Endothelial dysfunction plays a central role in COVID-19 pathogenesis, by affecting vascular homeostasis and worsening thromboinflammation. This imbalance may contribute to blood–brain barrier (BBB) disruption, which has been reported in long COVID-19 patients with neurological sequelae. The kallikrein–kinin system (KKS) generates bradykinin (BK), a proinflammatory peptide that induces microvascular leakage via B2R. Under inflammatory conditions, BK is converted to Des-Arg-BK (DABK), which activates B1R, a receptor upregulated in inflamed tissues. DABK is degraded by ACE2, the main SARS-CoV-2 receptor; thus, viral binding and ACE2 downregulation may lead to DABK/B1R imbalance. Here, we investigated these interactions using human brain microvascular endothelial cells (HBMECs), as a model of the BBB. Since endothelial cell lines express low levels of ACE2, HBMECs were modified with an ACE2-carrying pseudovirus. SARS-CoV-2 replication was confirmed by RNA, protein expression, and infectious particles release. Infection upregulated cytokines and endothelial permeability, enhancing viral and leukocyte transmigration. Additionally, viral replication impaired ACE2 function in HBMECs, amplifying the response to DABK, increasing nitric oxide (NO) production, and further disrupting endothelial integrity. Our findings reveal a mechanism by which SARS-CoV-2 impacts the BBB and highlights the ACE2/KKS/B1R axis as a potential contributor to long COVID-19 neurological symptoms.

Hydroxypropyl-beta-cyclodextrin (HP-BCD) is a cholesterol sequestering agent that has been explored as a potential antiviral drug against enveloped viruses and is currently under clinical investigation for Niemann Pick C disease. We previously demonstrated that HP-BCD inhibits SARS-CoV-2 replication and infectivity by targeting both host cells and viral particles. In this study, we investigated the molecular mechanisms underlying HP-BCD antiviral activity against SARS-CoV-2 in vitro. Treatment of Vero cells with HP-BCD altered intracellular compartmentalization, as indicated by the redistribution of early endosome markers. Also, HP-BCD treatment prior to SARS-CoV-2 inoculation promoted an accumulation of nucleocapsid protein at early time points after infection. Infected cells pretreated with HP-BCD exhibited reduced cholesterol and lipid droplets content, potentially hampering the formation of new double-membrane vesicles. Consistently, viral replication complexes were scarcely detected in treated cells, which displayed disformed vesicle-like structures and lacked membrane-associated virus particles. Notably, HP-BCD also reduced viral replication when administered after virus adsorption, although with lower efficacy, indicating interference with potentially multiple stages of the SARS-CoV-2 life cycle. These findings suggest that HP-BCD effectively impairs SARS-CoV-2 biosynthesis through multiple mechanisms with minimal cytotoxicity, supporting its potential as a promising antiviral candidate.