Measurement of allergen-specific IgE antibodies to inhaled allergens is important for the diagnosis and risk evaluation of allergic diseases such as asthma and allergic rhinitis. This study aimed to elucidate the prevalence of allergen sensitization among the healthy population in Japan using serum samples stocked in the Japanese Red Cross for blood donation. Age- and gender-stratified serum samples (n = 800) from residents in Tokyo aged 20-59 years were randomly selected from the stocked serum obtained for blood donation in 2005. Total and specific IgE antibodies to 17 inhaled allergens were measured by the ImmunoCAP method. Individuals with positive (≥0.35 U_A/mL) specific IgE antibodies to at least one inhaled allergen were defined as atopic. Stocked serums from donors aged 20-29 years in Sapporo, Osaka, Fukuoka, and Okinawa (n = 200 each) were also obtained for the measurement of IgE to six common inhaled allergens, to evaluate regional differences in the rate of positivity. Among residents in Tokyo, the prevalence of atopy was 78.0% and highest in men aged 20-29 years (94.0%), which decreased with age. The prevalence of specific IgE antibodies was highest for Japanese cedar pollen (66.8%), followed by cypress pollen (46.8%), Dermatophagoides pteronyssinus (38.3%), and moths (30.1%). Examination of IgE to Japanese cedar pollen, D. pteronyssinus, and moths identified 97.6% of atopic subjects in Tokyo. There were substantial regional differences in the prevalence of pollen IgE positivity. This study demonstrated an extremely high prevalence of positivity in inhaled allergen-specific IgE antibodies among healthy adults in Japan.

Patients with severe eosinophilic asthma, characterised by a high disease burden, benefit from mepolizumab, which improves symptoms and reduces exacerbations, potentially leading to clinical remission in a subgroup. This study aimed to identify treatment response trajectories to mepolizumab for severe eosinophilic asthma and to assess the achievement of clinical remission. Data from the Australian Mepolizumab Registry were used to assess treatment responses at 3, 6, and 12 months. The treatment response trajectories were identified using a group-based trajectory model. The proportions achieving clinical remission at 12 months, which was defined as well-controlled symptoms, no exacerbations, and no oral corticosteroid (OCS) use for asthma management, were compared between trajectories, and baseline predictors of the trajectories were identified using logistic regression analysis. We identified three trajectory groups: group 1, responsive asthma with less OCS use (n=170); group 2, responsive late-onset asthma (n=58); and group 3, obstructed and less responsive asthma (n=70). Groups 1 and 2 demonstrated higher proportions achieving clinical remission at 36.5% and 25.9%, respectively, compared to group 3 with 5.7% (p <0.001). Baseline predictors for assigned groups included lower OCS dose in group 1; greater FEV₁% predicted, higher Asthma Quality of Life Questionnaire score, higher OCS dose, and nasal polyps in group 2; with group 3 as the reference. Treatment response to mepolizumab in severe eosinophilic asthma follows 3 trajectories with varying proportions achieving clinical remission and differing baseline characteristics. Treatment response variability may influence the achievement of clinical remission with mepolizumab therapy.

The presence of IgG antibodies (Abs) to Aspergillus fumigatus (Af) is a crucial diagnostic criterion for allergic bronchopulmonary aspergillosis (ABPA). Although precipitation is traditionally used to document IgG Abs, anti-Af serum IgG levels can also be measured by enzyme immunoassay (EIA). However, there are insufficient data on the optimal cut-offs to assess diagnostic performance of the EIA method. This study aimed to determine cut-off levels of IgG binding crude Af extracts or recombinant Asp f 1 (by ImmunoCAP®) and to compare their efficacy for ABPA diagnosis with Af-precipitating Abs. The age distribution of levels of IgG to crude extracts of Af (Af-IgG) and recombinant Asp f 1 (Asp f 1-IgG) was established using sera from 694 healthy controls (HC). Receiver operating characteristic analysis for Af-IgG and Asp f 1-IgG levels for the purpose of ABPA diagnosis was performed in 306 Af-sensitized asthma patients (including 49 ABPA), and cut-offs were determined. An age-dependent decline in the levels of Af-IgG was observed in HC. Thus, cut-offs for Af-IgG levels were determined separately by age as 60 mg/L for patients aged <55 years, and 45 mg/L for those aged ≥55 years. For Asp f 1-IgG, 6.6 mg/L was set as the cut-off regardless of age. Although such IgG testing by EIA allowed a sufficiently good diagnostic performance, Af-precipitating Abs had better diagnostic applicability for ABPA. We determined cut-offs for Af-IgG and Asp f 1-IgG measured by EIA, which can be useful in clinical settings where precipitating Abs are unavailable.

Asthma cases have been increasingly investigated using claims data. However, the validity of defining asthma cases using health insurance claims in Japan is unclear. This study aims to assess the positive and negative predictive values of our proposed discrimination criteria for asthma. We developed discrimination criteria for asthma based on both the International Statistical Classification of Diseases and Related Health Problems (ICD)-10 disease codes for asthma and health insurance claims data for prescriptions and the treatment of asthma. Inclusion criteria were patients aged ≥16 years with at least one health insurance claim from April 2018 to March 2019 in all departments of our hospital. Physician-diagnosed asthma documented in the charts was used as the reference standard. Positive and negative predictive values of the discrimination criteria for physician-diagnosed asthma were estimated and compared with those estimated from discrimination criteria based solely on ICD-10 codes. The new discrimination criteria had a high positive predictive value (PPV) of 86.0%, which was significantly higher than the PPV for the criteria defined solely by the ICD-10 codes (61.5%) (P < 0.01). The negative predictive values for both criteria were 100%. Allergic rhinitis and chronic cough were frequently misclassified as asthma using the discrimination criteria based solely on ICD-10 codes but were more likely to be appropriately classified using our proposed criteria. Our proposed criteria adequately identified asthma subjects using health insurance claims data in Japan with a high PPV. Further studies are needed for external validation of these criteria.

Severe asthma is associated with persistent symptoms, frequent exacerbations, oral corticosteroid dependence, and reduced lung function. The emergence of biologic therapies targeting type 2 (T2) cytokines, including IL-5, IL-4, IL-13, thymic stromal lymphopoietin, and circulating IgE, has changed disease management and led to substantial improvement. This approach has also introduced the concept of clinical remission (defined as controlled symptoms, no maintenance corticosteroid use, no exacerbations, and optimized/stabilized lung function) as a potential treatment target. Although some guidelines propose remission criteria, no universally accepted definition exists, and reported prevalence varies depending on definitions, and therapies, and patient groups. Clinical remission has been achieved in approximately one-third of patients receiving T2-targeted biologics. Factors associated with achieving clinical remission include less severe disease (less symptoms, fewer exacerbations, and better lung function), fewer comorbidities (e.g. obesity, anxiety/depression), greater T2-disease activity (the presence of nasal polyps and higher T2 biomarkers), and early treatment response. Azithromycin therapy can also contribute to achieving remission in both T2-high and T2-low moderate to severe asthma phenotypes. Future perspectives on asthma remission include integrating a treatable traits approach, establishing and validating the definition of complete remission, and assessing the long-term benefits of achieving remission. Complete remission may encompass clinical remission, inflammatory remission (normalization of T2 biomarkers), and structural/functional remission (resolution of bronchial hyperresponsiveness, mucus plugging, and airway remodeling). Standardizing remission criteria will enable the identification of predictive factors and facilitate personalized, treat-to-target strategies. Early induction of clinical remission may be a promising strategy for optimizing outcomes in severe asthma.