Early NK cell-mediated immune response may contribute to severe COVID-19


Date:
August 21, 2020
Source:
Karolinska Institutet
Summary:
Researchers may have come one step closer toward understanding how
the immune system contributes to severe COVID-19. In a new study,
researchers show that so-called natural killer (NK) cells were
strongly activated early after SARS-CoV-2 infection but that
the type of activation differed in patients with moderate and
severe COVID-19. The discovery contributes to our understanding
of development of hyperinflammation in some patients.



FULL STORY ========================================================================== Researchers may have come one step closer toward understanding how the
immune system contributes to severe COVID-19. In a study published in
Science Immunology, researchers at Karolinska Institutet in Sweden show
that so-called natural killer (NK) cells were strongly activated early
after SARS-CoV- 2 infection but that the type of activation differed in patients with moderate and severe COVID-19. The discovery contributes
to our understanding of development of hyperinflammation in some patients.


========================================================================== SARS-CoV-2 infection can in some cases cause severe COVID-19
disease. Although this is thought to be partially driven by a misdirected innate immune response, many aspects of the early immune response to
the infection remain elusive.

Researchers at Karolinska Institutet have now, in collaboration with
colleagues at the Karolinska University Hospital, investigated the early response to SARS- CoV-2 infection of NK cells, a cell type in the immune
system known to be important in the control of viral infections.

The study analyzed blood samples from 27 patients with moderate (10)
and severe (17) COVID-19 infection. The researchers also included blood
samples from 17 healthy individuals as a control group. The result
showed that NK cells were strongly activated in the blood shortly after infection.

"The type of NK cell activation detected differed considerably in patients
with moderate compared to severe disease," says Niklas Bjo"rkstro"m,
physician and immunology researcher at the Center for Infectious
Medicine, Department of Medicine Huddinge, at Karolinska Institutet,
who led the study.

It is likely that the type of NK cell response observed in SARS-CoV-2
infected patients with moderate disease is a canonical NK cell
response shared between many types of viral infections, according to
the researchers.

However, patients who developed severe COVID-19 had a different
composition of responding NK cells. These patients' NK cells generally
had higher expression of the proteins perforin, NKG2C and Ksp37, which according to the researchers reflect a high presence of so-called adaptive
NK cells. Adaptive NK cells have an even greater ability to kill target
cells compared to other NK cells.

The researchers are now investigating to what extent the NK cell-mediated immune response observed in the critically ill patients might contribute
to COVID-19 severity, and the extent to which other parts of the response
may be beneficial.

"Taken together, our findings provide additional insights into immune
reactions in early SARS-CoV-2 infection and ensuing COVID-19 disease,"
Niklas Bjo"rkstro"m says. "We hope that these insights will contribute to
the improved care and treatment of patients with severe COVID-19 disease."
The study is part of the larger Karolinska COVID-19 Immune Atlas project,
which aims to increase knowledge about the characteristics of immune
cells in patients with COVID-19.

This work was supported by the Knut and Alice Wallenberg Foundation, Nordstjernan AB, the Swedish Research Council, the Swedish Cancer
Society, the Swedish Foundation for Strategic Research, the Center
for Innovative Medicine at Karolinska Institutet, Region Stockholm,
SRP Diabetes Karolinska Institutet, StratRegen Karolinska Institutet,
and Karolinska Institutet.


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


========================================================================== Journal Reference:
1. Christopher Maucourant, Iva Filipovic, Andrea Ponzetta, Soo Aleman,
Martin Cornillet, Laura Hertwig, Benedikt Strunz, Antonio
Lentini, Bjo"rn Reinius, Demi Brownlie, Angelica Cuapio Gomez,
Eivind Heggernes Ask, Ryan M. Hull, Alvaro Haroun-Izquierdo,
Marie Schaffer, Jonas Klingstro"m, Elin Folkesson, Marcus
Buggert, Johan K. Sandberg, Lars I. Eriksson, Olav Rooyackers,
Hans-Gustaf Ljunggren, Karl-Johan Malmberg, Jakob Michae"lsson,
Nicole Marquardt, Quirin Hammer, Kristoffer Straalin, Niklas
K. Bjo"rkstro"m, Karolinska COVID-19 Study Group. Natural killer
cell immunotypes related to COVID-19 disease severity. Science
Immunology, 2020; 5 (50): eabd6832 DOI: 10.1126/sciimmunol.abd6832 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200821155742.htm

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