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They identify what causes Covid-19 to be more serious in some patients

06/25/2021

On at 15:07 CEST

Since COVID-19 emerged more than a year and a half ago, the scientific and medical community has confirmed that the coronavirus infection SARS-CoV-2 It causes different presentations of the disease, with groups of patients progressing to a critical form that requires admission to the ICU and invasive mechanical ventilation.

Since the beginning of the pandemic, one of the main lines of study has been to try to predict which patients might be more susceptible to developing a critical form of COVID-19, an objective for which it is essential to define the most suitable biomarkers.

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Today it is known that SARS-CoV-2 can partially evade the immune response in some patients, which could be related to the severity of the disease, and that the so-called cellular adaptive immune response is important to fight infection.

A team of researchers from National Center for Microbiology (CNM) of the ISCIII has led an investigation that has analyzed different immunological indicators that may be useful in predicting the severity of COVID-19.

The results of this work, which have been published in the journal Frontiers in Immunology, point out that the fight against SARS-CoV-2 infection should not only focus on reducing disproportionate inflammatory responses, which reduce the efficiency of the immune response, but also on provoking an effective cytotoxic response against infected cells that allows reducing the viral replication of the virus.

In this study, the team at Carlos III Health Institute has analyzed various parameters related to the cellular immune response to the virus in blood samples from 109 patients with different presentations of COVID-19.

These patients were recruited from hospitals and primary care centers in Madrid during the first wave of the pandemic, between April and June 2020.

The analyzes show that hospitalized patients with the most severe forms of COVID-19 showed a potent inflammatory response that did not translate into an efficient immune response.

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The CNM researchers explain that, despite having high levels of cytotoxic immune cells capable of fighting the virus, such as T cells, Natural Killer cells and CD8 + lymphocytes, these patients who developed very serious disease showed “markers of immune depletion and a deficient cytotoxic functionality against target cells infected with SARS-CoV-2 ‘.

In other words, the weapons of the immune system were not working properly.

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This status hyperinflammatory of patients, accompanied by a scant cytotoxic response of your immune cells, seems to be associated with the presence of potential poor prognostic biomarkers in the course of the disease.

Specifically, these biomarkers detected in the most serious patients would be the following:

Low levels of CD8 T lymphocytes & pm; with gamma-delta receptor Very low CD4 + T lymphocyte count Increased levels of regulatory T cells (Tregs) Reduced plasma levels of interleukin 2 (IL-2) Reduced differentiation capacity of Th1 lymphocytes.

After defining and analyzing this ‘map’ of common biomarkers related to more severe forms of COVID-19, the researchers concluded that the immune response in these patients was characterized by an inefficient cytotoxic response in the fight against the virus.

The researchers Mayte Coiras, Lorena Vigón and María Rosa López-Huertas are the main signatories of the work, in which they also participate Montserrat Torres, Sara Rodríguez-Mora, Elena Mateos, Javier García-Pérez and José Alcamí, all of them from the AIDS Immunopathology Unit of the CNM-ISCIII.

Teams from the Ramón y Cajal, Puerta de Hierro, Severo Ochoa and El Escorial hospitals in Madrid also participated in the study, together with doctors from the Pedro Laín Entralgo Health Center in Alcorcón, researchers from the Polytechnic University of Madrid and scientists from the University of Utah, in United States.

The study of these severity biomarkers can facilitate the understanding of the immune response associated with more or less severe forms of COVID-19, and thus open new avenues in the search for drugs capable of controlling the infection.

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