Have been struggling with the Oak Ridge paper (that the Medium article above is based on) and another paper by a couple of prominent cardiologists, which just came out in the journal Circulation (by the American Heart Association), which seems somewhat complementary, but somewhat contradictory to the Oak Ridge one. And on top of that, there's a recent commentary in JAMA, by some Dutch doctors, saying the "cytokine storm" (over-inflammation reaction from the immune system), which many have said is key to the death spiral in many patients, doesn't really occur in COVID patients, which kind of supports the Oak Ridge paper, but is not in complete agreement with the Circulation paper (although they weren't investigating the inflammatory part of the system). Clearly, there's still some confusion out there amongst the medical experts on what exactly is going on with COVID, especially at the cellular level and how that impacts macro-level patient outcomes.
I think what the Oak Ridge folks are saying is that there is an incredibly complex cascade of effects once the virus enters both lung and vascular endothelial cells, via the ACE2 (angiotensin converting enzymes) pathway, eventually leading to wild swings in the RAS system (renin-angiotensin system), which induce similar effects in the related bradykinin system, leading to "bradykinin storms" featuring massive buildup of bradykinin in the body, leading to many of COVID's deadly effects. At one point, they do say, “the pathology of Covid-19 is likely the result of Bradykinin Storms rather than cytokine storms,” which
had been previously identified in Covid-19 patients, but that “the two may be intricately linked.” They also mention that this can lead to increased production of hyaluronic acid (HLA, a molecule that can trap 1000X its weight in water) in the lungs. forming a "hydrogel," and according to the paper, once this happens, “it’s
like trying to breathe through Jell-O.”
The Circulation paper makes the case that while COVID is obviously a respiratory disease, at its heart (pun intended) it's more of a microvascular disease: "We propose that severe COVID-19 is a microvascular disease in which coronavirus infection activates endothelial cells, triggering exocytosis, a rapid vascular response that drives microvascular inflammation and thrombosis." This paper goes through a ton of clinical data on progression of the disease, especially in blood vessel epithelial cells, host to countless ACE2 receptors, and talks about how that can lead to the "cytokine storms" and ARDS (acute respiratory distress syndrome), but due to the underlying vascular issues. I would imagine "bradykinin storms" which are part of the vascular system would be consistent with their research (it's just not a detail they looked into, I think).
The Dutch paper was aimed specifically at trying to measure cytokines for patients in the "cytokine storm" phase of severe COVID disease, but their findings were that they didn't really see highly elevated levels of cytokines. As per the authors, "The results from this study show that COVID-19 is not characterized by a cytokine storm....the severe disease observed in critically ill COVID-19 patients is therefore not explained by strongly elevated levels of inflammatory proteins in the blood. This means that critically ill COVID-19 patients likely will not benefit from specific anti-cytokine therapies." Obviously, there are all kinds of systemic effects leading to serious illness and death in many COVID patients, but maybe those aren't driven by a cytokine storm.
I'll admit confusion here. Might be time to "phone a friend," lol. Maybe one of our medical/immunology folks can help make more sense of this (and correct any major errors I might have above).
@LETSGORU91 @93RUDoc @RUfubar @UMRU?
Gene expression analysis reveals a novel, integrated molecular mechanism for much of the pathogenesis of COVID-19 that provides therapeutic intervention points that can be addressed with existing approved pharmaceuticals.
elifesciences.org
4 September 2020
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