Pre-clinical in vitro and in vivo safety evaluation of bovine whey derived osteopontin, Lacprodan® OPN-10

Milk Osteopontin and Human Health

Osteopontin (OPN) is a multifunctional protein found in all vertebrates. OPN is expressed in many different cell types, and is consequently found in most tissues and physiological secretions. OPN is involved in a multitude of biological processes, such as activation and regulation of the immune system; biomineralization; tissue-transformative processes, including growth and development of the gut and brain; interaction with bacteria; and many more. OPN is found in the highest concentrations in milk, where it is believed to initiate and regulate developmental, immunological and physiological processes in infants who consume milk. Processes for the isolation of bovine OPN for use in infant formula have been developed, and in recent years, many studies have investigated the effects of the intake of milk OPN. The purpose of this article is to review and compare existing knowledge about the structure and function of milk OPN, with a particular focus on the effects of milk OPN on human health and disease.

Naturally Occurring N-Terminal Fragments of Bovine Milk Osteopontin Are Transported across Models of the Intestinal Barrier

Osteopontin (OPN) is a bioactive integrin-binding protein found in high concentrations in milk, where it is present both as a full-length protein and as several N-terminally derived fragments. OPN resists gastric digestion, and via interaction with receptors in the gut or by crossing the intestinal barrier into circulation, ingested milk OPN may influence physiological processes. The aim of this study was to investigate OPN interaction with intestinal cells and its transport across models of the intestinal barrier. Immunodetection of OPN incubated with Caco-2 cells at 4 °C and 37 °C showed that OPN binds to the intestinal cells, but it is not internalised. Transepithelial transport was studied using mono- and co-cultures of Caco-2 cells and mucus-producing HT29-MTX cells in transwell membranes. OPN was shown to cross the barrier models in a time-, temperature-, and energy-dependent process inhibited by wortmannin, indicating that the transport takes place via the transcytosis pathway. Analyses of the naturally occurring milk mixture of full-length and N-terminal fragments showed that the N-terminal fragments of OPN bound intestinal cells most effectively and that the fragments were transported across the intestinal membrane models. This suggests that proteolytic processing of OPN increases its biological activity after ingestion.

The Effect of Human and Bovine Milk Osteopontin on Intestinal Caco-2 Cells: A Transcriptome Comparison

Osteopontin (OPN) is a multifunctional protein abundantly present in human milk, whereas the concentration is significantly lower in bovine milk. Human and bovine milk OPN are structurally similar and both proteins resist gastric digestion and reach the intestines in a bioactive form. Intervention studies have indicated the beneficial effects of supplementing infant formula with bovine milk OPN and several in vivo and in vitro studies have shown that bovine milk OPN positively influences intestinal development. To investigate the functional relationship, we compared the effect of simulated gastrointestinal digested human and bovine milk OPN on gene expression in Caco-2 cells. After incubation, total RNA was extracted and sequenced and transcripts were mapped to the human genome. Human and bovine milk OPN regulated the expression of 239 and 322 genes, respectively. A total of 131 genes were similarly regulated by the OPNs. As a control, a whey protein fraction with a high content of alpha-lactalbumin had a very limited transcriptional impact on the cells. Enrichment data analysis showed that biological processes related to the ubiquitin system, DNA binding, and genes associated with transcription and transcription control pathways were affected by the OPNs. Collectively, this study shows that human and bovine milk OPN have a significant and highly comparable effect on the intestinal transcriptome.

Safety evaluation of whey derived beta-lactoglobulin, Lacprodan® BLG

The safety of Lacprodan® BLG, a whey-based protein, was evaluated with respect to genotoxicity and sub-chronic toxicity according to regulatory requirements. Lacprodan® BLG did not show any mutagenic potential in a bacterial reverse mutation assay or any clastogenic or aneugenic potential in an in vitro micronucleus assay performed in human lymphocytes. In a sub-chronic toxicity study, groups of 10 male and 10 female Wistar rats received the test item orally by gavage for 90 days at dose levels of 100, 300 and 1000 mg/kg bw/day. A control group, also including 10 male and 10 female rats, received sterile water, as vehicle. No treatment-related clinical observations or toxicological effects on body or organ weights, food consumption, ophthalmic effects, hematology, clinical chemistry, fertility, urinalysis, or pathology were identified. Therefore, the no-observed-adverse-effect level (NOAEL) for Lacprodan® BLG in the 90-day toxicity study was established as 1000 mg/kg bw/day, corresponding to the highest dose level administered.

Carbon fiber reinforced polymers for implantable medical devices

Carbon fibers reinforced polymers (CFRPs) are prolifically finding applications in the medical field, moving beyond the aerospace and automotive industries. Owing to its high strength-to-weight ratio, lightness and radiolucency, CFRP-based materials are emerging to replace traditional metal-based medical implants. Numerous types of polymers matrices can be incorporated with carbon fiber using various manufacturing methods, creating composites with distinct properties. Thus, prior to biomedical application, comprehensive evaluation of material properties, biocompatibility and safety are of paramount importance. In this study, we systematically evaluated a series of novel CFRPs, aiming at analyzing biocompatibility for future development into medical implants or implantable drug delivery systems. These CFRPs were produced either via Carbon Fiber-Sheet Molding Compound or Fused Deposition Modelling-based additive manufacturing. Unlike conventional methods, both fabrication processes afford high production rates in a time-and cost-effective manner. Importantly, they offer rapid prototyping and customization in view of personalized medical devices. Here, we investigate the physicochemical and surface properties, material mutagenicity or cytotoxicity of 20 CFRPs, inclusive of 2 surface finishes, as well as acute and sub-chronic toxicity in mice and rabbits, respectively. We demonstrate that despite moderate in vitro physicochemical and surface changes over time, most of the CFRPs were non-mutagenic and non-cytotoxic, as well as biocompatible in small animal models. Future work will entail extensive material assessment in the context of orthopedic applications such as evaluating potential for osseointegration, and a chronic toxicity study in a larger animal model, pigs.

Milk proteins and their derived peptides on bone health: Biological functions, mechanisms, and prospects

Bone is a dynamic organ under constant metabolism (or remodeling), where a delicate balance between bone resorption and bone formation is maintained. Disruption of this coordinated bone remodeling results in bone diseases, such as osteoporosis, the most common bone disorder characterized by decreased bone mineral density and microarchitectural deterioration. Epidemiological and clinical evidence support that consumption of dairy products is beneficial for bone health; this benefit is often attributed to the presence of calcium, the physiological contributions of milk proteins on bone metabolism, however, are underestimated. Emerging evidence highlighted that not only milk proteins (including individual milk proteins) but also their derived peptides positively regulate bone remodeling and attenuate bone loss, via the regulation of cellular markers and signaling of osteoblasts and osteoclasts. This article aims to review current knowledge about the roles of milk proteins, with an emphasis on individual milk proteins, bioactive peptides derived from milk proteins, and effect of milk processing in particular fermentation, on bone metabolism, to highlight the potential uses of milk proteins in the prevention and treatment of osteoporosis, and, to discuss the knowledge gap and to recommend future research directions.

Early-Life Supplementation of Bovine Milk Osteopontin Supports Neurodevelopment and Influences Exploratory Behavior

INTRODUCTION

Osteopontin (OPN) is a whey protein found at high concentration in human milk and is involved in processes such as bone cell proliferation and differentiation. Milk OPN has shown to be involved in various aspects of development, including the immune system and gut health. However, the influence of dietary bovine milk OPN inclusion on brain and cognitive development has not been studied extensively until recently. This research examines whether dietary supplementation of bovine milk OPN supports brain and cognitive development in the translational pig model.

METHODS

From postnatal day (PND) 2 to 34, twenty-one intact male pigs were provided ad libitum access to one of two dietary treatments, a standard soy protein isolate-based milk replacer to serve as a control diet (n = 11) and the same base diet supplemented with bovine milk OPN to serve as a test diet (n = 10). In addition to growth and health outcomes, recognition memory was tested using the novel object recognition (NOR) task from PND 28 to 32, and magnetic resonance imaging was conducted at PND 34 to evaluate brain development.

RESULTS

No dietary effects were observed for growth performance or health indices. For the behavioral analysis, pigs that received the test diet exhibited shorter (p < 0.05) latency to the first object visited compared with pigs fed the control diet. Although the control group exhibited novelty preference, there was no difference in recognition index between dietary groups. Neuroimaging outcomes revealed increased (p < 0.05) relative brain volumes of the corpus callosum, lateral ventricle, left and right internal capsule, left and right putamen-globus pallidus, and right hippocampus, and right cortex in the test group. Diffusion tensor imaging revealed higher (p < 0.05) radial diffusivity in the corpus callosum and lower (p < 0.05) fractional anisotropy in pigs provided the test diet.

CONCLUSION

Dietary supplementation of bovine milk OPN increased the relative volume of several brain regions and altered behaviors in the NOR task. Underlying mechanisms of bovine milk OPN influencing the development of brain structures and additional behaviors warrant further investigation.

Evaluation of Bioactivities of Bovine Milk Osteopontin Using a Knockout Mouse Model

OBJECTIVES

Osteopontin (OPN) is a multifunctional protein present abundantly in human milk, but at low levels in bovine milk and infant formula. Bovine milk OPN (bmOPN) is commercially available, and may therefore, be added to formula. OPN exerts its multiple functions by binding to its receptors to activate cell signaling pathways. The OPN receptor (integrin)-binding site is conserved across species; therefore, bmOPN may exert bioactivities in humans and mice. The objective of the present study was to evaluate bioactivities of bmOPN using an established OPN knock-out (KO) mouse model.

METHODS

We evaluated bioactivities of bmOPN, including effects on intestinal growth, immune response, and brain development. In the present study, wild-type (WT) pups were nursed by WT dams, KO dams, or KO dams with bmOPN supplementation from postnatal days 1 to 21 (P1--P21).

RESULTS

Our results show that orally ingested bmOPN is partly resistant to in vivo gastrointestinal digestion, and supplemental bmOPN exhibited similar effects as mouse milk OPN (mmOPN) on promoting growth of the small intestine revealed by histological analysis of duodenum villus height and crypt depth at P10, on modifying TNF-α response against a LPS challenge at P30, as well as promoting brain myelination by increasing expression of myelin-associated glycoprotein (MAG) and myelin basic protein (MBP) and improving cognitive development.

CONCLUSIONS

Our finding that bmOPN with an amino acid sequence different from mmOPN but with a conserved integrin binding site exerts bioactivities similar to mmOPN suggests that bmOPN may provide bioactivities to human infants when added to formula.

Evaluation of Bioactivities of the Bovine Milk Lactoferrin-Osteopontin Complex in Infant Formulas

Human milk contains several bioactive proteins, including lactoferrin (LF) and osteopontin (OPN). These two proteins have been shown to form a complex, which shows increased bioactivities. Bovine LF and OPN can also form such a complex. We assessed bioactivities of the bovine LF-OPN complex (at molar ratios of LF:OPN = 3:1, 5:1, or 8:1) in a formula protein matrix, including LF, OPN, bovine whey protein hydrolysate, and α-lactalbumin. Our results show that the bovine LF-OPN complex together with formula proteins is resistant to in vitro digestion, stimulates intestinal cell proliferation (by 15-50%) and differentiation (by 30-50%), increases antibacterial activity (by 25-50%), and enhances intestinal immunity. The 3:1 ratio of LF to OPN exhibits the most potent effects, as compared with the other two ratios. In conclusion, adding bovine LF and OPN to infant formulas may result in increased stability of the two components and enhanced bioactivities, possibly improving outcomes in formula-fed infants.

Milk lactoperoxidase decreases ID1 and ID3 expression in human oral squamous cell carcinoma cell lines

Milk consumption may modify the risk of squamous cell carcinoma. The role of milk to modulate the gene expression in oral squamous cell carcinoma cells has not been investigated so far. Here, HSC2 oral squamous carcinoma cells were exposed to an aqueous fraction of human milk and a whole-genome array was performed. Among the genes that were significantly reduced by human and cow milk were the DNA-binding protein inhibitor 1 (ID1), ID3 and Distal-Less Homeobox 2 (DLX2) in HSC2 cells. Also, in TR146 oral squamous carcinoma cells, there was a tendency towards a decreased gene expression. Upon size fractionation, lactoperoxidase but not lactoferrin and osteopontin was identified to reduce ID1 and ID3 in HSC2 cells. Dairy products and hypoallergenic infant formula failed to decrease the respective genes. These data suggest that milk can reduce the expression of transcription factors in oral squamous carcinoma cells.

Osteopontin in human milk and infant formula affects infant plasma osteopontin concentrations

BACKGROUND

Osteopontin (OPN), a multifunctional protein, is present abundantly in human milk, but not in bovine milk and infant formulas. A recent randomized clinical trial showed that supplementing infant formula with bovine milk OPN (bOPN) resulted in better immune outcomes.

METHODS

Human milk OPN (hOPN) concentrations were analyzed by ELISA. Plasma samples were obtained from infants receiving one of four treatments: breast milk (BF), unsupplemented formula (F0), formula supplemented with 65 mg/L bOPN (F65), or with 130 mg/L bOPN (F130). Plasma samples were analyzed for hOPN and bOPN by ELISA.

RESULTS

The hOPN concentration was high in early lactation (D1 to D8), decreased gradually after D9, and deceased significantly after 1 month. At 4 and 6 months, higher levels of hOPN were found in plasma samples from the BF, F65, and F130 groups than in samples from the F0 group; the plasma bOPN concentration in the F130 group was greater than that in the F65 group.

CONCLUSION

Dynamic changes in the concentration of milk OPN may reflect infant needs for different amounts of milk OPN for various functions at different developmental stages. Supplemental bOPN in infant formula may exert its beneficial effects by increasing endogenous OPN in plasma.

Benefits of Lactoferrin, Osteopontin and Milk Fat Globule Membranes for Infants

The provision of essential and non-essential amino acids for breast-fed infants is the major function of milk proteins. In addition, breast-fed infants might benefit from bioactivities of milk proteins, which are exhibited in the intestine during the digestive phase and by absorption of intact proteins or derived peptides. For lactoferrin, osteopontin and milk fat globule membrane proteins/lipids, which have not until recently been included in substantial amounts in infant formulas, in vitro experiments and animal models provide a convincing base of evidence for bioactivities, which contribute to the protection of the infant from pathogens, improve nutrient absorption, support the development of the immune system and provide components for optimal neurodevelopment. Technologies have become available to obtain these compounds from cow´s milk and the bovine compounds also exhibit bioactivities in humans. Randomized clinical trials with experimental infant formulas incorporating lactoferrin, osteopontin, or milk fat globule membranes have already provided some evidence for clinical benefits. This review aims to compare findings from laboratory and animal experiments with outcomes of clinical studies. There is good justification from basic science and there are promising results from clinical studies for beneficial effects of lactoferrin, osteopontin and the milk fat globule membrane complex of proteins and lipids. Further studies should ideally be adequately powered to investigate effects on clinically relevant endpoints in healthy term infants.

Calcium-Phosphate-Osteopontin Particles Reduce Biofilm Formation and pH Drops in in situ Grown Dental Biofilms

This 2-period crossover study investigated the effect of calcium-phosphate-osteopontin particles on biofilm formation and pH in 48-h biofilms grown in situ. Bovine milk osteopontin is a highly phosphorylated glycoprotein that has been shown to interfere with bacterial adhesion to salivary-coated surfaces. Calcium-phosphate-osteopontin particles have been shown to reduce biofilm formation and pH drops in a 5-species laboratory model of dental biofilm without affecting bacterial viability. Here, smooth surface biofilms from 10 individuals were treated ex vivo 6 times/day for 30 min with either calcium-phosphate-osteopontin particles or sterile saline. After growth, the amount of biofilm formed was determined by confocal microscopy, and pH drops upon exposure to glucose were monitored using confocal-microscopy-based pH ratiometry. A total of 160 biofilms were analysed. No adverse effects of repeated ex vivo treatment with calcium-phosphate-osteopontin particles were observed. Particle treatment resulted in a 32% lower amount of biofilm formed (p < 0.05), but large inter-individual differences could be observed. Biofilm pH was significantly higher upon particle treatment, both shortly after the addition of glucose and after 30 min of incubation with glucose (p < 0.05). Calcium-phosphate-osteopontin particles may represent a new therapeutic approach to caries control and aim at directly targeting virulence factors involved in the caries process. Further studies are required to determine the effect of particle treatment on more acidogenic/aciduric biofilms as well as the remineralizing potential of the particles.

Calcium-phosphate-osteopontin particles for caries control

Caries is caused by acid production in biofilms on dental surfaces. Preventing caries therefore involves control of microorganisms and/or the acid produced. Here, calcium-phosphate-osteopontin particles are presented as a new approach to caries control. The particles are made by co-precipitation and designed to bind to bacteria in biofilms, impede biofilm build-up without killing the microflora, and release phosphate ions to buffer bacterial acid production if the pH decreases below 6. Analysis of biofilm formation and pH in a five-species biofilm model for dental caries showed that treatment with particles or pure osteopontin led to less biofilm formation compared to untreated controls or biofilms treated with osteopontin-free particles. The anti-biofilm effect can thus be ascribed to osteopontin. The particles also led to a slower acidification of the biofilm after exposure to glucose, and the pH always remained above 5.5. Hence, calcium-phosphate-osteopontin particles show potential for applications in caries control.