COVID-19 and multisystemic inflammatory syndrome in children: 75% of affected children have the same immune abnormality

Why do some children develop a severe form of inflammation 3 to 4 weeks after infection with SARS-CoV2? Why does this disease resemble Kawasaki disease and toxic shock syndrome?

Published on 26.05.2021

Research Acceleration

Since the discovery of the first cases nearly a year ago, researchers from the International Center for Infectious Disease Research (Lyon 1 University, Inserm, CNRS, ENS Lyon) and clinicians from the Hospices Civils de Lyon, in collaboration with the Immunology-Immunopathology-Immunotherapy (i3) laboratory of the Sorbonne Paris 6 University and the Imagine Research Institute (Necker-Enfants malades AP-HP Hospital, Inserm, Université de Paris) and other French hospitals, have discovered a unique component of immune system activation occurring in 75% of children with this disease.

This work, led by Professor Alexandre Belot, characterizes the particular inflammatory response that these children present and which resembles the immunological reactions encountered in staphylococcal or streptococcal toxic shock. The results of this work are published in the journal Science Immunology.

In April 2020, the first cases of a pediatric multisystemic inflammatory syndrome (PIMS or MIS-C) were reported in Europe. The symptoms (red eyes, high fever, rash, digestive signs) resembled Kawasaki syndrome. However, the severe cardiac involvement was atypical, causing severe hypotension and shock often requiring resuscitation. The severity of the disease and the association with initial hemodynamic shock are also reminiscent of another disease called staphylococcal toxic shock syndrome, which occurs in young women. This condition is associated with periodic tamponade and the production of a toxin by the bacteria that massively activates the immune system.

To understand these similarities with Kawasaki and toxic shock syndromes, French researchers and clinicians conducted a large study on 152 patients, among whom 36 children presented with a pediatric multi-systemic inflammatory syndrome.

Their results reveal an immunological signature present in 75% of the cases that proves to be specific to this new disease. It is a state of major activation of a subgroup of T lymphocytes, an activation very similar to that found in toxic shock, although the immunological signature is different. This activation of the immune system can be measured in less than 24 hours and can lead to a faster diagnosis.

This work thus makes it possible to envisage an early specific treatment for children suffering from severe post-infectious forms of the disease. The researchers now wish to determine the origin of this specific activation.

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