The developmental profile of lactoferrin in mouse epididymis

Lactoferrin: A glycoprotein that plays an active role in human health

Lactoferrin (Lf), existing widely in human and mammalian milk, is a multifunctional glycoprotein with many functions, such as immune regulation, anti-inflammation, antibacterial, antiviral, and antioxidant. These extensive functions largely attribute to its ability to chelate iron and interfere with the cellular receptors of pathogenic microorganisms and their hosts. Moreover, it is non-toxic and has good compatibility with other supplements. Thus, Lf has been widely used in food nutrition, drug carriers, biotechnology, and feed development. Although Lf has been continuously explored and studied, a more comprehensive and systematic compendium is still required. This review presents the recent advances in the structure and physicochemical properties of Lf as well as clinical studies on human diseases, with the aim of providing a reference for further research of Lf and the development of its related functional products.

Effects of exogenous lactoferrin on characteristics and functions of bovine epididymal, ejaculated and frozen-thawed sperm

The purpose of this study was to investigate effects of addition of lactoferrin on characteristics and functions of bovine epididymal, ejaculated, and frozen-thawed sperm. The addition of lactoferrin was significantly (p < .05) effective on increasing values of progressive motility, straightness, and linearity in caput epididymal sperm and values of motility in cauda epididymal sperm. When ejaculated sperm were incubated in capacitation medium, percentages of motile and progressively motile sperm decreased largely within the first period of 30 min, followed by only minor changes. However, the addition of lactoferrin significantly lessened the early decreases of these parameters and additionally promoted capacitation-dependent changes of chlortetracycline staining patterns (from F pattern to B pattern). In other experiments, when ejaculated sperm were exposed to oxidative stress with 100-µM H₂ O₂ , the addition of lactoferrin partially protected them from dysfunction of flagellar movement and loss of progressive movement. In final experiments with frozen-thawed samples incubated in the capacitation medium, the addition of lactoferrin effectively survived dying sperm and suppressed occurrence of sperm agglutination. These results may suggest biological and biotechnological potentials of lactoferrin for modulation of bovine sperm viability, motility, capacitation state, and preservation in vitro.

Effects of Estrogen Treatment on Aging in the Rat Epididymis

Previous studies from our laboratory demonstrated that estrogen signaling in the testis contributes to maintaining spermatogenesis in adult rats, and that estrogen treatment attenuated the age-associated decline in sperm production. The purpose of this study was to determine if epididymal function is also altered with age, and what effects estrogen treatment may have on the epididymis during aging. We compared untreated rats at 3 and 15 months of age to 18-month-old vehicle-treated and estrogen treated rats. In all four groups, tubule and lumen diameter of the cauda was significantly larger than more proximal regions of the epididymis. In the 3-, 15-, and 18-month-old treated animals, the epithelial cell height of the cauda was significantly shorter than that of more proximal regions. The caput cell height was shorter at 18 months compared to 3 months but this was not seen in estrogen treated animals. Thus, estrogen appears able to prevent some age related changes in epididymal morphology. Sperm transit time through the distal cauda was significantly delayed with aging. Estrogen treatment prevented this delay, indicating that sperm transit through the epididymis is an estrogen regulated function. Differences in estradiol and testosterone concentrations were observed between 3- and 15-month-old animals, but no further differences were noted between treated or untreated animals at 18 months. Interestingly, expression of androgen receptor and estrogen receptor alpha were similar between ages and treatments. Collectively, these results suggest epididymal morphology and function are affected by aging and estrogen treatment. Anat Rec, 302:1447-1457, 2019. © 2018 Wiley Periodicals, Inc.

Effects of In Utero and Lactational Exposure to New Generation Green Plasticizers on Adult Male Rats: A Comparative Study With Di(2-Ethylhexyl) Phthalate

Di(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer, is a ubiquitous environmental contaminant and may act as an endocrine disruptor. Early life exposures to DEHP may result in anti-androgenic effects, impairing the development of the male reproductive tract. However, data on the long-lasting consequences of such DEHP exposures on adult male reproductive function are still rare and discrepant. Previously, we identified 2 novel plasticizers, 1,4-butanediol dibenzoate (BDB) and dioctyl succinate (DOS), as potential substitutes for DEHP that did not reproduce classically described endocrine disrupting phenotypes in prepubertal male offspring after maternal exposure. Here, we investigated the consequences of in utero and lactational exposure to BDB and DOS on adult male rat reproductive function in a comparative study with DEHP and a commercially available alternative plasticizer, 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH). Timed pregnant Sprague Dawley rats were gavaged with vehicle or a test chemical (30 or 300 mg/kg/day) from gestation day 8 to postnatal day 21. While DEHP exposure (300 mg/kg/day) significantly increased epididymal weight in the adult, exposure to DINCH, BDB, or DOS did not affect reproductive organ weights, steroid levels, or sperm quality. Using a toxicogenomic microarray approach, we found that adult testicular gene expression was affected by exposure to the higher dose of DEHP; transcripts such as Nr5a2, Ltf, or Runx2 were significantly downregulated, suggesting that DEHP was targeting estrogen signaling. Lesser effects were observed after treatment with either DINCH or BDB. DOS exposure did not produce such effects, confirming its potential as a responsible substitute for DEHP.

Immunolocalization of estrogen and androgen receptors in the caput epididymidis of the fat sand rat (Psammomys obesus): Effects of seasonal variations, castration and efferent duct ligation

The fat sand rat (Psammomys obesus) is a model to study seasonal reproductive cycle changes and several metabolic disorders. In order to show a possible involvement of estrogens in the male reproductive functions, the expression of estrogen receptors (ESR1 and ESR2) and androgen receptor (AR) were investigated in the caput epididymidis of fat sand rats during the breeding season, resting season, after castration, after castration followed by testosterone treatment, and after ligation of efferent ducts. In the breeding season, principal cells presented a strong immunostaining of AR in both nuclei and cytoplasm, a strong staining of ESR1, mainly in the apical zone, and a strong immunoexpression of ESR2, mainly in nuclei. In the resting season, a moderate immunostaining of AR in both cytoplasm and nuclei was observed. ESR1 staining showed a strong immunoreactivity in the nuclei. In contrast, the nuclei were negative for ESR2. After castration, a low and selective signal distribution was observed: the nuclei were moderately positive for AR and ESR2, and negative for ESR1. After castration and testosterone treatment, an androgen-dependence for AR and the restoration of ESR1 but not ESR2 immunoexpression were observed. After ligation of the efferent ducts, a considerable reduction of AR immunoreactivity was observed in contrast to ESR1 and ESR2, which gave a strong immunostaining signal. These results illustrate the complexity of the regulation of the androgen and estrogen receptor expression in the epididymis and argue for the coexistence of both androgenic and estrogenic pathways.

Lactotransferrin in Asian elephant (Elephas maximus) seminal plasma correlates with semen quality

Asian elephants (Elephas maximus) have highly variable ejaculate quality within individuals, greatly reducing the efficacy of artificial insemination and making it difficult to devise a sperm cryopreservation protocol for this endangered species. Because seminal plasma influences sperm function and physiology, including sperm motility, the objectives of this study were to characterize the chemistry and protein profiles of Asian elephant seminal plasma and to determine the relationships between seminal plasma components and semen quality. Ejaculates exhibiting good sperm motility (≥65%) expressed higher percentages of spermatozoa with normal morphology (80.3±13.0 vs. 44.9±30.8%) and positive Spermac staining (51.9±14.5 vs. 7.5±14.4%), in addition to higher total volume (135.1±89.6 vs. 88.8±73.1 ml) and lower sperm concentration (473.0±511.2 vs. 1313.8±764.7×10⁶ cells ml⁻¹) compared to ejaculates exhibiting poor sperm motility (≤10%; P<0.05). Comparison of seminal plasma from ejaculates with good versus poor sperm motility revealed significant differences in concentrations of creatine phosphokinase, alanine aminotransferase, phosphorus, sodium, chloride, magnesium, and glucose. These observations suggest seminal plasma influences semen quality in elephants. One- and two-dimensional (2D) gel electrophoresis revealed largely similar compositional profiles of seminal plasma proteins between good and poor motility ejaculates. However, a protein of ∼80 kDa was abundant in 85% of ejaculates with good motility, and was absent in 90% of poor motility ejaculates (P<0.05). We used mass spectrometry to identify this protein as lactotransferrin, and immunoblot analysis to confirm this identification. Together, these findings lay a functional foundation for understanding the contributions of seminal plasma in the regulation of Asian elephant sperm motility, and for improving semen collection and storage in this endangered species.

Lactoferrin knockout mice demonstrates greater susceptibility to Aggregatibacter actinomycetemcomitans-induced periodontal disease

BACKGROUND

Among the innate defense mechanisms in the oral cavity, lactoferrin (LF) is a vital antimicrobial that can modify the host response against periodontopathogens. Aggregatibacter actinomycetemcomitans is the main periodontopathogen of localized aggressive periodontitis. The aim of this study is to evaluate the role of LF during A. actinomycetemcomitans-induced periodontitis.

METHODS

Differences in the expression levels of cytokines, chemokines, chemokine receptors, and bone loss markers between wild-type (WT) and LF knockout mice (LFKO(-/-)) were evaluated by real time-PCR. Serum IgG and LF levels were quantified by ELISA. Alveolar bone loss among the groups was estimated by measuring the distance from cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) at 20 molar sites.

RESULTS

Oral infection with A. actinomycetemcomitans increased LF levels in periodontal tissue (P = 0.01) and saliva (P = 0.0004) of wild-type infected (WTI) mice compared to wild-type control mice. Pro-inflammatory cytokines such as interferon-γ, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-12 were increased in the infected LF knockout (LFKO(-/-)I) mice compared to the WTI mice, whereas the anti-inflammatory cytokines IL-4 and IL-10 were decreased. Chemokines and chemokine receptors showed different expression patterns between WTI and LFKO(-/-)I mice. The LFKO(-/-)I mice developed increased bone loss (P = 0.002), in conjunction with increased expression of receptor activator of nuclear factor-κB ligand and decrease in osteoprotegerin, compared to WTI mice.

CONCLUSIONS

These results demonstrate that the infected LFKO(-/-) mice were more susceptible to A. actinomycetemcomitans-induced alveolar bone loss, with different patterns of immune responses compared to those of WTI mice.

Expression of lactoferrin in the boar epididymis: effects of reduced estrogen

Lactoferrin is regulated by estrogen in the female reproductive tract and evidence in immature mice suggests that it may be estrogen regulated in males as well. The estrogen regulation of lactoferrin in the epididymis of the boar, a high estrogen-producing male, is unknown. This study was designed to test the hypothesis that lactoferrin expression in the boar epididymis is regulated by estrogen. Twenty-one littermate pairs of boars were treated with vehicle or Letrozole, an aromatase inhibitor, from 1 week of age until castration at 2 through 8 months. Epididymal tissue was collected at castration and fixed for immunolocalization of lactoferrin. Epididymal and testicular tissues were also collected from five mature boars (1-2.5 years) and fixed for immunocytochemistry (ICC). Lactoferrin was localized in the principal cell cytoplasm of the caput, corpus and cauda of developing boars but only in the corpus and cauda of mature boars. Basal cells were negative for lactoferrin. Sperm in the corpus and cauda was also positive for lactoferrin. The efferent ducts and testes were negative for lactoferrin. Intensity of lactoferrin immunostaining increased with age in the corpus and cauda regardless of treatment. Reduced endogenous estrogen in the epididymis during development did not affect the intensity of immunostaining between control and Letrozole-treated animals. Lactoferrin expression in the epididymis of the developing boar does not appear to be regulated by estrogen.

Estrogen and androgen receptor expression in relation to steroid concentrations in the adult boar epididymis

The steroid hormone regulation of the epididymis in a high estrogen producing animal like the boar is not currently understood. To test the hypothesis that the boar epididymis is an estrogen and androgen responsive tissue, the presence of estrogen and androgen receptors, in conjunction with steroid hormone concentrations were investigated in the boar epididymis. Epididymal (caput, corpus, cauda) and testicular samples of boars (1-2.5 years; n=5) were collected for immunolocalization of estrogen receptor alpha (ERalpha), estrogen receptor beta (ERbeta) and androgen receptor (AR). Concentrations of testosterone, estradiol and estrogen conjugates (EC) in the tissue were also determined. AR and ERbeta were localized in the principal and basal cells of all three epididymal regions. ERalpha was localized in the principal cells of the caput, some cells of the corpus and was not present in the cauda. Testosterone (p<0.0001), estradiol (p<0.0001) and EC (p<0.005) were significantly lower in the epididymis compared with the testis. The epididymal regions were not significantly different from each other for testosterone (p>0.15) or estradiol (p>0.09). EC were significantly higher in the corpus than either the caput (p=0.003) or cauda (p=0.002). These results suggest that the boar epididymis is responsive to both estrogens and androgens and that both steroid hormones are important for proper epididymal function. Since testosterone and estradiol concentrations are similar throughout the epididymis, regional differences in steroid hormone regulation are likely due to differences in receptor expression.

Coordinated transcriptional regulation patterns associated with infertility phenotypes in men

INTRODUCTION

Microarray gene-expression profiling is a powerful tool for global analysis of the transcriptional consequences of disease phenotypes. Understanding the genetic correlates of particular pathological states is important for more accurate diagnosis and screening of patients, and thus for suggesting appropriate avenues of treatment. As yet, there has been little research describing gene-expression profiling of infertile and subfertile men, and thus the underlying transcriptional events involved in loss of spermatogenesis remain unclear. Here we present the results of an initial screen of 33 patients with differing spermatogenic phenotypes.

METHODS

Oligonucleotide array expression profiling was performed on testis biopsies for 33 patients presenting for testicular sperm extraction. Significantly regulated genes were selected using a mixed model analysis of variance. Principle components analysis and hierarchical clustering were used to interpret the resulting dataset with reference to the patient history, clinical findings and histological composition of the biopsies.

RESULTS

Striking patterns of coordinated gene expression were found. The most significant contains multiple germ cell-specific genes and corresponds to the degree of successful spermatogenesis in each patient, whereas a second pattern corresponds to inflammatory activity within the testis. Smaller-scale patterns were also observed, relating to unique features of the individual biopsies.

Formulation and evaluation of lactoferrin bioadhesive tablets

For the treatment of chronic inflammation in the oral cavity, we attempted to develop bioadhesive tablets of bovine lactoferrin (B-LF) which has antibacterial properties and immune regulatory functions. B-LF tablets containing pectin, tamarind gum or carboxymethylcellulose (CMC) were prepared by direct compression. Tablets consisting of B-LF, pectin and xylitol passed through 60- or 100-mesh sieves were also prepared. The tablets containing CMC had insufficient bioadhesive force. Although the tablets containing tamarind gum showed the longest residence time in the oral cavity, an unpleasant taste gradually developed. The tablets containing pectin showed the highest value of bioadhesive force and the taste was acceptable. The characteristics of the B-LF tablets were improved by adding an appropriate amount of xylitol and using the ingredients sieved by a 100-mesh sieve. The therapeutic effect was evaluated by using rats with an ulcer on the oral mucosa. In the present study, swelling on the periphery of the ulcer was observed after administration of the B-LF tablets, and then the ulcer has reduced overall.

Influence of Pectins on Preparation Characteristics of Lactoferrin Bioadhesive Tablets

For the treatment of chronic inflammation in the oral cavity, we attempted to develop bioadhesive tablets of bovine lactoferrin (B-LF). Pectin was used as a bioadhesive polymer, and the influence of the degree of esterification and the molecular weight of pectins on the characteristics of B-LF tablets were investigated. Concerning bioadhesive force, a tendency increasing the value according to increase of the esterification of the pectin was confirmed. Sustained release of B-LF from the tablets was observed as the esterification increased, and a possibility for prediction of the time required to release 50% of B-LF by using the equation given by the degree of esterification and the logarithm of the molecular weight was suggested. Pectin cross-linked with Ca(2+) (Ca-PC) was also used for the preparation of the B-LF tablets. Prolonged release of B-LF from the tablets was observed as the Ca(2+) in Ca-PC increased. Our findings suggest that pectin with a high degree of esterification is suitable as a bioadhesive polymer since high bioadhesive force and sustained release are shown. Furthermore, a possibility that the B-LF release could be controlled by adjusting the Ca(2+) concentration in Ca-PC was suggested.

Immunolocalization of estrogen and androgen receptors and steroid concentrations in the stallion epididymis

The presence of steroids and their receptors throughout development, specifically androgen receptor (AR), estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta), in the epididymis of a high estrogen producing species like the stallion has not been determined. Epididymal and testicular samples were collected for analysis of testosterone and estradiol-17beta (E(2)) concentrations and for immunolocalization of AR, ERalpha and ERbeta. The concentration of testosterone in the testis and epididymis were not different among age groups (P>0.05). AR was localized in the principal cells of the caput, corpus and cauda in all four age groups. This lack of change in testosterone concentration and receptor localization suggests that testosterone is important for both development and maintenance of epididymal function. There was an age-related increase in E(2) concentrations in all regions of the epididymis (P<0.05), suggesting that E(2) is also important for adult function. ERbeta was localized in the principal cells of the caput, corpus and cauda in all four age groups, but the localization of ERalpha was regional and age dependent. In peri-pubertal animals, ERalpha immunostaining was most prominent and estradiol was similarly present in all three epididymal regions; this suggests that estradiol also plays a key role in the maturation of the stallion epididymis during the pubertal transition when sperm first arrive in the epididymis. In conclusion, these results suggest that the stallion epididymis is regulated by both androgens and estrogens throughout development and that estradiol is more important to epididymal function in the stallion than previously believed.

Developmental gene expression of lactoferrin and effect of dietary iron on gene regulation of lactoferrin in mouse mammary gland

This study evaluated the developmental gene expression of lactoferrin (LF) and the effect of supplementary iron on gene expression of LF in the mammary gland of mice using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. In experiment 1, a total of 12 female mice were used to determine the effect of different lactating stages on mRNA expression of LF. The Institute of Cancer Research mice were divided into 4 groups; each group of 3 mice was tested on d 1, 9, 17, and 25 of lactation. In experiment 2, 6 groups of mice (total of 24 female mice at d 12 after mating) were fed purified diets (without iron or supplement iron) and were assigned to 2 treatments (control and treatment). The experimental feeding period lasted 35 d. During the feeding experiment, 6 mice (3 animals in each group) were chosen on d 1, 9, 17, and 25 of lactation to determine the effect of iron on LF mRNA expression of mice at different stages of lactation. The results of experiment 1 showed that LF mRNA had strong expression on d 1 of lactation, decreased gradually on d 9 and 17 of lactation, and then increased again markedly on d 25 of lactation. These results imply that the expression of LF in the mammary gland at different lactating stages is consistent with the changes in LF concentrations in milk. Iron significantly increased LF mRNA expression on d 1 and 25 of lactation. Iron did not statistically increase LF gene expression on d 9 and 17 of lactation. These findings raised the possibility that iron supplementation may play a role in regulation of LF levels in vivo.

Developmental gene expression of lactoferrin in duodenum and effect of weaning age on gene expression of lactoferrin in piglets

Two experiments were conducted to evaluate duodenal gene expression of lactoferrin and effect of weaning age on mRNA expression of lactoferrin in piglets using semi-quantitative RT-PCR analysis. In experiment 1, a total of 15 female Duroc x Landrace x Yorkshire piglets of five groups, each group pigs at 1, 14, 28, 42 and 56 days of age were used to determine developmental gene expression of lactoferrin in duodenum. In experiment 2, a total of 18 female neonatal piglets were divided into three groups, which were weaned at 21, 28 and 35 days of age respectively. In each group, three piglets' duodena were sampled at 21, 28 and 35 days of age and the other three piglets' duodena were sampled 7 days after weaning in each group. The samples were collected for detecting the effect of weaning age on lactoferrin mRNA expression of piglets. The results show that lactoferrin mRNA levels decreased steadily in postnatal day 1-56. But only from day 28-42 (14 days after weaned), the levels of lactoferrin gene expression were decreased markedly (p < 0.05), and the difference of lactoferrin mRNA levels at other stages was not significant. This result suggested that weaning had an effect on gene expression of lactoferrin. The results of experiment 2 showed that when the piglets were weaned at 21-28 and 35 days of age respectively, the expression levels of lactoferrin were decreased by 77%, 53% and 59% at the seventh day after weaning. Our results showed that weaning significantly decreased lactoferrin mRNA expression of piglets.

Suppression of endogenous estrogen during development affects porcine epididymal sperm maturation

Estrogen plays an important role in male reproduction, critical for sustained fertility in some species. Reducing estrogen's interaction with its receptor(s) in monkey and mouse models is associated with reduced sperm motility and, in some cases, documented elimination of sperm fertilizing ability, suggesting that normal epididymal function may be estrogen dependent. The objective of these experiments was to evaluate the effects of reduced endogenous estrogen on development of epididymal function in the pig, a species in which males have very high levels of endogenous estrogen. Letrozole, a potent inhibitor of estrogen synthesis, was administered to neonatal boars from 1 week of age and markedly suppressed estrogen production. Epididymal function assessed as acquisition of sperm fertilizing ability (in vitro fertilization of zona-free oocytes) was reduced in Letrozole-treated animals at 24 and 28 weeks of age (23% and 30% fertilization, respectively compared with 37% and 54% in vehicle controls) but had recovered by 32 weeks of age. Cauda epididymal sperm numbers were reduced in treated animals (35% of control values at 20 weeks of age) but appeared to be recovering at 32 weeks of age. Reduction of endogenous estrogen had no effect on other aspects of epididymal function (percentage of motile sperm, sperm motion parameters, sperm head morphometrics, or ability of sperm to undergo an acrosome reaction). Reducing endogenous estrogen during postnatal development appears to have transient effects on porcine epididymal function. These transient effects suggest that the pig, with its high endogenous estrogen, may respond differently than other species to reduced estrogen synthesis.

Expression of porcine lactoferrin by using recombinant baculovirus in silkworm, Bombyx mori L., and its purification and characterization

Lactoferrin is a multifunctional glycoprotein that is present in several mucosal secretions. In this study, we exploited the silkworm, Bombyx mori, as host for the recombinant baculovirus harboring the porcine lactoferrin (PLF) gene to produce the recombinant PLF (rPLF). Around 205 mug of rPLF was purified from a single silkworm pupa infected by the virus and the rPLF was proved to be biologically active. This method established in our study will pave the way for efficient industrial production of rPLF on a large scale for further utilization of this protein as a feed additive in the future.

Relationship between seminal plasma lactoferrin and gonadal function in horses

Total 78 semen samples were obtained from 27 Thoroughbred stallions (aged 6 to 27 years), and were subjected to quantification of lactoferrin (Lf) in seminal plasma and examination of the seminal properties. The seminal plasma Lf concentration varied from 21 to 689 microg/ml, with a mean value of 244 +/- 151 microg/ml (S.D.). The seminal plasma Lf concentration and total seminal plasma Lf positively correlated with the sperm concentration (r=0.5938, P<0.001) and with the total sperm number (r=0.6959, P<0.001), respectively. There was no correlation between seminal plasma Lf and sperm motility. These results suggest that seminal plasma Lf reflects gonadal function.

Seminal plasma lactoferrin but not transferrin reflects gonadal function in dogs

Lactoferrin purified from canine seminal plasma by a three-step chromatography procedure had a molecular mass of 75.2 kDa and cross-reacted with antiserum to equine seminal plasma lactoferrin. Seminal plasma lactoferrin concentrations were determined by a competitive enzyme-linked immunosorbent assay (ELISA) by using rabbit anti-equine lactoferrin antibody and alkaline phosphatase-labeled goat anti-rabbit IgG antibody in 14 normal dogs and found to range from 12 to 197 micro g/ml, with a mean value of 77 +/- 59 micro g/ml (the mean +/- SD). Seminal plasma transferrin concentrations were determined by a sandwich ELISA with goat antibody to canine serum transferrin and alkaline phosphatase-conjugated goat anti-canine transferrin antibody and found to range from 0.32 to 12.6 micro g/m l, with a mean value of 2.44 +/- 3.25 micro g/m l. The lactoferrin concentration significantly correlated with the sperm concentration (r=0.7025, P<0.01), but there was no significant correlation between the seminal plasma transferrin concentration and sperm density. These results indicate that seminal plasma lactoferrin, but not transferrin, reflects gonadal function.

Purification and quantification of lactoferrin in equine seminal plasma

Lactoferrin with a molecular mass of 80 kDa was purified from equine seminal plasma by heparin-Agarose affinity chromatography and Sephacryl S-200 gel filtration. Purified lactoferrin was found to be highly homogeneous on the bases of its migration as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and of the monospecificity of rabbit antibodies to the purified protein in immunoblotting of seminal plasma proteins. A sandwich enzyme-linked immunosorbent assay was developed for quantifying lactoferrin in equine seminal plasma. Seminal plasma lactoferrin concentrations in 23 normal stallions ranged from 42 to 453 microg/ml, with a mean value of 157 +/- 118 microg/ml (S.D.).

Antiinflammatory activities of lactoferrin

Lactoferrin is a non-heme iron binding glycoprotein produced during lactation and by epithelial cells at mucosal surfaces. The protein is a prominent component of the first line of mammalian host defense and its expression is upregulated in response to inflammatory stimuli. In this paper, the antibacterial and immune modulatory properties of lactoferrin that contribute to host defense are reviewed. In addition, the results of recent preclinical and clinical studies demonstrating that lactoferrin acts as an inhibitor of dermal inflammatory cytokine production are summarized. The results indicate that lactoferrin may act as a potent anti-inflammatory protein at local sites of inflammation including the respiratory and gastrointestinal tracts.

Various forms of mouse lactoferrins: purification and characterization

This work was conducted to study the microheterogeneity of mouse lactoferrin (LF). Two forms, LF1 and LF2, could be purified from uterine luminal fluid by ion-exchange HPLC on a Protein PAK SP 5PW column. Another form, LF3, was purified from the epididymis homogenate by affinity chromatography on a column of Protein A-Sepharose coupled with the purified LF2 antibody that was prepared to give no crossreaction with serum albumin. Both LF1 and LF2 showed a Mr 74000 band while LF3 gave a Mr 70000 band on reducing SDS-PAGE. All of them were reduced to a Mr 68000 band after they had been digested with N-glycosidase F. The data from automated Edman degradation confirmed the completely identical 19 amino acid sequences in the N-terminal regions of these three LFs, except the lack of N-terminal Lys-Ala of LF2/LF3 in LF1. LF in tissue homogenates was immunodetected by Western blot procedure using the purified LF2 antibody. Different amounts of LF with a molecular mass of the 70000 or 74000 were distributed in the non-sexual organs such as kidney, spleen, lung, heart and liver and the sexual glands including epididymis, vagina, uterus, ovary and prostate. No LF was detected in stomach, intestine, testis and seminal vesicle.

Restricted spatiotemporal expression of lactoferrin during murine embryonic development

Lactoferrin is a member of the transferrin family of iron-binding glycoproteins. Lactoferrin is induced by estrogen in the mouse uterus during early pregnancy. However, the expression and function, if any, of lactoferrin in the preimplantation embryo during this developmental period has not been investigated. In the current study, the spatiotemporal expression of lactoferrin during murine embryogenesis was examined using in situ hybridization and immunohistochemical analyses. Lactoferrin expression was first detected in the 2-4 cell fertilized embryo and continued until the blastocyst stage of development. Interestingly, at the 16-cell stage, coinciding with the first major differentiation step in the embryo, lactoferrin messenger RNA (mRNA) is synthesized by the inner cells, whereas the protein is selectively taken up by the outside cells. This differential pattern of lactoferrin messenger RNA and protein localization continues until the blastocyst stage, with expression almost absent in the hatched blastocyst. Lactoferrin expression does not resume in the embryo until the latter half of gestation, where it is first detected in neutrophils of the fetal liver at embryonic day 11.5 and later in epithelial cells of the respiratory and digestive systems. Our results show that lactoferrin is expressed in a tightly regulated spatiotemporal manner during murine embryogenesis and suggest a novel paracrine role for this protein in the development of the trophoectodermal lineage during preimplantation development.

The hydrophobic pocket of 24p3 protein from mouse uterine luminal fluid: fatty acid and retinol binding activity and predicted structural similarity to lipocalins

The conformation of 24p3 protein purified from mouse uterine luminal fluid was studied by circular dichroism spectroscopy in 200-300 nm. At pH 7.4, the spectrum in the UV region appears as one negative band with a minimum mean residue ellipticity of -3,600 deg.cm2.dmole(-1) at 217 nm, suggesting a very low or no helical content, but a considerable amount of beta-form, beta-turn, and unordered form in the protein molecule. This agrees with the predicted secondary structures consisting of only one a-helical segment of residues 150-163 and nine segments of residues 28-35, 50-60, 67-72, 78-86, 94-97, 106-114, 119-125, 136-140 and 166-172 in beta-forms, which would construct two orthonormal beta-sheets to form a less polar beta-barrel. The environments around Trp-31 and Trp-81 of this protein were studied by intrinsic fluorescence and solute quenching. They give an emission peak at 332 nm, and only about 21% of them are accessible to quenching by acrylamide. This together with their low accessibility to either CsCI or KI suggests that they are located in the less polar beta-barrel. Hydrophobic compounds such as fatty acids, retinoids, and cholesteryl oleate in the protein solution diminish the protein fluorescence. Analysis of the fluorescence data suggests that the protein has a binding site for hydrophobic ligand. The association constants for the complex formation are 1.03 x 10(6) MM(-1), 1.92 x 10(5) M(-1), 2.38 x 10(5) M(-1) or 1.25 x 10(5) M(-1) for cholesteryl oleate, oleic acid, retinol, or retinoic acid at pH 7.4. Analysis of the equilibrium binding data from binding assay using [H3]-retinol and [H3]-retinoic acid reveals a singular type of retinoid-binding site in the protein with the association constant of 4.92 x 10(5) M(-1) and 1.17 x 10(5) M(-1) for retinol and retinoic acid, respectively. Trp-31 or/ and Trp-81 is in or very near the binding site and the gross conformation of protein changes considerably as the formation of protein-ligand complex.

Restricted spatiotemporal expression of lactoferrin during murine embryogenesis

Lactoferrin is a member of the transferrin family of iron-binding proteins to which several physiological functions have been ascribed. While there is a wealth of evidence about the distribution and function of this protein in the adult, the expression and function, if any, of lactoferrin during embryogenesis has not been investigated. In the current study, the spatiotemporal distribution of lactoferrin was analyzed during normal murine embryonic development. This analysis demonstrated that lactoferrin is expressed in three distinct patterns during embryogenesis. First, lactoferrin is expressed at the 2-cell stage in the preimplantation embryo where it continues to be expressed until the blastocyst stage when expression ceases. The second phase of lactoferrin expression is not detected until the latter half of gestation when the protein is detected in the myeloid cells, beginning in the fetal liver at embryonic day 11 and later in the spleen and bone marrow coinciding with the onset and diversification of myelopoiesis in these organs during embryogenesis. Finally, lactoferrin is detected in a variety of glandular epithelial cells and/or their secretions, including respiratory and oral epithelia which is consistent with the expression pattern observed for this protein in the adult where it plays an important role in host defense at the mucosal surface. Taken together, these analyses indicate that the role of lactoferrin in the developing embryo is restricted to the preimplantation stage and development of first and second line host defense systems.

Expression and characterization of recombinant murine lactoferrin

Lactoferrin (Mw=78 kDa) is a member of the transferrin family of iron-binding glycoproteins. Previous studies carried out primarily in vitro indicate that the protein has multifunctional properties and may be involved in regulation of iron homeostasis, inhibition of bacterial growth and regulation of immune responses. However, the significance and species specificity of these proposed functions in vivo have not been adequately addressed due to lack of sufficient purified homospecies lactoferrin for analysis in small animal models. We previously reported the successful production of biologically active recombinant human lactoferrin using an Aspergillus expression system. In the present study, we report the production of recombinant murine lactoferrin using a similar expression strategy. Recombinant murine lactoferrin was purified to homogeneity and was similar in size and immunoreactivity to native murine milk lactoferrin. The recombinant protein was correctly processed at its N-terminus and was glycosylated. Interestingly, while both human and murine lactoferrin bind iron in a 2:1 molar ratio, iron bound to recombinant murine lactoferrin was more acid labile than human lactoferrin, demonstrating species-specific variation in the stability of iron-binding to this protein. Finally, the availability of recombinant murine lactoferrin will now facilitate the study of the species specificity of lactoferrin action in a mouse model system.

Direct evidence for the secretion of lactoferrin and its binding to sperm in the porcine epididymis

Lactoferrin has been for the first time purified from the porcine cauda epididymal fluid as a 70 kDa protein. Both Western and Northern blot analyses show that lactoferrin is synthesized in the regions from the distal caput to the cauda epididymis and secreted into the luminal fluid. Lactoferrin is first secreted as a 75 kDa glycoprotein and its carbohydrate moieties are gradually digested to form 70 kDa protein in the cauda epididymis. Lactoferrin has already bound to the surface of the epididymal sperm because the anti-lactoferrin antiserum induces the mature sperm tail-to-tail agglutination. These results strongly suggest new physiological functions of lactoferrin on the sperm maturation in the epididymis.

Demonstration of a glycoprotein derived from the 24p3 gene in mouse uterine luminal fluid

A glycoprotein in mouse uterine luminal fluid was purified to homogeneity via a series of purification steps involving Sephadex G-100 chromatography, Sephadex G-50 chromatography and HPLC on a reverse-phase C18 column, in that order. Automated Edman degradation was unable to determine the N-terminal residue of the glycoprotein and the partial sequences determined from its trypsin digests were found to be identical with the protein sequence deduced from 24p3 cDNA. The core protein and the total amount of carbohydrate together gave a molecular mass of 25.8 kDa. Results from the characterization of the glycopeptide bond indicated the presence of N-linked carbohydrate but no O-linked carbohydrate in the protein, which has two potential sites for N-linked carbohydrate at Asn81 and Asn85, as deduced from analysis of the primary structure. The core protein was shown to have a molecular mass equal to that of the putative protein deduced from cDNA, suggesting that this protein may contain no signal peptide. Results of Northern-blot analysis for various tissues of adult mice revealed that the 24p3 gene was expressed in lung, spleen, uterus, vagina and epididymis.

Cooperative interactions between the amino- and carboxyl-terminal lobes contribute to the unique iron-binding stability of lactoferrin

Lactoferrin is a member of the transferrin family of iron-binding proteins. Several functions have been ascribed to lactoferrin, including regulation of iron homeostasis, antibacterial properties, and regulation of myelopoiesis. However, the structural features of lactoferrin that are required for most of these functions are unknown. Previously, we reported the development of an efficient fungal expression system to produce recombinant human lactoferrin. The availability of this production system demonstrated the feasibility of producing mutant lactoferrins to address the structure/function relationship of the protein. In the present study, we used a site-directed mutagenesis approach to address the contribution of the bilobal structure of lactoferrin to its unique iron-binding stability. Like transferrin, lactoferrin consists of two repeated iron-binding lobes that bind one iron atom each. However, unlike transferrin, lactoferrin retains iron over a broad pH range, a key property that contributes to the unique iron-binding functions of the protein. Using mutants that selectively ablate the iron-binding function in either lobe, we demonstrate differential iron-binding stability of the amino- and carboxyl-terminal iron-binding lobes of lactoferrin. Further, we show that the unique iron-binding stability of the protein is imparted primarily by the carboxyl-terminal domain which functions cooperatively to stabilize iron-binding to the amino-terminal domain of lactoferrin.

A system for production of commercial quantities of human lactoferrin: a broad spectrum natural antibiotic

We previously reported the production of limited quantities of biologically active recombinant human lactoferrin in the filamentous fungus Aspergillus oryzae. In the present study, we report a modification of this production system combined with a classical strain improvement program that has enabled production of levels of recombinant human lactoferrin in excess of 2 g/l. The protein was expressed in Aspergillus awamori as a glucoamylase fusion polypeptide which was secreted into the growth medium and processed to mature human lactoferrin by an endogenous KEX-2 peptidase. The recombinant protein retains full biological activity in terms of its ability to bind iron and human enterocyte receptors. Furthermore, the recombinant protein functions as a potent broad spectrum antimicrobial protein.