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bioRxiv · 10.1101/2025.09.12.675877

Immunoregulatory effect of metformin in monocytes exposed to SARS-CoV-2 spike protein subunit 1

Maurmann, R. M.·Davis, K.·Mosalmanzadeh, N.·Schmitt, B. L.·Pence, B. D.
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Abstract

BackgroundSevere COVID-19 is characterized by a hyperinflammatory state associated with an exacerbated inflammatory activation of monocytes and macrophages in the respiratory tract. Metformin has been identified as a potent monocyte inflammatory suppressor, and it has been demonstrated to attenuate inflammation in COVID-19. The mechanisms underlying metformin anti-inflammatory effects are, however, unclear. We thus sought to investigate metformins main interactions and their respective isolated effects in modulating monocyte inflammatory response to SARS-CoV-2 stimulation. MethodsClassical human monocytes were isolated from healthy 18-40-year-old individuals and stimulated in vitro with recombinant spike protein subunit 1 (rS1) to assess glycolytic and oxidative metabolic responses by Seahorse extracellular flux analysis, and inflammatory gene expression by qPCR. Stimulated monocytes were either pre-treated with metformin, rotenone, S1QEL, or A769662. ResultsMonocytes stimulated in vitro with rS1 showed an increased glycolytic response associated with production of pro-inflammatory cytokines. Metformin pre-treatment reduced glycolytic activation while partially suppressing inflammation. Rotenone-dependent mitochondrial complex I inhibition was not able to replicate the same effect, and neither complex I specific ROS scavenging. Conversely, A769662 induced AMPK activation led to suppressed glycolytic inflammatory response and cytokine expression pattern similar to metformin, thus suggesting AMPK modulation as a possible central component for metformins mode of action upon S1 stimulation. ConclusionsIn summary, further investigation into the interactions underlying AMPK activity on monocytes in the context of SARS-CoV-2 may provide a better elucidation of metformins anti-inflammatory effect.

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Maurmann, R. M., Davis, K., Mosalmanzadeh, N., Schmitt, B. L., Pence, B. D.. 2025-09-12. Immunoregulatory effect of metformin in monocytes exposed to SARS-CoV-2 spike protein subunit 1. https://doi.org/10.1101/2025.09.12.675877

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