Bovine lactoferrin for the prevention of COVID-19 infection in health care personnel: a double-blinded randomized clinical trial (LF-COVID)

A comprehensive review of research advances in the study of lactoferrin to treat viral infections

Lactoferrin (Lf) is a naturally occurring glycoprotein known for its antiviral and antibacterial properties and is present in various physiological fluids. Numerous studies have demonstrated its antiviral effectiveness against multiple viruses, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza virus (IFV), herpes simplex virus (HSV), hepatitis B virus (HBV), and human immunodeficiency virus (HIV). Lf, a vital component of the mucosal defense system, plays a crucial role in inhibiting viral infection by binding to both host cells and viral particles, such as the Hepatitis C virus (HCV). This interaction enables Lf to keep viral particles away from their target cells, emphasizing its significance as a fundamental element of mucosal defense against viral infections. Additionally, Lf has the ability to modulate cytokine expression and enhance cellular immune responses. In the innate immune system, Lf serves as a unique iron transporter and helps suppress various pathogens like bacteria, fungi, and viruses. This article summarises the potential antiviral properties of Lf against various viruses, along with its other mentioned functions. The advancement of Lf-based therapies supports the homology of food and medicine, providing a promising avenue to address viral infections and other public health challenges.

The Proteolytic Activity of Neutrophil-Derived Serine Proteases Bound to the Cell Surface Arming Lung Epithelial Cells for Viral Defense

The collaboration between cellular proteases and host cells is pivotal in mounting an effective innate immune defense. Of particular interest is the synergistic interaction between cathepsin G (CatG) and neutrophil elastase (NE), which are proteases secreted by activated neutrophils, and the human alveolar basal epithelial cell line (A549) and the human lung epithelial-like cell line (H1299), because of the potential implications for viral infection. Our study aimed to investigate the binding capacity of CatG and NE on the surface of A549 and H1299 cells through preincubation with purified CatG and NE; thereby, the proteolytic activity could be detected using activity-based probes. Both CatG and NE were capable of binding to the cell surface and exhibited proteolytic activity, leading to increased cell surface levels of MHC I molecules, which is crucial for displaying the endogenous antigenic repertoire. In addition, CatG cleaved the S2' site of the SARS-CoV-2 spike protein at two specific sites (815RS816 and 817FI818) as well as NE (813SK814 and 818IE819), which potentially leads to the destruction of the fusion peptide. Additionally, furin required the presence of Ca2+ ions for the distinct cleavage site necessary to generate the fusion peptide. Overall, the findings suggest that CatG and NE can fortify target cells against viral entry, underscoring the potential significance of cell surface proteases in protecting against viral invasion.

Assessment of Supplementation with Different Biomolecules in the Prevention and Treatment of COVID-19

Consequences of the disease produced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have led to an urgent search for preventive and therapeutic strategies. Besides drug treatments, proposals have been made for supplementation with biomolecules possessing immunomodulatory and antioxidant properties. The objective of this study was to review published evidence on the clinical usefulness of supplementation with vitamin D, antioxidant vitamins (vitamin A, vitamin E, and vitamin C), melatonin, lactoferrin and natural products found in food (curcumin, luteolin, ginger, allicin, magnesium and zinc) as supplements in SARS-CoV-2 infection. In general, supplementation of conventional treatments with these biomolecules has been found to improve the clinical symptoms and severity of the coronavirus disease (COVID-19), with some indications of a preventive effect. In conclusion, these compounds may assist in preventing and/or improving the symptoms of COVID-19. Nevertheless, only limited evidence is available, and findings have been inconsistent. Further investigations are needed to verify the therapeutic potential of these supplements.

MFGM-enriched whey displays antiviral activity against common pediatric viruses in vitro

Background

Among the most common mucosal viral infections in infants are rotavirus, one of the main causes of severe gastroenteritis in infants and children up to 5 years, and respiratory syncytial virus (RSV), one of the leading causes of lower respiratory tract infections. Both human milk and bovine milk derived factors may provide protection against mucosal viral infections. More recently, a similar activity of milk derived proteins was suggested for SARS-CoV-2. The goal of the current study was to test antiviral activity of the bovine milkfat globule membrane (MFGM) against rotavirus, RSV and SARS-CoV-2 and to further characterize MFGM-enriched whey to identify which components in MFGM-enriched whey may contribute to the inhibitory activity.

Methods

The effects of MFGM-enriched whey, its whey protein isolate counterpart (WPI, obtained from the same production process) and a conventional whey protein concentrate (WPC) on rotavirus (strains Wa and SA114F), RSV (strain RSV-A2) and SARS-CoV-2 (Alpha variant) infectivity were determined using MA104 cells, human alveolar basal epithelial (A549) cells and monkey kidney (Vero E6) cells, respectively. The compounds were characterized in detail by LC-MS/MS and 31P-NMR to determine protein and phospholipid composition, respectively.

Results

Relative to its WPI counterpart, MFGM-enriched whey demonstrated a dose-dependent inhibition for both rotavirus and RSV whereas for SARS-CoV-2 inhibition was only observed at the highest concentration tested. Label-free quantification (LFQ) and intensity based absolute quantification (iBAQ) of identified proteins revealed a clear difference between MFGM-enriched whey and its controls including enrichment of known MFGM proteins and non-MFGM proteins that are enriched simultaneously, some of which have previously been demonstrated to display anti-viral activity. Although not completely absent from other whey protein preparations, MFGM-enriched whey had the highest specific and total phospholipid levels.

Conclusion

MFGM-enriched whey displayed antiviral activity against multiple viruses of clinical importance. This study provides insights into the active components in MFGM-enriched whey and may contribute to previous clinical observations with MFGM-enriched formula demonstrating reduced respiratory and gastrointestinal infections in formula fed infants.

The Multifaceted Roles of Bovine Lactoferrin: Molecular Structure, Isolation Methods, Analytical Characteristics, and Biological Properties

Bovine lactoferrin (bLF) is widely known as an iron-binding glycoprotein from the transferrin family. The bLF molecule exhibits a broad spectrum of biological activity, including iron delivery, antimicrobial, antiviral, immunomodulatory, antioxidant, antitumor, and prebiotic functions, thereby making it one of the most valuable representatives for biomedical applications. Remarkably, LF functionality might completely differ in dependence on the iron saturation state and glycosylation patterns. Recently, a violently growing demand for bLF production has been observed, mostly for infant formulas, dietary supplements, and functional food formulations. Unfortunately, one of the reasons that inhibit the development of the bLF market and widespread protein implementation is related to its negligible amount in both major sources─colostrum and mature milk. This study provides a comprehensive overview of the significance of bLF research by delineating the key structural characteristics of the protein and elucidating their impact on its physicochemical and biological properties. Progress in the development of optimal isolation techniques for bLF is critically assessed, alongside the challenges that arise during its production. Furthermore, this paper presents a curated list of the most relevant instrumental techniques for the characterization of bLF. Lastly, it discusses the prospective applications and future directions for bLF-based formulations, highlighting their potential in various fields.

Sigma Receptor Ligands Prevent COVID Mortality In Vivo: Implications for Future Therapeutics

The emergence of lethal coronaviruses follows a periodic pattern which suggests a recurring cycle of outbreaks. It remains uncertain as to when the next lethal coronavirus will emerge, though its eventual emergence appears to be inevitable. New mutations in evolving SARS-CoV-2 variants have provided resistance to current antiviral drugs, monoclonal antibodies, and vaccines, reducing their therapeutic efficacy. This underscores the urgent need to investigate alternative therapeutic approaches. Sigma receptors have been unexpectedly linked to the SARS-CoV-2 life cycle due to the direct antiviral effect of their ligands. Coronavirus-induced cell stress facilitates the formation of an ER-derived complex conducive to its replication. Sigma receptor ligands are believed to prevent the formation of this complex. Repurposing FDA-approved drugs for COVID-19 offers a timely and cost-efficient strategy to find treatments with established safety profiles. Notably, diphenhydramine, a sigma receptor ligand, is thought to counteract the virus by inhibiting the creation of ER-derived replication vesicles. Furthermore, lactoferrin, a well-characterized immunomodulatory protein, has shown antiviral efficacy against SARS-CoV-2 both in laboratory settings and in living organisms. In the present study, we aimed to explore the impact of sigma receptor ligands on SARS-CoV-2-induced mortality in ACE2-transgenic mice. We assessed the effects of an investigational antiviral drug combination comprising a sigma receptor ligand and an immunomodulatory protein. Mice treated with sigma-2 receptor ligands or diphenhydramine and lactoferrin exhibited improved survival rates and rapid rebound in mass following the SARS-CoV-2 challenge compared to mock-treated animals. Clinical translation of these findings may support the discovery of new treatment and research strategies for SARS-CoV-2.

Biomedical and Nutritional Applications of Lactoferrin

Lactoferrin (Lf) is a glycoprotein belonging to the transferrin family, which can be found in mammalian milk. It was first isolated from bovine milk in the 1930s, and later in the 1960s, it was determined from human milk. This multifunctional protein has the specific ability to bind iron. It plays various biological roles, such as antibacterial, antiviral, antifungal, anti-tumour, anti-obesity, antioxidant, anti-inflammatory and immunomodulatory activities. There are several studies describing its use against in various cancer cell lines (e.g., liver, lung and breast) and the glycoprotein has even been reported to inhibit the development of experimental metastases in mice. Previous studies also suggest Lf-mediated neuroprotection against age-related neurodegenerative diseases and it is also expected to attenuate aging. More recently, Lf has been proposed as a potential approach in COVID-19 prophylaxis. In this review, we discuss the recent developments about the biological activities of this pleiotropic glycoprotein that will reason the exploitation of its biomedical and supplementary nutritional value.