Which patient will develop a severe form of Covid-19? This is an essential question to which Inserm teams and researchers from an international consortium will perhaps bring an answer. From the start of the Covid-19 pandemic, researcher Jean-Laurent Casanova and his team set up a consortium called COVID human genetic effort, in order to identify the genetic and immunological factors that may explain the occurrence of severe forms of the disease.
They have in fact discovered that this worsening of the disease is caused by a sharp increase in cytokines. This runaway inflammatory response is correlated with a massive infiltration into the lungs of innate immune cells, namely neutrophils and monocytes, creating lung damage and acute respiratory distress syndrome..
An explanation for 15% of severe forms
By targeting their research on type I interferons (IFNs), which are powerful antiviral molecules, the researchers first identified genetic abnormalities in certain patients that decrease the production of type I IFNs (which represents 3 to 4% of severe forms). In other patients, they have identified autoimmune diseases that block the action of type I IFNs (which represents 10 to 11% of severe forms). All of these discoveries would therefore explain 15% of severe forms of Covid-19.
“Consequently, type I IFN deficiency could be a signature of serious forms of Covid-19 and could make it possible to identify a high-risk population” underlines Inserm. These results further suggest that “learly intake of type 1 IFN in these patients could be a therapeutic avenue. These drugs have been available for over 30 years and without noticeable side effects if taken for a short time.
“Whether it is genetic variants which decrease the production of type I IFN during infection or antibodies which neutralize them, these deficits precede infection by the virus and explain the serious disease. These two publications therefore highlight the crucial role of type I IFNs in the immune response against SARS-CoV2 “, conclude the Inserm researchers. Their two studies have been published in the journal Science.
An immune signature in diabetic patients
As an extension of these studies, another Inserm team, directed by Nicolas Venteclef at the Cordeliers Research Center, conducted research at the “University Center for Diabetes and its Complications” directed by Jean-François Gautier, diabetologist researcher at the Lariboisière AP-HP hospital (Paris). “ The aim was to better understand the link between pre-existing inflammation in diabetes and the risk of developing a severe form of Covid-19 ” they emphasize.
They were therefore interested in the immune response of 45 patients with Covid-19 and hospitalized, of which 30 had type 2 diabetes. Among the participants in this study, 35% of diabetic patients developed a severe form of the disease. requiring intensive care, compared to 25% of non-diabetic hospitalized patients. Their work, published in the journal EMBO Molecular Medicine, suggest that there is an immune and inflammatory signature specific to diabetic patients at risk for severe form of Covid-19. This discovery offers physicians the opportunity to identify patients who will need further follow-up and potentially a place in intensive care.
What is a severe form of Covid?
Patients with Covid-19 who progress to a severe or critical form, in particular develop severe pneumonia transforming into acute respiratory distress syndrome. Although these forms sometimes occur at the onset of the disease, clinical observations generally describe a progression of the disease in two stages, starting with a mild to moderate form, followed by worsening of the respiratory system 9 to 12 days after the onset of the first. symptoms.
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