Metformin and Phenformin Attenuate SARS-CoV-2 Spike Protein S1-Induced Endothelial Inflammation Involving AMPK/NF-κB Signaling in HUVECs

OBJECTIVE: COVID-19, caused by SARS-CoV-2, is a systemic disease with vascular involvement. The spike protein subunit 1 (S1) has been suggested to contribute to endothelial dysfunction by modulating AMP-activated protein kinase (AMPK) signaling and nuclear factor kappa B (NF-κB) activation, potentially promoting inflammation, thrombosis, and vascular injury.This study aimed to investigate the effects of metformin and phenformin, biguanide drugs with known AMPK-activating properties, on S1-induced inflammatory responses and AMPK/NF-κB pathway modulation in human umbilical vein endothelial cells (HUVECs). MATERIALS AND METHODS: HUVECs were used as a model of the macrovascular endothelium, which is known to exhibit endothelial dysfunction and inflammation associated with vascular complications in COVID-19. Cells were exposed to the S1 protein for 1 and 24 hours, followed by treatment with phenformin (10 µM and 100 µM) or metformin (100 µM and 1000 µM). Cell viability, AMPK activation, NF-κB phosphorylation, and monocyte adhesion were evaluated. RESULTS: S1 exposure was associated with increased endothelial cell viability and NF-κB activity, along with decreased AMPK phosphorylation. Metformin, particularly at 1000 µM, was associated with increased AMPK activity and reduced NF-κB signaling and monocyte adhesion. Phenformin (10 µM and 100 µM) showed similar but less pronounced effects. These findings suggest that the S1 protein may contribute to endothelial dysfunction in HUVECs. Metformin, at higher concentrations, may mitigate these effects through modulation of the AMPK/NF-κB signaling pathway. CONCLUSION: Metformin may exert protective effects against S1 protein-induced endothelial inflammation and dysfunction via modulation of AMPK/NF-κB signaling. Further studies are needed to confirm these findings.