Elevated inflammation persists in immune cells months after mild COVID-
19
Date:
March 15, 2022
Source:
Karolinska Institutet
Summary:
There is a lack of understanding as to why some people suffer from
long- lasting symptoms after COVID-19 infection. A new study now
demonstrates that a certain type of immune cell called macrophages
show altered inflammatory and metabolic expression several months
after mild COVID-19.
FULL STORY ========================================================================== There is a lack of understanding as to why some people suffer from
long-lasting symptoms after COVID-19 infection. A new study from
Karolinska Institutet in Sweden, the Helmholtz Center Munich (HMGU)
and the Technical University of Munich (TUM), both in Germany, now
demonstrates that a certain type of immune cell called macrophages show
altered inflammatory and metabolic expression several months after mild COVID-19. The findings are published in the journal Mucosal Immunology.
==========================================================================
"We can show that the macrophages from people with mild COVID-19 exhibit
an altered inflammatory and metabolic expression for three to five
months post- infection," says Craig Wheelock, docent at the Department of Medical Biochemistry and Biophysics, Karolinska Institutet, and one of
the study's authors. "Even though the majority of these people did not
have any persistent symptoms, their immune system was more sensitive
than that of their healthy counterparts." Long-term symptoms are
relatively common after severe COVID-19 infection but may also affect
some individuals with previous mild disease. More research is needed
to understand the long-term immune aberrations in patients who have
recovered from the acute phase of the infection.
To examine this aspect, the researchers in the current study analysed
blood samples from 68 people with previous mild COVID-19 infection and
a control group of 36 people who had not had COVID-19.
The researchers isolated the macrophages in the laboratory and
stimulated them with spike protein, steroids and lipopolysaccharides
(LPS), a molecule that triggers the immune system. The cells were then
RNA sequenced to measure active genes. The researchers also measured
the presence of eicosanoid signaling molecules, which are a fundamental
feature of inflammation.
"It is not surprising to find a large number of eicosanoid molecules
in people with COVID-19 as the disease causes inflammation, but it was surprising that they were still being produced in high quantities several months after the infection," Craig Wheelock says.
==========================================================================
The study also showed a higher concentration of leukotrienes, which are
a type of pro-inflammatory molecules known for causing asthma.
"It's very striking that the concentration of leukotrienes remains
elevated in macrophages in people who have had mild COVID-19," says
the study's corresponding author Julia Esser-von Bieren, research group
leader at the Helmholtz Center Munich and the Technical University of
Munich. "Leukotrienes are key mediators of asthma, but they're also
involved in the antiviral host defence against influenza. A sustained
increase after SARS-CoV-2 infection could cause a greater sensitivity
to respiratory inflammation, but could also improve antiviral immunity
to SARS-CoV-2 or other viruses." The blood samples were collected on
two occasions, at three to five months after SARS-CoV-2 infection and
after 12 months. At three to five months, around 16 percent reported
persistent mild symptoms while the rest were symptom-free.
At 12 months, none reported persistent symptoms and there was no longer
any difference in inflammatory markers between those with previous
COVID-19 infection and the healthy control group.
The researchers note that the post-COVID diagnosis was not specifically examined in the study and as such more research is needed to determine if
these results can be directly linked to what is also known as long COVID.
"We would like to do a corresponding study in which we involve both
people with severe COVID-19 and people without COVID-19 but who have
another kind of respiratory disease, such as influenza," Esser-von
Bieren says. "We'll then examine if what inflicts COVID-19 patients also inflicts those with, say, seasonal influenza." The study was financed
by the Swedish Heart-Lung Foundation, the German Research Foundation
(DFG) and the Helmholtz Association.
One of the authors has received funding from Allergopharma, PLS Design
and Zeller AG.
========================================================================== Story Source: Materials provided by Karolinska_Institutet. Note: Content
may be edited for style and length.
========================================================================== Journal Reference:
1. Sina Bohnacker, Franziska Hartung, Fiona Henkel, Alessandro
Quaranta,
Johan Kolmert, Alina Priller, Minhaz Ud-Dean, Johanna Giglberger,
Luisa M. Kugler, Lisa Pechtold, Sarah Yazici, Antonie Lechner,
Johanna Erber, Ulrike Protzer, Paul Lingor, Percy Knolle, Adam
M. Chaker, Carsten B.
Schmidt-Weber, Craig E. Wheelock, Julia Esser-von Bieren. Mild
COVID-19 imprints a long-term inflammatory eicosanoid- and chemokine
memory in monocyte-derived macrophages. Mucosal Immunology, 2022;
DOI: 10.1038/ s41385-021-00482-8 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220315095020.htm
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