Orally administered lactoferrin preserves bone mass and microarchitecture in ovariectomized rats

Nutraceutical and Health-Promoting Potential of Lactoferrin, an Iron-Binding Protein in Human and Animal: Current Knowledge

Lactoferrin is a natural cationic iron-binding glycoprotein of the transferrin family found in bovine milk and other exocrine secretions, including lacrimal fluid, saliva, and bile. Lactoferrin has been investigated for its numerous powerful influences, including anticancer, anti-inflammatory, anti-oxidant, anti-osteoporotic, antifungal, antibacterial, antiviral, immunomodulatory, hepatoprotective, and other beneficial health effects. Lactoferrin demonstrated several nutraceutical and pharmaceutical potentials and have a significant impact on improving the health of humans and animals. Lactoferrin plays a critical role in keeping the normal physiological homeostasis associated with the development of pathological disorders. The current review highlights the medicinal value, nutraceutical role, therapeutic application, and outstanding favorable health sides of lactoferrin, which would benefit from more exploration of this glycoprotein for the design of effective medicines, drugs, and pharmaceuticals for safeguarding different health issues in animals and humans.

Lactoferrin-Anchored Tannylated Mesoporous Silica Nanomaterials-Induced Bone Fusion in a Rat Model of Lumbar Spinal Fusion

Lactoferrin (LF) is a potent antiviral, anti-inflammatory, and antibacterial agent found in cow and human colostrum which acts as an osteogenic growth factor. This study aimed to investigate whether LF-anchored tannylated mesoporous silica nanomaterials (TA-MSN-LF) function as a bone fusion material in a rat model. In this study, we created TA-MSN-LF and measured the effects of low (1 μg) and high (100 μg) TA-MSN-LF concentrations in a spinal fusion animal model. Rats were assigned to four groups in this study: defect, MSN, TA-MSN-LF-low (1 μg/mL), and TA-MSN-LF-high (100 μg/mL). Eight weeks after surgery, a greater amount of radiological fusion was identified in the TA-MSN-LF groups than in the other groups. Hematoxylin and eosin staining showed that new bone fusion was induced in the TA-MSN-LF groups. Additionally, osteocalcin, a marker of bone formation, was detected by immunohistochemistry, and its intensity was induced in the TA-MSN-LF groups. The formation of new vessels was induced in the TA-MSN-LF-high group. We also confirmed an increase in the serum osteocalcin level and the mRNA expression of osteocalcin and osteopontin in the TA-MSN-LF groups. TA-MSN-LF showed effective bone fusion and angiogenesis in rats. We suggest that TA-MSN-LF is a potent material for spinal bone fusion.

The role of lactoferrin in bone remodeling: evaluation of its potential in targeted delivery and treatment of metabolic bone diseases and orthopedic conditions

Lactoferrin (Lf) is a multifunctional protein that is synthesized endogenously and has various biological roles including immunological regulation, antibacterial, antiviral, and anticancer properties. Recently, research has uncovered Lf's critical functions in bone remodeling, where it regulates the function of osteoblasts, chondrocytes, osteoclasts, and mesenchymal stem cells. The signaling pathways involved in Lf's signaling in osteoblasts include (low density lipoprotein receptor-related protein - 1 (LRP-1), transforming growth factor β (TGF-β), and insulin-like growth factor - 1 (IGF-1), which activate downstream pathways such as ERK, PI3K/Akt, and NF-κB. These pathways collectively stimulate osteoblast proliferation, differentiation, and mineralization while inhibiting osteoclast differentiation and activity. Additionally, Lf's inhibitory effect on nuclear factor kappa B (NF-κB) suppresses the formation and activity of osteoclasts directly. Lf also promotes chondroprogenitor proliferation and differentiation to chondrocytes by activating the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) and phosphoinositide 3-kinase/protein kinase B(PI3K/Akt)signaling pathways while inhibiting the expression of matrix-degrading enzymes through the suppression of the NF-κB pathway. Lf's ability to stimulate osteoblast and chondrocyte activity and inhibit osteoclast function accelerates fracture repair, as demonstrated by its effectiveness in animal models of critical-sized long bone defects. Moreover, studies have indicated that Lf can rescue dysregulated bone remodeling in osteoporotic conditions by stimulating bone formation and suppressing bone resorption. These beneficial effects of Lf on bone health have led to its exploration in nutraceutical and pharmaceutical applications. However, due to the large size of Lf, small bioactive peptides are preferred for pharmaceutical applications. These peptides have been shown to promote bone fracture repair and reverse osteoporosis in animal studies, indicating their potential as therapeutic agents for bone-related diseases. Nonetheless, the active concentration of Lf in serum may not be sufficient at the site requiring bone regeneration, necessitating the development of various delivery strategies to enhance Lf's bioavailability and target its active concentration to the site requiring bone regeneration. This review provides a critical discussion of the issues mentioned above, providing insight into the roles of Lf in bone remodeling and the potential use of Lf as a therapeutic target for bone disorders.

Lactoferrin Mediates Enhanced Osteogenesis of Adipose-Derived Stem Cells: Innovative Molecular and Cellular Therapy for Bone Repair

A prospective source of stem cells for bone tissue engineering is adipose-derived stem cells (ADSCs), and BMP-2 has been proven to be highly effective in promoting the osteogenic differentiation of stem cells. Rarely has research been conducted on the impact of lactoferrin (LF) on ADSCs' osteogenic differentiation. As such, in this study, we examined the effects of LF and BMP-2 to assess the ability of LF to stimulate ADSCs' osteogenic differentiation. The osteogenic medium was supplemented with the LF at the following concentrations to culture ADSCs: 0, 10, 20, 50, 100, and 500 μg/mL. The Cell Counting Kit-8 (CCK-8) assay was used to measure the proliferation of ADSCs. Calcium deposition, alkaline phosphatase (ALP) staining, real-time polymerase chain reaction (RT-PCR), and an ALP activity assay were used to establish osteogenic differentiation. RNA sequencing analysis was carried out to investigate the mechanism of LF boosting the osteogenic development of ADSCs. In the concentration range of 0-100 μg/mL, LF concentration-dependently increased the proliferative vitality and osteogenic differentiation of ADSCs. At a dose of 500 μg/mL, LF sped up and enhanced differentiation, but inhibited ADSCs from proliferating. LF (100 and 500 μg/mL) produced more substantial osteoinductive effects than BMP-2. The PI3 kinase/AKT (PI3K/AKT) and IGF-R1 signaling pathways were significantly activated in LF-treated ADSCs. The in vitro study results showed that LF could effectively promote osteogenic differentiation of ADSCs by activating the PI3K/AKT and IGF-R1 pathways. In our in vitro investigation, an LF concentration of 100 μg/mL was optimal for osteoinduction and proliferation. Our study suggests that LF is an attractive alternative to BMP-2 in bone tissue engineering. As a bioactive molecule capable of inducing adipose stem cells to form osteoblasts, LF is expected to be clinically used in combination with biomaterials as an innovative molecular and cellular therapy to promote bone repair.

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.

Association between Dairy Product intake and Risk of Osteoporotic Fractures in Postmenopausal Japanese Women: Secondary Analysis of 15-Year Follow-Up data from the Japanese Population-Based Osteoporosis (JPOS) Cohort Study

OBJECTIVES

Few prospective cohort studies have evaluated the relationship between dairy product intake frequency and risk of osteoporotic fractures in Asians. This study aimed to investigate the association between habitual dairy product intake and risk of osteoporotic fractures.

DESIGN

Secondary analysis of prospective cohort study.

SETTING

Five municipalities of Japan.

PARTICIPANTS

This study included 1,429 postmenopausal Japanese women (age ≥45 years at baseline).

MEASUREMENTS

Baseline milk-intake frequency was obtained using nurse-administered questionnaires. Intakes of yogurt and cheese, and estimated calcium intake, were assessed using a validated food frequency questionnaire. Osteoporotic fracture was defined as a clinical fracture diagnosed using radiography. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards models.

RESULTS

Over a median follow-up period of 15.1 years (interquartile range [IQR], 10.1-15.4 years; total, 18,118 person-years), 172 women sustained at least one osteoporotic fracture. The proportions of participants with milk intakes <1, 1, and ≥2 cups/d were 34.4%, 48.0%, and 17.6%, respectively. After adjustment for age, frequency of yogurt intake, frequency of cheese intake, body mass index, history of osteoporotic fractures, and frequency of natto intake, the HRs compared with that for milk intake <1 cup/d were 0.71 (95% CI: 0.51-0.98) and 0.57 (95% CI: 0.35-0.92) for 1 cup/d and ≥2 cups/d, respectively. After adjustment for bone mineral density, HR significance for milk intakes ≥2 cups/d remained significant. Yogurt and cheese intakes were not related to the risk of osteoporotic fractures.

CONCLUSION

High habitual milk intake, but not a habitual yogurt or cheese intake is associated with a decreased risk of osteoporotic fractures, independent of bone mineral density, in postmenopausal Japanese women.

Pharmacological and Non-Pharmacological Agents versus Bovine Colostrum Supplementation for the Management of Bone Health Using an Osteoporosis-Induced Rat Model

Osteoporosis is defined by loss of bone mass and deteriorated bone microarchitecture. The present study compared the effects of available pharmacological and non-pharmacological agents for osteoporosis [alendronate (ALE) and concomitant supplementation of vitamin D (VD) and calcium (Ca)] with the effects of bovine colostrum (BC) supplementation in ovariectomized (OVX) and orchidectomized (ORX) rats. Seven-month-old rats were randomly allocated to: (1) placebo-control, (2) ALE group (7.5 μg/kg of body weight/day/5 times per week), (3) VD/Ca group (VD: 35 μg/kg of body weight/day/5 times per week; Ca: 13 mg/kg of body weight/day/3 times per week), and (4) BC supplementation (OVX: 1.5 g/day/5 times per week; ORX: 2 g/day/5 times per week). Following four months of supplementation, bone microarchitecture, strength and bone markers were evaluated. ALE group demonstrated significantly higher Ct.OV, Ct.BMC, Tb.Th, Tb.OV and Tb.BMC and significantly lower Ct.Pr, Tb.Pr, Tb.Sp, Ct.BMD and Tb.BMD, compared to placebo (p < 0.05). BC presented significantly higher Ct.Pr, Ct.BMD, Tb.Pr, Tb.Sp, and Tb.BMD and significantly lower Ct.OV, Ct.BMC, Tb.Th, Tb.OV and Tb.BMC compared to ALE in OVX rats (p < 0.05). OVX rats receiving BC experienced a significant increase in serum ALP and OC levels post-supplementation (p < 0.05). BC supplementation may induce positive effects on bone metabolism by stimulating bone formation, but appear not to be as effective as ALE.

Lactoferrin Deficiency Impairs Proliferation of Satellite Cells via Downregulating the ERK1/2 Signaling Pathway

Lactoferrin (Ltf), a naturally active glycoprotein, possesses anti-inflammatory, anti-microbial, anti-tumor, and immunomodulatory activities. Many published studies have indicated that Ltf modulates the proliferation of stem cells. However, the role of Ltf in the proliferation of satellite cells, an important cell type in muscle regeneration, has not yet been reported. Here, by using Ltf systemic knockout mice, we illustrate the role of Ltf in skeletal muscle. Results shows that Ltf deficiency impaired proliferation of satellite cells (SCs) and the regenerative capability of skeletal muscle. Mechanistic studies showed that ERK1/2 phosphorylation was significantly downregulated after Ltf deletion in SCs. Simultaneously, the cell cycle-related proteins cyclin D and CDK4 were significantly downregulated. Intervention with exogenous recombinant lactoferrin (R-Ltf) at a concentration of 1000 μg/mL promoted proliferation of SCs. In addition, intraperitoneal injection of Ltf effectively ameliorated the skeletal muscle of mice injured by 1.2% BaCl₂ solution. Our results suggest a protective effect of Ltf in the repair of skeletal muscle damage. Ltf holds promise as a novel therapeutic agent for skeletal muscle injuries.

Evaluation of the anti-osteoporotic effect of a low-phenylalanine whey protein hydrolysate in an ovariectomized mice model

A phenylalanine (Phe)-restricted diet is indispensable to control the blood Phe for individuals with phenylketonuria (PKU), who are also confronted with progressive bone impairment. Thus, the development of a low-Phe protein substitute that could positively regulate bone metabolism is desired for their bone health. Our previous study reported the preparation of a low-Phe containing whey hydrolysate (LPH) from a selected whey protein hydrolysate (TAH). However, the effect of LPH on the bone status is unknown. In this study, we used an ovariectomized (OVX) mice model to evaluate the anti-osteoporotic potential of oral administration of whey protein concentrate (WPC, protein control), TAH, and LPH on bone physiology and bone metabolism. The results showed that after 12 weeks of treatment, the decreased bone mineral density, the deteriorated trabecular microarchitecture, and the reduced ultimate load due to ovariectomy were significantly attenuated by two whey protein hydrolysates (TAH and LPH); meanwhile, the body weight, uterine weight, bone composition, and the femoral elastic load of OVX mice had not been significantly affected by whey samples. In addition, LPH and TAH dual-regulated bone remodeling in OVX mice through triggering osteogenesis (promoted the expression of runt-related protein 2 (Runx2) and osteoformation markers) and inhibiting osteoresorption as well as inflammation. The modulated mitogen-activated protein kinase signaling and the inhibited nuclear factor κB signaling by LPH and TAH might relate to the dual-regulatory activities on bone. Overall, in the OVX mice model, LPH exerted higher osteoprotective potential than TAH of the same dose by activating the bone formation markers and inhibiting the inflammatory status. The current study demonstrated for the first time the potential use of a low-Phe whey hydrolysate, a protein substitute for PKU individuals, in the prevention of osteoporosis.

Lactoferrin with Zn-ion protects and recovers fibroblast from H2O2-induced oxidative damage

Lactoferrin (LF) has attracted great attention due to its various bioactivities, which depend on the degree of saturation with different cations. This study focused on the synergistic effect of LF and Zn²⁺ on human gingival fibroblasts (hGFs), considering antioxidant activities, cell proliferation, and collagen gene expression levels in these cells to improve the wound healing. The hGFs were cultured in an experimental medium, containing 1000 μg/mL of LF and various concentrations of ZnCl₂. The cells were subjected to oxidative damage by exposure to 600 μM H₂O₂ for 30 min before incubation in the experimental medium. The cell proliferation rate and the relative gene expression levels of genes associated with apoptosis, antioxidant enzymes, and collagen were compared. H₂O₂ decomposition by LF was also measured using a colorimetric assay. LF enhanced hGF proliferation and the expression of collagen. Furthermore, LF directly scavenged H₂O₂ and prevented lipid peroxidation by enhancing the expression of glutathione peroxidase 4 gene expression, resulting in the prevention of apoptosis and recovery of the cells from H₂O₂-induced oxidative damage. The addition of ZnCl₂ enhanced these results. The results indicated that LF with Zn-ion could play an important role in modulating the functions related to wound healing.

Lactoferrin promotes the autophagy activity during osteoblast formation via BCL2-Beclin1 signaling

BACKGROUND

Lactoferrin, as the main component of milk, can maintain osteoblast formation, which is conducive to the prevention and treatment of osteoporosis. Lactoferrin also serves as an autophagy regulator, especially in osteoblasts. This study aimed to explore the significance of autophagy in osteoblast formation regulated by lactoferrin and the internal mechanism.

METHODS AND RESULTS

In this study, we firstly explored the roles of lactoferrin in the autophagy activity of primary osteoblasts (LC3 transformation rate, autophagosome formation). Subsequently, we further investigated the effects of lactoferrin on the BCL2 expression and BCL2-Beclin1 complex. Ultimately, the significance of BCL2 overexpression and Beclin1 silencing on lactoferrin-regulated osteoblast autophagy and osteogenic parameters (ALP activity and mRNA expression of PCNA, Col1, BGLAP and OPN) was observed by gene processing, respectively. Our results showed that lactoferrin enhanced the autophagy activity of osteoblasts. Importantly, lactoferrin inhibited BCL2 expression and the co-immunoprecipitation of BCL2 and Beclin1 in osteoblasts. Moreover, lactoferrin-promoted autophagy and osteogenic parameters was reversed by BCL2 overexpression or Beclin1 silencing in osteoblasts.

CONCLUSIONS

In conclusion, lactoferrin can inhibit BCL2 expression in osteoblasts, further enhancing Beclin1-dependent autophagy activation.

Bovine Colostrum Supplementation Improves Bone Metabolism in an Osteoporosis-Induced Animal Model

Osteoporosis is characterized by bone loss. The present study aims to investigate the effects of bovine colostrum (BC) on bone metabolism using ovariectomized (OVX) and orchidectomized (ORX) rat models. Twenty-seven-week-old Wistar Han rats were randomly assigned as: (1) placebo control, (2) BC supplementation dose 1 (BC1: 0.5 g/day/OVX, 1 g/day/ORX), (3) BC supplementation dose 2 (BC2: 1 g/day/OVX, 1.5 g/day/ORX) and (4) BC supplementation dose 3 (BC3: 1.5 g/day/OVX, 2 g/day/ORX). Bone microarchitecture, strength, gene expression of VEGFA, FGF2, RANKL, RANK and OPG, and bone resorption/formation markers were assessed after four months of BC supplementation. Compared to the placebo, OVX rats in the BC1 group exhibited significantly higher cortical bone mineral content and trabecular bone mineral content (p < 0.01), while OVX rats in the BC3 group showed significantly higher trabecular bone mineral content (p < 0.05). ORX rats receiving BC dose 2 demonstrated significantly higher levels of trabecular bone mineral content (p < 0.05). Serum osteocalcin in the ORX was pointedly higher in all BC supplementation groups than the placebo (BC1: p < 0.05; BC2, BC3: p < 0.001). Higher doses of BC induced significantly higher relative mRNA expression of OPG, VEGFA, FGF2 and RANKL (p < 0.05). BC supplementation improves bone metabolism of OVX and ORX rats, which might be associated with the activation of the VEGFA, FGF2 and RANKL/RANK/OPG pathways.

Lactoferrin Is a Potential Activator of the Vitamin D Receptor in Its Regulation of Osteogenic Activities in C57BL/6J Mice and MC3T3-E1 Cells

BACKGROUND

Lactoferrin (LF) has been shown to promote bone anabolism, and the vitamin D receptor (VDR) mediates the effects of vitamin D on bone. We hypothesized that LF improves bone health by increasing VDR expression.

OBJECTIVES

We sought to determine the role of VDR activation in LF-induced osteogenic activity in vivo and in vitro and the underlying molecular mechanisms.

METHODS

Sixty male C57BL/6J mice (aged 4 wk) were randomly assigned into 6 groups and fed vitamin D-deficient (VDD; 0 IU/kg) or vitamin D-normal diet (VDN; 1000 IU cholecalciferol/kg) and administered placebo or LF (100 or 1000 mg/kg body weight) by gavage for 24 wk. Trabecular bone structure was analyzed using micro-CT, and VDR expression was assessed by immunohistochemistry. In vitro, MC3T3-E1 cells were treated with 100 μg LF/mL to evaluate its effect on VDR expression. Finally, the direct recruitment of LF to the Vdr promoter was confirmed by chromatin immunoprecipitation assay. In addition, cells were transfected with pGL3-basic Vdr vector for monitoring Vdr promoter activation using luciferase assays.

RESULTS

LF supplementation at 100 and 1000 mg/kg revealed an ∼6.5% (P < 0.05) increase in bone mineral density in mice on VDD diet and exhibited an enhanced expression of VDR in bone compared with control. This increased expression of VDR was also observed in the bone of mice on the VDN diet, but the effect was more pronounced in VDD diet. In vitro, compared with the control group, Vdr mRNA expression was 18 times greater (P < 0.05) and peaked at 2 h posttreatment of LF. By cotransfection of the pGL3-basic Vdr vector, LF induced luciferase activity by 30% (P < 0.05) in MC3T3-E1 cells.

CONCLUSIONS

In vivo and in vitro, LF, a potential activator of VDR, promotes osteogenesis. This suggests that dairy products, which are rich in LF, may serve as a functional food to improve bone health.

Variation in milk fat globule size and composition: A source of bioactives for human health

Milk fat globules (MFGs) are secreted from the mammalian gland and are composed of a triacylglycerol core surrounded by a triple membrane structure, the milk fat globule membrane (MFGM). The MFGM contains complex lipids and proteins reported to have nutritional, immunological, neurological and digestive functions. Human and ruminant milk are shown to share a similar MFG structure but with different size, profile and abundance of protein and polar lipids. This review summarizes the reported data on human, bovine, caprine and ovine MFG composition and concentration of bioactive components in different MFG-size fractions. A comprehensive understanding of compositional variations between milk from different species and MFG size fractions may help promote various milk sources as targeted supplements to improve human development and health. MFG size and MFGM composition are species-specific and affected by lactation, diet and breed (or maternal origin). Purification and enrichment methods for some bioactive proteins and lipids present in the MFGM have yet to be established or are not scaled sufficiently to be used to supplement human diets. To overcome this problem, MFG size selection through fractionation or herd selection may provide a convenient way to pre-enrich the MFG fraction with specific protein and lipid components to fulfill human dietary and health requirements.

Bovine lactoferrin inhibits alveolar bone destruction in an orthodontic rat model with periodontitis

OBJECTIVE

We aimed to evaluate the effect of bovine lactoferrin (bLF) on alveolar bone destruction and remodelling under orthodontic force (OF) in periodontitis-affected rats.

MATERIAL AND METHODS

After establishing the periodontitis-affected rat model with lipopolysaccharides (LPS), the left maxillary first molars were moved orthodontically under a force of 0.2N. Based on saline or bLF gavage, 54 Sprague-Dawley (SD) rats were randomized into 5 groups: A (blank), P1 (LPS+OF+bLF), P2 (LPS+OF+saline), C1 (OF+bLF), and C2 (OF+saline). Animals were evaluated using micro-computed tomography (micro-CT) followed by haematoxylin and eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining, and the LF level was determined using ELISA in the gingival crevicular fluid (GCF) of the experimental teeth. Immunohistochemistry helped to detect expression changes in RANKL, OPG and COX-2.

RESULTS

Micro-CT results indicated that compared with group P2, trabecular number (Tb.N) and trabecular thickness (Tb.Th) in group P1 were higher and bone surface/bone volume (BS/BV) was lower on day 14, while trabecular separation (Tb.Sp) decreased significantly on Day 5 and Day 14 after bLF gavage (P<0.05). This was supported by changes in H&E and TRAP staining. bLF down-regulated RANKL level at both timepoints and up-regulated OPG level on Day 14 in periodontitis rats (P<0.05). The significant changes mentioned above were not observed between group C1 and C2 (P>0.05). No significant change in COX-2 levels were observed in any group (P>0.05). The lactoferrin level in GCF increased significantly after bLF gavage (P<0.05).

CONCLUSION

Bovine lactoferrin inhibited LPS-induced bone destruction, but the bone healing effect was independent of orthodontic aseptic inflammatory bone remodelling.

Lactoferrin as a regenerative agent: The old-new panacea?

Lactoferrin (Lf) possesses various biological properties and therapeutic potentials being a perspective anti-inflammatory, antibacterial, antiviral, antioxidant, antitumor, and immunomodulatory agent. A significant body of literature has also demonstrated that Lf modulates regenerative processes in different anatomical structures, such as bone, cartilage, skin, mucosa, cornea, tendon, vasculature, and adipose tissue. Hence, this review collected and analyzed the data on the regenerative effects of Lf, as well as paid specific attention to their molecular basis. Furthermore, tissue and condition-specific activities of different Lf types as well as problems of their delivery to the targeted organs were discussed. The authors strongly hope that this review will stimulate researchers to focus on the highlighted topics thus accelerating the progress of Lf's wider clinical application.

Osteogenic effects of the peptide fraction derived from pepsin-hydrolyzed bovine lactoferrin

Osteoporosis is a common disease that frequently occurs in the older population, particularly in postmenopausal women. It severely compromises the health of the older population, and the drugs commonly used to treat osteoporosis have a variety of adverse effects. Lactoferrin (LF) is a protein present in milk that has recently been found to exhibit osteogenic activity. Lactoferrin is nontoxic and harmless, suggesting that it may have excellent biocompatibility and tolerability after human consumption. Oral consumption of LF in an ovariectomized rat model has been found to ameliorate osteoporosis. However, the mechanism underlying this effect remains to be clarified. In this study, bovine LF (bLF) was first hydrolyzed by pepsin for 1 h, and the hydrolyzed mixture was freeze-dried and collected. The hydrolyzed mixture was then separated into 5 components (E1-E5), of which E3 had the greatest effect in promoting proliferation of osteoblasts (MC3T3-E1). Component E3 was further isolated into 21 components with preparative reversed phase HPLC, and the E3-15 component had maximal bioactivity. With HPLC-mass spectrometry and peptide sequencing, E3-15 was identified to contain amino acids 97 to 208 from the bLF N terminus. Then, E3-15 was divided into 6 different peptide segments (P1-P6), and the corresponding segments were generated by solid-phase synthesis. Only the P1 peptide (amino acids 97-122 from the N terminus of bLF) significantly promoted osteoblast proliferation. The bioactivity of P1 toward osteoblast cells and alkaline phosphatase activity were tested as a function of P1 concentration, and a nonlinear effect was observed.

Lactoferrin-Anchored Tannylated Mesoporous Silica Nanomaterials for Enhanced Osteo-Differentiation Ability

In the present study, we created lactoferrin-anchored mesoporous silica nanomaterials with absorbed tannic acid (LF/TA-MSNs) and evaluated the effect of these LF/TA-MSNs on the in vitro osteo-differentiation ability of adipose-derived stem cells (ADSCs) by testing alkaline phosphatase (ALP) level, calcium accumulation, and expression of osteo-differentiation-specific genes, including osteocalcin (OCN) and osteopontin (OPN). Both bare MSNs and LF/TA-MSNs exhibited round nano-particle structures. The LF/TA-MSNs demonstrated prolonged LF release for up to 28 days. Treatment of ADSCs with LF (50 μg)/TA-MSNs resulted in markedly higher ALP level and calcium accumulation compared to treatment with LF (10 μg)/TA-MSNs or bare MSNs. Furthermore, LF (50 μg)/TA-MSNs remarkably increased mRNA levels of osteo-differentiation-specific genes, including OCN and OPN, compared to MSNs or LF (10 μg)/TA-MSNs. Together, these data suggest that the ability of LF/TA-MSNs to enhance osteo-differentiation of ADSCs make them a possible nanovehicle for bone healing and bone regeneration in patients with bone defect or disease.

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.

Oral administration of bovine lactoferrin accelerates the healing of fracture in ovariectomized rats

INTRODUCTION

Lactoferrin has recently been reported for its potent bone growth effects. However, the effects of lactoferrin on the healing process of fragility fracture have not yet been studied, so the purpose of this study is to investigate whether oral administration of lactoferrin can promote the fracture healing in an OVX animal model.

MATERIALS AND METHODS

Three months after bilateral ovariectomy, all rats underwent unilateral tibial osteotomy and were then randomly divided into control group and bovine lactoferrin (bLF) group. At 4 and 8 weeks post-fracture, animals were sacrificed, and the fractured tibiae and serum samples were collected for evaluation.

RESULTS

Our results showed that bLF treatment not only accelerated the bone growth at an early stage of OPF healing but also shortened the remolding process of OPF healing. When compared to control group, bLF treatment induced a significant rise in callus BMD (by 35.0% at 4 weeks and by 39.7% at 8 weeks; both p < 0.05) consistent with enhanced biomechanical strength of the callus, with ultimate force increased by 3.39-fold at 4 weeks (p < 0.05) and 1.95-fold at 8 weeks (p < 0.05). Besides, bLF administration resulted in a substantial increase in serum levels of BALP and a significant decrease in serum levels of TRAP 5b and TNF-α. Moreover, both the RANKL/OPG mRNA ratio and the expression of TNF-α in the callus of bLF-treated group were markedly lower than those in the control group.

CONCLUSIONS

At a dose of 85mg/kg/day orally administrated bLF potently promoted the bone healing following tibial fracture in OVX rats.

Lactoferrin from Bovine Milk: A Protective Companion for Life

Lactoferrin (Lf), an iron-binding multifunctional glycoprotein belonging to the transferrin family, is present in most biological secretions and reaches particularly high concentrations in colostrum and breast milk. A key function of lactoferrin is non-immune defence and it is considered to be a mediator linking innate and adaptive immune responses. Lf from bovine milk (bLf), the main Lf used in human medicine because of its easy availability, has been designated by the United States Food and Drug Administration as a food additive that is generally recognized as safe (GRAS). Among the numerous protective activities exercised by this nutraceutical protein, the most important ones demonstrated after its oral administration are: Antianemic, anti-inflammatory, antimicrobial, immunomodulatory, antioxidant and anticancer activities. All these activities underline the significance in host defence of bLf, which represents an ideal nutraceutical product both for its economic production and for its tolerance after ingestion. The purpose of this review is to summarize the most important beneficial activities demonstrated following the oral administration of bLf, trying to identify potential perspectives on its prophylactic and therapeutic applications in the future.

Lactoferrin in Bone Tissue Regeneration

Among the multiple properties exhibited by lactoferrin (Lf), its involvement in bone regeneration processes is of great interest at the present time. A series of in vitro and in vivo studies have revealed the ability of Lf to promote survival, proliferation and differentiation of osteoblast cells and to inhibit bone resorption mediated by osteoclasts. Although the mechanism underlying the action of Lf in bone cells is still not fully elucidated, it has been shown that its mode of action leading to the survival of osteoblasts is complemented by its mitogenic effect. Activation of several signalling pathways and gene expression, in an LRPdependent or independent manner, has been identified. Unlike the effects on osteoblasts, the action on osteoclasts is different, with Lf leading to a total arrest of osteoclastogenesis. Due to the positive effect of Lf on osteoblasts, the potential use of Lf alone or in combination with different biologically active compounds in bone tissue regeneration and the treatment of bone diseases is of great interest. Since the bioavailability of Lf in vivo is poor, a nanotechnology- based strategy to improve the biological properties of Lf was developed. The investigated formulations include incorporation of Lf into collagen membranes, gelatin hydrogel, liposomes, loading onto nanofibers, porous microspheres, or coating onto silica/titan based implants. Lf has also been coupled with other biologically active compounds such as biomimetic hydroxyapatite, in order to improve the efficacy of biomaterials used in the regulation of bone homeostasis. This review aims to provide an up-to-date review of research on the involvement of Lf in bone growth and healing and on its use as a potential therapeutic factor in bone tissue regeneration.

Activation of TGF-β Canonical and Noncanonical Signaling in Bovine Lactoferrin-Induced Osteogenic Activity of C3H10T1/2 Mesenchymal Stem Cells

Lactoferrin (LF) is known to modulate the bone anabolic effect. Previously, we and others reported that the effects of LF on the bone may be conferred by the stimulation of transforming growth factor β (TGF-β) signaling in the preosteoblast. However, the underlying molecular mechanisms of LF-induced osteogenic differentiation of mesenchymal stem cells (MSCs) has not been identified. In this study, we tested the hypothesis that the effects of LF on osteogenesis of MSCs required mediation by TGF-β Receptors and activating TGF-β signaling pathway. Using siRNA silencing technology, the knockdown of TGF-β Receptor II (TβRII) could significantly attenuate LF’s effect on the proliferation rate and alkaline phosphatase (ALP) activity of MSCs. It indicated that LF induced osteogenic activity that is dependent on TβRII in C3H10T1/2. Subsequently, it was shown that LF activated Smad2. Downregulating TGF-β Receptor I (TβRI) with SB431542 attenuated the expression of p-Smad2 and p-P38, also the LF-induced the osteogenic activity. Besides, the stimulation by LF on the expression of Osteocalcin (OCN), Osteopontin (OPN), Collagen-2a1 (Col2a1), and Fibroblast Growth Factor 2 (FGF2) were abolished by SB431542. These results confirmed that LF induced osteogenic activity though the TGF-β canonical and noncanonical signaling pathway. This study provided the first evidence of the signaling mechanisms of LF’s effect on osteogenesis in MSCs.

Taurine May Modulate Bone in Cholesterol Fed Estrogen Deficiency-Induced Rats

Taurine is thought to affect bone in rats favorably. However, studies on the actions of this estrogen deficiency and high cholesterol diet factors on the bone metabolism are limited. In this study, the protective effect of taurine on bone was determined. Thirty-two 42 days old female SD rats were placed in individual stainless cages. Given to rats was fed to chow (Samyang Corporation, South Korea) and deionized water for a 4 days adaptation period. After the period of adaptation, Half of the rats were induced estrogen deficiency model by ovariectomy (OVX), and the left rats with sham-operated were used control (SHAM). For six weeks, the OVX and SHAM rats had separately a 2% taurine supplemented diet with ad libitum in both the water and the food. DEXA for small animals (PIXImus, GE Lunar co, Wisconsin) was used to determine spinal and femoral bone. The concentrations of serum calcium and phosphorus were also measured. The monitoring of bone formation was done by determining the serum ALP and osteocalcin. Urinary DPD the values were determined as index of bone resorption. Statistical measure was done with SAS (version 9.3). A lower overall intake of the daily food was observed in non-ovariectomized rats than in the OVX rats. At sacrifice, a much greater body weight was observed in ovariectomized group compare to non-operated group. That difference was absent in both fed taurine SHAM and OVX rats. Serum calcium and phosphorus were not statistically different by taurine supplementation. Urinary excretion of calcium was not effected by taurine supplementation. Serum ALP and was significantly decreased by taurine in OVX rats (p < 0.05). For the spine BMD and BMC, there was no difference among SHAM and OVX rats by taurine. Spine BMC per body weight of taurine groups were higher than control groups (p < 0.1). No significant difference was observed after taurine supplementation in femur BMD and BMC. The analysis of the results suggest that taurine supplementation modulates the bone mineral contents in postmenopausal model rats fed with high cholesterol diet.

Ficus deltoidea Prevented Bone Loss in Preclinical Osteoporosis/Osteoarthritis Model by Suppressing Inflammation

Osteoporosis (OP) and osteoarthritis (OA) are debilitating musculoskeletal diseases of the elderly. Ficus deltoidea (FD) or mistletoe fig, a medicinal plant, was pre-clinically evaluated against OP- and OA-related bone alterations, in postmenopausal OA rat model. Thirty twelfth-week-old female rats were divided into groups (n = 6). Four groups were bilateral ovariectomized (OVX) and OA-induced by intra-articular monosodium iodoacetate (MIA) injection into the right knee joints. The Sham control and OVX-OA non-treated groups were given deionized water. The three other OVX-OA groups were orally administered daily with FD extract (200, 400 mg/kg) or diclofenac (5 mg/kg) for 4 weeks. The rats' bones and blood were evaluated for protein and mRNA expressions of osteoporosis and inflammatory indicators, and micro-CT computed tomography for bone microstructure. The non-treated OVX-OA rats developed severe OP bone loss and bone microstructural damage in the subchondral and metaphyseal regions, supported by reduced serum bone formation markers (osteocalcin, osteoprotegerin) and increased bone resorption markers (RANKL and CTX-I). The FD extract significantly (p < 0.05) mitigated these bone microstructural and biomarker changes by dose-dependently down-regulating pro-inflammatory NF-κβ, TNF-α, and IL-6 mRNA expressions. The FD extract demonstrated good anti-osteoporotic properties in this OP/OA preclinical model by stimulating bone formation and suppressing bone resorption via anti-inflammatory pathways. This is among the few reports relating the subchondral bone plate and trabecular thickening with the metaphyseal trabecular osteopenic bone loss under osteoporotic-osteoarthritis conditions, providing some insights on the debated inverse relationship between osteoporosis and osteoarthritis.

Lactoferrin Promotes Osteogenesis through TGF-β Receptor II Binding in Osteoblasts and Activation of Canonical TGF-β Signaling in MC3T3-E1 Cells and C57BL/6J Mice

Background

Lactoferrin (LF), as a major functional protein in dairy products, is known to modulate bone anabolic effects. However, the underlying molecular mechanisms remain unclear; the receptor of LF in osteoblast differentiation has not been identified.

Objective

The aims of the study were to 1) illuminate whether the receptor of LF in osteoblast differentiation is transforming growth factor-β (TGF-β) receptor (TβR) II and 2) determine whether the TGF-β signaling pathway is activated by LF in promoting osteogenesis in vitro and in vivo, in addition to P38 and extracellular signal-regulated kinase (ERK) pathways.

Methods

We utilized co-immunoprecipitation to detect any binding of LF to TβRII. Subsequently, the role of the TGF-β signaling pathway involved in LF-induced osteoblast proliferation and differentiation was determined by inhibition of TβRI activity by inhibition and knockout of TβRII expression by small guide RNA (sgRNAs) in MC3T3-E1 cells. In addition, 4-wk-old male C57BL/6J mice were orally administered 100 mg LF/kg body weight for 16 wk, after which any activation of the TGF-β signaling pathway in vivo was measured by Western blots.

Results

LF was shown to directly interact with the TβRII protein and to activate the TGF-β signaling pathway in MC3T3-E1 cells. Inhibition of TβRI activity and knockout TβRII expression both attenuated the stimulation of LF in osteoblast proliferation and differentiation by 30-50%. LF-induced activation of TGF-β canonical signaling resulted in upregulation of osteogenic factors. Moreover, the expression of phosphorylated-drosophila mothers against decapentaplegic protein 2 (SMAD2) was increased by 1-fold after LF treatment in the femoral tissue of mice.

Conclusions

This study provides evidence identifying TβRII as an LF receptor in LF-induced osteoblast differentiation. In addition, the TβRII-dependent TGF-β canonical signaling pathways were proven to play an important role in mediating LF-induced osteogenesis both in MC3T3-E1 cells and in C57BL/6J mice.

Egg White Ovotransferrin Shows Osteogenic Activity in Osteoblast Cells

Ovotransferrin, the major protein in egg white, is a member of transferrin family. The objective of this study was to study the effects of ovotransferrin on cell proliferation, differentiation, mineralization and osteoclastogenesis of bone osteoblast cells. Effect of ovotransferrin (concentrations ranging from 1 to 1000 μg/mL) on the proliferation, differentiation, and mineralization of mouse osteoblast cells MC3T3-E1 was determined by 5-bromo-2-deoxyuridine (BrdU) incorporation assay, Western blot, immunofluorescence, and Alizarin-S red staining, respectively. Our results showed that ovotransferrin stimulated cell proliferation (enhanced BrdU incorporation), differentiation (enhanced expression of alkaline phosphatase and type-I collagen), and mineralization (increased calcium deposits) in a dose-dependent manner. Furthermore, ovotransferrin could increase the expression of osteoprotegerin (OPG) while decreasing the expression of receptor activator of nuclear factor kappa-B ligand (RANKL), suggesting its role in inhibition of bone resorption. This study demonstrated for the first time that ovotransferrin might promote bone formation while preventing bone resorption, which might open up a new application of egg white protein ovotransferrin as a functional ingredient in bone health management.

Bone health-promoting bioactive peptides

Bioactive peptides, derivatives of proteins, show versatile biological effects and represent potential health-promoting agents as functional food ingredients and/or nutraceuticals. Bone health depends on the balance between bone formation and resorption. When the balance is disrupted, bone diseases such as osteoporosis and fragility fractures may result. Accumulating evidence suggests that peptides derived from endogenous proteins and food proteins enhance bone health. This article reviews the literature on peptides exhibiting bone health-promoting effects. Possible biochemical mechanisms and production of these peptides are briefly discussed. PRACTICAL APPLICATIONS: Bioactive peptides are derived from food proteins via enzymatic hydrolysis, are already commercially available. In vitro and in vivo bone health-promoting effects of bioactive peptides have been shown in several animal models of osteoporosis and fractures. Thus, peptides can be used as functional food ingredients and/or nutraceuticals. However, their exact role and safety in human subjects should be evaluated prior to commercialization.

Lactoferrin preserves bone homeostasis by regulating the RANKL/RANK/OPG pathway of osteoimmunology

Lactoferrin preserves bone homeostasis via the osteoimmunology pathway.

Lactoferrin promotes MC3T3-E1 osteoblast cells proliferation via MAPK signaling pathways

Lactoferrin has attracted great attention as a potential functional factor to prevent osteoporosis due to its various bioactivities. However, the molecular mechanism underlining the osteogenic activity of lactoferrin is unclear. In this study, effect of lactoferrin on MC3T3-E1 osteoblast cells proliferation was determined using MTT assay, while MAPK signaling pathways related to proliferation of MC3T3-E1 osteoblast cells were investigated based on mRNA and protein expressions. The distribution of cells at different cell cycle stages was evaluated by flow cytometry. Our findings indicated that lactoferrin enhanced MC3T3-E1 osteoblast cells proliferation in a dose-dependent manner; namely, it increased the proportion of cells in S and G2/M phases. Furthermore, we also found that lactoferrin could stimulate ERK, JNK and p38 MAPK. The mRNA expression of MAPK were significantly enhanced after treatment of lactoferrin. Lactoferrin significantly promoted the activation-associated phosphorylation of ERK and p38 MAPK and prevented the activation of JNK. Additionally, lactoferrin could enhance c-Fos and c-Jun expression by 3 times and 26 times, respectively. These results indicated that lactoferrin induced MC3T3-E1 osteoblast cells proliferation through c-Fos and c-Jun by stimulating ERK, JNK and p38, elucidating the molecular basis of the osteogenic activity of lactoferrin on MC3T3-E1 osteoblast cells.

Effects of Recombinant Human Lactoferrin on Osteoblast Growth and Bone Status in Piglets

Lactoferrin (LF), an ~80 kDa iron-binding glycoprotein, modulates many biological effects, including antimicrobial and immunomodulatory activities. Recently, it was shown that LF also regulates bone cell activity, suggesting its therapeutic effect on postmenopausal bone loss. However, a minimal amount is known regarding the effects of recombinant human LF (rhLF) supplementation on bone status in young healthy infants. We found osteoblast cell differentiation was significantly promoted in vitro. Furthermore, treatment of human osteoblast cells with rhLF rapidly induced phosphorylation of p44/p42 mitogen-activated protein kinase (p44/p42 MAPK, ERK1/2). In order to investigate the effects of rhLF on bone status in vivo, we used a piglet model, which is a useful model for human infants. Piglets were supplemented with rhLF milk for 30 days. Bone formation markers, Serum calcium concentration, bone mineral density (BMD), bone mineral content (BMC), tibia bone strength, and the overall metabolite profile analysis showed that rhLF was advantageous to the bone growth in piglets. These findings suggest that rhLF supplementation benefits neonate bone health by modulating bone formation.

Local application of lactoferrin promotes bone regeneration in a rat critical-sized calvarial defect model as demonstrated by micro-CT and histological analysis

Lactoferrin is a multifunctional glycoprotein with therapeutic potential for bone tissue engineering. The aim of this study was to assess the efficacy of local application of lactoferrin on bone regeneration. Five‐millimetre critical‐sized defects were created over the right parietal bone in 64 Sprague–Dawley rats. The rats were randomized into four groups: group 1 (n  =  20) had empty defects; group 2 (n  =  20) had defects grafted with collagen gels (3 mg/ml); group 3 (n  =  20) had defects grafted with collagen gels impregnated with bovine lactoferrin (10 μg/gel); and group 4 (n  =  4) had sham surgeries (skin and periosteal incisions only). The rats were sacrificed at 4 or 12 weeks post‐operatively, and the calvaria were excised and evaluated with micro‐CT (Skyscan 1172) followed by histology. The bone volume fraction (BV/TV) was higher in lactoferrin‐treated animals at both timepoints, with groups 1, 2, 3 and 4 measuring 10.5  ±  1.1%, 8.6  ±  1.4%, 16.5  ±  0.6% and 24.27  ±  2.6%, respectively, at 4 weeks (P  <  0.05); and 12.2  ±  1.3%, 13.6  ±  1.5%, 21.9  ±  1.2% and 29.3  ±  0.8%, respectively, at 12 weeks (P  <  0.05). Histological analysis revealed that the newly formed bone within the calvarial defects of all groups was a mixture of woven and lamellar bone, with more bone in the group treated with lactoferrin at both timepoints. Our study demonstrated that local application of lactoferrin significantly increased bone regeneration in a rat critical‐sized calvarial defect model. The profound effect of lactoferrin on bone regeneration has therapeutic potential to improve the poor clinical outcomes associated with bony non‐union. LF In Vivo JTERM Authors Contributions. Copyright © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons, Ltd.

Combination of micellar casein with calcium and vitamins D2 and K2 improves bone status of ovariectomized mice

Nutritional approaches may help to preserve bone quality. The purpose of our study was to demonstrate the efficiency of an innovative bone health product (BHP) including micellar casein rich in calcium, vitamin D2 and vitamin K2, to improve bone mineral density.

INTRODUCTION

The aim of postmenopausal osteoporosis treatment is to decrease bone resorption and/or increase bone formation. Because of the slow bone turnover, osteoporosis prevention and therapies are long-lasting, implying great costs and poor compliance. Even if the effects of nutrition on bone are not as marked as that of pharmaceutical agents, it can be of great help. The purpose of our study was to demonstrate the efficiency of an innovative bone health product (BHP) containing micellar casein rich in calcium, vitamin D2 and vitamin K2, for the improvement of bone mineral density (BMD).

METHODS

An ovariectomized mice model was used to study the effect of different concentrations of the ingredient on BMD and microarchitectural parameters. Blood concentrations of C-terminal telopeptide of type I collagen (CTX), N-terminal propeptide of type 1 procollagene (PINP), alkaline phosphatase (ALP), osteocalcin (OC) and RANKL were also measured to evaluate bone remodelling, To evaluate the efficiency of the product to modulate osteoblast and osteoclast growth and differentiation, primary murine bone cells were used.

RESULTS

In vivo studies showed that BMD and microarchitectural parameters were dose-dependently improved after ingestion of the supplement for 3 months. We also report increased osteoblast activity as shown by increased OC activity and decreased osteoclastogenesis as shown by reduced CTX activity. In vitro studies support that BHPs stimulate osteoblast differentiation and mineralization and inhibit osteoclast resorption activity.

CONCLUSION

Our results show that, when chronically ingested, BHPs improve BMD of ovariectomized mice. This work supports that providing an ingredient including micellar casein rich in calcium, vitamin D2 and vitamin K2 is more efficient than the control diet to maintain bone quality.

Lactoferrin from Milk: Nutraceutical and Pharmacological Properties

Lactoferrin is an iron-binding protein present in large quantities in colostrum and in breast milk, in external secretions and in polymorphonuclear leukocytes. Lactoferrin's main function is non-immune protection. Among several protective activities shown by lactoferrin, those displayed by orally administered lactoferrin are: (i) antimicrobial activity, which has been presumed due to iron deprivation, but more recently attributed also to a specific interaction with the bacterial cell wall and extended to viruses and parasites; (ii) immunomodulatory activity, with a direct effect on the development of the immune system in the newborn, together with a specific antinflammatory effects; (iii) a more recently discovered anticancer activity. It is worth noting that most of the protective activities of lactoferrin have been found, sometimes to a greater extent, also in peptides derived from limited proteolysis of lactoferrin that could be generated after lactoferrin ingestion. Lactoferrin could therefore be considered an ideal nutraceutic product because of its relatively cheap production from bovine milk and of its widely recognized tolerance after ingestion, along with its well demonstrated protective activities. The most important protective activities shown by orally administered bovine lactoferrin are reviewed in this article.

Bone Regeneration Is Promoted by Orally Administered Bovine Lactoferrin in a Rabbit Tibial Distraction Osteogenesis Model

BACKGROUND

Lactoferrin, an iron-binding glycoprotein which belongs to the transferrin family, has been shown to promote bone growth. However, reports regarding effects of lactoferrin on bone regeneration during distraction osteogenesis are limited. Our study was designed to investigate the effect of bovine lactoferrin treatment on bone formation of the distracted callus.

QUESTIONS/PURPOSES

We asked whether bovine lactoferrin enhances bone formation of the distraction callus as determined by (1) radiographic and histologic appearances; (2) dual-energy x-ray absorptiometry (DXA) analysis of bone mineral composition and bone mineral density; (3) micro-CT measures of trabecular architecture; and (4) biomechanical strength of the healing bone. Additionally, serology, reverse transcription (RT)-PCR, and immunohistochemistry were used to explore the possible mechanisms of bovine lactoferrin use on bone formation during distraction osteogenesis.

METHODS

Unilateral tibial osteodistraction was performed on 80 New Zealand White rabbits with a distraction rate of 1 mm per day for 10 days. Animals then were divided randomly into two groups: (1) vehicle and (2) bovine lactoferrin. At 4 and 8 weeks after completion of distraction, the animals were sacrificed. Lengthened tibias and serum samples were obtained and subjected to radiologic, DXA, micro-CT, histologic, and biomechanical examinations, and serum, RT-PCR and immunohistochemical analyses.

RESULTS

Radiologic, DXA, micro-CT, histologic, and biomechanical examinations indicated that bovine lactoferrin treatment not only accelerated bone formation at early stages of distraction osteogenesis but also promoted bone consolidation at late stages. The ultimate force of the distracted calluses was increased by 37% (118.8 ± 6.65 N in the lactoferrin group and 86.5 ± 5.47 N in the vehicle group; p < 0.001) and 84% (384.8 ± 18.4 N in the lactoferrin group and 209.0 ± 15.2 N in the vehicle group; p < 0.001) at 4 and 8 weeks, respectively. Moreover, serum analysis showed that bovine lactoferrin treatment significantly increased serum levels of bone alkaline phosphatase and decreased serum levels of tartrate resistant acid phosphatase 5b. In addition, RT-PCR and immunohistochemical analyses suggested that bovine lactoferrin treatment induced a lower receptor activator of nuclear factor-kappaB (RANK) ligand/osteoprotegerin (RANKL/OPG) ratio in the distracted callus.

CONCLUSIONS

The results of our study suggest that bovine lactoferrin treatment could promote bone regeneration during distraction osteogenesis in the rabbit. The results indicate that the OPG/RANKL/RANK system might be a major mechanism for increased bone formation and decreased bone resorption in distraction osteogenesis with bovine lactoferrin treatment.

CLINICAL RELEVANCE

Oral administration of bovine lactoferrin may provide a feasible approach for promoting osteogenesis during distraction osteogenesis.

Effect of lactoferrin-impregnated porous poly(lactide-co-glycolide) (PLGA) microspheres on osteogenic differentiation of rabbit adipose-derived stem cells (rADSCs)

The aim of this study was to develop lactoferrin (LF)-impregnated porous poly(lactide-co-glycolide) (PLGA) microspheres (PMs) to induce osteogenic differentiation of rabbit adipose-derived stem cells (rADSCs). Porous PLGA PMs were fabricated by a fluidic device and their surfaces were modified with heparin-dopamine (Hep-DOPA). Then, LF (100μg, 500μg, and 1000μg) was impregnated on the surface of heparinized PMs (Hep-PMs) via electrostatic interactions to yield LF-impregnated PMs. PMs and modified PMs were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Osteogenic differentiation of rADSCs on PMs and modified PMs was demonstrated by alkaline phosphatase (ALP) activity, calcium deposition, and mRNA expression of osteocalcin and osteopontin. Successful immobilization of Hep-DOPA and LF on the surface of PMs was confirmed by XPS analysis. LF-impregnated PMs generated significantly greater ALP activity, calcium deposition, and mRNA expression of osteocalcin and osteopontin compared with PMs. These results suggested that LF-impregnated PMs effectively induced osteogenic differentiation of rADSCs.

The bone regenerative effects of fucosterol in in vitro and in vivo models of postmenopausal osteoporosis

SCOPE

The aim of this study was to investigate the bone regenerative effects of fucosterol in estrogen-deficient ovariectomized (OVX) rats.

METHODS AND RESULTS

Bone regeneration was assessed in fucosterol-treated MG63 cells in vitro via assays for osteoblast proliferation, alkaline phosphatase, and osteoclast differentiation. Osteoblast proliferation rates, alkaline phosphatase activity, and mineralization were increased in the fucosterol-treated group. Moreover, differentiation of osteoclasts was decreased in the fucosterol-treated group. In the in vivo assay, female rats were OVX. Twelve weeks after ovariectomy, rats were divided into seven groups, each oral administrate everyday for 7 weeks. The bone mineral density of femoral bones was higher in fucosterol groups than in OVX control, and body weight was lower in fucosterol groups. Among bone-quality parameters, bone volume/total volume increased and trabecular separation decreased in fucosterol groups relative to the OVX control. Bone formation and resorption were evaluated using the serum biomarkers osteocalcin and CTx. Fucosterol tripled the level of serum osteocalcin relative to the OVX group and reduced the serum level of CTx.

CONCLUSION

These results suggest that fucosterol has the dual potentials to activate osteoblasts to stimulate bone formation and suppress differentiation of osteoclasts so as to reduce bone resorption.

Bovine lactoferrin ingestion protects against inflammation via IL-11 induction in the small intestine of mice with hepatitis

Accumulating evidence suggests that orally ingested lactoferrin protects against inflammation. To assess the efficacy of orally administered bovine lactoferrin (bLF) against hepatitis and to identify the underlying mechanism, in the present study, we used four mouse models of hepatitis induced by d-galactosamine (GalN), carbon tetrachloride (CCl4), GalN plus lipopolysaccharide (LPS) and zymosan plus LPS. Intraperitoneal (i.p.) injection of GalN (500 mg/kg body weight) in mice treated with bovine serum albumin (BSA) for 14 d significantly increased serum aspartate aminotransferase (AST) concentrations compared with the untreated mice. However, orally administered bLF reduced AST concentrations compared with BSA treatment. In mice that received a single injection (0·4 ml/kg) and twice-weekly injections (0·08 ml/kg) of CCl4 for 24 weeks and pretreated with bLF for 14 d and 24 weeks, respectively, significantly suppressed alanine aminotransferase and AST concentrations were observed compared with the BSA-treated control. Oral administration of bLF for 14 d before i.p. injection of LPS (5 mg/kg) plus GalN (1 g/kg) significantly improved the survival rate. In mice that received intravenous injection of zymosan (25 mg/kg) and LPS (15 μg/kg) at 7 d intervals, bLF reduced the elevation of AST concentrations and enhanced the production of IL-11 and bone morphogenetic protein 2 in the small intestine compared with the BSA-treated control. To evaluate the effects of IL-11, we used IL-11 receptor α-null mice treated with GalN, CCl4 and zymosan plus LPS. In this group, the activity of bLF was not significantly different from that of BSA. These data indicate that orally ingested bLF enhances the expression of IL-11 in the small intestine and up-regulates protective activity in mice with hepatitis.

Lactoferrin stimulates osteoblast differentiation through PKA and p38 pathways independent of lactoferrin's receptor LRP1

Lactoferrin (LF) has been established as a potent anabolic factor for bone health both in vivo and in vitro. However, the molecular mechanisms underlying LF's action are still largely unknown. Here, we explore the signaling pathways that mediate LF's beneficial effect on osteoblast differentiation. In primary osteoblast and preosteoblast MC3T3‐E1, LF promoted alkaline phosphatase (ALP)activity, osteocalcin (OCN) secretion, and mineralization. Along with this enhanced osteogenic differentiation, activation of p38 mitogen‐activated protein kinase (MAPK) was detected in LF‐treated MC3T3‐E1 cells. Downregulating p38 with selective inhibitor SB203580 or p38a small interfering RNA (siRNA) attenuated the effect of LF on osteogenesis. Furthermore, knockdown of p38α significantly decreased LF‐induced Runt‐related transcription factor 2 (Runx2) phosphorylation. According to previous studies and our results, we speculated that LF‐induced osteoblast proliferation and differentiation were two relatively separate processes controlled by extracellular signal‐regulated kinase 1/2 (ERK1/2) and p38 pathways, respectively. Besides p38 MAPK activation, protein kinase A(PKA) was also activated in MC3T3‐E1 cells. PKA inhibitor H89 significantly inhibited LF‐induced p38 activation, ALP activity, and OCN secretion, indicating that PKA possibly acted as an upstream kinase of p38. In order to further identify the role of LF's receptor low-density lipoprotein receptor‐related protein 1 (LRP1), we constructed LRP1 stable‐knockdown MC3T3‐E1 cells. Neither LRP1 antagonist receptor associated protein (RAP), nor LRP1 knockdown approach could attenuate the LF‐induced osteogenesis, implying that LF stimulated osteoblast differentiation via an LRP1‐independent pathway. Taken together, the present work indicated that LF stimulated MC3T3‐E1 preosteoblast differentiation mainly through LRP1‐independent PKA and p38 signaling pathways. These results provided the first evidence of the signaling mechanisms of LF's effect on osteoblast differentiation.

Shark protein improves bone mineral density in ovariectomized rats and inhibits osteoclast differentiation

OBJECTIVES

Fish proteins are potential sources of natural medicines and food additives. There are many studies being performed to develop underutilized fish proteins. Therefore, the aim of this study was to determine how shark protein functions as a dietary supplement for bone health.

METHODS

Three groups of ovariectomized (OVX) rats were fed different diets containing 20% casein protein, 20% shark protein, or 20% cod protein for 4 wk. Bone mineral density of the right femur was measured by dual-energy x-ray absorptiometry and quantitative computed tomography. Furthermore, we prepared low-molecular-weight peptides from shark protein using protease for in vitro studies. Calcitriol was added to bone marrow cells and the receptor activator of the nuclear factor-κB ligand was added to RAW264 cells. After 7 d, the number of tartrate-resistant acid phosphatase-positive cells was counted.

RESULTS

In the shark protein-fed group, bone mineral density of the femur epiphysis was higher than that of the casein protein-fed group. In particular, the shark protein-fed group showed an increase in bone mineral density, represented mainly by trabecular bone. Shark protein hydrolysates inhibited osteoclast formation in bone marrow cells and RAW264 cells.

CONCLUSIONS

These results suggest that shark protein might suppress the bone loss caused by estrogen deficiency through the suppression of osteoclast formation.