Enhanced Efficacy of Dust Mite Sublingual Immunotherapy in Low-Response Allergic Rhinitis Patients after Dose Increment at 6 Months: A Prospective Study

Allergen immunotherapy in China

Allergen immunotherapy (AIT) is an etiological treatment strategy that involves administering escalating doses of clinically relevant allergens to desensitize the immune system. It has shown encouraging results in reducing allergy symptoms and enhancing patients' quality of life. In this review, we offer a thorough overview of AIT in China, examining its efficacy, safety, current practices, and prospects. We further underscore the progress made in AIT research and clinical applications, as well as the distinct challenges and opportunities that China faces in this area.

Chinese Guideline on Allergen Immunotherapy for Allergic Rhinitis: The 2022 Update

In the last few decades, there has been a progressive increase in the prevalence of allergic rhinitis (AR) in China, where it now affects approximately 250 million people. AR prevention and treatment include allergen avoidance, pharmacotherapy, allergen immunotherapy (AIT), and patient education, among which AIT is the only curative intervention. AIT targets the disease etiology and may potentially modify the immune system as well as induce allergen-specific immune tolerance in patients with AR. In 2017, a team of experts from the Chinese Society of Allergy (CSA) and the Chinese Allergic Rhinitis Collaborative Research Group (C2AR2G) produced the first English version of Chinese AIT guidelines for AR. Since then, there has been considerable progress in basic research of and clinical practice for AIT, especially regarding the role of follicular regulatory T (TFR) cells in the pathogenesis of AR and the use of allergen-specific immunoglobulin E (sIgE) in nasal secretions for the diagnosis of AR. Additionally, potential biomarkers, including TFR cells, sIgG4, and sIgE, have been used to monitor the incidence and progression of AR. Moreover, there has been a novel understanding of AIT during the coronavirus disease 2019 pandemic. Hence, there was an urgent need to update the AIT guideline for AR by a team of experts from CSA and C2AR2G. This document aims to serve as professional reference material on AIT for AR treatment in China, thus improving the development of AIT across the world.

The Present and Future of Allergen Immunotherapy in Personalized Medicine

Allergic diseases are particularly suitable for personalized medicine, because they meet the needs for therapeutic success, which include a known molecular mechanism of the disease, a diagnostic tool for that disease and a treatment that blocks this mechanism. A range of tools is available for personalized allergy diagnosis, including molecular diagnostics, treatable traits and omics (i.e., proteomics, epigenomics, metabolomics, transcriptomics and breathomics), to predict patient response to therapies, detect biomarkers and mediators and assess disease control status. Such tools enhance allergen immunotherapy. Higher diagnostic accuracy results in a significant increase (based on a greater performance achieved with personalized treatment) in efficacy, further increasing the known and unique characteristics of a treatment designed to work on allergy causes.

Venom Immunotherapy and Aeroallergen Immunotherapy: How Do Their Outcomes Differ?

Allergen immunotherapy (AIT) and venom immunotherapy (VIT) are meant to work on the causes of allergies, respectively, to respiratory allergens and Hymenoptera venom, inducing tolerance to the allergens and modifying the natural history of allergy. Both types of immunotherapies have evidence of efficacy, but actually they present wide differences in both effectiveness and safety. Indeed, as far as the effectiveness of VIT is concerned, if the protection against fatal reactions to stings is considered as the primary objective, more than 40 years of clinical practice demonstrate complete success. The clinical success of AIT is measurable on the basis of reduction or disappearance of allergic symptoms. The difference between the two treatments is even higher as regards safety: AIT has been concerned in the past by a series of fatal reactions caused, which underwent a progressive decrease when it was understood that they were related to the presence of uncontrolled asthma. However, fatal reactions related to failure to recognize the presence of risk factors or administration errors are still reported. Similarly to what has been observed for efficacy, VIT has never been affected by fatal reactions to the administration of venom, and the most important risk of anaphylaxis, which is the concomitance of mastocytosis, is now identified by measuring its marker serum tryptase. To date, mechanisms of hypersensitivity reactions that differentiate respiratory allergy from Hymenoptera venom allergy have not been successfully demonstrated. We have examined the past and present literature in order to propose reasonable hypotheses about the mechanisms actually involved.

Clinical Evaluation for Sublingual Immunotherapy With Dermatophagoides farinae in Polysensitized Allergic Asthma Patients

Background: Many studies have demonstrated the efficacy of single-allergen sublingual immunotherapy (SLIT) in polysensitized patients with allergic rhinitis (AR), but less is reported in polysensitized patients with allergic asthma (AS).

Method: Data of 133 adult patients with house dust mite (HDM)-induced AS who had been treated for 3 years were collected. These patients were divided into the control group (treated with low to moderate dose of inhaled glucocorticoids and long-acting β2 agonists, n = 37) and the SLIT group (further treated with Dermatophagoides farinae drops, n = 96). The SLIT group contained three subgroups: the single-allergen group (only sensitized to HDM, n = 35), the 1- to 2-allergen group (HDM combined with one to two other allergens, n = 32), and the 3-or-more-allergen group (HDM combined with three or more other allergens, n = 29). The total asthma symptom score (TASS), total asthma medicine score (TAMS), and asthma control test (ACT) were assessed before treatment and at yearly visits. Forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) was assessed before treatment and at the end of SLIT.

Results: TASS and ACT scores in the control group were significantly higher than that in the single-allergen group and the 1- to 2-allergen group after 1, 2, and 3 years of SLIT and significantly higher than that in the 3-or-more-allergen group after 3-year SLIT (all p < 0.05). TAMS of the control group was significantly higher than that of the other three groups after 0.5, 1, 2, and 3 years of SLIT (all p < 0.05). FEV1/FVC in the control group was significantly higher than baseline after 3 years of immunotherapy (p < 0.05).

Conclusion: Patients sensitized to HDM with/without other allergens showed similar efficacy after 3 years of SLIT. However, the initial response of patients with three or more allergens was slower during immunotherapy process.

Serum Soluble ST2 Correlated with Symptom Severity and Clinical Response of Sublingual Immunotherapy for House Dust Mite-Induced Allergic Rhinitis Patients

Background

Suppressor of tumorigenicity 2 (ST2) is a key biomarker in inflammation and cardiovascular diseases, but limited data is available on its role in allergic rhinitis (AR).

Objective

The aim of this study is to explore the role of serum soluble ST2 (sST2) in evaluating disease severity and predicting the efficacy of sublingual immunotherapy (SLIT) in house dust mite- (HDM-) induced AR patients.

Methods

Eighty healthy controls (HC group) and 160 HDM-induced AR patients, including 40 mild patients (MAR group) and 120 moderate-severe patients (MSAR group), were recruited in this study. Serum was collected from all participants and levels of sST2 were determined by ELISA and the relationship between sST2 levels and disease severity was assessed. In the MSAR group, 109 patients received 3 years of SLIT, and the relationship between serum levels of sST2 and efficacy of SLIT was exampled.

Results

Serum sST2 levels were increased in HDM-induced AR patients compared to the HC group (P < 0.001), and the concentrations were higher in the MSAR group than in the MAR group and HC group (all P < 0.05). Moreover, sST2 levels positively correlated with the total nasal symptom score (TNSS), visual analogue scale (VAS), and specific IgE levels (P < 0.05). Seventy-eight MSAR patients accomplished SLIT, and they were divided into an effective group (n = 40) and an ineffective group (n = 38). The serum sST2 levels in the effective group were lower than those in the ineffective group (P < 0.001). In addition, patients in the effective group levels exhibited significantly lower sST2 levels post-SLIT than pre-SLIT (P < 0.001), but no statistic difference was observed in the ineffective group (P > 0.05). Receiver operating characteristic (ROC) curve showed promising accuracy for predicting clinical efficacy of SLIT in AR patients (area under the curve = 0.839, P < 0.001).

Conclusion

Serum sST2 is a potential biomarker for assessing disease severity and may serve as a sensitive biomarker for predicting the therapeutic response of SLIT in HDM-induced AR patients.