COVID-19 vaccination: long-term activation of immune cells
SARS-CoV-2 mRNA vaccines play a key role in the fight against the ongoing COVID-19 pandemic. Vaccination stimulates cells of the innate immune system, but the duration of this effect was not known until now. Researchers have now gained new insights into this.
When the human immune system comes into contact with the SARS-CoV-2 coronavirus, it defends itself and forms antibodies. A similar immune response is triggered by COVID-19 vaccines. So far, however, little data is available on the durability of immune protection. But now there are new findings on this: the results of a study on the activation of immune cells after vaccination with SARS-CoV-2 mRNA were recently published in the journal "EMBO Molecular Medicine" .
Good protection against steep slopes
In some people, infection with SARS-CoV-2 leads to severe inflammation of the lungs and other vital organs. The corona vaccination offers very good protection against these serious diseases.
According to a statement from the University Hospital of Cologne, numerous studies have looked into the role of the so-called acquired immune response after vaccination and have been able to show that, for example, antibodies can be measured in the blood after vaccination. vaccination, then decrease over time. month.
In order to trigger a powerful immune response, however, vaccinations first require the activation of the innate immune system, which reacts non-specifically to foreign proteins from viruses or bacteria. It was previously unknown how accurately and for how long new mRNA vaccines stimulate cells of the innate immune system.
In the just published vaccination study, researchers at Cologne University Hospital and the Faculty of Medicine are for the first time looking at the signaling pathways of these defense cells and their impact on the acquired immune response.
Important for long lasting and powerful effects
The rapid development of potent vaccines against the SARS-CoV-2 coronavirus has been instrumental in containing the pandemic. Many studies show protection against severe courses of COVID-19 and reduction in infections with full vaccination.
In particular, potent mRNA vaccines that could be made available quickly were an important step in this development. In the meantime, researchers have been able to study the duration of vaccine protection via activation of the acquired immune system relatively well.
In order for a vaccination to have the longest and strongest possible effect, it is important to activate the innate immune system, which triggers the interaction of various defense cells and leaves a memory function in the immune system.
Most conventional vaccines use so-called adjuvants, additives intended to stimulate cells of the innate immune system such as macrophages. mRNA vaccines lack these classic additives, and the mechanism by which immune cells are stimulated directly after vaccination is not yet known.
The effects observed after the second vaccination are particularly strong
Here the research of the Priv. Dr. doctor Jan Rybniker. "We were able to show that mRNA vaccination very specifically stimulates macrophages circulating in the blood via a very specific signaling pathway", explains the scientist.
"It is only when these macrophages come into contact with the spike protein of SARS-CoV-2 that the pre-activation of the cells allows the release of pro-inflammatory messenger substances and therefore the activation of the defense cells of the system. acquired immune."
According to the information, this pre-activation of blood cells also represents a kind of cell protection device, in which inflammation occurs only in the tissue that produces the spike protein and not for a long time throughout the body.
According to Rybniker, head of the Infectiology Research Laboratory at Cologne University Hospital and last author of the publication, this inflammatory reaction is more likely to occur locally in the lymph nodes, into which these blood cells can migrate.
The highly specific reaction to the spike protein observed in the present study is unusual for defense cells of the innate immune system. Accordingly, spike protein-binding receptors on the surface of macrophages are responsible. After vaccination, these receptors activate the central control protein SYK, which activates many pro-inflammatory processes in immune cells.
Interestingly, the observed effects were only particularly pronounced after the second vaccination. But even the third vaccination (booster) was able to reactivate the macrophages months after the primary vaccination. However, the macrophages present in the blood have a very short lifespan of only a few days.
“Apparently, primary immunization also leads to memory function in these short-lived cells. This important finding is new to mRNA vaccination. The underlying mechanism could also contribute to the strong protective effect we obtain with the vaccine. recall,” says Dr. Sebastian Theobald, post-doctoral fellow at Cologne University Hospital and first author of the study.
The results can also be used for future vaccinations
The SYK signaling pathway described in the work and the upstream receptor molecules have long been considered as a possible and attractive mechanism with which cells of the innate immune system could be stimulated in the context of vaccinations. This theory can now be confirmed for mRNA vaccination, which has a very good safety profile.
The results can now be used to specifically activate similar immunity-boosting mechanisms in future vaccinations, for example via appropriate adjuvants.
“Therapies and vaccinations based on mRNA are on the rise. It is all the more important now to decode as much information as possible about the immune responses triggered by these drugs in order to fully exploit their potential,” explains Dr. Rybnik.
Possible therapeutic approach
The SYK signaling pathway also appears to play a role in severe COVID-19 disease. In an earlier study, the group was able to demonstrate similar influences on the blood cells of COVID-19 patients.
Therefore, SYK is also considered as a possible therapeutic starting point for immunomodulatory treatments in severe COVID-19 infections. Clinical studies are already underway with corresponding drugs. (ad)
Author and source informationShow now
This text corresponds to the specifications of the specialized medical literature, medical guidelines and current studies and has been verified by health professionals.
Sources:University Hospital Cologne: Vaccination against COVID-19 activates the innate immune system in the long term - signaling pathway decoded, (accessed: July 5, 2022), University Hospital Cologne Sebastian J Theobald, Alexander Simonis, Julie M Mudler, Ulrike Göbel, Richard Acton, Viktoria Kohlhas, Marie-Christine Albert, Anna-Maria Hellmann, Jakob J Malin, Sandra Winter, Michael Hallek, Henning Walczak, Phuong-Hien Nguyen, Manuel Koch, Jan Rybniker: mRNA vaccination of CoV- 2; in: EMBO Molecular Medicine, (published on: 07/04/2022), EMBO Molecular Medicine
This article contains general advice only and should not be used for self-diagnosis or treatment. It cannot substitute a visit to the doctor.