Exosomes May Hold Key To Improving Drug Therapy, Harvard Study Finds

Every time we breathe in through our noses, a battle breaks out between bacteria trying to invade our bodies and the immune systems tasked with keeping us healthy.

A new study of this constant struggle might have big implications for how doctors administer medicine to patients.

Researchers at Harvard Medical School have uncovered how tiny, fluid-filled sacs called exosomes have the ability to shuttle bacteria-fighting proteins throughout the airway. Scientists are now weighing how to use this natural transport system to speed up treatments for infections, nausea and more.

Dr. Benjamin Bleier, a sinus surgeon and professor at Harvard Medical School and the study’s senior author, discussed how these new discoveries can impact the future of drug therapy.

On what led to the study

"The study of exosomes is a relatively young field. But there has been a lot of recent work in it. And I came across some studies in any culture in [gastrointestinal] epithelial cell cultures which showed that exosomes in the gut may be capable of attacking certain types of bacteria. And so, that's interesting because we've shown that exosomes are present in the nose and they're present not only in disease but also in the state of health. So we have this question of, what are exosomes doing in the normal healthy human nose and how could that relate to some of the findings of some function in other parts of the body?"

On what an exosome is and why it's important

"When your nose breathes in bacteria, the cells in the front of the nose detect the presence of the bacteria and then the exosomes are released to go and fight off that bacteria. We call it sort of a swarm function because it's sort of analogous to if you kick a hornet's nest, the hornets will come out and attack whoever is attacking the nest itself.

At the same time, we know that the exosomes would then go into the mucus and be carried backwards in the nose. And so the exosomes, after being exposed to bacteria and having this early warning sign, are carried toward the back of the nose and transport some protective proteins to the other cells in the back of the nose as the same bacteria are being transported in the mucous layer."

On what the findings mean

"The most interesting [thing] about it is that this is really the only example of an innate immune function in the human body where the immune system actually leaves the body itself to go attack an external invader.

Also, we showed that the exosomes released into the mucus had the same effect on the bacteria as an antibiotic. These are very powerful microbial proteins that are unleashed to go and kill the invading bacteria and then are actually donated to the adjacent epithelial cells."

On how the new discovery help drug treatments

"These exosomes are exquisitely able to be taken up by other cells of the nose. We actually show that they're taken up within minutes, which is really important. For example, if you put a tablet or some powder of saccharin or sugar on the on the tip of the nose inside, the patient will typically say that they can taste a sweet taste within 15 to 20 minutes. So that's how long it takes for something to touch the front of the nose and be transported all the way to the back.

There are things like pain medication, anti-nausea medication, seizure medications and things like that, that are that are currently administered as nasal sprays. This is a much more efficient way if you are able to encapsulate it in the exosomes because they're essentially designed to be absorbed by the cells of the nose."

On the future direction of the study

"We’re starting to look at how exosomes may be a way that the body regulates the healthy bacteria and keep them in check and prevent the bad bacteria from overtaking it. And then by studying these new components of the immune system and using new tools ... we’re actually able to identify new diseases and biomarkers for diseases and then also develop therapeutics to fight those diseases."