Validated allergen exposure chamber is plausible tool for the assessment of house dust mite-triggered allergic rhinitis

Comparative Evaluation of an Allergen Exposure Chamber and Nasal Allergen Challenge Versus In-Field Symptom Assessment in Patients With Allergic Rhinitis Triggered by Timothy Grass Pollen

BACKGROUND

An allergen exposure chamber (AEC) is a specialized medical facility designed to expose individuals to allergens at precise and consistent concentrations within a controlled environment. This study aimed to correlate the assessment of clinical endpoints in patients with allergic rhinitis sensitized to timothy grass pollen (Phleum pratense) by comparing three different methods: AEC, nasal allergen challenge (NAC), and symptoms during natural exposure during the grass pollen season.

METHODS

Fifteen allergic subjects and twelve healthy controls were evaluated in the ALLEC AEC; allergic symptoms were measured by subjective and objective methods, including total nasal symptom score (TNSS), acoustic rhinometry (AcR), peak nasal inspiratory flow (PNIF), and nasal discharge amount. For the in-field evaluation, a combined symptom medication score (EAACI-CSMS), as proposed by the European Academy of Allergy and Clinical Immunology (EAACI), was used, which was assessed for 14 days during the peak of the pollen season. The AcR, PNIF, and TNSS were used for the NAC assessment.

RESULTS

Both in the AEC and NAC, all allergic individuals developed symptoms at the optimal pollen/allergen concentration across all the measured endpoints. Using Spearman's rank correlation coefficient (p < 0.05), the analysis revealed significant correlations between symptoms assessed in AEC at 120 min of the challenge, as well as in NAC after 15 min with the EAACI-CSMS in-field. The correlations between in-field assessment and AEC were stronger than those with NAC, which showed weaker or no significant correlations. This indicates that the AEC challenge correlates better with in-field assessments than NAC.

CONCLUSION

Clinical endpoints assessed to allergen exposure in the AEC and NAC significantly correspond to the efficacy analysis in-field (EAACI-CSMS during the peak of pollen exposure). The effect of NAC was not significant for all outcomes measured. Both methods might be considered to be an alternative to traditional assessment during natural exposure.

Questionnaire for Clinical Diagnosis of House Dust Mite's Allergy Approved by Delphi Consensus

Despite house dust mite (HDM)-allergy is the most frequent in the world, no standard questionnaire exists to help physicians in their clinical practice for screening patients with this possible diagnosis. The objective of this survey was to develop a questionnaire that could be used to identify patients with suspicion of HDM-allergy. The survey was conducted using the Delphi methodology. Nineteen international experts in allergology constituted the scientific board who established the items included in the first version of the questionnaire, defined the criteria of the selection for the next steps, and validated the final questionnaire and its interpretation. The initial version of the questionnaire included 15 items. For each item, five answers were suggested graduated by scores from "no importance" to "very high importance." The predefined conditions for the item selection after each round were a median score ≥ 7 and > 50% of responses according "high importance" and "very high importance." The electronic survey circulated within the Interasma Scientific Network platform. Eight questions based on the occurrence/worsening of symptoms induced by HDM-allergen exposure meet the survey criteria after the second and the third rounds and were included in the final questionnaire. Binomial answers for each question with 1 point accorded for "Yes" and none for "No" were suggested for the final version with a score ≥ 5 points associated with a high probability for HDM-allergy. By applying the Delphi process, we generated a brief questionnaire with binomial answers, easy to use in clinical practice for screening patients with HDM-allergy.

A Modern Approach to Clinical Outcome Assessment in Allergy Management: Advantages of Allergen Exposure Chambers

Allergic diseases triggered by airborne allergens such as allergic rhinitis and conjunctivitis are increasingly prevalent, posing significant challenges for both patients and healthcare systems. Assessing the efficacy of allergen immunotherapy and other anti-allergic treatments requires precise and reproducible methods. Allergen exposure chambers (AECs) have emerged as advanced tools for evaluating clinical outcomes, offering controlled conditions that address many limitations of traditional field-based studies. This review explores the advantages of AECs in allergy management, emphasizing their role in providing standardized allergen exposure for both clinical research and routine assessments. AECs deliver consistent and reproducible data comparable to the nasal allergen challenge and natural allergen exposure, making them a valuable addition to the diagnosis and treatment effectiveness of allergic diseases. Although they are well suited to early-stage clinical trials, further standardization and validation are needed to gain broader acceptance in pivotal phase III studies. Future research should focus on refining AEC protocols and integrating them into regulatory frameworks, ensuring their role in the advancement of therapeutic approaches for allergic diseases.

Clinical validation of grass pollen exposure chamber in patients with allergic rhinitis triggered by timothy grass

BACKGROUND

The fluctuation in concentrations of airborne allergens frequently presents a challenge to assessing the efficacy of allergen immunotherapy (AIT) in 'field' studies. Allergen exposure chambers (AECs) are specialized medical installations developed to expose individuals to allergens at defined and consistent concentrations under a controlled environment. The aim of the study was to validate the provocation test with timothy grass pollen as well as to assess its safety in the AEC in patients with allergic rhinitis.

METHODS

In the ALLEC® AEC, varying concentrations of timothy grass pollen were dispersed. Allergic symptoms were measured by total nasal symptom score (TNSS), acoustic rhinometry, peak nasal inspiratory flow (PNIF) and nasal discharge volume. Lung function, assessed through peak expiratory flow rate (PEFR) and forced expiratory volume in the first second (FEV1), was used to evaluate safety.

RESULTS

The consistency of the test was proved by the stability of environmental conditions, including temperature, humidity and CO2 levels, as well as constant concentrations of grass pollen at predetermined levels ranging from 1000 to 10,000 particles per cubic meter (p/m3). Allergic individuals developed symptoms at concentrations of 3000 p/m3 and above, across all measured endpoints. Lung function was not affected throughout all the challenges. The reproducibility of symptoms was confirmed throughout the tests. The concentration of 8000 p/m3 together with a challenge duration of 120 min was found to be optimal.

CONCLUSION

The study demonstrates that the ALLEC® grass pollen exposure chamber provides a reliable and safe method for inducing repeatable symptoms in patients with allergic rhinitis. This approach can be effectively applied for allergy diagnostics and clinical endpoint determination during AIT.

Hot topics in allergen immunotherapy, 2023: Current status and future perspective

The importance of allergen immunotherapy (AIT) is multifaceted, encompassing both clinical and quality-of-life improvements and cost-effectiveness in the long term. Key mechanisms of allergen tolerance induced by AIT include changes in memory type allergen-specific T- and B-cell responses towards a regulatory phenotype with decreased Type 2 responses, suppression of allergen-specific IgE and increased IgG1 and IgG4, decreased mast cell and eosinophil numbers in allergic tissues and increased activation thresholds. The potential of novel patient enrolment strategies for AIT is taking into account recent advances in biomarkers discoveries, molecular allergy diagnostics and mobile health applications contributing to a personalized approach enhancement that can increase AIT efficacy and compliance. Artificial intelligence can help manage and interpret complex and heterogeneous data, including big data from omics and non-omics research, potentially predict disease subtypes, identify biomarkers and monitor patient responses to AIT. Novel AIT preparations, such as synthetic compounds, innovative carrier systems and adjuvants, are also of great promise. Advances in clinical trial models, including adaptive, complex and hybrid designs as well as real-world evidence, allow more flexibility and cost reduction. The analyses of AIT cost-effectiveness show a clear long-term advantage compared to pharmacotherapy. Important research questions, such as defining clinical endpoints, biomarkers of patient selection and efficacy, mechanisms and the modulation of the placebo effect and alternatives to conventional field trials, including allergen exposure chamber studies are still to be elucidated. This review demonstrates that AIT is still in its growth phase and shows immense development prospects.

Immunological mechanisms of tolerance: Central, peripheral and the role of T and B cells

T and B cells are key components of the adaptive immune system. Through their immune properties and their interactions with other immune cells and cytokines around them, they build a complex network to achieve immune tolerance and maintain homeostasis of the body. This is achieved through mechanisms of central and peripheral tolerance, both of which are associated with advantages and disadvantages. For this reason, the immune system is tightly regulated and their dysregulation can result in the subsequent initiation of various diseases. In this review, we will summarize the roles played by T cells and B cells within immune tolerance with specific examples in the context of different diseases that include allergic disease. In addition, we will also provide an overview on their suitability as biomarkers of allergen-specific immunotherapy.

Sodium Chloride versus Lactose as a Carrier for House Dust Mite Allergen in Allergen Chamber Studies: A Clinical Study to Assess Noninferiority

INTRODUCTION

In the Fraunhofer allergen challenge chamber (ACC), a standardized, universal, good manufacturing practice-conforming technology using a spray dried solution of lactose (L) and allergen extract has been established. In this study, we investigated the noninferiority of hypertonic sodium chloride (S) versus L as a carrier for house dust mite (HDM) allergen to simplify manufacturing, reduce costs, and allow for wider use.

METHODS

Using a participant-blinded, sham exposure-controlled, single-arm, sequential intervention study, we challenged adults with HDM allergic rhinitis five times in the ACC. Participants were first exposed to S, L, and clean air (block 1), followed by S + HDM and L + HDM (block 2). Primary endpoints were mean total nasal symptom score (TNSS) and mean nasal secretion weight.

RESULTS

19 participants were enrolled in the study (10 females; mean age 32 years [22-49], 4 with mild allergic asthma). The safety profile of S + HDM and L + HDM was similar; eight participants experienced mild procedure-related adverse events including tiredness, cough, and dyspnea. Due to dropouts, 13 participants completed the study and were evaluated. Mean TNSS and nasal secretion were as follows: S 0.98, 0.28 g; L 1.1, 0.20 g; clean air 1.1, 0.23 g; S + HDM 5.7, 4.8 g; L + HDM 5.1, 5.1 g. Separate block 1/block 2 MANOVAs with TNSS and nasal secretion as dependent variables revealed no significant differences between the carriers, neither alone and compared with clean air (p = 0.2059, Wilk's λ = 0.78) nor combined with HDM (p = 0.3474, Wilk's λ = 0.89). Noninferiority of S was established using a meta-analysis-based minimal clinical important difference of -0.55: mean TNSS difference between S + HDM and L + HDM was 0.62 (90% CI: -0.51 to 1.74).

CONCLUSION

S as an HDM carrier was safe and well tolerated. It was noninferior to L which makes it an adequate and easy-to-use carrier substitute.