ACE-2-like Enzymatic Activity in COVID-19 Convalescent Patients with Persistent Pulmonary Symptoms Associated with Immunoglobulin

Many difficult to understand clinical features characterize COVID-19 and Post-Acute Sequelae of COVID-19 (PASC or Long COVID, LC). These can include blood pressure instability, hyperinflammation, coagulopathies, and neuropsychiatric complaints. The pathogenesis of these features remains unclear. The SARS-CoV-2 Spike protein Receptor Binding Domain (RBD) binds Angiotensin Converting Enzyme 2 (ACE2) on the surface of host cells to initiate infection. We hypothesized that some patients may produce anti-RBD antibodies that resemble ACE2 sufficiently to have ACE2-like catalytic activity, that is they are ACE2-like proteolytic abzymes that may help mediate the pathogenesis of COVID-19 and LC. In previous work, we showed that some acute COVID-19 patients had immunoglobulin-associated ACE2-like proteolytic activity, suggesting that some COVID-19 patients indeed produced ACE2-like abzymes. However, it remained unknown whether ACE2-like abzymes were seen only in acute COVID-19 patients or whether ACE2-like abzymes could also be identified in convalescent COVID-19 patients. Here we show that some convalescent COVID-19 patients attending a clinic for patients with persistent pulmonary symptoms also have ACE2-like abzymes and that the presence of ACE2-like catalytic activity correlates with alterations in blood pressure in an exercise test.