Human lactoferrin supplementation of infant formulas increases thymidine incorporation into the DNA of rat crypt cells

The need to study human milk as a biological system

Critical advancement is needed in the study of human milk as a biological system that intersects and interacts with myriad internal (maternal biology) and external (diet, environment, infections) factors and its plethora of influences on the developing infant. Human-milk composition and its resulting biological function is more than the sum of its parts. Our failure to fully understand this biology in a large part contributes to why the duration of exclusive breastfeeding remains an unsettled science (if not policy). Our current understanding of human-milk composition and its individual components and their functions fails to fully recognize the importance of the chronobiology and systems biology of human milk in the context of milk synthesis, optimal timing and duration of feeding, and period of lactation. The overly simplistic, but common, approach to analyzing single, mostly nutritive components of human milk is insufficient to understand the contribution of either individual components or the matrix within which they exist to both maternal and child health. There is a need for a shift in the conceptual approach to studying human milk to improve strategies and interventions to support better lactation, breastfeeding, and the full range of infant feeding practices, particularly for women and infants living in undernourished and infectious environments. Recent technological advances have led to a rising movement towards advancing the science of human-milk biology. Herein, we describe the rationale and critical need for unveiling the multifunctionality of the various nutritional, nonnutritional, immune, and biological signaling pathways of the components in human milk that drive system development and maturation, growth, and development in the very early postnatal period of life. We provide a vision and conceptual framework for a research strategy and agenda to change the field of human-milk biology with implications for global policy, innovation, and interventions.

Identification and Peptidomic Profiling of Exosomes in Preterm Human Milk: Insights Into Necrotizing Enterocolitis Prevention

SCOPE

Human breast milk has been shown to prevent necrotizing enterocolitis (NEC). Although exosomes have been identified in breast milk, their function and components have not been fully addressed. This study is conducted to elucidate the differences in peptidomic complexities between preterm and term milk exosomes.

METHODS AND RESULTS

Breast milk samples are collected from healthy lactating mothers who have delivered term and preterm infants. Exosomes are separated and quantified. The protective effects of purified exosomes against NEC are investigated both in vitro and in vivo. The peptidomic complexities in term and preterm milk exosomes are analyzed by iTRAQ LC-MS/MS to screen differentially expressed exosomal peptides. Preterm milk exosomes administration significantly enhances proliferation and migration of intestinal epithelial cells compared with term milk exosomes. A total of 70 peptides are found to be significantly modulated in preterm milk samples compared to term milk samples. Of these, 47 peptides are upregulated, and 23 peptides are downregulated. Bioinformatics analysis suggests several potential regulatory roles of the altered peptides in intestinal epithelial cell function.

CONCLUSION

These results reveal the differences for the first time in peptidomic complexities between preterm and term milk exosomes. Milk exosome administration might be a promising prevention for NEC.

Comparison of Proliferative Effect of Human Lactoferrin and Its Proteolytic Peptide on Normal and Transformed Epithelial Cells

Human lactoferrin (hLF) is an iron-binding glycoprotein with a variety of functions. hLF undergoes proteolytic cleavage to smaller peptides in the stomach following ingestion. In the present study, we evaluated the effects of hLF and its proteolytic product, human lactoferrin peptide (hLFP), on the proliferation of two epithelial cells, HEK293 normal cells and KATO III gastric carcinoma cells, using an MTT assay and expression of proliferative nuclear cell antigen (PCNA), a notable proliferation marker. When the two epithelial cells were stimulated with hLF and hLFP in the presence of fetal bovine serum (FBS), hLFP stimulated proliferation of both cell types at lower concentrations than hLF by two orders of magnitude. The cancer cells exhibited proliferative responses to both hLF and hLFP at lower concentrations by 2∼3 orders of magnitude than the normal cells. Either hLF or hLFP alone did not support appreciable proliferation of these cell lines in the absence or low concentrations of FBS. Bovine serum albumin or its proteolytic product failed to promote cellular proliferation even in the presence of 10 % FBS, indicating the specificity of the proliferative activity of hLF and hLFP. These data highlight feasibility of hLF and its peptide for adjuvants for tissue culture medium.

Skimmed, sterilized, and concentrated bovine late colostrum promotes both prevention and recovery from intestinal tissue damage in mice

Bovine colostrum is a rich source of tissue repair and growth factors, and inhibits gastrointestinal injury induced by the side effects of nonsteroidal antiinflammatory drugs (NSAID), such as indomethacin. Nonsteroidal antiinflammatory drugs are drugs with analgesic and antipyretic effects, but in higher doses they have inflammatory effects. The pathogenesis of small intestinal damage caused by NSAID is unclear. The present study was performed to investigate the antiinflammatory effects of skimmed, sterilized, and concentrated bovine late colostrum on intestinal injury induced by side effects of NSAID, and then to identify the active ingredient in the colostrum for intestinal tissue. In Japan, the sale of bovine colostrum within 5 d after parturition is prohibited by law. Therefore, we focused on bovine late colostrum obtained from healthy lactating cows 6 to 7 d after parturition. Proliferation of small intestine epithelial cells was stimulated in mice fed the colostrum for 1 wk. With regard to indomethacin-induced enteropathy, both prefeeding and postfeeding with colostrum facilitated growth of the intestinal villi, indicating preventive and healing effects. Furthermore, to identify the active ingredient in the colostrum responsible for this effect, the casein and whey fractions were prepared from the colostrum and fed to normal mice. Only the colostrum casein fraction stimulated intestinal villus elongation, whereas the whey fraction and mature milk casein showed no such effect. Taken together, these observations indicate that the skimmed, sterilized, and concentrated bovine late colostrum, especially the casein fraction, could be used to treat the injurious effects of NSAID in the intestine and could be effective for treatment of other ulcerative conditions in the bowel, suggesting that the colostrum has therapeutic potential for intestinal inflammation.

Biochemical and molecular impacts of lactoferrin on small intestinal growth and development during early life1This article is part of a Special Issue entitled Lactoferrin and has undergone the Journal's usual peer review process

Postnatal modeling of the intestinal epithelium has long-term impacts on the healthy development of infants and relies largely on nutrient composition of the diet. Lactoferrin (Lf) is among the various human milk trophic factors that facilitate the infant intestinal adaptation. Hydrolysis of Lf is minimal at the prevailing postprandial pH of infants, and Lf may therefore have greater biological potential in infants than in adults. Lf bidirectionally stimulates concentration-dependent proliferation and differentiation of small intestinal epithelial cells, and therefore affects small intestinal mass, length, and epithelial digestive enzyme expression. A 105 kDa Lf receptor (LfR) specifically mediates the uptake of Lf into enterocytes and crypt cells. Mechanistically, the complex of Lf and LfR is internalized through clathrin-mediated endocytosis; both iron-free apo-Lf and iron-saturated holo-Lf activate the PI3K/Akt pathway, whereas only apo-Lf triggers ERK1/2 signaling. Lf enters the nucleus, where it can stimulate thymidine incorporation into crypt cells, regulating transcription of genes such as TGF-β1. In the fetus, the plasma membrane LfR is at the highest abundance in the small intestine, and the receptor gene is tightly controlled at multiple levels. Aspecific microRNA, miR-584, is involved in the posttranscriptional regulation of LfR, and in the human LfR DNA promoter, 2 Sp1 binding sites have been characterized functionally. Finally, cell proliferation and global gene expression reveal that native bovine Lf can perform biological activities similar to those exerted by human Lf in postnatal small intestinal development.

Apo- and holo-lactoferrin stimulate proliferation of mouse crypt cells but through different cellular signaling pathways

Lactoferrin (Lf), an iron-binding glycoprotein in human milk, plays an important role in intestinal epithelial cell proliferation, but the underlying molecular mechanisms remain unknown. Mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinases (ERK) and the phosphoinositide 3-kinase (PI3K) cascades are chief pathways controlling cell proliferation. We hypothesized that Lf stimulates proliferation of intestinal epithelial cells by activating ERK and PI3K signaling cascades and that lactoferrin receptor (LfR) is involved in these processes. Confocal microscopy showed that LfR is expressed and localized at the plasma membrane of mouse crypt cells isolated from 7 to 10 days old pups, specifically binding both iron-free Lf (apo-Lf) and iron-saturated Lf (holo-Lf). Using the BrdU assay, we observed that apo-Lf had a stronger stimulatory effect than holo-Lf on proliferation of crypt cells. Both function-blocking antibody against LfR and MEK inhibitor (U0126) resulted in inhibitory effects on apo-Lf-induced cell proliferation, whereas PI3K inhibitor (LY294002) significantly decreased both apo- and holo-Lf-induced proliferation. Although both apo- and holo-Lf up-regulated transcription of cyclin D1, an effector of ERK1/2 and PI3K/Akt signaling cascades, only apo-Lf initiated ERK1/2 signaling and both apo- and holo-Lf were capable of activating the PI3K/Akt signaling pathway. Function-blocking antibody against LfR and LfR siRNA inhibited apo-Lf induced activation of the ERK1/2 signaling pathway, suggesting that LfR is involved in apo-Lf induced activation of the ERK1/2, but not the PI3K signaling pathway. In conclusion, apo-Lf and holo-Lf stimulate intestinal proliferation but through different signaling pathways.

Breast- v. formula-feeding: impacts on the digestive tract and immediate and long-term health effects

The health benefits of breast-feeding have been recognised for a long time. In particular, breast-feeding is associated with lower incidence of necrotising enterocolitis and diarrhoea during the early period of life and with lower incidence of inflammatory bowel diseases, type 2 diabetes and obesity later in life. The higher nutritional and protective degree of human milk is related to its nutritional composition that changes over the lactation period and to the biological activities of specific components while lower growth rate of breast-fed infants may be attributed to their self-regulation of milk intake at a lower level than formula-fed infants. Many results now suggest that the developmental changes in intestinal and pancreatic function that occur postnatally are modulated by the diet. Indeed, formula-feeding induces intestinal hypertrophy and accelerates maturation of hydrolysis capacities; it increases intestinal permeability and bacterial translocation, but does not induce evident differences in microbiota composition. Whether these changes would be beneficial for enhancing absorptive capacities and for educating the gut-associated immune system remains to be further studied. Moreover, it is evident that formula-feeding increases basal blood glucose and decreases plasma ketone body concentrations, while discrepancies on postprandial glycaemia, insulin and incretin responses in both human studies and experimental studies are inconclusive. Manipulating the composition of formula, by reducing protein content, adding prebiotics, growth factors or secretory IgA can modulate intestinal and pancreatic function development, and thereby may reduce the differential responses between breast-fed and formula-fed neonates. However, the developmental responses of the digestive tract to different feeding strategies must be elucidated in terms of sensitivity to developing diseases, taking into account the major role of the intestinal microbiota.

Human lactoferrin stimulates skin keratinocyte function and wound re-epithelialization

BACKGROUND

Human lactoferrin (hLF), a member of the transferrin family, is known for its antimicrobial and anti-inflammatory effects. Recent studies on various nonskin cell lines indicate that hLF may have a stimulatory effect on cell proliferation.

OBJECTIVES

To study the potential role of hLF in wound re-epithelialization.

MATERIALS AND METHODS

The effects of hLF on cell growth, migration, attachment and survival were assessed, with a rice-derived recombinant hLF (holo-rhLF), using proliferation analysis, scratch migration assay, calcein-AM/propidium iodide staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) method, respectively. The mechanisms of hLF on cell proliferation and migration were explored using specific pathway inhibitors. The involvement of lactoferrin receptor low-density lipoprotein receptor-related protein 1 (LRP1) was examined with RNA interference technique. An in vivo swine second-degree burn wound model was also used to assess wound re-epithelialization.

RESULTS

Studies revealed that holo-rhLF significantly stimulated keratinocyte proliferation which could be blocked by mitogen-activated protein kinase (MAPK) kinase 1 inhibitor. Holo-rhLF also showed strong promoting effects on keratinocyte migration, which could be blocked by either inhibition of the MAPK, Src and Rho/ROCK pathways, or downregulation of the LRP1 receptor. With cells under starving or 12-O-tetradecanoylphorbol-13-acetate exposure, the addition of holo-rhLF was found greatly to increase cell viability and inhibit cell apoptosis. Additionally, holo-rhLF significantly increased the rate of wound re-epithelialization in swine second-degree burn wounds.

CONCLUSIONS

Our studies demonstrate the direct effects of holo-rhLF on wound re-epithelialization including the enhancement of keratinocyte proliferation and migration as well as the protection of cells from apoptosis. The data strongly indicate its potential therapeutic applications in wound healing.

Nutritional roles of lactoferrin

PURPOSE OF REVIEW

Until relatively recently, the only significant source of lactoferrin in the diet was human lactoferrin, provided in breast milk. Today, however, bovine lactoferrin, isolated by dairy technology, as well as recombinant human lactoferrin are commercially available and can be added to foods and clinical products with perceived benefits to the consumer. In this review, the potential biological functions of dietary lactoferrin are described and critically examined.

RECENT FINDINGS

Ingested lactoferrin has been suggested to exert antibacterial and antiviral activities in the intestine, in part through a direct effect on pathogens, but possibly also affecting mucosal immune function. The latter function is most likely mediated by lactoferrin being taken up by cells via a unique receptor-mediated pathway and affecting gene transcription. Lactoferrin has also been shown to enhance iron status of infants and pregnant women, possibly also via the receptor-mediated pathway. In addition, lactoferrin can stimulate intestinal cell proliferation and differentiation, causing expansion of tissue mass and absorptive capacity. On the contrary, lactoferrin has been shown to inhibit carcinogenesis. Recent findings also suggest that oral lactoferrin treatment may have an anti-inflammatory effect on pregnant women, reducing pregnancy complications.

SUMMARY

Lactoferrin treatment may have beneficial preventive and therapeutic effects on infection, inflammation, and cancer as well as enhancing iron status and growth in vulnerable groups.

The potential role of lactoferrin and derivatives in the management of infectious and inflammatory complications of hematology patients receiving a hematopoietic stem cell transplantation

Human lactoferrin is a natural defense protein belonging to the innate immune system present in several body fluids and secretions, as well as in the secondary granules of polymorphonuclear neutrophils. Lactoferrin and its derivatives have pleiotropic functions including broad-spectrum anti-microbial activity, anti-tumor activity, regulation of cell growth and differentiation, and modulation of inflammatory as well as humoral and cellular immune responses. This is the reason why much research has addressed the potential therapeutic activity of these molecules in different clinical settings, especially regarding infectious diseases and uncontrolled inflammatory conditions. In patients with hematological malignancies treated with a hematopoietic stem cell transplantation (HSCT), morbidity and mortality due to infections and uncontrolled inflammation remains high, despite many advances in supportive care. These life-threatening complications are a result of the damage caused by the conditioning regimens to the mucosal barrier, and the innate and adaptive, humoral, and cellular immune defenses. These complications necessitate the continued exploration of new treatment modalities. Systemic and probably local levels of lactoferrin are decreased following HSCT. Therefore, the use of lactoferrin, or short peptide derivatives that retain the cationic N-terminal moiety that is essential for the anti-microbial and anti-inflammatory activity, may prove to be a promising versatile class of agents for managing the complications that arise from HSCT.

Lactoferrin-enhanced anoikis: a defense against neonatal necrotizing enterocolitis

Enteral nutrition with human milk lowers the incidence of necrotizing enterocolitis in preterm human infants. Lactoferrin, the major whey protein in human milk, has many functions related to host defense against bacterial infection. Here, we hypothesize that lactoferrin also helps terminate bacterial invasion of enterocytes via a detachment-induced apoptosis called anoikis. Death of infected epithelia by anoikis prevents local spread of bacterial pathogens because the bacteria are trapped within the cell. Such infected, apoptotic and sloughed epithelia also cannot infect the lower gastrointestinal tract, and the epithelia exit the body in the stool. Currently, anoikis is a phenomenon related to the renewal of enterocytes, and it is not recognized as an anti-bacterial host defense. We suggest that anoikis of infected enterocytes is a process in which lactoferrin plays an important role. In a pilot study in which neonatal rats were pre-treated with intra-gastric recombinant human lactoferrin, we found evidence of epithelia with anoikis in ileal fluid after enteric infection. This finding was rarely seen in infected neonatal rats without pre-treatment with lactoferrin. Quantitative analysis of intestinal lavage specimens and quantitative stereology of apoptotic epithelia in this model will be required to verify the theory. We propose that oral use of recombinant human lactoferrin might have these hypothesized and other anti-bacterial effects in preterm infants, and hence, this protein might prevent necrotizing enterocolitis in preterm infants who cannot take human milk.

Anti-inflammatory activities of human lactoferrin in acute dextran sulphate-induced colitis in mice

In this study, we investigated the anti-inflammatory effects of orally administered human lactoferrin (hLF) and two peptides, based on the bactericidal region of hLF (HLD1 and HLD2), on the course of experimental colitis. Acute colitis was induced in C57Bl/6 mice by giving 5% dextran sulphate (DX) in the drinking water. The mice were killed after 2 or 7 days of DX exposure. The animals were given hLF or the peptides orally twice a day (2 mg/dose/mouse) during the DX exposure. In the control animals, the hLF or the peptides were replaced by bovine serum albumin or water. The appearance of occult blood in the faeces and macroscopic rectal bleeding were significantly delayed and partly reduced in the hLF-treated animals compared with the control animals. The shortening of the colon, a pathological effect of DX exposure, was significantly less pronounced in the hLF-treated group compared with the control group. Also, the interleukin-1beta (IL-1beta) levels in the blood were significantly diminished in this group after 2 days of DX exposure. A significantly lower crypt score was observed in the distal part of the colon in the hLF-treated group compared with the control group. Also, significantly reduced numbers of CD4 cells, F4/80-positive macrophages and tumour necrosis factor-alpha-producing cells were detected by immunohistochemistry in the distal colon of the hLF-treated animals compared with the control animals after 7 days of DX exposure. A reduction was also observed concerning the IL-10-producing cells in the middle colonic submucosa. The HLD1 and HLD2 treatment, which was carried out for 2 days, only gave results almost identical to those of hLF, concerning clinical parameters after the 2 days of DX exposure. An even stronger effect was observed for HLD2, regarding decreased occult blood in the faeces and colon length. Our results show that perorally given hLF mediates anti-inflammatory effects on the DX-induced acute colitis, and further suggest that the bactericidal region of the hLF molecule may be involved in these activities.

Iron status of infants fed low-iron formula: no effect of added bovine lactoferrin or nucleotides

BACKGROUND

The appropriate level of iron fortification in infant formula remains undetermined.

OBJECTIVES

We compared hematologic indexes and iron-status indicators in infants who were either breast-fed or fed formula with concentrations of 2 or 4 mg Fe/L and evaluated the effects of providing part of the iron as bovine lactoferrin and of adding nucleotides.

DESIGN

Healthy term infants were exclusively breast-fed (n = 16) or fed formula (n = 10-12) from age 4 +/- 2 wk to 6 mo. Anthropometric measures were taken monthly, and blood samples were taken at 1, 4, and 6 mo. Hematologic indexes; indicators of iron, zinc, and copper status; and erythrocyte fatty acids were assessed.

RESULTS

No significant differences in hematology or iron status were observed between groups at 4 and 6 mo of age. Although 34% of all infants had a hemoglobin concentration <110 g/L at 6 mo, the absence of iron deficiency or defective erythropoiesis suggests that this hemoglobin cutoff is too high for this age group. Neither the source or the concentration of iron in formula nor fortification with nucleotides had any significant effect on serum zinc or copper, and nucleotide fortification did not affect erythrocyte fatty acids.

CONCLUSIONS

A concentration of 1.6 mg Fe/L formula meets the iron requirement of healthy term infants aged </=6 mo, and providing more iron does not benefit iron stores. Fortification with bovine lactoferrin or nucleotides did not benefit either iron status or erythrocyte fatty acids. Additional studies are needed to establish age-appropriate cutoffs for iron deficiency and iron deficiency anemia in infancy.

Cell proliferation effect of lactoferrin in human endometrial stroma cells

The aim of this study was to evaluate the effect of lactoferrin (LF) on the proliferation of human endometrial stroma cells. In addition, we compared the effect of LF, oestradiol and epidermal growth factor (EGF) on the proliferation of human endometrial stroma cells. Human endometrial tissue was obtained from patients with a normal menstrual cycle in the proliferative phase and the stroma cells were isolated and cultured in vitro. When LF was added to the culture medium, the rate of cell proliferation increased significantly in comparison to controls (P < 0.01). The enhanced rate of proliferation induced by LF was neutralized by the addition of anti-LF monoclonal antibody. The effect of LF on cell proliferation at a concentration of 100 ng/ml was similar to that of 10 nmol/l oestradiol, but less than that of 10 mg/ml EGF. When LF was added in combination with either oestradiol or EGF, no additive effects on cell proliferation were observed. Based on the present results, it is suggested that LF has a potential biological effect in the proliferation of human endometrium.

Regulation of epidermal Langerhans cell migration by lactoferrin

Lactoferrin (LF) is a member of the transferrin family of iron-binding glycoproteins to which several anti-inflammatory functions have been ascribed. LF has been shown to down-regulate expression of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha), although the possibility has been raised that the activity of LF in this regard was indirect and secondary to its ability to bind to and inactivate the bacterial lipopolysaccharide (LPS) used to induce cytokine production. However, the identification of putative membrane receptors for LF raises the possibility that the interaction of LF with its receptor may be one important route through which this protein exerts anti-inflammatory activity. In the present investigations the biological properties of LF have been examined in a model of cutaneous immune function where the allergen-induced migration of epidermal Langerhans cells (LC) from the skin and their subsequent accumulation as dendritic cells (DC) in skin-draining lymph nodes are known to be dependent upon the de novo synthesis of TNF-alpha, but independent of exogenous LPS. Consistent with the protein having direct anti-inflammatory properties, it was found that the intradermal injection of recombinant murine LF (either iron-saturated or iron-depleted LF) inhibited significantly allergen (oxazolone) -induced LC migration and DC accumulation. That these inhibitory effects were secondary to the inhibition of local TNF-alpha synthesis was suggested by the findings that first, LF was unable to inhibit LC migration induced by intradermal injection of TNF-alpha itself, and second, that migration stimulated by local administration of another epidermal cytokine, interleukin 1beta, which is also dependent upon TNF-alpha production, was impaired significantly by prior treatment with LF. Finally, immunohistochemical analyses demonstrated the presence of LF in skin, associated primarily with keratinocytes. Collectively these data support the possession by LF of direct immunomodulatory and/or anti-inflammatory activity, probably associated in this case with inhibition of cytokine production. Furthermore, the results suggest that as a constituent of normal skin, LF may play a role in homeostatic regulation of cutaneous immune function.

Synthesis of lactoferrin and transport of transferrin in the lactating mammary gland of sheep

Two iron-binding proteins, lactoferrin and transferrin, are present in ruminant milk. Lactoferrin commonly has been assumed to be a product of mammary synthesis, but the origin of milk transferrin has not been elucidated. The objective of this experiment was to study the synthesis and distribution of these two proteins in the mammary gland of sheep. Explants from lactating mammary gland of sheep have been cultured in the presence of [3H]leucine to determine rates of synthesis of lactoferrin and transferrin. After incubation, [3H]lactoferrin was found, but labeled transferrin was not. The capacity of the mammary gland to synthesize lactoferrin decreased markedly in the first 24 h of lactation. Immunohistochemical techniques were utilized to identify the locations of lactoferrin and transferrin in the mammary gland. Transferrin was found in the colostrum contained in the alveolar lumen, in the cytoplasm of the secretory cells, and in the connective tissue between the mammary acini. High concentration of transferrin was found in the basal membrane of the secretory alveolar cells, mainly in those near capillary vessels. Lactoferrin was found in the colostrum and in the cytoplasm of secretory cells with a more homogeneous distribution than transferrin. The connective tissue stained negative for lactoferrin. These results suggest that, although lactoferrin is synthesized by mammary gland of the sheep, transferrin comes from blood serum, probably by a receptor-mediated mechanism of transcytosis.