By Dennis Thompson HealthDay Reporter
(HealthDay)
TUESDAY, Dec. 6, 2022 (HealthDay News) — Researchers can have sniffed out why colds are more likely in wintertime: The reply may lie throughout the nose.
A previously unidentified immune response contained in the nose is accountable for fighting off the viruses that cause upper respiratory infections, in keeping with researchers at Massachusetts Eye and Ear and Northeastern University in Boston.
Unfortunately, cold weather inhibits this protective response, making it more likely that an individual will come down with anything from a chilly to COVID-19.
The latest study offers the primary biological reason why respiratory virus infections usually tend to spike in colder seasons, researchers said.
“Conventionally, it was thought that cold and flu season occurred in cooler months because individuals are stuck indoors more where airborne viruses could spread more easily,” said senior researcher Dr. Benjamin Bleier, director of Otolaryngology Translational Research at Mass Eye and Ear.
“Our study, nonetheless, points to a biological root cause for the seasonal variation in upper respiratory viral infections we see annually, most recently demonstrated throughout the COVID-19 pandemic,” he said in a hospital news release.
The nose is a major entry point for viruses or bacteria, which might either be inhaled or directly deposited if an individual does something like rub their nose.
Once contained in the nose, germs work their way backward up the airway and into the body, infecting the cells along the way in which.
However the nose is able to fighting this infection. Cells within the front of the nose can detect inhaled germs, and respond by releasing billions of tiny fluid-filled sacs into mucus to surround and attack the pathogen.
These sacs, called extracellular vesicles (EVs), shuttle antibacterial proteins throughout the airway and form a protective blockade intended to maintain germs from spreading up the airway.
To see how this response works in various conditions, researchers collected samples from the noses of patients and volunteers. They then exposed those samples to 3 viruses — a coronavirus and two rhinoviruses that cause the common cold.
The viruses each triggered an EV response from nasal cells. The researchers also found that the EVs respond in a special approach to viruses — they carry receptors that snag the viruses before they’ll infect cells.
Nevertheless, the researchers found that colder temperatures affect this response.
Healthy volunteers placed in cold conditions — about 40 degrees Fahrenheit — experienced a temperature drop inside their nose.
Nose cells within the lab exposed to such a temperature decline delivered a blunted immune response, researchers found, secreting about 42% fewer EVs. Further, the antiviral receptors on the EVs were hampered by the cold.
“Combined, these findings provide a mechanistic explanation for the seasonal variation in upper respiratory infections,” said lead creator Di Huang, a research fellow at Mass Eye and Ear and Northeastern.
The researchers plan to explore in additional detail how the nose’s immune response protects against all forms of pathogens.
Additionally they think latest drugs could possibly be created that might induce and strengthen the nose’s immune response.
“The query now changes to, ‘How can we exploit this natural phenomenon and recreate a defensive mechanism within the nose and boost this protection, especially in colder months?'” said co-author Mansoor Amiji, professor of pharmaceutical sciences at Northeastern.
SOURCE: Massachusetts Eye and Ear, news release, Dec. 6, 2022
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