Short-chain fatty acids regulate systemic bone mass and protect from pathological bone loss

Gut dysbiosis was inevitable, but tolerance was not: temporal responses of the murine microbiota that maintain its capacity for butyrate production correlate with sustained antinociception to chronic morphine

The therapeutic benefits of opioids are compromised by the development of analgesic tolerance, which necessitates higher dosing for pain management thereby increasing the liability for drug dependence and addiction. Rodent models indicate opposing roles of the gut microbiota in tolerance: morphine-induced gut dysbiosis exacerbates tolerance, whereas probiotics ameliorate tolerance. Not all individuals develop tolerance, which could be influenced by differences in microbiota, and yet no study design has capitalized upon this natural variation. We leveraged natural behavioral variation in a murine model of voluntary oral morphine self-administration to elucidate the mechanisms by which microbiota influences tolerance. Although all mice shared similar morphine-driven microbiota changes that largely masked informative associations with variability in tolerance, our high-resolution temporal analyses revealed a divergence in the progression of dysbiosis that best explained sustained antinociception. Mice that did not develop tolerance maintained a higher capacity for production of the short-chain fatty acid (SCFA) butyrate known to bolster intestinal barriers and promote neuronal homeostasis. Both fecal microbial transplantation (FMT) from donor mice that did not develop tolerance and dietary butyrate supplementation significantly reduced the development of tolerance independently of suppression of systemic inflammation. These findings could inform immediate therapies to extend the analgesic efficacy of opioids.

Bacillus coagulans ameliorates inflammatory bone loss in post-menopausal osteoporosis via modulating the "Gut-Immune-Bone" axis

Osteoporosis is a systemic skeletal disease that leads to lower bone mineral density and intensifies the risk of unexpected fractures. Recently, our group reported that numerical defect in the frequencies of Bregs along with their compromised tendency to produce IL-10 cytokine further aggravates inflammatory bone loss in post-menopausal osteoporosis (PMO). Dysbiosis induced mucosal injury and leaky gut are the predominant contributors involved in the progression of inflammatory diseases including PMO. Furthermore, several evidence suggest that gut microbial composition plays a crucial role in the development and differentiation of Bregs. Nevertheless, the potential role of dysbiotic gut microbiota (GM) and Bregs under estrogen deficient PMO conditions has never been deciphered. Here, we evaluated the role of GM in the onset and progression of PMO along with its role in modulating the anti-osteoporotic potential of Bregs. We found that enhancement in the endotoxin producing bacteria and concomitant reduction in the short chain fatty acids producing bacteria, both under pre-clinical and clinical osteoporotic condition augment inflammatory bone loss. This suggests that dysbiosis of GM potentially exacerbates bone deterioration under estrogen deficient PMO conditions. Remarkably, supplementation of probiotic Bacillus coagulans significantly improved the bone mineral density, bone strength, and bone microarchitecture by modulating the anti-osteoclastogenic, immunosuppressive and immunomodulatory potential of Bregs. The present study delves deeper into the role of immune homeostasis ("Breg-Treg-Th17" cell axis) and GM profile in the pathophysiology of PMO. Altogether, findings of the present study open novel therapeutic avenues, suggesting restoration of GM composition as one of the viable therapeutic options in mitigating inflammatory bone loss under PMO conditions via modulating the "Gut-Immune-Bone" axis.

Gut microbiota and microbial metabolites for osteoporosis

Osteoporosis is an age-related bone metabolic disease. As an essential endocrine organ, the skeletal system is intricately connected with extraosseous organs. The crosstalk between bones and other organs supports this view. In recent years, the link between the gut microecology and bone metabolism has become an important research topic, both in preclinical studies and in clinical trials. Many studies have shown that skeletal changes are accompanied by changes in the composition and structure of the gut microbiota (GM). At the same time, natural or artificial interventions targeting the GM can subsequently affect bone metabolism. Moreover, microbiome-related metabolites may have important effects on bone metabolism. We aim to review the relationships among the GM, microbial metabolites, and bone metabolism and to summarize the potential mechanisms involved and the theory of the gut‒bone axis. We also describe existing bottlenecks in laboratory studies, as well as existing challenges in clinical settings, and propose possible future research directions.

Interaction of environmental fluoride exposure and gut microbes: Potential implication in the development of fluorosis in human subjects

Fluoride exposure primarily occurs through contaminated water and leads to fluorosis, which is a global health concern. After ingestion, fluoride is absorbed via gastrointestinal tract, where it interacts with the gut microbiota. While animal studies have explored fluoride's effects on gut microbiota, no human studies have yet been conducted. Most research emphasizes metagenomic diversity, neglecting isolation and characterization of pure cultures for further applications. Additionally, the association between gut microbiota with fluorosis outcomes in fluoride-exposed populations is unexplored. This study characterizes and compares the cultivable gut microbiota in the fluoride-exposed population with (symptomatic, group II) or without (asymptomatic, group I) signs of skeletal fluorosis along with unexposed control (group III). Group I displayed higher abundance of Firmicutes (58.58 %), group II had predominance of Proteobacteria (61.25 %) while group III showed similar abundance of Proteobacteria (50.38 %) and Firmicutes (49.51 %). On analyzing short-chain fatty acid (SCFA) profiles, group I isolates produced higher isobutyric acid (1.31 ± 0.9 mM) than group II (0.71 ± 0.35 mM), while group II produced more isovaleric acid (0.8 ± 0.41 mM) than group I (0.61 ± 0.08 mM) (p < 0.05). These findings suggest that gut microbiota and SCFAs alteration may influence bone metabolism, affecting the fluorosis progression.

The impact of mechanical unloading on the gut microbiota and the mitigating role of butyrate in bone loss

Bone loss induced by mechanical unloading is a critical concern in aerospace medicine and for patients subjected to prolonged bed rest. In this study, we investigated the effects of mechanical unloading on the gut microbiota and short-chain fatty acid (SCFA) metabolism, as well as the potential role of butyrate in mitigating bone loss. Through a combination of a hindlimb unloading model, microbiological assessments, and metabolic profiling, we demonstrated that mechanical unloading significantly reduced gut microbiota diversity, altered the Firmicutes-to-Bacteroidetes ratio, and decreased total SCFA levels. Furthermore, butyrate supplementation mitigated the adverse effects of mechanical unloading on the bone microstructure by increasing ELK1 protein expression through HDAC2 inhibition, thus promoting osteoblast differentiation and bone formation. These findings highlight the intricate relationships among gut microbiota alterations, SCFA metabolism, and bone health during mechanical unloading, suggesting that butyrate may be a potential therapeutic agent to counteract bone loss in microgravity environments.

Immune Cells as Mediators of Lipidome Influence on Osteoporosis: Evidence from a Mediation Analysis

Background: Although clinical studies have indicated a possible association between dyslipidemia and osteoporosis, the underlying genetic basis and mechanistic pathways remain insufficiently defined. Most prior research has concentrated on conventional lipid markers, which are prone to confounding and limit causal inference. Exploring lipidomic profiles offers a more comprehensive view of lipid metabolism and may reveal novel genetic links beyond traditional lipid traits. Additionally, alterations in immune cell function, often triggered by metabolic disturbances, may contribute to osteoporosis development; however, the potential mediating role of immune cells in the lipid-bone axis has not been systematically investigated. Methods: A total of 179 lipid species across 13 lipid classes were analyzed in 7174 Finnish individuals from the GeneRISK cohort. Genome-Wide Association Study (GWAS) summary statistics for osteoporosis and 731 immune cell immunophenotypes were sourced from the GWAS Catalog. A two-step, two-sample Mendelian randomization analysis, using inverse variance weighting (IVW), was conducted to explore the potential causal effects of lipids on osteoporosis and the mediating role of immune cells in the relationship between lipids and osteoporosis. Results: Mendelian randomization analysis indicated that triacylglycerol levels of 48:0 were possibly associated with an increased risk of osteoporosis (IVW: odds ratio [OR] 1.1320, 95% CI 1.0401-1.2321; p = 0.004), while triacylglycerol levels of 48:3 appeared to be associated with a reduced risk of osteoporosis (IVW: OR 0.9053, 95% CI 0.8364-0.9800; p = 0.014). Two statistically significant mediating effects were identified: First, IgD- CD38dim %B cells appeared to partially negatively mediate the association between triacylglycerol levels of 48:3 and osteoporosis, with a negative mediating effect of -0.00669 (95% CI: -0.0214, 0.00805), which accounted for 6.73% of the total effect. That is, the protective effect of triacylglycerol levels of 48:3 against osteoporosis was attenuated by IgD- CD38dim %B cells. Second, HLA DR++ monocytes% leukocytes also partially negatively mediated this relationship, with a mediating effect of -0.023 (95% CI: -0.0434, -0.00266), accounting for 23.2% of the total effect. This indicates that other immune cells, HLA DR++ monocytes %leukocytes, resisted the protective effect of triacylglycerol levels of 48:3 against osteoporosis, with a weakening effect stronger than that of IgD- CD38dim %B cells. Conclusions: Our findings contribute to the growing understanding of the potential causal relationships and shared pathogenic mechanisms between dyslipidemia and osteoporosis. The results suggest that the potential genetic effects of plasma lipid metabolites on osteoporosis may be partially down-regulated by specific kinds of immune cells.

Intake of Neutral core Human Milk Oligosaccharides (HMOs) during early life improves long-term bone quality

Infancy is a key period for bone growth, determining bone strength later in life. Studies have provided early insights into the role that human milk oligosaccharides (HMOs) may play in growth, potentially through their effects on the microbiome. However, focus was on sialylated HMOs whereas neutral core HMOs represent the most abundant class in human breast milk. We explored impact on bone quantity, quality and strength in 1year old female minipigs exposed to neutral HMOs during preweaning. Milk formula led to significant lower bone mineral density and quality compared to sow-fed (positive control). Milk formula enriched in neutral HMOs led to higher tibia bone density, structure and matrix quality compared to milk formula, leading to similar bone strength as in naturally sow-fed, whereas sialylated HMOs was not able to significantly differentiate than milk formulae. We identify a specific correlation between neutral HMOs, bone and microbiome, with the novel taxonomies Turicibacter sanguinis and Paraprevotella clara associating with HMO-mediated bone strength. This study provides important insights on the role of different HMO subtypes on bone health and possible associated adaptations in microbiome taxa, providing perspectives for new nutritional solutions for bone growth in early life.

Progress of research on the gut microbiome and its metabolite short-chain fatty acids in postmenopausal osteoporosis: a literature review

Postmenopausal osteoporosis (PMOP) is a systemic metabolic bone disease caused by the decrease in estrogen levels after menopause. It leads to bone loss, microstructural damage, and an increased risk of fractures. Studies have found that the gut microbiota and its metabolites can regulate bone metabolism through the gut-bone axis and the gut-brain axis. As research progresses, PMOP has been found to be associated with gut microbiota dysbiosis and Th17/Treg imbalance. The gut microbiota is closely related to the development and differentiation of Treg and Th17 cells. Among them, the metabolites of the gut microbiota such as short-chain fatty acids (SCFAs) can regulate the differentiation of effector T cells by acting on molecular receptors on immune cells, thereby regulating the bone immune process. The multifaceted relationship among the gut microbiota, SCFAs, Th17/Treg cell-mediated bone immunity, and bone metabolism is eliciting attention from researchers. Through a review of existing literature, we have comprehensively summarized the effects of the gut microbiota and SCFAs on PMOP, especially from the perspective of Th17/Treg balance. Regulating this balance may provide new opportunities for PMOP treatment.

Research trends and hotspots of osteoporosis and intestinal microbiota: A bibliometric analysis

BACKGROUND

Osteoporosis (OP) is the second most detrimental chronic disease, and thus novel diagnostic and therapeutic approaches are needed. In recent years, there has been an increased emphasis on the utilization of gut microbiota (GM) in the context of OP. However, a comprehensive bibliometric analysis on this subject is currently lacking. Furthermore, a deeper exploration of the role of GM in bone health is imperative, and there is a pressing need to foster international and inter-agency exchange and experience in this field. Accordingly, this study aimed to provide an overview of the research trends in this field and propose suggestions for related scientific and technological research and development.

METHODS

The Web of Science database was searched for articles related to both GM and OP. Statistical analyses and data visualization were performed using the EXCEL and CiteSpace software.

RESULTS

China exhibited the highest number of publications, followed by the United States. NUTRIENTS and Sichuan University were identified as the journal and institution, respectively, with the highest number of articles. Notably, the keywords "gut microbiota" and "bone loss" have been increasingly used in publications.

CONCLUSION

In conclusion, this study fills the existing gap in the literature and contributes valuable insights to the understanding of the relationship between GM and OP.

Non-starch polysaccharides and health: gut-target organ axis influencing obesity

Obesity is recognized as a global epidemic that can result in changes in the human body and metabolism. Accumulating evidence indicates that gut microbiota (GM) can affect the development of obesity. The GM not only plays a crucial role in digesting and absorbing nutrients, but also in maintaining the overall health of the host. Dietary supplements such as non-starch polysaccharides are mainly fermented by the GM in the colon. Recent findings suggest that shaping the GM through the prebiotic function of non-starch polysaccharides may be a viable strategy against obesity. In this paper, the effects of non-starch polysaccharides on host health, together with their prebiotic function influencing the GM to control obesity via the gut-target organ axis, are reviewed. Potential perspectives of non-starch polysaccharides exhibiting anti-obesity effects via the gut-target organ axis are proposed for future research.

Graphical abstract

Effects of high-dose glucocorticoids on gut microbiota in the treatment of Graves' ophthalmopathy

Many studies indicate the gut microbiome is associated with diseases caused by administering high-dose glucocorticoids (GCs), such as hypertension, hyperglycemia, and osteoporosis. However, the association between intestinal flora and the use of high-dose GCs remains elusive. We aimed to characterize gut microbiome in Graves' ophthalmopathy (GO) patients after administering high-dose GCs. In this study, 20 primary GO patients were recruited. The differences in gut microbiota of GO patients before and after administering high-dose GCs were analyzed by 16S rDNA sequencing technology. Untargeted metabolomic analysis was used to examine the differences in gut metabolites between two groups. There were significant differences in α and β diversities of gut microbiota in GO patients before and after administering high-dose GCs. The random forest analysis indicated that three intestinal bacteria (Faecalibacterium, Streptococcus, and Prevotella) could distinguish the two groups with the highest accuracy, which was proven by receiver operator characteristic curve and linear discriminant analysis effect size analysis. The short-chain fatty acid-producing ability in GO patients' gut after high-dose GC administration was significantly decreased. The 5-hydroxytryptamine levels significantly increased in the gut of GO patients after administering high-dose GCs. Our study suggests that high-dose GC administration causes the changes in gut microbiome and metabolites. Moreover, the altered flora and metabolites are related to hypertension, hyperglycemia, and osteoporosis. These findings can help understand the development of side effects caused by high-dose GCs and can be further used to develop potential probiotics to facilitate the prevention for those side effects.IMPORTANCEFor the first time, we revealed that gut microbiome and metabolome in Graves' ophthalmopathy patients after high-dose glucocorticoid (GC) administration significantly changed, and the altered flora and metabolites are related to hypertension, hyperglycemia, and osteoporosis. These findings can help understand the development of side effects caused by high-dose GCs and can be further used to develop potential probiotics to facilitate the prevention for those side effects.

Linking microbial communities to rheumatoid arthritis: focus on gut, oral microbiome and their extracellular vesicles

Rheumatoid arthritis (RA) is a severe, chronic autoimmune disease affecting approximately 1% of the global population. Research has demonstrated that microorganisms play a crucial role in the onset and progression of RA. This indicates that the disruption of immune homeostasis may originate from mucosal sites, such as the gut and oral cavity. In the intestines of patients in the preclinical stage of RA, an increased abundance of Prevotella species with a strong association to the disease was observed. In the oral cavity, infections by Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans can mediate the production of anti-citrullinated protein antibodies (ACPAs), potentially contributing to RA pathogenesis. Nevertheless, no single bacterial species has been consistently identified as the primary driver of RA. This review will discuss the connection between gut and oral bacteria in the development of arthritis. Additionally, it explores the role of bacterial extracellular vesicles (bEVs) in inducing inflammation and their potential pathogenic roles in RA.

Modulation of the gut-bone axis: Lacticaseibacillus paracasei LC86 improves bone health via anti-inflammatory metabolic pathways in zebrafish models of osteoporosis and cartilage damage

Aim

Osteoporosis and cartilage injury are major health concerns with limited treatment options. This study investigates the therapeutic effects of Lacticaseibacillus paracasei LC86 (LC86) on osteoporosis and cartilage damage in a zebrafish (Danio rerio) model, focusing on its modulation of the gut-bone axis and its potential mechanisms for enhancing bone health.

Methods

A Dexamethasone-induced zebrafish model was used to mimic osteoporosis and cartilage injury. Zebrafish were divided into control, model, and LC86 treatment groups (3×107 CFU/mL). Bone and cartilage health were assessed using Alizarin red staining and fluorescence microscopy. Bone marker expression (sp7, runx2a, bmp2a, bmp4, and col2a1a) was quantified via qPCR. Metabolic alterations were analyzed using untargeted metabolomics, and changes in gut microbiota were examined through 16S rRNA gene sequencing.

Results

LC86 treatment significantly improved bone and cartilage health, as evidenced by increased fluorescence intensity in the skull, hard bone, and cartilage (p < 0.01, p < 0.05). qPCR results showed upregulation of key bone-related genes (sp7, runx2a, bmp2a, bmp4, and col2a1a), indicating enhanced bone and cartilage structure. Metabolomics analysis revealed alterations in over 300 metabolites, with changes in anti-inflammatory and energy pathways. Gut microbiota analysis demonstrated an increase in beneficial bacteria and a decrease in pathogenic genera.

Conclusions

LC86 significantly improved bone health, cartilage structure, and gut microbiota composition in a Dexamethasone-induced zebrafish model, supporting its potential as a therapeutic strategy for osteoporosis and cartilage injury via modulation of the gut-bone axis.

Curcumin Ameliorated Glucocorticoid-Induced Osteoporosis While Modulating the Gut Microbiota and Serum Metabolome

Glucocorticoid-induced osteoporosis (GIOP) is the leading cause of secondary osteoporosis. Recently, the "bone-gut axis" theory has linked bone development with gut microbial diversity, community composition, and metabolites. Curcumin, a well-studied polyphenol, shows potential in mitigating bone loss and osteoporosis. Alendronate, a standard therapeutic agent for osteoporosis, serves as a positive control in this investigation. The study demonstrates the potency of curcumin in reducing bone loss and restoring bone mineral density, enhancing trabecular parameters notably through increased trabecular number, volume, and thickness and reduced bone marrow cavity size. Gut microbiome sequencing revealed that both curcumin and alendronate treatments similarly enhanced gut microbial diversity and altered microbiota composition, increasing beneficial bacteria (Akkermansia_muciniphila, Dubosiella_sp910585105, and Ruminococcus_sp910584195) while reducing harmful bacteria (Treponema_D_sp910584475 and Duncaniella_sp910584825). Furthermore, significant changes in serum levels of metabolites including raffinose, ursolic acid, spermidine, inosine, hypoxanthine, thiamine, and pantothenic acid were observed post-treatment with curcumin or alendronate. Importantly, these beneficial metabolites and microorganisms were negatively correlated with inflammatory cytokines. In conclusion, curcumin holds promise for use against GIOP by modulating the gut microbiome and serum metabolome as well as reducing systemic inflammation.

Engineered Pseudomonas mirabilis-Derived Outer Membrane Vesicles Targeting Bone Microenvironment to Improve Osteoporosis

Introduction: Osteoporosis (OP) is a prevalent condition marked by reduced bone density and a heightened risk of fractures. Current treatments often have side effects, underscoring the need for safer alternatives. Recent research highlights the significant role of gut microbiota and their metabolites in maintaining bone health. Notably, bacterial outer membrane vesicles (OMVs) have emerged as a promising platform due to their nanoscale sizes, low toxicity, drug-loading capabilities, and excellent biocompatibility. Methods: In this study, we developed a delivery system using OMVs derived from Pseudomonas mirabilis (PM). By anchoring bone-targeting peptides to the PM-OMVs membrane, we equipped these vesicles to deliver endogenous miRNAs to the bone microenvironment effectively. Results and Discussion: The bone-targeted PM-OMVs (PM-OMVs-BT) demonstrated exceptional bone-targeting abilities and exhibited a favorable safety profile in vivo. Additionally, LGG-OMVs-BT were successfully internalized by bone marrow stromal cells (BMSCs) without significant cytotoxicity, effectively promoting their osteogenic differentiation and mineralization. In conclusion, our study indicates that PM-OMVs-BT could offer a safe and effective treatment option for OP.

Zinc Glycine supplementation improves bone quality in meat geese by modulating gut microbiota, SCFA's, and gut barrier function through Wnt10b/NF-κB axis

Bone disorders are characterized by leg abnormalities and alterations in gut microbiota, which are linked with destruction of bone structure and increased risk of fractures. Zinc (Zn) plays a crucial role in normal bone homeostasis and has been proven to be highly effective against leg problems. The effects of different Zn sources on bone quality were evaluated in this study. A total of 300 one-d-old Wanpu mixed-sexed geese fed 2 basal diets added with best suited levels of 80 mg/kg inorganic zinc (ZnSO4), and 80 mg/kg Organic zinc (Zn-Glycine) for 60 d. Tibia bone mineral density (BMD), ash percentage, and tibia length increased with dietary Zn source (P < 0.05). Micro-computed tomography analysis revealed that Zn-Glycine improved bone mass, potentially due to an increased abundance of Firmicutes and higher SCFA production in the cecum. Dietary Zn Glycine addition reduced intestinal permeability, upregulated the protein expression of tight junction protein (Zonula Occludens-1, Claudin-1), downregulated diamine oxidase (DAO) levels, and increased the abundance of Lactobacillus and Bifidobacterium, which was accompanied by a reduction in inflammatory cytokines levels in the serum, tibia, and cecum. In terms of bone turnover, Zn-Glycine increased alkaline phosphatase (ALP) and other bone markers (Runt-related transcription factor 2- Runx2, Osteoprotegerin- OPG, Osteocalcin- OCN, Suppressor of mother against decapentaplegic- SMAD) expression, resulting in a decrease in osteoclast number and a reduction in serum bone resorption biomarkers, including serum tartrate-resistant acid phosphatase activity and tibia nuclear factor of activated T-cells (NFATC1) and tumor necrosis factor receptor associated factor 6 (TRAF-6) (P < 0.05). Zn-Glycine also enhanced antioxidant capacity by increasing catalase (CAT) and glutathione peroxidase (GSH-PX), resulting in reduced reactive oxygen species (ROS) and malondialdehyde (MDA) production (P<0.05). Zn-Glycine at 80mg/kg in the diet actively reduced (P<0.05) the expression of cell-death-associated proteins (Beclin-1, Caspase-3). Additionally, Zn-Glycine improved intestinal morphology (villus height, villus-to-crypt ratio), supporting efficient nutrient absorption. Immunofluorescence analysis of tibia showed higher expression of wingless type-10b (Wnt-10b) and reduced expression of nuclear factor-kappa B (NF-κB) in Zn-Glycine group compared to ZnSO4 group. These findings underscore the significance of the gut-bone axis and provide new insights into the effect of Zn-Glycine on bone health in meat geese through a key signaling pathway.

Regulation of osteoclast-mediated bone resorption by lipids

Hyperactivation of osteoclasts has been identified as a significant etiological factor in several bone resorption-related disorders, including osteoporosis, periodontitis, arthritis, and bone metastasis of tumors. It has been demonstrated that the severity of these diseases is influenced by lipids that regulate osteoclast differentiation and activity through specific signaling pathways and cytokine levels. The regulatory mechanisms of different types of lipids on osteoclastogenesis vary across diverse disease contexts in bone resorption regulated by osteoclasts. This review presents an overview of the mechanisms underlying osteoclast formation and summarizes the pathways through which various lipids regulate osteoclastogenesis in different pathological contexts. We also discuss effective therapeutic strategies for osteolytic diseases based on modulation of lipid metabolism.

Gut-X Axis and Its Role in Poultry Bone Health: A Review

The normal development and growth of bones are critical for poultry health. With the rapid increase in poultry growth rates achieved over the last few decades, juvenile meat-type poultry exhibit a high incidence of leg weakness and lameness. These issues are significant contributors to poor animal welfare and substantial economic losses. Understanding the potential etiology of bone problems in poultry will aid in developing treatments for bone diseases. The gut microbiota represents the largest micro-ecosystem in animals and is closely related to many metabolic disorders, including bone disease. It achieves this by secreting secondary metabolites and coordinating with various tissues and organs through the circulatory system, which leads to the concept of the gut-X axis. Given its importance, modulating gut microbiota to influence the gut-X axis presents new opportunities for understanding and developing innovative therapeutic approaches for poultry bone diseases. In light of the extensive literature on this topic, this review focuses on the effects of gut microbiota on bone density and strength in poultry, both directly and indirectly, through the regulation of the gut-X axis. Our aim is to provide scientific insights into the bone health problems faced by poultry.

Effects of dietary fiber on the composition, function, and symbiotic interactions of intestinal microbiota in pre-weaned calves

Introduction

Dietary fiber plays a crucial role in maintaining gastrointestinal health. However, its protective effects on the intestinal health of calves remain to be fully elucidated. This study aimed to investigate the impact of dietary fiber supplementation on the intestinal microbiota of pre-weaned calves and its potential role in modulating microbial metabolic pathways.

Methods

A randomized controlled trial was conducted, enrolling 135 calves that were randomly assigned into three groups: (1) inulin supplementation, (2) psyllium husk powder (PHP) supplementation, and (3) a control group receiving no dietary fiber. Fecal microbiota samples were collected from calves without diarrhea at five time points (0, 7, 14, 28, and 56 days of age). Metagenomic sequencing was performed to analyze microbial composition and functional pathways. Additionally, a differential analysis of carbohydrate-active enzymes (CAZymes) was performed to evaluate the effect of dietary fiber on carbohydrate metabolism enzyme activity within the intestinal microbiota.

Results

Calves supplemented with dietary fiber exhibited a significant increase in the abundance of Bifidobacterium and Prevotella compared to the control group. These bacterial genera contributed to intestinal protection by modulating secondary bile acid metabolism and flavonoid metabolism pathways. CAZymes differential analysis revealed an increased abundance of carbohydrate metabolism enzymes in response to dietary fiber supplementation, with distinct microbial community compositions observed among different fiber treatments. Notably, at 56 days of age, calves fed PHP harbored intergeneric symbiotic clusters comprising Clostridium, Prevotella, and Bacteroides, suggesting a cooperative microbial network that may contribute to intestinal homeostasis.

Discussion

The findings of this study highlight the beneficial effects of dietary fiber on calf intestinal microbiota, particularly in enhancing microbial diversity and enzymatic activity related to carbohydrate metabolism. The observed microbial symbiosis in PHP-fed calves suggests a potential role in maintaining intestinal homeostasis. These insights provide a theoretical foundation for optimizing dietary interventions to promote gut health in calves during the transition period. Further research is warranted to explore the mechanistic interactions between dietary fiber, gut microbiota, and host health outcomes.

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.

Causal associations between 26 musculoskeletal disorders and gut microbiota: a Mendelian randomization analysis with Bayesian validation

Emerging evidence suggests that gut microbiota imbalances may influence the onset of musculoskeletal disorders (MSDs), yet conclusive evidence establishing causation remains limited. This study investigates the causal relationship between gut microbiota and a range of MSDs, aiming to identify potential therapeutic targets. Using data on 211 gut microbiome taxa from a genome-wide association study (GWAS) and summary statistics for 26 MSDs from the Finnish Biobank, we employed Mendelian randomization (MR) with inverse-variance weighting (IVW) as the primary analytical approach, complemented by Bayesian model validation to ensure robust results. Our MR analyses revealed significant causal associations between gut microbiota and nine MSDs within four categories, including osteoporosis (IVW-Beta = 0.011, P = 0.025), rheumatoid arthritis (IVW-Beta = - 0.016, P < 0.001), rotator cuff syndrome (IVW-Beta = - 0.007, P = 0.022), and calcific tendonitis of the shoulder (IVW-Beta = - 0.021, P = 0.034). Bayesian validation underscored the plausibility of these relationships, supporting the potential causal role of gut microbiota in the development of these disorders. Our findings present a library of causal associations that underscore the gut microbiome's role in MSD pathogenesis, providing genetic evidence that highlights specific gut microbiota taxa as prospective therapeutic targets. This research offers novel insights into the pathogenic mechanisms underlying MSDs and points toward new directions for future investigation into microbiome-based therapies.

In vitro dynamics of rumen microbiota and fermentation profiles with Antler growth of Sika deer

The rumen microbiota plays a vital role in the nutrient metabolism affecting the growth of velvet antler. However, the fermentation patterns and dynamics of the rumen microbiota across growth stages of velvet antler remain largely unexplored. Here, we employed an in vitro fermentation approach to assess fermentation parameters and microbial composition in the rumen liquid of sika deer during the early growth (EG), metaphase growth (MG), and fast growth (FG) phases . Our findings indicated that the levels of short-chain fatty acids (SCFAs), ammonia nitrogen, and gas production increased over fermentation time in all three groups. The concentrations of total SCFAs, ammonia nitrogen, and gas production, along with the proportions of butyrate, isobutyrate, and isovalerate, were markedly higher in the MG and FG groups compared with the EG group. Principal coordinate analysis highlighted significant variations in microbial communities among the EG, MG, and FG groups during the fermentation process. The abundances of Stomatobaculum and Blautia across the three groups increased over fermentation time, whereas Bacteroides, Lawsonibacter, Sporobacter, Papillibacter, Butyricicoccus, and Succiniclasticum exhibited higher abundances in MG or FG groups than in the EG group after 24 hours of fermentation. Co-occurrence network analysis uncovered positive correlations between butyrate levels and butyrate-producing bacteria (Stomatobaculum, Butyrivibrio) in the MG and FG groups. Additionally, there were positive correlations between proteolytic bacteria (Clostridium and Roseburia) and branched-chain volatile fatty acids in the FG group. These findings shed light on the fermentation patterns and microbial dynamics within the rumen of sika deer during different growth periods of velvet antler.IMPORTANCEVelvet antlers are distinctive and rapidly growing organs that hold significant value in traditional medicine. Through in vitro analysis, our study characterized the dynamics of microbiota and metabolites within the rumen liquid fermentation of sika deer throughout the different antler growth phase. We identified distinct microbial communities at various fermentation time points and observed shifts in fermentation patterns that paralleled antler development. These findings suggest a potentially pivotal role for these microbial dynamics in facilitating the growth process of velvet antlers.

Recent trends in human milk oligosaccharides: New synthesis technology, regulatory effects, and mechanisms of non-intestinal functions

Recently, the non-intestinal functions of human milk oligosaccharides (HMOs) have been widely documented, including their roles in promoting brain development and growth, as well as ameliorating anxiety, allergies, and obesity. Understanding their mechanisms of action is becoming increasingly critical. Furthermore, these effects are frequently associated with the type and structure of HMOs. As an innovative technology, "plant factory" is expected to complement traditional synthesis technology. This study reviews the novel "plant factory" synthesis techniques. Particular emphasis is placed on the processes, advantages, and limitations of "plant factory" synthesis of HMOs. This technology can express genes related to HMO synthesis instantaneously in plant leaves, thereby enabling the rapid and cost-effective generation of HMOs. However, "plant factory" technology remains underdeveloped, and challenges related to low yield and unsustainable production must be addressed. Furthermore, we present an overview of the most recent clinical and preclinical studies on the non-intestinal functions of HMOs. This review emphasizes the mechanisms of action underlying the non-intestinal functions of HMOs. HMOs primarily exert non-intestinal functions through the cleavage of beneficial monomer components, metabolism to produce advantageous metabolites, and regulation of immune responses.

Gut microbiota dysbiosis involved in decabromodiphenyl ether-induced bone homeostasis disorder through inflammaging

BDE-209 has a causal relationship with adverse health outcomes. However, research on its effect on bone homeostasis is relatively lacking. This study examined the relationship between BDE-209 exposure and bone health, as well as the underlying mechanisms, using both in vitro and in vivo models. In animal studies, female SD rats were administered BDE-209 for 60 days. Bone mineral density, bone microstructure, gut microbiota, and inflammaging markers were measured. Furtherly, THP-1 cell-derived macrophages were treated with a culture medium containing population-relevant dose of BDE-209 or sodium butyrate. The expression of M1 macrophage markers, osteoclast markers, and inflammatory cytokines was measured. Then macrophages were induced by osteoclast conditioned medium to evaluate the effect of BDE-209 on their differentiation into osteoclasts. Results showed reduced humeral bone density, enhanced osteoclast activity, upregulation of IL-1β, TNF-α, IL-6, and activation of PGC-1α/NAD+/cGAS-STING in the exposed group. 16s sequencing revealed that BDE-209 disrupts the abundance of the gut microbiota, notably a reduction in Lachnospiraceae. In vitro, BDE-209 can stimulate macrophages to differentiate more osteoclasts and activate the cGAS-STING pathway, while sodium butyrate can inhibit these effects. This study reveals that gut microbiota dysbiosis is involved in BDE-209-induced bone homeostasis disorder through inflammatory aging and sodium butyrate can mitigate this effect. Overall, this study provides research data for the precaution and treatment of osteoporosis associated with BDE-209 exposure.

The Impact of Fermented Dairy Products and Probiotics on Bone Health Improvement

The bone is an important body organ due to its role in locomotion, protection and mineral homeostasis. Bone health is affected by various intrinsic and extrinsic factors like genetics, diet, environment and immune status of an individual. Being a dynamic organ, bones are continuously being remodeled and the remodeling is mediated by an intricate balance of bone formation and resorption which, in turn, are regulated by environmental, genetic, hormonal and neural factors. Lack of balance in any of these factors leads to bone disorders such as osteoporosis. Fermented dairy products along with their probiotics content play a significant role in bone remodeling process ensuring the maintenance of intricate balance in bone forming cells (osteoblasts) and bone resorbing cells (osteoclasts). Proteins and various minerals are important constituents of bone. Dairy products, especially fermented ones, are significant because of being a good source of proteins and minerals required to make and maintain a healthy bone. In addition, these provide the body with probiotics which are involved in bone health improvement by enhancing the bioavailability of dietary constituents, production of short chain fatty acids and reducing the inflammatory components. Hence, fermented dairy products should be a regular part of our diet to keep our bone healthy.

Metabolites and Charcot Foot: A Comprehensive Analysis Through Mendelian Randomization

BACKGROUND

Multiple studies have shown metabolites may have potential effects on Charcot foot. However, the Mendelian randomization method has not yet explored the relationship between metabolites and Charcot foot.

METHODS

We selected genetic variants from the publicly available Genome-wide Association Studies (GWAS) summary database to represent 1400 metabolites described in recent research. Mendelian randomization (MR) analysis was carried out to examine the relationships between these metabolites and Charcot foot. Significant single nucleotide polymorphism (SNP) data associated with exposure were screened out through association analysis. Valid instrumental variables (IVs) were then selected, excluding SNPs with F-statistic values below 10. The MR analyses primarily employed the inverse variance weighted (IVW) method. Bayesian weighted Mendelian randomization (BWMR), constrained maximum likelihood(cML), contamination mixture(Conmix), robust adjusted profile score(RAPS), and debiased inverse-variance weighted(deIVW) method were used to enhance the results. Colocalization analysis was performed to identify shared causal genetic variants associated with the resulting phenotypes. Sensitivity analyses, including assessments of Cochrane's Q test, egger intercept, and MR PRESSO test were conducted to confirm the robustness of the results.

RESULTS

After preliminary MR exploration, the IVW results exhibited positive causal relationships between hexadecenedioate (C16:1-DC) levels (OR = 0.698, 95%CI: 0.586 to 0.831, PFDR = 0.040), octadecadienedioate (C18:2-DC) levels (OR = 0.665, 95%CI: 0.552 to 0.800, PFDR = 0.021), octadecanedioylcarnitine (C18-DC) levels (OR = 0.676, 95%CI: 0.553 to 0.827, PFDR = 0.067) and Charcot foot. Colocalization analysis indicated that the above three metabolites share a common causal variant at the same genomic location with Charcot foot. Sixty-four metabolites with suggestive causal relationships with Charcot foot were also identified, among which 25 kinds of metabolites were positively correlated with Charcot foot, and 33 metabolites were negatively associated with Charcot foot. The BWMR, cML, Conmix, RAPS, and deIVW results supported our preliminary MR results. In several results, sensitivity analyses showed heterogeneity and horizontal pleiotropy, while the causal relationships obtained through FDR correction did not show any significant heterogeneity and horizontal pleiotropy. No reverse causal association was detected.

CONCLUSION

We detected protective and risk metabolites in Charcot foot. Controlling metabolites may decrease Charcot foot risk and serve as a novel therapeutic biomarker for the therapy.

The association of gut microbiome composition with musculoskeletal features in middle-aged and older adults: a two-cohort joint study

Background

Bones and muscles are connected anatomically, and functionally. Preliminary evidence has shown the gut microbiome influences the aging process of bone and muscle in animal studies. However, such evidence in humans is still scarce. This study aimed to assess the microbiome-bone and microbiome-muscle associations in two cohorts of community-dwelling older adults.

Methods

We leveraged information from two large population-based cohorts, i.e., the Rotterdam Study (mean age 62.7 ± 5.6 years; n=1,249) and the Framingham Heart Study (mean age 55.2 ± 9.1 years; n=1,227). For individuals included in this study, gut microbiome 16S rRNA sequencing, musculoskeletal phenotyping derived from DXA images, lifestyle and socioeconomic data, and medication records were available. Per cohort, the 16S rRNA sequencing data, derived from stool, were processed with the DADA2 pipeline and taxonomies were assigned using the SILVA reference database. In addition, the microbiome functional potential was obtained with PICRUSt2. Further, we investigated the association between the human gut microbiome (alpha diversity, genera and predicted functional pathways) and appendicular lean mass (ALM), femoral neck bone mineral density (FN-BMD) and trabecular bone score (TBS) using multilinear regression models controlling for multiple confounders, and performed a joint analysis from both cohorts. Sex-stratified analyses were also conducted.

Results

The gut microbiome alpha diversity was not associated with either tested phenotype after accounting for multiple-testing (P>1.67e-02). In the joint analysis, lower abundance of Oscillibacter (beta= -.51, 95%CI [-0.74, -.29]), Anaerotruncus (beta=-0.41, 95%CI [-0.61, - 0.21]), Eisenbergiella (beta=-0.39, 95%CI [-0.59, -.19]) and higher abundance of Agathobacter (beta=0.40, 95%CI [0.20, 0.60]) were associated with higher ALM (P<2.0e-04). Lower abundance of Anaerotruncus (beta=-0.32, 95%CI [-0.45, -.19]), Hungatella (beta=-0.26, 95%CI [-0.38, -.15]) and Clostridiales bacterium DTU089 (beta=-0.37, 95%CI [-0.55, -.19]) was associated with higher ALM only in females (P< 2.0e-04). Moreover, the biotin biosynthesis II pathway was positively associated with ALM (beta=0.44, 95% CI [0.24, 0.64]) (P<1.90e-04) in females while no associations were observed in males. We did not observe any robust association of bone traits with gut microbiome features.

Conclusion

Our results indicate that specific genera are associated with ALM in middle-aged and older adults and these associations can present in a sex-specific manner. Overall, our study suggests that the gut microbiome is linked to muscle aging in middle-aged and older adults. However, larger sample sizes are still needed to underpin the specific microbiome features involved.

The beneficial effects of a probiotic mix on bone and lean mass are dependent on the diet in female mice

Bone mass and lean mass decrease with age and these changes are associated with increased fracture risk and sarcopenia. Previous studies demonstrated that a probiotic mixture of Lacticaseibacillus paracasei DSM13434, Lactiplantibacillus plantarum DSM 15312 and DSM 15313 (L. Mix) prevents bone loss in ovariectomized (ovx) female mice. The purpose of the present study is to test if the beneficial effect of L. Mix is modified by the diet. Female mice were fed either a high-fat (HFD, 60% kcal from fat) or a low-fat (LFD, 10% kcal from fat) diet and subjected to either sham or ovx surgery and treated with L. Mix for 12 weeks. L. Mix treatment increased total body bone mineral density (p ≤ 0.01), by increasing cortical bone area, and total body lean mass (p = 0.035) in mice on LFD but not in mice on HFD. Metagenome sequencing of cecal content showed that L. Mix treatment increased the relative abundance of Lacticaseibacillus paracasei and, Lactiplantibacillus plantarum, demonstrating successful treatment. In addition, the probiotic treatment affected the overall gut microbiota composition and functionality. These findings demonstrate that the L. Mix in combination with a healthy diet is beneficial for musculoskeletal health in female mice.

Integrated metagenomic and metabolomic analyses of the effects of total flavonoids of Rhizoma Drynariae on reducing ovariectomized-induced osteoporosis by regulating gut microbiota and related metabolites

TFRD has been widely used in China to treat osteoporosis (OP). However, the specific molecular mechanism of TFRD against OP has not been fully clarified. Our previous studies have also proved that TFRD could attenuate OP and the clinical equivalent dose of 67.5mg/kg/d is the effective dose for TFRD treating OP. Therefore, this study used 67.5mg/kg as the dosage of TFRD in combination with multi omics to investigate the mechanism of action of TFRD in the treatment of OP. The aim of this study was to further elucidate molecular mechanism of TFRD for treating OP based on metagenomic and metabolomic analyses. In this study, hematoxylin-eosin (H&E) staining, micro computed tomography (micro-CT) and bone mineral density (BMD) analysis were used to observe pharmacological effects of TFRD against ovariectomized (OVX)-induced OP. Subsequently, multiomics analysis including metagenomics, untargeted and short chain fatty acids (SCFAs) metabolomics were carried out to identify whether the anti-osteoporosis mechanism of TFRD correlated with gut microbiota and related metabolites. Our results indicate that TFRD could improve the microstructure and density of trabecular bone in OVX rats. 17 differential species, which mainly from Akkermansia, Bacteroides, and Phascolarctobacterium genus, 14 related differential metabolites and acetic acid in SCFAs were significantly altered by OVX and reversed by TFRD. Furthermore, according to results of untargeted metabolomics analysis, it was found that several metabolic pathways such as phenylalanine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis and so on might play an important role in TFRD against OP. In order to further study the relationship between gut microbiota and related metabolites, spearman correlation analysis was used, and showed that gut microbiota such as Akkermansia muciniphila might be closely related to several metabolites and metabolic pathways. These findings suggest that TFRD treatment could reduce the effects of OVX-induced OP by altering community composition and abundance of gut microbiota, regulating metabolites and SCFAs. It was speculated that the gut microbiota especially Akkermansia muciniphila and related metabolites might play an important role in TFRD against OP, and deserve further study by follow-up experiment. This conclusion provides new theoretical support for mechanism research of TFRD against OP.

Gut microbiome and bone health: update on mechanisms, clinical correlations, and possible treatment strategies

The intestinal microbiome is increasingly regarded as a relevant modulator of the pathophysiology of several age-related conditions, including frailty, sarcopenia, and cognitive decline. Aging is in fact associated with alteration of the equilibrium between symbiotic bacteria and opportunistic pathogens, leading to dysbiosis. The microbiome is able to regulate intestinal permeability and systemic inflammation, has a central role in intestinal amino acid metabolism, and produces a large number of metabolites and byproducts, with either beneficial or detrimental consequences for the host physiology. Recent evidence, from both preclinical animal models and clinical studies, suggests that these microbiome-centered pathways could contribute to bone homeostasis, regulating the balance between osteoblast and osteoclast function. In this systematic review, we provide an overview of the mechanisms involved in the gut-bone axis, with a particular focus on microbiome function and microbiome-derived mediators including short-chain fatty acids. We also review the current evidence linking gut microbiota dysbiosis with osteopenia and osteoporosis, and the results of the intervention studies on pre-, pro-, or post-biotics targeting bone mineral density loss in both animal models and human beings, indicating knowledge gaps and highlighting possible avenues for future research.

Gut-X axis

Recent advances in understanding the modulatory functions of gut and gut microbiota on human diseases facilitated our focused attention on the contribution of the gut to the pathophysiological alterations of many extraintestinal organs, including the liver, heart, brain, lungs, kidneys, bone, skin, reproductive, and endocrine systems. In this review, we applied the "gut-X axis" concept to describe the linkages between the gut and other organs and discussed the latest findings related to the "gut-X axis," including the underlying modulatory mechanisms and potential clinical intervention strategies.

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.

Isolation and Evaluation of Potential Use of Prebiotics-Utilizing Butyrate-Producing Bacteria in Nibea coibor

Butyrate-producing bacteria (BPB) benefit the health of aquatic animals. This current study aimed to isolate BPB from the intestines of Nibea coibor and assess their probiotic potential. The results showed that nine isolates were obtained in vitro from the gut of N. coibor, including six Clostridium butyricum, two Proteocatella sphenisci, and one Fusobacterium varium. The representative bacteria, C. butyricum CG-3 and P. sphenisci DG-1, which produce high butyrate levels, were further studied for short-chain fatty acid (SCFA) production and antibiotic susceptibility. The effects of BPB singly (CB: basal diet + CG-3 and PS: basal diet + DG-1, at 107 CFU/g) or in combination with galactooligosaccharides (GOS) (0.5%) and inulin (0.5%) (CBIG) or D-sorbitol (0.5%) (PSGS) on the growth and health status of N. coibor were investigated. Results showed an increase in growth parameters in the CB, CBIG, and PSGS groups, except for the PS group. Alterations in intestinal microbiota (including diversity, abundance, and function) were observed in four experimental groups (CB, CBIG, PS, and PSGS groups). SCFA contents increased in treated groups; butyrate production was positively related to bacterial abundance. Compared to control, levels of complement C3, complement C4, immunoglobulin M (IgM), transforming growth factor-β (TGF-β), interleukin (IL)-10, IL-1β, and lysozyme (LZM) increased, while malondialdehyde (MDA) decreased in treated groups. Contents of IL-6 (PS and PSGS groups), tumor necrosis factor-alpha (TNF-α) (CB, PS, and PSGS groups), total antioxidant capacity (T-AOC) (CB and PS groups), total superoxide dismutase (T-SOD) (PS group), catalase (CAT) (CB and PSGS groups), and activities of amylase (PS and PSGS groups), trypsin (CB group), and lipase (CBIG group) were increased. Our results suggested the potential use of C. butyricum CG-1 or P. sphenisci DG-1 singly or in combination with prebiotics improved growth and health conditions in N. coibor.

Potential role of gut-related factors in the pathology of cartilage in osteoarthritis

Osteoarthritis (OA) is a common progressive degenerative disease. Gut microbiota (GM) and their metabolites have been closely associated with the onset, progression, and pathology of OA. GM and their metabolites may influence the cartilage directly, or indirectly by affecting the gut, the immune system, and the endocrine system. They function through classical pathways in cartilage metabolism and novel pathways that have recently been discovered. Some of them have been used as targets for the prevention and treatment of OA. The current study sought to describe the major pathological signaling pathways in OA chondrocytes and the potential role of gut-related factors in these pathways.

Exploring the relationship between periodontal diseases and osteoporosis: Potential role of butyrate

Osteoporosis, a condition marked by the loss of bone density and mass, affects individuals of all ages. However, it becomes more prevalent and severe with aging, increasing the risk of fractures and other health complications. Recent research has highlighted a link between osteoporosis and periodontitis, a chronic gum disease, as both conditions involve excessive bone loss that can lead to significant oral health problems if untreated. The growing interest in strategies to prevent bone loss has brought attention to butyrate, a short-chain fatty acid produced by gut bacteria during fiber fermentation. Butyrate has demonstrated protective effects against systemic bone loss, particularly in the context of osteoporosis. Notably, oral bacteria also produce butyrate, suggesting its potential as a therapeutic tool for preventing periodontal bone loss. Given the connection between systemic and oral health, understanding the role of butyrate in bone metabolism could offer new avenues for treating osteoporosis and periodontitis. This review will explore the biological mechanisms through which butyrate influences bone health, aiming to highlight its potential therapeutic applications in preventing bone loss across these conditions.

The contribution of the novel CLTC-VMP1 fusion gene to autophagy regulation and energy metabolism in cisplatin-resistant osteosarcoma

Osteosarcoma (OS) is a highly malignant tumor, and chemotherapy resistance is a major challenge in the treatment of this disease. This study aims to explore the role of the CLTC-VMP1 gene fusion in the mechanism of chemotherapy resistance in OS and investigate its molecular mechanisms in mediating energy metabolism reprogramming by regulating autophagy and apoptosis balance. Using single-cell transcriptome analysis, the heterogeneity of OS cells and their correlation with resistance to platinum drugs were revealed. Cisplatin-resistant cell lines were established in human OS cell lines for subsequent experiments. Based on transcriptomic analysis, the importance of VMP1 in chemotherapy resistance was confirmed. Lentiviral vectors overexpressing or interfering with VMP1 were used, and it was observed that inhibiting VMP1 could reverse cisplatin resistance, promote cell apoptosis, and inhibit autophagy, and mitochondrial respiration and glycolysis. Furthermore, the presence of CLTC-VMP1 gene fusion was validated, and its ability to regulate autophagy and apoptosis balance, promote mitochondrial respiration, and glycolysis was demonstrated. Mouse model experiments further confirmed the promoting effect of CLTC-VMP1 on tumor growth and chemotherapy resistance. In summary, the CLTC-VMP1 gene fusion mediates energy metabolism reprogramming by regulating autophagy and apoptosis balance, which promotes chemotherapy resistance in OS.NEW & NOTEWORTHY This study identifies the CLTC-VMP1 gene fusion as a key driver of chemotherapy resistance in osteosarcoma by regulating autophagy and reprogramming cellular energy metabolism. Through single-cell transcriptomics, the research reveals the heterogeneity of tumor cells and the role of VMP1 in promoting resistance to cisplatin. The findings suggest that targeting the CLTC-VMP1 fusion gene may offer new therapeutic strategies to overcome chemotherapy resistance in osteosarcoma.

Decoding the synergistic potential of herbal medicine and dietary supplements for treating postmenopausal osteoporosis

PURPOSE

The exploration of the combined effects of FLL and quinoa presents an intriguing opportunity to enhance the efficacy of osteoporosis treatment.

METHODS

This study aimed to predict the potential anti-osteoporotic effects of FLL and quinoa using network pharmacology and subsequently verify these predictions through experimental investigation. Thirty rats were divided into five groups: sham operation group (SO), ovariectomized group (OVX), FLL group (FLL), quinoa group (Quinoa), and FLL combined with quinoa group (F&Q). The 12-week experiment involved measurements of bone density and microstructure, histological evaluation of femoral trabeculae and bone cortex, quantification of osteoclasts in the femur, assessment of osteoclast differentiation factor expression (NFATc1 and C-Fos), and measurement of collagen I carboxyl-terminal peptide (CTX-1). Additionally, intestinal flora analysis was performed.

RESULTS

The results demonstrated reduced bone mineral density, compromised bone microarchitecture, increased osteoclast numbers and differentiation, and enhanced bone resorption in the OVX group, which were completely ameliorated by FLL, quinoa and F&Q interventions. F&Q exhibited superior improvement in bone density and microarchitecture compared to FLL and quinoa, although no significant differences were observed in their effects on osteoclasts and bone resorption. Gut flora analysis revealed that F&Q was more effective than FLL and quinoa in alleviating OVX-induced intestinal flora disorders, particularly in terms of enhancing intestinal flora diversity and function.

CONCLUSION

The combo of FLL and quinoa was more effective in treating ovariectomy-induced osteoporosis and gut flora dysbiosis than FLL alone.

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.

Colon-targeted engineered postbiotics nanoparticles alleviate osteoporosis through the gut-bone axis

The potential for mitigating intestinal inflammation through the gut-bone axis in the treatment of osteoporosis is significant. While various gut-derived postbiotics or bacterial metabolites have been created as dietary supplements to prevent or reverse bone loss, their efficacy and safety still need improvement. Herein, a colon-targeted drug delivery system is developed using surface engineering of polyvinyl butyrate nanoparticles by shellac resin to achieve sustained release of postbiotics butyric acid at the colorectal site. These engineered postbiotics nanoparticles can effectively suppress macrophage inflammatory activation, modulate the redox balance, and regulate the composition of the gut microbiota, thereby restoring epithelial barriers, inhibiting bacterial invasion, and down-regulating pro-inflammatory responses. As a result, the remission of systemic inflammation is accompanied by a rebalancing of osteoblast and osteoclast activity, alleviating inflammatory bowel disease-related and post-menopausal bone loss. Specifically, the treatment of engineered postbiotics nanoparticles can also improve the quality and quantity of bone with restoration of deteriorative mechanical properties, which indicating a therapeutic potential on fracture prevention. This study provides valuable insights into the gut-bone axis and establishes a promising and safe therapeutic strategy for osteoporosis.

Modified Zuo Gui Wan Ameliorates Ovariectomy-Induced Osteoporosis in Rats by Regulating the SCFA-GPR41-p38MAPK Signaling Pathway

Objective

Modified Zuo Gui Wan (MZGW) was a combination of Zuo Gui Wan and red yeast rice used for treating osteoporosis (OP), but its mechanism remains unclear. We aimed to validate the anti-OP effect of MZGW and explore its underlying mechanism.

Methods

An ovariectomy (OVX) rat model in vivo and a RANKL-induced osteoclasts (OCs) model in vitro were established. Key active ingredients in MZGW high dose (MZGW-H) group were detected by UPLC-MS/MS. Micro-CT scans and histomorphology analysis were performed in OVX rats. 16S rRNA gene sequencing was performed to investigate the relationship between the anti-OP effect of MZGW-H and intestinal flora. CCK-8 assay was applied to examine the optimal concentration of Modified Zuo Gui Wan drug serum (MZGW-DS) on osteoclasts. The qRT-PCR and Western blotting were utilized to explore the potential anti-OP pathway of MZGW, namely the SCFA-GPR41-p38MAPK signaling pathway. GPR41 was knocked down to further reverse to verify whether the pathway was the key pathway for MZGW-DS to exert its inhibitory effect on osteoclasts.

Results

The three main blood components, Ferulic acid, L-Ascorbic acid and Riboflavin, were examined mainly by UPLC-MS/MS. 16S rRNA gene sequencing showed that MZGW-H changed the metabolism of SCFAs. In vivo studies verified that MZGW-H ameliorated microstructure damage, improved histological changes and reduced TRAP, BALP, and BGP in OVX rats by regulating the SCFA-GPR41-p38MAPK signaling pathway. CCK-8 revealed that 5% MZGW-DS group was the most optimal concentration of MZGW-DS to inhibit osteoclast differentiation. In vitro, MZGW-DS was better than peripheral blood concentration of SCFAs in inhibiting osteoclasts. After the knockout of GPR41, MZGW-DS could not inhibit the expression of osteoclast-related protein (CTSK and NFATc1) via SCFA-GPR41-p38MAPK signaling pathway.

Conclusion

MZGW-H effectively ameliorates OVX-induced osteoporosis partially achieved by increasing SCFAs metabolism and modulating the SCFA-GPR41-p38MAPK signaling pathway.

Butyric Acid Modulates Gut Microbiota to Alleviate Inflammation and Secondary Bone Loss in Ankylosing Spondylitis

Background: Ankylosing spondylitis (AS) is a chronic inflammatory and autoimmune disease that primarily affects the sacroiliac joints and axial skeleton. While the exact pathogenetic mechanism of AS remains unclear, previous reports have highlighted the involvement of genetic factors, immune responses, and gut microbiota dysregulation in the development of this condition. Short-chain fatty acids (SCFAs), which are microbial fermentation products derived from sugar, protein, and dietary fibers, play a role in maintaining the intestinal barrier function and reducing inflammatory responses. The aim of this study was to investigate the therapeutic potential of butyric acid (BA), an important SCFA, in the treatment of AS. Methods: To evaluate the anti-inflammatory and anti-bone loss effects of BA, a murine AS model was established using proteoglycan and dimethyl dioctadecyl ammonium (DDA) adjuvants. Various techniques, including an enzyme-linked immunosorbent assay (ELISA), magnetic resonance imaging (MRI), micro-CT, histology, quantitative PCR (qPCR) for intestinal tight junction protein expression, and 16S rDNA sequencing to analyze gut microbiota abundance, were employed to assess the inflammation and bone health in the target tissues. Results: The results indicated that BA demonstrated potential in alleviating the inflammatory response in the peripheral joints and the axial spine affected by AS, as evidenced by the reductions in inflammatory infiltration, synovial hyperplasia, and endplate erosion. Furthermore, BA was found to impact the intestinal barrier function positively. Notably, BA was associated with the downregulation of harmful inflammatory factors and the reversal of bone loss, suggesting its protective effects against AS. Conclusions: These beneficial effects were attributed to the modulation of gut microbiota, anti-inflammatory properties, and the maintenance of skeletal metabolic homeostasis. This study contributes new evidence supporting the relationship between gut microbiota and bone health.

Gut Microbiota Modulation: A Novel Strategy for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a chronic autoimmune disease that leads to joint inflammation, progressive tissue damage and significant disability, severely impacting patients' quality of life. While the exact mechanisms underlying RA remain elusive, growing evidence suggests a strong link between intestinal microbiota dysbiosis and the disease's development and progression. Differences in microbial composition between healthy individuals and RA patients point to the role of gut microbiota in modulating immune responses and promoting inflammation. Therapies targeting microbiota restoration have demonstrated promise in improving treatment efficacy, enhancing patient outcomes and slowing disease progression. However, the complex interplay between gut microbiota and autoimmune pathways in RA requires further investigation to establish causative relationships and mechanisms. Here, we review the current understanding of the gut microbiota's role in RA pathogenesis and its potential as a therapeutic target.

The microbial metabolite imidazole propionate dysregulates bone homeostasis by inhibiting AMP-activated protein kinase (AMPK) signaling

Microbial metabolites provide numerous benefits to the human body but can also contribute to diseases such as obesity, diabetes, cancer, and bone disorders. However, the role of imidazole propionate (ImP), a histidine-derived metabolite produced by the intestinal microbiome, in bone metabolism and the development of osteoporosis is still poorly understood. In this study, we investigated the role of ImP and its underlying mechanisms in regulating bone homeostasis. When ImP was administered to 8-week-old mice for 4 weeks, bone loss was observed, along with a decrease in alkaline phosphatase-positive osteoblast cells. Additionally, bone marrow stromal cells (BMSCs) isolated from ImP-treated mice exhibited reduced osteogenic potential. In BMSCs from control mice, ImP treatment inhibited BMP2-induced osteoblast differentiation while promoting adipocyte differentiation. However, ImP had no effect on RANKL-induced osteoclast differentiation or activity in bone marrow macrophages. Mechanistically, ImP treatment increased p38γ phosphorylation and decreased AMPK (T172) phosphorylation in BMSCs. Suppression of p38γ expression using si-p38γ reversed the inhibitory effects of ImP on osteoblast differentiation, with a concurrent increase in AMPK (T172) phosphorylation. Conversely, ImP stimulated adipocyte differentiation by decreasing AMPK (T172) phosphorylation. Treatment with the AMPK agonist metformin significantly reversed the inhibitory effects of ImP on osteoblast differentiation and the promotion of adipocyte differentiation, along with enhanced AMPK (T172) phosphorylation. These findings suggest that the microbial metabolite ImP may disrupt bone homeostasis by stimulating p38γ phosphorylation and inhibiting the AMPK pathway, presenting a potential therapeutic target for managing metabolic bone diseases.

Immunotherapy in the management of inflammatory bone loss in osteoporosis

Osteoporosis, a progressive skeletal disorder characterized by decreased bone mass and increased fracture risk, has traditionally been treated with pharmacological agents targeting bone remodeling. However, emerging research highlights the critical role of immune system in regulating bone metabolism, introducing the concept of Osteoimmunology. Chronic low-grade inflammation is now recognized as a significant contributor to osteoporosis, particularly in postmenopausal women and the elderly. Immune cells, such as T cells and B cells, and their secreted cytokines directly influence bone resorption and formation, tipping the balance toward net bone loss in inflammatory environments. Immunotherapy, a treatment modality traditionally associated with cancer and autoimmune diseases, is now gaining attention in the management of osteoporosis. By targeting immune dysregulation and reducing inflammatory bone loss, immunotherapies offer a novel approach to treating osteoporosis that goes beyond merely inhibiting bone resorption or promoting bone formation. This therapeutic strategy includes monoclonal antibodies targeting inflammatory cytokines, cell-based therapies to enhance the function of regulatory T and B cells, and interventions aimed at modulating immune pathways linked to bone health. This chapter reviews the emerging role of immunotherapy in addressing inflammatory bone loss in osteoporosis. Present chapter also explores the underlying immune mechanisms contributing to bone degradation, current immunotherapeutic strategies under investigation, and the potential of these approaches to revolutionize the management of osteoporosis.

Mechanisms of gut homeostasis regulating Th17/Treg cell balance in PMOP

Postmenopausal osteoporosis (PMOP) is a metabolic bone disease driven by estrogen deficiency, primarily manifesting as reduced bone mass and heightened fracture risk. Its development is intricately linked to the balance between Th17 and Treg cells. Recent studies have highlighted the significant role of gut homeostasis in PMOP. The gut microbiota profoundly impacts bone health by modulating the host's immune system, metabolic pathways, and endocrine functions. In particular, the regulation of Th17 and Treg cell balance by gut homeostasis plays a pivotal role in the onset and progression of PMOP. Th17 cells secrete pro-inflammatory cytokines that stimulate osteoclast activity, accelerating bone resorption, while Treg cells counteract this process through anti-inflammatory mechanisms, preserving bone mass. The gut microbiota and its metabolites can influence Th17/Treg equilibrium, thereby modulating bone metabolism. Furthermore, the integrity of the gut barrier is critical for systemic immune stability, and its disruption can lead to immune dysregulation and metabolic imbalances. Thus, targeting gut homeostasis to restore Th17/Treg balance offers a novel therapeutic avenue for the prevention and treatment of PMOP.

Effects of Synbiotic Supplementation on Bone and Metabolic Health in Caucasian Postmenopausal Women: Rationale and Design of the OsteoPreP Trial

BACKGROUND/OBJECTIVES

Correction of decreased diversity of the gut microbiome, which is characteristic of menopause, by supplementation with a synbiotic may attenuate or prevent dysbiosis processes and preserve bone mass. We describe the rationale and design of the OsteoPreP trial aimed at evaluating the effects of 12 months of supplementation with a synbiotic on bone and metabolic health in postmenopausal Caucasian women.

METHODS

This is a randomized, double-blinded, placebo-controlled trial among 160 Caucasian, postmenopausal women with no current diagnosis of osteoporosis or supplementation with pro- or prebiotics, and no medical treatment affecting bone turnover. Dual-energy X-ray absorptiometry scans will be conducted at screening to confirm absence of osteoporosis. The primary outcome is the relative change (%) in total bone mineral density of the distal tibia at 12 months post-treatment between the active and placebo groups, as determined via high-resolution peripheral quantitative computed tomography. Secondary outcomes are the effects on immune system modulation and cognition, gut microbiota composition, and musculoskeletal and metabolic functions, with particular emphasis on blood glucose regulation.

CONCLUSIONS

The trial will inform on the efficacy and safety of a synbiotic containing both aerobic and anerobic bacterial strains and a prebiotic fiber on reduction in bone loss and on indices of blood glucose regulation. This trial may pave the way for an exciting field of translational research and be the underpinnings of the prevention strategy of osteoporosis and the management of metabolic dysfunction in postmenopausal women. The trial is registered with clinicaltrials.gov (NCT05348694).

Pharmacological inhibition of HIF2 protects against bone loss in an experimental model of estrogen deficiency

Estrogen deficiency, which is linked to various pathological conditions such as primary ovarian insufficiency and postmenopausal osteoporosis, disrupts the delicate balance between bone formation and resorption. This imbalance leads to bone loss and an increased risk of fractures, primarily due to a significant reduction in trabecular bone mass. Trabecular osteoblasts, the cells responsible for bone formation within the trabecular compartment, originate from skeletal progenitors located in the bone marrow. The microenvironment of the bone marrow contains hypoxic (low oxygen) regions, and the hypoxia-inducible factor-2α (HIF2) plays a crucial role in cellular responses to these low-oxygen conditions. This study demonstrates that the loss of HIF2 in skeletal progenitors and their derivatives during development enhances trabecular bone mass by promoting bone formation. More importantly, PT2399, a small molecule that specifically inhibits HIF2, effectively prevents trabecular bone loss in ovariectomized adult mice, a model for estrogen-deficient bone loss. Both the genetic and pharmacological approaches result in an increase in osteoblast number, which is linked to the expansion of the pool of skeletal progenitor cells. This expansion either by loss or inhibition of HIF2 uncovers a pivotal mechanism for increasing osteoblast numbers and bone formation, resulting in greater trabecular bone mass.

Delineating the nexus between gut-intratumoral microbiome and osteo-immune system in bone metastases

Emerging insights in osteoimmunology have enabled researchers to explore in depth the role of immune modulation in regulating bone health. Bone is one of the common sites of metastasis notably in case of breast cancer, prostate cancer and several other cancer types. High calcium ion concentration and presence of several factors within the mineralized bone matrix including TGF-β, BMP etc., aid in tumor growth and proliferation. Accumulating evidence has substantiated the role of the gut-microbiota (GM) in tumorigenesis, further providing a strong impetus for the growing "immune-cancer-gut microbiota" relationship. Recent advancements in research further highlight the importance of the intra-tumor microbiota in conjunction with GM in cancer metastasis. Intratumoral microbiota owing to their ability to cause genetic instability, mutations, and epigenetic modifications within the tumor microenvironment, has been recognized to affect cancer cell physiology. The host microbiota and immune system crosstalk shapes the innate and adaptive arms of the immune system, which is the key player in cancer progression. In this review, we aim to decipher the role of microorganisms mediating bone metastasis by shedding light on the immuno-onco-microbiome (IOM) axis. We discussed the feasible cancer therapeutic interventions based on the modulation of the microbiome-immune cell axis which includes prebiotics, probiotics, and postbiotics. Here, we leverage the conceptual framework based on the published articles on microbiota-based therapies to target bone metastases. Understanding this complicated nexus will provide insights into fundamental factors governing bone metastases which will subsequently help in managing this malignancy with better efficacy.

Advances in body composition and gender differences in susceptibility to frailty syndrome: Role of osteosarcopenic obesity

There is general consensus that an improper diet negatively impacts health and that nutrition is a primary tool for the prevention of non-communicable diseases. Unfortunately, the importance of studying body composition, which can reveal early predictors of gender-related diseases, is still not well understood in this context. Currently, individuals are still classified as obese based solely on their body mass index, without considering the amount of fat, its distribution, and the quantity of muscle and bone mass. In this regard, the body composition phenotype defined as "osteosarcopenic obesity" affects approximately 6-41 % of postmenopausal women, with prevalence increasing with age due to the hormonal and metabolic changes that occur during this period. This particular phenotype arises from the strong relationship between visceral fat, muscle, bone, and gut microbiota and predispose postmenopausal women to frailty. Frailty is a complex clinical phenomenon with significant care and economic implications for our society. Recent studies suggest that women have a higher prevalence of frailty syndrome and its individual components, such as osteoporosis, fractures and sarcopenia, compared to men. Here, we provide a comprehensive overview of recent advances regarding the impact of gender on body composition and frailty. Furthermore, we reflect on the crucial importance of personalized nutritional interventions, with a focus on reducing visceral fat, increasing protein intake and optimizing vitamin D levels. A review of the scientific literature on this topic highlights the importance of studying body composition for a personalized and gender-specific approach to nutrition and dietetics, in order to identify frailty syndrome early and establish personalized treatments. This new method of researching disease predictors could likely help clarify the controversial results of studies on vitamin D, calcium and proteins, translate into practical wellness promotion across diverse elderly populations.

Sodium butyrate protect bone mass in lipopolysaccharide-treated rats by reducing oxidative stress and inflammatory

OBJECTIVE

The study will be to observe the effect of Sodium butyrate (NaB) on bone loss in lipopolysaccharide (LPS)-treated rats.

METHODS

In the rat model, we observed that changes in the expression of oxidative stress regulators, inflammatory markers and target genes were measured by immunofluorescence and RT-PCR after treatment. Changes in viability and osteogenesis of MC3T3-E1, osteoclast differentiation in RAW264.7 cells in the presence of LPS were evaluated using CCK-8, ALP staining, RES staining, and TRAP staining.

RESULTS

In vitro experiments have shown that LPS-induced inhibition of JC-1, SIRT1, GPX1 and SOD2 is associated with increased levels of inflammation and oxidative stress. In addition, NaB has been found to suppress oxidative stress, inflammation and Mito SOX, promote osteogenic differentiation, and inhibit osteoclast differentiation. In addition, NaB significantly promoted SITR1 expression, repaired impaired bone metabolism, and improved bone strength and bone mineral density.

CONCLUSION

Given all this experimental evidence, the results strongly suggest that NaB can restore osteogenic activity in the presence of LPS by reducing intracellular ROS, inhibiting osteoclast differentiation and reducing bone loss in LPS-treated rat models.