Background: Severe asthma is a complex disease with heterogeneous features and involves type 2 airway inflammation, including eosinophil accumulation. Surrogate biomarkers, fraction of exhaled nitric oxide (FeNO) and blood eosinophil count (b-EOS), may predict eosinophilic airway inflammation. Here we investigated clinical characteristics of severe asthma phenotype using a combined analysis of FeNO and b-EOS.

Methods: This retrospective study examined clinical data of patients with severe asthma (N = 107; median age, 64 years) treated at Saitama Medical University Hospital from 2009 to 2016. Thresholds of FeNO and b-EOS for sputum eosinophil ratio ≥2% were determined using receiver operating characteristic curve (ROC) analysis. Clinical characteristics were analyzed after classifying patients into four subgroups according to these thresholds.

Results: Of 39 induced sputum samples examined, ROC area under the curve for predicting sputum eosinophilia was 82.0% (p = 0.001) for b-EOS and 77.0% (p = 0.006) for FeNO at optimal cut-off values of ≥300/μL and ≥25 ppb, respectively. The number of sensitized allergens was higher in the high FeNO/low b-EOS and high FeNO/high b-EOS subgroups (p < 0.05). The prevalence of chronic sinusitis was higher in the low FeNO/high b-EOS and high FeNO/high b-EOS subgroups (p = 0.04). The high FeNO/high b-EOS subgroup included the largest proportion (approximately 40%) of patients experiencing frequent severe exacerbations. Both low FeNO/low b-EOS and high FeNO/low b-EOS subgroups showed less severe exacerbations.

Conclusions: Combined evaluation of FeNO and b-EOS can identify patients with frequent exacerbations and stratify the appropriate therapy for type 2 inflammation-predominant severe asthma.

Background: Several serological tests for specific precipitin or IgG are available to demonstrate type III hypersensitivity reactions to Aspergillus species and are essential for infectious fungal disease diagnosis. These assays are also important for allergic bronchopulmonary aspergillosis (ABPA) diagnosis; however, their concordance in ABPA was not well studied.

Methods: Fifty-two ABPA patients diagnosed based on ISHAM criteria were enrolled. Precipitins and IgG specific to Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, or Aspergillus terreus were measured using Ouchterlony double immunodiffusion tests and ImmunoCAP method, respectively. A. fumigatus-specific IgG was also determined using complement-fixation (CF) method.

Results: Forty-eight percent of cases were double-positive for A. fumigatus-specific precipitin and IgG (ImmunoCAP), whereas 3 (6%) and 14 (28%) cases were positive for precipitin or IgG alone, respectively. Kappa coefficient between these measurements was 0.32, suggesting poor concordance. Double-positive cases were more likely to present: Aspergillus sp. in sputum culture, lower pulmonary functions, peripheral blood eosinophilia, higher total IgE and A. fumigatus-specific IgG titer than precipitin-negative cases. A. fumigatus-specific IgG (CF) was positive only in 8 (15%) cases. The presence of A. fumigatus-specific precipitin or IgG was associated with antibodies specific for other Aspergillus spp., suggesting cross-reactivity.

Conclusions: Positive rate of A. fumigatus-specific precipitin or IgG (ImmunoCAP) was superior to IgG (CF), but relatively poor concordance was noted between precipitin and IgG (ImmunoCAP). Positive precipitin for A. fumigatus suggests more active diseases. Cross-reactivity may exist between antibodies to different Aspergillus spp. Therefore, the type III hypersensitivity results in ABPA diagnosis should be carefully evaluated.

Background: Although rodent decidual mast cells (MCs) reportedly play an important role in implantation and placenta formation, the characterization of human decidual MCs has been not well clarified. The aims of this study were to investigate the distribution and characteristics of MCs in human decidua and to establish a culture system for decidua-derived MCs.

Methods: Decidual tissues were obtained from patients who underwent a legal elective abortion (6th week to 9th week of pregnancy), and decidual MCs were enzymatically dispersed. Cultured decidua-derived MCs were generated by culturing decidual cells with stem cell factor. An ultrastructural analysis of primary decidual MCs and cultured decidua-derived MCs was performed using a transmission electron microscope. Receptor and protease expression was analyzed using FACS. Histamine released from MCs was measured using enzyme immune assays.

Results: A larger proportion of tryptase positive⁽⁺⁾ MCs in decidua was present on the maternal side. Both enzymatically dispersed decidual MCs and cultured decidua-derived MCs showed an FcεRIα⁺Kit⁺tryptase⁺chymase⁺ phenotype. Their granules contenting particles exhibited variable amounts of electron-lucent space separating electron-dense particles. Both enzymatically dispersed decidual MCs and cultured decidua-derived MCs released comparable amounts of histamine following FcεRI aggregation.

Conclusions: The isolation method for MCs from decidua during early pregnancy and the culture system for decidua-derived MCs may enable the roles of decidual MC during pregnancy to be explored.

Background: We have recently demonstrated that T cell-mediated nasal hyperresponsiveness (NHR) is a representative pathophysiological feature of allergic rhinitis (AR). Although several anti-allergic drugs are used for the treatment of AR, the efficacy of these drugs on T cell-mediated NHR have not been elucidated. In these studies we investigated the effects of dexamethasone (Dex), montelukast (Mk), and chlorpheniramine (Chl) on NHR in antigen-immunized and antigen-specific Th2 cell-transferred mice.

Methods: OVA-immunized BALB/c mice were treated with Dex, Mk, or Chl and challenged intranasally with OVA. We then assessed NHR, the number of inflammatory cells in the nasal lavage fluid (NALF), mRNA expression of Th2 cytokines in the nasal tissue, the population of CD3⁺CD4⁺ cells in the nasal lymphoid tissue (NALT), and antigen-specific serum IgE and IgG levels. Antigen-induced NHR and changes in antigen-specific T cells in the NALT were investigated in OVA-specific Th2 cell-transferred mice.

Results: Dex significantly suppressed antigen-induced NHR, inflammatory cell infiltration, and IL-4, IL-5, IL-6, and IL-13 expression in immunized mice. Chl was completely ineffective, and only IL-13 expression was suppressed by Mk. None of these drugs affected IgE and IgG production. Antigen-induced NHR and the increase in antigen-specific T cells in the NALT of Th2 cell-transferred mice were inhibited by Dex, but not by Mk or Chl.

Conclusions: Steroids are effective for the reduction of NHR in AR by suppressing the accumulation of inflammatory cells, especially antigen-specific T cells.

Background: Epithelial cell-derived IL-33 has an important role in the initiation and activation of innate allergic inflammation. IL-33 acts as a cytokine through the ST2 receptor (ST2L) and it stimulates the production of Th2 cytokines. Soluble ST2 (sST2) may regulate Th2 responses by neutralizing the activity of IL-33. Basophils express ST2L and produce IL-5 in response to IL-33. However, the role of the epithelial cell-basophil interaction and sST2 in IL-5 production remains unclear.

Methods: Cultured human bronchial epithelial (hBE33) cells, that contained the human IL-33 gene (i.e., hBE33 cells) and a human basophilic cell line, KU812 cells, were used to study the epithelial cell-basophil interaction in the production of IL-5 induced by HDM.

Results: At 15 min after incubation, HDM stimulated the rapid release of IL-33 from cultured hBE33 cells. IL-33 and the supernatant of HDM-treated hBE33 cells stimulated IL-5 production from KU812 cells. Anti-IL-33 antibody and anti-ST2 antibody treatment of KU812 cells suppressed IL-5 production, which had been induced by the supernatant of HDM-treated hBE33 cells. The hBE33 cells secreted sST2 in a time-dependent manner. The production of sST2 by KU812 cells co-cultured with hBE33 cells was significantly increased, compared with KU812 cells cultured with the supernatant of hBE33 cells. Soluble ST2 suppressed IL-5 production by KU812 cells, which was induced by the supernatant of HDM-treated hBE33 cells.

Conclusions: Epithelial cell-derived IL-33 promoted IL-5 production by KU812 cells. The subsequently produced sST2 has important roles in regulating Th2 responses.