Bacteria are present in just about every breath of air we take in. How the airway protects itself from infection from these bacteria has largely remained a mystery — until now. When bacteria are inhaled, exosomes, or tiny fluid-filled vesicles, are immediately secreted from cells that directly attack the bacteria and also shuttle protective antimicrobial proteins from the front of the nose to the back along the airway, protecting other cells against the bacteria before they get too far into the body. A research team from Massachusetts Eye and Ear describes this newly discovered mechanism in a report publishd online on November 12, 2018 in the Journal of Allergy and Clinical Immunology (JACI). The findings shed new light on our immune systems — and also pave the way for drug delivery techniques to be developed that harness this natural transportation process from one group of cells to another. The article is titled “Exosome Swarms Eliminate Airway Pathogens and Provide Passive Epithelial Immunoprotection Through Nitric Oxide.” “Similar to kicking a hornets’ nest, the nose releases billions of exosomes into the mucus at the first sign bacteria, killing the bacteria and arming cells throughout the airway with a natural, potent defense,” said senior author Benjamin S. Bleier, MD, a sinus surgeon at Massachusetts Eye and Ear and Associate Professor of Otolaryngology at Harvard Medical School. “It’s almost like this swarm of exosomes vaccinates cells farther down the airway against a microbe before they even have a chance to see it.” The JACI study was motivated by a perplexing previous finding from Dr. Bleier’s lab a few years ago. In studies of sinus inflammation, researchers found that proteins in the cells of the nasal cavity were also present in patients’ nasal mucus.
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