Early in the pandemic, it was thought that the SARS-CoV-2 virus attacked blood vessels and the heart with just as much vigor as it did the lungs. But now, just over a year later, a new study shows that the virus attacks the lungs and the lining of lung tissue, and that injury to blood vessels may be less common.
In research published recently in Critical Care, blood markers indicated that lung tissue sustained more damage than blood vessels or other organs. This research confirms clinical observations made over the year and may guide the development of future therapeutics against the virus, said first author Dr. Pavan Bhatraju, a pulmonary and critical care doctor at UW Medicine and Harborview Medical Center.
“In this study, we enrolled critically ill patients in the ICU, some with COVID-19 and others without, and compared (them) against each other via the use of blood markers,” Bhatraju said. “Patients with COVID-19 did not do worse than patients with other types of diseases that lead to ICU care. I think this is reassuring and suggests that while the underlying biology is different between COVID-19 and non-COVID-19, the outcomes are similar.”
One limitation of previous research has been the comparison of patients critically ill with COVID-19 with healthy patients, noted Dr. Eric Morrell, a co-first author of the paper.
“This is one of the largest studies to compare critically ill patients with and without COVID-19 who were enrolled at the same time,” which enables an “apples-to-apples” comparison, said Morrell. He is a UW assistant professor of pulmonary, critical care, and sleep medicine at the University of Washington School of Medicine.
The researchers started monitoring patient biomarkers in April 2020 and continued through September. Blood samples were drawn from 172 critically ill patients across both study groups; the first draw came within 24 hours of admission to the ICU and a second draw was taken three days later. The researchers tracked 22 biomarkers, looking specifically at endothelial and epithelial cells and inflammatory reactions in patients with and without COVID-19.
“The main question we were hoping to answer was whether there was something unique to COVID-19, and could this be used to develop therapeutics to treat people differently in the future,” Bhatraju said.
What the team discovered surprised them: Cells lining the blood vessels (endothelial cells) appeared to show less damage in COVID-19 patients than in critically ill patients without COVID-19.
“This study will narrow down the window of what type of therapeutics we should look at next,” Morrell said. “It indicates we should target drugs that will act as a therapeutic to the linings of the lung.”
He added that this research may redirect clinical use of drugs that target lung inflammation rather than inflammation in other organ systems.
“We also found that rates of hospital mortality and organ dysfunction were similar in critically ill patients with and without COVID-19. These findings differ from previous studies reporting extremely high rates of acute kidney injury, thrombosis and death in patients with COVID-19,” the report stated.
Funding was received from the National Institute of Diabetes and Digestive and Kidney Diseases (K23DK116967, R01DK124063), the National Heart, Lung, and Blood Institute (K23HL144916), National Institute of Allergy and Infectious Diseases (K08 AI119142), Bill and Melinda Gates Foundation, The Centers for Disease Control Foundation, an investigator initiated study grant from Roche, the Firland Foundation, and an unrestricted gift to the Kidney Research Institute from the Northwest Kidney Centers.
