188 COVID Autopsies is a summary of all the autopsy findings that have been done on covid patients. This is based on 8 published studies and/or case reports. Here are the links to those studies:
https://www.acpjournals.org/doi/10.7326/M20-2003
https://www.acpjournals.org/doi/10.7326/M20-2566
https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30243-5/fulltext
https://www.nejm.org/doi/full/10.1056/NEJMoa2015432
https://www.medrxiv.org/content/10.1101/2020.05.18.20099960v1
https://www.nejm.org/doi/full/10.1056/NEJMc2019373
https://jamanetwork.com/journals/jamacardiology/fullarticle/2768914
https://www.thelancet.com/journals/lancet/article/PIIS2213-2600(20)30076-X/fulltext
SARS-CoV-2 exhibits selectivity for the lungs. Specifically, type II pneumocytes, meaning type II alveolar cells. Alveoli are the tiny microscopic air sacs of the lungs, which is the part of our lungs that is responsible for gas exchange. Air is brought down into the lungs to the alveoli, and the oxygen diffuses from the alveoli into our tiny blood vessels there, called capillaries.
At the same time, carbon dioxide, a waste product from our body, travels from the capillaries into our alveoli, and we then exhale out that carbon dioxide. Alveoli are made up of mainly type I alveolar cells. But to a lesser degree, they are also made up of type II alveolar cells, which are like the maintenance guys for the alveoli. They play a part in making surfactant, a sort of lubricant for the alveoli. But these cells also play a part in defending against foreign pathogens, like viruses and bacteria.
188 COVID Autopsies
Well, as it turns out, these type II alveolar cells have the ACE2 receptors on them, and SARS-CoV-2 binds to this receptor, and that’s how it gains entry into these cells and our body. When the SARS-CoV-2 invades the type II alveolar cells, it precipitates a cascade of reactions that causes the body to react to it, with inflammation and lots of damage to the alveoli, known as diffuse alveolar damage. Clinically, this is what we call ARDS, acute respiratory distress syndrome.
This is what causes oxygen levels to go down and what causes the so-called cytokine storm. When people die of COVID, this is what’s going. Also, there is a propensity for blood clots to develop, and some people with COVID died due to pulmonary emboli, meaning blood clots in their lungs. The capillaries in the lung surround the alveoli. Here, they serve to bring red blood cells near the alveoli to allow gas exchange to occur, as I mentioned earlier.
The lining of these capillaries is called the endothelium; the cells that make up the endothelium here also have ACE2 receptors. At least in those with severe disease, the virus seems to be infiltrating the endothelium and causing inflammation and injury to the capillaries, not just the alveoli. This likely at least partially explains why this virus is causing blood clots to develop here.
So we see a common theme here: microthrombi found in blood vessels of pretty much all the organs, including the brain, kidneys, heart, liver, and of course, lungs. This is likely all because of endothelial damage that occurs due to the virus binding to the ACE2 receptors that are located there.
After all, in some of these autopsy studies, they used electron microscopy to find what appeared to be viral particles in the endothelial cells, not only in the lungs but also in the heart and kidneys. The endothelial damage serves to trigger the clotting process, something known as a coagulation cascade. But is also possible that the endothelial damage is mainly occurring in the lung capillaries, where the tiny clots first develop. Then they travel to other parts of the body, eventually lodging in blood vessels of other organs.
Or it could be both of these things. It’s interesting to note that Endothelial cells are more vulnerable to dying in people with preexisting endothelial dysfunction, which is more often associated with being a male, being a smoker, having high blood pressure, diabetes, and obesity. So overall, organ damage that occurs in severe COVID is likely a result of a multitude of factors, such as:
1) Directly viral invasion using the ACE2 receptor
2) Indirect damage that occurs as a result of cytokine storm
3) Indirect damage using blood clots
4) Indirect damage that occurs as a result of oxygen deprivation, as well as toxic effects of various drug treatments, and other factors as well
Doctor Mike Hansen, MD
Internal Medicine | Pulmonary Disease | Critical Care Medicine
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