A tickle in the nose can help trigger a sneeze, expelling irritants and disease-causing pathogens. But the cellular pathways that control the sneeze reflex go far beyond the sinuses and have been poorly understood. Now, a team led by researchers at Washington University School of Medicine in St. Louis has identified, in mice, specific cells and proteins that control the sneeze reflex.
“Better understanding what causes us to sneeze — specifically how neurons behave in response to allergens and viruses — may point to treatments capable of slowing the spread of infectious respiratory diseases via sneezes,” said Qin Liu, associate professor of anesthesiology and the study’s senior investigator.
The findings are published June 15 in the journal Cell.
“We study the neural mechanism behind sneezing because so many people, including members of my own family, sneeze because of problems such as seasonal allergies and viral infections,” said Liu, a researcher in the university’s Center for the Study of Itch and Sensory Disorders. “Our goal is to understand how neurons behave in response to allergies and viral infections, including how they contribute to itchy eyes, sneezing and other symptoms. Our recent studies have uncovered links between nerve cells and other systems that could help in the development of treatments for sneezing and for fighting infectious respiratory diseases.”
Sneezing is the most forceful and common way to spread infectious droplets from respiratory infections. Scientists first identified a sneeze-evoking region in the central nervous system more than 20 years ago, but little has been understood regarding how the sneeze reflex works at the cellular and molecular level.
In the new study, Liu and her team established a mouse model in an attempt to identify which nerve cells send signals that make mice sneeze. The researchers exposed the mice to aerosolized droplets containing either histamine or capsaicin, a pungent compound made from chili peppers. Both elicited sneezes from the mice, as they do in people.