SARS-CoV-2 spike protein receptor-binding domain perturbates intracellular calcium homeostasis and impairs pulmonary vascular endothelial cells

Abstract

Exposure to the spike protein or receptor-binding domain (S-RBD) of SARS-CoV-2 significantly influences endothelial cells and induces pulmonary vascular endotheliopathy. In this study, angiotensin-converting enzyme 2 humanized inbred (hACE2 Tg) mice and cultured pulmonary vascular endothelial cells were used to investigate how spike protein/S-RBD impacts pulmonary vascular endothelium. Results show that S-RBD leads to acute-to-prolonged induction of the intracellular free calcium concentration ([Ca2+]i) via acute activation of TRPV4, and prolonged upregulation of mechanosensitive channel Piezo1 and store-operated calcium channel (SOCC) key component Orai1 in cultured human pulmonary arterial endothelial cells (PAECs). In mechanism, S-RBD interacts with ACE2 to induce formation of clusters involving Orai1, Piezo1 and TRPC1, facilitate the channel activation of Piezo1 and SOCC, and lead to elevated apoptosis. These effects are blocked by Kobophenol A, which inhibits the binding between S-RBD and ACE2, or intracellular calcium chelator, BAPTA-AM. Blockade of Piezo1 and SOCC by GsMTx4 effectively protects the S-RBD-induced pulmonary microvascular endothelial damage in hACE2 Tg mice via normalizing the elevated [Ca2+]i. Comparing to prototypic strain, Omicron variants (BA.5.2 and XBB) of S-RBD induces significantly less severe cell apoptosis. Transcriptomic analysis indicates that prototypic S-RBD confers more severe acute impacts than Delta or Lambda S-RBD. In summary, this study provides compelling evidence that S-RBD could induce persistent pulmonary vascular endothelial damage by binding to ACE2 and triggering [Ca2+]i through upregulation of Piezo1 and Orai1. Targeted inhibition of ACE2-Piezo1/SOCC-[Ca2+]i axis proves a powerful strategy to treat S-RBD-induced pulmonary vascular diseases.

Reduction in D-dimer Levels After Treatment with Auxora in Patients with Severe Covid-19 Pneumonia Reflects Endothelial Stabilization

“…Supporting this suggestion of a direct effect on the endothelium are the results of a recently published study in in-vivo ACE2 humanized inbred mice and in-vitro cultured human and mice pulmonary vascular endothelial cells that demonstrated that the receptor binding domain of the SARS-CoV-2 virus caused pulmonary vascular endothelial damage in part by upregulating Orai1 and triggering calcium in ux. 27 Treatment with Auxora would block this calcium in ux and consequently prevent endothelial damage independently of a decrease in systemic in ammation.…”

Understanding COVID-19-associated endothelial dysfunction: role of PIEZO1 as a potential therapeutic target

“…Pharmacological inhibition of Piezo1 using GsMTx4 effectively prevents disruption of intracellular calcium homeostasis in endothelial cells. These findings strongly suggest that targeting Piezo1 could be a potential therapeutic strategy for mitigating S-RBD-induced pulmonary vascular damage, offering novel insights into the management of COVID-associated pulmonary vascular diseases and long-term complications in individuals with long COVID ( 96 ). It has been also reported to enhance lung endothelial barrier function and mitigate ventilator-induced lung injury by suppressing Src-induced VE-cadherin phosphorylation ( 7 ).…”

“…The spike protein of SARS-CoV-2 features a critical region known as the spike protein receptor-binding domain (S-RBD), which exhibits a high affinity for human ACE-2 receptors and is crucial for viral entry ( 94 , 95 ). S-RBD has been implicated in inducing an acute to prolonged increase in intracellular calcium concentration in human pulmonary arterial endothelial cells, which is associated with the activation and expression of Piezo1 and store-operated calcium channels (SOCC) ( 96 ). The SARS-CoV-2 induced persistent perturbation of intracellular calcium homeostasis, driven by the upregulation of Piezo1 and other calcium channels, may lead to elevated apoptosis and impairment of pulmonary vascular endothelial cells, contributing to the vascular complications observed in severe COVID-19 cases.…”

“…Additionally, the S-RBD disrupts intracellular calcium homeostasis and triggers cell apoptosis by engaging with the ACE2 receptor and formation of ACE2-bounded calcium channel clusters ( 96 ). The formation of clusters involving ACE2, Piezo1, and SOCC, induced by the S-RBD, suggests a complex interplay between the virus and the host’s calcium signaling system.…”

“…Although there is limited research on MS ion channels in the context of COVID-19-associated endothelial dysfunction, a recent preclinical investigation has shown promising results regarding the pharmacological inhibition of Piezo1 using GsMTx4 ( 96 ). This inhibition helps maintain intracellular calcium homeostasis in endothelial cells and may hold potential for managing pulmonary vascular disorders associated with COVID-19 and long-term complications in individuals with long COVID.…”