• Cytokine storms play a limited role in moderate-to-severe #COVID-19 | EurekAlert! Science News
    https://www.eurekalert.org/pub_releases/2020-11/sjcr-csp111320.php

    “The lack of hyperinflammation in most COVID-19 patients does not mean they had less disease,” said co-first author Jeremy Chase Crawford, Ph.D., of St. Jude Immunology. “We are saying that in most cases the disease was not caused by broad hyperinflammation from cytokine storm, which has important implications for developing generalizable COVID-19 therapeutics.”

    The analysis revealed that the antiviral immune response was profoundly suppressed in COVID-19 patients compared to flu patients. Along with measuring cytokines, researchers analyzed cytokine transcription in individual blood cells in patients with flu, COVID-19 and healthy volunteers. COVID-19 was associated with significantly reduced production of and response to Type I and Type II interferons, cytokines that play a central role in the antiviral immune response.

    Researchers also found evidence that SARS-CoV-2 alters pathways controlling the immune response to promote steroid production by patients. “Our results suggest that most COVID-19 patients are perhaps already producing high levels of glucocorticoids prior to treatment, possibly leading to the blunted immunity we see in most of them,” Thomas said. “These patients may need therapy to turn up their immune response to knock the virus down.”

  • Antibody evolution may predict #COVID-19 outcomes | EurekAlert ! Science News
    https://www.eurekalert.org/pub_releases/2020-11/mgh-aem111320.php

    For COVID-19, the difference between surviving and not surviving severe disease may be due to the quality, not the quantity, of the patients’ antibody development and response, suggests a new Cell paper published by Galit Alter, PhD, a member of the Ragon Institute of MGH, MIT and Harvard.

    [...]

    Compared to survivors, patients who passed from COVID-19 had antibodies that never fully developed the ability to strongly bind to Fc-receptors and therefore may not have been able to fully trigger immune killing activity.

    Alter’s group, led by Tomer Zohar, Carolin Loos, Stephanie Fischinger, and Caroline Atyeo, PhD, also found that survivors’ immune systems could recognize and target an area of the SARS-CoV-2 spike protein known as the S2-domain. The S2 domain is found in other coronaviruses that infect humans, so patients whose antibodies can target it may have pre-existing immunity to the S2 domain because of exposure to other, common coronaviruses.

    Patients with antibodies that can recognize S2 domains on different coronaviruses may be able to use this pre-existing immunity to generate killer antibodies faster and sooner following SARS-CoV-2 infection.

    “If we can further understand the importance of cross-coronavirus immunity,” says Zohar, “researchers may be able to design vaccines able to counteract a much broader range of coronaviruses.”

    #immunité #immunité_croisée