Ethanol impairs estrogen receptor signaling resulting in accelerated activation of senescence pathways, whereas estradiol attenuates the effects of ethanol in osteoblasts

The impact of ageing mechanisms on musculoskeletal system diseases in the elderly

Ageing is an inevitable process that affects various tissues and organs of the human body, leading to a series of physiological and pathological changes. Mechanisms such as telomere depletion, stem cell depletion, macrophage dysfunction, and cellular senescence gradually manifest in the body, significantly increasing the incidence of diseases in elderly individuals. These mechanisms interact with each other, profoundly impacting the quality of life of older adults. As the ageing population continues to grow, the burden on the public health system is expected to intensify. Globally, the prevalence of musculoskeletal system diseases in elderly individuals is increasing, resulting in reduced limb mobility and prolonged suffering. This review aims to elucidate the mechanisms of ageing and their interplay while exploring their impact on diseases such as osteoarthritis, osteoporosis, and sarcopenia. By delving into the mechanisms of ageing, further research can be conducted to prevent and mitigate its effects, with the ultimate goal of alleviating the suffering of elderly patients in the future.

Biological Effects of "Inflammageing" on Human Oral Cells: Insights into a Potential Confounder of Age-Related Diseases

OBJECTIVES

The term "inflammageing" describes the process of inflammation-induced aging that leads living cells to a state of permanent cell cycle arrest due to chronic antigenic irritation. This in vitro study aimed to shed light on the mechanisms of "inflammageing" on human oral cells.

METHODS

Primary cultures of human gingival fibroblasts (hGFs) were exposed to variable pro-inflammatory stimuli, including lipopolysaccharide (LPS), Tumor Necrosis Factor-alpha (TNFa), and gingival crevicular fluid (GCF) collected from active periodontal pockets of systemically healthy patients. Inflammageing was studied through two experimental models, employing either late-passage ("aged") cells (p. 10) that were exposed to the pro-inflammatory stimuli or early-passage ("young") cells (p. 1) continuously exposed during a period of several passages (up to p. 10) to the above-mentioned stimuli. Cells were evaluated for the expression of beta-galactosidase activity (histochemical staining), senescence-associated genes (qPCR analysis), and biomarkers related to a Senescence-Associated Secretory Phenotype (SASP), through proteome profile analysis and bioinformatics.

RESULTS

A significant increase (p < 0.05) in beta-galactosidase-positive cells was observed after exposure to each pro-inflammatory stimulus. The senescence-associated gene expression included upregulation for CCND1 and downregulation for SUSD6, and STAG1, a profile typical for cellular senescence. Overall, pro-inflammatory priming of late-passage cells caused more pronounced effects in terms of senescence than long-term exposure of early-passage cells to these stimuli. Proteomic analysis showed induction of SASP, evidenced by upregulation of several pro-inflammatory proteins (IL-6, IL-10, IL-16, IP-10, MCP-1, MCP-2, M-CSF, MIP-1a, MIP-1b, TNFb, sTNF-RI, sTNF-RII, TIMP-2) implicated in cellular aging and immune responses. The least potent impact on the induction of SASP was provoked by LPS and the most pronounced by GCF.

CONCLUSION

This study demonstrates that long-term exposure of hGFs to various pro-inflammatory signals induced or accelerated cellular senescence with the most pronounced impact noted for the late-passage cells. The outcome of these analyses provides insights into oral chronic inflammation as a potential confounder of age-related diseases.

Colchicine Protects against Ethanol-Induced Senescence and Senescence-Associated Secretory Phenotype in Endothelial Cells

Inflammaging is a potential risk factor for cardiovascular diseases. It results in the development of thrombosis and atherosclerosis. The accumulation of senescent cells in vessels causes vascular inflammaging and contributes to plaque formation and rupture. In addition to being an acquired risk factor for cardiovascular diseases, ethanol can induce inflammation and senescence, both of which have been implicated in cardiovascular diseases. In the current study, we used colchicine to abate the cellular damaging effects of ethanol on endothelial cells. Colchicine prevented senescence and averted oxidative stress in endothelial cells exposed to ethanol. It lowered the relative protein expression of aging and senescence marker P21 and restored expression of the DNA repair proteins KU70/KU80. Colchicine inhibited the activation of nuclear factor kappa B (NFκ-B) and mitogen activated protein kinases (MAPKs) in ethanol-treated endothelial cells. It reduced ethanol-induced senescence-associated secretory phenotype. In summary, we show that colchicine ameliorated the ethanol-caused molecular events, resulting in attenuated senescence and senescence-associated secretory phenotype in endothelial cells.

Impact of Alcohol on Bone Health in People Living With HIV: Integrating Clinical Data From Serum Bone Markers With Morphometric Analysis in a Non-Human Primate Model

People living with HIV (PLWH) represent a vulnerable population to adverse musculoskeletal outcomes due to HIV infection, antiretroviral therapy (ART), and at-risk alcohol use. Developing measures to prevent skeletal degeneration in this group requires a grasp of the relationship between alcohol use and low bone mass in both the PLWH population and its constituents as defined by sex, age, and race. We examined the association of alcohol use with serum biochemical markers of bone health in a diverse cohort of PLWH enrolled in the New Orleans Alcohol Use in HIV (NOAH) study. To explore the effects of alcohol on bone in the context of HIV and ART and the role of estrogen, we conducted a parallel, translational study using simian immunodeficiency virus (SIV)+/ART+ female rhesus macaques divided into four groups: vehicle (Veh)/Sham; chronic binge alcohol (CBA)/Sham; Veh/ovariectomy (OVX); and CBA/OVX. Clinical data showed that both osteocalcin (Ocn) and procollagen type I N-propeptide (PINP) levels were inversely associated with multiple measures of alcohol consumption. Age (>50 years) significantly increased susceptibility to alcohol-associated suppression of bone formation in both female and male PLWH, with postmenopausal status appearing as an additional risk factor in females. Serum sclerostin (Scl) levels correlated positively with measures of alcohol use and negatively with Ocn. Micro-CT analysis of the macaque tibias revealed that although both CBA and OVX independently decreased trabecular number and bone mineral density, only OVX decreased trabecular bone volume fraction and impacted cortical geometry. The clinical data implicate circulating Scl in the pathogenesis of alcohol-induced osteopenia and suggest that bone morphology can be significantly altered in the absence of net change in osteoblast function as measured by serum markers. Inclusion of sophisticated tools to evaluate skeletal strength in clinical populations will be essential to understand the impact of alcohol-induced changes in bone microarchitecture. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

GPR109A gene deletion ameliorates gonadectomy-induced bone loss in mice

Sex steroid deficiency plays critical roles in the pathophysiology of bone as the result of uncertain bone remodeling, i.e., increased bone resorption with equivocal bone formation. We have previously shown that GPR109A, a G protein coupled receptor, controls osteoclastogenesis and bone resorption, where global GPR109A deletion decreased osteoclast bone resorption and increased bone mass. Here, we used global GPR109A gene deletion, ovariectomized (OVX) and orchidectomized (ORX) mouse models to probe the role of GPR109A in gonadectomy-induced bone loss in female and male mice. Six months old GPR109A^-/- mice and their wild type littermates were allocated to Sham or gonadectomized groups for six weeks. Using densitometric micro-CT confirmed by peripheral quantitative CT (pQCT) scans on tibia and spine, and three-point bending test on femur ex vivo, we found the bone volume, trabecular number, as well as bone mineral density and content in both trabecular and cortical sites were significantly decreased in wild type OVX and ORX compared with respective Sham groups. While bone mass in both male and female GPR109A^-/- Sham groups were significantly higher compared with their respective wild type Sham groups, global GPR109A gene deletion ameliorated gonadectomy-induced bone loss. In GPR109A^-/- females, most of bone mass and strength parameters measured by micro-CT, pQCT and three-point bending test were not different between Sham and OVX groups. In wild type but not in GPR109^-/- mice, bone remodeling marker measurements indicated that both bone resorption (Cathepsin K) and bone formation (osteocalcin) markers were increased in gonadectomized mice compared to sham, with the exception of bone specific ALP, which was decreased in gonadectomized mice. Expression of bone resorption markers (Cathepsin K) were significantly lower, but β-catenin expression was higher in GPR109A^-/- mice compared with their wild type littermates. Collectively, these data indicate that global GPR109A deletion ameliorates gonadectomy-induced bone loss through suppression of bone resorption.

Nox4 expression in osteo-progenitors controls bone development in mice during early life

Tightly regulated and cell-specific NADPH-oxidases (Nox) represent one of the major sources of reactive oxygen species (ROS) signaling molecules that are involved in tissue development and stem cell self-renewal. We have characterized the role of Nox4 in osteo-progenitors during postnatal bone development. Nox4 expression in bone and ROS generation were increased during early osteoblast differentiation and bone development. Stromal osteoblastic cell self-renewal, proliferation and ROS production were significantly lower in samples from whole-body Nox4 knockout mice (Nox4^-/-) and conditional knockout (CKO) mice with depletion of Nox4 in the limb bud mesenchyme compared with those from control mice (Nox4^fl/fl), but they were reversed after 9 passages. In both sexes, bone volume, trabecular number and bone mineral density were significantly lower in 3-week old CKO and Nox4^-/- mice compared with Nox4^fl/fl controls. This was reflected in serum levels of bone formation markers alkaline phosphatase (ALP) and procollagen 1 intact N-terminal propeptide (P1NP). However, under-developed bone formation in 3-week old CKO and Nox4^-/- mice quickly caught up to levels of control mice by 6-week of age, remained no different at 13-week of age, and was reversed in 32-week old male mice. Osteoclastogenesis showed no differences among groups, however, CTX1 reflecting osteoclast activity was significantly higher in 3-week old male CKO and Nox4^-/- mice compared with control mice, and significantly lower in 32-week old Nox4^-/- mice compared with control mice. These data suggest that Nox4 expression and ROS signaling in bone and osteoblastic cells coordinately play an important role in osteoblast differentiation, proliferation and maturation.

Episodic alcohol exposure attenuates mesenchymal stem cell chondrogenic differentiation during bone fracture callus formation

BACKGROUND

During bone fracture repair, mesenchymal stem cells (MSC) differentiate into chondrocytes and osteoblasts to form a fracture callus. Our laboratory previously reported that alcohol-exposed rodents with a surgically created tibia fracture display deficient fracture callus formation and diminished signs of endochondral ossification characterized by the absence of chondrocytes and mature hypertrophic chondrocytes, suggesting that alcohol may inhibit MSC differentiation. These findings led to our hypothesis that alcohol exposure inhibits mesenchymal stem cell chondrogenic differentiation within the developing fracture callus.

METHODS

In the present study, we utilized a lineage-tracing approach to determine which stage(s) of chondrogenic differentiation are affected by alcohol exposure. We utilized lineage-specific reporter mice to determine the effects of alcohol on MSC and early and late chondrogenic cell frequencies within the fracture callus. In addition, serially sectioned slides were stained immunofluorescently and immunohistochemically and quantified to determine the effect of alcohol on cell proliferation and apoptosis, respectively, within the fracture callus of alcohol-administered rodents.

RESULTS

Alcohol-administered rodents had a reduced fracture callus area at 4, 6, and 9 days postfracture. Alcohol had no effect on apoptosis in the fracture callus at any of the examined timepoints. Alcohol-administered rodents had significantly fewer proliferative cells in the fracture callus at 9 days postfracture, but no effect on cell proliferation was observed at earlier fracture callus timepoints. Alcohol-administered rodents had reduced Collagen2a1- and Collagen10a1-expressing cells in the developing fracture callus, suggesting that alcohol inhibits both early chondrogenic differentiation and later chondrocyte maturation during fracture callus development.

CONCLUSION

The data suggest that alcohol could affect normal fracture healing through the mitigation of MSC chondrogenic differentiation at the callus site.

Effect of ethanol consumption during pregnancy and lactation on bone histomorphometry and in vitro osteogenic differentiation of bone marrow mesenchymal stem cells in maternal rats

This study aimed to evaluate the effect of maternal ethanol consumption during gestation and lactation on bone mass and osteogenic differentiation of mesenchymal stem cells of the bone marrow (BMMSCs) in rats. Thirteen adult Wistar rats were used. The rats were mated, and after confirmation of gestation, (day 0) they were distributed in two groups: the control group and the ethanol-treated group. From the ninth day of gestation, the rats of the ethanol and control groups were administered 40% alcoholic solution (4 g ethanol/kg) and distilled water, respectively, daily via gavage until the thirtieth day of lactation. The BMMSCs were extracted from the right femurs and tibiae and cultured using an osteogenic medium for 7, 14, and 21 days. The conversion of MTT to formazan crystals, alkaline phosphatase activity, and percentages of cells per field were analyzed. The number of mineralized nodules per field was examined, and quantification of the gene transcripts for osteopontin, osteocalcin, and BMP-2 was evaluated on day 21 by real-time RT-PCR. Morphometric evaluations of the percentage of trabecular bone and cortical thickness in the left femur and tibia were performed. The means were compared by the Student's t-test, and the differences were considered significant if p < 0.05. The BMMSCs of the rats that consumed ethanol during gestation and lactation, when subjected to osteogenic differentiation in vitro, demonstrated higher conversion of MTT to formazan, higher alkaline phosphatase activity, a higher percentage of cells per field, higher expression of BMP-2, and higher synthesis of mineralized nodules when compared to those of control rat cells. However, there was no significant difference in the percentage of trabecular bone or cortical thickness between both groups. Hence, the consumption of ethanol during pregnancy and lactation did not alter the trabecular and cortical bone tissues of the femur and tibia compared with that of pregnant and lactating control rats that did not consume alcohol, despite BMMSCs showing higher osteogenic differentiation under in vitro conditions.

Estrogen prevents cellular senescence and bone loss through Usp10-dependent p53 degradation in osteocytes and osteoblasts: the role of estrogen in bone cell senescence

Estrogens play multiple roles in maintaining skeletal homeostasis by regulating many physiological processes in bone cells. Recently, cellular senescence in bone cells, especially in osteocytes, has been demonstrated to be a pivotal factor in bone loss. However, whether and how estrogen mediates cellular senescence in bone cells remains unknown. Here, we show that estrogen is negatively correlated with p53-related cellular senescence, primarily through the regulation of p53 protein levels, both in vivo and in vitro. Further study confirmed that estrogen attenuated the nuclear import of p53 and accelerated p53 degradation in osteocyte-like MLO-Y4 cells and osteoblastic MC3T3-E1 cells. A screen of p53-related ubiquitinating/deubiquitinating enzymes indicated that estrogen induced the degradation of p53 through the regulation of Usp10, a deubiquitinase that is directly linked to p53. Usp10 inhibition attenuated H₂O₂-induced senescence in MLO-Y4 cells, as indicated by p53/p21 quantification, a senescence-associated β-galactosidase (SA-β-gal) assay, and p53 localization visualization with a confocal microscope. Usp10 overexpression abolished the estrogen-mediated regulation of p53 and the downstream transcriptional gene p21. The injection of ovariectomized (OVX) mice with Spautin-1, a Usp10 inhibitor, inhibited the expression of p53 and the transcription of downstream senescence markers, as well as promoted bone mass recovery. Taken together, our study unveils the regulatory function of estrogen in the prevention of cellular senescence through the regulation of Usp10, thereby accelerating the degradation of senescent factor p53 and inhibiting its nuclear import.

Exploration of several plants from Baung Forest on bone formation cell models

OBJECTIVES

Osteoporosis is an ailment described by a skeletal degradation of bone skeletal dominating to increases the chance of fracture. In order to find out the bone formation agents from Baung Forest plants, this research analyzed the effects of 96% ethanol extract of several plants from Baung Forest on antioxidant activity and the effect of osteoblast differentiation-related to the bone formation on the most potent extract.

METHODS

The antioxidant effect and osteoblast differentiation of 96% ethanol extracts were evaluated by measuring DPPH scavenging and alkaline phosphatase in p-nitrophenyl phosphate effects by the enzyme-linked immunosorbent assay (ELISA) reader method, respectively.

RESULTS

The 96% ethanol extract of Elaeocarpus serratus L. from Baung Forest had the strongest DPPH radical scavenging as anti oxidant (82.17%) and stimulated osteoblast differentiation (116%). Then, this extract had been fractionated based on polarity to become hexane, ethyl acetate, butanol, and aqueous fractions. All the fractions stimulated their alkaline phosphatase (ALP) activity to 138.11 ± 9.72%, 108 ± 5.05%, 148.56 ± 8.47, and 144.58 ± 1.04, respectively.

CONCLUSIONS

The extract and fractions of E. serratus L. can successfully inhibit DPPH radical scavenging value and increase ALP activities as markers of osteoblast functions.

Effects of graded increases in ethanol consumption on biochemical markers of bone turnover in young adult male cynomolgus macaques

Chronic heavy alcohol use is often associated with reduced bone mineral density and altered bone turnover. However, the dose response effects of ethanol on bone turnover have not been established. This study examined the effects of graded increases of ethanol consumption on biochemical markers of bone turnover in young adult male cynomolgus macaques (Macaca fascicularis). For this study, 6.6-year-old (95% CI: 6.5, 6.7) male macaques were subjected to three 30-day sessions of increased ethanol intake over a 90-day interval. During the first 30 days, the monkeys drank a predetermined volume of ethanol corresponding to 0.5 g/kg/day, followed by 1.0 g/kg/day and 1.5 g/kg/day. Osteocalcin, a marker of bone formation, and carboxyterminal cross-linking telopeptide of type 1 collagen (CTX), a marker of resorption, were measured during each 30-day session. In addition, the ratio of osteocalcin to CTX was determined as a surrogate measure of global turnover balance. Mean osteocalcin decreased by 2.6 ng/mL (1.8, 3.5) for each one-half unit (0.5 g/kg/day) increase in dose (p < 0.001). Mean CTX decreased by 0.13 ng/mL (0.06, 0.20) for each one-half unit increase in dose (p < 0.001). Furthermore, there was an inverse relationship between dose and the ratio of osteocalcin to CTX, such that the mean ratio decreased by 0.9 (0.3, 1.5) for each one-half unit increase in dose (p = 0.01). In summary, male cynomolgus macaques had decreased blood osteocalcin and CTX, and osteocalcin to CTX ratio during the 90-day interval of graded increases in ethanol consumption, indicative of reduced bone turnover and negative turnover balance, respectively. These findings suggest that over the range ingested, ethanol resulted in a linear decrease in bone turnover. Furthermore, the negative bone turnover balance observed is consistent with reported effects of chronic alcohol intake on the skeleton.

Effects of Chronic Ethanol Consumption and Ovariectomy on the Spontaneous Alveolar Bone Loss in Rats

Postmenopausal estrogen deficiency and ethanol (EtOH) abuse are known risk factors for different diseases including bone tissues. However, little is known about the synergic effects of EtOH abuse and estrogen deficiency on alveolar bone loss in women. The present study evaluated the effects of EtOH chronic exposure and ovariectomy on the alveolar bone loss in female rats. For this, 40 female Wistar rats were randomly divided into 4 groups: control, EtOH exposure, ovariectomy (OVX), and OVX plus EtOH exposure. Initially, half of the animals were ovariectomized at 75 days of age. After that, the groups received distilled water or EtOH 6.5 g/kg/day (20% w/v) for 55 days via gavage. Thereafter, animals were sacrificed and the mandibles were collected, dissected, and separated into hemimandibles. Alveolar bone loss was evaluated by measuring the distance between the cementoenamel junction and the alveolar bone crest through a stereomicroscope in 3 different anatomical regions of the tissue. One-way ANOVA and post hoc Tukey were used to compare groups (p < 0.05). The results showed that the ovariectomy and EtOH exposure per se were able to induce alveolar bone loss, and their association did intensify significantly the effect. Therefore, OVX associated with heavy EtOH exposure increase the spontaneous alveolar bone loss in rats.

Nox4 Expression Is Not Required for OVX-Induced Osteoblast Senescence and Bone Loss in Mice

Estrogen deficiency and aging play critical roles in the pathophysiology of bone as a result of increased oxidative stress. It has been suggested that prevention of NADPH oxidase- (Nox-) dependent accumulation of ROS may be an approach to potentially minimize bone loss caused by these conditions. Using ovariectomized (OVX) and Nox4 gene-deletion mouse models, we investigated the role of Nox4 in OVX-induced bone loss and osteoblast senescence signaling. Six-month-old WT C57Bl6 mice were allocated to a sham control group, OVX, and OVX plus E2 treatment group for 8 weeks. Decreased bone mass including BMD and BMC were found in the OVX group compared with the sham control (p < 0.05); E2 treatment completely reversed OVX-induced bone loss. Interestingly, the prevention of OVX-induced bone loss by E2 was associated with the elimination of increased senescence signaling in bone osteoblastic cells from the OVX group. E2 blunted OVX-induced p53 and p21 overexpression, but not p16 and Nox4 in bone. In addition, 8- and 11-month-old Nox4 KO female mice were OVX for 8 weeks. Significant bone loss and increased bone osteoblastic cell senescence signaling occurred not only in Nox4 KO OVX mice compared with sham-operated animals, but also in 11-month-old Nox4 KO sham mice compared with 8-month-old Nox4 KO sham mice (p < 0.05). These data suggest that Nox4-mediated ROS in bone osteoblastic cells may be dispensable for sex steroid deficiency-induced bone loss and senescence. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Impact of Alcohol on Bone Health, Homeostasis and Fracture repair

Purpose of review

Alcohol use continues to rise globally. We review the current literature on the effect of alcohol on bone health, homeostasis and fracture repair to highlight what has been learned in people and animal models of alcohol consumption.

Recent findings

Recently, forkhead box O (FoxO) has been found to be upregulated and activated in mesenchymal stem cells (MSC) exposed to alcohol. FoxO has also been found to modulate Wnt/β-catenin signaling, which is necessary for MSC differentiation. Recent evidence suggests alcohol activates FoxO signaling, which may be dysregulating Wnt/β-catenin signaling in MSCs cultured in alcohol.

Summary

This review highlights the negative health effects learned from people and chronic and episodic binge alcohol consumption animal models. Studies using chronic alcohol exposure or alcohol exposure then bone fracture repair model have explored several different cellular and molecular signaling pathways important for bone homeostasis and fracture repair, and offer potential for future experiments to explore additional signaling pathways that may be dysregulated by alcohol exposure.

Voluntary Chronic Heavy Alcohol Consumption in Male Rhesus Macaques Suppresses Cancellous Bone Formation and Increases Bone Marrow Adiposity

BACKGROUND

Chronic heavy alcohol consumption is an established risk factor for bone fracture, but comorbidities associated with alcohol intake may contribute to increased fracture rates in alcohol abusers. To address the specific effects of alcohol on bone, we used a nonhuman primate model and evaluated voluntary alcohol consumption on: (i) global markers of bone turnover in blood and (ii) cancellous bone mass, density, microarchitecture, turnover, and microdamage in lumbar vertebra.

METHODS

Following a 4-month induction period, 6-year-old male rhesus macaques (Macaca mulatta, n = 13) voluntarily self-administered water or ethanol (EtOH; 4% w/v) for 22 h/d, 7 d/wk, for a total of 12 months. Control animals (n = 9) consumed an isocaloric maltose-dextrin solution. Tetracycline hydrochloride was administered orally 17 and 3 days prior to sacrifice to label mineralizing bone surfaces. Global skeletal response to EtOH was evaluated by measuring plasma osteocalcin and carboxyterminal collagen cross-links (CTX). Local response was evaluated in lumbar vertebra using dual-energy X-ray absorptiometry, microcomputed tomography, static and dynamic histomorphometry, and histological assessment of microdamage.

RESULTS

Monkeys in the EtOH group consumed an average of 2.8 ± 0.2 (mean ± SE) g/kg/d of EtOH (30 ± 2% of total calories), resulting in an average blood EtOH concentration of 88.3 ± 8.8 mg/dl 7 hours after the session onset. Plasma CTX and osteocalcin tended to be lower in EtOH-consuming monkeys compared to controls. Significant differences in bone mineral density in lumbar vertebrae 1 to 4 were not detected with treatment. However, cancellous bone volume fraction (in cores biopsied from the central region of the third vertebral body) was lower in EtOH-consuming monkeys compared to controls. Furthermore, EtOH-consuming monkeys had lower osteoblast perimeter and mineralizing perimeter, no significant difference in osteoclast perimeter, and higher bone marrow adiposity than controls. No significant differences between groups were detected in microcrack density (2^nd lumbar vertebra).

CONCLUSIONS

Voluntary chronic heavy EtOH consumption reduces cancellous bone formation in lumbar vertebra by decreasing osteoblast-lined bone perimeter, a response associated with an increase in bone marrow adiposity.

Effects of Alcohol and Estrogen Receptor Blockade Using ICI 182,780 on Bone in Ovariectomized Rats

BACKGROUND

Estrogen signaling is essential for the sexual dimorphism of the skeleton, is required for normal bone remodeling balance in adults, and may influence the skeletal response to alcohol. High levels of alcohol consumption lower bone mass in ovary-intact but not ovariectomized (ovx) rats. However, the extremely rapid rate of bone loss immediately following ovx may obscure the effects of alcohol. We therefore determined (i) whether heavy alcohol consumption (35% caloric intake) influences bone in sexually mature ovx rats with established cancellous osteopenia and (ii) whether ICI 182,780 (ICI), a potent estrogen receptor signaling antagonist, alters the skeletal response to alcohol.

METHODS

Three weeks following ovx, rats were randomized into 5 groups, (i) baseline, (ii) control + vehicle, (iii) control + ICI, (iv) ethanol (EtOH) + vehicle, or (v) EtOH + ICI, and treated accordingly for 4 weeks. Dual-energy X-ray absorptiometry, microcomputed tomography, blood measurements of markers of bone turnover, and gene expression in femur and uterus were used to evaluate response to alcohol and ICI.

RESULTS

Rats consuming alcohol had lower bone mass and increased fat mass. Bone microarchitecture of the tibia and gene expression in femur were altered; specifically, there was reduced accrual of cortical bone, net loss of cancellous bone, and differential expression of 19/84 genes related to bone turnover. Furthermore, osteocalcin, a marker of bone turnover, was lower in alcohol-fed rats. ICI had no effect on weight gain, body composition, or cortical bone. ICI reduced cancellous bone loss and serum CTX-1, a biochemical marker of bone resorption; alcohol antagonized the latter 2 responses. Neither alcohol nor ICI affected uterine weight or gene expression.

CONCLUSIONS

Alcohol exaggerated bone loss in ovx rats in the presence or absence of estrogen receptor blockade with ICI. The negligible effect of alcohol on uterus and limited effects of ICI on bone in alcohol-fed ovx rats suggest that estrogen receptor signaling plays a limited role in the action of alcohol on bone in a rat model for chronic alcohol abuse.

Maternal obesity impairs skeletal development in adult offspring

Intrauterine or early postnatal high-fat diet (HFD) has substantial influences on adult offspring health; however, studies of HFD-induced maternal obesity on regulation of adult offspring bone formation are sparse. Here, we investigated the effects of HFD-induced maternal obesity on both fetal and adult offspring skeletal development. We found that HFD-induced maternal obesity significantly decreased fetal skeletal development, but enhanced fetal osteoblastic cell senescence signaling and significantly increased the expression of inflammatory factors of the senescence-associated secretory phenotype (SASP) in osteo-progenitors. It was found that p300/CBP activation led to H3K27 acetylation to increase the expression of senescence-related genes and PPARγ in embryonic mouse osteogenic calvarial cells from HFD obese dams. These results were recapitulated in human umbilical cord mesenchymal stem cells (UC MSCs) isolated from offspring of pregnant obese and lean mothers following delivery. Regardless of postnatal HFD challenge, adult offspring from HFD obese dams showed significantly suppressed bone formation. Such early involution of bone formation of adult offspring from HFD obese dams may at least in part due to histone acetylation, i.e., epigenetic regulation of genes involved in cell senescence signaling in pre-osteoblasts from prenatal development. These findings indicate fetal pre-osteoblastic cell senescence signaling is epigenetically regulated by maternal obesity to repress bone formation in adult offspring in rodents and suggest that at least some of these effects may also manifest in humans.

Alcohol Induces Cellular Senescence and Impairs Osteogenic Potential in Bone Marrow-Derived Mesenchymal Stem Cells

Aims

Chronic and excessive alcohol consumption is a high-risk factor for osteoporosis. Bone marrow-derived mesenchymal stem cells (BM-MSCs) play an important role in bone formation; however, they are vulnerable to ethanol (EtOH). The purpose of this research was to investigate whether EtOH could induce premature senescence in BM-MSCs and subsequently impair their osteogenic potential.

Methods

Human BM-MSCs were exposed to EtOH ranging from 10 to 250 mM. Senescence-associated β-galactosidase (SA-β-gal) activity, cell cycle distribution, cell proliferation and reactive oxygen species (ROS) were evaluated. Mineralization and osteoblast-specific gene expression were evaluated during osteogenesis in EtOH-treated BM-MSCs. To investigate the role of silent information regulator Type 1 (SIRT1) in EtOH-induced senescence, resveratrol (ResV) was used to activate SIRT1 in EtOH-treated BM-MSCs.

Results

EtOH treatments resulted in senescence-associated phenotypes in BM-MSCs, such as decreased cell proliferation, increased SA-β-gal activity and G0/G1 cell cycle arrest. EtOH also increased the intracellular ROS and the expression of senescence-related genes, such as p16INK4α and p21. The down-regulated levels of SIRT1 accompanied with suppressed osteogenic differentiation were confirmed in EtOH-treated BM-MSCs. Activation of SIRT1 by ResV partially counteracted the effects of EtOH by decreasing senescence markers and rescuing the inhibited osteogenesis.

Conclusion

EtOH treatments induced premature senescence in BM-MSCs in a dose-dependent manner that was responsible for EtOH-impaired osteogenic differentiation. Activation of SIRT1 was effective in ameliorating EtOH-induced senescence phenotypes in BMSCs and could potentially lead to a new strategy for clinically preventing or treating alcohol-induced osteoporosis.

Short summary

Ethanol (EtOH) treatments induce premature senescence in marrow-derived mesenchymal stem cells in a dose-dependent manner that is responsible for EtOH-impaired osteogenic differentiation. Activation of SIRT1 is effective in ameliorating EtOH-induced senescence phenotypes, which potentially leads to a new strategy for clinically treating alcohol-induced osteoporosis.

Effects of Melatonin and Its Underlying Mechanism on Ethanol-Stimulated Senescence and Osteoclastic Differentiation in Human Periodontal Ligament Cells and Cementoblasts

The present study evaluated the protective effects of melatonin in ethanol (EtOH)-induced senescence and osteoclastic differentiation in human periodontal ligament cells (HPDLCs) and cementoblasts and the underlying mechanism. EtOH increased senescence activity, levels of reactive oxygen species (ROS) and the expression of cell cycle regulators (p53, p21 and p16) and senescence-associated secretory phenotype (SASP) genes (interleukin [IL]-1β, IL-6, IL-8 and tumor necrosis factor-α) in HPDLCs and cementoblasts. Melatonin inhibited EtOH-induced senescence and the production of ROS as well as the increased expression of cell cycle regulators and SASP genes. However, it recovered EtOH-suppressed osteoblastic/cementoblastic differentiation, as evidenced by alkaline phosphatase activity, alizarin staining and mRNA expression levels of Runt-related transcription factor 2 (Runx2) and osteoblastic and cementoblastic markers (glucose transporter 1 and cementum-derived protein-32) in HPDLCs and cementoblasts. Moreover, it inhibited EtOH-induced osteoclastic differentiation in mouse bone marrow⁻derived macrophages (BMMs). Inhibition of protein never in mitosis gene A interacting-1 (PIN1) by juglone or small interfering RNA reversed the effects of melatonin on EtOH-mediated senescence as well as osteoblastic and osteoclastic differentiation. Melatonin blocked EtOH-induced activation of mammalian target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK) and Nuclear factor of activated T-cells (NFAT) c-1 pathways, which was reversed by inhibition of PIN1. This is the first study to show the protective effects of melatonin on senescence-like phenotypes and osteoclastic differentiation induced by oxidative stress in HPDLCs and cementoblasts through the PIN1 pathway.

NOX4 Deletion in Male Mice Exacerbates the Effect of Ethanol on Trabecular Bone and Osteoblastogenesis

Chronic alcohol consumption increases bone resorption and decreases bone formation. A major component of ethanol (EtOH) pathology in bone is the generation of excess reactive oxygen species (ROS). The ROS-generating NADPH oxidase-4 (NOX4) is proposed to drive much of the EtOH-induced suppression of bone formation. Here, 13-week-old male wild-type (WT) and NOX4^-/- mice were pair fed (PF) a high-fat (35%), Lieber-DeCarli liquid diet with or without EtOH at 30% of their total calories for 12 weeks. Micro-computed tomography analysis demonstrated significant decreases in trabecular bone volume/total volume (BV/TV) percentage and cortical thickness in WT, EtOH-fed mice compared with PF controls. EtOH-fed NOX4^-/- mice also displayed decreased trabecular BV/TV and trabecular number compared with PF (P < 0.05). However, NOX4^-/- mice were protected against EtOH-induced decreases in cortical thickness (P < 0.05) and decreases in collagen1 and osteocalcin mRNA expression in cortical bone (P < 0.05). In WT and NOX4^-/- vertebral bone, EtOH suppressed expression of Wnt signaling components that promote osteoblast maturation. A role for NOX4 in EtOH inhibition of osteoblast differentiation was further demonstrated by protection against EtOH inhibition of osteoblastogenesis in ex vivo bone marrow cultures from NOX4^-/-, but not p47^phox-/- mice lacking active NADPH oxidase-2. However, bone marrow cultures from NOX4^-/- mice formed fewer osteoblastic colonies compared with WT cultures (P < 0.05), suggesting a role for NOX4 in the maintenance of mesenchymal progenitor cell populations. These data suggest that NOX4 deletion is partially protective against EtOH effects on osteoblast differentiation, but may predispose bone to osteogenic impairments.

Novel Akt activator SC-79 is a potential treatment for alcohol-induced osteonecrosis of the femoral head

Alcohol is a leading risk factor for osteonecrosis of the femoral head (ONFH). We explored the molecular mechanisms underlying alcohol-induced ONFH and investigated the protective effect of the novel Akt activator SC-79 against this disease. We found that ethanol inhibited expression of the osteogenic genes RUNX2 and OCN, downregulated osteogenic differentiation, impaired the recruitment of Akt to the plasma membrane, and suppressed Akt phosphorylation at Ser473, thereby inhibiting the Akt/GSK3β/β-catenin signaling pathway in bone mesenchymal stem cells. To assess SC-79′s ability to counteract the inhibitory effect of ethanol on Akt-Ser73 phosphorylation, we performed micro-computerized tomography and immunofluorescent staining of osteopontin, osteocalcin and collagen type 1 in a rat model of alcohol-induced ONFH. We found that SC-79 injections inhibited alcohol-induced osteonecrosis. These results show that alcohol-induced ONFH is associated with suppression of p-Akt-Ser473 in the Akt/GSK3β/β-catenin signaling pathway in bone mesenchymal stem cells. We propose that SC-79 treatment to rescue Akt activation could be tested in the clinic as a potential therapeutic approach to preventing the development of alcohol-induced ONFH.

High glucose impaired estrogen receptor alpha signaling via β-catenin in osteoblastic MC3T3-E1

Diabetic Mellitus is a risk factor for osteoporosis. It has been suggested that altered estrogen or estrogen receptor α/β (ERα/β) signaling may be involved in diabetic osteoporosis. The present study is to investigate the effects of high glucose on ERα/β signaling in osteoblastic MC3T3-E1 and how the altered signaling of ERα/β affect osteoblastic bone formation. ERα/β signaling was demonstrated as ERα/β protein expression (Western Blotting) and ER transcription activity (Luciferase Reporter assays). Proliferation (WSK-1 assaying), differentiation (ALP staining) and mineralization (Alizalard Red staining) of MC3T3-E1 were examined to evaluate bone formation function. It has been found that high glucose increased ERα/β expression dose-dependently and time-dependently, but high glucose (33mM) decreased ERα transcription activity. 17β-estradiol increased the ERα/β expression dose-dependently in normal medium, but decreased the ERα/β expression dose-dependently in medium with high glucose (33mM). High glucose decreased bone formation and also decreased the osteogenic effects of 17β-estradiol (10^-8M). High glucose decreased β-catenin expression dose-dependently and time-dependently. LiCl, an inhibitor of β-catenin degradation, decreased ERα expression but increased ERα transcription activity. When compared with high glucose treatment, LiCl (5mM) increased ALP activity and calcified nodes. Besides, high glucose also decreased the protein expression PI-3K, pAKT/AKT, GSK-3β. In conclusion, the present study suggested that high glucose may impair ERα transcription activity by inhibiting β-catenin signaling in osteoblastic MC3T3-E1, leading decreased bone formation ligand-dependently or ligand-independently.

The protective effect of PFTα on alcohol-induced osteonecrosis of the femoral head

Epidemiologic studies have shown alcohol plays a pivotal role in the development of osteonecrosis of the femoral head (ONFH). The aim of this study was to explore the underlying mechanism of alcohol-induced ONFH and the protective effect of pifithrin-α (PFTα). In vitro, we found ethanol treatment significantly activated p53, suppressed Wnt/β-catenin signaling and inhibited osteogenic-related proteins. Furthermore, by separating the cytoplasmic and nuclear proteins, we found ethanol inhibited osteogenesis by impairing the accumulation of β-catenin in both the cytoplasm and nucleus in human bone mesenchymal stem cells (hBMSCs), which resulted from activating glycogen synthase kinase-3β (GSK-3β). Therefore, PFTα, a p53 inhibitor, was introduced in this study to block the ethanol-triggered activation of p53 in hBMSCs and alcohol-induced ONFH in a rat model. In vivo, we established alcohol-induced ONFH in rats and investigated the protective effect of PFTα. Hematoxylin & eosin (H&E) staining combined with TdT-mediated dUTP nick end labeling (TUNEL), cleaved caspase-3 immunohistochemical staining, and micro-CT images revealed substantial ONFH in the alcohol-administered rats, whereas significantly less osteonecrosis developed in the rats injected with PFTα. Osteogenic-related proteins, including osteocalcin, osteopontin and collagen I, were significantly decreased in the alcohol-administered rats, whereas these results were reversed in the PFTα-injected rats. Fluorochrome labeling similarly showed that alcohol significantly reduced the osteogenic activity in the rat femoral head, which was blocked by the injection of PFTα. In conclusion, PFTα had an antagonistic effect against the effects of ethanol on hBMSCs and could be a clinical strategy to prevent the development of alcohol-induced ONFH.

The crosstalk between Wnt/β-catenin signaling pathway with DNA damage response and oxidative stress: Implications in cancer therapy

DNA repair is essential for maintaining genomic integrity in cells. The dependence of cancer cell survival on proper DNA repair provides an opportunity to treat defective tumors by DNA damaging agents. Not only Wnt signaling has important functions in controlling gene expression, as well as cell polarity, adhesion and behavior, it also highly interacts with DNA damage response (DDR) in different levels. Furthermore, oxidative stress, which is responsible for majority of DNA lesions, affects Wnt signaling in different ways. A better understanding of the cross-talk between these pathways and events could provide strategies for treatment of cancer cells with deficient DNA repair capacity. As such, we will give a brief overview of the importance of the DNA repair machinery, signaling mechanisms of Wnt/β-catenin pathway, and DDR. We will further review the interactions between Wnt signaling and DDR, and the impact of oxidative stress on Wnt signaling. Finally, Wnt signaling is discussed as a potential treatment strategy for cancer.

Partial Protection by Dietary Antioxidants Against Ethanol-Induced Osteopenia and Changes in Bone Morphology in Female Mice

BACKGROUND

Chronic alcohol consumption leads to increased fracture risk and an elevated risk of osteoporosis by decreasing bone accrual through increasing osteoclast activity and decreasing osteoblast activity. We have shown that this mechanism involves the generation of reactive oxygen species (ROS) produced by NADPH oxidases. It was hypothesized that different dietary antioxidants, N-acetyl cysteine (NAC; 1.2 mg/kg/d), and α-tocopherol (Vit.E; 60 mg/kg/d) would be able to attenuate the NADPH oxidase-mediated ROS effects on bone due to chronic alcohol intake.

METHODS

To study the effects of these antioxidants, female mice received a Lieber-DeCarli liquid diet containing ethanol (EtOH) with or without additional antioxidant for 8 weeks.

RESULTS

Tibias displayed decreased cortical bone mineral density in both the EtOH and EtOH + antioxidant groups compared to pair-fed (PF) and PF + antioxidant groups (p < 0.05). However, there was significant protection from trabecular bone loss in mice fed either antioxidant (p < 0.05). Microcomputed tomography analysis demonstrated a significant decrease in bone volume (bone volume/tissue volume) and trabecular number (p < 0.05), along with a significant increase in trabecular separation in the EtOH compared to PF (p < 0.05). In contrast, the EtOH + NAC and EtOH + Vit.E did not statistically differ from their respective PF controls. Ex vivo histologic sections of tibias were stained for nitrotyrosine, an indicator of intracellular damage by ROS, and tibias from mice fed EtOH exhibited significantly more staining than PF controls. EtOH treatment significantly increased the number of marrow adipocytes per mm as well as mRNA expression of aP2, an adipocyte marker in bone. Only NAC was able to reduce the number of marrow adipocytes to PF levels. EtOH-fed mice exhibited reduced bone length (p < 0.05) and had a reduced number of proliferating chondrocytes within the growth plate. NAC and Vit.E prevented this (p < 0.05).

CONCLUSIONS

These data show that alcohol's pathological effects on bone extend beyond decreasing bone mass and suggest a partial protective effect of the dietary antioxidants NAC and Vit.E at these doses with regard to alcohol effects on bone turnover and bone morphology.

Maternal Obesity Programs Senescence Signaling and Glucose Metabolism in Osteo-Progenitors From Rat and Human

Nutritional status during intrauterine and early postnatal life impacts the risk of chronic diseases, presumably via epigenetic mechanisms. However, evidence on the impact of gestational events on regulation of embryonic bone cell fate is sparse. We investigated the effects of maternal obesity on fetal osteoblast development in both rodents and humans. Female rats were fed control or an obesogenic high-fat diet (HFD) for 12 weeks and mated with male rats fed control diets, and respective maternal diets were continued during pregnancy. Embryonic rat osteogenic calvarial cells (EOCCs) were taken from gestational day 18.5 fetuses from control and HFD dams. EOCCs from HFD obese dams showed increases in p53/p21-mediated cell senescence signaling but decreased glucose metabolism. Decreased aerobic glycolysis in HFD-EOCCs was associated with decreased osteoblastic cell differentiation and proliferation. Umbilical cord human mesenchymal stem cells (MSCs) from 24 pregnant women (12 obese and 12 lean) along with placentas were collected upon delivery. The umbilical cord MSCs of obese mothers displayed less potential toward osteoblastogenesis and more towards adipogenesis. Human MSCs and placenta from obese mothers also exhibited increased cell senescence signaling, whereas MSCs showed decreased glucose metabolism and insulin resistance. Finally, we showed that overexpression of p53 linked increased cell senescence signaling and decreased glucose metabolism in fetal osteo-progenitors from obese rats and humans. These findings suggest programming of fetal preosteoblastic cell senescence signaling and glucose metabolism by maternal obesity.

Dietary factors during early life program bone formation in female rats

Nutritional status during intrauterine and early postnatal life impacts the risk of chronic diseases; however, evidence for an association between early-life dietary factors and bone health in adults is limited. Soy protein isolate (SPI) may be one such dietary factor that promotes bone accretion during early life with persistent effects into adulthood. In the present study, we fed postnatal day (PND) 24 weanling female rats an SPI diet for 30 d [short-term SPI (ST-SPI)], and on PND 55, we switched SPI diet to control Cas diet until age 6 mo. Rats then underwent either ovariectomy (OVX) or sham surgery and thereafter either continued to be fed an SPI diet or control diet for 1 or 3 wk. We showed significantly increased bone mass in 30-d SPI-fed young rats compared with controls. OVX-induced bone loss was associated with increased osteoblastic cell senescence. On the one hand, both long-term SPI (continuous SPI diet throughout life) and ST-SPI diet only in early life protected against 1 wk post-OVX-associated bone loss. On the other hand, long-term SPI diet diminished the loss of total, trabecular, and cortical bone mineral density, whereas ST-SPI diet only reduced cortical bone mineral density loss 3 wk post-OVX. Persistent and protective effects of SPI diets on OVX-induced bone loss were associated with down-regulation of the caveolin-1/p53-mediated senescence pathway in bone. We recapitulated these results in cell cultures. Reprogramming of cellular senescence signaling by SPI-associated isoflavones in osteoblastic cells may explain the persistent effects of SPI on bone. These results suggest that OVX-induced bone loss, in part, is a result of increased osteoblastic cell senescence, and that ST-SPI diet early in life has modest but persistent programming effects on bone formation to prevent OVX-induced bone loss in adult female rats.-Chen, J.-R., Lazarenko, O. P., Blackburn, M. L., Shankar, K. Dietary factors during early life program bone formation in female rats.

Alcohol: A Simple Nutrient with Complex Actions on Bone in the Adult Skeleton

BACKGROUND

Alcohol is an important nonessential component of diet, but the overall impact of drinking on bone health, especially at moderate levels, is not well understood. Bone health is important because fractures greatly reduce quality of life and are a major cause of morbidity and mortality in the elderly. Regular alcohol consumption is most common following skeletal maturity, emphasizing the importance of understanding the skeletal consequences of drinking in adults.

METHODS

This review focuses on describing the complex effects of alcohol on the adult skeleton. Studies assessing the effects of alcohol on bone in adult humans as well as skeletally mature animal models published since the year 2000 are emphasized.

RESULTS

Light to moderate alcohol consumption is generally reported to be beneficial, resulting in higher bone mineral density (BMD) and reduced age-related bone loss, whereas heavy alcohol consumption is generally associated with decreased BMD, impaired bone quality, and increased fracture risk. Bone remodeling is the principal mechanism for maintaining a healthy skeleton in adults and dysfunction in bone remodeling can lead to bone loss and/or decreased bone quality. Light to moderate alcohol may exert beneficial effects in older individuals by slowing the rate of bone remodeling, but the impact of light to moderate alcohol on bone remodeling in younger individuals is less certain. The specific effects of alcohol on bone remodeling in heavy drinkers are even less certain because the effects are often obscured by unhealthy lifestyle choices, alcohol-associated disease, and altered endocrine signaling.

CONCLUSIONS

Although there have been advances in understanding the complex actions of alcohol on bone, much remains to be determined. Limited evidence implicates age, skeletal site evaluated, duration, and pattern of drinking as important variables. Few studies systematically evaluating the impact of these factors have been conducted and should be made a priority for future research. In addition, studies performed in skeletally mature animals have potential to reveal mechanistic insights into the precise actions of alcohol and associated comorbidity factors on bone remodeling.

p47phox-Nox2-dependent ROS Signaling Inhibits Early Bone Development in Mice but Protects against Skeletal Aging

Bone remodeling is age-dependently regulated and changes dramatically during the course of development. Progressive accumulation of reactive oxygen species (ROS) has been suspected to be the leading cause of many inflammatory and degenerative diseases, as well as an important factor underlying many effects of aging. In contrast, how reduced ROS signaling regulates inflammation and remodeling in bone remains unknown. Here, we utilized a p47(phox) knock-out mouse model, in which an essential cytosolic co-activator of Nox2 is lost, to characterize bone metabolism at 6 weeks and 2 years of age. Compared with their age-matched wild type controls, loss of Nox2 function in p47(phox-/-) mice resulted in age-related switch of bone mass and strength. Differences in bone mass were associated with increased bone formation in 6-week-old p47(phox-/-) mice but decreased in 2-year-old p47(phox-/-) mice. Despite decreases in ROS generation in bone marrow cells and p47(phox)-Nox2 signaling in osteoblastic cells, 2-year-old p47(phox-/-) mice showed increased senescence-associated secretory phenotype in bone compared with their wild type controls. These in vivo findings were mechanistically recapitulated in ex vivo cell culture of primary fetal calvarial cells from p47(phox-/-) mice. These cells showed accelerated cell senescence pathway accompanied by increased inflammation. These data indicate that the observed age-related switch of bone mass in p47(phox)-deficient mice occurs through an increased inflammatory milieu in bone and that p47(phox)-Nox2-dependent physiological ROS signaling suppresses inflammation in aging.

Soy protein isolate inhibits high-fat diet-induced senescence pathways in osteoblasts to maintain bone acquisition in male rats

Chronic consumption by experimental animals of a typical Western diet high in saturated fats and cholesterol during postnatal life has been demonstrated to impair skeletal development. However, the underlying mechanism by which high-fat, energy-dense diets affect bone-forming cell phenotypes is poorly understood. Here, we show that male weanling rats fed a diet containing 45% fat and 0.5% cholesterol made with casein (HF-Cas) for 6 weeks displayed lower bone mineral density and strength compared with those of AIN-93G-fed dietary controls. Substitution of casein with soy protein isolate (SPI) in the high-fat diet (HF-SPI) prevented these effects. The bone-sparing effects of SPI were associated with prevention of HF-Cas-induced osteoblast senescence pathways through suppression of the p53/p21 signaling pathways. HF-Cas-fed rats had increased caveolin-1 and down-regulated Sirt1, leading to activations of peroxisome proliferator-activated receptor γ (PPARγ) and p53/p21, whereas rats fed HF-SPI suppressed caveolin-1 and activated Sirt1 to deacetylate PPARγ and p53 in bone. Treatment of osteoblastic cells with nonesterified free fatty acid (NEFA) increased cell senescence signaling pathways. Isoflavones significantly blocked activations of senescence-associated β-galactosidase and PPARγ/p53/p21 by NEFA. Finally, replicative senescent osteoblastic cells and bone marrow mesenchymal ST2 cells exhibited behavior similar to that of cells treated with NEFA and in vivo bone cells in rats fed the HF-Cas diet. These results suggest that (1) high concentrations of NEFA occurring with HF intake are mediators of osteoblast cell senescence leading to impairment of bone development and acquisition and (2) the molecular mechanisms underlying the SPI-protective effects involve isoflavone-induced inhibition of osteoblastic cell senescence to prevent HF-induced bone impairments.

Hip fractures and chronic alcohol excess: a series of 7,023 cases

We aim to compare trends in characteristics and outcomes for 131 patients with evidence of excess alcohol intake at the time of admission with a hip fracture against 6,892 hip fracture patients with no evidence of alcohol excess. Alcohol excess was determined by a finding of abnormal liver function tests in association with a history of excessive alcohol consumption. Patients who consumed excess alcohol were younger (64 versus 80 years mean age), more likely to be male (47% versus 22%), smoke cigarettes (54% versus 11%), be more mobile and less likely to use a walking aid (28% versus 46%). They were also more likely to sustain an extracapsular fracture (53% versus 39%) and to be living in their own homes at the time of injury (85% versus 66%). Hypertension and cardiac disease were less common in those with alcohol excess. Postoperatively those with alcohol abuse had a shorter hospital stay (mean nine days versus 16 days) but were at a greater risk of developing deep wound infections (2.3% versus 0.6%). For those patients who sustained intracapsular fractures treated by internal fixation there was an increased risk of fracture non-union occurring (29% versus 16%) but there were no other differences in operative complications.

Genistein supplementation increases bone turnover but does not prevent alcohol-induced bone loss in male mice

Chronic alcohol consumption results in bone loss through increased bone resorption and decreased bone formation. These effects can be reversed by estradiol (E2) supplementation. Soy diets are suggested to have protective effects on bone loss in men and women, as a result of the presence of soy protein-associated phytoestrogens such as genistein (GEN). In this study, male mice were pair-fed (PF), a control diet, an ethanol (EtOH) diet, or EtOH diet supplemented with 250 mg/kg of GEN for 8 weeks to test if GEN protects against bone loss associated with chronic drinking. Interestingly, alcohol consumption reduced cortical area and thickness and trabecular bone volume in both EtOH and EtOH/GEN groups when compared to the corresponding PF and PF/GEN controls, P < 0.05. However, in the trabecular bone compartment, we observed a significant increase in overall trabecular bone density in the PF/GEN group compared to the PF controls. Bone loss in the EtOH-treated mice was associated with the inhibition of osteoblastogenesis as indicated by decreased alkaline phosphatase staining in ex vivo bone marrow cultures, P < 0.05. GEN supplementation improved osteoblastogenesis in the EtOH/GEN cultures compared to the EtOH group, P < 0.05. Vertebral expression of bone-formation markers, osteocalcin, and runt-related transcription factor 2 (Runx2) was also significantly up-regulated in the PF/GEN and EtOH/GEN groups compared to the PF and EtOH-treated groups. GEN supplementation also increased the expression of receptor activator of nuclear factor κ-B ligand (RANKL) in the PF/GEN, an increase that persisted in the EtOH/GEN-treated animals (P < 0.05), and increased basal hydrogen peroxide production and RANKL mRNA expression in primary bone marrow cultures in vitro, P < 0.05. These findings suggest that GEN supplementation increases the overall bone remodeling and, in the context of chronic alcohol consumption, does not protect against the oxidative stress-associated EtOH-mediated bone resorption.

Osteoporosis in men

Osteoporosis in men causes significant morbidity and mortality. Bone health declines gradually, often insidiously; and in light of the advancing aging population poses a serious public health issue that is not well recognized. Studies of the past decade have expanded our understanding of the events within, as well as the regulation of, bone remodeling and provided better insight into the physiology and pathophysiology specific to the adult male skeleton. The clinical measurement of bone mineral density using dual-energy X-ray absorptiometry remains the gold standard for diagnosis of osteoporosis in males; and fracture risk assessment is now recognized as a preferred approach to guide treatment decisions. Utilizing surrogate end-points such as increasing bone mineral density and decreasing concentrations of bone resorption markers, clinical trials have demonstrated efficacy in pharmacological treatment of osteoporosis in the adult male. Unfortunately, few studies have evaluated the anti-fracture benefits in this population. Measurement of bone turnover markers may be an additional tool to monitor therapeutic responsiveness in addition to the measurement of bone mineral density.

Soy protein isolates prevent loss of bone quantity associated with obesity in rats through regulation of insulin signaling in osteoblasts

In both rodents and humans, excessive consumption of a typical Western diet high in saturated fats and cholesterol is known to result in disruption of energy metabolism and development of obesity and insulin resistance. However, how these high-fat, energy-dense diets affect bone development, morphology, and modeling is poorly understood. Here we show that male weanling rats fed a high-fat (HF) diet containing 45% fat and 0.5% cholesterol made with casein (HF-Cas) for 6 wk displayed a significant increase in bone marrow adiposity and insulin resistance. Substitution of casein with soy protein isolate (SPI) in the HF diet (HF-SPI) prevented these effects. Maintenance of bone quantity in the SPI-fed rats was associated with increased undercarboxylated osteocalcin secretion and altered JNK/IRS1/Akt insulin signaling in osteoblasts. The HF-Cas group had significantly greater serum nonesterified free fatty acid (NEFA) concentrations than controls, whereas the HF-SPI prevented this increase. In vitro treatment of osteoblasts or mesenchymal stromal ST2 cells with NEFAs significantly decreased insulin signaling. An isoflavone mixture similar to that found in serum of HF-SPI rats significantly increased in vitro osteoblast proliferation and blocked significantly reduced NEFA-induced insulin resistance. Finally, insulin/IGF1 was able to increase both osteoblast activity and differentiation in a set of in vitro studies. These results suggest that high-fat feeding may disrupt bone development and modeling; high concentrations of NEFAs and insulin resistance occurring with high fat intake are mediators of reduced osteoblast activity and differentiation; diets high in soy protein may help prevent high dietary fat-induced bone impairments; and the molecular mechanisms underlying the SPI-protective effects involve isoflavone-induced normalization of insulin signaling in bone.

Blueberry consumption prevents loss of collagen in bone matrix and inhibits senescence pathways in osteoblastic cells

Ovariectomy (OVX)-induced bone loss has been linked to increased bone turnover and higher bone matrix collagen degradation as the result of osteoclast activation. However, the role of degraded collagen matrix in the fate of resident bone-forming cells is unclear. In this report, we show that OVX-induced bone loss is associated with profound decreases in collagen 1 and Sirt1. This was accompanied by increases in expression and activity of the senescence marker collagenase and expression of p16/p21 in bone. Feeding a diet supplemented with blueberries (BB) to pre-pubertal rats throughout development or only prior to puberty [postnatal day 21 (PND21) to PND34] prevents OVX-induced effects on expression of these molecules at PND68. In order to provide more evidence and gain a better understanding on the association between bone collagen matrix and resident bone cell fate, in vitro studies on the cellular senescence pathway using primary calvarial cells and three cell lines (ST2 cells, OB6, and MLO-Y4) were conducted. We found that senescence was inhibited by collagen in a dose-response manner. Treatment of cells with serum from OVX rats accelerated osteoblastic cell senescence pathways, but serum from BB-fed OVX rats had no effect. In the presence of low collagen or treatment with OVX rat serum, ST2 cells exhibited higher potential to differentiate into adipocytes. Finally, we demonstrated that bone cell senescence is associated with decreased Sirt1 expression and activated p53, p16, and p21. These results suggest that (1) a significant prevention of OVX-induced bone cell senescence from adult rats can occur after only 14 days consumption of a BB-containing diet immediately prior to puberty, and (2) the molecular mechanisms underlying this effect involves, at least in part, prevention of collagen degradation.

Female mice lacking p47phox have altered adipose tissue gene expression and are protected against high fat-induced obesity

The current study was designed to determine if the NADPH-oxidase NOX2 plays a role in development of obesity after high fat feeding. Wild-type (WT) mice and mice lacking the essential cytosolic NOX2 system component p47phox (P47KO mice) were fed AIN-93G diets or high-fat diets (HFD) containing 45% fat and 0.5% cholesterol for 13 wk from weaning. Fat mass was increased to a similar degree by HFD in males of both genotypes ( P < 0.05). However, female P47KO-HFD mice had no increase in adiposity or adipocyte size relative to female WT-HFD mice. Resistance to HFD-driven obesity in P47KO females was associated with increased expression of hepatic TFAM and UCP-2 mRNA, markers of mitochondrial number and uncoupling, and increased expression of hepatic mitochondrial respiratory complexes and whole body energy expenditure in response to HFD. Microarray analysis revealed significantly lower expression of mRNA encoding genes linked to energy metabolism, adipocyte differentiation (PPARγ), and fatty acid uptake (CD36, lipoprotein lipase), in fat pads from female P47KO-HFD mice compared with WT-HFD females. Moreover, differentiation of preadipocytes ex vivo was suppressed more by 17β-estradiol in cells from P47KO compared with cells from WT females in conjunction with overexpression of mRNA for Pref-1 ( P < 0.05). HFD mice of both sexes were resistant to the development of hyperglycemia and hepatic steatosis ( P < 0.05) and had reduced serum triglycerides, leptin, and adiponectin relative to WT-HFD mice ( P < 0.05). These data suggest that NOX2 is an important regulator of metabolic homeostasis and diet-induced obesity.

Melatonin and ethanol intake exert opposite effects on circulating estradiol and progesterone and differentially regulate sex steroid receptors in the ovaries, oviducts, and uteri of adult rats

Chronic ethanol intake is associated with sex hormone disturbances, and it is well known that melatonin plays a key role in regulating several reproductive processes. We report the effects of ethanol intake and melatonin treatment (at doses of 100 μg/100 g BW/day) on sex hormones and steroid receptors in the ovaries, oviducts and uteri of ethanol-preferring rats. After 150 days of treatment, animals were euthanized, and tissue samples were harvested to evaluate androgen, estrogen, progesterone and melatonin receptor subunits (AR, ER-α and ER-β, PRA, PRB and MT1R, respectively). Melatonin decreased estradiol (E2) and increased progesterone (P4) and 6-sulfatoxymelatonin (6-STM), while an ethanol-melatonin combination reduced both P4 and E2. Ovarian AR was not influenced by either treatment, and oviduct AR was reduced after ethanol-melatonin combination. Oviduct ER-α, ER-β and uterine ER-β were down-regulated by either ethanol or melatonin. Conversely, ovarian PRA and PRB were positively regulated by ethanol and ethanol-melatonin combination, whereas PRA was down-regulated in the uterus and oviduct after ethanol consumption. MT1R was increased in ovaries and uteri of melatonin-treated rats. Ethanol and melatonin exert opposite effects on E2 and P4, and they differentially regulate the expression of sex steroid receptors in female reproductive tissues.

A high-fat diet induces obesity and impairs bone acquisition in young male mice

The postnatal development of obesity is highly associated with the excessive consumption of a high-calorie, high-fat diet (HFD). However, the correlation between HFD-induced pediatric obesity and skeletal development remains to be elucidated. In the present study, postnatal day 17 (PND17) mice were weaned on a HFD for eight weeks ad libitum to induce obesity. The HFD mice showed a significant increase in the total body weight and gonadal and abdominal fat mass compared with the control animals. Peripheral quantitative (pQ) CT scans of the tibial bone revealed that the bone mineral density (BMD), including the total, trabecular and cortical BMD, was unchanged between the HFD and control diet groups, but that it was inversely associated with body fat. By contrast, the bone mineral content (BMC) and trabecular area were significantly decreased in the HFD group compared with the control. RNA and protein were isolated from the femur. qPCR and western blot analyses showed a significant downregulation in the gene expression of the key canonical Wnt signaling molecule β-catenin, the osteoblastic cell differentiation marker Runt-related transcription factor 2 (Runx2) and also in the β-catenin gene encoded protein levels of the HFD mice when compared with the controls. Consistent with the increased fat mass in the HFD-induced obese animals, the expression of the adipogenic genes and aP2 was increased compared with the controls. Bone marrow cells were aspirated and the ex vivo bone marrow cell cultures showed that the number of colony-forming unit osteoblasts (CFU-OBs) per bone was significantly decreased in the samples from the HFD mice compared with those from the controls. These observations suggested that HFD-induced obesity in growing animals may affect the total available osteoblastic cell differentiation progenitors in the bone, while increasing adipogenesis. This may result in negative consequences for the bone later on in adult life.

Association of regional body composition with bone mineral density in HIV-infected and HIV-uninfected women: women's interagency HIV study

OBJECTIVE

To understand how regional body composition affects bone mineral density (BMD) in HIV-infected and HIV-uninfected women.

METHODS

Dual energy x-ray absorptiometry was used to measure regional lean and fat mass and BMD at lumbar spine (LS), total hip (TH), and femoral neck (FN) in 318 HIV-infected and 122 HIV-uninfected Women's Interagency HIV Study participants at baseline and 2 and 5 years later. Total lean and fat mass were measured using bioimpedance analysis. Multivariate marginal linear regression models assessed the association of HIV status and body composition on BMD change.

RESULTS

Compared with HIV-uninfected women, HIV-infected women were older (44 vs. 37 years), more likely to be Hepatitis C virus-infected (32% vs. 14%), and postmenopausal (26% vs. 3%) and had lower baseline total fat mass, trunk fat, and leg fat. In multivariate models, increased total lean mass was independently associated with increased BMD at LS, TH, and FN, and total fat mass was associated with increased BMD at TH and FN (all P < 0.05). When total fat was replaced in multivariate models with trunk fat and leg fat, increased trunk fat (and not leg fat) was associated with increased TH and FN BMD (P < 0.001).

CONCLUSIONS

Total fat and lean mass are strong independent predictors of TH and FN BMD, and lean mass was associated with greater LS BMD. Regardless of HIV status, greater trunk fat (and not leg fat) was associated with increased TH and FN BMD, suggesting that weight-bearing fat may be a more important predictor of BMD in the hip.

Transcriptional activity of human brain estrogen receptor-α splice variants: evidence for cell type-specific regulation

Estrogen receptor α (ERα) isoforms with complex types of alternative splicing are naturally present in the human brain and may affect canonical receptor signaling. In the present study we investigated transcriptional activity of common ERα splice variants from this group with different molecular defects: MB1 (intron retention), TADDI (small deletion between exons 3 and 4 with an insert), the Δ (deletion) 3(⁎)-7(*)/819 (complete skipping of exons 4, 5 and 6 and partial deletion of exons 3 and 7) and the Δ3-6 (lacking exons 3, 4, 5 and 6) in HeLa and M17 cells upon stimulation with (17β)estradiol or insulin-like growth factor 1 (IGF-1). In HeLa cells, all these splice variants showed the dominant negative function that was more pronounced for the TADDI. In M17 cells the dominant negative variants appeared to be the MB1 and the Δ3-6, whereas TADDI turned out to be a clearly dominant positive variant. In M17 cells mRNA levels of Δ3-6 and Δ3(*)-7(*)/819 variants increased following (17β)estradiol administration. In Hela cells (17β)estradiol up-regulated the IGF-1 receptor mRNA levels in cultures transfected with MB1, TADDI and Δ3(*)-7(*)/819. Our data demonstrate that ERα splice variants show differential levels of the transcriptional activity in a cell type-specific way and that IGF-1 signaling pathways are differentially employed in a cell-type specific manner depending on the level of the discrete ERα splice variants expressed. Functional properties of various ERα splice variants and their cell type-specificity should, thus, be considered as potential confounders of estrogen therapy effects on the brain.

Pleiotropic actions of estrogen: a mitochondrial matter

Estrogen provides many beneficial effects early in life by regulating normal tissue development and several physiological functions. While estrogen replacement therapy (ERT) in women was expected to reduce the health risks associated with the age-related decline in estrogen levels during menopause, ERT also resulted in increased progression to other types of diseases. Hence, distinguishing the signaling pathways that regulate the beneficial and detrimental effects of estrogen is important for developing interventions that selectively harness the hormone's beneficial effects, while minimizing its side effects. Estrogen can minimize mitochondrial dysfunction, which is thought to contribute to aging phenotypes. Decline in estrogen levels during menopause may lead to progressive mitochondrial dysfunction and may permanently alter cellular response, including that of estrogen (i.e., ERT). This review discusses the interplay between estrogen and mitochondrial function during the aging process and suggests a potential role of mitochondria in influencing the pleiotropic action of estrogen.

Flavonoid intake and bone health

Flavonoids, found in a wide diversity of plant foods from fruits and vegetables, herbs and spices, essential oils, and beverages, have the most potential of dietary components for promotion of bone health beyond calcium and vitamin D. Recent epidemiological studies show flavonoid consumption to have a stronger association with bone than general fruit and vegetable consumption. Bioactive flavonoids are being assessed for properties beyond their chemical antioxidant capacity, including anti-inflammatory actions. Some have been reported to enhance bone formation and to inhibit bone resorption through their action on cell signaling pathways that influence osteoblast and osteoclast differentiation. Future research is needed to determine which of the flavonoids and their metabolites are most effective and at what dose, as well as the mechanism of modulating cellular events, in order to set priorities for clinical trials.

Comparison of the agar block and Lieber-DeCarli diets to study chronic alcohol consumption in an aging model of Fischer 344 female rats

INTRODUCTION

Post-menopausal women have a greater risk of developing alcoholic complications compared to age-matched men. Unfortunately, animal models of chronic ethanol consumption with estrogen deficiency are lacking. Here, we characterize the ability of the agar block and Lieber-DeCarli models of chronic ethanol consumption to produce elevated blood alcohol content (BAC) and liver pathology in the F344 postmenopausal animal model of aging.

METHODS

Adult (3 mo) and aged (18 mo) F344 ovary-intact or ovariectomized rats were administered ethanol for 14-20 weeks as follows: diet 1, standard chow access, 10% ethanol in drinking water, and 40% ethanol in agar blocks; diet 2, diet 1 plus low phytoestrogen chow (known to affect ethanol metabolism) for the final 4 weeks; diet 3, Lieber-DeCarli all liquid diet with 36% kcal ethanol. Control animals were matched isocalorically with dextrin.

RESULTS

For the agar block diet, average BAC was 13±4 mg/dL across groups. BAC was unaffected by reducing dietary phytoestrogen content (12±4 mg/dL), which is known to interfere with ethanol metabolism. Liver pathology was unaffected by the agar block diet. In contrast, the Lieber-DeCarli diet resulted in BAC of 45±5 mg/dL in conjunction with more severe hepatopathology.223

DISCUSSION

We conclude that the Lieber-DeCarli diet produces greater BAC and hepatopathology to study the effects of chronic ethanol administration in the F344 postmenopausal rodent model of aging when compared to an ethanol agar block diet.

Ugonin K-stimulated osteogenesis involves estrogen receptor-dependent activation of non-classical Src signaling pathway and classical pathway

We have reported previously that ugonin K, a flavonoid isolated from Helminthostachys zeylanica (L.) Hook, potently induces cell differentiation and mineralization of MC3T3-E1 mouse osteoblast-like cells. Here we aimed to elucidate whether ugonin K evoked osteogenesis required interaction with estrogen receptor. Results showed that ugonin K induced increases in alkaline phosphatase (ALP) activity, expressions of bone sialoprotein (BSP) and osteocalcin (OCN), and subsequent bone nodule formation were concentration-dependently inhibited by estrogen receptor antagonist ICI 182,780, suggesting that an estrogen receptor-dependent pathway was involved. In the presence of ICI 182,780, ugonin K induced up-regulation of the expressions of runt-related transcription factor 2 (Runx2) and osterix was also significantly repressed. Numerous studies have demonstrated that estrogens induced rapid and transient activation of the c-Src phosphorylation cascade. We found that ugonin K indeed raised the phosphorylated level of c-Src and such phosphorylation was significantly attenuated by ICI 182,780 treatment. Application of c-Src specific inhibitor PP2 concentration-dependently repressed ugonin K-induced osteogenesis. In the nuclear translocation assay, results showed that ugonin K increased the nuclear level of estrogen receptor-α protein, suggesting that an enhanced transcriptional activity might be observed. Excepting MC3T3-E1 cells, results obtained from ALP activity assay revealed that ugonin K also stimulated osteoblastic differentiation of human MG-63 osteosarcoma cells and rat primary osteoblasts isolated from femora. Our results demonstrate that ugonin K stimulated osteogenesis might act through an estrogen receptor-dependent activation of a non-classical signaling pathway mediated by phosphorylation of c-Src. Moreover, a transactivation potential toward estrogen receptor-α through a classical pathway might not be precluded.

Alcohol and bone: review of dose effects and mechanisms

Alcohol is widely consumed across the world. It is consumed in both social and cultural settings. Until recently, two types of alcohol consumption were recognized: heavy chronic alcohol consumption or light consumption. Today, there is a new pattern of consumption among teenagers and young adults namely: binge drinking. Heavy alcohol consumption is detrimental to many organs and tissues, including bones, and is known to induce secondary osteoporosis. Some studies, however, have reported benefits from light alcohol consumption on bone parameters. To date, little is known regarding the effects of binge drinking on bone health. Here, we review the effects of three different means of alcohol consumption: light, heavy, and binge drinking. We also review the detailed literature on the different mechanisms by which alcohol intake may decrease bone mass and strength. The effects of alcohol on bone are thought to be both direct and indirect. The decrease in bone mass and strength following alcohol consumption is mainly due to a bone remodeling imbalance, with a predominant decrease in bone formation. Recent studies, however, have reported new mechanisms by which alcohol may act on bone remodeling, including osteocyte apoptosis, oxidative stress, and Wnt signalling pathway modulation. The roles of reduced total fat mass, increased lipid content in bone marrow, and a hypoleptinemia are also discussed.

Feeding blueberry diets in early life prevent senescence of osteoblasts and bone loss in ovariectomized adult female rats

BACKGROUND

Appropriate nutrition during early development is essential for maximal bone mass accretion; however, linkage between early nutrition, childhood bone mass, peak bone mass in adulthood, and prevention of bone loss later in life has not been studied.

METHODOLOGY AND PRINCIPAL FINDINGS

In this report, we show that feeding a high quality diet supplemented with blueberries (BB) to pre-pubertal rats throughout development or only between postnatal day 20 (PND20) and PND34 prevented ovariectomy (OVX)-induced bone loss in adult life. This protective effect of BB is due to suppression of osteoblastic cell senescence associated with acute loss of myosin expression after OVX. Early exposure of pre-osteoblasts to serum from BB-fed rats was found to consistently increase myosin expression. This led to maintenance osteoblastic cell development and differentiation and delay of cellular entrance into senescence through regulation of the Runx2 gene. High bone turnover after OVX results in insufficient collagenous matrix support for new osteoblasts and their precursors to express myosin and other cytoskeletal elements required for osteoblast activity and differentiation.

CONCLUSIONS/SIGNIFICANCE

These results indicate: 1) a significant prevention of OVX-induced bone loss from adult rats can occur with only 14 days consumption of a BB-containing diet immediately prior to puberty; and 2) the molecular mechanisms underlying these effects involves increased myosin production which stimulates osteoblast differentiation and reduces mesenchymal stromal cell senescence.