Scientists have found that individuals with asthma are, in fact, less susceptible to COVID-19. One could question how a pre-existing health condition could actually aid in fighting off a virus? It is accurate to assume that an individual with allergy asthma would be at more risk than a perfectly healthy individual. 

Allergic asthma occurs when your airways tighten when an allergen is inhaled. The same immune system proteins that are involved with excess mucus production and the tightening of airways are used to form barriers around exposed airway cells (immune system mechanism for people with allergy asthma). This information is the basis behind the studies that explains the reasoning behind why people with asthma are less susceptible to COVID-19. 

Asthma attack-airway (bronchiole) constriction-animated

When a patient has asthma, usually the development viruses such as the Flu and Strep Throat are more dangerous for them, and still these patients with asthma are at more risk when they are infected with COVID-19. The difference lies between asthma and allergic asthma. Researchers were able to identify that people with allergic asthma were not showing major symptoms to COVID-19, which was not what one would expect. Why is that? 

Protein Protection

The differentiating factor that sets allergic asthma from regular asthma is a specific protein called interleukin-13 (IL-13). The normal function of IL-13 is to help fight off parasites. Normally, specific T-Cells release this protein. In response to the release of IL-13, the body produces a sticky mucus substance and compacts airways. This traps the parasite until the immune system finishes the job by killing the parasite. 

However, when an individual has allergic asthma, the body mistakes harmless matter such as pollen for a parasite, and uses IL-13 when it is not needed. The researchers now need to determine how, exactly, IL-13 is protecting patients from COVID-19.

Protein IL13 PDB 1ga3

No IL-13 Present Study

Researchers conducted a study in which they would compare how cells that haven’t  been treated with the IL-13 protein react when healthy and when infected with coronavirus. 

It was found that the healthy cells  grew in lawns that nearly resembled grassland. This area is made Bronchiolar epithelium 3 - SEMup of a hair-like substance called cilium. The cilia move in waves which aids in mucus movement and the excretion of anything stuck in the mucus.

On the other hand, the cells that were infected with the coronavirus had a much different reaction. The cilia lawn was no longer clear. The cilia was covered with mucus and many bald spots that seemed as if infected cells died. The infected cells were compressed out of the lawn of the cilia, and in that process they become inflated. This inflation occurs due to vacuoles in the infected cells getting blocked up with viruses. Once the infected cell gets filled up with viruses past its capacity, it explodes and releases all of the viruses that had been in the cell. 

Unfortunately, it is not as simple as this singular reaction, not all cells that were in the infected lawn were affected the same way. Researchers noticed that the cells that were attached to the cilia were infected with SARS-CoV-2, but the goblet cells, which are mucus producing cells, were barely affected. The researchers found that a protein called ACE2 is present on the surface of ciliated cells more commonly that goblet cells. With this finding, the researchers can assume that ACE2 is the protein receptor that allows SARS-CoV-2 to enter the cell. 

IL-13 Present 

Now the researchers conducted a second study in which they will coat the cell in  the IL-13 protein and compare how the cell reacts when infected with coronavirus. The celia lawn surface with the IL-13 present has a lot less inflated dying cells on its surface and the movement of the cilia was much less rapid. This decrease in movement indicates that the mucus is present in the cilia for much longer than when IL-13 is not present. It was made clear that the IL-13 protein acted as a protectant towards the infection. 

They later found out that untreated cells, once infected with SARS-CoV-2, release bursts of mucus. Whereas the IL-13 cells keep the mucus stored. Furthermore, it is known that IL-13 proteins produce a sticky mucus that has the ability to trap viruses before they get the chance to infect the cell. So, this excess mucus that is present in the treated cells can make sure the virus is out of the lungs before the damage has been done. Researchers also found A thick layer of keratan sulfate that was developed on the cell’s surface that was treated with IL-13, which protects them against SARS-CoV-2 from coming into contact with the cell.

In addition to protecting the cells, the IL-3 protein causes cells to produce less ACE2. And with less ACE2, not as many SARS-CoV-2 can come into the cell, since ACE2 is the SARS-CoV-2 receptor. 

There is so much unknown about IL-3, and researchers are still trying to determine specific properties of this protein. Scientists are eager to find out more about IL-13 as they think this protein can lead to new treatment findings.

This new information about how people with allergy asthma react to COVID-19 can be looked at as a positive because it’s one thing about having allergy asthma that actually benefited the individual!



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