NCT05042830

Contribution of Nasal IgE Production to the Boost of Systemic Allergen-specific IgE Upon Nasal Allergen Contact

Contribution of Local Nasal IgE Production to the Boost of Systemic Allergen-specific IgE Production Upon Nasal Allergen Contact - an Explorative Pilot Study

• Status: Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 30 (estimated)
• Sponsor: Medical University of Vienna · Academic / Other
• Sex: All
• Age: 18 Years – 60 Years
• Healthy volunteers: Not accepted

Summary

IgE-associated allergies are consistently on the rise forming an enormous wellbeing concern and affecting about 25% of the population around the world, with main prevalence in developed nations. Birch pollen is one important allergen driving allergic conjunctivitis and rhinitis. The characteristics and location IgE producing cells in the nose and their contribution to the subsequent increase in allergen-specific IgE levels in the serum have so far poorly been investigated. Understanding these mechanisms is critical for the development of new therapeutic approaches and is thus the aim of the proposed study. Thus, the investigators plan to conduct a two-armed study of a randomized placebo-controlled double-blind nasal allergen provocation where 30 patients will be provoked with birch pollen extract (n=20) or placebo (n=10) out of the birch pollen season (October) and follow them closely for up to 4 months. Therefore, the objective of this study is to investigate the localization and characteristics of IgE producing cells in the nasal mucosa contributing to the allergen-induced boosts of specific serum IgE upon natural and controlled nasal allergen exposure.

Detailed description

The nose represents an important and first site of allergen contact, both because it is the organ most frequently affected by allergic symptoms and also because it plays an important role for the regulation of IgE production and allergic inflammation. The nasal mucosa acts as a barrier against intruding allergens. This barrier function can be perturbed by various factors such as cigarette smoke, rhinovirus infection or interferon-γ. Exposure to these factors may lead to increased allergen penetration. Nasal allergen contact in sensitized subjects leads to allergic nasal inflammation and symptoms. The investigators of this study have previously demonstrated that allergen-specific IgE levels in sensitized individuals are strongly boosted upon nasal allergen contact during the relevant allergen season or in well controlled intranasal allergen challenge models. This allergen-induced rise in IgE levels consequently leads to increased sensitivity of allergic patients in terms of IgE-mediated mast cell and basophil activation as well as IgE-facilitated antigen presentation via the high (FcεRI) or low (CD23) affinity receptor for IgE by antigen presenting cells, to T cells. In this context, the investigators have recently shown that not only allergen-specific IgE levels themselves but also the crosslinking ability of complexes formed between IgE and allergen dictate the extent of CD23-mediated T cell activation. The observation that nasal allergen contact triggers boosting of systemic allergen-specific IgE levels indicates the presence of IgE+ producing cells locally in the nasal mucosa which can be stimulated upon allergen contact. This hypothesis is supported by the following observations: (A) there is an evidence that IgE-producing B cells and plasma cells are present in the nasal mucosa but nothing has been proven yet. (B) Upon ex vivo challenge of biopsies from nasal mucosa of allergic patients, local synthesis not only of ε germline, but also of ε circle transcripts as products of mature IgE synthesis were observed. However, to which extent this local nasal IgE production contributes to the observed systemic boost of IgE and the underlying kinetics of IgE production are so far unknown and are one important aim of this proposal. Also, though local IgE production has been observed, the presence of the IgE producing cells themselves in the nasal mucosa has so far not been confirmed. One important reason for this is the difficulty of unambiguously identifying those cells by flow cytometry or fluorescence microscopy. In the past several step by step flow cytometry protocols have been developed with the aim of excluding non-relevant cells prior to gating for IgE+ B cells. However, it needs to be borne in mind that all currently used anti-IgE antibodies recognize not only surface IgE present in the form of the B cell receptor but also bound to CD23. As a consequence, most current studies overestimate the presence of IgE B cell receptor (BCR) bearing B cells. This has only recently been demonstrated in a study by Jimenez-Saiz et al. where the authors found that only around 0.0015% of B cells bear an IgE BCR. Here the authors employed a single cell nested polymerase chain reaction (PCR) approach to validate the nature of the BCR after flow cytometry-based cell sorting for IgE+ B cells using previously reported protocols. The overestimation is most likely due to detection of IgE+ B cells bearing CD23 bound IgE. One option to improve flow cytometric detection could be to exclude CD23 positive cells but this could also lead to exclusion of IgE producing cells expressing CD23. Thus, the only alternative to overcome this obstacle is to use an anti-IgE antibody that can distinguish between receptor bound and membrane anchored IgE. In this respect, an anti-IgE antibody fulfilling these requirements has recently been shown to successfully identify IgE producing cells. Thus, the investigators will employ this novel strategy to identify IgE producing cells both in the nasal mucosa as well as in the blood of allergic subjects. In this project, the investigators aim to elucidate the sites and characteristics of allergen-specific IgE production in a two-armed study spanning birch pollen allergic subject undergoing controlled nasal birch pollen challenge outside the season (October). To that aim, IgE producing cells in blood will be determined using flow cytometry and IgE producing cells in the nasal mucosa will be revealed in nasal biopsies using confocal microscopy. Understanding the characteristics and locations of IgE producing cells is critical for the development of future new therapeutic approaches.

Conditions

• Allergy

Interventions

Type	Name	Description
PROCEDURE	Blood sampling	Blood samples will be taken by puncture of the antecubital vein for peripheral blood mononuclear cells (PBMCs) isolation, cytokines measurement, and flow cytometry analysis
PROCEDURE	Nasal biopsies	Nasal biopsies will be taken from the lower fringe of the inferior turbinate, approximately 1-2cm from the anterior curved edge for RNA sequencing and confocal microscopy staining
BIOLOGICAL	Nasal specimen collection	Nasal specimen collection will be conducted. Nasosorption FXi/PU (containing a synthetic absorptive matrix (SAM)) will be obtained.
PROCEDURE	Mucosal RNA sampling	A 10 cm nasal curette will be used (Rhino-Probe, Arlington Scientific, USA). The curette is brought to lie against the mid-inferior portion of the inferior turbinate under direct visualisation. The curette is rubbed against the mucosal surface, going outwards. To ensure successful sample acquisition, this motion will be repeated 2-3 times
PROCEDURE	Intranasal challenge	The extract of birch pollen (Allergopharma, Vienna, Austria) will be freshly diluted in a 0.9 percent sterile sodium chloride solution and administered by means of a metered pump. The allergen will be administered supplying 15 μl per puff to both nostrils. Azelastine nasal spray or desloratadine 5mg will be given if the patient suffers from nasal or eye symptoms after the challenge. Equivalent amount of saline without allergens will be given to the control group.
PROCEDURE	Skin prick test	In order to evaluate the patient's sensitization profile at the screening visit, a regular skin prick test will be conducted with commercial birch pollen extract and a panel of allergens used in routine diagnosis in the allergy clinic of the ear, nose, and throat (ENT) department. Titrated skin prick test: Titrated skin prick test (SPT) to birch pollen extract is conducted by using increasing dilutions up to 1:100 000. As a result, it is possible to determine the lowest concentration that leads in a skin reaction.
PROCEDURE	Peak Nasal Inspiratory Flow (PNIF)	The functionality and convenience of the PNIF presents a rare opportunity to rapidly obtain objective measurements of nasal peak inspiratory flow. It was also validated during other nasal allergen challenge as a study tool
BIOLOGICAL	Pregnancy test	In female patients, a regular urine pregnancy test will rule out pregnancy. The test will be conducted at the screening visit before the first skin prick test and then once a month afterwards.

Timeline

• Start date: 2021-11-11
• Primary completion: 2026-01-01
• Completion: 2026-09-01
• First posted: 2021-09-13
• Last updated: 2025-05-07

Locations

1 site across 1 country: Austria