Vitamin A and carotenoids stimulate differentiation of mouse osteoblastic cells

Lycopene Improves Bone Quality in SAMP6 Mice by Inhibiting Oxidative Stress, Cellular Senescence, and the SASP

SCOPE

Cellular senescence (CS) is closely related to tissue ageing including bone ageing. CS and the senescence-associated secretory phenotype (SASP) have emerged as critical pathogenesis elements of senile osteoporosis. This study aims to investigate the effect of lycopene on senile osteoporosis.

METHODS AND RESULTS

The senescence-accelerated mouse prone 6 (SAMP6) strain of mice is used as the senile osteoporosis model. Daily ingestion of lycopene for 8 weeks preserves the bone mass, density, strength, and microarchitecture in the SAMP6 mice. Moreover, these alterations are associated with a decrease in oxidative stress in the senile osteoporosis model. In addition, there is a reduction in osteoblast and osteocyte senescence and the SASP in the bone tissues of the SAMP6 mice. Lycopene improves bone health likely due to its antioxidant properties that may be linked with the regulation of CS and SASP in the SAMP6 mice.

CONCLUSION

These results suggest that lycopene may be beneficial for the management of senile osteoporosis by inhibiting oxidative stress, CS, and the SASP.

The effects of β-carotene on osteoporosis: a systematic review and meta-analysis of observational studies

PURPOSE

The aim is to evaluate the effect of β-carotene for osteoporosis and provide quantitative evidence.

METHOD

PubMed, Embase, Web of Science, and Cochrane Library were searched for eligible studies. Fifteen studies were included. Random-effect model was applied to pool the odds ratio (OR). The risk of osteoporosis and fracture were compared between low β-carotene intake group and high β-carotene intake group.

RESULT

The intake of β-carotene was unassociated with the overall risk of osteoporosis [OR = 0.733, 95% Cl (0.528, 1.018), p = 0.064]. Subgroup analysis showed that the intake of β-carotene was negatively associated with the risk of osteoporosis in both male subgroup [OR = 0.7, 95% Cl (0.549, 0.893), I² = 40.40%, p = 0.004] and female subgroup [OR = 0.684, 95% Cl (0.487, 0.960), I² = 86.40%, p = 0.028]. There was also a negative association between β-carotene intake and osteoporosis in Asia subgroup [OR = 0.512, 95% Cl (0.403, 0.650), I² = 0.00%, p = 0], whereas no association was observed in Western subgroup [OR = 1.107, 95% Cl (0.908, 1.350), I² = 2.30%, p = 0.314]. In addition, random-effect model was adopted to pool the standard mean difference (SMD), and the results showed that β-carotene intake was positively associated with overall bone mineral density (BMD) [SMD =  - 0.213, 95% Cl (- 0.391, - 0.034), I² = 87.30%, p = 0.019]. Subgroup analysis showed that β-carotene intake was positively associated with BMD in Asian participants [SMD =  - 0.394, 95% Cl (- 0.461, - 0.328), I² = 0, p = 0], while unassociated in Western participants [SMD =  - 0.047, 95% Cl (- 0.314, 0.219), I² = 78.9%, p = 0.727].

CONCLUSION

β-carotene may improve BMD and reduce the risk of osteoporosis and fracture. However, these effects could vary by gender and race and need to be further validated by longitudinal studies.

Plant-Derived Nanoscale-Encapsulated Antioxidants for Oral and Topical Uses: A Brief Review

Several plant-based nanoscale-encapsulated antioxidant compounds (rutin, myricetin, β-carotene, fisetin, lycopene, quercetin, genkwanin, lutein, resveratrol, eucalyptol, kaempferol, glabridin, pinene, and whole-plant bio-active compounds) are briefly introduced in this paper, along with their characteristics. Antioxidants’ bioavailability has become one of the main research topics in bio-nanomedicine. Two low patient compliance drug delivery pathways (namely, the oral and topical delivery routes), are described in detail in this paper, for nanoscale colloidal systems and gel formulations. Both routes and/or formulations seek to improve bioavailability and maximize the drug agents’ efficiency. Some well-known compounds have been robustly studied, but many remain elusive. The objective of this review is to discuss recent studies and advantages of nanoscale formulations of plant-derived antioxidant compounds.

A Rapid and Cheap Method for Extracting and Quantifying Lycopene Content in Tomato Sauces: Effects of Lycopene Micellar Delivery on Human Osteoblast-Like Cells

Identifying and quantifying the beneficial molecules contained in nutraceuticals is essential to predict the effects derived from their consumption. This study explores a cheap and rapid method for quantifying lycopene content from a semi-solid matrix. In addition, it compares the in vitro effects of the extracts obtained from different tomato sauces available on the local market with Osteocol®, a patented tomato sauce from southern Italy. We performed a liquid extraction of lycopene using suitable solvents. The lycopene extracted was encapsulated in surfactant micelles and finally tested in vitro on Saos-2 cells. The effects exerted by lycopene on ALP and Wnt/β-catenin pathways were investigated by Western blotting. Hexane was found to be the best solvent for lycopene extraction. Spectrophotometrical and HPLC analyses showed similar trends. Osteocol® contained 39 ± 4 mg lycopene per 100 g of sauce, while the best commercial product contained 19 ± 1 mg/100 g. The Osteocol® lycopene extract increased ALP and β-catenin protein expressions in a dose-dependent manner, also showing statistically significant results (p < 0.05 respectively). In conclusion, despite both techniques showing similar final results, UV/VIS spectrophotometer is preferable to HPLC due to its cheap, rapid, and accurate results, as well as for the opportunity to analyze lycopene-loaded micelles. The extraction and release of lycopene to bone cells positively influences the differentiation of osteoblasts and increases the expression of the ALP and β-catenin proteins. As a consequence, as a lycopene-rich sauce, Osteocol® represents a useful supplement in the prevention of osteoporosis compared to its commercial competitors.

Vitamin A and Bone Health: A Review on Current Evidence

Vitamin A is a fat-soluble micronutrient essential for growth, immunity, and good vision. The preformed retinol is commonly found in food of animal origin whereas provitamin A is derived from food of plant origin. This review summarises the current evidence from animal, human and cell-culture studies on the effects of vitamin A towards bone health. Animal studies showed that the negative effects of retinol on the skeleton were observed at higher concentrations, especially on the cortical bone. In humans, the direct relationship between vitamin A and poor bone health was more pronounced in individuals with obesity or vitamin D deficiency. Mechanistically, vitamin A differentially influenced the stages of osteogenesis by enhancing early osteoblastic differentiation and inhibiting bone mineralisation via retinoic acid receptor (RAR) signalling and modulation of osteocyte/osteoblast-related bone peptides. However, adequate vitamin A intake through food or supplements was shown to maintain healthy bones. Meanwhile, provitamin A (carotene and β-cryptoxanthin) may also protect bone. In vitro evidence showed that carotene and β-cryptoxanthin may serve as precursors for retinoids, specifically all-trans-retinoic acid, which serve as ligand for RARs to promote osteogenesis and suppressed nuclear factor-kappa B activation to inhibit the differentiation and maturation of osteoclasts. In conclusion, we suggest that both vitamin A and provitamin A may be potential bone-protecting agents, and more studies are warranted to support this hypothesis.

Potential Role of Lycopene in the Prevention of Postmenopausal Bone Loss: Evidence from Molecular to Clinical Studies

Osteoporosis is a metabolic bone disease characterized by reduced bone mineral density, which affects the quality of life of the aging population. Furthermore, disruption of bone microarchitecture and the alteration of non-collagenous protein in bones lead to higher fracture risk. This is most common in postmenopausal women. Certain medications are being used for the treatment of osteoporosis; however, these may be accompanied by undesirable side effects. Phytochemicals from fruits and vegetables are a source of micronutrients for the maintenance of bone health. Among them, lycopene has recently been shown to have a potential protective effect against bone loss. Lycopene is a lipid-soluble carotenoid that exists in both all-trans and cis-configurations in nature. Tomato and tomato products are rich sources of lycopene. Several human epidemiological studies, supplemented by in vivo and in vitro studies, have shown decreased bone loss following the consumption of lycopene/tomato. However, there are still limited studies that have evaluated the effect of lycopene on the prevention of bone loss in postmenopausal women. Therefore, the aim of this review is to summarize the relevant literature on the potential impact of lycopene on postmenopausal bone loss with molecular and clinical evidence, including an overview of bone biology and the pathophysiology of osteoporosis.

Lycopene and bone: an in vitro investigation and a pilot prospective clinical study

Background

There are several effective therapies for osteoporosis but these agents might cause serious adverse events. Lycopene intake could prevent bone loss, however studies on its effects on bone are scarce. Our aim was to investigate the effects of lycopene on osteoblast cells as well as bone mineral density and bone turnover markers in postmenopausal women.

Methods

We investigated the effect of lycopene on the Wnt/β-catenin and ERK 1/2 pathways, RUNX2, alkaline phosphatase, RANKL and COL1A of Saos-2. We also carried out a pilot controlled clinical study to verify the feasibility of an approach for bone loss prevention through the intake of a lycopene-rich tomato sauce in 39 postmenopausal women.

Results

Lycopene 10 µM resulted in higher β-catenin and phERK1/2 protein Vs the vehicle (p = 0.04 and p = 0.006). RUNX2 and COL1A mRNA was induced by both 5 and 10 µM doses (p = 0.03; p = 0.03 and p = 0.03; p = 0.05) while RANKL mRNA was reduced (p < 0.05). A significant bone density loss was not detected in women taking the tomato sauce while the control group had bone loss (p = 0.002). Tomato sauce intake resulted in a greater bone alkaline phosphatase reduction than the control (18% vs 8.5%, p = 0.03).

Conclusions

Lycopene activates the WNT/β-catenin and ERK1/2 pathways, upregulates RUNX2, alkaline phosphatase, COL1A and downregulates RANKL Saos-2. These processes contributed to prevent bone loss in postmenopausal women.

Lycopene influences osteoblast functional activity and prevents femur bone loss in female rats submitted to an experimental model of osteoporosis

Antioxidant properties of several nutrients may influence bone metabolism, affording protection against damaging effects caused by oxidative stress. Thus, we hypothesized that lycopene may benefit bone tissue metabolism and functional activity of osteoblastic cells from bone marrow of osteoporotic female rats. Wistar rats were ovariectomized and paired with sham animals. In vitro evaluations were performed after 60 days of surgery, when cells were cultured in osteogenic medium and divided in control (C), ovariectomized (OVX) and ovariectomized + 1 μmol/L lycopene (OVXL) groups. Besides, in vivo studies were carried out to evaluate femur bone remodeling by histological and histomorphometric analyses after daily intake of 10 mg/kg of lycopene for 30 and 60 days after ovariectomy. Cell proliferation was significantly higher in OVX and OVXL groups after 10 days of culture. Alkaline phosphatase activity (ALP) was higher in OVXL group in later periods of cell culture, whereas its in situ detection was higher for this group in all experimental periods; nevertheless, mineralization did not show significant differences among the groups. There was a significant upregulation of genes Sp7, Runx2 and Bsp after 3 days and genes Runx2 and Bglap after 10 days from OVXL when compared to OVX. In vivo results demonstrated that daily intake of 10 mg/kg of lycopene for 60 days decreased bone loss in femur epiphysis in ovariectomized rats by maintaining trabecular bone similar to controls. Data obtained suggest that lycopene might benefit the functional activity of osteoblastic cells from ovariectomized rats, as well as avoid further bone resorption.

Ethyl acetate and n-butanol fraction of Cissus quadrangularis promotes the mineralization potential of murine pre-osteoblast cell line MC3T3-E1 (sub-clone 4)

In a sequel to investigate osteogenic potential of ethanolic extract of Cissus quadrangularis (CQ), the present study reports the osteoblast differentiation and mineralization potential of ethyl acetate (CQ-EA) and butanol (CQ-B) extracts of CQ on mouse pre-osteoblast cell line MC3T3-E1 (sub-clone 4) with an objective to isolate an antiosteoporotic compound. Growth curve, proliferation, and viability assays showed that both the extracts were nontoxic to the cells even at high concentration (100 µg/ml). The cell proliferation was enhanced at low concentrations (0.1 µg/ml and 1 µg/ml) of both the extracts. They also upregulated the osteoblast differentiation and mineralization processes in MC3T3-E1 cells as reflected by expression profile of osteoblast marker genes such as RUNX2, Osterix, Collagen (COL1A1), Alkaline Phosphatase (ALP), Integrin-related Bone Sialoprotein (IBSP), Osteopontin (OPN), and Osteocalcin (OCN). CQ-EA treatment resulted in early differentiation and mineralization as compared with the CQ-B treatment. These findings suggest that low concentrations of CQ-EA and CQ-B have proliferative and osteogenic properties. CQ-EA, however, is more potent osteogenic than CQ-B.

Biodegradable bead-on-spring nanofibers releasing β-carotene for bone tissue engineering

Bead-on-string mats based on poly(lactide-co-glycolide) (PLGA) releasing β-carotene (βC) as a natural osteogen were fabricated and used for bone tissue engineering. Mesenchymal stem cells (MSCs) seeded on the scaffolds successfully differentiated to osteoblasts without using any a differential medium. The mats showed a small burst of β-carotene (24-27%) during the first day and a sustained slow release up to 21 days. The MTT and SEM results indicated good attachment and proliferation of MSCs on the scaffolds. Calcination of scaffolds and expression of RUNX2, SOX9, and osteonectin genes approved the differentiation of seeded MSCs to osteoblasts without using any external osteogenic differential agent. The scaffold loaded with 4% β-carotene not only induced the early phase of osteogenesis but also advanced the differentiation to the osteoblast maturation phase. Thus, these bead-on-string scaffolds can be used as a substrate for direct bone tissue engineering.

Higher dietary carotenoid intake associated with lower risk of hip fracture in middle-aged and elderly Chinese: A matched case-control study

BACKGROUND

Mechanism studies have suggested that carotenoids may benefit bone health due to their antioxidant properties, but epidemiological data on their effects on risk of hip fracture are sparse.

PURPOSE

To explore the relationships between dietary total and specific carotenoids and the risk of hip fracture in a middle-aged and elderly Chinese population.

DESIGN

A case-control study of 1070 patients with hip fractures (diagnosed within 2 weeks) aged 55-80 years and 1070 age- (within 3 years) and gender-matched controls was conducted in Guangdong, China between 2009 and 2015. Information on dietary carotenoid intake was assessed using a 79-item food frequency questionnaire administered in face-to-face interviews, and general information was collected using structured questionnaires. The univariate and multivariate conditional logistic regression models were applied to analyze the associations.

MAIN RESULTS

Higher intakes of both total and some specific carotenoids (including β-carotene, β-cryptoxanthin and lutein/zeaxanthin) were significantly associated with a lower risk of hip fracture (all p trends <0.01). Compared with the lowest quartile of carotenoids, the multivariate-adjusted odds ratios and 95% confidential intervals of the highest quartile were 0.44 (0.29, 0.68) (total carotenoids), 0.50 (0.29, 0.69) (β-carotene), 0.55 (0.38, 0.80) (β-cryptoxanthin) and 0.40 (0.27, 0.59) (lutein/zeaxanthin), respectively. There were no statistically significant associations between α-carotene and lycopene intakes and hip fracture risk after adjustment for various confounding variables.

CONCLUSION

These results suggest that the consumption of carotenoids may be protective against hip fracture in middle-aged and elderly Chinese adults.

β-Carotene prevents bone loss in hind limb unloading mice

β-Carotene has been reported to be useful to maintain a positive balance of bone turnover. However, the effects of β-carotene on bone loss remain to be elucidated in mice with hind limb unloading. Therefore, we investigated whether β-carotene prevented bone loss induced by skeletal hind limb unloading in mice. Female 8-week-old ddY mice were divided into six groups (n = 6–8 each) and subjected to: (1) normal housing, (2) sham unloading fed a control diet, (3) hind limb unloading fed a control diet, (4) hind limb unloading fed a 0.025% β-carotene-containing diet, (5) hind limb unloading fed a 0.05% β-carotene-containing diet, and (6) hind limb unloading fed a 0.25% β-carotene-containing diet. After 3 weeks, bone mineral density of the tibia was markedly reduced by unloading, which was prevented by 0.025% β-carotene. Histological analysis revealed a hind limb unloading-induced decrease in the calcified bone of the femur, which was slightly prevented by 0.025% β-carotene. The 0.025% β-carotene-containing diet increased the gene expression of osteoprotegerin in the bone marrow cells in unloading mice. These results suggest that a β-carotene-containing diet may preserve bone health in subjects with disabilities as well as in astronauts.

Carotenoids and risk of fracture: a meta-analysis of observational studies

To quantify the association between dietary and circulating carotenoids and fracture risk, a meta-analysis was conducted by searching MEDLINE and EMBASE databases for eligible articles published before May 2016. Five prospective and 2 case-control studies with 140,265 participants and 4,324 cases were identified in our meta-analysis. Among which 5 studies assessed the association between dietary carotenoids levels and hip fracture risk, 2 studies focused on the association between circulating carotenoids levels and any fracture risk. A random-effects model was employed to summarize the risk estimations and their 95% confidence intervals (CIs). Hip fracture risk among participants with high dietary total carotenoids intake was 28% lower than that in participants with low dietary total carotenoids (OR: 0.72; 95% CI: 0.51, 1.01). A similar risk of hip fracture was found for β-carotene based on 5 studies, the summarized OR for high vs. low dietary β-carotene was 0.72 (95% CI: 0.54, 0.95). However, a significant between-study heterogeneity was found (total carotene: I2 = 59.4%, P = 0.06; β-carotene: I2 = 74.4%, P = 0.04). Other individual carotenoids did not show significant associations with hip fracture risk. Circulating carotene levels had no significant association with any fracture risk, the pooled OR (95% CI) was 0.83 (0.59, 1.17). Based on the evidence from observational studies, our meta-analysis supported the hypothesis that higher dietary total carotenoids or β-carotene intake might be potentially associated with a low risk of hip fracture, however, future well-designed prospective cohort studies and randomized controlled trials are warranted to specify the associations between carotenoids and fracture.

β-Carotene: a natural osteogen to fabricate osteoinductive electrospun scaffolds

β-Carotene (βC) as a natural osteogenic material was incorporated in PCL electrospun mats to fabricate scaffolds for bone tissue engineering. These scaffolds successfully supported the attachment and proliferation of mesenchymal stem cells (MSCs). Seeded scaffolds were calcinated during 21 days of cell culture in a non-differential medium, which showed the osteodifferentiation of MSCs. Expression of RUNX2, SOX9, and osteonectin proved the osteoinductive effect of incorporated β-carotene on the differentiation of MSCs to osteoblasts without using any external osteogenic differential agent. However, the cells did not pass the early phase of osteogenesis and were still osteochondro-progenitor after 21 days of incubation. Thus, the fabricated fibrous scaffolds are potential candidates for direct bone tissue engineering.

Electrospun PCL scaffolds containing β-carotene as a natural osteogenic material can differentiate MSCs to osteoblasts without using external differential agents.

Lycopene: Is it Beneficial to Human Health as an Antioxidant?

It is well known that free oxygen radicals play an important role in the pathogenesis of several chronic disorders. Antioxidants are known as potential scavengers of reactive oxygen species that can protect biologic membranes against oxidative damage. Recent interest in phytochemicals has increased because of their protective effects against free oxygen radicals. Lycopene, which belongs to the carotenoid family, is the most effective singlet oxygen scavenger in vitro of all the carotenoids. Foods that contain lycopene and related supplements have been reported to prevent chronic diseases including cancer, asthma, and cardiovascular disorders. The aim of the article was to give a brief review of the antioxidant properties and beneficial health effects of lycopene.

Carotenoid dietary intakes and plasma concentrations are associated with heel bone ultrasound attenuation and osteoporotic fracture risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohort

Carotenoids are found in abundance in fruit and vegetables, and may be involved in the positive association of these foods with bone health. This study aimed to explore the associations of dietary carotenoid intakes and plasma concentrations with bone density status and osteoporotic fracture risk in a European population. Cross-sectional analyses (n 14 803) of bone density status, using calcaneal broadband ultrasound attenuation (BUA) and longitudinal analyses (n 25 439) of fracture cases were conducted on data from the prospective European Prospective Investigation into Cancer and Nutrition-Norfolk cohort of middle-aged and older men and women. Health and lifestyle questionnaires were completed, and dietary nutrient intakes were derived from 7-d food diaries. Multiple regression demonstrated significant positive trends in BUA for women across quintiles of dietary α-carotene intake (P=0·029), β-carotene intake (P=0·003), β-cryptoxanthin intake (P=0·031), combined lutein and zeaxanthin intake (P=0·010) and lycopene intake (P=0·005). No significant trends across plasma carotenoid concentration quintiles were apparent (n 4570). The Prentice-weighted Cox regression showed no trends in fracture risk across dietary carotenoid intake quintiles (mean follow-up time 12·5 years), except for a lower risk for wrist fracture in women with higher lutein and zeaxanthin intake (P=0·022); nevertheless, inter-quintile differences in fracture risk were found for both sexes. Analysis of plasma carotenoid data (mean follow-up time 11·9 years) showed lower hip fracture risk in men across higher plasma α-carotene (P=0·026) and β-carotene (P=0·027) quintiles. This study provides novel evidence that dietary carotenoid intake is relevant to bone health in men and women, demonstrating that associations with bone density status and fracture risk exist for dietary intake of specific carotenoids and their plasma concentrations.

Ethanol Extract of Cissus quadrangularis Enhances Osteoblast Differentiation and Mineralization of Murine Pre-Osteoblastic MC3T3-E1 Cells

Traditional medicinal literature and previous studies have reported the possible role of Cissus quadrangularis (CQ) as an anti-osteoporotic agent. This study examines the effectiveness of CQ in promoting osteoblast differentiation of the murine pre-osteoblast cell line, MC3T3-E1. Ethanolic extract of CQ (CQ-E) was found to affect growth kinetics of MC3T3-E1 cells in a dosage-dependent manner. High concentrations of CQ-E (more than 10 μg/ml) have particularly adverse effects, while lower concentrations of 0.1 and 1 µg/ml were non-toxic and did not affect cell viability. Notably, cell proliferation was significantly increased at the lower concentrations of CQ-E. CQ-E treatment also augmented osteoblast differentiation, as reflected by a substantial increase in expression of the early osteoblast marker ALP activity, and at later stage, by mineralization of extracellular matrix compared to the control group. These findings suggest dose-dependent effect of CQ-E with lower concentrations exhibiting anabolic and osteogenic properties. J. Cell. Physiol. 232: 540-547, 2017. © 2016 Wiley Periodicals, Inc.

Immediate effects of retinoic acid on gene expression in primary murine osteoblasts

Consistent with clinical observations demonstrating that hypervitaminosis A is associated with increased skeletal fracture risk, we have previously found that dietary retinol deprivation partially corrects the bone mineralization defects in a mouse model of X-linked hypophosphatemic rickets. That retinol-dependent signaling pathways impact the skeleton is further supported by various findings demonstrating a negative influence of retinoic acid (RA) on bone-forming osteoblasts. We hypothesized that RA would directly regulate the expression of specific target genes in osteoblasts, and we aimed to identify these by genome-wide expression analyses. Here we show that high dietary retinol intake in mice causes low bone mass associated with increased osteoclastogenesis and decreased osteoblastogenesis, but intact bone matrix mineralization. We additionally found that short-term treatment of primary osteoblasts with RA causes a rapid induction of specific genes involved in either retinol-dependent signaling (i.e. Rara, Crabp2) or skeletal remodeling (i.e. Twist2, Tnfsf11). In contrast, neither expression of established osteoblast differentiation markers nor the proliferation rate was immediately affected by RA administration. Collectively, our data suggest that the negative effects of vitamin A on skeletal integrity are explainable by an immediate influence of RA signaling on specific genes in osteoblasts that in turn influence bone remodeling.

Combined Effects of Soy Isoflavones and β-Carotene on Osteoblast Differentiation

Soy isoflavones, genistein, daidzein and its metabolite equol, as well as β-carotene have been reported to be effective for maintaining bone health. However, it remains to be elucidated whether combining soy isoflavones with β-carotene is beneficial to bone formation. This study investigated the combined effect of soy isoflavones and β-carotene on the differentiation of MC3T3-E1 preosteoblastic cells. Daidzein and genistein alone did not affect cell growth but increased alkaline phosphatase (ALP) activity. Beta-carotene alone inhibited cell growth and markedly enhanced ALP activity. Soy isoflavones combined with β-carotene resulted in higher ALP activity than treatment with isoflavones or β-carotene alone. We observed significant main effects of β-carotene on the enhanced expression of Runx2, ALP, and ostepontin mRNA, whereas there was a significant main effect of soy isoflavones on the expression of osterix mRNA. To investigate how β-carotene affected osteoblast differentiation, MC3T3-E1 cells were treated with retinoic acid receptor (RAR) pan-antagonist combined with β-carotene. Osteopontin and ALP mRNA expression levels, which were increased following treatment with β-carotene, were significantly suppressed by the RAR pan-antagonist. This suggests treatment with β-carotene enhanced early osteoblastic differentiation, at least in part via RAR signaling. These results indicate that a combination of isoflavones and β-carotene may be useful for maintaining a positive balance of bone turnover by inducing osteoblast differentiation.

Time-lapse Raman imaging of osteoblast differentiation

Osteoblastic mineralization occurs during the early stages of bone formation. During this mineralization, hydroxyapatite (HA), a major component of bone, is synthesized, generating hard tissue. Many of the mechanisms driving biomineralization remain unclear because the traditional biochemical assays used to investigate them are destructive techniques incompatible with viable cells. To determine the temporal changes in mineralization-related biomolecules at mineralization spots, we performed time-lapse Raman imaging of mouse osteoblasts at a subcellular resolution throughout the mineralization process. Raman imaging enabled us to analyze the dynamics of the related biomolecules at mineralization spots throughout the entire process of mineralization. Here, we stimulated KUSA-A1 cells to differentiate into osteoblasts and conducted time-lapse Raman imaging on them every 4 hours for 24 hours, beginning 5 days after the stimulation. The HA and cytochrome c Raman bands were used as markers for osteoblastic mineralization and apoptosis. From the Raman images successfully acquired throughout the mineralization process, we found that β-carotene acts as a biomarker that indicates the initiation of osteoblastic mineralization. A fluctuation of cytochrome c concentration, which indicates cell apoptosis, was also observed during mineralization. We expect time-lapse Raman imaging to help us to further elucidate osteoblastic mineralization mechanisms that have previously been unobservable.

Decreased serum and mucosa immunoglobulin A levels in vitamin Aand zinc-deficient mice

Simultaneous zinc and vitamin A deficiency are common health problems in developing countries. The objective of this study was to assess the effect of vitamin A- and zinc-deficient diet on immunoglobulin A (IgA) response. Six-week-old mice were assigned into two groups receiving a normal vitamin A and zinc or low vitamin A and zinc diet for five months. Serum and intestinal mucosa IgA levels were determined by the enzyme-linked immunosorbent assay method. The concentration of zinc in serum was determined using an inductively coupled plasma mass spectrometer. Vitamin A measurement in serum was carried out by high performance liquid chromatography. Mice maintained on a low vitamin A and zinc diet showed significantly greater food intake but lower production of IgA both in serum and mucosa. A mucosa IgA level was significantly higher in both control and deficient groups than the serum IgA level. Results indicated that zinc and vitamin A deficiency is associated with a lower production of IgA. Micronutrient intervention strategies addressing IgA-related gastrointestinal infections are needed.

Protective effects of dietary carotenoids on risk of hip fracture in men: the Singapore Chinese Health Study

Experimental and epidemiologic data suggest that carotenoids in vegetables and fruits may benefit bone health due to their antioxidant properties. The relationship between dietary total and specific carotenoids, as well as vegetables and fruits, and risk of hip fracture was examined among Chinese in Singapore. We used data from the Singapore Chinese Health Study, a prospective cohort of 63,257 men and women who were of ages 45 to 74 years between 1993 and 1998. At recruitment, subjects were interviewed on lifestyle factors and medical history. Usual diet was measured using a validated food frequency questionnaire. During a mean follow-up of 9.9 years, we identified 1630 hip fracture incident cases. Among men, consumption of vegetables was associated with lower hip fracture risk. Similarly, dietary total carotenoids and specific carotenoids, α-carotene, β-carotene, and lutein/zeaxanthin were inversely associated with hip fracture risk. Compared to men in the lowest quartile of nutrient density, men in the highest quartile had statistically significant 26% to 39% risk reduction (all p for trend <0.05). When stratified by body mass index (BMI), the greatest protective effects of total vegetables and carotenoids were found in men with BMI <20 kg/m(2) (p for trend ≤0.004). There was no association between dietary carotenoids or vegetables/fruits and hip fracture risk among women. This study suggests that adequate intake of vegetables may reduce risk of osteoporotic fractures among elderly men and that the antioxidant effects of carotenoids may counteract the mechanism of osteoporosis related to leanness.

Deficiency of retinaldehyde dehydrogenase 1 induces BMP2 and increases bone mass in vivo

The effects of retinoids, the structural derivatives of vitamin A (retinol), on post-natal peak bone density acquisition and skeletal remodeling are complex and compartment specific. Emerging data indicates that retinoids, such as all trans retinoic acid (ATRA) and its precursor all trans retinaldehyde (Rald), exhibit distinct and divergent transcriptional effects in metabolism. Despite these observations, the role of enzymes that control retinoid metabolism in bone remains undefined. In this study, we examined the skeletal phenotype of mice deficient in retinaldehyde dehydrogenase 1 (Aldh1a1), the enzyme responsible for converting Rald to ATRA in adult animals. Bone densitometry and micro-computed tomography (µCT) demonstrated that Aldh1a1-deficient (Aldh1a1^−/−) female mice had higher trabecular and cortical bone mass compared to age and sex-matched control C57Bl/6 wild type (WT) mice at multiple time points. Histomorphometry confirmed increased cortical bone thickness and demonstrated significantly higher bone marrow adiposity in Aldh1a1^−/− mice. In serum assays, Aldh1a1^−/− mice also had higher serum IGF-1 levels. In vitro, primary Aldh1a1^−/− mesenchymal stem cells (MSCs) expressed significantly higher levels of bone morphogenetic protein 2 (BMP2) and demonstrated enhanced osteoblastogenesis and adipogenesis versus WT MSCs. BMP2 was also expressed at higher levels in the femurs and tibias of Aldh1a1^−/− mice with accompanying induction of BMP2-regulated responses, including expression of Runx2 and alkaline phosphatase, and Smad phosphorylation. In vitro, Rald, which accumulates in Aldh1a1^−/− mice, potently induced BMP2 in WT MSCs in a retinoic acid receptor (RAR)-dependent manner, suggesting that Rald is involved in the BMP2 increases seen in Aldh1a1 deficiency in vivo. Collectively, these data implicate Aldh1a1 as a novel determinant of cortical bone density and marrow adiposity in the skeleton in vivo through modulation of BMP signaling.

Prolonged overdose of all-trans retinoic acid enhances bone sensitivity in castrated mice

OBJECTIVES

Intake of multivitamin preparations is very common in developed countries. However, excessive intake of vitamin A was associated with increased bone fragility. The aim of this study was to determine if chronic administration of the active metabolite of vitamin A all-trans-retinoic acid (ATRA) in slight excess is associated with changes of bone turnover and density in intact and castrated mice.

METHOD

Three mo old male mice (C57B1/6) intact and castrated were injected intraperitonealy with 10 mg/kg/d of the ATRA or vehicle (control) once daily for 3 wk. The bone density, ash weights, calcium, and phosphorus content of the femur were measured. Plasma tartrate-resistant acid phosphatase (Tr-ACP) and serum bone alkaline phosphatase (B-ALP) were determined.

RESULTS

ATRA decreased bone density in both groups; however, this effect was more pronounced in castrated animals (1.487 ± 0.04 to 1,360 ± 0.05 g/cm(3)) than in intact mice (1.570 ± 0.03 to 1.510 ± 0.03 g/cm(3)). Bone density correlated with decreased B-ALP and increased Tr-ACP in ATRA-treated mice. ATRA treatment led to significantly lower thickness of cortical bone both in the intact and castrated animals.

CONCLUSION

Our results indicate that repeated administration of ATRA in slight excess leads to significant bone loss both in intact and castrated mice. This effect was more pronounced in testosterone-deficient animals. Testosterone deficiency as occurs following castration may sensitize the bone to resorption mediated by ATRA. Therefore, chronic vitamin A administration may be a risk factor for osteoporosis, especially in older and testosterone-depleted subjects.

Chronic effects of lead (Pb) on bone properties in red deer and wild boar: relationship with vitamins A and D3

Here we study the occurrence of abnormalities on bone tissue composition and turnover mechanisms through the Pb-mediated disruption of vitamins A and D in wild ungulates living in a lead (Pb)-polluted mining area. Red deer (Cervus elaphus) and wild boar (Sus scrofa) from the mining area had significantly higher liver and bone Pb levels than controls, which were associated with the depletion of liver retinyl esters and the corresponding increase of free retinol levels both in deer and boar from the mining area. Pb-exposed adult deer had lower carbonate content in bone mineral than controls, which was associated with the increased free retinol percentage. In wild boar, the degree of bone mineralization was also positively associated with higher burdens of retinyl esters. These results suggest that Pb-associated changes in bone composition and mineralization is likely influenced by the depletion of vitamin A in wildlife exposed to environmental Pb pollution.

Polyphenols, isothiocyanates, and carotenoid derivatives enhance estrogenic activity in bone cells but inhibit it in breast cancer cells

While exposure to estrogens is a major risk factor of breast and endometrial cancer, it well established that estrogens are beneficial for bone health. We have previously shown that carotenoids inhibit estrogen signaling in breast and endometrial cancer cells. The aim of this study was to compare the effects of various phytonutrients, (carotenoid derivatives, polyphenols, isothiocyanates) on estrogenic activity in breast cancer cells and osteoblast-like cells. All the tested phytonutrients inhibited estrogen response element (ERE) transactivation in breast cancer cells. In contrast, these compounds either did not affect or enhanced ERE activity and the expression of several bone-forming genes. These results were obtained using two osteoblast-like cell lines, MG-63 human osteosarcoma cells stably transfected with estrogen receptor-α (ERα) and MC3T3-E1 mouse calvaria-derived cells expressing endogenous ER. Phytonutrients-induced ERE inhibition in breast cancer cells, and its potentiation in osteoblast-like cells were associated both with a decrease and a rise in total and nuclear ERα levels, respectively. Phytonutrients activated the electrophile/antioxidant response element (EpRE/ARE) transcription system to various extents in both cancer and bone cell lines. Overexpression of Nrf2, the major EpRE/ARE activating transcription factor, mimicked the effects of phytonutrients, causing inhibition and enhancement of ERE transactivation in breast cancer cells and in osteoblast-like cells, respectively. Moreover, reduction in Nrf2 levels by RNAi led to a decrease in the phytonutrient potentiation of ERE activity transactivation in osteoblast-like cells. These findings suggest that the enhancement and inhibition of estrogen signaling by phytonutrients in bone-derived cells and breast cancer cells, respectively, is partially mediated by the activation of the Nrf2/ARE system.

Retinol-binding protein 4 downregulation during osteogenesis and its localization to non-endocytic vesicles in human cranial suture mesenchymal cells suggest a novel tissue function

Craniosynostosis is a developmental disorder of the skull arising from premature bony fusion of cranial sutures, the sites of skull bone growth. In a recent gene microarray study, we demonstrated that retinol-binding protein 4 (RBP4) was the most highly downregulated gene in suture tissue during the pathological process of premature bony fusion. To gain insight into the function of RBP4 in cranial sutures, we analysed primary cells cultured from human cranial suture mesenchyme. These cells express RBP4 but not CRBP1, cellular retinol-binding protein 1, the typical cytoplasmic retinol storage protein. Using flow cytometry, we showed that suture mesenchymal cells express the RBP4 receptor, STRA6, on the cell surface. In a cell culture model of cranial osteogenesis, we found that RBP4 was significantly downregulated during mineralization, analogous to its decrease in pathological suture fusion. We found that cranial suture cells do not secrete detectable levels of RBP4, suggesting that it acts in a cell-autonomous manner. High-resolution confocal microscopy with a panel of antibody markers of cytoplasmic organelles demonstrated that RBP4 was present in several hundred cytoplasmic vesicles of about 300 nm in diameter which, in large part, were conspicuously distinct from the ER, the Golgi and endosomes of the endocytic pathway. We speculate that in suture mesenchymal cells, endogenous RBP4 receives retinol from STRA6 and the RBP4-retinol complex is stored in vesicles until needed for conversion to retinoic acid in the process of osteogenesis. This study extends the role of RBP4 beyond that of a serum transporter of retinol and implicates a broader role in osteogenesis.

Role of carotenoid β-cryptoxanthin in bone homeostasis

Bone homeostasis is maintained through a balance between osteoblastic bone formation and osteoclastic bone resorption. Aging induces bone loss due to decreased osteoblastic bone formation and increased osteoclastic bone resorption. Osteoporosis with its accompanying decrease in bone mass is widely recognized as a major public health problem. Nutritional factors may play a role in the prevention of bone loss with aging. Among various carotenoids (carotene and xanthophylls including beta (β)-cryptoxanthin, lutein, lycopene, β-carotene, astaxanthin, and rutin), β-cryptoxanthin, which is abundant in Satsuma mandarin orange (Citrus unshiu MARC.), has been found to have a stimulatory effect on bone calcification in vitro. β-cryptoxanthin has stimulatory effects on osteoblastic bone formation and inhibitory effects on osteoclastic bone resorption in vitro, thereby increasing bone mass. β-cryptoxanthin has an effect on the gene expression of various proteins that are related osteoblastic bone formation and osteoclastic bone resororption in vitro. The intake of β-cryptoxanthin may have a preventive effect on bone loss in animal models for osteoporosis and in healthy human or postmenopausal women. Epidemiological studies suggest a potential role of β-cryptoxanthin as a sustainable nutritional approach to improving bone health of human subjects. β-Cryptoxanthin may be an osteogenic factor in preventing osteoporosis in human subjects.

Supplementation with the antioxidant lycopene significantly decreases oxidative stress parameters and the bone resorption marker N-telopeptide of type I collagen in postmenopausal women

To date, no intervention studies have been published demonstrating the effect of the antioxidant lycopene on bone. Postmenopausal women supplemented with lycopene had significantly increased antioxidant capacity and decreased oxidative stress and the bone resorption marker N-telopeptide (NTx). Lycopene decreases bone resorption markers and may reduce the risk of osteoporosis.

INTRODUCTION

We have previously shown in vitro and in vivo that lycopene from tomato is associated with a protective effect on bone, but lycopene intervention studies have not been reported. Our aim was to carry out a randomized controlled intervention study to determine whether lycopene would act as an antioxidant to decrease oxidative stress parameters, resulting in decreased bone turnover markers, thus reducing the risk of osteoporosis in postmenopausal women.

METHODS

Sixty postmenopausal women, 50-60 years old, were recruited. Following a 1-month washout without lycopene consumption, participants consumed either (N = 15/group): (1) regular tomato juice, (2) lycopene-rich tomato juice, (3) tomato Lyc-O-Mato lycopene capsules, or (4) placebo capsules, twice daily for total lycopene intakes of 30, 70, 30, and 0 mg/day respectively for 4 months. Serum collected after the washout, 2 and 4 months of supplementation, was assayed for cross-linked aminoterminal N-telopeptide, carotenoid content, total antioxidant capacity (TAC), lipid, and protein oxidation.

RESULTS

Participants who consumed juice or lycopene capsules were analyzed in one group designated "LYCOPENE-supplemented". Repeated measures ANOVA showed that LYCOPENE-supplementation for 4 months significantly increased serum lycopene compared to placebo (p < 0.001). LYCOPENE-supplementation for 4 months resulted in significantly increased TAC (p < 0.05) and decreased lipid peroxidation (p < 0.001), protein oxidation (p < 0.001), and NTx (p < 0.001). These decreases in lipid peroxidation, protein oxidation, and NTx were significantly different from the corresponding changes resulting from placebo supplementation (p < 0.05, p < 0.005, and p < 0.02, respectively).

CONCLUSIONS

Our findings suggest that the antioxidant lycopene is beneficial in reducing oxidative stress parameters and the bone resorption marker NTx.

Osteoclastogenic activity and RANKL expression are inhibited in osteoblastic cells expressing constitutively active Gα(12) or constitutively active RhoA

Gα(12)-RhoA signaling is a parathyroid hormone (PTH)-stimulated pathway that mediates effects in bone and may influence genetic susceptibility to osteoporosis. To further elucidate effects of the pathway in osteoblasts, UMR-106 osteoblastic cells were stably transfected with constitutively active (ca) Gα(12) or caRhoA or dominant negative (dn) RhoA and co-cultured with RAW 264.7 cells to determine effects on hormone-stimulated osteoclastogenesis. Whereas PTH and calcitriol-stimulated osteoclastogenesis in co-cultures with UMR-106 cells expressing pcDNA or dominant negative RhoA, the osteoclastogenic effects of PTH and calcitriol were significantly attenuated when the UMR-106 cells expressed either caRhoA or caGα(12). These inhibitory effects were partially reversed by the Rho kinase inhibitor Y27632. None of the constructs affected osteoclastogenesis in untreated co-cultures, and the constructs did not inhibit the osteoclastogenic responses to receptor activator of NFκB ligand (RANKL). To investigate the mechanism of the inhibitory effects of caGα(12) and caRhoA, expression of RANKL, osteoprotegerin (OPG), osteopontin (OPN), and intercellular adhesion molecule-1 (ICAM) in response to PTH or calcitriol was examined in the UMR-106 cells. In the cells expressing pcDNA or dnRhoA, PTH and calcitriol increased RANKL mRNA and decreased OPG mRNA, whereas these effects were absent in the cells expressing caGα(12) or caRhoA. Basal expression of RANKL and OPG was unaffected by the constructs. The results suggest that Gα(12)-RhoA signaling can inhibit hormone-stimulated osteoclastogenesis by effects on expression of RANKL and OPG. Since PTH can stimulate the Gα(12)-RhoA pathway, the current findings could represent a homeostatic mechanism for regulating osteoclastogenic action.

Carotenoids, retinol, and intestinal barrier function in children from northeastern Brazil

OBJECTIVES

To investigate the association of carotenoids and retinol (vitamin A) with intestinal barrier function in children in an urban community in Fortaleza, northeastern Brazil.

METHODS

Descriptive analysis of serum carotenoids and retinol concentrations with intestinal barrier function in 102 children from an urban community, July 2000 to August 2001.

RESULTS

The weight for height z score (wasting) showed that 19.6% (20/102) had mild malnutrition (-1 to -2 z score). All of the children's serum retinol concentrations were determined and none were severely deficient (< or =0.35 micromol/L), 2.9% (3/102) were moderately (0.36-0.70 micromol/L) deficient, 20.6% (21/102) were mildly (0.71-1.05 micromol/L) deficient; 76.5% (78/102) were vitamin A sufficient (>1.05 micromol/L). The lactulose:mannitol (L/M) ratio was elevated (> or =0.0864) in 49% (47/97) of children when compared with healthy children with normal L/M ratio (<0.0864) in the same geographic area. Serum carotenoids, lutein, beta-cryptoxanthin and beta-carotene showed significant inverse correlations with the L/M ratio, but not lutein after adjusting for age. Acute phase proteins (C-reactive protein and alpha-acid glycoprotein) were significantly inversely correlated with retinol but not with carotenoids. Retinol and retinol-binding protein were not significantly associated with L/M ratio.

CONCLUSIONS

These data suggest a disruption of intestinal barrier function in the paracellular pathway with low serum concentrations of carotenoids. Carotenoids may provide a better marker for disrupted intestinal barrier function than retinol-binding protein or retinol.

Lycopene in cancer prevention and treatment

Dietary intake of lycopene is inversely associated with the risk of many cancers. Preclinical studies show that lycopene has potent in vitro and in vivo antitumor effects, suggesting potential preventive and therapeutic roles for the compound. However, clinical trials with lycopene have only recently been started, and available clinical data preclude firm conclusions with regard to its use in cancer prevention and treatment. Further mechanistic studies and randomized controlled clinical intervention trials with lycopene involving cancer patients are warranted.

Unravelling the molecular control of calvarial suture fusion in children with craniosynostosis

BACKGROUND

Craniosynostosis, the premature fusion of calvarial sutures, is a common craniofacial abnormality. Causative mutations in more than 10 genes have been identified, involving fibroblast growth factor, transforming growth factor beta, and Eph/ephrin signalling pathways. Mutations affect each human calvarial suture (coronal, sagittal, metopic, and lambdoid) differently, suggesting different gene expression patterns exist in each human suture. To better understand the molecular control of human suture morphogenesis we used microarray analysis to identify genes differentially expressed during suture fusion in children with craniosynostosis. Expression differences were also analysed between each unfused suture type, between sutures from syndromic and non-syndromic craniosynostosis patients, and between unfused sutures from individuals with and without craniosynostosis.

RESULTS

We identified genes with increased expression in unfused sutures compared to fusing/fused sutures that may be pivotal to the maintenance of suture patency or in controlling early osteoblast differentiation (i.e. RBP4, GPC3, C1QTNF3, IL11RA, PTN, POSTN). In addition, we have identified genes with increased expression in fusing/fused suture tissue that we suggest could have a role in premature suture fusion (i.e. WIF1, ANXA3, CYFIP2). Proteins of two of these genes, glypican 3 and retinol binding protein 4, were investigated by immunohistochemistry and localised to the suture mesenchyme and osteogenic fronts of developing human calvaria, respectively, suggesting novel roles for these proteins in the maintenance of suture patency or in controlling early osteoblast differentiation. We show that there is limited difference in whole genome expression between sutures isolated from patients with syndromic and non-syndromic craniosynostosis and confirmed this by quantitative RT-PCR. Furthermore, distinct expression profiles for each unfused suture type were noted, with the metopic suture being most disparate. Finally, although calvarial bones are generally thought to grow without a cartilage precursor, we show histologically and by identification of cartilage-specific gene expression that cartilage may be involved in the morphogenesis of lambdoid and posterior sagittal sutures.

CONCLUSION

This study has provided further insight into the complex signalling network which controls human calvarial suture morphogenesis and craniosynostosis. Identified genes are candidates for targeted therapeutic development and to screen for craniosynostosis-causing mutations.

Lycopene consumption decreases oxidative stress and bone resorption markers in postmenopausal women

INTRODUCTION

Oxidative stress induced by reactive oxygen species (ROS) is associated with the risk of osteoporosis, and can be reduced by certain dietary antioxidants. Lycopene is an antioxidant known to decrease the risk of age-related chronic diseases, such as cancer. However, the role of lycopene in osteoporosis has not yet been investigated.

MATERIALS AND METHODS

In a cross-sectional study, 33 postmenopausal women aged 50-60 years provided seven-day dietary records and blood samples. Serum samples were used to measure serum lycopene, lipid peroxidation, protein thiols, bone alkaline phosphatase (BAP), and cross-linked N-telopeptides of type I collagen (NTx). The serum lycopene per kilogram body weight of the participants was grouped into quartiles and associated with the above serum parameters using one-way ANOVA and the Newman-Keuls post-test.

RESULTS

The results showed that groups with higher lycopene intake, as determined from the dietary records, had higher serum lycopene (p<0.02). A higher serum lycopene was found to be associated with a low NTx (p<0.005). Similarly, groups with higher serum lycopene had lower protein oxidation (p<0.05).

DISCUSSION

In conclusion, these results suggest that the dietary antioxidant lycopene reduces oxidative stress and the levels of bone turnover markers in postmenopausal women, and may be beneficial in reducing the risk of osteoporosis.

Lycopene and soy isoflavones in the treatment of prostate cancer

Dietary intake of lycopene and soy has been associated with a lower risk of prostate cancer. In vitro studies with lycopene and genistein, a soy isoflavone, have shown induction of apoptosis and inhibition of cell growth in androgen-sensitive (LNCaP) and androgen-independent (PC3 and VeCaP) prostate cancer cell lines. In a previous Phase II clinical trial in prostate cancer patients, we observed prostate-specific antigen (PSA) stabilization with soy isoflavone intake. In this Phase II clinical trial, we investigated the efficacy of lycopene alone or in combination with soy isoflavones on serum PSA levels in men with prostate cancer. To be eligible for the study, men with prostate cancer had to have rising serum PSA following local therapy or while on hormone therapy. Study population included 71 eligible patients who had 3 successive rising PSA levels or a minimum PSA of 10 ng/ml at 2 successive evaluations prior to starting therapy. Subjects were randomly assigned to receive a tomato extract capsule containing 15 mg of lycopene alone (n = 38) or together with a capsule containing 40 mg of a soy isoflavone mixture (n = 33) twice daily orally for a maximum of 6 mo. One patient on the lycopene arm did not receive therapy due to his inability to ingest the study pill. There was no decline in serum PSA in either group qualifying for a partial or complete response. However, 35 of 37 (95%) evaluable patients in the lycopene group and 22 of 33 (67%) evaluable patients in the lycopene plus soy isoflavone group achieved stable disease described as stabilization in serum PSA level. The data suggest that lycopene and soy isoflavones have activity in prostate cancer patients with PSA relapse disease and may delay progression of both hormone-refractory and hormone-sensitive prostate cancer. However, there may not be an additive effect between the 2 compounds when taken together. Future studies are warranted to further investigate the efficacy of lycopene and soy isoflavones in prostate cancer as well as the mechanism of potential negative interaction between them.

Regulatory mechanism of food factors in bone metabolism and prevention of osteoporosis

Aging induces a decrease in bone mass, and osteoporosis with its accompanying decrease in bone mass is widely recognized as a major public health problem. Bone loss with increasing age may be due to decreased bone formation and increased bone resorption. Pharmacologic and nutritional factors may prevent bone loss with aging, although chemical compounds in food and plants which act on bone metabolism are poorly understood. We have found that isoflavones (including genistein and daidzein), which are contained in soybeans, have a stimulatory effect on osteoblastic bone formation and an inhibitory effect on osteoclastic bone resorption, thereby increasing bone mass. Menaquinone-7, an analogue of vitamin K(2) which is abundant in fermented soybeans, has been demonstrated to stimulate osteoblastic bone formation and to inhibit osteoclastic bone resorption. Of various carotenoids, beta-cryptoxanthin, which is abundant in Satsuma mandarin (Citrus unchiu MARC), has a stimulatory effect on osteoblastic bone formation and an inhibitory effect on osteoclastic bone resorption. The supplementation of these factors has a preventive effect on bone loss induced by ovariectomy in rats, which are an animal model of osteoporosis, and their intake has been shown to have a stimulatory effect on bone mass in humans. Factors with an anabolic effect on bone metabolism were found in extracts obtained from wasabi leafstalk (Wasabi japonica MATSUM), the marine alga Sargassum horneri, and bee pollen Cistus ladaniferus. Phytocomponent p-hydroxycinnamic acid was also found to have an anabolic effect on bone metabolism. Food chemical factors thus play a role in bone health and may be important in the prevention of bone loss with increasing age.

Deer antlers: a zoological curiosity or the key to understanding organ regeneration in mammals?

Many organisms are able to regenerate lost or damaged body parts that are structural and functional replicates of the original. Eventually these become fully integrated into pre-existing tissues. However, with the exception of deer, mammals have lost this ability. Each spring deer shed antlers that were used for fighting and display during the previous mating season. Their loss is triggered by a fall in circulating testosterone levels, a hormonal change that is linked to an increase in day length. A complex 'blastema-like' structure or 'antler-bud' then forms; however, unlike the regenerative process in the newt, most evidence (albeit indirect) suggests that this does not involve reversal of the differentiated state but is stem cell based. The subsequent re-growth of antlers during the spring and summer months is spectacular and represents one of the fastest rates of organogenesis in the animal kingdom. Longitudinal growth involves endochondral ossification in the tip of each antler branch and bone growth around the antler shaft is by intramembranous ossification. As androgen concentrations rise in late summer, longitudinal growth stops, the skin (velvet) covering the antler is lost and antlers are 'polished' in preparation for the mating season. Although the timing of the antler growth cycle is clearly closely linked to circulating testosterone, oestrogen may be a key cellular regulator, as it is in the skeleton of other male mammals. We still know very little about the molecular machinery required for antler regeneration, although there is evidence that developmental signalling pathways with pleiotropic functions are important and that novel 'antler-specific' molecules may not exist. Identifying these pathways and factors, deciphering their interactions and how they are regulated by environmental cues could have an important impact on human health if this knowledge is applied to the engineering of new human tissues and organs.

Lycopene

Oxidative stress is now recognized as an important etiological factor in the causation of several chronic diseases including cancer, cardiovascular diseases, osteoporosis, and diabetes. Antioxidants play an important role in mitigating the damaging effects of oxidative stress on cells. Lycopene, a carotenoid antioxidant, has received considerable scientific interest in recent years. Epidemiological, tissue culture, and animal studies provide convincing evidence supporting the role of lycopene in the prevention of chronic diseases. Human intervention studies are now being conducted to validate epidemiological observations and to understand the mechanisms of action of lycopene in disease prevention. To obtain a better understanding of the role of lycopene in human health, this chapter reviews the most recent information pertaining to its chemistry, bioavailability, metabolism, role in the prevention of prostate cancer and cancer of other target organs, its role in cardiovascular diseases, osteoporosis, hypertension, and male infertility. A discussion of the most relevant molecular markers of cancer is also included as a guide to future researchers in this area. The chapter concludes by reviewing global intake levels of lycopene, suggested levels of intake, and future research directions.

beta-cryptoxanthin stimulates cell differentiation and mineralization in osteoblastic MC3T3-E1 cells

The effect of beta-cryptoxanthin, a kind of carotenoid, on cell differentiation and mineralization in osteoblastic MC3T3-E1 cells was investigated. Cells were cultured for 72 h in a minimum essential medium containing 10% fetal bovine serum (FBS), and the cells with subconfluency were changed to a medium containing either vehicle or beta-cryptoxanthin (10(-8) to 10(-6) M) without FBS. Cells were cultured for 3 to 21 days. Gene expression in osteoblastic cells was determined using reverse transcription-polymerase chain reaction (RT-PCR). Culture with beta-cryptoxanthin (10(-7) or 10(-6) M) for 3 days caused a significant increase in Runx2 type 1, Runx2 type 2, alpha1 (I) collagen, and alkaline phosphatase mRNA levels in osteoblastic cells. These increases were completely blocked in the presence of cycloheximide, an inhibitor of protein synthesis, or 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), an inhibitor of transcriptional activity. Meanwhile, vitamin A (10(-6) M) did not have a significant effect on Runx2 type 1 mRNA expression in the cells. The effect of beta-cryptoxanthin (10(-6) M) in stimulating Runx2 type 1 and alpha1 (I) collagen mRNA levels, protein content, and alkaline phosphatase activity in the cells was also seen in the presence of vitamin A (10(-6) M), suggesting that the mode of beta-cryptoxanthin action differs from that of vitamin A. Prolonged culture with beta-cryptoxanthin (10(-6) M) for 3 to 21 days caused a significant increase in cell number, deoxyribonucleic acid (DNA) content, protein content, and alkaline phosphatase activity in osteoblastic cells, suggesting that beta-cryptoxanthin stimulates cell proliferation and differentiation. Moreover, culture with beta-cryptoxanthin (10(-7) or 10(-6) M) for 5 to 21 days caused a remarkable increase in mineralization. This study demonstrates that beta-cryptoxanthin has a stimulatory effect on cell differentiation and mineralization due to enhancing gene expression of proteins, which involve in bone formation in osteoblastic MC3T3-E1 cells.

Retinoid-induced bone thinning is caused by subperiosteal osteoclast activity in adult rodents

Excess of Vitamin A (retinol) and related compounds (retinoids) induces bone fragility and is associated with increased hip fracture incidence in humans. Yet, their impact on the adult skeleton has been studied in relatively little detail. It is assumed that they induce generalized bone loss and decrease long-bone thickness due to reduction of radial bone growth. Here we characterized early skeletal responses of adult rodents to retinoid treatment, revealing novel aspects of retinoid action on the mature skeleton. The retinoid Ro 13-6298, given subcutaneously for 4 days, induced bone loss in the hind limbs of 12- and 56-week-old rats and of 15-week-old mice. In vivo monitoring of bone mass and geometry changes by peripheral quantitative computed tomography demonstrated that bone mass decline was due to subperiosteal cortical bone loss, which induced a shrinkage of bone diameter, whilst cancellous bone mass was preserved. We observed that the native retinoic acid isomer all-trans RA induced an identical pattern of bone loss. Histomorphometric evaluation revealed that increased subperiosteal osteoclastic bone resorption caused the cortical bone destruction. Interestingly, bone resorption was suppressed in cancellous bone, which was in agreement with reduced in vitro formation of osteoclasts from bone marrow cells that were derived from the proximity of cancellous bone. The retinoid-induced increase in subperiosteal bone resorption could be blocked by bisphosphonate as direct potent inhibitor of osteoclast action, but not by estradiol. Retinoid treatment induced a reduction of bone-forming surfaces at the subperiosteal site, but not in cancellous bone. In vitro osteoblast performance was also reduced or unchanged, depending on the cellular system used and assay type/duration. In conclusion, our studies revealed that the impact of retinoids on bone is highly bone-compartment-specific at early treatment phases. Furthermore, we showed that bone diameter shrinks in the adult skeleton after retinoid treatment due to subperiosteal osteoclastic bone resorption. Thus, retinoid-induced bone thinning is not only due to reduced radial bone growth as previously assumed. Our findings might explain why high intake of retinol is associated with increased hip fracture risk in the elderly and suggest a therapy to prevent such potential negative effects.

PHENYTOIN STIMULATES CHONDROGENIC DIFFERENTIATION IN MOUSE CLONAL CHONDROGENIC EC CELLS, ATDC5

Phenytoin (DPH) is known to affect bone formation. However, the mechanism of this effect has not been well understood. In this study, we evaluated the effects of DPH on cartilage formation in a model system using ATDC5 cells, a clonal murine chondrogenic cell line. Alcian blue staining for cartilage nodules and real-time reverse-transcription polymerase chain reaction for the expression of genes encoding type II collagen, aggrecan, transforming growth factor (TGF)-beta1, bone morphogenetic protein (BMP)-4, parathyroid hormone-related peptide (PTHrP), indian hedgehog (Ihh), and patched (Ptc) were performed in ATDC5 cells cultured with DPH. The ATDC5 cells demonstrated enhanced cartilage formation in cultures with DPH. During promoted chondrogenic differentiation, it was observed that DPH increased the mRNA expression of TGF-beta1, BMP-4, Ihh, and Ptc, in a dose-dependent manner on Days 5 to 15. In contrast, other antiepileptic drugs, phenobarbital and valproic acid had no effects on chondrogenesis in ATDC5 cells and osteogenesis in MC3T3-E1 cells. Our results provide fundamental evidence that DPH has a direct stimulatory effect on cartilage formation by regulating TGF-beta and hedgehog signaling molecules, and that DPH effect on bone formation, including chondrogenesis and osteogenesis, is distinct from other antiepileptic drugs as suggested in clinical settings.

Vitamin A exerts its activity at the transcriptional level in the small intestine

THE AIM OF THIS STUDY

was to examine the effects of vitamin-A deficiency on the small intestinal morphology and on brush-border enzyme function and expression.

METHODS

Weanling male rats were fed a vitamin-A deficient (VAD), sufficient (VAS), or supplemented (VASUP) diet, or were pair-fed (PF) with the VAD rats. Average food intakes were not different among the groups.

RESULTS

From days 35 to 42, the body weight of VAD rats began to plateau, whereas the other groups, including the PF rats, continued to gain weight. At days 48 to 51, the final mean body weight of VAD rats was significantly lower than that of PF, VAS and VASUP rats (P < 0.05). Serum and liver retinol levels were lower in VAD rats (by 85 % and 99%, respectively) and higher in the VASUP group (by 126 % and 160%, respectively) compared to the VAS group (P < 0.01). Histological examination of the jejunum revealed that in VAD rats the villi were shorter and thicker and there was an elevation in crypt depth relative to the other treatment groups. Infiltration of inflammatory cells was also observed in the jejunum of most of the VAD rats, but not in rats from other groups. Biochemical assays revealed that in VAD rats, alkaline phosphatase (ALP) and sucrase-isomaltase (SI) activities are significantly decreased in the jejunum, compared to PF, VAS and VASUP groups (P < 0.01). ALP activity was decreased in the duodenum of VAD rats as well. By comparison, amino-peptidase (AP) activity per mg protein in the jejunum and ileum of VAD rats was significantly increased compared to VAS and VASUP rats (P < 0.01), but was not different from PF rats. In all of the small intestinal sections, mRNA expression of all three brush-border enzymes relative to beta-actin were significantly lower in VAD rats than in the other treatment groups. SI was similarly expressed in all of the small intestinal organs, whereas AP and ALP expression varied.

CONCLUSIONS

Our results suggest that vitamin-A deficiency modifies the maturation and differentiation processes of the small intestinal mucosa at the transcriptional and post-transcriptional levels respectively. This in turn may be one explanation for the alteration or elimination of nutrient digestion and absorption during VAD.