Asthma in certain patients elevates risk for worse COVID-19 outcomes
An analysis of sputum samples from patients with asthma suggests that certain subgroups, such as men, African Americans and those with diabetes, have higher expression of two genes that may make them more susceptible to more severe COVID-19 disease, researchers reported in the American Journal of Respiratory and Critical Care Medicine.
Michael C. Peters, MD, from the division of pulmonary and critical care medicine, the department of medicine and the Cardiovascular Research Institute at the University of California, San Francisco, and colleagues assessed gene expression for angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2), both of which mediate viral infection of host cells, as well as intercellular adhesion molecule-1 (ICAM-1), which mediates binding of human rhinoviruses to the airway epithelium, as a comparator in sputum cells from 330 participants in the Severe Asthma Research Program-3 and 79 healthy controls.
For sputum samples collected at baseline, there were no significant differences in the expression of ACE2 and TMPRSS2 between participants with asthma and healthy controls, whereas ICAM-1 expression was higher among those with asthma. Notably, ACE2 expression strongly correlated with expression of TMPRSS2 in healthy controls and participants with asthma, “suggesting that these genes are expressed in similar cells,” the researchers wrote.
In analyses of the 556 sputum samples collected at baseline and at 1-year and 3-year follow-up visits from the 330 participants with asthma, results demonstrated higher expression levels of ACE2 and TMPRSS2 in men vs. women and in African American vs. white participants. ACE2 expression was also higher in patients with diabetes than in those without diabetes. In contrast, the findings showed less consistent differences based on sex or race for ICAM-1 expression.
The researchers also compared sputum samples from baseline and follow-up visits among patients taking inhaled corticosteroids. After accounting for markers of asthma severity, such as FEV1, asthma control test scores and exacerbation history, the data indicated that participants taking inhaled corticosteroids had lower levels of ACE2 and TMPRSS2 expression than those not taking inhaled corticosteroids. These findings were particularly pronounced among those taking higher doses.
“In a large cohort of well-characterized patients with asthma, we report higher sputum cell expression of ACE2 and TMPRSS2 in males, African Americans and patients with diabetes mellitus and lower expression in patients taking inhaled corticosteroids,” the researchers wrote. “These findings can inform prospective study of COVID-19 outcomes in specific asthma subgroups, including subgroups taking inhaled corticosteroids in different dose strengths.” – by Melissa Foster
Disclosures: This study was funded by the NIH, the UCSF Sandler Asthma Basic Research Center and the Parker B. Francis Foundation. Healio Pulmonology could not confirm individual authors’ relevant financial disclosures at the time of publication.