Lactoferrin: from the structure to the functional orchestration of iron homeostasis

Critical Importance of Iron Saturation in Lactoferrin: Effects on Biological Activity, Nutritional Functions, and Applications

Lactoferrin (LF), a multifunctional glycoprotein with high iron-binding affinity, plays a critical role in modulating physiological processes through its ability to reversibly bind and release iron ions, existing in two distinct states: iron-saturated (holo-LF, > 85% saturation) and iron-deficient (apo-LF, < 5% saturation). However, the importance of iron saturation has been largely overlooked in LF production and research due to the lack of standardized protocols. The iron saturation level of LF dictates its functional specificity: apo-LF exhibits potent antimicrobial properties by chelating iron and disrupting membrane integrity, while also significantly inhibiting oxidative stress, thereby alleviating neurological disorders and modulating immune responses. In contrast, holo-LF participates in iron metabolism and transport, influencing tumor cell proliferation and systemic iron uptake. This review systematically evaluates the interplay between iron saturation levels and LF's biological functions, emphasizing its dual roles in human iron homeostasis and disease modulation. Future research should prioritize elucidating the mechanisms underlying iron saturation-dependent bioactivity and metabolic differences, while incorporating emerging technologies to enhance LF stability and refine iron saturation measurement accuracy.

Antioxidant Potential of Lactoferrin and Its Protective Effect on Health: An Overview

Chronic diseases, including cardiovascular and neurodegenerative diseases and cancer, are significant global health challenges. Oxidative stress, characterized by an imbalance between reactive oxygen species (ROS) production and antioxidant defenses, is a critical factor in the progression of these pathologies. Lactoferrin (Lf), a multifunctional iron-binding glycoprotein, has emerged as a promising therapeutic agent due to its potent antioxidant, anti-inflammatory, and iron-regulating properties. Lf plays a pivotal role in iron homeostasis by chelating iron, modulating its cellular uptake, and reducing ROS production, thereby mitigating oxidative stress-related tissue damage. Lf also demonstrates neuroprotective potential in diseases like Parkinson's and Alzheimer's, where it alleviates oxidative damage, regulates iron metabolism, and enhances antioxidant defenses. Furthermore, its ability to enhance endogenous antioxidant mechanisms, such as superoxide dismutase and glutathione peroxidase, underscores its systemic protective effects. Lf's anti-inflammatory and antimicrobial activities also contribute to its broad-spectrum protective role in chronic diseases. This review consolidates evidence of Lf's mechanisms in mitigating oxidative stress and highlights its therapeutic potential as a versatile molecule for preventing and managing chronic conditions linked to oxidative damage.

Controversial role of lactoferrin in cancer: A narrative review

Lactoferrin (Lf) is a positively charged iron-binding glycoprotein that has piqued the scientific community's interest due to its pleiotropic behavior, exhibiting a wide range of biological activities, including antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, and anticancer effects. This narrative review explores the current understanding of Lf's role in cancer, focusing on the endogenously expressed human full-length and ΔLf isoforms, and the effects of treatment with exogenous human and bovine Lf. We evaluated and compared the mechanisms by which Lf influences tumorigenesis and cancer progression, focusing on its impact on key processes such as cell growth, apoptosis, angiogenesis, cell migration, and invasiveness. Notably, the mechanisms of action of human and bovine Lf show some divergences, presumably due to slight structural differences that may lead to opposing effects. Insights from this comparison may help identify new Lf variants with enhanced anticancer activity. Indeed, both human and bovine Lf showed substantial anticancer activity, prompting researchers to investigate their potential utility in cancer prevention and progression. However, some studies have indicated that high levels of human Lf expression may be linked to increased carcinogenesis and metastasis, reflecting its intricate and context-dependent role in cancer. Thus, we emphasize the need for a deeper comprehension of Lf biology and its regulation to enhance understanding of Lf's role in cancer and identify more targeted therapeutic strategies, encouraging further research in this area.

Lactoferrin in the treatment of interstitial cystitis: a retrospective pilot study

Interstitial cystitis (IC), defined as a painful bladder syndrome (PBS), is a chronic condition that manifests itself as a suprapubic pain associated with an enhancing of frequency/urgency of urination, and for which there is no cure. Here, we present a retrospective pilot study on women affected from IC/PBS and treated with bovine lactoferrin (bLf). A total of 31 women, affected (20) or unaffected (11) from hereditary thrombophilia (HT), presented the median of 6 episodes of IC/PBS during the 6 months before the study. Treatment consisted of 17 weeks of orally administered Valpalf® capsules, containing bLf plus sodium bicarbonate and citrate. Out of 31 patients, only 3 women had one episode of IC/PBS during the follow-up period, while no episode was observed in 28 women. In the HT group, a significant decrease in both serum IL-6 and D-dimers was found after Valpalf® treatment. Moreover, in Valpalf®-treated women, cystoscopy revealed a global improvement in the appearance of the bladder, especially in term of inflammation/irritation and presence of Hunner ulcers. Even if our results must be corroborated by randomized double-blinded controlled trials on a larger number of patients, our observations indicate that bLf treatment is efficient in relieving IC/PBS symptoms, without side effects.

Lactoferrin/lactoferrin receptor: Neurodegenerative or neuroprotective in Parkinson's disease?

Lactoferrin (Lf) is a multifunctional protein in the transferrin family. It is involved in many physiological functions, including the regulation of iron absorption and immune response. It also has antibacterial, antiviral, anti-inflammatory, anticancer and antioxidant capabilities under pathophysiological conditions. The mammalian lactoferrin receptor (LfR) plays a key role in mediating multiple functions of Lf. Studies have shown that Lf/LfR is abnormally expressed in the brain of Parkinson's disease, and the excessive accumulation of iron in the brain caused by the overexpression of Lf and LfR is considered to be one of the initial causes of the degeneration of dopaminergic neurons in Parkinson's disease. On the other hand, a number of recent studies have reported that Lf/LfR has a significant neuroprotective effect on Parkinson's disease. In other words, it seems paradoxical that Lf/LfR has both neurodegenerative and neuroprotective effects in Parkinson's disease. This article focuses on recent advances in the possible mechanisms of the neurodegenerative and neuroprotective effects of Lf/LfR in Parkinson's disease and discusses why Lf/LfR has a seemingly contradictory role in the development of Parkinson's disease. Based on the evidence obtained so far, we believed that Lf/LfR has a neuroprotective effect on Parkinson's disease, while as to whether the overexpressed Lf/LfR is the cause of the development of Parkinson's disease, the current evidence is insufficient and further investigation needed.

A new spectrophotometric method for measuring ceruloplasmin ferroxidase activity: an innovative approach

Ferroxidases are enzymes that participate in the iron metabolism of different organisms. They catalyze the oxidation of ferrous iron, Fe2⁺, into ferric iron, Fe3⁺, which is essential in iron homeostasis and physiological functioning. The present study describes a novel spectrophotometric method of serum ceruloplasmin ferroxidase activity. This method is easy to perform; it is also sensitive, specific, and rapid. In this method, ferrous ions are used as a substrate for the enzyme, with either salicylic acid or sulfosalicylic acid being taken as a chromogenic compound. These chromogens easily form a colored complex with ferric ions but are not formed with ferrous ions. In the enzymatic reaction, the ceruloplasmin ferroxidase enzyme catalyzes the oxidation of ferrous to ferric ions. The resulting increase in ferric ion concentration is then measured spectrophotometrically, following the formation of the colored complex. The complex formed has maximum absorbance at 540 nm in the case of salicylic acid and 490 nm in the case of sulfosalicylic acid. Comparatively, it was tested against the standard method to ascertain the new method's effectuality and reliability for assaying ferroxidase activity. The determined correlation coefficient amounted to 0.99, showing a strong correlation between the results obtained by the two methods. This new spectrophotometric technique offers a simplified, sensitive, specific, and fast means of estimating ferroxidase activity. It avoids using concentrated strong acids in the procedure and correlates excellently with the standard technique. This sets up a potential alternative for accurately determining ferroxidase activity in biological samples.

Lactoferrin, chitosan double-coated oleosomes loaded with clobetasol propionate for remyelination in multiple sclerosis: Physicochemical characterization and in-vivo assessment in a cuprizone-induced demyelination model

Multiple sclerosis is a chronic inflammatory demyelinating disorder of the CNS characterized by continuous myelin damage accompanied by deterioration in functions. Clobetasol propionate (CP) is the most potent topical corticosteroid with serious side effects related to systemic absorption. Previous studies introduced CP for remyelination without considering systemic toxicity. This work aimed at fabrication and optimization of double coated nano-oleosomes loaded with CP to achieve brain targeting through intranasal administration. The optimized formulation was coated with lactoferrin and chitosan for the first time. The obtained double-coated oleosomes had particle size (220.07 ± 0.77 nm), zeta potential (+30.23 ± 0.41 mV) along with antioxidant capacity 9.8 μM ascorbic acid equivalents. Double coating was well visualized by TEM and significantly decreased drug release. Three different doses of CP were assessed in-vivo using cuprizone-induced demyelination in C57Bl/6 mice. Neurobehavioral tests revealed improvement in motor and cognitive functions of mice in a dose-dependent manner. Histopathological examination of the brain showed about 2.3 folds increase in corpus callosum thickness in 0.3 mg/kg CP dose. Moreover, the measured biomarkers highlighted the significant antioxidant and anti-inflammatory capacity of the formulation. In conclusion, the elaborated biopolymer-integrating nanocarrier succeeded in remyelination with 6.6 folds reduction in CP dose compared to previous studies.

Lactoferrin efficacy in treating hyperferritinemia in patients suffering from pathologies unrelated to hereditary hemochromatosis

Ferritin (Ftn), a globular protein, sequesters 4500 atoms of iron per molecule. Elevated serum Ftn levels (hyperferritinemia) is an indicator of iron homeostasis disorders. We present the results of an observational study involving 17 patients with hyperferritinemia unrelated to hereditary hemochromatosis (HH). All participants received treatment with 200 mg of bovine lactoferrin (bLf) once (n = 14) or twice (n = 3) a day before meals. The patients, treated with 200 mg/day of bLf, exhibited a significant increase in red blood cells (+10%, p < 0.001), hemoglobin (+4%, p < 0.001), and hematocrit (+15%, p = 0.004), accompanied by a significant reduction in serum Ftn levels (-52%, p < 0.001), C-reactive protein (CRP) (-85.0%, p < 0.001), and D-dimers (-19%, p < 0.001). Among the three patients treated with 400 mg/day of bLf, two had effects similar to those of patients bLf-treated with 200 mg/day and one experienced a strong reduction of Ftn, CRP, and erythrocyte sedimentation rate (from -97% to -75%). The decrease in serum Ftn levels due to bLf treatment was largely independent of gender (p = 0.78), age (p = 0.66), baseline symptoms (p = 0.20), and concomitant acute (p = 0.34) and chronic (p = 0.53) infections. Although this observational pilot study yields positive effects in patients with hyperferritinemia unrelated to HH treated with bLf, a larger sample size is needed for conclusive results.

Lactoferrin Protects Against Rotenone-Induced Toxicity in Dopaminergic SH-SY5Y Cells through the Modulation of Apoptotic-Associated Pathways

Parkinson's disease (PD) is a common motor neurodegenerative disease that still lacks effective therapeutic options. Previous studies have reported that lactoferrin exhibited neuroprotective effects in cellular and animal models of PD, typically induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 1-methyl-4-phenylpyridinium (MPP+) synthetic toxin. However, the neuroprotective capacity of lactoferrin in the rotenone-induced cellular model of PD remains relatively less established. Unlike MPTP/MPP+, rotenone is a naturally occurring environmental toxin known to induce chronic toxicity and increase the risk of PD in humans. In this study, we constructed a cellular model of PD by differentiating SH-SY5Y neuroblastoma cells with retinoic acid into mature dopaminergic neurons with increased β-tubulin III and tyrosine hydroxylase expression, followed by 24 h of rotenone exposure. Using this cellular model of PD, we showed that lactoferrin (1-10 µg/ml) pre-treatment for 48 h decreased loss of cell viability, mitochondrial membrane potential impairment, reactive oxygen species generation and pro-apoptotic activities (pan-caspase activation and nuclear condensation) in cells exposed to rotenone (1 and 5 µM) using biochemical assays, Hoechst 33342 staining and immunocytochemical techniques. We further demonstrated that 48 h of lactoferrin (10 µg/ml) pre-treatment decreased Bax:Bcl2 ratio and p42/44 mitogen-activated protein kinase expression but increased pAkt expression in 5 µM rotenone-exposed cells. Our study demonstrates that lactoferrin neuroprotective capacity is present in the rotenone-induced cellular model of PD, further supporting lactoferrin as a potential PD therapeutic that warrants further studies.

Valpalf®: A New Nutraceutical Formulation Containing Bovine Lactoferrin That Exhibits Potentiated Biological Activity

As a nutraceutical, bovine lactoferrin (bLf), an iron-binding glycoprotein involved in innate immunity, is gaining elevated attention for its ability to exert pleiotropic functions and to be exceptionally tolerated even at high dosages. Some of bLf's activities, including its anti-inflammatory and antioxidant, are tightly linked to its ability to both chelate iron and enter inside the cell nucleus. Here, we present data about Valpalf®, a new formulation containing bLf, sodium citrate, and sodium bicarbonate at a molar ratio of 10-3. In the present study, Valpalf® exhibits superior iron-binding capacity, resistance to tryptic digestion, and a greater capacity to accumulate into the nucleus over time when compared to the native bLf alone. In agreement, Valpalf® effectively reduces interleukin(IL)-6 levels in lipopolysaccharide-stimulated macrophages and modulates the expression of antioxidant enzymes, such as superoxide dismutase 1 and 2, in phorbol-12-myristate-13-acetate-stimulated monocytes. Of note, this potentiated bioactivity was corroborated in a retrospective study on the treatment of anemia of inflammation in hereditary thrombophilic pregnant and non-pregnant women, demonstrating that Valpalf® improves hematological parameters and reduces serum IL-6 levels to a higher extent than bLf alone.

Antibacterial, anti-invasive, and anti-inflammatory activity of bovine lactoferrin extracted from milk or colostrum versus whole colostrum

Lactoferrin (Lf), a multifunctional cationic glycoprotein extracted from milk or colostrum, is able to chelate two ferric ions per molecule, inhibit the formation of reactive oxygen species, interact with the anionic components of bacteria or host cells, and enter inside host cell nucleus, thereby exerting antibacterial, anti-invasive, and anti-inflammatory activities. By virtue of Lf presence, bovine colostrum is expected to perform analogous functions to pure Lf, along with additional activities attributable to other bioactive constituents. The present research aims to compare the antibacterial, anti-invasive, and anti-inflammatory activities of bovine Lf purified from milk (mbLf) and colostrum (cbLf) in comparison to those exhibited by whole bovine colostrum (wbc). The results demonstrated a major efficacy of mbLf in inhibiting pathogenic bacteria and in exerting anti-invasive and anti-survival activities with respect to cbLf and wbc. Furthermore, mbLf lowered IL-6 levels to those of uninfected cells, while a less evident decrease was observed upon cbLf treatment. Conversely, wbc managed to slightly lower IL-6 levels compared to those synthesized by infected cells. These data demonstrate that, to obtain maximum effectiveness in such activities, Lf should be formulated/used without addition of other substances and should be sourced from bovine milk rather than colostrum.

Association of plasma lactoferrin levels with disease severity in glaucoma patients

Objective

To explore the relationship between plasma lactoferrin (Lf) and glaucoma, assessing the clinical utility of Lf in glaucoma.

Methods

A cross-sectional study involved 161 glaucoma patients and 115 healthy controls, with a follow-up of 14 subjects after approximately 2 years. Plasma Lf markers were quantified using ELISA, comparing levels between glaucoma patients and healthy controls, and analyzing plasma Lf across different glaucoma severity grades.

Results

Glaucoma patients had significantly elevated plasma Lf levels compared to healthy controls (p < 0.001). Higher plasma Lf levels correlated with more severe disease stages (HPA grades showed ρ = 0.435, p < 0.001; AGIS grades showed ρ = 0.436, p < 0.001) and reduced retinal nerve fiber layer (RNFL) thickness (RNFL thickness showed ρ = -0.204, p = 0.024). ROC curve analysis demonstrated the efficacy of glaucoma markers in differentiating early-stage from advanced glaucoma.

Conclusion

Plasma Lf levels are significantly associated with glaucoma severity and may be involved in the pathogenic progression of the disease.

Current Views about the Inflammatory Damage Triggered by Bacterial Superantigens and Experimental Attempts to Neutralize Superantigen-Mediated Toxic Effects with Natural and Biological Products

Superantigens, i.e., staphylococcal enterotoxins and toxic shock syndrome toxin-1, interact with T cells in a different manner in comparison to conventional antigens. In fact, they activate a larger contingent of T lymphocytes, binding outside the peptide-binding groove of the major histocompatibility complex class II. Involvement of many T cells by superantigens leads to a massive release of pro-inflammatory cytokines, such as interleukin (IL)-1, IL-2, IL-6, tumor necrosis factor-alpha and interferon-gamma. Such a storm of mediators has been shown to account for tissue damage, multiorgan failure and shock. Besides conventional drugs and biotherapeutics, experiments with natural and biological products have been undertaken to attenuate the toxic effects exerted by superantigens. In this review, emphasis will be placed on polyphenols, probiotics, beta-glucans and antimicrobial peptides. In fact, these substances share a common functional denominator, since they skew the immune response toward an anti-inflammatory profile, thus mitigating the cytokine wave evoked by superantigens. However, clinical applications of these products are still scarce, and more trials are needed to validate their usefulness in humans.

Lactoferrin improves symptoms of dextran sulfate sodium-induced colitis in mice through modulation of cellular senescence

The multifaceted effects of lactoferrin (LF) on the digestive and immune systems make it an attractive therapeutic option in inflammatory bowel diseases. In this study, we aimed to explore the anti-inflammatory effects of LF in colitis, particularly in relation to cellular senescence. We hypothesize that LF has the potential to modulate the senescence process. The effects of LF on senescence were tested in vitro using HCT116 and SW480 cell lines, and in vivo, the dextran sulfate sodium-induced mouse model of colitis. LF (500 mg/kg) alleviated symptoms of colitis in mice with a significant decrease in colon damage (P < .0001 vs. control) and microscopic (P < .05 vs. control) scores. Cellular senescence markers p16 and p21 were significantly upregulated in the mouse colon during inflammation (both P < .01 vs. control), and LF at 500 mg/kg decreased these markers (both P < .05 vs. dextran sulfate sodium-treated mice). In vitro, LF significantly affected the expression of p16 and p21 (P < .05-P < .0001 vs. control), senescence associated secretory phenotype (P < .01-P < .0001 vs. control), and telomere-specific proteins: telomeric repeat binding factor 1 and 2 (P < .05-P < .0001 vs. control) in a concentration-dependent manner. LF modulates the expression of cellular senescence markers and shows hallmarks of senolytic and pro-senescent activity, depending on dose. Further studies are needed to fully understand the anti-inflammatory effect of LF in the context of senescence and safe utilization in patients with inflammatory bowel diseases.

To Boost or to Reset: The Role of Lactoferrin in Energy Metabolism

Many pathological conditions, including obesity, diabetes, hypertension, heart disease, and cancer, are associated with abnormal metabolic states. The progressive loss of metabolic control is commonly characterized by insulin resistance, atherogenic dyslipidemia, inflammation, central obesity, and hypertension, a cluster of metabolic dysregulations usually referred to as the "metabolic syndrome". Recently, nutraceuticals have gained attention for the generalized perception that natural substances may be synonymous with health and balance, thus becoming favorable candidates for the adjuvant treatment of metabolic dysregulations. Among nutraceutical proteins, lactoferrin (Lf), an iron-binding glycoprotein of the innate immune system, has been widely recognized for its multifaceted activities and high tolerance. As this review shows, Lf can exert a dual role in human metabolism, either boosting or resetting it under physiological and pathological conditions, respectively. Lf consumption is safe and is associated with several benefits for human health, including the promotion of oral and gastrointestinal homeostasis, control of glucose and lipid metabolism, reduction of systemic inflammation, and regulation of iron absorption and balance. Overall, Lf can be recommended as a promising natural, completely non-toxic adjuvant for application as a long-term prophylaxis in the therapy for metabolic disorders, such as insulin resistance/type II diabetes and the metabolic syndrome.

Effects of Lactoferrin on Oral and Throat Conditions under Low Humidity Environments: A Randomized, Double-Blind, and Placebo-Controlled Crossover Trial

To evaluate the effects of a single ingestion of bovine lactoferrin (bLF) on oral and throat conditions under a low-humidity environment. A randomized, double-blind, 2-sequence, 2-treatment, and 2-period placebo-controlled crossover trial was conducted. Healthy adult subjects orally ingested bLF dissolved in water, or placebo water, followed by exposure to low humidity (20 °C, 20% relative humidity (RH)) for 2 h. The primary endpoint was subjective oral and throat discomfort assessed by a visual analog scale (VAS), which positively correlated with the discomfort. Secondary endpoints were unstimulated whole salivary flow rate (UWSFR) and salivary immunoglobulin A (IgA) secretion rate. Overall, 40 subjects were randomly assigned to two sequences (20 each) and 34 were analyzed. The VAS values for oral and throat discomfort in the bLF treatment were significantly lower than in the placebo treatment, whereas UWSFR and IgA secretion rates were comparable between the two treatments. Adverse drug reactions were not observed. Subjective oral and throat discomfort associated with low humidity is suppressed by a single ingestion of bLF. Our findings demonstrate the novel use of bLF in a clinical situation that leverages its unique characteristics.

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.

Synergistic Antimicrobial Action of Lactoferrin-Derived Peptides and Quorum Quenching Enzymes

Combined use of various antimicrobial peptides (AMPs) with enzymes that hydrolyze the signaling molecules of the resistance mechanism of various microorganisms, quorum sensing (QS), to obtain effective antimicrobials is one of the leading approaches in solving the antimicrobial resistance problem. Our study investigates the lactoferrin-derived AMPs, lactoferricin (Lfcin), lactoferampin and Lf(1-11), as potential partners for combination with enzymes hydrolyzing lactone-containing QS molecules, the hexahistidine-containing organophosphorus hydrolase (His6-OPH) and penicillin acylase, to obtain effective antimicrobial agents with a scope of practical application. The possibility of the effective combination of selected AMPs and enzymes was first investigated in silico using molecular docking method. Based on the computationally obtained results, His6-OPH/Lfcin combination was selected as the most suitable for further research. The study of physical-chemical characteristics of His6-OPH/Lfcin combination revealed the stabilization of enzymatic activity. A notable increase in the catalytic efficiency of action of His6-OPH in combination with Lfcin in the hydrolysis of paraoxon, N-(3-oxo-dodecanoyl)-homoserine lactone and zearalenone used as substrates was established. Antimicrobial efficiency of His6-OPH/Lfcin combination was determined against various microorganisms (bacteria and yeasts) and its improvement was observed as compared to AMP without enzyme. Thus, our findings demonstrate that His6-OPH/Lfcin combination is a promising antimicrobial agent for practical application.