Estrogen deficiency increases osteoclastogenesis up-regulating T cells activity: a key mechanism in osteoporosis

Molecular mechanisms and treatment strategies for estrogen deficiency-related and glucocorticoid-induced osteoporosis: a comprehensive review

Osteoporosis, a debilitating condition characterized by reduced bone mass and increased fracture risk, is notably influenced by estrogen deficiency and glucocorticoid treatment. This comprehensive review elucidates the molecular mechanisms underpinning estrogen deficiency-related osteoporosis (EDOP) and glucocorticoid-induced osteoporosis (GIOP). The role of estrogen in bone metabolism is critically examined, highlighting its regulatory effects on bone turnover and formation through various signaling pathways. Conversely, this review explores how glucocorticoids disrupt bone homeostasis, focusing on their impact on osteoclast and osteoblast function and the subsequent alteration of bone remodeling processes. The pathogenesis of both conditions is intertwined, with estrogen receptor signaling pathways and the role of inflammatory cytokines being pivotal in driving bone loss. A detailed analysis of pathogenetic and risk factors associated with EDOP and GIOP is presented, including lifestyle and genetic factors contributing to disease progression. Modern therapeutic approaches emphasize pharmacologic, non-pharmacologic, and herbal treatments for managing EDOP and GIOP. In summary, current therapeutic strategies highlight the efficacy and the safety of various interventions. This review concludes with future directions for research, suggesting a need for novel treatment modalities and a deeper understanding of the underlying mechanisms of osteoporosis. By addressing the multifaceted nature of EDOP and GIOP, this work aims to provide insights into developing targeted therapeutic strategies and improving patient outcomes in osteoporosis management.

Effects of the Curcuminoid and Non-Curcuminoid Compounds of Turmeric on the Gut Microbiome and Inflammation: Potential Use in the Treatment and Prevention of Disease

The gut microbiome is a complex system that directly interacts with and influences many systems in the body. This delicate balance of microbiota plays an important role in health and disease and is highly influenced by lifestyle factors and the surrounding environment. As further research emerges, understanding the full potential of the gut microbiome and the impact of using nutraceuticals to positively influence its function may open the door to greater therapeutic outcomes in the treatment and prevention of disease. Curcumin, a bioactive compound derived from the turmeric rhizome, has been studied in depth for its influence on human health as a potent anti-inflammatory and antioxidant properties. However, the therapeutic activity of curcumin is limited by its low oral bioavailability. While most available research has primarily focused on the curcuminoid compounds of turmeric, the non-curcuminoid compounds hold promise to offer therapeutic benefits while synergistically enhancing the bioavailability of curcumin and supporting the gut microbiome. This review summarizes current knowledge of the relationship between the gut and the various systems within the body, and how dysbiosis, or disruption in the gut microbial balance, leads to inflammation and increased risk of chronic disease. The review also summarizes recent research that focuses on the bioactivity of both the curcuminoid and non-curcuminoid compounds that comprise the whole turmeric root and their synergistic role in enhancing bioavailability to support a healthy gut microbiome and promising use in the treatment and prevention of disease.

Fecal microbiota transplantation from postmenopausal osteoporosis human donors accelerated bone mass loss in mice

Objectives

To investigate the effect of gut microbiota from postmenopausal osteoporosis patients on bone mass in mice.

Methods

Fecal samples were collected from postmenopausal women with normal bone mass (Con, n=5) and postmenopausal women with osteoporosis (Op, n=5). Microbial composition was identified by shallow shotgun sequencing. Then fecal samples were transplanted into pseudo-sterile mice previously treated with antibiotics for 4 weeks. These mice were categorized into two groups: the Vehicle group (n=7) received fecal samples from individuals with normal bone mass, and the FMT group (n=7) received fecal samples from individuals with osteoporosis. After 8 weeks, bone mass, intestinal microbial composition, intestinal permeability and inflammation were assessed, followed by a correlation analysis.

Results

The bone mass was significantly reduced in the FMT group. Microbiota sequencing showed that Shannon index (p < 0.05) and Simpson index (p < 0.05) were significantly increased in Op groups, and β diversity showed significant differences. the recipient mice were similar. linear discriminant analysis effect size (LEfSe) analysis of mice showed that Halobiforma, Enterorhabdus, Alistipes, and Butyricimonas were significantly enriched in the FMT group. Lachnospiraceae and Oscillibacter were significantly enriched in the Vehicle group. H&E staining of intestinal tissues showed obvious intestinal mucosal injury in mice. Intestinal immunohistochemistry showed that the expression of Claudin and ZO-1 in the intestinal tissue of the FMT group mice was decreased. The FITC-Dextran (FD-4) absorption rate and serum soluble CD14 (sCD14) content were increased in FMT mice. Correlation analysis showed that these dominant genera were significantly associated with bone metabolism and intestinal permeability, and were associated with the enrichment of specific enzymes. Serum and bone tissue inflammatory cytokines detection showed that the expression of TNF-α and IL-17A in the FMT group were significantly increased.

Conclusion

Overall, our findings suggested gut microbiota from postmenopausal osteoporosis patients accelerate bone mass loss in mice. Aberrant gut microbiota might play a causal role in the process of bone mass loss mediated by inflammation after the destruction of the intestinal barrier.

Osteoporosis in postmenopausal women is associated with disturbances in gut microbiota and migration of peripheral immune cells

BACKGROUND

Postmenopausal osteoporosis (PMO) results from a reduction in bone mass and microarchitectural deterioration in bone tissue due to estrogen deficiency, which may increase the incidence of fragility fractures. In recent years, the "gut-immune response-bone" axis has been proposed as a novel potential approach in the prevention and treatment of PMO. Studies on ovariectomized murine model indicated the reciprocal role of Th17 cells and Treg cells in the aetiology of osteoporosis. However, the relationship among gut microbiota, immune cells and bone metabolic indexes remains unknown in PMO.

METHODS

A total of 77 postmenopausal women were recruited for the study and divided into control (n = 30), osteopenia (n = 19), and osteoporosis (n = 28) groups based on their T score. The frequency of Treg and Th17 cells in lymphocytes were analyzed by flow cytometry. The serum levels of interleukin (IL)-10, 17 A, 1β, 6, tumor necrosis factor (TNF)-α, and lipopolysaccharide (LPS) were determined via enzyme-linked immunosorbent assay. Additionally, 16S rRNA gene V3-V4 region sequencing analysis was performed to investigate the gut microbiota of the participants.

RESULTS

The results demonstrated decreased bacterial richness and diversed intestinal composition in PMO. In addition, significant differences of relative abundance of the gut microbial community in phylum and genus levels were found, mainly including increased Bacteroidota, Proteobacteria, and Campylobacterota, as well as reduced Firmicutes, Butyricicoccus, and Faecalibacterium. Intriugingly, in the osteoporosis group, the concentration of Treg cells and associated IL-10 in peripheral circulation was negatively regulated, while other chronic systemic proinflammatory cytokines and Th17 cells showed opposite trends. Moreover, significantly elevated plasma lipopolysaccharide (LPS) in patients with osteoporosis indicated that disrupted intestinal integrity and permeability. A correlation analysis showed close relationships between gut bacteria and inflammation.

CONCLUSIONS

Collectively, these observations will lead to a better understanding of the relationship among bone homeostasis, the microbiota, and circulating immune cells in PMO. The elevated LPS levels of osteoporosis patients which not only indicate a breach in intestinal integrity but also suggest a novel biomarker for assessing osteoporosis risk linked to gut health.

The potential application of fermented tea as a drink for regulating bone mass

Currently, there is evidence to suggest the benefits of drinking fermented tea for people with osteoporosis, and based on this, many studies have been conducted on the dosage, exact ingredients, mechanisms, and industrial applications of fermented tea for protecting against osteoporosis. A summary and analysis of studies on the regulation of bone mass by oolong tea, black tea, and their active ingredients (including 39 known catechin compounds) was conducted. It was found that the regulation of bone mass by fermented tea is backed by evidence from epidemiology, animal experiments, and cell experiments. The main active components of fermented tea are tea polyphenols, tea pigments, and trace amino acids. The specific mechanisms involved include regulating bone marrow mesenchymal stem cell osteogenesis, inhibiting osteoclast activity, promoting calcium and phosphorus absorption, reducing inflammation levels, regulating gut microbiota, regulating endocrine function, and inhibiting oxidative stress. In terms of its application, extraction, precipitation, biosynthesis and membrane separation method are mainly used to separate the active ingredients of anti osteoporosis from fermented tea. In conclusion, fermented tea has sufficient theoretical and practical support for regulating bone mass and preventing osteoporosis, and is suitable for development as a health supplement. At the same time, a large amount of epidemiological evidence is needed to prove the specific dosage of tea consumption.

Characteristics of the gut microbiota and serum metabolites in postmenopausal women with reduced bone mineral density

Introduction

Emerging evidence suggests that the gut microbiota is closely associated with bone homeostasis. However, little is known about the relationships among the bone mineral density (BMD) index, bone turnover markers, and the gut microbiota and its metabolites in postmenopausal women.

Methods

In this study, to understand gut microbiota signatures and serum metabolite changes in postmenopausal women with reduced BMD, postmenopausal individuals with normal or reduced BMD were recruited and divided into normal and OS groups. Feces and serum samples were collected for 16S rRNA gene sequencing, liquid chromatography coupled with mass spectrometry (LC-MS)-based metabolomics and integrated analysis.

Results

The results demonstrated that bacterial richness and diversity were greater in the OS group than in the normal group. Additionally, distinguishing bacteria were found among the two groups and were closely associated with the BMD index and bone turnover markers. Metabolomic analysis revealed that the expression of serum metabolites, such as etiocholanolone, testosterone sulfate, and indole-3-pyruvic acid, and the corresponding signaling pathways, especially those involved in tryptophan metabolism, fatty acid degradation and steroid hormone biosynthesis, also changed significantly. Correlation analysis revealed positive associations between normal group-enriched Bacteroides abundance and normal group-enriched etiocholanolone and testosterone sulfate abundances; in particular, Bacteroides correlated positively with BMD. Importantly, the tryptophan-indole metabolism pathway was uniquely metabolized by the gut bacteria-derived tnaA gene, the predicted abundance of which was significantly greater in the normal group than in the control group, and the abundance of Bacteroides was strongly correlated with the tnaA gene.

Discussion

Our results indicated a clear difference in the gut microbiota and serum metabolites of postmenopausal women. Specifically altered bacteria and derived metabolites were closely associated with the BMD index and bone turnover markers, indicating the potential of the gut microbiota and serum metabolites as modifiable factors and therapeutic targets for preventing osteoporosis.

The immune cells in modulating osteoclast formation and bone metabolism

Osteoclasts are pivotal in regulating bone metabolism, with immune cells significantly influencing both physiological and pathological processes by modulating osteoclast functions. This is particularly evident in conditions of inflammatory bone resorption, such as rheumatoid arthritis and periodontitis. This review summarizes and comprehensively analyzes the research progress on the regulation of osteoclast formation by immune cells, aiming to unveil the underlying mechanisms and pathways through which diseases, such as rheumatoid arthritis and periodontitis, impact bone metabolism.

Age-related bone diseases: Role of inflammaging

Bone aging is characterized by an imbalance in the physiological and pathological processes of osteogenesis, osteoclastogenesis, adipogenesis, and chondrogenesis, resulting in exacerbated bone loss and the development of age-related bone diseases, including osteoporosis, osteoarthritis, rheumatoid arthritis, and periodontitis. Inflammaging, a novel concept in the field of aging research, pertains to the persistent and gradual escalation of pro-inflammatory reactions during the aging process. This phenomenon is distinguished by its low intensity, systemic nature, absence of symptoms, and potential for management. The mechanisms by which inflammaging contribute to age-related chronic diseases, particularly in the context of age-related bone diseases, remain unclear. The precise manner in which systemic inflammation induces bone aging and consequently contributes to the development of age-related bone diseases has yet to be fully elucidated. This article primarily examines the mechanisms underlying inflammaging and its association with age-related bone diseases, to elucidate the potential mechanisms of inflammaging in age-related bone diseases and offer insights for developing preventive and therapeutic strategies for such conditions.

Transcriptional reprogramming during human osteoclast differentiation identifies regulators of osteoclast activity

Enhanced osteoclastogenesis and osteoclast activity contribute to the development of osteoporosis, which is characterized by increased bone resorption and inadequate bone formation. As novel antiosteoporotic therapeutics are needed, understanding the genetic regulation of human osteoclastogenesis could help identify potential treatment targets. This study aimed to provide an overview of transcriptional reprogramming during human osteoclast differentiation. Osteoclasts were differentiated from CD14+ monocytes from eight female donors. RNA sequencing during differentiation revealed 8 980 differentially expressed genes grouped into eight temporal patterns conserved across donors. These patterns revealed distinct molecular functions associated with postmenopausal osteoporosis susceptibility genes based on RNA from iliac crest biopsies and bone mineral density SNPs. Network analyses revealed mutual dependencies between temporal expression patterns and provided insight into subtype-specific transcriptional networks. The donor-specific expression patterns revealed genes at the monocyte stage, such as filamin B (FLNB) and oxidized low-density lipoprotein receptor 1 (OLR1, encoding LOX-1), that are predictive of the resorptive activity of mature osteoclasts. The expression of differentially expressed G-protein coupled receptors was strong during osteoclast differentiation, and these receptors are associated with bone mineral density SNPs, suggesting that they play a pivotal role in osteoclast differentiation and activity. The regulatory effects of three differentially expressed G-protein coupled receptors were exemplified by in vitro pharmacological modulation of complement 5 A receptor 1 (C5AR1), somatostatin receptor 2 (SSTR2), and free fatty acid receptor 4 (FFAR4/GPR120). Activating C5AR1 enhanced osteoclast formation, while activating SSTR2 decreased the resorptive activity of mature osteoclasts, and activating FFAR4 decreased both the number and resorptive activity of mature osteoclasts. In conclusion, we report the occurrence of transcriptional reprogramming during human osteoclast differentiation and identified SSTR2 and FFAR4 as antiresorptive G-protein coupled receptors and FLNB and LOX-1 as potential molecular markers of osteoclast activity. These data can help future investigations identify molecular regulators of osteoclast differentiation and activity and provide the basis for novel antiosteoporotic targets.

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.

Progress of linking gut microbiota and musculoskeletal health: casualty, mechanisms, and translational values

The musculoskeletal system is important for balancing metabolic activity and maintaining health. Recent studies have shown that distortions in homeostasis of the intestinal microbiota are correlated with or may even contribute to abnormalities in musculoskeletal system function. Research has also shown that the intestinal flora and its secondary metabolites can impact the musculoskeletal system by regulating various phenomena, such as inflammation and immune and metabolic activities. Most of the existing literature supports that reasonable nutritional intervention helps to improve and maintain the homeostasis of intestinal microbiota, and may have a positive impact on musculoskeletal health. The purpose of organizing, summarizing and discussing the existing literature is to explore whether the intervention methods, including nutritional supplement and moderate exercise, can affect the muscle and bone health by regulating the microecology of the intestinal flora. More in-depth efficacy verification experiments will be helpful for clinical applications.

Gut-spine axis: a possible correlation between gut microbiota and spinal degenerative diseases

As society ages, the number of patients with spinal degenerative diseases (SDD) is increasing, posing a major socioeconomic problem for patients and their families. SDD refers to a generic term for degenerative diseases of spinal structures, including osteoporosis (bone), facet osteoarthritis (joint), intervertebral disk degeneration (disk), lumbar spinal canal stenosis (yellow ligament), and spinal sarcopenia (muscle). We propose the term "gut-spine axis" for the first time, given the influence of gut microbiota (GM) on the metabolic, immune, and endocrine environment in hosts through various potential mechanisms. A close cross-talk is noted between the aforementioned spinal components and degenerative diseases. This review outlines the nature and role of GM, highlighting GM abnormalities associated with the degeneration of spinal components. It also summarizes the evidence linking GM to various SDD. The gut-spine axis perspective can provide novel insights into the pathogenesis and treatment of SDD.

Inflammation and gut dysbiosis as drivers of CKD-MBD

Two decades ago, Kidney Disease: Improving Global Outcomes coined the term chronic kidney disease-mineral and bone disorder (CKD-MBD) to describe the syndrome of biochemical, bone and extra-skeletal calcification abnormalities that occur in patients with CKD. CKD-MBD is a prevalent complication and contributes to the excessively high burden of fractures and cardiovascular disease, loss of quality of life and premature mortality in patients with CKD. Thus far, therapy has focused primarily on phosphate retention, abnormal vitamin D metabolism and parathyroid hormone disturbances, but these strategies have largely proved unsuccessful, thus calling for paradigm-shifting concepts and innovative therapeutic approaches. Interorgan crosstalk is increasingly acknowledged to have an important role in health and disease. Accordingly, mounting evidence suggests a role for both the immune system and the gut microbiome in bone and vascular biology. Gut dysbiosis, compromised gut epithelial barrier and immune cell dysfunction are prominent features of the uraemic milieu. These alterations might contribute to the inflammatory state observed in CKD and could have a central role in the pathogenesis of CKD-MBD. The emerging fields of osteoimmunology and osteomicrobiology add another level of complexity to the pathogenesis of CKD-MBD, but also create novel therapeutic opportunities.

Gut microbiota as a target in the bone health of livestock and poultry: roles of short-chain fatty acids

The regulation and maintenance of bone metabolic homeostasis are crucial for animal skeletal health. It has been established that structural alterations in the gut microbiota and ecological dysbiosis are closely associated with bone metabolic homeostasis. The gut microbiota and its metabolites, especially short-chain fatty acids (SCFAs), affect almost all organs, including the bone. In this process, SCFAs positively affect bone healing by acting directly on cells involved in bone repair after or by shaping appropriate anti-inflammatory and immunomodulatory responses. Additionally, SCFAs have the potential to maintain bone health in livestock and poultry because of their various biological functions in regulating bone metabolism, including immune function, calcium absorption, osteogenesis and osteolysis. This review primarily focuses on the role of SCFAs in the regulation of bone metabolism by gut microbiota and provides insight into studies related to bone health in livestock and poultry.

P2X7Rs: new therapeutic targets for osteoporosis

Increasing evidence suggests that both the occurrence and progression of osteoporosis are associated with inflammation, especially in primary osteoporosis. The maintenance of skeletal homeostasis is dependent on the complex regulation of bone metabolism. Numerous evidence suggested that purinoceptor networks are essential for bone homeostasis. In this review, the relationship between inflammation and the development of osteoporosis and the role of P2X7 receptor (P2X7R) in regulating the dynamic regulation of bone reconstruction were covered. We also discussed how P2X7R regulates the balance between resorption and bone formation by osteoblasts and reviewed the relevance of P2X7R polymorphisms in skeletal physiology. Finally, we analyzed potential targets of P2X7R for osteoporosis.

Specific targeting of inflammatory osteoclastogenesis by the probiotic yeast S. boulardii CNCM I-745 reduces bone loss in osteoporosis

Bone destruction is a hallmark of chronic inflammation, and bone-resorbing osteoclasts arising under such a condition differ from steady-state ones. However, osteoclast diversity remains poorly explored. Here, we combined transcriptomic profiling, differentiation assays and in vivo analysis in mouse to decipher specific traits for inflammatory and steady-state osteoclasts. We identified and validated the pattern-recognition receptors (PRR) Tlr2, Dectin-1, and Mincle, all involved in yeast recognition as major regulators of inflammatory osteoclasts. We showed that administration of the yeast probiotic Saccharomyces boulardii CNCM I-745 (Sb) in vivo reduced bone loss in ovariectomized but not sham mice by reducing inflammatory osteoclastogenesis. This beneficial impact of Sb is mediated by the regulation of the inflammatory environment required for the generation of inflammatory osteoclasts. We also showed that Sb derivatives as well as agonists of Tlr2, Dectin-1, and Mincle specifically inhibited directly the differentiation of inflammatory but not steady-state osteoclasts in vitro. These findings demonstrate a preferential use of the PRR-associated costimulatory differentiation pathway by inflammatory osteoclasts, thus enabling their specific inhibition, which opens new therapeutic perspectives for inflammatory bone loss.

Denosumab Is Superior to Raloxifene in Lowering Risks of Mortality and Ischemic Stroke in Osteoporotic Women

Both osteoporosis and cardiovascular disease (CVD) share similar pathways in pathophysiology and are intercorrelated with increased morbidity and mortality in elderly women. Although denosumab and raloxifene are the current guideline-based pharmacological treatments, their impacts on cardiovascular protection are yet to be examined. This study aimed to compare mortality rate and cardiovascular events between denosumab and raloxifene in osteoporotic women. Risks of CVD development and all-cause mortality were estimated using Cox proportional hazard regression. A total of 7972 (3986 in each group) women were recruited between January 2003 and December 2018. No significant difference between denosumab and raloxifene was observed in composite CVDs, myocardial infarction, or congestive heart failure. However, comparison of the propensity score matched cohorts revealed that patients with proportion of days covered (PDC) ≥60% had lower incidence of ischemic stroke in the denosumab group than that in the raloxifene group (aHR 0.68; 95% CI 0.47–0.98; p = 0.0399). In addition, all-cause mortality was lower in the denosumab group than in the raloxifene group (aHR 0.59; 95% CI 0.48–0.72; p = 0.001), except in patients aged <65 y/o in this cohort study. We concluded that denosumab is superior to raloxifene in lowering risks of all-cause mortality and certain ischemic strokes in osteoporotic women.

Valgus-varus deformity induced abnormal tissue metabolism, inflammatory damage and apoptosis in broilers

1. This study explored the tissue metabolic status and the relationship with inflammation in valgus-valgus deformity (VVD) broilers with increasing age.2. Tissue and blood from VVD and healthy broilers were collected at two, four and five weeks old. A fully automated biochemical analyser, real-time PCR, HE staining and enzyme-linked immunosorbent assay were used to detect tissue metabolic indexes, mRNA levels of inflammation and apoptosis cytokines in immune organs, histological changes and serum inflammation and immune-related protein contents in VVD broilers.3. The results showed that VVD increased the levels of total protein, albumin, alanine aminotransferase at five weeks of age, aspartate aminotransferase, urea and creatine kinase in blood at two weeks of age. It upregulated the gene expression of inflammatory factors IL-1β, IL-6, IL-8, TNF-α, NF-κB and TGF-β and apoptotic factors FAS, Bcl-2, caspase-3 and 9 in immune organs; increased levels of serum proteins TNF-α, IL-1β and IL-6 and decreased levels of serum immunoglobulins IgY and CD3⁺.4. In addition, with increasing age, IL-10 gene expression gradually increased in the BF and decreased in the spleen.5. In conclusion, VVD broilers have disorders of liver and kidney metabolism, inflammation and apoptosis of immune organs and increased levels of serum inflammatory factor proteins.

Association between Immunosenescence, Mitochondrial Dysfunction and Frailty Syndrome in Older Adults

Aging is associated with changes in the immune system, increased inflammation and mitochondrial dysfunction. The relationship between these phenomena and the clinical phenotype of frailty is unclear. Here, we evaluated the immune phenotypes, T cell functions and mitochondrial functions of immune cells in frail and robust older subjects. We enrolled 20 frail subjects age- and gender-matched with 20 robust controls, and T cell phenotype, response to immune stimulation, cytokine production and immune cell mitochondrial function were assessed. Our results showed that numbers of CD4+ and CD8+ T cells were decreased in frail subjects, without impairment to their ratios. Memory and naïve T cells were not significantly affected by frailty, whereas the expression of CD28 but not that of ICOS was decreased in T cells from frail subjects. T cells from robust subjects produced more IL-17 after CD28 stimulation. Levels of serum cytokines were similar in frail subjects and controls. Mitochondrial bioenergetics and ATP levels were significantly lower in immune cells from frail subjects. In conclusion, we suggest that changes in T cell profiles are associated with aging rather than with frailty syndrome; however, changes in T cell response to immune stimuli and reduced mitochondrial activity in immune cells may be considered hallmarks of frailty.

Fecal microbiota transplantation ameliorates bone loss in mice with ovariectomy-induced osteoporosis via modulating gut microbiota and metabolic function

BACKGROUND

Osteoporosis (OP) is a systemic metabolic bone disease characterized by decreased bone mass and destruction of bone microstructure, which tends to result in enhanced bone fragility and related fractures. The postmenopausal osteoporosis (PMOP) has a relatively high proportion, and numerous studies reveal that estrogen-deficiency is related to the imbalance of gut microbiota (GM), impaired intestinal mucosal barrier function and enhanced inflammatory reactivity. However, the underlying mechanisms remain unclear and the existing interventions are also scarce.

METHODS

In this study, we established a mouse model induced by ovariectomy (OVX) and conducted fecal microbiota transplantation (FMT) by gavage every day for 8 weeks. Subsequently, the bone mass and microarchitecture of mice were evaluated by the micro computed tomography (Micro-CT). The intestinal permeability, pro-osteoclastogenic cytokines expression, osteogenic and osteoclastic activities were detected by the immunohistological analysis, histological examination, enzyme-linked immunosorbent assay (ELISA) and western blot analysis accordingly. Additionally, the composition and abundance of GM were assessed by 16S rRNA sequencing and the fecal short chain fatty acids (SCFAs) level was measured by metabolomics.

RESULTS

Our results demonstrated that FMT inhibited the excessive osteoclastogenesis and prevented the OVX-induced bone loss. Specifically, compared with the OVX group, FMT enhanced the expressions of tight junction proteins (zonula occludens protein 1 (ZO-1) and Occludin) and suppressed the release of pro-osteoclastogenic cytokines (tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)). Furthermore, FMT also optimized the composition and abundance of GM, and increased the fecal SCFAs level (mainly acetic acid and propionic acid).

CONCLUSIONS

Collectively, based on GM-bone axis, FMT prevented the OVX-induced bone loss by correcting the imbalance of GM, improving the SCFAs level, optimizing the intestinal permeability and suppressing the release of pro-osteoclastogenic cytokines, which may be an alternative option to serve as a promising candidate for the prevention and treatment of PMOP in the future.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This study indicates the ingenious involvement of GM-bone axis in PMOP and the role of FMT in reshaping the status of GM and ameliorating the bone loss in OVX-induced mice. FMT might serve as a promising candidate for the prevention and treatment of PMOP in the future.

Changes in bone turnover markers in patients without bone metastases receiving immune checkpoint inhibitors: An exploratory analysis

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Immune checkpoint inhibitors (ICIs) are correlated with immune-related adverse events (irAEs) that may potentially affect all host tissues.

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The effects of ICIs on the skeleton are poorly investigated, thus we evaluated the changes of specific markers of bone resorption and formation.

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We found an increase of type I collagen C-terminal telopeptide (CTX-I) levels after 3 months of ICIs treatment with a concomitant reduction of N-terminal propeptide of type I procollagen (PINP) levels with a trend toward statistical significance.

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CTX-I increase was also associated with poor prognosis in terms of treatment response and survival.

Immune checkpoint inhibitors (ICIs) has revolutionized the treatment of different advanced solid tumors, but most patients develop severe immune-related adverse events (irAEs). Although a bi-directional crosstalk between bone and immune systems is widely described, the effect of ICIs on the skeleton is poorly investigated. Here, we analyze the changes in plasma levels of type I collagen C-terminal telopeptide (CTX-I) and N-terminal propeptide of type I procollagen (PINP), reference makers of bone turnover, in patients treated with ICIs and their association with clinical outcome.

A series of 44 patients affected by advanced non-small cell lung cancer or renal cell carcinoma, without bone metastases, and treated with ICIs as monotherapy were enrolled. CTX-I and PINP plasma levels were assessed at baseline and after 3 months of ICIs treatment by ELISA kits.

A significant increase of CTX-I with a concomitant decreasing trend towards the reduction of PINP was observed after 3 months of treatment. Intriguingly, CTX-I increase was associated with poor prognosis in terms of treatment response and survival. These data suggest a direct relationship between ICIs treatment, increased osteoclast activity and potential fracture risk.

Overall, this study reveals that ICIs may act as triggers for skeletal events, and if confirmed in larger prospective studies, it would identify a new class of skeletal-related irAEs.

The immune factors have complex causal regulation effects on bone mineral density

Recent evidence has gradually recognized that the immune and skeletal systems are two closely correlated systems, but the specific immune factors on bone mineral density (BMD) are largely unknown. Based on the summary-level data of genome-wide association studies (GWASs), we performed a series of analyses including two-sample Mendelian randomization (MR) analysis to test potential causal links between 731 immune traits [including median fluorescence intensities (MFIs), absolute cell (AC) counts, relative cell (RC) counts, and morphological parameters (MP)] and BMD. After false discovery rate (FDR) correction, 9 MFI-BMD, 16 AC-BMD, 22 RC-BMD, and 5 MP-BMD pairs reached the level of significance (FDR-adjusted p< 0.05). For MFI traits, the T- and B-cell panels had the largest number of significant immune trait pairs than other panels. CD40, as a molecule expressed by four subsets of monocytes, was highlighted due to its consistently positive correlation with BMD at four sites. For both AC and RC traits, immune traits from the T-cell panel were also highlighted, with CD39-positive T-cell subsets being the most frequently observed feature. For MP traits, the most significant association immune trait with BMD was SSC-A on CD14+ monocyte. Sensitivity analyses suggested that the identified immune factors were robust to pleiotropy. Multivariable MR analysis confirmed the independent causal effect of several immune traits on BMD. Mediation analyses showed that CD40 on monocytes could mediate multiple immune traits, especially the suggestive associations of CD27 on several memory B cells with BMD mediated by CD40 on CD14+ CD16- monocyte. Our study represents the first comprehensive evaluation of the causal effects of immune traits on the risk of osteoporosis. The findings highlighted the complex and important role of immune-derived factors in the pathogenesis of osteoporosis.

The Role of Prunes in Modulating Inflammatory Pathways to Improve Bone Health in Postmenopausal Women

The prevalence of osteoporosis among women aged 50 y and older is expected to reach 13.6 million by 2030. Alternative nonpharmaceutical agents for osteoporosis, including nutritional interventions, are becoming increasingly popular. Prunes (dried plums; Prunus domestica L.) have been studied as a potential whole-food dietary intervention to mitigate bone loss in preclinical models of osteoporosis and in osteopenic postmenopausal women. Sixteen preclinical studies using in vivo rodent models of osteopenia or osteoporosis have established that dietary supplementation with prunes confers osteoprotective effects both by preventing and reversing bone loss. Increasing evidence from 10 studies suggests that, in addition to antiresorptive effects, prunes exert anti-inflammatory and antioxidant effects. Ten preclinical studies have found that prunes and/or their polyphenol extracts decrease malondialdehyde and NO secretion, increase antioxidant enzyme expression, or suppress NF-κB activation and proinflammatory cytokine production. Two clinical trials have investigated the impact of dried plum consumption (50-100 g/d for 6-12 mo) on bone health in postmenopausal women and demonstrated promising effects on bone mineral density and bone biomarkers. However, less is known about the impact of prune consumption on oxidative stress and inflammatory mediators in humans and their possible role in modulating bone outcomes. In this review, the current state of knowledge on the relation between inflammation and bone health is outlined. Findings from preclinical and clinical studies that have assessed the effect of prunes on oxidative stress, inflammatory mediators, and bone outcomes are summarized, and evidence supporting a potential role of prunes in modulating inflammatory and immune pathways is highlighted. Key future directions to bridge the knowledge gap in the field are proposed.

Targeting chronic inflammation as a potential adjuvant therapy for osteoporosis

Systemic, chronic, low-grade inflammation (SCLGI) underlies the pathogenesis of various widespread diseases. It is often associated with bone loss, thus connecting chronic inflammation to the pathogenesis of osteoporosis. In postmenopausal women, osteoporosis is accompanied by SCLGI development, likely owing to estrogen deficiency. We propose that SCGLI persistence in osteoporosis results from failed inflammation resolution, which is mainly mediated by specialized, pro-resolving mediators (SPMs). In corroboration, SPMs demonstrate encouraging therapeutic effects in various preclinical models of inflammatory disorders, including bone pathology. Since numerous data implicate gut dysbiosis in osteoporosis-associated chronic inflammation, restoring balanced microbiota by supplementing probiotics and prebiotics could contribute to the efficient resolution of SCGLI. In the present review, we provide evidence for this hypothesis and argue that efficient SCGLI resolution may serve as a novel approach for treating osteoporosis, complementary to traditional anti-osteoporotic medications.

Effect of Administration of Azithromycin and/or Probiotic Bacteria on Bones of Estrogen-Deficient Rats

The gut microbiota plays an important role in maintaining homeostasis, including that of the skeletal system. Antibiotics may affect the skeletal system directly or indirectly by influencing the microbiota. Probiotic bacteria have been reported to favorably affect bones in conditions of estrogen deficiency. The aim of this study was to investigate the effects of azithromycin (AZM) administered alone or with probiotic bacteria (Lactobacillus rhamnosus; LR) on bones in estrogen-deficient rats. The experiments were carried out on mature rats divided into five groups: non-ovariectomized (NOVX) control rats, ovariectomized (OVX) control rats, and OVX rats treated with: LR, AZM, or AZM with LR. The drugs were administered for 4 weeks. Serum biochemical parameters, bone mineralization, histomorphometric parameters, and mechanical properties were examined. Estrogen deficiency increased bone turnover and worsened cancellous bone microarchitecture and mechanical properties. The administration of LR or AZM slightly favorably affected some skeletal parameters of estrogen-deficient rats. The administration of AZM with LR did not lead to the addition of the effects observed for the separate treatments, indicating that the effects could be microbiota-mediated.

Immunology of osteoporosis: relevance of inflammatory targets for the development of novel interventions

Osteoporosis is recognized as low bone mass and deteriorated bone microarchitecture. It is the leading cause of fractures and consequent morbidity globally. The established pathophysiological evidence favors the endocrine factors for osteoporosis and the role of the immune system on the skeletal system has been recently identified. Due to the common developmental niche bone and immune system interactions have led to the emergence of osteoimmunology. Immune dysregulation can initiate inflammatory conditions that adversely affect bone integrity. The role of immune cells, such as T-lymphocytes subsets (Th17), cannot be neglected in the pathogenesis of osteoporosis. Local inflammation within the bone from any cause attracts immune cells that participate in the activation of osteoclasts. This work summarizes the present knowledge of osteoimmunology in reference to osteoporosis and identifies novel targets for immunotherapy of osteoporosis.

Osteocyte CIITA aggravates osteolytic bone lesions in myeloma

Osteolytic destruction is a hallmark of multiple myeloma, resulting from activation of osteoclast-mediated bone resorption and reduction of osteoblast-mediated bone formation. However, the molecular mechanisms underlying the differentiation and activity of osteoclasts and osteoblasts within a myelomatous microenvironment remain unclear. Here, we demonstrate that the osteocyte-expressed major histocompatibility complex class II transactivator (CIITA) contributes to myeloma-induced bone lesions. CIITA upregulates the secretion of osteolytic cytokines from osteocytes through acetylation at histone 3 lysine 14 in the promoter of TNFSF11 (encoding RANKL) and SOST (encoding sclerostin), leading to enhanced osteoclastogenesis and decreased osteoblastogenesis. In turn, myeloma cell-secreted 2-deoxy-D-ribose, the product of thymidine catalyzed by the function of thymidine phosphorylase, upregulates CIITA expression in osteocytes through the STAT1/IRF1 signaling pathway. Our work thus broadens the understanding of myeloma-induced osteolysis and indicates a potential strategy for disrupting tumor-osteocyte interaction to prevent or treat patients with myeloma bone disease.

Genkwanin Prevents Lipopolysaccharide-Induced Inflammatory Bone Destruction and Ovariectomy-Induced Bone Loss

Objectives

The first objective of this study was to probe the effects of genkwanin (GKA) on osteoclast. The second goal of this study was to study whether GKA can protect lipopolysaccharide (LPS) and ovariectomized (OVX) induced bone loss.

Materials and Methods

Various concentrations of GKA (1 and 10 mg/kg) were injected into mice. Different concentrations of GKA (1 and 5 μM) were used to detect the effects of GKA on osteoclast and osteoblast.

Key Findings

GKA attenuated the osteoclast differentiation promoted by RANKL and expression of marker genes containing c-fos, ctsk as well as bone resorption related gene Trap and to the suppression of MAPK signaling pathway. In addition, GKA induced BMMs cell apoptosis in vitro. Moreover, GKA prevented LPS-induced and ovariectomized-induced bone loss in mice.

Conclusion

Our research revealed that GKA had a potential to be an effective therapeutic agent for osteoclast-mediated osteoporosis.

Toll-like receptor 9 deficiency induces osteoclastic bone loss via gut microbiota-associated systemic chronic inflammation

Toll-like receptors (TLRs) play pivotal roles in inflammation and provide important links between the immune and skeletal systems. Although the activation of TLRs may affect osteoclast differentiation and bone metabolism, whether and how TLRs are required for normal bone remodeling remains to be fully explored. In the current study, we show for the first time that TLR9^-/- mice exhibit a low bone mass and low-grade systemic chronic inflammation, which is characterized by the expansion of CD4⁺ T cells and increased levels of inflammatory cytokines, including TNFα, RANKL, and IL1β. The increased levels of these cytokines significantly promote osteoclastogenesis and induce bone loss. Importantly, TLR9 deletion alters the gut microbiota, and this dysbiosis is the basis of the systemic inflammation and bone loss observed in TLR9^-/- mice. Furthermore, through single-cell RNA sequencing, we identified myeloid-biased hematopoiesis in the bone marrow of TLR9^-/- mice and determined that the increase in myelopoiesis, likely caused by the adaptation of hematopoietic stem cells to systemic inflammation, also contributes to inflammation-induced osteoclastogenesis and subsequent bone loss in TLR9^-/- mice. Thus, our study provides novel evidence that TLR9 signaling connects the gut microbiota, immune system, and bone and is critical in maintaining the homeostasis of inflammation, hematopoiesis, and bone metabolism under normal conditions.

Gut Microbiota and Bone Diseases: A Growing Partnership

Gut microbiota is key to human health and disease. Convincing studies have demonstrated that dysbiosis in the commensal gut microbiota is associated with intestinal and extra-intestinal diseases. Recent explorations have significantly contributed to the understanding of the relationship between gut microbiota and bone diseases (osteoporosis, osteoarthritis, rheumatoid arthritis, and bone cancer). Gut microbiota and its metabolites may become associated with the development and progression of bone disorders owing to their critical role in nutrient absorption, immunomodulation, and the gut-brain-bone axis (regulation hormones). In this work, we review the recent developments addressing the effect of gut microbiota modulation on skeletal diseases and explore a feasible preventive approach and therapy for bone diseases.

Maternal Exposure to D-galactose Reduces Ovarian Reserve in Female Rat Offspring Later in Life

BACKGROUND

Embryonic life is critical for the formation of ovaries in mammals, and the intrauterine environment may affect ovarian reserve.

OBJECTIVES

The present study aimed to investigate the impact of prenatal D-galactose exposure on ovarian reserve in female rat offspring in their later lives.

METHODS

Ten pregnant Wistar rats were randomly divided into two groups. In one group, rats were fed with 35% D-galactose-enriched food from the third day to the end of pregnancy, and in the other group, rats were fed with a standard diet throughout pregnancy. Female offspring (prenatally galactose-exposed rats and non-exposed control rats) were examined in terms of hormonal levels [anti-Mullerian hormones (AMH), follicle-stimulating hormone (FSH), and estradiol (E2)] and ovarian histology at 45 - 50, 105 - 110, and 180 - 185 days of their age.

RESULTS

The number of primordial follicles significantly decreased time-dependently in prenatally galactose-exposed rats compared to controls (P-value = 0.002). In addition, decreases in AMH (3.25 vs. 7.5 ng/mL; P = 0.000) and E2 (7.9 vs. 19.5 pg/mL; P = 0.000) and increases in FSH (6.5 vs. 0.8 mIU/mL; P < 0.007) were observed in galactose-exposed rats compared to controls at 45 - 50 days of age.

CONCLUSIONS

Prenatal exposure to D-galactose negatively affects ovarian reserve in female rats in their later lives. However, further investigation is needed to confirm our findings and explore underlying mechanisms.

Cardiovascular Implications of Immune Disorders in Women

Immune responses differ between men and women, with women at higher risk of developing chronic autoimmune diseases and having more robust immune responses to many viruses, including HIV and hepatitis C virus. Although immune dysregulation plays a prominent role in chronic systemic inflammation, a key driver in the development of atherosclerotic cardiovascular disease (ASCVD), standard ASCVD risk prediction scores underestimate risk in populations with immune disorders, particularly women. This review focuses on the ASCVD implications of immune dysregulation due to disorders with varying global prevalence by sex: autoimmune disorders (female predominant), HIV (male-female equivalent), and hepatitis C virus (male predominant). Factors contributing to ASCVD in women with immune disorders, including traditional risk factors, dysregulated innate and adaptive immunity, sex hormones, and treatment modalities, are discussed. Finally, the need to develop new ASCVD risk stratification tools that incorporate variables specific to populations with chronic immune disorders, particularly in women, is emphasized.

Heat-Killed Lacticaseibacillus paracasei GMNL-653 Exerts Antiosteoporotic Effects by Restoring the Gut Microbiota Dysbiosis in Ovariectomized Mice

Osteoporosis is a metabolic inflammatory disease, an imbalance occurs between bone resorption and formation, leading to bone loss. Anti-inflammatory diet is considered having the potential to ameliorate osteoporosis. Heat-killed probiotics exhibit health benefits in relation to their immunomodulatory effects, but the detail mechanism involved in gut microbiota balance, host metabolism, immunity, and bone homeostasis remains unclear. In this study, we evaluated the antiosteoporotic effects of heat-killed Lacticaseibacillus paracasei GMNL-653 in vitro and in ovariectomized (OVX) mice. Furthermore, whole-genome sequencing and comparative genomics analysis demonstrated potentially genes involved in antiosteoporotic activity. The GMNL-653 exerts anti-inflammatory activity which restored gut microbiota dysbiosis and maintained intestinal barrier integrity in the OVX mice. The levels of IL-17 and LPS in the sera decreased following GMNL-653 treatment compared with those of the vehicle control; mRNA levels of RANKL were reduced and TGF-β and IL-10 enhanced in OVX-tibia tissue after treatment. The levels of IL-17 were significantly associated with gut microbiota dysbiosis. Gut microbial metagenomes were further analyzed by PICRUSt functional prediction, which reveal that GMNL-653 intervention influence in several host metabolic pathways. The analysis of whole-genome sequencing accompanied by comparative genomics on three L. paracasei strains revealed a set of GMNL-653 genes that are potentially involved in antiosteoporotic activity. Our findings validated antiosteoporotic activity of heat-killed GMNL-653 using in vitro and in vivo models, to whole-genome sequencing and identifying genes potentially involved in this gut microbiota–bone axis.

Bioactive coatings with anti-osteoclast therapeutic agents for bone implants: Enhanced compliance and prolonged implant life

The use of therapeutic agents that inhibit bone resorption is crucial to prolong implant life, delay revision surgery, and reduce the burden on the healthcare system. These therapeutic agents include bisphosphonates, various nucleic acids, statins, proteins, and protein complexes. Their use in systemic treatment has several drawbacks, such as side effects and insufficient efficacy in terms of concentration, which can be eliminated by local treatment. This review focuses on the incorporation of osteoclast inhibitors (antiresorptive agents) into bioactive coatings for bone implants. The ability of bioactive coatings as systems for local delivery of antiresorptive agents to achieve optimal loading of the bioactive coating and its release is described in detail. Various parameters such as the suitable concentrations, release times, and the effects of the antiresorptive agents on nearby cells or bone tissue are discussed. However, further research is needed to support the optimization of the implant, as this will enable subsequent personalized design of the coating in terms of the design and selection of the coating material, the choice of an antiresorptive agent and its amount in the coating. In addition, therapeutic agents that have not yet been incorporated into bioactive coatings but appear promising are also mentioned. From this work, it can be concluded that therapeutic agents contribute to the biocompatibility of the bioactive coating by enhancing its beneficial properties.

Menopausal Transition: Prospective Study of Estrogen Status, Circulating MicroRNAs, and Biomarkers of Bone Metabolism

OBJECTIVE

Osteoporosis is associated with an impaired balance between bone resorption and formation, which in turn leads to bone loss and fractures. Many recent studies have underlined the regulatory role of microRNAs (miRNAs) in bone remodeling processes and their potential as biomarkers of osteoporosis. The purpose of this study was to prospectively examine the association of circulating miRNAs and bone biomarkers with estrogen status in women before and after oophorectomy, as well as in oophorectomized women on estrogen therapy.

METHODS

In this prospective study, we included 11 women before oophorectomy and hysterectomy and at 201 ± 24 days after the surgery. Another 11 women were evaluated 508 ± 127 days after oophorectomy and hysterectomy and after an additional 203 ± 71 days of estradiol treatment. Serum miRNAs were profiled by sequencing. Estrogen status and biomarkers of bone metabolism were quantified. Bone mineral density was assessed in the lumbar spine.

RESULTS

Our analysis revealed 17 miRNAs associated with estrogen levels. Of those miRNAs that were upregulated with estrogen deficiency and downregulated after estrogen therapy, miR-422a correlated with serum beta-carboxy-terminal type I collagen crosslinks (β-CTX) and procollagen 1 N-terminal propeptide (P1NP); and miR-1278 correlated with serum β-CTX, P1NP, osteocalcin, sclerostin, and Dickkopf-1(Dkk1). In contrast, we found an inverse association of miR-24-1-5p with estrogen status and a negative correlation with serum β-CTX, P1NP, osteoprotegerin, and sclerostin levels.

CONCLUSION

The reported miRNAs associated with estrogen status and bone metabolism could be potential biomarkers of bone pathophysiology and would facilitate studies on the prevention of postmenopausal osteoporosis. Our findings require validation in an extended cohort.

The Microbiota-Bone-Allergy Interplay

Emerging knowledge suggests an increasing importance of gut microbiota in health and disease. Allergy and bone metabolism are closely interconnected, and the possible negative effects of common therapies are not the only aspects of this relationship. The immune system is influenced by the microbiota-host interactions, and several pieces of evidence suggest the existence of an interplay between microbiota, bone metabolism, and allergies. Understanding these inter-relationships is essential for the development of new potential strategies of treatment and prevention targeting microbiota. A wide range of substances and germs, prebiotics and probiotics, are capable of influencing and modifying the microbiota. Prebiotics and probiotics have been shown in several studies to have different actions based on various factors such as sex, hormonal status, and age. In this review, we summarize the latest knowledge on the topic, and we discuss practical implications and the need for further studies.

Estrogens and phytoestrogens in body functions

Estrogens are the hormones of reproduction in women as well as of many other important functions in the male and female body. They undergo significant changes in the different phases of life, e.g. during puberty, pregnancy or at menopause/andropause. Phytoestrogens are natural non-steroidal phenolic plant compounds that can mimic the activity of estrogens and their beneficial effects in women and in men. This narrative review summarizes the literature on the physiological role of estrogens and the several potential health benefits of phytoestrogens, with particular attention given to the possible role of phytoestrogens in aging.

Oral Osteomicrobiology: The Role of Oral Microbiota in Alveolar Bone Homeostasis

Osteomicrobiology is a new research field in which the aim is to explore the role of microbiota in bone homeostasis. The alveolar bone is that part of the maxilla and mandible that supports the teeth. It is now evident that naturally occurring alveolar bone loss is considerably stunted in germ-free mice compared with specific-pathogen-free mice. Recently, the roles of oral microbiota in modulating host defense systems and alveolar bone homeostasis have attracted increasing attention. Moreover, the mechanistic understanding of oral microbiota in mediating alveolar bone remodeling processes is undergoing rapid progress due to the advancement in technology. In this review, to provide insight into the role of oral microbiota in alveolar bone homeostasis, we introduced the term “oral osteomicrobiology.” We discussed regulation of alveolar bone development and bone loss by oral microbiota under physiological and pathological conditions. We also focused on the signaling pathways involved in oral osteomicrobiology and discussed the bridging role of osteoimmunity and influencing factors in this process. Finally, the critical techniques for osteomicrobiological investigations were introduced.

Modulation of Bone and Joint Biomarkers, Gut Microbiota, and Inflammation Status by Synbiotic Supplementation and Weight-Bearing Exercise: Human Study Protocol for a Randomized Controlled Trial

BACKGROUND

There is strong evidence suggesting that prebiotics and probiotics regulate gut microbiota, reducing inflammation and thereby potentially improving bone health status. Similarly, mechanistic evidence suggests that either low-impact or high-impact weight-bearing exercises improve body composition and consequently increase bone mineral density in individuals with osteoporosis and osteoarthritis.

OBJECTIVE

This study aims to investigate the effects of a synbiotic (probiotic+prebiotic) supplementation, an exercise intervention, or a combination of both on gut microbiota, inflammation, and bone biomarkers in postmenopausal women.

METHODS

A total of 160 postmenopausal women from New Zealand will be recruited and randomized to one of four interventions or treatments for 12 weeks: control, synbiotic supplementation, exercise intervention, or synbiotic supplementation and exercise. The primary outcome measure is the bone and joint biomarkers at baseline and week 12, whereas the gut microbiota profile and inflammatory cytokine measurements will serve as the secondary outcome measures at baseline and week 12. Baseline data and exercise history will be used to assess, allocate, and stratify participants into treatment measures.

RESULTS

Recruitment of participants will begin in September 2021, and the anticipated completion date is June 2022.

CONCLUSIONS

To the best of our knowledge, this will be the first randomized controlled trial to analyze the effects of both a synbiotic supplement and an exercise intervention in postmenopausal women. On the basis of the results obtained, a combination of synbiotic supplements and exercise might serve as a noninvasive approach to manage and/or improve body composition and bone health in postmenopausal women.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12620000998943p; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=380336&isClinicalTrial=False.

Betel Nut Chewing Decreased Calcaneus Ultrasound T-Score in a Large Taiwanese Population Follow-Up Study

Chewing betel nut is common in Taiwan. Although previous studies have shown that chewing betel nuts is associated with adverse health effects, findings about the impact on bone density have been inconsistent. Therefore, the aim of this study was to investigate the correlation between betel nut chewing and calcaneus ultrasound T-score in a longitudinal study of 118,856 participants from the Taiwan Biobank. Of these participants, 27,002 were followed up with for a median of 4 years. The T-score of the calcaneus was measured in the non-dominant foot using ultrasound. Multivariable analysis showed that a history of chewing betel nut (coefficient β = -0.232; p < 0.001) was significantly associated with low baseline T-score in all participants (n = 118,856). In addition, a long duration of betel nut chewing (per 1 year; coefficient β = -0.003; p = 0.022) was significantly associated with a low baseline T-score in the participants with a history of chewing betel nut (n = 7210). Further, a long duration of betel nut chewing (per 1 year; coefficient β = -0.004; p = 0.039) was significantly associated with a low ΔT-score in the participants with a history of chewing betel nut (n = 1778) after 4 years of follow-up. In conclusion, our results showed that betel nut chewing was associated with a decrease in calcaneus ultrasound T-score, and thus, it is important to stop chewing betel nut to help prevent an increased risk of osteoporosis in the Taiwanese population.

Human Immunodeficiency Virus (HIV) and Menopause Are Independently Associated With Lower Bone Mineral Density: Results From the Women's Interagency HIV Study

BACKGROUND

We previously reported lower bone mineral density (BMD) among premenopausal women with HIV (WWH) compared to women without HIV (HIV-). Rate of bone loss may be even greater for WWH during the menopausal transition.

METHODS

Pre-, peri- and postmenopausal women in the Women\'s Interagency HIV Study (WIHS) underwent whole body DXA and central quantitative computed tomography to measure areal BMD (aBMD) and volumetric BMD (vBMD), respectively. Multivariable regression models with covariates associated with low aBMD (T score < -1.0) in univariate analyses (P≤.05) and known risk factors for low BMD assessed contributions of HIV and menopausal stage to the prediction of aBMD.

RESULTS

Compared to HIV- women, in unadjusted analyses, WWH had 5-9% lower aBMD at the lumbar spine (P=.001), femoral neck (P=.04), total hip (P=.003) and the ultradistal radius (P=.004), and higher osteoporosis prevalence (T score<-2.5) at the ultradistal radius only (13.5% vs 0%, P=.0003). WWH also had lower vBMD at the spine and hip. In fully adjusted models, HIV independently predicted reduced aBMD at the lumbar spine, total hip, femoral neck, and ultradistal radius; menopausal stage remained a significant predictor of lumbar spine and ultradistal radius aBMD.

CONCLUSIONS

HIV infection and menopausal stage were independent predictors of lower BMD, and had an additive effect on lumbar spine and total hip BMD. Additional research is needed to better understand underlying mechanisms by which HIV impacts BMD as women age and transition through menopause, and develop strategies to mitigate osteoporosis and fracture risk in this growing population.

Analysis of the molecular mechanisms by flavonoids with potential use for osteoporosis prevention or therapy

BACKGROUND

Osteoporosis is the most common skeletal disorder worldwide. Flavonoids have the potential to alleviate bone alterations in osteoporotic patients with the advantage of being safer and less expensive than the conventional therapies.

OBJECTIVE

The main objective is to analyze the molecular mechanisms triggered in bone by different subclasses of flavonoids. In addition, this review provides an up-to-date overview on the cellular and molecular aspects of osteoporotic bones versus healthy bones, and a brief description of some epidemiological studies indicating that flavonoids could be useful for osteoporosis treatment.

METHODS

The PubMed database was searched in the range of years 2001- 2021 using the keywords osteoporosis, flavonoids, and their subclasses such as flavones, flavonols, flavanols, isoflavones, flavanones and anthocyanins, focusing the data on the molecular mechanisms triggered in bone.

RESULTS

Although flavonoids comprise many compounds that differ in structure, their effects on bone loss in postmenopausal women or in ovariectomized-induced osteoporotic animals are quite similar. Most of them increase bone mineral density and bone strength, which occur through enhancement of osteoblastogenesis and osteoclast apoptosis, decrease in osteoclastogenesis as well as increase in neovascularization on the site of the osteoporotic fracture.

CONCLUSION

Several molecules of signaling pathways are involved in the effect of flavonoids on osteoporotic bone. Whether all flavonoids have a common mechanism or they act as ligands of estrogen receptors remain to be established. More clinical trials are necessary to know better their safety, efficacy, delivery and bioavailability in humans, as well as comparative studies with conventional therapies.

Blood factors as biomarkers in osteoporosis: points from the COVID-19 era

The restrictions adopted during the coronavirus disease 2019 (COVID-19) pandemic limiting direct medical consultations and access to healthcare centers reduced the participation of patients with chronic diseases, such as osteoporosis (OP), in screening and monitoring programs. This highlighted the need for new screening diagnostic tools that are clinically effective, but require minimal technical and time commitments, to stratify populations and identify who is more at risk for OP and related complications. This paper provides an overview of the potential use of blood-related factors, such as platelet (PLT)- and monocyte-related factors, as biomarkers able to quickly screen, detect, and monitor OP in both sexes. Such biomarkers might be of key importance not only during the COVID-19 pandemic but also, even more importantly, during periods of better global health stability.

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

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

MSTN is an important myokine for weight-bearing training to attenuate bone loss in ovariectomized rats

Weight-bearing training, as one of resistance exercises, is beneficial to bone health. Myostatin (MSTN) is a negative regulator of skeletal muscle growth and development. Animals lacking MSTN show increased bone mineral density (BMD). The aim of this study was to investigate the preventive effect of weight-bearing training on bone loss in ovariectomized rats and whether it was related to MSTN. In this study, the rats were randomly assigned to three group: Sham-ovariectomized (Sham), ovariectomized (OVX), ovariectomized and weight-bearing training (OWT). The rats in the OWT group ran at 20-m/min bearing with 35% of their body weight for 6 days/week. After 10 weeks, compared with the OVX group, weight-bearing training increased the BMD of total femur and trabecular bone by 8.13% and 57.44%, respectively. The OVX-induced destruction of bone microarchitecture including the thickness and number of trabeculae and bone volume fraction was all significantly improved (9.26%, 47.68%, 63.03%) in the OWT group. The OVX-induced degradation of bone mechanical properties was significantly enhanced in the OWT group (maximum load increased by 35.46%, stiffness increased by 89.19%, energy absorption increased by 53.4%; elastic modulus increased by 26.3%). Ten-week weight-bearing training also significantly upregulated the mRNA and protein expression of Wnt1 and β-catenin, which is crucial in bone development. Compared with the Sham group, MSTN in serum and muscle increased in the OVX group, but it decreased in the OWT group compared with the OVX group. Its receptor ActRIIB and downstream molecules Smad2/3 in the OVX group were downregulated in bone by weight-bearing training. The results indicated that MSTN is an important myokine for weight-bearing training to attenuate bone loss in ovariectomized rats.

Increased frequency of Th17 cells and IL-17 levels are associated with low bone mineral density in postmenopausal women

Osteoporosis is one of the chronic and often neglected bone diseases in aging postmenopausal women that affect the quality of life. Studies on ovariectomized mice models indicated the reciprocal role of Th17 cells and Treg cells in the aetiology of osteoporosis. While Th17 cells promote osteoclastogenesis, Treg cells exhibit anti-osteoclastogenic activity. This exploratory study aimed to determine the difference in the frequency of these T-cell subtypes in pre-and postmenopausal women and to examine their association with BMD. In our study, the frequency of Treg cells, analyzed by flow cytometry, did not differ between pre-and postmenopausal women. However, plasma levels of IL-10 along with IL-10+CD4+T cells were higher in post- compared to premenopausal women. The frequency of Th17 cells was higher in postmenopausal women irrespective of their BMD, however, only postmenopausal women with low BMD had elevated IL-17 levels and their T-scores were associated with Th17 frequency. Collectively, the results suggest that estrogen insufficiency in postmenopausal women may lead to increased Th17 cell frequency and elevated IL-17 levels which are associated with low BMD. This study highlights, Th17 cells and IL-17 as key players in the pathogenesis of osteoporosis and they can be the potential targets for immunotherapy in the treatment of osteoporosis.

Inverse association between systemic immune-inflammation index and bone mineral density in postmenopausal women

OBJECTIVE

The aim of the present study was to investigate whether systemic immune-inflammation index (SII) and neutrophil-to-platelet ratio (NLR) were associated with bone mineral density (BMD) in postmenopausal women.

METHODS

In this cross-sectional study, we enrolled 413 postmenopausal women who never received menopause hormone therapy. The relationship between SII, NLR, and BMD was investigated by linear regression analysis.

RESULTS

Significant inverse association was observed between SII and BMD in postmenopausal women. The mean BMD in each quartile of SII level were 0.923, 0.914, 0.900, and 0.876 g/cm², respectively (p = .011). After adjusting for covariates, SII levels remained significantly associated with BMD (regression coefficients for quartiles 1-3 vs. quartile 4 were 0.035, 0.029, and 0.023, respectively; p for trend <.05). An inverse association was also found between NLR and BMD in postmenopausal women. However, there was no significant association between NLR and BMD after adjusting for covariates.

CONCLUSION

The quartile of SII was negatively associated with the mean BMD in postmenopausal women, independent of age, body mass index, sex hormone levels, and other factors. Therefore, SII can be used as a new predictor of bone loss in postmenopausal women.

The Gut Microbiome: a New Frontier in Musculoskeletal Research

PURPOSE OF THE REVIEW

The human gut harbors a complex community of microbes that influence many processes regulating musculoskeletal development and homeostasis. This review gives an update on the current knowledge surrounding the impact of the gut microbiota on musculoskeletal health, with an emphasis on research conducted over the last three years.

RECENT FINDINGS

The gut microbiota and their metabolites are associated with sarcopenia, osteoporosis, osteoarthritis, and rheumatoid arthritis. The field is moving fast from describing simple correlations to pursue establishing causation through clinical trials. The gut microbiota and their microbial-synthesized metabolites hold promise for offering new potential alternatives for the prevention and treatment of musculoskeletal diseases given its malleability and response to environmental stimuli.

Advances in the occurrence and biotherapy of osteoporosis

Osteoporosis (OP) is a bone metabolic disease, is characterized by degeneration of bone structure and decreased bone mass. It happens in more than 1/3 women and 1/5 men of over than 50 years old, which affects the health and lives of people. The main mechanism of OP is mainly that the dynamic balance between the bone formation and resorption is broken, so that bone resorption is more than bone formation. It is prone to result in bone metabolism disorder. There are many precipitating factor such as elder age, low hormone level, genetic factors and bad hobbies. At the same time, the occurrence of the OP and its complications has different degrees of impact on people's quality of life. Based on the current understanding of the OP, we summarized the etiology, current clinical drugs and potential targeting therapy for OP. Although the research have made many progress in explore what is the novel mechanism and how to improve the effect, there are still many problems in the treatment method that limit its application prospects and need to be solved. In this review, we mainly focus on the mechanism of OP and related research on the targeted treatment of OP. Hopefully, our summary will provide a reference to develop some novel strategies for the target therapy of OP.

Post-menopausal Osteoporosis and Probiotics

Postmenopausal osteoporosis (PMO) is characterized by low bone mass and structural deterioration of bone tissue with increased risk of fracture in postmenopausal women. It is due to the deficiency of estrogen production after menopause, which causes the imbalance in the bone remodeling process where resorption/formation skewed more towards resoption, which leads to bone loss. It causes high morbidity and severe health complication among the affected women. The current PMO therapy has many unwanted side effects and even increases the possibility of tumorigenesis. Therefore, an alternative therapy that is safe and effective is required. Probiotics are dietary supplements consisting of beneficial microbes and when administered in an adequate amount, confer a health benefit to the host. Recent scientific evidences suggested the link between the intestinal microbiota and bone health. This review discusses the process of bone remodeling and the role of intestinal microbiota on the bone metabolism of the host. Further, it summarizes the recent studies of probiotic on an animal model of PMO and also in post postmenopausal women.