The following is a summary of “Examining Histamine-Releasing Factor in Severe Asthma and Rhinovirus-Induced Exacerbations,” published in the SEPTEMBER 2023 issue of Allergy & Immunology by Kawakami, et al.
Histamine-releasing factor (HRF) has been implicated in allergic diseases, particularly asthma. Previous studies have demonstrated its pathogenic role in mouse models of asthma.
For a study, researchers sought to analyze data from multiple sources, including sera samples from asthmatic patients, nasal washings from individuals infected with rhinovirus (RV), sera samples from patients experiencing RV-induced asthma exacerbations. The goal was to investigate factors related to HRF function in asthma and virus-induced asthma exacerbations.
The study utilized enzyme-linked immunosorbent assay (ELISA) to quantify total IgE, HRF-reactive IgE/IgG, and HRF levels in various samples. The samples were collected from patients with mild/moderate asthma, severe asthma (SA), and healthy controls (HCs). Additionally, HRF secretion was analyzed in culture media from RV-infected human bronchial epithelial cells and in nasal washings from experimentally RV-infected individuals. Longitudinal serum samples from patients experiencing asthma exacerbations were also assessed for HRF-reactive IgE/IgG levels.
The study found that HRF-reactive IgE and total IgE levels were higher in SA patients than HCs. In contrast, HRF-reactive IgGlow(particularly IgG1) levels were lower in asthmatic patients than in HCs. Notably, asthmatic patients with high levels of HRF-reactive IgEhigh tended to release more tryptase and prostaglandin D2 when their bronchoalveolar lavage cells were stimulated with anti-IgE. RV infection was shown to induce HRF secretion from bronchial epithelial cells in vitro and from the nasal epithelium in vivo. Furthermore, asthmatic patients had elevated levels of HRF-reactive IgE during asthma exacerbations triggered by RV infections, compared to levels after resolution. The phenomenon was not observed in asthma exacerbations unrelated to viral infections.
The findings suggested that HRF-reactive IgE was associated with the severity of asthma, particularly in patients with SA. Moreover, RV infections can stimulate HRF secretion from respiratory epithelial cells, highlighting the potential role of HRF in RV-induced asthma exacerbations.