Published Online: October 14, 2020
Chronic obstructive pulmonary disease (COPD) is a smoking related chronic lung disease that affects millions of people worldwide. Early evidence shows that patients with COPD are a high risk of poor outcomes from SARS-CoV-2 infection through unknown mechanisms. Steroid inhalers are used commonly to treat COPD but the effects that these inhalers have upon risk of SARS-CoV-2 infection is unknown.
In a recently published study in The Journal of Allergy and Clinical Immunology (JACI), a team led by investigators at Imperial College London report that use of steroid inhalers in COPD reduces expression of ACE2, an important receptor that is used by SARS-CoV-2 to gain entry into the lungs. Finney et al initially studied airway samples taken from patients with COPD to examine whether expression of ACE2 or other viral receptors was altered in patients who take steroid inhalers. The investigators then further validated their findings by carrying out controlled experiments in the laboratory where steroids were directly administered onto lung cells from COPD patients or into the airways of mice with COPD-like changes.
The expression of ACE2, but not other viral entry receptors, was lower in airway samples from patients taking steroid inhalers and similarly reduced in response to direct administration of steroids in COPD cells and mice. The investigators identified that this effect occurs due to the steroids reducing a group of proteins called ‘interferons’ which are produced in response to viral infection and are known to regulate the expression of ACE2.
These findings indicate that use of steroid inhalers may directly alter the susceptibility of COPD patients to SARS-CoV-2 infection by reducing the expression of a key receptor used by the virus to gain entry into the lungs. However, other effects of steroids such as reducing interferon response may conversely have detrimental implications in the context of active viral infection. Additional research, including clinical studies examining effects of inhaled steroid use on the clinical course of SARS-CoV-2 infection are ongoing and will provide greater insight in the future.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.