The potential mechanism of the microbiota-gut-bone axis in osteoporosis: a review

Evaluation of causal links of gut microbiota and inflammatory cytokines with 10 fracture locations: A Mendelian randomization study

Recent investigations have revealed an association of variations in gut microbiota (GM) composition and inflammatory cytokine (IC) levels with fracture risk; however, the causal relationship of GM or inflammatory factors with fracture risk remains unelucidated. The study utilized Mendelian randomization (MR) analyses, utilizing aggregated data from the genome-wide association study of GM, ICs, and 10 fracture locations. The primary aim was to examine the causal associations between GM, ICs, and 10 fracture locations. Furthermore, mediational analyses and multivariate MR were conducted to explore the potential mediating role of ICs in this relationship. MR analysis identified 35 positive and 53 negative causal associations between GM and 10 fracture locations. ICs showed 22 positive and 24 negative correlations with 10 fracture locations. However, after false discovery rate correction, most associations lost significance, leaving only 1 IC significant for foot fractures. Moreover, our findings suggest that the ICs may be act as a mediating factor in the pathway from GM to 10 fracture locations. GM and ICs exhibited a significant causal relationship with the 10 fracture locations; furthermore, ICs may function as mediators in the pathway from GM to fracture risk.

A promising approach to diabetic osteoporosis: oxymatrine's effects on gut microbiota and osteoblasts

OBJECTIVES

Oxymatrine (OMT), a quinolizidine alkaloid derived from Sophora flavescens Ait., has demonstrated therapeutic potential in type 2 diabetes mellitus (T2DM). This study aimed to investigate its effects on diabetic osteoporosis (DOP) and explore the underlying mechanisms involving gut microbiota and osteogenic regulation.

METHODS

In a rat model of T2DM, intragastric Oxymatrine was used to study trabecular bone repair through bone microstructure and histopathology analyses. Changes in gut microbiota, especially Gram-negative bacteria releasing lipopolysaccharides (LPS), were assessed via 16S rRNA sequencing. miRNA sequencing on LPS-induced rat osteoblasts, with and without Oxymatrine, explored osteoblast proliferation, mineralization, and the miR-539-5p/OGN/Runx2 pathway.

RESULTS

The administration of OMT resulted in an enhancement of diabetic osteopathy by reversing trabecular bone loss and modifying the composition of gut microbiota, specifically affecting Gram-negative bacteria that release LPS into the bloodstream. miRNA sequencing revealed that miR-539-5p, which was upregulated in LPS-induced ROBs, was downregulated following OMT treatment. Furthermore, OMT was found to promote osteoblast proliferation and mineralization under conditions of LPS exposure and modulate the miR-539-5p/OGN/Runx2 signaling pathway.

CONCLUSIONS

OMT improves diabetic osteoporosis by altering gut microbiota, decreasing LPS release, and enhancing osteoblast growth and differentiation through the miR-539-5p/OGN/Runx2 pathway, suggesting its potential as a treatment.

Irisin mitigates osteoporotic-associated bone loss and gut dysbiosis in ovariectomized mice by modulating microbiota, metabolites, and intestinal barrier integrity

BACKGROUND

Osteoporotic bone defects significantly affect patient health and quality of life. The gut-bone axis plays a crucial role in osteoporosis, and disruptions in gut microbiota are linked to systemic inflammation and compromised bone metabolism. Irisin, a myokine, has shown potential in protecting against osteoporosis, but its mechanisms of action on the gut-bone axis remain unclear. This study aimed to investigate the role of irisin in mitigating osteoporotic bone defects by examining its effects on gut microbiota, related metabolites, and intestinal barrier integrity.

METHODS

An osteoporosis model was created using ovariectomized (OVX) mice. The mice were divided into Sham, OVX, and r-irisin groups. Mice in the r-irisin group received intraperitoneal injections of 100 μg/kg irisin twice weekly for five weeks. Bone parameters were analyzed by micro-CT and histological staining. Gut microbiota composition was examined via 16S rDNA sequencing. Intestinal cytokines and barrier proteins were measured using immunohistochemistry and ELISA. Fecal metabolomic profiling was conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and correlations between gut microbiota, metabolites, and bone metabolism markers were evaluated.

RESULTS

Irisin treatment improved bone mineral density (BMD), bone volume/tissue volume (BV/TV), trabecular bone thickness (Tb.Th), and trabecular number (Tb.N), and reduced trabecular separation (Tb.Sp) in OVX mice. It enhanced new bone formation and collagen deposition. Irisin restored intestinal barrier integrity by increasing tight junction protein expression and reducing inflammatory cytokines in intestinal tissues. It also modulated gut microbiota diversity, reducing Firmicutes and increasing Verrucomicrobiota abundance. Key fecal metabolites, including atractylon (r = - 0.60, P < 0.01) and enterodiol (r = + 0.83, P < 0.01), showed strong correlations with BMD.

CONCLUSION

Irisin mitigates osteoporotic bone defects by enhancing bone formation, restoring intestinal barrier integrity, modulating gut microbiota composition, and influencing fecal metabolites. These preclinical findings highlight irisin's potential to mitigate osteoporosis via the gut-bone axis.

Therapeutic effects of Isaria felina on postmenopausal osteoporosis: modulation of gut microbiota, metabolites, and immune responses

Background

The intricate relationship between human health and gut microecology has emerged as a central theme in contemporary medical research. Postmenopausal osteoporosis, primarily driven by estrogen deficiency, remains a major health concern. Traditional Chinese herbal medicines have attracted significant interest for their promising role in osteoporosis treatment.

Methods

The effects of Isaria felina, derived from Cordyceps sinensis, on postmenopausal osteoporosis in rats are the focus of this study. Adult female Sprague-Dawley rats were categorized into control, postmenopausal osteoporosis (OVX), and Isaria felina-treated (IF+OVX) groups. Following a 12-week treatment period, various analyses, including micro-CT, histological assessments, 16S rDNA sequencing, untargeted metabolomics, flow cytometry, and ELISA, were performed.

Results

Micro-CT and histological assessments indicated significant improvements in bone loss and obesity control in OVX rats treated with Isaria felina. 16S rDNA sequencing revealed that Isaria felina corrected gut microbiota dysbiosis, particularly in the Bacteroides and Ruminococcus genera. Untargeted metabolomics highlighted alterations in nucleotide and lipid metabolism. Flow cytometry and ELISA analyses demonstrated that Isaria felina modulated the Th17/Treg immune balance, resulting in reduced levels of inflammatory cytokines IL-17 and TNF-α.

Conclusions

These findings indicate that Isaria felina mitigates bone loss in postmenopausal osteoporosis through modulation of gut microbiota and immune responses, underscoring its potential as a therapeutic agent for osteoporosis treatment.

A promising fusion: Traditional Chinese medicine and probiotics in the quest to overcome osteoporosis

Botanical drugs and probiotic supplements present safer alternative options for the prevention and treatment of osteoporosis (OP). However, pathological disorders of the gut microbiota and the specific properties of probiotics and traditional Chinese medicine (TCM) significantly limit their therapeutic efficacy. Given the favorable synergistic and complementary effects between probiotics and herbal medicines, a creative combination of these approaches may address the issue of their current limited efficacy. A comprehensive analysis is necessary to provide a detailed review of their potential for combination, the mechanisms behind their synergy, scientific applications, and future developments. There exists a complex relationship between gut microbiota and OP, and the underlying regulatory mechanisms are multidimensional, involving the production of pro-inflammatory metabolites, immune system disruption, and the impairment of the intestinal mucosal barrier. Furthermore, we analyzed the complex mechanisms and potential connections between probiotics, TCM, and their combined applications. We highlighted the principle of complementary gain and the substantial therapeutic potential of their organic combination, which facilitates the release of active substances in TCM, increases the bioavailability of TCM, enhances probiotic delivery efficiency, and exerts synergistic effects. The combined use of probiotics and TCM offers a safe and effective strategy for managing OP and presents an innovative and promising direction for the future development of modern phytomedicine.

Interplay of gut microbiota in Kawasaki disease: role of gut microbiota and potential treatment strategies

Kawasaki disease (KD) is an acute systemic immune vasculitis with predominant involvement of the medium and small arteries. It mostly affects pediatric patients, representing the most common form of pediatric vasculitis in children less than 5 years old. Numerous diseases, especially those related to the immune system, have established links with the intestinal flora. Recent studies have investigated the intestinal flora changes throughout the management of KD. There was gut microbiota dysbiosis in pediatric KD at the acute phase, particularly the downregulation of short-chain fat acids-producing microbiota and the over-proliferation of opportunistic pathogens. The relationship between the response to therapies in individuals with KD and specific microbiota remains uncertain. Targeted microbial supplements and dietary regulation may serve as potential measures to alleviate KD complications and thus improve prognosis. This review provides an overview of the current understanding of the interplay of the gut microbiota and KD. Furthermore, it discusses the possibility of altering the gut microbiota to reinstate a healthy condition.

Effects of traditional Chinese medicine Zuo-Gui-Wan on gut microbiota in an osteoporotic mouse model

BACKGROUND

The target and mechanism of oral traditional Chinese medicine (TCM) have been important research directions for a long time. The close relationship between osteoporosis and gut microbiota (GM) has been confirmed. However, the relevance of oral TCM and the "Gut-Bone Axis" is still poorly understood.

METHODS

Twenty-one SPF C57BL/6J female mice were divided into sham (Sham), ovariectomized (OVX), and Zuo-Gui-Wan-treated (ZGW, 1.4 g/kg) groups. The osteoporosis mouse model was established through ovariectomy. After eight weeks of Zuo-Gui-Wan treatment via gavage, serum calcium, phosphorus, ALT, AST, CREA, and other biochemical indicators were measured. Subsequently, Micro-CT, HE staining, and analysis of gut microbiota were conducted to further explore the potential mechanism.

RESULTS

The anti-osteoporotic effects of ZGW were confirmed through micro-CT, histological, and biochemical tests in an OVX-induced osteoporosis mouse model. ZGW treatment also alters the diversity and composition of the gut microbiota and altered the Firmicutes/Bacteroidetes ratio. Further analysis reveals a correlation between specific bacterial groups and serum indicators. Mfuzz clustering analysis and metagenomeSeq analysis identified important microbiota species that were rescued or modulated by ZGW treatment.

CONCLUSION

These findings suggest that changes in gut microbiota abundance may be linked to ZGW's ability to improve osteoporosis. This study provides new insights into how ZGW treats osteoporosis, though further research is needed to clarify the mechanisms by which specific gut microbiota influence bone health.

Gut-bone axis perturbation: Mechanisms and interventions via gut microbiota as a primary driver of osteoporosis

A growing number of studies have highlighted the significance of human gut microbiota (GM) as a potential target for osteoporosis. In this review, we discuss the effect of GM to bone metabolism focusing on two aspects: the local alterations of the human gut permeability that modify how the GM interact with the gut-bone axis (e.g., intestinal leakage, nutrient absorption), and the alterations of the GM itself (e.g., changes in microbiota metabolites, immune secretion, hormones) that modify the events of the gut-bone axis. We then classify these changes as possible therapeutic targets of bone metabolism and highlight some associated promising microbiome-based therapies. We also extend our discussions into combinatorial treatments that incorporate conservative treatments, such as exercise. We anticipate our review can provide an overview of the current pathophysiological and therapeutic paradigms of the gut-bone axis, as well as the prospects of ongoing clinical trials for readers to gain further insights into better microbiome-based treatments to osteoporosis and other bone-degenerative diseases. The translational potential of this article: This paper reviewed the potential links between gut microbiota and osteoporosis, as well as the prospective therapeutic avenues targeting gut microbiota for osteoporosis management, presenting a thorough and comprehensive literature review.

Exhaled breath metabolites reveal postmenopausal gut-bone cross-talk and non-invasive markers for osteoporosis

BACKGROUND

Menopause driven decline in estrogen exposes women to risk of osteoporosis. Detection of early onset and silent progression are keys to prevent fractures and associated burdens.

METHODS

In a discovery cohort of 120 postmenopausal women, we combined repeated quantitative pulse-echo ultrasonography of bone, assessment of grip strength and serum bone markers with mass-spectrometric analysis of exhaled metabolites to find breath volatile markers and quantitative cutoff levels for osteoporosis. Obtained markers and cutoffs were validated in an independent cohort of 49 age-matched women with six months apart seasonal follow-ups.

RESULTS

Here, within the discovery cohort, concentrations of exhaled end-tidal dimethyl sulfide (DMS), allyl-methyl sulfide, butanethiol and butyric acid are increased (p ≤ 0.005) pronouncedly in subjects with bone mineral density (BMD) at high-risk of osteoporosis and fracture, when compared to subjects with normal BMD. Increased age and decreased grip strength are concomitant. All changes are reproduced during independent validation and seasonal follow-ups. Exhaled metabolite expressions remain age independent. Serum markers show random expressions without reproducibility. DMS exhalations differs between patients with recent, old and without fractures. Metabolite exhalations and BMDs are down-regulated during winter. ROC analysis in discovery cohort yields high classification accuracy of DMS with a cutoff for osteoporosis, which predicts subjects at high-risk within the independent validation cohort with >91% sensitivity and specificity.

CONCLUSIONS

Non-invasive analysis of exhaled DMS allowed more reliable classification of osteoporosis risk than conventional serum markers. We identified associations of exhaled organosulfur and short-chain fatty acids to bone metabolism in postmenopausal osteoporosis via a gut-bone axis.

Impact of dementia and mild cognitive impairment on bone health in older people

Mild cognitive impairment, dementia and osteoporosis are common diseases of ageing and, with the increasingly ageing global population, are increasing in prevalence. These conditions are closely associated, with shared risk factors, common underlying biological mechanisms and potential direct causal pathways. In this review, the epidemiological and mechanistic links between mild cognitive impairment, dementia and skeletal health are explored. Discussion will focus on how changes in brain and bone signalling can underly associations between these conditions, and will consider the molecular and cellular drivers in the context of inflammation and the gut microbiome. There is a complex interplay between nutritional changes, which may precede or follow the onset of mild cognitive impairment (MCI) or dementia, and bone health. Polypharmacy is common in patients with MCI or dementia, and there are difficult prescribing decisions to be made due to the elevated risk of falls associated with many drugs used for associated problems, which can consequently increase fracture risk. Some medications prescribed for cognitive impairment may directly impact bone health. In addition, patients may have difficulty remembering medication without assistance, meaning that osteoporosis drugs may be prescribed but not taken. Cognitive impairment may be improved or delayed by physical activity and exercise, and there is evidence for the additional benefits of physical activity on falls and fractures. Research gaps and priorities with the aim of reducing the burden of osteoporosis and fractures in people with MCI or dementia will also be discussed.

Probiotics: a promising intervention for osteoporosis prevention and management

Osteoporosis (OP) is a systemic skeletal disease that is characterized by low bone mass and increased fracture risk. This article explores the potential of probiotics as an adjunctive approach for the prevention and management of OP. It has been well established that the gut microbiota (GM), a complex community of microbes, plays an important role in bone health. The gut dysbiosis is linked with a higher risk of OP. However, the consumption of probiotics in adequate amounts restores gut health thus improving bone health. Probiotics may influence bone metabolism through enhanced calcium absorption, reduced inflammation, and increased bone formation. The animal and human studies demonstrate the positive effects of probiotics on bone health parameters like reduced osteoclastogenesis, bone resorption markers, osteoblast, osteocyte apoptosis, and increased bone mineral density and expression of osteoprotegerin. The current evidence suggests that probiotics can be used as an adjunctive approach along with the existing therapies for the prevention and management of OP.

Effects of probiotic supplementation on bone health in postmenopausal women: a systematic review and meta-analysis

Context

The beneficial effects of probiotic supplementation on bone health in postmenopausal women require further validation.

Objective

This study systematically reviewed and conducted a meta-analysis of randomized controlled trials (RCTs) to assess the relationship between probiotic supplementation and changes in bone mineral density (BMD) and bone turnover markers (BTMs) among postmenopausal women.

Methods

A systematic search was conducted across four databases to retrieve data on lumbar spine BMD, hip BMD, collagen type 1 cross-linked C-telopeptide (CTX), receptor activator of nuclear factor-κB ligand (RANKL), osteocalcin (OC), osteoprotegerin (OPG), N-terminal propeptide of type 1 procollagen (P1NP), and bone-specific alkaline phosphatase (BALP) in postmenopausal women. Eligible RCTs were quantitatively analyzed using random-effects meta-analyses. Additional analyses, including subgroup, sensitivity, and meta-regression analyses, were performed.

Results

Twelve RCTs involving 1183 postmenopausal women were included. Compared with the control group, postmenopausal women who received probiotic supplementation showed significantly greater BMD in both the lumbar spine (standardized mean difference [SMD] = 0.60, 95% confidence interval [CI] 0.14 to 1.05) and the hip (SMD = 0.74, 95%CI 0.15 to 1.33). Additionally, probiotic supplementation was associated with reduced levels of CTX (SMD = -1.51, 95%CI -1.88 to -0.41) and BALP (SMD = -1.80, 95%CI -2.78 to -0.81). No significant differences were found between the probiotic and control groups in terms of other BTMs. Subgroup analyses revealed that the increase in BMD due to probiotic supplementation was more significant in postmenopausal women with osteopenia than in those with osteoporosis. The meta-analysis results for both lumbar spine and hip BMD remained robust after conducting sensitivity analyses and meta-regressions.

Conclusion

Supplementation with probiotics may increase BMD among postmenopausal women, with stronger evidence in women with osteopenia than osteoporosis. Further RCTs are suggested to confirm and refine these findings.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024576764.

Mitigating lead-induced osteoporosis: The role of butyrate in gut-bone axis restoration

Lead (Pb) is an environmentally widespread bone toxic pollutant, contributes to the development of osteoporosis. Butyric acid, mainly produced by the fermentation of indigestible dietary fiber by gut microbiota, plays a pivotal role in the maintenance of bone homeostasis. However, the effects of butyric acids on the Pb induced osteoporosis have not yet been elucidated. In this study, our results showed that Pb exposure was negatively related to the abundance of butyric acid, in the Pb-exposed population and Pb-exposed mice. Pb exposure caused gut microbiota disorders, resulting in the decline of butyric acid-producing bacteria, such as Butyrivibrio_crossotus, Clostridium_sp._JN9, and the butyrate-producing enzymes through the acetyl-CoA pathway. Moreover, results from the NHANES data suggested that dietary intake of butyrate was associated with a reduced risk of osteoporosis in lead-burdened populations, particularly among men or participants aged 18-60 years. In addition, butyrate supplementation in mice with chronic Pb exposure improved the bone microarchitectures, repaired intestinal damage, upregulated the proportion of Treg cells. Taken together, these results demonstrated that chronic Pb exposure disturbs the gut-bone axis, which can be restored by butyric acid supplement. Our results suggest that butyrate supplementation is a possible therapeutic strategy for lead-induced bone toxicity.

Gut microbiota, plasma metabolites, and osteoporosis: unraveling links via Mendelian randomization

Objective

Osteoporosis, characterized by reduced bone density and heightened fracture risk, is influenced by genetic and environmental factors. This study investigates the interplay between gut microbiota, plasma metabolomics, and osteoporosis, identifying potential causal relationships mediated by plasma metabolites.

Methods

Utilizing aggregated genome-wide association studies (GWAS) data, a comprehensive two-sample Mendelian Randomization (MR) analysis was performed involving 196 gut microbiota taxa, 1,400 plasma metabolites, and osteoporosis indicators. Causal relationships between gut microbiota, plasma metabolites, and osteoporosis were explored.

Results

The MR analyses revealed ten gut microbiota taxa associated with osteoporosis, with five taxa positively linked to increased risk and five negatively associated. Additionally, 96 plasma metabolites exhibited potential causal relationships with osteoporosis, with 49 showing positive associations and 47 displaying negative associations. Mediation analyses identified six causal pathways connecting gut microbiota to osteoporosis through ten mediating relationships involving seven distinct plasma metabolites, two of which demonstrated suppression effects.

Conclusion

This study provides suggestive evidence of genetic correlations and causal links between gut microbiota, plasma metabolites, and osteoporosis. The findings underscore the complex, multifactorial nature of osteoporosis and suggest the potential of gut microbiota and plasma metabolite profiles as biomarkers or therapeutic targets in the management of osteoporosis.

Unraveling the Evolutionary Diet Mismatch and Its Contribution to the Deterioration of Body Composition

Over the millennia, patterns of food consumption have changed; however, foods were always whole foods. Ultra-processed foods (UPFs) have been a very recent development and have become the primary food source for many people. The purpose of this review is to propose the hypothesis that, forsaking the evolutionary dietary environment, and its complex milieu of compounds resulting in an extensive metabolome, contributes to chronic disease in modern humans. This evolutionary metabolome may have contributed to the success of early hominins. This hypothesis is based on the following assumptions: (1) whole foods promote health, (2) essential nutrients cannot explain all the benefits of whole foods, (3) UPFs are much lower in phytonutrients and other compounds compared to whole foods, and (4) evolutionary diets contributed to a more diverse metabolome. Evidence will be presented to support this hypothesis. Nutrition is a matter of systems biology, and investigating the evolutionary metabolome, as compared to the metabolome of modern humans, will help elucidate the hidden connections between diet and health. The effect of the diet on the metabolome may also help shape future dietary guidelines, and help define healthy foods.

Prediction of Osteoporotic Hip Fracture Outcome: Comparative Accuracy of 27 Immune-Inflammatory-Metabolic Markers and Related Conceptual Issues

Objectives: This study, based on the concept of immuno-inflammatory-metabolic (IIM) dysregulation, investigated and compared the prognostic impact of 27 indices at admission for prediction of postoperative myocardial injury (PMI) and/or hospital death in hip fracture (HF) patients. Methods: In consecutive HF patient (n = 1273, mean age 82.9 ± 8.7 years, 73.5% females) demographics, medical history, laboratory parameters, and outcomes were recorded prospectively. Multiple logistic regression and receiver-operating characteristic analyses (the area under the curve, AUC) were used to establish the predictive role for each biomarker. Results: Among 27 IIM biomarkers, 10 indices were significantly associated with development of PMI and 16 were indicative of a fatal outcome; in the subset of patients aged >80 years with ischaemic heart disease (IHD, the highest risk group: 90.2% of all deaths), the corresponding figures were 26 and 20. In the latter group, the five strongest preoperative predictors for PMI were anaemia (AUC 0.7879), monocyte/eosinophil ratio > 13.0 (AUC 0.7814), neutrophil/lymphocyte ratio > 7.5 (AUC 0.7784), eosinophil count < 1.1 × 109/L (AUC 0.7780), and neutrophil/albumin × 10 > 2.4 (AUC 0.7732); additionally, sensitivity was 83.1-75.4% and specificity was 82.1-75.0%. The highest predictors of in-hospital death were platelet/lymphocyte ratio > 280.0 (AUC 0.8390), lymphocyte/monocyte ratio < 1.1 (AUC 0.8375), albumin < 33 g/L (AUC 0.7889), red cell distribution width > 14.5% (AUC 0.7739), and anaemia (AUC 0.7604), sensitivity 88.2% and above, and specificity 85.1-79.3%. Internal validation confirmed the predictive value of the models. Conclusions: Comparison of 27 IIM indices in HF patients identified several simple, widely available, and inexpensive parameters highly predictive for PMI and/or in-hospital death. The applicability of IIM biomarkers to diagnose and predict risks for chronic diseases, including OP/OF, in the preclinical stages is discussed.

Microbiota and Resveratrol: How Are They Linked to Osteoporosis?

Osteoporosis (OP), which is characterized by a decrease in bone density and increased susceptibility to fractures, is closely linked to the gut microbiota (GM). It is increasingly realized that the GM plays a key role in the maintenance of the functioning of multiple organs, including bone, by producing bioactive metabolites such as short-chain fatty acids (SCFA). Consequently, imbalances in the GM, referred to as dysbiosis, have been identified with a significant reduction in beneficial metabolites, such as decreased SCFA associated with increased chronic inflammatory processes, including the activation of NF-κB at the epigenetic level, which is recognized as the main cause of many chronic diseases, including OP. Furthermore, regular or long-term medications such as antibiotics and many non-antibiotics such as proton pump inhibitors, chemotherapy, and NSAIDs, have been found to contribute to the development of dysbiosis, highlighting an urgent need for new treatment approaches. A promising preventive and adjuvant approach is to combat dysbiosis with natural polyphenols such as resveratrol, which have prebiotic functions and ensure an optimal microenvironment for beneficial GM. Resveratrol offers a range of benefits, including anti-inflammatory, anti-oxidant, analgesic, and prebiotic effects. In particular, the GM has been shown to convert resveratrol, into highly metabolically active molecules with even more potent beneficial properties, supporting a synergistic polyphenol-GM axis. This review addresses the question of how the GM can enhance the effects of resveratrol and how resveratrol, as an epigenetic modulator, can promote the growth and diversity of beneficial GM, thus providing important insights for the prevention and co-treatment of OP.

Effects of daily probiotic supplementation with Lactobacillus acidophilus on calcium status, bone metabolism biomarkers, and bone mineral density in postmenopausal women: a controlled and randomized clinical study

Background

Menopause poses significant health risks for women, particularly an increased vulnerability to fractures associated with osteoporosis. Dietary interventions have emerged as promising strategies, focusing on mitigating the risk of osteoporosis rather than solely addressing the established disease. This 12-week randomized controlled trial aimed to analyze the effects of consuming Lactobacillus acidophilus probiotics on calcium levels, biomarkers of bone metabolism, and bone mineral density (BMD) profiles in postmenopausal women.

Methods

Fifty-five participants were randomly assigned to receive either a placebo (n = 25) or the probiotic L. acidophilus UALa-01™ (n = 30) daily via oral intervention. Throughout the study, evaluations included body composition, blood biochemical parameters, serum calcium levels, and biomarkers of bone metabolism. Additionally, Dual-energy X-ray absorptiometry was used to measure BMD profiles.

Results

The findings delineated that the probiotic group experienced a decrease in serum calcium levels compared to their initial levels. However, hair calcium levels and biomarkers related to bone metabolism showed no notable changes within this group. Consumption of probiotic L. acidophilus also seemed to prevent fluctuations in bone turnover markers. Moreover, there were no significant alterations in BMD levels at the lumbar spine, left femur, and total body in the probiotic group. Additionally, probiotic intake led to favorable outcomes by significantly reducing both body fat and visceral fat during the intervention period. Conversely, an adverse effect of consuming probiotic L. acidophilus was observed with a significant increase in glucose concentration.

Conclusion

In conclusion, the consumption of L. acidophilus probiotics daily for 12 weeks among postmenopausal women does not affect the profile of BMD, but it may help in stabilizing bone turnover. It is important to note that most measured parameters were within the normal range for this population. However, it is worth noting that 3 months of probiotic supplementation could potentially disrupt calcium and glucose status in postmenopausal women.

Assessment of the relationship between gut microbiota and bone mineral density: a two-sample Mendelian randomization study

Background

Emerging evidence from observational studies and clinical trials suggests a connection between the gut microbiota and variations in bone mineral density (BMD). Nonetheless, the specific association between gut microbiota and BMD alterations at different skeletal sites has not been comprehensively explored. To address this, we employed Genome-Wide Association Study (GWAS) summary statistics from a publicly accessible database, conducting a two-sample Mendelian Randomization analysis to elucidate the potential causal relationship between gut microbiota composition and BMD.

Methods

This study utilized two distinct thresholds for screening instrumental variables (IVs), followed by an extensive series of quality control procedures to identify IVs that were significantly related to exposure. Gut microbiota were classified into two sets based on hierarchical levels: phylum, class, order, family, and genus. Bone mineral density (BMD) data were systematically collected from four skeletal sites: femoral neck, lumbar spine, forearm, and heel. For Mendelian Randomization (MR) analysis, robust methods including Inverse-Variance Weighting (IVW) and the Wald Ratio Test were employed. Additional analytical tests such as the Outlier Test, Heterogeneity Test, 'Leave-One-Out' Test, and Pleiotropy Test were conducted to assess the impact of horizontal pleiotropy, heterogeneities, and the genetic variation stability of gut microbiota on BMD causal associations. The MR Steiger Directionality Test was applied to exclude studies with potential directional biases.

Results

In this two-sample Mendelian randomization analysis, we utilized five sets of exposure GWAS (Genome-Wide Association Studies) summary statistics and four sets of outcome GWAS summary statistics. The initial analysis, applying a threshold of p < 5 × 10-6, identified 48 significant causal relationships between genetic liability in the gut microbiome and bone mineral density (BMD). A subsequent analysis with a more stringent threshold of p < 5 × 10-8 uncovered 14 additional causal relationships. Upon applying the Bonferroni correction, 9 results from the first analysis and 10 from the second remained statistically significant.

Conclusion

Our MR analysis revealed a causal relationship between gut microbiota and bone mineral density at all sites, which could lead to discoveries in future mechanistic and clinical studies of microbiota-associated osteoporosis.

Metabolic and inflammatory perturbation of diabetes associated gut dysbiosis in people living with and without HIV infection

BACKGROUND

Gut dysbiosis has been linked with both HIV infection and diabetes, but its interplay with metabolic and inflammatory responses in diabetes, particularly in the context of HIV infection, remains unclear.

METHODS

We first conducted a cross-sectional association analysis to characterize the gut microbial, circulating metabolite, and immune/inflammatory protein features associated with diabetes in up to 493 women (~ 146 with prevalent diabetes with 69.9% HIV +) of the Women's Interagency HIV Study. Prospective analyses were then conducted to determine associations of identified metabolites with incident diabetes over 12 years of follow-up in 694 participants (391 women from WIHS and 303 men from the Multicenter AIDS Cohort Study; 166 incident cases were recorded) with and without HIV infection. Mediation analyses were conducted to explore whether gut bacteria-diabetes associations are explained by altered metabolites and proteins.

RESULTS

Seven gut bacterial genera were identified to be associated with diabetes (FDR-q <  0.1), with positive associations for Shigella, Escherichia, Megasphaera, and Lactobacillus, and inverse associations for Adlercreutzia, Ruminococcus, and Intestinibacter. Importantly, the associations of most species, especially Adlercreutzia and Ruminococcus, were largely independent of antidiabetic medications use. Meanwhile, 18 proteins and 76 metabolites, including 3 microbially derived metabolites (trimethylamine N-oxide, phenylacetylglutamine (PAGln), imidazolepropionic acid (IMP)), 50 lipids (e.g., diradylglycerols (DGs) and triradylglycerols (TGs)) and 23 non-lipid metabolites, were associated with diabetes (FDR-q <  0.1), with the majority showing positive associations and more than half of them (59/76) associated with incident diabetes. In mediation analyses, several proteins, especially interleukin-18 receptor 1 and osteoprotegerin, IMP and PAGln partially mediate the observed bacterial genera-diabetes associations, particularly for those of Adlercreutzia and Escherichia. Many diabetes-associated metabolites and proteins were altered in HIV, but no effect modification on their associations with diabetes was observed by HIV.

CONCLUSION

Among individuals with and without HIV, multiple gut bacterial genera, blood metabolites, and proinflammatory proteins were associated with diabetes. The observed mediated effects by metabolites and proteins in genera-diabetes associations highlighted the potential involvement of inflammatory and metabolic perturbations in the link between gut dysbiosis and diabetes in the context of HIV infection.

A review of "plant gold" Eucommia ulmoides Oliv.: A medicinal and food homologous plant with economic value and prospect

Eucommia ulmoides Oliv. is an ancient and precious plant that has been used as medicine in China for more than 2000 years. Because its bark, leaves, seeds, and male flowers can be used in medicine, it plays an important role in medicine, food, chemical industry, and other fields, so it is also called "plant gold". 246 compounds have been isolated from E. ulmoides, which endow E. ulmoides with many unique pharmacological effects and make it wide to study in the fields of osteoporosis, hypertension, liver protection, and so on. Besides, E. ulmoides also has significant medicinal effects on anti-inflammatory, antioxidant, immunomodulation, and neuroprotection, and is often used in clinical compound medicines of traditional Chinese medicine. In addition to updating its ethnobotany, phytochemistry, pharmacology, and toxicology information, the economic botany of leaves, seeds, and male flowers was also introduced. It hopes hoping to fully understand this economically important Chinese medicine and provide a scientific basis for further development and utilization of E. ulmoides.

Diets intervene osteoporosis via gut-bone axis

Osteoporosis is a systemic skeletal disease that seriously endangers the health of middle-aged and older adults. Recently, with the continuous deepening of research, an increasing number of studies have revealed gut microbiota as a potential target for osteoporosis, and the research concept of the gut-bone axis has gradually emerged. Additionally, the intake of dietary nutrients and the adoption of dietary patterns may affect the gut microbiota, and alterations in the gut microbiota might also influence the metabolic status of the host, thus adjusting bone metabolism. Based on the gut-bone axis, dietary intake can also participate in the modulation of bone metabolism by altering abundance, diversity, and composition of gut microbiota. Herein, combined with emerging literatures and relevant studies, this review is aimed to summarize the impacts of different dietary components and patterns on osteoporosis by acting on gut microbiota, as well as underlying mechanisms and proper dietary recommendations.

Microbiome's role in musculoskeletal health through the gut-bone axis insights

The interplay between the human microbiome and the musculoskeletal system represents a burgeoning field of research with profound implications for understanding and treating musculoskeletal disorders. This review articulates the pivotal role of the microbiome in modulating bone health, highlighting the gut-bone axis as a critical nexus for potential therapeutic intervention. Through a meticulous analysis of recent clinical research, we underscore the microbiome's influence on osteoporosis, sarcopenia, osteoarthritis, and rheumatoid arthritis, delineating both the direct and indirect mechanisms by which microbiota could impact musculoskeletal integrity and function. Our investigation reveals novel insights into the microbiota's contribution to bone density regulation, hormone production, immune modulation, and nutrient absorption, laying the groundwork for innovative microbiome-based strategies in musculoskeletal disease management. Significantly, we identify the challenges hindering the translation of research into clinical practice, including the limitations of current microbial sequencing techniques and the need for standardized methodologies in microbiome studies. Furthermore, we highlight promising directions for future research, particularly in the realm of personalized medicine, where the microbiome's variability offers unique opportunities for tailored treatment approaches. This review sets a new agenda for leveraging gut microbiota in the diagnosis, prevention, and treatment of musculoskeletal conditions, marking a pivotal step toward integrating microbiome science into clinical musculoskeletal care.

Regulatory mechanisms of autophagy-related ncRNAs in bone metabolic diseases

Bone metabolic diseases have been tormented and are plaguing people worldwide due to the lack of effective and thorough medical interventions and the poor understanding of their pathogenesis. Non-coding RNAs (ncRNAs) are heterogeneous transcripts that cannot encode the proteins but can affect the expressions of other genes. Autophagy is a fundamental mechanism for keeping cell viability, recycling cellular contents through the lysosomal pathway, and maintaining the homeostasis of the intracellular environment. There is growing evidence that ncRNAs, autophagy, and crosstalk between ncRNAs and autophagy play complex roles in progression of metabolic bone disease. This review investigated the complex mechanisms by which ncRNAs, mainly micro RNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), regulate autophagic pathway to assist in treating bone metabolism disorders. It aimed at identifying the autophagy role in bone metabolism disorders and understanding the role, potential, and challenges of crosstalk between ncRNAs and autophagy for bone metabolism disorders treatment.

Potential application of Atractylodes macrocephala Koidz. as a natural drug for bone mass regulation: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Atractylodes macrocephala Koidz. (AM) has been used for thousands of years in China, and it's extracts contain various constituents, such as volatile oils, polysaccharides, and lactones, with a myriad of pharmacological effects, including improves the healthy state of the gastrointestinal system and regulating immunity, hormone secretion, anti-inflammatory, antibacterial, antioxidation, anti-aging, and antitumor properties. Recently, researchers have focused on the effect of AM in regulating bone mass; therefore, its potential mechanism of action in regulating bone mass needs to be elucidated.

AIM OF REVIEW

This study reviewed the known and possible mechanisms of bone mass regulation by AM.

MATERIALS AND METHODS

Cochrane, Medline via PubMed, Embase, CENTRAL, CINAHL, Web of Science, Chinese biomedical literature database, Chinese Science and Technology Periodical Database, and Wanfang Database were used to search AM root extracts-related studies. The retrieval date was from the establishment of the database to January 1, 2023.

RESULTS

By summarizing 119 natural active substances that have been isolated from AM root to date, we explored its possible targets and pathways (such as Hedgehog, Wnt/β-catenin, and BMP/Smads pathways etc.) for bone growth and presented our position on possible future research/perspectives in the regulation of bone mass using this plant.

CONCLUSIONS

AM root extracts (incuding aqueous, ethanol etc.) promotes osteogenesis and inhibits osteoclastogenesis. These functions promote the absorption of nutrients, regulate gastrointestinal motility and intestinal microbial ecology, regulate endocrine function, strengthen bone immunity, and exert anti-inflammatory and antioxidant effects.

The synergistic effects of polyphenols and intestinal microbiota on osteoporosis

Osteoporosis is a common metabolic disease in middle-aged and elderly people. It is characterized by a reduction in bone mass, compromised bone microstructure, heightened bone fragility, and an increased susceptibility to fractures. The dynamic imbalance between osteoblast and osteoclast populations is a decisive factor in the occurrence of osteoporosis. With the increase in the elderly population in society, the incidence of osteoporosis, disability, and mortality have gradually increased. Polyphenols are a fascinating class of compounds that are found in both food and medicine and exhibit a variety of biological activities with significant health benefits. As a component of food, polyphenols not only provide color, flavor, and aroma but also act as potent antioxidants, protecting our cells from oxidative stress and reducing the risk of chronic disease. Moreover, these natural compounds exhibit anti-inflammatory properties, which aid in immune response regulation and potentially alleviate symptoms of diverse ailments. The gut microbiota can degrade polyphenols into more absorbable metabolites, thereby increasing their bioavailability. Polyphenols can also shape the gut microbiota and increase its abundance. Therefore, studying the synergistic effect between gut microbiota and polyphenols may help in the treatment and prevention of osteoporosis. By delving into how gut microbiota can enhance the bioavailability of polyphenols and how polyphenols can shape the gut microbiota and increase its abundance, this review offers valuable information and references for the treatment and prevention of osteoporosis.

Meta-Analysis Reveals Compositional and Functional Microbial Changes Associated with Osteoporosis

Over the past decade, the role of the gut microbiota in many disease states has gained a great deal of attention. Mounting evidence from case-control and observational studies has linked changes in the gut microbiota to the pathophysiology of osteoporosis (OP). Nonetheless, the results of these studies contain discrepancies, leaving the literature without a consensus on osteoporosis-associated microbial signatures. Here, we conducted a comprehensive meta-analysis combining and reexamining five publicly available 16S rRNA partial sequence data sets to identify gut bacteria consistently associated with osteoporosis across different cohorts. After adjusting for the batch effect associated with technical variation and heterogeneity of studies, we observed a significant shift in the microbiota composition in the osteoporosis group. An increase in the relative abundance of opportunistic pathogens Clostridium sensu stricto, Bacteroides, and Intestinibacter was observed in the OP group. Moreover, short-chain-fatty-acid (SCFA) producers, including members of the genera Collinsella, Megasphaera, Agathobaculum, Mediterraneibacter, Clostridium XIV, and Dorea, were depleted in the OP group relative to the healthy control (HC) group. Lactic acid-producing bacteria, including Limosilactobacillus, were significantly increased in the OP group. The random forest algorithm further confirmed that these bacteria differentiate the two groups. Furthermore, functional prediction revealed depletion of the SCFA biosynthesis pathway (glycolysis, tricarboxylic acid [TCA] cycle, and Wood-Ljungdahl pathway) and amino acid biosynthesis pathway (methionine, histidine, and arginine) in the OP group relative to the HC group. This study uncovered OP-associated compositional and functional microbial alterations, providing robust insight into OP pathogenesis and aiding the possible development of a therapeutic intervention to manage the disease. IMPORTANCE Osteoporosis is the most common metabolic bone disease associated with aging. Mounting evidence has linked changes in the gut microbiota to the pathophysiology of osteoporosis. However, which microbes are associated with dysbiosis and their impact on bone density and inflammation remain largely unknown due to inconsistent results in the literature. Here, we present a meta-analysis with a standard workflow, robust statistical approaches, and machine learning algorithms to identify notable microbial compositional changes influencing osteoporosis.

Identifying microbial signatures for patients with postmenopausal osteoporosis using gut microbiota analyses and feature selection approaches

Osteoporosis (OP) is a metabolic bone disorder characterized by low bone mass and deterioration of micro-architectural bone tissue. The most common type of OP is postmenopausal osteoporosis (PMOP), with fragility fractures becoming a global burden for women. Recently, the gut microbiota has been connected to bone metabolism. The aim of this study was to characterize the gut microbiota signatures in PMOP patients and controls. Fecal samples from 21 PMOP patients and 37 controls were collected and analyzed using amplicon sequencing of the V3-V4 regions of the 16S rRNA gene. The bone mineral density (BMD) measurement and laboratory biochemical test were performed on all participants. Two feature selection algorithms, maximal information coefficient (MIC) and XGBoost, were employed to identify the PMOP-related microbial features. Results showed that the composition of gut microbiota changed in PMOP patients, and microbial abundances were more correlated with total hip BMD/T-score than lumbar spine BMD/T-score. Using the MIC and XGBoost methods, we identified a set of PMOP-related microbes; a logistic regression model revealed that two microbial markers (Fusobacteria and Lactobacillaceae) had significant abilities in disease classification between the PMOP and control groups. Taken together, the findings of this study provide new insights into the etiology of OP/PMOP, as well as modulating gut microbiota as a therapeutic target in the diseases. We also highlight the application of feature selection approaches in biological data mining and data analysis, which may improve the research in medical and life sciences.

Application of metabolomics in osteoporosis research

Osteoporosis (OP) is a systemic disease characterized by bone metabolism imbalance and bone microstructure destruction, which causes serious social and economic burden. At present, the diagnosis and treatment of OP mainly rely on imaging combined with drugs. However, the existing pathogenic mechanisms, diagnosis and treatment strategies for OP are not clear and effective enough, and the disease progression that cannot reflect OP further restricts its effective treatment. The application of metabolomics has facilitated the study of OP, further exploring the mechanism and behavior of bone cells, prevention, and treatment of the disease from various metabolic perspectives, finally realizing the possibility of a holistic approach. In this review, we focus on the application of metabolomics in OP research, especially the newer systematic application of metabolomics and treatment with herbal medicine and their extracts. In addition, the prospects of clinical transformation in related fields are also discussed. The aim of this study is to highlight the use of metabolomics in OP research, especially in exploring the pathogenesis of OP and the therapeutic mechanisms of natural herbal medicine, for the benefit of interdisciplinary researchers including clinicians, biologists, and materials engineers.