The Effects of Aβ1-42 Binding to the SARS-CoV-2 Spike Protein S1 Subunit and Angiotensin-Converting Enzyme 2

Increasing evidence suggests that elderly people with dementia are vulnerable to the development of severe coronavirus disease 2019 (COVID-19). In Alzheimer's disease (AD), the major form of dementia, beta-amyloid (A beta) levels in the blood are increased; however, the impact of elevated A beta levels on the progression of COVID-19 remains largely unknown. Here, our findings demonstrate that A beta(1-42), but not A beta(1-40), bound to various viral proteins with a preferentially high affinity for the spike protein S1 subunit (S1) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the viral receptor, angiotensin-converting enzyme 2 (ACE2). These bindings were mainly through the C-terminal residues of A beta(1-42). Furthermore, A beta(1-42) strengthened the binding of the S1 of SARS-CoV-2 to ACE2 and increased the viral entry and production of IL-6 in a SARS-CoV-2 pseudovirus infection model. Intriguingly, data from a surrogate mouse model with intravenous inoculation of A beta(1-42) show that the clearance of A beta(1-42) in the blood was dampened in the presence of the extracellular domain of the spike protein trimers of SARS-CoV-2, whose effects can be prevented by a novel anti-A beta antibody. In conclusion, these findings suggest that the binding of A beta(1-42) to the S1 of SARS-CoV-2 and ACE2 may have a negative impact on the course and severity of SARS-CoV-2 infection. Further investigations are warranted to elucidate the underlying mechanisms and examine whether reducing the level of A beta(1-42) in the blood is beneficial to the fight against COVID-19 and AD.