SARS-CoV-2 Brain Regional Detection, Histopathology, Gene Expression, and Immunomodulatory Changes in Decedents with COVID-19

The study titled “SARS-CoV-2 Brain Regional Detection, Histopathology, Gene Expression, and Immunomodulatory Changes in Decedents with COVID-19” focused on the brains of 42 COVID-19 decedents and 107 non-COVID-19 controls.

It revealed that:

  1. Viral Sequences Detection: RT-PCR screening of 16 brain regions from 20 COVID-19 autopsies found SARS-CoV-2 E gene viral sequences in 7 regions (2.5% of 320 samples), mainly in 4 out of 20 subjects (20%). Additional screening in the olfactory bulb (OB), amygdala (AMY), and entorhinal area detected viral sequences in 8 out of 21 subjects (38%).
  2. Histopathology Observations: Significant histopathology was limited to 2 out of 42 cases (4.8%), one with a large acute cerebral infarct and another with hemorrhagic encephalitis.
  3. Gene Expression Changes: RNA sequencing in OB and AMY revealed over 5000 and 700 differentially expressed genes, respectively, which were unrelated to RT-PCR results. These genes were involved in the immune response, neuronal constituents, and olfactory/taste receptor genes.
  4. Olfactory Impairment and Immune Response: There was a reduction in olfactory marker protein-1, indicating COVID-19-related loss of OB olfactory mucosa afferents. Also, Iba-1-immunoreactive microglia showed reduced area fractions in the cerebellar cortex and AMY, with cytokine arrays revealing generalized downregulation in the AMY and upregulation in blood serum in COVID-19 cases.

The study concluded that while the OB is a major brain portal for SARS-CoV-2, COVID-19 brain changes are likely due to blood-borne immune mediators and trans-synaptic gene expression changes arising from OB deafferentation​​.

Read More: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9278252/

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