Dose dependence of immunological response to sublingual immunotherapy

Exploring Side Effects of Sublingual Immunotherapy: A Systemic Review and Meta-Analysis

Objective: Sublingual immunotherapy (SLIT) has emerged as a potentially safe and convenient option for allergen immunotherapy for patients with inhalant allergy. Larger studies on the overall side effects and severe reactions anaphylaxis are still lacking. Study Design: Systematic review and meta-analysis. Setting: Author's review was completed in the University of Texas Medical Branch. Methods: A systematic review and meta-analysis of prospective clinical trials focusing on SLIT safety published from January 1, 2001, to December 31, 2021, was conducted. Results: Twenty-six studies were included with analysis of 7827 patients, representing over 2.7 million SLIT doses. All studies focused on single-antigen immunotherapy. The mean duration of treatment was 11.54 months. Local side effects were present in 40.83% of patients [95% confidence interval (CI) 24.78-57.96]. Systemic side effects were encountered in 1.09% of SLIT patients (95% CI 0.57-1.78). Anaphylaxis was reported in 0.13% of patients (95% CI 0.06-0.22). Discontinuation rates due to side effects were low, at 4.32% of patients (95% CI 3.28-5.49). Conclusion: This meta-analysis shows that single-antigen SLIT is well-tolerated, with overall low rates of systemic side effects including anaphylaxis. Although there is a high rate of minor local side effect, the treatment attrition during the first year is low. With growing allergy burden worldwide, SLIT is a convenient and economically feasible option for immunotherapy. Further work is needed to evaluate long-term safety and efficacy of single as well as multi-antigen SLIT, including quality of life assessments.

Use of Sublingual Immunotherapy for Aeroallergens in Children with Asthma

Asthma is a heterogeneous disease that in children is often allergen-driven with a type 2 inflammation. Sublingual immunotherapy represents an important progress in the use of personalized medicine in children with allergic asthma. It is a viable option for house dust mite-driven asthma and in subjects with the asthma associated with allergic rhinitis. The use and indications for isolated asthma caused by other allergens are still controversial owing to heterogeneity of commercially available products and methodological limitations of studies in children. Nevertheless, most studies and meta-analyses found the efficacy of sublingual immunotherapy. Sublingual immunotherapy is safe but cannot be recommended in children with uncontrolled asthma.

DC-targeted gold nanoparticles as an efficient and biocompatible carrier for modulating allergic responses in sublingual immunotherapy

BACKGROUND

Sublingual immunotherapy (SLIT) was introduced to deliver allergens in an effective and non-invasive route, which can be considered as an alternative for allergen-specific subcutaneous immunotherapy (SCIT). On the other hand, the use of gold nanoparticles (AuNPs) in allergen delivery has beneficial effects on sublingual immunotherapy. In addition, the molecular targeting agents like aptamers (Apt), have been widely applied for targeted drug delivery. Therefore, the current study aimed to evaluate the effects of dendritic cells (DCs)-specific Aptamer-modified AuNPs coated with ovalbumin (OVA) on the improvement of the SLIT outcome in the mouse model of allergy.

MATERIAL AND METHODS

AuNPs with approximately 15 nm diameter were prepared by citrate reduction of HAuCl4. Afterward, Apt-modified AuNP complex was prepared and OVA was then loaded onto this complex. Following sensitization of Balb/c mice to OVA, SLIT was performed with Apt-AuNPs containing 5 µg OVA twice a week for a 2-month period. Allergen-specific IgE in serum, as well as cytokines secretion of spleen cells, were analyzed using ELISA. Also, nasopharyngeal lavage Fluid (NALF) was collected for total and eosinophil counts. Moreover, the lungs were removed for histopathological examination.

RESULTS

SLIT with Apt-modified AuNPs complex containing 5 μg OVA, decreased the IgE levels compared to the other groups. Also, IL-4 production has significantly decreased in spleen cells, while TGF-β and IFN-γ have significantly increased. The assessment of NALF in the group treated by this complex showed a decrease in total cell as well as in eosinophil count. Also, the examination of lung tissues revealed that, in the group treated by this complex, inflammation and perivascular infiltration were lesser than the other groups, which were observed in only one vessel of tissue.

CONCLUSION

It was shown that, Sublingual immunotherapy with DC specific Apt-modified AuNPs containing 5 μg OVA can improve the Th1 and Treg immunomodulatory responses.

Enhanced efficacy of sublingual immunotherapy by liposome-mediated delivery of allergen

Immunotherapy by sublingual administration of allergens provides high patient compliance and has emerged as an alternative to subcutaneous immunotherapy for the treatment of IgE-associated allergic diseases. However, sublingual immunotherapy (SLIT) can cause adverse events. Development of allergen delivery systems enabling more efficient delivery and hence lower allergen load might reduce the adverse events. In the present study, we have investigated neutral and cationic liposomes as delivery systems of ovalbumin (OVA), as a model allergen, in an OVA-induced allergic airway inflammation model. We investigated the liposome carriers' ability to improve tolerance induction of antigens compared to the corresponding dose of free OVA. Mice were treated sublingually over 2 weeks with free or liposome encapsulated OVA followed by intraperitoneal injections and intranasal challenge. Mice sublingually treated with OVA-liposomes showed a significant reduction of airway eosinophilia and splenocyte proliferation in comparison to free OVA. A similar nonsignificant pattern was seen for OVA-specific IgE antibodies. In addition, reduced levels of interferon-γ and interleukin-5 were observed in spleen cell culture supernatants from OVA-liposome-treated mice compared to the sham-treated group. In conclusion, in vivo efficacy data showed that prophylactic SLIT with OVA-liposomes is significantly more effective in preventing allergic inflammation than the corresponding dose of free OVA.

Allergen specific sublingual immunotherapy in children with asthma and allergic rhinitis

BACKGROUND

The incidence of asthma and allergic rhinitis (AR) is significantly increased, especially in younger children. Current treatment for children with asthma and allergic rhinitis include allergen avoidance, standard pharmacotherapy, and immunotherapy. Since standard pharmacotherapy is prescribed for symptoms, immunotherapy at present plays an important role in the treatment of allergic diseases. This article presents insights into the up-to-date understanding of immunotherapy in the treatment of children with allergic rhinitis and asthma.

DATA SOURCES

PubMed articles published from 1990 to 2014 were reviewed using the MeSH terms "asthma", "allergic rhinitis", "children", and "immune therapy". Additional articles were identified by hand searching of the references in the initial search.

RESULTS

Numerous studies have shown that sublingual application of allergen specific immunotherapy (SLIT) is an adequate, safe and efficient substitution to subcutaneous route of allergens administration (SCIT) in the treatment of IgE-mediated respiratory tract allergies in children. According to the literature, better clinical efficacy is connected with the duration of treatment and mono sensitized patients.

CONCLUSIONS

At least 3 years of treatment and stable asthma before the immunotherapy are positive predictors of good clinical efficacy and tolerability of SLIT. SLIT reduces the symptoms of allergic diseases and the use of medicaments, and improves the quality of life of children with the diseases.

The safety of self-administered allergen immunotherapy during the buildup and maintenance phases

BACKGROUND

Self-administered allergen immunotherapy is considered controversial. We believe the implementation of a self-administration protocol characterized by patient preselection and a slow buildup phase is safe.

METHODS

We analyzed 23,614 patient records and associated immunotherapy injections for systemic reactions (SR) during a 1-year period (2011 to 2012). SRs were graded in accordance with the World Allergy Organization (WAO) criteria.

RESULTS

Thirty-seven SRs were reported for 23,614 patients who self-administered 2,021,600 injections yielding an annual SR rate of 0.16% (per patient) or 0.002% (per injection). Only 9 of 4643 pediatric (0.19%) and 28 of 18,971 adult patients (0.15%) experienced 1 or more SRs. No deaths (grade V SR) occurred. From 2009 through early 2014, over 90,000 patients received more than 10 million injections in accordance with the United Allergy Services (UAS) protocol without fatalities.

CONCLUSION

We believe this safety profile is due to a preselection of patients to exclude those with a high risk for adverse reactions and a slow immunotherapy buildup phase. In contrast, previous studies documented office-based SRs ranging from approximately 3% to greater than 14%. Thus, the UAS home-immunotherapy SR rate is significantly lower than office-based immunotherapy SR rates (p < 0.0001). The enhanced safety of this protocol results in a decreased frequency and severity of SRs. This safety report, derived from analyses of one of the largest patient cohorts studied, corroborates and expands the observations of previous studies of self-administered subcutaneous immunotherapy in a low-risk patient population by assessing self-administered allergen immunotherapy during the buildup and maintenance phases.

Sublingual immunotherapy in preschool children: an update

Allergen immunotherapy is a subject widely debated by allergists. Currently, there are controversial discussions focused on the sublingual route. Sublingual immunotherapy (SLIT) has so far been used in Europe, Asia and Australia for the treatment of allergic respiratory diseases. The minimum age to start specific immunotherapy with inhalant allergens in children has not been clearly established, and position papers discourage its use in children younger than 5 years of age. Nevertheless, it is known that SLIT efficacy is higher when SLIT is started at an earlier age. The aim of this review is to focus on studies in preschool children evaluating SLIT safety and efficacy, in order to improve this practice at an earlier age in childhood.

Fast onset of action of sublingual immunotherapy in house dust mite-induced allergic rhinitis: a multicenter, randomized, double-blind, placebo-controlled trial

OBJECTIVES/HYPOTHESIS

To investigate how quickly an allergic rhinitis (AR) patients' symptoms will improve with sublingual immunotherapy (SLIT).

STUDY DESIGN

Double-blind placebo study.

METHODS

This is a multicenter, randomized, double-blind, placebo-controlled study of SLIT used to treat house dust mite-induced AR. A total of 120 AR patients, aged 4 to 60 years, were treated for 6 months and randomized into two groups: 1) SLIT with Dermatophagoides pteronyssinus (D.p.) and Dermatophagoides farina (D.f.) extract (n = 60) ; and 2) matched placebo controls (n = 60). Symptom, medications received, and a visual analog scale score were recorded during the whole study. Serum-specific IgE and IgG4 to D. p. and D. f. were assessed before and after the treatment.

RESULTS

Eighty-five patients (70.8%) completed the study. Twelve patients (20%) chose to withdraw from the SLIT group, but none because of serious adverse effects. The total symptom and visual analog scores VAS in the SLIT group decreased significantly when compared to the placebo controls (P <0.05) after week 14, as well as for the significant (P <0.05) improvement of all individual AR symptoms in the SLIT group (e.g., sneezing, nasal discharge, itching, and nasal obstruction) after week 22. There was a significant (P <0.05) increase of IgG4 to both D.f. and D.p. in the SLIT, but not in the placebo group after treatment.

CONCLUSION

SLIT with a mixture of D.f. and D.p. extract is an effective and safe treatment for patients with house dust mite-induced AR. Its onset of action can be observed as early as 14 weeks after treatment.

Requirements for acquiring a high-quality house dust mite extract for allergen immunotherapy

The house dust mite is a major cause of respiratory allergy worldwide. The management of mite allergy is based on avoidance measures, drug treatment, and allergen immunotherapy, but only allergen immunotherapy is able to modify the natural history of the disease. Injectable subcutaneous immunotherapy was introduced a century ago, while sublingual immunotherapy was proposed in the 1980s and emerged in the ensuing years as an effective and safe option to subcutaneous immunotherapy. However, the quality of the extracts to be used in allergen immunotherapy is crucial for the success of treatment. The mite extract for sublingual immunotherapy known as Staloral 300 was developed to offer optimal characteristics concerning the mite culture medium, standardization, and allergen dose. Double-blind, placebo-controlled trials with Staloral 300 have provided a substantial part of the clinical evidence analyzed in a meta-analysis of the efficacy of allergen immunotherapy in mite-induced rhinitis and asthma. Safety and tolerability are very good, mild local reactions in the mouth being the most common side effect. This makes it feasible to carry out sublingual immunotherapy for the 3–5-year duration needed to achieve long-lasting tolerance to the specific allergen. The performance of Staloral 300 may provide optimal conditions for an effective and safe sublingual immunotherapy in patients with mite-induced respiratory allergy.

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.

Immunological mechanisms of sublingual allergen-specific immunotherapy

Within the last 100 years of allergen-specific immunotherapy, many clinical and scientific efforts have been made to establish alternative noninvasive allergen application strategies. Thus, intra-oral allergen delivery to the sublingual mucosa has been proven to be safe and effective. As a consequence, to date, sublingual immunotherapy (SLIT) is widely accepted by most allergists as an alternative to conventional subcutaneous immunotherapy. Although immunological mechanisms remain to be elucidated in detail, several studies in mice and humans within recent years provided deeper insights into local as well as systemic immunological features in response to SLIT. First of all, it was shown that the target organ, the oral mucosa, harbours a sophisticated immunological network as an important prerequisite for SLIT, which contains among other cells, local antigen-presenting cells (APC), such as dendritic cells (DCs), with a constitutive disposition to enforce tolerogenic mechanisms. Further on, basic research on local DCs within the oral mucosa gave rise to possible alternative strategies to deliver the allergens to other mucosal regions than sublingual tissue, such as the vestibulum oris. Moreover, characterization of oral DCs led to the identification of target structures for both allergens as well as adjuvants, which could be applied during SLIT. Altogether, SLIT came a long way since its very beginning in the last century and some, but not all questions about SLIT could be answered so far. However, recent research efforts as well as clinical approaches paved the way for another exciting 100 years of SLIT.

Clinical practice: Allergen-specific immunotherapy in children: facts and FAQs

Allergen-specific immunotherapy (SIT) in its various application forms represents the main treatment approach of IgE-mediated allergic diseases in adults and children. Despite this clear recommendation, many particularities of products, patient characteristics, and product availability in different countries hamper the use of allergen-specific immunotherapy in particular in children. The frequently asked questions by parents, patients, and physicians are the backbone of this review. Thus, the potentials and limitations of allergen-specific immunotherapy in children and adolescents will be highlighted. IgE-mediated allergic diseases are affecting about 20% of the population. They manifest commonly early in life, and hence, the use of SIT should be considered also early in the course of the disease.

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.

Development of a sublingual allergy vaccine for grass pollinosis

Grass pollen is a very common cause of allergic rhinitis and asthma. The only treatment targeting the underlying causes of allergy is immunotherapy (IT). Sublingual immunotherapy (SLIT) has been introduced to solve the problem of systemic reactions to subcutaneous IT (SCIT). This article evaluates the characteristics of the allergen extract, Staloral, in terms of practical administration, effectiveness, safety, and mechanism of action. Efficacy data were obtained from double-blind, placebo-controlled studies using Staloral in patients sensitized to grass pollen, while practical administration, cost-effectiveness, and mechanism of action data were provided by well designed studies. The efficacy and safety of Staloral, as demonstrated by review of published studies which used doses up to 1125 times those administered with SCIT, shows that this allergen extract has optimal characteristics for treating patients with seasonal allergies due to grass pollens. The main mechanism of action is the interaction between dendritic cells of the oral mucosa and the subsequent tolerance induced in T-cells.

Development of an allergen extract for sublingual immunotherapy--evaluation of Staloral

BACKGROUND

Specific immunotherapy (IT) is an effective treatment for rhinitis and asthma caused by aeroallergens sensitization. Sublingual IT (SLIT) was introduced to solve the problem of systemic reactions to subcutaneous IT (SCIT) and developed to represent an actual treatment option. It is now generally accepted that allergen doses much higher than those administered by SCIT must be used to achieve clinical efficacy on allergic symptoms.

OBJECTIVE

To evaluate the characteristics of Staloral, an allergen extract produced by Stallergenes (Antony, France) in terms of practical administration, efficacy, safety and mechanism of action.

METHODS

Data were obtained from 20 double-blind, placebo-controlled studies using Staloral in patients sensitized to pollens and house-dust mites, and also from open studies concerning practical administration and the mechanism of action.

RESULTS/CONCLUSION

Efficacy and safety of Staloral, as demonstrated by the revision of the studies, which used doses up to 1125 times those administered with SCIT, are very satisfactory and confer to this allergen extract optimal characteristics for treating patients with seasonal allergies due to pollens or with perennial symptoms induced by dust mites. The main mechanism of action is the interaction with dendritic cells of the oral mucosa and the subsequent tolerance induced in T cells.

[Allergen-specific Immunotherapy for children and adolescents - a review on available products in Austria]

A pediatric consensus report on allergen-specific immunotherapy for children and adolescents is presented for Austria. Products on the market in Austria are presented and categorised according to studies performed on the target population of children and adolescents, their effectiveness and indication. In general, more clinical studies on children and adolescents are mandatory for most of the available allergen-specific immunotherapeutics. In addition, the use of allergen-specific immunotherapy in general should be promoted as the exclusive treatment with long-lasting effects in type I allergies in particular in children.

Sublingual immunotherapy in children: facts and needs

Allergen specific immunotherapy (SIT) is the practice of administering gradually increasing doses of the specific causative allergen to reduce the clinical reactivity of allergic subjects, and is the only treatment targeting the causes of hypersensitivity and not only the symptoms, as done by drugs. The traditional, subcutaneous immunotherapy (SCIT) was burdened by the problem of systemic reactions which may be sometimes severe and - though very rarely - even fatal. This was the background to develop non injections routes for SIT and particularly sublingual immunotherapy (SLIT), that emerged as a real treatment option for respiratory allergy.

A number of studies was conducted to evaluate efficacy and safety of SLIT, the first meta-analysis - including 22 placebo-controlled trials - concluded for positive results in both issues, but the number of studies on children was too low to draw definite conclusions. Since then, many other studies became available and make possible to analyze SLIT in children in its well defined aspects as well as in sides still requiring more solid data.

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.

House dust mite sublingual immunotherapy: the role for transforming growth factor-beta and functional regulatory T cells

RATIONALE

Sublingual allergen-specific immunotherapy is gaining popularity for treatment of allergic diseases, but underlying immunological mechanisms are unresolved.

OBJECTIVES

To perform detailed immunological investigation of sublingual house dust mite (HDM) immunotherapy.

METHODS

A 12-month randomized double-blind placebo-controlled study of sublingual HDM immunotherapy in 30 HDM-allergic subjects was performed, with 1-year open extension in 9 patients on active treatment. HDM-stimulated blood mononuclear cells were analyzed for proliferation, cytokines, and regulatory T cells (Tregs) by flow cytometry and ELISA. Effects of blocking transforming growth factor (TGF)-beta and IL-10 on proliferation were determined. Treg suppressor function and allergen-specific antibody levels were measured. Clinical efficacy was assessed by symptom, medication, and Juniper quality-of-life scores.

MEASUREMENTS AND MAIN RESULTS

Allergen-induced CD4(+) T-cell division and IL-5 production were significantly decreased after 6- and 12-months' active treatment but not placebo. sTGF-betaRII blocked immunotherapy-induced suppression of allergen-specific T-cell proliferation, maximal at 6 months. Decreased allergen-specific CD4(+) T-cell proliferation and increased IL-10 secretion and serum Der p 2-specific IgG(4) were maximal at 24 months' active treatment. Treg (CD4(+)CD25(+)CD127(lo)/Foxp3(+)) function was demonstrated by suppression of allergen-specific effector T-cell (CD4(+)CD25(-)CD127(hi)) proliferation and cytokine production. Clinical efficacy of immunotherapy was supported by significantly decreased rhinitis symptom score, total asthma score, and Juniper quality-of-life score.

CONCLUSIONS

This study establishes the novel finding that TGF-beta mediates the immunological suppression seen early in clinically effective sublingual HDM immunotherapy in addition to an increase in Tregs with suppressor function. Clinical trial registered with www.clinicaltrials.gov (NCT00250263).

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.

Sublingual immunotherapy and allergic rhinitis

This paper reviews the safety and efficacy of sublingual immunotherapy (SLIT) in the treatment of allergic rhinitis. The literature from 1986 through 2007 shows approximately a 6000-fold range in doses found to be effective with SLIT. However, recent studies in large patient populations have demonstrated a clear dose response with an effective dose range that appears to be equivalent to one to two times the monthly subcutaneous immunotherapy dose administered daily or weekly (ie, 15 to 30 microg of major allergen). Further study is needed to establish the optimal dose and dosing schedule for each formulation. Local reactions (eg, oral itchiness) are common, and serious adverse reactions, although rare, have been reported. Cost-effective analysis cannot be made until the effective dose is established. SLIT appears to be a promising treatment for allergic rhinitis, but it is currently considered investigational in the United States until a formulation approved by the US Food and Drug Administration is available.

Efficacy and safety of specific immunotherapy with a high-dose sublingual grass pollen preparation: a double-blind, placebo-controlled trial

BACKGROUND

Sublingual immunotherapy (SLIT) is increasingly being used for the treatment of allergic rhinitis, but there are conflicting study results demonstrating clinically relevant efficacy.

OBJECTIVE

To show clinical efficacy and safety of a new high-dose grass pollen preparation for SLIT.

METHODS

In a 2-year, double-blind, placebo-controlled trial, 185 subjects with rhinitis or rhinoconjunctivitis, with or without asthma, were treated with a recently developed, high-dose, 6-grass pollen mixture for SLIT once daily.

RESULTS

The primary end point, a combined symptom-medication score, showed almost no change in the placebo group during a 42-day evaluation period in the grass pollen season from 2003 to 2005, whereas active treatment was associated with a significant and clinically relevant improvement (full analysis set, P = .01; main data set, P = .002). The effect was irrespective of asthma diagnosis. Allergen-specific IgE showed no difference in both groups, and specific IgG4 and IgG1 increased with active treatment in the first and second study years compared with placebo, clearly indicating the immunogenic effect of the active treatment. The SLIT was well tolerated. No serious adverse drug reactions occurred.

CONCLUSIONS

High-dose, sublingual, specific immunotherapy with an extract of a 6-grass pollen mixture showed a significant and clinically relevant improvement in subjects with grass pollen-associated rhinitis or rhinoconjunctivitis, with or without asthma. The treatment with the sublingual solution was well tolerated.

The immune privilege of the oral mucosa

Despite high bacterial colonization and frequent allergen contact, acute inflammatory and allergic reactions are rarely seen in the oral mucosa. Therefore we assert that immune tolerance predominates at this site and antigen presenting cells, such as dendritic cells and different T cell subtypes, serve as key players in oral mucosal tolerance induction. In this article we describe the mechanisms that lead to tolerance induced in the oral mucosa and how they differ from tolerance induced in the lower gastrointestinal tract. Furthermore we discuss ways in which novel nonparenteral approaches for immune intervention, such as allergen-specific immunotherapy applied by way of the sublingual route, might be improved to target the tolerogenic properties of the sophisticated oral mucosal immune network.

Immunotherapy: clinical trials--optimal trial and clinical outcomes

PURPOSE OF REVIEW

The methodology of randomized clinical trials is essential to assess and register treatment interventions. Although specific immunotherapy was introduced a century ago, very few trials meet the criteria for pivotal studies. The paper reviews the methods which should be used to investigate specific immunotherapy.

RECENT FINDINGS

Large pivotal trials on specific immunotherapy were published within the last year and made sublingual immunotherapy an accepted treatment in Europe. Moreover, a study proposed the guidelines for conducting trials on immunotherapy. Phase I studies were also published on sublingual immunotherapy. A large trial on subcutaneous immunotherapy confirmed its efficacy, but showed that this form of treatment is associated with side effects.

SUMMARY

The clinical efficacy of subcutaneous and sublingual immunotherapy with pollen and mites is well established for both rhinitis and asthma, but the methodology of many specific immunotherapy trials was found to be insufficient until recent large pivotal studies. The present paper reviews the requirements for conducting trials in allergen-specific immunotherapy including allergen standardization, patient inclusion and exclusion criteria, phase I trials to assess safety, dose-ranging studies, and pivotal trials. These need to be randomized, parallel group, placebo-controlled designs. The number of patients should be sufficient. Primary and secondary outcome measures are listed. Trials for asthma need specific requirements. In all trials, safety should be carefully monitored. Studies in children are required.

Sublingual immunotherapy in pediatric allergic rhinitis and asthma: efficacy, safety, and practical considerations

Specific allergen immunotherapy (SIT) is the only disease-modifying treatment for allergic rhinitis and asthma. Subcutaneous immunotherapy (SCIT) is the only method with a US Food and Drug Administration (FDA)-approved formulation, but safety concerns limit administration to medical facilities. Sublingual immunotherapy (SLIT), under investigation in the United States, appears to have a more favorable safety profile, which may expand its use to populations generally not treated with SIT (eg, young children). This paper reviews SLIT studies that were specifically limited to the pediatric population. Most demonstrated evidence of clinical efficacy, but approximately 29% failed to demonstrate efficacy in symptom and medication scores in the first treatment year. Efficacy was seen in a broad range of allergen doses, but optimal dose range has not been established. SLIT appeared to be well tolerated in children as young as 2 years, but serious adverse reactions, including anaphylaxis, were reported. SLIT is a promising immunotherapy that may expand the population receiving SIT because of the convenience of home administration due to its favorable safety profile. However, questions remain unanswered, including optimal therapeutic dose.

Long-term allergen-specific immunotherapy correlates with long-term allergen-specific immunological tolerance

INTRODUCTION

One method of treatment for allergic diseases is allergen-specific immunotherapy (SIT). The clinical efficacy of SIT in pollen-induced allergic rhinitis has been demonstrated in several controlled clinical trials. There is no consensus about the protective effect of SIT. In this study, we evaluated the correlation between the duration of SIT and relapse of allergic rhinoconjunctivitis.

METHODS

We evaluated 148 patients who had received SIT between 1998 and 2006. All of the patients had allergic rhinoconjunctivitis. According to the data 116 had sensitivity to grass pollen and 32 to house dust. SIT was performed on 87 patients for 4 y (Group A) and 61 patients for 6 y (Group B).

RESULTS

All of the 148 patients were monitored regularly with no medication for 2 y after SIT. Thirty-one patients in Group A relapsed (36%); 11 patients in Group B relapsed (18%). Mean duration until relapse was 11.1+/-1.99 mo in Group A and 19.64+/-1.86 mo in Group B. During evaluation, symptom scores were 2.32+/-0.74 in Group A and 1.81+/-0.75 in Group B and serum total immunoglobulin E levels were 432.4+/-78.5 KU/lt in Group A and 288.6+/-55.3 KU/lt in Group B. There was significant difference between the groups (P < 0.05).

CONCLUSION

According to these results, long-term SIT therapy correlates with long-term, allergen-specific, acquired immunological tolerance.

Allergen immunotherapy: where is it now?

The scientific basis and the proof of clinical effectiveness of allergen immunotherapy administered by subcutaneous injection (SCIT) are well established. It is effective treatment for sensitivity to Hymenoptera venom and for allergic rhinitis and allergic asthma. SCIT administered in the proper setting reduces the development of new sensitivities and progression from rhinitis to asthma. Further, the beneficial effects persist long after completion of a course of treatment. Although many people enjoy the benefits of SCIT, extension of its use to the many others who might be candidates for this treatment is limited by its drawbacks of safety concerns and the inconvenience of repeated clinic visits over several years to receive the injections. There are many attempts underway to improve on the safety and convenience while still retaining the benefits of SCIT. These include approaches using current allergen extracts, especially by administering them sublingually. Alternatively, through recombinant technology, extracts are being modified to reduce their allergenicity without reducing their immunogenicity. They are being linked to immunostimulatory DNA sequences that will modify their in vivo processing resulting in an enhanced nonallergic response or they are being incorporated into fusion proteins with inhibitory properties for mast cells and basophils.

Multiple daily administrations of low-dose sublingual immunotherapy in allergic rhinoconjunctivitis

BACKGROUND

Sublingual immunotherapy (SLIT) is an efficacious treatment for allergic rhinoconjunctivitis.

OBJECTIVE

To investigate whether the number of daily administrations of SLIT can affect its efficacy.

METHODS

In an open study, 64 patients with allergic seasonal rhinoconjunctivitis to grass or birch pollens were assigned to the following 2-year daily treatment schedules: "3-3" group, 1 drop 3 times daily for 2 years; "2-3" group, 1 drop twice daily in year 1 and 1 drop 3 times daily in year 2; "1-3" group, 1 drop once daily in year 1 and 1 drop 3 times daily in year 2; and control group, no treatment. One fifth of the allergen concentration recommended by the manufacturer as maintenance treatment was used throughout the study. Patients were monitored for skin reactivity to the allergen used for SLIT using an end point dilution technique and for drug use.

RESULTS

No treatment-related adverse effects were observed. Skin reactivity to allergen decreased compared with controls in the first treatment year only in the "3-3" group and in all treated patients in year 2. Drug use decreased in the first treatment year in the "3-3" and "2-3" groups vs controls. This outcome extended to "1-3" patients in treatment year 2. Antihistamine use decreased significantly compared with baseline in year 1 in "3-3" and "2-3" patients and in all treated patients in year 2. No changes were observed in controls.

CONCLUSION

The number of daily administrations seems to correlate with the efficacy of SLIT.

Germinal-centre reactions in allergic inflammation

Primary and secondary immune responses in the germinal centres of lymphoid organs have been studied in the past. There is now compelling evidence of a third stage in the immune response, in 'tertiary lymphoid organs' that develop at sites of chronic inflammation in response to persistent local antigen challenge. Germinal-centre-like reactions are well-documented in the target organs of autoimmune diseases. Here, we review recent evidence that they also occur at sites of allergic inflammation.

Targeting dendritic cells in allergen immunotherapy

Allergen immunotherapy is a well-established strategy for treating allergic diseases with the goal of inducing allergen-specific tolerance. Identified mechanisms contributing to the therapeutic effect of immunotherapy include a shift of T helper 2 (Th2)-type immune responses to a modified Th2 immune response, a change of the balance of IgE-producing B cells to the production of IgG subtypes, in addition to increased IL-10 and TGF-beta secretion and activation of the suppressive functions of regulatory T-cells. Dendritic cells (DCs), which as outposts of the immune system are capable of T-cell priming through efficient allergen uptake by IgE receptors expressed on their cell surface. Most of the hypotheses concerning the function of DCs as facilitators of allergen-specific tolerance in allergen immunotherapy remain speculative. Therefore, studies must focus on the functional changes of DCs under immunotherapy to close the gap of knowledge about their exact role. These experimental data should help confirm the hypothesis of DCs as efficient silencers and potential target cells and take advantage of the bivalent character and tolerogenic properties of DCs.

Sublingual immunotherapy: a comprehensive review

Sublingual immunotherapy (SLIT) has been used with increasing frequency in Europe and is viewed with increasing interest by allergists in the United States. To address this interest, a Joint Task Force of the American College of Allergy, Asthma and Immunology and the American Academy of Allergy, Asthma and Immunology's Immunotherapy and Allergy Diagnostic Committees reviewed the available literature on SLIT and prepared this report. The task force concluded that despite clear evidence that SLIT is an effective treatment, many questions remained unanswered, including effective dose, treatment schedules, and overall duration of treatment. Until these have been determined, an assessment of the cost/benefit ratio of the treatment cannot be made. SLIT does appear to be associated with few serious side effects, but it has not been administered in high-risk asthmatic patients, nor in the studies reviewed has it been administered as a mixture of non-cross-reacting allergens. Furthermore, there is currently no allergy extract approved for this use in the United States, nor is there a Current Procedural Terminology code for billing purposes. All of these factors should be given careful consideration by anyone contemplating initiating SLIT treatment for their allergic patients.

Sublingual immunotherapy for allergic rhinitis: an update

PURPOSE OF REVIEW

The inter-relationship between allergy and nasal diseases has long been known. Failure to address when allergy is a contributing factor diminishes the possibility of a successful surgical intervention. Sublingual immunotherapy is recommended by the World Health Organization to treat allergic rhinitis and is widely used in Europe. Many clinical trials and rigorous meta-analysis support its efficacy. The criteria, however, for the integration of this treatment (with the surgical management of those allergic patients who suffer chronic nasal obstruction, severe drug-resistant hypertrophy and increase in glandular structures of the inferior turbinates) are not fully established. We review here the most recent literature on the efficacy and safety of sublingual immunotherapy. The purpose is to stimulate the use of complementary approaches by ear, nose and throat doctors and allergologists, and to improve the management of patients with persistent allergic rhinitis.

RECENT FINDINGS

In addition to the results of clinical trials, postmarketing surveillance has confirmed the high safety profile of sublingual immunotherapy in adults and children, its positive impact on the quality of life, and the reduction of the personal and social cost of allergy. Sublingual immunotherapy can prevent new allergic sensitizations and maintain its beneficial effect for years after its discontinuation.

SUMMARY

Sublingual immunotherapy is a highly efficacious and well tolerated form of immunotherapy for allergic rhinitis, and it is capable of interfering with disease progression. Sublingual immunotherapy should be integrated with surgical intervention to achieve optimal outcomes in allergic subjects with chronic nasal obstruction.

Absence of systemic immunologic changes during dose build-up phase and early maintenance period in effective specific sublingual immunotherapy in children

BACKGROUND

Sublingual immunotherapy (SLIT) has been reported to be a safe treatment for inhalant allergies in children. Yet the immunologic mechanisms resulting in clinical improvement are poorly understood.

OBJECTIVE

To identify early systemic immunologic changes during the first 8 weeks of clinically effective SLIT to grass pollen, tree pollen or house dust mite in paediatric patients with allergic rhinoconjunctivitis and/or asthma.

METHODS

Peripheral blood mononuclear cells and plasma samples of 13 children with reduced symptoms after 1 year of SLIT were obtained before therapy and at 2 and 8 weeks after the initiation of SLIT. Allergen-specific lymphocyte proliferation assays were performed, and allergen-induced cytokine production (IL-2, IL-4, IL-10, IFN-gamma, and TGF-beta(1)) was measured by ELISA and flow cytometry. Allergen-specific IgE, IgG1, IgG4, and IgA levels in plasma samples were determined in ELISA.

RESULTS

During the first 8 weeks of successful SLIT, allergen-specific lymphoproliferation (n=13) as well as levels of allergen-specific intracellular (n=8) and secreted cytokines (n=9) did not change significantly. In addition, no alterations in levels of allergen-specific Igs (n=7) were observed.

CONCLUSION

We could not find any early systemic immunologic changes during the first 8 weeks of clinically effective SLIT to inhalant allergens in paediatric patients with allergic rhinoconjunctivitis and/or asthma.