Expression of SARS-CoV-2-related Receptors in Cells of the Neurovascular Unit: Implications for HIV-1 Infection

Abstract

Background. Neurological complications are common in patients affected by COVID-19 due to the ability of SARS-CoV-2 to infect brains. While the mechanisms of this process are not fully understood, it has been proposed that SARS-CoV-2 can infect the cells of the neurovascular units (NVU), which form the blood-brain barrier (BBB). The aim of the current study was to analyze the expression pattern of the main SARS-CoV-2 receptors in naïve and HIV-1-infected cells of the NVU in order to elucidate a possible pathway of the virus entry into the brain and a potential modulatory impact of HIV-1 in this process. Methods. The gene and protein expression profile of ACE2, TMPRSS2, ADAM17, BSG, DPP4, AGTR2, ANPEP, cathepsin B and cathepsin L was assessed by qPCR and immunoblotting, respectively. In addition, we investigated if brain endothelial cells can be affected by the exposure to the S1 subunit of the S protein, the domain responsible for the direct binding of SARS-CoV-2 to the ACE2 receptors. Results. The receptors involved in SARS-CoV-2 infection are coexpressed in the cells of the NVU, especially in astrocytes and microglial cells. These receptors are functionally active as exposure of endothelial cells to the SARS CoV-2 S1 protein subunit altered the expression pattern of tight junction proteins, such as claudin-5 and ZO-1. Additionally, HIV-1 infection upregulated ACE2 and TMPRSS2 expression in brain astrocytes and microglia cells.Conclusions. These findings provide key insight into SARS-CoV-2 recognition by cells of the NVU and may help to develop possible treatment of CNS complications of COVID-19.

SARS-CoV-2 infection of human brain microvascular endothelial cells leads to inflammatory activation through NF-κB non-canonical pathway and mitochondrial remodeling

“…In the present study we have investigated the molecular indices of Neuro-COVID-19 as they are related to brain endothelial cells forming the BBB. Despite our previous observation that primary HBMECs express several receptors for the virus (Torices et al, 2021), we found little to no indication of productive viral replication in the supernatants of HBMECs which is in accordance with previous reports that described that several endothelial cell types are not permissive for SARS-CoV-2 productive infection (McCracken et al, 2021; Nascimento Conde et al, 2021). Krasemann et al, (2022) observed infection of iPS-derived HBMECs but only at MOIs 10 and 100, which are unlikely to have pathological significance.…”

“…In the same context, HBMECs infected with different MOIs did not show any increase in the expression of SARS-CoV-2 Spike1 and E genes at 6 and 24 hpi ( Figure 1B ). We showed recently that HBMEC cells express, to some extent, several of SARS-CoV-2 receptors at both RNA and protein levels (Torices et al, 2021). Therefore, we evaluated the possible effect of infection on the expression of ACE2 and TMPRSS2 in HBMEC cells and found that infection with the MOI 0.1 induced a 40% decrease in ACE2 mRNA expression (p<0.05), which did not result in ACE2 protein level alterations ( Figure 1C ).…”

“…Upon S1-ACE2 interaction, a transmembrane serine protease 2 (TMPRSS2) is required for priming of the S protein and viral entry into the cell (Coronaviridae Study Group of International Committee on Taxonomy of Viruses, 2020; Zhu et al, 2020; Ni et al, 2019). Along with ACE2 and TMPRSS2, several other proteins have been suggested to participate in SARS-CoV-2 entry into human cells, such as ADAM metallopeptidase domain 17 (ADAM17) (Torices et al, 2021; Hoffmann et al, 2020), dipeptidyl peptidase 4 (DPP4) (Zhou et al, 2020; Shulla et al, 2011), angiotensin II receptor type 2 (AGTR2) (Zipeto et al, 2020; Schreiber et al, 2020), basigin (BSG, also called extracellular matrix metalloproteinase inducer [EMMPRIN] or cluster of differentiation 147 [CD147]) (Solerte et al, 2020; Bassendine et al, 2020), aminopeptidase N (ANPEP) (Cui et al, 2020) and cathepsin B/L (de Souza et al 2020; Wang et al, 2020).…”

A novel histone deacetylase inhibitor‐based approach to eliminate microglia and retain astrocyte properties in glial cell culture

“…At least two risk factors are believed to contribute to the CNS vulnerability to SARS‐CoV‐2: direct viral invasion and infection of CNS cells (Cantuti‐Castelvetri et al, 2020; Meinhardt et al, 2021) and indirect immune response from peripheral infection (Pellegrini et al, 2020; Yang et al, 2021), both of which are tightly associated with glial‐mediated CNS immunity. Indeed, multiple evidence exist confirming the expression of angiotensin‐converting enzyme 2, the receptor for the spike protein of SARS‐CoV‐2 in astrocytes and microglia (Chen et al, 2021; Gowrisankar & Clark, 2016; Hernández et al, 2021; Torices et al, 2021). Experimental studies have shown that the spike protein of SARS‐CoV‐2 is able to trigger immune responses in macrophage and microglia (Frank et al, 2022; Shirato & Kizaki, 2021; Zhao et al, 2021).…”

Auricular Transcutaneous Vagus Nerve Stimulation may Increase the Risk of Mild-COVID-19 Infection or of Herpetic Flare: Is there a Role of Microbiota?

“…SARS-CoV-2 enters the cells through the angiotensin-converting enzyme-2 receptors (ACE2-R). The expression of ACE2-R is markedly upregulated on activated type 1 macrophages such as alveolar macrophages, Kupffer cells within liver, and microglial cells in brain [58][59][60]. Microglial cells are known to participate to the transport of SARS-CoV-2 to the brain [61].…”