Mechanisms of sublingual immunotherapy

A Meta-Analysis Investigating the Efficacy and Safety of Allergen-Specific Immunotherapy in the Management of Respiratory Allergies

Background: This meta-analysis aimed to evaluate the effectiveness and adverse effects of specific immunotherapy (SIT) in the management of respiratory allergens, including allergic asthma, rhinitis, and related disorders, based on a review of current literature up to November 8, 2022.Methods: We conducted a search of databases, including PubMed, Embase, Cochrane, and Web of Science, to identify relevant randomized controlled trials (RCTs) assessing respiratory allergy-specific immunotherapy. We employed the Consolidated Standards of Reporting Trials (CONSORT) Statement to select RCTs that adhered to rigorous reporting standards. Specifically, we focused on double-blind placebo-controlled (DBPC) trials and open studies involving both adults and children, considering factors such as dosage, inclusion criteria, allergens, and primary outcome measurements.Results: A total of 25 meta-analyses were included in this study. Among them, 14 evaluated sublingual specific allergen immunotherapy (SLIT), 4 assessed subcutaneous allergen immunotherapy (SCIT), 4 explored both sublingual and subcutaneous immunotherapy, and 3 investigated intralymphatic immunotherapy. The outcomes of these meta-analyses indicated a reduction in medication scores in 20 cases and a decrease in symptom scores in 23 cases. Additionally, six studies reported on changes in IgE levels, seven studies focused on IgG4, four studies examined FEV1 (forced expiratory volume in one second), and eight studies reported on symptom and medication scores. Furthermore, eleven studies reported on differences in adverse reactions.Conclusion: The results of our meta-analysis suggest that specific immunotherapy, while associated with some adverse effects, effectively reduces the symptoms of asthma and rhinitis. Therefore, we recommend its use in the treatment of respiratory allergies.

Desensitization and remission after peanut sublingual immunotherapy in 1- to 4-year-old peanut-allergic children: A randomized, placebo-controlled trial

BACKGROUND

Prior studies of peanut sublingual immunotherapy (SLIT) have suggested a potential advantage with younger age at treatment initiation.

OBJECTIVE

We studied the safety and efficacy of SLIT for peanut allergy in 1- to 4-year-old children.

METHODS

Peanut-allergic 1- to 4-year-old children were randomized to receive 4 mg peanut SLIT versus placebo. Desensitization was assessed by double-blind, placebo-controlled food challenge (DBPCFC) after 36 months of treatment. Participants desensitized to at least 443 mg peanut protein discontinued therapy for 3 months and then underwent DBPCFC to assess for remission. Biomarkers were measured at baseline and longitudinally during treatment.

RESULTS

Fifty participants (25 peanut SLIT, 25 placebo) with a median age of 2.4 years were enrolled across 2 sites. The primary end point of desensitization was met with actively treated versus placebo participants having a significantly greater median cumulative tolerated dose (4443 mg vs 143 mg), higher likelihood of passing the month 36 DBPCFC (60% vs 0), and higher likelihood of demonstrating remission (48% vs 0). The highest rate of desensitization and remission was seen in 1- to 2-year-olds, followed by 2- to 3-year-olds and 3- to 4-year-olds. Longitudinal changes in peanut skin prick testing, peanut-specific IgG4, and peanut-specific IgG4/IgE ratio were seen in peanut SLIT but not placebo participants. Oropharyngeal itching was more commonly reported by peanut SLIT than placebo participants. Skin, gastrointestinal, upper respiratory, lower respiratory, and multisystem adverse events were similar between treatment groups.

CONCLUSION

Peanut SLIT safely induces desensitization and remission in 1- to 4-year-old children, with improved outcomes seen with younger age at initiation.

Characterization of Metal-Specific T-Cells in Inflamed Oral Mucosa in a Novel Murine Model of Chromium-Induced Allergic Contact Dermatitis

The element chromium (Cr) is a component of several types of alloys found in the environment, or utilized in dentistry, that may cause intraoral metal contact allergy. However, the pathological mechanism of intraoral Cr allergy remains unclear because there is no established animal model of Cr allergy in the oral mucosa. In this study, we established a novel murine model of Cr-induced intraoral metal contact allergy and elucidated the immune response in terms of cytokine profiles and T-cell receptor repertoire. Two sensitizations with Cr plus lipopolysaccharide solution into the postauricular skin were followed by a single Cr challenge of the oral mucosa to generate the intraoral metal contact allergy model. Histological examination revealed that CD3+ T-cells had infiltrated the allergic oral mucosa one day after exposure to the allergen. The increase in T-cell markers and cytokines in allergic oral mucosa was also confirmed via quantitative PCR analysis. We detected Cr-specific T-cells bearing TRAV12D-1-TRAJ22 and natural killer (NK) T-cells in the oral mucosa and lymph nodes. Our model demonstrated that Cr-specific T-cells and potent NKT-cell activation may be involved in the immune responses of Cr-induced intraoral metal contact allergy.

Rupatadine to prevent local allergic reactions to sublingual allergy immunotherapy: a case series

BACKGROUND

Sublingual immunotherapy tablets (SLIT-T) are an effective treatment for allergic rhinitis (AR), but some patients experience local allergic reactions (LAR) in the first few weeks of treatment that can lead to treatment discontinuation. Although oral antihistamines are recommended for the treatment and pretreatment of LAR associated with SLIT-T, there are no clinical trial data to support this recommendation. Rupatadine is an H1 antihistamine that also inhibits platelet activating factor activity. The objective of this case series is to describe real-world clinical situations in which rupatadine was used to treat or mitigate SLIT-T-related LAR.

CASE PRESENTATIONS

Five cases are presented by the managing allergist and off-label use of rupatadine is their expert opinion only. Patients in all 5 cases were treated with a SLIT-T (e.g. ragweed, tree, grass, or house dust mites) for the management of allergic rhinitis and experienced bothersome LAR with the first SLIT-T administration. In 3 cases, rupatadine 10 mg was administered for the immediate treatment of LAR (either in-office with the first SLIT-T dose or for subsequent LAR experienced at home) and the symptoms resolved. In 3 cases, pretreatment with other second-generation H1 antihistamines was unable to prevent LAR and the patients discontinued the SLIT-T. In these 3 cases, switching to pretreatment with rupatadine allowed the patients to restart and tolerate SLIT-T treatment with minimal or no LAR. In these patients with an established history of LAR, proactive pretreatment with rupatadine in subsequent seasons or with initiation of a different SLIT-T mitigated the previously experienced LARs.

CONCLUSIONS

In the cases presented, treatment with rupatadine resolved LAR associated with SLIT-T treatment and rupatadine pretreatment appeared to mitigate subsequent LAR. Rupatadine may be an option to treat or improve the tolerability of the SLIT-T, potentially improving early treatment persistence.

Insights Into Mucosal Innate Immune Responses in House Dust Mite-Mediated Allergic Asthma

The prevalence of asthma has been rising steadily for several decades, and continues to be a major public health and global economic burden due to both direct and indirect costs. Asthma is defined as chronic heterogeneous inflammatory diseases characterized by airway obstruction, mucus production and bronchospasm. Different endotypes of asthma are being recognized based on the distinct pathophysiology, genetic predisposition, age, prognosis, and response to remedies. Mucosal innate response to environmental triggers such as pollen, cigarette smoke, fragrances, viral infection, and house dust mite (HDM) are now recognized to play an important role in allergic asthma. HDM are the most pervasive allergens that co-habitat with us, as they are ubiquitous in-house dusts, mattress and bedsheets, and feed on a diet of exfoliated human skin flakes. Dermatophagoides pteronyssinus, is one among several HDM identified up to date. During the last decade, extensive studies have been fundamental in elucidating the interactions between HDM allergens, the host immune systems and airways. Moreover, the paradigm in the field of HDM-mediated allergy has been shifted away from being solely a Th2-geared to a complex response orchestrated via extensive crosstalk between the epithelium, professional antigen presenting cells (APCs) and components of the adaptive immunity. In fact, HDM have several lessons to teach us about their allergenicity, the complex interactions that stimulate innate immunity in initiating and perpetuating the lung inflammation. Herein, we review main allergens of Dermatophagoides pteronyssinus and their interactions with immunological sentinels that promote allergic sensitization and activation of innate immunity, which is critical for the development of the Th2 biased adaptive immunity to HDM allergens and development of allergic asthma.

Sublingual immunotherapy for food allergy and its future directions

Food allergy is an important medical problem with increasing prevalence throughout the world. Different approaches of food immunotherapy are being investigated including oral, epicutaneous and sublingual routes. Sublingual immunotherapy (SLIT) for food allergy involves placement of glycerinated allergen under the tongue daily to achieve allergen-specific desensitization. SLIT has been studied in the treatment of hazelnut, peach, apple, milk and peanut allergies with substantial focus on the treatment of peanut allergy. Phase II studies have shown SLIT for treatment of peanut allergy increases the tolerated dose of peanut by a substantial margin with fewer and less severe side effects than other modalities. This review discusses the mechanisms of SLIT, early studies of its use in food allergy and larger randomized controlled trials for treatment of peanut allergy. Future directions using the mechanisms involved in SLIT include oral mucosal immunotherapy for peanut allergy.

Sublingual dendritic cells targeting by aptamer: Possible approach for improvement of sublingual immunotherapy efficacy

The efficacy improvement of current sublingual immunotherapy (SLIT) for preventing and treating respiratory airway allergic diseases is the main purpose of many investigations. In this study, we aimed to assess whether ovalbumin (Ova) encapsulated poly (lactic-co-glycolic) acid nanoparticles (PLGA NPs) decorated with dendritic cells (DCs)-specific aptamer could be applied for this purpose.The nanoparticles containing Ova were synthesized by emulsion/solvent evaporation method and attached to DCs-specific aptamer. Ova-sensitized BALB/c mice have been treated in five ways: subcutaneously with free Ova (SCIT), sublingually either with free Ova, Ova-PLGA NPs (two doses), Apt-Ova-PLGA NPs (two doses) and placebo/control Apt-Ova-PLGA NPs. For assessment of immunologic responses, IL-4, IFN-γ, IL-17, IL10, and TGF-β and IgE antibody levels were measured by ELISA and T cell proliferation were evaluated by MTT. In addition, lung and nasal histological examinations, NALF cells counting were carried out. Results declared that the lowest IgE and IL- 4 levels were observed in Apt-Ova-PLGA NPs (both doses). In the other hands, Apt-Ova-PLGA NPs (high dose) showed the highest increase of IFN- γ and TGF- β, decrease of IL-17 levels, total cell count and T-cell proliferation. IL-10 levels showed more decrease in SCIT, Apt-Ova-PLGA NPs (high dose) and Ova-PLGA NPs (high dose) than other groups. Histopathological examinations also confirmed in vitro results. Our findings suggest SLIT with this functionalized delivery system could be a promising approach for promoting the SLIT efficiency by decreasing the required allergen doses through specific delivery of allergen to sublingual DCs and enhancing the suppression of allergic responses.

Clinical Practice of Allergen Immunotherapy for Allergic Rhinoconjunctivitis and Asthma: An Expert Panel Report

Allergen immunotherapy (AIT) reduces symptoms and medication use associated with allergic rhinitis with or without conjunctivitis and allergic asthma. Although several AIT guidelines exist, there remain unanswered questions about AIT that are relevant to everyday practice. Our objective was to prepare an evidence-based overview addressing the practical aspects of AIT in clinical practice based on published evidence and the experience of international experts in the field. Topics covered include interpretation and translation of clinical trial data into everyday clinical practice (eg, allergen doses and treatment duration), assessment of risk and treatment of local and systemic allergic reactions, recommendations for improvement of AIT guidelines, and identification of appropriate data for seeking regulatory approval, to name a few. Many informational gaps in AIT practice need further evaluation as products and practices evolve.

Characterization of T cell receptors in a novel murine model of nickel-induced intraoral metal contact allergy

Nickel is a component of several alloy types that are widely used in our environment, including several dental alloy types that cause intraoral metal contact allergy. However, metal-specific immune responses in the oral mucosa have not been elucidated because a suitable animal model has not been established. In this study, we established a novel murine model of nickel-induced intraoral metal contact allergy and aimed to elucidate the immune response in terms of T-cell receptor repertoire and cytokine profiles in inflamed oral mucosa. The intraoral metal contact allergy model was induced by two sensitizations of nickel plus lipopolysaccharide solution into the postauricular skin followed by a single nickel challenge of the buccal mucosa. Cytokine expression profiles and T-cell phenotypes were determined by quantitative polymerase chain reaction. T cells accumulated in the cervical lymph nodes and inflamed oral mucosa were characterized by analyzing their T-cell receptor α- and β-chain repertoires, and the nucleotide sequences of complementary determining region 3. Significant swelling and pathological features were histologically evident at 1 day after challenge in mice with nickel allergy. At 1 day after the challenge, CD8-positive T cells producing high levels of T helper 1 type cytokines had accumulated in the allergic oral mucosa. At 7 days after the challenge, excessive nickel allergy in the oral mucosa was suppressed by regulatory T cells. Characterization of the T-cell receptor repertoire in nickel allergic mice revealed the presence of natural killer T cells and T cells bearing Trav6-6-Traj57 at 1 day after the challenge. Our murine model of nickel-induced intraoral metal contact allergy showed that natural killer T cells and T cells bearing Trav6-6-Traj57 might be involved in the immune responses of nickel-induced intraoral metal contact allergy.

Immunotherapy of house dust mite allergy

House dust mite (HDM) is a predominant source of indoor aeroallergen worldwide, which induces allergic diseases including allergic rhinoconjunctivitis, allergic asthma, atopic eczema and other allergic skin diseases. Allergen specific immunotherapy (AIT) is the only potential disease-modifying treatment of HDM allergic subjects. However, AIT remains underused due to no universally accepted allergen standardization and a shortage of rigorous clinical studies to confirm safety and efficacy. With the effort of doctors and researchers in allergy field, efficacy, safety, standardization and strategy of AIT are being continuously developed. This review presents the updated research based on recently published trials and meta-analyses.

Application of bacterial therapeutic vaccine Immunovac-VP4 in the treatment of pollinosis

AIM

The aim of the study was to study the effectiveness of the complex use of bacterial therapeutic vaccine Immunovac-VP4 and allergen-specific immune therapy (ASIT) in pollinosis in children and adults.

MATERIALS AND METHODS

Bacterial therapeutic vaccine Immunovac-VP4 was used annually, nasal and oral administration in patients before the course of ASIT standardized aqueous-salt solutions of allergens.

RESULTS

The therapeutic application of bacterial vaccines, Immunoac-ВП4 before the course ASIT has helped to reduce the frequency of acute respiratory infections in 8,5 times in comparison with the control group. Clinical efficacy of complex treatment according to the results of the survey of patients in 7 years after the start of therapy was 90%. There was a significant decrease In IgG4 to causally significant allergens, General immnunoglobulin E (IgE) and a tendency to decrease IgE.

CONCLUSION

The use of bacterial therapeutic vaccine Immunovac-VP4, which is a natural ligand of toll-like receptors in combination with ASIT, seems to be an effective and promising direction in the treatment of allergic diseases.

A practical guide to the sublingual immunotherapy tablet adverse event profile: implications for clinical practice

OBJECTIVES

Treatment with allergy immunotherapy improves allergic rhinoconjunctivitis, but can also improve comorbidities associated with allergic rhinitis such as asthma. Sublingual immunotherapy (SLIT)-tablets are a convenient and efficacious method of allergy immunotherapy. They are self-administered after the first tablet has been provided under medical supervision. Therapy may elicit local reactions or, rarely, systemic allergic reactions. The objective of this report is to inform healthcare practitioners about the safety and tolerability profile of SLIT-tablets and use this information to provide practical guidance that may inform patients regarding potential adverse reactions and how to manage them.

METHODS

Pooled analyses of safety data from completed randomized, multicenter, double-blind, placebo-controlled phase 2 and phase 3 US and EU trials of timothy grass, short ragweed, and SQ house dust mite SLIT-tablets were conducted to characterize safety and tolerability.

RESULTS

SLIT-tablets are generally well tolerated. No life-threatening events, serious systemic allergic reactions, or events that compromised the airway have been reported. The most common treatment-related adverse events (AEs) are oral site reactions, most of which begin on day 1 of treatment, recur for less than 2 weeks, and resolve after approximately 30-60 minutes. Systemic allergic reactions have been managed with conventional pharmacotherapy. Reactions treated with epinephrine are uncommon, but have been reported. Treatment of AEs, treatment discontinuation considerations, and patient FAQs regarding SLIT-tablet safety/tolerability are discussed.

CONCLUSIONS

This report gives healthcare providers valuable information to educate patients regarding what to expect in terms of SLIT-tablet safety and tolerability. Practical guidance is also provided to ensure proper treatment of any adverse reactions.

Evidence and evidence gaps of medical treatment of non-tumorous diseases of the head and neck

Unfortunately, the treatment of numerous otolaryngological diseases often lacks of evidence base because appropriate studies are missing.

Whereas sufficient high-quality trials exist for the specific immunotherapy of allergic rhinitis and in a limited measure also for the angiotensin-converting enzyme inhibitor induced angioedema, the evidence for Menière’s disease or for pharmacotherapy of postoperative laryngeal edema is rather poor. This contribution will discuss the trial situation and evidence of the respective diseases.

Efficacy and safety of SQ house dust mite (HDM) SLIT-tablet treatment of HDM allergic asthma

INTRODUCTION

In the treatment of house dust mite (HDM) respiratory allergic disease, allergy immunotherapy constitutes an add-on treatment option targeting the underlying immunological mechanisms of allergic disease. However, for the treatment of HDM allergic asthma, the use of subcutaneous allergy immunotherapy (SCIT) has been limited by the risk of systemic adverse events. Thus, sublingually administered allergy immunotherapy (SLIT) has been investigated as a treatment option with an improved tolerability profile that allows for safer treatment of patients with HDM allergic asthma.

AREAS COVERED

In this Drug Profile, we provide a review of the clinical data behind the SQ HDM SLIT-tablet, which was recently approved for the treatment of HDM allergic asthma and allergic rhinitis by regulatory authorities in several European countries. Expert commentary: The SQ HDM SLIT-tablet is the first allergy immunotherapy to be tested prospectively in patients with asthma, and to favorably modify patient relevant end points such as requirement for inhaled corticosteroid (ICS) or the time to first asthma exacerbation upon ICS reduction, suggesting that SQ HDM SLIT-tablet treatment may contribute to improving overall asthma control.

Immunotherapy in all aspects

Allergen immunotherapy is a form of long-term treatment that decreases symptoms for many people with allergic rhinitis, allergic asthma, conjunctivitis (eye allergy) or stinging insect allergy. In this review, we presented the important topics in immunotherapy. The important aspects of immunotherapy are considered to be "Immunologıcal responses to immunotherapy"; "The principal types of immunotherapy"; "Effectiveness"; "Indications"; "Contraindications"; "Allergen immunotherapy in children"; "Safety"; and "Anaphylactic reactions after immunotherapy". The principal types of immunotherapy are subcutaneous immunotherapy (SCIT) and sublingual immunotherapy. Both of them can be used in indicated cases. When using SCIT, physicians must be more careful because of reported rare fatal cases. The risks and benefits of continuing allergen immunotherapy in patients who have experienced severe systemic reactions should be carefully considered.

Regulatory T cells in children with allergy and asthma: it is time to act

Nowadays allergy and asthma are a huge medical problem. Despite deeper and more precise knowledge concerning their pathogenesis and the role of the immune system in these processes, so far immunotherapy is the only treatment which can modify the course of these diseases. Considering that regulatory T cells (Treg cells) have a great significance in pathogenesis of both diseases it seems appropriate to pay attention to their role in the treatment process. This work summarizes the Treg cells characteristics, the influence of allergen specific immunotherapy and other treatment modalities on Treg cells, and the possibility of using Treg cells in therapy.

An update on allergen immunotherapy and asthma

PURPOSE OF REVIEW

The aim is to review recent literature up to July 2013 concerning the effect of allergen-specific immunotherapy (AIT) on asthma. AIT, effective in combined allergic rhinitis and asthma, was previously described as a convenient approach able to improve clinical outcomes and reduce bronchial hyperresponsiveness. In addition, long-term and preventive effects on the onset of new sensitizations and progression from allergic rhinitis to asthma have been shown.

RECENT FINDINGS

Recent investigations, mainly based on observational or small open trials, confirmed previous findings, showing improvement in asthma control, symptoms and medication usage and steroid-sparing effects, sometimes inconsistent with changes in lung function. Some meta-analyses support the clinical benefit on adult and paediatric asthma. Only few trials, however, were specifically designed to explore asthma endpoints.

SUMMARY

Clinical studies primarily have focused on AIT, and research on asthma endpoints is scarce; however, the evidence of beneficial effect of AIT for the treatment of adults and children affected by allergic rhinitis with or without asthma suggests that this treatment can favourably affect asthma. In children, sublingual AIT has been more extensively investigated than injective. Confirmatory, adequately powered trials are needed to reinforce the evidence of efficacy for individual AIT products. The main drawback in using injective AIT for asthma is the risk of serious adverse reactions and uncontrolled asthma. The sublingual route is better tolerated and does not appear inferior. As standard controller pharmacotherapy seems unable to affect the natural course of asthma, the potentially disease-modifying effect of AIT represents an appealing perspective that requires further investigation.

Sublingual immunotherapy: World Allergy Organization position paper 2013 update

We have prepared this document, "Sublingual Immunotherapy: World Allergy Organization Position Paper 2013 Update", according to the evidence-based criteria, revising and updating chapters of the originally published paper, "Sublingual Immunotherapy: World Allergy Organization Position Paper 2009", available at http://www.waojournal.org. Namely, these comprise: "Mechanisms of sublingual immunotherapy;" "Clinical efficacy of sublingual immunotherapy" - reporting all the data of all controlled trials published after 2009; "Safety of sublingual immunotherapy" - with the recently published Grading System for adverse reactions; "Impact of sublingual immunotherapy on the natural history of respiratory allergy" - with the relevant evidences published since 2009; "Efficacy of SLIT in children" - with detailed analysis of all the studies; "Definition of SLIT patient selection" - reporting the criteria for eligibility to sublingual immunotherapy; "The future of immunotherapy in the community care setting"; "Methodology of clinical trials according to the current scientific and regulatory standards"; and "Guideline development: from evidence-based medicine to patients' views" - including the evolution of the methods to make clinical recommendations.Additionally, we have added new chapters to cover a few emerging crucial topics: "Practical aspects of schedules and dosages and counseling for adherence" - which is crucial in clinical practice for all treatments; "Perspectives and new approaches" - including recombinant allergens, adjuvants, modified allergens, and the concept of validity of the single products. Furthermore, "Raising public awareness about sublingual immunotherapy", as a need for our patients, and strategies to increase awareness of allergen immunotherapy (AIT) among patients, the medical community, all healthcare stakeholders, and public opinion, are also reported in detail.

Efficacy of sublingual immunotherapy for allergic asthma: retrospective meta-analysis of randomized, double-blind and placebo-controlled trials

BACKGROUND

Allergen-specific immunotherapy (SIT) is the only available curative choice with a disease-modifying effect against respiratory allergies. The efficacy of SIT via the sublingual route was demonstrated by a number of clinical trials. This meta-analysis was performed to investigate the clinical efficacy and safety of sublingual-specific immunotherapy (SLIT) for allergic asthma.

METHODS

PubMed, EMBASE and the Cochrane Central Register of Controlled Trials were searched for randomized, double-blind and placebo-controlled (DBPC) trials evaluating the efficacy and safety of SLIT on allergic asthma. Subgroup analyses were performed according to age, type of allergen and duration of SLIT treatment.

RESULTS

Sixteen randomized DBPC trials comprising 794 patients in total met the inclusion criteria. The results suggest that SLIT significantly reduces both symptom [standardized mean difference (SMD), -0.74; P=0.006] and medication scores (SMD, -0.78; P=0.02) compared with placebo. SLIT offers a better clinical response in mite sensitive asthmatics but without confirmed proof from subgroup analyses. Prolonged duration of treatment for more than 12 months brings no additive effects. Improvement in the skin prick test was also observed following immunotherapy. There was no consistent effect on forced expiratory volume in 1 s, serum levels of antigen-specific immunoglobulin G4 and immunoglobulin E in the treated group. The risk of adverse effects was relative risk 2.23 (P=0.01).

CONCLUSIONS

SLIT is safe and clinically effective in reducing symptoms and medication use for allergic asthma. Our subgroup analyses failed to identify a disproportionate benefit of SLIT in any specific group of asthmatics, but some possible trends did emerge.

Immunotherapy - risk/benefit in food allergy

Food allergy is a growing health concern in the westernized world with approx. 6% of children suffering from it. A lack of approved treatment has led to strict avoidance of the culprit food proteins being the only standard of care. Nowadays in-depth research is conducted to evaluate the possible use of allergen-specific immunotherapy (SIT) as an active therapeutic option for food allergy. Various routes of administration for the immunotherapy are investigated, including subcutaneous, oral, sublingual, and epicutaneous, and some appear to be successful in inducing a temporary tolerant state. Most research has been conducted with oral immunotherapy due to its efficacious and relatively safe profile. Increasing interest is dedicated to safer and more convenient approaches, such as sublingual and epicutaneous SIT; however, doubts exist about their possible capacity to induce temporary tolerant state and permanent oral tolerance. The high frequency of allergic adverse reactions of the various approaches and the inability to achieve permanent oral tolerance have highlighted the need of refinements in the strategies. A promising strategy for preventing IgE cross-linking and thus enhancing safety of SIT, while still activating T cells, is the use of tolerogenic peptides. The implementation of such an immunotherapy approach has the potential of not only increasing the chance of achieving a permanent state of tolerance, but also improving the safety and tolerability of the therapy. Immunotherapy for food allergy is still not ready for the clinic, but current and upcoming studies are dedicated to collect enough evidence for the possible implementation of allergen-SIT as a standard treatment for food allergy.

Allergen-specific immunotherapy: update on immunological mechanisms

Immunotherapy selectively modulates the allergen-specific immune response. It involves the gradual administration of increasing amounts of allergen for the purpose of inducing protective immunological changes and it is the only curative approach for specific type I allergy.

AIM

Description of the allergic inflammation.- Comprehension of the early cellular changes after specific immunotherapy has been initiated. Exposure of the mechanisms involved in tolerance induction by regulatory T cells (Treg) with the inhibition of the Th2 responses. Comprehension of IL-10 and transforming growth factor (TGF- ) roles. Explanation of specific IgE, IgG and IgA changes. Description of the suppression of inflammatory responses during immunotherapy.

Update on immune mechanisms associated with sublingual immunotherapy: practical implications for the clinician

Sublingual immunotherapy (SLIT) is established as a safe and efficacious treatment for patients with type I respiratory allergies. The ability of SLIT to elicit antigen (allergen)-specific tolerance is linked to the peculiar biology of oral antigen-presenting cells. In the absence of danger signals, Langerhans cells, myeloid dendritic cells, and macrophages located in oral tissues, tonsils, and draining cervical lymph nodes are biased toward the induction of T(H)1 and IL-10-producing CD4(+) regulatory T cells, thus supporting tolerance as opposed to inflammation. Sublingual administration does not lead to any detectable systemic exposure of intact allergens nor to IgE neosensitization. Oral tissues contain limited numbers of mast cells located in submucosal areas, thereby explaining the well-established safety profile of SLIT, with mostly local but rare systemic reactions. The induction of CD4(+) regulatory T cells and blocking anti-inflammatory IgGs or IgAs are considered important for tolerance induction after SLIT. Specific molecular signatures associated with tolerogenic dendritic cells were recently reported during the onset of SLIT efficacy in the peripheral blood of patients exhibiting clinical benefit. Collectively, these observations confirm the induction of strong allergen-specific suppressive/tolerogenic immune responses during SLIT and pave the ground for the identification of biomarkers of efficacy. Practical implications of this emerging scientific knowledge are presented (1) to support the rational design of second-generation sublingual vaccines based on purified allergens, vector systems and/or adjuvants and (2) to help the clinician in decision making during his/her practice.

Prophylactic vaccination with adjuvant monophosphoryl lipid a prevents Th2-mediated murine asthmatic responses

OBJECTIVE

Asthma is a chronic respiratory disorder characterized by airway hyperreactivity, eosinophilic infiltration, high titer of allergen-specific IgE, and overproduction of T helper 2 (Th2) cytokines. Antigen combined with an appropriate adjuvant and administrated through the proper route can elicit suitable immunological responses to protect humans and animals from diseases. Antigen formulated with monophosphoryl lipid A (MPLA) can produce priming of Th1-mediated immune responses. The purpose of this study was to examine the utility of MPLA as an adjuvant to prevent asthma.

METHODS

BALB/c mice were immunized with ovalbumin (OVA) formulated with or without MPLA by intraperitoneal, footpad, or subcutaneous injection. Vaccinated mice were challenged with OVA aerosol to estimate the protective efficacy of MPLA in comparison to Th2-adjuvant aluminum hydroxide (Alum). Airway hyperresponsiveness to methacholine, eosinophilia in bronchoalveolar lavage fluid (BALF), circulating titers of OVA-specific antibodies, and stimulating levels of IFN-γ and IL-4 cytokines from splenocytes were evaluated.

RESULTS

Mice immunized by all injection routes with OVA formulated with MPLA increased the ratio of Th1/Th2 responses compared to mice receiving antigen alone. For prophylactic vaccination purpose, MPLA reduced airway responsiveness and eosinophilic inflammation in the lung, decreased serum OVA-specific IgE level, and increased the serum ratio of OVA-specific IgG2a/IgG1 and the ratio of IFN-γ/IL4 from OVA-activated splenocytes compared with mice vaccinated with Alum.

CONCLUSION

MPLA may be clinically useful in the vaccination of individuals predisposed to asthma.

Allergen immunotherapy for allergic respiratory diseases

Allergen specific immunotherapy involves the repeated administration of allergen products in order to induce clinical and immunologic tolerance to the offending allergen. Immunotherapy is the only etiology-based treatment that has the potential for disease modification, as reflected by longterm remission following its discontinuation and possibly prevention of disease progression and onset of new allergic sensitizations. Whereas subcutaneous immunotherapy is of proven value in allergic rhinitis and asthma there is a risk of untoward side effects including rarely anaphylaxis. Recently the sublingual route has emerged as an effective and safer alternative. Whereas the efficacy of SLIT in seasonal allergy is now well-documented in adults and children, the available data for perennial allergies and asthma is less reliable and particularly lacking in children. This review evaluates the efficacy, safety and longterm benefits of SCIT and SLIT and highlights new findings regarding mechanisms, potential biomarkers and recent novel approaches for allergen immunotherapy.

Immunological mechanisms for desensitization and tolerance in food allergy

Food allergy is a major public health concern in westernized countries, estimated to affect 5 % of children and 3-4 % of adults. Allergen-specific immunotherapy for food allergy is currently being actively evaluated, but is still experimental. The optimal protocol, in terms of the route of administration of the food, target maintenance dose, and duration of maintenance therapy, and the optimal patient for these procedures are still being worked out. The mechanisms underlying successful food desensitization are also unclear, in part, because there is no standard immunotherapy protocol. The mechanisms involved, however, may include mast cell and basophil suppression, development of food-specific IgG4 antibodies, reduction in the food-specific IgE/IgG4 ratio, up-regulation and expansion of natural or inducible regulatory T cells, a skewing from a Th2 to a Th1 profile, and the development of anergy and/or deletion in antigen-specific cells. Additional studies are required to elucidate and understand these mechanisms by which desensitization and tolerance are achieved, which may reveal valuable biomarkers for evaluating and following food allergic patients on immunotherapy.

Epigenetic modifications and improved regulatory T-cell function in subjects undergoing dual sublingual immunotherapy

BACKGROUND

Allergen-specific immunotherapy is the only mode of therapy that has been demonstrated to offer a cure in patients with IgE-mediated respiratory allergies.

OBJECTIVE

We sought to demonstrate the safety and efficacy of timothy grass (TG) and dust mite (DM) dual sublingual immunotherapy (SLIT) and to begin to investigate the immune mechanisms involved in successful immunotherapy with multiple allergens.

METHODS

The safety and efficacy of dual SLIT with TG and DM in children and adults with demonstrated allergies to TG and DM were investigated in a single-center, randomized, double-blind, controlled phase I study. Thirty subjects received either TG and DM dual SLIT (n= 20) or placebo (n = 10). Immune parameters were evaluated for differentiation of desensitized subjects from control subjects.

RESULTS

Subjects treated with dual SLIT had decreased rhinoconjunctivitis scores (P < .001) and medication use scores (P < .001) and reduced responses to TG and DM allergen based on results of skin prick tests or nasal disk challenges (P < .01 and P < .001, respectively) compared with placebo-treated control subjects. An increase in TG- and DM-specific IgG(4) levels, reduced allergen-specific IgE levels, and subsequent basophil activation were observed in the active treatment group. Dual SLIT promoted allergen-specific suppressive CD4(+)CD25(high)CD127(low)CD45RO(+) forkhead box protein 3 (Foxp3)(+) memory regulatory T cells with reduced DNA methylation of CpG sites within the Foxp3 locus.

CONCLUSION

The results of this pilot study suggest that dual SLIT could be an effective means to treat subjects with sensitivities to a variety of allergens and that long-term tolerance might be induced by epigenetic modifications of Foxp3 in memory regulatory T cells.

μ-opioid receptor-mediated alterations of allergen-induced immune responses of bronchial lymph node cells in a murine model of stress asthma

BACKGROUND

Psychological stress has a recognized association with asthma symptoms. Using a murine model of allergic asthma, we recently demonstrated the involvement of μ-opioid receptors (MORs) in the central nervous system in the stress-induced exacerbation of airway inflammation. However, the involvement of MORs on neurons and immunological alterations in the stress asthma model remain unclear.

METHODS

MOR-knockout (MORKO) mice that express MORs only on noradrenergic and adrenergic neurons (MORKO/Tg mice) were produced and characterized for stress responses. Sensitized mice inhaled antigen and were then subjected to restraint stress. After a second antigen inhalation, bronchoalveolar lavage cells were counted. Before the second inhalation, bronchial lymph node (BLN) cells and splenocytes from stressed and non-stressed mice were cultured with antigen, and cytokine levels and the proportions of T cell subsets were measured.

RESULTS

Stress-induced worsening of allergic airway inflammation was observed in wild-type and MORKO/Tg mice but not MORKO mice. In wild-type stressed mice, IFN-γ/IL-4 ratios in cell culture supernatants and the proportion of regulatory T cells in BLN cell populations were significantly lower than those in non-stressed mice. These differences in BLN cells were not observed between the stressed and non-stressed MORKO mice. Restraint stress had no effect on cytokine production or T cell subsets in splenocytes.

CONCLUSIONS

Restraint stress aggravated allergic airway inflammation in association with alterations in local immunity characterized by greater Th2-associated cytokine production and a reduced development of regulatory T cells, mediated by MORs.

Comparative effect of pre-coseasonal and continuous grass sublingual immunotherapy in children

BACKGROUND

One of the most important aspects of sublingual immunotherapy (SLIT) is the regimen of administration. The aim of the study was to compare the efficacy and the safety of SLIT given pre-coseasonally (starting before the pollen season and continuing until the end of it) and continuously (all year round, independent of the pollen season) in children allergic to grass pollen.

METHODS

Sixty children aged 6-18, sensitive only to grass pollen, with rhinitis (20 patients had concomitant asthma) participated in the 2-year prospective, randomized, double-blind, placebo-controlled trial.

RESULTS

Both pre-coseasonal and continuous SLIT were associated with a substantial reduction in the combined symptoms/medication score when compared with placebo; there were no significant differences between the regimens (mean difference: 18.1 ± 12.4, P > 0.05). Similar changes were observed in the total symptoms score. Pre-coseasonal therapy, compared with continuous, was more effective in the reduction of nasal symptoms (mean difference: -18.0 ± 2.5, P = 0.006). We did not observe significant differences in medication, ocular, and asthma scores between the regimens. We did not observe changes in morning PEF, FEV1, and PD20 in any of the three groups nor between the groups throughout the study. We showed a significant decrease in FeNO level comparable in both active groups. There were no differences between groups in the induction of CD4CD25Foxp3-positive cells in peripheral blood during the study.

CONCLUSION

Both protocols were effective compared with placebo and showed similar decreases for combined symptoms/medication score and all secondary endpoints, with the exception of nasal symptoms that were lower in the pre-coseasonal group.

Quality of life improvement with sublingual immunotherapy: a prospective study of efficacy

Due to its excellent safety profile, ease of administration, and economic considerations, sublingual immunotherapy (SLIT) is becoming a preferred form of allergen specific immunotherapy. The efficacy of SLIT is still debated. The purpose of this act of practice trial is to evaluate quality of life outcomes in patients treated with SLIT. Fifty one patients with allergic rhinoconjunctivitis demonstrated by skin testing completed the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) at initiation, at four months and at 10-12 months of SLIT. Significant improvement (P < 0.05) on six of seven domain categories of the RQLQ questionnaire was noted. Total RQLQ scores also showed significant improvement. This study supports SLIT as a modality effective in controlling allergic symptoms.

Induction of tolerance via the sublingual route: mechanisms and applications

The clinical efficacy of sublingual immunotherapy (SLIT) with natural allergen extracts has been established in IgE-dependent respiratory allergies to grass or tree pollens, as well as house dust mites. Sublingual vaccines have an excellent safety record, documented with approximately 2 billion doses administered, as of today, in humans. The oral immune system comprises various antigen-presenting cells, including Langerhans cells, as well as myeloid and plasmacytoid dendritic cells (DCs) with a distinct localisation in the mucosa, along the lamina propria and in subepithelial tissues, respectively. In the absence of danger signals, all these DC subsets are tolerogenic in that they support the differentiation of Th1- and IL10-producing regulatory CD4(+) T cells. Oral tissues contain limited numbers of mast cells and eosinophils, mostly located in submucosal areas, thereby explaining the good safety profile of SLIT. Resident oral Th1, Th2, and Th17 CD4(+) T cells are located along the lamina propria, likely representing a defence mechanism against infectious pathogens. Second-generation sublingual vaccines are being developed, based upon recombinant allergens expressed in a native conformation, possibly formulated with Th1/T reg adjuvants and/or mucoadhesive particulate vector systems specifically designed to target oral dendritic cells.

Mechanisms of immunotherapy to aeroallergens

Allergen immunotherapy is allergen-specific, allergen dose- and time-dependent and is associated with long-term clinical and immunological tolerance that persists for years after discontinuation. Successful immunotherapy is accompanied by the suppression of numbers of T-helper 2 (Th2) effector cells, eosinophils, basophils, c-kit+mast cells and neutrophils infiltration in target organs, induction of IL-10 and/or TGF-β+Treg cells and increases in 'protective' non-inflammatory blocking antibodies, particularly IgG4 and IgA2 subclasses with inhibitory activity. These events are accompanied by a reduction and/or a redirection of underlying antigen-specific Th2-type T cell-driven hypersensitivity to the allergen(s) used for therapy. This suppression occurs within weeks or months as a consequence of the appearance of a population of regulatory T cells that exert their effects by mechanisms involving cell-cell contact, but also by the release of cytokines such as IL-10 (increases IgG4) and TGF-β (increases specific IgA). The more delayed-in-time appearance of antigen-specific T-helper 1 responses and alternative mechanisms such as Th2 cell anergy and/or apoptosis may also be involved. The mechanisms of sublingual immunotherapy are similar to those following a subcutaneous administration of allergen, whereas it is likely that additional events following antigen presentation in the sublingual mucosa and regional lymph nodes are involved. These insights have resulted in novel approaches and portend future biomarkers that may be surrogate or predictive of the clinical response to treatment.

Sublingual immunotherapy for treating allergic conjunctivitis

BACKGROUND

Allergic ocular symptoms, although frequently trivialised, are common and represent an important comorbidity of allergic rhinitis. Sublingual Immunotherapy (SLIT) is an effective and well-tolerated treatment for allergic rhinitis, but its effects on symptoms of ocular allergy have not been well established.

OBJECTIVES

To evaluate the efficacy of SLIT compared with placebo for reductions in ocular symptoms, topical ocular medication requirements and conjunctival immediate allergen sensitivity.

SEARCH STRATEGY

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 1), MEDLINE (January 1950 to January 2011), EMBASE (January 1980 to January 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2011), Web of Science (January 1970 to January 2011), Biosis Previews, (January 1979 to January 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) (January 2011), ClinicalTrials.gov (www.clinicaltrials.gov) (January 2011), the Australian New Zealand Clinical Trials Registry (ANZCTR) (www.actr.org.au) (July 2010), SCOPUS (November 2008) and the UK Clinical Trials Gateway (January 2010). There were no language or date restrictions in the search for trials. All electronic databases except for SCOPUS, the UK Clinical Trials Gateway and ANZCTR were last searched on 19 January 2011.

SELECTION CRITERIA

Randomised controlled trials (RCTs), double-masked and placebo controlled, which evaluated the efficacy of SLIT in patients with symptoms of allergic rhinoconjunctivitis (ARC) or allergic conjunctivitis (AC).

DATA COLLECTION AND ANALYSIS

The primary outcome was the total ocular symptom scores. Secondary endpoints included individual ocular symptom scores (such as itchy eyes, red eyes, watery eyes, swollen eyes), ocular medication scores (eye drops) and conjunctival immediate allergen sensitivity (CIAS). Data were analysed and reported as standardised mean differences (SMDs) using Review Manager software.

MAIN RESULTS

Forty-two trials (n = 3958 total participants; n= 2011 SLIT and n = 1947 placebo) had available data to evaluate the efficacy of SLIT on AC and were included in the meta-analyses. Heterogeneity among studies (I(2) statistic) was around 50% or below for all endpoints. Sublingual immunotherapy induced a significant reduction in both total ocular symptom scores (SMD -0.41; 95% confidence interval (CI) -0.53 to -0.28; P < 0.00001; I(2) = 59%) and individual ocular symptom scores for red eyes (SMD -0.33; 95% CI -0.45 to -0.22; P < 0.00001; I(2) = 27%), itchy eyes (SMD -0.31; 95% CI -0.42 to -0.20; P < 0.00001; I(2) = 46%) and watery eyes (SMD -0.23; 95% CI -0.34 to -0.11; P < 0.0001; I(2) = 42%) compared to placebo. Those participants having active treatment showed an increase in the threshold dose for the conjunctival allergen provocation test (SMD 0.35; 95% CI 0.00 to 0.69; P = 0.05; I(2) = 43%). No significant reduction was observed in ocular eye drops use (SMD -0.10; 95% CI -0.22 to 0.03; P = 0.13; I(2) = 34%).

AUTHORS' CONCLUSIONS

Overall, SLIT is moderately effective in reducing total and individual ocular symptom scores in participants with ARC and AC. There were however some concerns about the overall quality of the evidence-base, this relating to inadequate descriptions of allocation concealment in some studies, statistical heterogeneity and the possibility of publication bias. There is a need for further large rigorously designed studies that study long-term effectiveness after discontinuation of treatment and establish the cost-effectiveness of SLIT.

Sublingual immunotherapy in patients with allergic rhinoconjunctivitis

Sublingual immunotherapy (SLIT) is a well-established treatment option for allergic rhinitis in several European countries, but it is considered investigational in the United States. Studies conducted in Europe provided a large body of evidence supporting the safety and efficacy of SLIT, but those studies used allergen products that are different from those that are likely to be approved in the United States, and many of them were not controlled, randomized, double-blinded trials. This review summarize research conducted on the efficacy, safety, and mechanisms of SLIT published during the past year, with a focus on ragweed and grass antigens. Results of recent US studies document the safety and efficacy of SLIT and have started to yield insight into the mechanisms of SLIT.

Strategies of mucosal immunotherapy for allergic diseases

Incidences of allergic disease have recently increased worldwide. Allergen-specific immunotherapy (SIT) has long been a controversial treatment for allergic diseases. Although beneficial effects on clinically relevant outcomes have been demonstrated in clinical trials by subcutaneous immunotherapy (SCIT), there remains a risk of severe and sometimes fatal anaphylaxis. Mucosal immunotherapy is one advantageous choice because of its non-injection routes of administration and lower side-effect profile. This study reviews recent progress in mucosal immunotherapy for allergic diseases. Administration routes, antigen quality and quantity, and adjuvants used are major considerations in this field. Also, direct uses of unique probiotics, or specific cytokines, have been discussed. Furthermore, some researchers have reported new therapeutic ideas that combine two or more strategies. The most important strategy for development of mucosal therapies for allergic diseases is the improvement of antigen formulation, which includes continuous searching for efficient adjuvants, collecting more information about dominant T-cell epitopes of allergens, and having the proper combination of each. In clinics, when compared to other mucosal routes, sublingual immunotherapy (SLIT) is a preferred choice for therapeutic administration, although local and systemic side effects have been reported. Additionally, not every allergen has the same beneficial effect. Further studies are needed to determine the benefits of mucosal immunotherapy for different allergic diseases after comparison of the different administration routes in children and adults. Data collected from large, well-designed, double-blind, placebo-controlled, and randomized trials, with post-treatment follow-up, can provide robust substantiation of current evidence.

Specific immunotherapy: beyond the clinical scores

OBJECTIVE

The efficacy of specific immunotherapy always has been evaluated by clinical scores (symptoms or medication intake). Nonetheless, specific immunotherapy possesses some special or "additional" effects, including the carryover effect and the preventive actions, which are unique. Those effects are the consequence of the complex mechanism of action, which induces profound and persistent modifications in the immune response to allergens. The literature is reviewed to evaluate the available experimental data on this.

DATA SOURCES

The main databases (EmBase, Medline, Scopus) were searched.

STUDY SELECTION

Clinical trials of immunotherapy, either randomized or not, including placebo-controlled trials, were selected.

RESULTS

Currently, the carryover effect (persistence of the benefit after stopping the treatment) is well ascertained for injection immunotherapy, whereas fewer data are available for the sublingual route. On the contrary, the demonstration of the prevention of asthma onset relies on 2 randomized studies for sublingual immunotherapy, and 1 single study for subcutaneous immunotherapy.

CONCLUSION

Although additional confirmatory data are needed, possibly obtained with a rigorous methodology, the long-lasting and preventive effects of specific immunotherapy always should be taken into account when the efficacy is evaluated. The additional effects also may have relevant socioeconomic implications.

Immunotherapy in asthma

Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role. Chronic inflammation is associated with airway hyper-responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing, as well as variable airflow obstruction within the lung. With time, such airflow obstruction may become permanent due to remodeling. It has been treated for more than 100 years by subcutaneous immunotherapy with allergen extracts but in recent years, other forms and types of immunotherapy have been introduced. Perhaps the most successful of these to date, is sublingual immunotherapy, which has attained significant usage in European countries but has yet to make inroads into clinical practice in North America. Other mechanisms to modify the inflammatory responses of asthma have included immunotherapy with recombinant allergens, the use of allergen peptides targeting antigen-specific T cells and the administration of Toll-like receptor agonists coupled to allergen proteins. As the inflammatory responses in asthma frequently involve IgE, a modified monoclonal antibody to IgE and interfering with its binding to the IgE receptor have gained acceptance for treating severe allergic asthma. Other monoclonal antibodies or recombinant receptor antagonists are being assessed for their ability to block other contributors to the inflammatory response. Finally, attempts have been made to generate autoantibody responses to cytokines implicated in asthma. Most of these therapies aim to modify or inhibit the so-called Th 2 immune response, which is implicated in many forms of asthma, or to inhibit cytokines involved in these responses. However, an added benefit of classical immunotherapy seems to be the ability to prevent the allergic progression to new sensitivities and new forms of allergic disease.

Tissue-based class control: the other side of tolerance

In this Essay, we offer a new perspective on how immune responses are regulated. We do not cover how they are turned on and off, but focus instead on the second major aspect of an immune response: the control of effector class. Although it is generally thought that the class of an immune response is tailored to fit the invading pathogen, we suggest here that it is primarily tailored to fit the tissue in which the response occurs. To this end, we cover such topics as the nature of T helper (T(H)) cell subsets (current and yet to be discovered), the nature of privileged sites, the difference between oral tolerance and oral vaccination, why the route of immunization matters, whether the T(H)1-type response is really the immune system's primary defense, and whether there might be a different role for some regulatory T cells.

Ara h 2 peptides containing dominant CD4+ T-cell epitopes: candidates for a peanut allergy therapeutic

BACKGROUND

Peanut allergy is a life-threatening condition; there is currently no cure. Although whole allergen extracts are used for specific immunotherapy for many allergies, they can cause severe reactions, and even fatalities, in peanut allergy.

OBJECTIVE

This study aimed to identify short, T-cell epitope-based peptides that target allergen-specific CD4(+) T cells but do not bind IgE as candidates for safe peanut-specific immunotherapy.

METHODS

Multiple CD4(+) T-cell lines specific for the major peanut allergen Ara h 2 were generated from PBMCs of 16 HLA-diverse subjects with peanut allergy by using 5,6-carboxyfluorescein diacetate succinimidylester-based methodology. Proliferation and ELISPOT assays were used to identify dominant epitopes recognized by T-cell lines and to confirm recognition by peripheral blood T cells of epitope-based peptides modified for therapeutic production. HLA restriction of core epitope recognition was investigated by using anti-HLA blocking antibodies and HLA genotyping. Serum-IgE peptide-binding was assessed by dot-blot.

RESULTS

Five dominant CD4(+) T-cell epitopes were identified in Ara h 2. In combination, these were presented by HLA-DR, HLA-DP, and HLA-DQ molecules and recognized by T cells from all 16 subjects. Three short peptide variants containing these T-cell epitopes were designed with cysteine-to-serine substitutions to facilitate stability and therapeutic production. Variant peptides showed HLA-binding degeneracy, did not bind peanut-specific serum IgE, and could directly target T(H)2-type T cells in peripheral blood of subjects with allergy.

CONCLUSION

Short CD4(+) T-cell epitope-based Ara h 2 peptides were identified as novel candidates for a T-cell-targeted peanut-specific immunotherapy for an HLA-diverse population.

Immunological effects of sublingual immunotherapy: clinical efficacy is associated with modulation of programmed cell death ligand 1, IL-10, and IgG4

Sublingual immunotherapy (SLIT) is an alternate route of administration of allergen-specific immunotherapy with an improved safety profile; to clarify the immune mechanisms elicited by this therapy, we analyzed the clinical and immunologic effects of SLIT in patients with a clinical history of ragweed sensitization. To analyze possible difference among immunotherapeutic protocols, we also compared patients receiving preseasonal, seasonal, or prolonged sublingual therapy (≥ 3 y); patients receiving symptomatic therapy alone were enrolled as well in the study. Clinical and immunological parameters were measured twice in and out of the pollination period. Clinical benefits, as measured by the visual analog scale for symptoms and for use of drugs, were evident in all three groups of individuals receiving immunotherapy, but were significantly better in patients undergoing prolonged SLIT. Immunologically, SLIT resulted in increased IL-10 production, programmed cell death ligand 1 expression, and concentration of allergen-specific IgG4, as well as in the reduction of CD80 and CD86 expression and IL-4 production. SLIT, thus, is associated with modulation of programmed cell death ligand 1 expression and IL-10 synthesis and favors the production of allergen-specific IgG4. These effects are evident from the first pollen season, independently from therapeutic regimen (preseasonal or seasonal) even if a prolonged treatment is necessary to obtain full clinical efficacy. A more detailed understanding of the interaction of allergen and APCs within the oral mucosa will allow improved targeting of allergy vaccine.

Regulatory T cells, inflammation and the allergic response-The role of glucocorticoids and Vitamin D

Regulatory T cells (TRegs) play a central role in the maintenance of peripheral tolerance. They prevent inappropriate immune responses to ubiquitous allergens in healthy individuals, and contribute to the maintenance of immune homeostasis in the airways. Both Foxp3+ and IL-10+ TReg have been implicated in these functions. Glucocorticoids represent the mainstay of treatment for asthma and other allergic conditions, and evidence that steroids influence TReg function will be reviewed. Growing bodies of epidemiological and immunological data suggest a role for endogenous Vitamin D in immune regulation. This review will discuss the role of glucocorticoids and Vitamin D, and their potential interactions in promoting tolerance in the context of allergic disease and asthma.