The effect of whey acidic protein fractions on bone loss in the ovariectomised rat

Bioactive peptides of whey: obtaining, activity, mechanism of action, and further applications

Bioactive peptides derived from diverse food proteins have been part of diverse investigations. Whey is a rich source of proteins and components related to biological activity. It is known that proteins have effects that promote health benefits. Peptides derived from whey proteins are currently widely studied. These bioactive peptides are amino acid sequences that are encrypted within the first structure of proteins, which required hydrolysis for their release. The hydrolysis could be through in vitro or in vivo enzymatic digestion and using microorganisms in fermented systems. The biological activities associated with bio-peptides include immunomodulatory properties, antibacterial, antihypertensive, antioxidant and opioid, etc. These functions are related to general conditions of health or reduced risk of certain chronic illnesses. To determine the suitability of these peptides/ingredients for applications in food technology, clinical studies are required to evaluate their bioavailability, health claims, and safety of them. This review aimed to describe the biological importance of whey proteins according to the incidence in human health, their role as bioactive peptides source, describing methods, and obtaining technics. In addition, the paper exposes biochemical mechanisms during the activity exerted by biopeptides of whey, and their application trends.

Septoclasts expressing epidermal fatty acid-binding protein (E-FABP, FABP5) in endochondral ossification

BACKGROUND

Long-chain fatty acids (LCFAs) and retinoic acid (RA) are abundant in the growth plates (GPs) of long bones; however, their roles have not been elucidated. We observed that epidermal fatty acid-binding protein (E-FABP/FABP5) with a high affinity for both LCFAs and RA is exclusively expressed in the septoclasts located at the chondro-osseous junction (COJ) of the GP.

HIGHLIGHTS

E-FABP expressed in septoclasts is involved in both LCFA metabolism and RA signaling as an intracellular transporter of both LCFAs and RA. Septoclasts with shortened cytoplasmic processes are associated with cartilage resorptive activity downregulation because of E-FABP deficiency or excess or deficiency of RA. In ontogeny, the septoclasts are differentiated from the pericytes and involved in the resorption of the uncalcified matrix of the cartilage templates in endochondral ossification.

CONCLUSION

Septoclasts originate from pericytes and express E-FABP to play crucial roles in uncalcified matrix resorption by LCFA metabolism and RA signaling during endochondral ossification.

The Role of Milk Components, Pro-, Pre-, and Synbiotic Foods in Calcium Absorption and Bone Health Maintenance

Increasing peak bone mass during adolescence and reducing bone loss in later life are two approaches to reduce the risk of osteoporosis with aging. Osteoporosis affects a large proportion of the elderly population worldwide and the incidence is increasing. Milk consumption is an accepted strategy in building peak bone mass and therefore may reduce the risk of osteoporosis. In childhood calcium, phosphorous, and growth factors are the important components to support bone growth but in adults the positive influence on bone density/maintenance may also be due to other bioactive proteins/peptides or lipids in milk acting directly in the gastrointestinal tract (GIT). Lactose has been known to increase calcium absorption; galactooligosaccharides (GOS) are derived from lactose and are non-digestible oligosaccharides. They have been shown to improve mineral balance and bone properties as well as causing increases in bifidobacteria in the gut, therefore a prebiotic effect. Supplementation with fortified milk and dairy products with added prebiotics, increased both calcium and magnesium absorption and caused some modulation of gut microbiota in animals and humans. Fermented milk is now also recognized to contain highly active components such as vitamins, peptides, oligosaccharides, and organic acids. In this review, the role of milk and milk components in improving calcium absorption and thereby supporting bone health is discussed. In addition, some reference is made to the significance of combining the inherent beneficial components from milk with fortificants/nutrients that will support bone health through adulthood. Novel data suggesting differences in diversity of the microbiota between healthy and osteoporotic women are provided.

Osteoanabolic activity of whey-derived anti-oxidative (MHIRL and YVEEL) and angiotensin-converting enzyme inhibitory (YLLF, ALPMHIR, IPA and WLAHK) bioactive peptides

Exploring bone rebuilding anabolic agents has been gaining much attention due to their potential therapeutic effects in treating several bone disorders including osteoporosis. Whey protein has been reported to affect bone health osteoanabolically, in terms of proliferation and differentiation of primary osteoblast cells. This study investigates whether whey derived anti-oxidative (AO) (P1- MHIRL, P2- YVEEL) and angiotensin converting enzyme inhibitory (ACE inhibitory) (P3- YLLF, P4-ALPMHIR, P5-IPA, P6- WLAHK) bioactive peptides affect the proliferation and differentiation of primary osteoblast cells isolated from rat calvaria. The proliferation and osteogenic activity of osteoblast cells in presence of these peptides were determined by MTT assay, DNA quantification study, Alkaline phosphatase activity (ALP) and ALP staining, Alizarin red activity and staining, and secretory osteocalcin measurement. The expression of osteogenesis-related genes (COLI-α, ALP, OCN and RUNX2) were determined by real-time quantitative PCR (RT-PCR) analysis over a period of 21days. The peptide treated osteoblasts showed a significant increase in viable cell density and proliferation in the order of P2>P6>P3 at optimised concentration. Furthermore, the osteoblastic differentiation markers in response to these peptides were found to be significantly up regulated in the order of P2>P6>P3 when compared to the controls. These results demonstrated that bioactive whey-derived AO and ACE inhibitory peptides can play a potential therapeutic role in osteoporosis by activating osteoblasts anabolically.

Whey Protein Concentrate Hydrolysate Prevents Bone Loss in Ovariectomized Rats

Milk is known as a safe food and contains easily absorbable minerals and proteins, including whey protein, which has demonstrated antiosteoporotic effects on ovariectomized rats. This study evaluated the antiosteoporotic effect of whey protein concentrate hydrolysate (WPCH) digested with fungal protease and whey protein concentrate (WPC). Two experiments were conducted to determine (1) efficacy of WPCH and WPC and (2) dose-dependent impact of WPCH in ovariectomized rats (10 weeks old). In Experiment I, ovariectomized rats (n=45) were allotted into three dietary treatments of 10 g/kg diet of WPC, 10 g/kg diet of WPCH, and a control diet. In Experiment II, ovariectomized rats (n=60) were fed four different diets (0, 10, 20, and 40 g/kg of WPCH). In both experiments, sham-operated rats (n=15) were also fed a control diet containing the same amount of amino acids and minerals as dietary treatments. After 6 weeks, dietary WPCH prevented loss of bone, physical properties, mineral density, and mineral content, and improved breaking strength of femurs, with similar effect to WPC. The bone resorption enzyme activity (tartrate resistance acid phosphatase) in tibia epiphysis decreased in response to WPCH supplementation, while bone formation enzyme activity (alkaline phosphatase) was unaffected by ovariectomy and dietary treatment. Bone properties and strength increased as the dietary WPCH level increased (10 and 20 g/kg), but there was no difference between the 20 and 40 g/kg treatment. WPCH and WPC supplementation ameliorated bone loss induced by ovariectomy in rats.

Expression of epidermal fatty acid binding protein (E-FABP) in septoclasts in the growth plate cartilage of mice

n-3 Polyunsaturated fatty acids play a role in regulating the growth of the long bones. Fatty acid-binding proteins (FABPs) bind and transport hydrophobic long-chain fatty acids intracellularly, and epidermal-type FABP (E-FABP) has an affinity for n-3 fatty acids. This study aimed to clarify the localization of E-FABP in the growth plate of the mouse tibia. At the chondro-osseous junction (COJ) of the growth plate, E-FABP-immunoreactivity was exclusively localized in mononuclear, spindle-shaped cells with several long processes. These E-FABP-immunoreactive cells were identified as being septoclasts, i.e., cells that resorb uncalcified transverse septa. The processes of these immunoreactive septoclasts terminated between the longitudinal and transverse septa. E-FABP-immunoreactivity was found in the entire cytoplasm and on the mitochondrial outer membrane. In ontogeny, immunoreactive septoclasts were observed immediately after emergence of the primary ossifying center and were distributed not only at the COJ but also in the metaphysis near the COJ. The number of septoclasts increased at the postnatal age of 1 week (P1w)-P2w, and thereafter gradually decreased; and the cells became concentrated at the COJ after P3w-P4w. The immunoreactivity for peroxisome proliferator-activated receptor (PPAR)β/δ was detected in these E-FABP-immunoreactive septoclasts. The present results suggest that fatty acids, preferably n-3 ones, are intracellularly transported by E-FABP to various targets, including mitochondria and nucleus, in which PPARβ/δ may play functional roles in the transcriptional regulation of genes involved in the endochondral ossification.

The positive effect of soybean protein hydrolysates-calcium complexes on bone mass of rapidly growing rats

It was previously found that soybean protein hydrolysates (SPHs) can bind with calcium to form soluble complexes and promote calcium uptake by Caco-2 cells. However, the role of SPHs-calcium complexes on bone mass still needs to be explored. Fast growing male and female rats (n = 72) were assigned to eight groups: Control, lactic acid calcium (LCa), SPHs-calcium complexes (SPHCa) and casein phosphopeptides calcium (CPPCa). After four weeks treatment, oral administration of SPHCa significantly increased femur BMD of rats compared with Control and LCa groups (P < 0.05), while there are no obvious difference on the BMD of femur and lumbar vertebrae between SPHCa and CPPCa groups. Also, SPHCa showed a tendency to improve the mechanical properties of vertebra lumber for female rats. These findings suggest that the SPHs-calcium complexes might have positive effects on bone accretion of fast growing animals. This study brings new insight for better understanding the role of soybean protein itself on bone mass.

Skim milk powder enhances trabecular bone architecture compared with casein or whey in diet-induced obese rats

OBJECTIVE

We previously showed that skim milk powder (SMP) prevents weight gain more so than casein or whey alone. Dairy foods and changes in body mass can affect bone architecture; therefore, our objective was to examine the effect of dairy proteins on bone structure in the tibia of dietary-induced obese rats.

METHODS

Twelve-week-old diet-induced obese Sprague-Dawley rats were randomized to one of six diets that varied in protein source (casein, whey, or SMP), Ca level (0.67% or 2.4%), and energy density (high-fat/high-sucrose [HFHS], or normal energy density [NE]). After 8 wk, body composition was assessed via dual energy x-ray absorptiometry and trabecular and cortical bone parameters of the tibia were assessed using micro-computed tomography and mixed model analysis.

RESULTS

Rats fed SMP with 2.4% calcium had significantly lower body mass and fat mass than all other groups. The ratio of bone volume to total volume (BV/TV) was significantly higher when the HFHS diet was supplemented with SMP and 2.4% calcium compared with whey (+66.7%) or casein (+32.6%). The HFHS diet group had 49.3% greater BV/TV compared with the NE groups. Increasing the amount of calcium resulted in a significant increase in BV/TV (188.9%) in the HFHS diet groups but not in the NE groups.

CONCLUSION

The intake of skim milk powder supplemented with calcium enhances trabecular bone architecture in obese rats consuming HFHS diet to a greater extent than with either casein or whey protein alone. Bioactive ingredients in complete dairy may contribute to these effects.

Invited review: physiological properties of bioactive peptides obtained from whey proteins

Processing of whey proteins yields several bioactive peptides that can trigger physiological effects in the human body: on the nervous system via their opiate and ileum-contracting activities; on the cardiovascular system via their antithrombotic and antihypertensive activities; on the immune system via their antimicrobial and antiviral activities; and on the nutrition system via their digestibility and hypocholesterolemic effects. The specific physiological effects, as well the mechanisms by which they are achieved and the stabilities of the peptides obtained from various whey fractions during their gastrointestinal route, are specifically discussed in this review.

OMICS-rooted studies of milk proteins, oligosaccharides and lipids

Milk has co-evolved with mammals and mankind to nourish their offspring and is a biological fluid of unique complexity and richness. It contains all necessary nutrients for the growth and development of the newborn. Structure and function of biomolecules in milk such as the macronutrients (glyco-) proteins, lipids, and oligosaccharides are central topics in nutritional research. Omics disciplines such as proteomics, glycomics, glycoproteomics, and lipidomics enable comprehensive analysis of these biomolecule components in food science and industry. Mass spectrometry has largely expanded our knowledge on these milk bioactives as it enables identification, quantification and characterization of milk proteins, carbohydrates, and lipids. In this article, we describe the biological importance of milk macronutrients and review the application of proteomics, glycomics, glycoproteomics, and lipidomics to the analysis of milk. Proteomics is a central platform among the Omics tools that have more recently been adapted and applied to nutrition and health research in order to deliver biomarkers for health and comfort as well as to discover beneficial food bioactives.

A bovine whey protein extract can enhance innate immunity by priming normal human blood neutrophils

Bovine milk-derived products, in particular whey proteins, exhibit beneficial properties for human health, including the acquired immune response. However, their effects on innate immunity have received little attention. Neutrophils are key cells of innate defenses through their primary functions of chemotaxis, phagocytosis, oxidative burst, and degranulation. A whey protein extract (WPE) purified from bovine lactoserum was evaluated for its direct and indirect effects on these primary functions of normal human blood neutrophils in vitro. Although WPE had no direct effects on primary functions, a 24-h pretreatment of neutrophils with WPE was associated with a significant and dose-dependent increase of their chemotaxis, superoxide production, and degranulation in response to N-formyl-methionine-leucine-phenylalanine, as well as of their phagocytosis of bioparticles. The pretreatment increased the surface expression of CD11b, CD16B, and CD32A receptors. The major WPE protein components beta-lactoglobulin (beta-LG) and alpha-lactalbumin (alpha-LA) were the main active fractions having an additive effect on human neutrophils that became more responsive to a subsequent stimulation. This effect on NADPH oxidase activity was associated with translocation of p47(phox) to plasma membrane. Glycomacropeptide, a peptide present in measurable amounts in WPE products, was able to enhance the individual effect of beta-LG or alpha-LA on neutrophils. The present data suggest that WPE, through beta-LG and alpha-LA, has the capacity to enhance or "prime" human neutrophil responses to a subsequent stimulation, an effect that could be associated with increased innate defenses in vivo.

Nutrition: its role in bone health

At a given age, bone mass is determined by the amount of bone accumulated at the end of skeletal growth (the so-called peak bone mass), and by the amount of bone lost subsequently. Nutritional intake is an environmental factor that influences both bone capital accumulation, which is fully achieved by the end of the second decade of life, and bone loss, which occurs during the second half of existence. Nutrients may act directly by modifying bone turnover, or indirectly via changes in calciotropic hormone secretion. The study of the association between nutrition and a bone phenotypic expression may provide inconsistent results, in part because of the low accuracy and reproducibility of the various tools used to assess dietary intakes. Sufficient dietary calcium and protein are necessary for bone health during growth as well as in the elderly.

Emerging health properties of whey proteins and their clinical implications

The nursery rhyme "Little Miss Muffet sat on a tuffet (small stool) eating her curds and whey. ..." is recognition of the fact that over the centuries "curds and whey", the two major components of cow's milk, have been widely accepted as part of a healthy diet. Milk provides complete nourishment for the neonate for six months from birth, containing factors that help develop various organ systems including the brain, immune system, and the intestine. Importantly it provides immune protection at a time when the neonates own immune system, though fully developed, is albeit immature. Many adult consumers include cow's milk as part of a healthy diet as it provides protein and essential nutrients, vitamins, and minerals, in particular calcium for strong bones. There is a growing appreciation that milk, and in particular whey, contains components that not only provide nutrition, but can also prevent and attenuate disease, or augment conventional therapies, when delivered in amounts that exceed normal dietary intakes. This paper reviews the emerging health properties of whey proteins and their clinical implications.

The use of whey or skimmed milk powder in fortified blended foods for vulnerable groups

Fortified blended foods (FBF), especially corn soy blend, are used as food aid for millions of people worldwide, especially malnourished individuals and vulnerable groups. There are only a few studies evaluating the effect of FBF on health outcomes, and the potential negative effect of antinutrients has not been examined. Different lines of evidence suggest that dairy proteins have beneficial effects on vulnerable groups. Here we review the evidence on the effects of adding whey or skimmed milk powder to FBF used for malnourished infants and young children or people living with HIV or AIDS. Adding whey or skimmed milk powder to FBF improves the protein quality, allowing a reduction in total amount of protein, which could have potential metabolic advantages. It also allows for a reduced content of soy and cereal and thereby a reduction of potential antinutrients. It is possible that adding milk could improve weight gain, linear growth, and recovery from malnutrition, but this needs to be confirmed. Bioactive factors in whey might have beneficial effects on the immune system and muscle synthesis, but evidence from vulnerable groups is lacking. Milk proteins will improve flavor, which is important for acceptability in vulnerable groups. The most important disadvantage is a considerable increase in price. Adding 10-15% milk powder would double the price, which means that such a product should be used only in well-defined vulnerable groups with special needs. The potential beneficial effects of adding milk protein and lack of evidence in vulnerable groups call for randomized intervention studies.

Effects of Bioactive Peptide, Valyl-Prolyl-Proline (VPP), and Lactobacillus helveticus Fermented Milk Containing VPP on Bone Loss in Ovariectomized Rats

BACKGROUND

Valyl-prolyl-proline (VPP), a bioactive peptide formed during the fermentation with Lactobacillus helveticus LBK-16H (L. helveticus), has been shown to increase bone formation in vitro. The aim of the study was to determine whether VPP and L. helveticus fermented milk prevent bone loss in ovariectomized (OVX) rats.

METHODS

During the 12-week intervention study, the OVX rats received VPP in water or L. helveticus fermented milk, containing VPP. Sham-operated rats receiving water acted as controls. The trabecular and cortical bone mineral density were determined by peripheral quantitative computed tomography before the operation and at 4 and 12 weeks. The mechanical testing and ash weight analysis as well as the static and dynamic histomorphometrical parameters were assessed at the end of the intervention.

RESULTS

VPP given in water showed no clear effect on bone loss. L. helveticus fermented milk prevented bone loss by decreasing bone turnover and increasing the bone mineral density. Ovariectomy caused a 57% loss in the trabecular bone, which was attenuated by 16% in the L. helveticus group.

CONCLUSIONS

VPP peptide did not prevent ovariectomy-induced bone loss, which could be due to the poor bioavailability of VPP from water solution. L. helveticus fermented milk prevented bone loss, whether this is due to the VPP peptide cannot be concluded.