Pre-existing asthma does not enhance cytokine response and disease severity of COVID-19

Background: Both COVID-19 and asthma involve pulmonary inflammation, damage and dysfunction, and can result in respiratory failure and death.(1) A significant portion of COVID-19 sufferers have asthma comorbidity,(2) however, the impact of COVID-19 infections on patients with asthma is still unclear. In this study, we investigated the roles of pre-existing asthma as a comorbidity in disease severities of COVID-19 by measuring immune response in circulating cytokines.

Methods: Plasma samples and clinical information were collected from patients (total 80) with mild (25), severe (36) or critical (19) cases of COVID-19 at the John Radcliffe Hospital, Oxford, UK. The concentrations of 51 proteins in the plasma samples were measured with Luminex Kits (Bio-techne) using a Bio-Rad Bio-Plex® 200 Systems.

Results: A total of 16 pre-existing asthma patients were found (3 in mild, 10 in severe, and 3 in critical COVID-19).
In the comparison of circulating cytokines enrichment, no significant difference between COVID-19 patients with and without asthma was found in different disease severities and age groups. Indeed, a trend of slightly lower levels of CXCL10, CCL2, and IL-8 were observed in patients with asthma.
In comparing clinical traits within the same COVID-19 severity group, also no differences were observed between patients with or without asthma in terms of oxygen level, CRP, neutrophil counts, and length of hospital stay. Although the age distribution showed a slight increase with severity of COVID-19 (37.33±17.04 in mild, 55.60±16.12 in severe and 70.00±11.36 in critical) in the patients with asthma but not in the patients without asthma (69.91±20.15 in mild, 66.69±15.51 in severe and 55.38±12.47 in critical), the prevalence of asthma in COVID-19 severity groups (12.0% in mild, 27.8% in severe and 15.8% in critical) did not exhibit a clear correlation between asthma and the severities of COVID-19. Furthermore, the mortality ratio in the COVID-19 patients with asthma (12.5%) was not higher than that in patients without asthma (17.2%).

Conclusions: Based on this cohort study, pre-existing asthma was not associated with an enhanced cytokine storm after COVID-19 infection, and did not have strong effects on COVID-19 progression.

References
1. Menter T, et al. Postmortem examination of COVID-19 patients reveals diffuse alveolar damage with severe capillary congestion and variegated findings in lungs and other organs suggesting vascular dysfunction. Histopathology. 2020 May 4.
2. Docherty AB, et al. Features of 20133 UK patients in hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: prospective observational cohort study. BMJ. 2020;369:m1985.

Jian Luo MD, PhD

University of Oxford

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