Age-related changes in biochemical markers of bone turnover and gonadotropin levels and their relationship among Chinese adult women

Bu-Shen-Ning-Xin decoction inhibits macrophage activation to ameliorate premature ovarian insufficiency-related osteoimmune disorder via FSH/FSHR pathway

Limited studies are associated with premature ovarian insufficiency (POI)-related osteoimmune disorder currently. Bu-Shen-Ning-Xin decoction (BSNXD) displayed a favorable role in treating postmenopausal osteoporosis. However, its impact on the POI-related osteoimmune disorder remains unclear. The study primarily utilized animal experiments and network pharmacology to investigate the effects and underlying mechanisms of BSNXD on the POI-related osteoimmune disorder. First, a 4-vinylcyclohexene dioxide (VCD)-induced POI murine model was conducted to explore the therapeutical action of BSNXD. Second, we analyzed the active compounds of BSNXD and predicted their potential mechanisms for POI-related osteoimmune disorder via network pharmacology, further confirmed by molecular biology experiments. The results demonstrated that VCD exposure led to elevated follicle-stimulating hormone (FSH) levels, a 50% reduction in the primordial follicles, bone microstructure changes, and macrophage activation, indicating an osteoimmune disorder. BSNXD inhibited macrophage activation and osteoclast differentiation but did not affect serum FSH and estradiol levels in the VCD-induced POI model. Network pharmacology predicted the potential mechanisms of BSNXD against the POI-related osteoimmune disorder involving tumor necrosis factor α and MAPK signaling pathways, highlighting BSNXD regulated inflammation, hormone, and osteoclast differentiation. Further experiments identified BSNXD treatment suppressed macrophage activation via downregulating FSH receptor (FSHR) expression and inhibiting the phosphorylation of ERK and CCAAT enhancer binding proteins β. In conclusion, BSNXD regulated POI-related osteoimmune disorder by suppressing the FSH/FSHR pathway to reduce macrophage activation and further inhibiting osteoclastogenesis.

Peripheral extracellular vesicles in neurodegeneration: pathogenic influencers and therapeutic vehicles

Neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis epitomize a class of insidious and relentless neurological conditions that are difficult to cure. Conventional therapeutic regimens often fail due to the late onset of symptoms, which occurs well after irreversible neurodegeneration has begun. The integrity of the blood-brain barrier (BBB) further impedes efficacious drug delivery to the central nervous system, presenting a formidable challenge in the pharmacological treatment of NDDs. Recent scientific inquiries have shifted focus toward the peripheral biological systems, investigating their influence on central neuropathology through the lens of extracellular vesicles (EVs). These vesicles, distinguished by their ability to breach the BBB, are emerging as dual operatives in the context of NDDs, both as conveyors of pathogenic entities and as prospective vectors for therapeutic agents. This review critically summarizes the burgeoning evidence on the role of extracerebral EVs, particularly those originating from bone, adipose tissue, and gut microbiota, in modulating brain pathophysiology. It underscores the duplicity potential of peripheral EVs as modulators of disease progression and suggests their potential as novel vehicles for targeted therapeutic delivery, positing a transformative impact on the future landscape of NDD treatment strategies. Search strategy A comprehensive literature search was conducted using PubMed, Web of Science, and Scopus from January 2000 to December 2023. The search combined the following terms using Boolean operators: "neurodegenerative disease" OR "Alzheimer's disease" OR "Parkinson's disease" OR "Amyotrophic lateral sclerosis" AND "extracellular vesicles" OR "exosomes" OR "outer membrane vesicles" AND "drug delivery systems" AND "blood-brain barrier". MeSH terms were employed when searching PubMed to refine the results. Studies were included if they were published in English, involved human subjects, and focused on the peripheral origins of EVs, specifically from bone, adipose tissue, and gut microbiota, and their association with related diseases such as osteoporosis, metabolic syndrome, and gut dysbiosis. Articles were excluded if they did not address the role of EVs in the context of NDDs or did not discuss therapeutic applications. The titles and abstracts of retrieved articles were screened using a dual-review process to ensure relevance and accuracy. The reference lists of selected articles were also examined to identify additional relevant studies.

Pituitary crosstalk with bone, adipose tissue and brain

Traditional textbook physiology has ascribed unitary functions to hormones from the anterior and posterior pituitary gland, mainly in the regulation of effector hormone secretion from endocrine organs. However, the evolutionary biology of pituitary hormones and their receptors provides evidence for a broad range of functions in vertebrate physiology. Over the past decade, we and others have discovered that thyroid-stimulating hormone, follicle-stimulating hormone, adrenocorticotropic hormone, prolactin, oxytocin and arginine vasopressin act directly on somatic organs, including bone, adipose tissue and liver. New evidence also indicates that pituitary hormone receptors are expressed in brain regions, nuclei and subnuclei. These studies have prompted us to attribute the pathophysiology of certain human diseases, including osteoporosis, obesity and neurodegeneration, at least in part, to changes in pituitary hormone levels. This new information has identified actionable therapeutic targets for drug discovery.

Association of follicle-stimulating hormone with bone turnover markers and bone mineral density in Chinese women across the menopausal transition

BACKGROUND

Elevated follicle-stimulating hormone (FSH) is associated with an increased risk of postmenopausal osteoporosis. This study investigated the association of serum FSH with bone turnover markers (BTMs) and bone mineral density (BMD) in healthy women undergoing menopausal transition.

METHODS

A total of 487 healthy women (age 35-65 years, 50 ± 8.5 years) were enrolled in this study. Serum FSH, BTMs, and BMD at lumbar spine and total hip were measured in these subjects.

RESULTS

Follicle-stimulating hormone was positively correlated with various BTMs (r = 0.339-0.583, all p < 0.001) and negatively correlated with lumbar spine and total hip BMD (r = -0.629 and -0.514, all p < 0.001). After adjusting for age and body mass index, the partial correlation coefficients of FSH with BTMs and BMD remained significant. Estimating from the regression equation, for every 10 IU/L increase in serum FSH, BTMs increased by 0.38-3.6 units, and BMD decreased by 0.03-0.05 g/cm2 , respectively. Multiple linear regression analysis showed that FSH was a positive factor for serum bone-specific alkaline phosphatase, osteocalcin, and N-telopeptide of collagen type 1 (β = 0.188-0.403, all p < 0.001), and a negative factor for lumbar spine BMD and serum C-telopeptide of collagen type 1 (β = -0.629 and -0.183, all p < 0.001).

CONCLUSIONS

This study suggests that serum FSH levels are an independent risk factor for BTMs and BMD in menopause-transitioning women, particularly for serum BAP and lumbar spine BMD.

Bone circuitry and interorgan skeletal crosstalk

The past decade has seen significant advances in our understanding of skeletal homeostasis and the mechanisms that mediate the loss of bone integrity in disease. Recent breakthroughs have arisen mainly from identifying disease-causing mutations and modeling human bone disease in rodents, in essence, highlighting the integrative nature of skeletal physiology. It has become increasingly clear that bone cells, osteoblasts, osteoclasts, and osteocytes, communicate and regulate the fate of each other through RANK/RANKL/OPG, liver X receptors (LXRs), EphirinB2-EphB4 signaling, sphingolipids, and other membrane-associated proteins, such as semaphorins. Mounting evidence also showed that critical developmental pathways, namely, bone morphogenetic protein (BMP), NOTCH, and WNT, interact each other and play an important role in postnatal bone remodeling. The skeleton communicates not only with closely situated organs, such as bone marrow, muscle, and fat, but also with remote vital organs, such as the kidney, liver, and brain. The metabolic effect of bone-derived osteocalcin highlights a possible role of skeleton in energy homeostasis. Furthermore, studies using genetically modified rodent models disrupting the reciprocal relationship with tropic pituitary hormone and effector hormone have unraveled an independent role of pituitary hormone in skeletal remodeling beyond the role of regulating target endocrine glands. The cytokine-mediated skeletal actions and the evidence of local production of certain pituitary hormones by bone marrow-derived cells displays a unique endocrine-immune-skeletal connection. Here, we discuss recently elucidated mechanisms controlling the remodeling of bone, communication of bone cells with cells of other lineages, crosstalk between bone and vital organs, as well as opportunities for treating diseases of the skeleton.

Roles of Follicle-Stimulating Hormone on Bone Metabolism in Late Postmenopausal Women

BACKGROUND

The effects of elevated follicle-stimulating hormone (FSH) levels on physiological changes in the bone remain unclear. This study aimed to clarify the association between FSH concentrations and bone mineral density (BMD) and bone turnover markers (BTM) in late postmenopausal women.

METHODS

A total of 169 Korean women were enrolled. The participants' ages ranged from 60 to 84 years (mean age, 69.0±5.1) and reported a mean duration of 19.4±6.6 years since menopause (YSM). The participants showed an average body mass index (BMI) of 24.4±2.8 kg/m2. Age, YSM, estradiol, testosterone, and BMI were confounders in the Pearson's partial correlation. A test for trends across the quartiles of FSH levels was performed for each variable.

RESULTS

The mean FSH and estradiol concentrations were 61.5 IU/L and 2.9 pg/mL, respectively. Serum FSH concentration was not significantly associated with BMD (lumbar, r=0.09, P=0.30; total hip, r=0.00, P=0.96; and femoral neck, r=0.05, P=0.62). BTM across the FSH quartiles did not show any trend association (bone-specific alkaline phosphate, P=0.31; crosslinked C-terminal telopeptide of type I collagen, P=0.90). Instead, FSH levels were negatively correlated with BMI (r=-0.34, P=0.00). In the multivariate regression model adjusted for age, testosterone, and estradiol, only BMI showed a negative value across the FSH quartiles (β coefficient -0.11, P=0.00).

CONCLUSIONS

This study identified that high FSH concentrations were not associated with bone loss or high bone turnover in women in the late postmenopausal period.

Sexual dimorphism in the relation between sex hormones and osteoporosis in patients with type 2 diabetes mellitus

INTRODUCTION

To investigate the association between sex hormones and osteoporosis in type 2 diabetic mellitus (T2DM) patients.

MATERIALS AND METHODS

We performed a retrospective study in patients with T2DM. The patients were assigned into three groups (normal bone mineral density, osteopenia, and osteoporosis) in both sexes. The clinical characteristics, bone metabolic markers, and sex hormones were compared. The relationship between the sex hormones and osteoporosis was analyzed by ordinary regression analysis. Statistical analysis was performed using SPSS 26.0.

RESULTS

A total of 795 T2DM patients (446 men ≥ 50 years old and 349 postmenopausal women) were identified and analyzed. The osteoporosis group had the lowest estradiol level in men (P = 0.013) and the highest follicle-stimulating hormone (FSH) level in women (P = 0.042). In the multivariate analysis, men with lower estradiol levels (< 87.96 pmol/L) had a nearly 1.6-fold increased risk for osteoporosis than those with the higher estradiol levels (> 122.82 pmol/L). In addition, women with lower FSH (< 41.17 IU/L) had nearly 0.6-fold for osteoporosis compared to those with higher FSH (> 60.83 IU/L) after adjusting for age, duration of T2DM, body mass index, pulse pressure, creatinine clearance, glycosylated hemoglobin, fasting C-peptide, and estradiol (in FSH) or FSH (in estradiol).

CONCLUSION

In T2DM, the estrogen level was negatively correlated with osteoporosis in men, and the FSH level was positively correlated with the osteoporosis in women.

FSH may mediate the association between HbA1c and bone turnover markers in postmenopausal women with type 2 diabetes

INTRODUCTION

Recent studies in postmenopausal women have found associations of follicle-stimulating hormone (FSH) levels with both glucose metabolism and bone turnover. The objective of the study was to investigate whether FSH may contribute to suppressed bone turnover markers (BTMs) in postmenopausal women with type 2 diabetes (T2D).

MATERIALS AND METHODS

888 postmenopausal women with T2D, 352 nondiabetes (prediabetes plus normoglycemia) were included from the METAL study. HbA1c, sex hormones, 25-hydroxy vitamin D (25(OH)D), serum procollagen type I N-terminal propeptide (P1NP), and β-C-terminal telopeptide (β-CTX) were measured.

RESULTS

P1NP and β-CTX decreased in postmenopausal T2D women compared with nondiabetes controls (both p < 0.001). The major factors responsible for the changes in P1NP were HbA1c (β = - 0.050, p < 0.001), 25(OH)D (β = - 0.003, p = 0.006), FSH (β = 0.001, p = 0.044) and metformin (β = - 0.109, p < 0.001), for β-CTX were HbA1c (β = - 0.049, p < 0.001), body mass index (BMI) (β = - 0.011, p = 0.005), 25(OH)D (β = - 0.003, p = 0.003), FSH (β = 0.002, p = 0.022) and metformin (β = - 0.091, p = 0.001) in postmenopausal T2D women based on multivariate regression analysis. With the increase in HbA1c, FSH decreased significantly (p for trend < 0.001). Mediation analysis demonstrated that FSH partly mediated the suppression of LnP1NP and Lnβ-CTX by HbA1c (β = - 0.009 and - 0.010, respectively), and Lnβ-CTX by BMI (β = - 0.015) when multiple confounders were considered (all p < 0.05).

CONCLUSION

HbA1c was the crucial determinant contributing to the suppression of BTMs. FSH might play a novel mediation role in BTM suppression due to HbA1c or BMI.

The Relationship Between Bone and Reproductive Hormones Beyond Estrogens and Androgens

Reproductive hormones play a crucial role in the growth and maintenance of the mammalian skeleton. Indeed, the biological significance for this hormonal regulation of skeletal homeostasis is best illustrated by common clinical reproductive disorders, such as primary ovarian insufficiency, hypothalamic amenorrhea, congenital hypogonadotropic hypogonadism, and early menopause, which contribute to the clinical burden of low bone mineral density and increased risk for fragility fracture. Emerging evidence relating to traditional reproductive hormones and the recent discovery of newer reproductive neuropeptides and hormones has deepened our understanding of the interaction between bone and the reproductive system. In this review, we provide a contemporary summary of the literature examining the relationship between bone biology and reproductive signals that extend beyond estrogens and androgens, and include kisspeptin, gonadotropin-releasing hormone, follicle-stimulating hormone, luteinizing hormone, prolactin, progesterone, inhibin, activin, and relaxin. A comprehensive and up-to-date review of the recent basic and clinical research advances is essential given the prevalence of clinical reproductive disorders, the emerging roles of upstream reproductive hormones in bone physiology, as well as the urgent need to develop novel safe and effective therapies for bone fragility in a rapidly aging population.

Preoperative vitamin D status and its effects on short-term clinical outcomes in lumbar spine surgery

BACKGROUND

Many studies have found that vitamin D deficiency has a high incidence rate worldwide, but we found few studies on the role of vitamin D in spinal degenerative diseases. We investigated the determinants of preoperative vitamin D deficiency and its effects on postoperative outcomes among patients undergoing elective lumbar spine surgery.

METHODS

360 patients treated from July 2017 to July 2018 were retrospectively identified for inclusion. The patients' fasting serum levels of 25(OH)D, N-terminal midfragment of osteocalcin (N-MID), and β typeⅠcollagen carboxyl terminal peptide (β-CTX) were measured by electrochemiluminescence before the operation. The visual analogue scale (VAS), Japanese Orthopaedic Association (JOA) and Oswestry Disability Index scores (ODI) were used to evaluate the clinical outcomes. Standard demographic data and all perioperative complications occurring within 3 months follow-up after operation were recorded.

RESULTS

The mean serum level of 25(OH)D was 20.81 ± 8.55 ng/mL, the rates of deficiency (<20 ng/ml) was 53.6%. The abnormal proportion of N-MID and β-CTX were 8.61% and 34.44%, bone turnover markers serum level was higher in older age groups (p < 0.05). Female sex (p < 0.001), a high body mass index (BMI) (p = 0.012), lack of vitamin D supplementation (p = 0.018), smoking (p = 0.033), moderate (p < 0.001) to severe pain (p = 0.005) were significant predictors of vitamin D deficiency after the multivariate analysis. The VAS, JOA and ODI scores showed significantly better outcomes compared to deficient group at post-operative and final follow-up (p < 0.05).

CONCLUSION

Vitamin D deficiency was common in patients undergoing elective lumbar spine surgery. Female sex, high BMI, lack of vitamin D supplementation, smoking and moderate to severe pain were risk factors for vitamin D deficiency. Moreover, preoperative hypovitaminosis D (<20 ng/ml) was correlated with worse surgical outcomes in short-term.

FSH-metabolic circuitry and menopause

FSH has a primary function in procreation, wherein it induces estrogen production in females and regulates spermatogenesis in males. However, in line with our discoveries over the past decade of non-unitary functions of pituitary hormones, we and others have described hitherto uncharacterized functions of FSH. Through high-affinity receptors, some of which are variants of the ovarian FSH receptor (FSHR), FSH regulates bone mass, adipose tissue function, energy metabolism, and cholesterol production in both sexes. These newly described actions of FSH may indeed be relevant to the pathogenesis of bone loss, dysregulated energy homeostasis, and disordered lipid metabolism that accompany the menopause in females and aging in both genders. We are therefore excited about the possibility of modulating circulating FSH levels toward a therapeutic benefit for a host of age-associated diseases, including osteoporosis, obesity and dyslipidemia, among other future possibilities.

FSH Beyond Fertility

The traditional view of follicle-stimulating hormone (FSH) as a reproductive hormone is changing. It has been shown that FSH receptors (FSHRs) are expressed in various extra-gonadal tissues and mediate the biological effects of FSH at those sites. Molecular, animal, epidemiologic, and clinical data suggest that elevated serum FSH may play a significant role in the evolution of bone loss and obesity, as well as contributing to cardiovascular and cancer risk. This review summarizes recent data on FSH action beyond reproduction.

Contribution of bone turnover markers to the variation in bone mineral density: a study in Vietnamese men and women

The present cross-sectional study constructed reference ranges for bone resorption marker beta isomerized form of C-terminal crosslinking telopeptides of type I collagen (beta-CTX) and bone formation marker procollagen type 1 N-terminal propeptide (PINP) for the Vietnamese population. We have further shown that for a given age and weight, higher levels of beta-CTX were significantly associated with bone mineral density in men and women.

INTRODUCTION

Normal bone is constantly renewed by two opposing processes of resorption and formation which can be reflected by bone turnover markers (BTMs). This study sought to define the contribution of BTMs to the variation in bone mineral density (BMD) in normal individuals.

METHODS

The study involved 205 men and 432 women aged between 18 and 87, who were randomly selected from various districts within Ho Chi Minh City, Vietnam. Fasting serum levels of PINP and beta-CTX were determined by electrochemiluminescence (Roche, ECLIA). BMD at the lumbar spine (LS) and femoral neck (FN) was measured by dual-energy x-ray absorptiometry (Hologic, Waltham, MA, USA).

RESULTS

Among those aged < 50 years, women had lower PINP and beta-CTX levels than men, but among those aged > 50 years, women had higher PINP and beta-CTX levels than men. In the multiple linear regression analysis, beta-CTX-but not PINP-was significantly associated with both femoral neck (P = 0.008) and lumbar spine BMD (P = 0.008) and the association was independent of gender, age, and body weight. The proportion of variance in BMD attributable to beta-CTX was 1% for femoral neck BMD and 2% for lumbar spine BMD.

CONCLUSION

The elevation in bone formation marker PINP and bone resorption marker beta-CTX in postmenopausal women was greater than in elderly men. However, only beta-CTX was modestly but significantly associated with BMD.

FSH, Bone Mass, Body Fat, and Biological Aging

The Study of Women's Health Across the Nation has taught us that impending ovarian failure during late perimenopause is associated with a sharp rise in serum FSH, which coincides with the most rapid rate of bone loss and the onset of visceral adiposity. At this time in a woman's life, serum estrogen levels are largely unaltered, so the hypothesis that hypoestrogenemia is the sole cause of bone loss and visceral obesity does not offer a full explanation. An alternative explanation, arising from animal models and human data, is that both physiologic aberrations, obesity and osteoporosis, arise at least in part from rising FSH levels. Here, we discuss recent findings on the mechanism through which FSH exerts biological actions on bone and fat and review clinical data that support a role for FSH in causing osteoporosis and obesity. We will also provide a conceptual framework for using a single anti-FSH agent to prevent and treat both osteoporosis and obesity in women across the menopausal transition.

Pituitary Diseases and Bone

Neuroendocrinology of bone is a new area of research based on the evidence that pituitary hormones may directly modulate bone remodeling and metabolism. Skeletal fragility associated with high risk of fractures is a common complication of several pituitary diseases such as hypopituitarism, Cushing disease, acromegaly, and hyperprolactinemia. As in other forms of secondary osteoporosis, pituitary diseases generally affect bone quality more than bone quantity, and fractures may occur even in the presence of normal or low-normal bone mineral density as measured by dual-energy X-ray absorptiometry, making difficult the prediction of fractures in these clinical settings. Treatment of pituitary hormone excess and deficiency generally improves skeletal health, although some patients remain at high risk of fractures, and treatment with bone-active drugs may become mandatory. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary diseases.

Extragonadal Effects of Follicle-Stimulating Hormone on Osteoporosis and Cardiovascular Disease in Women during Menopausal Transition

The risk of osteoporosis and cardiovascular disease increases significantly in postmenopausal women. Until recently, the underlying mechanisms have been primarily attributed to estrogen decline following menopause. However, follicle-stimulating hormone (FSH) levels rise sharply during menopausal transition and are maintained at elevated levels for many years. FSH receptor has been detected in various extragonadal sites, including osteoclasts and endothelial cells. Recent advances suggest FSH may contribute to postmenopausal osteoporosis and cardiovascular disease. Here, we review the key actions through which FSH contributes to the risk of osteoporosis and cardiovascular disease in women as they transition through menopause. Advancing our understanding of the precise mechanisms through which FSH promotes osteoporosis and cardiovascular disease may provide new opportunities for improving health-span for postmenopausal women.

Actions of pituitary hormones beyond traditional targets

Studies over the past decade have challenged the long-held belief that pituitary hormones have singular functions in regulating specific target tissues, including master hormone secretion. Our discovery of the action of thyroid-stimulating hormone (TSH) on bone provided the first glimpse into the non-traditional functions of pituitary hormones. Here we discuss evolving experimental and clinical evidence that growth hormone (GH), follicle-stimulating hormone (FSH), adrenocorticotrophic hormone (ACTH), prolactin, oxytocin and arginine vasopressin (AVP) regulate bone and other target tissues, such as fat. Notably, genetic and pharmacologic FSH suppression increases bone mass and reduces body fat, laying the framework for targeting the FSH axis for treating obesity and osteoporosis simultaneously with a single agent. Certain 'pituitary' hormones, such as TSH and oxytocin, are also expressed in bone cells, providing local paracrine and autocrine networks for the regulation of bone mass. Overall, the continuing identification of new roles for pituitary hormones in biology provides an entirely new layer of physiologic circuitry, while unmasking new therapeutic targets.

Emerging concepts in the epidemiology, pathophysiology, and clinical care of osteoporosis across the menopausal transition

Bone loss in women accelerates during perimenopause, and continues into old age. To-date, there has been little progress made in stratifying for fracture risk in premenopausal and early postmenopausal women. Epidemiologic data suggests that changes in serum FSH could predict decrements in bone mass during peri- and postmenopause. In bone, FSH stimulates osteoclast formation by releasing osteoclastogenic cytokines. Here, we address the evidence for bone loss across the menopausal transition, discuss strategies for detection and treatment of early postmenopausal osteoporosis, and describe the role FSH plays in physiology and likely in pathophysiology of early postmenopausal bone loss.

Pituitary-bone connection in skeletal regulation

Pituitary hormones have traditionally been thought to exert specific, but limited function on target tissues. More recently, the discovery of these hormones and their receptors in organs such as the skeleton suggests that pituitary hormones have more ubiquitous functions. Here, we discuss the interaction of growth hormone (GH), follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), prolactin, oxytocin and arginine vasopressin (AVP) with bone. The direct skeletal action of pituitary hormones therefore provides new insights and therapeutic opportunities for metabolic bone diseases, prominently osteoporosis.

Beyond Reproduction: Pituitary Hormone Actions on Bone

The long-held belief that pituitary hormones act solely on master targets was first questioned when we documented G protein-coupled receptors for thyroid-stimulating hormone, follicle-stimulating hormone, adrenocorticotrophic hormone, oxytocin, and vasopressin on bone cells. These evolutionarily conserved hormones and their receptors are known to have primitive roles, and exist in invertebrate species as far down as coelenterates. It is not surprising therefore that each such hormone has multiple hitherto unrecognized functions in mammalian integrative physiology, and hence, becomes a potential target for therapeutic intervention. Here we discuss the skeletal actions of pituitary hormones.

Bone turnover alterations across the menopausal transition in south-eastern Chinese women [corrected]

OBJECTIVES

To explore the serum levels of bone resorption marker C-terminal telopeptide of type I collagen (CTX) and bone formation marker N-amino terminal propeptide of type I collagen (PINP) in Chinese women across the menopausal transition and the correlation between follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol with the bone turnover markers.

METHODS

A cross-sectional study was conducted on 464 healthy Chinese women, separated into pre-, peri- and postmenopausal groups based on their menstruation changes. The serum levels of CTX, PINP, FSH, LH, and estradiol were measured.

RESULTS

The serum levels of CTX and PINP were significantly higher in women in the peri- and postmenopausal groups. The serum levels of FSH were significantly correlated with the serum levels of PINP in premenopausal women. Both serum FSH and LH were positively correlated with serum CTX in perimenopausal women and postmenopausal women. Estradiol was inversely correlated with CTX in the perimenopausal group. Multiple linear regression models show the serum FSH levels were independently related to the bone turnover markers CTX and PINP.

CONCLUSIONS

The elevated serum levels of FSH were independent risk factors for bone loss in peri- and postmenopausal women, and measurement of the serum FSH levels in mid-age women with irregular menses could be used in early diagnosis of postmenopausal osteoporosis.

Age-related bone turnover markers and osteoporotic risk in native Chinese women

BACKGROUND

The rate of bone turnover is closely related to osteoporosis risk. We investigated the correlation between bone turnover markers and BMD at various skeletal sites in healthy native Chinese women, and to study the effect of changes in the levels of bone turnover markers on the risk of osteoporosis.

METHODS

A cross-section study of 891 healthy Chinese women aged 20-80 years was conducted. The levels of serum osteocalcin (OC), bone-specific alkaline phosphatase (BAP), serum cross-linked N-terminal telopeptides of type I collagen (sNTX), cross-linked C-terminal telopeptides of type I collagen (sCTX), urinary NTX (uNTX), urinary CTX (uCTX) and total urinary deoxypyridinoline (uDPD) were determined. BMD at the posteroanterior spine and the hip was measured using DXA.

RESULTS

Pearson's correlation coefficient found significant negative correlation between bone turnover marker and BMD T-score at different skeletal sites (r = -0.08 to -0.52, all P = 0.038-0.000). After adjustments for age and body mass index, the partial correlation coefficients between the OC, BAP, sNTX, sCTX and uCTX, and the T-scores at various skeletal sites were still significant. After adjustment of height and weight, the correlation coefficients between most BTMs and PA lumbar spine BMD were also significant. Multiple linear regression analysis showed that bone turnover markers were negative determinants of T-scores. BAP and OC accounted for 33.1% and 7.8% of the variations in the T-scores of the PA spine, respectively. Serum OC, BAP, uDPD, and sNTX accounted for 0.4-21.9% of the variations in the femoral neck and total hip T-scores. The bone turnover marker levels were grouped as per quartile intervals, and the T-scores, osteoporosis prevalence and risk were found to markedly and increase with increase in bone turnover marker levels.

CONCLUSIONS

This study clarified the relationship between bone turnover markers and osteoporosis risk in native Chinese women. Bone turnover marker levels were found to be important determinants of BMD T-scores. Furthermore, osteoporotic risk significantly increased with increase in the levels of bone turnover markers.

Relationships between age-related biochemical markers of bone turnover and OPG, TGF-β1 and TGF-β2 in native Chinese women

Osteoprotegerin (OPG), transforming growth factor-β1 (TGF-β1) and TGF-β2 are cytokines closely associated with bone metabolism. However, their association with bone turnover markers in native Chinese women remains unknown. The study aims to investigate the relationship between bone metabolism related cytokines including OPG, TGF-β1, TGF-β2 and bone turnover markers in native Chinese women. The cross-sectional study was conducted on 691 healthy Chinese women (20-80 years old). Levels of OPG, TGF-β1, TGF-β2, serum bone-specific alkaline phosphatase (BAP), osteocalcin (OC), cross-linked N-terminal telopeptides of type I collagen (sNTX), cross-linked C-terminal telopeptides of type I collagen (sCTX), urinary NTX (uNTX), urinary CTX (uCTX) and total urinary deoxypyridinoline (uDPD) were determined. The present study showed that OPG and TGF-β2 had positive correlation with BAP, OC, uNTX, uCTX and uDPD, while TGF-β1 showed negative correlation with BAP, OC, sCTX, uNTX and uCTX, and most of the coefficients of partial correlation remained significant after adjustments for age and body mass index (BMI). Multiple linear regression stepwise analysis showed that OPG and TGF-β2 were positive determinative factors for BAP, sCTX, uNTX and uCTX, which could explain 0.6-16.6% of the variation in these markers. TGF-β1 was a negative determinative factor for BAP, OC, sCTX and uCTX, which could explain 0.7-7.3% of the variation in these markers. This study suggested that measuring bone turnover indicators and serum cytokines simultaneously might help evaluating changes in bone turnover rate caused by aging or menopause in women.

KIR3DL2 binds to HLA-B27 dimers and free H chains more strongly than other HLA class I and promotes the expansion of T cells in ankylosing spondylitis

The human leukocyte Ag HLA-B27 (B27) is strongly associated with the spondyloarthritides. B27 can be expressed at the cell surface of APC as both classical β2-microglobulin-associated B27 and B27 free H chain forms (FHC), including disulfide-bonded H chain homodimers (termed B27(2)). B27 FHC forms, but not classical B27, bind to KIR3DL2. HLA-A3, which is not associated with spondyloarthritis (SpA), is also a ligand for KIR3DL2. In this study, we show that B27(2) and B27 FHC bind more strongly to KIR3DL2 than other HLA-class I, including HLA-A3. B27(2) tetramers bound KIR3DL2-transfected cells more strongly than HLA-A3. KIR3DL2Fc bound to HLA-B27-transfected cells more strongly than to cells transfected with other HLA-class I. KIR3DL2Fc pulled down multimeric, dimeric, and monomeric FHC from HLA-B27-expressing cell lines. Binding to B27(2) and B27 FHC stimulated greater KIR3DL2 phosphorylation than HLA-A3. B27(2) and B27 FHC stimulated KIR3DL2CD3ε-transduced T cell IL-2 production to a greater extent than control HLA-class I. KIR3DL2 binding to B27 inhibited NK IFN-γ secretion and promoted greater survival of KIR3DL2(+) CD4 T and NK cells than binding to other HLA-class I. KIR3DL2(+) T cells from B27(+) SpA patients proliferated more in response to Ag presented by syngeneic APC than the same T cell subset from healthy and disease controls. Our results suggest that expansion of KIR3DL2-expressing leukocytes observed in B27(+) SpA may be explained by the stronger interaction of KIR3DL2 with B27 FHC.

Establishing reference intervals for bone turnover markers in the healthy shanghai population and the relationship with bone mineral density in postmenopausal women

The reference ranges of bone turnover markers (BTMs) were important during the treatment of osteoporosis, and the associations with bone mineral density (BMD) were controversial. The aim of this study was to establish the reference ranges of N-terminal procollagen of type l collagen (P1NP), osteocalcin (OC), and beta C-terminal cross-linked telopeptides of type I collagen ( β -CTX) in Shanghai area and to investigate the relationships between BTMs and BMD in postmenopausal women. 2,799 subjects recruited in Shanghai City were measured BTMs to establish the reference ranges. Additional 520 healthy postmenopausal women were also measured BTMs, these women measured BMD in addition. BTMs were measured using the Roche electrochemiluminescence system. We used the age range of 35 to 45-year-olds to calculate reference intervals. The reference range of OC was 4.91 to 13.90 ng/mL for women and 5.58 to 16.57 ng/mL for men, P1NP was 13.72 to 32.90 ng/mL for women and 16.89 to 42.43 ng/mL for men, and β -CTX was 0.112 to 0.210 ng/mL for women and 0.100 to 0.378 ng/mL for men. BTMs significantly negatively correlated with lumbar spine and femoral and total hip in postmenopausal women (Betastd = -0.157 ~ -0.217, P < 0.001). We established the normal reference ranges of P1NP, OC, and β -CTX in the Shanghai area. This study also found that BTMs correlated with BMD and suggested that BTMs were the key determining factors of early BMD decreases.

Early bone mineral density decrease is associated with FSH and LH, not estrogen

BACKGROUND

It remains unclear whether gonadotropins or estrogen is responsible for early bone mineral density (BMD) decrease in Chinese women.

METHODS

A cross-sectional study was conducted on 368 healthy adult women, aged 35-60 years. We measured BMD, calculated BMD decrease rates (BDRs) and assessed serum follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E(2)) levels.

RESULTS

BDR was significantly negatively correlated with serum FSH (r=-0.429 to -0.622, all p=0.000) and LH (r=-0.359 to -0.526, all p=0.000). After adjustment for age and body mass index, the negative correlations of serum FSH and LH with BDR persisted, but there was no overall correlation between serum E(2) and BDR. Multiple linear stepwise regression analysis suggested that serum FSH is a negative determinant of BDR. Serum E(2) seems to be a positive determinant of BDR in a few parts of the skeleton.

CONCLUSIONS

The decrease of BMD during the menopause is associated with FSH and LH levels, rather than E(2) in Chinese women.

Blocking antibody to the β-subunit of FSH prevents bone loss by inhibiting bone resorption and stimulating bone synthesis

Low estrogen levels undoubtedly underlie menopausal bone thinning. However, rapid and profuse bone loss begins 3 y before the last menstrual period, when serum estrogen is relatively normal. We have shown that the pituitary hormone FSH, the levels of which are high during late perimenopause, directly stimulates bone resorption by osteoclasts. Here, we generated and characterized a polyclonal antibody to a 13-amino-acid-long peptide sequence within the receptor-binding domain of the FSH β-subunit. We show that the FSH antibody binds FSH specifically and blocks its action on osteoclast formation in vitro. When injected into ovariectomized mice, the FSH antibody attenuates bone loss significantly not only by inhibiting bone resorption, but also by stimulating bone formation, a yet uncharacterized action of FSH that we report herein. Mesenchymal cells isolated from mice treated with the FSH antibody show greater osteoblast precursor colony counts, similarly to mesenchymal cells isolated from FSH receptor (FSHR)(-/-) mice. This suggests that FSH negatively regulates osteoblast number. We confirm that this action is mediated by signaling-efficient FSHRs present on mesenchymal stem cells. Overall, the data prompt the future development of an FSH-blocking agent as a means of uncoupling bone formation and bone resorption to a therapeutic advantage in humans.

Bone health status of premenopausal healthy adult females in Pakistani females

Bone health status in healthy premenopausal females was assessed. We found high bone turnover in 36.8 % and vitamin D deficiency and insufficiency in 82.8 and 16.1 %, respectively, and secondary hyperparathyroidism in 25.9 % of the subjects. This is alarming as there is inability to achieve peak bone mass and predisposes to osteoporosis risk.

PURPOSE

This study aimed to assess bone health status in healthy females by using biochemical markers of bone metabolism in blood [N-telopeptide of type I collagen (NTx), 25-hydroxyvitamin D (25OHD), and plasma intact parathyroid hormone (iPTH)].

MATERIAL AND METHODS

One hundred and seventy-four healthy premenopausal female volunteers were recruited from an urban residential area in Karachi. Demographic details were collected on a preformed questionnaire. Blood samples for the estimation of serum NTx, 25OHD, and plasma iPTH were taken in a fasting state. Data were analyzed using Statistical Package for Social Sciences 16.0. A p value of <0.05 was considered as significant.

RESULTS

High bone turnover, as depicted by NTx, was seen in 36.8 % cases. Vitamin D deficiency, insufficiency, and sufficiency were seen in 82.8, 16.1, and 1.1 % respectively. Secondary hyperparathyroidism was present in 25.9 % of the subjects, while others had blunted PTH response. Significant correlates of bone health were serum 25OHD levels, duration of sun exposure, and the practice of wearing veil (p value < 0.001).

CONCLUSION

Bone turnover is high with high prevalence of vitamin D deficiency in apparently healthy premenopausal females predisposing them to higher risk for development of osteoporosis.

Role of serum FSH measurement on bone resorption in postmenopausal women

In vitro and animals models have shown follicle-stimulating hormone (FSH) effects on osteoclastic function, and FSH levels seem to influence bone loss independently of estrogen concentrations in humans. Our aim was to evaluate the role of serum FSH measurement in the assessment of bone resorption in postmenopausal women. We conducted a cross-sectional study including 92 postmenopausal healthy women aged 56.2 (3.6) and 7.2 (4) years since menopause. Serum FSH, luteinizing hormone (LH), estradiol (E2) and bone turnover markers as osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX) were measured. We analyzed the relationship between serum levels of gonadotropins, E2, and bone turnover markers. Serum levels of OC and CTX were positively related to FSH (r = 0.234, P = 0.047 and r = 0.384, P = 0.003) and LH (r = 0.319, P = 0.012 and r = 0.273, P = 0.038). There was no relationship with E2 levels. When gonadotropins levels were divided into quartiles, we found significant differences in bone turnover markers between the first and the fourth quartile. OC levels were higher in the highest quartile of FSH (P = 0.024) and LH (P = 0.001). Serum CTX was also higher in the highest quartile of FSH (P = 0.004) and LH (P = 0.039). FSH levels could explain approximately 14.7% of the chances in CTX. In summary, gonadotropins were related to bone turnover in postmenopausal healthy women. Moreover, the rise in FSH appears to contribute to higher bone resorption. Our results suggest that the measurement of FSH could be usefulness to perform a more comprehensive assessment of bone loss in these women.

Determinants of serum sclerostin in healthy pre- and postmenopausal women

Sclerostin is a secreted Wnt antagonist produced almost exclusively by osteocytes that regulates bone mass. However, there is currently limited information on the determinants of sclerostin in a large population-based study. The main objectives of the present study were to: (1) establish reference normative interval values for serum sclerostin in randomly selected healthy premenopausal women; (2) study the changes in serum sclerostin in relation to age in premenopausal and postmenopausal women and the factors that may influence bone turnover; and (3) determine the effect of menopausal status on serum sclerostin. A total of 1803 women were studied (including [n = 1235] premenopausal, and [n = 568] postmenopausal women, respectively, aged 20 to 79 years). A total of 443 healthy premenopausal women (aged 35 to 45 years) were used to establish reference normative intervals for serum sclerostin. All women studied were medically examined and had their bone mineral density values obtained for the lumbar spine (L(1) -L(4) ) and femoral neck according to a detailed inclusion criteria. In all women, values of serum sclerostin increased with increasing age up to the age of 45 years, and remained increased in postmenopausal women. Significant increases were evident in serum sclerostin in postmenopausal women with increasing years since menopause. Using stepwise multiple linear regression analysis, several variables were identified as determinants of serum sclerostin, including age, parathyroid hormone, estradiol (E(2)), and follicle-stimulating hormone (FSH) for premenopausal women; age, FSH, and E(2) for postmenopausal women; and age, serum osteocalcin, FSH, and E(2) in the entire sample studied. Further studies are needed to establish the potential role of this increase in mediating the known age-related impairment in bone formation.

The role of FSH and TSH in bone loss and its clinical relevance

Osteoporosis, a global health problem, is now frequently recognized to be secondary to alterations in the pituitary-bone axis. This review examines the current evidence for how dysregulation of the pituitary-bone axis leads to osteoporotic bone loss. Specifically, perimenopausal bone loss in the context of follicle-stimulating hormone action, and hyperthyroid bone loss in the context of thyroid-stimulating hormone action are explored. From the reviewed scientific findings, recommendations for early diagnosis and better clinical management of bone loss are made.

The pathophysiology of the aging skeleton

In recent decades the population of both elderly men and women has grown substantially worldwide. Aging is associated with a number of pathologies involving various organs including the skeleton. Age-related bone loss and resultant osteoporosis put the elderly population at an increased risk for fractures and morbidity. Fortunately, in parallel our understanding of this malady has also grown substantially in recent years. A number of clinical as well as translational studies have been pivotal in providing us with an understanding of the pathophysiology of this condition. This article discusses the current concepts of age-related modulation of the skeleton involving intrinsic factors such as genetics, hormonal changes, levels of oxidative stress, and changes in telomere length, as well as extrinsic factors such as nutritional and lifestyle choices. It also briefly outlines recent studies on the relationship between bone and fat in the marrow as well as the periphery.

Reference intervals of biochemical bone turnover markers for Saudi Arabian women: a cross-sectional study

Biochemical bone turnover markers (BTMs) provide important information on the diagnosis, therapy and monitoring of metabolic bone diseases including osteoporosis. One goal of antiresorptive therapy in women is to decrease biochemical BTMs to the lower half of reference intervals for healthy pre-menopausal counterparts, using newly developed automated assays of such markers. The main objectives of the present study were to: (1) establish reference interval values for the following biochemical BTMs: serum osteocalcine (s-OC), bone alkaline phosphatase (s-bone ALP), procollagen type 1 N-terminal propeptide (s-PINP), crosslinked C-terminal telopeptide of Type 1 collagen (s-CTX), tartarate-resistant acid phosphatase isoform 5b (s-TRACP-5b) and urinary: CTX (u-CTX), N-telopeptides of type 1 collagen (u-NTX), pyridinoline (u-PYD) and deoxypyridinoline (u-DPD) in randomly selected Saudi healthy pre-menopausal women; (2) study the changes in biochemical BTMs in relation to age in pre- and post-menopausal women and the factors reported to influence bone turnover and (3) determine the effect of menopausal status on BTMs. A total of 2125 women were studied [including (n=1557) pre-, and (n=568) post-menopausal women, respectively, aged 20-79 years]. A total of 765 healthy pre-menopausal women (aged 35-45 years) were used to establish reference intervals for biochemical BTMs. All women studied were medically examined and had their bone mineral density (BMD) values obtained for the lumbar spine (L(1)-L(4)) and femoral neck according to detailed inclusion criteria. In all women, values of biochemical BTMs, decreased with increasing age up to the age of 45 years, increased steeply among women in their 50s and remained increased in post-menopausal women. Significant increases were evident in all biochemical BTMs in post-menopausal women with >5 years since menopause with the exception of s-OC, u-DPD, and u-PYD. Using stepwise multiple linear regression analysis, several variables were identified (depending on the BTM) as determinants of BTMs including age, BMI, parity, FSH, LH, PTH, s-Ca, s-Mg, s-PO(4) and 25(OH)D. In the reference intervals group, there are no significant correlations between any of the biochemical BTMs and age of menarche, day of menstrual cycle, physical activity, total daily dietary calcium and caffeine intakes and parity. It is recommended that the age range 35-45 years should be used when establishing biochemical BTMs reference intervals in Saudi Arabian pre-menopausal women.

Further evidence for direct pro-resorptive actions of FSH

We confirm that FSH stimulates osteoclast formation, function and survival to enhance bone resorption. It does so via the activation of a pertussis toxin-sensitive G(i)-coupled FSH receptor that we and others have identified on murine and human osteoclast precursors and mature osteoclasts. FSH additionally enhances the production of several osteoclastogenic cytokines, importantly TNFalpha, likely within the bone marrow microenvironment, to augment its pro-resorptive action. FSH levels in humans rise before estrogen falls, and this hormonal change coincides with the most rapid rates of bone loss. On the basis of accumulating evidence, we reaffirm that FSH contributes to the rapid peri-menopausal and early post-menopausal bone loss, which might thus be amenable to FSH blockade.