McMaster researchers say web-like immune response could lead to COVID vaccine in nasal spray form

This undated electron microscope image made available by the U.S. National Institutes of Health in February 2020 shows the Novel Coronavirus SARS-CoV-2, yellow, emerging from the surface of cells, blue/pink, cultured in the lab. Also known as 2019-nCoV, the virus causes COVID-19. THE CANADIAN PRESS/AP-NIAID-RML via AP. THE CANADIAN PRESS/AP-NIAID-RML via AP

A research project at Hamilton’s McMaster University is looking at potential applications for a tool in the human immune system that reacts like a “spider web” when engaging microorganisms that can cause disease like SARS-CoV-2 – the virus responsible for COVID-19.

Immunologists at the university say they’ve discovered a “previously unknown mechanism” tied to a type of white blood cell, neutrophils, which explode when binding to pathogens releasing DNA outside of a cell creating a sticky tangle that acts as a trap.

The study’s lead author Matthew Miller, an associate professor at McMaster’s Michael G. DeGroote Institute for Infectious Disease Research, says the potential applications for such a reaction could lead to the manufacture of aerosol and nasal spray technologies that could help head off infections in the body.

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“Vaccines can produce these antibodies that are present in our lungs, which are the first type of antibody to see viruses like flu or COVID-19, which infect our lungs and respiratory tracts,” Miller said in a release.

“Mechanisms that can stop the infection at the site where it enters our body can prevent the spread and serious complications.”

Hannah Stacey, a graduate student in the Miller Lab and lead author of the paper, says current injectable vaccines bolster antibodies in the blood, but the antibodies typically are not present where an infection begins.

“We should be thinking carefully about next-generation COVID-19 vaccines that could be administered in the respiratory tract to stimulate antibodies. We don’t have many candidates right now that are focused on raising the mucosal response,” said Stacey.

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“If you want a lot of these antibodies that are really abundant in blood, then injections make the most sense, but if you want antibodies that are abundant in the respiratory tract, then a spray or an aerosol makes sense.”

The downside to the potential “spider-web” treatment is a lack of control, according to the researchers.

Miller points to an early wave of the pandemic when the so-called NETs (neutrophil extracellular traps) were actually found in some patients’ lungs, and made their breathing difficult.

The mechanism does have the potential to cause inflammation and further illness if the web is not properly restrained.

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“An immune response that is meant to protect you can end up harming you if it’s not properly controlled,” said Miller.

“It’s important to understand the balance of the immune system. If you have a lot of these antibodies before you get infected, they are likely going to protect you, but if the infection itself stimulates a lot of those antibodies it might be harmful.”

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