Mucus: Its Underappreciated Protective Role

rynner2

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#1
A mystery being uncovered:

'Brush' offers clues to fighting lung disease

Scientists say the discovery of an internal "brush" that helps clear lungs of unwanted matter could help them understand more about lung diseases.
A team from the University of North Carolina found that the brush-like layer pushes out sticky mucus and the foreign bodies it contains.
Writing in Science, it says that could help identify what goes wrong in cystic fibrosis, asthma and similar diseases.

UK lung experts said the work aided understanding of how lungs function.
The mucus, which helps collect inhaled pollutants, emerges as a runny nose and a wet cough.
Until now, most experts believed a watery substance acted as a lubricant and helped separate mucus from the cells lining airways.
But this did not tally with the fact that mucus remained in its own distinct layer.

The researchers used imaging techniques to examine what was happening within the lungs.
They were able to see a dense meshwork of human bronchial epithelial cell cultures.

The brush-like layer consists of protective molecules that keep sticky mucus from reaching the cilia and epithelial cells, thus ensuring the normal flow of mucus.

Dr Michael Rubinstein, who led the study, said: "The air we breathe isn't exactly clean, and we take in many dangerous elements with every breath.
"We need a mechanism to remove all the junk we breathe in, and the way it's done is with a very sticky gel, called mucus, that catches these particles and removes them with the help of tiny cilia."
"The cilia are constantly beating, even while we sleep.
"In a co-ordinated fashion, they push mucus, containing foreign objects, out of the lungs, and we either swallow it or spit it out.

"These cilia even beat for a few hours after we die. If they stopped, we'd be flooded with mucus that provides a fertile breeding ground for bacteria."

etc...

http://www.bbc.co.uk/news/health-19357090

Next time I cough up a gob of phlegm, I shall look at it with more interest!
 

EnolaGaia

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#2
Mucus has long been treated as an unwelcome by-product of biology. It is now becoming recognized as an active protective layer that supports and facilitates our immune systems.
For The First Time, Scientists Have Observed Mucus's Secret Ability to Subdue Germs

We are all full of mucus, and not only because cold season is upon us. Our bodies produce a fresh liter of slime each day to coat our passages and tracts. Mucus may be gross, but its grossness disguises how helpful it is.

A study published Monday in Nature Microbiology demonstrates one of mucus's unexpected beneficial properties: Mucus contains sugars that keep potentially harmful germs in check.

Biophysicist Katharina Ribbeck at the Massachusetts Institute of Technology has spent more than a decade exploring the biochemistry that happens within mucus.

"Mucus piqued my interest because it is just this vastly understudied material that occupies a large surface area in our body," Ribbeck said. The gel lubricates the esophagus, lines the stomach, helps sperm move past the cervix and guards nasal tissues.

Ribbeck and her colleagues study compounds called mucins in mucus. Mucins are long polymers, or molecular chains, densely studded with sugars. They "look like mini bottlebrushes," Ribbeck said, except bristling with sugar molecules where whiskers would be.

"Mucus has for too long been considered bad in general public, but also in medicine," said Gunnar C. Hansson, who studies mucin compounds at the University of Gothenburg in Sweden and was not a member of the team behind the new work.

"Mucus and mucins are extremely complex to study and has been lagging almost all other types of biomedical research."

The textbook model of mucus — a filter that traps and eliminates microbes — isn't entirely accurate.

"We added microbes into mucus and we saw they don't get trapped at all," Ribbeck said.

Inside a glob of mucus, bacteria swim freely, in a state the scientist describes as "planktonic." That helps our immune systems. A lone drifter, as opposed to many germs gathered in tough-to-penetrate clumps, makes an easier target for immune cells.
FULL STORY:
https://www.sciencealert.com/we-now...-extremely-helpful-function-of-subduing-germs
 

EnolaGaia

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#3
Here are the bibliographic particulars and the abstract from the published research article ...

Mucin glycans attenuate the virulence of Pseudomonas aeruginosa in infection

Kelsey M. Wheeler, Gerardo Cárcamo-Oyarce, Bradley S. Turner, Sheri Dellos-Nolan, Julia Y. Co, Sylvain Lehoux, Richard D. Cummings, Daniel J. Wozniak & Katharina Ribbeck

Nature Microbiology (2019)
Abstract

A slimy, hydrated mucus gel lines all wet epithelia in the human body, including the eyes, lungs, and gastrointestinal and urogenital tracts. Mucus forms the first line of defence while housing trillions of microorganisms that constitute the microbiota1. Rarely do these microorganisms cause infections in healthy mucus1, suggesting that mechanisms exist in the mucus layer that regulate virulence. Using the bacterium Pseudomonas aeruginosa and a three-dimensional (3D) laboratory model of native mucus, we determined that exposure to mucus triggers downregulation of virulence genes that are involved in quorum sensing, siderophore biosynthesis and toxin secretion, and rapidly disintegrates biofilms—a hallmark of mucosal infections. This phenotypic switch is triggered by mucins, which are polymers that are densely grafted with O-linked glycans that form the 3D scaffold inside mucus. Here, we show that isolated mucins act at various scales, suppressing distinct virulence pathways, promoting a planktonic lifestyle, reducing cytotoxicity to human epithelia in vitro and attenuating infection in a porcine burn model. Other viscous polymer solutions lack the same effect, indicating that the regulatory function of mucin does not result from its polymeric structure alone. We identify that interactions with P. aeruginosa are mediated by mucin-associated glycans (mucin glycans). By isolating glycans from the mucin backbone, we assessed the collective activity of hundreds of complex structures in solution. Similar to their grafted counterparts, free mucin glycans potently regulate bacterial phenotypes even at relatively low concentrations. This regulatory function is likely dependent on glycan complexity, as monosaccharides do not attenuate virulence. Thus, mucin glycans are potent host signals that ‘tame’ microorganisms, rendering them less harmful to the host.
SOURCE: https://www.nature.com/articles/s41564-019-0581-8
 

GNC

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#7
What's the difference between mucus and phlegm? (not the feedline for a joke)
 

EnolaGaia

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#8
What's the difference between mucus and phlegm? (not the feedline for a joke)
In strict usage ... Phlegm is the sub-category of mucus specific to the lungs and lower respiratory tract.
 

EnolaGaia

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#11
Thanks - but there's no real difference in its constitution?
Mucus is mutable based on pH and ionic conditions, so it can vary in viscosity. It can also vary in color depending on embedded impurities and / or side-effects of local infections. Setting aside these types of variation ...

I don't know how identical different areas of mucus may be (chemically) in the multiple places where it occurs (respiratory tracts, reproductive organs, intestinal tract, etc.).
 

GNC

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#12
It's a good thing I'm going to bed and won't have anything to eat till tomorrow, whereupon I will have forgotten this thread...
 

INT21

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#13
Mucus is mutable based on pH and ionic conditions, so it can vary in viscosity. It can also vary in color depending on embedded impurities and / or side-effects of local infections. Setting aside these types of variation ...

I don't know how identical different areas of mucus may be (chemically) in the multiple places where it occurs (respiratory tracts, reproductive organs, intestinal tract, etc.).
So, 'snot always what it's made out to be ?
 

Ogdred Weary

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#14
When viewing the main forum, if this thread comes up the word count cuts it down to "Mucus: Its Underappreciated Prote", which prompts my mind to complete the final word as "protein".

 
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