Preparation and antimicrobial action of three tryptic digested functional molecules of bovine lactoferrin

Bovine Lactoferrin and Current Antifungal Therapy Against Candida Albicans: A Systematic Review and Meta-Analysis

Candida albicans is an important causative organism of opportunistic fungal infection, and it is a growing medical concern due to the increasing usage of broad-spectrum antibiotics, immunosuppressant agents, and other immunocompromising conditions. Currently, bLf and antifungal drugs have been known to have synergistic effects, increasing the drug's efficacy. This study aims to investigate the efficacy of the synergistic effect of bLf and antifungal drugs. This review addressed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. We conducted literature searches to assess the association of lactoferrin and current antifungal therapy against Candida albicans in ProQuest, PubMed, MEDLINE, EBSCOhost, SAGE, JSTOR, GARUDA, and Open Gray with no date restriction (until March 5th, 2021). We used Jeffry's Amazing Statistical Program (JASP) to measure the overall size effect of MIC (minimum inhibitory concentration) between studies. A total of 7 studies retained were experimental in vitro studies. Based on the available data, 4 out of 7 studies were included in the quantitative analysis. This systematic review showed that bovine lactoferrin could help inhibit the development of azole-susceptible and azole-resistant C. albicans. Furthermore, there was synergistic activity between lactoferrin and various antifungals. Our meta-analysis showed that lactoferrin could significantly inhibit the C. albicans growth than the control group. Bovine lactoferrin and its peptide derivatives isolated from bovine milk can significantly inhibit the growth of C. albicans, both susceptible to azoles and those with azole resistance.

Proteolysis of vaginally administered bovine lactoferrin: clearance, inter-subject variability, and implications for clinical dosing

This report describes proteolytic fragmentation and clearance of bovine lactoferrin (bLF) upon intravaginal administration in premenopausal women. Tablet formulations (MTbLF) containing 300 mg of bLF progressed through three phases: Pre-Dissolution, Dissolution, and Washout, over a 30-h time course. Tablets dissolved slowly, replenishing intact 80 kDa bLF in vaginal fluid (VF) as proteolysis occurred. bLF was initially cleaved approximately in half between its N- and C-lobes, then degraded into sub-fragments and small peptides. The extent of proteolysis was less than 10-20% across multiple subjects. Concentrations of both intact 80 kDa bLF and smaller fragments decreased in VF with a similar time course suggesting washout not proteolysis was the main clearance mechanism. Concentrations of intact and/or nicked 80 kDa bLF peaked between 4 and 8 h after administration and remained above 5 mg/mL for approximately 24 h. Experiments with protease inhibitors in ex vivo VF digests suggested an aspartyl protease was at least partially responsible for bLF cleavage. However, digestion with commercial pepsin or in vivo in the human stomach, demonstrated distinctly different patterns of fragments compared to vaginal proteolysis. Furthermore, the 3.1 kDa antimicrobial peptide lactoferricin B was not detected in VF. This suggests pepsin-like aspartyl proteases are not responsible for vaginal proteolysis of bLF.

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.

Lactoferrin: A Nutraceutical with Activity against Colorectal Cancer

Homeostasis in the human body results from the tight regulation of several events, since too little inflammation disrupts the process of tissue repair and remodeling, whereas too much exerts a collateral effect by causing tissue damage with life-threatening consequences. In some clinical conditions, such as inflammatory bowel disease (IBD), inflammation functions as a double-edged sword by either enabling or inhibiting cancer development and progression. Generally, cancer develops through evasion mechanisms that regulate cell growth, causing a high rate of uncontrolled proliferation, and mechanisms for evading cell death, such as apoptosis. Moreover, chronic inflammation is a factor that contributes to colorectal cancer (CRC), as observed in individuals with IBD; all these conditions favor an increased rate of angiogenesis and eventual metastasis. Lactoferrin (Lf) is a mammalian iron-binding multifunctional glycoprotein regarded as a natural compound that up- and downregulates both humoral and cellular components of immunity involved in regulating the inflammatory response and maintaining gut homeostasis. Human and bovine Lf share high sequence homology and have very similar antimicrobial, anti-inflammatory, and immunomodulatory activities. Bovine Lf from milk is considered a safe molecule and is commercially available in large quantities. This review mainly focuses on the regulatory effects of orally administered bovine Lf on the inflammatory response associated with CRC; this approach indicates that CRC is one of the most frequently diagnosed cancers and affects the intestinal tract with high clinical and epidemiologic relevance. Thus, this review may provide foundations for the potential use of bovine Lf alone or as a natural adjunct agent to increase the effectiveness and reduce the side effects of anticancer chemotherapy.

Diverse Mechanisms of Antimicrobial Activities of Lactoferrins, Lactoferricins, and Other Lactoferrin-Derived Peptides

Lactoferrins are an iron-binding glycoprotein that have important protective roles in the mammalian body through their numerous functions, which include antimicrobial, antitumor, anti-inflammatory, immunomodulatory, and antioxidant activities. Among these, their antimicrobial activity has been the most studied, although the mechanism behind antimicrobial activities remains to be elucidated. Thirty years ago, the first lactoferrin-derived peptide was isolated and showed higher antimicrobial activity than the native lactoferrin lactoferricin. Since then, numerous studies have investigated the antimicrobial potencies of lactoferrins, lactoferricins, and other lactoferrin-derived peptides to better understand their antimicrobial activities at the molecular level. This review defines the current antibacterial, antiviral, antifungal, and antiparasitic activities of lactoferrins, lactoferricins, and lactoferrin-derived peptides. The primary focus is on their different mechanisms of activity against bacteria, viruses, fungi, and parasites. The role of their structure, amino-acid composition, conformation, charge, hydrophobicity, and other factors that affect their mechanisms of antimicrobial activity are also reviewed.

Lactoferrin receptors in Gram-negative bacteria: an evolutionary perspective

In this short review, we outline the major events that led to the development of iron acquisition systems in Gram-negative bacteria and mammals since the beginning of life on earth. Naturally, the interaction between these organisms led to the development of a wonderfully complex set of protein systems used for competition over a once prevalent (but no longer) biocatalytic cofactor. These events led to the appearance of the lactoferrin gene, which has since been exploited into adopting countless new functions, including the provision of highly bactericidal degradation products. In parallel to lactoferrin's evolution, evolving bacterial receptors have countered the bactericidal properties of this innate immunity protein.

Lactoferrin in the Prevention and Treatment of Intestinal Inflammatory Pathologies Associated with Colorectal Cancer Development

The connection between inflammation and cancer is well-established and supported by genetic, pharmacological and epidemiological data. The inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, have been described as important promoters for colorectal cancer development. Risk factors include environmental and food-borne mutagens, dysbalance of intestinal microbiome composition and chronic intestinal inflammation, with loss of intestinal epithelial barrier and enhanced cell proliferation rate. Therapies aimed at shutting down mucosal inflammatory response represent the foundation for IBDs treatment. However, when applied for long periods, they can alter the immune system and promote microbiome dysbiosis and carcinogenesis. Therefore, it is imperative to find new safe substances acting as both potent anti-inflammatory and anti-pathogen agents. Lactoferrin (Lf), an iron-binding glycoprotein essential in innate immunity, is generally recognized as safe and used as food supplement due to its multifunctionality. Lf possesses a wide range of immunomodulatory and anti-inflammatory properties against different aseptic and septic inflammatory pathologies, including IBDs. Moreover, Lf exerts anti-adhesive, anti-invasive and anti-survival activities against several microbial pathogens that colonize intestinal mucosa of IBDs patients. This review focuses on those activities of Lf potentially useful for the prevention/treatment of intestinal inflammatory pathologies associated with colorectal cancer development.

Lactoferrin-Derived Peptide Lactofungin Is Potently Synergistic with Amphotericin B

Lactoferrin (LF) is an iron-binding glycoprotein with broad-spectrum antimicrobial activity. Previously, we discovered that LF synergistically enhanced the antifungal efficacy of amphotericin B (AMB) across a variety of yeast species and subsequently hypothesized that this synergy was enhanced by the presence of small peptides derived from the whole LF molecule. In this study, LF was digested with pepsin under a range of conditions. The resulting hydrolysates exhibited enhanced synergy with AMB compared to its synergy with undigested LF. Samples were analyzed using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and 14 peptides were identified. The sequences of these peptides were predicted by matching their molecular weights to those of a virtual digest with pepsin. The relative intensities of predicted peptides in each hydrolysate were compared with the activity of the hydrolysate, and the structural and physicochemical properties of the peptides were assessed. From this, a 30-residue peptide was selected for synthesis and dubbed lactofungin (LFG). Pure LFG was highly synergistic with AMB, outperforming native LF in all fungal species tested. With potential for further structural and chemical improvements, LFG is an excellent lead for development as an antifungal adjuvant.

Modification of protein structures by altering the whey protein profile and heat treatment affects in vitro static digestion of model infant milk formulas

Heat treatments induce changes in the protein structure in infant milk formulas (IMFs). The present study aims to investigate whether these structural modifications affect protein digestion. Model IMFs (1.3% proteins), with a bovine or a human whey protein profile, were unheated or heated at 67.5 °C or 80 °C to reach 65% of denaturation, resulting in six protein structures. IMFs were submitted to in vitro static gastrointestinal digestion simulating infant conditions. During digestion, laser light scattering was performed to analyze IMF destabilization and SDS-PAGE, OPA assay and cation exchange chromatography were used to monitor proteolysis. Results showed that, during gastric digestion, α-lactalbumin and β-lactoglobulin were resistant to hydrolysis in a similar manner for all protein structures within IMFs (p > 0.05), while the heat-induced denaturation of lactoferrin significantly increased its susceptibility to hydrolysis. Casein hydrolysis was enhanced when the native casein micelle structure was modified, i.e. partially disintegrated in the presence of lactoferrin or covered by heat-denatured whey proteins. The IMF destabilization at the end of the gastric digestion varied with protein structures, with larger particle size for IMF containing native casein micelles. During intestinal digestion, the kinetics of protein hydrolysis varied with the IMF protein structures, particularly for IMFs containing denatured lactoferrin, exhibiting higher proteolysis degree (67.5 °C and 80 °C vs. unheated) and essential amino acid bioaccessibility (67.5 °C vs. unheated). Overall, the protein structures, generated by modulating the whey protein profile and the heating conditions, impacted the IMF destabilization during the gastric phase and the proteolysis during the entire simulated infant digestion.

Evaluation of therapeutic potential of recombinant buffalo lactoferrin N-lobe expressed in E. coli

Lactoferrin (Lf) is a multifunctional bi-lobate iron-binding glycoprotein belonging to transferrin family with a mass of approximately 80 kD. Being ubiquitously present in almost all biological secretions, it performs important biological functions. One of the earliest and very well-documented functions of Lf is the antibacterial effect against broad spectrum Gram-negative and Gram-positive bacteria. In this study, buffalo Lf N-lobe cDNA was amplified, cloned and expressed as a fusion protein in Escherichia coli cells using pQE30 expression vector. After post-induction confirmation of expressed protein by SDS-PAGE, purification of recombinant protein using Ni-NTA was attempted and the yield of recombinant buffalo N-lobe Lf was estimated to be 1 mg/ml. Antibacterial activity of recombinant buffalo Lf N-lobe was assessed on pathogenic E. coli and Staphylococcus aureus strains. Peptic digest of recombinant N-lobe buffalo Lf showed antibacterial activity comparable to commercially available bovine Lf. The successful expression and characterization of functional recombinant N-lobe of buffalo Lf expressed in E. coli opens new vistas for developing alternate therapeutics, particularly against the diseases caused by Gram-negative microbes such as septicemia and diarrhea in newborn calves and mastitis in dairy animals.

Supplementing 2 g per day bovine lactoferrin from late gestation until weaning did not improve lactation performance of mixed parity sows

Context Lactoferrin is a non-haem binding protein that possesses antimicrobial, antioxidant and anti-inflammatory properties. A previous study showed lactoferrin supplementation from early gestation to weaning improved lactation performance in primiparous sows; however, it is unknown whether the supplementation within a more specified duration (from late gestation to weaning) can improve lactation performance in multiparous sows, which limits its commercial application. Aims This experiment investigated the effects of 2 g/day bovine lactoferrin supplementation from late gestation to weaning on lactation performance in mixed parity sows. Methods Forty-seven primiparous sows and 167 multiparous sows (up to parity 5; Large White × Landrace, PrimeGro Genetics, Corowa, NSW) were allocated to either a Control diet (2 g/day casein) or Lactoferrin supplement diet (2 g/day lactoferrin) when entering the farrowing house in late gestation (101 ± 4.6 days, mean ± s.d.) balanced by parity (2.4 ± 1.80, mean ± s.d.). Sows were housed individually in farrowing crates and fed the experimental diets until weaning (26 ± 2.5 days, mean ± s.d.). Farrowing outcomes and lactation performance were recorded. Key results Lactoferrin supplementation did not affect the number of piglets born alive, number of stillborn piglets, number of mummified fetuses, the percentage of born-light piglets (≤1.1 kg) or piglet pre-fostering survival rate. Cross-fostering within the first 48 h standardised the litter size and litter weight between dietary treatments. Piglet pre-weaning survival rate, litter weight gain, average daily gain of piglets, or coefficient of variation of piglet growth rate was not affected by lactoferrin supplementation. Daily feed intake during lactation, bodyweight and backfat thickness of sows at weaning were similar between the dietary treatments. Conclusions Two grams per day lactoferrin supplementation from late gestation to weaning did not affect lactation performance in mixed parity sows. Implications The effectiveness of lactoferrin supplementation may depend upon the duration of supplementation, which should be optimised in future studies.

In vitro effectiveness of recombinant human lactoferrin and its hydrolysate in alleviating LPS-induced inflammatory response

This study aimed to evaluate the potential anti-inflammatory role of the most produced form of lactoferrin expressed in various expression systems (Fe-saturated recombinant human Lf, rhLf) and its hydrolysate in concentrations resembles that found in mature human milk. Co-culture model consisted of CaCo-2 and RAW 246.7 cell lines was used to evaluate the potential anti-inflammatory activity of rhLf and its hydrolysate. During this experiment, CaCo-2 monolayer permeability and integrity was assayed through the measurement of transepithelial electrical resistance (TEER values). Also, the production of reactive oxygen species (ROS), nitric oxide (NO) and different cytokines (IL-8, IL-1β, IL-6, IL-10, IL-12p70, and TNF-α) were measured. The treatment with rhLf and its hydrolysate protected the monolayer integrity against LPS effect and reduced IL-8 and ROS production. This effect was dependent on the dose and 2mgmL^-1 of rhLf hydrolysate was more effective. The addition of rhLf and its hydrolysate to infant formula is a prominent step towards improving both infant formula functionality and newborn health. Thus, these functional ingredients could be incorporated in infant foods. In this context, ongoing researches are conducted to clarify this effect whether by using synthetic peptides or by using LPS-sepsis animal.

Antibacterial Activity of AI-Hemocidin 2, a Novel N-Terminal Peptide of Hemoglobin Purified from Arca inflata

The continued emergence of antibiotic resistant bacteria in recent years is of great concern. The search for new classes of antibacterial agents has expanded to non-traditional sources such as shellfish. An antibacterial subunit of hemoglobin (Hb-I) was purified from the mantle of Arca inflata by phosphate extraction and ion exchange chromatography. A novel antibacterial peptide, AI-hemocidin 2, derived from Hb-I, was discovered using bioinformatics analysis. It displayed antibacterial activity across a broad spectrum of microorganisms, including several Gram-positive and Gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 37.5 to 300 μg/mL, and it exhibited minimal hemolytic or cytotoxic activities. The antibacterial activity of AI-hemocidin 2 was thermostable (25–100 °C) and pH resistant (pH 3–10). The cellular integrity was determined by flow cytometry. AI-hemocidin 2 was capable of permeating the cellular membrane. Changes in the cell morphology were observed with a scanning electron microscope. Circular dichroism spectra suggested that AI-hemocidin 2 formed an α-helix structure in the membrane mimetic environment. The results indicated that the anti-bacterial mechanism for AI-hemocidin 2 occurred through disrupting the cell membrane. AI-hemocidin 2 might be a potential candidate for tackling antibiotic resistant bacteria.

A role for whey-derived lactoferrin and immunoglobulins in the attenuation of obesity-related inflammation and disease

Obesity is a strong predictive factor in the development of chronic disease and has now superseded undernutrition as a major public health issue. Chronic inflammation is one mechanism thought to link excess body weight with disease. Increasingly, the gut and its extensive population of commensal microflora are recognized as playing an important role in the development of obesity-related chronic inflammation. Obesity and a high fat diet are associated with altered commensal microbial communities and increased intestinal permeability which contributes to systemic inflammation as a result of the translocation of lipopolysaccharide into the circulation and metabolic endotoxemia. Various milk proteins are showing promise in the prevention and treatment of obesity and chronic low-grade inflammation via reductions in visceral fat, neutralization of bacteria at the mucosa and reduced intestinal permeability. In this review, we focus on evidence supporting the potential antiobesogenic and anti-inflammatory effects of bovine whey-derived lactoferrin and immunoglobulins.

Antimicrobial Activity of Lactoferrin-Related Peptides and Applications in Human and Veterinary Medicine

Antimicrobial peptides (AMPs) represent a vast array of molecules produced by virtually all living organisms as natural barriers against infection. Among AMP sources, an interesting class regards the food-derived bioactive agents. The whey protein lactoferrin (Lf) is an iron-binding glycoprotein that plays a significant role in the innate immune system, and is considered as an important host defense molecule. In search for novel antimicrobial agents, Lf offers a new source with potential pharmaceutical applications. The Lf-derived peptides Lf(1-11), lactoferricin (Lfcin) and lactoferrampin exhibit interesting and more potent antimicrobial actions than intact protein. Particularly, Lfcin has demonstrated strong antibacterial, anti-fungal and antiparasitic activity with promising applications both in human and veterinary diseases (from ocular infections to osteo-articular, gastrointestinal and dermatological diseases).

Screening the anti infectivity potentials of native N- and C-lobes derived from the camel lactoferrin against hepatitis C virus

BACKGROUND

Hepatitis C virus (HCV) infection represents a worldwide health threat that still needs efficient protective vaccine and/or effective drug. The traditional medicine, such as camel milk, is heavily used by the large sector of HCV patients to control the infection due to the high cost of the available standard therapy. Camel milk contains lactoferrin, which plays an important and multifunctional role in innate immunity and specific host defense against microbial infection. Continuing the analysis of the effectiveness of camel lactoferrin against HCV, the current study aimed to separate and purify the native N- and C-lobes from the proteolytically cleaved camel lactoferrin (cLF) and to compare their in vitro activities against the HCV infection in Huh7.5 cells in order to determine the most active domain.

METHODS

Lactoferrin and its digested N- and C-lobes were purified by Mono S 5/50 GL column and Superdex 200 5/150 column. The purified proteins were assessed through three venues: 1. To inhibit intracellular replication, HCV infected cells were treated with the proteins at different concentrations and time intervals; 2. The proteins were directly incubated with the viral particles (neutralization) and then such neutralized viruses were used to infect cells; 3. The cells were protected with proteins before exposure to the virus. The antiviral potentials of the cLf and its lobes were determined using three techniques: 1. RT-nested PCR, 2. Real-time PCR, and 3. Flow cytometry.

RESULTS

N- and C-lobes were purified in two consecutive steps; using Mono-S and Superdex 200 columns. The molecular mass of N- and C-lobes was about 40 kDa. cLF and its lobes could prevent HCV entry into Huh 7.5 cells with activity reached 100% through direct interaction with the virus. The inhibition of intracellular viral replication by N-lobe is 2-fold and 3-fold more effective than that of the cLF and C-lobe, respectively.

CONCLUSION

Generated native N- and C-lobes from camel lactoferrin demonstrated a range of noticeably different potentials against HCV cellular infectivity. The anti-HCV activities were sorted as N-lobe > cLf > C-lobe.