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Immunoglobulin A as a key immunological molecular signature of post-COVID-19 conditions, 2023, Graziele Fonseca de Sousa et al

Discussion in 'Long Covid research' started by Mij, May 17, 2023.

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  1. Mij

    Mij Senior Member (Voting Rights)

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    Abstract
    COVID-19 has infected humans worldwide, causing millions of deaths or prolonged symptoms in survivors. The transient or persistent symptoms after SARS-CoV-2 infection have been defined as post-COVID-19 conditions (PCC).

    We conducted a study of 151 Brazilian PCC patients to analyze symptoms and immunoglobulin profiles, taking into account gender, vaccination, hospitalization and age. Fatigue and myalgia were the most common symptoms and lack of vaccination, hospitalization, and neuropsychiatric and metabolic comorbidities were relevant for the development of PCC.

    Analysis of serological immunoglobulins showed that IgA was higher in PCC patients, especially in the adult and elderly groups. Also, non-hospitalized and hospitalized PCC patients produced high and similar levels of IgA.

    Our results indicated that the detection of IgA antibodies against SARS-CoV-2 during the course of the disease could be associated with the development of PCC and may be an immunological signature to predict prolonged symptoms in COVID-19 patients.

    https://www.medrxiv.org/content/10.1101/2023.05.11.23289866v1
     
    Mij, May 17, 2023
    #1
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  2. Hutan

    Hutan Moderator Staff Member

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    Brazilian research

    When I read the abstract, I sigh at seeing post-covid conditions being lumped altogether. I don't think that is helpful trying to understand what is going on. And so, I'm not sure that any finding from people with diverse conditions, as here, will be useful. To be fair, this study does try to find subgroups.

    I think we have seen a range of antibody levels in people with Lond Covid, I'm not sure that we have seen a clear picture of something notable happening in overall levels. I don't know what IgA antibodies/immunoblobulins are.

    Here's a googled definition, but we probably need to know more than this:
    The paper suggests that other papers have found increased production of IgA in Post-Covid Condition.

    The sample sounds to be of all of the patients attending a post-Covid clinic who agreed to participate (151/255). Incidence of fatigue was 80%, myalgia 80%. 'Hypoprosexia' (72%) was new to me - 'a difficulty concentrating' - hopefully not a term that catches on due to its potential for confusion.


    Here's the comparison between IgA in controls and the PCC people:

    Screen Shot 2023-05-18 at 11.30.34 am.png
     
    Last edited: May 18, 2023
    Hutan, May 18, 2023
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  3. Hutan

    Hutan Moderator Staff Member

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    Hutan, May 18, 2023
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  4. Hutan

    Hutan Moderator Staff Member

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    Biochemistry, Immunoglobulin A
    This paper gives some background on IgA.

    From Wikipedia:
    That latter sentence then begs the question - how important are levels of IgA in blood? Perhaps what needs to be looked at is levels of IgA in the places where it is mostly found?
     
    Hutan, May 18, 2023
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  5. Jonathan Edwards

    Jonathan Edwards Senior Member (Voting Rights)

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    IgA is puzzling in that very low levels in blood (serum IgA deficiency) are common and don't seem to matter much at least in developed countries. The assumption tends to be that the main function is to protect mucous membrane barriers using the secreted dimer.

    The problem with looking at level in tissue microenvironment, though, is that concentrations will be confounded by all sorts of irrelevant factors - essentially because one is not studying a steady state fluid phase. The density of IgA plasma cells within a certain distance from mucous surface might be more relevant.

    I think measuring blood IgA is fair enough because a difference in levels of the sort reported would indicate at least some sort of change in IgA production or dimerisation (which effects compartmentalisation). To me it seems like an interesting and plausible finding.

    It may be worth remembering that a very significant proportion of our plasma cells and antibody production occurs in gut mucosa. Gut is absolutely stuffed with lymphocytes and plasma cells, unsurprisingly perhaps, since it is our main interface with foreign chemicals. Gut trouble makes people feel ill pretty reliably. So maybe post-Covid symptoms have something to do with prolonged production of unhelpful IgA - or at least some persistent signal that has IgA production in gut as a spin off.
     
    Jonathan Edwards, May 18, 2023
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  6. wastwater

    wastwater Senior Member (Voting Rights)

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    I suspect I may have an IGA deficiency as someone in my rare eye genes group mentioned this as being a cause for under reactive to bacteria In Younger years that’s grown out of and then over reactive after viral illness
    https://www.southtees.nhs.uk/services/pathology/tests/immunoglobulins-igg-iga-igm/
    IgA deficiency is the commonest of the primary disorders. The incidence is 1 in 500 of the population but 30% are symptom free.
     
    Last edited: Jul 29, 2023
    wastwater, Jul 29, 2023
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