Why does COVID-19 impact only some organs, not others?

Date:
August 11, 2020
Source:
American Institute of Physics
Summary:
COVID-19 proliferates through a receptor present in most of the
human body. But if the receptor is so pervasive, why does the
virus seem to target only specific organs?


FULL STORY ==========================================================================
In severe cases of COVID-19, damage can spread beyond the lungs and
into other organs, such as the heart, liver, kidney and parts of the neurological system.

Beyond these specific sets of organs, however, the virus seems to
lack impact.


========================================================================== Ernesto Estrada, from the University of Zaragoza and Agencia Aragonesa
para la Investigacio'n Foundation in Spain, aimed to uncover an
explanation as to how it is possible for these damages to propagate
selectively rather than affecting the entire body. He discusses his
findings in the journal Chaos, from AIP Publishing.

In order to enter human cells, the coronavirus relies on interactions
with an abundant protein called angiotensin-converting enzyme 2.

"This receptor is ubiquitous in most human organs, such that if the
virus is circulating in the body, it can also enter into other organs
and affect them," Estrada said. "However, the virus affects some organs selectively and not all, as expected from these potential mechanisms."
Once inside a human cell, the virus's proteins interact with those
in the body, allowing for its effects to cultivate. COVID-19 damages
only a subset of organs, signaling to Estrada that there must be a
different pathway for its transmission. To uncover a plausible route,
he considered the displacements of proteins prevalent in the lungs and
how they interact with proteins in other organs.

"For two proteins to find each other and form an interaction complex,
they need to move inside the cell in a subdiffusive way," Estrada said.

He described this subdiffusive motion as resembling a drunkard walking
on a crowded street. The crowd presents obstacles to the drunkard,
stunting displacement and making it difficult to reach the destination.

Similarly, proteins in a cell face several crowded obstacles they must
overcome in order to interact. Adding to the complexity of the process,
some proteins exist within the same cell or organ, but others do not.

Taking these into account, Estrada developed a mathematical model
that allowed him to find a group of 59 proteins within the lungs that
act as the primary activators affecting other human organs. A chain of interactions, beginning with this set, triggers changes in proteins down
the line, ultimately impacting their health.

"Targeting some of these proteins in the lungs with existing drugs will
prevent the perturbation of the proteins expressed in organs other than
the lungs, avoiding multiorgan failure, which, in many cases, conduces
the death of the patient," Estrada said.

How the affected proteins travel between organs remains an open question
that Estrada is dedicating for future studies.

The article, "Fractional diffusion on the human proteome as an
alternative to the multi-organ damage of SARS CoV-2," is authored by
Ernesto Estrada. The article will appear in Chaos on Aug. 11, 2020.


========================================================================== Story Source: Materials provided by American_Institute_of_Physics. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Ernesto Estrada. Fractional diffusion on the human proteome as an
alternative to the multi-organ damage of SARS-CoV-2. Chaos: An
Interdisciplinary Journal of Nonlinear Science, 2020; 30 (8):
081104 DOI: 10.1063/5.0015626 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200811120150.htm

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