The Potential Role of Serum IGF-1 and Leptin as Biomarkers: Towards Screening for and Diagnosing Postmenopausal Osteoporosis

Oral dehydroepiandrosterone supplementation enhances osteoporotic fracture healing in the OVX rats

Osteoporosis easily causes delayed fracture union, even non-union. It has been demonstrated that dehydroepiandrosterone (DHEA) supplementation can increase estrogen levels and improve bone mineral density (BMD) in the elderly, while the role of DHEA on fracture healing remains unknown. This study aimed to elucidate the impact of DHEA supplementation on osteoporotic fracture healing. Seventy-two female Sprague-Dawley rats were used. Forty-eight rats received ovariectomy (OVX), and the remaining rats received a sham OVX operation (sham group). A right transverse femoral osteotomy was performed in all rats at 12 weeks post-OVX. OVX rats were randomly allocated into 2 groups (n = 24 in each group): (i) ovariectomized rats (control group) and (ii) ovariectomized rats treated with DHEA (DHEA group, 5 mg/kg/day). The DHEA supplementation was initiated on the first day post-fracture for 3, 6, and 12 weeks. Fracture healing was evaluated by radiography, histology, biomechanical analysis, and dual-energy X-ray absorptiometry (DEXA). Serum biomarkers were analyzed using enzyme-linked immunosorbent assay (ELISA). At 3 and 6 weeks, radiographs revealed reduced calluses formation and lower radiographic scores in the control group than in other groups. The sham and DHEA groups showed higher BMD and bone mineral content (BMC) at the fracture site than the control group after fracture. Histological analysis revealed the fracture callus was remodeled better in the sham and DHEA groups than in the control group. At the early phase of healing, DHEA supplementation increased osteoblast number, callus area, and cartilage area than the control group. An increased bone area was observed in the DHEA group than in the control group at the late phase of healing. Additionally, improved biomechanical characteristics were observed in both the sham and DHEA groups than those in the control group post-fracture. ELISA showed higher levels of insulin-like growth factor-1 (IGF-1) and 17β-estradiol (E2) in the DHEA group than in the control group post-fracture. Furthermore, the DHEA group exhibited significantly elevated alkaline phosphatase (ALP) and osteocalcin (OC) levels compared to the control group at 6 and 12 weeks. The DHEA group and the control group did not exhibit a notable difference in TRAP-5b levels. The present study demonstrated that the DHEA treatment has a favorable impact on osteoporotic fracture healing by enhancing callus formation, consolidation, and strength in the OVX rats.

Identification of immune infiltration and immune-related biomarkers of periprosthetic joint infection

Background

The immune response associated with periprosthetic joint infection (PJI) is an emerging but relatively unexplored topic. The aim of this study was to investigate immune cell infiltration in periprosthetic tissues and identify potential immune-related biomarkers.

Methods

The GSE7103 dataset from the GEO database was selected as the data source. Differentially expressed genes (DEGs) and significant modular genes in weighted correlation network analysis (WGCNA) were identified. Functional enrichment analysis and transcription factor prediction were performed on the overlapping genes. Next, immune-related genes from the ImmPort database were matched. The protein-protein interaction (PPI) analysis was performed to identify hub genes. CIBERSORTx was used to evaluate the immune cell infiltration pattern. Spearman correlation analysis was used to evaluate the relationship between hub genes and immune cells.

Results

A total of 667 DEGs were identified between PJI and control samples, and 1847 PJI-related module genes were obtained in WGCNA. Enrichment analysis revealed that the common genes were mainly enriched in immune and host defense-related terms. TFEC, SPI1, and TWIST2 were the top three transcription factors. Three hub genes, SDC1, MMP9, and IGF1, were identified in the immune-related PPI network. Higher levels of plasma cells, CD4+ memory resting T cells, follicular helper T cells, resting mast cells, and neutrophils were found in the PJI group, while levels of M0 macrophages were lower. Notably, the expression of all three hub genes correlated with the infiltration levels of seven types of immune cells.

Conclusion

The present study revealed immune infiltration signatures in the periprosthetic tissues of PJI patients. SDC1, MMP9, and IGF1 were potential immune-related biomarkers for PJI.

Osteoporosis and Leptin: A Systematic Review

Background

Leptin has a great effect on bone through direct or indirect involvement in bone remodeling. Considering the ambiguities that exist regarding the effect of leptin on bone and bone-related diseases including osteoporosis, in this study, we aimed to conduct a systematic review of various studies on the effect of leptin on osteoporosis, which may find an answer to the existing ambiguities.

Methods

The search was performed to review studies on the effects of leptin on osteoporosis by using several databases including Scopus, PubMed, Web of Science, and Google Scholar. Electronic searches were conducted on 5 Jan 2023. There was no limit on the publication date of the articles. The risk of bias for the animal study was assessed with the CAMARADES checklist, and the study quality assessment was also assessed based on the guidelines for in vivo experiments (ARRIVE). In this study, the risk of bias (quality) of human studies was assessed using the quality assessment checklists by NHLBI.

Results

Overall, 34 articles were included for data extraction and quality assessment. Overall, 27 human studies and seven animal studies were included in the article. The results of most of the studies conducted in this study showed that leptin has a physiological role in maintaining bone mass and better bone quality and reduces bone marrow adipogenesis and increases bone mineral density (BMD). As plasma leptin levels increased, BMD values or bone formation biomarkers increased.

Conclusion

Leptin has an inhibitory role against bone resorption and increasing osteoprotegerin (OPG) levels, which, as a result, maintains bone density and reduces osteoclast activity, and has a positive relationship with increasing osteocalcin.

The Association of nutritional status and physical activity on osteoporotic refractures among older adults

BACKGROUND

This paper focuses on revealing the relationship between the Geriatric Nutritional Risk Index (GNRI) and Activity of Daily Living (ADL) with osteoporotic refracture.

METHODS

Data from 1068 inpatients with osteoporotic fractures were analyzed. Binary logistic regression, Cox proportional hazard regression and Kaplan-Meier curves were performed for osteoporosis characteristics and its risk factors. Receiver operating characteristic (ROC) curve was developed to predict the cut-off value.

RESULTS

The study showed that older age, lower ADL and lower GNRI were independent risk factors for osteoporotic fracture with OR of 1.039, 0.946, 0.892 and HR of 1.033, 0.967, 0.947 respectively. According to the results of ROC, the predictive accuracy of GNRI was high with an area under ROC (AUC) of 0.715, sensitivity of 76.6%, specificity of 53.5% and a threshold value of 99.65.

CONCLUSION

Older age, lower ADL and lower GNRI were independent risk factors for osteoporotic refracture.

Leptin-VEGF crosstalk in excess body mass and related disorders: A systematic review

By 2030, it is expected that a billion people will have suffer from obesity. Adipose tissue synthesizes leptin, an adipokine that affects cardiovascular risk. Leptin intensifies the synthesis of vascular endothelial growth factor (VEGF). Our study reviews recent reports on leptin-VEGF crosstalk in obesity and related disorders. PubMed, Web of Science, Scopus, and Google Scholar were searched. One hundred and one articles involving human, animal, and in vitro research were included. In vitro studies show the crucial role of interaction between endothelial cells and adipocytes and hypoxia as a factor that intensifies leptin's effects on VEGF. Leptin-VEGF crosstalk promotes the progression of cancer. The animal research reveal that a high-fat diet enhances leptin and VEGF crosstalk. Genetic and epigenetic mechanisms and procreator-offspring programming may be involved in leptin-VEGF crosstalk. Some female-specific characteristics of leptin-VEGF relation in obesity were observed. The human studies have shown that increased leptin and VEGF synthesis and leptin-VEGF crosstalk are factors linking obesity with elevated cardiovascular risk. The studies of the last 10 years documented a range of significant aspects of leptin-VEGF crosstalk specific for obesity and related disorders, shedding new light on the link between obesity and increased cardiovascular risk.

Associations Between Inflammatory Mediators and Bone Outcomes in Postmenopausal Women: A Cross-Sectional Analysis of Baseline Data from the Prune Study

Purpose

Hypoestrogenism triggers increased production of inflammatory mediators, which contribute to bone loss during postmenopausal osteoporosis. This study aimed to investigate the association between circulating inflammatory markers and bone outcomes in postmenopausal women.

Materials and methods

We conducted a cross-sectional, secondary analysis of baseline data from participants who completed a 12-month randomized controlled trial, The Prune Study (NCT02822378), which included healthy postmenopausal women (n=183, 55-75 years old) with bone mineral density (BMD) T-score between 0.0 and -3.0 at any site. BMD was measured using dual-energy X-ray absorptiometry, and bone geometry and strength were measured using peripheral quantitative computed tomography. Blood was collected at baseline to measure (1) serum biomarkers of bone turnover, including procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide and (2) inflammatory markers, including serum high-sensitivity C-reactive protein (hs-CRP) and plasma pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, and monocyte chemoattractant protein (MCP)-1, using enzyme-linked immunosorbent assay. The associations between bone and inflammatory outcomes at baseline were analyzed using correlation and regression analyses.

Results

Serum hs-CRP negatively correlated with P1NP (r=-0.197, p=0.042). Plasma IL-1β, IL-6, IL-8, and TNF-α negatively correlated with trabecular bone score at the lumbar spine (all p<0.05). In normal-weight women, plasma IL-1β, IL-6, and IL-8 negatively correlated (p<0.05) with trabecular and cortical bone area, content, and density at various sites in the tibia and radius. Serum hs-CRP positively predicted lumbar spine BMD (β=0.078, p=0.028). Plasma IL-6 negatively predicted BMD at the total body (β=-0.131, p=0.027) and lumbar spine (β=-0.151, p=0.036), whereas plasma TNF-α negatively predicted total hip BMD (β=-0.114, p=0.028).

Conclusion

At baseline, inflammatory markers were inversely associated with various estimates of bone density, geometry, and strength in postmenopausal women. These findings suggest that inflammatory markers may be an important mediator for postmenopausal bone loss.

Elucidating the relationship between dyslipidemia and osteoporosis: A multicenter, prospective cohort study protocol

Background

A previous study has shown similar factors in dyslipidemias (DL) and osteoporosis (OP). However, no cohort study has been reported on the association between DL and OP in the postmenopausal population in China. This study aims to provide epidemiological and pathophysiological evidence regarding the association between DL and bone mass and fracture risk.

Methods

This is a multicenter, prospective cohort study that will have approximately 1,100 representative participants enrolled from multiple hospitals or communities in China. They will be divided into two groups according to whether or not they are exposed to dyslipidemia and will be epidemiologically investigated. Each participant will be visited continuously once every year with a minimum follow-up of 3 years to track incidences of OP. Meanwhile, free bone density screening, questionnaires, and blood sample collection will also be completed during this period.

Conclusion

The current study is likely to provide greater insight into the relationship between lipid metabolism and bone metabolism in postmenopausal women. Furthermore, the research result maybe fed into public health strategies with regard to metabolic disease prevention.

IL-6 and Leptin Are Potential Biomarkers for Osteoporotic Fracture Risk Assessment and Prediction of Postmenopausal Women with Low Bone Mass: A Follow-Up Study Using a Regional Sample Cohort

Osteoporotic fracture, a major complication which is known as the outcome postmenopausal osteoporosis, seriously threatens the health of postmenopausal women. At present, the traditional osteoporotic fracture prediction methods are characterized by inconvenient application and time-consuming statistical results, while predictive serum biomarkers can make up for this shortcoming. Accurate and advanced risk prediction of osteoporotic fracture is meaningful to early prevention and intervention, effectively avoiding the risk of this disease and the secondary fracture in the surgical treatment. In this study, based on the BEYOND cohort, a 2-year follow-up study was conducted after subjects participated to survey if OF occurred. Independent sample t-test and Mann–Whitney U-test were used to analyze the differences of bone metabolism biomarkers between the OF and non-OF group. Cox proportional hazard model was used to screen the potential biomarkers might be used to predict OF risk. ROC curves and AUCs were used to analyze the predictive accuracy, and the Delong's test was used to compare the differences between the AUCs. 15 postmenopausal women with low bone mass and OF were found, and other 60 subjects without OF were matched with 1 : 4, age, and BMI classification as control group. The serum IL-6 (OR = 1.139, 95%CI = 1.058 − 1.226) and leptin (OR = 0.921, 95%CI = 0.848 − 1.000) were found as OF risk predictive biomarkers for postmenopausal women with low bone mass with high accuracy (IL − 6 = 0.871) (leptin = 0.813) and accuracy enhanced when they were combined (AUC = 0.898). The results of Delong's test showed that the difference of AUC between leptin and IL-6&Leptin was meaningful (P = 0.024) but meaningless between IL-6 and leptin (P = 0.436), IL-6 and IL-6&Leptin (P = 0.606). To sum up, IL-6 and leptin are the predictive biomarkers of OF for postmenopausal women with low bone mass. The IL-6 can improve the prediction accuracy of leptin (P = 0.024), but not vice versa (P = 0.606). Trial Information. Registered on the Chinese Clinical Trial Registry already. (Registration Number: ChiCTR-SOC-17013090).

Crosstalk between the gut microbiota and postmenopausal osteoporosis: Mechanisms and applications

Postmenopausal osteoporosis (PMO) results from a reduction in bone mass and microarchitectural deterioration in bone tissue due to estrogen deficiency, which may increase the incidence of fragility fractures. The number of people suffering from PMO has increased over the years because of the rapidly aging population worldwide. However, several pharmacological agents for the treatment of PMO have many safety risks and impose a heavy financial burden to patients and society. In recent years, the "gut-bone" axis has been proposed as a new approach in the prevention and treatment of PMO. This paper reviews the relationship between the gut microbiota and PMO, which mainly includes the underlying mechanisms between hormones, immunity, nutrient metabolism, metabolites of the gut microbiota and intestinal permeability, and explores the possible role of the gut microbiota in these processes. Finally, we discuss the therapeutic effects of diet, prebiotics, probiotics, and fecal microbiota transplantation on the gut microbiota.