ABSTRACT
Background: Rhinovirus is the most common trigger for exacerbations of asthma. Alveolar macrophages (AM) are a major site of RV infection and can also be infected by SARS-CoV-2. The pandemic caused by the SARS-CoV-2 raised concerns that patients with severe asthma (SA) would be at particularly high risk of developing severe disease. To date, evidence for poor outcomes in asthma remains limited suggesting a differential immune response to these two viruses. Method(s): Alveolar macrophages (AM) were isolated from bronchoalveolar lavage samples from patients with SA and infected with RV (n=13), SARS-CoV-2 alpha (B.1.1.7) (n=9) and delta (B.1.627.2)(n=8) variants. Antiviral mediators representing NF-KB-induced interferon-driven mRNAs (IL6 and IL8, RIGI and MDA5, respectively) were measured by qPCR, normalised to GAPDH and compared between infected AM and controls. Result(s): RV infected AM showed significant increases in mRNA expression of RIGI (4.39 fold change +/-4.68, p<0.001 vs control), MDA5 (2.96 fold change +/- 2.93, p=0.002 vs control) and IL6 (1.88 fold change +/- 0.98, p=0.006) compared to AM treated with control media alone, whilst IL8 did not significantly change. However, AM infected with SARS-CoV-2 alpha or delta variants showed no difference in levels of antiviral mediators compared to controls. Longitudinal analysis of AMs infected with SARS-CoV-2 alpha or delta variants showed no antiviral response. Conclusion(s): AM from subjects with severe asthma produce a pattern of anti-viral responses following RV infection that is absent when exposed to SARS-CoV-2 variants currently in circulation.