The cellular pathways that control the sneeze reflex go far beyond the sinuses and until recently have been poorly understood. A recent mouse model study published in Cell has identified specific cells and proteins that control the sneeze reflex (Cell. Published online ahead of print June 10, 2021. doi:10.1016/j. cell.2021.05.017).
For this study, researchers, led by senior investigator Qin Liu, PhD, an associate professor of anesthesiology at the Washington University School of Medicine in St. Louis, exposed the mice to aerosolized droplets containing either histamine or capsaicin, a pungent compound made from chili peppers that elicite sneezes. By examining nerve cells that were already known to react to capsaicin, they were able to identify a class of small neurons linked to the sneezing. The researchers then looked for neuropeptides that could transmit sneeze signals to those nerve cells and found that the molecule neuromedin B (NMB) was required for sneezing. Conversely, eliminating the NMB-sensitive neurons in the part of the nervous system that evoked sneezes in the mice, blocked the sneeze reflex. Researchers also found that NMB-sensitive neurons further project to the caudal ventral respiratory group, so that chemical activation of NMB-sensitive neurons led to sneezing despite the mice not being exposed to capsaicin, histamine, or other allergens.
“To prevent future viral outbreaks and help treat pathological sneezing caused by allergens, it will be important to understand the pathways that cause sneezing in order to block them,” said Dr. Liu in a press release. “By identifying neurons that mediate the sneeze reflex, as well as neuropeptides that activate these neurons, we have discovered targets that could lead to treatments for pathological sneezing or strategies for limiting the spread of infections.”