Investigating the role and therapeutic potential of the alpha5beta1 integrin in risk factors for COVID-19-associated cognitive impairment - ABSTRACT Rapidly emerging evidence has characterized the association between vascular dementia (VaD) and increased COVID-19 incidence, morbidity, and post-COVID cognitive decline. We theorize that brain vascular pathology in VaD and additional pathophysiologic features such as blood-brain barrier (BBB) disruption and reduced cerebral blood flow may directly contribute to both VaD and COVID-19. Several lines of evidence support this hypothesis. First, we have demonstrated that SARS-CoV-2 binds to the vascular integrin α5β1 receptor to infect cells, the same receptor we have also linked to BBB disruption in brain ischemia (stroke) models and chronic bilateral carotid artery stenosis (BCAS), which models pathophysiological aspects of VaD such as reduced cerebral blood flow, BBB disruption, neuroinflammation, white matter damage, and cognitive decline. Second, integrin α5β1 is substantially upregulated in an age-dependent fashion (aged>young) in the brain vasculature after stroke and BCAS, and inhibition of this receptor with the clinically-validated integrin α5β1 pentapeptide inhibitor ATN-161 lessens BBB disruption and cognitive impairment in these models. Third, SARS-CoV-2 infection also increases integrin α5β1 expression in vivo and disrupts the BBB. Forth, preliminary results suggest that SARS-CoV-2 infection after BCAS further increases morbidity vs. BCAS or infection alone and accelerates brain vascular integrin α5β1 upregulation. Fifth, ATN-161 inhibits SARS-CoV-2 infection in vitro and in vivo and prevents SARS- CoV-2-induced increased expression of α5β1 integrin. Finally, although angiotensin-converting enzyme 2 (ACE2) is the canonical receptor for viral entry (internalization and fusion) into host cells, its ectodomain binds the viral spike protein (S-protein) on the surface to facilitate virus attachment and access into host cells through receptor-mediated endocytosis using an RGD motif. As many cell-surface integrins also bind RGD, we and others have provided compelling evidence that integrins are co-receptors of the virus. Additionally, we have shown that talin-dependent integrin activation is required for SARS-CoV-2 infectivity. Consistent with our results, previous studies have shown that α5β1 and ACE2 engage in signaling crosstalk likely driven by mutual interaction at their cytoplasmic tails. Building on these findings, we hypothesize that (i) integrin α5β1 plays an important age-dependent pathogenic role in the association between SARS-CoV-2 infection and VaD by worsening pre-existing VaD after COVID-19, (ii) ATN-161 treatment before, during, or after COVID-19 infection will stabilize BBB integrity to improve COVID-19 neurocognitive outcomes in the context of pre-existing vascular dementia, and (iii) integrin α5β1 signaling regulates infectivity, and its upregulation potentiates dysregulation of the BBB. To investigate these hypotheses, we propose to 1). Demonstrate that experimental VaD worsens COVID-19 morbidity and subsequent cognitive decline, 2). Determine the therapeutic potential of integrin α5β1 inhibition in improving VaD post-COVID morbidity and cognitive decline, 3). Determine the signaling mechanism of integrin α5β1 required for SARS-CoV-2 productive infection and dysregulation of cell barrier function.
