Could the activation of FcγRIII/CD16 by anti-spike SARS-CoV-2 antibodies independently determine COVID-19 severity?

A team of scientists from Germany recently investigated whether hyperactivation of immune receptors that recognize the Fc part of an IgG molecule (FcγR) can lead to immunopathologic changes in coronavirus disease 2019 (COVID-19) patients. They have observed that hyperactivation of FcγRIII (CD16) by proinflammatory IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can significantly contribute to COVID-19 related immunopathology. The study is currently available on the bioRxiv* preprint server.

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources

Background

Hyperinflammation is a hallmark of severe COVID-19. In critically ill COVID-19 patients, aggravation of symptoms often correlates with high levels of anti-SARS-CoV-2 IgG antibodies and proinflammatory cytokines, including IL-6 and TNF alpha. During viral infection, activation of FcγRs by circulating soluble antigen-antibody complexes and subsequent release of cytokines is considered as a potent defense mechanism against invading viruses. However, hyperactivation of FcγRs can lead to heightened inflammatory response, which in turn can contribute to immunopathology, as observed in critically ill COVID-19 patients. In this context, studies have shown that N297-dependent modification of glycans such as afucosylation within the constant region of anti-SARS-CoV-2 IgG antibodies can increase their binding to FcγRs, which in turn can trigger hyperinflammatory responses.

In the current study, the scientists have analyzed the correlation between antigen-specific IgG responses and the activation profile of immune receptor FcγRIII (CD16) in hospitalized COVID-19 patients. They have investigated whether hyperactivation of CD16 is associated with COVID-19 severity.

The Fc receptor CD16, which is expressed by natural killer cells, monocyte-derived macrophages, or neutrophils, recognizes circulatory soluble antigen-antibody complexes to mediate antibody-dependent cellular cytotoxicity and antibody-dependent cytokine secretion, which are vital cellular processes to combat invading pathogens.

Study design

To determine the kinetics of anti-SARS-CoV-2 IgG antibodies, serum samples were collected from 41 hospitalized COVID-19 patients. Of all patients, 27 were critically ill with severe pneumonia requiring invasive mechanical ventilation, and 14 were severely ill with pneumonia. The most common comorbidity was hypertension, which was present in 85% of patients.

The serum samples were collected from the patients at different time points within 6 – 25 days after symptom onset and analyzed for anti-spike and anti-nucleocapsid IgG antibodies.

Anti-SARS-CoV-2 antibody kinetics

In most of the patients, anti-SARS-CoV-2 IgG antibodies were detected within 9 – 14 days after symptom onset, which gradually increased over time, reaching a constant level at 18 – 20 days. Specifically, seroconversion for anti-nucleocapsid antibodies occurred earlier than that for anti-spike antibodies. Regarding neutralizing antibodies, peak titers were observed in all patients at 18 – 20 days post symptom onset. Taken together, these observations indicate that there is no significant difference in antibody kinetics between severely ill and critically ill COVID-19 patients.

Activation of CD16

Cell-based reporter system was utilized to examine at which extent anti-SARS-CoV-2 IgG antibodies impact CD16 activation. The findings revealed that both anti-spike and anti-receptor binding domain (RBD) antibodies caused a significantly increased activation of CD16 in critically ill patients compared to severely ill patients. However, no such difference was observed for anti-nucleocapsid antibody-mediated activation of CD16. Overall, in all critically ill patients, a sustained activation of CD16 by spike and RBD-specific antibodies was observed, indicating the involvement of CD16 in determining COVID-19 severity.  

For further evaluation, IgG core fucosylation (the process of adding fucose sugar to the antibody Fc region) of anti-spike and anti-nucleocapsid antibodies were examined in serum samples obtained from critically and severely ill patients. The findings reveal that compared to patients with a low CD16 activation profile, patients with high CD16 activity had significantly lower levels of core fucosylation. However, no difference in fucosylation level was observed between critically and severely ill patients. Overall, these observations indicate that lower fucosylation of anti-spike and anti-nucleocapsid antibodies is associated with enhanced CD16 activation in patients with critical or severe COVID-19.

Soluble immune complexes and COVID-19 severity

The quantification of CD16 activation by IgG-specific soluble immune complexes was carried out by a cell-based reporter assay. The findings revealed significantly higher levels of CD16-reactive soluble immune complexes in critically ill patients compared to that in severely ill patients. To further validate whether soluble immune complexes represent the CD16-reactive component in the serum, a series of experiments were conducted, which collectively revealed that the serum levels of CD-16-reactive immune complexes independently determine COVID-19 severity.

Study significance

The study reveals that activation of CD16 by soluble immune complexes strongly correlates with COVID-19 severity. Based on the study findings, the scientists suggest that saturation of Fc receptors, including CD16 by intravenous administration of immunoglobulins, can be effective in mitigating COVID-19 related immunopathology.

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources

Journal references:

Article Revisions

  • Apr 10 2023 - The preprint preliminary research paper that this article was based upon was accepted for publication in a peer-reviewed Scientific Journal. This article was edited accordingly to include a link to the final peer-reviewed paper, now shown in the sources section.
Dr. Sanchari Sinha Dutta

Written by

Dr. Sanchari Sinha Dutta

Dr. Sanchari Sinha Dutta is a science communicator who believes in spreading the power of science in every corner of the world. She has a Bachelor of Science (B.Sc.) degree and a Master's of Science (M.Sc.) in biology and human physiology. Following her Master's degree, Sanchari went on to study a Ph.D. in human physiology. She has authored more than 10 original research articles, all of which have been published in world renowned international journals.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Dutta, Sanchari Sinha Dutta. (2023, April 10). Could the activation of FcγRIII/CD16 by anti-spike SARS-CoV-2 antibodies independently determine COVID-19 severity?. News-Medical. Retrieved on July 21, 2024 from https://www.news-medical.net/news/20210628/Could-the-activation-of-Fcceb3RIIICD16-by-anti-spike-antibodies-independently-determine-COVID-19-severity.aspx.

  • MLA

    Dutta, Sanchari Sinha Dutta. "Could the activation of FcγRIII/CD16 by anti-spike SARS-CoV-2 antibodies independently determine COVID-19 severity?". News-Medical. 21 July 2024. <https://www.news-medical.net/news/20210628/Could-the-activation-of-Fcceb3RIIICD16-by-anti-spike-antibodies-independently-determine-COVID-19-severity.aspx>.

  • Chicago

    Dutta, Sanchari Sinha Dutta. "Could the activation of FcγRIII/CD16 by anti-spike SARS-CoV-2 antibodies independently determine COVID-19 severity?". News-Medical. https://www.news-medical.net/news/20210628/Could-the-activation-of-Fcceb3RIIICD16-by-anti-spike-antibodies-independently-determine-COVID-19-severity.aspx. (accessed July 21, 2024).

  • Harvard

    Dutta, Sanchari Sinha Dutta. 2023. Could the activation of FcγRIII/CD16 by anti-spike SARS-CoV-2 antibodies independently determine COVID-19 severity?. News-Medical, viewed 21 July 2024, https://www.news-medical.net/news/20210628/Could-the-activation-of-Fcceb3RIIICD16-by-anti-spike-antibodies-independently-determine-COVID-19-severity.aspx.

Comments

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment
Post

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
New study links COVID-19 to lasting neuropsychiatric issues, highlights vaccination benefits