Nasal microbiota holds clues to who will develop symptoms from novel coronavirus

Date:
September 28, 2021
Source:
Medical College of Georgia at Augusta University
Summary:
The microbiota in the nose and upper throat likely contains
biomarkers for assessing how sick an individual infected with
SARS-CoV-2 may get and for developing new treatment strategies to
improve their outcome, researchers say.



FULL STORY ==========================================================================
The microbiota in the nose and upper throat likely contains biomarkers
for assessing how sick an individual infected with SARS-CoV-2 may get
and for developing new treatment strategies to improve their outcome, researchers say.


==========================================================================
This nasopharyngeal microbiota is generally considered a frontline
protection against viruses, bacteria and other pathogens that enter these natural passageways, says Dr. Sadanand Fulzele, geriatric researcher in
the Department of Medicine at the Medical College of Georgia at Augusta University.

Distinct patterns emerged when the researchers examined the microbiota
of 27 individuals age 49 to 78 who were negative for the virus, 30
who were positive but had no symptoms, and 27 who were positive with
moderate symptoms that did not require hospitalization, they report in
the journal Diagnostics.

"Millions of people get infected and relatively few of them become
symptomatic.

This might be one of the reasons," says Dr. Ravindra Kolhe, director of
MCG's Georgia Esoteric and Molecular Laboratory, or GEM Lab. which has performed more than 100,000 COVID tests.

The most significant changes were in those who were symptomatic, including about half those patients not having a sufficient amount of microbiota
to even sequence, says corresponding author Fulzele.

They were surprised to find these "low reads" of bacteria in the
nasopharyngeal cavity of symptomatic individuals versus only two and
four individuals in the negative and positive with no symptoms groups, respectively. The vast majority of the positive individuals with no
symptoms still had sufficient microbiota, notes first author Kolhe.



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"We don't know which came first, the disease or the wipeout of the
microbiota," Fulzele says. Runny noses and sneezing might account for
the loss, an already significantly lower number of bacterial inhabitants
might have increased the individuals' risk for developing these kinds
of symptoms, or the virus may have changed the landscape, says Fulzele,
who suspects it's the latter.

Based on experience with microbiota in the gastrointestinal tract, Kolhe
thinks the different microbiota content and size is another good bet and
they both would like a definitive answer. "We don't have sufficient data
at this moment," Kolhe says.

They found differences in the type of bacteria as well, although the researchers note that the function of some of the bacteria they found
are not well understood.

As the virus' name and nearly two years of experience with it indicate,
a major method for transmitting severe acute respiratory syndrome
coronavirus 2, or SARS-Cov-2, is when someone coughs, sneezes or even
talks, and droplets called aerosols carrying the virus move through the
air and into another person's nose or mouth.

Those age 65 and older and/or with underlying health conditions
like hypertension and diabetes, are considered at increased risk for hospitalization and death from the infection, so they decided to look
at the microbiota in the upper part of the respiratory system called
the nasopharynx of older individuals.



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The moist, mucus-producing lining of this area works like a natural
barrier to invaders and there also is a significant complement of immune
cells present, Fulzele says, and their response to respiratory viruses
is key.

The area also is abundant with ACE-2 receptors, to which the spiky virus
binds, and Kolhe says it's a major landing spot for this virus.

Their new findings indicate that the altered microbiota in the symptomatic patients impacted their immune response to the virus, Kolhe and Fulzele
say.

The symptomatic individuals had significantly higher levels of two
bacterial species, including Cutibacterium, generally found on the skin
and associated with acne but also with heart infection and shoulder
infections following surgery. Conversely there was a significantly lower presence of a handful of other, not well-studied bacterium.

The microbiota of both infected groups, symptomatic and asymptomatic,
had high levels of bacterium like Cyanobacteria, also called blue green
algae, that can be found in contaminated water but is a usual inhabitant
of the microbiome in humans which appears to have a role in regulating
the immune response. These bacterium typically enter the body through
mucosal surfaces, like those in the nose, and are known to cause pneumonia
and liver damage. Those who were symptomatic had twice as much of this bacterium as their asymptomatic counterparts.

Fulzele notes that between the asymptomatic and symptomatic there was no significant change in microbiota diversity -- just those big differences
in volume -- but they did see a lot of individual bacterium moving up
and down in numbers.

For example, their graph of the number of another water-loving bacterium Amylibacter, looked like stair steps as it moved from negative to positive
with symptoms individuals, while there was a downward trend in a handful
of other bacterium.

While the relationship between the nasopharyngeal microbiota and the
severity of COVID-19 remains unknown, their study indicates a "strong association" between the nasal microbiota, SARS-CoV-2 infection and
severity, they write.

Their analysis was done before the current virus variants began to
surface, but the researchers say the differences in the microbiota likely
will hold for these as well and they have already begun that analysis.

Larger studies are needed to ensure that the clear patterns they found
hold, the researchers say. They are putting together a grant application
that will enable a larger study and looking for other testing sites who
want to be partners. Using the same nasopharyngeal swab used for many
COVID tests would enable a microbiota analysis to be done at the same
time as testing, they say.

They note the striking contrast that has emerged over nearly two years
of experience with the virus, with the majority of those infected being asymptomatic or experiencing mild symptoms like they would with a cold,
while others get severe viral pneumonia, require hospitalization and die.

A handful of recent studies have now been published suggesting that the bacterial composition of the nasal canal can have a "drastic" influence
on the development of respiratory infections and the severity of symptoms,
they write.

Some studies have indicated that the nasal microbiota can influence
the viral load, immune response and symptoms of a rhinovirus infection,
which is responsible for somewhere between 10-40% of common colds.

A myriad of other conditions like inflammatory bowel syndrome, peptic
ulcers and viral diseases have been linked to significant changes in
the microbiota of the gut, nasal and oral cavity, they write.

Diversity of bacterium in the microbiota is generally a good thing,
and it's something that naturally decreases with age, says Fulzele,
and also can be harmed by habits like smoking and improved by those like
eating a diverse diet.

The work was supported in part by the National Institutes of Health.

========================================================================== Story Source: Materials provided by Medical_College_of_Georgia_at_Augusta_University.

Original written by Toni Baker. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Ravindra Kolhe, Nikhil Shri Sahajpal, Sagar Vyavahare, Akhilesh S.

Dhanani, Satish Adusumilli, Sudha Ananth, Ashis K. Mondal, G. Taylor
Patterson, Sandeep Kumar, Amyn M. Rojiani, Carlos M. Isales,
Sadanand Fulzele. Alteration in Nasopharyngeal Microbiota Profile
in Aged Patients with COVID-19. Diagnostics, 2021; 11 (9): 1622 DOI:
10.3390/ diagnostics11091622 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210928074951.htm

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