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PubMed2006

Recombinant human lactoferrin has a potential to suppresses uterine cervical ripening in preterm delivery in animal model.

OBJECTIVE: To investigate the effect of recombinant human lactoferrin (rhLF) on cervical ripening using a rabbit model in which preterm labor was induced by bacterial endotoxin lipopolysaccharide (LPS). STUDY DESIGN: Timed pregnant rabbits (New Zealand White, 3-4 kg, day 14) were randomly assigned to the following treatment groups: Group A, LPS + rhLF (n = 4); Group B, LPS (n = 4); and Group C, control (n = 4). Recombinant human lactoferrin (10 microg) was administrated to pregnant rabbits in Group A and not in Group B. Lipopolysaccharide (100 microg) was given to the rabbits in both groups for 3 days (days14-16). Drugs were administered as a vaginal suppository. On day 18, the rabbits were anesthetized with intramuscular ketamine hydrochloride (20 mg/kg) and diazepam (4 mg/kg). Both cervices of the rabbit uterus, which is bicorpus-bicolli, were taken out. One cervix was placed in 10% formalin solution for a histological study with standard hematoxylin-eosin staining. The other was used for an extension test to assess the grade of ripening. Extension was measured after a 5-mm length of cervical tissue was loaded with 5.8 g. RESULTS: The histological study showed remarkably loose and edematous connective tissue in Group B cervices. Cervical tissues in Group A was not different from those in Group C. Extension lengths were 2.2 +/- 0.2 mm in Group A, 7.0 +/- 2.7 mm in Group B, and 1.7 +/- 0.3 mm in Group C. CONCLUSION: These results suggest that rhLF inhibits cervical maturation induced by LPS in a rabbit model and may have a potential to prevent preterm delivery caused by cervical infection and ripening.

Administration, Intravaginal↗
PubMed1983

A new procedure for the synthesis of polyethylene glycol-protein adducts; effects on function, receptor recognition, and clearance of superoxide dismutase, lactoferrin, and alpha 2-macroglobulin.

A new, simplified technique for the synthesis of polyethylene glycol (PEG) derivatives of proteins utilizing 1,1'-carbonyldiimidazole for PEG activation, is described. PEG derivatives of superoxide dismutase, alpha 2-macroglobulin, alpha 2-macroglobulin-trypsin, and lactoferrin were prepared and studied. Superoxide dismutase coupled to PEG preserved 95% of its original activity while its plasma half-life increased from 3.5 min to 9 or more hours depending on the PEG derivative studied. PEG-derivatized alpha 2-macroglobulin showed decreased protease binding activity but PEG derivatives of performed alpha 2-macroglobulin-trypsin demonstrated no loss of activity. The plasma clearance of PEG-alpha 2-macroglobulin-trypsin was prolonged significantly compared to native alpha 2-macroglobulin-trypsin, particularly when a high-molecular-weight PEG was coupled to the protease inhibitor complex. The plasma clearance half-life of lactoferrin was increased 5- to 20-fold by this modification. Trinitrobenzenesulfonic acid titration studies demonstrated that epsilon-amino groups of lysine residues are modified by the coupling of carbonyldiimidazole-activated PEG to proteins.

Animals↗
PubMed1985

A specific iron stain for iron-binding proteins in polyacrylamide gels: application to transferrin and lactoferrin.

A new method for specifically staining the iron atoms present in transferrin and lactoferrin after polyacrylamide gel electrophoresis and isoelectric focusing is described. The stain, 3-(2-pyridyl)-5,6-bis(2-(5-furylsulfonic acid))-1,2,4-triazine, disodium salt, or Ferene S, will detect transferrin in 5 microliters of human serum, lactoferrin in 10 microliters of human whey, and 10 micrograms of purified primate (Macaca fascicularis) transferrin. This method of staining is very rapid as the serum transferrin bands can be seen within 5 to 10 min of staining.

Animals↗
PubMed1989

Relationships between human parotid saliva lysozyme lactoferrin, salivary peroxidase and secretory immunoglobulin A in a large sample population.

Saliva antimicrobial proteins may interact in a common system for host defence. This study applied multivariate analysis as a means of describing inter-person variation in that system. Samples of stimulated parotid saliva were obtained from 198 subjects. Flow rate was determined, and assays run for total protein, lysozyme, lactoferrin, salivary peroxidase and secretory IgA. Correlation and principal components analysis were used to define the relationships between proteins; cluster analysis was used to identify persons with similar protein concentration profiles. All proteins were significantly correlated at p less than 0.002 (r = 0.20-0.52). Principal components analysis identified a major axis of common variation, defined by lysozyme and salivary peroxidase, and a second axis, defined by secretory IgA. Lactoferrin was associated with both axes. Seven major groupings were obtained by cluster analysis; these were significantly different at p less than 0.001. Such groupings may prove useful in comparing the antimicrobial properties of saliva samples.

Adolescent↗
PubMed1995

Modulation of the anti-Candida activity of apo-lactoferrin by dietary sucrose and tunicamycin in vitro.

The sensitivity to apo-lactoferrin (apo-LF) of two oral isolates each of Candida albicans and C. krusei preincubated in either sucrose- or tunicamycin-supplemented media was investigated. Known apo-LF-sensitive isolates of both C. albicans and C. krusei demonstrated significantly increased resistance to apo-LF when preincubated in sucrose-supplemented media, but such preincubation had no effect on an apo-LF-resistant isolate of C. albicans, irrespective of the sugar concentration in the medium. Surprisingly, an apo-LF-resistant isolate of C. krusei demonstrated increased susceptibility to apo-LF when preincubated in sucrose. Further, when preincubated with tunicamycin, a chemical that interferes with candidal cell-wall formation, the susceptibility to apo-LF of the resistant isolates increased significantly. These results, when extrapolated in vivo, imply that dietary sucrose may diminish the anticandidal potency of salivary lactoferrin. However, the aberrant behaviour of a single isolate of C. krusei under these circumstances is possibly due to the different cell-wall structure of this yeast and needs to be further investigated.

Apoproteins↗
PubMed1995

Zonal distribution of receptor binding of trypsin-activated alpha 2-macroglobulin, alpha 2-macroglobulin receptor-associated protein, lactoferrin and transferrin on rat liver parenchymal cells.

Periportal and perivenous rat liver parenchymal cells were isolated according to the digitonin-collagenase perfusion method. Affinities and maximal specific binding of a conjugate of glutathione S-transferase and the alpha 2-macroglobulin receptor-associated protein (GST-39kDaP), of lactoferrin and of transferrin to freshly isolated periportal parenchymal cells in vitro were not significantly different from values obtained with perivenous cells. It is concluded that the receptors for these three ligands show a zonally homogeneous expression in rat liver. The zonal homogeneity in binding observed for GST-39kDaP is at variance with the 1.5-fold higher periportal over perivenous binding of trypsin-activated alpha 2-macroglobulin. Since GST-39kDaP as well as trypsin-activated alpha 2-macroglobulin are ligands for the alpha 2-macroglobulin receptor/low-density lipoprotein receptor-related protein, it is suggested that GST-39kDaP can bind to (an) additional receptor(s) with a higher perivenous expression. The zonal homogeneity observed with lactoferrin, an inhibitor of ligand binding to the lipoprotein remnant receptor, may indicate zonal homogeneity of the lipoprotein remnant receptor. The observed zonal homogeneity of the transferrin receptor suggests an equal and essential need for iron by parenchymal cells across the rat liver acinus in vivo.

Animals↗
PubMed1971

Association of lactoferrin with other proteins, as demonstrated by changes in electrophoretic mobility.

Lactoferrin in a number of human body fluids was found to possess different electrophoretic mobilities, while being immunologically identical. The isolated protein migrated slower than any of the naturally occurring forms. This phenomenon was found to be due to the property of human lactoferrin to interact strongly with acidic macromolecules, forming complexes with a faster migration than the single protein. Beside electrostatic interactions also other forces seem to be involved in the complex formation.

Apoproteins↗
PubMed1984

The latency of serum acute phase proteins in meningococcal septicemia, with special emphasis on lactoferrin.

Serum lactoferrin concentrations were elevated in almost all children with meningococcal septicemia, in whom the disease had been clinically apparent for less than 18 hours, while the concentrations were normal or only moderately elevated in patients who had had the disease longer before being admitted. Concentrations of C-reactive protein (CRP) were markedly elevated, even with a time lapse of less than six hours, making this the most suitable parameter for the early diagnosis of severe meningococcal infection. Following an operative injury on children the lactoferrin concentrations changed very little. More than six hours after an operation, however, a marked increase in CRP-values was observed, possibly indicating differentiation of this response from that of bacterial infection. The concomitant study of serum alpha 1-antitrypsin, alpha 1-antichymotrypsin, orosomucoid and haptoglobin did not uncover results of great significance with regard to early changes.

Acute Disease↗
PubMed1996

Antibacterial activity of peptides homologous to a loop region in human lactoferrin.

Human lactoferrin contains a 46 residue sequence named lactoferricin H thought to be responsible for its antimicrobial properties. Synthetic peptides HLT1, corresponding to the loop region of human lactoferricin (FQWQR-NMRKVRGPPVS) and HLT2, corresponding to its charged portion (FQWQRNMRKVR), exerted significant antibacterial effects against E. coli serotype O111 strains NCTC 8007 and ML35. The corresponding sequences in native human lactoferrin were shown to adopt a charged helix and hydrophobic tail within the N-lobe remote from the iron binding site. Sequence similarities between lactoferricin and dermaseptin and magainins suggest that lactoferricin may act as an amphipathic alpha helix.

Amino Acid Sequence↗
PubMed1987

Unfolding of iron and copper complexes of human lactoferrin and transferrin.

1. Human lactoferrin and transferrin are capable of binding two iron or copper ions into specific binding sites in the presence of bicarbonate. 2. Urea and several alkyl ureas have been effective in unfolding these metal-protein complexes. 3. Biphasic transitions are observed for the unfolding of each of the metal complexes of these proteins as determined by direct visible spectroscopy suggesting the release of iron(III) and Cu(II) ions from both of these metal-binding proteins during the unfolding process. 4. Greater stabilization and increased resistance to protein unfolding is observed for all iron(III) complexes compared to Cu(II) complexes of lactoferrin and transferrin as determined by isothermal unfolding and thermal denaturation. 5. Relative stabilization of the different metal-protein complexes investigated within this study were determined to be as follows: Lf-Fe(III) greater than Lf-Cu(II); Tf-Fe(III) greater than Tf-Cu(II), and Lf-Fe(III) greater than Tf-Fe(III); Lf-Cu(II) greater than Tf-Cu(II).

Circular Dichroism↗
PubMed1992

Spectroscopic analysis of the unfolding of transition metal-ion complexes of human lactoferrin and transferrin.

1. Human lactoferrin and transferrin are capable of binding several transition metal ions [Fe(III), Cu(II), Mn(III), Co(III)] into specific binding sites in the presence of bicarbonate. 2. Increased conformational stability and increased resistance to protein unfolding is observed for these metal-ion complexes compared to the apoprotein form of these proteins. 3. Mn(III)-lactoferrin and transferrin complexes exhibit steeper denaturation transitions than the Co(III) complexes of these proteins suggesting greater cooperativity in the unfolding process. 4. The incorporation of Fe(III) into the specific metal binding sites offers the greatest resistance to thermal unfolding when compared to the other transition metal ions studied. 5. Non-coincidence of unfolding transitions is observed, with fluorescence transition midpoints being lower than those determined by absorbance measurements. 6. Fully denatured proteins in the presence of urea and alkyl ureas exhibit fluorescence wavelength maxima at 355-356 nm indicative of tryptophan exposure upon protein unfolding.

Female↗
PubMed1992

Immunohistochemical identification of ferritin, lactoferrin and transferrin in leprosy lesions of human skin biopsies.

Granulomatous lesions of human leprosy contained ferritin and lactoferrin but little or no transferrin, as demonstrated by the avidin-biotin complex immunoperoxidase method. Lactoferrin was found in the neutrophils. These results suggested that the cells of the host mononuclear phagocyte system in leprosy granulomas provide an adequate nutritional environment for iron acquisition by M. leprae. A possible role of iron binding proteins in the granulomas is discussed in relation to previous data on bovine paratuberculous granulomas.

Biopsy↗
PubMed1985

A rapid and sensitive non-competitive avidin-biotin assay for lactoferrin.

We have developed an avidin-biotin assay for the detection of lactoferrin in human seminal plasma. We compared 5 modifications of this assay, and found the non-competitive avidin-biotin assay (NABA) to be the most sensitive. The detection limit of 3-step NABA was 0.2 or 0.1 ng lactoferrin/ml, depending whether avidin-biotin-peroxidase complex (ABC) or avidin-peroxidase was used. The intra-assay and inter-assay coefficients of variation for 3-step NABA were 6.2 and 8.5%, respectively. The lactoferrin levels of human seminal plasma samples measured by 3-step NABA and radioimmunoassay (RIA) showed good correlation (r = 0.96). The total performance time of 3-step NABA is flexible and the method can be modified for rapid (less than 1 h) or overnight assay according to need.

Avidin↗
PubMed1989

Structure of human lactoferrin: crystallographic structure analysis and refinement at 2.8 A resolution.

The structure of human lactoferrin has been refined crystallographically at 2.8 A (1 A = 0.1 nm) resolution using restrained least squares methods. The starting model was derived from a 3.2 A map phased by multiple isomorphous replacement with solvent flattening. Rebuilding during refinement made extensive use of these experimental phases, in combination with phases calculated from the partial model. The present model, which includes 681 of the 691 amino acid residues, two Fe3+, and two CO3(2-), gives an R factor of 0.206 for 17,266 observed reflections between 10 and 2.8 A resolution, with a root-mean-square deviation from standard bond lengths of 0.03 A. As a result of the refinement, two single-residue insertions and one 13-residue deletion have been made in the amino acid sequence, and details of the secondary structure and tertiary interactions have been clarified. The two lobes of the molecule, representing the N-terminal and C-terminal halves, have very similar folding, with a root-mean-square deviation, after superposition, of 1.32 A for 285 out of 330 C alpha atoms; the only major differences being in surface loops. Each lobe is subdivided into two dissimilar alpha/beta domains, one based on a six-stranded mixed beta-sheet, the other on a five-stranded mixed beta-sheet, with the iron site in the interdomain cleft. The two iron sites appear identical at the present resolution. Each iron atom is coordinated to four protein ligands, 2 Tyr, 1 Asp, 1 His, and the specific Co3(2-), which appears to bind to iron in a bidentate mode. The anion occupies a pocket between the iron and two positively charged groups on the protein, an arginine side-chain and the N terminus of helix 5, and may serve to neutralize this positive charge prior to iron binding. A large internal cavity, beyond the Arg side-chain, may account for the binding of larger anions as substitutes for CO3(2-). Residues on the other side of the iron site, near the interdomain crossover strands could provide secondary anion binding sites, and may explain the greater acid-stability of iron binding by lactoferrin, compared with serum transferrin. Interdomain and interlobe interactions, the roles of charged side-chains, heavy-atom binding sites, and the construction of the metal site in relation to the binding of different metals are also discussed.

Amino Acid Sequence↗
PubMed1983

Spectroscopic studies on copper (II) complexes of human lactoferrin.

The interaction of Cu(II) with human lactoferrin has been studied as a function of pH, using electronic and electron spin resonance spectroscopy. Specific Cu(II) binding, with bicarbonate as the co-anion, occurs over the pH range 6 to 9. In the presence of a fiftyfold molar excess of oxalate, a monocopper(II) lactoferrin oxalate complex forms when the Cu(II) to protein is 1:1. If this ratio is increased to 2:1, a hybrid complex forms, in which the second copper utilizes bicarbonate as the co-anion, thus demonstrating, as for serum transferrin, a difference in the anion binding sites. The quenching of the intrinsic fluorescence of apolactoferrin is significantly less in the presence of oxalate than bicarbonate. The interaction of Cu(II) with apolactoferrin in the presence of the malonate, glycolate, thioglycolate, glycinate, and ethylenediaminetetraacetate ions has been examined.

Bicarbonates↗
PubMed1996

Lactoferrin inhibits herpes simplex virus type 1 adsorption to Vero cells.

This paper describes the ability of human and bovine lactoferrins (HLf; BLf), iron-binding proteins belonging to the non-immune defense system, to interfere with herpes simplex virus type 1 (HSV-1) infection. Since lactoferrins are known to bind to heparan sulphate proteoglycans and to low density lipoprotein receptor, which in turn act as binding sites for the initial interaction of HSV-1 with host cells, we tested the effect of these proteins on HSV-1 multiplication in Vero cells. Both HLf and BLf are found to be potent inhibitors of HSV-1 infection, the concentrations required to inhibit the vital cytopathic effect in Vero cells by 50% being 1.41 microM and 0.12 microM, respectively. HLf and BLf exerted their activity through the inhibition of adsorption of virions to the cells independently of their iron withholding property showing similar activity in the apo- and iron-saturated form. The binding of [35S]methionine-labelled HSV-1 particles to Vero cells was strongly inhibited when BLf was added during the attachment step. BLf interacts with both Vero cell surfaces and HSV-1 particles, suggesting that the hindrance of cellular receptors and/or of viral attachment proteins may be involved in its antiviral mechanism.

Animals↗
PubMed1994

Fourier transform infrared spectroscopy and differential scanning calorimetry of transferrins: human serum transferrin, rabbit serum transferrin and human lactoferrin.

Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) have been used to investigate the solution structure and thermal stability of human serum transferrin (HST), human lactoferrin (HLF) and rabbit serum transferrin (RST) in their diferric and apo forms. Our study shows that: (A) The secondary structure of all the proteins studied (estimated in H2O) was in the range 43-53% alpha-helix and 23-28% beta-sheet. These values differ markedly from previously reported circular dichroism (CD) data. This is attributed to the fact that FTIR and CD measure different aspects of secondary structure (hydrogen bonding and dihedral angles, respectively). (B) The secondary structural content of the proteins is not altered by iron binding or release. However, the iron-free proteins undergo a greater extent of 1H-2H exchange than the diferric proteins indicating that significant structural changes do occur upon iron binding/release. (C) The removal of iron leads to thermal destabilization of HST, HLF and RST. Structural variation in the apo transferrins is indicated by the observation of a single irreversible DSC transition for apo human lactoferrin, a double DSC transition for apo human serum transferrin (one reversible) and a broad irreversible asymmetric DSC transition for apo rabbit serum transferrin. FTIR spectroscopy shows that a distinct loss of protein secondary structure occurs at the transition temperatures shown by DSC.

Animals↗
PubMed1995

Lactoferrin as a sensitive blood marker of neutrophil activation in normal pregnancies.

OBJECTIVE: To test lactoferrin as a marker of neutrophil activation during pregnancy. DESIGN: Cross-sectional study in normal pregnant (n = 100), nonpregnant (n = 11) and post partum women (n = 30). METHODS: Serum or plasma measurements of neutrophils, lactoferrin, vitamin C, vitamin E, lipid peroxide, elastase, C-reactive protein gamma-glutamyltranspeptidase, haptoglobin and osmotic fragility. RESULTS: During normal pregnancy all markers of neutrophil-activation increase. CONCLUSION: Neutrophil-activation compromises the antioxidant defense mechanism during normal pregnancy.

Adult↗