Overreaction of the immune system: scientists decipher how the coronavirus kills people



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The coronavirus kills mainly through an overreaction of the immune system, the function of which is precisely to fight infections, say scientists who have deciphered the mechanisms, symptoms and diagnosis of the disease caused by the SARS-Cov-2 coronavirus.

In a study published in the journal Frontiers in Public Health, researchers explained step by step how the virus infects the airways, multiplies within cells, and, in severe cases, overwhelms immune defenses with a “storm of cytokines. “

This storm is an over-activation of white blood cells, which release too large amounts of cytokines, molecules that stimulate inflammation, into the blood, they said.

“Similar to what happens after infection with SARS and MERS, the data shows that patients with severe COVID-19 may have cytokine storm syndrome,” said study author Daishun Liu, a professor at the University of Medicine. Zunyi in China.

“The rapid increase in cytokines attracts an excess of immune cells, such as lymphocytes and neutrophils, resulting in an infiltration of these cells into the lung tissue and therefore causing lung damage,” Liu said.

The researchers explained that the cytokine storm eventually causes high fever, excessive leakage of blood vessels, and clotting of blood within the body.

It also causes extremely low blood pressure, lack of oxygen and excess acidity of the blood, and accumulation of fluids in the lungs, they said.

The researchers noted that white blood cells are misdirected to attack and inflame even healthy tissue, leading to failure of the lungs, heart, liver, intestines, kidneys, and genitalia.

This multiple organ dysfunction syndrome (MODS) can worsen and shut down the lungs, a condition called acute respiratory distress syndrome (ARDS), they said.

This, the researchers explained, occurs due to the formation of the so-called hyaline membrane, made up of protein debris and dead cells, which line the lungs, making oxygen absorption difficult.

The majority of COVID-19 deaths are due to respiratory failure, they said.

The researchers explained that, in the absence of a specific antiviral cure for COVID-19, the goal of treatment should be to combat symptoms and reduce the death rate by intensively maintaining organ function.

For example, an artificial liver blood purification system or kidney replacement therapy can be used to filter blood by mechanical means, they said.

The team noted that methods to supplement or replace lung function are especially important, for example with non-invasive mechanical ventilation through a mask, ventilation through a tube in the trachea, the administration of heated and humidified oxygen through a tube in the nose, or a heart-lung bypass.

The researchers stressed the importance of preventing secondary infections.

They noted that SARS-Cov-2 also invades the intestines, where it causes inflammation and leaks in the intestinal lining, allowing opportunistic entry of other disease-causing microorganisms.

The researchers argue that this should be avoided with nutritional support, for example with probiotics, beneficial bacteria that protect against the establishment of harmful ones, and nutrients and amino acids to improve immune defenses and bowel function.

“Because treatment for now is based on aggressive treatment of symptoms, preventive protection against secondary infections, such as bacteria and fungi, is particularly important in supporting organ function, especially in the heart, kidneys, and liver, to try to prevent further deterioration of their condition, “Liu added.

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