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PubMed1996

Lactoferrin: similarity to diamine oxidase and purification by aminohexyl affinity chromatography.

A protein reacting with a monoclonal antibody against human placental diamine oxidase was purified from the specific granules of human neutrofil granulocytes using affinity chromatography on aminohexyl-divinylsulfonyl-agarose. The protein had an M(r) determined by SDS/PAGE, corresponding to diamine oxidase, but had other properties which indicated that it might be a different protein. A combination of protein chemical techniques, including N-terminal sequencing, identified the protein as lactoferrin, an iron-containing protein with an M(r) of approximately 800000, a high isoelectric point and ferroxidase activity. Purified commercial lactoferrin was shown to bind to aminohexyl-divinylsulfonyl-agarose, and to be eluted in a heterogenous way from the matrix by amines and salt. Alignment of the sequences of diamine oxidase and lactoferrin showed that they are similar, indicating a common ancestry for these two different classes of metallo-oxidases.

Amine Oxidase (Copper-Containing)↗

PubMed1997

Transferrin--interactions of lactoferrin with hydrogen carbonate.

The interaction of apolactoferrin with hydrogen carbonate (bicarbonate) has been investigated in the pH range 6.5-9.2. In the absence of bicarbonate apolactoferrin loses a single proton with pK1a of 8.10. This proton loss is independent of the interaction with the synergistic anion. The C-site of apolactoferrin interacts with bicarbonate with a very low affinity (K(-1)C = 3.2 M(-1)). This process is accompanied by a proton loss, which is probably provided by the bicarbonate in interaction with the protein. This proton loss can possibly be the result of a shift in the proton dissociation constant, pKa, of the bicarbonate/carbonate acid/base equilibrium, which would decrease from pKa 10.35 to pK2a 6.90 in the bicarbonate-lactoferrin adduct. The N-site of the protein interacts with bicarbonate with an extremely low affinity, which excludes the presence of the N-site-synergistic anion adduct in neutral physiological media. Contrary to serum transferrin, the concentration of the apolactoferrin in interaction with bicarbonate is pH dependent. Between pH 7.4 and pH 9 with [HCO3-] about 20 mM, the concentration of the serum transferrin-bicarbonate adduct is always about 30%, whereas that of the apolactoferrin-synergistic anion adduct varies from 25% at pH 7.5 to 90% at pH 9. This implies that, despite an affinity for bicarbonate two orders of magnitude lower than that of serum transferrin, lactoferrin interacts better with the synergistic anion. This can be explained by the possible interaction of lactoferrin with carbonate in neutral media, whereas transferrin only interacts with bicarbonate.

Animals↗

PubMed1994

A review: the active peptide of lactoferrin.

A potent antimicrobial peptide, 'lactoferricin', was found to be generated upon gastric pepsin cleavage of lactoferrin. The active peptide consists mainly of a loop of 18 amino acid residues, derived from the N-terminal region of the lactoferrin molecule. Like various other antimicrobial peptides that display membrane-disruptive properties, it contains a high proportion of basic amino acid residues. A physiologically diverse range of micro-organisms was tested and found to be susceptible to inhibition by this natural peptide including Gram-negative and Gram-positive bacteria, yeasts and filamentous fungi. Its antimicrobial effect against sensitive micro-organisms was lethal. Electron microscopy studies revealed that it induces a profound change in cell ultrastructural features and causes substantial cell damage in bacteria and fungi. These findings suggest the possibility that active peptides of lactoferrin may have a role in the host defense against microbial disease. If produced in substantial quantities in vivo such peptides could have important physiological significance, especially in nursing infants.

Amino Acid Sequence↗

PubMed1996

Effect of Vibrio cholerae non-O1 protease on lysozyme, lactoferrin and secretory immunoglobulin A.

The effect of Vibrio cholerae non-O1 protease on host defense proteins (lysozyme, secretory immunoglobulin A and lactoferrin) was studied in relation to its virulence mechanism. The proteins treated with the protease were analysed by SDS-PAGE. There was no influence of the protease on lysozyme. The protease cleaved lactoferrin into two fragments of 50 kDa and 34 kDa. N-terminal amino acid sequencing of these fragments revealed that the cleavage site was near the hinge region, between serine 420 and serine 421. This cleavage could affect the transition from open to closed configuration which is involved in iron binding and release. The anti-bacterial activity of lactoferrin was not affected by protease treatment. Secretory immunoglobulin A yielded a 42-kDa protein as the cleavage product. The susceptibility of secretory immunoglobulin A to V. cholerae non-O1 protease suggests a mechanism by which bacteria might evade the effect of this immunoglobulin.

Amino Acid Sequence↗

PubMed1997

Identification of a lactoferrin-binding protein in Prevotella nigrescens.

A 40-kDa lactoferrin-binding protein was identified in a strain of Prevotella nigrescens isolated from a patient with periodontitis. The protein was purified by affinity column chromatography using a Sepharose-lactoferrin column and detergent-solubilized membranes. The N-terminal sequence revealed no apparent similarities with any other sequenced bacterial protein. The native conformation of the 40-kDa protein was a condition to bind either iron-free or iron-saturated lactoferrin. A possible function of this Lf-binding protein could be related with an iron acquisition mechanism in P. nigrescens.

Bacterial Outer Membrane Proteins↗

PubMed2001

Binding of lactoferrin and free secretory component to enterotoxigenic Escherichia coli.

The ability of two glycoproteins of human milk, lactoferrin and free secretory component, to bind to Escherichia coli colonization factors (CFAs) was investigated using immunocytochemistry assays of enriched fimbrial extracts. The results revealed that lactoferrin binds to fimbrial CFA I adhesin but not to CFA II adhesin (CS1 and CS3), while free secretory component interacts with both CFA I and CFA II adhesins. Our data indicate that lactoferrin and free secretory component, which are very abundant proteins of human milk, could play an important role against infant enteric disease by blocking bacterial adhesion.

Bacterial Adhesion↗

PubMed1997

The ratio of albumin to lactoferrin in tear fluid as a diagnostic tool in primary Sjögren's syndrome.

PURPOSE: To compare the protein composition of tear fluid obtained from patients with primary Sjögren's syndrome, patients with other connective tissue diseases and control individuals. METHODS: SDS polyacrylamide gel electrophoresis followed by staining with Coomassie blue and Western blotting. RESULTS: Comparison revealed the presence of a characteristic difference in the ratio of intensity between the albumin and lactoferrin bands. An albumin:lactoferrin ratio above 2:1 was significantly more common in patients with primary Sjögren's syndrome than in patients with other connective tissue diseases or the controls. CONCLUSION: An albumin:lactoferrin ratio above 2:1 may therefore prove of use when diagnosing 1(0)SS. Used as a test, its sensitivity was 67% and its specificity 100%.

Adult↗

PubMed1986

Bone-marrow regeneration after therapy-induced hypoplasia monitored by serum measurements of lactoferrin, lysozyme and myeloperoxidase.

Serum levels of lactoferrin, lysozyme and myeloperoxidase were measured sequentially after induction treatment in 30 patients with AML in order to test the hypothesis that these proteins may be used to monitor activity and different stages of myelopoiesis in the bone-marrow. The results showed that myeloperoxidase and lysozyme started to rise again 6-8 days after initiation of treatment as compared to 12 d for lactoferrin and 16 d for blood polymorphonuclear leukocytes. The rate of marrow regeneration was exponential and estimated to be 9-20% per d. The comparison between two different chemotherapy regimes showed that the initial reduction in lysozyme, in contrast to other measured variables, was significantly larger with the therapy that contained vincristine and glucocorticosteroids. This might reflect a reduction in lysozyme secretion in addition to the effects on the leukemic cell mass. We conclude that the measurements of lactoferrin, lysozyme and myeloperoxidase in serum under certain circumstances may be used to monitor the myelopoietic activity in the bone-marrow.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1988

Lactoferrin-mediated transfer of iron to intracellular ferritin in human monocytes.

Interactions of 125I-59Fe-lactoferrin with human monocytes were studied. After 4 hours of incubation, the uptake of 59Fe exceeded that of 125I. In dissociation studies the cellular 59Fe-activity was only partly dissociable during 16 h, whereas the 125I-activity could be released nearly completely. Disruption of the cells and studies on the cytosolic phase were performed employing gel-filtration and affinity chromatography. An appreciable amount of lactoferrin was found in the cytosolic phase. About 50% of the cytosolic 59Fe-activity was bound to ferritin. The results suggest that lactoferrin is internalized into monocytes and that iron is transferred to ferritin. These cellular events may contribute to an understanding of the accumulation of iron in the monocyte/macrophage system observed during inflammatory conditions.

Cells, Cultured↗

PubMed1985

Immunohistochemical investigation of lysozyme, lactoferrin, alpha 1-antitrypsin, alpha 1-antichymotrypsin and ferritin in parotid gland tumors.

Presence of lysozyme, lactoferrin, alpha 1-antitrypsin, alpha 1-antichymotrypsin and ferritin was examined by the immunoperoxidase method in 15 consecutive parotid gland tumors as well as in normal parotid gland tissue. Lysozyme and lactoferrin were detected in intercalated duct cells of normal tissue and in the epithelial component of pleomorphic adenomas. alpha 1-antitrypsin, alpha 1-antichymotrypsin and ferritin were found in both epithelial and mesenchymal components of pleomorphic adenomas but not in normal parotid tissue. In the epithelial component of adenolymphoma only alpha 1-antichymotrypsin and lactoferrin were observed. The results would support a tentative histogenetic link between the intercalated duct cell and the epithelial component of the pleomorphic adenoma.

Adenocarcinoma↗

PubMed1993

Concentrations of thiocyanate, hypothiocyanite, 'free' and 'total' lysozyme, lactoferrin and secretory IgA in resting and stimulated whole saliva of children aged 12-14 years and the relationship with plaque accumulation and gingivitis.

Resting and stimulated whole saliva was collected from 94 children aged 12-14 years and analyzed for thiocyanate, hypothiocyanite, 'free' and 'total' lysozyme, lactoferrin and secretory IgA. Clinical assessments of the amounts of plaque and gingival inflammation were made, and plaque was collected for determination of dry weight. An inverse relationship was observed between salivary thiocyanate concentrations in both resting and stimulated saliva and the amounts of plaque and gingival inflammation in these subjects (p < 0.05). Lactoferrin concentration in stimulated saliva was directly related to the amounts of plaque and gingivitis (p < 0.05). 'Total' lysozyme concentration in stimulated saliva was directly related to the amount of plaque (p < 0.05), and the 'free' lysozyme concentration in the same saliva was directly related to the amount of gingivitis (p < 0.05). The direct relationship observed between clinical measurements and both lysozyme and lactoferrin concentrations in saliva may have been due to contributions from gingival crevicular fluid. Cluster analysis identified three groups of subjects with different profiles in resting whole saliva, and in particular with different levels of secretory IgA. A statistically significant difference was observed in the quantity of plaque collected from subjects in two of these groups (p < 0.05). These results from cluster analysis using resting whole saliva from children confirmed the findings of a previous study with young adults.

Adolescent↗

PubMed1980

The effect of digestive enzymes on the binding and bacteriostatic properties of lactoferrin and vitamin B12 binder in human milk.

Human milk contains unsaturated lactoferrin and vitamin B12 binding protein. It has been suggested that these proteins may exert antibacterial effects in the intestine of the breast fed infant, but the effect of the intestinal environment on the antibacterial effect of these proteins has not been described. In this study human milk was treated with pepsin and trypsin and the influence of digestion on iron and vitamin B12 binding capacity, bacterial uptake of iron and vitamin B12 from milk and bacteriostatic effect was studied. Pepsin digestion had no effect on vitamin B12 binding capacity, or the ability of bacteria to take up vitamin B12, or the growth inhibitory effect on a vitamin B12 dependent strain. In contrast, trypsin digestion did not affect iron binding or bacteriostatic effects attributable to lactoferrin. The. findings support an in vivo bacteriostatic role for lactoferrin in the breast fed neonate's intestine but do not support a similar role for the vitamin B12 binding protein.

Bacterial Proteins↗

PubMed1989

Breast-milk IgA and lactoferrin survival in the gastrointestinal tract--a study in rural Gambian children.

The survival of breast-milk secretory-IgA and lactoferrin has been investigated in 23 Gambian children aged 1.5, 3 and 17 months. Endogenous excretion of these immune proteins was measured in 7 weaned 34-month-old children. Defaecation rate was the prime determinant of faecal secretory-IgA and lactoferrin outputs, indicating that partial degradation occurs in the large intestine. Calculations showed that at least 30% of IgA and 2% of lactoferrin ingested from breast-milk must survive in the small intestine. Variations in faecal immune protein outputs were related to differences in intake and defaecation rate and were not affected by age or solid food consumption. The raised faecal outputs of 5 children with diarrhoea were a consequence of their high stool frequencies. IgA disappearance in the large intestine proceeded twice as fast in Gambian breast-fed children as in comparable Cambridge infants, suggesting that differences in gut flora may influence IgA survival. Thus breast-feeding, irrespective of age or additional food, can deliver significant quantities of these antimicrobial proteins to the small intestine but differences in defaecation rate and gut flora may affect their protective potential in the large intestine.

Breast Feeding↗

PubMed1992

Supplementation of an adapted formula with bovine lactoferrin: 1. Effect on the infant faecal flora.

The development of the infant faecal flora was studied over the first three months of life in infants receiving breast milk, a modern adapted formula and adaptations of this formula. Breast-fed infants developed a flora rich in Bifidobacterium sp. Facultative anaerobes were ubiquitous, but in relatively small numbers within the diet group. Other obligate anaerobes, such as Clostridium sp. and Bacteriodes sp. were rarely isolated. Standard formula produced a flora rich in bifidobacteria, but the growth of facultative organisms was not suppressed by this diet. Clostridium sp. and Bacteroides sp. were more common in this feeding group. After the addition of lactoferrin at 10 mg/100 ml to the formula diet, a flora similar to that of the standard formula-fed babies was achieved. Lactoferrin at 100 mg/100 ml was able to establish a "bifidus flora" in half of the babies given this formula, but only at age three months. Clostridium sp. and Bacteroides sp. were common faecal isolates from babies receiving both the lactoferrin diets.

Age Factors↗

PubMed1997

Effect of human milk prostaglandins and lactoferrin on respiratory syncytial virus and rotavirus.

The effect of lactoferrin and prostaglandins E and F2 alpha on the growth of rotavirus and respiratory syncytial virus in cell culture was investigated. Lactoferrin inhibited the growth of respiratory syncytial virus at a concentration tenfold lower than that normally present in human milk. The prostaglandins had no effect on either virus growth, even at a concentration of 100-fold more than that found in human milk. Lactoferrin may have some antiviral properties in human milk in addition to its known antibacterial functions.

Animals↗

PubMed1990

Early response in neonatal septicemia. The effect of Escherichia coli, Streptococcus agalactiae and tumor necrosis factor on the generation of lactoferrin.

Using an in vitro model, we report the early effect of Escherichia coli (E. coli), Streptococcus agalactiea (group B streptococci, GBS) and recombinant tumor necrosis factor alpha (TNF) on the release of lactoferrin (LF) and the generation of interleukin-1 (IL-1) due to E. coli, using heparinized whole blood from healthy full-term newborns. We wanted to find a dose response relationship between lactoferrin generation on the one hand and the amount of E. coli, GBS and TNF on the other hand. In a final concentration of 10(7) per ml both bacteria increased the release of LF significantly. The response to E. coli was immediate and mg/l +/- 0.29 mg/l, E. coli 1.83 mg/l +/- 0.76 mg/l, p less than 0.001). GBS was a less potent stimulant than E. coli and the response was only apparent after 20 minutes (mean +/- S.D.: 1.06 mg/l +/- 0.49 mg/l, p less than 0.01). TNF in a concentration of 10000 pg/ml as well as 1000 pg/ml increased the release of LF significantly (after 20 minutes mean +/- S.D.: 1.09 mg/l +/- 0.42 mg/l and 0.97 mg/l +/- 0.36 mg/l, respectively), whereas a concentration of 100 pg/ml had no effect. Whole blood incubated with different preparations of LF for 20 minutes did not increase the generation of LF significantly. No significant changes in IL-1 levels were observed. Lactoferrin had bacteriostatic but no bactericidal effect on GBS and Streptococcus mutans.

Animals↗

PubMed1995

Orally administered bovine lactoferrin inhibits bacterial translocation in mice fed bovine milk.

Feeding of bovine milk to mice induced a high incidence of bacterial translocation from the intestines to the mesenteric lymph nodes, and the bacteria involved were mainly members of the family Enterobacteriaceae. Supplementation of the milk diet with bovine lactoferrin or a pepsin-generated hydrolysate of bovine lactoferrin resulted in significant suppression of bacterial translocation. Our findings suggest that this ability of lactoferrin to inhibit bacterial translocation may be due to its suppression of bacterial overgrowth in the guts of milk-fed mice.

Administration, Oral↗

PubMed1987

Release of lactoferrin by polymorphonuclear leukocytes after aerosol challenge with Escherichia coli.

Mice with cyclophosphamide-induced granulocytopenia were challenged with aerosolized Escherichia coli, their lungs were lavaged at 1 and 4 h, and total cell counts, differential counts, and levels of lactoferrin, transferrin, and albumin were measured in the lung lavage fluid. Lung lavage fluid from cyclophosphamide-treated mice had few neutrophils and no increase in lactoferrin levels, whereas control mice had significant increases in both. Transferrin levels did not change in either group. Neutrophils are the source of increased lactoferrin levels in lung lavage fluid after aerosol challenge.

Aerosols↗