Immunotherapy for allergies and asthma: present and future

Current practices and future trends in cockroach allergen immunotherapy

PURPOSE OF REVIEW

This review evaluates the current modes of allergen-specific immunotherapy for cockroach allergens, in terms of clinical outcomes and explores future trends in the research and development needed for a more targeted cockroach immunotherapy approach with the best efficacy and minimum adverse effects.

SUMMARY

Cockroach allergy is an important risk factor for allergic rhinitis in the tropics, that disproportionately affects children and young adults and those living in poor socio-economic environments. Immunotherapy would provide long-lasting improvement in quality of life, with reduced medication intake. However, the present treatment regime is long and has a risk of adverse effects. In addition, cockroach does not seem to have an immuno-dominant allergen, that has been traditionally used to treat allergies from other sources. Future trends of cockroach immunotherapy involve precision diagnosis, to correctly identify the offending allergen. Next, precision immunotherapy with standardized allergens, which have been processed in a way that maintains an immunological response without allergic reactions. This approach can be coupled with modern adjuvants and delivery systems that promote a Th1/Treg environment, thereby modulating the immune response away from the allergenic response.

Recent advance of spleen tyrosine kinase in diseases and drugs

Spleen tyrosine kinase (Syk) is a non-receptor protein tyrosine kinase, also known as p72Syk. It is important for downstream signaling from cell surface receptors, such as Fc receptors, complement receptors and integrin. Syk plays the critical role in triggering immune and allergic reactions, the signaling pathway of Syk has become the research focus on drugs for allergic disease and human malignancies. This review summarized the characteristics of Syk, its mechanism in related reactions, and mainly discussed the signal transduction pathway mediated by Syk. With the development of industry and the aggravation of environmental pollution, the incidence of allergic diseases is increasing, it has become a global priority disease. In this process, Syk participates in IgE/FcεRI signaling pathway plays a critical role in triggering allergic reactions. This review described the characteristics and the interaction mechanism of Syk and its binding proteins in disease, and summarized the research status of targeted Syk inhibitors.

Egg Allergy: Diagnosis and Immunotherapy

Hypersensitivity or an allergy to chicken egg proteins is a predominant symptomatic condition affecting 1 in 20 children in Australia; however, an effective form of therapy has not yet been found. This occurs as the immune system of the allergic individual overreacts when in contact with egg allergens (egg proteins), triggering a complex immune response. The subsequent instantaneous inflammatory immune response is characterized by the excessive production of immunoglobulin E (IgE) antibody against the allergen, T-cell mediators and inflammation. Current allergen-specific approaches to egg allergy diagnosis and treatment lack consistency and therefore pose safety concerns among anaphylactic patients. Immunotherapy has thus far been found to be the most efficient way to treat and relieve symptoms, this includes oral immunotherapy (OIT) and sublingual immunotherapy (SLIT). A major limitation in immunotherapy, however, is the difficulty in preparing effective and safe extracts from natural allergen sources. Advances in molecular techniques allow for the production of safe and standardized recombinant and hypoallergenic egg variants by targeting the IgE-binding epitopes responsible for clinical allergic symptoms. Site-directed mutagenesis can be performed to create such safe hypoallergens for their potential use in future methods of immunotherapy, providing a feasible standardized therapeutic approach to target egg allergies safely.

Mechanism(s) of prolonged attenuation of allergic responses after modulation of idiotypic regulatory network

BACKGROUND

We showed previously that allergic reactivity to ovalbumin (OVA) could be regulated in mice following perturbation of immune networks using combinations of an immune Ig along with anti-idiotypic Ig. We have explored features of this regulation including: its persistence after cessation of administration of combined Igs; the ability of heterologous Igs to produce immunoregulation; a role for Treg induction in regulation; and the ability to attenuate responses in mice pre-sensitized to an allergic stimulus.

METHODS

BALB/c mice were sensitized to OVA. Mice also received 5 weekly injections of immune Ig or anti-idiotype Ig (at separate sites) from either homologous (mouse) or heterologous (human) sources. In the latter case pooled IVIG (given IM, hence hereafter IMIG) was used as a source of anti-idiotype Ig, and human anti-Tet as immune Ig. Injections of the Ig were given from the time of OVA sensitization (to attenuate development of immunity), or after pre-sensitization of mice (to attenuate existing allergic responses). All mice were assayed for development of OVA-specific serum IgE and IgG, as well as the production of OVA-induced IL-2, IL-4, IL-13, IL-31 and IL-33 in splenocytes cultured for 72 h. In studies examining possible mechanism(s) responsible for inhibition of immunity mice received, in addition to the Ig treatments described, infusion of depleting anti-CD4, and/or anti-CD8 antibodies, or a mAb to TNFSFR25, known to expand Tregs implicated in regulation of Allo immunity.

RESULTS

Combinations of both heterologous and homologous immune Igs and anti-idiotype Igs attenuated OVA allergic responses in both naïve and pre-sensitized mice. This attenuation persisted in mice greater than 14 weeks after cessation of treatment with the Igs used. Finally, depletion of either CD4 or CD8 cells ameliorated the suppressive effect seen, while the combination of anti-CD4 and anti-CD8 essentially abolished suppression. Suppression was further enhanced by anti-TNFSFR25 mAb.

CONCLUSIONS

We conclude that the combine Ig treatment protocols used produced a long-lasting suppression of allergic immunity, even in pre-sensitized animals. The effects seem to depend upon induction and expansion of Tregs and represents a novel approach to treatment of allergic disease in humans and other animals.

Species Specificity on Interaction between IgE and FcεRI

Allergic diseases are one of the most prevalent diseases at present, it is imperative to understanding the pathophysiology and treatment strategies for allergic diseases. In this process, the binding of IgE and FcεRI on effector cells plays a critical role in triggering allergic reactions. However, the species specificity of the interaction between IgE and FcεRI has not been clearly explained. This review described the characteristics and the interaction mechanism in the allergic reaction of IgE and FcεRI and summarized the species specificity between IgE and FcεRI.

Specific immunotherapy in allergic rhinitis

Allergic rhinitis is a common condition, with significant impact on quality of life depending on severity and quality of control. Allergen-specific immunotherapy (allergen-SIT) is the only known treatment able to alter the natural course of allergic rhinitis. Although well known to allergologists, it has yet to be fully adopted by the ENT community. This review, based on the most recent meta-analyses and clinical studies, shows that SIT significantly reduces symptoms and medication requirements (nasal corticosteroids, H1-antihistamines) in allergic rhinitis. It can reduce the risk of progression to asthma and, if initiated early enough, of developing new sensitizations. Immunobiological analysis shows an altered inflammatory profile following SIT, with immune tolerance involving T-regulatory lymphocyte induction and IgG production. Sublingual SIT with drops is as effective as subcutaneous SIT and is simpler to use, with less anaphylactic risk. Standardization of trial protocols in terms of treatment response assessment and side effect grading is recommended to improve comparative studies. Sublingual SIT with tablets has recently been introduced, providing a good opportunity for ENT practitioners to adopt the SIT approach in rhinitis triggered by allergy to pollens and, in the near future, to house dust mites.

Critical appraisal of the clinical utility of sublingual immunotherapy in allergy

Since it was introduced by Noon in 1911, allergen-specific immunotherapy or desensitization has been widely prescribed in the management of allergic diseases. Aimed at the etiology, it represents the only effective treatment for allergy. The basic mechanisms of immunotherapy are becoming better understood and allow us to improve this technique in the future. The sublingual immunotherapy as an alternative to subcutaneous route has been widely studied. Several clinical trials confirmed that sublingual immunotherapy is efficient in reducing allergic respiratory symptoms. The sublingual immunotherapy reduces the risk of developing serious side effects due to desensitization. We performed a literature review in order to remind the mechanisms of action and to demonstrate efficacy and tolerability of the sublingual immunotherapy in the treatment of allergic rhinoconjunctivitis and asthma and its impact on the quality of life.

Specific allergen immunotherapy for the treatment of atopic eczema

BACKGROUND

Specific allergen immunotherapy (SIT) is a treatment that may improve disease severity in people with atopic eczema (AE) by inducing immune tolerance to the relevant allergen. A high quality systematic review has not previously assessed the efficacy and safety of this treatment.

OBJECTIVES

To assess the effects of specific allergen immunotherapy (SIT), including subcutaneous, sublingual, intradermal, and oral routes, compared with placebo or a standard treatment in people with atopic eczema.

SEARCH METHODS

We searched the following databases up to July 2015: the Cochrane Skin Group Specialised Register, CENTRAL in the Cochrane Library (Issue 7, 2015), MEDLINE (from 1946), EMBASE (from 1974), LILACS (from 1982), Web of Science™ (from 2005), the Global Resource of EczemA Trials (GREAT database), and five trials databases. We searched abstracts from recent European and North American allergy meetings and checked the references of included studies and review articles for further references to relevant trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of specific allergen immunotherapy that used standardised allergen extracts in people with AE.

DATA COLLECTION AND ANALYSIS

Two authors independently undertook study selection, data extraction (including adverse effects), assessment of risk of bias, and analyses. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified 12 RCTs for inclusion in this review; the total number of participants was 733. The interventions included SIT in children and adults allergic to either house dust mite (10 trials), grass pollen, or other inhalant allergens (two trials). They were administered subcutaneously (six trials), sublingually (four trials), orally, or intradermally (two trials). Overall, the risk of bias was moderate, with high loss to follow up and lack of blinding as the main methodological concern.Our primary outcomes were 'Participant- or parent-reported global assessment of disease severity at the end of treatment'; 'Participant- or parent-reported specific symptoms of eczema, by subjective measures'; and 'Adverse events, such as acute episodes of asthma or anaphylaxis'. SCORing Atopic Dermatitis (SCORAD) is a means of measuring the effect of atopic dermatitis by area (A); intensity (B); and subjective measures (C), such as itch and sleeplessness, which we used.For 'Participant- or parent-reported global assessment of disease severity at the end of treatment', one trial (20 participants) found improvement in 7/9 participants (78%) treated with the SIT compared with 3/11 (27%) treated with the placebo (risk ratio (RR) 2.85, 95% confidence interval (CI) 1.02 to 7.96; P = 0.04). Another study (24 participants) found no difference: global disease severity improved in 8/13 participants (62%) treated with the SIT compared with 9/11 (81%) treated with the placebo (RR 0.75, 95% CI 0.45 to 1.26; P = 0.38). We did not perform meta-analysis because of high heterogeneity between these two studies. The quality of the evidence was low.For 'Participant- or parent-reported specific symptoms of eczema, by subjective measures', two trials (184 participants) did not find that the SIT improved SCORAD part C (mean difference (MD) -0.74, 95% CI -1.98 to 0.50) or sleep disturbance (MD -0.49, 95% CI -1.03 to 0.06) more than placebo. For SCORAD part C itch severity, these two trials (184 participants) did not find that the SIT improved itch (MD -0.24, 95% CI -1.00 to 0.52). One other non-blinded study (60 participants) found that the SIT reduced itch compared with no treatment (MD -4.20, 95% CI -3.69 to -4.71) and reduced the participants' overall symptoms (P < 0.01), but we could not pool these three studies due to high heterogeneity. The quality of the evidence was very low.Seven trials reported systemic adverse reactions: 18/282 participants (6.4%) treated with the SIT had a systemic reaction compared with 15/210 (7.1%) with no treatment (RR 0.78, 95% CI 0.41 to 1.49; the quality of the evidence was moderate). The same seven trials reported local adverse reactions: 90/280 participants (32.1%) treated with the SIT had a local reaction compared with 44/204 (21.6%) in the no treatment group (RR 1.27, 95% CI 0.89 to 1.81). As these had the same study limitations, we deemed the quality of the evidence to also be moderate.Of our secondary outcomes, there was a significant improvement in 'Investigator- or physician-rated global assessment of disease severity at the end of treatment' (six trials, 262 participants; RR 1.48, 95% CI 1.16 to 1.88). None of the studies reported our secondary outcome 'Parent- or participant-rated eczema severity assessed using a published scale', but two studies (n = 184), which have been mentioned above, used SCORAD part C, which we included as our primary outcome 'Participant- or parent-reported specific symptoms of eczema, by subjective measures'.Our findings were generally inconclusive because of the small number of studies. We were unable to determine by subgroup analyses a particular type of allergen or a particular age or level of disease severity where allergen immunotherapy was more successful. We were also unable to determine whether sublingual immunotherapy was associated with more local adverse reactions compared with subcutaneous immunotherapy.

AUTHORS' CONCLUSIONS

Overall, the quality of the evidence was low. The low quality was mainly due to the differing results between studies, lack of blinding in some studies, and relatively few studies reporting participant-centred outcome measures. We found limited evidence that SIT may be an effective treatment for people with AE. The treatments used in these trials were not associated with an increased risk of local or systemic reactions. Future studies should use high quality allergen formulations with a proven track record in other allergic conditions and should include participant-reported outcome measures.

Subcutaneous Immunotherapy Improves the Symptomatology of Allergic Rhinitis

Introduction The relevance of allergic rhinitis is unquestionable. This condition affects people's quality of life and its incidence has increased over the last years.

Objective Thus, this study aims to analyze the effectiveness of subcutaneous injectable immunotherapy in cases of nasal itching, sneeze, rhinorrhea and nasal congestion in allergic rhinitis patients.

Methods In the present study, the same researcher analyzed the records of 281 patients. Furthermore, the researchers identified allergens through puncture cutaneous tests using standardized extracts containing acari, fungi, pet hair, flower pollen, and feathers. Then, the patients underwent treatment with subcutaneous specific immunotherapy, using four vaccine vials for desensitization, associated with environmental hygiene. The authors analyzed conditions of nasal itching, sneeze, rhinorrhea, and nasal congestion throughout the treatment, and assigned them with a score ranging from zero (0), meaning absence of these symptoms to three (3), for severe cases. The symptoms were statistically compared in the beginning, during, and after treatment.

Results In this study, authors analyzed the cases distribution according to age and the evolution of symptomatology according to the scores, comparing all phases of treatment. The average score for the entire population studied was 2.08 before treatment and 0.44 at the end. These results represent an overall improvement of ∼79% in symptomatology of allergic rhinitis in the studied population.

Conclusion The subcutaneous immunotherapy as treatment of allergic rhinitis led to a reduction in all symptoms studied, improving the quality of life of patients, proving itself as an important therapeutic tool for these pathological conditions.

Phenotypes and endotypes of rhinitis and their impact on management: a PRACTALL report

Rhinitis is an umbrella term that encompasses many different subtypes, several of which still elude complete characterization. The concept of phenotyping, being the definition of disease subtypes on the basis of clinical presentation, has been well established in the last decade. Classification of rhinitis entities on the basis of phenotypes has facilitated their characterization and has helped practicing clinicians to efficiently approach rhinitis patients. Recently, the concept of endotypes, that is, the definition of disease subtypes on the basis of underlying pathophysiology, has emerged. Phenotypes/endotypes are dynamic, overlapping, and may evolve into one another, thus rendering clear-cut definitions difficult. Nevertheless, a phenotype-/endotype-based classification approach could lead toward the application of stratified and personalized medicine in the rhinitis field. In this PRACTALL document, rhinitis phenotypes and endotypes are described, and rhinitis diagnosis and management approaches focusing on those phenotypes/endotypes are presented and discussed. We emphasize the concept of control-based management, which transcends all rhinitis subtypes.

Randomized, double-blind, placebo-controlled trial of standardized ragweed sublingual-liquid immunotherapy for allergic rhinoconjunctivitis

BACKGROUND

Sublingual immunotherapy with liquid extracts provides an appealing alternative to subcutaneous immunotherapy for the treatment of allergic rhinoconjunctivitis (ARC), but a lack of robust evidence has deterred its use in North America.

OBJECTIVE

To determine the efficacy and tolerability of standardized glycerinated short ragweed sublingual allergen immunotherapy liquid (RW-SAIL) extract in subjects with ragweed-related ARC.

METHODS

This phase 3, randomized, placebo-controlled trial was conducted in North America. Subjects (age range, 18-55 years) with or without asthma were selected based on ARC symptom severity and erythema skin prick reaction to short ragweed. Subjects self-administered the maximum tolerated dose of RW-SAIL (n = 218) or placebo (n = 211) daily beginning approximately 8 to 16 weeks before and through the end of the ragweed pollen season. The primary end point was subject-assessed total combined daily rhinoconjunctivitis symptom and medication scores (TCS).

RESULTS

During the entire season, there was a 43% decrease in TCS in subjects treated with RW-SAIL compared with placebo. Similar decreases were observed in TCS between the 2 groups during peak season (42%) and in daily symptom scores during the entire (42%) and peak (41%) seasons. The occurrence of adverse events was similar between the treatment groups; most were mild in severity. Treatment-related oromucosal local application site reactions occurred early and were transient and self-limited. No anaphylaxis occurred.

CONCLUSIONS

This is the first successful North American confirmatory phase 3 clinical trial to demonstrate the safety and efficacy of a sublingual standardized ragweed allergen immunotherapy liquid extract for the treatment of ARC.

Prerequisites for the pharmaceutical industry to develop and commercialise helminths and helminth-derived product therapy

During the past 10 years, immunologists, epidemiologists and parasitologists have made many new exciting discoveries in the field of helminth-mediated immune regulation. In addition, many animal experiments have shown that certain helminths or products derived from helminths can protect mice from developing allergic or autoimmune disease. Some clinical trials utilising Trichuris suis or Necator americanus for the treatment of allergic disorders and inflammatory bowel disease have been conducted. The outcomes of these trials suggest that they may be used to treat these disorders. However, to date no helminth therapy is routinely being applied to patients and no helminth-derived product therapy has been developed. In order to bring new drugs to the market and shoulder the enormous costs involved in developing such therapies, pharmaceutical companies need to be involved. However, currently the resources from the pharmaceutical industry devoted to this concept are relatively small and there are good reasons why the industry may have been reluctant to invest in developing these types of therapies. In this review article, the hurdles that must be overcome before the pharmaceutical industry might invest in these novel therapies are outlined.

Novel challenges for the allergist

The last years have witnessed novel findings with exciting developments in the field of allergy-related diseases including asthma, bronchial hyperresponsiveness, eczema, and atopy that have enormously increased over the past few years. This issue of the Reviews is timely dedicated to comprehensive articles discussing the current trends in the study of these conditions. In particular, the impact of new data in genomics, environmental factors through epigenetics and proteomics will be reviewed and critically discussed.

MAPK kinase 3 specifically regulates Fc epsilonRI-mediated IL-4 production by mast cells

Mast cells play a central role in allergic inflammation and are activated through cross-linking of FcεRI receptor-bound IgE, initiating a signaling cascade resulting in production of biologically potent mediators. Signaling pathways in the regulation of specific mediators remain incompletely defined. In this study, we examined the role of MAPK kinase 3 (MKK3) in IgE-dependent mast cell activation. In an in vivo model of passive cutaneous anaphylaxis, MKK3-deficient mice showed a deficit in late-phase IgE-dependent inflammation. To characterize the mechanism of this deficiency, we cultured bone marrow-derived mast cells (BMMCs) from wild-type and MKK3-deficient mice. We found that FcεRI-mediated mast cell activation induced rapid MKK3 phosphorylation by 5 min, diminishing slowly after 6 h. In MKK3-deficient BMMCs, phosphorylation of p38 was reduced at early and later time points. Among 40 cytokines tested using a protein array, IL-4 was the only cytokine specifically downregulated in MKK3-deficient BMMCs. Reduced IL-4 expression was seen in the local skin of MKK3-deficient mice following passive cutaneous allergic reaction. Furthermore, early growth response-1 (Egr1) bound to the promoter of IL-4 in FcεRI-activated mast cells, and Egr1 transcription factor activity was diminished in MKK3-deficient BMMCs. Finally, mast cell-deficient mice reconstituted with MKK3-deficient BMMCs displayed a significantly impaired late-phase allergic inflammatory response. Thus, mast cell MKK3 signaling contributes to IgE-dependent allergic inflammation and is a specific regulator of FcεRI-induced IL-4 production.

Management of rhinitis: allergic and non-allergic

RHINITIS IS A GLOBAL PROBLEM AND IS DEFINED AS THE PRESENCE OF AT LEAST ONE OF THE FOLLOWING: congestion, rhinorrhea, sneezing, nasal itching, and nasal obstruction. The two major classifications are allergic and nonallergic rhinitis (NAR). Allergic rhinitis occurs when an allergen is the trigger for the nasal symptoms. NAR is when obstruction and rhinorrhea occurs in relation to nonallergic, noninfectious triggers such as change in the weather, exposure to caustic odors or cigarette smoke, barometric pressure differences, etc. There is a lack of concomitant allergic disease, determined by negative skin prick test for relevant allergens and/or negative allergen-specific antibody tests. Both are highly prevalent diseases that have a significant economic burden on society and negative impact on patient quality of life. Treatment of allergic rhinitis includes allergen avoidance, antihistamines (oral and intranasal), intranasal corticosteroids, intranasal cromones, leukotriene receptor antagonists, and immunotherapy. Occasional systemic corticosteroids and decongestants (oral and topical) are also used. NAR has 8 major subtypes which includes nonallergic rhinopathy (previously known as vasomotor rhinitis), nonallergic rhinitis with eosinophilia, atrophic rhinitis, senile rhinitis, gustatory rhinitis, drug-induced rhinitis, hormonal-induced rhinitis, and cerebral spinal fluid leak. The mainstay of treatment for NAR are intranasal corticosteroids. Topical antihistamines have also been found to be efficacious. Topical anticholinergics such as ipratropium bromide (0.03%) nasal spray are effective in treating rhinorrhea symptoms. Adjunct therapy includes decongestants and nasal saline. Investigational therapies in the treatment of NAR discussed include capsaicin, silver nitrate, and acupuncture.