Study reveals what triggers lung damage during COVID-19
A longitudinal study of macrophages from SARS-CoV-2 infected lungs offers
new insights into dynamic immunological changes

Date:
August 4, 2021
Source:
The Korea Advanced Institute of Science and Technology (KAIST)
Summary:
Researchers found that a specific subtype of macrophages
that originated from blood monocytes plays a key role in the
hyper-inflammatory response in SARS-CoV-2 infected lungs, by
performing single-cell RNA sequencing of bronchoalveolar lavage
fluid cells. This study provides new insights for understanding
dynamic changes in immune responses to COVID-19.



FULL STORY ==========================================================================
A KAIST immunology research team found that a specific subtype of
macrophages that originated from blood monocytes plays a key role in the hyper-inflammatory response in SARS-CoV-2 infected lungs, by performing single-cell RNA sequencing of bronchoalveolar lavage fluid cells. This
study provides new insights for understanding dynamic changes in immune responses to COVID-19.


==========================================================================
In the early phase of COVID-19, SARS-CoV-2 infected lung tissue and the immediate defense system is activated. This early and fast response
is called 'innate immunity,' provided by immune cells residing in
lungs. Macrophages are major cell types of the innate immune system of
the lungs, and newly differentiated macrophages originating from the bloodstream also contribute to early defenses against viruses.

Professor Su-Hyung Park and his collaborators investigated the
quantitative and qualitative evaluation of immune responses in the
lungs of SARS-CoV-2 infected ferrets. To overcome the limitations
of research using patient-originated specimens, the researchers used a
ferret infection model to obtain SARS-CoV- 2 infected lungs sequentially
with a defined time interval.

The researchers analyzed the 10 subtypes of macrophages during the
five-day course of SARS-CoV-2 infection, and found that infiltrating macrophages originating from activated monocytes in the blood were key
players for viral clearance as well as damaged lung tissue. Moreover,
they found that the differentiation process of these inflammatory
macrophages resembled the immune responses in the lung tissue of severe COVID-19 patients.

Currently, the research team is conducting a follow-up study to
identify the dynamic changes in immune responses during the use of immunosuppressive agents to control hyper-inflammatory response called 'cytokine storm' in patients with COVID-19.

Dr. Jeong Seok Lee, the chief medical officer at Genome Insight Inc., explained, "Our analysis will enhance the understanding of the early
features of COVID-19 immunity and provide a scientific background for
the more precise use of immunosuppressive agents targeting specific
macrophage subtypes." "This study is the first longitudinal study using sequentially obtained immune cells originating from SARS-CoV-2 infected
lungs. The research describes the innate immune response to COVID-19
using single cell transcriptome data and enhances our understanding of
the two phases of inflammatory responses," Professor Park said.

This work was supported by the Ministry of Health and Welfare and KAIST,
and was published in Nature Communications on July 28.

========================================================================== Story Source: Materials provided by The_Korea_Advanced_Institute_of_Science_and_Technology_ (KAIST). Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jeong Seok Lee, June-Young Koh, Kijong Yi, Young-Il Kim, Su-Jin
Park,
Eun-Ha Kim, Se-Mi Kim, Sung Ho Park, Young Seok Ju, Young Ki Choi,
Su- Hyung Park. Single-cell transcriptome of bronchoalveolar lavage
fluid reveals sequential change of macrophages during SARS-CoV-2
infection in ferrets. Nature Communications, 2021; 12 (1) DOI:
10.1038/s41467-021- 24807-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210804123625.htm

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