/IgG4 ratio can be used as a substantial biomarker for predicting immunological effectiveness of SCIT.

Efficacy of mite allergen immunotherapy in allergic rhinitis and the immune synergistic effect on cross-allergens

Aim: To compare the efficacy of single- and double-species mite allergen immunotherapy. Materials and methods: An open, pseudo-randomized, controlled study was conducted (n = 125 allergic rhinitis patients). The primary end point involved the visual analogue scale. Secondary end points included a basophil activation test and serum specific IgE and IgG4 assays. Results: Visual analogue scale analysis indicated considerable reductions in both groups. Both treatments improved quality of life and induced sIgG4 antibody production. Basophil activation and serum IgE inhibition were not evident in either treatment. Neither treatment displayed an early stage immune synergistic effect on cross-allergens. Conclusions: Both treatments were effective against allergic rhinitis, and statistical differences were not observed. Future studies may require long-term, large-scale research.

Role of nanostructures in allergy: Diagnostics, treatments and safety

Nanotechnology is science, engineering and technology conducted at the nanoscale, which is about 1-100 nm. It has led to the development of nanomaterials, which behave very differently from materials with larger scales and can have a wide range of applications in biomedicine. The physical and chemical properties of materials of such small compounds depend mainly on the size, shape, composition and functionalization of the system. Nanoparticles, carbon nanotubes, liposomes, polymers, dendrimers and nanogels, among others, can be nanoengineeried for controlling all parameters, including their functionalization with ligands, which provide the desired interaction with the immunological system, that is dendritic cell receptors to activate and/or modulate the response, as well as specific IgE, or effector cell receptors. However, undesired issues related to toxicity and hypersensitivity responses can also happen and would need evaluation. There are wide panels of accessible structures, and controlling their physico-chemical properties would permit obtaining safer and more efficient compounds for clinical applications goals, either in diagnosis or treatment. The application of dendrimeric antigens, nanoallergens and nanoparticles in allergy diagnosis is very promising since it can improve sensitivity by increasing specific IgE binding, mimicking carrier proteins or enhancing signal detection. Additionally, in the case of immunotherapy, glycodendrimers, liposomes, polymers and nanoparticles have shown interest, behaving as platforms of allergenic structures, adjuvants or protectors of allergen from degradation or having a depot capacity. Taken together, the application of nanotechnology to allergy shows promising facts facing important goals related to the improvement of diagnosis as well as specific immunotherapy.

Immunological parameters as biomarkers of response to MicroCrystalline Tyrosine-adjuvanted mite immunotherapy

Background

Despite the effectiveness of allergen immunotherapy (AIT), some patients are unresponsive for reasons still unknown; yet validated response biomarkers remain unavailable.

Objective

To analyze immunological parameters as biomarkers to monitor and predict clinical response to a MicroCrystalline Tyrosine-adjuvanted house dust mite (HDM) AIT in patients with allergic rhinitis (AR).

Methods

Observational, prospective, multicenter study including adult patients (aged 18-65 years) with AR, with and without asthma, sensitized to the HDM Dermatophagoides pteronyssinus (DP) and prescribed Acarovac Plus® DP 100% in the routine practice. Serum concentrations of total IgE, specific IgE, specific IgG4, IL-4, IL-5, IL-10, IL-13, and IFN-γ were compared between baseline and 12 months after AIT. The relationship between patients' baseline immunological profiles and classification as low, high, and non-responders and between their sensitization profile to DP allergens and effectiveness were analyzed.

Results

Of 141 patients recruited, 118 (mean [SD] age of 33.6 [9.5] years) were evaluable. One year after treatment, Der p 1-specific IgE, DP-specific IgG4, and IL-10 increased by a mean (SD) of 3.4 (13.6) kU/L (p = 0.016), 0.43 (0.55) mg/L (p < 0.0001), and 1.35 (7.56) pg/mL (p = 0.033), respectively. Non-responders showed increased baseline levels of IL-13 compared to high responders (p = 0.037). Changes in effectiveness variables between baseline and after AIT were similar regardless of the sensitization profile.

Conclusion

Non-responsive patients to AIT showed increased baseline IL-13 concentrations, suggesting its value as prognostic biomarker. DP-specific AIT increased Der p 1-specific IgE, DP-specific IgG4, and IL-10 concentrations in patients with AR. All patients benefited from treatment regardless of their sensitization profile to major DP allergens.

Changes in Immunologic Indicators During Allergen-Specific Immunotherapy for Allergic Rhinitis and Determinants of Variability: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

To date, there are no generally recognized biomarkers for allergen immunotherapy (AIT) and even the changes in immunological indicators during AIT are inconsistent in different publications.

OBJECTIVE

This study was conducted to quantify the immunological changes that occur during AIT and identify the determinants of heterogeneity.

METHODS

Randomized controlled trials of AIT published in the past 10 years were searched in Medline, Embase and Cochrane CENTRAL. Data on immunological indicators were extracted, and the characteristics of the included studies were collected. Meta-analysis and meta-regression were conducted for each indicator. The study was registered on the PROSPERO website (CRD42020176127).

RESULTS

We reviewed 1898 studies. Forty-six studies met the inclusion criteria, and 31 studies were included in the quantitative analyses. Subset analyses by time demonstrated that serum allergen-specific IgE (sIgE) of AIT patients increased in the first 12 months, then decreased and became slightly lower than that of control patients. Allergen-specific IgG4 (sIgG4) was elevated in the AIT group during and after treatment. IgE-blocking factor (IgE-BF) was increased and IgE-facilitated allergen binding (IgE-FAB) was reduced in AIT patients. Both of them of the 2 factors were associated with clinical efficacy in the multivariate regression analysis. sIgE/sIgG4 decreased in AIT patients, while there was no change in total IgE.

CONCLUSION

The levels of serum sIgE and sIgG4 during AIT showed a time-dependent pattern. IgE-BF and IgE-FAB should be further investigated as biomarkers for predicting and monitoring AIT efficacy.

Allergen Immunotherapy: Biomarkers and Clinical Outcome Measures

Clinical trials for allergen immunotherapy products’ development and approval are conducted, aiming to monitor safety and efficacy of them. Symptom scores and the use of rescue medication are the primary clinical endpoints used in the conducted clinical trials, while Quality of Life scores and symptom-free days are measurements also used as secondary endpoints. Although the use of in vitro biomarkers might have been more practical and objective, there are yet no broadly used reliable ones accurately reflecting the clinical effects of allergen immunotherapy. On the contrary, in vivo biomarkers, such as the nasal allergy provocation test, are reliable and successfully used. The aim of this review is to describe how to adapt and use biomarkers and clinical outcomes in the everyday practice of Allergists who perform allergen immunotherapy.

Mechanisms of Allergen Immunotherapy in Allergic Rhinitis

PURPOSE OF REVIEW

Allergic rhinitis (AR) is a chronic inflammatory immunoglobulin (Ig) E-mediated disease of the nasal mucosa that can be triggered by the inhalation of seasonal or perennial allergens. Typical symptoms include sneezing, rhinorrhea, nasal itching, nasal congestion and symptoms of allergic conjunctivitis. AR affects a quarter of the population in the United States of America and Europe.

RECENT FINDINGS

AR has been shown to reduce work productivity in 36-59% of the patients with 20% reporting deteriorated job attendance. Moreover, 42% of children with AR report reduced at-school productivity and lower grades. Most importantly, AR impacts the patient's quality of life, due to sleep deprivation. However, a proportion of patients fails to respond to conventional medication and opts for the allergen immunotherapy (AIT), which currently is the only disease-modifying therapeutic option. AIT can be administered by either subcutaneous (SCIT) or sublingual (SLIT) route. Both routes of administration are safe, effective, and can lead to tolerance lasting years after treatment cessation. Both innate and adaptive immune responses that contribute to allergic inflammation are suppressed by AIT. Innate responses are ameliorated by reducing local mast cell, basophil, eosinophil, and circulating group 2 innate lymphoid cell frequencies which is accompanied by decreased basophil sensitivity. Induction of allergen-specific blocking antibodies, immunosuppressive cytokines, and regulatory T and B cell phenotypes are key pro-tolerogenic adaptive immune responses.

CONCLUSION

A comprehensive understanding of these mechanisms is necessary for optimal selection of AIT-responsive patients and monitoring treatment efficacy. Moreover, it could inspire novel and more efficient AIT approaches.

Der p 1-based immunotoxin as potential tool for the treatment of dust mite respiratory allergy

Immunotoxins appear as promising therapeutic molecules, alternative to allergen-specific-immunotherapy. In this work, we achieved the development of a protein chimera able to promote specific cell death on effector cells involved in the allergic reaction. Der p 1 allergen was chosen as cell-targeting domain and the powerful ribotoxin α-sarcin as the toxic moiety. The resultant construction, named proDerp1αS, was produced and purified from the yeast Pichia pastoris. Der p 1-protease activity and α-sarcin ribonucleolytic action were effectively conserved in proDerp1αS. Immunotoxin impact was assayed by using effector cells sensitized with house dust mite-allergic sera. Cell degranulation and death, triggered by proDerp1αS, was exclusively observed on Der p 1 sera sensitized-humRBL-2H3 cells, but not when treated with non-allergic sera. Most notably, equivalent IgE-binding and degranulation were observed with both proDerp1αS construct and native Der p 1 when using purified basophils from sensitized patients. However, proDerp1αS did not cause any cytotoxic effect on these cells, apparently due to its lack of internalization after their surface IgE-binding, showing the complex in vivo panorama governing allergic reactions. In conclusion, herein we present proDerp1αS as a proof of concept for a potential and alternative new designs of therapeutic tools for allergies. Development of new, and more specific, second-generation of immunotoxins following proDerp1αS, is further discussed.

Early Response of Specific IgE can Predict Satisfaction with Sublingual Immunotherapy

OBJECTIVE

To investigate predictive parameters at baseline and during the early response to sublingual immunotherapy (SLIT) for house dust mites in allergic rhinitis patients.

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients were treated with SLIT for at least 3 years and serological tests performed at baseline and at 1-year follow-up to investigate predictive parameters. Satisfaction with SLIT, 4 nasal symptoms, and quality of life were evaluated before and after 3 years of SLIT. Sixty-one patients were enrolled and divided into two groups depending on their satisfaction after 3 years of SLIT: 43 were satisfied (70.5%) and 18 were not (29.5%).

RESULTS

Immunological parameters at baseline did not differ significantly between the satisfactory and unsatisfactory groups. However, changes in both Dermatophagoides pteronyssinus (Dp)- and D. farinae (Df)-specific IgEs were significantly higher in the unsatisfactory group than in the satisfactory group during the early response to SLIT (P = .006 and P = .045, respectively).

CONCLUSION

The changes in both Dp- and Df-specific IgE levels during early response may be indicators for favorable long-term treatment outcomes with SLIT. These results suggest that clinicians could measure these immunological parameters 1 year after Dp and Df SLIT to indicate potential responders versus nonresponders.

LEVEL OF EVIDENCE

2b Laryngoscope, 131:467-472, 2021.

Regulatory T and B cells in peripheral blood of subcutaneous immunotherapy-treated Japanese cedar pollinosis patients

AIM

The aim of this study was to clarify whether there are more regulatory T (Treg) and regulatory B (Breg) cells, and higher levels of IL-10-related transcription factors in subcutaneous immunotherapy (SCIT)-treated pollinosis patients than in non-SCIT-treated patients.

METHODS

Japanese cedar pollinosis patients undergoing SCIT had received treatment for at least 2.8 years. Peripheral blood mononuclear cells were used for flow cytometer analyses and mRNA measurement.

RESULTS

The numbers of type 1 regulatory T (Tr1)-like cells and Breg cells, and expression of E4BP4 mRNA by peripheral blood mononuclear cells in SCIT-treated patients were higher than those in non-SCIT-treated patients.

CONCLUSION

Tr1-like cells, Breg cells and E4BP4 may be involved in the effectiveness of SCIT.

Immunological effects of sublingual immunotherapy with Japanese cedar pollen extract in patients with combined Japanese cedar and Japanese cypress pollinosis

Sublingual immunotherapy (SLIT) with Japanese cedar (JCe) pollinosis was expected to be effective for Japanese cypress (JCy) pollinosis. However, only a half of JCy pollinosis patients clinically improved. Therefore, we examined the immunological effect of SLIT for JCy pollinosis. Peripheral blood mononuclear cells (PBMCs) from patients with JCe and JCy pollinosis who did and did not receive SLIT were incubated with Cry j 1, Cha o 1 and Cha o 3 antigens. Basophil activation test (BAT) were performed. Production of IL-5 and IL-17 induced by antigens was inhibited in the SLIT group. Cry j 1-specific production of IL-10 was increased, and serum Cry j 1-specific IgE and -IgG4 were elevated. However, Cha o 1- or Cha o 3-specific production of IL-10 and specific IgG4 was not increased. Antigens-specific BAT did not decrease after SLIT. New SLIT with JCe and JCy is needed for patients with combined JCe and JCy pollinosis.

Immunoregulatory Effects of Subcutaneous Immunotherapy on Lymphocyte Subgroups and Cytokines in Children with Asthma

Objective

Asthma is a syndrome that incorporates many immune phenotypes. The immunologic effects of subcutaneous immunotherapy (SCIT) exerts on allergic asthma remain still largely unknown. Here, we investigated the effects of SCIT on cytokine production and peripheral blood levels of lymphocyte subtypes in children with mite-induced moderate and severe allergic asthma.

Methods

The study included 60 kids with mite-induced allergic asthma from 5 to 10 years old. All subjects had received antiasthmatic pharmacologic for 3 months at baseline. Half of the children were treated with SCIT combined with pharmacologic treatment named the SCIT group and the other half only with pharmacologic therapy named the no-SCIT group. Total asthma symptom score (TASS) and total medication score (TMS) were recorded. Flow cytometry was used to identify lymphocyte subtypes: type 2 innate lymphocytes (ILC2s), type 1 (Th1) and type 2 (Th2) helper T cells, T helper 17 (Th17) cells, and regulatory T (Treg) cells. ELISA, flow cytometry, and cytometric bead array were used to assess cytokines IL-13, IFN-γ, IL-4, IL-17, and TGF-β, at baseline and 3 and 6 months after study treatment in both groups of patients.

Results

Both groups can significantly improve clinical symptoms in children with asthma. SCIT can significantly reduce asthma medication after 6 months of treatment. SCIT induced a significantly higher and progressive reduction in ILC2 percentage and IL-13 levels after 3 and 6 months of treatment compared with baseline and compared with no-SCIT patients. Significant differences were detected in the Th1/Th2 cell ratio and IFN-γ/IL-4 cytokine ratio between groups after 6 months of treatment. Similarly, the Th17/Treg ratio and IL-17/TGF-β ratio in the SCIT group were much lower than those in the no-SCIT group after 3-6 months of treatment.

Conclusion

SCIT is a promising option to reduce the percentage of ILC2 and regulate Th1/Th2 and Th17/Treg immune balance in the peripheral blood of children with asthma.

[Analyses of Foxp3+ Treg cells and Tr1 cells in subcutaneous immunotherapy-treated allergic individuals in humans and mice]

Subcutaneous immunotherapy (SCIT) is a causative treatment for allergic diseases. More recently, it has become clear that regulatory T (Treg) cells are increased by SCIT. Treg cells are generally divided into two main groups: 1) CD25⁺ Foxp3⁺ CD4⁺ T cells (Foxp3⁺ Treg cells) and 2) IL-10-producing Foxp3^- CD4⁺ T cells (Tr1 cells). We demonstrated that the number of Tr1 cells in peripheral blood mononuclear cells in SCIT-treated pollinosis patients were significantly higher than that in non-SCIT-treated patients, but Foxp3⁺ Treg cells were not. Consistent with the results of human peripheral blood, Tr1 cells were increased in the lungs of asthmatic mice by SCIT, but Foxp3⁺ Treg cells were not. Moreover, in vitro-induced Tr1 cells were responded to the antigen to produce a large amount of IL-10 in in vitro and in vivo. Adoptive transfer of the induced Tr1 cells significantly suppressed the development of asthma. In any species of human and mouse, the increase in Tr1 cells rather than Foxp3⁺ Treg cells could be important for the effects of SCIT. The increased Tr1 cells by SCIT functionally suppressed allergic asthma probably via production of IL-10 in response to the specific antigen. Therefore, analyses of the induction mechanisms of Tr1 cells and search for compounds which induce Tr1 cells are thought to lead to development of more efficient SCIT.

Combined allergic rhinitis and asthma syndrome (CARAS)

Combined allergic rhinitis and asthma syndrome (CARAS) is a concept of "one airway - one disease" or "unified airway disease ". The upper and lower airway inflammation characterizes allergic rhinitis and asthma, respectively and both diseases have shown an intimate connection in their genesis, coexistence and similarities as triggered by the same etiological agents; the same inflammatory cell profile and share therapeutic treatment. This review highlights the concept of CARAS by its phenotype, endotype and biomarker classification. Indeed, rhinitis is divided into four major phenotypes: allergic rhinitis; infectious rhinitis; non-infective/non-allergic rhinitis and mixed rhinitis. On the other hand, asthma has no common consensus yet; however, the most accepted classification is based on the stage of life (early- or late- onset asthma) in which the clinical symptoms are presented. Experimental researches where animals develop a syndrome similar to CARAS have been contributed to better understand the pathogenesis of the syndrome. Therefore, the aim of this review is to clarify current terms related to CARAS as definition, phenotypes, endotypes/biomarkers, physiopathology and treatments.

Maintenance-Phase Subcutaneous Immunotherapy with House Dust Mites Induces Cyclic Immunologic Effects

BACKGROUND

Subcutaneous immunotherapy (SCIT) is an effective treatment of respiratory allergies including house dust mite (HDM) and Hymenoptera venom allergy. During the build-up phase, the allergen is administered weekly at increasing doses, while during the maintenance phase, it is administered at a fixed high dose every 4 weeks. Upon SCIT injection, the allergen is driven to the draining lymph nodes where it most likely induces an immune response. Immunologic changes are thus supposedly induced at each injection.

OBJECTIVES

It is now established that SCIT induces tolerance in the long term, but the precise underlying immunologic mechanisms remain unclear. Therefore, we wanted to analyze the immunologic changes induced in both innate and adaptive immune cells at each individual SCIT administration during the maintenance phase in HDM-allergic patients. More specifically, we wondered whether the changes in regulatory T cell (Treg) and IgE+ B cell percentages, which are observed at the end of a 3-year course of SCIT, already occurred during the maintenance phase and whether these possible changes were sustained.

METHODS

We enrolled 6 patients suffering from HDM allergic rhinitis and undergoing maintenance HDM SCIT for 18-24 months. The same SCIT extract was used for all patients. We collected blood samples at 5 time points: T1 (immediately before a given SCIT injection), T2 (9 days after T1), T3 (29 days after T1 and right before the successive administration), T4 (39 days after T1), and T5 (61 days after T1 and just before the next injection). Six non-allergic age-matched healthy individuals were used as controls. Using flow cytometry, we assessed the following cell subsets in peripheral blood mononuclear cells: CD4 and CD8 T cells, Tregs, B cells, IgE+ B cells, NK and NKT cells, and total and activated basophils.

RESULTS

HDM-allergic patients displayed increased percentages of CD4 and CD8 T cells and NK cells compared to healthy controls. In contrast, NKT cells, total B cells, and basophils were diminished. These differences were maintained throughout the time course and seemed to be independent of the periodical SCIT injections. On the contrary, Treg percentages were significantly reduced in all HDM-allergic patients at T1. However, they increased at T2 and T4 (9 days after each SCIT injection) but decreased again at T3 and T5, just before the next one, resulting in cyclic changes. IgE+ B cells were significantly increased at T1, even more increased after each administration (T2, T4), and went back to their initial levels at T3 and T5, also resulting in a cyclic pattern.

CONCLUSIONS

Our data suggest that during the SCIT maintenance phase, cycles of expansion/contraction of Tregs and IgE+ B cells occur at each SCIT injection. Therefore, the sustained induction of immune tolerance by SCIT, through the increase of Tregs, seems to depend on the periodical exposure to the allergen, at least during the early steady state.

Allergen immunotherapy improves defective follicular regulatory T cells in patients with allergic rhinitis

BACKGROUND

The function of follicular regulatory T (T_FR) cells, especially in regulating IgE production in patients with allergic diseases, is poorly understood.

OBJECTIVE

We sought to investigate the phenotype, function, and clinical relevance of T_FR cells in patients with allergic rhinitis (AR).

METHODS

The phenotype and frequency of tonsillar and circulating T_FR cells were characterized by using flow cytometry. T_FR cell function was examined in an assay by coculturing with follicular helper T cells and B cells. The associations between T_FR cells and the clinical features in patients with AR before and after allergen immunotherapy (AIT) were analyzed.

RESULTS

T_FR cells were detected in germinal centers of tonsils, but compared with subjects without AR, the frequencies decreased in patients with AR who were allergic to house dust mites. Circulating T_FR cells in blood were phenotypically and numerically correlated with tonsillar T_FR cells, and a reduction of circulating T_FR cells but not total or CXCR5^- regulatory T cells was noted in patients with AR compared with healthy control subjects. Moreover, circulating T_FR cells in patients with AR showed a specific defect in suppressing IgE production but were capable of suppressing production of other immunoglobulin types. We identified negative associations of circulating T_FR cell frequencies and function with antigen-specific IgE levels or disease severity in patients with AR. After AIT, the frequencies and function of circulating T_FR cells were improved, which positively associated with disease remission.

CONCLUSION

Impairment in T_FR cells might contribute to aberrant IgE production in patients with AR, and AIT improves defective T_FR cell function. T_FR cells might serve as a potential biomarker to monitor clinical response to AIT.

The Use of Biomarkers to Predict Aero-Allergen and Food Immunotherapy Responses

The incidence of allergic conditions has continued to rise over the past several decades, with a growing body of research dedicated toward the treatment of such conditions. By driving a complex range of changes in the underlying immune response, immunotherapy is the only therapy that modulates the immune system with long-term effects and is presently utilized for the treatment of several atopic conditions. Recent efforts have focused on identifying biomarkers associated with these changes that may be of use in predicting patients with the highest likelihood of positive clinical outcomes during allergen immunotherapy (AIT), providing guidance regarding AIT discontinuation, and predicting symptomatic relapse and the need for booster AIT after therapy. The identification of such biomarkers in food allergy has the additional benefit of replacing oral food challenges, which are presently the gold standard for diagnosing food allergies. While several markers have shown early promise, research has yet to identify a marker that can invariably predict clinical response to AIT. Skin prick testing (SPT) and specific IgE have commonly been used as inclusion criteria for the initiation of AIT and prediction of reactions during subsequent allergen challenge; however, existing data suggests that changes in these markers are not always associated with clinical improvement and can be widely variable, reducing their utility in predicting clinical response. Similar findings have been described for the use of allergen-specific functional IgG4 antibodies, basophil activation and histamine release, and type 2 innate lymphoid cells. There appears to be a promising association between changes in the expression of dendritic cell-associated markers, as well as the use of DNA promoter region methylation patterns in the prediction of allergy status following therapy. The cellular and molecular changes brought about by immunotherapy are still under investigation, but major strides in our understanding are being made.

Nasal allergen-neutralizing IgG4 antibodies block IgE-mediated responses: Novel biomarker of subcutaneous grass pollen immunotherapy

BACKGROUND

Grass pollen subcutaneous immunotherapy (SCIT) is associated with induction of serum IgG₄-associated inhibitory antibodies that prevent IgE-facilitated allergen binding to B cells.

OBJECTIVE

We sought to determine whether SCIT induces nasal allergen-specific IgG₄ antibodies with inhibitory activity that correlates closely with clinical response.

METHODS

In a cross-sectional controlled study, nasal fluid and sera were collected during the grass pollen season from 10 SCIT-treated patients, 13 untreated allergic patients (with seasonal allergic rhinitis [SAR]), and 12 nonatopic control subjects. Nasal and serum IgE and IgG₄ levels to Phleum pratense components were measured by using the Immuno Solid Allergen Chip microarray. Inhibitory activity was measured by IgE-facilitated allergen binding assay. IL-10⁺ regulatory B cells were quantified in peripheral blood by using flow cytometry.

RESULTS

Nasal and serum Phl p 1- and Phl p 5-specific IgE levels were increased in patients with SAR compared to nonatopic control subjects (all, P < .001) and SCIT-treated patients (nasal, P < .001; serum Phl p 5, P = .073). Nasal IgG₄ levels were increased in the SCIT group compared to those in the SAR group (P < .001) during the pollen season compared to out of season. IgG-associated inhibitory activity in nasal fluid and serum was significantly increased in the SCIT group compared to that in the SAR (both, P < .01). The magnitude of the inhibitory activity was 93% (P < .001) in nasal fluid compared to 66% (P < .001) in serum and was reversed after depletion of IgG. Both nasal fluid (r = -0.69, P = .0005) and serum (r = -0.552, P = .0095) blocking activity correlated with global symptom improvement. IL-10⁺ regulatory B cells were increased in season compared to out of season in the SCIT group (P < .01).

CONCLUSION

For the first time, we show that nasal IgG₄-associated inhibitory activity correlates closely with the clinical response to allergen immunotherapy in patients with allergic rhinitis with or without asthma.

The impact of allergen exposure and specific immunotherapy on circulating blood cells in allergic rhinitis

Allergic rhinitis (AR) is an IgE-mediated inflammatory disease of the nasal mucosa with well described local immune responses during allergen exposure. The frequent association of AR with general extra-nasal symptoms and other allergic conditions, such as conjunctivitis and asthma, however, support a more systemic disease impact. In addition to acute elevation of soluble inflammatory mediators in periphery blood, a growing number of studies have reported changes in circulating blood cells after specific nasal allergen challenge or environmental allergen exposure. These findings imply an involvement of specific blood leukocyte subsets, thrombocytes and recently, erythrocytes. This review summarizes the circulating blood cell dynamics associated with allergen exposure in AR subjects reported so far. Additionally, the impact of therapy, particularly allergen-specific immunotherapy (AIT), the only currently available causal treatment reducing AR-related symptoms, is further considered in this context.

Mechanisms of allergen-specific immunotherapy: Diverse mechanisms of immune tolerance to allergens

OBJECTIVE

The aim of this review is to provide an overview of the current knowledge on the mechanisms of allergen immunotherapy based on the recent publications and clinical trials.

DATA SOURCES

PubMed literature review.

STUDY SELECTIONS

In this review, we focus on diverse mechanisms of AIT and provide an insight into alternative routes of administration. Additionally, we review and discuss the most recent studies investigating potential biomarkers and highlight their role in clinical settings.

RESULTS

Successful allergen-specific immunotherapy (AIT) induces the reinstatement of tolerance toward allergens and represents a disease-modifying treatment. In the last decades, substantial progress in understanding the mechanisms of AIT has been achieved. Establishment of long-term clinical tolerance to allergens engages a complex network of interactions, modulating the functions of basophils, mast cells, allergen-specific regulatory T and B cells, and production of specific antibodies. The reduction of symptoms and clinical improvement is achieved by skewing the immune response away from allergic inflammation.

CONCLUSION

Although the complex nature of AIT mechanisms is becoming more clear, the need to discover reliable biomarkers to define patients likely to respond to the treatment is emerging.

FcεRI expression and IgE binding by dendritic cells and basophils in allergic rhinitis and upon allergen immunotherapy

BACKGROUND

In humans, both basophils and dendritic cells (DCs) express the high-affinity IgE receptor (FcεRI).

OBJECTIVE

To gain more insight into the relation between serum IgE levels and FcεRI expression and IgE binding by DCs and basophils in house dust mite (HDM) allergy and during subcutaneous immunotherapy (SCIT).

METHODS

We measured FcεRI, IgE and HDM allergen on DCs (conventional type 2 DCs, cDC2s; plasmacytoid dendritic cells, pDCs) and basophils by flow cytometry in 22 non-allergic vs 52 allergic subjects and upon HDM SCIT in 28 allergic subjects. IgE levels were measured in serum.

RESULTS

Serum IgE correlated differentially with FcεRI expression and IgE binding depending on cell type and allergic status. In non-allergic subjects, FcεRI/IgE surface densities increased with serum IgE to a significantly stronger degree on basophils compared to cDC2s. By contrast, in allergic subjects FcεRI/IgE surface densities increased with serum IgE to a slightly stronger degree on cDC2s compared to basophils. In addition, the data set suggests sequential loading of IgE onto FcεRI expressed by these cells (basophils>cDC2s>pDCs). Finally, HDM SCIT induced a temporary increase in serum IgE, which was paralleled by a peak in FcεRI and IgE on DCs, but not on basophils.

CONCLUSIONS & CLINICAL RELEVANCE

This study provides a comprehensive insight into the relation between serum IgE and FcεRI/IgE on basophils and DC subsets. The novel finding that HDM SCIT induces a temporary increase in FcεRI expression on DCs, but not on basophils, can be an incentive for future research on the potential tolerogenic role of IgE/FcεRI signalling in DCs in the setting of allergen immunotherapy.

Blocking antibodies induced by allergen-specific immunotherapy ameliorate allergic airway disease in a human/mouse chimeric model

BACKGROUND

Allergen-specific immunotherapy (AIT) induces specific blocking antibodies (Ab), which are claimed to prevent IgE-mediated reactions to allergens. Additionally, AIT modulates cellular responses to allergens, for example, by desensitizing effector cells, inducing regulatory T and B lymphocytes and immune deviation. It is still enigmatic which of these mechanisms mediate(s) clinical tolerance. We sought to address the role of AIT-induced blocking Ab separately from cellular responses in a chimeric human/mouse model of respiratory allergy.

METHODS

Nonobese diabetic severe combined immunodeficient γc^-/- (NSG) mice received intraperitoneally allergen-reactive PBMC from birch pollen-allergic patients together with birch pollen extract and human IL-4. Engraftment was assessed by flow cytometry. Airway hyperresponsiveness (AHR) and bronchial inflammation were analyzed after intranasal challenges with allergen or PBS. Sera collected from patients before and during AIT with birch pollen were added to the allergen prior to intranasal challenge. The IgE-blocking activity of post-AIT sera was assessed in vitro.

RESULTS

Human cells were detected in cell suspensions of murine lungs and spleens indicating successful humanization. Humanized mice displayed a more pronounced AHR and bronchial inflammation when challenged with allergen compared to negative controls. Post-AIT sera exerted IgE-blocking activity. In contrast to pre-AIT sera, the presence of heterologous and autologous post-AIT sera significantly reduced the allergic airway inflammation and matched their IgE-blocking activity determined in vitro.

CONCLUSION

Our data demonstrate that post-AIT sera with IgE-blocking activity ameliorate allergic airway inflammation in a human/mouse chimeric model of respiratory allergy independently of AIT-induced cellular changes.

Immunological Changes Induced in Peach Allergy Patients with Systemic Reactions by Pru p 3 Sublingual Immunotherapy

SCOPE

Sublingual immunotherapy using peach extract enriched in Pru p 3 (Pru p 3-enriched-SLIT) brings a new perspective to treating patients with allergy to lipid transfer proteins. We evaluate the immunological changes induced by Pru p 3-enriched-SLIT during one year.

METHODS AND RESULTS

Three groups are included: peach allergic patients who receive Pru p 3-enriched-SLIT, peach allergic untreated patients, and controls. Peripheral blood mononuclear cells are obtained before treatment and at different time-points. Monocyte-derived dendritic cells (moDCs) maturation and lymphocyte proliferation are assessed by flow cytometry. Data showed a significant reduction of moDCs maturation status during one year of treatment and an increase in PD-L1. Moreover, we observed a significant decrease of the Pru p 3-specific proliferation of effector cells and an increase in regulatory T (Treg) cells with higher PD-L1 expression and IL-10 production. These are observed in patients treated only.

CONCLUSION

Successful Pru p 3-enriched-SLIT is linked to an important immunosuppression of allergen-specific effector T cells, potentially due to an increase of allergen-specific Treg cells. These cellular changes are orchestrated by the activity of moDCs promoting the expression of PD-L1 that will participate in the regulatory response. These changes may serve as biomarkers during SLIT alongside other features such as IgE/IgG₄ ratio.

The clinical and immunological effects of Pru p 3 sublingual immunotherapy on peach and peanut allergy in patients with systemic reactions

BACKGROUND

The peach non-specific lipid transfer protein, Pru p 3, is the primary sensitizer in fruits and responsible for severe reactions in the Mediterranean area. Peach allergy is frequently associated with other allergies such as peanut. Therefore, it is important to assess how specific immunotherapy to Pru p 3 could affect both peach and peanut tolerance.

OBJECTIVES

To evaluate peach and peanut desensitization and immunological changes after 1 year of Pru p 3 sublingual immunotherapy (SLIT) in patients with systemic allergic reactions to peach and/or peanut.

METHODS

Forty-eight peach allergic patients, 36 treated with SLIT and 12 non-treated, were monitored for 12 months. Treated patients were subclassified as peanut allergic (Group A), sensitized (Group B) or tolerant (Group C). SLIT effect was evaluated by skin prick test (SPT) reactivity and food challenge. Immunological changes were evaluated by monitoring sIgE and sIgG4 levels and basophil reactivity.

RESULTS

After 1 year of SLIT, the weal area in SPT significantly decreased and a significant increase in peach threshold in treated patients was observed (P < 0.001). Patients in Group A showed a significant decrease in peanut SPT weal area and an increase in peanut threshold (P < 0.001). Immunological changes were observed in treated patients only, with a significant decrease in sIgE and a parallel increase in sIgG4, sIgG4/sIgE and basophil reactivity for both Pru p 3 and Ara h 9.

CONCLUSIONS AND CLINICAL RELEVANCE

After 1 year, Pru p 3 SLIT induces both desensitization and immunological changes not only for peach but also for other food allergens relevant in the induction of severe reactions such as peanut.

The role of regulatory T cells and genes involved in their differentiation in pathogenesis of selected inflammatory and neoplastic skin diseases. Part II: The Treg role in skin diseases pathogenesis

Regulatory FOXP3+ T cells (Tregs) constitute 5% to 10% of T cells in the normal human skin. They play an important role in the induction and maintenance of immunological tolerance. The suppressive effects of these cells are exerted by various mechanisms including the direct cytotoxic effect, anti-inflammatory cytokines, metabolic disruption, and modulation of the dendritic cells function. The deficiency of Treg cells number or function are one of the basic elements of the pathogenesis of many skin diseases, such as psoriasis, atopic dermatitis, bacterial and viral infections. They also play a role in the pathogenesis of T cell lymphomas of the skin (cutaneous T cell lymphomas - CTCL), skin tumors and mastocytosis. Here, in the second part of the cycle, we describe dysfunctions of Tregs in selected skin diseases.

Dermatophagoides pteronyssinus immunotherapy changes the T-regulatory cell activity

Subcutaneous specific immunotherapy (SCIT) has been shown to modify the Dermatophagoides pteronissinus (DP) allergic response, characterized by generation of Treg cells. However, studies have reported no changes in the proportion of Treg cells after immunotherapy, indicating that the effects may be due to modifications in their regulatory activities. We aimed to determine whether Tregs generated by DP-SCIT can switch the allergic response to tolerant and study the involvement of suppressive cytokines on it. Twenty-four DP-allergic rhinitis patients were recruited, 16 treated with DP-SCIT and 8 untreated. Treg and T effector cells were isolated before and after DP-SCIT, and cocultured in different combinations with α-IL-10, α-TGF-β blocking antibodies and nDer p 1. Treg cells after DP-SCIT increased Th1 and decreased Th2 and Th9 proliferation. Similarly, they increased IL-10 and decreased IL-4 and IL-9-producing cells. α-IL-10 affected the activity of Treg cells obtained after DP-SCIT only. Finally, DP-specific IgG4 levels, Treg percentage and IL-10 production were correlated after DP-SCIT. These results demonstrate that DP-SCIT induces Treg cells with different suppressive activities. These changes could be mediated by IL-10 production and appear to play an important role in the induction of the tolerance response leading to a clinical improvement of symptoms.

Biomarkers for monitoring clinical efficacy of allergen immunotherapy for allergic rhinoconjunctivitis and allergic asthma: an EAACI Position Paper

BACKGROUND

Allergen immunotherapy (AIT) is an effective treatment for allergic rhinoconjunctivitis (AR) with or without asthma. It is important to note that due to the complex interaction between patient, allergy triggers, symptomatology and vaccines used for AIT, some patients do not respond optimally to the treatment. Furthermore, there are no validated or generally accepted candidate biomarkers that are predictive of the clinical response to AIT. Clinical management of patients receiving AIT and efficacy in randomised controlled trials for drug development could be enhanced by predictive biomarkers.

METHOD

The EAACI taskforce reviewed all candidate biomarkers used in clinical trials of AR patients with/without asthma in a literature review. Biomarkers were grouped into seven domains: (i) IgE (total IgE, specific IgE and sIgE/Total IgE ratio), (ii) IgG-subclasses (sIgG1, sIgG4 including SIgE/IgG4 ratio), (iii) Serum inhibitory activity for IgE (IgE-FAB and IgE-BF), (iv) Basophil activation, (v) Cytokines and Chemokines, (vi) Cellular markers (T regulatory cells, B regulatory cells and dendritic cells) and (vii) In vivo biomarkers (including provocation tests?).

RESULTS

All biomarkers were reviewed in the light of their potential advantages as well as their respective drawbacks. Unmet needs and specific recommendations on all seven domains were addressed.

CONCLUSIONS

It is recommended to explore the use of allergen-specific IgG4 as a biomarker for compliance. sIgE/tIgE and IgE-FAB are considered as potential surrogate candidate biomarkers. Cytokine/chemokines and cellular reponses provided insight into the mechanisms of AIT. More studies for confirmation and interpretation of the possible association with the clinical response to AIT are needed.

Advances in allergen immunotherapy in 2015

The year 2015 saw a significant number of advances in allergen immunotherapy (AIT), and several of these are reviewed in this report. Although AIT has been used for more than 100 years, investigations into optimal treatment approaches and mechanisms are ongoing. Among the highlights was a report by an international group of experts who reviewed AIT guidelines from the major specialty societies and addressed potential unmet needs. Herein, advances in the effectiveness, safety, and mechanisms of sublingual and oral immunotherapy are reviewed. Development of hypoallergenic vaccines to enhance safety, newer routes and regimens to improve efficacy, and biomarkers to monitor immunotherapy are also discussed.

[Immunological mechanisms of allergen-specific immunotherapy]

Allergen-specific immunotherapy is accompanied by multiple changes on the cellular and humoral level. A shift of Th2 immune responses towards immune responses of the Th1 type, which goes along with an increase of regulatory T cells and B cells, IL-10 as well as reduction of effector cells and eosinophils in the tissue, combined with lower IgE production in favor of higher IgG4 production, are regarded as key mechanisms of allergen-specific immunotherapy . A better understanding of immunologic pathways of specific immunotherapy would be essential for the improvement of this therapy as well as for the development of reliable biomarkers capable to monitor therapeutic responses as well as compliance of the patients.

Update on Biomarkers to Monitor Clinical Efficacy Response During and Post Treatment in Allergen Immunotherapy

Allergen immunotherapy (AIT) is an immune modulating treatment for allergic diseases. Although highly effective, some patients do not respond to the treatment. To date there are no surrogate biomarkers that are predictive of the clinical response to AIT. More and more is known about the underlying immunological mechanism involved in AIT. Through modulation of both innate and adaptive immune responses, involving reduced ILC2 and enhanced Treg and Breg induction and functionality, along with induction of IgG4 antibody production which have the capacity to inhibit both allergen-induced basophil responsiveness and CD23-mediated IgE-facilitated allergen presentation, the result is an immune skewing towards a more balanced Type I response. So far, however there is not a clear correlation with the observed immunological changes and predictive correlates of clinical efficacy. The most promising biomarker of successful AIT is IgE-FAB as a reflection of functional IgG4. Cellular responses and cytokine analysis gives a great deal of insight into the mechanisms of AIT but may not represent useful or indeed reliable biomarkers in a clinical setting. There is a need for more research for confirmation and interpretation of the possible association with biomarkers and clinical response to AIT.

Applications and mechanisms of immunotherapy in allergic rhinitis and asthma

Clinical and immunologic tolerance are hallmarks of successful allergen immunotherapy (AIT). Clinical benefits such as reduced symptoms, pharmacotherapy intake and improvement of quality of life persist following cessation of treatment. Successful AIT is associated with suppression of allergic inflammatory cells such as mast cells, eosinophils and basophils in target organs. Furthermore, AIT down-regulates type 2 innate lymphoid cells and allergen-specific type 2 T-helper (Th2) cells. The immunologic tolerant state following AIT is associated with the induction of distinct phenotypes of regulatory T-cells (T-regs) including interleukin (IL)-10-, IL-35- and transforming growth factor (TGF)-β- producing T-regs and FoxP3⁺ T-regs. B-cell responses, including the induction of IL-10⁺ regulatory B-cells (B-regs) and the production of IgG4-associated blocking antibodies are also induced following successful AIT. These events are associated with the suppression of antigen-specific Th2 responses and delayed immune deviation in favour of Th1 type responses. Insight into the mechanisms of AIT has allowed identification of novel biomarkers with potential to predict the clinical response to AIT and also novel therapeutic strategies for more effective and safer AIT.