Effect of specific immunotherapy with house dust mite extract on the bronchial responsiveness of paediatric asthma patients

Efficacy and safety of subcutaneous immunotherapy in asthmatic children allergic to house dust mite: a meta-analysis and systematic review

Background

Subcutaneous immunotherapy (SCIT) has been proved to be effective and safe in adult asthma. But it is still controversial in children.

Object

To evaluate the efficacy and safety of SCIT in asthmatic children with allergy to house dust mite.

Method

We searched the databases of Cochrane Library, EMBASE and MEDLINE (from 1 January 1990 to 1 December 2022). Two reviewers independently screened studies, extracted data and critically appraised the risk of bias. We used the Revman 5 to synthesize the effect sizes.

Results

We finally selected 38 eligible studies including 21 randomized controlled trials to evaluate the efficacy and safety of SCIT and 17 observational studies to assess the safety. The results revealed that short-term asthma symptom scores were declined with a standardized mean difference (SMD) of -1.19 (95% CI: -1.87, -0.50) in 12 researches with high heterogeneity. Short-term asthma medication scores were decreased with SMD -1.04 (95% CI: -1.54, -0.54) in 12 heterogeneous researches. One study showed no significant reduction in combined symptom and medication scores without providing details. No studies we reviewed reported long-term efficacy. SCIT resulted in an obviously increased risk of adverse reactions compared with placebo. For secondary outcomes, SCIT improved life quality and reduced the numbers of annual asthma attacks and allergen-specific airway hyperreactivity, but without significant improvement in pulmonary function, asthma control or hospitalization.

Conclusions

SCIT can reduce the short-term symptom scores and medication scores regardless of different treatment duration or mono/polysensitization, but with an increased incidence of local and systemic adverse effects. Further studies on pediatric asthma are needed to evaluate the long-term efficacy, and clarify the effectiveness of SCIT in specific population using mix allergen extracts or with severe asthma. Overall, it is recommended for children with mild-moderate HDM-driven allergic asthma.

Effect of asthma therapies on the natural course of asthma

OBJECTIVE

To provide an evidence-based review on the role of pharmacologic (inhaled corticosteroids, leukotriene receptor antagonists, biologic therapies, aeroallergen immunotherapy) and nonpharmacologic therapies (environmental modifications, microbiome) in secondary and tertiary asthma prevention.

DATA SOURCES

A PubMed search for English-language publications regarding asthma and secondary or tertiary prevention was performed. Some articles cited in selected studies were also considered for inclusion in this review.

STUDY SELECTIONS

Studies were included that were original research and specifically addressed the question of asthma prevention and use of pharmacologic or nonpharmacologic therapies. When possible, we selected the articles with the most robust level of evidence.

RESULTS

More than 100 articles were initially identified, 79 were reviewed in depth, and 60 were included in this review. Several studies suggest no disease-modifying effect for inhaled corticosteroids. Small studies suggest a tertiary preventive effect for leukotriene receptor antagonists. Biological therapies have somewhat conflicting evidence with a paucity of pediatric data, although some have tremendous promise. A role of allergen immunotherapy (specifically pollen) in secondary asthma prevention has been suggested, with no firm conclusions possible for tertiary prevention. One large trial suggests a role for environmental modifications in secondary asthma prevention, whereas the preponderance of evidence does not suggest a role in tertiary prevention. The microbiome is an active area of research that has promise for a disease-modifying effect.

CONCLUSION

Further work needs to be performed to allow physicians to intervene early and alter the natural course of asthma in children.

Can Serum-Specific IgE/Total IgE Ratio Predict Clinical Response to Allergen-Specific Immunotherapy in Children Monosensitized to House Dust Mite?

Background. Allergen-specific immunotherapy (SIT) is one of the important regimens for the treatment of allergic diseases. Predictive tests for the clinical response to SIT are limited. In this study we aimed to evaluate whether specific IgE/total IgE levels can predict clinical improvement in monosensitized patients to house dust mite treated with immunotherapy. Patients and Methods. We analyzed 32 patients who had undergone 2 years of SIT. Serum t-IgE and s-IgE levels, and serum s-IgE/t-IgE ratios were calculated and tested for correlation with clinical response to SIT. Asthma symptom score (ASS), rhinitis symptom score (RSS), pulmonary functions and visual analogue scales (VAS) were evaluated at the beginning and after 2 years. Results. There were 17 boys and 15 girls with the mean age of 10.78 ± 3.03 years. The mean serum house dust mite s-IgE level was 128.62 ± 142.61 kU/L, t-IgE 608.90 ± 529.98 IU/mL, and s-IgE/t-IgE ratio 33.83 ± 53.18. Before immunotherapy, ASS was 6.23 ± 1.63, RSS; 8.20 ± 1.88, VAS; 7.38 ± 2.01, FEV1 (%); 89.14 ± 8.48, PEF (%); 88.93 ± 13.57, and after 2 years, these values were determined as 1.90 ± 1.10, 3.05 ± 1.39, 1.35 ± 1.24, 97.6 ± 11.26, and 97.0 ± 11.55, respectively. s-IgE/t-IgE ratio was correlated with change in RSS (r = −0.392, P = 0.08) and VAS (r = −0.367, P = 0.05). Conclusion. Although SIT is very effective treatment, all patients do not benefit from treatment. We assumed that s-IgE/t-IgE ratio would be useful to predict the clinical response to SIT.

The role of immunotherapy in the management of childhood asthma

Subcutaneous immunotherapy (SCIT) is still questioned as a safe and efficacious way of treating allergic asthma in children. In a Cochrane review published in 2010 it was, however, concluded that SCIT has significant and beneficial effects on symptoms and medication use in both children and adults with mostly mild asthma. Only a few studies have been performed to specifically study if SCIT in children with moderate asthma reduces the need for inhaled corticosteroids. There are conflicting results that illustrate the problem of the heterogeneity of the asthma disease and the fact that allergies may play different roles on the severity and symptoms of the disease. Furthermore, children with severe allergic asthma are often sensitized to multiple allergens, which makes SCIT both complicated and less safe to administer. On the other hand, if the child suffers from asthmatic symptoms despite adherence to pharmacotherapy, omalizumab or a combination of omalizumab and allergen immunotherapy might be useful. There is a need for more studies on this combination before it can be considered as an additional therapy in children with asthma and severe allergies. Sublingual immunotherapy (SLIT) has also been shown to improve asthma symptoms and medication use. SLIT is safe although its efficacy compared with SCIT has been studied very little. Another approach is to try to prevent asthma by treating children with SCIT for allergic rhinoconjunctivitis before asthma has developed. The most attractive prospect, however, is to find ways of preventing asthma by vaccination against the most common viruses, particularly rhinovirus. There is evidence that there are children at high risk of developing asthma in whom a viral infection can also enhance the risk of allergen sensitization. So far this vaccination has not been achievable although research is in progress.

Effect of allergen-specific immunotherapy with purified Alt a1 on AMP responsiveness, exhaled nitric oxide and exhaled breath condensate pH: a randomized double blind study

Background

Little information is available on the effect of allergen-specific immunotherapy on airway responsiveness and markers in exhaled air. The aims of this study were to assess the safety of immunotherapy with purified natural Alt a1 and its effect on airway responsiveness to direct and indirect bronchoconstrictor agents and markers in exhaled air.

Methods

This was a randomized double-blind trial. Subjects with allergic rhinitis with or without mild/moderate asthma sensitized to A alternata and who also had a positive skin prick test to Alt a1 were randomized to treatment with placebo (n = 18) or purified natural Alt a1 (n = 22) subcutaneously for 12 months. Bronchial responsiveness to adenosine 5'-monophosphate (AMP) and methacholine, exhaled nitric oxide (ENO), exhaled breath condensate (EBC) pH, and serum Alt a1-specific IgG₄ antibodies were measured at baseline and after 6 and 12 months of treatment. Local and systemic adverse events were also registered.

Results

The mean (95% CI) allergen-specific IgG₄ value for the active treatment group increased from 0.07 μg/mL (0.03-0.11) at baseline to 1.21 μg/mL (0.69-1.73, P < 0.001) at 6 months and to 1.62 μg/mL (1.02-2.22, P < 0.001) at 12 months of treatment. In the placebo group, IgG₄ value increased nonsignificantly from 0.09 μg/mL (0.06-0.12) at baseline to 0.13 μg/mL (0.07-0.18) at 6 months and to 0.11 μg/mL (0.07-0.15) at 12 months of treatment. Changes in the active treatment group were significantly higher than in the placebo group both at 6 months (P < 0.001) and at 12 months of treatment (P < 0.0001). However, changes in AMP and methacholine responsiveness, ENO and EBC pH levels were not significantly different between treatment groups. The overall incidence of adverse events was comparable between the treatment groups.

Conclusion

Although allergen-specific immunotherapy with purified natural Alt a1 is well tolerated and induces an allergen-specific IgG₄ response, treatment is not associated with changes in AMP or methacholine responsiveness or with significant improvements in markers of inflammation in exhaled air. These findings suggest dissociation between the immunotherapy-induced increase in IgG₄ levels and its effect on airway responsiveness and inflammation.

Injection allergen immunotherapy for asthma

BACKGROUND

Allergen specific immunotherapy has long been a controversial treatment for asthma. Although beneficial effects upon clinically relevant outcomes have been demonstrated in randomised controlled trials, there remains a risk of severe and sometimes fatal anaphylaxis. The recommendations of professional bodies have ranged from cautious acceptance to outright dismissal. With increasing interest in new allergen preparations and methods of delivery, we updated the systematic review of allergen specific immunotherapy for asthma.

OBJECTIVES

The objective of this review was to assess the effects of allergen specific immunotherapy for asthma.

SEARCH STRATEGY

We searched the Cochrane Airways Group Trials Register up to 2005, Dissertation Abstracts and Current Contents.

SELECTION CRITERIA

Randomised controlled trials using various forms of allergen specific immunotherapy to treat asthma and reporting at least one clinical outcome.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed eligibility of studies for inclusion. Two authors independently performed quality assessment of studies.

MAIN RESULTS

Eighty-eight trials were included (13 new trials). There were 42 trials of immunotherapy for house mite allergy; 27 pollen allergy trials; 10 animal dander allergy trials; two Cladosporium mould allergy, two latex and six trials looking at multiple allergens. Concealment of allocation was assessed as clearly adequate in only 16 of these trials. Significant heterogeneity was present in a number of comparisons. Overall, there was a significant reduction in asthma symptoms and medication, and improvement in bronchial hyper-reactivity following immunotherapy. There was a significant improvement in asthma symptom scores (standardised mean difference -0.59, 95% confidence interval -0.83 to -0.35) and it would have been necessary to treat three patients (95% CI 3 to 5) with immunotherapy to avoid one deterioration in asthma symptoms. Overall it would have been necessary to treat four patients (95% CI 3 to 6) with immunotherapy to avoid one requiring increased medication. Allergen immunotherapy significantly reduced allergen specific bronchial hyper-reactivity, with some reduction in non-specific bronchial hyper-reactivity as well. There was no consistent effect on lung function. If 16 patients were treated with immunotherapy, one would be expected to develop a local adverse reaction. If nine patients were treated with immunotherapy, one would be expected to develop a systemic reaction (of any severity).

AUTHORS' CONCLUSIONS

Immunotherapy reduces asthma symptoms and use of asthma medications and improves bronchial hyper-reactivity. One trial found that the size of the benefit is possibly comparable to inhaled steroids. The possibility of local or systemic adverse effects (such as anaphylaxis) must be considered.

New visions in specific immunotherapy in children: an iPAC summary and future trends

Specific immunotherapy is indicated for confirmed immunoglobulin E-mediated airway diseases using standardized allergen products with documented clinical efficacy and safety. For decades the subcutaneous route of administration (SCIT) has been the gold standard. Recently, the sublingual immunotherapy (SLIT) has also been investigated in children. SCIT, especially with grass and birch pollens but also house dust mites, is an effective treatment in children with allergic rhinitis and asthma when a significant part of their symptoms are caused by these allergens. A long-term effect up to 12 yr after discontinuation of SCIT with timothy allergen has been shown. Efficacy and safety of SLIT in pollen allergic rhinoconjunctivitis have been demonstrated in adults. The evidence in children is a little less convincing, and more data is needed. The clinical relevance, long-term results and the size of the effect, as well as the dose, the treatment regimen and duration has not been sufficiently elaborated. It is demonstrated that SCIT has the potential for preventing the development of asthma in children with allergic rhinoconjunctivitis. Also one randomized study indicates a preventive effect of SLIT in children on the development of asthma. At present, there are no studies who clearly demonstrates either a long-term effect or a preventive effect on the development of asthma of SLIT in children. The areas with lack of evidence should be addressed in well performed prospective, randomized long-term studies both with SCIT and SLIT. This review was initiated by iPAC (international Pediatric Allergy and Asthma Consortium) and aims to review current knowledge related to specific immunotherapy in childhood, and to identify needs for future research in this field.

Specific immunotherapy is effective in the prevention of new sensitivities

BACKGROUND

Allergen specific immunotherapy is the only specific and curative approach in the treatment of IgE-mediated allergic diseases such as bronchial asthma and allergic rhinitis. The safety and clinical efficacy of this treatment are well documented but data on the prevention of new sensitizations remain scarce.

OBJECTIVE

To demonstrate the efficacy of specific immunotherapy in allergic respiratory diseases in childhood and to determine whether this treatment prevents the development of new sensitizations in children sensitized to house dust mite or pollen species.

METHODS

Fifty-six patients received specific immunotherapy (43 sensitive to house dust mite and 13 sensitive to pollen). Fifty-one patients not receiving immunotherapy but treated with pharmacotherapy were enrolled in the control group. The patients were followed-up for at least 4 years and treatment efficacy and the development of new sensitizations were compared between the two groups.

RESULTS

The number of patients with symptoms was significantly decreased in both groups at the end of the treatment period. No new sensitizations were found in 35 of the 43 (81.39 %) patients in the house dust mite immunotherapy group and in 10 of 13 (76.92 %) patients in the pollen immunotherapy group. In contrast, 20 of 51 (39.21 %) patients in the control group showed new sensitizations. The difference between the house dust mite and pollen immunotherapy groups and the control group in this parameter was statistically significant (p = 0.033).

CONCLUSION

Our data demonstrate that administration of specific immunotherapy in allergic patients significantly reduced symptoms and the development of new sensitivities.

Assessment of sublingual immunotherapy efficacy in children with house dust mite-induced allergic asthma optimally controlled by pharmacologic treatment and mite-avoidance measures

Although several studies have demonstrated the efficacy of subcutaneous immunotherapy in allergic asthma, few have shown the same benefit using sublingual immunotherapy (SLIT) in asthmatic patients. This study was conducted to assess the efficacy of house dust mite (HDM) SLIT in addition to allergen avoidance and standard pharmacologic treatment. A double-blind, placebo-controlled trial was performed in 111 children (aged 5-15 yr) with HDM-induced mild-to-moderate asthma. After a 4-week baseline phase, patients were randomly assigned to receive SLIT with tablets of HDM extract (n = 55) or placebo (n = 56) for 18 months. Pharmacologic treatment was adjusted every 3 months following a step-down approach. Asthma symptom scores, reduction in use of inhaled corticosteroids and inhaled beta(2)-agonists, rhinitis symptoms, lung function tests, skin sensitivity to HDM, dust mite-specific immunoglobulin (Ig) E and IgG(4), and quality of life (QoL) were assessed during the study. After 18 months of treatment, diurnal and nocturnal asthma symptoms scores did not show significant differences between SLIT and placebo groups. Inhaled corticosteroids and inhaled beta(2)-agonists use was reduced in both groups without significant differences between groups. There were no significant differences in lung function (forced expiratory volume in 1 s and peak flow rate variations) between groups. Rhinitis symptom score decreased in both groups, with no difference between the two groups. The severity dimension of QoL was significantly improved in the SLIT group (age 6-12 yr). SLIT induced a significant reduction of skin sensitivity to HDM (p < 0.01) and a significant increase in HDM-specific IgE and IgG(4) antibodies (p < 0.001) in the SLIT group compared with the placebo group. SLIT was well tolerated with mild/moderate local adverse events. No severe systemic reactions were reported. This study indicates that, when mild-moderate asthmatic children are optimally controlled by pharmacologic treatment and HDM avoidance, SLIT does not provide additional benefit, despite a significant reduction in allergic response to HDM. Under such conditions, only a complete, but ethically unfeasible, discontinuation of inhaled corticosteroid would have demonstrated a possible benefit of SLIT.

Immunotherapy in children

PURPOSE OF REVIEW

Specific allergen immunotherapy although being performed for almost 100 years, is still being addressed in clinical trials. In children the sublingual allergen application has gained considerable interest.

RECENT FINDINGS

Controlled long-term trials suggest that specific allergen immunotherapy has the capacity to modify the natural history of allergic airway disease by reducing the incidence of new sensitivities non-specifically, reducing allergic symptoms years after discontinuation and preventing the incidence of asthma. The current evidence on sublingual immunotherapy is not sufficient to recommend this mode of treatment in clinical practice yet.

SUMMARY

Specific allergen immunotherapy should be considered in children in whom IgE-mediated allergic symptoms cannot be adequately controlled by symptomatic treatment.

Immunological mechanisms in specific immunotherapy

Specific immunotherapy (SIT) represents the only curative treatment of allergy and is, therefore, of particular interest for immunological and pharmacological research. The current understanding of immunological mechanisms underlying SIT focuses on regulatory T cells (T regs), which balance Th1 and Th2 effector functions. This ensures that allergens are recognized, but tolerated by the immune system. There is clear evidence that SIT restores the disturbed balance of T regs and effector cells in allergic patients. Current efforts are focused to improve SIT regimens to make them more applicable in atopy and asthma. The current review provides an overview on the mechanisms of SIT and possible adjuvant treatment strategies on the background of the T reg concept.

Allergen immunotherapy for asthma

BACKGROUND

Allergen specific immunotherapy has long been a controversial treatment for asthma. Although beneficial effects upon clinically relevant outcomes have been demonstrated in randomised controlled trials, there remains a risk of severe and sometimes fatal anaphylaxis. The recommendations of professional bodies have ranged from cautious acceptance to outright dismissal. With increasing interest in new allergen preparations and new methods of delivery, it was time to conduct another systematic review of allergen specific immunotherapy for asthma.

OBJECTIVES

The objective of this review was to assess the effects of allergen specific immunotherapy for asthma.

SEARCH STRATEGY

We searched the Cochrane Airways Group trials register up to June 2001, MEDLINE, Dissertation Abstracts, Current Contents and reference lists of articles.

SELECTION CRITERIA

Randomised controlled trials using various forms of allergen specific immunotherapy to treat asthma and reporting at least one clinical outcome.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed eligibility of studies for inclusion. Two reviewers independently performed quality assessment of studies.

MAIN RESULTS

Seventy-five trials were included (52 of 54 previously included trials and 23 new trials). A total of 3,506 participants (3,188 with asthma) were involved. There were 36 trials of immunotherapy for house mite allergy; 20 pollen allergy trials; ten animal dander allergy trials; two Cladosporium mould allergy, one latex and six trials looking at multiple allergens. Concealment of allocation was assessed as clearly adequate in only 15 of these trials. Significant heterogeneity was present in a number of comparisons. Overall, there was a significant reduction in asthma symptoms and medication and improvement in bronchial hyper-reactivity following immunotherapy. There was a significant improvement in asthma symptom scores (standardised mean difference -0.72, 95% confidence interval -0.99 to -0.33) and it would have been necessary to treat 4 (95%CI 3 to 5) patients with immunotherapy to avoid one deterioration in asthma symptoms. Overall it would have been necessary to treat 5 (95%CI 4 to 6) patients with immunotherapy to avoid one requiring increased medication. Allergen immunotherapy significantly reduced allergen specific bronchial hyper-reactivity, with some reduction in non-specific bronchial hyper-reactivity as well. There was no consistent effect on lung function.

REVIEWER'S CONCLUSIONS

Immunotherapy reduces asthma symptoms and use of asthma medications and improves bronchial hyper-reactivity. One trial found that the size of the benefit is possibly comparable to inhaled steroids. The possibility of adverse effects (such as anaphylaxis) must be considered.

Benefits of immunotherapy with a standardized Dermatophagoides pteronyssinus extract in asthmatic children: a three-year prospective study

BACKGROUND

Although widely practiced for over 80 years, the role of specific immunotherapy (SIT) in pediatric asthma treatment is still controversial. We assessed the effects of a 3-year period of subcutaneous administration of a standardized preparation of Dermatophagoides pteronyssinus (D pt) on the respiratory health in a group of asthmatic children monosensitized to house dust mite (HDM).

METHODS

A randomized clinical trial was performed after 1-year run-in period. Fifteen children receiving SIT for HDM and 14 controls (four drop-outs), matched for age, allergen sensitization, asthma severity, lung function, and non-specific bronchial reactivity (BHR), were studied during the 3-year treatment period. During the whole trial, respiratory symptoms, pharmacological and respiratory function parameters were regularly evaluated. Skin prick tests and methacholine challenge were performed at the beginning and end of the study.

RESULTS

In the SIT group significant improvement in asthmatic symptoms and marked reduction in drug intake was observed. The SIT group also showed a significant decrease in non-specific bronchial BHR. No new sensitivity occurred during the study period in the SIT group only. No major local or systemic side-effects were reported during the study.

CONCLUSIONS

Our results confirm that SIT is effective in asthmatic children sensitive to mites. It is associated with a decrease in BHR and it may prevent the development of new sensitizations in monosensitized subjects.

Safety evaluation of a glutaraldehyde modified tyrosine adsorbed housedust mite extract containing monophosphoryl lipid A (MPL) adjuvant: a new allergy vaccine for dust mite allergy

A new allergy vaccine is currently under clinical evaluation for the prevention or relief of symptoms caused by specific housedust mites. It consists of a 50:50 mixture of the mite Dermatophagoides pteronyssinus and D. farinae protein derived from aqueous extracts of the mites which is chemically modified by glutaraldehyde and adsorbed onto L-tyrosine with addition of the immunostimulatory adjuvant, monophosphoryl lipid A (MPL) "Polymite". A specific preclinical safety testing strategy was developed to support clinical use and comprised single and repeat dose toxicity, reproduction toxicity and local tolerance studies. Dose levels of up to 0.5ml for the mouse and up to 1ml for both the rat and the rabbit were used. Overall, the product was shown to produce no toxicological findings of significance at levels greatly in excess to those proposed for clinical use. A not unexpected, but relatively minor, immunostimulatory effect was seen following repeated dosing (once weekly for 13 weeks) at 1ml per rat; the Polymite formulation also resulted in injection site reaction which can largely be attributed to the presence of tyrosine. No reproduction toxicity was found.

Prevention of new sensitizations in asthmatic children monosensitized to house dust mite by specific immunotherapy. A six-year follow-up study

BACKGROUND

Specific immunotherapy (SIT) is a recognized way of treating IgE-mediated respiratory diseases. The clinical outcome is usually better in allergic children than in adults.

OBJECTIVE

To increase our knowledge of the ability of SIT to prevent the onset of new sensitizations in monosensitized subjects, so far poorly documented.

METHODS

134 children (age range 5-8 years), who had intermittent asthma with or without rhinitis, with single sensitization to mite allergen (skin prick test and serum-specific IgE), were enrolled. SIT was proposed to all the children's parents, but was accepted by only 75 of them (SIT Group). The remaining 63 children were treated with medication only, and were considered the Control Group. Injective SIT with mite mix was administered to the SIT Group during the first three years and all patients were followed for a total of 6 years. All patients were checked for allergic sensitization(s) by skin prick test and serum-specific IgE every year until the end of the follow-up period.

RESULTS

Both groups were comparable in terms of age, sex and disease characteristics. 123 children completed the follow-up study. At the end of the study, 52 out of 69 children (75.4%) in the SIT Group showed no new sensitization, compared to 18 out of 54 children (33.3%) in the Control Group (P < 0.0002). Parietaria, Gramineae and Olea were the most common allergens responsible for the new sensitization(s).

CONCLUSIONS

According to our data, SIT may prevent the onset of new sensitizations in children with respiratory symptoms monosensitized to house dust mite (HDM).

Immunotherapy in bronchial asthma

The incidence and prevalence of allergic diseases are constantly increasing in our times. The only etiologic treatments currently available are allergen avoidance and immunotherapy. Many scientific data demonstrate that immunotherapy with allergens is an effective and safe treatment for allergic rhinitis and asthma in adequately selected patients and that it reduces treatment costs for the patients in the long run. Other promising aspects of immunotherapy are its capacity to produce prolonged clinical remissions over time, that it is the only treatment capable of stopping the natural development of the respiratory allergic disease, and the possibility that immunotherapy could avoid evolution to asthma in a significant percent of patients with rhinitis.