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PubMed1993

Comparison of cytosolic calcium shifts, superoxide generation, and lactoferrin secretion in the neutrophils of atopics and nonatopics.

We previously found that platelet-activating factor (PAF) stimulated greater lactoferrin secretion by neutrophils of atopics than nonatopics. To help understand underlying mechanisms, we compared agonist-stimulated lactoferrin secretion with another response, superoxide generation, to determine whether there is a global alteration in the reactivity of atopic neutrophils to these stimuli. We also determined Ca2+ mobilization in such neutrophils because such mobilization is a signaling pathway for both superoxide generation and granule content exocytosis. Although PAF again stimulated greater lactoferrin secretion in atopic than in nonatopic neutrophils, the peak superoxide secretion and cytosolic Ca2+ mobilization were not significantly different in atopics and nonatopics. Leukotriene B4-induced superoxide secretion and cytosolic Ca2+ shifts were also similar in atopics and nonatopics. These findings suggest that (1) the enhanced PAF-induced lactoferrin secretion in atopic neutrophils is not a reflection of greater PAF binding or broad-based cell hyperreactivity and (2) a selective signaling pathway in atopic neutrophils may be responsible for the enhanced lactoferrin secretion. These findings may be relevant to in vivo events because we have found increased PAF and lactoferrin release in skin chambers overlying immunoglobulin E-mediated human skin reactions.

Calcium↗

PubMed1993

Bovine lactoferrin in involuting mammary tissue.

Bovine lactoferrin in involuting mammary tissue was identified by immunohistochemistry and tissue explant culture. Immunoreactive lactoferrin was associated with mammary epithelial cells. Immunostaining for lactoferrin increased during involution, in contrast to declining immunostaining of epithelia for the milk-specific protein beta-lactoglobulin. Immunostaining for lactoferrin also was observed at the basal region of alveolar epithelia, perhaps in association with basement membrane components. Lactoferrin was preferentially synthesized in involuting mammary tissue compared with lactating tissue. Synthesis of lactoferrin in the involuting mammary gland occurs despite the apparent decline in synthesis of milk-specific proteins.

Animals↗

PubMed1994

Synthesis of lactoferrin and casein by explants of bovine mammary tissue.

Synthesis of lactoferrin and casein by the bovine mammary gland was determined in an experimental model where lactation was maintained in one mammary half, while involution was induced in the contralateral half. Culture of explants with prolactin had no consistent effect on synthesis of casein or lactoferrin in tissue from either mammary half. Endotoxin and tumor necrosis factor-alpha generally decreased synthesis of casein and lactoferrin, suggesting that these inflammatory mediators are not directly responsible for increasing lactoferrin synthesis during mammary inflammation or involution. Synthesis of lactoferrin was increased and casein decreased in the involuting mammary half vs. the lactating half. These results suggest that local factors in the mammary gland play a role in the regulation of lactoferrin synthesis during involution.

Animals↗

PubMed2000

Amonabactin-mediated iron acquisition from transferrin and lactoferrin by Aeromonas hydrophila: direct measurement of individual microscopic rate constants.

The effectiveness and mechanism of iron acquisition from transferrin or lactoferrin by Aeromonas hydrophila has been analyzed with regard to the pathogenesis of this microbe. The ability of A. hydrophila's siderophore, amonabactin, to remove iron from transferrin was evaluated with in vitro competition experiments. The kinetics of iron removal from the three molecular forms of ferric transferrin (diferric, N- and C-terminal monoferric) were investigated by separating each form by urea gel electrophoresis. The first direct determination of individual microscopic rates of iron removal from diferric transferrin is a result. A. hydrophila 495A2 was cultured in an iron-starved defined medium and the growth monitored. Addition of transferrin or lactoferrin promoted bacterial growth. Growth promotion was independent of the level of transferrin or lactoferrin iron saturation (between 30 and 100%), even when the protein was sequestered inside dialysis tubing. Siderophore production was also increased when transferrin or lactoferrin was enclosed in a dialysis tube. Cell yield and growth rate were identical in experiments where transferrin was present inside or outside the dialysis tube, indicating that binding of transferrin was not essential and that the siderophore plays a major role in iron uptake from transferrin. The rate of iron removal from diferric transferrin shows a hyperbolic dependence on amonabactin concentration. Surprisingly, amonabactin cannot remove iron from the more weakly binding N-terminal site of monoferric transferrin, while it is able to remove iron from the more strongly binding C-terminal site of monoferric transferrin. Iron from both sites is removed from diferric transferrin and it is the N-terminal site (which does not release iron in the monoferric protein) that releases iron more rapidly! It is apparent that there is a significant interaction of the two lobes of the protein with regard to the chelator access. Taken together, these results support an amonabactin-dependent mechanism for iron removal by A. hydrophila from transferrin and lactoferrin. The implications of these findings for an amonabactin-dependent mechanism for iron removal by A. hydrophila from transferrin and lactoferrin are discussed.

Aeromonas hydrophila↗

PubMed2006

Calprotectin and lactoferrin in the assessment of intestinal inflammation and organic disease.

BACKGROUND AND AIMS: Calprotectin and lactoferrin are specific neutrophil-derived proteins, which can be measured in the feces because they are released by cells in inflammatory conditions. We evaluated the efficacy of calprotectin and lactoferrin in detecting organic disease as assessed by colonoscopy. METHODS: The study comprised 144 patients undergoing colonoscopy for lower gastrointestinal symptoms (abdominal pain, altered bowel habits, and bloody stools) (67), or inflammatory bowel disease activity, or surveillance for dysplasia (77). A single stool sample was assayed for calprotectin and lactoferrin. The proportion of patients correctly diagnosed with each test and the relationship with endoscopic and histological findings were measured. RESULTS: Fecal excretion of calprotectin significantly correlated with the finding of colonic inflammation at endoscopy, both in ulcerative colitis and in Crohn's disease (p<0,001 and p<0,008, respectively), while lactoferrin excretion significantly correlated with histological inflammation (p=0.001 and p=0.009 respectively). Recommended cut-off values need to be adjusted in the inflammatory bowel disease group. Overall sensitivity, specificity, positive predictive value, and diagnostic efficacy were 78, 83, 86, and 80% for calprotectin and 80, 85, 87, and 81% for lactoferrin, respectively. CONCLUSIONS: Fecal calprotectin and lactoferrin appear to be equally recommendable as inflammatory disease markers in patients with lower gastrointestinal symptoms. Both tests are needed to accurately discriminate activity in inflammatory bowel disease patients.

Adolescent↗

PubMed1976

The effect of trypsin on bovine transferrin and lactoferrin.

The iron-saturated and iron-free (apo) forms of bovine transferrin and lactoferrin were digested with trypsin and the digests analysed by column chromatography and electrophoresis. Both of the iron-saturated proteins were more resistant to proteolysis than the corresponding apoproteins, and iron-transferrin was more resistant than iron-lactoferrin. Digestion of iron-transferrin yielded two iron-binding fragments with molecular weights of 32 000 and 38 500 whereas apotransferrin yielded only the larger fragment. In digests of lactoferrin, up to five different fragments with molecular weights ranging from 25 000 to 52 700 were detected, there being no obvious qualitative difference between digests of iron-lactoferrin and apolactoferrin. The susceptibility of apolactoferrin to tryptic digestion was only slightly reduced when apolactoferrin was complexed with beta-lactoglobulin, suggesting that complex-formation is not a mechanism for protecting lactoferrin against intestinal degradation. There was no immunological cross reaction between bovine transferrin or its digestion products against anti-lactoferrin antiserum, or vice-versa.

Animals↗

PubMed1994

Immunochemical detection of human lactoferrin in feces as a new marker for inflammatory gastrointestinal disorders and colon cancer.

We have developed a new immunochemical test for fecal lactoferrin (LF) utilizing an enzyme-linked immunosorbent assay (ELISA). The ELISA had a sensitivity of about 10 micrograms/L of lactoferrin and the measurable range was 10.0-1000.0 micrograms/L (1.0-100.0 micrograms LF/g feces). The stability of lactoferrin in feces was greater than that of myeloperoxidase and leucocyte elastase. The fecal concentration of lactoferrin (mean +/- SD) in 35 normal subjects was 0.75 +/- 0.83 microgram/g feces, whereas that in 24 patients with colon cancer was 74.4 +/- 88.3 micrograms/g feces. The fecal lactoferrin concentration of 38 patient with active ulcerative colitis was 307.4 +/- 233.9 micrograms/g feces, and that in 36 patients with active Crohn's disease was 191.7 +/- 231.1 micrograms/g feces. The ELISA for human fecal lactoferrin might be useful in the diagnosis of colon disease.

Adolescent↗

PubMed1984

Kinetic effect of human lactoferrin on the growth of Escherichia coli 0111.

Previous studies have suggested that human lactoferrin has a bacteriostatic effect on Escherichia coli 0111 growth. Determination of the time required for cultures to reach one-half maximal cell density (t1/2) indicates that within the concentration range of lactoferrin used in this study, its effect in vitro on the growth of E. coli 0111 is kinetic rather than bacteriostatic. Compared to a control, added apo-lactoferrin (250-1000 micrograms/ml) produced only a delay effect as seen by an increase in the t1/2 indicating these concentrations are probably within the subinhibitory concentration range. The kinetic delay effect of apo-lactoferrin is also consistently increased in the presence of Zn2+ and Cu2+ cations. Cu2+, Zn2+ and NTA (nitrilotriacetate) did not affect the growth rate of this organism in the absence of lactoferrin compared to the control. These studies indicate that the mechanism by which lactoferrin alters the bacterial growth of E. coli 0111 is more complex than simple iron deprivation.

Cations, Divalent↗

PubMed1993

Lactoferrin binding to human platelets.

1. Platelets bind specifically lactoferrin. 2. The lactoferrin binding to the platelets depends on the concentration of labelled lactoferrin, the number of platelets, the time of incubation and pH. 3. The binding was characterized by two types of binding site: one with high affinity and low capacity, and another with low affinity and high capacity (respectively Kaff1 = 13.6 x 10(9) l/mol and about 40 binding sites, and Kaff2 = 1.23 x 10(9) l/mol and about 135 binding sites per platelet). 4. Both human transferrin and bovine lactoferrin compete with human lactoferrin for the receptors. 5. The presence of lactoferrin receptors on the platelet membrane surface is connected most probably with the effect(s) on the cell function(s) of these cells.

Binding Sites↗

PubMed1993

Analysis of human and bovine milk lactoferrins by Rotofor and chromatofocusing.

1. Isoelectric points of human and bovine lactoferrins were evaluated by Rotofor and chromatofocusing analysis. 2. By Rotofor, the isoelectric value of human lactoferrin fraction was determined at 8.7 and that of bovine lactoferrin at 8.8. 3. By chromatofocusing analysis, human and bovine lactoferrins showed different elution patterns. Human lactoferrin was eluted at pH 6.8-8 and bovine lactoferrin eluted at pH 8.2-8.9.

Animals↗

PubMed1994

Characterization of lactoferrin binding to the MAC-T bovine mammary epithelial cell line using a biotin-avidin technique.

1. A non-radioisotopic method utilizing a biotin-avidin approach was used to characterize lactoferrin binding to the clonal MAC-T bovine mammary epithelial cell line. 2. Binding of lactoferrin to MAC-T cells and isolated membranes was specific and saturable. 3. Unlabeled lactoferrin competed for and displaced biotin-labeled lactoferrin from binding sites on mammary epithelial cells. In contrast, unlabeled transferrin did not compete. 4. Scatchard analysis of lactoferrin binding to MAC-T cell crude membranes was nonlinear, revealing two classes of binding sites with association constants (Ka) of 2.36 x 10(7) and 3.36 x 10(6) M-1. 5. Binding of lactoferrin to MAC-T cells may be associated with the initial events which result in decreased MAC-T cell proliferation.

Animals↗

PubMed1994

Lactoferrin contains structural motifs of ribonuclease.

A high molecular weight ribonuclease isolated from human milk (hmRNAase) shares identical immunological, physical, structural features and considerable sequence homology with human lactoferrin; and it has been demonstrated to be an isoform of lactoferrin. We have analyzed the sequence data of lactoferrin looking for the existence of specific features corresponding to the consensus sequence of pyrimidine-specific ribonucleases. The analysis was done by comparing sequence features with respect to elements which are, in principle, responsible for RNAase activity. This revealed the existence of a ribonuclease-signature pattern in lactoferrin. Further analysis of X-ray data together with molecular modeling studies have revealed close similarities between the spatial geometry of the constituent groups of the active site of pyrimidine-specific ribonucleases and the corresponding groups comprising the potential active site of lactoferrin. Our results provide the strong structural basis for the existence of ribonuclease activity in lactoferrin.

Amino Acid Sequence↗

PubMed1983

Identification of lactoferrin as an essential growth factor for human lymphocytic cell lines in serum-free medium.

A serum-free medium supplemented with growth factor(s) was devised to grow human lymphocytic cell lines. The medium was developed using human lymphocytic cell line, Bri 7 cells. In the process of constructing the medium, human lactoferrin was found to be an essential growth factor for the cell line. Human lactoferrin has higher growth stimulatory activity than human transferrin, and was sensitive to heat. Long-term cultivation of the cells was achieved in the defined medium supplemented with human lactoferrin only. The defined medium specifically supported the growth of various other human B- and T-lymphocytic cell lines but not the growth of various mouse lymphocytic cell lines. In lactoferrin-supplemented medium, the growth of some human cell lines were further stimulated by the addition of a combination of insulin, ethanolamine and selenium, or another combination of 2-mercaptoethanol and the above three factors. Bovine lactoferrin could be substituted for human lactoferrin.

Animals↗

PubMed1992

Lactoferrin and lysozyme in the intrahepatic bile duct of normal livers and hepatolithiasis. An immunohistochemical study.

Lactoferrin and lysozyme have bactericidal activities and are responsible for mucosal defense against local bacterial infections. To assess the local defense mechanisms in the intrahepatic biliary tree, we studied the distribution of lactoferrin and lysozyme immunohistochemically in 14 normal autopsy livers and in 29 surgically resected and two autopsy livers of hepatolithiasis. In the latter, bacterial infection was constantly found. Lactoferrin and lysozyme were detected in low doses and in specific areas in the intramural and extramural glands of certain normal livers. In contrast, in hepatolithiasis, the incidence of lactoferrin- and lysozyme-positive cases significantly increased both in the intramural glands (94% and 77% of 31 cases, respectively) and in the extramural glands (72% and 48% of 29 cases, respectively) (p less than 0.01) in the stone-containing bile ducts. These glands proliferated considerably in the stone-containing bile ducts and were stained more widely and intensely than in normal livers. These data suggest that these proliferated peribiliary glands in the stone-containing bile ducts produce and secrete significant amounts of lactoferrin and lysozyme. Increased production and secretion of lactoferrin and lysozyme suggests activated local defense mechanisms against bacterial infection in the stone-containing bile ducts, and may be beneficial for inhibition of the growth of calculi and prevention of the suppurative inflammation.

Adult↗

PubMed1983

The effect of trypsin and chymotrypsin on the in vitro antimicrobial and iron-binding properties of lactoferrin in human milk and bovine colostrum. Unusual resistance of human apolactoferrin to proteolytic digestion.

The susceptibility of lactoferrin in bovine colostrum and human milk to digestion by trypsin and chymotrypsin has been investigated. Neither enzyme had much effect on the lactoferrin-mediated antimicrobial activity of human milk, and the iron binding capacity of lactoferrin in the milk was only slightly reduced. Likewise both enzymes had only a slight effect on the iron-binding capacity of purified lactoferrin. Although iron-free (apo)lactoferrin was slightly more susceptible to digestion, especially by chymotrypsin, than the iron-saturated form, the difference was much less than has been found in earlier studies with other proteins of the transferrin class. In contrast, trypsin destroyed the antimicrobial activity of bovine colostrum, and, in line with earlier studies, appreciably reduced the iron-binding capacity of both colostrum and purified bovine apolactoferrin. Bovine iron-saturated lactoferrin was more resistant to digestion. The unusual resistance of human apolactoferrin to proteolysis may reflect an evolutionary development designed to permit its survival in the gut of the infant.

Animals↗

PubMed1992

Binding of bovine lactoferrin to Streptococcus agalactiae.

Bovine lactoferrin is an iron-binding protein present in mammary gland secretions. The exposure of Streptococcus agalactiae to bovine lactoferrin resulted in the binding of this protein to all the 12 strains of bovine origin tested, and also, although to a lesser degree, to the five tested strains of human origin. The interaction of lactoferrin with one high-binding bovine strain (24/60, the prototype NT/X strain) was studied. Binding was time-dependent, dose-dependent, and saturable. The binding of lactoferrin was slightly affected by cultivation conditions, and appeared to be heat-stable. The binding of biotinylated lactoferrin was inhibited by unlabelled lactoferrin but not by bovine serum albumin.

Animals↗

PubMed1989

Gastric luminal digestion of lactoferrin and transferrin by preterm infants.

Lactoferrin, a milk iron-binding protein, may play antimicrobial, iron-absorptive and growth-promoting roles in the developing gastrointestinal tract. To perform such functions, lactoferrin must survive digestive processes in the gut lumen in an active form. We investigated the gastric digestion of lactoferrin in addition to that of the other milk proteins, transferrin and casein, in preterm infants by measuring their degradation during incubation in vitro at 37 degrees C with gastric fluid at pH 1.8, 3.2 and 5.8. Fluid was obtained 1 h after a milk feeding, a time of maximum peptic activity, from 12 infants with a mean gestational age of 29.7 +/- 0.8 weeks at birth and a postnatal age of 24.7 +/- 3.2 days at sampling. Hydrolysis of all three proteins as indicated by generation of trichloroacetic acid soluble material from iodinated substrate was maximal at acid pH and declined by greater than 75% at pH 5.8, lactoferrin was less rapidly degraded than casein at low pH and transferrin breakdown was intermediate. Analysis of reaction mixtures by SDS-polyacrylamide gel electrophoresis showed degradation of lactoferrin and transferrin to low molecular weight products at pH 3.2 but minimal breakdown at pH 5.8. Several discrete fragments were generated at low pH, including species with molecular weights of 41,000-42,000 which may represent half-molecules. We conclude that dietary lactoferrin and transferrin may be degraded by preterm infant gastric fluid to discrete species, but that hydrolysis may be minimal at the prevailing postprandial pH. Consequently they may be rendered available for possible subsequent biological action within the infant.

Caseins↗

PubMed1980

Relationships between iron and vanadium metabolism: the association of vanadium with bovine lactoferrin.

Bovine milk was incubated simultaneously with 48VO2+ and 59Fe3+ ions. The lactoferrin was separated by ion exchange gel chromatography on CM Sephadex C-50 resin. Sephacryl 200 gel filtration of the lactoferrin-containing fractions, from ion exchange chromatography was carried out to dertermine the proportions of 48V and 59Fe radioactivities associated with macromolecules of the size of lactoferrin. It was found that 48V was incorporated into lactoferrin, the milk protein which contains iron. This suggests that lactoferrin may play a role in the bioavailability of vanadium during lactation, as vanadium is an essential element for the growth of some animal species. More generally, the vanadium binding properties of lactoferrin further support previous findings on the possible biochemical role of Fe-containing non hemoproteins in the metabolism of vanadium.

Chromatography, Ion Exchange↗