SNHS Biology Blog 13: ‘Spider-Man’ Immune Response May Promote Severe COVID-19

Ria Mathew

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Neutrophils, or cells involved with the immune system shows potential in the fight against COVID-19. Neutrophils compose a large part of the immune system, and play a major role in fighting off infections. Once an invader is sensed in the immune system, neutrophils eat the invader, or rally up other white blood cells to get rid of the invader. An interesting property of neutrophils was discovered: they could shoot webs of DNA and harmful proteins which could confine the pathogen and halt the spread of disease, but die in the process. In a recent study published on April 24th, reports of NETs (neutrophil extracellular traps) were found in samples from COVID patients. With COVID-19 patients who had NETs, their lungs were filled with mucus and had a plethora of neutrophils. In 2004 a paper was published about NETs in dysentery and appendicitis. Andrew Weber and Mikala Egeblad partnered to study the role of NETs in COVID-19 patients, but their trial was delayed due to the pandemic outbreak.

Although they couldn’t continue their trial, Weber and Egeblad found health records of patients across the globe, in locations such as Italy, China etc. Through a deliberate search of records, Weber found patients had a high amount of neutrophils, which fueled his desire to understand NETs. Weber and his team, along with rheumatologist Jason S. Knight, created the NETwork, an association, to discuss protocols and help the scientists get an idea of NETs works. The Journal of Experimental Medicine proposed an explanation- with the sickest COVID-19 patients, the immune system would form a plethora of cytokines. With the rapid generation of cytokines, acute respiratory distress syndrome (ARDS) could develop and worsen the condition of the patient. Research has found a correlation between ARDS and NETs. Specifically with COVID patients, WEber and his team discovered NETs in 50 patients, compared to healthy controls which highlights how NETs plays a role in the coronavirus. James Chalmers, a pulmonologist, created a study which tests an enzymes’ efficiency of preventing NETs. The enzyme reduced inflammation with patients infected with bronchiectasis. More drugs are also being tested, such as medication for dornase alfa and drugs approved for rheumatoid arthritis and gout, for COVID-19 patients. There is not much research about NETs, so it is difficult for scientists to understand why neutrophils die in the process, and it is hard to detect neutrophils in labs. Further research is needed to understand the link between cytokines and NETs, and how neutrophils interact with macrophages (another immune cell). One possible explanation for how NETs relates to COVID-19 is that when neutrophils eject their webs, it is for the purpose of fighting infection, but the neutrophils may not function accordingly, and the coronavirus can continue to infect and make patients sicker.