As the novel coronavirus pandemic continues, 11 international medical research organizations are investigating why some COVID-19 patients have more severe reactions than others. The consortium (NETwork) researchers believe that overactive immune cells that produce Neutrophil Extracellular Traps (NETs).
Many COVID-19 patients with severe symptoms develop Acute Respiratory Distress Syndrome (ARDS), as well as pulmonary inflammation, mucus in the lungs, and blood clots. Patients who develop ARDS and these other symptoms are in grave danger, and many die as a result. The NETwork believes that these severe cases might be caused by overactive neutrophils (white blood cells), which can detect bacteria and use their own DNA to attack the bacteria with a web of toxic enzymes, called a NET. NETs digest pathogens, but in patients with ARDS, NETs end up causing lung damage.
According to Betsy Barnes, Ph.D., lead and co-corresponding paper author and professor at the Feinstein Institutes, “Given the clear similarities between the clinical presentation of severe COVID-19 and other known diseases driven by NETs, such as ARDS, we propose that excess NETs may play a major role in the disease. As samples from patients become available, it will be important to determine whether the presence of NETs associates with disease severity and/or particular clinical characteristics of COVID-19.”
"NETs were identified in 2004, but many scientists have never heard of them. Most of the researchers in the NETwork have worked on NETs in other diseases, and when we started hearing about the symptoms of the COVID-19 patients, it sounded familiar," said Cold Spring Harbor Laboratory cancer biologist Mikala Egeblad, Ph.D., the senior and corresponding author of the paper.
Jonathan Spicer, M.D., Ph.D., a clinician-scientist at the Research Institute of the McGill University Health Center and Assistant Professor of Surgery at McGill University noted, "We see in these patients severe lung damage known as ARDS, another serious problem caused by excess NETs and seen in cases of severe influenza. In addition, their airways are often clogged with thick mucus and unlike most severe lung infections, these patients tend to form small clots throughout their body at much higher rates than normal. NETs have also been found in the blood of patients with sepsis or cancer, where they can facilitate the formation of such blood clots."
The researchers are now investigating if NETs are common to COVID-19 cases. Their work is published in the Journal of Experimental Medicine.