When the body is fighting infection, the immune system kicks into high gear. It may not be acting alone, however. Research by HMS scientists indicates that the nervous system may also be involved, particularly in deadly lung infections.
In work carried out in mice, scientists in the HMS departments of Microbiology and Immunobiology and Cell Biology, the Evergrande Center for Immunologic Diseases at HMS, Brigham and Women’s Hospital, and the University of Calgary in Alberta, Canada, found that neurons carrying nerve signals to and from the lungs suppress immune response during infection with Staphylococcus aureus. This bacterium, which is growing increasingly impervious to antibiotics, has emerged as a top killer of hospitalized patients.
In the lungs, sensory neurons detect mechanical pressure, inflammation, temperature change, and the presence of chemical irritants, then send an alert to the brain—a notification that can come in the form of pain, airway constriction, or a cough that expels harmful agents or particles from the airways.
This study, however, revealed that when mouse lungs are invaded by staph bacteria, sensory neurons reduce the lungs’ ability to summon several types of disease-fighting cells in response to infection. A second set of experiments showed that disabling these neurons in mice promoted immune-cell recruitment, increased the lungs’ ability to clear bacteria, and boosted survival in staph-infected mice.
According to the researchers, the results suggest that different classes of sensory neurons may be involved in restraining or promoting immune response. These findings could pave the way to nonantibiotic therapies for bacterial pneumonia that would target neuroimmune signaling in the lungs.
Baral P, et al., Nature Medicine, March 2018