Lactoferrin binding to Sars-CoV-2 Spike glycoprotein protects host from infection, inflammation and iron dysregulation

The anti-SARS-Cov-2 activity of the iron-binding protein Lactoferrrin has been investigated in epithelial and macrophagic cell models using a Pseudovirus decorated with the SARS-CoV-2 Spike glycoprotein. The human and, even more, the nutraceutically available bovine Lactoferrin inhibit pseudoviral infection in all cellular models tested. The bovine protein efficiently counteracts the deleterious effects of purified Spike on iron and inflammatory homeostasis, as shown by restored levels of the main proteins of the iron-handling system and, in the case of macrophagic THP-1 cells, of the proinflammatory cytokines IL-1β and IL-6. A direct interaction between Lactoferrin and Spike is likely at the basis of the observed effects, as demonstrated by an in vitro pull-down assay. Finally, in silico approaches have been applied to analyze the interactions of human and bovine Lactoferrins with Transferrin Receptor 1, a potential gate for SARS-CoV-2 entry into cells, as well as the binding of the bovine protein to different variants of concern of the SARS-Cov-2 Spike glycoprotein. Our results give hope for the employment of bovine Lactoferrin as an adjuvant of the standard of care therapies in COVID-19 treatment.