Eosinophil-mediated suppression and anti-IL-5 enhancement of plasmacytoid dendritic cell interferon responses in asthma

Background: Virus-induced IFN-alpha secretion by plasmacytoid dendritic cells (pDCs) is negatively impacted by IgE and has been linked to asthma exacerbations. Eosinophils, another contributor to type 2 inflammation, are also associated with asthma severity. Objective: We sought to investigate the impact of eosinophils on pDC antiviral interferon responses and determine whether anti-IL-5/5R alpha therapy enhances pDC antiviral function. Methods: Blood pDCs purified from anonymous donors were stimulated in vitro with rhinovirus (RV)-16 in the presence or absence of eosinophils/eosinophil supernatants. IFN-alpha was measured in supernatants and RNA collected for bulk RNA-sequencing. Next, purified pDCs from 8 individuals with moderate to severe asthma, treated or not treated with anti-IL-5/5R alpha therapy, were cultured ex vivo with or without RV; IFN-alpha secretion and differential gene expression analysis were compared between groups. Results: Exposure to either eosinophils or eosinophil supernatants inhibited RV-induced pDC IFN-alpha secretion in a dose-dependent manner and did not impact pDC viability. Eosinophil-derived neurotoxin and TGF-beta partially recapitulated pDC IFN-alpha inhibition. Transcriptome analysis revealed global repression of pDC interferon response patterns by eosinophils, most notably in basal expression of interferon-stimulated genes. Increased RV-induced IFN-alpha secretion and transcription as well as increased basal interferon-stimulated gene expression was detected in pDCs from participants treated with anti-IL-5/5R alpha therapy. Conclusions: Our findings highlight a novel mechanism through which type 2 inflammation regulates pDC IFN-alpha responses relevant to RV respiratory infections in the context of eosinophilic airway disease, suggesting a potential mechanism through which eosinophil-depleting therapies may reduce severity of RV illnesses.

Automated summary

This study investigated the impact of eosinophils on pDC antiviral interferon responses and found that eosinophils inhibit pDC IFN-alpha secretion and repress basal expression of interferon-stimulated genes. Furthermore, it was observed that pDCs from individuals treated with anti-IL-5/5R alpha therapy exhibited increased IFN-alpha secretion and transcription in response to RV.