Ken, you understandably questioned why the study c
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https://journals.plos.org/plosone/article?id=...ne.0257016
Limitations of this study include the (i) use of deidentified samples so a correlation with PASC symptoms could not be determined, (ii) a relatively small sample size, and (iii) the inability of our assay to distinguish between IgG and IgM ACE2 antibodies. Moreover, the study does not prove a causal relationship between anti-ACE2 antibodies and symptoms of PASC as we do not have any data regarding PASC symptoms in this cohort.
Nevertheless, the finding that ACE2 antibodies are present after infection with SARS-CoV-2 and that plasma from patients with antibodies can inhibit ACE2 activity provides a potential mechanism for PASC.
These studies show for the first time that ACE2 antibodies are present after SARS-CoV-2 infection. This finding is consistent with a hypothesis that ACE2 antibodies may be involved in a process that leads to immune activation. While we do not have data about the association of ACE2 antibodies and PASC in this cohort, we hypothesize that antibodies could initiate a cascade of effects that lead to the symptoms of PASC. If these antibodies are responsible for symptoms of PASC, several treatments are possible. Angiotensin receptor blockers are safe and widely used. These drugs would mitigate the effects of increased Ang II caused by inhibition of ACE2. An association between protection from sequelae of SARS-CoV-2 infection and treatment with angiotensin receptor blockers or ACE inhibitors has not yet been examined but should be a high priority for ongoing research into PASC. Treatment with these RAS blockers may not be possible however in patients with low blood pressure. More targeted therapy of the mechanism of ACE2 inhibition is possible. Recombinant soluble ACE2 protein is proposed as a treatment during acute phases of infection but may also be useful for PASC. Small molecule activators of ACE2 are available and have been proposed for treatment of hypertension and may be useful for the treatment of PASC [22, 23]. Thus if the relationship between ACE2 antibodies and PASC is confirmed, several treatments will be available.