The human body has several built-in defenses that protect against illness, but some of these processes are still a mystery. Recent research reveals new insight into how the nasal airway works to protect us from bacteria.
A team from Massachusetts Eye and Ear developed and reported the research, publishing it in the Journal of Allergy and Clinical Immunology.
Researchers discovered that cells secrete small fluid-filled sacs called exosomes when we inhale bacteria. Once secreted, exosomes promptly attack the bacteria and also send antimicrobial molecules to nearby areas in the nose.
A team led by Dr. Benjamin Bleier, a sinus surgeon at Massachusetts Eye and Ear and associate professor of otolaryngology at Harvard Medical School, wanted to expand on previous findings where they discovered that proteins found in the cells of the nasal cavity were also present in a person’s nasal mucus.
The researchers were interested in finding out how exosomes were moving from the cells into the mucus.
To do this, they collected the mucus of participants and grew their cells out in laboratory culture. To determine what happened when these cells came into contact with germs, they simulated exposure to bacteria and then calculated the number of released exosomes.
The results showed that exosome numbers “swarmed” — they doubled after bacterial exposure, as did antibacterial molecules.
“Similar to kicking a hornets’ nest, the nose releases billions of exosomes into the mucus at the first sign [of] bacteria, killing the bacteria and arming cells throughout the airway with a natural, potent defense.”
Dr. Bleier, senior author
The team then conducted experiments using patients and discovered that the resulting exosomes successfully killed the bacteria — as effectively as antibiotics, even.
As Dr. Bleier explains, “It’s almost like this swarm of exosomes vaccinates cells further down the airway against a microbe before they even have a chance to see it.”
The researchers also showed that these exosomes were taken up by other cells in the area and could share their antimicrobial molecules. This was the answer the team was after.
The exosomes can help cells at the back of the nose prepare to fight off bacteria, as well, before they even get there, which is a neat vaccination-type boost to our body’s initial defenses.
There is another natural defense inside the nasal airways that we probably don’t think about often, and when we do, we probably don’t think about it fondly.
Mucus tends to become an issue when we have a cold virus or allergies, and it can feel like a nuisance. However, mucus is one way our bodies deal with pathogens and eliminate them before we become sick.
The human body produces mucus continually, and it covers 400 square meters of surface area inside every adult — about the size of a basketball court.
Sites that produce mucus include our lungs, digestive system, urinary tract, reproductive tract, eyes, and nose.
Mucus helps trap pathogens that break through one of the body’s entry points, and it helps kill those germs or isolate them. As far as the nose goes, a person can then blow the germs out with a tissue.
The latest research on exosomes helps scientists understand the immune system a little better and may lead to a new way to deliver medications.
In the future, it could potentially lead to the development of drugs that take advantage of this natural transportation process already in place in our bodies.
As a group of cells can transport antibodies down the airway to ward off attacks in places where bacteria have yet to invade, it may be possible to use this innate system to shuttle medications along the same pathway.
As Dr. Bleier observes, “The nose provides a unique opportunity to directly study the immune system of the entire human airway — including the lungs.”