Autoimmune attack causes 10% of serious cases of Covid-19

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Two new published studies in one of the world’s leading scientific journals, Science, indicate that at least 1 in 10 people who have developed severe Covid-19 may have been attacked by the immune system itself.

The condition is more frequent among men. The study points out that 12.5% ​​of those who developed acute cases of the new coronavirus had their condition worsened by the defense system itself, compared to 2.6% of women.

Understand study results

Image: Ca-ssis / iStock

According to the researchers, the results help to explain why people with no known comorbidities who contracted Covid-19 died.

In contact with a virus, the body produces substances called type 1 interferon (protein). This protein is responsible for preventing the virus from reproducing in cells and for stimulating other cells to fight the invader. This initial phase of action activates the immune response with the production of antibodies.

The first study analyzed plasma and serum samples from 987 people with aggravated Covid-19, 663 asymptomatic or pre-asymptomatic and 1,127 healthy people (who were part of the control group).

The researchers found that in 10% of cases the patients’ bodies had antibodies that acted against their own type 1 interferons. In other words, the body’s own defense system prevented the body from fighting Sars-CoV-2, resulting in the worsening of the disease, and, in some cases, death.

Carolina Prando, coordinator of the Immune System Genetics Research Group at the Pelé Pequeno Príncipe Research Institute and co-author of the studies, explains that there are two types of type 1 interferons, alpha and beta. Alpha interferon was the most attacked by the immune system of the tested patients.

“The antibody works like an autoimmune disease to block interferon [alfa]. So there’s no point in giving interferon [alfa] for patients. There are treatments for other diseases, for example, which are made with interferon beta. It is necessary to conduct clinical trials to find out whether supplementing beta interferon can benefit the treatment of Covid-19, ”he said.

With the new discovery it is possible to predict which patients are most at risk of dying

severe cases of Covid-19 autoimmune attack
Image: RyanKing999 / iStock

The findings may also aid research on treatment with convalescent plasma, a process in which antibodies obtained from the plasma of those who have had the disease and recovered are applied to a patient.

They can also curb the introduction of antibodies in patients who are part of the 10% affected by the autoimmune attack, as this would make the disease worse instead of improving, because the antibodies would fight the body itself and not the virus.

The conclusions are complemented by another published study, according to which 3.5% of patients with a severe clinical picture of Covid-19 had genetic mutations that prevent the body from producing antibodies against the virus. In that study, the genetic material of 659 people in severe disease was analyzed.

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Prando stresses that only new clinical trials will reveal whether the mutation makes these patients susceptible to severe reinfection.

“We cannot rule out that possibility. Interferon is necessary for antibodies to occur. Because this is a genetic mutation, it can be hereditary and, therefore, it is important to investigate whether other relatives of a seriously ill patient are at greater risk. ”

In such cases, she says, it would be possible to stimulate the immune system with the administration of type 1 interferon, similarly to what occurs in the treatment of hepatitis.

With the publication of the studies, the group is preparing to start clinical trials that will check possible therapeutic interventions to circumvent the published results.

Both studies were carried out by COVID Human Genetic Effort, a collaborative project between more than 50 genetic sequencing centers and hundreds of hospitals around the world.

Prando and another Brazilian, researcher Antonio Condino Neto, from the University of São Paulo (USP), are on the project’s board.

MATHEUS MEDEIROS || FOLHAPRESS

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