Study finds physical link between chilly weather, severity of colds

New research has revealed a physical link between chilly weather and the severity of colds, and it’s right under — or, rather, inside — our noses.

Researchers at Massachusetts Eye and Ear and Northeastern University have discovered an immune response inside the nose that fights incoming infections — when it is warm enough. The organ is a formidable front-line defender against the common cold and a host of other pathogens except during cold weather, they said in a study published this month in the Journal of Allergy and Clinical Immunology.

“Conventionally, it was thought that cold and flu season occurred in cooler months because people are stuck indoors more where airborne viruses could spread more easily,” Dr. Benjamin Bleier, director of Otolaryngology Translational Research at Mass Eye and Ear and senior author of the study, said in a statement.

“Our study, however, points to a biological root cause for the seasonal variation in upper respiratory viral infections we see each year, most recently demonstrated throughout the COVID-19 pandemic.”

We inhale pathogens through our nose, or rub our nose and transfer germs from our hands to our nasal passages. Then they work their way deeper into the body. The researchers built on the findings of a 2018 study, which determined that cells at the front of the nose release billions of “extracellular vesicles” (EVs), tiny sacs filled with fluid, that swarm the invaders.

“It’s akin to if you kick a hornets’ nest, and all the hornets come out and attack,” Bleier said.

The 2018 experiment was done on bacteria. For the current study, Mansoor Amiji, a distinguished professor of pharmaceutical sciences and chemical engineering at Northeastern, tried it on viruses and then took it a step further, studying the effects of temperature on this immune response.

Using cultured cells from volunteers, the team found that the number of EVs dropped when the temperature inside the nose went down by as little as 9 degrees. With fewer of EVs to bind to the virus particles and prevent entry, it was easier for an infection to root.

The researchers are hoping to use this information to beef up immunity or treat upper respiratory infections. The researchers also noted that masks can help by keeping the inside of the nose warm.