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

Abstract

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.

Molecular mimicry of the receptor-binding domain of the SARS-CoV-2 spike protein: from the interaction of spike-specific antibodies with transferrin and lactoferrin to the antiviral effects of human recombinant lactoferrin

“…Interaction of Lf with Spike protein has been documented already in three studies (Campione et al 2021 ; Miotto et al 2021 ; Cutone et al 2022 ). Interaction of Lf with Spike protein prevents its interaction with anti-Lf mAbs (Fig.…”

“…Noteworthy, the RBD of Spike protein of all SARS-CoV-2 lineages also contains RGD motif, whereas it is absent in previous human coronavirus variants (Dakal 2021 ; Makowski et al 2021 ; Othman et al 2022 ; Norris et al 2022 ). Moreover, the interaction of Spike protein with bovine Lf has been reported in at least three studies (Campione et al 2021 ; Miotto et al 2021 ; Cutone et al 2022 ). Several studies demonstrated protective effects of Lf (recombinant and milk-derived) against SARS-CoV-2 infection in vitro (Campione et al 2021 ; Prieto-Fernández et al 2021 ; Salaris et al 2021 ; Mirabelli et al 2021 ; Hu et al 2021 ; Lai et al 2022 ; Worting et al 2022 ; Cutone et al 2022 ).…”

“…Moreover, the interaction of Spike protein with bovine Lf has been reported in at least three studies (Campione et al 2021 ; Miotto et al 2021 ; Cutone et al 2022 ). Several studies demonstrated protective effects of Lf (recombinant and milk-derived) against SARS-CoV-2 infection in vitro (Campione et al 2021 ; Prieto-Fernández et al 2021 ; Salaris et al 2021 ; Mirabelli et al 2021 ; Hu et al 2021 ; Lai et al 2022 ; Worting et al 2022 ; Cutone et al 2022 ). Different mechanisms of antiviral effect of Lf have been proposed, but not all papers contain information on the degree of iron saturation of Lf.…”

The Influence of Viral Infections on Iron Homeostasis and the Potential for Lactoferrin as a Therapeutic in the Age of the SARS-CoV-2 Pandemic

“…Additionally, macrophages are presumed to be infected by COVID-19, and increased iron storage in macrophages may favor viral replication [ 77 ]. More recently, Cutone et al demonstrated in both enterocytes and macrophages that the SARS-CoV-2 spike protein can induce the dysregulation of major iron-handling proteins, including the downregulation of ferroportin, DMT-1, and hephaestin and the upregulation of TfR1 [ 66 ].…”

“…Interestingly, they found that Lf bound the ACE2 receptor ectodomain, indicating that hLf may competitively inhibit RBD binding by either directly interfering with the ACE2-RBD interaction or by binding an ACE2 receptor region far from the RBD site, triggering conformational changes of the ACE2 receptor and inhibiting RBD binding [ 64 ]. In contrast, Cutone et al recently showed that both hLf and bLf do interact with the SARS-CoV-2 trimeric form of a full-length spike protein, even with the introduction of point mutations observed in recent viral variants [ 66 ]. Clearly, further studies are warranted; however, these in vitro results are promising, especially given the continued efficacy of Lf when challenged with newly emergent viral variants.…”