Relationship of circulating MMP-2, MMP-1, and TIMP-1 levels with bone biochemical markers and bone mineral density in postmenopausal Chinese women

Olink and gut microbial metabolomics reveal new biomarkers for the prediction and diagnosis of PMOP

LNTRODUCTION

Postmenopausal osteoporosis (PMOP) can cause postmenopausal women to experience pain and interference. Identifying and exploring potential early diagnostic biomarkers of PMOP is of substantial clinical value and social significance. This study aimed to screen for potential novel diagnostic biomarkers of PMOP through a multiomics approach, providing new directions and ideas for the early prevention and treatment of this disease.

MATERIALS AND METHODS

Fifteen postmenopausal women with osteoporosis and 12 without were recruited. Clinical information was collected, and various clinical biochemical parameters were tested. Plasma and fecal samples were collected and analyzed using Olink proteomics and gut microbial metabolomics.

RESULTS

The functions of the differentially abundant metabolites were mainly related to autophagy and arginine and proline metabolism and were involved in immunoinflammatory metabolic processes. Olink showed significant differences in the expression of seven inflammation-related proteins between the two groups.

CONCLUSION

We demonstrated that metabolic differences between PMOP patients and healthy controls were associated with inflammatory responses and found seven proteins with significant differences. Among these proteins, CDCP1, IL10, and IL-1alpha combined with clinical indicators had high discriminant efficiency in identifying PMOP. This is also the first study to demonstrate noteworthy changes in CDCP1 levels in patients with PMOP.

Current knowledge of bone-derived factor osteocalcin: its role in the management and treatment of diabetes mellitus, osteoporosis, osteopetrosis and inflammatory joint diseases

Osteocalcin (OC) is the most abundant non-collagenous and osteoblast-secreted protein in bone. It consists of two forms such as carboxylated OC (cOC) and undercarboxylated OC (ucOC). While cOC promotes bone mineralization and increases bone strength, ucOC is regarded an endocrinologically active form that may have several functions in multiple end organs and tissues. Total OC (tOC) includes both of these forms (cOC and ucOC) and is considered a marker of bone turnover in clinical settings. Most of the data on OC is limited to preclinical studies and therefore may not accurately reflect the situation in clinical conditions. For the stated reason, the aim of this review was not only to summarize current knowledge of all forms of OC and characterize its role in diabetes mellitus, osteoporosis, osteopetrosis, inflammatory joint diseases, but also to provide new interpretations of its involvement in the management and treatment of aforementioned diseases. In this context, special emphasis was placed on available clinical trials. Significantly lower levels of tOC and ucOC could be associated with the risk of type 2 diabetes mellitus. On the contrary, tOC level does not seem to be a good indicator of high bone turnover status in postmenopausal osteoporosis, osteoarthritis and rheumatoid arthritis. The associations between several pharmacological drugs used to treat all disorders mentioned above and OC levels have also been provided. From this perspective, OC may serve as a medium through which certain medications can influence glucose metabolism, body weight, adiponectin secretion, and synovial inflammation.

Importance of Metalloproteinase Enzyme Group in Selected Skeletal System Diseases

Bone tissue is a dynamic structure that is involved in maintaining the homeostasis of the body due to its multidirectional functions, such as its protective, endocrine, or immunological role. Specialized cells and the extracellular matrix (ECM) are responsible for the remodeling of specific bone structures, which alters the biomechanical properties of the tissue. Imbalances in bone-forming elements lead to the formation and progression of bone diseases. The most important family of enzymes responsible for bone ECM remodeling are matrix metalloproteinases (MMPs)-enzymes physiologically present in the body's tissues and cells. The activity of MMPs is maintained in a state of balance; disruption of their activity is associated with the progression of many groups of diseases, including those of the skeletal system. This review summarizes the current understanding of the role of MMPs in bone physiology and the pathophysiology of bone tissue and describes their role in specific skeletal disorders. Additionally, this work collects data on the potential of MMPs as bio-markers for specific skeletal diseases.

Identification of State Markers in Anorexia Nervosa: Replication and Extension of Inflammation Associated Biomarkers Using Multiplex Profiling in Anorexia Nervosa and Atypical Anorexia Nervosa

Proteomics provides an opportunity for detection and monitoring of anorexia nervosa (AN) and its related variant, atypical-AN (atyp-AN). However, research to date has been limited by the small number of proteins explored, exclusive focus on adults with AN, and lack of replication across studies. This study performed Olink Proseek Multiplex profiling of 92 proteins involved in inflammation among females with AN and atyp-AN (N = 64), all < 90% of expected body weight, and age-matched healthy controls (HC; N=44). After correction for multiple testing, nine proteins differed significantly in the AN/atyp-AN group relative to HC group ( lower levels: CXCL1, HGF, IL-18R1, TNFSF14, TRANCE; higher levels: CCL23, Flt3L, LIF-R, MMP-1). The expression levels of three proteins ( lower IL-18R1, TRANCE; higher LIF-R) were uniquely disrupted in females with AN. No unique expression levels emerged for atyp-AN. Across the whole sample, twenty-one proteins correlated positively with BMI (ADA, AXIN1, CD5, CD244, CD40, CD6, CXCL1, FGF-21, HGF, IL-10RB, IL-12B, IL18, IL-18R1, IL6, LAP TGF-beta-1, SIRT2, STAMBP, TNFRSF9, TNFSF14, TRAIL, TRANCE) and six (CCL11, CCL23, FGF-19, IL8, LIF-R, OPG) were negatively correlated with BMI. Overall, our results replicate the prior study demonstrating a dysregulated inflammatory status in AN, and extend these results to atyp-AN (AN/atyp-AN all < 90% of expected body weight). Of the 27 proteins correlated with BMI, 18 were replicated from a prior study using similar methods, highlighting the promise of inflammatory protein expression levels as biomarkers of disease monitoring. Additional studies of individuals across the entire weight spectrum are needed to understand the role of inflammation in atyp-AN.

Asperosaponin VI induces osteogenic differentiation of human umbilical cord mesenchymal stem cells via the estrogen signaling pathway

BACKGROUND

Asperosaponin VI (ASA VI) is an active ingredient found in the traditional Chinese herb Radix Dipsaci, which is used to treat fractures. ASA VI combined with osteogenic medium can induce osteogenic differentiation of rat-derived stem cells. However, whether ASA VI alone can induce osteoblast differentiation of human mesenchymal stem cells (MSCs) remains unclear.

METHODS

ASA VI human-derived binding proteins were searched in the PharmMapper database, osteogenesis-related signaling pathways were obtained through a literature search, and proteins contained in these signaling pathways were queried in the Kyoto Encyclopedia of Genes and Genomes database. SystemsDock was used to perform online molecular docking of target proteins to evaluate their binding abilities, and validation experiments were performed.

RESULTS

A total of 620 ASA VI target proteins and 12 osteogenesis-related signaling pathways were queried, and 17 intersecting targets were screened. Molecular docking results showed that these targets had high binding affinity for ASA VI. We selected estrogen receptor 2 and its estrogen signaling pathway for experimental validation. The results showed that ASA VI can induce the osteogenic differentiation of MSCs through the estrogen signaling pathway.

CONCLUSION

ASA VI can independently induce osteogenic differentiation of human umbilical cord MSCs, and the estrogen signaling pathway plays an important role in this process. Thus, ASA VI may have potential as an anti-osteoporosis drug.

A Potential Participant in Type 2 Diabetes Bone Fragility: TIMP-1 at Sites of Osteocyte Lacunar-Canalicular System

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of bone fracture, but the bone mineral density (BMD) is typically normal or higher in such patients. Because the fracture risk is independent of reduced BMD, bone fragility in T2DM may be partially due to poor bone quality. The mechanisms triggering bone quality abnormalities in T2DM are complex, and include the accumulation of advanced glycation end-products, the increased inflammation, and low bone turnover. Matrix metalloproteinases (MMPs) in bone can hydrolyze the bone matrix. Tissue inhibitors of MMPs (TIMPs) can inhibit the activity of MMPs. Both MMPs and TIMPs participate in mediating bone quality. Among all types of TIMPs, TIMP-1 is mostly reportedly increased in the serum of T2DM patients. Because osteocytes can express TIMP-1, and osteocyte pericellular matrix influences bone quality partially regulated by perilacunar/canalicular remodeling, we hypothesized that TIMP-1 at sites of osteocyte lacunar-canalicular system is involved in T2DM bone fragility.

Deciphering the Relevance of Bone ECM Signaling

Bone mineral density, a bone matrix parameter frequently used to predict fracture risk, is not the only one to affect bone fragility. Other factors, including the extracellular matrix (ECM) composition and microarchitecture, are of paramount relevance in this process. The bone ECM is a noncellular three-dimensional structure secreted by cells into the extracellular space, which comprises inorganic and organic compounds. The main inorganic components of the ECM are calcium-deficient apatite and trace elements, while the organic ECM consists of collagen type I and noncollagenous proteins. Bone ECM dynamically interacts with osteoblasts and osteoclasts to regulate the formation of new bone during regeneration. Thus, the composition and structure of inorganic and organic bone matrix may directly affect bone quality. Moreover, proteins that compose ECM, beyond their structural role have other crucial biological functions, thanks to their ability to bind multiple interacting partners like other ECM proteins, growth factors, signal receptors and adhesion molecules. Thus, ECM proteins provide a complex network of biochemical and physiological signals. Herein, we summarize different ECM factors that are essential to bone strength besides, discussing how these parameters are altered in pathological conditions related with bone fragility.

A meta-analysis of serum osteocalcin level in postmenopausal osteoporotic women compared to controls

Background

Circulatory osteocalcin (OC) has been widely used as a biomarker to indicate bone turnover status in postmenopausal osteoporosis (PMO). However, the change of serum OC (sOC) level in PMO cases compared to postmenopausal controls remains controversial.

Methods

We searched the online database of PubMed and Cochrane Library. A meta-analysis of case-control studies was performed to compare the pooled sOC level between PMO patients and postmenopausal controls. Subgroup analysis according to potential confounding factors (different OC molecules and regions of the study population) was also performed.

Results

Ten case-control studies with 1577 postmenopausal women were included in this meta analysis. We found no significant difference in the pooled sOC level [mean difference (MD) = 1.84, 95% confidence interval (CI): (− 1.49, 5.16), p = 0.28] between PMO patients and controls. Subgroup analysis also revealed no significant difference in intact OC [MD = 1.76, 95%CI: (− 1.71, 5.23), p = 0.32] or N-terminal mid-fragment of the OC molecule [MD = 0.67, 95%(− 5.83, 7.18), p = 0.84] between groups. For different regions, no significant difference in sOC was found in Asian population between cases and controls [MD = -0.06, 95%(− 6.02, 5.89), p = 0.98], while the pooled sOC level was significantly higher in European PMO cases than controls [MD = 3.15, 95%(0.90, 5.39), p = 0.006].

Conclusions

Our analysis revealed no significant difference in sOC level between PMO cases and controls according to all the current eligible studies. OC molecules are quite heterogeneous in the circulation and can be influenced by glucose metabolism. Therefore, sOC is currently not a good indicator for the high bone turnover status in PMO. More trials with standardized methodologies for the evaluation of circulatory OC are awaited to update our current findings.

Screening and validation of serum protein biomarkers for early postmenopausal osteoporosis diagnosis

Postmenopausal osteoporosis is one of the most prominent worldwide public health problems and the morbidity is increasing with the aging population. It has been demonstrated that early diagnosis and intervention delay the disease progression and improve the outcome. Therefore, searching for biomarkers that are able to identify postmenopausal women at high risk for developing osteoporosis is an effective way to improve the quality of life of patients, and alleviate social and economic burdens. In the present study, a protein array was used to identify potential biomarkers. The bone mineral densities of 10 rats were dynamically measured in an ovariectomized model by micro‑computed tomography assessment, and the early stage of osteoporosis was defined. Through the protein array‑based screening, the expression levels of six serum protein biomarkers in ovariectomized rats were observed to alter at the initiation stage of the postmenopausal osteoporosis. Fractalkine, tissue inhibitor of metalloproteinases‑1 and monocyte chemotactic protein‑1 were finally demonstrated to be increased in the serum of eight enrolled postmenopausal osteoporosis patients using ELISA assay and were correlated with the severity of progressive bone loss. These biomarkers may be explored as potential early biomarkers to readily evaluate and diagnose postmenopausal osteoporosis in the clinic.

Matrix Metalloproteinases in Bone Resorption, Remodeling, and Repair

Matrix metalloproteinases (MMPs) are the major protease family responsible for the cleavage of the matrisome (global composition of the extracellular matrix (ECM) proteome) and proteins unrelated to the ECM, generating bioactive molecules. These proteins drive ECM remodeling, in association with tissue-specific and cell-anchored inhibitors (TIMPs and RECK, respectively). In the bone, the ECM mediates cell adhesion, mechanotransduction, nucleation of mineralization, and the immobilization of growth factors to protect them from damage or degradation. Since the first description of an MMP in bone tissue, many other MMPs have been identified, as well as their inhibitors. Numerous functions have been assigned to these proteins, including osteoblast/osteocyte differentiation, bone formation, solubilization of the osteoid during bone resorption, osteoclast recruitment and migration, and as a coupling factor in bone remodeling under physiological conditions. In turn, a number of pathologies, associated with imbalanced bone remodeling, arise mainly from MMP overexpression and abnormalities of the ECM, leading to bone osteolysis or bone formation. In this review, we will discuss the functions of MMPs and their inhibitors in bone cells, during bone remodeling, pathological bone resorption (osteoporosis and bone metastasis), bone repair/regeneration, and emergent roles in bone bioengineering.

Matrix Metallopeptidase-2 Gene rs2287074 Polymorphism is Associated with Brick Tea Skeletal Fluorosis in Tibetans and Kazaks, China

Brick tea skeletal fluorosis is still a public health issue in the north-western area of China. However its pathogenesis remains unknown. Our previous study reveals that the severity of skeletal fluorosis in Tibetans is more serious than that in Kazaks, although they have similar fluoride exposure, suggesting the onset of brick tea type skeletal fluorosis might be genetically influenced. Here we show that MMP-2 rs2287074 SNP (G/A), but not rs243865, was associated with Brick tea type fluorosis in Tibetans and Kazaks, China. The trend test reveals a decline in probability for skeletal fluorosis with increasing number of A alleles in Tibetans. After controlling potential confounders, AA genotype had about 80 percent lower probability of developing skeletal fluorosis than GG genotype in Tibetans (odds ratio = 0.174, 95% CI: 0.053, 0.575), and approximately 53 percent lower probability in Kazaks (odds ratio = 0.462, 95% CI: 0.214, 0.996). A meta-analysis shows that the AA genotype had approximately 63 percent lower odds (odds ratio = 0.373, 95% CI: 0.202, 0.689) compared with GG genotype within the two ethnicities. A significant correlation was also found between the genotype of MMP2 rs2287074 and skeletal fluorosis severity. Therefore, the A allele of MMP2 rs2287074 could be a protective factor for brick tea skeletal fluorosis.

Relationships between serum Omentin-1 levels and bone mineral density in older men with osteoporosis

OBJECTIVE

To investigate the correlation between serum Omentin-1 levels and the presence of osteoporosis in older men.

METHODS

Serum Omentin-1, bone turnover biochemical markers, and bone mineral density (BMD) were determined in 45 older men with osteoporosis or 45 older men without osteoporosis (65-70 years old).

RESULTS

Omentin-1 levels were increased in older men with osteoporosis, and the differences remained significant after controlling for fat mass. Omentin-1 was negatively correlated with BMD. In a multiple linear stepwise regression analysis, Omentin-1, lean mass, but not fat mass, were independent predictors of BMD for the combined group. Significant negative correlations between Omentin-1 and bone-specific alkaline phosphatase (BAP) and bone cross-linked N-telopeptides of type Ⅰ collagen (NTX) were found. Omentin-1 was also independently associated with BMD and bone turnover markers in older men with osteoporosis and control groups that were considered separately.

CONCLUSIONS

Omentin-1 is an independent predictor of BMD in older men with osteoporosis, and it is negatively correlated with bone turnover biochemical markers. It is suggested that Omentin-1 may exert a negative effect on bone mass through the regulation of the osteoblast differentiation in the older men with osteoporosis.

Potential impact of sitagliptin on collagen-derived dipeptides in diabetic osteoporosis

It is known that diabetes coincides with an increased risk of osteoporosis. While a disturbed collagen metabolism is proposed as a possible cause, much remains unknown about the enzymes involved and changes in the collagen-derived dipeptides and amino acids. Therefore, we sought to study this intricate pathway and the effect of dipeptidyl peptidase 4 (DPP4) inhibitors. Control and streptozotocin-nicotinamide-induced diabetic rats were treated for 12 weeks with vehicle or sitagliptin, a DPP4 inhibitor (Con/VH, Con/SG, DM/VH and DM/SG). The activities of four key enzymes involved in collagen breakdown were determined in serum (DPP4, matrix metalloproteinase 2 and 9 and prolidase). Dipeptide (Ala-Pro, Gly-Pro, Pro-Pro and Pro-Hyp) and amino acid (Pro and Hyp) concentrations were measured by liquid chromatography coupled to mass spectrometry. We found three-fold higher MMP9 activities in DM/VH than in controls, while in DM/SG this rise was attenuated. MMP2 and prolidase did not differ in the investigated groups. Furthermore, we are the first to report on two-fold higher Ala-Pro and Pro-Pro levels in diabetes compared to controls. In contrast, Pro-Hyp concentrations were lower in diabetes (DM/VH and DM/SG). DPP4 inhibition does not seem to have a direct influence on the collagen metabolism in streptozotocin-nicotinamide-induced diabetic rats. Instead, it probably acts through its effect on osteoprotective substrates. In diabetes, increased MMP9 activities seem to favour the production of Ala-Pro and Pro-Pro containing collagen fragments. The high Pro-Hyp levels in untreated controls might have a bone-stimulating effect. Nevertheless, the biological significance of these dipeptides is not yet clear and should be further investigated.

Relationship between serum omentin-1 level and bone mineral density in girls with anorexia nervosa

BACKGROUND

Adolescents with anorexia nervosa (AN) have low bone mineral density (BMD). Omentin- 1, the main circulating adipocytokine, plays an important role in bone metabolism in healthy individuals. However, their association with bone metabolism in AN is unknown.

METHODS

Serum omentin-1, bone turnover biochemical markers, and BMD were determined in 26 girls with AN and 24 healthy girls (15-18 years old).

RESULTS

Omentin-1 levels increased in AN subjects, and the differences became greater after controlling for fat mass. Omentin-1 was negatively correlated with BMD. In the multiple linear stepwise regression analysis, omentin-1, body mass index and lean mass, but not fat mass, were independent predictors of BMD for the combined group. Significant negative correlations were found between omentin-1 and bone-specific alkaline phosphatase, bone cross-linked N-telopeptides of type I collagen. Omentin-1 was also independently associated with BMD and bone turnover markers in the AN and control groups considered separately.

CONCLUSIONS

Omentin-1 was an independent predictor of BMD in adolescents with AN, and negatively correlated with bone turnover markers. This suggested that omentin-1 may exert a negative effect on bone mass by inhibiting bone formation in girls with AN.

Targeting polymer therapeutics to bone

An aging population in the developing world has led to an increase in musculoskeletal diseases such as osteoporosis and bone metastases. Left untreated many bone diseases cause debilitating pain and in the case of cancer, death. Many potential drugs are effective in treating diseases but result in side effects preventing their efficacy in the clinic. Bone, however, provides a unique environment of inorganic solids, which can be exploited in order to effectively target drugs to diseased tissue. By integration of bone targeting moieties to drug-carrying water-soluble polymers, the payload to diseased area can be increased while side effects decreased. The realization of clinically relevant bone targeted polymer therapeutics depends on (1) understanding bone targeting moiety interactions, (2) development of controlled drug delivery systems, as well as (3) understanding drug interactions. The latter makes it possible to develop bone targeted synergistic drug delivery systems.

Expression of MMP-1 and TIMP-1 in irradiated mandibles during distraction osteogenesis

OBJECTIVES

The study aimed to evaluate the expression of MMP-1 and TIMP-1 in irradiated mandibles during distraction osteogenesis.

STUDY DESIGN

Rabbits in the experimental group received preoperative radiation of 9 Gy for 5 fractions. After 1 month, all rabbits underwent osteotomy and distraction osteogenesis with 7 days of latency. Three rabbits in the control and experimental groups were killed at days 7, 12, 18, and 25. Specimens were subjected to immunohistochemical examination and real-time polymerase chain reaction analysis.

RESULTS

At day 7, expression of MMP-1 and TIMP-1 was significantly suppressed in the radiotherapy group in contrast to the control group. At day 12, expression of MMP-1 was significantly higher in the control group. At day 18, expression of MMP-1 and TIMP-1 was significantly higher in the control than in the radiotherapy group.

CONCLUSIONS

Radiotherapy changes the expression pattern of MMP-1 and TIMP-1.

Matrix metalloproteases MMP-2 and MMP-9: are they early biomarkers of bone remodelling and healing after arthroscopic acromioplasty?

Arthroscopic acromioplasty, one of the most frequent procedures in shoulder surgery, can promote tissue healing process by the release of growth/angiogenic factors from the acromion. Matrix metalloproteinases MMP-2 and MMP-9 are involved in such process. The purpose of this study was to measure MMP-2 and MMP-9 levels in the articular fluid and in the peripheral blood of patients undergoing arthroscopic acromioplasty in order to better understand the local involvement of such factors in the healing process after surgical procedures. Concentrations of MMP-2 and MMP-9 in the subacromial space and peripheral blood collected shortly after surgery were determined by ELISA. MMP-2 and MMP-9 concentrations were measured in the subacromial fluid of 23 patients. In subacromial fluid, the levels between MMP-2 and MMP-9 did not reach statistical significance (127.15±45.56 vs 149.41±53.61 pg/ml, respectively, p>0.05). Peripheral blood levels of MMP-2 (130.75±47.48 pg/ml) were comparable to the subacromial fluid ones (127.15±45.56 pg/ml) whereas MMP-9 level was higher in the subacromial space (149.41±53.61 pg/ml) than in the peripheral blood (67.61±12.62 pg/ml, p<0.001). This work suggests that the measurement of bone specific MMPs (MMP-2 and MMP-9) can be an useful tool to be monitored in parallel with growth factor levels and other bone turnover markers in order to evaluate the bone remodelling and tissue healing processes. This study suggests that the measurement of bone specific MMPs levels, in particular MMP-9, may evaluate the bone remodelling and healing after arthroscopic shoulder acromioplasty.

Relationships between serum adiponectin, apelin, leptin, resistin, visfatin levels and bone mineral density, and bone biochemical markers in post-menopausal Chinese women

BACKGROUND

Adiponectin, apelin, leptin, resistin, and visfatin, as the main circulating peptides secreted by adipose tissue, are potential contributors to bone metabolism. However, their association with bone mineral density (BMD) is unclear.

AIM

The present study investigated whether these serum adipocytokines levels are associated with BMD and bone turnover markers.

METHODS

Serum adiponectin, apelin, leptin, resistin, visfatin levels, bone turnover biochemical markers, and BMD were determined in 336 post-menopausal Chinese women (41-81 yr old).

RESULTS

Adiponectin was negatively correlated with fat mass, while leptin had a positive correlation. In the multiple linear stepwise regression analysis, years since menopause, lean mass, estradiol, and adiponectin, but not fat mass, apelin, leptin, resistin, and visfatin, were independent predictors of BMD. The significant positive correlations between adiponectin and bone-specific alkaline phosphatase, bone crosslinked N-telopeptides of type I collagen were found.

CONCLUSIONS

Adiponectin was an independent predictor of BMD in post-menopausal Chinese women, and positively correlated with bone turnover biochemical markers. It suggested that adiponectin may exert a negative effect on bone mass by promoting excessive bone resorption associated with bone loss in post-menopausal women.

Human bone disorders: pathological role and diagnostic potential of matrix metalloproteinases

Bone undergoes continuous remodeling under physiological and pathological conditions. Failure of the regulation of this process leads to several disorders involving bone erosion. This series of events is mainly based on the action of proteinases, particularly matrix metalloproteinases (MMPs). MMPs have been recently suggested as potential bone resorption markers which could be added to the commonly used ones, in order to predict outcome of disease processes and healing, and to monitor disease response to treatment. As for classical biochemical bone markers, MMPs are far from being applied in primary clinical diagnosis, but they could be promising in some cases for disease prognosis. MMPs as bone remodeling biomarkers could provide information that boosts our understanding of the prognosis, disease activity and pathogenesis of bone disorders. Clarifying the MMPs' role in bone remodeling and healing could potentially help predict disease progression and the effects of direct specific therapy.

Carotid intima-media thickness and bone turnover: the role of C-terminal telopeptide of type I collagen

Osteoporosis and vascular disease are commonly found together in elderly people. Several common mechanisms and risk factors have been suggested to contribute to the development of osteoporosis and atherosclerosis. The present cross-sectional study was performed to determine whether the degree of bone turnover is correlated to carotid intima-media thickness (CCA-IMT), as a marker of subclinical atherosclerosis. We selected 50 outpatients (mean age 71.7 +/- 12.3), underwent to eco-Doppler evaluation of extracranial carotid tract, without history of calcium and/or vitamin D supplementation, or antireabsorptive therapy. CCA-IMT was measured by high-resolution B-mode ultrasonography. Bone turnover was evaluated by analysing serum levels of C-terminal telopeptide of type I collagen (sCTX), and bone-specific alkaline phosphatase. We also evaluated the vitamin D status by determination of the serum concentration of 25-hydroxyvitamin D [25(OH)D]. We found a prevalence of hypovitaminosis D [serum 25(OH)D levels <30 ng/mL, mean value 10.7 +/- 5.8] of 91.8%, and an increased bone resorption, with mean sCTX levels higher than reference values (mean 1.18 +/- 0.57 ng/mL). A significant positive correlation was found between CCA-IMT and age (r = 0.480, P = 0.001), erythrocyte sedimentation rate (ESR: r = 0.438, P = 0.001), high-sensitivity C-Reactive Protein (HsCRP: r = 0.482, P = 0.011), serum creatinine (r = 0.305, P = 0.031), and sCTX (r = 0.389, P = 0.006). In a multivariate linear regression, CCA-IMT was independently predicted by age (beta = 0.34, P = 0.001), ESR (beta = 0.37, P = 0.005), and sCTX (beta = 0.32, P = 0.006). The preliminary results of our study seem to indicate that after adjustment for established cardiovascular risk factors, sCTX independently predict an increased CCA-IMT in the elderly population.

Relationships between serum adiponectin, leptin concentrations and bone mineral density, and bone biochemical markers in Chinese women

BACKGROUND

Adiponectin and leptin, as the main circulating peptides secreted by adipose tissue, are potential contributors to bone metabolism. However, their association with bone mineral density (BMD) is unknown. We investigated whether these serum adipocytokines concentrations are associated with BMD and bone turnover markers.

METHODS

Serum adiponectin, leptin concentrations, bone turnover biochemical markers, and BMD were determined in 265 premenopausal and 336 postmenopausal Chinese women.

RESULTS

In postmenopausal Chinese women, the multiple linear stepwise regression analysis showed that year since menopause, lean mass, estradiol, and adiponectin, but not fat mass, leptin, were independent predictors of BMD in postmenopausal Chinese women. However, in premenopausal Chinese women, adiponectin was not the predictor of BMD. The significant positive correlations between adiponectin and bone-specific alkaline phosphatase (BAP), bone cross-linked N-telopeptides of type I collagen (NTX) were found only in postmenopausal women. Serum BAP, and NTX, but not adiponectin, decreased in response to alendronate therapy.

CONCLUSIONS

Adiponectin was an independent predictor of BMD, and positively correlated with bone turnover biochemical markers in postmenopausal Chinese women, but not premenopausal women. It suggested that adiponectin may exert a negative effect on bone mass by promoting excessive bone resorption associated with bone loss. However, these effects may be mediated by menopausal status.

Genetic variation in candidate osteoporosis genes, bone mineral density, and fracture risk: the study of osteoporotic fractures

Candidate osteoporosis gene variants were examined for associations with fracture risk and bone mineral density (BMD). A total of 9,704 white women were recruited at four U.S. clinical centers and enrolled into the Study of Osteoporotic Fractures, a longitudinal cohort study. Genotyping of 31 polymorphisms from 18 candidate osteoporosis genes was performed in 6,752 women. Incident radiographic fractures were identified at the third and eighth examinations compared with the baseline examination. BMD was measured at the total hip by dual-energy X-ray absorptiometry. Analyses were adjusted for age, clinic site, and self-reported ethnicity. During a mean follow-up of 14.5 years, a total of 849 hip, 658 vertebral, and 2,496 nonhip/nonvertebral fractures occurred in 6,752 women. Women carrying the ALOX15_G48924T T/T genotype had a higher rate of hip fracture (hazard ratio [HR] = 1.33;95% confidence interval [95% CI] = 1.00-1.77) compared with the G/G genotype. Compared with those carrying the PRL_T228C T/T genotype, women with either the C/C (HR = 0.80; 95% CI = 0.67-0.95) or C/T (HR = 0.81; 95% CI = 0.68-0.97) genotype had a lower rate of nonvertebral/nonhip fractures. Women carrying the BMP2_A125611G G/G genotype had a higher rate of vertebral fracture (odds ratio [OR] = 1.51; 95% CI = 1.03-2.23) compared with the A/A genotype. Women with the ESR1_C1335G G/G genotype had a higher rate of vertebral fracture (OR = 1.64; 95% CI = 1.07-2.50) compared with the C/C genotype. Compared with those with the MMP2_C595T C/C genotype, women with the C/T (OR = 0.79; 95% CI = 0.65-0.96) or T/T (OR = 0.44; 95% CI = 0.27-0.72) genotype had a lower rate of vertebral fracture. In conclusion, polymorphisms in several candidate genes were associated with hip, vertebral, and nonhip/nonvertebral fractures but not with total hip BMD in this large population based cohort study.

Relationships between serum adiponectin, leptin, resistin, visfatin levels and bone mineral density, and bone biochemical markers in Chinese men

BACKGROUND

Adiponectin, leptin, resistin, and visfatin, as the main circulating peptides secreted by adipose tissue, are potential contributors to bone metabolism. We investigated whether these serum adipocytokines levels are associated with BMD and bone turnover biochemical markers in 232 Chinese men (20-80 y).

METHODS

Serum adiponectin, leptin, resistin, and visfatin levels were determined by ELISA.

RESULTS

Leptin had a positively correlation with fat mass, and remained significant after adjustment for age and BMI. There was a significant negative weak correlation between adiponectin and fat mass, and disappear after adjustment for age and BMI. Resistin and visfatin were not significantly correlated with fat mass. In the multiple linear stepwise regression analysis, lean mass and adiponectin, but not leptin, resistin and visfatin, were independent predictors of BMD. The significant positive correlations between adiponectin and bone-specific alkaline phosphatase (BAP), bone cross-linked N-telopeptides of type collagen (NTX) were found, and remained significant after adjustment for age and fat mass.

CONCLUSIONS

Adiponectin was an independent predictor of BMD in Chinese men, and positively correlated with bone turnover biochemical markers. It suggested that adiponectin exert a negative effect on bone mass in men.

Effects of tacrolimus, cyclosporin A and sirolimus on MG63 cells

The reduction in bone mineral density after organ transplantation results in increased morbidity (post-transplantation bone disease) and remains an unsolved problem. A connection with the long-term application of nonglucocorticoidal immunosuppressants is the subject of controversial discussion. We hypothesized that such substances have an influence on the skeletal system on the cellular level by modulating osteoblast differentiation. Therefore, we investigated the effects of tacrolimus, cyclosporin A and sirolimus as representative substances of nonglucocorticoidal immunosuppressants on cell proliferation and expression of bone tissue-specific genes of human osteoblasts (MG63). None of the examined substances affected cell proliferation, but all influenced the gene expression pattern towards change in cell differentiation. In detail, collagen III and XII, matrix metalloproteinase 2, SMAD2, epithelial growth factor receptor, annexin V and osteonectin expression were increased by all of the examined substances. Tacrolimus, cyclosporin A and sirolimus influence intracellular signalling pathways, transmembranous receptors and bone-specific matrix synthesis. They do not have antiproliferative or toxic effects. We postulate that the shown changes of osteoblast differentiation cause post-transplantation disease.