The physiology of lactoferrin

Interactions of caeruloplasmin with other proteins participating in inflammation

The first detailed report of a specific interaction of CP (caeruloplasmin) with another protein described its complex with LF (lactoferrin) in 2000. Since then, several protein–protein interactions involving CP have been reported, mostly concerning iron-containing proteins. The CP–LF complex was studied thoroughly, and evidence of reciprocal effects of CP and LF was obtained. Another specific interaction investigated in detail occurs between CP and MPO (myeloperoxidase). CP–LF, CP–MPO and CP–LF–MPO complexes were found in sera of patients with inflammation. Modelling in vitro allowed understanding of which structural peculiarities of CP and partners allow the modification of their functions in a complex. The present paper reviews the latest data on complexes of CP with LF and MPO, and advances some suggestions about their role in health and disease.

Impact of interfacial composition on physical stability and in vitro lipase digestibility of triacylglycerol oil droplets coated with lactoferrin and/or caseinate

The physicochemical and functional properties of oil-in-water emulsions can be controlled by engineering the interfacial layer coating the oil droplets. This study examined the impact of interfacial deposition of lactoferrin (LF) and/or caseinate (Cas) onto oil droplets stabilized by the opposite protein on emulsion stability and lipase digestibility. Zeta potential measurements show both proteins can be deposited on droplet surfaces coated with the opposite protein. Secondary emulsion formulations containing droplets coated with mixed caseinate-lactoferrin layers (Cas-LF and LF-Cas emulsions) had enhanced stability to flocculation in 3 < pH < 7 and from 0 to 80 mM calcium chloride. The majority of emulsions studied were rapidly digested by lipase in an in vitro digestion model, demonstrating the improved secondary formulations are not expected to alter lipid bioavailability. This work provides information valuable in the design of emulsion formulations for applications in the food, pharmaceutical, and personal care industries.

Fabrication and morphological characterization of biopolymer particles formed by electrostatic complexation of heat treated lactoferrin and anionic polysaccharides

Biopolymer particles fabricated from proteins and/or polysaccharides can be used to encapsulate functional components or to modify various functional properties of materials. In this study, sub-micrometer biopolymer particles were fabricated by electrostatic complexation of heat-denatured protein (lactoferrin, LF) particles with anionic polysaccharides (alginate, carrageenan, or pectin). The aim of the study was to exploit macromolecular electrostatic interactions to form sub-micrometer sized particles and study their stability and morphological characteristics. Initially, protein particles were formed by heat treatment (91 degrees C, 20 min) of a lactoferrin solution (0.2% LF, pH 7), which led to a suspension of protein particles with mean diameter of 200-400 nm and isoelectric point of pI approximately 8.5. Biopolymer particles were then formed by mixing the protein particles with anionic polysaccharides at pH 8 and then lowering the pH to promote electrostatic deposition of polysaccharides onto the protein particle surfaces. The influence of pH (2-11) and ionic strength (0-200 mM NaCl) on the properties and stability of the complexes was studied using turbidity, dynamic light scattering, and electrophoresis measurements. Relatively stable particles could be formed from pH 5 to 8, but appreciable aggregation occurred at lower pH which was attributed to charge neutralization and bridging effects. LF-pectin complexes were relatively stable to salt addition, but LF-carrageenan and LF-alginate complexes exhibited aggregation at higher salt concentrations. These results have important implications for the application of lactoferrin-polysaccharide complexes as functional components in commercial products, such as pharmaceuticals, personal care products, and foods.

E2F1-directed activation of Bcl-2 is correlated with lactoferrin-induced apoptosis in Jurkat leukemia T lymphocytes

Lactoferrin (Lf) has been shown to control the proliferation of a variety of mammalian cells. Recently, we reported that human Lf induces apoptosis via a c-Jun N-terminal kinases (JNK)-associated Bcl-2 pathway that stimulates programmed cell death. In order to gain insight into the mechanism underlying Lf-triggered apoptotic features, we attempted to determine the mechanisms whereby the Lf-induced Bcl-2 family proteins exert their pro- or anti-apoptotic effects in Jurkat leukemia T lymphocytes. Treatment of the cells with high concentrations of Lf resulted in a significant reduction in in vitro growth and cell viability. As the levels of Lf increased, greater quantities of CDK6 and hyper-phosphorylated retinoblastoma protein were produced, resulting in the induction of E2F1-dependent apoptosis. Simultaneously, PARP and caspases were efficiently cleaved during Lf-induced apoptosis. The E2F1-induced apoptotic process occurred preferentially in p53-deficient Jurkat leukemia cells. Therefore, we attempted to determine whether E2F1-regulated Bcl-2 family proteins involved in the apoptotic process were relevant to Lf-induced apoptosis. We found that Lf increased the interaction of Bcl-2 with the pro-apoptotic protein Bad, whereas the total protein levels did not change significantly. Our results, collectively, suggest that Lf exploits the control mechanism of E2F1-regulated target genes or Bcl-2 family gene networks involved in the apoptotic process in Jurkat human leukemia T lymphocytes.

Lactoferrin protects against concanavalin A-induced liver injury in mice

BACKGROUND

Liver diseases, caused by viral infection, autoimmune conditions, alcohol ingestion or the use of certain drugs, are a significant health issue, as many can develop into liver failure. Lactoferrin (Lac) is an iron-binding glycoprotein that belongs to the transferrin family. Owing to its multiple biological functions, Lac has been evaluated in a number of clinical trials to treat infections, inflammation and cancer.

AIM

The present study aims to reveal a profound hepatoprotective effect of Lac, using a mouse model of Concanavalin A (Con A)-induced hepatitis, which mimics the pathophysiology of human viral and autoimmune hepatitis.

METHOD

C57Bl/6J mice were injected with bovine Lac following Con A challenge. The effects of Lac on interferon (IFN)-gamma and interleukin (IL)-4 expression were determined. The roles of Lac on T-cell apoptosis and activation, and leukocytes infiltration were examined.

RESULT

The data demonstrated that the protective effect of Lac was attributed to its ability to inhibit T-cell activation and production of IFN-gamma, as well as to suppress IL-4 production by hepatic natural killer T cells.

CONCLUSION

These findings indicate a great therapeutic potential of Lac in treating in treating inflammatory hepatitis and possibly other inflammatory diseases.

Lactoferrin in canine sera: a pyometra study

The concentration of lactoferrin was measured in canine sera from groups of healthy male dogs as well as pregnant and non-pregnant female dogs and was compared with that of bitches with pyometra. Lactoferrin concentrations were higher in bitches with pyometra. The role of elevated lactoferrin concentrations in the suppression of lymphocyte activity was examined in sera from bitches with pyometra in a series of investigations. Although the sera from bitches with pyometra were capable of suppressing lymphocyte activity, lactoferrin was not found to be involved in this action.

A preliminary approach to creating an overview of lactoferrin multi-functionality utilizing a text mining method

Lactoferrin is a multi-functional metal-binding glycoprotein that exhibits many biological functions of interest to many researchers from the fields of clinical medicine, dentistry, pharmacology, veterinary medicine, nutrition and milk science. To date, a number of academic reports concerning the biological activities of lactoferrin have been published and are easily accessible through public data repositories. However, as the literature is expanding daily, this presents challenges in understanding the larger picture of lactoferrin function and mechanisms. In order to overcome the "analysis paralysis" associated with lactoferrin information, we attempted to apply a text mining method to the accumulated lactoferrin literature. To this end, we used the information extraction system GENPAC (provided by Nalapro Technologies Inc., Tokyo). This information extraction system uses natural language processing and text mining technology. This system analyzes the sentences and titles from abstracts stored in the PubMed database, and can automatically extract binary relations that consist of interactions between genes/proteins, chemicals and diseases/functions. We expect that such information visualization analysis will be useful in determining novel relationships among a multitude of lactoferrin functions and mechanisms. We have demonstrated the utilization of this method to find pathways of lactoferrin participation in neovascularization, Helicobacter pylori attack on gastric mucosa, atopic dermatitis and lipid metabolism.

Lactoferrin protects against acetaminophen-induced liver injury in mice

Acetaminophen-induced liver injury (AILI) is a significant health problem and represents the most frequent cause of drug-induced liver failure in the United States. The development and implementation of successful therapeutic intervention strategies have been demanding, due to significant limitations associated with the current treatment for AILI. Lactoferrin (Lac), a glycoprotein present in milk, has been demonstrated to possess a multitude of biological functions. Our study demonstrated a profound protective effect of Lac in a murine model of AILI, which was not dependent on its iron-binding ability, inhibition of acetaminophen (APAP) metabolism, or a direct cytoprotective effect on hepatocytes. Instead, Lac treatment significantly attenuated APAP-induced liver sinusoidal endothelial cell dysfunction and ameliorated hepatic microcirculation disorder. This protective effect of Lac appeared to be dependent on hepatic resident macrophages (Kupffer cells [KCs]).

CONCLUSION

Collectively, our data indicate that Lac, through activation of KCs, inhibited APAP-induced liver sinusoidal endothelial cell damage and improved hepatic congestion, thereby protecting against AILI. These findings reveal the significant therapeutic potential of Lac during AILI and other types of liver diseases.

Microbicidal effect of the lactoferrin peptides lactoferricin17-30, lactoferrampin265-284, and lactoferrin chimera on the parasite Entamoeba histolytica

Entamoeba histolytica is a parasitic protozoan that produces amoebiasis, an intestinal disease characterized by ulcerative colitis and dysentery. In some cases, trophozoites can travel to the liver leading to hepatic abscesses and death. Recently, lactoferrin and lactoferricin B have been shown to be amoebicidal in axenic cultures. The aim of this work was to determine whether the lactoferrin-peptides lactoferricin amino acids 17-30, lactoferrampin amino acids 265-284, and lactoferrin chimera which is a fusion product of the two peptides, are capable of producing a microbicidal effect to trophozoites of E. histolytica. We evaluated the killing effect of these peptides in growth kinetics carried out in axenic culture medium to which different concentrations of peptides were added. At 50 muM of peptide concentration, lactoferricin and lactoferrampin had a moderate amoebicidal effect, since a 45-50% of trophozoites remained viable at 24 h culture. However, at 50 microM of the lactoferrin chimera 75% amoeba were killed whereas at 100 microM all cells died. These data indicate that of lactoferrin-peptides mainly the chimera have amoebicidal activity in a time- and concentration-dependent manner. The lactoferrin-peptides might be useful as therapeutic agents against amoebiasis and thereby diminish the use of metronidazole, which is extremely toxic for the host.

Inhibitory effect of lactoferrin on hypertrophic differentiation of ATDC5 mouse chondroprogenitor cells

The skeleton is formed by two different mechanisms. In intramembranous ossification, osteoblasts form bone directly, whereas in endochondral ossification, chondrocytes develop a cartilage template, prior to osteoblast-mediated skeletogenesis. Lactoferrin is an iron-binding glycoprotein belonging to the transferrin family. It is known to promote the growth and differentiation of osteoblasts. In this study, we investigated the effects of bovine lactoferrin on the chondrogenic differentiation of ATDC5 chondroprogenitor cells. This mouse embryonic carcinoma-derived clonal cell line provides an in vitro model of chondrogenesis. Lactoferrin treatment of differentiating ATDC5 cells promoted cell proliferation in the initial stage of the differentiation process. However, lactoferrin treatment resulted in inhibition of hypertrophic differentiation, characterized by suppression of alkaline phosphatase activity, aggrecan synthesis and N-cadherin expression. This inhibitory effect was accompanied by sustained Sox9 expression, as well as increased Smad2/3 expression and phosphorylation, suggesting that lactoferrin regulates chondrogenic differentiation by up-regulating the Smad2/3-Sox9 signaling pathway.

Immunolocalization of lactoferrin in cartilage-forming neoplasms

BACKGROUND

Lactoferrin (Lf) is an 80-kDa basic glycoprotein, a member of the transferrin family of iron-binding proteins. Lf immunoreactivity has been extensively investigated in many neoplastic tissues. Recently, Lf expression was documented in the osteoblastic lineage of bone-forming tumors as well as in osteoblasts of fetal bone.

METHODS

Lactoferrin (Lf) immunoexpression was investigated in 30 human cartilage-forming tumors [15 enchondromas, 6 osteochondromas, 3 chondroblastomas (CBL), 3 chondrosarcomas, and 3 chondromyxoid fibromas (CMF)] as well as in human normal bone specimens and cartilaginous tissues obtained at autopsy from 5 adults and 3 fetuses.In addition, the immunohistochemical expression of Ki-67 antigen was analyzed on parallel sections from the same specimens. Quantification of Lf immunoreactivity was performed by using an intensity distribution (ID) score.

RESULTS

Lf immunoexpression with a variable ID score was encountered exclusively in 3 of 3 chondroblastomas and in 3 of 3 chondromyxoid fibromas. Lf immunoreactivity in these tumors, in clear contrast with the Lf absence in enchondromas, osteochondromas, and chondrosarcomas, may suggest a different histogenesis of the former. In agreement with this histogenetic origin, we detected Lf in the chondroblasts and osteoblasts within the fetal tissue, whereas no immunoreactivity was found in the corresponding adult cells. No significant associations were found between the Lf immunoexpression and the Ki 67 LI of the tumors of our series.

CONCLUSIONS

The presence of Lf in neoplastic cells of CBL and CMF, as well as in fetal cartilaginous tissue, may reflect a less mature phenotype of these tumors.

Lactoferrin modulation of BCG-infected dendritic cell functions

Lactoferrin, an 80-kDa iron-binding protein with immune modulating properties, is a unique adjuvant component able to enhance efficacy of the existing Mycobacterium bovis Bacillus Calmette Guerin (BCG) vaccine to protect against murine model of tuberculosis. Although identified as having effects on macrophage presentation events, lactoferrin's capability to modulate dendritic cells (DCs) function when loaded with BCG antigens has not been previously recognized. In this study, the potential of lactoferrin to modulate surface expression of MHC II, CD80, CD86 and CD40 from bone marrow-derived dendritic cells (BMDCs) was examined. Generally, lactoferrin decreased pro-inflammatory cytokines [tumor necrosis factor (TNF)-alpha, IL-6 and IL-12p40] and chemokines [macrophage inflammatory protein (MIP)-1alpha and MIP-2] and increased regulatory cytokine, transforming growth factor-beta1 and a T-cell chemotatic factor, monocyte chemotactic protein-1, from uninfected or BCG-infected BMDCs. Culturing BCG-infected BMDCs with lactoferrin also enhanced their ability to respond to IFN-gamma activation through up-regulation of maturation markers: MHC I, MHC II and the ratio of CD86:CD80 surface expression. Furthermore, lactoferrin-exposed BCG-infected DCs increased stimulation of BCG-specific CD3(+)CD4(+) splenocytes, as defined by increasing IFN-gamma production. Finally, BCG-/lactoferrin-vaccinated mice possessed an increased pool of BCG antigen-specific IFN-gamma producing CD3(+)CD4(+)CD62L(-) splenocytes. These studies suggest a mechanism in which lactoferrin may exert adjuvant activity by enhancing DC function to promote generation of antigen-specific T cells.

Iron-saturated lactoferrin stimulates cell cycle progression through PI3K/Akt pathway

Iron binding lactoferrin (Lf) is involved in the control of cell cycle progression. However, the molecular basis underlying the effects of Lf on cell cycle control, as well as its target genes, remains incompletely understood. In this study, we have demonstrated that a relatively low level of ironsaturated Lf, Lf(Fe(3+)), can stimulate S phase cell cycle entry, and requires Akt activation in MCF-7 cells. Lf(Fe(3+)) immediately induced Akt phosphorylation at Ser473, which subsequently induced the phosphorylation of two G1-checkpoint Cdk inhibitors, p21(Cip/WAF1) and p27(kip1). The Lf(Fe(3+))-induced phosphorylation of Cdk inhibitors impaired their nuclear import behavior, thereby inducing cell cycle progression. However, the treatment of cells with a PI3K inhibitor, LY294002, almost completely blocked Lf(Fe(3+))-stimulated cell cycle progression. LY294002 treatment abrogated Lf(Fe(3+))-induced Akt activation, and prevented the cytoplasmic localization of p27(kip1). Higher levels of p21(Cip/WAF1) were also detected in the cytoplasmic sub-cellular compartment as a measure of cellular response to Lf(Fe(3+)). Consequently, the degree of phosphorylation of retinoblastoma protein was enhanced in response to Lf(Fe(3+)). Therefore, we conclude that Lf(Fe(3+)), as a potential antagonist of Cdk inhibitors, can facilitate the functions of E2F during progression to S phase via the Akt signaling pathway.

Histological and immunohistochemical evaluation of duodenal and colonic biopsies after oral bovine lactoferrin supplementation in beagle puppies

Lactoferrin is a natural compound in the milk of mammals and was shown to influence the intestinal micro-flora and the immune system in mice, calves, dogs and man. The present study was carried out to investigate the effect of orally administered bovine lactoferrin (0, 30, 60 and 120 mg/kg DM feed) on the intestinal morphology and lymphocyte colonization in 36 motherless raised puppies. Endoscopic biopsies from duodenum and colon, taken in week 14, were scored histologically after staining with haematoxylin and eosin (H&E) and lymphocytes (CD3+, CD4+, CD8+) and plasma cells (IgA+, IgG+, IgM+) were enumerated after immunohistochemical staining by computer-aided quantification. Histological scoring revealed no significant differences amongst the groups. IgG+ plasma cells were reduced (p < 0.05) in the lamina propria of the colon of the 30 and the 60 mg group. The number of CD8+ lymphocytes was higher (p < 0.05) in the epithelium of the colon of the lactoferrin groups. In conclusion, this study indicated only minimal effects of bovine lactoferrin on the population of selected immune cells in the gut mucosa of puppies. More investigations are needed to describe the impact of lactoferrin on the digestive physiology of puppies.

Effect of lactoferrin-embedded collagen membrane on osteogenic differentiation of human osteoblast-like cells

Lactoferrin (LF) has the ability to promote the proliferation and differentiation of osteoblasts, suggesting its potential utility as an osteogenic growth factor in bone tissue engineering. However, this type of application requires improved drug delivery system (DDS) technology at the target site. In this study, we report enhanced calcium deposition and alkaline phosphatase (ALP) activity using the type I collagen membrane during osteogenic differentiation of MG63 human osteoblast-like cells, indicating that type I collagen not only acts as a site for calcification but also promotes the expression of differentiated phenotypes. We also used this membrane as a drug delivery carrier for bovine LF. Approximately 27% of LF embedded on the type I collagen membrane was released within the first hour in cell-free condition. This initial burst release of LF was followed by a slower release from the collagen membrane. Bovine LF embedded in the type I collagen membrane promoted its calcification during osteogenic differentiation of MG63 cells without the loss of LF bioactivity. Taken together, ALP activity and osteocalcin production were enhanced in the MG63 cells plated on the LF-embedded collagen membrane, suggesting that LF incorporated in the collagen membrane promoted bone-like tissue formation by MG63 cells. These observations suggest that the type I collagen membrane is useful as a drug delivery carrier for LF in bone tissue engineering.

Use and endocytosis of iron-containing proteins by Entamoeba histolytica trophozoites

Iron is essential for nearly all organisms; in mammals, it is part of proteins such as haemoglobin, and it is captured by transferrin and lactoferrin. Transferrin is present in serum, and lactoferrin is secreted by the mucosa and by neutrophils at infection sites, as a host iron-withholding response, sequestering iron away from invading microorganisms. Additionally, all cells contain ferritin, which sequesters iron when its intracellular levels are increased, detoxifying and preventing damage. Liver ferritin contains 50% of iron corporal reserves. During evolution, pathogens have evolved diverse strategies to obtain iron from their hosts in order to survive. The protozoan Entamoeba histolytica invades the intestinal mucosa, causing dysentery, and the trophozoites often travel to the liver producing hepatic abscesses; thus, intestine and liver proteins could be important iron supplies for E. histolytica. We found that E. histolytica trophozoites can grow in both ferrous and ferric iron, and that they can use haemoglobin, holo-transferrin, holo-lactoferrin, and ferritin as in vitro iron sources. These proteins supported the amoeba growth throughout consecutive passages, similarly to ferric citrate. By confocal microscopy and immunoblotting, iron-binding proteins were observed specifically bound to the amoeba surface, and they were endocytosed, trafficked through the endosomal/lysosomal route, and degraded by neutral and acidic cysteine-proteases. Transferrin and ferritin were mainly internalized through clathrin-coated vesicles, and holo-lactoferrin was mainly internalized by caveola-like structures. In contrast, apo-lactoferrin bound to membrane lipids and cholesterol, inducing cell death. The results suggest that in vivo trophozoites secrete products that can destroy enterocytes, erythrocytes, and hepatocytes, releasing transferrin, haemoglobin, ferritin, and other iron-containing proteins, which, together with lactoferrin derived from neutrophils and acinar cells, could be used as abundant iron supplies by amoebas.

Orally administered lactoferrin preserves bone mass and microarchitecture in ovariectomized rats

Lactoferrin (LF) is reported to stimulate osteoblast proliferation and inhibit osteoclast activity in bone cell culture. However, the effect of oral LF on bone in osteoporosis needs to be explored. Three-month-old female Sprague-Dawley rats (n = 70) were assigned to the following groups: sham-operated, ovariectomized (OVX) untreated, OVX + bovine serum albumin (BSA; 85 mg/kg body weight), OVX + LF (0.85 mg/kg, 8.5 mg/kg, and 85 mg/kg body weight), and OVX + 17beta-estradiol (E(2); 10 microg/kg body weight). After 3 mo of treatment, E(2) completely prevented the OVX-induced bone loss. OVX rats treated with LF were protected against the OVX-induced reduction of bone volume, trabecular number, and thickness, and the elevation of trabecular separation was prevented. LF also increased bone mineral density and increased the parameters of mechanical strength at 8.5- and 85-mg/kg doses. Greater bone formation and reduced bone resorption, as assessed by biochemical markers of bone remodeling, occurred in rats administered LF. LF at 8.5- and 85-mg/kg concentrations caused a significant decrease in serum calcium, but this reduction did not occur in rats fed 0.85 mg/kg LF. In addition, serum tumor necrosis factor-alpha and interleukin-6 production were suppressed and serum calcitonin was elevated significantly in LF-fed rats at all 3 doses. These findings indicated that oral LF not only preserved bone mass but also improved bone microarchitecture. The absorption of LF peptides and their effects on bone cells could to some extent account for the osteogenic function of oral LF.

Lactoferrin and cancer disease prevention

Lactoferrin (LF) is an iron-binding glycoprotein that is composed of the transferrin family and is predominantly found in the products of the exocrine glands located in the gateways of the digestive, respiratory, and reproductive systems, suggesting a role in the non-specific defence against invading pathogens. Additionally, several physiological roles have been attributed to LF, namely regulation of iron homeostasis, host defence against infection and inflammation, regulation of cellular growth, and differentiation and protection against cancer development and metastasis. These findings have suggested LF's great potential therapeutic use in cancer disease prevention and/or treatment, namely as a chemopreventive agent. This review looks at the recent advances in understanding the mechanisms underlying the multifunctional roles of LF and future perspectives on its potential therapeutic applications.

Bovine lactoferrin supplementation supports immune and antioxidant status in healthy human males

Dietary supplements of bovine lactoferrin are purported in consumer literature to enhance and support the immune system response through their antioxidant, antibacterial, and antiviral properties. Our aim was to investigate more fully the potential immune modulating properties and antioxidant activity of an oral supplementation of bovine lactoferrin in humans. Using an intraindividual repeated measure design, 8 healthy males aged 30 to 55 years, self-administered daily for 21 days, one capsule of placebo for 7 days, followed by 100 mg of lactoferrin for 7 days, followed by 200 mg of lactoferrin for 7 days. Peripheral blood lymphocyte subset counts, T-cell activation, natural killer (NK) cell cytotoxicity, serum cytokine levels (tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma, interleukin [IL]-2, IL-4, IL-6, and IL-10), and serum hydrophilic, lipophilic, and total antioxidant capacity were repeatedly measured before and after each progressive supplementation. Statistically significant increases were found between presupplementation levels and levels after 200 mg of supplementation in total T-cell activation (as measure by CD3(+)) (P < .001), helper T-cell activation (as measure by CD4(+)) (P < .001), cytotoxic T-cell activation (as measured by CD8(+)) (P < .001), and hydrophilic antioxidant capacity (P < .05). No significant changes were seen in the other parameters measured. These results support the proposal that oral supplements of bovine lactoferrin may be a useful adjunct toward modulation of immune activity, in particular T-cell activation and antioxidant status.

Effect of lactoferrin on oxidative features of ceruloplasmin

In our previous report we first described a complex between lactoferrin (Lf) and ceruloplasmin (Cp) with K (d) approximately 1.8 microM. The presence of this complex in colostrum that never contains more than 0.3 microM Cp questions the reliability of K (d) value. We carefully studied Lf binding to Cp and investigated the enzymatic activity of the latter in the presence of Lf, which allowed obtaining a new value for K (d) of Cp-Lf complex. Lf interacting with Cp changes its oxidizing activity with various substrates, such as Fe(2+), o-dianisidine (o-DA), p-phenylenediamine (p-PD) and dihydroxyphenylalanine (DOPA). The presence of at least two binding sites for Lf in Cp molecule is deduced from comparison of substrates' oxidation kinetics with and without Lf. When Lf binds to the first site affinity of Cp to Fe(2+) and to o-DA increases, but it decreases towards DOPA and remains unchanged towards p-PD. Oxidation rate of Fe(2+) grows, while that of o-DA, p-PD and DOPA goes down. Subsequent Lf binding to the second center has no effect on iron oxidation, hampers DOPA and o-DA oxidation, and reduces affinity towards p-PD. Scatchard plot for Lf sorbing to Cp-Sepharose allowed estimating K (d) for Lf binding to high-affinity (approximately 13.4 nM) and low-affinity (approximately 211 nM) sites. The observed effect of Lf on ferroxidase activity of Cp is likely to have physiological implications.

Production of recombinant human lactoferrin in the allantoic fluid of embryonated chicken eggs and its characteristics

The human iron-binding protein lactoferrin (hLf) has been implicated in a number of important physiological pathways, including those regulating immune function and tumor growth. In an effort to develop an efficient system for production of recombinant hLf (rhLf) that is structurally and functionally equivalent to the natural protein, we generated a recombinant CELO (chicken embryo lethal orphan) avian adenovirus containing an expression cassette for hLf. Embryonated chicken eggs were infected with the generated CELO-Lf virus. rhLf expression was measured in the allantoic fluid of infected eggs by ELISA three days later. The level of recombinant protein was about 0.8mg per embryo. rhLf was efficiently purified (up to 85% yield) from the allantoic fluid of infected eggs using affinity chromatography. rhLf produced in the allantoic fluid was characterized in comparison with natural hLf (nhLf) purified from human breast milk. SDS-PAGE, Western blotting and glycosylation analyzes showed that the recombinant protein had similar physical characteristics to nhLf. In addition, we demonstrated that the antioxidative and antimicrobial activity of rhLf produced in this system is equivalent to that of nhLf. Taken together, these results illustrate the utility of the described "recombinant CELO adenovirus-chicken embryo" system for production of functionally active rhLf. Efficient production of rhLf with accurate structure and function is an important step in furthering investigation of Lf as a potential human drug.

Effect of bovine lactoferrin on the internalization of coagulase-negative staphylococci into bovine mammary epithelial cells under in-vitro conditions

Coagulase-negative staphylococci (CNS) have emerged as bovine mastitis pathogens in many countries. CNS mastitis is generally mild but can persist in the udder for long periods. Pathogenesis of CNS intramammary infection is not well understood. In the present study, adhesion, invasion and intracellular replication of twenty-two CNS strains isolated from bovine mastitis and the effect of bovine lactoferrin (bLf) on the internalization were studied in vitro in a bovine mammary epithelial (BME) cell model. The CNS strains were of Staphylococcus chromogenes, Staph. simulans, Staph. epidermidis, Staph. haemolyticus and Staph. cohnii urealyticus; two strains of Staph. aureus were used as controls. Seven of the CNS strains originated from persistent and five from transient mastitis infections. The in-vitro susceptibility of the strains to bLf was also investigated. All CNS species examined had an adhesive ability equal to that of Staph. aureus, but internalization varied among staphylococcal strains. The antagonistic effect of bLf on the adhesion and invasion of CNS strains was weak, but bLf significantly decreased intracellular replication and replication rates of CNS. No correlation between the in-vitro susceptibility of the strain to bLf or internalization among clinical signs of mastitis was established. No difference between the persistent and transient CNS strains in adhesion, invasion or replication rate was recorded. This in-vitro BME cell model can be used to study the virulence potential of mastitis pathogens, although the severity and persistence of eventual infections shall be further investigated in vivo. The role of bLf in intramammary infection caused by CNS may be limited.

Lactoferrin immuno-expression in human normal and neoplastic bone tissue

Lactoferrin (Lf) expression was investigated by using a Lf monoclonal antibody in 50 formalin-fixed and paraffin-embedded human bone tumours [10 giant cell tumours (GCTs), 7 osteoid osteomas, 6 ossifying fibromas, 19 enchondromas, 2 chondroblastomas, 2 chondrosarcomas, 2 chondroblastic osteosarcomas, 1 myeloma and 1 adamantinoma] as well as in 8 samples of adult and foetal human normal bone specimens. In addition, the immunohistochemical expression of the estrogen receptor (ER), progesterone receptor (PR) and Ki-67 antigen was analysed on parallel sections from the same specimens. Quantification of Lf immunoreactivity was performed by using an Intensity Distribution (ID) score. Lf immuno-expression with a variable ID score was encountered in 19/50 tumours and specifically in 10/10 GCTs, in 5/7 osteoid osteomas, in 2/2 chondroblastomas as well as in the adamantinoma and in the myeloma. With reference to normal bone samples, Lf was expressed by the osteoblasts only in the foetal bone. No immunoreactivity for ER and PR was encountered in all neoplastic samples, and no correlation was found between Lf and sex steroid hormone receptor (ER and PR) immuno-expression. Even more, no association was evidenced between Lf immuno-reactivity and the growth fraction of the tumours, reflected by the Ki-67 labelling index. Lf expression in the osteoblastic lineage of bone-forming tumours, together with its presence in the osteoblasts of foetal bone, requires further investigations, although it cannot be ruled out that Lf might be involved in the bone formation in humans, similarly to what has been demonstrated in other species.

Multivariate gene expression analysis reveals functional connectivity changes between normal/tumoral prostates

BACKGROUND

Prostate cancer is a leading cause of death in the male population, therefore, a comprehensive study about the genes and the molecular networks involved in the tumoral prostate process becomes necessary. In order to understand the biological process behind potential biomarkers, we have analyzed a set of 57 cDNA microarrays containing approximately 25,000 genes.

RESULTS

Principal Component Analysis (PCA) combined with the Maximum-entropy Linear Discriminant Analysis (MLDA) were applied in order to identify genes with the most discriminative information between normal and tumoral prostatic tissues. Data analysis was carried out using three different approaches, namely: (i) differences in gene expression levels between normal and tumoral conditions from an univariate point of view; (ii) in a multivariate fashion using MLDA; and (iii) with a dependence network approach. Our results show that malignant transformation in the prostatic tissue is more related to functional connectivity changes in their dependence networks than to differential gene expression. The MYLK, KLK2, KLK3, HAN11, LTF, CSRP1 and TGM4 genes presented significant changes in their functional connectivity between normal and tumoral conditions and were also classified as the top seven most informative genes for the prostate cancer genesis process by our discriminant analysis. Moreover, among the identified genes we found classically known biomarkers and genes which are closely related to tumoral prostate, such as KLK3 and KLK2 and several other potential ones.

CONCLUSION

We have demonstrated that changes in functional connectivity may be implicit in the biological process which renders some genes more informative to discriminate between normal and tumoral conditions. Using the proposed method, namely, MLDA, in order to analyze the multivariate characteristic of genes, it was possible to capture the changes in dependence networks which are related to cell transformation.

Proteomic profiling in early venous stenosis formation in a porcine model of hemodialysis graft

PURPOSE

To use proteomic analysis to identify up- and downregulated proteins in early venous stenosis formation in a porcine model of hemodialysis graft failure.

MATERIALS AND METHODS

Pigs had chronic renal insufficiency created by subtotal renal infarction caused by renal artery embolization. Arteriovenous polytetrafluoroethylene grafts were placed 28 days later and the animals were killed after a further 3 days (n = 4), 7 days (n = 4), or 14 days (n = 4). Proteomic analysis with isotope-coded affinity tags and multidimensional liquid chromatography followed by tandem mass spectrometry was performed on the venous stenosis and control vessels. Expression of proteins was further confirmed by Western blot analysis. The blood urea nitrogen (BUN) and creatinine levels were determined before renal artery embolization and at the time of graft placement.

RESULTS

At graft placement, mean BUN and creatinine levels were significantly higher than before embolization (P < .05). Six proteins were identified that were common to all four animals at the same time point. Five proteins (alpha-fetoprotein, fetuin A, macrophage migration inhibitory factor, pyruvate dehydrogenase E1 component, and lactoferrin) were upregulated and one protein (decorin) was downregulated. Expression of macrophage migration inhibitory factor, alpha-fetoprotein, and lactoferrin was further validated with Western blotting. By day 14, lactoferrin and fetuin-A expression were increased significantly in early venous stenosis formation.

CONCLUSIONS

Significantly increased expression of lactoferrin and fetuin-A were observed in early venous stenosis by day 14. Understanding the role of lactoferrin and fetuin-A in hemodialysis vascular access failure could help in improving outcomes in patients undergoing hemodialysis.

The effects of lactoferrin in a rat model of catecholamine cardiotoxicity

Lactoferrin is recently under intense investigation because of its proposed several pharmacologically positive effects. Based on its iron-binding properties and its physiological presence in the human body, it may have a significant impact on pathological conditions associated with iron-catalysed reactive oxygen species (ROS). Its effect on a catecholamine model of myocardial injury, which shares several pathophysiological features with acute myocardial infarction (AMI) in humans, was examined. Male Wistar rats were randomly divided into four groups according to the received medication: control (saline), isoprenaline (ISO, 100 mg kg(-1) s.c.), bovine lactoferrin (La, 50 mg kg(-1) i.v.) or a combination of La + ISO in the above-mentioned doses. After 24 h, haemodynamic functional parameters were measured, a sample of blood was withdrawn and the heart was removed for analysis of various parameters. Lactoferrin premedication reduced some impairment caused by ISO (e.g. a stroke volume decrease, an increase in peripheral resistance and calcium overload). These positive effects were likely to have been mediated by the positive inotropic effect of lactoferrin and by inhibition of ROS formation due to chelation of free iron. The failure of lactoferrin to provide higher protection seems to be associated with the complexity of catecholamine cardiotoxicity and with its hydrophilic character.

Bovine colostrum contains immunoglobulin G antibodies against intimin, EspA, and EspB and inhibits hemolytic activity mediated by the type three secretion system of attaching and effacing Escherichia coli

Enterohemorrhagic Escherichia coli (EHEC) is the main cause of hemolytic-uremic syndrome, an endemic disease in Argentina which had an incidence in 2005 of 13.9 cases per 100,000 children younger than 5 years old. Cattle appear to be a major reservoir of EHEC, and a serological response to EHEC antigens has been demonstrated in natural and experimental infections. In the current study, antibodies against proteins implicated in EHEC's ability to form attaching and effacing lesions, some of which are exported to the host cell via a type three secretion system (TTSS), were identified in bovine colostrum by Western blot analysis. Twenty-seven (77.0%) of the 35 samples examined contained immunoglobulin G (IgG) antibodies against the three proteins assayed in this study: EspA, EspB, and the carboxy-terminal 280 amino acids of gamma-intimin, an intimin subtype associated mainly with O157:H7 and O145:H- serotypes. Every colostrum sample was able to inhibit, in a range between 45.9 and 96.7%, the TTSS-mediated hemolytic activity of attaching and effacing E. coli. The inhibitory effect was partially mediated by IgG and lactoferrin. In conclusion, we found that early colostrum from cows contains antibodies, lactoferrin, and other unidentified substances that impair TTSS function in attaching and effacing E. coli strains. Bovine colostrum might act by reducing EHEC colonization in newborn calves and could be used as a prophylactic measure to protect non-breast-fed children against EHEC infection in an area of endemicity.

Effect of lactoferrin on enteric pathogens

Much has been learned in recent years about the mechanisms by which breastfeeding improves child health and survival. However, there has been little progress in using these insights to improve pediatric care. Factors that are important for protecting the breast fed infant might be expected to decrease the adverse effects of weaning on diarrhea, growth, and development. Lactoferrin, an iron-binding protein with multiple physiological functions (anti-microbial, anti-inflammatory, and immunomodulatory), is one of the most important proteins present in mammalian milk. Protection against gastroenteritis is the most likely biologically relevant activity of lactoferrin. Multiple in vitro and animal studies have shown a protective effect of lactoferrin on infections with enteric microorganisms, including rotavirus, Giardia, Shigella, Salmonella and the diarrheagenic Escherichia coli. Lactoferrin has two major effects on enteric pathogens: it inhibits growth and it impairs function of surface expressed virulence factors thereby decreasing their ability to adhere or to invade mammalian cells. Thus, lactoferrin may protect infants from gastrointestinal infection by preventing the attachment by enteropathogens in the gut. Recently several clinical trials in children have started to address this issue. Whether lactoferrin can prevent a significant portion of diarrheal disease remains to be determined.

28-Day repeated dose oral toxicity of recombinant human apo-lactoferrin or recombinant human lysozyme in rats

Lactoferrin and lysozyme are important proteins of the human innate immune system. These proteins are found in breast milk and have been associated with improved infant health. Recombinant human apo-lactoferrin (apo-rhLF), 1800 and 180mg/kg bw/day, and recombinant human lysozyme (rhLZ), 360 and 36mg/kg bw/day, were orally administered to Wistar rats for 28 days. Apo-rhLF and rhLZ were expressed in rice grain, extracted, purified; the lactoferrin was iron desaturated. The animals were examined for evidence of toxicity; there were no deaths and in-life physical signs were normal. Transient differences in mean food consumption occurred in high dose apo-rhLF and low dose LZ females at week three. There were no biologically significant differences in hematological or clinical chemistry parameters. Necropsy results were normal and microscopic evaluation showed no treatment related changes in animals dosed with 1800mg/kg/day apo-rhLF or 360mg/kg/day rhLZ. The results of the 28-day oral administration demonstrate a lack of toxicity of apo-rhLF and rhLZ in rats. There were no treatment related, toxicologically relevant changes in clinical signs, growth, food consumption, hematology, clinical chemistry, organ weight and pathology. The no observed adverse effect level (NOAEL) is greater than 1800mg/kg/day for apo-rhLF and 360mg/kg/day for rhLZ.

Involvement of the nitric oxide-cyclic GMP-protein kinase G-K+ channel pathway in the antihyperalgesic effects of bovine lactoferrin in a model of neuropathic pain

The possible involvement of the nitric oxide (NO)-cyclic GMP (cGMP)-protein kinase G (PKG) pathway on bovine lactoferrin (BLF)-induced spinal antihyperalgesic activity was elucidated in sciatic nerve injured rats. Intrathecal BLF reduced thermal hyperalgesia in a dose-dependent manner. Pretreatment with NG-L-nitro-arginine methyl ester (L-NAME, non-specific inhibitor of NO synthase), 7-nitroindazole (7-NI, neuronal NO synthase inhibitor), 1H-[1,2,4]-oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, guanylyl-cyclase inhibitor), (9S, 10R, 12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2, 9-dimethyl-1-oxo-9, 12-epoxy-1H-diindolo-[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid methyl ester (KT-5823, specific PKG inhibitor) or glybenclamide (ATP-sensitive K+ channel blocker), but not NG-D-nitro-arginine methyl ester (D-NAME, an inactive enantiomer of l-NAME), d-Phe-Cys-Tyr-d-Trp-Orn-Thr-NH2 (CTOP, selective mu-opioid receptor antagonist) or naloxone (nonselective opioid receptor antagonist) prevented BLF-induced antihyperalgesia. Data suggest that BLF-induced spinal antihyperalgesia could be due to activation of the NO-cGMP-PKG-K+ channel pathway and it is not mediated by mu-opioid receptor in a model of neuropathic pain.

In vitro effects of bovine lactoferrin on autoaggregation ability and surface hydrophobicity of bifidobacteria

Changes in autoaggregation ability and surface hydrophobicity of bifidobacteria with addition of bovine lactoferrin in liquid media were investigated. Lactoferrin addition caused loss of autoaggregation ability, disappearance of microscopic clusters and produced consistent turbidity in the cultured medium compared with control. Similar outcomes with addition of bovine lactoferrin hydrolysates (pepsin), bovine transferrin or ovotransferrin suggested that the effect is not lactoferrin-specific. On the other hand, addition of proteins, except bovine transferrin, did not alter surface hydrophobicity. These results indicate that one or more surface components involved in autoaggregation of bifidobacteria are proteins.

Effect of bovine lactoferrin on extracellular matrix calcification by human osteoblast-like cells

Osteoblast-mediated calcium deposition to the extracellular matrix (ECM) is a critical step in bone tissue generation. Bovine lactoferrin enhanced the calcium deposition by MG63 human osteoblast-like cells cultured on collagen-coated plates. Lactoferrin also promoted the alkaline phosphatase activity and osteocalcin production during the calcification process, whereas it had little effect on the growth of the cells on the collagen-coated plates.

Lactoferrin enhanced efficacy of the BCG vaccine to generate host protective responses against challenge with virulent Mycobacterium tuberculosis

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is a disease with world wide consequences, affecting nearly a third of the world's population. The established vaccine for TB, an attenuated strain of Mycobacterium bovis Calmette Guerin (BCG), has existed since 1921. Lactoferrin, an iron-binding protein found in mucosal secretions and granules of neutrophils was hypothesized to be an ideal adjuvant to enhance the efficacy of the BCG vaccine, specifically because of previous reports of lactoferrin enhancement of IL-12 production from macrophages infected with BCG. Different vaccination protocols were investigated for generation of host protective responses against MTB infection using lactoferrin admixed to the BCG vaccine. Resulting effects demonstrate that BCG/lactoferrin increased host protection against MTB infection by decreasing organ bacterial load and reducing lung histopathology; significant reduction in tissue CFUs and pathology were observed post-challenge compared to those seen with BCG alone. Addition of lactoferrin to the vaccine led to reduced pathological damage upon subsequent infection with virulent MTB, with positive results demonstrated when admixed in oil-based vehicle (incomplete Freund's adjuvant, IFA) or when given with BCG in saline. The observed post-challenge results paralleled increasing production of IFN-gamma and IL-6, but only limited changes to proinflammatory mediators TNF-alpha or IL-1beta from BCG-stimulated splenocytes. Overall, these studies indicate that lactoferrin is a useful and effective adjuvant to improve efficacy of the BCG vaccine, with potential to reduce related tissue damage and pulmonary histopathology.

Antibacterial activity of bovine lactoferrin hydrolysate against mastitis pathogens and its effect on superoxide production of bovine neutrophils

Antibacterial activity of bovine lactoferrin hydrolysates (LFH) on microorganisms isolated from bovine mastitis, and superoxide (O(2)(-)) production of bovine neutrophils were evaluated. Antibacterial effects of LFH were measured in vitro against Staphylococcus aureus, coagulase-negative staphylococci, Streptococci, Enterococci, Escherichia coli, Klebsiella pneumoniae, yeast-like fungi and Prototheca zopfii isolated from clinical cases of bovine mastitis. To compare susceptibilities against LFH, minimal inhibitory concentration (MIC) values were determined by a micro-plate assay method. Most organisms were sensitive to LFH. Prototheca zopfii was highly sensitive to LFH; the growth of the microorganism was inhibited completely even at 1 mug/ml. Staphylococcus aureus and Escherichia coli were resistant to LFH. The production of O(2)(-) by bovine neutrophils was used to evaluate the effect of LFH administration on functional activity. Increase in O(2)(-) production by bovine neutrophils occurred upon addition of LFH to neutrophils. These results demonstrate that LFH possesses antibacterial activity against pathogens that cause mastitis and activates neutrophil superoxide production.

Bovine lactoferrin reduces plasma triacylglycerol and NEFA accompanied by decreased hepatic cholesterol and triacylglycerol contents in rodents

In the present study we examined whether oral administration of bovine lactoferrin (bLF) reduces plasma or hepatic triacylglycerol and cholesterol in mice. When bLF mixed with a standard commercial diet (10g/kg) was given to mice for 4 weeks, plasma triacylglycerol and NEFA decreased, while plasma HDL-cholesterol levels increased (P<0·01). These changes in plasma lipid profiles were accompanied by significant decreases in hepatic cholesterol and triacylglycerol contents. When mice were fed a high-fat diet containing 300·0g lard, 10·0g cholesterol and 2·5g bovine bile powder/kg for 4 weeks, bovine LF did not have any significant effects on plasma or hepatic cholesterol and triacylglycerol concentrations. Furthermore, bLF had no significant effects on faecal excretion of total bile acids in mice. Interestingly, bLF showed a suppressive effect on the lymphatic triacylglycerol absorption in chronically treated rats. We conclude that bLF has a beneficial effect on plasma cholesterol levels and retards hepatic lipid accumulation in mice fed a standard diet.