A high-throughput method for the quantification of iron saturation in lactoferrin preparations

Quantitative Evaluation of Iron-Containing Proteins Bound to Mesoporous Silica Microspheres by Inductively Coupled Plasma Mass Spectrometry and Confocal Laser Raman Microscopy

Inductively coupled plasma mass spectrometry (ICP-MS) is important in the biological and biochemical fields as it can quantify trace elements. Confocal laser Raman microscopy (CLRM), a powerful tool for the compositional analysis of biological samples, organic materials, and inorganic materials, can be used to analyze samples in aqueous solutions. Despite their analytical strength, the quantitative evaluation of proteins bound to mesoporous silica (SiO2) microspheres, which are promising candidates for drug delivery systems and vaccine carriers, has not been sufficiently explored. Therefore, we investigated the applicability of ICP-MS and CLRM to quantify lactoferrin (LF), a widely studied iron-containing protein bound to mesoporous SiO2 microspheres (SBA24). The bound LF amount was measured using ICP-MS, selectively monitoring iron derived from LF as a marker element, and CLRM. The results were compared with those obtained using a conventional bulk analysis technique. The amounts and trends of the signal intensities obtained using ICP-MS and CLRM agreed with each other and with the bulk analysis results. Our findings demonstrate that ICP-MS and CLRM are applicable for the quantitative evaluation of iron-containing proteins bound to SBA24. These methods offer a reliable platform for the quantification of biomolecules on microparticles and provide valuable insights for biomedical research and quality control in related industries.

Iron saturation and binding capacity of lactoferrin - development and validation of a colorimetric protocol for quality control

Among the numerous biofunctional properties of lactoferrin, its ability to bind iron ions can be considered a core function. The saturation level with ferric iron affects the stability and functionality of the protein. To reliably quantify the iron saturation, an assay based on the color reagent Ferrozine was developed and validated concerning the lower detection (0.023 μg mL-1) and quantification limits (0.069 μg mL-1), as well as precision, recovery and accuracy values. The established assay was used to monitor iron uptake, comparing two commercially available bovine lactoferrin powders. Significant differences between the samples were observed. One sample exhibited nearly ideal binding behavior with a high affinity for ferric iron (saturation > 98 %), while the comparison sample did not exceed saturation values >80 %. This finding underscores the importance of assessing the iron status and binding capacity for the quality evaluation of lactoferrin products.

Structure and function of fermentation-derived bovine lactoferrin produced from Komagataella phaffii

Bovine lactoferrin (bLf) confers significant functional benefits for human health, but low concentrations in milk and high cost of commercial production limit availability and thus product application. Precision fermentation offers a solution to increase availability of biosimilar recombinant bLf (rbLf) thereby opening new opportunities for this high-value ingredient. To comply with regulatory requirements, we aimed to establish that rbLf from Komagataella phaffii is substantially similar to native bLf in structure and key functions. Intact mass analysis showed a molecular weight of 84 kDa for rbLf, comparable to 82-83 kDa of bLf. LC-MS N-linked glycan profiling revealed predominantly high-mannose-based glycans on rbLf, similar to ∼50% of bLf glycans. The isoelectric point and core amino acid sequence of rbLf and bLf are identical. rbLf retains the functional ability to bind and release iron, bind to intestinal Lf receptors, increase epithelial cell growth (>120% of control, P < 0.0001), reduce enteropathogenic Escherichia coli growth (>50% reduction, P < 0.0001), bind lipopolysaccharide (LPS) (+4-fold, P < 0.001), and antagonize LPS-induced toll-like receptor 4 activity (>40% reduction, P < 0.0001). These results demonstrate similarity of rbLf in structure and function to native bLf, supporting the effective application for expanded market opportunities for infant and adult health.

Determination of Lactoferrin Using High-Frequency Piezoelectric Quartz Aptamer Biosensor Based on Molecular Bond Rupture

In this study, an aptamer biosensor for detecting lactoferrin (LF) was developed using piezoelectric quartz-induced bond rupture sensing technology. The thiol-modified aptamer I was immobilized on the gold electrode surface of the quartz crystal microbalance (QCM) through an Au-S bond to specifically bind LF. It was then combined with aptamer-magnetic beads to amplify the mass signal. The peak excitation voltage was 8 V at the resonance frequency for the 60 MHz gold-plated quartz crystal. When the molecular bond cracking process occurred, the aptamer-magnetic beads combined on the surface of the piezoelectric quartz were removed, which resulted in an increase in quartz crystal resonance frequency. Therefore, the specific detection of LF can be realized. Under optimized experimental conditions, the linear range for LF was 10-500 ng/mL, the detection limit (3σ) was 8.2 ng/mL, and the sample recoveries for actual milk powder samples ranged from 97.2% to 106.0%. Compared with conventional QCM sensing technology, the signal acquisition process of this sensing method is simple, fast, and easy to operate.

The [(bathophenanthroline)3:Fe2+] complex as an aromatic non-polymeric medium for purification of human lactoferrin

We describe a non-chromatographic, ligand-free platform for the efficient purification of recombinant human lactoferrin (LF). The platform consists of a [metal:chelator] complex precipitate in the presence of osmotically active polyethylene glycol 6000 (PEG-6000). Purification is achieved in three stages. Following formation of the complex, LF is captured under neutral conditions by the aggregated complexes (Step I), a washing step follows (Step II) and then, (Step III) LF is extracted in pure form with 100 mM tribasic Na citrate buffer (pH 7). Of the four complexes investigated, [bathophenanthroline (batho)3:Fe2+] was determined to be the most efficient. LF is recovered with high yield (∼90%, by densitometry) and purity (≥97%, by SDS polyacrylamide gel electrophoresis (SDS-PAGE)) from an artificial contamination background comprising E. coli lysate proteins. Purified LF is demonstrated to be monomeric by dynamic light scattering (DLS); to preserve its native secondary structure by circular dichroism (CD) spectroscopy; and, as apo-LF, to efficiently inhibit bacterial growth. Process yield is not affected by a 45-fold increase in LF concentration from 0.2 to 9 mg/mL. We provide evidence that protein capture relies on [cation:π] interactions between the lysine and arginine residues of LF with the fully aromatic [(batho)3:Fe2+] complexes. The use of [metal:chelator] complex aggregates is demonstrated to provide an economical and efficient avenue for LF purification.

Impact of Ultrafiltration on the Physicochemical Properties of Bovine Lactoferrin: Insights into Molecular Mass, Surface Morphology, and Elemental Composition

The large-scale isolation of bovine lactoferrin (bLF) typically involves using large amounts of concentrated eluents, which might introduce impurities to the final product. Sometimes, protein pre-concentration is required for the greater accuracy of experimental results. In this research, the supplied bLF sample was subjected to additional ultrafiltration (UF) to eliminate possible small impurities, such as salts and peptides of bLF. Beforehand, the basic characterization of native bLF, including surface-charge properties and the structural sensitivity to the various pH conditions, was performed. The study aimed to evaluate the difference in molecular mass, primary structure, surface morphology, and elemental composition of the protein before and after UF. The research was provided by application of spectroscopic, spectrometric, electrophoretic, and microscopic techniques. The evident changes in the surface morphology of bLF were observed after UF, while the molecular masses of both proteins were comparable. According to MALDI-TOF/MS results, UF had a positive impact on the bLF sample representation, improving the identification parameters, such as sequence coverage and intensity coverage.

Harnessing the Power of a Novel Triple Chelate Complex in Fermented Probiotic Dairy Products: A Promising Solution for Combating Iron Deficiency Anemia

This study discovered and examined novel triple chelate complexes involving iron, ascorbic acid, and essential amino acids (AsA-Fe-AmA triple chelate complexes) for the first time. The mechanism of complex formation was studied using FTIR spectroscopy and quantum chemical modeling. The produced complexes were shown to be suitable for fortifying food items with a pH of 3-7 that have not been exposed to heat treatment at temperatures over 75 °C for more than 15 min. Thus, it can be said that the concentration for milk fortification should be 0.005 mol/L or less. In vivo experiments in rats models revealed that the synthesized complexes increased serum iron levels after a single application to reference values within 24 h of oral administration. The iron level increased by 14.0 mmol/L at 2 mL dose of the complex. This fact makes it possible to consider the use of developed complexes and developed fermented dairy products for the prevention of iron deficiency and iron deficiency anemia. Research on the effect of discovered compounds on the physicochemical and organoleptic qualities of milk was conducted. Furthermore, iron ascorbate threoninate, iron ascorbate methioninate, iron ascorbate lysinate, and iron ascorbate tryptophanate all had a beneficial effect on Lacticaseibacillus rhamnosus at concentrations as low as 0.0005 mol/L, which is significant for milk fermentation. A study of fermented milk products revealed that the most effective AsA-Fe-AmA triple chelate complex is iron ascorbate lysinate, which might be further investigated as a viable molecule for dietary fortification in iron deficiency anemia. It was found that fortified fermented milk products had a titratable acidity of 67 ± 1°T, pH of 4.38 ± 0.05, and a viscosity of 2018 ± 142 Pa·s.

A high-throughput differential scanning fluorimetry method for rapid detection of thermal stability and iron saturation in lactoferrin

Thermal stability and iron saturation of lactoferrin (LF) are of great significance not only for the evaluation of the biological activities of LF but also for the optimization of the isolation and drying process parameters. Differential scanning calorimetry (DSC) is a well-established and efficient method for thermal stability and iron saturation detection in LF. However, multiple DSC measurements are typically performed sequentially, thus time-consuming and low throughput. Herein, we introduced the differential scanning fluorimetry (DSF) approach to overcome such limitations. The DSF can monitor LF thermal unfolding with a commonly available real-time PCR instrument and a fluorescent dye (SYPRO orange or Glomelt), and the measured melting temperature of LF is consistent with that determined by DSC. On the basis of that, a new quantification method was established for determination of iron saturation levels using the linear correlation of the degree of ion saturation of LF with DSF measurements. Such DSF method is simple, inexpensive, rapid (<15 min), and high throughput (>96 samples per experiment), and provides a valuable alternative tool for thermal stability detection of LF and other whey proteins.

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.

Encapsulation of Iron-Saturated Lactoferrin for Proteolysis Protection with Preserving Iron Coordination and Sustained Release

Lactoferrin (Lf) is a globular glycoprotein found mainly in milk. It has a very high affinity for iron(III) ions, and its fully saturated form is called holoLf. The antimicrobial, antiviral, anticancer, and immunomodulatory properties of Lf have been studied extensively for the past two decades. However, to demonstrate therapeutic benefits, Lf has to be efficiently delivered to the intestinal tract in its structurally intact form. This work aimed to optimize the encapsulation of holoLf in a system based on the versatile Eudragit® RS polymer to protect Lf against the proteolytic environment of the stomach. Microparticles (MPs) with entrapped holoLf were obtained with satisfactory entrapment efficiency (90-95%), high loading capacity (9.7%), and suitable morphology (spherical without cracks or pores). Detailed studies of the Lf release from the MPs under conditions that included simulated gastric or intestinal fluids, prepared according to the 10th edition of the European Pharmacopeia, showed that MPs partially protected holoLf against enzymatic digestion and ionic iron release. The preincubation of MPs loaded with holoLf under conditions simulating the stomach environment resulted in the release of 40% of Lf from the MPs. The protein released was saturated with iron ions at 33%, was structurally intact, and its iron scavenging properties were preserved.

Time to Kill and Time to Heal: The Multifaceted Role of Lactoferrin and Lactoferricin in Host Defense

Lactoferrin is an iron-binding glycoprotein present in most human exocrine fluids, particularly breast milk. Lactoferrin is also released from neutrophil granules, and its concentration increases rapidly at the site of inflammation. Immune cells of both the innate and the adaptive immune system express receptors for lactoferrin to modulate their functions in response to it. On the basis of these interactions, lactoferrin plays many roles in host defense, ranging from augmenting or calming inflammatory pathways to direct killing of pathogens. Complex biological activities of lactoferrin are determined by its ability to sequester iron and by its highly basic N-terminus, via which lactoferrin binds to a plethora of negatively charged surfaces of microorganisms and viruses, as well as to mammalian cells, both normal and cancerous. Proteolytic cleavage of lactoferrin in the digestive tract generates smaller peptides, such as N-terminally derived lactoferricin. Lactoferricin shares some of the properties of lactoferrin, but also exhibits unique characteristics and functions. In this review, we discuss the structure, functions, and potential therapeutic uses of lactoferrin, lactoferricin, and other lactoferrin-derived bioactive peptides in treating various infections and inflammatory conditions. Furthermore, we summarize clinical trials examining the effect of lactoferrin supplementation in disease treatment, with a special focus on its potential use in treating COVID-19.

Early-Life Intervention of Lactoferrin and Probiotic in Suckling Piglets: Effects on Immunoglobulins, Intestinal Integrity, and Neonatal Mortality

The aim of this study was to determine the effects of early-life bovine lactoferrin and host specific probiotic interventions on growth performance, mortality, and concentrations of immunoglobulin A and immunoglobulin G and transforming growth factor beta 1 (a marker of intestinal integrity) in serum of neonatal piglets. A total of eight piglet litters from parity matched sows were randomly divided into four groups and assigned to one of the four interventions: control (sterile normal saline), bovine lactoferrin (100 mg bovine lactoferrin), probiotic (1 × 109 colony forming unit (cfu) of swine origin Pediococcus acidilactici FT28 probiotic), and bovine lactoferrin + probiotic (100 mg bovine lactoferrin and 1 × 109 CFU of P. acidilactici FT28 probiotic). All the interventions were given once daily through oral route for first 7 days of life. The average daily gain (p = 0.0004) and weaning weight (p < 0.0001) were significantly improved in the probiotic group. The piglet survivability was significantly higher in bovine lactoferrin and probiotic groups than control group in Log-rank (Mantel-Cox) test. The concentrations of immunoglobulin A on day 21 in bovine lactoferrin, probiotic, and bovine lactoferrin + probiotic groups increased significantly (p < 0.05). Immunoglobulin G concentrations on day 7 and 15 in bovine lactoferrin and bovine lactoferrin + probiotic groups and on day 15 in probiotic group were significantly (p < 0.05) elevated, whereas, the concentration of transforming growth factor-β1 was significantly (p < 0.05) increased from day 7 to 21 in all the supplemented groups. In conclusion, the early-life bovine lactoferrin and P. acidilactici FT28 probiotic interventions reduced the mortality in the suckling piglets by promoting the systemic immunity and enhancing the intestinal integrity.

Lactoferrin Decreases Enterotoxigenic Escherichia coli-Induced Fluid Secretion and Bacterial Adhesion in the Porcine Small Intestine

Enterotoxigenic Escherichia coli (ETEC) infections are one of the most prevalent causes of post-weaning diarrhea in piglets, resulting in morbidity, mortality and elevated use of antibiotics. The emergence and further spread of antimicrobial resistance together with the growing demand for high quality animal protein requires the identification of novel alternatives for antimicrobials. A promising alternative is lactoferrin, as we previously showed that it can both inhibit the growth and degrade bacterial virulence factors of porcine ETEC strains in vitro. Aiming to confirm these findings in vivo, we performed a small intestinal segment perfusion experiment in piglets. Here, we showed that lactoferrin could not only decrease ETEC-induced fluid secretion, but also their ability to colonize the small intestinal epithelium. Furthermore, while ETEC infection induced pro-inflammatory cytokine mRNA expression in this experiment, lactoferrin was not able to counteract these responses. In addition, a bacterial motility assay showed that lactoferrin can reduce the motility of ETEC. Our findings further support the use of lactoferrin as an alternative for antimicrobials and also show its potential for the prevention of ETEC infections in pigs.

Synthesis and physicochemical characterization of bovine lactoferrin supersaturated complex with iron (III) ions

The aim of the study was to investigate the process of Fe³⁺ binding to bLTF. Moreover, the physicochemical characterization of the respective supersaturated complex was studied. The knowledge should be important for the description of processes that may take place in dairy products fortified with iron. Additionally, the synthesized complex can be utilized as a dietary supplement for the treatment of iron deficiency anemia (IDA). Finally, it was shown that formation of supersaturated iron-protein structures which include LTF often accompanies development of neurodegenerative diseases such as Alzheimer or Parkinson. Thus, the study can reveal some aspects of its pathogenesis process. The methodology of the investigation comprised the utilization of batch sorption study and applying Freundlich and Langmuir models. The complex also was characterized by numerous techniques: spectrometric (ICP-MS), spectroscopic (UV–Vis, ATR-FTIR), electron microscopy (TEM–EDX), SDS-PAGE. Based on obtained results the potential mechanisms of iron interaction with protein were described. Moreover, the molecular docking was applied to visualize possible metal binding sites. The respective complex contains ≈ 33.0 mg/g of iron which is nearly 50 Fe³⁺ per one protein molecule. The cytotoxicity of the obtained complex was evaluated by MTT reduction and LDH release assays on Caco-2 and nL929 cell lines.

Lactoferrin and its nano-formulations in rare eye diseases

Lactoferrin (LF) is an iron-binding glycoprotein released from mucous secreting cells and neutrophils. LF can be used in a broad range of eye diseases related to the retina, cornea, and optic nerve. The retina is particularly affected by oxidative stress inside the photoreceptor being constantly exposed to light which induces accumulation of reactive oxygen species (ROS) in the retinal pigmented epithelium (RPE) causing damage to photoreceptor recycling. Retinitis pigmentosa (RP) and macular degeneration are inherited retinopathies that consist of different disease-causing genes, that cause mutations with highly varied clinical consequences. Age-related macular degeneration is a chronic disease of the retina and one of the major causes of sight loss. This review provides an application of lactoferrin and LF-based nano-formulations or nanoparticles in the field of retinal diseases or corneal diseases such as retinitis pigmentosa, retinoblastoma, age-related macular degeneration (AMD), keratoconus and uveitis. Several studies have found that lactoferrin's antibacterial activity is not limited to its iron sequestration, but also its ability as a nanoparticle that acts as a carrier to deliver drugs by crossing the blood-retina barrier (BRB) and its involvement in cell cycle control, which is not possible by many transferrin proteins.

Characterization of proteolytic degradation products of vaginally administered bovine lactoferrin

When bovine lactoferrin (bLF) contacts human vaginal fluid (VF) it is subjected to proteolytic degradation. This report describes fragmentation patterns of bLF dosed vaginally in clinical trials or incubated ex vivo with VF. A consensus pattern of fragments was observed in samples from different women. The 80 kDa bLF molecule is initially cleaved between its homologous 40 kDa domains, the N-lobe and C-lobe, and then degraded into sub-fragments and mixtures of small peptides. We characterized this fragmentation process by polyacrylamide gel electrophoresis, western blotting, chromatographic separation, and mass spectral sequence analysis. Common to most VF fragmentation patterns were large amounts of an N-lobe 37 kDa fragment and a C-lobe 43 kDa fragment resulting from a single cleavage following tyrosine 324. Both fragments possessed full sets of iron-ligand amino acids and retained iron-binding ability. In some VF samples, alternative forms of large fragments were found, which like the 37+43 kDa pair, totaled 80 kDa. These included 58+22 kDa, 18+62 kDa, and 16+64 kDa forms. In general, the smaller component was from the N-lobe and the larger from the C-lobe. The 18+62 kDa pair was absent in some VF samples but highly abundant in others. This variability suggests multiple endopeptidases are involved, with the 18 kDa fragment’s presence dependent upon the balance of enzymes. Further action of VF endopeptidases produced smaller peptide fragments, and we found evidence that exopeptidases trimmed their N- and C-termini. The 3.1 kDa antimicrobial peptide lactoferricin B was not detected. These studies were facilitated by a novel technique we developed: tricolor western blots, which enabled simultaneous visualization of N- and C-terminal epitopes.

The Multi-Component Causes of Late Neonatal Sepsis-Can We Regulate Them?

Elucidating the mechanisms of bacterial translocation is crucial for the prevention and treatment of neonatal sepsis. In the present study, we aimed to evaluate the potential of lactoferrin to inhibit the development of late-onset blood infection in neonates. Our investigation evaluates the role of key stress factors leading to the translocation of intestinal bacteria into the bloodstream and, consequently, the development of life-threatening sepsis. Three stress factors, namely weaning, intraperitoneal administration of Gram-positive cocci and oral intake of Gram-negative rods, were found to act synergistically. We developed a novel model of rat pups sepsis induced by bacterial translocation and observed the inhibition of this process by supplementation of various forms of lactoferrin: iron-depleted (apolactoferrin), iron-saturated (hololactoferrin) and manganese-saturated lactoferrin. Additionally, lactoferrin saturated with manganese significantly increases the Lactobacillus bacterial population, which contributes to the fortification of the intestinal barrier and inhibits the translocation phenomenon. The acquired knowledge can be used to limit the development of sepsis in newborns in hospital neonatal intensive care units.

A Peptide Bond from the Inter-lobe Segment in the Bilobal Lactoferrin Acts as a Preferred Site for Cleavage for Serine Proteases to Generate the Perfect C-lobe: Structure of the Pepsin Hydrolyzed Lactoferrin C-lobe at 2.28 Å Resolution

C-lobe represents the C-terminal half of lactoferrin which is a bilobal 80 kDa iron binding glycoprotein. The two lobes are designated as N-lobe (Ser1-Glu333) and C-lobe (Arg344-Arg689). The N- and C-lobes are connected by a 10-residue long α-helical peptide (Thr334-Thr343). Both lobes adopt similar conformations and have identical iron binding sites. The bilobal lactoferrin was hydrolyzed in a limited proteolysis using pepsin at pH 2.0. It produced a 40 kDa and fully functional C-lobe which was purified and crystallized at pH 8.0. The structure determination revealed that the structure contained residues from Tyr342 to Arg689 representing a fully functional monoferric C-lobe. It showed that pepsin cleaved lactoferrin at the peptide bond Arg341-Tyr342 which is part of the inter-lobe decapeptide. Interestingly, the two previously determined structures of the enzymatically produced C-lobe using trypsin and proteinase K also cleaved lactoferrin at the same peptide bond Arg341-Tyr342. This was a striking result as the three enzymes, pepsin, trypsin and proteinase K have different specificity requirements and yet they cleaved the bilobal lactoferrin at the same peptide bond and generated an identical and fully functional C-lobe. This shows that the observed cleavage site in lactoferrin adopts a highly favourable conformation for proteolysis. It is noteworthy that the three enzymes with different specificities cut the protein at the same peptide bond which may be of physiological significance because the antibacterial action of lactoferrin is extended further through the C-lobe.

Influence of iron binding in the structural stability and cellular internalization of bovine lactoferrin

Lactoferrin (Lf) is an iron-binding glycoprotein and a component of many external secretions with a wide diversity of functions. Structural studies are important to understand the mechanisms employed by Lf to exert so varied functions. Here, we used guanidine hydrochloride and high hydrostatic pressure to cause perturbations in the structure of bovine Lf (bLf) in apo and holo (unsaturated and iron-saturated, respectively) forms, and analyzed conformational changes by intrinsic and extrinsic fluorescence spectroscopy. Our results showed that the iron binding promotes changes on tertiary structure of bLf and increases its structural stability. In addition, we evaluated the effects of bLf structural change on the kinetics of bLf internalization in Vero cells by confocal fluorescence microscopy, and observed that the holo form was faster than the apo form. This finding may indicate that structural changes promoted by iron binding may play a key role in the intracellular traffic of bLf. Altogether, our data improve the comprehension of bLf stability and uptake, adding knowledge to its potential use as a biopharmaceutical.

Lactoferrin and Its Detection Methods: A Review

Lactoferrin (LF) is one of the major functional proteins in maintaining human health due to its antioxidant, antibacterial, antiviral, and anti-inflammatory activities. Abnormal levels of LF in the human body are related to some serious diseases, such as inflammatory bowel disease, Alzheimer’s disease and dry eye disease. Recent studies indicate that LF can be used as a biomarker for diagnosis of these diseases. Many methods have been developed to detect the level of LF. In this review, the biofunctions of LF and its potential to work as a biomarker are introduced. In addition, the current methods of detecting lactoferrin have been presented and discussed. We hope that this review will inspire efforts in the development of new sensing systems for LF detection.

Surface-reacted calcium carbonate microparticles as templates for lactoferrin encapsulation

Microencapsulation helps to improve bioavailability of a functional whey protein, lactoferrin (Lf), in adults. Herein, we report the Lf loading capacity (LC) and retention efficiency (RE) in the microparticles of surface-reacted calcium carbonate (SRCC) of different types and compare them to those of widely used vaterite microparticles. The LCs and REs are analyzed in connection to the total surface area and the volume of intraparticle pores. The best performing SRCC3 demonstrates Lf LC of 11.00 wt% achieved in a single absorption step and 74% RE after two cycles of washing with deionized water. A much larger surface area of SRCC templates and a lower pH required to release Lf do not affect its antitumor activity in MCF-7 assay. Layer-by-Layer assembly of pepsin-tannic acid multilayer shell around Lf-loaded microparticles followed by acidic decomposition of the inorganic core produces microencapsulated Lf with a yield ~36 times higher than from vaterite templates reported earlier, while the scale of encapsulated Lf production is ~12,000 times larger. In vitro digestion tests demonstrate the protection of ~65% of encapsulated Lf from gastric digestion. The developed capsules are prospective candidates for functional foods fortified with Lf.

Lactoferrin as a regenerative agent: The old-new panacea?

Lactoferrin (Lf) possesses various biological properties and therapeutic potentials being a perspective anti-inflammatory, antibacterial, antiviral, antioxidant, antitumor, and immunomodulatory agent. A significant body of literature has also demonstrated that Lf modulates regenerative processes in different anatomical structures, such as bone, cartilage, skin, mucosa, cornea, tendon, vasculature, and adipose tissue. Hence, this review collected and analyzed the data on the regenerative effects of Lf, as well as paid specific attention to their molecular basis. Furthermore, tissue and condition-specific activities of different Lf types as well as problems of their delivery to the targeted organs were discussed. The authors strongly hope that this review will stimulate researchers to focus on the highlighted topics thus accelerating the progress of Lf's wider clinical application.

Iron Absorption is Greater from Apo-Lactoferrin and is Similar Between Holo-Lactoferrin and Ferrous Sulfate: Stable Iron Isotope Studies in Kenyan Infants

BACKGROUND

Whether lactoferrin (Lf) binds iron to facilitate its absorption or to sequester iron from potential enteropathogens remains uncertain. Bovine Lf is added to many infant formulas, but previous studies in infants reported that Lf had no effect on or inhibited iron absorption. The effects of the apo (iron-free) or the holo (iron-loaded) forms of Lf on iron absorption are unclear.

OBJECTIVES

Our objective was to compare iron absorption from a maize-based porridge containing: 1) labeled ferrous sulfate (FeSO4) alone; 2) labeled FeSO4 given with bovine apo-Lf; and 3) intrinsically labeled bovine holo-Lf.

METHODS

In a crossover study, we measured iron absorption in Kenyan infants (n = 25; mean ± SD age 4.2 ± 0.9 months; mean ± SD hemoglobin 109 ± 11 g/L) from maize-based test meals containing: 1) 1.5 mg of iron as 54Fe-labeled FeSO4; 2) 1.42 mg of iron as 58Fe-labeled FeSO4, given with 1.41 g apo-Lf (containing 0.08 mg iron); and 3) 1.41 g holo-Lf carrying 1.5 mg iron as 57Fe. The iron saturation levels of apo- and holo-Lf were 0.56% and 47.26%, respectively primary outcome was fractional iron absorption (FIA), assessed by erythrocyte incorporation of isotopic labels.

RESULTS

The FIA from the meal containing apo-Lf + FeSO4 (geometric mean, 9.8%; -SD and +SD, 5.4% and 17.5%) was higher than from the meals containing FeSO4 (geometric mean, 6.3%; -SD and +SD, 3.2% and 12.6%; P = 0.002) or holo-Lf (geometric mean, 5.0%; -SD and +SD, 2.8% and 8.9%; P <0.0001). There was no significant difference in FIA when comparing the meals containing holo-Lf versus FeSO4 alone (P = 0.24).

CONCLUSIONS

The amount of iron absorbed from holo-Lf was comparable to that of FeSO4, and the addition of apo-Lf to a test meal containing FeSO4 significantly increased (+56%) iron absorption. These findings suggest that Lf facilitates iron absorption in young infants. Because Lf binds iron with high affinity, it could be a safe way to provide iron to infants in low-income countries, where iron fortificants can adversely affect the gut microbiome and cause diarrhea. This study was registered at clinicaltrials.gov as NCT03617575.

Porcine and Bovine Forms of Lactoferrin Inhibit Growth of Porcine Enterotoxigenic Escherichia coli and Degrade Its Virulence Factors

Postweaning diarrhea (PWD) is an economically important, multifactorial disease affecting pigs within the first 2 weeks after weaning. The most common agent associated with PWD is enterotoxigenic Escherichia coli (ETEC). Currently, antibiotics are used to control PWD, and this has most likely contributed to an increased prevalence of antibiotic-resistant strains. This puts pressure on veterinarians and farmers to decrease or even abandon the use of antibiotics, but these measures need to be supported by alternative strategies for controlling these infections. Naturally derived molecules, such as lactoferrin, could be potential candidates due to their antibacterial or immune-modulating activities. Here, we analyzed the ability of bovine lactoferrin (bLF), porcine lactoferrin (pLF), and ovotransferrin (ovoTF) to inhibit ETEC growth, degrade ETEC virulence factors, and inhibit adherence of these pathogens to porcine intestinal epithelial cells. Our results revealed that bLF and pLF, but not ovoTF, inhibit the growth of ETEC. Furthermore, bLF and pLF can degrade several virulence factors produced by ETEC strains, more specifically F4 fimbriae, F18 fimbriae, and flagellin. On the other hand, ovoTF degrades F18 fimbriae and flagellin but not F4 fimbriae. An in vitro adhesion assay showed that bLF, ovoTF, and pLF can decrease the number of bacteria adherent to epithelial cells. Our findings demonstrate that lactoferrin can directly affect porcine ETEC strains, which could allow lactoferrin to serve as an alternative to antimicrobials for the prevention of ETEC infections in piglets.IMPORTANCE Currently, postweaning F4⁺ and F18⁺ Escherichia coli infections in piglets are controlled by the use of antibiotics and zinc oxide, but the use of these antimicrobial agents most likely contributes to an increase in antibiotic resistance. Our work demonstrates that bovine and porcine lactoferrin can inhibit the growth of porcine enterotoxigenic E. coli strains. In addition, we also show that lactoferrin can reduce the adherence of these strains to small intestinal epithelial cells, even at a concentration that does not inhibit bacterial growth. This research could allow us to develop lactoferrin as an alternative strategy to prevent enterotoxigenic E. coli (ETEC) infections in piglets.

Lactoferrin Metal Saturation-Which Form Is the Best for Neonatal Nutrition?

We evaluated the impact of metal saturation of lactoferrin (with iron and manganese) on population numbers of pathogenic species relevant for neonatal sepsis that commonly originates from the gut due to bacterial translocation. Little attention has been paid to how metal ions bound to the protein affect its activity. Several reference and clinical strains as well as probiotic strains were incubated with different forms of lactoferrin: metal-depleted (apolactoferrin), iron-saturated (hololactoferrin) and manganese-saturated lactoferrin. We also attempted to confirm the observed effects of lactoferrin forms in vivo using rat pups. The observed decrease in population numbers of Gram-negative rods could not be confirmed by quantitative plating—lactoferrin may regulate these populations diversely (e.g., by anti-biofilm activity) and contribute to the inhibition of inflammatory response. We did not see any effect of lactoferrin forms on staphylococci and bifidobacteria. However, we have noted a significant increase of population numbers of Lactobacillus strains upon incubation with manganese-saturated lactoferrin. These results were confirmed in vivo in a rat model. Metal saturation is an underestimated factor regulating lactoferrin activity. Some forms are more potent in the inhibition of pathogenic species while others, such as manganese-saturated lactoferrin, could contribute to the restoration of gut homeostasis.

Lactoferrin is a dynamic protein in human melioidosis and is a TLR4-dependent driver of TNF-α release in Burkholderia thailandensis infection in vitro

Melioidosis is an often-severe tropical infection caused by Burkholderia pseudomallei (Bp) with high associated morbidity and mortality. Burkholderia thailandensis (Bt) is a closely related surrogate that does not require BSL-3 conditions for study. Lactoferrin is an iron-binding glycoprotein that can modulate the innate inflammatory response. Here we investigated the impact of lactoferrin on the host immune response in melioidosis. Lactoferrin concentrations were measured in plasma from patients with melioidosis and following ex vivo stimulation of blood from healthy individuals. Bt growth was quantified in liquid media in the presence of purified and recombinant human lactoferrin. Differentiated THP-1 cells and human blood monocytes were infected with Bt in the presence of purified and recombinant human lactoferrin, and bacterial intracellular replication and cytokine responses (tumor necrosis factor-α (TNF-α), interleukin-1β and interferon-γ) were measured. In a cohort of 49 melioidosis patients, non-survivors to 28 days had significantly higher plasma lactoferrin concentrations compared to survivors (median (interquartile range (IQR)): 326 ng/ml (230-748) vs 144 ng/ml (99-277), p<0.001). In blood stimulated with heat-killed Bp, plasma lactoferrin concentration significantly increased compared to unstimulated blood (median (IQR): 424 ng/ml (349-479) vs 130 ng/ml (91-214), respectively; p<0.001). Neither purified nor recombinant human lactoferrin impaired growth of Bt in media. Lactoferrin significantly increased TNF-α production by differentiated THP-1 cells and blood monocytes after Bt infection. This phenotype was largely abrogated when Toll-like receptor 4 (TLR4) was blocked with a monoclonal antibody. In sum, lactoferrin is produced by blood cells after exposure to Bp and lactoferrin concentrations are higher in 28-day survivors in melioidosis. Lactoferrin induces proinflammatory cytokine production after Bt infection that may be TLR4 dependent.

Lactoferrin Is Broadly Active against Yeasts and Highly Synergistic with Amphotericin B

Lactoferrin (LF) is a multifunctional milk protein with antimicrobial activity against a range of pathogens. While numerous studies report that LF is active against fungi, there are considerable differences in the level of antifungal activity and the capacity of LF to interact with other drugs. Here we undertook a comprehensive evaluation of the antifungal spectrum of activity of three defined sources of LF across 22 yeast and 24 mold species and assessed its interactions with six widely used antifungal drugs. LF was broadly and consistently active against all yeast species tested (MICs, 8 to 64 μg/ml), with the extent of activity being strongly affected by iron saturation. LF was synergistic with amphotericin B (AMB) against 19 out of 22 yeast species tested, and synergy was unaffected by iron saturation but was affected by the extent of LF digestion. LF-AMB combination therapy significantly prolonged the survival of Galleria mellonella wax moth larvae infected with Candida albicans or Cryptococcus neoformans and decreased the fungal burden 12- to 25-fold. Evidence that LF directly interacts with the fungal cell surface was seen via scanning electron microscopy, which showed pore formation, hyphal thinning, and major cell collapse in response to LF-AMB synergy. Important virulence mechanisms were disrupted by LF-AMB treatment, which significantly prevented biofilms in C. albicans and C. glabrata, inhibited hyphal development in C. albicans, and reduced cell and capsule size and phenotypic diversity in Cryptococcus Our results demonstrate the potential of LF-AMB as an antifungal treatment that is broadly synergistic against important yeast pathogens, with the synergy being attributed to the presence of one or more LF peptides.

Antilisterial activity of dromedary lactoferrin peptic hydrolysates

The aim of this study was to explore the antibacterial peptides derived from dromedary lactoferrin (LFc). The LFc was purified from colostrum using a batch procedure with a cation exchange chromatography support and was hydrolyzed with pepsin to generate peptic digest. This peptic digest was fractionated by cation exchange chromatography, and the antilisterial activity of LFc, peptic digest, and obtained fractions was investigated using the bioscreen method. The growth of Listeria innocua ATCC 33090 and LRGIA 01 strains was not inhibited by LFc and its hydrolysates. Two fractions of dromedary lactoferrin peptic hydrolysate were active against both strains. A tandem mass spectroscopy analysis revealed that the 2 active fractions comprised at least 227 different peptides. Among these peptides, 9 found in the first fraction had at least 50% similarity with 10 known antimicrobial peptides (following sequence alignments with the antimicrobial peptide database from the University of Nebraska Medical Center, Omaha). Whereas 9 of these peptides presented homology with honeybee, frog, or amphibian peptides, the 10th peptide, F₁₅₂SASCVPCVDGKEYPNLCQLCAGTGENKCACSSQEPYFGY₁₉₂ (specifically found in 1 separated fraction), exibited 54% homology with a synthetic antibacterial peptide (AP00481) derived from human lactoferrin named kaliocin-1. Similarly, the second fraction contained 1 peptide similar to lactoferrampin B, an antibacterial peptide derived from bovine milk. This result suggests that peptic hydrolysis of LFc releases more active antimicrobial peptides than their protein source and thus provides an opportunity for their potential use to improve food safety by inhibiting undesirable and spoilage bacteria.

Effects of lactoferrin on neonatal pathogens and Bifidobacterium breve in human breast milk

Supplementation with probiotics in preterm infants reduces necrotizing enterocolitis and sepsis. Bovine lactoferrin is a promising supplement that may further reduce disease burden, but its effects on probiotic bacteria in human breast milk has not been evaluated. We aimed to characterise the antimicrobial activity of bovine and human lactoferrin in human breast milk against probiotics and typical neonatal sepsis pathogens. Lactoferrin levels were determined by enzyme linked immunosorbent assay in fresh and pasteurised human breast milk. The neonatal pathogens Staphylococcus epidermidis and Escherichia coli, and the probiotic Bifidobacterium breve strain M-16V were cultured in human breast milk or infant formula in the presence or absence of clinically relevant doses of bovine or human lactoferrin. Standard microbiological methods were used to determine the effects of lactoferrin on bacterial growth. Unpasteurised human breast milk contained significantly higher lactoferrin levels and resulted in superior inhibition of pathogenic bacterial growth compared to infant formula and pasteurised human breast milk. Human lactoferrin was significantly more effective at inhibiting bacterial growth, when compared to bovine lactoferrin. Supplementation with human lactoferrin or high dose bovine lactoferrin inhibited growth of the probiotic strain B. breve M-16V in pasteurised human breast milk. Although unpasteurised human breast milk and human lactoferrin had the greatest antimicrobial activity against all bacterial species tested, higher doses of bovine lactoferrin also showed activity against B. breve and. S. epidermidis. This study suggests that simultaneous administration of lactoferrins and probiotics may affect colonisation with probiotic bacteria, warranting further investigations.

Lactoferrin is a natural inhibitor of plasminogen activation

The plasminogen system is essential for dissolution of fibrin clots, and in addition, it is involved in a wide variety of other physiological processes, including proteolytic activation of growth factors, cell migration, and removal of protein aggregates. On the other hand, uncontrolled plasminogen activation contributes to many pathological processes (e.g. tumor cells' invasion in cancer progression). Moreover, some virulent bacterial species (e.g. Streptococci or Borrelia) bind human plasminogen and hijack the host's plasminogen system to penetrate tissue barriers. Thus, the conversion of plasminogen to the active serine protease plasmin must be tightly regulated. Here, we show that human lactoferrin, an iron-binding milk glycoprotein, blocks plasminogen activation on the cell surface by direct binding to human plasminogen. We mapped the mutual binding sites to the N-terminal region of lactoferrin, encompassed also in the bioactive peptide lactoferricin, and kringle 5 of plasminogen. Finally, lactoferrin blocked tumor cell invasion in vitro and also plasminogen activation driven by Borrelia Our results explain many diverse biological properties of lactoferrin and also suggest that lactoferrin may be useful as a potential tool for therapeutic interventions to prevent both invasive malignant cells and virulent bacteria from penetrating host tissues.

Lactoferrin promotes murine C2C12 myoblast proliferation and differentiation and myotube hypertrophy

Lactoferrin (Lf) is a multifunctional glycoprotein, which promotes the proliferation of murine C2C12 myoblasts. In the present study, it was investigated how Lf promotes myoblast proliferation and whether Lf promotes myoblast differentiation or induces myotube hypertrophy. Lf promoted the proliferation of myoblasts in a dose-dependent manner. Myoblast proliferation increased on day 3 when myoblasts were cultured in the presence of Lf for three days and also when myoblasts were cultured in the presence of Lf for the first day and in the absence of Lf for the subsequent two days. In addition, Lf induced the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 in myoblasts. The mitogen-activated protein kinase kinase 1/2 inhibitor U0126 inhibited Lf-induced ERK1/2 phosphorylation and repressed Lf-promoted myoblast proliferation. C2C12 myoblasts, myotubes and skeletal muscle expressed low-density lipoprotein receptor-related protein (LRP)1 mRNA and Lf-promoted myoblast proliferation was attenuated by an LRP1 antagonist or LRP1 gene silencing. The knockdown of LRP1 repressed Lf-induced phosphorylation of ERK1/2. Furthermore, when myoblasts were induced to differentiate, Lf increased the expression of the myotube-specific structural protein, myosin heavy chain (MyHC) and promoted myotube formation. Knockdown of LRP1 repressed Lf-induced MyHC expression. Lf also increased myotube size following differentiation. These results indicate that Lf promotes myoblast proliferation and differentiation, at least partially through LRP1 and also stimulates myotube hypertrophy.

Dietary N-Glycans from Bovine Lactoferrin and TLR Modulation

SCOPE

Bovine lactoferrin (bLF) is an ingredient of food supplements and infant formulas given its antimicrobial and antiviral properties. We modified bLF enzymatically to alter its N-glycosylation and to isolate the glycan chains. The aims of this study include (1) to evaluate whether such derivates induce responses via pattern recognition receptors namely Toll-like receptors (TLRs) and (2) to relate those responses to their different glycosylation profiles.

METHODS AND RESULTS

The unmodified and modified bLF fractions are incubated with reporter cell lines expressing pattern recognition receptors. Afterwards, we screen for TLRs and analyze for nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) activation. Activation of reporter cell lines show that signaling is highly dependent on TLRs. The activation pattern of bLF is reduced with the desialylated form and increased with the demannosylated form. In reporter cells for TLR, bLF activate TLR-4 and inhibit TLR-3. The isolated glycans from bLF inhibit TLR-8. TLR-2, TLR-5, TLR-7, and TLR-9 are not significantly altered.

CONCLUSION

The profile of glycosylation is key for the biological activity of bLF. By understanding how this affects the human defense responses, the bLF glycan profile can be modified to enhance its immunomodulatory effects when used as a dietary ingredient.

Bovine lactoferrin free of lipopolysaccharide can induce a proinflammatory response of macrophages

Background

Lactoferrin (LF) is an 80 kDa glycoprotein which is known for its effects against bacteria, viruses and other pathogens. It also has a high potential in nutrition therapy and welfare of people and a variety of animals, including piglets. The ability to bind lipopolysaccharide (LPS) is one of the described anti-inflammatory mechanisms of LF. Previous studies suggested that cells can be stimulated even by LPS-free LF. Therefore, the aim of our study was to bring additional information about this possibility. Porcine monocyte derived macrophages (MDMF) and human embryonic kidney (HEK) cells were stimulated with unpurified LF in complex with LPS and with purified LF without bound LPS.

Results

Both cell types were stimulated with unpurified as well as purified LF. On the other hand, neither HEK0 cells not expressing any TLR nor HEK4a cells transfected with TLR4 produced any pro-inflammatory cytokine transcripts after stimulation with purified LF. This suggests that purified LF without LPS stimulates cells via another receptor than TLR4. An alternative, TLR4-independent, pathway was further confirmed by analyses of the NF-kappa-B-inducing kinase (NIK) activation. Western blot analyses showed NIK which activates different NFκB subunits compared to LF-LPS signaling via TLR4. Though, this confirmed an alternative pathway which is used by the purified LF free of LPS. This stimulation of MDMF led to low, but significant amounts of pro-inflammatory cytokines, which can be considered as a positive stimulation of the immune system.

Conclusion

Our results suggest that LF’s ability is not only to bind LPS, but LF itself may be a stimulant of pro-inflammatory pathways.

The impact of lactoferrin with different levels of metal saturation on the intestinal epithelial barrier function and mucosal inflammation

Translocation of bacteria, primarily Gram-negative pathogenic flora, from the intestinal lumen into the circulatory system leads to sepsis. In newborns, and especially very low birth weight infants, sepsis is a major cause of morbidity and mortality. The results of recently conducted clinical trials suggest that lactoferrin, an iron-binding protein that is abundant in mammalian colostrum and milk, may be an effective agent in preventing sepsis in newborns. However, despite numerous basic studies on lactoferrin, very little is known about how metal saturation of this protein affects a host’s health. Therefore, the main objective of this study was to elucidate how iron-depleted, iron-saturated, and manganese-saturated forms of lactoferrin regulate intestinal barrier function via interactions with epithelial cells and macrophages. For these studies, a human intestinal epithelial cell line, Caco-2, was used. In this model, none of the tested lactoferrin forms induced higher levels of apoptosis or necrosis. There was also no change in the production of tight junction proteins regardless of lactoferrin metal saturation status. None of the tested forms induced a pro-inflammatory response in Caco-2 cells or in macrophages either. However, the various lactoferrin forms did effectively inhibit the pro-inflammatory response in macrophages that were activated with lipopolysaccharide with the most potent effect observed for apolactoferrin. Lactoferrin that was not bound to its cognate receptor was able to bind and neutralize lipopolysaccharide. Lactoferrin was also able to neutralize microbial-derived antigens, thereby potentially reducing their pro-inflammatory effect. Therefore, we hypothesize that lactoferrin supplementation is a relevant strategy for preventing sepsis.

Potential of lactoferrin to prevent antibiotic-induced Clostridium difficile infection

Objectives

Clostridium difficile infection (CDI) is a global healthcare problem. Recent evidence suggests that the availability of iron may be important for C. difficile growth. This study evaluated the comparative effects of iron-depleted (1% Fe³⁺ saturated) bovine apo-lactoferrin (apo-bLf) and iron-saturated (85% Fe³⁺ saturated) bovine holo-lactoferrin (holo-bLf) in a human in vitro gut model that simulates CDI.

Methods

Two parallel triple-stage chemostat gut models were inoculated with pooled human faeces and spiked with C. difficile spores (strain 027 210, PCR ribotype 027). Holo- or apo-bLf was instilled (5 mg/mL, once daily) for 35 days. After 7 days, clindamycin was instilled (33.9 mg/L, four times daily) to induce simulated CDI. Indigenous microflora populations, C. difficile total counts and spores, cytotoxin titres, short chain fatty acid concentrations, biometal concentrations, lactoferrin concentration and iron content of lactoferrin were monitored daily.

Results

In the apo-bLf model, germination of C. difficile spores occurred 6 days post instillation of clindamycin, followed by rapid vegetative cell proliferation and detectable toxin production. By contrast, in the holo-bLf model, only a modest vegetative cell population was observed until 16 days post antibiotic administration. Notably, no toxin was detected in this model. In separate batch culture experiments, holo-bLf prevented C. difficile vegetative cell growth and toxin production, whereas apo-bLf and iron alone did not.

Conclusions

Holo-bLf, but not apo-bLf, delayed C. difficile growth and prevented toxin production in a human gut model of CDI. This inhibitory effect may be iron independent. These observations suggest that bLf in its iron-saturated state could be used as a novel preventative or treatment strategy for CDI.

Lactoferrin Induces Osteoblast Growth through IGF-1R

Objectives. To investigate the role of the IGF-1R by which lactoferrin induces osteoblast growth. Methods. Osteoblast received 5 d lactoferrin intervention at a concentration of 0.1, 1, 10, 100, and 1000 μg/mL, and the IGF-1 and IGF-1R were detected using RT-PCR and western blot. The osteoblast into the control, 100 μg/mL lactoferrin, Neo-scramble (NS, empty vector), NS + 100 μg/mL lactoferrin, shIGF-1R and shIGF-1R + 100 μg/mL lactoferrin group. We test the apoptosis and proliferation and the level of PI3K and RAS in osteoblasts after 5 d intervention. Results. (1) 1, 10, 100, and 1000 μg/mL lactoferrin induced the expression of IGF-1 mRNA and protein. 10 μg/mL and 100 μg/mL lactoferrin induced the expression of IGF-1R mRNA and protein. (2) Lactoferrin (100 μg/mL) induced osteoblast proliferation while inhibiting apoptosis. Osteoblasts with silenced IGF-1R exhibited decreased proliferation but increased apoptosis. MMT staining and flow cytometry both indicated that there was no significant difference between the shIGF-1R group and the shIGF-1R + 100 μg/mL lactoferrin group. (3) Lactoferrin (100 μg/mL) induced PI3K and RAS phosphorylation and silence of IGF-1R resulted in decreased p-PI3K and p-RAS expression. Lactoferrin-treated shIGF-1R cells showed significantly higher level of p-PI3K and p-RAS when compared with shIGF-1R. Conclusion. Lactoferrin induced IGF-1/IGF-1R in a concentration-dependent manner. Lactoferrin promoted osteoblast proliferation while inhibiting apoptosis through IGF-1R. Lactoferrin activated PI3K and RAS phosphorylation via an IGF-1R independent pathway.