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Persistent post–COVID-19 smell loss is associated with immune cell infiltration and altered gene expression in olfactory epithelium, 2022, Finlay JB

Discussion in 'Long Covid research' started by Sarah, Dec 22, 2022.

  1. Sarah

    Sarah Senior Member (Voting Rights)


    SARS-CoV-2 causes profound changes in the sense of smell, including total smell loss. Although these alterations are often transient, many patients with COVID-19 exhibit olfactory dysfunction that lasts months to years. Although animal and human autopsy studies have suggested mechanisms driving acute anosmia, it remains unclear how SARS-CoV-2 causes persistent smell loss in a subset of patients. To address this question, we analyzed olfactory epithelial samples collected from 24 biopsies, including from nine patients with objectively quantified long-term smell loss after COVID-19. This biopsy-based approach revealed a diffuse infiltrate of T cells expressing interferon-γ and a shift in myeloid cell population composition, including enrichment of CD207+ dendritic cells and depletion of anti-inflammatory M2 macrophages. Despite the absence of detectable SARS-CoV-2 RNA or protein, gene expression in the barrier supporting cells of the olfactory epithelium, termed sustentacular cells, appeared to reflect a response to ongoing inflammatory signaling, which was accompanied by a reduction in the number of olfactory sensory neurons relative to olfactory epithelial sustentacular cells. These findings indicate that T cell–mediated inflammation persists in the olfactory epithelium long after SARS-CoV-2 has been eliminated from the tissue, suggesting a mechanism for long-term post–COVID-19 smell loss.

    Finlay JB et al.
    Science Translational Medicine 21 Dec 2022 Vol 14, Issue 676 DOI: 10.1126/scitranslmed.add0484
    Lilas, boolybooly, Hutan and 4 others like this.
  2. Sarah

    Sarah Senior Member (Voting Rights)

  3. rvallee

    rvallee Senior Member (Voting Rights)

    It's almost like immunity has a cost. It's a battle, technically. There are resources, soldiers, casualties. It works, but it's not free. Medicine seems convinced that it works for free, that an immune battle won quickly is the same thing as there having been no battle at all. Doesn't deplete anything. Damage done is either not happening or repaired immediately. It's ready to go for it again and again and again, without end.

    Lots of that problematic thinking going around. Like the idea that thinking is a free lunch, doesn't require energy or is special and separate from all other forms of energy biology uses. Somehow emotions separated from intellectual thinking because they've always been separated, somehow. So is the idea that everything is harmless unless there is massive evidence of harm, as if pathogens living in the body have zero effect on it, do not consume anything, do not lead to an immune response that keep things in check. The belief that once pathogens establish themselves, they just live a cozy life in harmony with the body, I guess.

    That's been the premise to sell herd immunity: it's free, no harm done. You're sick for a few days and that's it. Doesn't leave a mark, can't even. It takes the idea of immunity and presents it as invincibility, unlimited, infinite. Economics don't care about feelings. There is no such thing as a free lunch. Sooner or later you run out of soldiers, resources, or access to the battlefield, or all of those.
  4. belbyr

    belbyr Established Member (Voting Rights)

    Last edited by a moderator: Dec 23, 2022

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