Estrogens maintain bone mass by regulating expression of genes controlling function and life span in mature osteoclasts

Potential Metabolic Pathways Involved in Osteoporosis and Evaluation of Fracture Risk in Individuals with Diabetes

Diabetes has a significant global prevalence. Chronic hyperglycemia affects multiple organs and tissues, including bones. A large number of diabetic patients develop osteoporosis; however, the precise relationship between diabetes and osteoporosis remains incompletely elucidated. The activation of the AGE-RAGE signaling pathway hinders the differentiation of osteoblasts and weakens the process of bone formation due to the presence of advanced glycation end products. High glucose environment can induce ferroptosis of osteoblasts and then develop osteoporosis. Hyperglycemia also suppresses the secretion of sex hormones, and the reduction of testosterone is difficult to effectively maintain bone mineral density. As diabetes therapy, thiazolidinediones control blood glucose by activating PPAR-γ. Activated PPAR-γ can promote osteoclast differentiation and regulate osteoblast function, triggering osteoporosis. The effects of metformin and insulin on bone are currently controversial. Currently, there are no appropriate tools available for assessing the risk of fractures in diabetic patients, despite the fact that the occurrence of osteoporotic fractures is considerably greater in diabetic individuals compared to those without diabetes. Further improving the inclusion criteria of FRAX risk factors and clarifying the early occurrence of osteoporosis sites unique to diabetic patients may be an effective way to diagnose and treat diabetic osteoporosis and reduce the risk of fracture occurrence.

Inhibition of cysteine protease disturbs the topological relationship between bone resorption and formation in vitro

INTRODUCTION

Osteoporosis is a global health issue. Bisphosphonates that are commonly used to treat osteoporosis suppress both bone resorption and subsequent bone formation. Inhibition of cathepsin K, a cysteine proteinase secreted by osteoclasts, was reported to suppress bone resorption while preserving or increasing bone formation. Analyses of the different effects of antiresorptive reagents such as bisphosphonates and cysteine proteinase inhibitors will contribute to the understanding of the mechanisms underlying bone remodeling.

MATERIALS AND METHODS

Our team has developed an in vitro system in which bone remodeling can be temporally observed at the cellular level by 2-photon microscopy. We used this system in the present study to examine the effects of the cysteine proteinase inhibitor E-64 and those of zoledronic acid on bone remodeling.

RESULTS

In the control group, the amount of the reduction and the increase in the matrix were correlated in each region of interest, indicating the topological and quantitative coordination of bone resorption and formation. Parameters for osteoblasts, osteoclasts, and matrix resorption/formation were also correlated. E-64 disrupted the correlation between resorption and formation by potentially inhibiting the emergence of spherical osteoblasts, which are speculated to be reversal cells in the resorption sites.

CONCLUSION

These new findings help clarify coupling mechanisms and will contribute to the development of new drugs for osteoporosis.

Exploring the role and mechanism of Fuzi decoction in the treatment of osteoporosis by integrating network pharmacology and experimental verification

BACKGROUND

Fuzi decoction (FZD), a traditional Chinese medicine formula, was used to treat musculoskeletal diseases by warming channels, strengthening yang and dispelling pathogenic cold and dampness. In clinical practice, FZD has been used to treat rheumatoid arthritis and osteoarthritis. It alleviated osteoarticular disorders through ameliorating the degradation of cartilage and improving meniscal damage in osteoarthritis, while its roles and mechanisms in the treatment of bone loss diseases remain unclear. This study aims to investigate the underlying mechanisms of FZD in treating osteoporosis using an integrative method of network pharmacology and experimental study.

METHODS

In this study, network pharmacology was used to predict the core targets and potential pathways of the bioactive ingredients of FZD to attenuate osteoporosis. Molecular docking was performed to evaluate the interactions between core compounds and key targets. In addition, both cell and animal experiments were carried out to validate the role and potential mechanism in treating osteoporosis.

RESULTS

In the present study, data revealed that kaempferol, beta-sitosterol, stigmasterol, fumarine, and (+)-catechin may be the primary bioactive ingredients of FZD in the treatment of osteoporosis, which were closely associated with the osteoporosis-related targets. And the KEGG results indicated that the NF-κB pathway was closely associated with the function of FZD in treating osteoporosis. In addition, in vivo demonstrated that FZD ameliorated osteoporosis. In vitro experiments showed that the pro-apoptotic factors indicators including CASP3 and BAX were decreased by FZD and the anti-apoptotic factor BCL2 was increased by FZD. In addition, FZD significantly suppressed the osteoclast differentiation in culture and the expression levels of osteoclast-related genes including TRAF6, CTSK, and MMP9. And the NF-κB pathway was confirmed, via in vitro experiment, to be involved in osteoclast differentiation.

CONCLUSIONS

This study demonstrated that FZD played a pivotal role in suppressing the osteoclast differentiation via regulating the NF-κB pathway, indicating that FZD could be a promising antiosteoporosis drug and deserve further investigation.

Compound of Cynanchum wilfordii and Humulus lupulus L. Ameliorates Menopausal Symptoms in Ovariectomized Mice

Cynanchum wilfordii and Humulus lupulus L. have been used for their various pharmacological properties in South Korea as a traditional medicine or health functional food, respectively, and their intake may relieve menopausal symptoms. The purpose of current study was to determine the effect of compound of Cynanchum wilfordii and Humulus lupulus L. (CWHL) in menopausal symptoms of ovariectomized (OVX) mice. OVX mice received CWHL or caudatin (an active ingredient of CWHL) once daily for 7 weeks. Values for hypothalamic serotonin (5-HT), dopamine, norepinephrine, estrogen receptor (ER)-β, 5-HT1A, and 5-HT2A were significantly enhanced, while value for hypothalamic monoamine oxidase A was reduced in CWHL and caudatin groups compared with the OVX group. CWHL and caudatin significantly reduced tail skin temperature and rectal temperature of OVX mice through partial recovering of the levels of serum estrogen, nitric oxide, follicle-stimulating hormone, luteinizing hormone, and receptor-activator of the NF-κB ligand (RANKL). Moreover, CWHL and caudatin improved bone mineral density via decreasing levels of serum RANKL, tartrate-resistant acid phosphatase, and collagen type 1 cross-linked N-telopeptide and improving levels of serum alkaline phosphatase, osteoprotegerin, and osteocalcin compared with the OVX group without adverse effects such as dyslipidemia. CWHL increased uterine ER-β levels but did not change uterus and vaginal weights. Taken together, the results indicate that CWHL may relieve menopausal symptoms by controlling depression-, hot flashes-, and osteoporosis-associated biomarkers. Therefore, we propose that CWHL might be a safe and potential candidate for management of menopause as a health functional food.

Analysis of the effect of zoledronic acid on gene differences in rat jaw

BACKGROUND

With the widespread use of bisphosphonates, there are more and more complications about bisphosphonates, bisphosphonate-related osteonecrosis of the jaw is one.In the past ten years, there have been many studies on the mechanism of bisphosphonate associated jaw necrosis.

OBJECTIVE

To investigate the influence and analysis of zoledronic acid on gene differences in rat jaw.

METHODS

Six Sprague-Dawley female rats were randomly divided into control group (n = 3) and experimental group (n = 3). The experimental group received zoledronic acid injection for 12 weeks (dose of 0.2 mg / kg, 3 times a week).Control groups were injected with normal saline for 12 weeks. All rats were subjected to left mandibular first molar extraction 12 weeks later.After 8 weeks of tooth extraction, all rats were sacrificed and the mandible was removed.RNA-seq was used to analyze differential gene changes in all mandibles. Bioinformatics analysis of differential genes.

RESULTS

Compared with the two rat groups, there were 2,830 different genes, including 1,001 upregulated genes and 1,829 down-regulated genes. Gene Ontology analysis revealed that the upregulated genes were mainly associated with immune-related pathways. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that Hedgehog signaling pathway, Notch signaling pathway and Hippo signaling pathway were associated with upregulated genes. After the Gene Set Enrichment Analysis, the Gene Ontology analysis showed that 2559 / 6588 gene sets are upregulated in phenotype experimental group,and 342 gene sets with p <0.05. The Kyoto Encyclopedia of Genes and Genomes analysis revealed that 95 / 316 gene sets are upregulated in phenotype experimental group, and four gene sets(Notch pathway, other types of O-glycan biosynthesis, ovarian steridogenesis and Hippo pathway) with p <0.05.

CONCLUSIONS

Changes in differential genes are mainly related to immune-related processes and pathways, and pathways related to bone metabolism. The up-regulation of some genes can promote the progress of Bisphosphonate-related osteonecrosis of the jaw.

Clinical Data for Parametrization of In Silico Bone Models Incorporating Cell-Cytokine Dynamics: A Systematic Review of Literature

In silico simulations aim to provide fast, inexpensive, and ethical alternatives to years of costly experimentation on animals and humans for studying bone remodeling, its deregulation during osteoporosis and the effect of therapeutics. Within the varied spectrum of in silico modeling techniques, bone cell population dynamics and agent-based multiphysics simulations have recently emerged as useful tools to simulate the effect of specific signaling pathways. In these models, parameters for cell and cytokine behavior are set based on experimental values found in literature; however, their use is currently limited by the lack of clinical in vivo data on cell numbers and their behavior as well as cytokine concentrations, diffusion, decay and reaction rates. Further, the settings used for these parameters vary across research groups, prohibiting effective cross-comparisons. This review summarizes and evaluates the clinical trial literature that can serve as input or validation for in silico models of bone remodeling incorporating cells and cytokine dynamics in post-menopausal women in treatment, and control scenarios. The GRADE system was used to determine the level of confidence in the reported data, and areas lacking in reported measures such as binding site occupancy, reaction rates and cell proliferation, differentiation and apoptosis rates were highlighted as targets for further research. We propose a consensus for the range of values that can be used for the cell and cytokine settings related to the RANKL-RANK-OPG, TGF-β and sclerostin pathways and a Levels of Evidence-based method to estimate parameters missing from clinical trial literature.

Halogen-Based 17β-HSD1 Inhibitors: Insights from DFT, Docking, and Molecular Dynamics Simulation Studies

The high expression of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) mRNA has been found in breast cancer tissues and endometriosis. The current research focuses on preparing a range of organic molecules as 17β-HSD1 inhibitors. Among them, the derivatives of hydroxyphenyl naphthol steroidomimetics are reported as one of the potential groups of inhibitors for treating estrogen-dependent disorders. Looking at the recent trends in drug design, many halogen-based drugs have been approved by the FDA in the last few years. Here, we propose sixteen potential hydroxyphenyl naphthol steroidomimetics-based inhibitors through halogen substitution. Our Frontier Molecular Orbitals (FMO) analysis reveals that the halogen atom significantly lowers the Lowest Unoccupied Molecular Orbital (LUMO) level, and iodine shows an excellent capability to reduce the LUMO in particular. Tri-halogen substitution shows more chemical reactivity via a reduced HOMO-LUMO gap. Furthermore, the computed DFT descriptors highlight the structure-property relationship towards their binding ability to the 17β-HSD1 protein. We analyze the nature of different noncovalent interactions between these molecules and the 17β-HSD1 using molecular docking analysis. The halogen-derived molecules showed binding energy ranging from -10.26 to -11.94 kcal/mol. Furthermore, the molecular dynamics (MD) simulations show that the newly proposed compounds provide good stability with 17β-HSD1. The information obtained from this investigation will advance our knowledge of the 17β-HSD1 inhibitors and offer clues to developing new 17β-HSD1 inhibitors for future applications.

Transplantation of bone marrow mesenchymal stem cells and fibrin glue into extraction socket in maxilla promoted bone regeneration in osteoporosis rat

AIMS

Bone defect repair in osteoporosis remains a tremendous challenge for clinicians due to increased bone metabolism resulted from estrogen deficiency. This study aims to investigate the effect of bone marrow mesenchymal stem cells (BMSCs) combined with fibrin glue (FG) in the extraction socket healing process of osteoporosis rats, as well as estimate the role of estrogen receptors (ERs) played in BMSCs differentiation in vitro and in the alveolar bone reconstruction process in vivo.

MAIN METHODS

Forty rats were randomly divided into four groups, under general anesthesia, three groups underwent bilateral ovariectomy(OVX) and one group with the sham operation. Three months later, the osteogenic ability of BMSCs, isolated from healthy and osteoporosis rats, respectively, was tested. The ERα and ERβ mRNA expression in BMSCs was also evaluated by RT-PCR analysis. In vivo experiment, Micro-CT detection, histological and immunofluorescent analysis, tissue PCR was conducted up to 2, 4 and 6 weeks after transplantation of BMSCs/FG to assess the newly formed bone in the extraction socket.

KEY FINDINGS

The BMSCs from osteoporosis rats displayed weaker osteogenic potential and lower ERs expression compared with the BMSCs from healthy rats. Newly formed bone tissue filled the socket defect in BMSCs/FG treated VOX rats after six weeks, which was comparable to the sham group, while reduced ERs expression was found in the regenerated bone of the OVX group.

SIGNIFICANCE

The BMSCs seeded within FG might provide an alternative therapeutic method for repairing the extraction socket defect in osteoporosis condition.

Gut-Bone Axis: A Non-Negligible Contributor to Periodontitis

Periodontitis is a polymicrobial infectious disease characterized by alveolar bone loss. Systemic diseases or local infections, such as diabetes, postmenopausal osteoporosis, obesity, and inflammatory bowel disease, promote the development and progression of periodontitis. Accumulating evidences have revealed the pivotal effects of gut microbiota on bone health via gut-alveolar-bone axis. Gut pathogens or metabolites may translocate to distant alveolar bone via circulation and regulate bone homeostasis. In addition, gut pathogens can induce aberrant gut immune responses and subsequent homing of immunocytes to distant organs, contributing to pathological bone loss. Gut microbial translocation also enhances systemic inflammation and induces trained myelopoiesis in the bone marrow, which potentially aggravates periodontitis. Furthermore, gut microbiota possibly affects bone health via regulating the production of hormone or hormone-like substances. In this review, we discussed the links between gut microbiota and periodontitis, with a particular focus on the underlying mechanisms of gut-bone axis by which systemic diseases or local infections contribute to the pathogenesis of periodontitis.

Gut microbiome depletion and repetitive mild traumatic brain injury differentially modify bone development in male and female adolescent rats

Dysregulation of the gut microbiome has been shown to disrupt both bone formation and bone resorption in several preclinical and clinical models. However, the role of microbiome in adolescent bone development remains poorly understood. This effect of disrupted bone development may be more pronounced during adolescence, when bone development is vulnerable to environmental stimuli and external insults (e.g., antibiotic treatment and traumatic brain injury), as this is a critical window of development. Therefore, in this study, we sought to investigate the effect of repetitive mild traumatic brain injury (RmTBI) and gut microbiome depletion by antibiotic treatment on femur length and bone density in male and female adolescent Sprague Dawley rats. Rats were randomly assigned to receive standard or antibiotic autoclaved drinking water and to receive sham or RmTBIs injuries. Using micro-computed tomography (μCT), we found sexually dimorphic changes in adolescent bone development in response to microbiome depletion and RmTBI. Specifically, gut microbiome depletion stunted femur growth in males and altered cross sectional bone area (CSA), bone area fraction, and the bone volume of low and mid density bone in the distal metaphyseal region of the femur. Conversely, RmTBI and antibiotic treatment individually disrupted bone growth, bone area fraction, and bone volume of high-density bone within the distal metaphyseal region of the femur in females, but not when combined. Therefore, findings from this study indicate that gut microbiome and RmTBI may alter bone development in a sex-dependent manner during adolescence.

The Human Gut Microbiota: A Key Mediator of Osteoporosis and Osteogenesis

An expanding body of research asserts that the gut microbiota has a role in bone metabolism and the pathogenesis of osteoporosis. This review considers the human gut microbiota composition and its role in osteoclastogenesis and the bone healing process, specifically in the case of osteoporosis. Although the natural physiologic processes of bone healing and the pathogenesis of osteoporosis and bone disease are now relatively well known, recent literature suggests that a healthy microbiome is tied to bone homeostasis. Nevertheless, the mechanism underlying this connection is still somewhat enigmatic. Based on the literature, a relationship between the microbiome, osteoblasts, osteoclasts, and receptor activator of nuclear factor-kappa-Β ligand (RANKL) is contemplated and explored in this review. Studies have proposed various mechanisms of gut microbiome interaction with osteoclastogenesis and bone health, including micro-RNA, insulin-like growth factor 1, and immune system mediation. However, alterations to the gut microbiome secondary to pharmaceutical and surgical interventions cannot be discounted and are discussed in the context of clinical therapeutic consideration. The literature on probiotics and their mechanisms of action is examined in the context of bone healing. The known and hypothesized interactions of common osteoporosis drugs and the human gut microbiome are examined. Since dysbiosis in the gut microbiota can function as a biomarker of bone metabolic activity, it may also be a pharmacological and nutraceutical (i.e., pre- and probiotics) therapeutic target to promote bone homeostasis.

Breast Cancer: Targeting of Steroid Hormones in Cancerogenesis and Diagnostics

Breast cancer is the most common malignancy in women with high mortality. Sensitive and specific methods for the detection, characterization and quantification of endogenous steroids in body fluids or tissues are needed for the diagnosis, treatment and prognosis of breast cancer and many other diseases. At present, non-invasive diagnostic methods are gaining more and more prominence, which enable a relatively fast and painless way of detecting many diseases. Metabolomics is a promising analytical method, the principle of which is the study and analysis of metabolites in biological material. It represents a comprehensive non-invasive diagnosis, which has a high potential for use in the diagnosis and prognosis of cancers, including breast cancer. This short review focuses on the targeted metabolomics of steroid hormones, which play an important role in the development and classification of breast cancer. The most commonly used diagnostic tool is the chromatographic method with mass spectrometry detection, which can simultaneously determine several steroid hormones and metabolites in one sample. This analytical procedure has a high potential in effective diagnosis of steroidogenesis disorders. Due to the association between steroidogenesis and breast cancer progression, steroid profiling is an important tool, as well as in monitoring disease progression, improving prognosis, and minimizing recurrence.

The impact of oral contraceptive use on breast cancer risk: State of the art and future perspectives in the era of 4P medicine

Breast cancer is the most commonly occurring cancer in women, the second most frequent cancer overall, and it causes the greatest number of cancer-related deaths among women. The significant increased concern of breast cancer worldwide may be attributed to the prolonged life expectancy and the adoption of the western lifestyle with its related risks factors. A woman's risk for breast cancer is linked to her reproductive history and with her lifetime hormonal exposure. Among the known risk factors for breast cancer, several studies investigated the possible role of the assumption of hormonal "pills" in both breast cancer incidence and development. Nevertheless, data about the association between the assumption of oral contraceptives and breast cancer incidence are still controversial and not conclusive. Given the public health importance of breast cancer and the popularity of hormonal "pills" as contraceptive, the impact of oral contraceptive use on breast cancer risk assumes relevance from both a clinical and a social point of view. Therefore, in this review we wanted to illustrate this issue by addressing the following major themes: a) the role of sex steroid hormones in female breast development and carcinogenesis; b) the clinical impact of hormonal oral contraception according to the state of the art literature; c) the actual scientific debate and future perspectives.

Interleukin 17A: a Janus-faced regulator of osteoporosis

Interleukin (IL)-17A is a well-described mediator of bone resorption in inflammatory diseases, and postmenopausal osteoporosis is associated with increased serum levels of IL-17A. Ovariectomy (OVX) can be used as a model to study bone loss induced by estrogen deficiency and the role of IL-17A in osteoporosis development has previously been investigated using various methods to inhibit IL-17A signaling in this model. However, the studies show opposing results. While some publications reported IL-17A as a mediator of OVX-induced osteoporosis, others found a bone-protective role for IL-17 receptor signaling. In this study, we provide an explanation for the discrepancies in previous literature and show for the first time that loss of IL-17A has differential effects on OVX-induced osteoporosis; with IL-17A being important for cortical but not trabecular bone loss. Interestingly, the decrease in trabecular bone after OVX in IL-17A knock-out mice, was accompanied by increased adipogenesis depicted by elevated leptin levels. Additionally, the bone marrow adipose tissue expanded, and the bone-turnover decreased in ovariectomized mice lacking IL-17A compared to ovariectomized WT mice. Our results increase the understanding of how IL-17A signaling influences bone remodeling in the different bone compartments, which is of importance for the development of new treatments of post-menopausal osteoporosis.

Evaluation of circulating miRNA-208a-3p, miRNA-155-5p and miRNA-637 as potential non-invasive biomarkers and the possible mechanistic insights into pre- and postmenopausal osteoporotic females

BACKGROUND AND AIM

Osteoporosis is a systemic skeletal disorder that increases bone fragility and the risk of fractures. Recent studies have shown that miRNAs possess a pivotal role in osteoporosis development. This study aimed to evaluate the expression profiles of sera miRNA-208a-3p, miRNA-155-5p, and miRNA-637, to examine relation to osteoporosis and suggest the possible mechanisms of action to be used as innovative biomarkers for the diagnosis of osteoporosis among pre- and postmenopausal females.

SUBJECT AND METHOD

In this pilot study, the blood samples were collected from 140 women who were divided depending on DEXA results (T-score) as following; osteoporotic patients with T-score ≤ -2.5 and healthy controls with T-score ≥ -1. Then, each group was subdivided into pre- and postmenopausal females (each, n = 35). The expression profiles of the studied miRNAs were measured using real-time polymerase chain reaction (RT-PCR).

RESULTS

Serum miRNA-208a-3p was significantly upregulated, whereas miRNA-155-5p was markedly downregulated in the premenopausal patients compared to its respective controls. However, the miRNA-637 level showed a non-significant decrease in premenopausal patients than their controls. Moreover, the three studied miRNAs were significantly upregulated in the postmenopausal patients when compared to their respective controls, and premenopausal osteoporotic ones.

CONCLUSION

Differential expression of these miRNAs suggests their association with osteoporosis pathogenesis and elucidate their promising roles in the diagnosis of osteoporosis.

Hypogonadism, Type-2 Diabetes Mellitus, and Bone Health: A Narrative Review

One of the complications from chronic hyperglycemia and insulin resistance due to type 2 diabetes mellitus (T2DM) on the hypothalamic-pituitary-gonadal axis in men is the high prevalence of hypogonadotropic hypogonadism (HH). Both T2DM and hypogonadism are associated with impaired bone health and increased fracture risk but whether the combination results in even worse bone disease than either one alone is not well-studied. It is possible that having both conditions predisposes men to an even greater risk for fracture than either one alone. Given the common occurrence of HH or hypogonadism in general in T2DM, a significant number of men could be at risk. To date, there is very little information on the bone health men with both hypogonadism and T2DM. Insulin resistance, which is the primary defect in T2DM, is associated with low testosterone (T) levels in men and may play a role in the bidirectional relationship between these two conditions, which together may portend a worse outcome for bone. The present manuscript aims to review the available evidences on the effect of the combination of hypogonadism and T2DM on bone health and metabolic profile, highlights the possible metabolic role of the skeleton, and examines the pathways involved in the interplay between bone, insulin resistance, and gonadal steroids.

Comprehensive identification of steroid hormones in human urine based on liquid chromatography-high resolution mass spectrometry

Steroid hormones, structural derivatives of cyclopentanoperhydrophenanthrene, play important roles in modulation of many physiological processes. Comprehensive characterization of steroid hormones is valuable for understanding the process of human life activities and even disease diagnosis. Hitherto systematical characterization of steroid hormones has been rarely investigated. Here, we presented an integrated method for human urine analysis based on ultra-high performance liquid chromatography-high resolution mass spectrometry in data-dependent acquisition mode with the following parallel reaction monitoring mode. To process the data acquired by two scan modes, a comparative study of standards' fragmentation behaviors and diagnostic product ions (DPIs) were firstly conducted to facilitate the characterization of steroid hormones. The fragmentation behaviors, DPIs, elemental composition and double-bond equivalent were then simultaneously utilized for systematical characterization of steroid hormones in human urine. Consequently, fragmentation pathways and DPIs for all types of steroid hormones were comprehensively interpreted. It is interesting to find that dehydration is not restricted in the form of hydroxyl groups loss, elimination of the carbonyl oxygen could also generate dehydrated ions. Ultimately, a total of 80 and 107 steroidal hormones were characterized or tentatively identified in human urine of male and female, respectively. The proposed method is expected to provide valuable insights for chemical characterization in complex matrixes.

Structural identification and osteogenic activity of a novel heteropolysaccharide obtained from female flowers of Humulus lupulus

The flowers and infructescences of Humulus lupulus are used worldwide in beer brewing as an essential flavoring ingredient, and are also used in traditional Chinese medicine.

Gonadal Hormones and Bone

In both sexes, estrogen is one of the most essential hormones for maintaining bone integrity. Also, especially in men, androgen has beneficial effects on bone independent of estrogen. However, estrogen replacement therapy for postmenopausal women increases the risk of developing breast cancer and endometrial cancer, and androgen replacement therapy for partial androgen deficiency of the aging male increases the risk of developing prostate cancer. Various mechanisms have been proposed on the effects of gonadal hormones on bone, such as effects through cytokines including IL-6 and effects on the OPG/RANKL ratio. In addition, large amounts of new information deriving from high-throughput gene expression analysis raise the possibility of multiple other effects on bone cells. Both estrogen and androgen exert their effects via the estrogen receptor (ER) or the androgen receptor (AR), which belongs to the nuclear receptor superfamily. Compounds such as selective estrogen receptor modulators (SERMs) and selective androgen receptor modulators (SARMs) also bind ER and AR, respectively. However, SERMs and SARMs alter the ER or AR structure differently from estrogen or androgen, resulting in other downstream gene responses. As a result they can exert favorable effects on bone while suppressing the undesirable actions of estrogen and androgen. Elucidation of ER and AR ligand-specific and tissue-specific gene regulation mechanisms will also provide information on the signal transduction mechanisms of other nuclear receptors and will be valuable for the development of new therapeutic agents.

Breast osteoblast-like cells: a new biomarker for the management of breast cancer

Background

In this study, we investigated the relationship between the expression of the main in situ markers of breast cancer and the presence of breast osteoblast-like cells (BOLCs).

Methods

We collected 100 breast biopsies. Serial paraffin sections were obtained from each biopsy to perform histological classifications and immunohistochemical analyses (RUNX2, RANKL, vimentin, TGFβ, Ki67, CD44, ER, PR and HER2).

Results

Linear regression analysis showed a positive and significant correlation between the number of BOLCs and the expression of EMT-related markers (vimentin and TGFβ), Ki67 and ER. Conversely, we observed an inverse correlation between the number of CD44-positive breast cancer cells and the BOLCs. No significant differences were observed between the number of BOLCs and the HER2 scores.

Conclusions

Morphological and molecular characterisation of BOLCs can lay the foundations towards understanding the biological basis of the formation of breast microcalcifications, and breast cancer metastasis to bone. The data here reported may be useful for the identification of breast lesions with high potential to develop bone metastasis.

Cardiometabolic Risk and Female Sexuality-Part I. Risk Factors and Potential Pathophysiological Underpinnings for Female Vasculogenic Sexual Dysfunction Syndromes

INTRODUCTION

Erectile dysfunction is recognized as an opportunity for preventing cardiovascular (CV) events, and assessing the impairment of penile vascular flow by Doppler ultrasound is an important tool to ascertain CV risk. Conversely, the role of genital vascular impairment in the pathophysiology of female sexual dysfunction (FSD) remains contentious.

AIM

To focus on the current scientific support for an association between CV risk factors and female sexual health in the 1st part of a 2-part review.

METHODS

A thorough literature search of peer-reviewed publications on the associations between CV risk factors and FSD and their underlying mechanisms was performed using the PubMed database.

MAIN OUTCOME MEASURES

We present a summary of the evidence from clinical studies and discuss the possible mechanisms providing the pathophysiologic bases of vasculogenic FSD syndromes.

RESULTS

The peripheral sexual response in women is a vascular-dependent event, and evidence suggests that cardiometabolic-related perturbations in endothelial function can determine vascular insufficiency in female genital tissues. Although epidemiologic and observational studies demonstrate that the prevalence of FSD is higher in women with diabetes mellitus, a cause-effect relation between these clinical conditions cannot be assumed. Evidence on the effect of obesity, metabolic syndrome, and polycystic ovary syndrome on sexual function in women is controversial. Data on the associations of dyslipidemia and hypertension with FSD are limited.

CONCLUSION

Common cardiometabolic alterations could affect vascular function in the female genital tract. Based on limited data, there is an association between CV risk factors and female sexual health in women; however, this association appears milder than in men. Maseroli E, Scavello I, Vignozzi L. Cardiometabolic Risk and Female Sexuality-Part I. Risk Factors and Potential Pathophysiological Underpinnings for Female Vasculogenic Sexual Dysfunction Syndromes. Sex Med Rev 2018;6:508-524.

Mouse models to evaluate the role of estrogen receptor α in skeletal maintenance and adaptation

Estrogen signaling and mechanical loading have individual and combined effects on skeletal maintenance and adaptation. Previous work investigating estrogen signaling both in vitro and in vivo using global estrogen receptor α (ERα) gene knockout mouse models has provided information regarding the role of ERα in regulating bone mass and adaptation to mechanical stimulation. However, these models have inherent limitations that confound interpretation of the data. Therefore, recent studies have focused on mice with targeted deletion of ERα from specific bone cells and their precursors. Cell stage, tissue type, and mouse sex all influence the effects of ERα gene deletion. Lack of ERα in osteoblast progenitor and precursor cells generally affects the periosteum of female and male mice. The absence of ERα in differentiated osteoblasts, osteocytes, and osteoclasts in mice generally resulted in reduced cancellous bone mass, with differing reports of the effect by animal sex and greater deficiencies in bone mass typically occurring in cancellous bone in female mice. Limited data exist for the role of bone cell-specific ERα in skeletal adaptation in vivo. Cell-specific ERα gene knockout mice provide an excellent platform for investigating the function of ERα in regulating skeletal phenotype and response to mechanical loading by sex and age.

Adrenomedullin inhibits osteoclast differentiation through the suppression of receptor activator of nuclear factor-κB ligand-induced nuclear factor-κB activation in glucocorticoid-induced osteoporosis

The current study aimed to improve the understanding on the association between adrenomedullin and osteoporosis in mice with glucocorticoid-induced osteoporosis. Bone resorption and osteoporosis-associated indexes, including maximum load, stiffness, energy to failure, ultimate strength, elastic modulus, post-yield displacement and post-yield displacement, in mice with osteoporosis were analyzed in order to evaluate the effect of adrenomedullin. The receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation was investigated subsequent to treatment with adrenomedullin in vitro. The results demonstrated that adrenomedullin significantly improved bone mass loss, density, bone strength and osteoporosis disease in the mice with glucocorticoid-induced osteoporosis. In addition, adrenomedullin markedly improved the osteoporosis-associated NFATc1, TRAP, OSCAR and c-Fos expression levels. Furthermore, the current findings indicated that RANKL-mediated osteoclast differentiation was suppressed in vitro and in vivo. Notably, the data revealed that adrenomedullin significantly improved the osteoporotic symptoms through inhibition of RANKL-induced NF-κB activation in glucocorticoid-induced osteoporosis. In conclusion, adrenomedullin serves an essential role in the progression of glucocorticoid-induced osteoporosis, regulating the bone mass loss, density and strength through the NF-κB signaling pathway.

Intestinal microbiota: a potential target for the treatment of postmenopausal osteoporosis

Postmenopausal osteoporosis (PMO) is a prevalent metabolic bone disease characterized by bone loss and structural destruction, which increases the risk of fracture in postmenopausal women. Owing to the high morbidity and serious complications of PMO, many efforts have been devoted to its prophylaxis and treatment. The intestinal microbiota is the complex community of microorganisms colonizing the gastrointestinal tract. Probiotics, which are dietary or medical supplements consisting of beneficial intestinal bacteria, work in concert with endogenous intestinal microorganisms to maintain host health. Recent studies have revealed that bone loss in PMO is closely related to host immunity, which is influenced by the intestinal microbiota. The curative effects of probiotics on metabolic bone diseases have also been demonstrated. The effects of the intestinal microbiota on bone metabolism suggest a promising target for PMO management. This review seeks to summarize the critical effects of the intestinal microbiota and probiotics on PMO, with a focus on the molecular mechanisms underlying the pathogenic relationship between bacteria and host, and to define the possible treatment options.

The "soft" side of the bone: unveiling its endocrine functions

Bone has always been regarded as a merely structural tissue, a "hard" scaffold protecting all of its "soft" fellows, while they did the rest of the work. In the last few decades this concept has totally changed, and new findings are starting to portray bone as a very talkative tissue that is capable not only of being regulated, but also of regulating other organs. In this review we aim to discuss the endocrine regulation that bone has over whole-body homeostasis, with emphasis on energy metabolism, male fertility, cognitive functions and phosphate (Pi) metabolism. These delicate tasks are mainly carried out by two known hormones, osteocalcin (Ocn) and fibroblast growth factor 23 (FGF23) and possibly other hormones that are yet to be found. The extreme plasticity and dynamicity of bone allows a very fine tuning over the actions these hormones exert, portraying this tissue as a full-fledged endocrine organ, in addition to its classical roles. In conclusion, our findings suggest that bone also has a "soft side", and is daily taking care of our entire organism in ways that were unknown until the last few years.

Bone mineral density is associated with vitamin D related rs6013897 and estrogen receptor polymorphism rs4870044: The Tromsø study

Background

Bone mineral density (BMD) is determined by bone remodeling processes regulated by endocrine, autocrine and genetic mechanisms. Thus, some studies have reported that BMD is associated with single nucleotide polymorphisms (SNPs) associated with vitamin D receptor (VDR), serum 25(OH)D levels and estrogen receptor 1 (ESR1), but without consensus. Therefore, we aimed to map and compare the risk genotypes for forearm and total hip low BMD.

Methods and findings

Data were derived from a population-based study in northern Norway; the Tromsø Study. Distal forearm BMD was measured with a single x-ray absorptiometric device, while total hip BMD was measured with a dual-energy x-ray absorptiometric device. There were 7,317 and 4,082 successful analyses of distal forearm and total hip BMD, respectively, and at least one SNP of interest. We evaluated plausible BMD modulating factors and associations of BMD and SNPs related to vitamin D metabolism (FokI, Cdx2, BsmI, rs2298850, rs10741657, rs3794060, rs6013897), ApaI-BsmI-TaqI haplotypes and ESR1 SNP rs4870044.

Results

Age, BMI, physical activity and smoking were significantly associated with BMD. In a linear regression model with adjustment for age and gender and with the major homozygote as reference, rs6013897 had a standardized beta coefficient (β) of –0.031 (P = 0.024) for total hip BMD. β for ESR1 SNP rs4870044 was –0.016 (P = 0.036) for forearm BMD and –0.034 (P = 0.015) for total hip BMD. The other SNPs nor serum 25(OH)D were significantly associated with BMD.

Conclusions

Both forearm and total hip BMD were associated with ESR1 SNP rs4870044. Of the vitamin D–related genes, only CYP24A1 gene rs6013897 was associated with total hip BMD, but the association was weak and needs confirmation in other studies. Serum 25(OH)D was not associated with BMD in our population, probably due to the generally sufficient vitamin D levels in the population.

Design and synthesis of novel selective estrogen receptor degradation inducers based on the diphenylheptane skeleton

Estrogen receptors (ERs) are a family of nuclear receptors (NRs) that regulate physiological effects such as reproduction and bone homeostasis. It has been reported that approximately 70% of human breast cancers are hormone-dependent and ERα-positive. Recently, novel anti-breast cancer drugs based on different mechanisms of action have received significant attention. In this article, we have designed and synthesized a selective ER degradation inducer based on the diphenylheptane skeleton. Western blotting analysis revealed that PBP-NC10 degraded ERα through the ubiquitin-proteasome system. We also performed computational docking analysis to predict the binding mode of PBP-NC10 to ERα.

Bone remodeling and regulating biomarkers in women at the time of breast cancer diagnosis

PURPOSE

The majority of breast cancer patients receive endocrine therapy, including aromatase inhibitors known to cause increased bone resorption. Bone-related biomarkers at the time of breast cancer diagnosis may predict future risk of osteoporosis and fracture after endocrine therapy.

METHODS

In a large population of 2,401 female breast cancer patients who later underwent endocrine therapy, we measured two bone remodeling biomarkers, TRAP5b and BAP, and two bone regulating biomarkers, RANKL and OPG, in serum samples collected at the time of breast cancer diagnosis. We analyzed these biomarkers and their ratios with patients' demographic, lifestyle, clinical tumor characteristics, as well as bone health history.

RESULTS

The presence of bone metastases, prior bisphosphonate (BP) treatment, and blood collection after chemotherapy had a significant impact on biomarker levels. After excluding these cases and controlling for blood collection time, several factors, including age, race/ethnicity, body mass index, physical activity, alcohol consumption, smoking, and hormonal replacement therapy, were significantly associated with bone biomarkers, while vitamin D or calcium supplements and tumor characteristics were not. When prior BP users were included in, recent history of osteoporosis and fracture was also associated.

CONCLUSIONS

Our findings support further investigation of these biomarkers with bone health outcomes after endocrine therapy initiation in women with breast cancer.

Bone Density and Dental External Apical Root Resorption

When orthodontic patients desire shorter treatment times with aesthetic results and long-term stability, it is important for the orthodontist to understand the potential limitations and problems that may arise during standard and/or technology-assisted accelerated treatment. Bone density plays an important role in facilitating orthodontic tooth movement (OTM), such that reductions in bone density can significantly increase movement velocity. Lifestyle, genetic background, environmental factors, and disease status all can influence a patients' overall health and bone density. In some individuals, these factors may create specific conditions that influence systemic-wide bone metabolism. Both genetic variation and the onset of a bone-related disease can influence systemic bone density and local bone density, such as observed in the mandible and maxilla. These types of localized density changes can affect the rate of OTM and may also influence the risk of unwanted outcomes, i.e., the occurrence of dental external apical root resorption (EARR).

Is There an Association Between Bone Mineral Density and Mammographic Density? A Systematic Review

INTRODUCTION

Both bone mineral density (BMD) and breast density are related to reproductive hormone levels. This suggests that BMD and breast density could be meaningfully associated, and serve as surrogate markers for breast cancer risk. However, few studies have investigated the association of BMD with percent mammographic density, making it difficult to draw meaningful conclusions.

MATERIALS AND METHODS

We conducted a systematic review of studies published in electronic databases till April 2016 using the following search terms: "bone density," "bone mineral density," "mammographic breast density," "breast density," and "mammographic density." We identified 203 articles, of which 8 met the inclusion criteria for this review.

RESULTS

BMD does not appear to be associated with percent mammographic density. BMD at the spine was weakly positively associated with percent mammographic density among postmenopausal women who were not hormone users, while BMD at the hip and legs was positively associated with percent mammographic density among premenopausal women. On the other hand, one study reported an inverse association of BMD at the spine and hip with percent mammographic density among perimenopausal women.

CONCLUSION

In this review, we found no evidence of an association between BMD and percent mammographic density.

The Effects of Dietary Supplements of Calcium, Vitamin D and Estrogen Hormone on Serum Levels of OPG and RANKL Cytokines and their Relationship with Increased Bone Density in Rats

INTRODUCTION

Osteoprotegerin (OPG)-Receptor activator of nuclear factor kappa-B ligand (RANKL) pathway is one of the contributing factors in the regulation of osteogenesis and bone resorption routes.

AIM

The purpose of this study was to evaluate the effects of various dietary supplements on this pathway.

MATERIALS AND METHODS

The samples for this study (24 newborn rats) were divided in three groups according to the experiment applied for each group. Rats were given special diet according to their group plan for six weeks. Blood samples were collected to measure their serum levels of OPG and RANKL and all organs of rats were used to measure their bone density too. The results were analysed using appropriate statistical analysing tests.

RESULTS

Levels of whole-body bone mineral density in calcium plus vitamin D plus Estrogen (Ca + D + E) group and calcium plus vitamin D (Ca + D) group were significantly increased compared to control group. Mineral density was highest in calcium plus vitamin D plus Estrogen group and was about 0.1357 g/cm2. RANKL had a significant decrease in calcium plus vitamin D plus Estrogen group compared to control and calcium plus vitamin D groups. There was a significant increase in the mean calcium and OPG in both experimental groups rather than control. Also, significant increase in estrogen was observed in Ca + D group than the control group.

CONCLUSION

The results showed that intake of calcium and vitamin D and estrogen at determined dose led to an increase in OPG and RANKL cytokines reduction which ultimately led to an increase in bone mineral density. But Ca, D and E synergies were more effective in increasing bone mineral density compared to only the use of Ca and D.

The Estrogen Receptor α-Cistrome Beyond Breast Cancer

Although many tissues express estrogen receptor (ER)α, most studies focus on breast cancer where ERα occupies just a small fraction of its total repertoire of potential DNA-binding sites, based on sequence. This raises the question: Can ERα occupy these other potential binding sites in a different context? Ligands, splice variants, posttranslational modifications, and acquired mutations of ERα affect its conformation, which may alter chromatin interactions. To date, literature describes the DNA-binding sites of ERα (the ERα cistrome) in breast, endometrium, liver, and bone, in which the receptor mainly binds to enhancers. Chromosomal boundaries provide distinct areas for dynamic gene regulation between tissues, where the usage of enhancers deviates. Interactions of ERα with enhancers and its transcriptional complex depend on the proteome, which differs per cell type. This review discusses the biological variables that influence ERα cistromics, using reports from human specimens, cell lines, and mouse tissues, to assess whether ERα genomics in breast cancer can be translated to other tissue types.

Glucosamines Attenuate Bone Loss Due to Menopause by Regulating Osteoclast Function in Ovariectomized Mice

The effect of glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) on bone metabolism in ovariectomized (OVX) mice was studied. After 12 weeks of feeding with 0.2% GlcN and 0.2% GlcNAc, the femoral bone mineral density in OVX mice was significantly increased compared with that in OVX mice fed the control diet. Histomorphometric analysis of the tibia indicated that the rates of osteogenesis and bone resorption were reduced due to the GlcN diet. The erosion depth of osteoclasts on the tibia in GlcN- and GlcNAc-fed OVX mice was significantly lower than that in the control OVX mice. The number of tartrate-resistant acid phosphatase-positive osteoclasts induced from bone marrow stem cells isolated from GlcN-fed OVX mice was significantly lower than that from control OVX mice. A loss of uterine weight and higher serum calcium concentration in the GlcN- and GlcNAc-fed OVX mice were observed. The results suggest that the intake of GlcN suppresses bone loss by inhibiting osteoclast differentiation and activity in a nonestrogenic manner.

Osteoprotective Effects of Estrogen in the Maxillary Bone Depend on ERα

Estrogen deficiency results in disruption of maxillary alveolar bone microarchitecture. Most of the actions of estrogen in long bones occur via estrogen receptor α (ERα). However, the function of ERα in the maxillary bone has not been defined. We aimed to investigate the role and underlying mechanisms of ERα in the physiological and mechanically induced alveolar bone remodeling in female and male mice. Wild-type (WT) and ERα−/− (ERKOα) mice were subjected to mechanically stimulated bone remodeling by inducing orthodontic tooth movement (OTM). The maxillary bone was analyzed using histomorphometric analysis, micro–computed tomography, quantitative polymerase chain reaction, and energy-dispersive spectroscopy. Bone marrow cells (BMCs) from WT and ERKOα mice were tested for their capacity to differentiate into osteoblasts and osteoclasts. Both male and female ERKOα mice exhibited marked reduction of alveolar bone mass and increased OTM. This response was associated with an increased number of osteoclasts and reduced number of apoptotic cells and osteoblasts in the periodontium and alveolar bone. Consistently, ERKOα mice exhibited lower levels of calcium in bone and increased expression of IL-33 (interleukin-33), TNF-α (tumor necrosis factor α), and IL-1β (interleukin-1β) and decreased expression of dentin matrix acidic phosphoprotein and alkaline phosphatase in periodontal tissues. Moreover, the differentiation of osteoclasts and osteoblasts in vitro was significantly higher in BMCs obtained from ERKOα. ERα is required to maintain the microarchitecture of maxillary alveolar bone. This process is linked to bone cell differentiation and apoptosis, as well as local production of inflammatory molecules such as IL-33, TNF-α, and IL-1β.

Impact and risk factors of post-stroke bone fracture

Bone fracture occurs in stroke patients at different times during the recovery phase, prolonging recovery time and increasing medical costs. In this review, we discuss the potential risk factors for post-stroke bone fracture and preventive methods. Most post-stroke bone fractures occur in the lower extremities, indicating fragile bones are a risk factor. Motor changes, including posture, mobility, and balance post-stroke contribute to bone loss and thus increase risk of bone fracture. Bone mineral density is a useful indicator for bone resorption, useful to identify patients at risk of post-stroke bone fracture. Calcium supplementation was previously regarded as a useful treatment during physical rehabilitation. However, recent data suggests calcium supplementation has a negative impact on atherosclerotic conditions. Vitamin D intake may prevent osteoporosis and fractures in patients with stroke. Although drugs such as teriparatide show some benefits in preventing osteoporosis, additional clinical trials are needed to determine the most effective conditions for post-stroke applications.

An Evolutionary and Life-History Perspective on Osteoporosis

Osteoporosis is a systemic disease characterized by bone mass reductions and heightened fracture risk; its global prevalence rates are projected to increase precipitously over the next few decades. Evolutionary and life-history perspectives have proven valuable for offering a different lens with which to consider the etiologies of common chronic diseases, and in this review, these approaches are applied to osteoporosis. Although there are many perspectives on human susceptibility to bone loss, this article explores the most prominent and empirically studied theories. Osteoporosis is considered within the context of theories on aging (e.g., antagonistic pleiotropy, disposable soma) and mismatch theory. Female vulnerability is considered within a separate evolutionary framework and has been articulated as a trade-off between reproduction and skeletal health. Recent advancements in bone imaging techniques for skeletal and living human and nonhuman primate populations (i.e., CT scans, ultrasonometry) have facilitated huge strides in contextualizing osteoporosis within evolutionary theory.

Non-linear pattern of age-specific bone mineral density and related factors in women: data from the 5th Korea National Health and Nutrition Examination Survey

Age-specific bone mineral density (BMD) of Korean women showed a nonlinear pattern. According to our study, this pattern could be mainly attributed to the nonlinear effects of body composition. Interventions targeting these factors in premenopausal women could be critical for achieving peak BMD.

PURPOSE

The patterns of age-specific bone mineral density (BMD) of femur and spine in women showed a non-unidirectional decrease, with ups and downs around the point of achieving peak BMD, that are not evident in men. We investigated the factors associated with these age-specific BMD in women using linear and nonlinear models.

METHODS

A total of 4681 women recruited during the 5th Korean National Health and Nutrition Examination Survey 2010-2011 (KNHANES V) were included. A range of related factors were considered including body compositional, reproductive, and socio-behavioral factors. Age-specific BMD was demonstrated using a generalized additive model (GAM) with smoothing spline transformation.

RESULTS

Age, lean body mass, fat mass, and age at menarche were significant predictors of BMD in premenopausal women. The GAM plot of BMD according to age revealed two peaks for total femur, femoral neck, and lumbar spine. After adjustment for body compositional factors, the peaks flattened. In the full model, the pattern for lumbar spine showed a single peak around the mid-40s. The GAM showed a generally better performance than the linear model for BMD at all three sites. Reduced models that included only lean body mass and fat mass best explained the variance of BMD in GAMs.

CONCLUSIONS

The BMD of Korean women in reproductive period could be largely attributed to the nonlinear effects of age and body compositional factors. Intervention targeting these factors could be critical for maintaining peak BMD.

Relationship between bone mineral density, its associated physiological factors, and tooth loss in postmenopausal Korean women

BACKGROUND

Previous studies have proposed a relationship between bone mineral density (BMD) and oral health. However, the relationship between BMD and tooth loss in female individuals is not yet well understood. Therefore, the aim of this study was to assess the association between BMD, including its related physiological factors, and tooth loss among postmenopausal women in Korea.

METHODS

A total of 3,992 postmenopausal women aged 50 years or above were selected from the Fourth and Fifth Korea National Health and Nutrition Examination Surveys, which were cross-sectional in design and conducted from 2008 to 2011. The participants' BMD and number of teeth were assessed by radiologists and dentists. Socioeconomic characteristics and female-related physiological factors, including menarche age, duration of menopause, number of pregnancies, age at first child's birth, and duration of oral contraceptive or female hormone use, were surveyed.

RESULTS

Participants who had lower BMD had significantly fewer teeth (p < 0.001). Female-related physiological factors, including the duration of menopause, number of pregnancies, age at first child's birth, duration of oral contraceptive or female hormone use, and calcium intake level, showed a significant relationship with the number of teeth. Using multiple regression analysis, BMD, duration of menopause, age at first child's birth, and duration of female hormone use significantly influenced the number of teeth.

CONCLUSIONS

BMD and its related physiological factors in female individuals showed a significant relationship with the number of teeth in postmenopausal Korean women, implicating osteoporosis as a risk factor for tooth loss in postmenopausal women.

17β-Estradiol induces odontoblastic differentiation via activation of the c-Src/MAPK pathway in human dental pulp cells

The present study is aimed at investigating the effects of the exogenous estrogen 17β-estradiol (E2) on odontoblastic differentiation in human dental pulp cells (HDPCs) immotalized with hTERT gene and their molecular mechanism. Proliferation was detected by BrdU assay, and odontoblast differentiation induction was evaluated by the expression of dentin sialophosphoprotein (DSPP), dentin sialoprotein (DSP) and dentin matrix protein1 (DMP1), and alkaline phosphatase (ALP) activity and mineralization. Estrogen receptor-α (ER-α), c-Src, and mitogen-activated protein kinases (MAPKs) were examined and their inhibitors were used to determine the roles on odontogenic induction. E2 significantly promoted the HDPC proliferation, which was mediated by extracellular signal-related kinase 1/2. E2 upregulated DSPP, DSP, and DMP1 as the odontogenic differentiation markers and enhanced ALP activity and mineralization. E2 increased phosphorylation of ER-α and fulvestrant, an ER downregulator, significantly downregulated DSPP, DMP1, and DSP induced by E2. Moreover, E2 treatment activated c-Src and MAPKs upon odontogenic induction, whereas chemical inhibition of c-Src and MAPKs decreased expression of DSPP, DMP1, and DSP and mineralization augmented by E2. Moreover, fulvestrant reduced E2-induced phosphorylation of c-Src and MAPK and inhibition of c-Src by PP2 attenuated activation of MAPKs during E2-induced odontoblastic differentiation. Taken together, these results indicated that E2 stimulates odontoblastic differentiation of HDPCs via coordinated regulation of ER-α, c-Src, and MAPK signaling pathways, which may play a key role in the regeneration of dentin.

Hormonal regulation of hematopoietic stem cells and their niche: a focus on estrogen

Self-renewal and differentiation are hallmarks of stem cells and controlled by various intrinsic and extrinsic factors. Increasing evidence indicates that estrogen (E2), the primary female sex hormone, is involved in regulating the proliferation and lineage commitment of adult and pluripotent stem cells as well as modulating the stem cell niche. Thus, a detailed understanding of the role of E2 in behavior of stem cells may help to improve their therapeutic potential. Recently, it has been reported that E2 promotes cell cycle activity of hematopoietic stem and progenitor cells and induces them to megakaryocyte-erythroid progenitors during pregnancy. This study paves the way towards a previously unexplored endocrine mechanism that controls stem cell behavior. In this review, we will focus on the scientific findings regarding the regulatory effects of E2 on the hematopoietic system including its microenvironment.

Multiple hormonal dysregulation as determinant of low physical performance and mobility in older persons

Mobility-disability is a common condition in older individuals. Many factors, including the age-related hormonal dysregulation, may concur to the development of disability in the elderly. In fact, during the aging process it is observed an imbalance between anabolic hormones that decrease (testosterone, dehydroepiandrosterone sulphate (DHEAS), estradiol, insulin like growth factor-1 (IGF-1) and Vitamin D) and catabolic hormones (cortisol, thyroid hormones) that increase. We start this review focusing on the mechanisms by which anabolic and catabolic hormones may affect physical performance and mobility. To address the role of the hormonal dysregulation to mobility-disability, we start to discuss the contribution of the single hormonal derangement. The studies used in this review were selected according to the period of time of publication, ranging from 2002 to 2013, and the age of the participants (≥65 years). We devoted particular attention to the effects of anabolic hormones (DHEAS, testosterone, estradiol, Vitamin D and IGF-1) on both skeletal muscle mass and strength, as well as other objective indicators of physical performance. We also analyzed the reasons beyond the inconclusive data coming from RCTs using sex hormones, thyroid hormones, and vitamin D (dosage, duration of treatment, baseline hormonal values and reached hormonal levels). We finally hypothesized that the parallel decline of anabolic hormones has a higher impact than a single hormonal derangement on adverse mobility outcomes in older population. Given the multifactorial origin of low mobility, we underlined the need of future synergistic optional treatments (micronutrients and exercise) to improve the effectiveness of hormonal treatment and to safely ameliorate the anabolic hormonal status and mobility in older individuals.

Association of serum inorganic phosphate with sex steroid hormones and vitamin D in a nationally representative sample of men

Defects in bone regulatory pathways have been linked to chronic diseases including cardiovascular disease and cancer. In men, a link between bone metabolism and gonadal hormones has been suggested. However, to date, there is lack of evidence on the association between serum inorganic phosphate (Pi) and sex steroid hormones. The objective of this study was to investigate the association between Pi, sex steroid hormones and a known Pi metabolic regulator, vitamin D, in men in the National Health and Nutrition Examination Survey III (NHANES III). From NHANES III, we selected 1412 men aged 20+ who participated in the morning session of Phase I (1988-1991) with serum measurements of Pi, sex hormones, and vitamin D. Multivariable linear regression was used to calculate crude and geometric mean Pi by total and estimated free testosterone and estradiol, sex hormone-binding globulin, androstanediol glucuronide (AAG), and vitamin D. Similar analyses were performed while stratifying by race/ethnicity and vitamin D levels. We found a lack of statistically significant difference in geometric means of Pi across quintiles of concentrations of sex hormones, indicating a tight regulation of Pi. However, Pi levels were inversely associated with calculated free testosterone in non-Hispanic black men, with geometric mean levels of Pi of 1.16 and 1.02 ng/mL for those in the lowest and highest quintiles of free testosterone, respectively (p-trend < 0.05). A similar but weaker pattern was seen between total testosterone and Pi. An inverse association was also seen between AAG and Pi in men with vitamin D concentration below the median (<24.2 ng/mL). No associations were observed among men with vitamin D levels at or above the median. Our findings suggest a weak link among sex hormones, vitamin D, and Pi in men. The observed effects of race/ethnicity and vitamin D indicate a complex association involving various regulators of Pi homeostasis.

Role of Fas and Treg cells in fracture healing as characterized in the fas-deficient (lpr) mouse model of lupus

Previous studies showed that loss of tumor necrosis factor α (TNFα) signaling delayed fracture healing by delaying chondrocyte apoptosis and cartilage resorption. Mechanistic studies showed that TNFα induced Fas expression within chondrocytes; however, the degree to which chondrocyte apoptosis is mediated by TNFα alone or dependent on the induction of Fas is unclear. This question was addressed by assessing fracture healing in Fas-deficient B6.MRL/Fas(lpr) /J mice. Loss of Fas delayed cartilage resorption but also lowered bone fraction in the calluses. The reduced bone fraction was related to elevated rates of coupled bone turnover in the B6.MRL/Fas(lpr) /J calluses, as evidenced by higher osteoclast numbers and increased osteogenesis. Analysis of the apoptotic marker caspase 3 showed fewer positive chondrocytes and osteoclasts in calluses of B6.MRL/Fas(lpr) /J mice. To determine if an active autoimmune state contributed to increased bone turnover, the levels of activated T cells and Treg cells were assessed. B6.MRL/Fas(lpr) /J mice had elevated Treg cells in both spleens and bones of B6.MRL/Fas(lpr) /J but decreased percentage of activated T cells in bone tissues. Fracture led to ∼30% to 60% systemic increase in Treg cells in both wild-type and B6.MRL/Fas(lpr) /J bone tissues during the period of cartilage formation and resorption but either decreased (wild type) or left unchanged (B6.MRL/Fas(lpr) /J) the numbers of activated T cells in bone. These results show that an active autoimmune state is inhibited during the period of cartilage resorption and suggest that iTreg cells play a functional role in this process. These data show that loss of Fas activity specifically in chondrocytes prolonged the life span of chondrocytes and that Fas synergized with TNFα signaling to mediate chondrocyte apoptosis. Conversely, loss of Fas systemically led to increased osteoclast numbers during later periods of fracture healing and increased osteogenesis. These findings suggest that retention of viable chondrocytes locally inhibits osteoclast activity or matrix proteolysis during cartilage resorption.

Effects of radiation on bone

Ionizing radiation produces its deleterious biologic effects by both direct (DNA strand breaks) and indirect processes (formation of free oxygen radicals). Mitotically active cells are more susceptible to the detrimental effects of ionizing radiation. These effects are most severe locally within the treatment field but can also occur systemically, possibly reflecting hormonal influences and inflammatory cytokine mediators. Specific bone complications of radiation include osteopenia, growth arrest, fracture and malignancy. Some of these complications, such as osteopenia, are reversible and severity is dose dependent. Insufficiency fractures are a common complication after radiation therapy and generally affect those bones under most physiologic stress and with the highest ratio of trabecular to cortical bone. Familiarity with the radiographic appearance of irradiated bone, including computed tomography (CT) and magnetic resonance imaging (MRI), will improve image interpretation and facilitate accurate diagnosis.

Effects of alcohol on the endocrine system

Chronic consumption of a large amount of alcohol disrupts the communication between nervous, endocrine, and immune system and causes hormonal disturbances that lead to profound and serious consequences at physiologic and behavioral levels. These alcohol-induced hormonal dysregulations affect the entire body and can result in various disorders such as stress abnormalities, reproductive deficits, body growth defect, thyroid problems, immune dysfunction, cancers, bone disease, and psychological and behavioral disorders. This review summarizes the findings from human and animal studies that provide consistent evidence on the various effects of alcohol abuse on the endocrine system.

Steering the osteoclast through the demineralization-collagenolysis balance

There is a lot of interest for how and how much osteoclasts resorb bone. However, little is known about the mechanism which controls the orientation and the duration of a resorptive event, thereby determining the specific geometry of a cavitation. Here we show that the relative rate of collagenolysis vs. demineralization plays a critical role in this process. First we observed that when culturing osteoclasts on bone slices, excavations appeared either as round pits containing demineralized collagen, or as elongated trenches without demineralized collagen. This suggests that round pits are generated when collagen degradation is slower than demineralization, and trenches when collagen degradation is as fast as demineralization. Next we treated the osteoclasts with a low dose of a carbonic anhydrase inhibitor to slightly decrease the rate of demineralization, thereby allowing collagen degradation to proceed as fast as demineralization. This resulted in about a two-fold increase of the proportion of trenches, thus supporting our hypothesis. The same result was obtained if facilitating collagen degradation by pre-treating the bone slices with NaOCl. In contrast, when decreasing the rate of collagenolysis vs. demineralization by the addition of a cathepsin K specific inhibitor, the proportion of trenches fell close to 0%, and furthermore the round pits became almost half as deep. These observations lead to a model where the osteoclast resorption route starts perpendicularly to the bone surface, forming a pit, and continues parallel to the bone surface, forming a trench. Importantly, we show that the progress of the osteoclast along this route depends on the balance between the rate of collagenolysis and demineralization. We propose that the osteocytes and bone lining cells surrounding the osteoclast may act on this balance to steer the osteoclast resorptive activity in order to give the excavations a specific shape.