Allergen Immunotherapy for Pediatric Asthma

Current Evidence and Knowledge Gaps

Giovanni Passalacqua; Massimo Landi; Diego G. Peroni

Disclosures

Curr Opin Allergy Clin Immunol. 2020;20(2):162-167. 

In This Article

Abstract and Introduction

Abstract

Purpose of review: The introduction of high-quality and standardized extracts for immunotherapy has renewed the interest in the treatment of pediatric allergic asthma that represents a high-prevalence disease.

Recent findings: In addition to clinical trials, several systematic reviews and metaanalyses were published, confirming overall the clinical efficacy of allergen immunotherapy in pediatric asthma. In addition, new data on the preventive effect of the treatment on asthma onset were published. Despite this, many intriguing questions emerged, in parallel to the development of knowledge.

Summary: Allergen immunotherapy is overall effective for the treatment of asthma in children, but a class-effect should not be claimed, rather the efficacy of each single product. According to the recent findings, the challenge for the future research will be to clarify: when to start immunotherapy in children, which are (if they exist) the predictive biomarkers for efficacy in the single individual, the magnitude of the preventive effect and the optimal duration of the treatment.

Introduction

Asthma, especially in its allergic form is a high-prevalence disease, in particular in the pediatric age, where age-specific issues with diagnosis and management emerge. It is acknowledged that asthma is a heterogeneous disease,[1] but in the pediatric age allergic asthma is the most common presentation.[2–4] This is a typical type-2 high asthma phenotype characterized by early onset, atopic background and family history of atopy, IgE sensitization to aeroallergens, and a Th2-driven inflammation.[5]

Allergen-specific immunotherapy (AIT), introduced more than one century ago on an empirical basis, is a 'biological response modifier,' capable to interfere with and to modulate the specific Th2 response to allergens. This results in a wide array of mechanisms including: induction of regulatory T cells; secretion of allergen-specific IgG4 which can compete with the IgE-mediated antigen presentation; reduction in IgE-mediated mast-cell activation (for review, see[6]). Recently, also B cells and innate lymphoid cells 2 appeared to be involved in the mechanisms of action of AIT.[7]

It is believed that as earlier is the application of AIT as greater are the benefits obtained. Thus, the pediatric age would seem to be the optimal time frame to use this therapeutic approach. Indeed, there are numerous experimental evidences showing that AIT is effective (reduction in symptoms and rescue medication use) for respiratory allergy in children, but the majority of the clinical trials were conducted with rhinitis as the main outcome. In the pediatric studies of AIT, asthma has ever been evaluated as a secondary outcome (subgroups of rhinitis children who had also concomitant asthma). Metaanalyses about the efficacy of AIT in asthmatic children are also available, but they are distorted by the great heterogeneity of the included studies. Another interesting aspect in children is the possibility to prevent the evolution of the allergic respiratory disease, from rhinitis to asthma. Indeed, there is experimental evidence suggesting the preventive effect of AIT. Although there is evidence that AIT can modulate and improve asthma in children, there are many unsolved questions in this context that still need to be elucidated.[8] We will review herein the main experimental evidence about the use of AIT in pediatric asthma and will also review the main knowledge gaps in this context.

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....