Lipid metabolism disorders and bone dysfunction--interrelated and mutually regulated (review)

PCSK9 inhibitors and osteoporosis: mendelian randomization and meta-analysis

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors represent an effective strategy for reducing cardiovascular disease risk. Yet, PCSK9's impact on osteoporosis remains unclear. Hence, we employed Mendelian randomization (MR) analysis for examining PCSK9 inhibitor effects on osteoporosis.

METHODS

Single nucleotide polymorphisms (SNPs) for 3-hydroxy-3-methylglutaryl cofactor A reductase (HMGCR) and PCSK9 were gathered from available online databases for European pedigrees. Four osteoporosis-related genome-wide association studies (GWAS) data served as the main outcomes, and coronary artery disease (CAD) as a positive control for drug-targeted MR analyses. The results of MR analyses examined by sensitivity analyses were incorporated into a meta-analysis for examining causality between PCSK9 and HMGCR inhibitors and osteoporosis.

RESULTS

The meta-analysis involving a total of 1,263,102 subjects, showed that PCSK9 inhibitors can increase osteoporosis risk (P < 0.05, I2, 39%). However, HMGCR inhibitors are not associated with osteoporosis risk. Additionally, a replication of the analysis was conducted with another exposure-related GWAS dataset, which led to similar conclusions.

CONCLUSION

PCSK9 inhibitors increase osteoporosis risk. However, HMGCR inhibitors are unremarkably linked to osteoporosis.

Associations between new obesity indices and abnormal bone density in type 2 diabetes mellitus patients

The clinical data analysis found that, compared with the traditional obesity index, the waist-weight ratio (WWR) has more advantages in predicting abnormal bone mineral density in subjects with type 2 diabetes. WWR may serve as a new predictive indicator for osteoporosis in T2DM patients.

PURPOSE

This study was designed to explore the correlation between obesity-related indices and bone mineral density (BMD) and its influencing factors in type 2 diabetes mellitus (T2DM) patients.

METHODS

A total of 528 patients with type 2 diabetes were recruited. Glucose tolerance, insulin stimulation, and blood biochemical tests were conducted on all participants. All subjects underwent dual-energy X-ray bone density testing and were grouped based on the bone density results.

RESULTS

Compared with those in the normal BMD group, the waist-to-body weight ratio (WWR) and weight-adjusted-waist index (WWI) in the osteopenia and osteoporosis groups were significantly greater, while body mass index (BMI) was significantly lower (P < 0.05). The logistic regression results showed that the WWR, WWI, and BMI were independently correlated with abnormal BMD in T2DM patients (P < 0.05). WWR and the WWI were negatively correlated with the T-value of bone density in various parts of the body, while BMI was positively correlated with the T-value of bone density (P < 0.05). The area under the working characteristic curve (AUC) for T2DM patients with abnormal bone mass predicted by the WWR [0.806, 95% CI = (0.770-0.843), P < 0.001] was greater than that for patients with other obesity indicators, such as the WWI and BMI.

CONCLUSION

We found a positive correlation between the WWR and bone density in T2DM patients. Compared with other obesity indicators, such as BMI and WWI, the WWR has a stronger discriminative ability for T2DM patients with abnormal bone density. Therefore, more attention should be given to the WWR in T2DM patients.

The relationship between advanced liver fibrosis and osteoporosis in type 2 diabetes patients with MAFLD

PURPOSE

To investigate the relationship between advanced liver fibrosis and osteoporosis in metabolic-associated fatty liver disease (MAFLD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 1144 T2DM patients were divided into the MAFLD and non-MAFLD groups, 460 T2DM patients with MAFLD (277 males aged ≥50 years and 183 postmenopausal females) were divided into N1 (advanced liver fibrosis excluded), N2 (indeterminate advanced liver fibrosis), and N3 (advanced liver fibrosis) groups according to the non-alcoholic fatty liver fibrosis score (NFS), the differences in bone mineral density (BMD) levels and prevalence of osteoporosis were compared. Based on the tertile levels of BMD of the lumbar spine (L), T2DM patients were divided into three groups (T1, T2, and T3), and the differences in the prevalence of advanced liver fibrosis were compared.

RESULTS

The BMD levels of the L4, and L1-4 in the MAFLD group were lower than those of the non-MAFLD groups in male and female T2DM patients .The BMD levels of the total hip, L4, and L1-4 in the N3 group were lower than those of the N2 and N1 groups in male and female T2DM patients with MAFLD, and the prevalence of osteoporosis in the N3 group of males was higher than that in the N1 group. The BMD levels of the total hip, L4, and L1-4 were negatively correlated with NFS in both males and females. The BMD levels of the total hip and L4 in males, and the BMD level of L4 in females were negatively associated with NFS. The prevalence of advanced liver fibrosis was higher in the T1 group than in the T2 and T3 groups in T2DM patients with MAFLD.

CONCLUSION

The BMD levels in male aged ≥50 years or postmenopausal female diabetic patients with MAFLD were negatively correlated with the degree of advanced liver fibrosis, which means an increased risk of liver fibrosis with decreasing BMD.

The role of lipid metabolism in osteoporosis: Clinical implication and cellular mechanism

In recent years, researchers have become focused on the relationship between lipids and bone metabolism balance. Moreover, many diseases related to lipid metabolism disorders, such as nonalcoholic fatty liver disease, atherosclerosis, obesity, and menopause, are associated with osteoporotic phenotypes. It has been clinically observed in humans that these lipid metabolism disorders promote changes in osteoporosis-related indicators bone mineral density and bone mass. Furthermore, similar osteoporotic phenotype changes were observed in high-fat and high-cholesterol-induced animal models. Abnormal lipid metabolism (such as increased oxidized lipids and elevated plasma cholesterol) affects bone microenvironment homeostasis via cross-organ communication, promoting differentiation of mesenchymal stem cells to adipocytes, and inhibiting commitment towards osteoblasts. Moreover, disturbances in lipid metabolism affect the bone metabolism balance by promoting the secretion of cytokines such as receptor activator of nuclear factor-kappa B ligand by osteoblasts and stimulating the differentiation of osteoclasts. Conclusively, this review addresses the possible link between lipid metabolism disorders and osteoporosis and elucidates the potential modulatory mechanisms and signaling pathways by which lipid metabolism affects bone metabolism balance. We also summarize the possible approaches and prospects of intervening lipid metabolism for osteoporosis treatment.

Non-linear association of atherogenic index of plasma with bone mineral density a cross-sectional study

INTRODUCTION

Although there has been abundant evidence of the association between dyslipidemia as a single factor and osteoporosis, the non-linear relationship between osteoporosis and the Atherogenic Index of Plasma (AIP) has not yet been thoroughly investigated. This study aimed to investigate the complex relationship between AIP and bone mineral density (BMD) to elucidate their interrelationship.

METHODS

An analysis of 2007-2018 National Health and Nutrition Survey (NHANES) data was conducted for this study. The study enrolled 5,019 participants. Logarithmically multiplying triglycerides and high-density lipoprotein cholesterol yields the AIP (base 10). The measured variables consisted of BMD in the total femur (TF), femoral neck (FN), and lumbar spine (LS). The association between AIP and BMD was examined using a range of statistical models, such as weighted multivariable logistic regression, generalized additive model, etc. RESULTS: It was found that AIP was positively associated with BMD after adjusting for age, gender, race, socioeconomic status, degree of education, income, Consuming alcoholic beverages, osteoporosis status (Yes or No), ALT, AST, serum creatinine, and total calcium levels. Further studies supported the association link between elevated BMD and AIP. Furthermore, compared to men, females had a higher positive connection between AIP and BMD. In general, there was a curve in the reverse L-shape seen, with a point of change around 0.877, indicating a relationship between AIP and TF BMD. Moreover, a curve exhibiting an L-formed pattern, with a point of inflection at around 0.702, was seen between AIP and FN BMD. In addition, a J-shaped curve was seen, with a point of inflection at 0.092, which demonstrates the association between AIP and LS BMD.

CONCLUSION

The AIP and TF BMD curves resemble inverted L shapes, as do the AIP and FN BMD curves. The relationship between AIP and LS BMD was further demonstrated by a J-shaped curve. The results indicate a possible association between AIP and bone mineral density, which should be explored in more detail.

Higher high-density lipoprotein cholesterol levels increased vertebral osteoporotic fracture, but reduced hip fracture in men based on the National Health Insurance Service-National Health Screening Cohort

BACKGROUND CONTEXT

Lipids are currently known to play an important role in bone metabolism.

PURPOSE

This study aimed to investigate the effect of high-density lipoprotein cholesterol (HDL-C) on osteoporotic fractures beyond its beneficial effects on the cardiovascular system.

STUDY DESIGN/SETTING

This was a retrospective, observational study that used data from the National Health Insurance Service-Health Screening cohort database.

PATIENT SAMPLE

This study included 318,237 participants who were 50 years or older and with HDL-C levels of 10 to 200 mg/dL.

OUTCOMES MEASURES

Physiologic measure-Diagnosis of osteoporotic fracture during the follow-up period.

METHODS

The study participants were categorized into four quartiles according to baseline HDL-C levels. The Cox proportional hazards model was used to assess osteoporotic fracture risk according to HDL-C levels.

RESULTS

After full adjustment and with the Q1 group as the reference group, estimates of hazard ratios (HRs; 95% confidence intervals [CIs]) for any osteoporotic fracture in men were 1.03 (0.94-1.12), 1.02 (0.93-1.11), and 1.07 (0.98-1.18) for the Q2, Q3, and Q4 groups, respectively. After classifying osteoporotic fractures according to the body location, the fully adjusted HRs for vertebral and hip fractures in the men's Q4 groups were 1.16 (1.02-1.31) and 0.74 (0.57-0.96), respectively. In women, fully adjusted HRs (95% CIs) of the female Q4 group for any osteoporotic, vertebral, and hip fractures were 1.03 (0.95-1.11), 0.96 (0.86-1.07), and 1.06 (0.80-1.41), respectively.

CONCLUSION

In this study, HDL-C levels were positively associated with vertebral fractures in both men and women but inversely related to hip fractures in men. Therefore, monitoring the lipid profiles of patients with osteoporosis may be beneficial for the prevention of osteoporotic fractures.

MicroRNA let-7g links foam cell formation and adipogenic differentiation: A key regulator of Paeonol treating atherosclerosis-osteoporosis

BACKGROUD

High comorbidity rates have been reported in patients with atherosclerosis and osteoporosis, posing a serious risk to the health and well-being of elderly patients. To improve and update clinical practice regarding the joint treatment of these two diseases, the common mechanisms of atherosclerosis and osteoporosis need to be clarified. MicroRNAs (miRNAs), are importance molecules in the pathogenesis of human diseases, including in cardiovascular and orthopedic fields. They have garnered interest as potential targets for novel therapeutic strategies. However, the key miRNAs involved in atherosclerosis and osteoporosis and their precise regulation mechanisms remain unknown. Paeonol (Pae), an active ingredient in Cortex Moutan, has shown promising results in improving both lipid and bone metabolic abnormalities. However, it is uncertain whether this agent can exert a cotherapeutic effect on atherosclerosis and osteoporosis.

OBJECTIVE

This study aimed to screen important shared miRNAs in atherosclerotic and osteoporotic complications, and explore the mechanism of the protective effects of Pae against atherosclerosis and osteoporosis in high-fat diet (HFD)-fed ApoE-/- mice.

METHODS

An experimental atherosclerosis and osteoporosis model was established in 40-week-old HFD ApoE-/- mice. Various techniques such as Oil Red O staining, HE staining and micro-CT were used to confirm the co-occurrence of these two diseases and efficacy of Pae in addition to the associated biochemical changes. Bioinformatics was used to screen key miRNAs in the atherosclerosis and osteoporosis model, and gene involvement was assessed through serum analyses, qRT-PCR, and western blot. To investigate the effect of Pae on the modulation of the miR let-7g/HMGA2/CEBPβ pathway, Raw 264.7 cells were cocultured with bone marrow mesenchymal stem cells (BMSCs) and treated with an miR let-7g mimic/inhibitor.

RESULTS

miR let-7g identified using bioinformatics was assessed to evaluate its participation in atherosclerosis-osteoporosis. Experimental analysis showed reduced miR let-7g levels in the atherosclerosis-osteoporosis mice model. Moreover, miR let-7g was required for BMSC - Raw 264.7 cell crosstalk, thereby promoting foam cell formation and adipocyte differentiation. Treatment with Pae significantly reduced plaque accumulation and foam cell number in the aorta while increasing bone density and improving trabecular bone microarchitecture in HFD ApoE-/- mice. Pae also increased the level of miR let-7g in the bloodstream of model mice. In vitro studies, Pae enhanced miR let-7g expression in BMSCs, thereby suppressing the HMGA2/CEBPβ pathway to prevent the formation of foam cells and differentiation of adipocytes induced by oxidized low-density lipoprotein (ox-LDL).

CONCLUSION

The study results suggested that miR let-7g participates in atherosclerosis -osteoporosis regulation and that Pae acts as a potential therapeutic agent for preventing atherosclerosis-osteoporosis through regulatory effects on the miR let-7g/HMGA2/CEBPβ pathway to hinder foam cell formation and adipocyte differentiation.

Effect of Calcium and Vitamin D Supplementation (Dairy vs. Pharmacological) on Bone Health of Underprivileged Indian Children and Youth with Type-1 Diabetes: A Randomized Controlled Trial

BACKGROUND

Bone health is affected by chronic childhood disorders including type-1 diabetes mellitus (T1DM). We conducted this randomized controlled trial with the objective of investigating the effect of 1-year supplementation of vitamin-D with milk or with pharmacological calcium on bone mass accrual in underprivileged Indian children and youth with T1DM.

METHODS

5 to 23year old (n = 203) underprivileged children and youth with T1DM were allocated to one of three groups: Milk (group A-received 200 ml milk + 1000 international unit (IU) vitamin-D3/day), Calcium supplement (group B-received 500 mg of calcium carbonate + 1000 IU of vitamin-D3/day) or standard of care/control (group C). Anthropometry, clinical details, biochemistry, diet (3-day 24-h recall), physical activity (questionnaires adapted for Indian children) and bone health parameters (using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography- DXA and pQCT respectively) were evaluated at enrolment and end of 12 month intervention.

RESULTS

Total body less head(TBLH) bone mineral content (BMC(g)) and bone mineral density (BMD(gm/cm2)) were significantly higher at end of study in girls in both supplemented groups (TBLHBMC-A-1011.8 ± 307.8, B-983.2 ± 352.9, C-792.8 ± 346.8. TBLHBMD-A-± 0.2, B-0.8 ± 0.2, C-0.6 ± 0.2, p < 0.05). Z score of lumbar spine bone mineral apparent density of supplemented participants of both sexes was significantly higher than controls (Boys- A-0.7 ± 1.1, B-0.6 ± 1.4, C- -0.7 ± 1.1; Girls- A-1.1 ± 1.1, B-0.9 ± 3.4, C- -1.7 ± 1.3, p < 0.05). A significantly higher percentage increase was found in cortical thickness in girls in both supplemented groups (A-17.9 ± 28.6, B-15.3 ± 16.5, C-7.6 ± 26.2); the differences remained after adjusting for confounders.

CONCLUSION

Supplementation with milk or pharmacological calcium (+vitaminD3) improved bone outcomes-particularly geometry in children with T1DM with more pronounced effect in girls. Pharmacological calcium may be more cost effective in optimising bone health in T1DM in resource limited settings.

Obesity, diabetes and risk of bone fragility: How BMAT behavior is affected by metabolic disturbances and its influence on bone health

PURPOSE

Osteoporosis is a metabolic bone disease characterized by decreased bone strength and mass, which predisposes patients to fractures and is associated with high morbidity and mortality. Like osteoporosis, obesity and diabetes are systemic metabolic diseases associated with modifiable risk factors and lifestyle, and their prevalence is increasing. They are related to decreased quality of life, functional loss and increased mortality, generating high costs for health systems and representing a worldwide public health problem. Growing evidence reinforces the role of bone marrow adipose tissue (BMAT) as an influential factor in the bone microenvironment and systemic metabolism. Given the impact of obesity and diabetes on metabolism and their possible effect on the bone microenvironment, changes in BMAT behavior may explain the risk of developing osteoporosis in the presence of these comorbidities.

METHODS

This study reviewed the scientific literature on the behavior of BMAT in pathological metabolic conditions, such as obesity and diabetes, and its potential involvement in the pathogenesis of bone fragility.

RESULTS

Published data strongly suggest a relationship between increased BMAT adiposity and the risk of bone fragility in the context of obesity and diabetes.

CONCLUSION

By secreting a broad range of factors, BMAT modulates the bone microenvironment and metabolism, ultimately affecting skeletal health. A better understanding of the relationship between BMAT expansion and metabolic disturbances observed in diabetic and obese patients will help to identify regulatory pathways and new targets for the treatment of bone-related diseases, with BMAT as a potential therapeutic target.

Mg-ZIF nanozyme regulates the switch between osteogenic and lipogenic differentiation in BMSCs via lipid metabolism

The accumulation of reactive oxygen species (ROS) within the bone marrow microenvironment leads to diminished osteogenic differentiation and heightened lipogenic differentiation of mesenchymal stem cells residing in the bone marrow, ultimately playing a role in the development of osteoporosis (OP). Mitigating ROS levels is a promising approach to counteracting OP. In this study, a nanozyme composed of magnesium-based zeolitic imidazolate frameworks (Mg-ZIF) was engineered to effectively scavenge ROS and alleviate OP. The results of this study indicate that Mg-ZIF exhibits significant potential in scavenging ROS and effectively promoting osteogenic differentiation of bone mesenchymal stem cells (BMSCs). Additionally, Mg-ZIF was found to inhibit the differentiation of BMSCs into adipose cells. In vivo experiments further confirmed the ability of Mg-ZIF to mitigate OP by reducing ROS levels. Mechanistically, Mg-ZIF enhances the differentiation of BMSCs into osteoblasts by upregulating lipid metabolic pathways through ROS scavenging. The results indicate that Mg-ZIF has potential as an effective therapeutic approach for the treatment of osteoporosis.

Comparative Analysis of Differentially Expressed Genes in Chondrocytes from Rats Exposed to Low Selenium and T-2 Toxin

The aim of this study was to construct rat models of environmental risk factors for Kashin-Beck disease (KBD) with low selenium and T-2 toxin levels and to screen the differentially expressed genes (DEGs) between the rat models exposed to environmental risk factors. The Se-deficient (SD) group and T-2 toxin exposure (T-2) group were constructed. Knee joint samples were stained with hematoxylin-eosin, and cartilage tissue damage was observed. Illumina high-throughput sequencing technology was used to detect the gene expression profiles of the rat models in each group. Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis were performed and five differential gene expression results were verified by quantitative real-time polymerase chain reaction (qRT‒PCR). A total of 124 DEGs were identified from the SD group, including 56 upregulated genes and 68 downregulated genes. A total of 135 DEGs were identified in the T-2 group, including 68 upregulated genes and 67 downregulated genes. The DEGs were significantly enriched in 4 KEGG pathways in the SD group and 9 KEGG pathways in the T-2 group. The expression levels of Dbp, Pc, Selenow, Rpl30, and Mt2A were consistent with the results of transcriptome sequencing by qRT‒PCR. The results of this study confirmed that there were some differences in DEGs between the SD group and the T-2 group and provided new evidence for further exploration of the etiology and pathogenesis of KBD.

Association of dietary carbohydrate and fiber ratio with postmenopausal bone mineral density and prevalence of osteoporosis: A cross-sectional study

BACKGROUND

This study aimed to investigate the associations of carbohydrate to dietary fiber ratio with bone mineral density (BMD) and the prevalence of osteoporosis in postmenopausal women.

METHODS

This cross-sectional study retrieved the data of 2829 postmenopausal women from the National Health and Nutrition Examination Survey (NHANES) database. Weighted univariable logistic regression models were used to investigate the correlations of carbohydrate, dietary fiber, or carbohydrate to fiber ratio with osteoporosis.

RESULTS

Higher dietary fiber intake was correlated with decreased odds ratio of osteoporosis [odds ratio(OR) = 0.96, 95% confidence interval (CI): 0.93 to 0.99]. The odds ratio of osteoporosis in postmenopausal women was elevated as the increase of carbohydrate to fiber ratio (OR = 1.80, 95%CI: 1.10 to 2.96). Carbohydrate to fiber ratio >17.09 was related to increased odds ratio of osteoporosis (OR = 1.63, 95%CI: 1.04 to 2.56). Compared to the carbohydrate to fiber ratio ≤11.59 group, carbohydrate to fiber ratio >17.09 was associated with decreased total femur BMD (β = -0.015, 95%CI: -0.028 to -0.001) and femur neck BMD (β = -0.020, 95%CI: -0.033 to -0.006) in postmenopausal women. The femur neck BMD in postmenopausal women was decreased with the increase of carbohydrate to fiber ratio (β = -0.015, 95%CI: -0.028 to -0.001).

CONCLUSION

In postmenopausal women, a high carbohydrate/fiber ratio >17.09 is associated with an increased risk of osteoporosis and lower hip BMD and high fiber intake is associated with less osteoporosis and higher hip BMD.

Chronic alcohol and nicotine consumption as catalyst for systemic inflammatory storm and bone destruction in apical periodontitis

AIM

To assess the periapical alveolar bone pattern and the serum levels of proinflammatory cytokines, biochemical markers and metabolites in rats subjected to chronic alcohol and nicotine consumption and induced apical periodontitis.

METHODOLOGY

Twenty-eight male Wistar rats were divided into four groups: Control, Alcohol, Nicotine and Alcohol+Nicotine. The alcohol groups were exposed to self-administration of a 25% alcohol solution, while the other groups were given only filtered water. The nicotine groups received daily intraperitoneal injections of a nicotine solution (0.19 μL of nicotine/mL), whereas the other groups received saline solution. Periapical lesions were induced by exposing the pulps of the left mandibular first molars for 28 days. After euthanasia, the mandibles were removed and the percentage bone volume, bone mineral density, trabecular thickness, trabecular separation and trabecular number of the periapical bone were measured using micro-computed tomography images. Serum samples were collected for analysis of proinflammatory cytokines (IL-1β, IL-4, IL-6 and TNF-α), biochemical and metabolomic analysis. Statistical analysis was performed with a significance level of 5%. Nonparametric data were analysed using the Kruskal-Wallis test followed by Dunn's test, while one-way anova followed by Tukey's test was performed for parametric data.

RESULTS

The groups exposed to alcohol or nicotine consumption exhibited an altered bone pattern indicating lower bone density and higher levels of IL-1β, IL-6 and TNF-α compared to the Control group (p < .05). Significant differences were observed among the groups in the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase, cholesterol, triglycerides, urea, creatinine, albumin, uric acid, bilirubin and calcium. Metabolomic analysis revealed significant differences in glycine, phosphocholine, lysine, lactate, valine, pyruvate and lipids (CH2 CH2 CO), n(CH2 ) and n(CH3 ). Most of these parameters were even more altered in the simultaneous consumption of both substances compared to single consumption.

CONCLUSION

Alcohol and nicotine chronic consumption altered several metabolic markers, impaired liver and kidney function, increased the production of systemic proinflammatory mediators and harmed the periapical bone microarchitecture in the presence of apical periodontitis. The simultaneous consumption of alcohol and nicotine intensified these detrimental effects.

Gut microbial community and fecal metabolomic signatures in different types of osteoporosis animal models

BACKGROUND

The gut microbiota (GM) constitutes a critical factor in the maintenance of physiological homeostasis. Numerous studies have empirically demonstrated that the GM is closely associated with the onset and progression of osteoporosis (OP). Nevertheless, the characteristics of the GM and its metabolites related to different forms of OP are poorly understood. In the present study, we examined the changes in the GM and its metabolites associated with various types of OP as well as the correlations among them.

METHODS

We simultaneously established rat postmenopausal, disuse-induced, and glucocorticoid-induced OP models. We used micro-CT and histological analyses to observe bone microstructure, three-point bending tests to measure bone strength, and enzyme-linked immunosorbent assay (ELISA) to evaluate the biochemical markers of bone turnover in the three rat OP models and the control. We applied 16s rDNA to analyze GM abundance and employed untargeted metabolomics to identify fecal metabolites in all four treatment groups. We implemented multi-omics methods to explore the relationships among OP, the GM, and its metabolites.

RESULTS

The 16S rDNA sequencing revealed that both the abundance and alterations of the GM significantly differed among the OP groups. In the postmenopausal OP model, the bacterial genera g__Bacteroidetes_unclassified, g__Firmicutes_unclassified, and g__Eggerthella had changed. In the disuse-induced and glucocorticoid-induced OP models, g__Akkermansia and g__Rothia changed, respectively. Untargeted metabolomics disclosed that the GM-derived metabolites significantly differed among the OP types. However, a Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that it was mainly metabolites implicated in lipid and amino acid metabolism that were altered in all cases. An association analysis indicated that the histidine metabolism intermediate 4-(β-acetylaminoethyl) imidazole was common to all OP forms and was strongly correlated with all bone metabolism-related bacterial genera. Hence, 4-(β-acetylaminoethyl) imidazole might play a vital role in OP onset and progression.

CONCLUSIONS

The present work revealed the alterations in the GM and its metabolites that are associated with OP. It also disclosed the changes in the GM that are characteristic of each type of OP. Future research should endeavor to determine the causal and regulatory effects of the GM and the metabolites typical of each form of OP.

Predicting fracture risk for elderly osteoporosis patients by hybrid machine learning model

Background and Objective

Osteoporotic fractures significantly impact individuals's quality of life and exert substantial pressure on the social pension system. This study aims to develop prediction models for osteoporotic fracture and uncover potential risk factors based on Electronic Health Records (EHR).

Methods

Data of patients with osteoporosis were extracted from the EHR of Xinhua Hospital (July 2012-October 2017). Demographic and clinical features were used to develop prediction models based on 12 independent machine learning (ML) algorithms and 3 hybrid ML models. To facilitate a nuanced interpretation of the results, a comprehensive importance score was conceived, incorporating various perspectives to effectively discern and mine critical features from the data.

Results

A total of 8530 patients with osteoporosis were included for analysis, of which 1090 cases (12.8%) were fracture patients. The hybrid model that synergistically combines the Support Vector Machine (SVM) and XGBoost algorithms demonstrated the best predictive performance in terms of accuracy and precision (above 90%) among all benchmark models. Blood Calcium, Alkaline phosphatase (ALP), C-reactive Protein (CRP), Apolipoprotein A/B ratio and High-density lipoprotein cholesterol (HDL-C) were statistically found to be associated with osteoporotic fracture.

Conclusions

The hybrid machine learning model can be a reliable tool for predicting the risk of fracture in patients with osteoporosis. It is expected to assist clinicians in identifying high-risk fracture patients and implementing early interventions.

Distinct Metabolites in Osteopenia and Osteoporosis: A Systematic Review and Meta-Analysis

Multiple studies have indicated that distinct metabolites are involved in the occurrence and development of osteopenia (ON) and osteoporosis (OP); however, these metabolites in OP and ON have not yet been classified and standardized. This systematic review and meta-analysis included 21 articles aiming to investigate the distinct metabolites in patients with ON and OP. The quality of the included articles was generally high; seventeen studies had >7 stars, and the remaining four received 6 stars. This systematic review showed that three metabolites (phosphatidylcholine (PC) (lipid metabolites), galactose (carbohydrate metabolites), and succinic acid (other metabolites)) increased, four (glycylglycine (gly-gly), cystine (amino acids), sphingomyelin (SM) (lipid metabolites) and glucose (carbohydrate metabolites)) decreased, and five (glutamine, hydroxyproline, taurine (amino acids), lysophosphatidylcholine (LPC) (lipid metabolites), and lactate (other metabolites)) had conflicting directions in OP/ON. The results of the meta-analysis show that gly-gly (MD = -0.77, 95%CI -1.43 to -0.11, p = 0.02) and cystine (MD = -5.52, 95%CI -7.35 to -3.68, p < 0.00001) decreased in the OP group compared with the healthy control group. Moreover, LPC (MD = 1.48, 95%CI 0.11 to 2.86, p = 0.03) increased in the OP group compared with the healthy control group. These results indicate that distinct metabolites were associated with ON and OP, which could be considered a predictor for OP.

Association between total cholesterol and lumbar bone density in Chinese: a study of physical examination data from 2018 to 2023

BACKGROUND

The impact of total cholesterol (TC) on lumbar bone mineral density (BMD) is a topic of interest. However, empirical evidence on this association from demographic surveys conducted in China is lacking. Therefore, this study aimed to examine the relationship between serum TC and lumbar BMD in a sample of 20,544 Chinese adults between the ages of 20 and 80 years over a period of 5 years, from February 2018 to February 2023. Thus, we investigated the effect of serum TC level on lumbar BMD and its relationship with bone reduction in a Chinese adult population.

METHODS

This cross-sectional study used data obtained from the Department of Health Management at Henan Provincial People's Hospital between February 2018 and February 2023. The aim of this study was to examine the correlation between serum TC and lumbar BMD in individuals of different sexes. The research methodology encompassed population description, analysis of stratification, single-factor and multiple-equation regression analyses, smooth curve fitting, and analysis of threshold and saturation effects. The R and EmpowerStats software packages were used for statistical analysis.

RESULTS

After adjusting for confounding variables, a multiple linear regression model revealed a significant correlation between TC and lumbar BMD in men. In subgroup analysis, serum TC was found to have a positive association with lumbar BMD in men, specifically those aged 45 years or older, with a body mass index (BMI) ranging from 24 to 28 kg/m2. A U-shaped correlation arose between serum TC and lumbar BMD was detected in women of different ages and BMI, the inflection point was 4.27 mmol/L for women aged ≥ 45 years and 4.35 mmol/L for women with a BMI of ≥ 28 kg/m2.

CONCLUSION

In this study, Chinese adults aged 20-80 years displayed different effects of serum TC on lumbar BMD in sex-specific populations. Therefore, monitoring BMI and serum TC levels in women of different ages could prevent osteoporosis and osteopenia.

TRIAL REGISTRATION

The research protocol was approved by the Ethics Committee of Beijing Jishuitan Hospital, in accordance with the Declaration of Helsinki guidelines (No. 2015-12-02). These data are part of the China Health Quantitative CT Big Data Research team, which has been registered at clinicaltrials.gov (code: NCT03699228).

Apolipoprotein E deficiency attenuated osteogenesis via down-regulating osterix

Apolipoprotein E (ApoE), a ligand for low-density lipoprotein receptors, is strongly induced during osteogenesis and has a physiologic role in regulating osteoblast function, but the mechanisms of its action are still unclear. The study aims to elucidate the influence and molecular mechanisms of ApoE on bone formation. An ovariectomy-induced osteoporotic model were conducted in ApoE knockout (ApoE-/-) mice to study the effect of ApoE on the bone system. Bone quality were assessed through bone mineral density and histomorphometric analysis. To investigate the underlying role and mechanisms of ApoE during osteogenesis, primary osteoblasts from the calvariums of newborn ApoE-/- or wild-type (WT) mice were cultured in the osteoblastic differentiation medium in vitro for further research. Our animal experiment data showed that ApoE-/- mice exhibited bone loss, exacerbated by estrogen deprivation after ovariectomy. ApoE deficiency attenuated osteoblast activity and inhibited osteoblast osteogenesis, accompanied by decreased osterix expression. ApoE deficiency did not affect primary osteoblast viability and collagen-1 expression. Moreover, osteoprotegerin expression in ApoE-/- osteoblasts was reduced compared to WT controls. Our study demonstrated that ApoE gene deficiency contributed to bone loss and attenuated osteogenesis by down-regulating osterix expression.

Regulation of cholesterol homeostasis in osteoporosis mechanisms and therapeutics

Osteoporosis is a metabolic bone disease that affects hundreds of millions of people worldwide and is characterized by excessive loss of bone protein and mineral content. The incidence and mortality of osteoporosis increase with age, creating a significant medical and economic burden globally. The importance of cholesterol levels has been reported in the development of diseases including osteoporosis. It is important to note that key enzymes and molecules involved in cholesterol homeostasis are closely related to bone formation. Excessive cholesterol may cause osteoporosis, cholesterol and its metabolites affect bone homeostasis by regulating the proliferation and stimulation of osteoblasts and osteoclasts. Therefore, antagonism of elevated cholesterol levels may be a potential strategy to prevent osteoporosis. There is sufficient evidence to support the use of bisphosphonates and statin drugs for osteoporosis in the clinic. Therefore, in view of the aggravation of the aging problem, we summarize the intracellular mechanism of cholesterol homeostasis and its relationship with osteoporosis (including cholesterol and cholesterol oxidation products (COPs) in osteoporosis). Furthermore, the current clinical cholesterol-lowering drugs for osteoporosis were also summarized, as are new and promising therapies (cell-based therapies (e.g., stem cells) and biomaterial-delivered target drug therapies for osteoporosis as well).

Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors and the Risk of Fracture: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Osteoporosis and hyperlipidemia are closely correlated and statins might be associated with a decreased risk of fracture. We aimed to investigate the association between proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) therapy and the risk of fracture. The PubMed, Cochrane library, and EMBASE databases were systematically searched from the inception dates to October 22, 2022. Randomized clinical trials (RCTs) that addressed to fracture events of participants using alirocumab, evolocumab, bococizumab or inclisiran, with a follow-up of ≥ 24 weeks were included. Meta-analyses were conducted to calculate the odds ratio (OR) with 95% confidence intervals (CIs) for major osteoporotic fracture, hip fracture, osteoporotic non-vertebral fracture, and total fracture. 30 trials assessing PCSK9i among 95, 911 adults were included. There were no significant associations between PCSK9i therapy and the risk of major osteoporotic fracture [OR 1.08 (95% Cl 0.87-1.34), p = 0.49], hip fracture [OR 1.05 (95% Cl 0.73-1.53), p = 0.79], osteoporotic non-vertebral fracture [OR 1.03 (95% Cl 0.80-1.32), p = 0.83], and total fracture [OR 1.03 (95% Cl 0.88-1.19), p = 0.74] over a period of 6-64 months. No significant associations were detected in any of the sensitivity analyses and subgroup analyses stratified by the type of PCSK9i, follow-up duration, age, sex, sample size, and patient profile. Pooled results of our meta-analysis showed that exposure to PCSK9i was not associated with reduced risks of fracture in the short term.

Structural characterization and anti-osteoporosis effects of polysaccharide purified from Eucommia ulmoides Oliver cortex based on its modulation on bone metabolism

EuOCP3, with a molecular weight of 38.1 kDa, is an acidic polysaccharide purified from Eucommia ulmoides Oliver cortex. Herein, we determined that the main backbone of EuOCP3 was predominantly composed of →4)-α-GalpA-(1 → 4)-α-GalpA-(1→, →4)-α-GalpA-(1 → 5)-α-Araf-(1→, →4)-α-GalpA-(1 → 2)-α-Rhap-(1→, and →4)-α-GalpA-(1 → 5)-α-Araf-(1 → 2)-α-Rhap-(1 → repeating blocks, which were connected by →2,3,5)-α-Araf-(1→. The side chains, substituted at C-2 and C-5 of →2,3,5)-α-Araf-(1→, contained T-β-Araf→ and T-β-Araf → 4)-α-GalpA-(1 → residues. In dexamethasone (Dex)-induced osteoporosis (OP) mice, EuOCP3 treatment restored cortical bone thickness, increased mineralized bone area, enhanced the number of osteoblasts, and decreased the number of osteoclasts on the surface of cortical bone. Combining analysis of gut microflora, serum metabolite profiles, and biological detection results, we demonstrated that EuOCP3 regulated the abundance of specific species within the gut microflora, such as g_Dorea and g_Prevotella, and ameliorated oxidative stress. In turn, enhancement of osteogenic function and restoration of bone metabolism via the extracellular signal-regulated kinase (ERK)/c-Jun N-terminal kinase (JNK)/nuclear factor erythroid-2 related factor 2 (Nrf2) signaling pathway was indicated. The current findings contribute to understanding the potential of EuOCP3 in anti-OP treatment.

Comparative pharyngeal cartilage developmental toxicity of bisphenol A, bisphenol S and bisphenol AF to zebrafish (Danio rerio) larvae: A combination of morphometry and global transcriptome analyses

Exposure to BPA is recently shown to affect cartilage development in teleost fishes; whether BPS and BPAF, its two most frequently used phenolic analogues have similar effect, however, remains unclear. Here, we utilize zebrafish (Danio rerio) as an in-vivo larval model for systematic comparison of the pharyngeal arch-derived cartilage developmental toxicity of BPA, BPS and BPAF. Zebrafish are continuously exposed to three bisphenol analogues (3-BPs) at a range of concentrations since the embryonic stage (0.5 hpf), and identified cartilage malformations of the mandibular and hyoid pharyngeal arches at larval stage (120 hpf). BPA and BPAF prolong length and broaden cartilage angles; however, BPS shortens length and narrows the angles of skull cartilages. The results of the comparative transcriptome show that FoxO and MAPK signaling pathways are closely associated with the toxicity of BPA and BPAF, while BPS exposure affects energy metabolism-related pathways. Moreover, exposure to 3-BPs have an impact on the oxidative stress status. Our data collectively indicate that BPS and BPAF may not be safer than BPA regarding the impact on pharyngeal cartilage development in fish model, the mechanisms still need explorations, and that these two analogues should be applied with caution.

The correlation between high-density lipoprotein cholesterol and bone mineral density in adolescents: a cross-sectional study

Recent studies have shown a correlation between high-density lipoprotein cholesterol (HDL-C) and bone mineral density (BMD) in adults, but their relationship is unclear in adolescents. This study aimed to explore whether a correlation existed between them among adolescents aged 12-19. Data analyzed in our study was fetched from the National Health and Nutrition Examination Survey (NHANES) database 2011-2018. The relationship between HDL-C level and total BMD value was analyzed by multivariate logistic regression models, fitted smoothing curves, and generalized additive models. 3770 participants participated in this analysis. After adjusting for all relevant covariates involved in this study, we found a negative correlation between HDL-C levels and total bone density in male adolescents.Furthermore, the stratified analysis showed that all covariables-adjusted models retained the negative correlation excepting female, black, or Mexican American subgroups. An inverted U-shaped curve represented the correlation of HDL-C and total BMD among adolescents aged 16 to 19, and the turning point was 1.06 mmol/L. After adjusting for all relevant covariates involved in this study, the study found a negative correlation between HDL-C levels and total BMD in male adolescents aged 12 to 19, particularly among those of races other than Black and Mexican. There was a saturation effect between HDL-C level and total BMD in 16-19-year-old adolescents. The turning point was 1.06 mmol/L. Therefore, HDL-C might be a biomarker to detect bone health and further perform a more detailed examination.

Reduced High-Density Lipoprotein Cholesterol Is an Independent Determinant of Altered Bone Quality in Women with Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is associated with an increased fracture risk. Our study aimed to explore differences in bone alterations between T2DM women and controls and to assess clinical predictors of bone impairment in T2DM. For this observational case control study, we recruited 126 T2DM female patients and 117 non-diabetic, age- and BMI-comparable women, who underwent clinical examination, routine biochemistry and dual-energy X-ray absorptiometry (DXA) scans for bone mineral density (BMD) and trabecular bone score (TBS) assessment-derived indexes. These were correlated to metabolic parameters, such as glycemic control and lipid profile, by bivariate analyses, and significant variables were entered in multivariate adjusted models to detect independent determinants of altered bone status in diabetes. The T2DM patients were less represented in the normal bone category compared with controls (5% vs. 12%; p = 0.04); T2DM was associated with low TBS (OR: 2.47, C.I. 95%: 1.19–5.16, p = 0.016) in a regression model adjusted for age, menopausal status and BMI. In women with T2DM, TBS directly correlated with plasma high-density lipoprotein cholesterol (HDL-c) (p = 0.029) and vitamin D (p = 0.017) levels. An inverse association was observed with menopausal status (p < 0.001), metabolic syndrome (p = 0.014), BMI (p = 0.005), and waist circumference (p < 0.001). In the multivariate regression analysis, lower HDL-c represented the main predictor of altered bone quality in T2DM, regardless of age, menopausal status, BMI, waist circumference, statin treatment, physical activity, and vitamin D (p = 0.029; R2 = 0.47), which likely underlies common pathways between metabolic disease and bone health in diabetes.

Role of Vitamin D in the diagnosis of acute Myeloid Leukemia

A range of hematological and biochemical markers have been investigated in Acute Myeloid Leukemia (AML) patients to determine the relationship between cancer growth and metabolic problems. This study aimed to determine the effects of vitamin D deficiency in Iraqi patients with acute myeloid leukemia who had recently been diagnosed. There was a significant inverse correlation between the total serum cholesterol (TC) level of acute myeloid leukemia (AML) patients group [(148.77±12.2) for males, (165.29±9.64) for females] and the control group [(164.50±7.26) for males, (180.05±7.31) for females], also an inverse correlation between high-density lipoprotein (HDL) level of acute myeloid leukemia (AML) patients group [(46.00±2.04) for males, (46.18±1.08) for females] and control group [(54.25±1.86) for males,(51.94±1.37) for females]. A significant difference was between the serum triglyceride (TG) level of acute myeloid leukemia (AML) patients group [(128.71±13.07) for males, (152.48±10.6) for females] and control group [85.12±11.30) for male, (90.50±10.90) for females], also between vitamin D level of acute myeloid leukemia (AML) patients group [(17.23±1.18) for males, (12.96±0.74) for females] and control group [(42.62±1.43) for males, (40.76±0.82) for females]. A statistically significant difference was between the serum calcium levels of individuals with acute myeloid leukemia [(8.99±0.32) for males, (8.91±0.23) for females] and the control group [(13.13±1.16) for males, (10.73±0.28) for females]. AML patients can benefit from vitamin D treatment, according to a pairwise analysis of receiver operating characteristic (ROC) curves. The above results are related to concluding that Vitamin D can be utilized as a diagnostic test for AML patients. Keywords; acute myeloid leukemia (AML), Hypereosinophilia, ROC curve, hypocholesterolemia, vitamin D.

Evaluation of the Association between Low-Density Lipoprotein (LDL) and All-Cause Mortality in Geriatric Patients with Hip Fractures: A Prospective Cohort Study of 339 Patients

BACKGROUND

Many factors affect the prognosis of hip fractures in the elderly. Some studies have suggested a direct or indirect association among serum lipid levels, osteoporosis, and hip fracture risk. LDL levels were found to have a statistically significant nonlinear U-shaped relationship with hip fracture risk. However, the relationship between serum LDL levels and the prognosis of patients with hip fractures remains unclear. Therefore, in this study, we assessed the influence of serum LDL levels on patient mortality over a long-term follow-up period.

METHODS

Elderly patients with hip fractures were screened between January 2015 and September 2019, and their demographic and clinical characteristics were collected. Linear and nonlinear multivariate Cox regression models were used to identify the association between LDL levels and mortality. Analyses were performed using Empower Stats and R software.

RESULTS

Overall, 339 patients with a mean follow-up period of 34.17 months were included in this study. Ninety-nine patients (29.20%) died due to all-cause mortality. Linear multivariate Cox regression models showed that LDL levels were associated with mortality (HR = 0.69, 95%CI: 0.53, 0.91, p = 0.0085) after adjusting for confounding factors. However, the linear association was unstable, and nonlinearity was identified. An LDL concentration of 2.31 mmol/L was defined as the inflection point for prediction. A LDL level < 2.31 mmol/L was associated with mortality (HR = 0.42, 95%CI: 0.25, 0.69, p = 0.0006), whereas LDL > 2.31 mmol/L was not a risk factor for mortality (HR = 1.06, 95%CI: 0.70, 1.63, p = 0.7722).

CONCLUSIONS

The preoperative LDL level was nonlinearly associated with mortality in elderly patients with hip fractures, and the LDL level was a risk indicator of mortality. Furthermore, 2.31 mmol/L could be considered a predictor cut-off for risk.

Association between total cholesterol and total bone mineral density in US adults: National Health and Nutrition Examination Survey (NHANES), 2011-2018

BACKGROUND

Accumulated evidence indicates that cholesterol is offensive to bone metabolism. Therefore, we examined the real-world study among total cholesterol and total bone mineral density (BMD). We investigated the relationship between total cholesterol and total BMD among 10,039 US participants aged 20-59 years old over the period 2011-2018 from the NHANES.

METHODS

To analyze the relationship among total cholesterol and total BMD, multivariate linear regression models were used. Fitted smoothing curves, generalized additive models, and threshold effect analysis were also conducted.

RESULTS

After adjusting for additional covariates, weighted multivariable linear regression models indicated total cholesterol concentration levels exhibited a negative relationship with total BMD, particularly among participants aged 20-29 years. Concerning subgroup analysis, stratified by gender, race/ethnicity and age group, the negative correlation of total cholesterol with total BMD dwelled in both female and male as well as in whites and other races (including Hispanic and Multi-Racial), but not in non-Hispanic blacks and Mexican American. In other races, this relationship presented a nonlinear association (inflection point: 6.7 mmol/L) with a U-shaped curve. Among participants aged 40 to 49 years, this relationship also followed a nonlinear association (inflection point: 5.84 mmol/L), indicating a saturation effect. Moreover, the three types of diabetes status were found to have negative, U-shaped, and positive relationships. In participants with borderline diabetes status, the relationship of total cholesterol with total BMD was a U-shaped curve (inflection point: 4.65 mmol/L).

CONCLUSIONS

For US young adults (20-29 years old), our study revealed a negative relationship between total cholesterol and total BMD. This association followed a U-shaped curve (inflection point: 4.65 mmol/L) in borderline diabetes status participants, a saturation curve (inflection point: 5.84 mmol/L) in participants aged 40-49 years and a nonlinear curve (inflection point: 6.7 mmol/L) in other races (including Hispanic and Multi-Racial). Therefore, keeping total cholesterol concentration at a reasonable level for young adults and diabetic population might be an approach to prevent osteoporosis or osteopenia.

Relationship of idiopathic femoral head necrosis with blood lipid metabolism and coagulation function: A propensity score-based analysis

Background

Nontraumatic osteonecrosis of the femoral head (ONFH) can be corticosteroid-induced, alcohol-induced, and idiopathic ONFH (IONFH). Although corticosteroid- and alcohol-induced ONFH has been investigated extensively regarding its relationship with blood lipids and coagulation factor levels. However, the effect of blood lipid metabolism and coagulation function on IONFH has rarely been studied. Therefore, this study aimed to analyse the relationship of IONFH with blood lipid and coagulation indicators.

Methods

Total 680 patients diagnosed with IONFH in our institution during January 2011-June 2019 who met the inclusion criteria composed the case group; 613 healthy persons who underwent physical examination at our institution during the same period composed the control group. Propensity scores were used for baseline feature matching, and two matching groups each with 450 patients were established. After the matching, blood lipid and coagulation factor levels of both groups were comparatively analysed.

Results

The case group showed significantly higher total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) levels, low-density/high-density lipoprotein (LDL/HDL) ratio, and apolipoprotein B (Apo-B) levels than the control group (p < 0.05). Conversely, the HDL and apolipoprotein A (Apo-AI) levels in the case group were significantly lower than those in the control group (p < 0.05). Regarding coagulation indicators, the activated partial thromboplastin time and prothrombin time were lower in the case group than in the control group; however, the differences were insignificant (p > 0.05). Furthermore, fibrinogen (FIB) levels and thrombin time (TT) in the case group were higher than those in the control group. There were significant differences between the two groups only in terms of FIB levels (p < 0.05), while TT was not significantly different (p > 0.05).

Conclusions

IONFH has strong associations with blood lipid metabolism and coagulation function, which provide an avenue for exploring the mechanism of IONFH.

Lipidomics Profiling of Patients with Low Bone Mineral Density (LBMD)

The relationship between lipid metabolism and bone mineral density (BMD) is still not fully elucidated. Despite the presence of investigations using osteoporotic animal models, clinical studies in humans are limited. In this work, untargeted lipidomics profiling using liquid chromatography-mass spectrometry (LC-MS) analysis of human serum samples was performed to identify the lipidomics profile associated with low bone mineral density (LBMD), with a subsequent examination of potential biomarkers related to OP risk prediction or progression. A total of 69 participants were recruited for this cohort study, including the osteoporotic group (OP, n = 25), osteopenia group (ON, n = 22), and control (Ctrl, n = 22). The LBMD group included OP and ON patients. The lipidomics effect of confounding factors such as age, gender, lipid profile, body mass index (BMD), chronic diseases, and medications was excluded from the dataset. The results showed a clear group separation and clustering between LBMD and Ctrl (Q² = 0.944, R² = 0.991), indicating a significant difference in the lipids profile. In addition, 322 putatively identified lipid molecules were dysregulated, with 163 up- and 159 down-regulated in LBMD, compared with the Ctrl. The most significantly dysregulated subclasses were phosphatidylcholines (PC) (n = 81, 25.16% of all dysregulated lipids 322), followed by triacylglycerol (TG) (n = 65, 20.19%), and then phosphatidylethanolamine (PE) (n = 40, 12.42%). In addition, groups of glycerophospholipids, including LPC (7.45%), LPE (5.59%), and PI (2.48%) were also dysregulated as of LBMD. These findings provide insights into the lipidomics alteration involved in bone remodeling and LBMD. and may drive the development of therapeutic targets and nutritional strategies for OP management.

7-Ketocholesterol Induces Oxiapoptophagy and Inhibits Osteogenic Differentiation in MC3T3-E1 Cells

7-Ketocholesterol (7KC) is one of the oxysterols produced by the auto-oxidation of cholesterol during the dysregulation of cholesterol metabolism which has been implicated in the pathological development of osteoporosis (OP). Oxiapoptophagy involving oxidative stress, autophagy, and apoptosis can be induced by 7KC. However, whether 7KC produces negative effects on MC3T3-E1 cells by stimulating oxiapoptophagy is still unclear. In the current study, 7KC was found to significantly decrease the cell viability of MC3T3-E1 cells in a concentration-dependent manner. In addition, 7KC decreased ALP staining and mineralization and down-regulated the protein expression of OPN and RUNX2, inhibiting osteogenic differentiation. 7KC significantly stimulated oxidation and induced autophagy and apoptosis in the cultured MC3T3-E1 cells. Pretreatment with the anti-oxidant acetylcysteine (NAC) could effectively decrease NOX4 and MDA production, enhance SOD activity, ameliorate the expression of autophagy-related factors, decrease apoptotic protein expression, and increase ALP, OPN, and RUNX2 expression, compromising 7KC-induced oxiapoptophagy and osteogenic differentiation inhibition in MC3T3-E1 cells. In summary, 7KC may induce oxiapoptophagy and inhibit osteogenic differentiation in the pathological development of OP.

The Association of Lipids and Lipoproteins with Hip Fracture Risk: The Cardiovascular Health Study

BACKGROUND

It is uncertain if lipids or lipoproteins are associated with osteoporotic fractures. In this study, incident hip fracture risk according to conventional lipid levels and lipoprotein levels and sizes was examined.

METHODS

We followed 5832 participants aged ≥65 years from the Cardiovascular Health Study for hip fracture for a mean of 13.5 (SD 5.7) years. Standard enzymatic methods were used to determine lipid levels (ie, high-density lipoprotein-cholesterol [HDL-c], low-density lipoprotein-cholesterol [LDL-c], and triglycerides). Nuclear magnetic resonance spectroscopy was used to measure lipoprotein fractions (ie, very-low-density lipoprotein-particle [VLDL-P], low-density lipoprotein-particle [LDL-P], high-density lipoprotein-particle [HDL-P]) in a subset of 1849 participants.

RESULTS

We documented 755 incident hip fractures among women (1.19 fractures per 100 participant years [95% confidence interval, 1.04, 1.35]) and 197 among men (0.67 fractures per 100 participant years [95% CI, 0.41, 1.10]) over an average follow-up. HDL-c and LDL-c levels had statistically significant nonlinear U-shaped relationships with hip fracture risk (HDL-c, P = .009; LDL-c, P = .02). Triglyceride levels were not significantly associated with hip fracture risk. In fully adjusted conjoint models, higher VLDL-P concentration (hazard ratio [HR] per 1 standard deviation [SD] increment 1.47 [1.13, 1.91] and size [HR per 1 SD increment 1.24 [1.05, 1.46]) and higher high-density lipoprotein particle size (HR per 1 SD increment 1.81 [1.25, 2.62]) were all associated with higher hip fracture risk.

CONCLUSIONS

Lipids and lipoproteins are associated with hip fracture risk in older adults. The associations are complex. Mechanistic studies are needed to understand these findings.

Asiatic acid improves high-fat-diet-induced osteoporosis in mice via regulating SIRT1/FOXO1 signaling and inhibiting oxidative stress

Asiatic acid can attenuate osteoporosis through suppressing adipogenic differentiation and osteoclastic differentiation. Oxidative stress enhances osteoclastic differentiation but represses osteogenic differentiation to promote osteoporosis. However, the role and mechanism of asiatic acid in osteoporosis have not been reported. Firstly, mice were fed with high-fat-diet (HFD) with or without asiatic acid for 16 weeks. Data from an automatic biochemical analyzer showed that HFD induced down-regulation of high-density lipoprotein (HDL) and an increase of serum levels of triglyceride (TG), total cholesterol (TC) and low-density lipoprotein (LDL). However, asiatic acid administration attenuated the decrease of HDL and increase of serum TG, TC and LDL in osteoporotic mice. Secondly, HFD induced high levels of malondialdehyde (MDA) and reactive oxygen species (ROS), low levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in osteoporotic mice. However, the levels of MDA, ROS, SOD and GSH-Px in osteoporotic mice were reversed by asiatic acid administration. (this section is unclear and requires revision) Asiatic acid administration reduced expression of c-telopeptide of type 1 collagen (CTX-1), enhanced alkaline phosphatase (ALP) and procollagen type 1 N-terminal propeptide (P1NP) in HFD-induced osteoporotic mice. (this section is unclear and requires revision) Thirdly, asiatic acid promoted calcium deposition in bone marrow cells and osteogenic differentiation in osteoporotic mice, but decreased ALP in bone marrow cells. Lastly, asiatic acid enhanced SIRT1 and nuclear FOXO1 (Nu-FOXO1) expression, while it reduced Acetyl FOXO1 (Ac-FOXO1) in osteoporotic mice. In conclusion, asiatic acid might inhibit oxidative stress and promote osteogenic differentiation through activating SIRT1/FOXO1 to attenuate HFD-induced osteoporosis in mice.

MicroRNA‑141 inhibits the differentiation of bone marrow‑derived mesenchymal stem cells in steroid‑induced osteonecrosis via E2F3

Osteonecrosis of the femoral head (ONFH) affects the life of patients. MicroRNA-141 (miR-141) has been found associated with proliferation of bone marrow-derived mesenchymal stem cells (BMSCs). E2F transcription factor 3 (E2F3) has been identified as the target of miR-141 to regulate cell proliferation. The aim of the present study was to investigate whether miR-141 and E2F3 were involved in the osteogenic differentiation of BMSCs during ONFH. BMSCs from 4-week-old Sprague-Dawley rats were transduced with miR-141 mimic or inhibitor lentiviruses. Alkaline phosphatase staining was performed to confirm osteogenic differentiation. Reverse transcription-quantitative PCR, luciferase reporter assays and western blot analysis were also used to examine the interaction between E2F3 and miR-141 in BMSCs from the control and ONFH rats. The lentiviral transductions were carried out successfully. The mRNA expression levels of miR-141 in ONFH were upregulated, while those of E2F3 were downregulated compared with the control rat. The luciferase reporter assays indicated that miR-141 could target E2F3. miR-141 knockdown upregulated the mRNA expression levels of E2F3. In addition, osteogenic differentiation of BMSCs was inhibited following miR-141 overexpression, but increased following miR-141 knockdown, as evidenced by the results of the alkaline phosphatase staining and western blot analysis. In conclusion, miR-141 inhibits the osteogenic differentiation of BMSCs in ONFH by targeting E2F3. These two molecules may represent novel candidates to examine in order to investigate the mechanism underlying ONFH.

Integration of the Human Gut Microbiome and Serum Metabolome Reveals Novel Biological Factors Involved in the Regulation of Bone Mineral Density

While the gut microbiome has been reported to play a role in bone metabolism, the individual species and underlying functional mechanisms have not yet been characterized. We conducted a systematic multi-omics analysis using paired metagenomic and untargeted serum metabolomic profiles from a large sample of 499 peri- and early post-menopausal women to identify the potential crosstalk between these biological factors which may be involved in the regulation of bone mineral density (BMD). Single omics association analyses identified 22 bacteria species and 17 serum metabolites for putative association with BMD. Among the identified bacteria, Bacteroidetes and Fusobacteria were negatively associated, while Firmicutes were positively associated. Several of the identified serum metabolites including 3-phenylpropanoic acid, mainly derived from dietary polyphenols, and glycolithocholic acid, a secondary bile acid, are metabolic byproducts of the microbiota. We further conducted a supervised integrative feature selection with respect to BMD and constructed the inter-omics partial correlation network. Although still requiring replication and validation in future studies, the findings from this exploratory analysis provide novel insights into the interrelationships between the gut microbiome and serum metabolome that may potentially play a role in skeletal remodeling processes.

Positive association between high-density lipoprotein cholesterol and bone mineral density in U.S. adults: the NHANES 2011-2018

Background

Serum lipids are highly inheritable and play a major role in bone health. However, the relationship between high-density lipoprotein cholesterol (HDL-C) and bone mineral density (BMD) remains uncertain. The goal of this study was to see if there was a link between HDL-C levels and BMD in persons aged 20–59.

Methods

Multivariate logistic regression models were used to determine the link between HDL-C and lumbar BMD using data from the National Health and Nutrition Examination Survey (NHANES) 2011–2018. Generalized additive models and fitted smoothing curves were also used.

Results

The analysis included a total of 10,635 adults. After controlling for various variables, we discovered that HDL-C was positively linked with lumbar BMD. The favorable connection of HDL-C with lumbar BMD was maintained in subgroup analyses stratified by sex and race in women, but not in men, and in blacks, but not in whites. The relationship between HDL-C and lumbar BMD in men and whites was a U-shaped curve with the same inflection point: 0.98 mmol/L.

Conclusions

In people aged 20 to 59, our research discovered a positive relationship among HDL-C and lumbar BMD. Among males and whites, this relationship followed a U-shaped curve (inflection point: 0.98 mmol/L). HDL-C measurement might be used as a responsive biomarker for detecting osteoporosis early and guiding therapy.

High Low-Density Lipoprotein Cholesterol Levels are Associated with Osteoporosis Among Adults 20–59 Years of Age

Background

Serum lipids are highly inheritable and play a major role in bone health. However, the relationship between low-density lipoprotein cholesterol (LDL-C) and bone mineral density (BMD) remains uncertain. The goal of this study was to see if there was a link between LDL-C levels and BMD in persons aged 20 to 59.

Methods

Using data from the National Health and Nutrition Examination Survey (NHANES) 2011–2018, multivariate logistic regression models were utilized to investigate the association between LDL-C and lumbar BMD. Fitted smoothing curves and generalized additive models were also used.

Results

The analysis included a total of 4909 adults. After controlling for various variables, we discovered that LDL-C was negatively linked with lumbar BMD. The favorable connection of LDL-C with lumbar BMD was maintained in subgroup analyses stratified by gender and race in both males and females, Whites and Mexican Americans, but not in Blacks and other races. The relationship between LDL-C and lumbar BMD in other races was an inverted U-shaped curve with the inflection point: 2.327 (mmol/L).

Conclusion

In people aged 20 to 59, our research discovered a negative relationship among LDL-C and lumbar BMD. Among races other than Whites, Blacks, Mexican Americans, this relationship followed an inverted U-shaped curve (inflection point: 2.327mmol/L). LDL-C measurement might be used as a responsive biomarker for detecting osteoporosis early and guiding therapy.

Bone Health in Patients with Dyslipidemias: An Underestimated Aspect

Beyond being aging-related diseases, atherosclerosis and osteoporosis share common pathogenetic pathways implicated in bone and vascular mineralization. However, the contributory role of dyslipidemia in this interplay is less documented. The purpose of this narrative review is to provide epidemiological evidence regarding the prevalence of bone disease (osteoporosis, fracture risk) in patients with dyslipidemias and to discuss potential common pathophysiological mechanisms linking osteoporosis and atherosclerosis. The effect of hypolipidemic therapy on bone metabolism is also discussed. Despite the high data heterogeneity and the variable quality of studies, dyslipidemia, mainly elevated total and low-density lipoprotein cholesterol concentrations, is associated with low bone mass and increased fracture risk. This effect may be mediated directly by the increased oxidative stress and systemic inflammation associated with dyslipidemia, leading to increased osteoclastic activity and reduced bone formation. Moreover, factors such as estrogen, vitamin D and K deficiency, and increased concentrations of parathyroid hormone, homocysteine and lipid oxidation products, can also contribute. Regarding the effect of hypolipidemic medications on bone metabolism, statins may slightly increase BMD and reduce fracture risk, although the evidence is not robust, as it is for omega-3 fatty acids. No evidence exists for the effects of ezetimibe, fibrates, and niacin. In any case, more prospective studies are needed further to elucidate the association between lipids and bone strength.

Folic Acid Attenuates High-Fat Diet-Induced Osteoporosis Through the AMPK Signaling Pathway

Objective: Obesity caused by a high-fat diet (HFD) will expand adipose tissue and cause chronic low-grade systemic inflammation, leading to osteoporosis. Folic acid (FA) is a water-soluble vitamin that plays an essential role in regulating blood lipids and antioxidants. However, the effects and underlying mechanisms of FA in osteoporosis induced by an HFD remain poorly understood. This study aimed to investigate the effect of FA on bone health by using HFD-induced osteoporosis mice. Materials and Methods: Mice were fed a normal diet, HFD or an HFD supplemented with FA (20 μg/ml in drinking water) for 16 weeks. Throughout the 16 weeks study period, the rats were weighed once every week. GTT, ITT and lipid indexes were detected to evaluate the effects of FA on lipid metabolism in the HFD-fed mice. Morphological and structural changes of the femur and tibial bone were observed using micro-CT, HE staining and bone conversion parameters. The expression of MDA, SOD and inflammatory factors were detected to evaluate the effects of FA on oxidative stress and inflammatory response in the HFD-fed mice. Quantitative real-time PCR and Western blot (WB) were used to investigate the AMPK signaling pathway. Results: After the intervention of FA, the body fat rate of obese mice was reduced, and related metabolic disorders such as insulin resistance, hyperlipidemia, and systemic inflammation were alleviated. In correlation with those modifications, FA attenuated bone loss and improved bone microarchitecture, accompanied the number of osteoclasts and adipocytes decreased. Furthermore, FA promoted the phosphorylation of AMPK, thereby promoting the expression of Carnitine palmitoyltransferase 1 (CPT1), nuclear factor erythroid-2 related factor 2 (Nrf2) and antioxidant enzymes. Conclusion: These findings suggest that FA may modulate lipid metabolism and oxidative stress responses activating the AMPK signaling pathway, thereby alleviating HFD-induced osteoporosis. The results from our study provide experimental evidence to prevent HFD-induced osteoporosis.

Lipid metabolism within the bone micro-environment is closely associated with bone metabolism in physiological and pathophysiological stages

Recent advances in society have resulted in the emergence of both hyperlipidemia and obesity as life-threatening conditions in people with implications for various types of diseases, such as cardiovascular diseases and cancer. This is further complicated by a global rise in the aging population, especially menopausal women, who mostly suffer from overweight and bone loss simultaneously. Interestingly, clinical observations in these women suggest that osteoarthritis may be linked to a higher body mass index (BMI), which has led many to believe that there may be some degree of bone dysfunction associated with conditions such as obesity. It is also common practice in many outpatient settings to encourage patients to control their BMI and lose weight in an attempt to mitigate mechanical stress and thus reduce bone pain and joint dysfunction. Together, studies show that bone is not only a mechanical organ but also a critical component of metabolism, and various endocrine functions, such as calcium metabolism. Numerous studies have demonstrated a relationship between metabolic dysfunction in bone and abnormal lipid metabolism. Previous studies have also regarded obesity as a metabolic disorder. However, the relationship between lipid metabolism and bone metabolism has not been fully elucidated. In this narrative review, the data describing the close relationship between bone and lipid metabolism was summarized and the impact on both the normal physiology and pathophysiology of these tissues was discussed at both the molecular and cellular levels.

Effects of highly selective sensory/motor nerve injury on bone metabolism and bone remodeling in rats

OBJECTIVES

This work aimed to investigate the mechanism of selective sensory/motor nerve injury in affecting bone metabolism and remodeling.

METHODS

The selective sensory/motor nerve injury rat model was constructed through posterior rhizotomy (PRG), anterior rhizotomy (ARG), or anterior combined with posterior rhizotomy (APRG) at the L_4-6 sensory/motor nerves on the right side of rats. Sham-operated (SOG) rats served as control. At 8 weeks after surgery, the sciatic nerves, spinal cord segments L₅ and tibial tissues were collected for analysis.

RESULTS

the integrity of trabecular bone was damaged, the number of trabecular bone was decreased and the number of osteoclasts were increased in ARG group. ARG activated NF-κβ and PPAR-γ pathways, and inhibited Wnt/β-catenin pathway. ARG group exhibited high turnover bone metabolism. In PRG group, the trabecular bone morphology became thinner, and the number of osteoclasts was increased. NF-κβ pathway was activated and OPG/RANKL ratio was decreased in PRG group. The activated osteoclasts, reduced osteoblasts activity and lower turnover bone metabolism were observed in PRG group. Additionally, the bone metabolism in APRG group was similar to ARG group.

CONCLUSION

The posterior rhizotomy and anterior rhizotomy induced the different degree of osteoporosis in rats, which may attribute to regulate Wnt/β-catenin, NF-κβ and PPAR-γ signalling pathways.

Adipose Tissue Dysfunction: Impact on Bone and Osseointegration

Bone metabolism may be adversely affected in metabolic diseases such as obesity and metabolic syndrome, which are characterised by weight gain, due to the expansion of adipose tissue deposits. As an important regulator of energy metabolism, adipose tissues synthesise and secrete several key regulatory adipokines that influence a range of metabolic functions. This narrative review outlines the evidence for the mechanisms by which adipose tissue dysfunction may alter bone metabolism prior to the development of frank hyperglycaemia and presents the emerging evidence for the impact of diet-induced expansion of adipose tissue on implant osseointegration. Successful osseointegration requires normal bone cell function, and the expansion of adipose tissue deposits results in dysregulated adipokine production favouring an increase in pro-inflammatory adipokines, contributing to the development of a chronic inflammatory state and insulin resistance. The increase in inflammatory cytokines promotes the growth and differentiation of osteoclasts indirectly through the modulation of osteoblastic RANKL production and directly by reducing osteoclast apoptosis and increased osteoclastic expression of RANK. Conversely, the suppression of osteoblastic regulatory genes results in reduced osteoblast numbers and function contributing to compromised bone turnover. Compromised osseointegration has been established in hyperglycaemia; however, as discussed in this review, it may not be the only driver of altered bone metabolism. The incidence of metabolic disease in the community is rising, patients may present for implant treatment with undiagnosed, underlying changes to bone cell metabolism due to adipose tissue dysmetabolism.

Metabolomic biomarkers of low BMD: a systematic review

Due to the metabolic nature of osteoporosis, this study was conducted to identify metabolomic studies investigating the metabolic profile of low bone mineral density (BMD) and osteoporosis. A comprehensive systematic literature search was conducted through PubMed, Web of Science, Scopus, and Embase databases up to April 08, 2020, to identify observational studies with cross-sectional or case-control designs investigating the metabolic profile of low BMD in adults using biofluid specimen via metabolomic platform. The quality assessment panel specified for the "omics"-based diagnostic research (QUADOMICS) tool was used to estimate the methodologic quality of the included studies. Ten untargeted and one targeted approach metabolomic studies investigating biomarkers in different biofluids through mass spectrometry or nuclear magnetic resonance platforms were included in the systematic review. Some metabolite panels, rather than individual metabolites, showed promising results in differentiating low BMD from normal. Candidate metabolites were of different categories including amino acids, followed by lipids and carbohydrates. Besides, certain pathways were suggested by some of the studies to be involved. This systematic review suggested that metabolic profiling could improve the diagnosis of low BMD. Despite valuable findings attained from each of these studies, there was great heterogeneity regarding the ethnicity and age of participants, samples, and the metabolomic platform. Further longitudinal studies are needed to validate the results and confirm the predictive role of metabolic profile on low BMD and fracture. It is also mandatory to address and minimize the heterogeneity in future studies by using reliable quantitative methods. Summary: Due to the metabolic nature of osteoporosis, researchers have considered metabolomic studies recently. This systematic review showed that metabolic profiling including different categories of metabolites could improve the diagnosis of low BMD. However, great heterogeneity was observed and it is mandatory to address and minimize the heterogeneity in future studies.

Lipid Metabolism, Disorders and Therapeutic Drugs - Review

Different lifestyles have an impact on useful metabolic functions, causing disorders. Different lipids are involved in the metabolic functions that play various vital roles in the body, such as structural components, storage of energy, in signaling, as biomarkers, in energy metabolism, and as hormones. Inter-related disorders are caused when these functions are affected, like diabetes, cancer, infections, and inflammatory and neurodegenerative conditions in humans. During the Covid-19 period, there has been a lot of focus on the effects of metabolic disorders all over the world. Hence, this review collectively reports on research concerning metabolic disorders, mainly cardiovascular and diabetes mellitus. In addition, drug research in lipid metabolism disorders have also been considered. This review explores lipids, metabolism, lipid metabolism disorders, and drugs used for these disorders.

Metabolomic analysis to elucidate the change of the n-3 polyunsaturated fatty acids in senescent osteoblasts

Senile osteoporosis is a major public health concern, and yet, effective treatment methods do not exist. Herein, we used metabolomics to analyze the change of n-3 polyunsaturated fatty acids (PUFA) in senescent osteoblasts. We found that with an increase in the number of passages, the osteoblasts proliferative ability, alkaline phosphatase activity, and expression levels of bone metabolism genes decreased, the expression levels of aging-related genes increased, the damage caused by oxidative stress became more severe. Furthermore, levels of n-3 PUFA family members were downregulated in passage 10 than in passage 3 osteoblasts. These findings indicated that multiple passages led to more severe oxidative stress damage in senescent osteoblasts, which could be related to a decrease in n-3 PUFA levels. We believe that unsaturated fatty acid metabolism is a key factor involved in osteoblast senescence and that a proper dietary intake of n-3 PUFA may delay the occurrence senile osteoporosis.

High-density Lipoprotein Cholesterol Is Negatively Correlated with Bone Mineral Density and Has Potential Predictive Value for Bone Loss

Background

Many studies have shown that lipids play important roles in bone metabolism. However, the association between high-density lipoprotein cholesterol (HDL-C) and bone mineral density (BMD) is unclear. Therefore, this study aimed to investigate the linear or nonlinear relation between HDL-C levels and BMD and addressed whether the HDL-C levels had the potential values for predicting the risk of osteoporosis or osteopenia.

Methods

Two researchers independently extracted all information from the National Health and Nutrition Examination Survey (NHANES) database. Participants over 20 years of age with available HDL-C and BMD data were enrolled in the final analysis. The linear relationship between HDL-C levels and BMD was assessed using multivariate linear regression models. Moreover, the nonlinear relationship was also characterized by fitted smoothing curves and generalized additive models. In addition, the odds ratio (OR) for osteopenia and osteoporosis was evaluated with multiple logistic regression models.

Results

The weighted multivariable linear regression models demonstrated that HDL-C levels displayed an inverse association with BMD, especially among females and subjects aged 30 to 39 or 50 to 59. Moreover, the nonlinear relationship characterized by smooth curve fittings and generalized additive models suggested that (i) HDL-C levels displayed an inverted U-shaped relationship with BMD among women 30 to 39 or over 60 years of age; (ii) HDL-C levels exhibited a U-shaped association with BMD among women 20 to 29 or 50 to 59 years of age. In addition, females with high HDL levels (62-139 mg/dL) had an increased risk of osteopenia or osteoporosis.

Conclusion

This study demonstrated that HDL-C levels exhibit an inverse correlation with BMD. Especially in females, clinicians need to be alert to patients with high HDL-C levels, which may indicate an increased risk of osteoporosis or osteopenia. For these patients, close monitoring of BMD and early intervention may be necessary.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01497-7.

Identification and Functional Characterization of Metabolites for Bone Mass in Peri- and Postmenopausal Chinese Women

CONTEXT

Although metabolic profiles appear to play an important role in menopausal bone loss, the functional mechanisms by which metabolites influence bone mineral density (BMD) during menopause are largely unknown.

OBJECTIVE

We aimed to systematically identify metabolites associated with BMD variation and their potential functional mechanisms in peri- and postmenopausal women.

DESIGN AND METHODS

We performed serum metabolomic profiling and whole-genome sequencing for 517 perimenopausal (16%) and early postmenopausal (84%) women aged 41 to 64 years in this cross-sectional study. Partial least squares regression and general linear regression analysis were applied to identify BMD-associated metabolites, and weighted gene co-expression network analysis was performed to construct co-functional metabolite modules. Furthermore, we performed Mendelian randomization analysis to identify causal relationships between BMD-associated metabolites and BMD variation. Finally, we explored the effects of a novel prominent BMD-associated metabolite on bone metabolism through both in vivo/in vitro experiments.

RESULTS

Twenty metabolites and a co-functional metabolite module (consisting of fatty acids) were significantly associated with BMD variation. We found dodecanoic acid (DA), within the identified module causally decreased total hip BMD. Subsequently, the in vivo experiments might support that dietary supplementation with DA could promote bone loss, as well as increase the osteoblast and osteoclast numbers in normal/ovariectomized mice. Dodecanoic acid treatment differentially promoted osteoblast and osteoclast differentiation, especially for osteoclast differentiation at higher concentrations in vitro (eg,10, 100 μM).

CONCLUSIONS

This study sheds light on metabolomic profiles associated with postmenopausal osteoporosis risk, highlighting the potential importance of fatty acids, as exemplified by DA, in regulating BMD.

The role of statins in the differentiation and function of bone cells

BACKGROUND

Statins are 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors blocking cholesterol biosynthesis in hepatic cells, thereby causing an increase in low-density lipoprotein (LDL) receptors resulting in enhanced uptake and clearance of atherogenic LDL-cholesterol (LDL-C) from the blood. Accordingly, statins decrease the risk of developing atherosclerosis and its acute complications, such as acute myocardial infarction and ischaemic stroke. Besides the LDL-C-lowering impact, statins also have other so-called pleiotropic effects. Among them, the ability to modulate differentiation and function of bone cells and exert direct effects on osteosynthesis factors. Specifically, earlier studies have shown that statins cause in vitro and in vivo osteogenic differentiation.

DESIGN

The most relevant papers on the bone-related 'pleiotropic' effects of statins were selected following literature search in databases and were reveiwed.

RESULTS

Statins increase the expression of many mediators involved in bone metabolism including bone morphogenetic protein-2 (BMP-2), glucocorticoids, transforming growth factor-beta (TGF-β), alkaline phosphatase (ALP), type I collagen and collagenase-1. As a result, they enhance bone formation and improve bone mineral density by modulating osteoblast and osteoclast differentiation.

CONCLUSION

This review summarizes the literature exploring bone-related 'pleiotropic' effects of statins and suggests an anabolic role in the bone tissue for this drug class. Accordingly, current knowledge encourages further clinical trials to assess the therapeutic potential of statins in the treatment of bone disorders, such as arthritis and osteoporosis.

Hypertension is associated with osteoporosis: a case-control study in Chinese postmenopausal women

BACKGROUND

Osteoporosis and cardiovascular disease (CVD) are age-related diseases. It is reported that patients with CVD have a higher risk of bone loss. This retrospective study sought to reveal the association between osteoporosis and CVD in Chinese women. Although epidemiological evidence has indicated a relationship between the two, clinical data in southeast China are lacking.

METHODS

In total, 2873 participants completed the baseline survey from January 2007 to October 2019, and 2039 were included in this retrospective study. We divided all subjects into an osteoporosis group and a non-osteoporosis group based on their bone mineral density (BMD). Dual-energy X-ray absorptiometry (DXA) was used to examine BMD. The general information came from the questionnaire survey. Cardiovascular diseases were defined by asking participants at the first visit and checking relevant medical records if they had suffered from hypertension, coronary heart disease, or cerebral infarction.

RESULTS

According to the criterion, the osteoporosis group had 678 subjects, and the non-osteoporosis group had 1361 subjects. Subjects in the osteoporosis group had a significantly higher prevalence of hypertension and coronary heart disease. Besides, the proportion of subjects who drank tea and drank milk were relatively higher in the osteoporosis group. The odds ratio (OR) for suffering from osteoporosis was high if the patients had hypertension.

CONCLUSIONS

This study indicated that Chinese postmenopausal women with osteoporosis had a higher prevalence of hypertension. Hypertension was significantly associated with osteoporosis.