The immune defense itself opens the "doors" to the coronavirus
Last reviewed: 04.09.2021
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It turns out that the immune protein contributes to the formation of many molecular "doors" in the cells of the mucous tissue for the entry of the coronavirus.
The coronavirus pathogen SARS-CoV-2 enters the cell using its own protein component S: it covers the fatty layer of the coronavirus. This protein interacts with the ACE2 receptor, a component of many cellular structures in the human body known as angiotensin-converting enzyme. One of the functional areas of this receptor is blood pressure management. However, the coronavirus was able to benefit from it: after the formation of a bond between the viral S-protein and ACE2, the cell membrane is deformed, and the virus has the opportunity to dive into it. Of course, other protein components of the coronavirus, which are located in its surface layer together with the S-protein, also contribute their "contribution". However, the leading role belongs to the above S-protein and the ACE2 receptor.
It turns out that the coronavirus pathogen will more easily penetrate those cells on which a greater number of ACE2 enzyme receptors are present. Scientists representing the Max Delbrück Center for Molecular Medicine, as well as the Charite Clinical Center, the Free University of Berlin and other scientific centers, noticed that the appearance of more protein components of ACE2 on the cell surface is due to the increased activity of the immune defense. When the virus enters the body, immunity cells begin to produce γ-interferon. This is the main signaling protein that activates macrophages and accelerates the release of toxins.
It was found that under the influence of γ-interferon, the cells of the mucous tissue produce a greater number of enzyme receptors. Thus, thanks to the immune protein, the virus can easily penetrate into the cells. Scientists have conducted a series of studies with an intestinal organoid - that is, an intestinal microscopic copy formed by stem cells folded into a three-dimensional structure. The intestine was chosen as one of the organs that is affected by the oronavirus infection along with the respiratory system.
When γ-interferon was added to the intestinal organoid, the gene encoding the receptor enzyme was stimulated inside the cells of the mucous tissue, which, in turn, became larger. When a coronavirus pathogen was added to the organoid, more coronavirus RNA was detected inside the cells after ingestion of γ-interferon.
Scientists admit that the severe and prolonged course of COVID-19 may be associated with the activity of γ-interferon. However, so far this is just an assumption that requires detailed clinical studies - in particular, on the real intestine inside the body. If the specialists' guesses are confirmed, then the next step will be to develop a method to prevent interferon "support" from immune protection.
The information is published in the open access on the pages of the scientific journal EMBO Molecular Medicine .