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Memento Covid-19 : A quick review before the start of the school year

Since the discovery of SARS-CoV-2 in China on January 9, 2020, we have been inundated with more or less verified information on the pandemic. It is useful to take stock of the scientific knowledge on the subject, with Jean-Marc Sabatier*.

The binding of the coronavirus SARS-CoV-2 (or spike protein) to its cellular receptor ACE2 (angiotensin converting enzyme 2) interferes with the degradation of angiotensin 2 by ACE2 which, in excess, induces the over-activation of the cellular receptor AT1R. The over-activation of the RAS has very deleterious effects on the organism, leading in particular to the development of COVID-19 diseases. The AT1R receptor has vasoconstrictor (hypertensive), pro-inflammatory (cytokine storm), pro-thrombotic, pro-fibrosing, pro-oxidative (causes oxidative stress), pro-angiogenic, hypertrophying organs (heart, lungs, etc.), inhibiting the production of nitric oxide (NO) affecting the immune and nervous systems... The over-activated AT1R receptor (= RAS dysfunction) is thus the real culprit in Covid-19 diseases.
The binding of the coronavirus SARS-CoV-2 (or spike protein) to its cellular receptor ACE2 (angiotensin converting enzyme 2) interferes with the degradation of angiotensin 2 by ACE2 which, in excess, induces the over-activation of the cellular receptor AT1R. The over-activation of the RAS has very deleterious effects on the organism, leading in particular to the development of COVID-19 diseases.
The AT1R receptor has vasoconstrictor (hypertensive), pro-inflammatory (cytokine storm), pro-thrombotic, pro-fibrosing, pro-oxidative (causes oxidative stress), pro-angiogenic, hypertrophying organs (heart, lungs, etc.), inhibiting the production of nitric oxide (NO) affecting the immune and nervous systems…
The over-activated AT1R receptor (= RAS dysfunction) is thus the real culprit in Covid-19 diseases.

 

Vaccinated and infected

Essential barrier measures

Glossary

SARS-CoV-2

During viral infection, SARS-CoV-2 over-activates the renin-angiotensin system (RAS) by binding to the ACE2 receptor, which has an angiotensin 2 degradation function. The binding of SARS-CoV-2 to the ACE2 receptor thus prevents the normal degradation of angiotensin 2, the excess of which leads to an over-activation of its cellular receptor AT1R. The overactivated AT1R receptor is very deleterious to the human body (induction of cytokine storm, vasoconstriction, inflammation, fibrosis, oxidative stress, angiogenesis, tissue hypertrophy, fall in nitric oxide NO related to immunity and memory processes, etc.) and seems to be at the origin of the progression to the severe, sometimes fatal, forms of Covid-19. This deleterious effect of AT1R on the human body results in the development of various pathologies similar to those described for SARS-CoV-2 infection. The genes coding for ACE2 and AT1R are located on chromosomes X and 3, respectively.

The renin-angiotensin system (RAS)

The RAS is a major hormonal/physiological system in mammals, present in the lungs, kidneys, intestines, heart, brain, spleen, pancreas, testes, blood vessels, as well as on “innate” immunity cells (circulating monocytes, macrophages, dendritic/antigen-presenting cells, natural killer (NK) cells, etc.). The RAS controls renal, pulmonary and cardiovascular functions, as well as “innate” immunity (which is the “immediate” non-specific immune response to pathogens) and the gut microbiota.
The gene encoding the AT1R receptor (of the RAS), which is highly deleterious to the human body when overactivated, is located on chromosome 3. It is notable that chromosome 3 contains a neanderthal haplotype (a set of “genetically linked” genes located on the same chromosome and transmitted together to the next generation) associated with severe forms of Covid-19. This haplotype is found at 16% in Europe, 65% in South Asia, and is almost non-existent in East Asia and Africa).

Vitamin D is a seco-steroid pro-hormone that acts on at least 291 genes, hence its involvement in many physiological processes: bone mineralization and calcification, innate (circulating monocytes, macrophages, dendritic/antigen-presenting cells, Natural Killer (NK) cells, etc.) and adaptive/acquired (B and T lymphocytes) immunity, proliferation and differentiation of certain cell types (including immune system cells), maintenance of physical barriers (effect on the immune system), and the development of the immune system. ) and adaptive/acquired immunity (B and T lymphocytes), proliferation and differentiation of certain cell types (including immune system cells), maintenance of physical barriers (effect on intercellular junctions), and regulation of RAS. In particular, vitamin D prevents/mitigates the cytokine storm that is very harmful to the human body (excessive release of pro-inflammatory cytokines TNF-alpha, interleukin-6, interleukin-1-beta, interferon-gamma, etc.), which is at the origin of the evolution towards the severe forms of Covid-19. At the same time, vitamin D enhances the production of anti-inflammatory cytokines via adaptive/acquired immunity to inhibit acute systemic hyperinflammation.

Another action of vitamin D on immunity is to directly induce the production of anti-microbial molecules active on viruses (cathelicidin and defensins).

Thus, vitamin D allows the optimal functioning of the immune system necessary for effective vaccination, and induces the production of molecules with antiviral properties allowing the host to prevent or treat possible infection with SARS-CoV-2 and its variants.

Self molecules

These are molecules belonging to the host and which the immune system should not attack.

Non-self” molecules

These are molecules that are “foreign” to the host, generally from pathogens, and which the immune system must attack.)

Vaccine “spike” protein

This is actually the (modified) spike of SARS-CoV-2; it is a trimer of the modified S protein, from which the fusogenic domain allowing the penetration of the virus into cells has been removed.

Les chiffres clés au 18 août 2021
Key figures as of August 18, 2021

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jean-Marc Sabatier (DR)
Jean-Marc Sabatier (DR)

 

*Jean-Marc Sabatier, Director of Research at the CNRS and Doctor in Cell Biology and Microbiology, affiliated with the Institute of NeuroPhysiopathology (INP), at the University of Aix-Marseille. Editor-in-Chief of the international scientific journals: “Coronaviruses” and “Infectious Disorders – Drug Targets”.

 

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