Long-term clinical and immunological effects of allergen immunotherapy

The long-term efficacy of intra-cervical lymphatic immunotherapy on adults with allergic rhinitis: A randomized controlled study

BACKGROUND

The efficacy and safety of the novel immunotherapy method, intra-cervical lymphatic immunotherapy (ICLIT), need to be investigated. Comparing it with subcutaneous immunotherapy (SCIT), we clarified the long-term efficacy and safety of intra-cervical lymphatic immunotherapy on allergic rhinitis (AR), and investigated the improvement of clinical efficacy of the booster injection at 1 year after ICLIT treatment.

METHODS

Ninety adult patients with dust mite allergy were randomly divided into 3 groups: 30 in the SCIT group, 30 in the ILCLIT group, and 30 in ICLIT booster group. Changes in total symptom score (TSS), nasal symptom score (TNSS), ocular symptom score (TOSS) and total medication score (TMS) were evaluated in the three groups. Adverse reactions were recorded, and serum dust mite specific IgE (sIgE) and specific IgG4 were assessed in the ICLIT group and ICLIT booster group.

RESULTS

TSS, TNSS, TOSS, and TMS scores were significantly lower in the three groups at 36 months after treatment (p < 0. 05). And at 36 months the ICLIT-booster group showed results similar to SCIT and superior to ICLIT (p < 0. 05). Serum specific IgE decreased in all three groups at 12 and 36 months after treatment, p < 0.01. The ICLIT group and the ICLIT booster group showed a significant increase in sIgG4, p < 0.01. None of the patients in the three groups had any serious systemic adverse effects during the 3-year follow-up.

CONCLUSION

The ICLIT treatment is effective and safe on AR. One booster injection of allergens at 1 year can greatly improve its long-term efficacy.

TRIAL REGISTRY

Clinical trial registration number: ChiCTR1800017130.

Clonal evolution and stereotyped sequences of human IgE lineages in aeroallergen-specific immunotherapy

BACKGROUND

Allergic disease reflects specific inflammatory processes initiated by interaction between allergen and allergen-specific IgE. Specific immunotherapy (SIT) is an effective long-term treatment option, but the mechanisms by which SIT provides desensitization are not well understood.

OBJECTIVE

Our aim was to characterize IgE sequences expressed by allergen-specific B cells over a 3-year longitudinal study of patients with aeroallergies who were undergoing SIT.

METHODS

Allergen-specific IgE-expressing clones were identified by using combinatorial single-chain variable fragment libraries and tracked in PBMCs and nasal biopsy samples over a 3-year period with antibody gene repertoire sequencing. The characteristics of private IgE-expressing clones were compared with those of stereotyped or "public" IgE responses to the grass pollen allergen Phleum pratense (Phl p) 2.

RESULT

Members of the same allergen-specific IgE lineages were observed in nasal biopsy samples and blood, and lineages detected at baseline persisted in blood and nasal biopsy samples after 3 years of SIT, including B cells that express IgE. Evidence of progressive class switch recombination to IgG subclasses was observed after 3 years of SIT. A common stereotyped Phl p 2-specific antibody heavy chain sequence was detected in multiple donors. The amino acid residues enriched in IgE-stereotyped sequences from seropositive donors were analyzed with machine learning and k-mer motif discovery. Stereotyped IgE sequences had lower overall rates of somatic hypermutation and antigen selection than did single-chain variable fragment-derived allergen-specific sequences or IgE sequences of unknown specificity.

CONCLUSION

Longitudinal tracking of rare circulating and tissue-resident allergen-specific IgE+ clones demonstrates persistence of allergen-specific IgE+ clones, progressive class switch recombination to IgG subtypes, and distinct maturation of a stereotyped Phl p 2 clonotype.

Immunogenicity of a novel anti-allergic vaccine based on house dust mite purified allergens and a combination adjuvant in a murine prophylactic model

The outer-membrane-derived proteoliposome (PL) of Neisseria meningitidis has been reported as a potent vaccine adjuvant, inducing a Th1-skewed response. This work aimed to assess the immunogenicity of a novel anti-allergic vaccine candidate based on allergens from Dermatophagoides siboney house dust mite and a combination adjuvant containing PL and Alum. In a preventative experimental setting, BALB/c mice were administered with three doses containing 2 µg of Der s1 and 0.4 µg Der s2 allergen, PL and Alum, at 7 days intervals, by subcutaneous route. Furthermore, mice were subjected to an allergen aerosol challenge for 6 consecutive days. Serum IgE, IgG1, and IgG2a allergen-specific antibodies were assessed by ELISA. Cytokine levels in supernatants of D. siboney stimulated lymphocyte cultures and in bronchoalveolar lavage (BAL) were measured by ELISA. Lung tissues were subjected to histological examination. The vaccine prevented the development of both, systemic (IgE) and local allergic responses (featuring lower IL-4, and IL-5 levels in BAL) upon allergen exposure by the inhalant route. Histological examination showed also a diminished allergic inflammatory response in the lungs. After the allergen challenge, cytokine levels in stimulated lymphocyte cultures showed lower values of IL-13 and augmented IFN-γ and IL-10. The vaccine induced a mixed IgG2a/IgG1 antibody response; although only IgG2a was PL-dependent. Both, IgG1/IgE and IgG2a/IgE ratios, showed significantly greater values in vaccinated mice. The findings support a preventative anti-allergic effect associated with the induction of a Th1-like IFN-γ/IL-10 response. IgG1/IgE and IgG2a/IgE ratios could be useful biomarkers for translation into clinical trials.

Emerging Hop Japanese Pollinosis in Asia

Hop Japanese (Hop J) pollen has been considered one of the major causative pollen allergens in Far East Asia in the autumn season. The sensitization rate, pollen count, and allergenicity of Hop J pollens are increasing in this region because of increased air pollution and global warming. However, commercial skin test agents for the diagnosis and allergen extracts for the allergen immunotherapy are not available. This review summarizes recent data on clinical impact of Hop J pollinosis in order to facilitate the development of diagnostic and therapeutic agents for this region.

Coordinated IgG2 and IgE responses as a marker of allergen immunotherapy efficacy

BACKGROUND

IgG2 responses are associated with repeated antigen exposure and display highly mutated variable domains. A recent study highlighted a role of IgG2+ memory B cells and allergen-specific IgG2 levels after a 3rd consecutive pre-seasonal sublingual allergen immunotherapy (AIT) with grass pollen tablet. Herein, we aim to explore changes in allergen-specific IgG2 in individuals undergoing house dust mite immunotherapy (HDM-AIT) and explore whether the interrelationship with other humoral responses (i.e., IgG4 and IgE) may discriminate between high and low responders.

METHODS

Levels of serum Dermatophagoides pteronyssinus and Dermatophagoides farinae-specific IgG2, IgG4, and IgE antibodies were measured by ELISA or ImmunoCap in a sub-group of individuals enrolled in a randomized, double-blind, placebo-controlled, sublingual AIT study evaluating the safety and efficacy of a 300 IR HDM tablet.

RESULTS

After 1-year sublingual AIT, HDM-specific serum IgG2 responses increase mostly in high versus low responders and are distinctive according to the clinical benefit. Higher correlation between HDM-specific IgG2, IgE, and/or IgG4 responses is seen in subjects benefiting the most from HDM-AIT as indicated by changes in Average Total Combined Scores. More strikingly, statistically significant correlation between HDM-specific IgG2 and IgE responses is only observed in individuals stratified as high responders.

CONCLUSIONS

We provide evidence for coordinated serum immune responses upon AIT in HDM-allergic subjects exhibiting high clinical benefit when compared with low responders. Assessing HDM-specific IgE, IgG2, and IgG4 in serum could be used as follow-up combined markers to support decision as to AIT continuation and/or adaptation.

Effectiveness of Sublingual Immunotherapy in the Treatment of HDM-Induced Nasobronchial Allergies: A 3-Year Randomized Case-Control Study From Kashmir

Allergen immunotherapy (AIT) is the only disease-modifying treatment for allergic disorders that induces immunological tolerance through administration of specific allergens. Studies on AIT for subcutaneous route are in abundance; however, the efficacy of AIT in tablet form through sublingual route has not been well elucidated. The present prospective, parallel-group, controlled study sought to compare the efficacy of sublingual immunotherapy (SLIT) tablets with pharmacotherapy (PT) in 332 house dust mite (HDM)-specific allergic asthma and/or rhinitis patients over a period of 3 years. Patients were followed up for a 6-month run-in period and then randomly stratified as those who would receive SLIT, SLIT in addition to PT (SLIT+PT), and PT alone. AIT was administered in the form of sublingual tablets. Symptom and medication scores were measured every 3 months. In vitro evaluation of serum total and HDM specific immunoglobulin E (HDM sIgE) levels was carried out every 3 months, whereas in vivo skin prick test was performed annually for 3 years. Our study demonstrated sustained clinical improvement, reduction in inhaled corticosteroid (ICS) dose and duration as well as prevention from development of neosensitization to other aero allergens in HDM-allergic asthmatics and/or rhinitis patients treated with 3 years SLIT. Despite a remarkable clinical improvement with AIT, we observed that SLIT did not significantly change the skin reactivity to HDM at 3 years and there was no significant change in the ratio of serum total and HDM sIgE. Given the immune and disease modifying effects of AIT in allergic diseases, the present study supports the notion of its sublingual mode being an effective long-term immunomodulator in HDM-sensitized nasobronchial allergies.

Immunopharmacology in Vernal Keratoconjunctivitis: Current and Future Perspectives

Vernal keratoconjunctivitis (VKC) is a complex and chronic, multifactorial Th2 cell-mediated chronic ocular surface inflammatory condition that typically affects predominantly male children in hot or warm climates. The primary symptom is intense ocular pruritus, often significant enough to affect activities of daily living. Clinical features differ from simple forms of allergic conjunctivitis in that they are more-or-less confined to the superior tarsus and limbus. There is also a risk of corneal involvement, which leads to irreversible vision loss in approximately 6% of patients. Right now, there is no standardized treatment protocol, and many of the currently available options are not effective in severe and recurrent cases. As such, it is imperative to understand this complex allergic immune response in order to identify future therapeutic targets. This review will focus on potential drug targets in VKC, with particular emphasis on immunomodulators and immunobiologic agents.

Long-term impact of hymenoptera venom immunotherapy on clinical course, immune parameters, and psychosocial aspects

BACKGROUND

Venom immunotherapy (VIT) is highly efficient in subjects suffering from IgE-mediated allergy to hymenoptera venom (HV), and VIT results in substantial improvement of quality of life (QoL). However, VIT-induced tolerance may be lost over time after cessation of treatment, putting patients at risk of re-sting anaphylaxis.

MATERIALS AND METHODS

To study the effect of VIT on maintenance of HV tolerance we evaluated the natural history of 54 patients who were treated with VIT up to 29 years ago, with a special focus on re-stings and their subsequent course. Furthermore, we analyzed HV-specific IgE, IgG, and IgG4 antibody titers. Finally, we assessed the long-term impact of VIT on various psychosocial aspects like dealing with hymenoptera exposures, daily life activities, self-assurance, and personal environment.

RESULTS

29 (53.7%) subjects experienced at least one re-sting after stopping VIT, with 23 (79%) showing no systemic reaction (SR). Eleven of these (37.9%) took emergency drugs as a safety measurement. Six individuals (21%) showed loss of tolerance experiencing an anaphylactic reaction. No difference in HV-specific IgE, IgG4, or IgG antibody concentrations was noticed among the different patients. Subjects who tolerated a re-sting without applying emergency drugs felt least affected in their social-behavioral leisure activities when hymenoptera were around or by anxiety for new stings.

CONCLUSION

VIT leads to long-term tolerance in the majority of HV-allergic patients, however, ~ 1/5 may lose protection over time, arguing for continued follow-up on VIT-treated subjects and keeping them equipped with an emergency kit. Notably, VIT also results in a lasting, strong impact on self-assurance and sense of well-being in individuals who tolerated a re-sting without employing emergency drugs, which emphasizes the need to use them only in case of systemic symptoms after stopping successful VIT.

Respiratory tract infections in children with allergic asthma on allergen immunotherapy during influenza season

To describle how respiratory tract infections (RTIs) that occurred in children with allergic asthma (AA) on allergen immunotherapy (AIT) during an influenza season. Data including clinical symptoms and treatment history of children (those with AA on AIT and their siblings under 14 years old), who suffered from RTIs during an influenza season (Dec 1st, 2019–Dec 31st, 2019), were collected (by face to face interview and medical records) and analyzed. Children on AIT were divided into 2 groups: stage 1 (dose increasing stage) and stage 2 (dose maintenance stage). Their siblings were enrolled as control. During the study period, 49 children with AA on AIT (33 patients in stage 1 and 16 patients in stage 2) as well as 49 children without AA ( their siblings ) were included. There were no significant differences in occurrences of RTIs among the three groups (p > 0.05). Compared with children in the other two groups, patients with RTIs in stage 2 had less duration of coughing and needed less medicine. Children on AIT with maintenance doses had fewer symptoms and recovered quickly when they were attacked by RTIs, which suggested that AIT with dose maintenance may enhance disease resistance of the body.

EAACI Allergen Immunotherapy User's Guide

Allergen immunotherapy is a cornerstone in the treatment of allergic children. The clinical efficiency relies on a well-defined immunologic mechanism promoting regulatory T cells and downplaying the immune response induced by allergens. Clinical indications have been well documented for respiratory allergy in the presence of rhinitis and/or allergic asthma, to pollens and dust mites. Patients who have had an anaphylactic reaction to hymenoptera venom are also good candidates for allergen immunotherapy. Administration of allergen is currently mostly either by subcutaneous injections or by sublingual administration. Both methods have been extensively studied and have pros and cons. Specifically in children, the choice of the method of administration according to the patient's profile is important. Although allergen immunotherapy is widely used, there is a need for improvement. More particularly, biomarkers for prediction of the success of the treatments are needed. The strength and efficiency of the immune response may also be boosted by the use of better adjuvants. Finally, novel formulations might be more efficient and might improve the patient's adherence to the treatment. This user's guide reviews current knowledge and aims to provide clinical guidance to healthcare professionals taking care of children undergoing allergen immunotherapy.

Allergen-Specific Immunotherapy With Liposome Containing CpG-ODN in Murine Model of Asthma Relies on MyD88 Signaling in Dendritic Cells

Changing the immune responses to allergens is the cornerstone of allergen immunotherapy. Allergen-specific immunotherapy that consists of repeated administration of increasing doses of allergen extract is potentially curative. The major inconveniences of allergen-specific immunotherapy include failure to modify immune responses, long-term treatment leading to non-compliance and the potential for developing life-threating anaphylaxis. Here we investigated the effect of a novel liposomal formulation carrying low dose of allergen combined with CpG-ODN, a synthetic TLR9 agonist, on established allergic lung inflammation. We found that challenge with allergen (OVA) encapsulated in cationic liposome induced significantly less severe cutaneous anaphylactic reaction. Notably, short-term treatment (three doses) with a liposomal formulation containing co-encapsulated allergen plus CpG-ODN, but not allergen or CpG-ODN alone, reversed an established allergic lung inflammation and provided long-term protection. This liposomal formulation was also effective against allergens derived from Blomia tropicalis mite extract. The attenuation of allergic inflammation was not associated with increased numbers of Foxp3-positive or IL-10-producing regulatory T cells or with increased levels of IFN-gamma in the lungs. Instead, the anti-allergic effect of the liposomal formulation was dependent of the innate immune signal transduction generated in CD11c-positive putative dendritic cells expressing MyD88 molecule. Therefore, we highlight the pivotal role of dendritic cells in mediating the attenuation of established allergic lung inflammation following immunotherapy with a liposomal formulation containing allergen plus CpG-ODN.

State-of-the-art in marketed adjuvants and formulations in Allergen Immunotherapy: A position paper of the European Academy of Allergy and Clinical Immunology (EAACI)

Since the introduction of allergen immunotherapy (AIT) over 100 years ago, focus has been on standardization of allergen extracts, with reliable molecular composition of allergens receiving the highest attention. While adjuvants play a major role in European AIT, they have been less well studied. In this Position Paper, we summarize current unmet needs of adjuvants in AIT citing current evidence. Four adjuvants are used in products marketed in Europe: aluminium hydroxide (Al(OH)₃ ) is the most frequently used adjuvant, with microcrystalline tyrosine (MCT), monophosphoryl lipid A (MPLA) and calcium phosphate (CaP) used less frequently. Recent studies on humans, and using mouse models, have characterized in part the mechanisms of action of adjuvants on pre-existing immune responses. AIT differs from prophylactic vaccines that provoke immunity to infectious agents, as in allergy the patient is presensitized to the antigen. The intended mode of action of adjuvants is to simultaneously enhance the immunogenicity of the allergen, while precipitating the allergen at the injection site to reduce the risk of anaphylaxis. Contrasting immune effects are seen with different adjuvants. Aluminium hydroxide initially boosts Th2 responses, while the other adjuvants utilized in AIT redirect the Th2 immune response towards Th1 immunity. After varying lengths of time, each of the adjuvants supports tolerance. Further studies of the mechanisms of action of adjuvants may advise shorter treatment periods than the current three-to-five-year regimens, enhancing patient adherence. Improved lead compounds from the adjuvant pipeline are under development and are explored for their capacity to fill this unmet need.

The behavior of Italian allergists in prescribing allergen immunotherapy for house dust mites allergy

The meeting 'Clinical Evidence, Extracts Quality and Biotechnology Innovation in Allergen Immunotherapy' held in Trieste (Italy) on 1 October 2017 concerned the outcomes of a real-world survey conducted on a group of Italian allergists about allergen immunotherapy (AIT) for house dust mites allergy. It pointed out: allergist's confidence that AIT should be prescribed continuously; tablets seem to be well accepted by patients and effective in most subjects with a fast onset of action (3-6 months); combined score for symptom severity and medication use is universally assessed; there is disagreement about the diagnosis of house dust mites allergy, the quote of AIT prescription, the choice for AIT route of administration, assessment of serum IgE and perception of patient's adherence.

Asthma, rhinitis, and nasal polyp multimorbidities

The aim of this review is to assist pulmonologists in the management of diseases involving both the upper and lower respiratory tract that are linked by a common, interrelated epidemiology, clinical signs and symptoms, and inflammatory mechanism - asthma, in particular. The document discusses the definitions of the various sinonasal phenotypes associated with asthma: allergic and non-allergic rhinitis and chronic rhinosinusitis with or without nasal polyps. Diagnostic criteria and severity levels are also listed. Particular attention has been given to the 2 main syndromes associated with asthma: (i)allergic rhinitis, the most common, and (ii)chronic rhinosinusitis with nasal polyps, the disease most closely associated with severe asthma. To summarize, the upper respiratory tract should always be evaluated in order to achieve a single diagnosis and comprehensive treatment of the "united airway".

Duration of Allergen Immunotherapy for Long-Term Efficacy in Allergic Rhinoconjunctivitis

RATIONALE

Subcutaneous and sublingual immunotherapy are effective for allergic rhinitis. An important question is whether allergen immunotherapy provides a sustained clinical effect after treatment cessation. In view of potential side effects, cost and the necessary patient commitment, long-term benefit is an important consideration for the recommendation of immunotherapy over standard pharmacotherapy.

PURPOSE OF REVIEW

In this review, we analyse the existing evidence for long-term effects of both routes of administration in the context of double-blind, placebo-controlled, randomised clinical trials that included a follow-up phase of at least 1 year after treatment cessation.

RECENT FINDINGS

Overall, evidence suggests that 3 years of either subcutaneous or sublingual immunotherapy result in clinical benefit and immunological changes consistent with allergen-specific tolerance sustained for at least 2-3 years after treatment cessation.

SUMMARY

The data presented here support recommendations in international guidelines that both routes of administration should be continued for a minimum of 3 years. Gaps in the evidence remain regarding the long-term efficacy of immunotherapy for perennial rhinitis and studies performed in children.

Intra-Seasonal Initiation of the SQ-Standardised Grass Allergy Immunotherapy Tablet Routinely Applied by Allergy Specialists and General Practitioners with Experience in Treatment of Allergy: A Non-Interventional Observational Study

INTRODUCTION

Intra-seasonal start of treatment with the SQ® grass sublingual immunotherapy (SLIT) tablet (GRAZAX®, ALK, Denmark) has been previously demonstrated to be well-tolerated. The objective of our study was to investigate the tolerability of intra-seasonal start of treatment comparing patients treated by allergists and general practitioners experienced in treatment of allergy (GPs).

METHODS

In a non-interventional, open-label, observational study, data on intra-seasonal start with the SQ® grass SLIT tablet were recorded in patients treated by allergists and GPs in Germany. Adverse events (AEs) were recorded by the physicians at first administration and during the 1-3-month observation period. The tablets taken and any AEs were recorded by the patients in diaries for the first 14 days.

RESULTS

Treatment with the SQ® grass SLIT tablet was started in 198 patients, and in 179 intra-seasonal (allergists: 140, GPs: 39) and 19 post-seasonal; average treatment period was 47 days. AEs related to intra-seasonal start were reported in 43.6% of patients; no relevant differences between allergists and GPs were observed. In the subgroup of GPs, patients were younger (p = 0.0191), had more frequently asthma (p = 0.0043), more patients used symptomatic medication in the previous pollen season (p = 0.0198) and were more frequently treated for other diseases (p = 0.0467). In the allergists subgroup, more diagnostic allergy tests were applied (p < 0.0001) with less anti-allergic premedication at first administration (p = 0.0026).

CONCLUSION

The intra-seasonal start of treatment with the SQ® grass SLIT tablet in patients routinely treated by allergists or GPs with experience in treatment of allergy was well-tolerated, although patient characteristics were different with respect to age, frequency of asthma and concomitant allergies, use of symptomatic medication in the previous grass pollen season and concomitant treatment of other diseases. The safety profile from a previous placebo-controlled clinical trial and data from a previous real-life study on intra-seasonal start performed by allergists were confirmed.

Current and future management of the young child with early onset wheezing

PURPOSE OF REVIEW

In this review, we discuss current thinking in relation to available guidelines for the care of preschool-aged children with recurrent wheezing, while highlighting the gaps in our knowledge and discussing changes that could occur over the next 5 years.

RECENT FINDINGS

The Asthma Predictive Index as well as allergen-specific IgE, peripheral eosinophil count and exhaled nitric oxide are perhaps underutilized sources of information that can assist in predicting progression to asthma and response to therapies. Inhaled corticosteroids and leukotriene receptor antagonists decrease impairment and exacerbation frequency in wheezing children but are not disease modifying. Macrolides may be useful during acute wheezing episodes for preventing progression to more severe symptoms. Monoclonal antibodies targeting IgE and TH2 cytokines have been successful in trials of adults and older children with asthma, but trials in younger children are needed.

SUMMARY

Establishing the phenotype and endotype of young wheezing children can be useful for prognostication of future asthma risk as well as for selection of the most appropriate treatment. Primary asthma prevention strategies are needed during the critical developmental window in early life prior to the onset of irrecoverable loss of lung function.

The future of immunotherapy for canine atopic dermatitis: a review

Allergen specific immunotherapy (ASIT) is a foundation treatment for canine atopic dermatitis (CAD), though few critical studies have documented its effectiveness as a disease-modifying treatment in dogs. The mechanisms by which ASIT works in dogs have not been elucidated, although they are likely to parallel those known for humans. Current ASIT approaches in CAD focus on either subcutaneous or sublingual administration. Greater knowledge of major allergens in dogs, ideal dosage regimes and details of allergen admixture are likely to lead to better efficacy in CAD. Evaluation of biomarkers for successful therapy may also be of benefit. Potentially important advances in human medicine, that have yet to be explored in dogs, include use of modified allergen preparations such as allergoids, recombinant major allergens or allergen peptides; modification with adjuvants; or packaging of the above in virus-like particles. Co-administration of immunomodulators such as CpG oligodeoxynucleotides or specific monoclonal antibodies might direct the immune response in the desired direction while calming the "cytokine storm" of active disease. Initial trials of alternative routes of administration such as intralymphatic immunotherapy have yielded exciting results in humans, and continuing study in dogs is underway. Progress in ASIT of human food allergy may provide clues that will assist with improved diagnosis and patient management of CAD. Importantly, further study must be undertaken to clarify the conditions under which ASIT is a valuable treatment modality for dogs.

Sublingual immunotherapy tablets as a disease-modifying add-on treatment option to pharmacotherapy for allergic rhinitis and asthma

Allergic rhinitis (AR) with or without conjunctivitis (AR/C) is associated with a significant health and economic burden, and is often accompanied by asthma. Pharmacotherapies are the mainstay treatment options for AR and asthma, but guidelines also recommend allergy immunotherapy (AIT). Unlike pharmacotherapies, AIT has the ability to modify the underlying immunologic mechanisms of AR and asthma with the potential for long-term benefits after treatment is discontinued. Immunotherapy may also prevent progression of AR/C to asthma. Sublingual immunotherapy (SLIT)-tablets are a self-administered alternative to subcutaneous immunotherapy that provide the benefits of AIT without the cost and inconvenience of frequent office visits or the discomfort of injections. SLIT-tablets are also an option that can be utilized by primary care clinicians. Pharmacotherapies are generally effective in mild disease although a number of patients remain uncontrolled. SLIT-tablets have proven efficacy for AR in adults, children, and poly-sensitized allergic patients. Indirect comparisons indicate that SLIT-tablets have superior or comparable efficacy compared with traditional pharmacotherapies for seasonal AR, and superior efficacy for perennial AR. House dust mite (HDM) SLIT-tablets have also demonstrated clinically relevant benefits for asthma, with significant observed reductions in daily inhaled corticosteroid use, risk of asthma exacerbations, and asthma symptoms. SLIT-tablets are well tolerated, with minimal risk of systemic allergic reactions. The most common treatment-related adverse events are oral site reactions such as oral pruritus and throat irritation. Based on the favorable efficacy and safety profile, as well as the convenience of at-home oral administration and disease-modifying effects, SLIT-tablets should be considered as an alternative or add-on treatment to pharmacotherapy for AR/C, and as an add-on treatment for HDM allergic asthma.

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

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

Allergen-Specific Immunotherapy

Allergen-specific immunotherapy remains the only causal treatment of allergic disease to date. Its efficacy in symptom reduction was demonstrated in double blind, placebo-controlled studies of allergic rhinoconjunctivitis, allergic asthma, and Hymenoptera venom hypersensitivity, including long-term effects after discontinuation of treatment. In addition, immunotherapy decreases the risk of developing new sensitisations to aeroallergens in monosensitised patients and allergic asthma in patients with mere allergic rhinitis. The mechanism of immunotherapy entails redirection of the T lymphocyte response from a T helper cell Type 2 phenotype in favour of induction of regulatory T cells and/or immune deviation toward a T helper cell Type 1 phenotype, with resulting inhibition of downstream effector pathways and induction of immunoglobulin G-associated blocking antibodies. Two main application forms are used in clinical practice: subcutaneous immunotherapy and sublingual immunotherapy. The advantage of subcutaneous immunotherapy is its proven efficacy over a broad range of indications. Disadvantages are systemic allergic reactions and inconvenience for the patient due to frequent doctor visits. Sublingual immunotherapy has been shown to result in less systemic allergic reactions and may be more convenient due to home application; however, efficacy has only been proven for allergic rhinitis. For clinicians, the adherence to practice guidelines and thorough knowledge of allergen products, application routes, indications, immunomodulatory mechanisms, efficacy, safety, and cost-effectiveness is important for successful treatment and will be addressed in this review article.

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

BACKGROUND

Eligibility to immunotherapy is based on the determination of IgE reactivity to a specific allergen by means of skin prick or in vitro testing. Biomarkers predicting the likelihood of clinical improvement during immunotherapy would significantly improve patient selection.

METHODS

Proteins were differentially assessed by using 2-dimensional differential gel electrophoresis and label-free mass spectrometry in pretreatment sera obtained from clinical responders and nonresponders within a cohort of 82 patients with grass pollen allergy receiving sublingual immunotherapy or placebo. Functional studies of Fetuin-A (FetA) were conducted by using gene silencing in a mouse asthma model, human dendritic cell in vitro stimulation assays, and surface plasmon resonance.

RESULTS

Analysis by using quantitative proteomics of pretreatment sera from patients with grass pollen allergy reveals that high levels of O-glycosylated sialylated FetA isoforms are found in patients exhibiting a strong decrease in rhinoconjunctivitis symptoms after sublingual immunotherapy. Although FetA is involved in numerous inflammatory conditions, its potential role in allergy is unknown. In vivo silencing of the FETUA gene in BALB/c mice results in a dramatic upregulation of airway hyperresponsiveness, lung resistance, and T_H2 responses after allergic sensitization to ovalbumin. Both sialylated and nonsialytated FetA bind to LPS, but only the former synergizes with LPS and grass pollen or mite allergens to enhance the Toll-like receptor 4-mediated proallergic properties of human dendritic cells.

CONCLUSIONS

As a reflection of the patient's inflammatory status, pretreatment levels of sialylated FetA in the blood are indicative of the likelihood of clinical responses during grass pollen immunotherapy.

Patient engagement and patient support programs in allergy immunotherapy: a call to action for improving long-term adherence

Allergy immunotherapy (AIT) is acknowledged to produce beneficial mid- and long-term clinical and immunologic effects and increased quality of life in patients with allergic respiratory diseases (such as allergic rhinoconjunctivitis and allergic asthma). However, poor adherence to AIT (due to intentional and/or non-intentional factors) is still a barrier to achieving these benefits. There is an urgent need for patient support programs (PSPs) that encompass communication, educational and motivational components. In the field of AIT, a PSP should be capable of (1) improving adherence, (2) boosting patient engagement, (3) explaining how AIT differs from pharmacological allergy treatments; (4) increasing health literacy about chronic, progressive, immunoglobulin-E-mediated immune diseases, (5) helping the patient to understand and manage local or systemic adverse events, and (6) providing and/or predicting local data on aeroallergen levels. We reviewed the literature in this field and have identified a number of practical issues to be addressed when implementing a PSP for AIT: the measurement of adherence, the choice of technologies, reminders, communication channels and content, the use of "push" messaging and social networks, interactivity, and the involvement of caregivers and patient leaders. A key issue is "hi-tech" (i.e. approaches based mainly on information technology) vs. "hi-touch" (based mainly on interaction with humans, i.e. family members, patient mentors and healthcare professionals). We conclude that multistakeholder PSPs (combining patient-, provider and society-based actions) must now be developed and tested with a view to increasing adherence, efficacy and safety in the field of AIT.

Treatment effect of sublingual immunotherapy tablets and pharmacotherapies for seasonal and perennial allergic rhinitis: Pooled analyses

BACKGROUND

Data comparing the treatment effect of allergy immunotherapy and pharmacotherapy are lacking.

OBJECTIVE

We sought to indirectly compare the treatment effect of sublingual immunotherapy (SLIT)-tablets with pharmacotherapy for seasonal allergic rhinitis (SAR) and perennial allergic rhinitis (PAR).

METHODS

Pooled data from randomized, double-blind, placebo-controlled trials for the clinical development programs of selected allergic rhinitis treatments were evaluated. Total nasal symptom scores (TNSSs) relative to placebo were compared. Subjects scored symptoms daily during entire pollen seasons in 6 timothy grass SLIT-tablet trials (n = 3094) and 2 ragweed SLIT-tablet trials (n = 658) and during the last 8 weeks of treatment in 2 house dust mite (HDM) SLIT-tablet trials (n = 1768). Subjects scored symptoms daily in 7 montelukast (10 mg, n = 6799), 9 desloratadine (5 mg, n = 4455), and 8 mometasone furoate nasal spray (MFNS; 200 μg daily, n = 2140) SAR or PAR trials. SLIT-tablet trials allowed rescue medication use, whereas most pharmacotherapy trials did not. A fixed-effect meta-analysis method estimated differences in on-treatment average TNSSs.

RESULTS

In grass and ragweed SLIT-tablet trials, overall improvement in TNSSs relative to placebo was 16.3% and 17.1%, respectively. In HDM SLIT-tablet trials, TNSS overall improvement relative to placebo was 16.1%. In the montelukast, desloratadine, and MFNS trials, TNSS overall improvement relative to placebo was 5.4%, 8.5%, and 22.2%, respectively, for SAR trials, and 3.7%, 4.8%, and 11.2%, respectively, for PAR trials.

CONCLUSIONS

Although comparisons were limited by study design heterogeneity and use of rescue medications in SLIT-tablet trials, effects on nasal symptoms with timothy grass and ragweed SLIT-tablets were nearly as great as with MFNS and numerically greater than with montelukast and desloratadine for SAR. HDM SLIT-tablet effects were numerically greater than all pharmacotherapies for PAR. SLIT-tablets offer the additional benefit of long-term efficacy.

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

INTRODUCTION

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

AREAS COVERED

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

Specific immunotherapy for rhinitis and asthma with a subcutaneous hypoallergenic high-dose house dust mite extract: results of a 9-month therapy

AIM

Effectiveness of a 9-month specific immunotherapy with a subcutaneous hypoallergenic high-dose house dust mite extract to reduce allergic symptoms as perceived by patients and physicians was assessed.

PATIENTS & METHODS

An observational, retrospective, multicenter study was carried out in patients diagnosed with asthma and/or rhinitis caused by house dust mites having started specific immunotherapy with Acaroid(®). Primary end point was perceived effectiveness.

RESULTS

A total of 409 patients were included. According to physician-completed visual analogue scale, a 58.1% clinical improvement was observed. Patient-completed visual analogue scale showed a 69.8% clinical improvement. The need for unscheduled/emergency healthcare, as an indication of poor quality of life, showed a significant reduction.

CONCLUSION

Our results confirm in a real-world setting the findings from randomized clinical trials of high-dose house dust mites allergoid immunotherapy with a subcutaneous hypoallergenic high-dose house dust mite extract.

Evaluation of various adjuvant nanoparticulate formulations for meningococcal capsular polysaccharide-based vaccine

Neisseria meningitidis is a leading cause of bacterial meningitis and sepsis and its capsular polysaccharides (CPS) are a major virulence factor in meningococcal infections and form the basis for serogroup designation and preventive vaccines. We have formulated a novel meningococcal nanoparticulate vaccine formulation that does not require chemical conjugation, but encapsulates meningococcal CPS polymers in a biodegradable material that slowly release antigens, thereby has antigen depot effect to enhance antigenicity. The novel vaccine formulation is inexpensive and can be stored as a dry powder with extended shelf life that does not require the cold-chain which facilitates storage and distribution. In order to enhance the antigenicity of meningococcal nanoparticulate vaccine, we screened various adjuvants formulated in nanoparticles, for their ability to potentiate antigen presentation by dendritic cells. Here, we report that MF59 and Alum are superior to TLR-based adjuvants in enhancing dendritic cell maturation and antigen presentation markers MHC I, MHC II, CD40, CD80 and CD86 in dendritic cells pulsed with meningococcal CPS nanoparticulate vaccine.

Increasing time interval and decreasing allergen dose interval improves ex vivo desensitization of human blood basophils

BACKGROUND

Desensitization is a method for inducing temporary tolerance to allergen. The mechanism underlying desensitization is yet to be established.

METHODS

Basophil granulocytes in whole blood from grass pollen allergic subjects were desensitized ex vivo by sequential addition of increasing allergen concentrations. At each step basophil activation (CD193 ⁺ CD63⁺ ) was monitored with and without (background activation) allergen challenge at optimal concentration. The sequential desensitization protocol was compared to two single-dose desensitization protocols with threshold and subthreshold allergen concentrations. Incubation intervals and allergen concentrations were varied in order to optimise the protocol.

RESULTS

Sequential desensitization effectively reduced basophil response. The single-dose subthreshold protocol and single-dose threshold protocol did not reduce basophil activation with optimal allergen challenge from a mean 57.1 (95% CI: 32.7 - 81.5) to 50.4% (95% CI: 16.3 - 84.4; n = 5; P = 0.43) and 45.0% (95% CI: 23.1 - 66.9; P = 0.14) respectively, while the sequential desensitization protocol reduced activation to a mean 37.2% (95% CI: 16.3 - 58.1; P = 0.018). Reducing incubation time from 10 to 5 minutes increased mean background activation from 22.4 (95% CI: 11.7 - 33.1) to 30.0% (95% CI: 19.7 - 40.3; n = 5; P = 0.026). Increasing time intervals from 10 to 20 minutes reduced background activation from 30.9 (95% CI: 22.8 - 39.0) to 21.9% (95% CI: 16.0 - 27.7; n = 5; P = 0.020). Increasing allergen concentration intervals from 2-fold to 5- and 10-fold did not have significant effect on basophil activation.

CONCLUSIONS

Sequential desensitization ex vivo effectively attenuates the basophil response to allergen. Increasing the time spent at each step improves desensitization. This protocol could be valuable for investigation the mechanism of desensitization. © 2016 International Clinical Cytometry Society.

Clinical considerations in the use of sublingual immunotherapy for allergic rhinitis

BACKGROUND

Allergen immunotherapy (AIT) has been in practice for more than 100 years. However, research in novel routes and delivery methods of immunotherapy to treat allergic rhinitis (AR) and conjunctivitis has only recently occurred in the United States, where the predominant form of AIT provided is largely via a subcutaneous immunotherapy (SCIT) route. AIT may prevent new sensitizations, improve symptoms, decrease medication usage, and prevent allergic asthma. Although AIT is the only potentially curative treatment for AR, access and adherence continue to be problematic. Only a fraction of eligible patients actually undergo treatment, and attrition rates are high. An obvious limitation of SCIT includes the requirement of regular injections to be provided in the physician's office due to the potential for anaphylaxis. Sublingual immunotherapy (SLIT) for home administration has been investigated as a potential alternative to address this limitation of SCIT.

METHODS

A literature review was performed including the current findings from randomized clinical trials and meta-analyses with a discussion of the most recent evidence for the efficacy, safety, and dosing of allergen SLIT.

RESULTS

The current data suggest that SLIT is effective for treatment of seasonal allergies, can potentially prevent asthma, and has a favorable safety profile. Head-to-head studies, however, are few, and comparative effectiveness still remains to be answered. Optimal treatment algorithms for SLIT have not yet been established, with wide variation in dosage selection and schedules. Similarly to SCIT, only a few allergens such as ragweed and grass pollen have been found to be effective in large clinical trials.

CONCLUSION

Recent data indicate that SLIT is an effective treatment modality for seasonal AR, improve quality of life, and can potentially prevent asthma but head-to head studies comparing SLIT to SCIT are needed.

Clinical and immunological responses of dust mite sensitive, atopic dogs to treatment with sublingual immunotherapy (SLIT)

BACKGROUND

Sublingual immunotherapy (SLIT) has been reported to be beneficial in people with atopic dermatitis (AD) and dust mite sensitivity. Evaluation of this therapy has not been reported in spontaneous canine AD.

OBJECTIVES

The objective of this study was to preliminarily evaluate the effectiveness of an established SLIT protocol, as used in human patients, in dogs with AD.

ANIMALS

Ten dust mite sensitive dogs with spontaneous AD.

METHODS

Dogs underwent a 6 month open trial of SLIT concurrently with decreasing dose oral methylprednisolone. Clinical evaluations and quantitative serum anti-mite IgE and IgG levels were performed every 2 months.

RESULTS

Mean methylprednisolone use from the first 2 months of the study to the final 2 months declined from 10.2 to 4.3 mg/kg/2 months (P < 0.001, Student's paired t-test); at 6 months, four dogs required no oral corticosteroid administration. Over the course of the study, median Canine Atopic Dermatitis Extent and Severity Index (CADESI)-03 scores declined from 76.5 to 59; median pruritus scores declined from 65 to 37 (P < 0.02 and P < 0.01, respectively; Wilcoxon signed-rank test). Pre- and post-SLIT intradermal test scores for mite allergen were not significantly different over time. Median Dermatophagoides farinae (DF)-specific IgE levels declined significantly from 150.2 × 10(3) AU/mL to 3.6 × 10(3) AU/mL (P < 0.05). Concurrently, median DF-specific IgG levels increased from 18.5 × 10(6) AU/mL to 3923.4 × 10(6) AU/mL (P < 0.05; Wilcoxon signed-rank tests).

CONCLUSIONS AND CLINICAL IMPORTANCE

SLIT treatment produced clinical improvement in dogs with dust mite-associated AD and was associated with serological changes supporting this improvement. Further studies in larger numbers of dogs and those with polysensitization are warranted.

Efficacy and safety of sublingual immunotherapy in children

Allergen immunotherapy (AIT) is currently the only available disease-modifying and aetiological treatment of IgE-mediated diseases. Sublingual allergen immunotherapy (SLIT) constitutes the preferred route of administration of AIT for respiratory allergies in Europe. Recently it has also been approved in the US. Further applications are currently under evaluation, such as IgE-mediated food allergy and IgE-mediated atopic dermatitis. The SLIT safety profile is overall favourable, although local adverse events, usually mild, are described. Most of the meta-analyses confirmed the efficacy of SLIT in reducing symptoms and medication intake in children with allergic diseases. AIT, as an immune-modulating treatment, can modify the natural history of the allergic diseases: reduction of the risk of development of asthma and bronchial hyperreactivity in patients with allergic rhinitis, and reduction of the onset of new sensitizations. A great interest is now devoted to the preventive effects of AIT and, consequently, to the optimal time of initiation.

From IgE to clinical trials of allergic rhinitis

The current scientific research is continuously aiming at identifying new therapeutic targets with the purpose of modifying the immune response to allergens. The evolution in immunological methods has led to the identification of immunoglobulin E (IgE) as both a diagnostic biomarker and potential therapeutic target in allergic diseases, such as allergic rhinitis. Allergen immunotherapy has been used for more than 100 years to treat allergic diseases and it is today considered the only disease-modifying treatment capable of inducing a long-lasting immunological and clinical tolerance toward the causal allergen. During the past 20 years, major advances have been made in understanding the molecular and cellular mechanisms of allergen tolerance in humans. Moreover, there has been considerable progress in allergen extract modifications and additions to standard extracts. The recognition that IgE plays a pivotal role in basic regulatory mechanisms of allergic inflammation has recently stimulated research into the therapeutic potential of directly targeting this antibody. Omalizumab, the most advanced humanized anti-IgE monoclonal antibody, is currently approved for the treatment of uncontrolled allergic asthma and chronic spontaneous urticaria. Interesting results also arise from studies in which omalizumab was administered in patients with allergic rhinitis. The aim of this review is to provide an update on current findings on immunological and clinical effects of allergen immunotherapy and anti-IgE therapy, which have been shown to have synergistic modes of action for the treatment of allergic rhinitis.

The effect of a new communication template on anticipated willingness to initiate or resume allergen immunotherapy: an internet-based patient survey

Background

A patient’s knowledge of his/her allergic condition and treatment is a key factor in adherence and effectiveness.

Methods

To assess patients’ understanding of allergy and acceptance of allergen immunotherapy on the basis of (i) information given by their physician at the time of prescription and (ii) a new communication template viewed some months later, we performed an Internet-based survey of patient panels in France, Germany, Spain, the USA and Russia. The survey participants were either recent “early abandoners” (having discontinued allergen immunotherapy before the end of the prescribed course) or “non-starters” (having decided not to initiate a course of allergen immunotherapy recommended by their physician). All participants completed an on-line questionnaire immediately before and immediately after viewing the new communication template. The study’s main objectives were to validate the new communication template and to assess its impact on anticipated willingness to initiate or resume allergen immunotherapy.

Results

We surveyed a total of 261 patients (France: 57; Germany: 51; Spain: 52; USA: 51; Russia: 50), comprising 127 “early abandoners” and 134 “non-starters”. The mean time since symptom onset and selection for the study was 14.5 years. Subcutaneous allergen immunotherapy had been prescribed in 60 % of cases. Twenty-eight percent of the participants did not know for which allergy they were being treated. Early abandoners reported a perception of low effectiveness (39 %) and complained about expense (39 %) and practical constraints (32 %). Twenty-two percent of the non-starters feared side effects. The communication template was considered to be clear (by 92 % of the patients), convincing (by 75 %) and reassuring (by 89 %); 80 % of the participants felt better informed afterwards, and 67 % stated that viewing the communication template would have made them more likely to continue or initiate allergen immunotherapy (overall willingness score: 5.65 out of 10 before viewing and 7.1 out of 10 afterwards).

Conclusions

After viewing a new communication template on allergy and allergen immunotherapy, patients participating in the survey felt better informed and more likely to initiate or complete this therapy. It now remains to investigate the communication template’s effect on actual acceptance of and adherence to allergen immunotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13223-015-0083-z) contains supplementary material, which is available to authorized users.

Allergen immunotherapy, routes of administration and cytokine networks: an update

Allergen immunotherapy is a disease-modifying therapy, effective for the treatment of allergic rhinitis, allergic asthma, conjunctivitis or stinging insect allergy. Allergen immunotherapy involves the administration of increasing doses of allergens with the aim of ameliorating the allergic response. Although precise underlying mechanisms of the induction of immune tolerance remain unclear, immunotherapy has been associated with the induction of distinct subsets of Tregs that eventually lead to peripheral tolerance by inducing a deviation from Th2 to Th1 immune responses. This review focuses on the current knowledge of the mechanisms of immunotherapy in relationship to different routes of administration and also provides a unifying view.

Immunotherapy with B cell epitopes ameliorates inflammatory responses in Balb/c mice

Osmotin, a protein from the pathogenesis-related family (PR-5), has been identified as an allergen based on in-silico and in-vitro studies. In the present study, three B cell epitopes of osmotin with single and double amino acid modifications were studied for immunotherapy in a murine model. The single-modification peptides (P-1-1, P-2-1 and P-3-1) and double-modification peptides (P-1-2, P-2-2 and P-3-2) showed significantly lower immunoglobulin (Ig)E binding with patients' sera compared to osmotin (P < 0·01). These peptides showed reduced IgE binding compared to the unmodified peptides (B cell epitopes) P-1, P-2 and P-3. Among the modified peptides, P-2-1, P-3-1, P-2-2 and P-3-2 showed significant reduction in IgE binding and were used for immunotherapy in mice. The sera of mice group treated with peptides showed a significant increase in IgG2a level and a significant decrease in IgE and IgG1 levels (P < 0·05). The mice that received peptide immunotherapy showed a shift from a T helper type 2 (Th2) to Th1 type where interferon (IFN)-γ and interleukin (IL)-10 levels were elevated, with a significant increase in groups treated with peptides P-3-1 and P-3-2 (P < 0·05). There was a reduction in the IL-4 and IL-5 levels in bronchoalveolar lavage fluid (BALF) in the peptide-treated mice groups. Total cell count and eosinophil count in BALF of the peptide-treated groups was also reduced compared to the phosphate-buffered saline (PBS)-treated group. Lung histology showed a significant reduction in cellular infiltrate in mice treated with P-2-2 and P-3-2 compared to PBS. In conclusion, peptides P-2-2 and P-3-2 lowered inflammatory responses and induced a Th1 response in mice.

Hypoallergenic derivatives of Fel d 1 obtained by rational reassembly for allergy vaccination and tolerance induction

BACKGROUND AND OBJECTIVE

The major cat allergen Fel d 1 represents one of the most important respiratory allergens. Aim of this study was to engineer recombinant Fel d 1 derivatives with reduced IgE reactivity and preserved T cell epitopes for vaccination and tolerance induction.

METHODS

Seven recombinant mosaic proteins were generated by reassembly of non-IgE-reactive peptides of Fel d 1 which contained the sequence elements for induction of allergen-specific blocking IgG antibodies and T cell epitopes. Mosaic proteins were expressed in Escherichia coli using codon-optimized synthetic genes and compared with Fel d 1 regarding structural fold by circular dichroism, IgE-binding capacity, activation of allergic patients' basophils and ability to induce allergen-specific blocking IgG antibodies upon immunization.

RESULTS

Although each of the mosaic proteins had lost the alpha-helical fold typical for Fel d 1, a strong reduction in IgE reactivity as well as allergenic activity in basophil activation assays was only obtained for three constructs, two reassembled fragments (Fel d 1 MB, Fel d 1 MC) and a fusion of the latter two (Fel d 1 MF) in which the cysteines of Fel d 1 MC were replaced by serines. Immunization of rabbits with Fel d 1 MB, MC and MF induced high levels of IgG antibodies that inhibited IgE reactivity of cat-allergic patients to Fel d 1 in a comparable manner as IgG induced with the wild-type allergen.

CONCLUSIONS

We report the development of hypoallergenic reassembled Fel d 1 proteins suitable for vaccination and tolerance induction in cat-allergic patients.

Sequential allergen desensitization of basophils is non-specific and may involve p38 MAPK

BACKGROUND

Sequential allergen desensitization provides temporary tolerance for allergic patients. We adapted a clinical protocol to desensitize human blood basophils ex vivo and investigated the mechanism and allergen specificity.

METHODS

We included 28 adult, grass allergic subjects. The optimal, activating allergen concentration was determined by measuring activated CD63(+) CD193(+) SS(Low) basophils in a basophil activation test with 8 log-dilutions of grass allergen. Basophils in whole blood were desensitized by incubation with twofold to 2.5-fold increasing allergen doses in 10 steps starting at 1 : 1000 of the optimal dose. Involvement of p38 mitogen-activated protein kinase (MAPK) was assessed after 3 min of allergen stimulation (n = 7). Allergen specificity was investigated by desensitizing cells from multi-allergic subjects with grass allergen and challenging with optimal doses of grass, birch, recombinant house dust mite (rDer p2) allergen or anti-IgE (n = 10).

RESULTS

Desensitization reduced the fraction of blood basophils responding to challenge with an optimal allergen dose from a median (IQR) 81.0% (66.3-88.8) to 35.4% (19.8-47.1, P < 0.0001). CD63 MFI expression was reduced from 68 248 (29 336-92 001) to 30 496 (14 046-46 179, P < 0.0001). Basophils from multi-allergic subjects were desensitized with grass allergen. Challenge with grass allergen resulted in 39.6% activation (15.8-58.3). An unrelated challenge (birch, rDer p2 or anti-IgE) resulted in 53.4% activation (30.8-66.8, P = 0.16 compared with grass). Desensitization reduced p38 MAPK phosphorylation from a median 48.1% (15.6-92.8) to 26.1% (7.4-71.2, P = 0.047) and correlated with decrease in CD63 upregulation (n = 7, r > 0.79, P < 0.05).

CONCLUSION

Desensitization attenuated basophil response rapidly and non-specifically at a stage before p38 MAPK phosphorylation.

A role for impaired regulatory T cell function in adverse responses to aluminum adjuvant-containing vaccines in genetically susceptible individuals

Regulatory T cells play a critical role in the immune response to vaccination, but there is only a limited understanding of the response of regulatory T cells to aluminum adjuvants and the vaccines that contain them. Available studies in animal models show that although induced T regulatory cells may be induced concomitantly with effector T cells following aluminum-adjuvanted vaccination, they are unable to protect against sensitization, suggesting that under the Th2 immune-stimulating effects of aluminum adjuvants, Treg cells may be functionally compromised. Allergic diseases are characterized by immune dysregulation, with increases in IL-4 and IL-6, both of which exert negative effects on Treg function. For individuals with a genetic predisposition, the beneficial influence of adjuvants on immune responsiveness may be accompanied by immune dysregulation, leading to allergic diseases. This review examines aspects of the regulatory T cell response to aluminum-adjuvanted immunization and possible genetic susceptibility factors related to that response.

Sublingual immunotherapy: recent advances

The practice of administering sublingual immunotherapy for respiratory allergy is gaining more and more diffusion worldwide as a consequence of the robust demonstration of clinical efficacy and safety provided by recent high-powered and well-designed studies, confirming for individual seasonal allergens the results of previous metanalyses in adult and pediatric populations. Preliminary evidence derives from recent rigorous trials on perennial allergens, like house dust mites, and specifically designed studies addressed the benefits on asthma. Emerging research suggests that SLIT may have a future role in other allergic conditions such as atopic dermatitis, food, latex and venom allergy. Efforts to develop a safer and more effective SLIT for inhalant allergens have led to the development of allergoids, recombinant allergens and formulations with adjuvants and substances targeting antigens to dendritic cells that possess a crucial role in initiating immune responses. The high degree of variation in the evaluation of clinical effects and immunological changes requires further studies to identify the candidate patients to SLIT and biomarkers of short and long term efficacy. Appropriate management strategies are urgently needed to overcome the barriers to SLIT compliance.

Efficacy analysis of three-year subcutaneous SQ-standardized specific immunotherapy in house dust mite-allergic children with asthma

The present study aimed to evaluate the efficacy of three-year subcutaneous SQ-standardized specific immunotherapy (SCIT) in house dust mite (HDM)-allergic children with asthma. Ninety children with allergic asthma to HDMs, with or without allergic rhinitis, were randomly divided into two groups, the treatment group and the control group. The treatment group received SCIT combined with standardized glucocorticoid management and the control group received standardized glucocorticoid management alone for a period of three years. The mean daily dose of inhaled corticosteroids (ICSs), a four-week diary recording the symptom scores of asthma, peak expiratory flow (PEF) measurements, skin prick test results and serum immunoglobulin E (IgE) levels were assessed prior to treatment and following one, two and three years of treatment. The median dose of ICS was reduced in the treatment group after two and three years of treatment compared with that of the control group. After three years of treatment, the discontinuation percentage of ICS in the treatment group was higher than that in the control group. The treatment group demonstrated significantly reduced daytime and night-time asthmatic symptom scores, increased PEF values and reduced serum IgE levels after two and three years of treatment compared with those in the control group (P<0.05). In conclusion, three-year SCIT treatment combined with ICS is an effective immunotherapy for children with allergic asthma and resulted in a reduction of the required ICS dose.

Efficacy and safety of sublingual tablets of house dust mite allergen extracts in adults with allergic rhinitis

BACKGROUND

Preliminary studies have suggested the efficacy of sublingual tablets of house dust mite (HDM) extracts in adults with allergic rhinitis.

OBJECTIVES

We sought to assess the efficacy and safety of 2 doses of HDM sublingual tablets over 1 treatment year and the subsequent immunotherapy-free year.

METHODS

Adults with HDM-associated allergic rhinitis were randomized in a double-blind, placebo-controlled study to receive 500 index of reactivity (IR) tablets, 300IR tablets, or placebo administered once daily for 1 year and were followed for the subsequent year. The primary efficacy variable was the Average Adjusted Symptom Score over the year 1 primary period (ie, October 1 to December 31). Symptoms and rescue medication scores, onset of action, patient-reported outcomes, and safety were secondary variables. The same end points were evaluated during the immunotherapy-free year. The primary efficacy end point was analyzed by using analysis of covariance.

RESULTS

Five hundred nine participants were randomized, and 427 continued in the immunotherapy-free year. Both the 500IR and 300IR HDM sublingual tablets significantly reduced mean Average Adjusted Symptom Scores compared with placebo by -20.2% (P = .0066) and -17.9% (P = .0150), respectively. Efficacy of both doses was maintained during the treatment-free follow-up phase. The onset of action was at 4 months. Participants' global evaluation of treatment success was significantly higher in the 500IR and 300IR groups compared with the placebo group (P = .0206 and P = .0001, respectively). Adverse events were generally application-site reactions. There were no reports of anaphylaxis.

CONCLUSIONS

Twelve months of treatment with 500IR and 300IR sublingual tablets of HDM allergen extracts was efficacious and well tolerated. Efficacy was maintained during the treatment-free follow-up year.

Allergen immunotherapy and allergic rhinitis: false beliefs

BACKGROUND

Over the last 100 years, several persistent misconceptions or 'false beliefs' have built up around allergen immunotherapy and its use in allergic rhinitis. This is perhaps because enthusiastic physicians administered complex allergen extracts to a diverse population of patients suffering from heterogeneous atopic conditions. Here, we review evidence that counters seven of these 'false beliefs.'

DISCUSSION

1. The symptoms of allergic rhinitis can be more heterogeneous, more severe and more troublesome in everyday life than many physicians believe. Large-scale epidemiological surveys show that the majority of allergic rhinitis patients have at least one symptom severe enough to interfere with sleep quality, productivity and/or well-being. 2. Allergen immunotherapy is not necessarily suitable for all allergic rhinitis patients (notably those with mild symptoms). Recent evidence from double-blind, placebo-controlled, randomized clinical trials suggests that the more severe the disease, the greater the treatment effect. 3. Allergen immunotherapy is often accused of lack of efficacy (relative to pharmacotherapy, for example). However, there are now many meta-analyses, systematic reviews and high-quality clinical trials that find overwhelmingly in favor of the efficacy of allergen immunotherapy (including sublingual formulations) in allergic rhinitis induced by pollen and, increasingly, other allergens. 4. Natural-exposure and challenge-chamber trials have shown that symptom relief may become apparent within months or even weeks of the initiation of allergen immunotherapy. 5. In pollen-induced allergic rhinitis, several years of subcutaneous or sublingual allergen immunotherapy are associated with sustained clinical efficacy after subsequent treatment cessation - confirming the disease-modifying nature of this therapy. 6. Most patients seeking treatment for allergic rhinitis are polysensitized, and allergen immunotherapy has proven efficacy in large, robust clinical trials in these groups. Polysensitization is not a contraindication to allergen immunotherapy. 7. Sublingual allergen immunotherapy is safe for home administration. A recent review calculated that 1 billion doses were administered worldwide between 2000 and 2010 and found that the 11 case reports of anaphylaxis (all non-fatal) corresponded to non-standard practice.

SUMMARY

Modern, evidence-based medicine has generated more than enough robust evidence to remove misconceptions about allergen immunotherapy and allergic rhinitis.

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.