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PubMed2005

Bovine lactoferrin peptidic fragments involved in inhibition of Echovirus 6 in vitro infection.

Bovine lactoferrin is a multifunctional glycoprotein folded in two symmetric globular lobes (N- and C-lobes), each being able to bind one ferric ion. We have previously demonstrated that this protein is able to prevent echovirus-induced apoptosis. In the present study, we have investigated both the role of tryptic fragments of bovine lactoferrin and the mechanism of lactoferrin effect on echovirus infection. Results obtained showed that bovine lactoferrin inhibits echovirus-induced cytopathic effect and antigen synthesis in a dose-dependent manner and that this protein is able to prevent viral replication when added not only during the entire cycle of infection but also before, during or after the viral adsorption step. The N-terminal cationic peptide was sufficient to prevent viral binding. Our data suggest that lactoferrin inhibition of echovirus attachment to cell receptors could be mediated by the cluster of positive charges at its N-terminus (lactoferricin).

Animals↗

PubMed2006

Lactoferrin inhibits early steps of human BK polyomavirus infection.

Lactoferrin, a member of the transferrin family, is a bi-globular iron binding glycoprotein, found in milk, exocrine secretions of mammals, and in secondary granules of polymorphonuclear neutrophiles that plays an important role in the defence against various pathogenic microorganisms. Previous studies in different virus-cell systems showed that lactoferrin is a potent inhibitor of different enveloped and naked virus infection. In this research we studied the effect of lactoferrin on BK polyomavirus, a human naked double-stranded DNA virus responsible for productive, persistent, and latent infections of the urinary tract. Results obtained demonstrate that lactoferrin treatment prevents early steps of BK virus infection in Vero cells, at the level of the adsorption phase, probably through the interaction with capsidic structures, although a lactoferrin-BK virus competition for cell plasma-membrane receptors cannot be ruled out.

Animals↗

PubMed2004

Lactoferrin modifies apoptosis-related gene expression in the colon of the azoxymethane-treated rat.

Lactoferrin, an iron-binding glycoprotein, exhibits suppressive effects on development of azoxymethane (AOM)-induced tumors in the rat colon, but the mechanisms are largely unknown. In this study, we investigated the effect of lactoferrin on the gene expression of 10 apoptosis-related molecules in colon mucosa of AOM-treated rats during early and late stages of colon carcinogenesis by reverse transcription PCR. Here we document that a death-inducing receptor, Fas, and a pro-apoptotic Bcl-2 family member, Bid, are increased in the colon mucosa in proportion to decreases in AOM-induced aberrant crypt foci by lactoferrin. Similarly, increased expression of the pro-apoptotic Bcl-2 family member, Bax, was also observed in AOM-induced tumors in rats fed by lactoferrin. These results indicate that Fas and pro-apoptotic Bcl-2 members participate in the lactoferrin action and may contribute to suppressive effects on tumor development in the rat colon.

Administration, Oral↗

PubMed2006

Induction of lactoferrin and IL-8 release from human neutrophils by tryptic enzymes via proteinase activated receptor-2.

Tryptic enzymes such as tryptase, trypsin and thrombin are reportedly able to alter neutrophil behavior. However, little is known of the influence of these proteinases on lactoferrin or IL-8 release from neutrophils. In the present study, we investigated the effects of tryptase, trypsin, thrombin and elastase, and agonist peptides of PAR-1 SFLLR-NH(2) and PAR-2 SLIGKV-NH(2) and tc-LIGRLO-NH(2) on lactoferrin and IL-8 release from highly purified human neutrophils. Flow cytometry shows CD16(+) neutrophils express PAR-1 and PAR-2, but not PAR-3 and PAR-4 proteins. RT-PCR analysis reveals that neutrophils express only PAR-2 genes. Tryptase and trypsin, but not thrombin and elastase, induced significant lactoferrin and IL-8 secretion from neutrophils. SLIGKV-NH(2) and tc-LIGRLO-NH(2), but not SFLLR-NH(2), also stimulated lactoferrin and IL-8 secretion from neutrophils. In conclusion, only a proportion of neutrophils express PAR-1 and/or PAR-2. Tryptase and trypsin-induced lactoferrin and IL-8 secretion from neutrophils most likely occur through activation of PAR-2.

Humans↗

PubMed2005

Inhibitory activity of bovine lactoferrin against echovirus induced programmed cell death in vitro.

Lactoferrin is a glycoprotein and plays an important role in defence against pathogens. Although the antiviral activity of lactoferrin is one of the major biological functions of such protein, the mechanism of action is still under debate. The effect of lactoferrin on echovirus 6 infection in vitro was analysed and results showed that (i) cells infected with echovirus 6, died as a result of apoptosis and that (ii) programmed cell death was inhibited by lactoferrin treatment. In this report, we demonstrate that lactoferrin can exert its anti-enteroviral activity by preventing viral-induced apoptosis.

Animals↗

PubMed2005

Lactoferrin augments BCG vaccine efficacy to generate T helper response and subsequent protection against challenge with virulent Mycobacterium tuberculosis.

The ability to control intracellular Mycobacterium tuberculosis (MTB) infection relies on cellular immunity and generation of a strong T-cell helper 1 (T(H)1) response. Lactoferrin, an iron-binding protein with immune regulatory functions, was investigated as an adjuvant to boost Mycobacterium bovis Bacillus Calmette-Guerin (BCG) efficacy. Lactoferrin was initially shown to augment IL-12(p40) production from macrophages stimulated with LPS. A single immunization of mice with Lactoferrin as an adjunct adjuvant resulted in amplified splenocyte proliferative response to heat-killed BCG, and elevated IL-12(p40) production with increased relative ratios of IL-12/IL-10. Furthermore, splenocyte recall response to HK-BCG was augmented for proinflammatory mediators, TNF-alpha, IL-1beta, and IL-6, approaching responses generated to complete Freund's adjuvant (CFA) immunized controls. Specific responses were identified, with significant elevation of IFN-gamma generated during antigenic recall. Subsequent aerosol challenge of Lactoferrin adjuvant immunized mice with virulent M. tuberculosis revealed decreased mycobacterial loads in the lung, and limitation of organism dissemination to a peripheral organ (spleen). These studies indicate that Lactoferrin can act as an adjunct adjuvant to augment cellular immunity and boost BCG efficacy for protection against subsequent challenge with virulent MTB.

Animals↗

PubMed2006

The cytotoxic effects of human neutrophil peptide-1 (HNP1) and lactoferrin on oral squamous cell carcinoma (OSCC) in vitro.

Alpha-defensin or human neutrophil peptide-1 (HNP1) is a neutrophil-derived antimicrobial peptide with cytotoxic effects towards cancer cells. Lactoferrin is also stored in human neutrophils and is a glycoprotein involved in mediating cytotoxicity towards tumour cells. This study investigated the sensitivity of normal oral keratinocyte and oral squamous cell carcinoma (OSCC) cells to HNP1 and lactoferrin in various combinations. A concentration of 100 microg/ml HNP1 induced the most significant cytotoxic effect on both normal and OSCC cells. Lactoferrin (12.5, 25 and 250 microg/ml) also significantly induced cell death in OSCC cells after 72 h. Of note, a combination of 10 microg/ml HNP1 and 50 microg/ml lactoferrin induced a differential effect, not observed with either concentration alone, which stimulated proliferation in normal cells, but induced cell death in OSCC cells throughout the study. These results indicate a potentially important co-operative role for HNP1 and lactoferrin in facilitating a selective cytotoxic effect on tumour cells.

Carcinoma, Squamous Cell↗

PubMed1980

Lactoferrin in human ocular tissues.

The main lacrimal gland and accessory lacrimal tissue from seven autopsy cases, lacrimal biopsy specimens from three patients, and conjunctival biopsy specimens from ten patients were examined for lactoferrin by an immunohistologic technique. Lactoferrin was identified and localized to acinar epithelial cells of both main and accessory lacrimal tissue. Lactoferrin was not found in conjunctival tissue except within conjunctival neutrophils. Other possible sources of human tear lactoferrin were considered, but we concluded from our data that the primary source of lactoferrin in normal human tears is the acinar epithelium of the main and accessory lacrimal glands.

Adult↗

PubMed2003

An intronic alternative promoter of the human lactoferrin gene is activated by Ets.

Lactoferrin expresses in a variety of tissues and involves in various aspects of host defense mechanisms. The lactoferrin gene is differentially regulated through multiple signaling pathways. Recently, an alternative form of human lactoferrin mRNA (Delta LF) was found in normal human tissues but absent from the tumor cells. In this study, we identified the transcription start sites of the Delta LF in mammary gland and bone marrow and demonstrated that the Delta LF is the product of an alternative (P2) promoter present in the first intron of the lactoferrin gene. The P2 promoter has high activity in Jurkat and U937 and low activity in RL95-2 and HEC-1B cell lines. Nonetheless, the promoter activity in HEC-1B cells was dramatically enhanced with overexpression of the Ets-1 transcription factor. The GFP-tagged lactoferrin is present in the cytoplasm whereas GFP-tagged Delta LF is found in both nucleus and cytoplasm as examined by fluorescence and confocal microscopy.

Cell Line↗

PubMed1990

The effect of bovine lactoferrin on muscle growth in vivo and in vitro.

Lactoferrin was found to be a potent stimulator of proliferation for L6 myoblasts. Both apo and holo-forms of lactoferrin were equipotent. By contrast, only the holo-form of transferrin (a structurally related iron binding protein) stimulated proliferation, apo-transferrin was without activity. Holo-transferrin was also less stimulatory than lactoferrin. Purified lactoferrin was administered to mature female rats and to neonatal rats by daily subcutaneous injection to determine if there was a measurable effect on muscle cell growth in vivo. Results from the in vivo studies suggest that lactoferrin has little or no effect on muscle cell growth in the whole animal.

Animals↗

PubMed1991

Metal ligand-induced alterations in the surface structures of lactoferrin and transferrin probed by interaction with immobilized copper(II) ions.

We have evaluated immobilized Cu(II) ions as a potential site-directed molecular probe to monitor ligand-induced alterations in protein surface structures. Metal ion-induced alterations in the surface structures of different lactoferrins (human and porcine), transferrins (human and rabbit), and ovotransferrin (chicken) were examined. Although these 78,000-dalton glycoproteins are related gene products with similar overall structure and function, they differ greatly in the number and distribution of surface-exposed electron-donor groups thought to interact with Cu(II) ions. Each of these proteins interacted with immobilized Cu(II) ions through sites which are distinct from the two specific high affinity metal binding sites identified for iron. In both the presence and absence of bound iron, transferrins interacted more strongly with the immobilized Cu(II) ions than did lactoferrins; ovotransferrin interacted only weakly. Although iron binding increased the affinities of lactoferrins for immobilized Cu(II), iron binding decreased the affinities of transferrins and ovotransferrin for immobilized Cu(II) ions. Iron-saturated and iron-free lactoferrins were resolved by pH gradient elution, but only in the presence of 3 M urea; they were not resolved by imidazole affinity elution. Conversely, the iron-saturated and iron-free forms of transferrin were only separated by imidazole affinity elution. Urea did not influence the resolution of apo and holo ovotransferrins by imidazole. The differential effects of urea and imidazole suggest the participation of different types of surface electron-donor groups. The progressive site-specific modification of surface-exposed histidyl residues by carboxyethylation revealed several lactoferrin forms of intermediate affinity for immobilized iminodiacetate-Cu(II) ions. In summary, independent of species, the affinity for immobilized Cu(II) ions increased as follows: iron-saturated ovotransferrin less than metal-free ovotransferrin less than apolactoferrin less than hololactoferrin much less than diferric or holotransferrin less than monoferric transferrin less than apotransferrin. We have demonstrated the use of immobilized Cu(II) ions to distinguish and to monitor ligand-induced alterations in protein surface structure. The results are discussed in relation to protein surface-exposed areas of electron-donor groups.

Animals↗

PubMed2002

Antiadenovirus activity of milk proteins: lactoferrin prevents viral infection.

Different milk proteins were analysed for their inhibitory effect on adenovirus infection in vitro. Proteins investigated were mucin, alpha-lactalbumin, beta-lactoglobulin, bovine lactoferrin, and human lactoferrin. Results obtained demonstrated that mucin, alpha-lactalbumin, and beta-lactoglobulin did not prevent the viral cytopathic effect, whereas lactoferrin was able to inhibit adenovirus replication in a dose-dependent manner. Further experiments were carried out in which lactoferrin was added to the cells during different phases of viral infection. Results obtained showed that lactoferrin was able to prevent viral replication when added both before, or during the viral adsorption step, or when present during the entire replicative cycle of adenovirus, demonstrating that its action takes place on an early phase of viral replication.

Adenovirus Infections, Human↗

PubMed2004

Enhancement of nisin, lysozyme, and monolaurin antimicrobial activities by ethylenediaminetetraacetic acid and lactoferrin.

A microtiter plate assay was employed to systematically assess the interaction between ethylenediaminetetraacetic acid (EDTA) or lactoferrin and nisin, lysozyme, or monolaurin against strains of Listeria monocytogenes, Escherichia coli, Salmonella enteritidis, and Pseudomonas fluorescens. Low levels of EDTA acted synergistically with nisin and lysozyme against L. monocytogenes but EDTA and monolaurin interacted additively against this microorganism. EDTA synergistically enhanced the activity of nisin, monolaurin, and lysozyme in tryptic soy broth (TSB) against two enterohemorrhagic E. coli strains. In addition, various combinations of nisin, lysozyme, and monolaurin with EDTA were bactericidal to some gram-negative bacteria whereas none of the antimicrobials alone were bactericidal. Lactoferrin alone (2000 microg ml(-1)) did not inhibit any of the bacterial strains, but did enhance nisin activity against both L. monocytogenes strains. Lactoferrin in combination with monolaurin inhibited growth of E. coli O157:H7 but not E. coli O104:H21. While lactoferrin combined with nisin or monolaurin did not completely inhibit growth of the gram-negative bacteria, there was some growth inhibition. All combinations of EDTA or lactoferrin with antimicrobials were less effective in 2% fat UHT milk than in TSB. S. enteritidis and P. fluorescens strains were consistently more resistant to antimicrobial combinations. Resistance may be due to differences in the outer membrane and/or LPS structure.

Animals↗

PubMed1999

Characterization of Korean native goat lactoferrin.

We purified lactoferrin from the colostrum of the Korean native goat (Capra hircus) by ion-exchange chromatography using CM-Toyopearl 650M followed by affinity chromatography on AF-Heparin Toyopearl 650M. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis suggested the molecular mass of Korean native goat lactoferrin is 82 kDa with an iron saturation of 30% as estimated by spectroscopic analysis. Circular dichroism analysis shows goat lactoferrin molecule contains 24.5%, alpha-helix; 36.0%, beta-structure; 13.5%, beta-turn and 26.0%, unordered structure. Heparin binding affinity is the same as that of bovine lactoferrin, but lower than that of human lactoferrin. An analysis using synthetic peptides shows that the peptide from residue 22 to 31--WQRRMRKLGA--exerts a positive heparin-binding ability.

Animals↗

PubMed2002

Expression, purification, and characterization of equine lactoferrin in Pichia pastoris.

Lactoferrin is an 80kDa iron-binding glycoprotein. It is secreted by exocrine glands. Many functions such as iron sequestering, anti-bacterial activity, regulation of gene expression, and immunomodulation are attributed to it. In the present study, we report the production of recombinant equine lactoferrin (ELF) in the methylotropic yeast Pichia pastoris using pPIC9K vector. The recombinant protein was purified by one-step affinity chromatography using heparin-Sepharose column. The purified protein has a molecular weight of 80kDa and reacted with antibody raised against the native equine lactoferrin. Its N-terminal sequence was identical to that of the native ELF. The iron-binding behavior and circular dichroism studies of the purified protein indicate that it has folded properly. The recombinant protein appears to be hyperglycosylated by the host strain, GS115. This is the first heterologous expression of equine lactoferrin and also the first report of intact lactoferrin expression using P. pastoris system. An yield of 40mg/l obtained in shake-flask cultures with this system, which is higher than the reported values for other systems.

Amino Acid Sequence↗

PubMed2000

Metal complexes of lactoferrin and their effect on the intracellular multiplication of Legionella pneumophila.

The action of bovine lactoferrin saturated with iron, zinc and manganese on the intracellular multiplication of Legionella pneumophila in HeLa cells has been tested. The results obtained showed that lactoferrin did not influence the invasive efficiency of Legionella. The intracellular multiplication of the bacterium was inhibited by apo-lactoferrin and by lactoferrin saturated with manganese and zinc, whereas lactoferrin saturated with iron enhanced the intracellular growth. Experiments in parallel were performed with iron, manganese and zinc citrate to test the effect due to the metal ions alone. Even in this condition the addition of an iron chelate enhanced the multiplication of Legionella while the manganese chelate produced a certain inhibition.

Animals↗

PubMed2001

N-glycosylation potential of maize: the human lactoferrin used as a model.

In order to determine the N-glycosylation potential of maize, a monocotyledon expression system for the production of recombinant glycoproteins, human lactoferrin was used as a model. The human lactoferrin coding sequence was inserted into the pUC18 plasmid under control of the wheat glutenin promoter. Maize was stably transformed and recombinant lactoferrin was purified from the fourth generation seeds. Glycosylation was analysed by gas chromatography, lectin detection, glycosidase digestions and mass spectrometry. The results indicated that both N-glycosylation sites of recombinant lactoferrin are mainly substituted by typical plant paucimannose-type glycans, with beta1,2-xylose and alpha1,3-linked fucose at the proximal N-acetylglucosamine, and that complex-type glycans with Lewis(a) determinants are not present in maize recombinant lactoferrin.

Blotting, Western↗

PubMed2004

Lactoferrin reduces methotrexate-induced small intestinal damage, possibly through inhibition of GLP-2-mediated epithelial cell proliferation.

A strategy protecting the small intestine against deleterious side effects associated with anti-cancer therapy is arresting epithelial cell cycling temporally. Since endogenous glucagon-like peptide-2 (GLP-2) is a trophic factor specific for intestinal epithelia, the possibility of inhibiting GLP-2-mediated cell proliferation by lactoferrin, thereby protecting the small intestine against deleterious side effects of anticancer therapy, was investigated. In Caco-2 cells, GLP-2-mediated proliferation was reduced in a dose-dependent manner using lactoferrin. Furthermore, in a rat model for methotrexate-induced mucositis, lactoferrin reduced BrdU incorporation in small intestinal epithelial cells, indicating inhibition of epithelial cell proliferation in vivo. Subsequently, protection against methotrexate-induced intestinal damage was found in corresponding regions. These results show, for the first time, that lactoferrin interferes with GLP-2-induced intestinal epithelial proliferation. It may therefore be hypothesized that lactoferrin protects the intestine against anticancer therapy-induced intestinal damage, via inhibition of GLP-2-induced small intestinal epithelial cell proliferation.

Animals↗