From estrogen-centric to aging and oxidative stress: a revised perspective of the pathogenesis of osteoporosis

Garcinol prevents oxidative stress-induced bone loss and dysfunction of BMSCs through NRF2-antioxidant signaling

There are multiple published data showing that excessive oxidative stress contributes to bone loss and even bone tissue damage, and it is also correlated with the pathophysiology of bone degenerative diseases, including osteoporosis (OP). Garcinol, a polyisoprenylated benzophenone derivative, has been recently established as an anti-oxidant agent. However, it remains elusive whether Garcinol protects bone marrow mesenchymal stem cells (BMSCs) and bone tissue from oxidative stress-induced damage. Here, we explored the potential effects of Garcinol supplementation in ameliorating oxidative stimulation-induced dysfunction of BMSCs and bone loss in osteoporotic mice. In this study, we verified that Garcinol exerted potent protective functions in the hydrogen peroxide (H2O2)-induced excessive oxidative stress and dysfunction of BMSCs. Besides, Garcinol was also identified to improve the reduced bone mass and abnormal lineage commitment of BMSCs in the condition of OP by suppressing the oxidative stimulation. Subsequent analysis revealed that nuclear factor erythroid 2-related factor 2 (NRF2) might be a key regulator in the sheltering effects of Garcinol on the H2O2-regulated oxidative stress, and the protective functions of Garcinol was mediated by NRF2-antioxidant signaling. Collectively, Garcinol prevented oxidative stress-related BMSC damage and bone loss through the NRF2-antioxidant signaling, which suggested the promising therapeutic values of Garcinol in the treatment of oxidative stress-related bone loss. Therefore, Garcinol might contribute to treating OP.

Effects of Multispecies Probiotic Supplementation on Serum Bone Turnover Markers in Postmenopausal Women with Osteopenia: A Randomized, Double-Blind, Placebo-Controlled Trial

Probiotics have been found to have beneficial effects on bone metabolism. In this randomized, double-blind, placebo-controlled trial, the effects of multispecies probiotic supplementation on bone turnover markers were evaluated after 12 weeks. Forty postmenopausal women with osteopenia were included and randomly divided into two groups. The intervention group received multispecies probiotics, while the control group received identical placebo sachets daily. The baseline characteristics of both groups were similar. Still, the median serum bone resorption marker C-terminal telopeptide of type I collagen (CTX) was slightly higher in the multispecies probiotic group than in the placebo group (0.35 (0.12, 0.53) vs. 0.16 (0.06, 0.75); p-value = 0.004). After 12 weeks, the mean difference in serum CTX at baseline versus 12 weeks was significantly different between the multispecies probiotic and placebo groups (-0.06 (-0.29, 0.05) vs. 0.04 (-0.45, 0.67); p-value < 0.001). The multispecies probiotic group showed a significant decrease in serum CTX at 12 weeks compared with baseline (p-value 0.026). However, the placebo group showed no significant change in serum CTX (p-value 0.18). In conclusion, multispecies probiotics may have a preventive effect on bone through their antiresorptive effect in osteopenic postmenopausal women.

Isoquercitrin attenuates the osteoclast-mediated bone loss in rheumatoid arthritis via the Nrf2/ROS/NF-κB pathway

An excess of osteoclastogenesis significantly contributes to the development of rheumatoid arthritis (RA). Activation of the nuclear factor erythroid-2 related factor 2 (Nrf2) and nuclear factor kappa B (NF-κB) ligand (RANKL)-induced reactive oxygen species (ROS)-to-NF-κB signaling cascade are important mechanisms regulating osteoclastogenesis; however, whether Nrf2 is involved in RANKL-induced NF-κB activation is controversial. Isoquercitrin, a natural flavonoid compound, has been shown to have Nrf2-dependent antioxidant effects inprevious studies. We sought to verify whether isoquercitrin could modulate RANKL-induced NF-κB activation by activating Nrf2, thereby affecting osteoclastogenesis. Tartrate-resistant acid phosphatase staining, F-actin ring staining and resorption pit assay suggested that isoquercitrin significantly inhibited osteoclastogenesis and osteolytic function. Mitosox staining showed that RANKL-induced ROS generation was significantly inhibited by isoquercitrin from day 3 of the osteoclast differentiation cycle. Quantitative real-time PCR, Western blot, and immunofluorescence indicated that isoquercitrin activated the Nrf2 signaling pathway and inhibited NF-κB expression. And when we used the Nrf2-specific inhibitor ML385, the inhibition of NF-κB by isoquercitrin disappeared. Moreover, we found that Nrf2 is not uninvolved in RANKL-induced NF-κB activation and may be related to the timing of ROS regulation. When we limited isoquercitrin administration to 2 days, Nrf2 remained activated and the inhibition of NF-κB disappeared. In vivo experiments suggested that isoquercitrin attenuated RA modeling-induced bone loss. Overall, isoquercitrin-activated Nrf2 blocked the RANKL-induced ROS-to-NF-κB signaling cascade response, thereby inhibiting osteoclastogenesis and bone loss. These findings provide new ideas for the treatment of RA.

Biomimetic Therapeutics for Bone Regeneration: A Perspective on Antiaging Strategies

Advances in modern medicine and the significant reduction in infant mortality have steadily increased the population's lifespan. As more and more people in the world grow older, incidence of chronic, noncommunicable disease is anticipated to drastically increase. Recent studies have shown that improving the health of the aging population is anticipated to provide the most cost-effective and impactful improvement in quality of life during aging-driven disease. In bone, aging is tightly linked to increased risk of fracture, and markedly decreased regenerative potential, deeming it critical to develop therapeutics to improve aging-driven bone regeneration. Biomimetics offer a cost-effective method in regenerative therapeutics for bone, where there are numerous innovations improving outcomes in young models, but adapting biomimetics to aged models is still a challenge. Chronic inflammation, accumulation of reactive oxygen species, and cellular senescence are among three of the more unique challenges facing aging-induced defect repair. This review dissects many of the innovative biomimetic approaches research groups have taken to tackle these challenges, and discusses the further uncertainties that need to be addressed to push the field further. Through these research innovations, it can be noted that biomimetic therapeutics hold great potential for the future of aging-complicated defect repair.

Agomelatine alleviates steroid-induced osteoporosis by targeting SIRT1/RANKL/FOXO1/OPG signalling in rats

One of the major contributors to secondary osteoporosis is long-term glucocorticoid usage. Clinically used antidepressant agomelatine also has anti-inflammatory properties. Our research aimed to inspect the probable defensive effect of agomelatine against steroid-promoted osteoporosis. There were four groups of rats; group I had saline as a negative control; rats of group II had dexamethasone (0.6 mg/kg, s.c.), twice weekly for 12 weeks; rats of group III had agomelatine (40 mg/kg/day, orally), as a positive control, daily for 12 weeks; and rats of group IV had dexamethasone + agomelatine in the same previous doses combined for 12 weeks. Finally, biochemical as well as histopathological changes were evaluated and dexamethasone treatment caused osteoporosis, as evidenced by discontinuous thin cancellous bone trabeculae, minor fissures and fractures, irregular eroded endosteal surface with elevated alkaline phosphate, tartarate resistant acid phosphate (TRACP) and osteocalcin levels. Osteoprotegerin (OPG), calcium, and phosphorus levels decreased with disturbed receptor activator of nuclear factor κ B ligand (RANKL), forkhead box O1 (FOXO1), and silent information regulator 1 (SIRT1) protein expression. However, treatment with agomelatine restored the normal levels of biochemical parameters to a great extent, supported by SIRT activation with an improvement in histopathological changes. Here, we concluded that agomelatine ameliorates steroid-induced osteoporosis through a SIRT1/RANKL/FOXO1/OPG-dependent pathway.

Age-related decline in melatonin contributes to enhanced osteoclastogenesis via disruption of redox homeostasis

BACKGROUND

Increased oxidative stress contributes to enhanced osteoclastogenesis and age-related bone loss. Melatonin (MT) is an endogenous antioxidant and declines with aging. However, it was unclear whether the decline of MT was involved in the enhanced osteoclastogenesis during the aging process.

METHODS

The plasma level of MT, oxidative stress status, bone mass, the number of bone marrow-derived monocytes (BMMs) and its osteoclastogenesis were analyzed in young (3-month old) and old (18-month old) mice (n = 6 per group). In vitro, BMMs isolated from aged mice were treated with or without MT, followed by detecting the change of osteoclastogenesis and intracellular reactive oxygen species (ROS) level. Furthermore, old mice were treated with MT for 2 months to investigate the therapeutic effect.

RESULTS

The plasma level of MT was markedly lower in aged mice compared with young mice. Age-related decline in MT was accompanied by enhanced oxidative stress, osteoclastogenic potential and bone loss. MT intervention significantly suppressed the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis, decreased intracellular ROS and enhanced antioxidant capacity of BMMs from aged mice. MT supplementation significantly attenuated oxidative stress, osteoclastogenesis, bone loss and deterioration of bone microstructure in aged mice.

CONCLUSIONS

These results suggest that age-related decline of MT enhanced osteoclastogenesis via disruption of redox homeostasis. MT may serve as a key regulator in osteoclastogenesis and bone homeostasis, thereby highlighting its potential as a preventive agent for age-related bone loss.

Surface characteristics and in vitro biocompatibility of titanium preserved in a vitamin C-containing saline storage solution

The purpose of this study is to explore a storage solution for titanium implants and investigate its osteogenic properties. The commercial pure titanium (cp-Ti) surface and double-etched (SLA) titanium surface specimens were preserved in air, saline, 10 mM Vitamin C (VitC)-containing saline and 100 mM VitC-containing saline storage solutions for 2 weeks. The surface microtopography of titanium was observed by scanning electron microscopy (SEM), the surface elemental compositions of the specimens were analyzed by Raman and X-ray photoelectron spectroscopy (XPS), and water contact angle and surface roughness of the specimens were tested. The protein adsorption capacity of two titanium surfaces after storage in different media was examined by BCA kit. The MC3T3-E1 osteoblasts were cultured on two titanium surfaces after storage in different media, and the proliferation, adhesion and osteogenic differentiation activity of osteoblasts were detected by CCK-8, laser confocal microscope (CLSM) and Western blot. The SEM results indicated that the titanium surfaces of the air group were relatively clean while scattered sodium chloride or VitC crystals were seen on the titanium surfaces of the other three groups. There were no significant differences in the micromorphology of the titanium surfaces among the four groups. Raman spectroscopy detected VitC crystals on the titanium surfaces of two experimental groups. The XPS, water contact angle and surface roughness results suggested that cp-Ti and SLA-Ti stored in 0.9% NaCl and two VitC-containing saline storage solutions possessed less carbon contamination and higher surface hydrophilicity. Moreover, the protein adsorption potentials of cp-Ti and SLA-Ti surfaces were significantly improved under preservation in two VitC-containing saline storage solutions. The results of in vitro study showed that the preservation of two titanium surfaces in 100 mM VitC-containing saline storage solution upregulated the cell adhesion, proliferation, osteogenic related protein expressions of MC3T3-E1 osteoblasts. In conclusion, preservation of cp-Ti and SLA-Ti in 100 mM VitC-containing saline storage solution could effectively reduce carbon contamination and enhance surface hydrophilicity, which was conducive to osteogenic differentiation of osteoblasts.

Crosstalk Between the Neuroendocrine System and Bone Homeostasis

The homeostasis of bone microenvironment is the foundation of bone health and comprises 2 concerted events: bone formation by osteoblasts and bone resorption by osteoclasts. In the early 21st century, leptin, an adipocytes-derived hormone, was found to affect bone homeostasis through hypothalamic relay and the sympathetic nervous system, involving neurotransmitters like serotonin and norepinephrine. This discovery has provided a new perspective regarding the synergistic effects of endocrine and nervous systems on skeletal homeostasis. Since then, more studies have been conducted, gradually uncovering the complex neuroendocrine regulation underlying bone homeostasis. Intriguingly, bone is also considered as an endocrine organ that can produce regulatory factors that in turn exert effects on neuroendocrine activities. After decades of exploration into bone regulation mechanisms, separate bioactive factors have been extensively investigated, whereas few studies have systematically shown a global view of bone homeostasis regulation. Therefore, we summarized the previously studied regulatory patterns from the nervous system and endocrine system to bone. This review will provide readers with a panoramic view of the intimate relationship between the neuroendocrine system and bone, compensating for the current understanding of the regulation patterns of bone homeostasis, and probably developing new therapeutic strategies for its related disorders.

Smart stimuli-responsive strategies for titanium implant functionalization in bone regeneration and therapeutics

With the increasing and aging of global population, there is a dramatic rise in the demand for implants or substitutes to rehabilitate bone-related disorders which can considerably decrease quality of life and even endanger lives. Though titanium and its alloys have been applied as the mainstream material to fabricate implants for load-bearing bone defect restoration or temporary internal fixation devices for bone fractures, it is far from rare to encounter failed cases in clinical practice, particularly with pathological factors involved. In recent years, smart stimuli-responsive (SSR) strategies have been conducted to functionalize titanium implants to improve bone regeneration in pathological conditions, such as bacterial infection, chronic inflammation, tumor and diabetes mellitus, etc. SSR implants can exert on-demand therapeutic and/or pro-regenerative effects in response to externally applied stimuli (such as photostimulation, magnetic field, electrical and ultrasound stimulation) or internal pathology-related microenvironment changes (such as decreased pH value, specific enzyme secreted by bacterial and excessive production of reactive oxygen species). This review summarizes recent progress on the material design and fabrication, responsive mechanisms, and in vitro and in vivo evaluations for versatile clinical applications of SSR titanium implants. In addition, currently existing limitations and challenges and further prospective directions of these strategies are also discussed.

The entrancing role of dietary polyphenols against the most frequent aging-associated diseases

Aging, a fundamental physiological process influenced by innumerable biological and genetic pathways, is an important driving factor for several aging-associated disorders like diabetes mellitus, osteoporosis, cancer, and neurodegenerative diseases including Alzheimer's and Parkinson's diseases. In the modern era, the several mechanisms associated with aging have been deeply studied. Treatment and therapeutics for age-related diseases have also made considerable advances; however, for the effective and long-lasting treatment, nutritional therapy particularly including dietary polyphenols from the natural origin are endorsed. These dietary polyphenols (e.g., apigenin, baicalin, curcumin, epigallocatechin gallate, kaempferol, quercetin, resveratrol, and theaflavin), and many other phytochemicals target certain molecular, genetic mechanisms. The most common pathways of age-associated diseases are mitogen-activated protein kinase, reactive oxygen species production, nuclear factor kappa light chain enhancer of activated B cells signaling pathways, metal chelation, c-Jun N-terminal kinase, and inflammation. Polyphenols slow down the course of aging and help in combatting age-linked disorders. This exemplified in the form of clinical trials on specific dietary polyphenols in various aging-associated diseases. With this context in mind, this review reveals the new insights to slow down the aging process, and consequently reduce some classic diseases associated with age such as aforementioned, and targeting age-associated diseases by the activities of dietary polyphenols of natural origin.

New Emerging Aspect of Herbal Extracts for the Treatment of Osteoporosis: Overview

As the global population ages, osteoporosis is becoming a more common silent disease. Osteoporosis is characterized by decreased bone quality and strength, which increases the risk of fragility fractures in the elderly. According to estimates, 50% of women eventually suffer from an osteoporotic fracture. Due to increasing disability, more frequent hospital hospitalizations, and most critically, fragility fractures have been linked to a reduced quality of life. Osteoporotic fractures have been linked to an increased mortality risk; and must be considered in awareness as a serious health concern. There are anti-osteoporotic medications available that improve bone quality. Considering the availability of various treatment options, still there are a lot of underserved needs in the treatment of fractures and osteoporosis. For example, the application of natural products and herbal resources for fracture healing, because of the androgen-like and antioxidant characteristics of the plants, they can play a crucial for accelerating the repair of bone fractures. In this article, we'll discuss the herbal remedies that are essential for treating osteoporosis (bone disease).

Probiotics and their Beneficial Health Effects

Probiotics are living microorganisms that are present in cultured milk and fermented food. Fermented foods are a rich source for the isolation of probiotics. They are known as good bacteria. They have various beneficial effects on human health including antihypertensive effects, antihypercholesterolemic effects, prevention of bowel disease, and improving the immune system. Microorganisms including bacteria, yeast, and mold are used as probiotics but the major microorganisms that are used as probiotics are bacteria from the genus Lactobacillus, Lactococcus, Streptococcus, and Bifidobacterium. Probiotics are beneficial in the prevention of harmful effects. Recently, the use of probiotics for the treatment of various oral and skin diseases has also gained significant attention. Clinical studies indicate that the usage of probiotics can alter gut microbiota composition and provoke immune modulation in a host. Due to their various health benefits, probiotics are attaining more interest as a substitute for antibiotics or anti-inflammatory drugs leading to the growth of the probiotic market.

Nanozymes With Osteochondral Regenerative Effects: An Overview of Mechanisms and Recent Applications

With the discovery of the intrinsic enzyme-like activity of metal oxides, nanozymes garner significant attention due to their superior characteristics, such as low cost, high stability, multi-enzyme activity, and facile preparation. Notably, in the field of biomedicine, nanozymes primarily focus on disease detection, antibacterial properties, antitumor effects, and treatment of inflammatory conditions. However, the potential for application in regenerative medicine, which primarily addresses wound healing, nerve defect repair, bone regeneration, and cardiovascular disease treatment, is garnering interest as well. This review introduces nanozymes as an innovative strategy within the realm of bone regenerative medicine. The primary focus of this approach lies in the facilitation of osteochondral regeneration through the modulation of the pathological microenvironment. The catalytic mechanisms of four types of representative nanozymes are first discussed. The pathological microenvironment inhibiting osteochondral regeneration, followed by summarizing the therapy mechanism of nanozymes to osteochondral regeneration barriers is introduced. Further, the therapeutic potential of nanozymes for bone diseases is included. To improve the therapeutic efficiency of nanozymes and facilitate their clinical translation, future potential applications in osteochondral diseases are also discussed and some significant challenges addressed.

Polyphenols as potential preventers of osteoporosis: A comprehensive review on antioxidant and anti-inflammatory effects, molecular mechanisms, and signal pathways in bone metabolism

Osteoporosis (OP) is a skeletal disorder characterized by decreased bone density, alterations in bone microstructure, and increased damage to the bones. As the population ages and life expectancy increases, OP has become a global epidemic, drawing attention from scientists and doctors. Because of polyphenols have favorable antioxidant and anti-allergy effects, which are regarded as potential methods to prevent angiocardipathy and OP. Polyphenols offer a promising approach to preventing and treating OP by affecting bone metabolism, reducing bone resolution, maintaining bone density, and lowering the differentiation level of osteoclasts (OC). There are multiple ways in which polyphenols affect bone metabolism. This article provides an overview of how polyphenols inhibit oxidative stress, exert antibacterial effects, and prevent the occurrence of OP. Furthermore, we will explore the regulatory mechanisms and signaling pathways implicated in this process.

Ziyin Bushen Fang improves Diabetic Osteoporosis by Inhibiting Autophagy and Oxidative Stress In vitro and In vivo

OBJECTIVE

Diabetic osteoporosis (DOP) belongs to the group of diabetes-induced secondary osteoporosis and is the main cause of bone fragility and fractures in many patients with diabetes. The aim of this study was to determine whether Ziyin Bushen Fang (ZYBSF) can improve DOP by inhibiting autophagy and oxidative stress.

METHODS

Type 1 diabetes mellitus (T1DM) was induced in rats using a high-fat high-sugar diet combined with streptozotocin. Micro-CT scanning was used to quantitatively observe changes in the bone microstructure in each group. Changes in the serum metabolites of DOP rats were analyzed using UHPLC-QTOF-MS. The DOP mouse embryonic osteoblast precursor cell model (MC3T3-E1) was induced using high glucose levels.

RESULTS

After ZYBSF treatment, bone microstructure significantly improved. The bone mineral density, trabecular number, and trabecular thickness in the ZYBSF-M and ZYBSF-H groups significantly increased. After ZYBSF treatment, the femur structure of the rats was relatively intact, collagen fibers were significantly increased, and osteoporosis was significantly improved. A total of 1239 metabolites were upregulated and 1527 were downregulated in the serum of T1DM and ZYBSF-treated rats. A total of 20 metabolic pathways were identified. In cellular experiments, ZYBSF reduced ROS levels and inhibited the protein expression of LC3II / I, Beclin-1, and p-ERK.

CONCLUSION

ZYBSF may improve DOP by inhibiting the ROS/ERK-induced autophagy signaling pathway.

Narrative Review of Traditional Chinese Medicine in the Treatment of Postmenopausal Osteoporosis

An increasing percentage of people in China are suffering from osteoporosis, particularly postmenopausal osteoporosis (PMOP), as the country rapidly evolves into an aging culture. Patients with osteoporosis are inclined to endure fractures, as well as deformities and impairments, which drastically decrease people's quality of life. The benefits of Traditional Chinese medicine (TCM) treatment have continued to become increasingly apparent as reports of adverse responses to Western medications increased. The main advantage of traditional Chinese medicine treatment is that pharmacological interactions may be employed to lessen adverse effects while increasing therapeutic efficacy. In addition, there are various exercise therapies created by medical doctors in the past generations, such as: Wuqinxi, Taijiquan, Baduanjin, Yijinjing, etc. Chinese medicine and exercise treatment for postmenopausal osteoporosis have garnered a lot of attention recently both domestically and internationally, and investigations demonstrate that these therapies have considerable therapeutic effects. The pathophysiology of postmenopausal osteoporosis, advancements of herbal therapy options, and exercise treatment options are all thoroughly addressed in this article.

Effects of Aging on Osteosynthesis at Bone-Implant Interfaces

Joint replacement is a common surgery and is predominantly utilized for treatment of osteoarthritis in the aging population. The longevity of many of these implants depends on bony ingrowth. Here, we provide an overview of current techniques in osteogenesis (inducing bone growth onto an implant), which is affected by aging and inflammation. In this review we cover the biologic underpinnings of these processes as well as the clinical applications. Overall, aging has a significant effect at the cellular and macroscopic level that impacts osteosynthesis at bone-metal interfaces after joint arthroplasty; potential solutions include targeting prolonged inflammation, preventing microbial adhesion, and enhancing osteoinductive and osteoconductive properties.

Trichostatin A enhances the titanium rods osseointegration in osteoporotic rats by the inhibition of oxidative stress through activating the AKT/Nrf2 pathway

The use of titanium implants as fixed supports following fractures in patients with OP can often result in sterile loosening and poor osseointegration. Oxidative stress has been shown to play a particularly important role in this process. While TSA has been reported to facilitate in vivo osteogenesis, the underlying mechanisms remain to be clarified. It also remains unclear whether TSA can improve the osseointegration of titanium implants. This study investigated whether TSA could enhance the osseointegration of titanium rods by activating AKT/Nrf2 pathway signaling, thereby suppressing oxidative stress. MC3T3-E1 cells treated with CCCP to induce oxidative stress served as an in vitro model, while an OVX-induced OP rat model was employed for in vivo analysis of titanium rod implantation. In vitro, TSA treatment of CCCP-treated MC3T3-E1 cells resulted in the upregulation of osteogenic proteins together with increased AKT, total Nrf2, nuclear Nrf2, HO-1, and NQO1 expression, enhanced mitochondrial functionality, and decreased oxidative damage. Notably, the PI3K/AKT inhibitor LY294002 reversed these effects. In vivo, TSA effectively enhanced the microstructural characteristics of distal femur trabecular bone, increased BMSCs mineralization capacity, promoted bone formation, and improved the binding of titanium implants to the surrounding tissue. Finally, our results showed that TSA could reverse oxidative stress-induced cell damage while promoting bone healing and improving titanium rods' osseointegration through AKT/Nrf2 pathway activation.

Metabolic bone disorders and the promise of marine osteoactive compounds

Metabolic bone disorders and associated fragility fractures are major causes of disability and mortality worldwide and place an important financial burden on the global health systems. These disorders result from an unbalance between bone anabolic and resorptive processes and are characterized by different pathophysiological mechanisms. Drugs are available to treat bone metabolic pathologies, but they are either poorly effective or associated with undesired side effects that limit their use. The molecular mechanism underlying the most common metabolic bone disorders, and the availability, efficacy, and limitations of therapeutic options currently available are discussed here. A source for the unmet need of novel drugs to treat metabolic bone disorders is marine organisms, which produce natural osteoactive compounds of high pharmaceutical potential. In this review, we have inventoried the marine osteoactive compounds (MOCs) currently identified and spotted the groups of marine organisms with potential for MOC production. Finally, we briefly examine the availability of in vivo screening and validation tools for the study of MOCs.

Local Effects of Steroid Hormones within the Bone Microenvironment

Steroid hormone production via the adrenal cortex, gonads, and placenta (so-called glandular steroidogenesis) is responsible for the endocrine control of the body's homeostasis and is organized by a feedback regulatory mechanism based on the hypothalamus-pituitary-steroidogenic gland axis. On the other hand, recently discovered extraglandular steroidogenesis occurring locally in different tissues is instead linked to paracrine or autocrine signaling, and it is independent of the control by the hypothalamus and pituitary glands. Bone cells, such as bone-forming osteoblasts, osteoblast-derived osteocytes, and bone-resorbing osteoclasts, respond to steroid hormones produced by both glandular and extraglandular steroidogenesis. Recently, new techniques to identify steroid hormones, as well as synthetic steroids and steroidogenesis inhibitors, have been introduced, which greatly empowered steroid hormone research. Based on recent literature and new advances in the field, here we review the local role of steroid hormones in regulating bone homeostasis and skeletal lesion formation. The novel idea of extraglandular steroidogenesis occurring within the skeletal system raises the possibility of the development of new therapies for the treatment of bone diseases.

Associations of dietary oxidative balance score with femur osteoporosis in postmenopausal women: data from the National Health and Nutrition Examination Survey

We used data from the NHANES to explore associations of DOBS with femur BMD and osteoporosis in postmenopausal women. We found that DOBS was positively associated with femur BMD and negatively associated with the risk of osteoporosis in postmenopausal women.

PURPOSE

The study aimed to investigate the relationship between dietary oxidative balance score (DOBS) and the risk of osteoporosis in American postmenopausal women.

METHODS

A total of 3043 participants were included in this study. The linear relationship between DOBS and femur BMD was evaluated using a weighted multivariate linear regression model. The association between DOBS and the risk of osteoporosis was assessed using a weighted logistic regression model, with odds ratios (ORs) and 95% confidence intervals (CIs) calculated. Moreover, the relationship was further characterized through smooth curve fitting (SCF) and weighted generalized additive model (GAM) analysis.

RESULTS

After adjusting for all covariates, the weighted multivariable linear regression models showed a positive correlation between DOBS and femur BMD. Moreover, the weighted logistic regression model demonstrated that compared to the first tertile of DOBS, the highest tertile of DOBS was significantly associated with a lower risk of osteoporosis, with ORs of 0.418 (95% CI, 0.334, 0.522) for individuals under the age of 70 and 0.632 (95% CI, 0.506, 0.790) for individuals aged 70 or above. Similar trends were also observed in SCF and GAM models.

CONCLUSION

The present study indicated that postmenopausal women with a higher DOBS have a lower risk of femur osteoporosis. This finding may highlight the potential protective role of an antioxidant-rich diet for the bones of the postmenopausal population. Moreover, DOBS may also be a valuable tool in identifying individuals with osteoporosis. Screening and early intervention for osteoporosis may be essential for postmenopausal women with low DOBS.

The Healing Callus-Promoting Effect of Fenugreek in a Humerus Shaft Fracture: A Case Report

A 54-year-old male presented with a fractured shaft in the right humerus and refused surgery. The patient was treated with a cast, and a follow-up plain radiography revealed good callus formation after 32 days. The patient had a history of receiving fenugreek seed extract from the first week after the fracture. We did our best to exclude any other factors that helped rapid fracture healing with good callus formation in our patient. The current case supports the hypothesis that fenugreek seed extract promotes bone healing. This hypothesis is supported by a literature review. Previous studies have suggested several mechanisms by which fenugreek promotes bone healing.

Association of overweight and obesity with vertebral fractures: a systematic review and meta-analysis

INTRODUCTION

Over the past decade, there has been increasing interest in exploring the relationship between overweight, obesity and vertebral fractures. Nonetheless, available data from studies on the relationship between overweight, obesity and vertebral fractures remains controversial.

EVIDENCE ACQUISITION

A systematic search was performed in the PubMed and Cochrane Library databases. We selected relevant literature by using these keywords: fracture, vertebral fracture, vertebral compression fracture, overweight, obese, obesity. The retrieval mainly collected publicly published observational studies on the correlation between overweight, obesity and vertebral fractures, excluding the literature that did not meet the inclusion criteria. Meta-analysis for the data extracted from all the included literatures was performed by STATA 12.0 (StataCorp LLC, College Station, TX, USA) to summarize test performance with forest plots and assess the heterogeneity.

EVIDENCE SYNTHESIS

Ten studies, including 1,024,181 subjects satisfied the predefined eligibility criteria. The results showed that the overweight (25.0≤ Body Mass Index [BMI] ≤29.9 kg/m2) and obesity (BMI≥30.0kg/m2) were associated with a decreased risk of vertebral fractures, respectively. The pooled RR is 0.86 (95% CI: 0.79, 0.95) and 0.81(95% CI:0.74-0.90) with no evidence of statistical heterogeneity. However, the relationship between overweight/obesity (BMI≥25 kg/m2) and vertebral fractures is not statistically significant.

CONCLUSIONS

This study showed that overweight and obesity might decrease the risk of vertebral fractures, respectively. However, we did not observe a significant association between overweight/obesity (BMI≥25 kg/m2) and vertebral fractures.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

The role of reactive oxygen species in bone cell physiology and pathophysiology

Hydrogen peroxide (H2O2), superoxide anion radical (O2-•), and other forms of reactive oxygen species (ROS) are produced by the vast majority of mammalian cells and can contribute both to cellular homeostasis and dysfunction. The NADPH oxidases (NOX) enzymes and the mitochondria electron transport chain (ETC) produce most of the cellular ROS. Multiple antioxidant systems prevent the accumulation of excessive amounts of ROS which cause damage to all cellular macromolecules. Many studies have examined the contribution of ROS to different bone cell types and to skeletal physiology and pathophysiology. Here, we discuss the role of H2O2 and O2-• and their major enzymatic sources in osteoclasts and osteoblasts, the fundamentally different ways via which these cell types utilize mitochondrial derived H2O2 for differentiation and function, and the molecular mechanisms that impact and are altered by ROS in these cells. Particular emphasis is placed on evidence obtained from mouse models describing the contribution of different sources of ROS or antioxidant enzymes to bone resorption and formation. Findings from studies using pharmacological or genetically modified mouse models indicate that an increase in H2O2 and perhaps other ROS contribute to the loss of bone mass with aging and estrogen deficiency, the two most important causes of osteoporosis and increased fracture risk in humans.

Diet-derived antioxidants and osteoporosis: A Mendelian randomization study

BACKGROUND

Antioxidants can prevent osteoporosis, but the association between serum antioxidants and the cause of osteoporosis remains unknown. We aimed to utilize Mendelian randomization (MR) to determine whether genetically predicted serum levels of diet-derived antioxidants can affect the risk of osteoporosis, to determine the effect of dietary supplementation of antioxidants.

METHODS

Genetic variants associated with diet-derived antioxidants were selected from the genome-wide association studies. A total of 12,946 osteoporosis cases and 506,624 healthy controls were obtained from UK Biobank (UKB) and Genetic Factors of Osteoporosis (GEFOS) consortia. We implemented a two-sample MR design and performed several sensitivity analyses to evaluate the causal relationship.

RESULTS

In UKB, the genetically predicted higher β-carotene (OR = 0.863, p = 7.37 × 10-6, power = 100%) and γ-tocopherol (OR = 0.701, p = 0.021, power = 5%) had an inverse relationship with osteoporosis. However, only the association of serum β-carotene passed FDR correction. In GEFOS, there were no significant diet-derived antioxidants. The direction of the association of β-carotene with osteoporosis (OR = 0.844, p = 0.106, power = 87%) was consistent with that in the UKB dataset. A fixed-effects meta-analysis confirmed that β-carotene (OR = 0.862, p = 2.21 × 10-6) and γ-tocopherol (OR = 0.701, p = 2.31 × 10-2) could decrease the risk of osteoporosis. To reduce exclusion limit bias, we used total body bone mineral density, lumbar spine bone mineral density and femoral neck bone mineral density as surrogates and found that the genetically elevated circulating β-carotene level could increase total body BMD (beta = 0.043, p-value = 8.26 x 10-5, power = 100%), lumbar spine BMD (beta = 0.226, p-value = 0.001, power = 100%) and femoral neck BMD(beta = 0.118, p-value = 0.016, power = 100%).

CONCLUSIONS

We observed that genetically predicted serum β-carotene could elevate BMD and prevent osteoporosis.

Association between dietary selenium intake and the prevalence of osteoporosis and its role in the treatment of glucocorticoid-induced osteoporosis

BACKGROUND

Long-term glucocorticoid therapy may lead to osteoporosis (OP). Selenium (Se) is an essential microelement for human health and bone health. This study evaluated the association between dietary Se intake and the prevalence of OP and further explored the potential therapeutic effect of Se on glucocorticoid-induced OP (GIOP) in vivo and in vitro.

METHODS

Data were collected from a population-based cross-sectional study conducted in our hospital. OP is diagnosed based on bone mineral density (BMD) measurements using compact radiographic absorptiometry. Dietary Se intake was assessed using a semi-quantitative food frequency questionnaire. The association between dietary Se intake and OP prevalence was analyzed by multivariable logistic regression. In animal experiments, male Sprague-Dawley rats were intramuscularly injected with dexamethasone (1 mg/kg) daily to induce GIOP, while different doses of Se were supplemented in rat drinking water for 60 d. BMD and biomechanical parameters of rat femur were measured. The histopathological changes of the femur were observed by HE staining, the number of osteoclasts was observed by TRAP staining, and OCN positive expression was detected by immunohistochemical staining. OPG, RANKL, Runx2, and BMP2 in rat femur were detected by Western blot. Bone turnover markers and oxidative stress markers were measured using commercial kits. MC3T3-E1 cells were induced to osteogenic differentiation, stimulated with DXM (100 μM), and/or treated with Se at different doses. Cell proliferation and apoptosis were assessed by CCK-8 and flow cytometry. ALP activity was detected by ALP staining and cell mineralization was observed by alizarin red staining.

RESULTS

Participants with lower dietary Se intake had higher OP prevalence. Se supplementation improved BMD, biomechanical parameters, and histopathological changes of the femur in GIOP rats. Se supplementation also suppressed DXM-induced changes in bone turnover- and oxidative stress-related markers. Under DXM conditions, Se treatment induced MC3T3-E1 cell proliferation, ALP activity, and mineralization.

CONCLUSION

Lower Dietary Se intake is associated with OP prevalence. Moreover, Se takes a position in bone protection and anti-oxidative stress in GIOP models. Therefore, Se may be a complementary potential treatment for GIOP.

A comprehensive review on environmental pollutants and osteoporosis: Insights into molecular pathways

A significant problem that has an impact on community wellbeing is environmental pollution. Environmental pollution due to air, water, or soil pollutants might pose a severe risk to global health, necessitating intense scientific effort. Osteoporosis is a common chronic condition with substantial clinical implications on mortality, morbidity, and quality of life. It is closely linked to bone fractures. Worldwide, osteoporosis affects around 200 million people, and every year, there are almost 9 million fractures. There is evidence that certain environmental factors may increase the risk of osteoporosis in addition to traditional risk factors. It is crucial to understand the molecular mechanisms at play because there is a connection between osteoporosis and exposure to environmental pollutants such as heavy metals, air pollutants, endocrine disruptors, metal ions and trace elements. Hence, in this scoping review, we explore potential explanations for the link between pollutants and bone deterioration through deep insights into molecular pathways. Understanding and recognizing these pollutants as modifiable risk factors for osteoporosis would possibly help to enhance environmental policy thereby aiding in the improvement of bone health and improving patient quality of life.

m6A demethylase FTO and osteoporosis: potential therapeutic interventions

Osteoporosis is a common bone disease, characterized by a descent in bone mass due to the dysregulation of bone homeostasis. Although different studies have identified an association between osteoporosis and epigenetic alterations in osteogenic genes, the mechanisms of osteoporosis remain unclear. N6-methyladenosine (m6A) modification is a methylated adenosine nucleotide, which regulates the translocation, exporting, translation, and decay of RNA. FTO is the first identified m6A demethylase, which eliminates m6A modifications from RNAs. Variation in FTO disturbs m6A methylation in RNAs to regulate cell proliferation, differentiation, and apoptosis. Besides, FTO as an obesity-associated gene, also affects osteogenesis by regulating adipogenesis. Pharmacological inhibition of FTO markedly altered bone mass, bone mineral density and the distribution of adipose tissue. Small molecules which modulate FTO function are potentially novel remedies to the treatment of osteoporosis by adjusting the m6A levels. This article reviews the roles of m6A demethylase FTO in regulating bone metabolism and osteoporosis.

Peak Bone Mass Formation: Modern View of the Problem

Peak bone mass is the amount of bone tissue that is formed when a stable skeletal state is achieved at a young age. To date, there are no established peak bone mass standards nor clear data on the age at which peak bone mass occurs. At the same time, the level of peak bone mass at a young age is an important predictor of the onset of primary osteoporosis. The purpose of this review is to analyze the results of studies of levels of peak bone mass in general, the age of its onset, as well as factors influencing its formation. Factors such as hormonal levels, body composition, physical activity, nutrition, heredity, smoking, lifestyle, prenatal predictors, intestinal microbiota, and vitamin and micronutrient status were considered, and a comprehensive scheme of the influence of these factors on the level of peak bone mass was created. Determining the standards and timing of the formation of peak bone mass, and the factors affecting it, will help in the development of measures to prevent its shortage and the consequent prevention of osteoporosis and concomitant diseases.

Cinnamaldehyde Alleviates Bone Loss by Targeting Oxidative Stress and Mitochondrial Damage via the Nrf2/HO-1 Pathway in BMSCs and Ovariectomized Mice

Osteoporosis (OP) is typically brought on by disruption of bone homeostasis. Excessive oxidative stress and mitochondrial dysfunction are believed to be the primary mechanisms underlying this disorder. Therefore, in order to restore bone homeostasis effectively, targeted treatment of oxidative stress and mitochondrial dysfunction is necessary. Cinnamaldehyde (CIN), a small molecule that acts as an agonist for the nuclear factor erythroid 2-related factor (Nrf2), has been found to possess antiapoptotic, anti-inflammatory, and antioxidant properties. We found that CIN, while rescuing apoptosis, can also reduce the accumulation of reactive oxygen species (ROS) to improve mitochondrial dysfunction and thus restore the osteogenic differentiation potential of BMSCs disrupted by hydrogen peroxide (H2O2) exposure. The role of CIN was preliminarily considered to be a consequence of Nrf2/HO-1 axis activation. The ovariectomized mice model further demonstrated that CIN treatment ameliorated oxidative stress in vivo, partially reversing OVX-induced bone loss. This improvement was seen in the trabecular microarchitecture and bone biochemical indices. However, when ML385 was concurrently injected with CIN, the positive effects of CIN were largely blocked. In conclusion, this study sheds light on the intrinsic mechanisms by which CIN regulates BMSCs and highlights the potential therapeutic applications of these findings in the treatment of osteoporosis.

Arctiin attenuates iron overload‑induced osteoporosis by regulating the PI3K/Akt pathway

Iron overload is a prevalent pathological factor observed among elderly individuals and those with specific hematological disorders, and is frequently associated with an elevated incidence of osteoporosis. Although arctiin (ARC) has been shown to possess antioxidant properties and the ability to mitigate bone degeneration, its mechanism of action in the treatment of iron overload‑induced osteoporosis (IOOP) remains incompletely understood. To explore the potential molecular mechanisms underlying the effects of ARC, the MC3T3‑E1 cell osteoblast cell line was used. Cell Counting Kit was used to assess MC3T3‑E1 cell viability. Alkaline phosphatase staining and alizarin red staining were assessed for osteogenic differentiation. Calcein AM assay was used to assess intracellular iron concentration. In addition, intracellular levels of reactive oxygen species (ROS), lipid peroxides, mitochondrial ROS, apoptosis rate and mitochondrial membrane potential changes in MC3T3‑E1 cells were examined using flow cytometry and corresponding fluorescent dyes. The relationship between ARC and the PI3K/Akt pathway was then explored by western blotting and immunofluorescence. In addition, the effects of ARC on IOOP was verified using an iron overload mouse model. Immunohistochemistry was performed to evaluate expression of osteogenesis‑related proteins. Micro-CT and H&E were used to analyze bone microstructural parameters and histomorphometric indices in the bone tissue. Notably, ARC treatment reversed the decreased viability and increased apoptosis in MC3T3‑E1 cells originally induced by ferric ammonium citrate, whilst promoting the formation of mineralized bone nodules in MC3T3‑E1 cells. Furthermore, iron overload induced a decrease in the mitochondrial membrane potential, augmented lipid peroxidation and increased the accumulation of ROS in MC3T3‑E1 cells. ARC not only positively regulated the anti‑apoptotic and osteogenic capabilities of these cells via modulation of the PI3K/Akt pathway, but also exhibited antioxidant properties by reducing oxidative stress. In vivo experiments confirmed that ARC improved bone microarchitecture and biochemical parameters in a mouse model of iron overload. In conclusion, ARC exhibits potential as a therapeutic agent for IOOP by modulating the PI3K/Akt pathway, and via its anti‑apoptotic, antioxidant and osteogenic properties.

Advances in the study of traditional Chinese medicine affecting bone metabolism through modulation of oxidative stress

Bone metabolic homeostasis is dependent on coupled bone formation dominated by osteoblasts and bone resorption dominated by osteoclasts, which is a process of dynamic balance between bone formation and bone resorption. Notably, the formation of bone relies on the development of bone vasculature. Previous studies have shown that oxidative stress caused by disturbances in the antioxidant system of the whole organism is an important factor affecting bone metabolism. The increase in intracellular reactive oxygen species can lead to disturbances in bone metabolism, which can initiate multiple bone diseases, such as osteoporosis and osteoarthritis. Traditional Chinese medicine is considered to be an effective antioxidant. Cumulative evidence shows that the traditional Chinese medicine can alleviate oxidative stress-mediated bone metabolic disorders by modulating multiple signaling pathways, such as Nrf2/HO-1 signaling, PI3K/Akt signaling, Wnt/β-catenin signaling, NF-κB signaling, and MAPK signaling. In this paper, the potential mechanisms of traditional Chinese medicine to regulate bone me-tabolism through oxidative stress is summarized to provide direction and theoretical basis for future research related to the treatment of bone diseases with traditional Chinese medicine.

Targeting estrogen signaling and biosynthesis for aged skin repair

Non-healing skin wounds are disproportionally prevalent in older adults. Current treatments do not account for the particularities of aged skin and result in inadequate outcomes. Overall, healing chronic wounds in the elderly remains a major unmet clinical need. Estrogens play a critical role in reproduction but also have important actions in non-reproductive organs. Estrogen biosynthesis and signaling pathways are locally activated during physiological wound healing, processes that are inhibited in elderly estrogen-deprived skin. Estrogen deprivation has been shown to be a critical mediator of impaired wound healing in both postmenopausal women and aged men, and topical estrogen application reverses age-associated delayed wound healing in both elderly men and women. These data indicate that adequate estrogen biosynthesis and properly regulated estrogen signaling pathways are essential for normal wound healing and can be targeted to optimize tissue repair in the elderly. However, due to fundamental questions regarding how to safely restore estrogen signaling locally in skin wounds, there are currently no therapeutic strategies addressing estrogen deficiency in elderly chronic wounds. This review discusses established and recent literature in this area and proposes the hypothesis that estrogen plays a pleiotropic role in skin aging and that targeting estrogen signaling and biosynthesis could promote skin repair in older adults.

Association between the ESR1 and ESR2 polymorphisms and osteoporosis risk: An updated meta-analysis

BACKGROUND

Gene polymorphisms of estrogen receptor (ESR) 1 PvuII (rs2234693), XbaI (rs9340799), G2014A (rs2228480), ESR2 AluI (rs4986938), and RsaI (rs1256049) had been reported to be associated with the risk of osteoporosis. However, these conclusions were inconsistent, therefore, an updated meta-analysis was conducted to further explore these issues.

OBJECTIVE

To evaluate the association between gene polymorphisms of ESR1 PvuII (rs2234693), XbaI (rs9340799), G2014A (rs2228480), ESR2 AluI (rs4986938), RsaI (rs1256049), and osteoporosis risk.

MATERIALS AND METHODS

PubMed, Medline, Ovid, Embase, CNKI, and China Wanfang databases were searched. Association was assessed using odds ratio with 95% confidence interval. Moreover, the false-positive reporting probability, Bayesian false-finding probability, and Venetian criteria were used to assess the credibility of statistically significant associations.

RESULTS

Overall, ESR1 PvuII (rs2234693) and XbaI (rs9340799) were associated with the risk of osteoporosis in Indians. Moreover, ESR1 G2014A (rs2228480) was associated with the decreased risk of osteoporosis in East Asians. Moreover, ESR2 Alul (rs4986938) was associated with the increased risk of osteoporosis in East Asians and Caucasians. There was a significant association between ESR2 Rsal (rs1256049) and osteoporosis risk in overall population. When only high-quality and Hardy-Weinberg equilibrium studies were included in the sensitivity analysis, all results did not change in the present study. When the credibility was evaluated applying false-positive reporting probability, Bayesian false-finding probability, and Venetian criteria, all significant associations were considered as false positive results.

CONCLUSIONS

In summary, this study shows that all substantial associations between gene polymorphisms of ESR1 (PvuII, XbaI, and G2014A) and ESR 2 (AluI and RsaI) and osteoporosis risk are possibly false positive results instead of real associations or biological variables.

The Role of Oxidative Stress in Multiple Exercise-Regulated Bone Homeostasis

Bone is a tissue that is active throughout the lifespan, and its physiological activities, such as growth, development, absorption, and formation, are always ongoing. All types of stimulation that occur in sports play an important role in regulating the physiological activities of bone. Here, we track the latest research progress locally and abroad, summarize the recent, relevant research results, and systematically summarize the effects of different types of exercise on bone mass, bone strength and bone metabolism. We found that different types of exercise have different effects on bone health due to their unique technical characteristics. Oxidative stress is an important mechanism mediating the exercise regulation of bone homeostasis. Excessive high-intensity exercise does not benefit bone health but induces a high level of oxidative stress in the body, which has a negative impact on bone tissue. Regular moderate exercise can improve the body's antioxidant defense ability, inhibit an excessive oxidative stress response, promote the positive balance of bone metabolism, delay age-related bone loss and deterioration of bone microstructures and have a prevention and treatment effect on osteoporosis caused by many factors. Based on the above findings, we provide evidence for the role of exercise in the prevention and treatment of bone diseases. This study provides a systematic basis for clinicians and professionals to reasonably formulate exercise prescriptions and provides exercise guidance for patients and the general public. This study also provides a reference for follow-up research.

Mitochondrial Genetics and Function as Determinants of Bone Phenotype and Aging

PURPOSE OF REVIEW

The purpose of this review is to summarize the recently published scientific literature regarding the effects of mitochondrial function and mitochondrial genome mutations on bone phenotype and aging.

RECENT FINDINGS

While aging and sex steroid levels have traditionally been considered the most important risk factors for development of osteoporosis, mitochondrial function and genetics are being increasingly recognized as important determinants of bone health. Recent studies indicate that mitochondrial genome variants found in different human populations determine the risk of complex degenerative diseases. We propose that osteoporosis should be among such diseases. Studies have shown the deleterious effects of mitochondrial DNA mutations and mitochondrial dysfunction on bone homeostasis. Mediators of such effects include oxidative stress, mitochondrial permeability transition, and dysregulation of autophagy. Mitochondrial health plays an important role in bone homeostasis and aging, and understanding underlying mechanisms is critical in leveraging this relationship clinically for therapeutic benefit.

MT2 INHIBITS OSTEOCLASTOGENESIS BY SCAVENGING ROS

Context and objective

Reactive oxygen species (ROS) produced under oxidative stress is important for osteoclastogenesis. As a major member of the metallothionein (MT) family, metallothionein2 (MT2) can scavenge ROS in osteoblasts. However, the role of MT2 in osteoclastogenesis and ROS production in osteoclast precursors (OCPs) is unknown.

Material and methods

In this study, we first investigated MT2 expression level in osteoporotic model mice. Next, we explored the roles of MT2 in osteoclastic differentiation and ROS production in OCPs. Ultimately, via rescue assays based on hydrogen peroxide (H2O2), the significance of ROS in MT-2-regulated osteoclastic differentiation was further elucidated.

Results

Compared with sham operated (Sham) mice, ovariectomized (OVX) mice displayed bone marrow primary OCPs (Ly6C+CD11b-) having higher ROS levels and lower MT2 expression. MT2 overexpression inhibited the formation of mature osteoclasts, while MT2 knockdown was contrary. Moreover, MT2 overexpression inhibited ROS production in OCPs, while MT2 knockdown exhibited the opposite effects. Notably, the inhibitory effect of MT2 overexpression on osteoclastogenesis and ROS production was blocked by the addition of H2O2.

Conclusion

MT2 inhibits osteoclastogenesis through repressing ROS production in OCPs, which indicates that the strategy of upregulating MT2 in OCPs may be applied to the clinical treatment of osteoclastic bone loss.

Sulforaphene suppresses RANKL-induced osteoclastogenesis and LPS-induced bone erosion by activating Nrf2 signaling pathway

BACKGROUND AND PURPOSE

Inflammatory disorders have been found to induce bone loss through sustained and persistent activation of osteoclast differentiation, leading to heightened bone resorption. The current pharmacological interventions for combating bone loss to harbor adverse effects or contraindications. There is a pressing need to identify drugs with fewer side effects.

EXPERIMENTAL APPROACH

The effect and underlying mechanism of sulforaphene (LFS) on osteoclast differentiation were illustrated in vitro and in vivo with RANKL-induced Raw264.7 cell line osteoclastogenesis and lipopolysaccharide (LPS)-induced bone erosion model.

KEY RESULTS

In this study, LFS has been shown to effectively impede the formation of mature osteoclasts induced from both Raw264.7 cell line and bone marrow macrophages (BMMs), mainly at the early stage. Further mechanistic investigations uncovered that LFS suppressed AKT phosphorylation. SC-79, a potent AKT activator, was found to reverse the inhibitory impact of LFS on osteoclast differentiation. Moreover, transcriptome sequencing analysis revealed that treatment with LFS led to a significant upregulation in the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and antioxidant-related genes. Then it's validated that LFS could promote NRF2 expression and nuclear translocation, as well as effectively resist oxidative stress. NRF2 knockdown reversed the suppression effect of LFS on osteoclast differentiation. In vivo experiments provide convincing evidence that LFS is protective against LPS-induced inflammatory osteolysis.

CONCLUSION AND IMPLICATIONS

These well-grounded and promising findings suggest LFS as a promising agent to addressing oxidative-stress related diseases and bone loss disorders.

The osteogenic and mineralogenic potential of the microalgae Skeletonema costatum and Tetraselmis striata CTP4 in fish models

Skeletal disorders are problematic aspects for the aquaculture industry as skeletal deformities, which affect most species of farmed fish, increase production costs and affect fish welfare. Following recent findings that show the presence of osteoactive compounds in marine organisms, we evaluated the osteogenic and mineralogenic potential of commercially available microalgae strains Skeletonema costatum and Tetraselmis striata CTP4 in several fish systems. Ethanolic extracts increased extracellular matrix mineralization in gilthead seabream (Sparus aurata) bone-derived cell cultures and promoted osteoblastic differentiation in zebrafish (Danio rerio) larvae. Long-term dietary exposure to both extracts increased bone mineralization in zebrafish and upregulated the expression of genes involved in bone formation (sp7, col1a1a, oc1, and oc2), bone remodeling (acp5a), and antioxidant defenses (cat, sod1). Extracts also improved the skeletal status of zebrafish juveniles by reducing the incidence of skeletal anomalies. Our results indicate that both strains of microalgae contain osteogenic and mineralogenic compounds, and that ethanolic extracts have the potential for an application in the aquaculture sector as dietary supplements to support fish bone health. Future studies should also identify osteoactive compounds and establish whether they can be used in human health to broaden the therapeutic options for bone erosive disorders such as osteoporosis.

Association of selenium intake with bone mineral density and osteoporosis: the national health and nutrition examination survey

Background

Osteoporosis (OP) is a systemic metabolic skeletal disorder characterized by a decrease in bone mineral density (BMD) and an increase in the risk of fracture. The level of selenium (Se) in serum is associated with BMD. However, the relationship between dietary and total selenium intake and parameters such as osteoporosis and BMD is unclear. By conducting National Health and Nutritional Examination Surveys (NHANES), in this study, we assessed the association of Se intake with BMD and the risk of OP among general middle-aged and elderly people.

Methods

The data were collected from three cycles of NHANES [2009-2010, 2013-2014, and 2017-2020]. Information on the dietary and supplementary Se intake was obtained from 24-h dietary recall interviews. Additionally, dual-energy X-ray absorptiometry (DXA) was performed to measure BMD, which was later transformed into T-scores; OP was diagnosed when the T-score was ≤ -2.5. We constructed a logistic regression model for the association between selenium intake and the risk of OP based on the estimated odds ratios (ORs) and the 95% confidence intervals (CIs). We also constructed a multivariable linear regression model to analyze the relationship between selenium intake and BMD.

Results

In this study, 3,250 individuals (average age: 60.01 ± 10.09 years; 51.88% females) participated. The incidence of OP was 9.35% (3.30% for males and 17.75% for females). In the logistic regression model adjusted for every interested covariate, a higher quartile of dietary Se intake (OR for quartile 4 vs. quartile 1: 0.63; 95% CI: 0.41-0.96; P for trend = 0.027) was related to a lower risk of OP relative to the lowest quartile. The total selenium intake also exhibited a consistent trend (OR for quartile 4 vs. quartile 1: 0.67; 95% CI: 0.44-1.01; P for trend = 0.049). The results of the adjusted multivariate linear regression model showed that the participants with the highest quartile of dietary Se intake (Q4) had higher BMD in the total femur (β = 0.069, P = 0.001; P for trend = 0.001), femoral neck (β = 0.064, P = 0.001; P for trend = 0.001), and total spine (β = 0.030, P = 0.136; P for trend = 0.064) compared to those in quintile 1 (Q1). A similar trend of associations was observed for the total selenium intake with BMD, which was more prominent among females, as determined by the subgroup analysis.

Conclusion

In this study, the dietary intake and total intake of selenium were positively associated with BMD, whereas they were negatively associated with the risk of OP among adults in the US. Further studies are required to verify our results and elucidate the associated biological mechanism.

The beneficial effects of simultaneous supplementation of Lactobacillus reuteri and calcium fluoride nanoparticles on ovariectomy-induced osteoporosis

BACKGROUND

The development of new strategies to inhibit and/or treat osteoporosis as a chronic systemic disease is one of the most crucial topics. The present study aimed to investigate the simultaneous effects of calcium fluoride nanoparticles (CaF2 NPs) and lactobacillus reuteri ATCC PTA 6475 (L. reuteri) against osteoporosis in an ovariectomized rat model (OVX).

METHODS

In this study, 18 matured Wistar female rats were randomly assigned into 6 groups, including control, OVX, sham, OVX + L. reuteri, OVX + CaF2 NPs, and OVX + L. reuteri + CaF2 NPs. We used OVX rats to simulate post-menopausal osteoporosis, and the treatments were begun two weeks before OVX and continued for four weeks. All groups' blood samples were collected, and serum biomarkers (estrogen, calcium, vitamin D3, and alkaline phosphatase (ALP)) were measured. The tibia and Femur lengths of all groups were measured. Histopathological slides of tibia, kidney, and liver tissues were analyzed using the Hematoxylin and Eosin staining method.

RESULTS

Our results revealed that dietary supplementation of L. reuteri and CaF2 NPs in low doses for 6 weeks did not show adverse effects in kidney and liver tissues. The tibial and femoral lengths of OVX rats as well as the population of osteoblasts and osteocytes and newly generated osteoid in the tibia remarkably increased in the combination therapy group. Moreover, there was a significant increase in serum estrogen levels and a significant decrease in serum calcium and alkaline phosphatase levels in combination treatment groups compared to the OVX groups not receiving the diet.

CONCLUSIONS

Our results suggest the favorable effects of the simultaneous supplementation of L. reuteri and CaF2 NP to reduce post-menopausal bone loss.

Protective effects of curcumin against osteoporosis and its molecular mechanisms: a recent review in preclinical trials

Osteoporosis (OP) is one of the most common metabolic skeletal disorders and is commonly seen in the elderly population and postmenopausal women. It is mainly associated with progressive loss of bone mineral density, persistent deterioration of bone microarchitecture, and increased fracture risk. To date, drug therapy is the primary method used to prevent and treat osteoporosis. However, long-term drug therapy inevitably leads to drug resistance and specific side effects. Therefore, researchers are constantly searching for new monomer compounds from natural plants. As a candidate for the treatment of osteoporosis, curcumin (CUR) is a natural phenolic compound with various pharmacological and biological activities, including antioxidant, anti-apoptotic, and anti-inflammatory. This compound has gained research attention for maintaining bone health in various osteoporosis models. We reviewed preclinical and clinical studies of curcumin in preventing and alleviating osteoporosis. These results suggest that if subjected to rigorous pharmacological and clinical trials, naturally-derived curcumin could be used as a complementary and alternative medicine for the treatment of osteoporosis by targeting osteoporosis-related mechanistic pathways. This review summarizes the mechanisms of action and potential therapeutic applications of curcumin in the prevention and mitigation of osteoporosis and provides reference for further research and development of curcumin.

Acid sphingomyelinase mediates ferroptosis induced by high glucose via autophagic degradation of GPX4 in type 2 diabetic osteoporosis

BACKGROUND

Ferroptosis has been implicated in the pathological process of type 2 diabetic osteoporosis (T2DOP), although the specific underlying mechanisms remain largely unknown. This study aimed to clarify the role and possible mechanism of acid sphingomyelinase (ASM)-mediated osteoblast ferroptosis in T2DOP.

METHODS

We treated hFob1.19 cells with normal glucose (NG) and different concentrations of high glucose (HG, 26.25 mM, 35 mM, or 43.75 mM) for 48 h. We then measured cell viability and osteogenic function, quantified ferroptosis and autophagy levels, and measured the levels of ASM and ceramide in the cells. To further investigate the specific mechanism, we examined these indicators by knocking down ASM expression, hydroxychloroquine (HCQ) treatment, or N-acetylcysteine (NAC) treatment. Moreover, a T2DOP rat model was induced and microcomputed tomography was used to observe the bone microstructure. We also evaluated the serum levels of iron metabolism-associated factors, ceramide and lipid peroxidation (LPO) and measured the expression of ASM, LC3 and GPX4 in bone tissues.

RESULTS

HG inhibited the viability and osteogenic function of osteoblasts by inducing ferroptosis in a concentration-dependent manner. Furthermore, the expression of ASM and ceramide and autophagy levels were increased by HG treatment, and these factors were required for the HG-induced reactive oxygen species (ROS) generation and LPO. Similarly, inhibiting intracellular ROS also reduced HG-induced ASM activation and autophagy. ASM-mediated activation of autophagy was crucial for HG-induced degradation of GPX4, and inhibiting ASM improved osteogenic function by decreasing HG-induced autophagy, GPX4 degradation, LPO and subsequent ferroptosis. We also found that inhibiting ASM could alleviated ferroptosis and autophagy and improved osteogenic function in a T2DOP rat model.

CONCLUSION

ASM-mediated autophagy activation induces osteoblast ferroptosis under HG conditions through the degradation of GPX4, providing a novel mechanistic insight into the treatment and prevention of T2DOP.

Association between dietary folate intake and bone mineral density in a diverse population: a cross-sectional study

BACKGROUND

Osteoporosis is a major public health problem, yet the association between dietary folate intake and bone health has been rarely studied. This study aimed to investigate the relationship between dietary folate intake and bone mineral density (BMD) in the general population of the USA.

METHODS

Utilizing data from the National Health and Nutrition Examination Survey, dietary folate intake was gauged through 24-h dietary recall and BMD was determined via dual-energy X-ray absorptiometry. Multivariate linear regression models and generalized additive models were employed for correlation analysis.

RESULTS

The study incorporated 9839 participants (48.88% males, aged 20-85 years, mean age: 47.62 ± 16.22). The average dietary folate intake stood at 401.1 ± 207.9 μg/day. And the average total femur, femoral neck, trochanter, intertrochanter, and lumbar BMD were 0.98 ± 0.16 g/cm2, 0.84 ± 0.15 g/cm2, 0.73 ± 0.13 g/cm2, 1.16 ± 0.19 g/cm2, and 1.03 ± 0.15 g/cm2, respectively. The higher quartiles of dietary folate intake directly correlated with increased total femoral, femoral neck, intertrochanteric, and lumbar BMD (P for trend = 0.003, 0.016, < 0.001, and 0.033, respectively). A consistent positive association between folate intake and BMD across age groups was observed, with significant findings for individuals over 80 years and non-Hispanic whites. Physical activity level and serum 25-hydroxyvitamin D levels influenced the association, with an optimal daily folate intake of 528-569 µg recommended for postmenopausal women.

CONCLUSION

In summary, our study reveals a significant positive association between dietary folate intake and BMD, across different age groups and particularly among individuals over 80 years old. Non-Hispanic whites benefit the most from increased folate intake. Physical activity level and serum 25-hydroxyvitamin D levels interact with this association. Screening and early intervention for osteoporosis may be essential for individuals with low dietary folate intake.

Major vault protein (MVP) suppresses aging- and estrogen deficiency-related bone loss through Fas-mediated apoptosis in osteoclasts

Osteoclasts (OCs), derived from monocyte/macrophage lineage, are key orchestrators in bone remodeling. Targeting osteoclast apoptosis is a promising approach to cut down excessive osteoclast numbers, and thus slow down the rate of bone mass loss that inevitably occurs during aging. However, the therapeutic target of apoptosis in osteoclasts has not been fully studied. Our previous work generated Mvpf/fLyz2-Cre mice, conditionally depleting major vault protein (MVP) in monocyte lineage, and identified MVP as a bone protector for its negative role in osteoclastogenesis in vivo and in vitro. Here, we observed a notable decline of MVP in osteoclasts with aging in mice, encouraging us to further investigate the regulatory role of osteoclast MVP. Then, Mvpf/fLyz2-Cre mice were exploited in two osteoporosis contexts, aging and abrupt loss of estrogen, and we revealed that conditional knockout of MVP inhibited osteoclast apoptosis in vivo and in vitro. Moreover, we reported the interaction between MVP and death receptor Fas, and MVP-Fas signaling cascade was identified to positively regulate the apoptosis of osteoclasts, thus preventing osteoporosis. Collectively, our comprehensive discovery of MVP's regulatory role in osteoclasts provides new insight into osteoclast biology and therapeutic targets for osteoporosis.

A novel small molecule effectively ameliorates estrogen deficiency-induced osteoporosis by targeting the gut-bone signaling axis

Postmenopausal osteoporosis stems mainly from estrogen deficiency leading to a gut microbiome-dependent disruption of host systemic immunity. However, the underlying mechanisms of estrogen deficiency-induced bone loss remain elusive and novel pharmaceutical intervention strategies for osteoporosis are needed. Here we reveal that ovariectomy (ovx)-induced estrogen deficiency in C57BL/6 mice causes significant disruption of gut microbiota composition, consequently leading to marked destruction of intestinal barrier function and gut leakage. As a result, signals transportation between intestinal microbiota and T cells from the gut to bone marrow is identified to contribute to osteoclastogenesis in ovx mice. Notably, we show that icariside I (GH01), a novel small molecule naturally occurring in Herbal Epimedium, has potential to alleviate or prevent ovx-induced bone loss in mice through regulation of gut-bone signaling axis. We find that GH01 treatment can effectively restore the gut microbiota composition, intestinal barrier function and host immune status markedly altered in ovx mice, thus significantly ameliorating bone loss and osteoporosis. These findings not only provide systematic understanding of the gut-immunity-bone axis-associated pathophysiology of osteoporosis, but also demonstrate the high potential of GH01 for osteoporosis treatment by targeting the gut-bone signaling axis.

The role of non-coding RNAs in diabetes-induced osteoporosis

Diabetes mellitus (DM) and osteoporosis are two major health care problems worldwide. Emerging evidence suggests that DM poses a risk for osteoporosis and can contribute to the development of diabetes-induced osteoporosis (DOP). Interestingly, some epidemiological studies suggest that DOP may be at least partially distinct from those skeletal abnormalities associated with old age or postmenopausal osteoporosis. The increasing number of DM patients who also have DOP calls for a discussion of the pathogenesis of DOP and the investigation of drugs to treat DOP. Recently, non-coding RNAs (ncRNAs) have received more attention due to their significant role in cellular functions and bone formation. It is worth noting that ncRNAs have also been demonstrated to participate in the progression of DOP. Meanwhile, nano-delivery systems are considered a promising strategy to treat DOP because of their cellular targeting, sustained release, and controlled release characteristics. Additionally, the utilization of novel technologies such as the CRISPR system has expanded the scope of available options for treating DOP. Hence, this paper explores the functions and regulatory mechanisms of ncRNAs in DOP and highlights the advantages of employing nanoparticle-based drug delivery techniques to treat DOP. Finally, this paper also explores the potential of ncRNAs as diagnostic DOP biomarkers.

Lower bone mineral density can be a risk for an enlarging bone marrow lesion: A longitudinal cohort study of Japanese women without radiographic knee osteoarthritis

OBJECTIVES

The aim is to elucidate the relationship between bone mineral density (BMD) at baseline and the change of bone marrow lesion (BML) during a 2-year follow-up (2YFU) period.

METHODS

Seventy-eight female participants (mean age: 54.9 ± 9.6 years) without radiographic knee osteoarthritis were eligible. Based on right-knee magnetic resonance imaging, maximum BML area (BMLa) was calculated by tracing the BML border. The change in BMLa was defined using the following formula: [2YFU] - [Baseline] = ΔBMLa. Positive ΔBMLa was defined as enlarged; negative ΔBMLa was defined as regressed. Dual-energy X-ray absorptiometry was performed to measure the BMD of distal radius. Young adult mean [YAM (%)] of the BMD was used for statistical analysis. Linear regression analysis was conducted with ΔBMLa as the dependent variable and YAM as the independent variable. Receiver operating characteristic curve and logistic regression analyses were conducted for YAM to predict the prevalence of BML enlargement or regression.

RESULTS

Twenty-six (33.3%) patients had enlarged BMLa, 12 (15.4%) participants showed regressing BMLa, and 40 (51.3%) patients remained stable. YAM was negatively associated with ΔBMLa (β: - 0.375, P = 0.046). The best predictor of BML enlargement risk was 85% (odds ratio: 8.383, P = 0.025).

CONCLUSIONS

Lower BMD could predict BML enlargement during a 2YFU period.