Changes in basophil activation during immunotherapy with house dust mite and mugwort in patients with allergic rhinitis

Diagnostic Workup in IgE-Mediated Allergy to Asteraceae Weed Pollen and Herbal Medicine Products in Europe

Anemophilous weeds from the Asteraceae family are highly allergenic and represent a significant source of aeroallergens in late summer and autumn. Ragweed and mugwort pollen allergies have become a significant health burden in Europe. Some people with respiratory allergies to weed pollen may also suffer hypersensitivity reactions to herbal medicines obtained from certain cross-reactive plants in the Compositae family, such as chamomile, marigold, and purple coneflower. General physicians, ear, nose, and throat (ENT) specialists, and pulmonologists need to be familiar with the diagnostic tests used by allergists in clinical practice to support accurate diagnosis in such patients. Allergists must also be aware of the suggestions of the European Medicines Agency (EMA)'s Herbal Medicinal Products Committee and the broad spectrum of herbal therapies to educate their patients about potential risks.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Dynamic Changes, Correlation of Basophils, and the Therapeutic Effect in Patients With Allergic Rhinitis During Allergen-specific Immunotherapy

BACKGROUND

The role of basophils in allergic rhinitis (AR) has been studied extensively; however, there are very few reports on changes in basophils after allergen-specific immunotherapy (SIT).

OBJECTIVE

To examine the changes and correlation of peripheral blood basophils and the therapeutic effect in patients with AR during allergen-SIT.

METHODS

A total of 77 patients with AR who were allergic only to house dust mites received allergen-SIT. At 3 time points, patients underwent testing for the percentage and activation rate of basophils in peripheral blood, skin index (SI) measurement, visual analog scale (VAS) assessment, and rhinoconjunctivitis quality of life questionnaire (RQLQ) evaluation. The results were compared to a control group with congenital preauricular fistula.

RESULTS

(1) Before treatment, the percentage and activation rate of basophils in patients with AR were significantly higher than those in controls. There was no significant difference in the percentages and activation rates of basophils at the 3 time points. (2) The SIs, VAS, and RQLQ scores of the patients immediately after treatment and 2 years posttreatment decreased significantly compared to those before treatment; the SI, VAS, and RQLQ scores of the patients 2 years posttreatment increased significantly compared with those immediately after treatment. (3) There was no correlation between the patients' basophil activation rate and percentage and the SI, VAS, and RQLQ scores at all time points.

CONCLUSION

The percentage and activation rate of basophils were higher in patients with AR than in controls. The values did not change significantly after allergen-SIT and showed no correlation with treatment effectiveness. Therefore, the frequency and activation rate of basophils cannot be used as criteria for assessing the effectiveness of allergen-SIT for house dust mites. Allergen-SIT is effective for the management of AR, but the effect declines after the completion of therapy.

Upregulated Expression of Toll-Like Receptor 7 in Peripheral Blood Basophils of Patients With Allergic Rhinitis

Background

Recently, it has been reported that Toll-like receptor 7 (TLR7) agonists can improve allergic rhinitis (AR) symptoms by up-regulation of Th1 cytokine release and suppression of Th2 cell functions. However, little is known of the expression of TLR7 in basophils of AR.

Objective

To explore the expression of TLR7 in basophils of AR, and influence of allergens on TLR7 expression.

Methods

The expression levels of TLR7 in basophils of patients with AR were determined by flow cytometry, and the influence of allergens on TLR7 expression was examined by real time (q) PCR.

Results

The percentages of TLR7+CCR3+ cells ( P < 0.001 and P = 0.011), TLR7+CD123+HLA-DR− cells ( P = 0 .016 and P = 0.042) and TLR7+CCR3+CD123+HLA-DR− cells ( P = 0.046 and P = 0.035) in blood granulocyte and mononucleated cell populations of the patients with AR were increased, respectively compared with HC subjects. TLR7 MFI on CCR3+ cells ( P = 0.050 and P = 0.043), CD123+HLA-DR− cells ( P < 0.001 and P = 0.002) and CCR3+CD123+HLA-DR− cells ( P < 0.001 and P = 0.003) were enhanced compared with HC subjects. Allergens Der p1 and OVA provoked upregulation of TLR7 expression at both protein and mRNA levels and IL-13 production in KU812 cells. House Dust Mite extract (HDME), Artemisia sieversiana wild allergen extract (ASWE), IL-31, IL-33, IL-37, and TSLP provoked elevation of IL-6 release from KU812 cells following 2 h incubation period.

Conclusions

The percentage of TLR7+ basophils and TLR7 expression intensity in a single basophil are both increased in the blood of patients with AR, indicating that basophils likely contribute to the pathogenesis of AR via TLR7.

Upregulation of the expression of Toll-like receptor 9 in basophils in patients with allergic rhinitis: An enhanced expression by allergens

It was reported that the expression of Toll-like receptor (TLR) 9 may be related to Th2-type allergic inflammation including allergic rhinitis (AR). However, little is known about the expression of TLR9 in the basophils in AR. In the present study, the expression of TLR9 was examined by flow cytometry analysis, and the expression of TLR9 mRNA in KU812 was determined by quantitative real-time PCR. The results showed that the percentage of TLR9⁺ CCR3⁺ cells in blood granulocytes increased by 46% in patients with AR, but not in peripheral blood mononuclear cells (PBMCs). Allergens namely Dermatophagoide allergen extract (DAE) and Platanus pollen allergen extract (PPAE) upregulated the expression of TLR9 in CCR3⁺ granulocytes by 76% and 84%, respectively. DAE and PPAE also enhanced the proportions of TLR9⁺ CD123⁺ HLA-DR^- cells and TLR9⁺ CCR3⁺ CD123⁺ HLA-DR^- cells in granulocytes and PBMCs of patients with AR. In order to investigate the actions of allergens on basophils, KU812 cells were used. It was observed that all KU812 cells expressed TLR9, and the expression intensity of TLR9 in a single KU812 cell was elevated by CpG. IL-37, IL-31, IL-33, Artemisia sieversiana wild allergen extract (ASWAE), DAE, OVA and Der p 1 induced an increase in the expression of TLR9 mRNA and IL-6 production in KU812 cells. It was shown that the percentage of TLR9-expressing basophils increased in the blood of ovalbumin (OVA)-sensitized mice. In conclusion, an increased expression of TLR9 and the production of IL-6 in basophils implicate that the contribution of basophils to AR is likely via TLR9.

Basophil Activation as Marker of Clinically Relevant Allergy and Therapy Outcome

For some years now the basophil activation test (BAT) using flow cytometry has emerged as a powerful tool and sensitive marker that can be used to detect clinically relevant allergies, provide information on the severity of an allergic reaction, and monitor therapies. Compared to other in vitro diagnostic tests, BAT seems to have a better informative value in terms of clinical relevance. In general, the BAT can be used for the diagnosis of the most common forms of IgE-mediated allergy such as hymenoptera venom allergy, inhalant allergy, food allergy, and drug allergy. Various basophil markers and parameters have been established which, depending on the trigger of the respective allergy, can provide information on the clinical relevance of sensitization, on the development of natural tolerance, on trigger thresholds, and on the severity of the allergic reaction. The BAT also serves as a suitable follow-up instrument for various therapeutic approaches such as specific immunotherapy, desensitization protocols, or use of anti-IgE-antibodies for the various diseases. Quality controls for routine use, standardization, and automatization are expected to expand the range of applications for the above-mentioned indications.

Maintenance-Phase Subcutaneous Immunotherapy with House Dust Mites Induces Cyclic Immunologic Effects

BACKGROUND

Subcutaneous immunotherapy (SCIT) is an effective treatment of respiratory allergies including house dust mite (HDM) and Hymenoptera venom allergy. During the build-up phase, the allergen is administered weekly at increasing doses, while during the maintenance phase, it is administered at a fixed high dose every 4 weeks. Upon SCIT injection, the allergen is driven to the draining lymph nodes where it most likely induces an immune response. Immunologic changes are thus supposedly induced at each injection.

OBJECTIVES

It is now established that SCIT induces tolerance in the long term, but the precise underlying immunologic mechanisms remain unclear. Therefore, we wanted to analyze the immunologic changes induced in both innate and adaptive immune cells at each individual SCIT administration during the maintenance phase in HDM-allergic patients. More specifically, we wondered whether the changes in regulatory T cell (Treg) and IgE+ B cell percentages, which are observed at the end of a 3-year course of SCIT, already occurred during the maintenance phase and whether these possible changes were sustained.

METHODS

We enrolled 6 patients suffering from HDM allergic rhinitis and undergoing maintenance HDM SCIT for 18-24 months. The same SCIT extract was used for all patients. We collected blood samples at 5 time points: T1 (immediately before a given SCIT injection), T2 (9 days after T1), T3 (29 days after T1 and right before the successive administration), T4 (39 days after T1), and T5 (61 days after T1 and just before the next injection). Six non-allergic age-matched healthy individuals were used as controls. Using flow cytometry, we assessed the following cell subsets in peripheral blood mononuclear cells: CD4 and CD8 T cells, Tregs, B cells, IgE+ B cells, NK and NKT cells, and total and activated basophils.

RESULTS

HDM-allergic patients displayed increased percentages of CD4 and CD8 T cells and NK cells compared to healthy controls. In contrast, NKT cells, total B cells, and basophils were diminished. These differences were maintained throughout the time course and seemed to be independent of the periodical SCIT injections. On the contrary, Treg percentages were significantly reduced in all HDM-allergic patients at T1. However, they increased at T2 and T4 (9 days after each SCIT injection) but decreased again at T3 and T5, just before the next one, resulting in cyclic changes. IgE+ B cells were significantly increased at T1, even more increased after each administration (T2, T4), and went back to their initial levels at T3 and T5, also resulting in a cyclic pattern.

CONCLUSIONS

Our data suggest that during the SCIT maintenance phase, cycles of expansion/contraction of Tregs and IgE+ B cells occur at each SCIT injection. Therefore, the sustained induction of immune tolerance by SCIT, through the increase of Tregs, seems to depend on the periodical exposure to the allergen, at least during the early steady state.

Basophil Activation Test: Old and New Applications in Allergy

PURPOSE OF REVIEW

The basophil activation test (BAT) using flow cytometry has supplanted traditional methods of measuring basophil degranulation using histamine and other mediator release, and can be used for clinical applications as well as to explore the immune mechanisms of effector cell response to allergen. This review discusses the advancements made in clinical, diagnostic and laboratory research of allergy utilizing an ever-evolving BAT.

RECENT FINDINGS

Being an in vitro surrogate of the allergic reaction that happens in vivo in the sick patient, the BAT can be used to support the diagnosis of various allergic conditions, such as food, drug, respiratory and insect venom allergies, and the assessment of clinical response to allergen-specific immunotherapy and other immunomodulatory treatments. The BAT can also be used for research purposes to explore the mechanisms of allergy and tolerance at the level of the basophil, for instance by manipulating IgE and IgG and their receptors and by studying intracellular signalling cascade in response to allergen. This review covers the applications of the BAT to the clinical management of allergic patients and the increased understanding of the mechanisms of immune response to allergens as well as technological advancements made in recent years.