During cold and flu season, Canadians across the country do their best to avoid viruses behind these illnesses. But for the over 2 million people in Canada suffering from asthma, there's an even greater need to prevent the invasion of the viruses causing the common cold. It's because the onset of this type of infection can lead to a troubling battle that may lead to asthma attacks as well as the need for hospitalization.
The link between these viruses and asthma has been documented for well over 40 years. It was first brought to light in the early 1970s, when researchers realized one of the most common common cold viruses, rhinovirus, seemed to put asthmatics as a higher risk for complications. Unfortunately, the technology was not in place to figure out exactly how the viruses were causing the trouble. All that could be done was to offer a warning for other doctors to look out for this combination.
As the ability to examine our bodies at the molecular level increased, so did our understanding of how asthma patients responded to the virus. By the end of the 1990s, a clearer picture of the process was in place. There appeared to be a significant rise in one of the branches of the immune system known to seek out and kill everything in its path. As this sector responded to the invasion, the damage could lead to unintended consequences such as restriction of the airways.
But while researchers could see how complications progressed, they still were unable to detect the trigger causing the attacks. The breakthrough had to wait until 2005 when trials in human volunteers revealed how rhinovirus affected the immune response in the lungs. The researchers discovered the virus triggered the massive production of a particular protein. It's known officially as interferon-gamma inducible protein 10, but better known as IP-10.
Now there may be an answer thanks to a group of Polish researchers.
Normally, IP-10 is in charge of conducting the first line of attack against an unknown invader. It brings in immune cells known to kill whatever happens to be in their path. This lasts until the infection is identified by the immune system and it is able to develop a coordinated attack. At this point, the molecule declines as it is no longer needed.
However, in the case of rhinovirus infection, the levels of IP-10 do not disappear while the virus is still present. This means those indiscriminate immune killers keep on coming into the area. Over time, they lead to that unwanted damage in the lung tissue that could increase the chances for attacks.
While this information was useful in demonstrating how rhinovirus could lead to troubles, it still could not explain why those with asthma suffered more than healthier individuals. If rhinovirus was causing higher levels of the IP-10 molecule, everyone would end up at risk.
But now there may be an answer thanks to a group of Polish researchers. They took a deeper look at the effect of rhinovirus infection on asthmatics in the hopes of finding some difference from other individuals. Their results reveal asthma may in fact change the way the lungs function.
The team collected lung tissue samples from 10 patients suffering from asthma and nine healthy controls. The cells were taken to the lab where they were infected with rhinovirus. Then, over the course of two days, the levels of IP-10 and other factors were measured.
As expected, IP-10 was produced in all samples, regardless of disease status. But, in asthmatics, there was much, much more of this molecule. On average, asthmatic patients produced 36 times more. This meant these individuals would have to deal with a massive influx of the killing cells and be incredibly prone to damage.
But there was an even bigger surprise in store. In healthy individuals, the signals for the coordinated antiviral attack progressed as usual. But in the asthmatic samples, the cells were producing molecules known to reduce the chances for an allergic reaction. The cells somehow knew the potential for an asthmatic attack and were doing all they could to prevent it.
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While this result could be considered beneficial for an asthmatic, the reality is that it's exactly the opposite. The massive amount of IP-10 produced would lead to problems no matter how much the cells tried to stop the problem. Not to mention the lack of focus on the coordinated attack would allow the virus to stick around longer and increase the risk for troubles.
Although this information does not bode well for those suffering from asthma, the results suggest there may be routes to explore for treatment. The massive spike in IP-10 levels could be controlled in the future and reduce the chances for damage. Also, the use of molecules known to stimulate an antiviral attack could be supplemented to help reduce the length of infection. This may offer a path for novel therapies in the future.
In the meantime, the best way to stay safe is to avoid infection altogether. Unlike influenza, there are no vaccines for cold viruses such as rhinovirus. This means the best options are hand hygiene, personal distancing and staying home whilst sick. These methods are well-known and may help to prevent millions of Canadians from suffering even greater consequences as a result of catching a cold.
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