A team of researchers say they’ve discovered the reason why people tend to catch the common cold more in winter months.
What You Need To Know
- A team of researchers say they’ve discovered the reason why people tend to catch the common cold more in winter months
- In a study published Tuesday in The Journal of Allergy and Clinical Immunology, researchers say the answer is actually in our noses because their innate immune response is diminished in colder weather
- The researchers exposed healthy volunteers to an environment of 40 degrees Fahrenheit for 15 minutes and found that the number of extracellular vesicles that attack bacteria entering the nose decreased by nearly 42%
- The findings could also lead to the development of therapeutics that can strengthen the nose’s immune response
Colds are the results of ever-present germs invading our bodies, and it’s long been believed that the illnesses are more likely to occur when colder weather drives people indoors, where viruses can spread more easily.
But in a study published Tuesday in The Journal of Allergy and Clinical Immunology, researchers say the answer is actually in our noses because their innate immune response is diminished in colder weather.
A 2018 study discovered that when cells in the front of the nose detect a bacteria, they release extracellular vesicles, or EVs, into the nasal mucus that swarm and attack the bacteria. Dr. Benjamin Bleier of Harvard University-affiliated Massachusetts Eye and Ear, who co-led the study, compares it to “kicking a hornets’ nest.”
Essentially acting as decoys, the EVs carry receptors that bind to and block the virus.
“The more decoys, the more the EVs can mop up the viruses in the mucus before the viruses have a chance to bind to the nasal cells, which suppresses the infection,” Di Huang of Massachusetts Eye and Ear and Northeastern University School of Pharmacy said in a news release.
The EVs also distribute antibacterial proteins through the mucus from the front to the back of the nose, protecting other cells.
Building on that research, Bleier, Huang and other researchers set out to determine whether colder temperature impacted the nasal immune response.
They exposed healthy volunteers to an environment of 40 degrees Fahrenheit for 15 minutes and found that the temperature inside their noses fell by about 41 degrees. They then applied that reduction in temperature to nasal tissue samples and observed a weakened immune response in tests involving two common rhinoviruses and a coronavirus that cause colds. The numbers of EVs released by the nasal cells decreased by nearly 42% and the antiviral proteins also were impaired, making an infection more likely to occur.
“There’s never been a convincing reason why you have this very clear increase in viral infectivity in the cold months,” Bleier said in a news release. “This is the first quantitative and biologically plausible explanation that has been developed.”
Mansoor Amiji, chairman of Northeastern’s pharmaceutical sciences department who was involved in both studies, said he anticipates future studies will attempt to replicate the results with other viruses, including the one that causes COVID-19.
The findings could also lead to the development of therapeutics that can strengthen the nose’s immune response — imagine, for example, a nasal spray that increases the numbers of EVs inside the nose.
“We’ve uncovered a new immune mechanism in the nose that is constantly being bombarded, and have shown what compromises this protection,” Amiji said. “The question now changes to how can we exploit this natural phenomenon and recreate a defensive mechanism in the nose and boost this protection, especially in colder months.”
Bleier told CNN the research also supports the idea of wearing masks to protect against colds partly because they can keep the nose warmer.
“Not only do masks protect you from the direct inhalation of viruses, but it’s also like wearing a sweater on your nose,” he said.
