Induction of interleukin 10 by sublingual immunotherapy for house dust mites: a preliminary report

Sublingual Immunotherapy: How Sublingual Allergen Administration Heals Allergic Diseases; Current Perspective about the Mode of Action

Owing to the successful application of sublingual immunotherapy (SLIT), allergen immunotherapy (AIT) has become one of the leading treatments for allergic diseases. Similar to the case with other AITs, such as subcutaneous and oral immunotherapies, not only the alleviation of allergic symptoms, but also the curing of the diseases can be expected in patients undergoing SLIT. However, how and why such strong efficacy is obtained by SLIT, in which allergens are simply administered under the tongue, is not clearly known. Various potential mechanisms, including the induction of blocking antibodies, T cell tolerance, regulatory B and T cells, CD103^-CD11b⁺ classical dendritic cells, and CD206⁺ macrophages, and the reduction of innate lymphoid cells, mast cells, and basophils, have been suggested. Recently, through a comparative analysis between high- and non-responder patients of SLIT, we have successfully proposed several novel mechanisms. Here, we introduce our recent findings and summarize the current understanding of the mechanisms underlying the strong efficacy of SLIT.

Role of interleukins 12B and 17A genetic variation in house dust mites allergy

Background

The house dust mites (HDM) constitute a major cause of allergic diseases all over the world. Genes encoding interleukins 12B and 17A which determine the course of T cell-mediated immune response are prime candidates as allergic disease susceptibility. The purpose of this study was to evaluate whether a single-nucleotide polymorphisms (SNP) of interleukins 12B + 1188A/C (rs3212227) and 17A −197G/A (rs2275913) confers susceptibility to HDM allergic diseases. Through a case-control study, 120 subjects served as 60 dust mites' allergic patients and 60 healthy non-allergic controls. Total immunoglobulin (Ig) E level, eosinophilic count, serum interleukins 4, 10, 12B, and 17A levels for the studied subjects were measured. Then, genotyping of single-nucleotide polymorphisms (SNPs) at +1188A/C for IL12B and −197G/A for IL17A gene were conducted using restriction fragment length polymorphisms (RFLP-PCR).

Results

The present study showed that in HDMs' allergic subjects there was a significant increase in IL12B (+1188 A/C) and IL17A (−197 G/A) genotype variants compared to that of the controls. There was a significant increase in total IgE levels, eosinophil counts, and the levels of both IL-4 and IL-17A, while IL12B was significantly lower in patients compared to that of the controls. There was no significant difference in IL-10 levels between patients and controls.                                                                            

Conclusion

Our findings indicate that IL12B (+1188 A/C) and IL17A (−197G/A) might be associated with an increase in the susceptibility to dust mites’ allergic patients.

Decreased Treg-derived miR-181a and miR-155 correlated with reduced number and function of Treg cells in allergic rhinitis children

BACKGROUND

Regulatory cells (Tregs) have been proved to be deeply involved in allergic airway inflammation. This study aims to evaluate the expression of miRNA in children with AR and their association with Tregs as well as the severity of AR.

METHODS

Twenty-five AR children and 20 healthy children were enrolled in this study. The Treg-cell percentage and expression of IL-10 and TGF-β were detected by flow cytometry and enzyme-linked immunosorbent assay. The microRNA microarray analysis in purified Tregs was performed and differentially expressed microRNAs were confirmed by quantitative polymerase chain reaction (qPCR).

RESULTS

Children with AR had lower percentage of Tregs and expression of IL-10 and TGF-beta compared with control children. We found that significantly lower levels of miR-155 and miR-181a in Tregs from AR than healthy controls. Furthermore, intracellular miR-155 and miR-181a level were positively correlated with percentage of Tregs and expression of IL-10 and TGF-beta. Similarly, total nasal severity scores (TNSS) were found to be negatively correlated with miR-155 and miR-181a levels.

CONCLUSION

Decreased Treg-derived miR-181a and miR-155 were correlated with reduced number and function of Tregs in AR children. The intracellular miR-155 and miR-181a levels may serve as predictors of disease severity in childhood AR.

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.

Basic science for the clinician: Mechanisms of sublingual and subcutaneous immunotherapy

OBJECTIVE

To discuss the general immunologic changes that occur during immunotherapy, focusing on the differences between subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT).

DATA SOURCES

PubMed literature review.

STUDY SELECTIONS

Articles pertaining to SCIT and SLIT, with specific emphasis on those that included immune mechanistic studies.

RESULTS

Both SCIT and SLIT are characterized by the induction of regulatory B and T cells, decreased allergen-specific T-cell proliferation, a shift from a TH2 to TH1 cytokine milieu and from an IgE to an IgG4/IgA antibody response. These changes are accompanied by clinical improvement in symptoms.

CONCLUSION

Immunotherapy using allergen extracts administered via both subcutaneous and sublingual approaches have demonstrated efficacy in the treatment of allergic rhinoconjunctivitis and other allergic conditions. There are subtle differences between the approaches, and understanding these differences may help clinicians select a preferred route of therapy for particular patients or allergens, depending on the immune response that is being targeted.

Novel approaches and perspectives in allergen immunotherapy

In this review, we report on relevant current topics in allergen immunotherapy (AIT) which were broadly discussed during the first Aarhus Immunotherapy Symposium (Aarhus, Denmark) in December 2015 by leading clinicians, scientists and industry representatives in the field. The aim of this symposium was to highlight AIT-related aspects of public health, clinical efficacy evaluation, mechanisms, development of new biomarkers and an overview of novel therapeutic approaches. Allergy is a public health issue of high socioeconomic relevance, and development of evidence-based action plans to address allergy as a public health issue ought to be on national and regional agendas. The underlying mechanisms are in the focus of current research that lays the ground for innovative therapies. Standardization and harmonization of clinical endpoints in AIT trials as well as current knowledge about potential biomarkers have substantiated proof of effectiveness of this disease-modifying therapeutic option. Novel treatments such as peptide immunotherapy, intralymphatic immunotherapy and use of recombinant allergens herald a new age in which AIT may address treatment of allergy as a public health issue by reaching a large fraction of patients.

Allergen-driven HLA-G expression and secretion in peripheral blood mononuclear cells from allergic rhinitis patients

BACKGROUND

It has been reported that soluble HLA-G serum levels are increased in patients with pollen-induced allergic rhinitis and decrease after immunotherapy. However, no functional study has been conducted so far. The aim of this study was to evaluate the membrane expression and secretion of HLA-G molecules in peripheral blood mononuclear cells from allergic rhinitis patients after in vitro incubation with the causal allergen.

METHODS AND RESULTS

Twenty-two allergic rhinitis patients and ten healthy subjects were enrolled. Membrane HLA-G expression was determined by flow cytometry and soluble HLA-G in culture supernatant was determined by immunoenzymatic assay. HLA-G expression was detected in CD4+ (T-helper-2) cells and monocytes after in vitro stimulation with the causal allergen but not with non specific stimuli and non causal allergens. Accordingly, the release of soluble HLA-G in culture supernatant occurred only after the stimulation with the causal allergen. Collectively, these results were confirmed by Western blot analysis.

CONCLUSIONS

The present study provides the first in vitro evidence that in allergic patients HLA-G expression and secretion is specifically induced by the causal allergen. These data may add new insights into the pathogenetic mechanisms underlying allergic inflammation and allergen specific immunotherapy.

Immunoregulatory Role of HLA-G in Allergic Diseases

Allergic diseases are sustained by a T-helper 2 polarization leading to interleukin-4 secretion, IgE-dependent inflammation, and mast cell and eosinophil activation. HLA-G molecules, both in membrane-bound and in soluble forms, play a central role in modulation of immune responses. Elevated levels of soluble HLA-G (sHLA-G) molecules are detected in serum of patients with allergic rhinitis to seasonal and perennial allergens and correlate with allergen-specific IgE levels, clinical severity, drug consumption, and response to allergen-specific immunotherapy. sHLA-G molecules are also found in airway epithelium of patients with allergic asthma and high levels of sHLA-G molecules are detectable in plasma and bronchoalveolar lavage of asthmatic patients correlating with allergen-specific IgE levels. Finally, HLA-G molecules are expressed by T cells, monocytes-macrophages, and Langerhans cells infiltrating the dermis of atopic dermatitis patients. Collectively, although at present it is difficult to completely define the role of HLA-G molecules in allergic diseases, it may be suggested that they are expressed and secreted by immune cells during the allergic reaction in an attempt to suppress allergic inflammation.

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.

Immune mechanisms of sublingual immunotherapy

Sublingual immunotherapy (SLIT) is a well-established allergen-specific immunotherapy and a safe and effective strategy to reorient inappropriate immune responses in allergic patients. SLIT takes advantage of the tolerogenic environment of the oral mucosa to promote tolerance to the allergen. Several clinical studies have investigated the complex interplay of innate and adaptive immune responses that SLIT exploits. The oral immune system is composed of tolerogenic dendritic cells that, following uptake of allergen during SLIT, support the differentiation of T helper cell type 1 (Th1) and the induction of IL-10-producing regulatory T cells. Following SLIT, allergic disease-promoting T helper cell type 2 (Th2) responses shift to a Th1 inflammatory response, and IL-10 and transforming growth factor (TGF)-β production by regulatory T cells and tolerogenic dendritic cells suppress allergen-specific T cell responses. These immune changes occur both in the sublingual mucosa and in the periphery of a patient following SLIT. SLIT also promotes the synthesis of allergen-specific IgG and IgA antibodies that block allergen-IgE complex formation and binding to inflammatory cells, thus encouraging an anti-inflammatory environment. Several of these revealing findings have also paved the way for the identification of biomarkers of the clinical efficacy of SLIT. This review presents the emerging elucidation of the immune mechanisms mediated by SLIT.

Mechanisms of allergen-specific immunotherapy: multiple suppressor factors at work in immune tolerance to allergens

Allergen-specific immunotherapy (AIT) has been used for more than 100 years as a desensitizing therapy for IgE-mediated allergic diseases and represents a potentially curative way of treatment. The mechanisms of action of AIT include the induction of very early desensitization of mast cells and basophils; generation of regulatory T and regulatory B (Breg) cell responses; regulation of IgE and IgG4; decreases in numbers and activity of eosinophils and mast cells in mucosal allergic tissues; and decreases in the activity of basophils in circulation. Skewing of allergen-specific effector T and effector B cells to a regulatory phenotype appears as a key event in the course of AIT and normal immune response to allergens. Recently, inducible IL-10-secreting Breg cells were also demonstrated to contribute to allergen tolerance through suppression of effector T cells and selective induction of IgG4 isotype antibodies. Allergen-specific regulatory T and Breg cells orchestrate a general immunoregulatory activity, which can be summarized as suppression of cytokines from inflammatory dendritic cells; suppression of effector TH1, TH2, and TH17 cells; suppression of allergen-specific IgE and induction of IgG4; and suppression of migration of mast cells, basophils, eosinophils, and effector T cells to tissues. A detailed knowledge of the mechanisms of AIT is not only important in designing the prevention and treatment of allergic diseases but might also find applications in the treatment of autoimmune diseases, organ transplantation, chronic infection, and cancer.

T-cell biology in immunotherapy

OBJECTIVE

This review discusses the current state of immunotherapy and how the CD4 T-cell response is pivotal in altering the allergic response.

DATA SOURCES

PubMed literature review.

STUDY SELECTIONS

Articles pertaining to subcutaneous, sublingual, and oral immunotherapies, with specific emphasis on those describing the T-cell response.

RESULTS

Although many drugs are available that help ameliorate allergic symptoms, the only intervention that has proved to provide long-term benefit and modulation of disease is immunotherapy. Many routes of immunotherapy are being pursued, including subcutaneous, sublingual, and oral immunotherapies; however, subcutaneous immunotherapy has the historical record of leading to immune changes that alter the immune response at subsequent allergen exposure. These changes are mediated by the induction of peripherally derived T-regulatory cells and appear to occur only after high-dose therapy for 3 to 5 years. Newer methods of sublingual and oral immunotherapies are currently being investigated, but their efficacy is not yet on par with subcutaneous immunotherapy.

CONCLUSION

The primary cells ultimately responsible for successful immunomodulation are CD4 T cells, specifically peripherally derived T-regulatory cells.

Allergen immunotherapy for house dust mite: clinical efficacy and immunological mechanisms in allergic rhinitis and asthma

INTRODUCTION

There is an increasing prevalence of atopic diseases such as allergic rhinitis and asthma with house dust mite (HDM) being the common allergen that is highly associated with allergic rhinitis and asthma. Allergen avoidance and pharmacotherapy are part of treatment but it has proved difficult to change the course of HDM-related allergic diseases. Allergen immunotherapy (AIT) has been in use for the past century and has been shown to be effective in the treatment of allergic respiratory disease.

AREAS COVERED

This review exclusively focuses on HDM-AIT and discusses the differences in clinical efficacy and safety, long-term effect after discontinuation and immunological changes observed in both HDM-subcutaneous immunotherapy (SCIT) and HDM-sublingual immunotherapy (SLIT) in the treatment of allergic rhinitis and asthma in both pediatric and adult populations.

EXPERT OPINION

The majority of studies involved small numbers of patients, variable doses of major allergens and are of variable quality. There is good evidence for HDM-SCIT efficacy and its long-term effect in adults and children, whereas at the present time, evidence for HDM-SLIT is unconvincing, particularly in children. In carefully selected patients, HDM-SCIT is effective and safe. More definitive trials are needed before HDM-SLIT can be recommended in routine practice for rhinitis and/or asthma.

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.

Emerging drugs for perennial allergic rhinitis

INTRODUCTION

Allergic rhinitis (AR) is a high-prevalence disease, sustained by an IgE-triggered reaction with histamine release, followed by an inflammatory response which involves cells, mediators, cytokines and adhesion molecules. According to its duration, AR can be either intermittent or persistent. In the persistent form, the inflammatory component usually predominates.

AREAS COVERED

The current therapeutic strategy is based on antihistamines, antileukotrienes and on corticosteroids (which broadly act on inflammation). Allergen-specific immunotherapy is a biological response modifier that affects the immune response to allergens in a broad sense. The available pharmacotherapy is overall effective in controlling symptoms and inflammation, but safety concerns may be present (especially for prolonged treatments), and a proportion of patients remain uncontrolled. The available therapeutic innovations, as derived from the most recent literature are reviewed herein.

EXPERT OPINION

In the last years there have been very few innovative approaches to optimize the management of AR. These include new histamine receptor antagonists, combination therapy and strategies to selectively block relevant signaling pathways of the allergic reaction. Some more promising advances have been shown for allergen immunotherapy, where a number of new strategies are currently under development.

Therapeutic effects and biomarkers in sublingual immunotherapy: a review

Immunotherapy is considered to be the only curative treatment for allergic diseases such as pollinosis, perennial rhinitis, asthma, and food allergy. The sublingual route is widely applied for immunotherapy for allergy, instead of the conventional administration by subcutaneous route. A recent meta-analysis of sublingual immunotherapy (SLIT) has shown that this approach is safe, has positive clinical effects, and provides prolonged therapeutic effects after discontinuation of treatment. However, the mechanism of SLIT and associated biomarkers are not fully understood. Biomarkers that change after or during SLIT have been reported and may be useful for response monitoring or as prognostic indicators for SLIT. In this review, we focus on the safety, therapeutic effects, including prolonged effects after treatment, and new methods of SLIT. We also discuss response monitoring and prognostic biomarkers for SLIT. Finally, we discuss immunological mechanisms of SLIT with a focus on oral dendritic cells and facilitated antigen presentation.

Specific immunotherapy in children: the evidence

Specific immunotherapy (SIT) is the only treatment able to not only act on the symptoms of allergy but also act on the causes. At present, SIT may be administered in two forms: subcutaneous (SCIT) and sublingual immunotherapy (SLIT). SCIT represents the standard modality of treatment while SLIT has recently been introduced into clinical practice and today represents an accepted alternative to SCIT. The main advantages of SIT that are lacking with drug treatment are long-lasting clinical effects and alteration of the natural course of the disease. This prevents the new onset of asthma in patients with allergic rhinitis and the onset of new sensitizations. The mechanism of action of both routes is similar; they modify peripheral and mucosal Th2-responses into a prevalent Th1-polarization with subsequent reduction of the allergic inflammatory reaction. Both have long-term effects for years after they have been discontinued, although for SLIT these evidences are insufficient. To date several guidelines have defined indications, controindications, side-effects, and clinical aspect for SCIT and SLIT. New forms of immunotherapy, allergen products and approaches to food allergy and atopic eczema represents the future of SIT.

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.

Oral macrophage-like cells play a key role in tolerance induction following sublingual immunotherapy of asthmatic mice

Sublingual allergen-specific immunotherapy (SLIT) is a safe and efficacious treatment for type 1 respiratory allergies. Herein, we investigated the key subset(s) of antigen-presenting cells (APCs) involved in antigen/allergen capture and tolerance induction during SLIT. Following sublingual administration, fluorochrome-labeled ovalbumin (OVA) is predominantly captured by oral CD11b⁺CD11c⁻ cells that migrate to cervical lymph nodes (CLNs) and present the antigen to naive CD4⁺ T cells. Conditional depletion with diphtheria toxin of CD11b⁺, but not CD11c⁺ cells, in oral tissues impairs CD4⁺ T-cell priming in CLNs. In mice with established asthma to OVA, specific targeting of the antigen to oral CD11b⁺ cells using the adenylate cyclase vector system reduces airway hyperresponsiveness (AHR), eosinophil recruitment in bronchoalveolar lavages (BALs), and specific Th2 responses in CLNs and lungs. Oral CD11b⁺CD11c⁻ cells resemble tolerogenic macrophages found in the lamina propria (LP) of the small intestine in that they express the mannose receptor CD206, as well as class-2 retinaldehyde dehydrogenase (RALDH2), and they support the differentiation of interferon-γ/interleukin-10 (IFNγ/IL-10)-producing Foxp3⁺ CD4⁺ regulatory T cells. Thus, among the various APC subsets present in oral tissues of mice, macrophage-like cells play a key role in tolerance induction following SLIT.

Sublingual immunotherapy in allergic rhinitis

Current treatment options for allergic rhinitis (AR) include allergen avoidance and environmental control, pharmacotherapy, nasal surgery and immunotherapy. Among these, immunotherapy is the only therapeutic option that modifies fundamental immunologic mechanism by inducing desensitization. Specific allergen immunotherapy has been used for 1 century since 1911 and subcutaneous immunotherapy (SCIT) has been demonstrated to be effective in asthma and AR. However, SCIT has several disadvantages such as inconvenience, invasiveness and potentially severe systemic reactions. Thus, sublingual immunotherapy (SLIT) has recently received much attention around the world as a treatment for AR and is now widely used to replace the subcutaneous route. SLIT has recently been introduced in Korea and is now available for AR treatment in the Asia-Pacific region. This review offers better understanding of SLIT for AR by summarizing published articles and our previous works regarding proposed mechanisms, indication and efficacy, safety and adverse events, and compliance.

Sublingual immunotherapy: other indications

Sublingual immunotherapy (SLIT) represents a significant advance and it seems particularly suitable in pediatric patients. There are favorable results for food allergy in controlled trials. For latex allergy, the results of several trials are encouraging. For atopic dermatitis, previous experience with subcutaneous immunotherapy and some earlier trials suggest the possible application of SLIT in children with mild to moderate dermatitis and sensitization to dust mite, but this recommendation is considered insufficiently evidence based. In hymenoptera allergy, the only trial available is a proof-of-concept study in large local reactions that needs to be confirmed in well-controlled studies.

Impairment of lung function might be related to IL-10 and IFN-γ defective production in allergic children

A functional defect of T regulatory cells (Tregs) has been proposed as pathogenic mechanism of allergic reaction. Impairment of lung function frequently occurs in children with respiratory allergy. This study aimed at investigating the possible role of IL-10 and IFN-γ on lung function deterioration in allergic children. Forty children with mild asthma, monosensitized to house dust mites, were evaluated and followed-up for 2 years. Spirometry was performed in all children. IL-10 and IFN-γ were evaluated in in vitro experiments. FEV(1), FVC, and FEF(25-75), evaluated as percent of predicted, significantly diminished over time (p<0.0001, p=0.03, and p<0.0001 respectively). There was a strong relationship between changes in spirometric parameters and IL-10 production and between changes in FEV(1) values and IFN-γ production over time. This preliminary study provided evidence that IL-10 and IFN-γ production could be defective in allergic children prone to develop functional impairment.

Pediatric allergy and immunology in Italy

In Italy, according to the International Study on Asthma and Allergies in Childhood study, the prevalence of current asthma, allergic rhinoconjunctivitis, and atopic eczema in 2006 was 7.9%, 6.5%, and 10.1% among children aged 6-7 and 8.4%, 15.5%, and 7.75% among children aged 13-14 yr. University education in this field is provided by the Postgraduate Schools of Pediatrics and those of Allergology and Clinical Immunology, as well as several annual Master courses. The Italian Society of Pediatric Allergology and Immunology (SIAIP) was founded in 1996 and counts about 1000 members. SIAIP promotes evidence-based management of allergic children and disseminates information to patients and their families through a quite innovative website and the National Journal 'Rivista Italiana di Allergologia Pediatrica'. In the last decade, four major regional, inter-regional, and national web-based networks have been created to link pediatric allergy centers and to share their clinical protocols and epidemiologic data. In addition, National Registers of Primary Immune-deficiencies and on Pediatric HIV link all clinical excellence centers. Research projects in the field of pediatric allergy and immunology are founded by the Italian Ministry of Education, University and Research (MIUR) and by the National Research Council (CNR), but the overall investments in this research area are quite low. Only a handful Italian excellence centers participate in European Projects on Pediatric Allergy and Immunology within the 7th Framework Program. The European Academy of Allergy and Clinical Immunology currently hosts two Italians in its Executive Committee (EC) and one in the EC of the Pediatric Section; moreover, major European Academy of Allergy and Clinical Immunology meetings and courses in the area of pediatrics (e.g., PAAM, Venice, 2009) have been held in Italy in the last 3 yr. Italian hallmarks in the management of allergic diseases in childhood are a quite alive and spread interest in Molecular Allergology and a remarkable predominance of sublingual (SLIT) compared to the subcutaneous (SCIT) immunotherapy.

Dendritic cells modification during sublingual immunotherapy in children with allergic symptoms to house dust mites

BACKGROUND

the importance of dendritic cells (DCs) in the initiation of the Th2-mediated inflammatory response to allergens is well known and more recently it has been proposed that DCs have a pivotal role in maintaining tolerance to allergens. The aim of this study was to investigate whether the success of sublingual immunotherapy (SLIT) in allergic asthma is mediated by the induction of changes of DCs functions.

METHODS

ten children with allergic asthma sensitive to house dust mite were studied before and after 12 months of SLIT. Immature DCs were derived from peripheral blood monocytes cultured for 6 days in presence of interleukin (IL)-4 and GM-CSF and stimulated with lipopolysaccharide for the last 24 hours to induce maturation.

RESULTS

after 12 months of SLIT, mature DCs derived from SLIT-treated patients showed a statistically significant defect of CD86 up-regulation, an increase of IL-10, and a reduction of IL-12 production.

CONCLUSION

SLIT induces changes in DCs functions that might be responsible for an impairment of T cell activation or drive T cells towards a regulatory activity, thus restoring immune tolerance to allergens.

Allergen immunotherapy: immunomodulatory treatment for allergic diseases

Allergen immunotherapy is currently the only immune-modifying treatment for allergic disease. At the present time it is indicated for the treatment of allergic rhinitis, asthma and venom hypersensitivity. Efficacy appears to be dose dependent, and the immunological mechanisms responsible for the clinical efficacy of immunotherapy are still being elucidated. Immunological changes associated with immunotherapy include induction of T regulatory cells, increase in allergen-specific immunoglobulin G4, increase in interleukin-10 production and downregulation of the T helper 2 response. The disadvantages of allergen immunotherapy include risk of adverse events and patient time and inconvenience. Risks of immunotherapy range from large local reactions to mild systemic reactions, such as rhinitis. Fatalities from immunotherapy injections have been reported at a rate of approximately one fatality per 2.5 million injections. Conventional subcutaneous immunotherapy build-up schedules involve administration of a single-dose increase each visit and it may take several months before a patient achieves the therapeutic maintenance dose. Accelerated schedules, such as rush and cluster, will allow the patient to achieve the maintenance dose sooner but there may be a greater risk of a systemic reaction. The current focus of immunotherapy research is to develop safer and more effective vaccines. Another approach to enhancing immunotherapy safety is through an alternative delivery method. Sublingual immunotherapy is clearly safer than subcutaneous immunotherapy, but further investigation is needed to determine optimal dose and appropriate patient selection.

Interferon-gamma and IL-10 may protect from allergic polysensitization in children: preliminary evidence

BACKGROUND

A functional defect of T regulatory cells (Treg) has been proposed as pathogenic mechanism of allergic reaction. Polysensitization is a common feature of allergic patients.

AIM OF THE STUDY

It was to investigate the possible role of Treg-Th1 cytokines, in the development of new sensitizations in childhood.

METHODS

Forty monosensitized (MS) children with allergic rhinitis were evaluated and followed-up for 2 years. New sensitizations were investigated. IL-10 and IFN-gamma were evaluated in in vitro experiments.

RESULTS

Children remaining MS showed significant higher production of both IL-10 and IFN-gamma.

CONCLUSION

This preliminary study provided evidence that IL-10 and IFN-gamma production could be defective in allergic children prone to develop polysensitization.

Antigen-specific immunotherapy against allergic rhinitis: the state of the art

Allergic rhinitis is the most prevalent type I allergy in industrialized countries. Pollen scattering from trees or grasses often induces seasonal allergic rhinitis, which is known as pollinosis or hay fever. The causative pollen differs across different areas and times of the year. Impaired performance due to pollinosis and/or medication used for treating pollinosis is considered to be an important reason for the loss of concentration and productivity in the workplace. Antigen-specific immunotherapy is an only available curative treatment against allergic rhinitis. Subcutaneous injection of allergens with or without adjuvant has been commonly used as an immunotherapy; however, recently, sublingual administration has come to be considered a safer and convenient alternative administration route of allergens. In this review, we focus on the safety and protocol of subcutaneous and sublingual immunotherapy against seasonal allergic rhinitis. We also describe an approach to selecting allergens for the vaccine so as to avoid secondary sensitization and adverse events. The biomarkers and therapeutic mechanisms for immunotherapy are not fully understood. We discuss the therapeutic biomarkers that are correlated with the improvement of clinical symptoms brought about by immunotherapy as well as the involvement of Tr1 and regulatory T cells in the therapeutic mechanisms. Finally, we focus on the current immunotherapeutic approach to treating Japanese cedar pollinosis, the most prevalent pollinosis in Japan, including sublingual immunotherapy with standardized extract, a transgenic rice-based edible vaccine, and an immunoregulatory liposome encapsulating recombinant fusion protein.

Lactic acid bacteria as adjuvants for sublingual allergy vaccines

We compared immunomodulatory properties of 11 strains of lactic acid bacteria as well as their capacity to enhance sublingual immunotherapy efficacy in a murine asthma model. Two types of bacterial strains were identified, including: (i) potent inducers of IL-12p70 and IL-10 in dendritic cells, supporting IFN-gamma and IL-10 production in CD4+ T cells such as Lactobacillus helveticus; (ii) pure Th1 inducers such as L. casei. Sublingual administration in ovalbumin-sensitized mice of L. helveticus, but not L. casei, reduced airways hyperresponsiveness, bronchial inflammation and proliferation of specific T cells in cervical lymph nodes. Thus, probiotics acting as a Th1/possibly Treg, but not Th1 adjuvant, potentiate tolerance induction via the sublingual route.

Peripheral Th-17 cells in allergic rhinitis: New evidence

BACKGROUND

Th17 is a subset of T helper lymphocytes exerting inflammatory activities. Recently, it has been reported that serum IL-17 levels are high in patients with severe birch allergy.

AIM OF THE STUDY

It was to compare the cytokine profile and the frequency of peripheral allergen-specific T helper producing IL-17 in patients with allergic rhinitis.

METHODS

Twelve patients with persistent allergic rhinitis due to pollens and 5 healthy non-allergic subjects were evaluated during the pollen season. Th17 were evaluated by intracellular staining in T cell compartment ex-vivo and after short activation by allergens and control antigens.

RESULTS

Ex-vivo PBMNC evaluation showed that allergic patients had higher frequencies of IL-17 producing T cells. Functional analysis after antigen-specific CD4+ T cell expansion demonstrated that allergic patients had higher frequencies of IL-17 producing T cells than normal subjects.

CONCLUSION

This preliminary study contributes to the knowledge concerning the possible role of Th-17 cells in the response to allergens.

Sublingual Immunotherapy Affects Specific Antibody and TGF-β Serum Levels in Patients with Allergic Rhinitis

Allergic rhinitis (AR) is characterized by Th2 polarized immune response, such as increased IL-4 and reduced IFN-γ production. Sublingual allergen-specific immunotherapy (SLIT) induces several immunological changes, most of which are still little known. The aim of this study is firstly to investigate the changes of allergen-specific IgE, IgG, IgG4, and IgA serum levels after SLIT. Secondly, this study aims at relating immunoglobulin (Ig) values with some Th1-, Th2-, and Treg-dependent cytokines. Twenty-three patients with pollen-induced AR were enrolled, and they assumed two pre-seasonal SLIT courses for 2 years. Serum allergen-specific IgE, IgG, IgG4 and IgA levels were determined by ELISA method at baseline and after each SLIT course. Serum IL-4, IFN-γ, IL-10, and TGF-β levels were also assessed. Allergen-specific IgE, IgG, IgG4, and IgA serum levels significantly increased after SLIT. Serum TGF-β significantly increased after SLIT. There was a significant correlation between IgA and TGF-β, both after the first and the second SLIT course. In conclusion, the present study provides the first evidence that pollen SLIT significantly affects Ig production, mainly concerning IgA; and IgA increase is related with TGF-β production. Moreover, this is the first study that measured Ig classes by using a quantitative method.

Quality of life outcomes with sublingual immunotherapy

PURPOSE

Immunotherapy is the titrated exposure of allergens to induce immunologic tolerance and offers long-term immune modification. Traditional subcutaneous immunotherapy (SCIT) has resulted in several deaths and raised safety concerns. Sublingual immunotherapy (SLIT) is an alternative administration route for allergen-specific immunotherapy. Compared to SCIT, SLIT has a shorter escalation phase, equal or greater efficacy for rhinitis, and an improved safety profile. The purpose of this study was to evaluate quality of life measures in a preliminary patient sample initiating SLIT at our institution.

MATERIALS AND METHODS

Patients with appropriate allergen reactivity were given the option to pursue immunotherapy by traditional SCIT or by SLIT techniques. Patients choosing SLIT completed the mini-Rhinoconjunctivitis Quality of Life Questionnaire (m-RQLQ), a 14-item Likert-type questionnaire, at baseline and during maintenance therapy. Patients typically reached maintenance dosing in less than 5 weeks.

RESULTS

Paired m-RQLQ data were available for 15 patients after antigen titration. Initial m-RQLQ results indicate statistically significant (P < .05) improvement on 12 of 14 domains, including impact on regular and recreational activities, sleep, nose rubbing and nose blowing, stuffy nose and runny nose, itchy eyes, sore eyes, watery eyes, thirst, and tiredness. In addition, total m-RQLQ score showed statistically significant improvement (P = .001). No serious adverse events occurred with the initiation of SLIT.

CONCLUSION

These results indicate that SLIT is effective in controlling allergic symptoms and is safe in an introductory patient sample. Double-blind placebo-controlled trials are needed to confirm our preliminary results.

Mechanisms of sublingual immunotherapy

Allergen-specific sublingual immunotherapy is now recognized to be an efficacious and well-tolerated treatment for allergic rhinitis. Emerging treatment strategies are also aimed at the primary treatment of allergic asthma, particularly allergy to house dust mites. Knowledge of the exact mechanisms of action of sublingual immunotherapy is at a basic level, although there appear to be similarities to the immunological changes seen in subcutaneous immunotherapy. An improved understanding should allow the development of more effective treatment programs and widen the potential use of this form of immunotherapy. This review discusses the possible mechanism of action of sublingual immunotherapy, including data from animal and clinical studies, while comparing this with the current understanding of subcutaneous immunotherapy.

Immunoglobulin production pattern is allergen-specific in polysensitized patients

Allergic rhinitis (AR) is characterized by Th2 polarized immune response, such as increased IL-4 and reduced IFN-gamma production, and by a functional defect of T regulatory cells. This impaired immune response profile influences the pattern of immunoglobulin production in allergic patients. Therefore, the aim of this study is firstly to investigate the allergen-specific IgE, IgG, IgG4, and IgA serum level pattern in polysensitized AR patients with the same skin prick test positivity to some pollen allergens. Secondly, this study aims at relating immunoglobulin (Ig) values with some clinical and immunological parameters. Eighty polysensitized patients with AR were enrolled. Serum allergen-specific IgE, IgG, IgG4, and IgA for mites, Parietaria, grasses, and birch, TGF-beta and sHLA-G were determined by the ELISA method. Allergic symptoms and drugs use were also assessed. Allergen-specific IgE, IgG, IgG4, and IgA serum levels were significantly different for each tested allergen (p=0.0001). There was a significant correlation between IgE levels and allergy severity, whereas IgA had an antagonistic behaviour, considering mite-specific immunoglobulins. In conclusion, the present study provides the first evidence that immunoglobulin production pattern depends on the specificity of the allergenic response.

Soluble serum HLA-G and HLA-A, -B, -C molecules in patients with seasonal allergic rhinitis exposed to pollens

BACKGROUND

Allergic rhinitis (AR) is characterized by a Th2 polarized immune response and soluble HLA (sHLA) molecules play an immunomodulatory role in this response. Previously, it has been reported that these molecules are increased in sera of patients with pollen-induced allergic rhinitis studied outside the pollen season. To date, however, no study has investigated there in AR patients during the pollen season.

OBJECTIVE

The aim of this study was to evaluate serum sHLA-G and sHLA-A, -B, -C levels in both AR patients and healthy controls.

METHODS

60 symptomatic allergic patients were enrolled. A group of 50 healthy subjects was included as a control. Serum sHLA-G and sHLA-A, -B, -C levels were determined by an immunoenzymatic method. Allergy severity was assessed by VAS for symptoms and drug use.

RESULTS

Allergic patients had significantly higher levels of both sHLA-G (p<0.001) and sHLA-A, -B, -C (p=0.001) than normal controls. In addition, there was a very strong correlation between sHLA-G levels and clinical severity.

CONCLUSION

The present study confirms evidence that serum sHLA-G and sHLA-A, -B, -C molecules are significantly increased in patients with pollen-induced AR also during the pollen season. Moreover, sHLA-G might be considered as a biomarker for assessing clinical severity.

Sublingual immunotherapy in children: an updated review

Although pharmacological therapy and allergen avoidance are effective means of managing allergic disease, allergen-specific immunotherapy is able to treat not only the symptoms, but also the underlying causes of the disease. Sublingual immunotherapy (SLIT) has been shown to be effective in patients with allergic diseases. It has demonstrated long-term clinical benefits and shown the potential to modify the course of allergic disease in children with rhinitis, conjunctivitis, and asthma. The precise mechanisms of SLIT remain unclear, but antigen-presenting cells in the oral mucosa may induce regulatory T-cells that suppress the allergic immune response by increasing production of interleukin-10. SLIT has also been shown to increase allergen-specific IgG antibodies that antagonize and block the allergic response. SLIT was well tolerated in all reported, double-blinded, placebo-controlled, randomized trials. SLIT is an ideal means of treating the pediatric population because of its excellent safety and good compliance. However, the optimal dose and duration of SLIT require further investigation.

Clinical and Immunological Correlates of Pre-Co-Seasonal Sublingual Immunotherapy with Birch Monomeric Allergoid in Patients with Allergic Rhinoconjunctivitis

Sublingual immunotherapy is safe and efficacious in the treatment of patients with allergic rhinitis. The clinical and biological efficacy of modified allergens (allergoids) has not been fully clarified. We investigated in birch allergic patients the effect of a pre-co-seasonal sublingual immunotherapy regimen with a modified allergen extract on clinical parameters and on T cell proliferation and regulatory cytokine production (IL-10, TGF-beta). We found that during the birch pollen season symptoms and drug usage scores were 30 and 40% improved, respectively, in treated versus control subjects (p<0.0001 for both comparisons) whereas well days were 23.5 (33%) versus 16.9 (23%) (p=0.0024), respectively. Bet v 1 allergen specific proliferation decreased (p = 0.0010), whereas IL-10 transcription increased (p = 0.0010) in treated, but not in control patients. Moreover, TGF-beta transcription was increased, although not significantly (p=0.066), following immunotherapy. Thus, sublingual immunotherapy with modified allergen in birch-allergic subjects was safe, clinically efficacious and associated with the reduction of allergen-specific proliferation and with the increased production of the IL-10 regulatory cytokine.

Long-term comparison of sublingual immunotherapy vs inhaled budesonide in patients with mild persistent asthma due to grass pollen

BACKGROUND

Few studies have compared the effects of immunotherapy and inhaled steroids. The main limitation of such studies is the long duration required to fully appreciate the effects of immunotherapy.

OBJECTIVE

To compare the effects of inhaled budesonide and sublingual immunotherapy (SLIT) in mild persistent asthma for up to 5 years.

METHODS

Patients with mild persistent asthma and rhinitis due to grass pollen were enrolled in an open randomized controlled trial. After a run-in season, they were randomized to either budesonide, 800 microg/d, in the pollen season or continuous grass SLIT for 5 years. All patients received rescue medications. Symptoms were evaluated by diary cards filled out from May to July at baseline and after 3 and 5 years. In-season nasal eosinophils and bronchial hyperresponsiveness were also assessed.

RESULTS

Fifty-one patients were enrolled and 46 completed the study. The bronchial symptom scores and the use of bronchodilators decreased significantly in both groups, but the improvement was greater in the SLIT patients at 3 and 5 years. The nasal symptom score and the intake of nasal steroids decreased only in the SLIT group, and the difference vs the budesonide group was always significant. In the SLIT group vs the budesonide group, a statistically significant decrease of nasal eosinophils was found at 3 and 5 years (P < .01). The bronchial hyperresponsiveness improved significantly only in the SLIT group.

CONCLUSION

In patients with grass pollen-induced asthma, in the long term SLIT was equally effective as inhaled budesonide in treating bronchial symptoms and provided an additional benefit in treating rhinitis symptoms and bronchial hyperresponsiveness.

Sublingual immunotherapy reduces soluble HLA-G and HLA-A,-B,-C serum levels in patients with allergic rhinitis

Allergic rhinitis (AR) is characterized by Th2 polarized immune response. Soluble HLA (sHLA) molecules play an immunomodulatory activity. Specific immunotherapy is the only causal treatment for AR. So far no study investigated the effect of sublingual immunotherapy (SLIT) on sHLA molecules. The aim of the study was to evaluate sHLA-G and sHLA-A,-B,-C serum levels in AR patients with pollen allergy before and after a pre-seasonal course of SLIT. Forty AR patients with pollen allergy were enrolled and they assumed a pre-seasonal SLIT course for 3 months. Serum sHLA-G and sHLA-A,-B,-C and IFN-gamma and IL-4 levels were determined by ELISA method at baseline and 3 months after the end of the SLIT course. Symptoms severity was assessed by a Visual Analogue Scale. Both sHLA-G and sHLA-A,-B,-C levels significantly diminished (p<0.0001 for both) after SLIT. Moreover, there was a highly significant relationship between the serum levels of these two soluble molecules (r=0.84). Significant relationship between symptoms evaluated by VAS and change of sHLA molecules was also evidenced (r=0.60 and 0.63). Serum cytokines were not affected by SLIT. Therefore, this preliminary study provides the first evidence that both sHLA-G and sHLA-A,-B,-C levels are significantly reduced by SLIT in AR patients with pollen allergy. Therefore, the clinical implication of this study is that these soluble molecules might be interpreted as biomarker of response to SLIT.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

In situ analysis of oral DCs was performed by immunohistology. Purified DCs were tested in vitro for their capacity to capture, process, and present the ovalbumin antigen to naive CD4(+) T cells. In vivo priming of ovalbumin-specific T cells adoptively transferred to BALB/c mice was analyzed by cytofluorometry in cervical lymph nodes after sublingual administration of mucoadhesive ovalbumin.

RESULTS

Three subsets of oral DCs with a distinct tissue distribution were identified: (1) a minor subset of CD207(+) Langerhans cells located in the mucosa itself, (2) a major subpopulation of CD11b(+)CD11c(-) and CD11b(+)CD11c(+) myeloid DCs at the mucosal/submucosal interface, and (3) B220(+)120G8(+) plasmacytoid DCs found in submucosal tissues. Purified myeloid and plasmacytoid oral DCs capture and process the antigen efficiently and are programmed to elicit IFN-gamma and/or IL-10 production together with a suppressive function in naive CD4(+) T cells. Targeting the ovalbumin antigen to oral DCs in vivo by using mucoadhesive particles establishes tolerance in the absence of cell depletion through the stimulation of IFN-gamma and IL-10-producing CD4(+) regulatory T cells in cervical lymph nodes.

CONCLUSION

The oral immune system is composed of various subsets of tolerogenic DCs organized in a compartmentalized manner and programmed to induce T(H)1/regulatory T-cell responses.

Early Cytokine Modulation after the Rapid Induction Phase of Sublingual Immunotherapy with Mite Monomeric Allergoids

The influence of different treatment schedules of sublingual immunotherapy (SLIT) in activating IL-10-producing T-cells, crucial in inducing allergen-specific tolerance, is not completely understood. The present work was designed to evaluate allergen driven interleukin release by mononuclear cells in the early phase of SLIT, after application of different induction schemes. Twenty mite-allergic patients were enrolled, 10 (group A) treated with a traditional 98 day induction scheme and 10 (group B) with a 16 day scheme with monomeric allergoid vaccine. At the end of the induction phase, the cumulative doses taken by group A and group B patients were equivalent to 50.5 and 50.3 μg of mite group 1 allergens, respectively. The release of Th1-, Th2- and Treg-related interleukins was assessed in culture supernatants of 5 μg/ml Der-p1-stimulated mononuclear cells, isolated before and after the induction phases. No relevant treatment-related side effects were observed. Interleukin release was similar in the two groups at the enrolment. Non-stimulated and Der p 1 stimulated release of studied cytokines was similar in the two groups at enrolment. Der p 1 stimulation significantly increased IL-10 release (p<0.0002) after treatment in group B patients, and this effect was higher (p=0.05) compared to group A patients. Furthermore, at the end of SLIT induction TNF-alpha, IL-4 and IFN-gamma production were reduced in group B patients (p<0.05, p=0.062 and p=0.060, respectively). The rapid induction scheme of sublingual immunotherapy induces an early immune suppression more effectively than the slower one. The rapid induction scheme should be the preferential way to start sublingual immunotherapy, particularly when monomeric allergoids are utilized.

Soluble HLA-G and HLA-A,-B,-C serum levels in patients with allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is characterized by Th2-polarized immune response. Soluble HLA (sHLA) molecules play an immunomodulatory activity. So far, however, no study investigated them in AR.

OBJECTIVE

The aim of this study was to evaluate sHLA-G and sHLA-A,-B,-C serum levels in AR patients with pollen allergy and in a group of healthy controls.

METHODS

Forty-nine AR patients were enrolled. A group of healthy nonallergic subjects was considered as control. sHLA-G and sHLA-A,-B,-C serum levels were determined by immunoenzymatic method. The study was conducted during the winter, such as outside the pollen season.

RESULTS

Allergic patients had significantly higher levels of both sHLA-G (P < 0.0001) and sHLA-A,-B,-C (P = 0.011) molecules than normal controls. Moreover, there was a significant relationship between these two soluble molecules (r = 0.69) in allergic patients.

CONCLUSION

The present study provides the first evidence that both sHLA-G and sHLA-A,-B,-C serum levels are significantly increased in AR patients with pollen allergy.