Association of osteoporotic fractures of femoral neck and femoral neck geometric parameters in native Chinese women.

BACKGROUND: Although it is generally believed that the femoral neck fracture is related to the femoral neck geometric parameters (FNGPs), the association between the risk of osteoporotic fracture of the femoral neck and FNGPs in native Chinese women is still unclear. METHODS: A total of 374 female patients (mean age 70.2 ± 9.32 years) with osteoporotic fracture of the femoral neck, and 374 non-fracture control groups were completely matched with the case group according to the age ratio of 1:1. Using DXA bone densitometer to measured eight FNGPs: the outer diameter (OD), cross-sectional area (CSA), cortical thickness (CT), endocortical diameter (ED), buckling ratio (BR), section modulus (SM), cross-sectional moment of inertia (CSMI), and compressive strength index (CSI) at the narrowest point of the femoral neck. RESULTS: Compared with the control group, the average values of OD (2.9%), ED (4.5%), and BR (26.1%) in the patient group significantly increased (p = 0.015 to < 0.001), while CSA (‒15.3%), CT (‒18.2%), SM (‒10.3%), CSMI (‒6.4%), and CSI (‒10.8%) significantly decreased (all p < 0.001). The prevalence of osteoporosis in the lumbar spine, femoral neck, and total hip was, respectively, 82%, 81%, and 65% in fracture patients. Cox proportional hazard model analysis showed that in the age adjusted model, the fracture hazard ratio (HR) of CSA, CT, BR, SM, and CSI significantly increased (HRs = 1.60‒8.33; 95% CI = 1.08‒16.6; all p < 0.001). In the model adjusted for age and femoral neck BMD, HRs of CT (HRs = 3.90‒8.03; 95% CI = 2.45‒15.1; all p < 0.001) and BR (HRs = 1.62‒2.60; 95% CI = 1.20‒5.44; all p < 0.001) were still significantly increased. CONCLUSION: These results suggest that the majority of osteoporotic fractures of the femoral neck of native Chinese women occur in patients with osteoporosis. CT thinning or BR increase of FNGPs may be independent predictors of fragility fracture of femoral neck in native Chinese women unrelated to BMD.

A phase III randomized, double-blind, placebo-controlled trial of the denosumab biosimilar QL1206 in postmenopausal Chinese women with osteoporosis and high fracture risk.

The current study evaluated the efficacy and safety of a denosumab biosimilar, QL1206 (60 mg), compared to placebo in postmenopausal Chinese women with osteoporosis and high fracture risk. At 31 study centers in China, a total of 455 postmenopausal women with osteoporosis and high fracture risk were randomly assigned to receive QL1206 (60 mg subcutaneously every 6 months) or placebo. From baseline to the 12-month follow-up, the participants who received QL1206 showed significantly increased bone mineral density (BMD) values (mean difference and 95% CI) in the lumbar spine: 4.780% (3.880%, 5.681%), total hip :3.930% (3.136%, 4.725%), femoral neck 2.733% (1.877%, 3.589%) and trochanter: 4.058% (2.791%, 5.325%) compared with the participants who received the placebo. In addition, QL1206 injection significantly decreased the serum levels of C-terminal crosslinked telopeptides of type 1 collagen (CTX): -77.352% (-87.080%, -66.844%), and N-terminal procollagen of type l collagen (P1NP): -50.867% (-57.184%, -45.217%) compared with the placebo over the period from baseline to 12 months. No new or unexpected adverse events were observed. We concluded that compared with placebo, QL1206 effectively increased the BMD of the lumbar spine, total hip, femoral neck and trochanter in postmenopausal Chinese women with osteoporosis and rapidly decreased bone turnover markers. This study demonstrated that QL1206 has beneficial effects on postmenopausal Chinese women with osteoporosis and high fracture risk.

Association of follicle-stimulating hormone with bone turnover markers and bone mineral density in Chinese women across the menopausal transition.

BACKGROUND: Elevated follicle-stimulating hormone (FSH) is associated with an increased risk of postmenopausal osteoporosis. This study investigated the association of serum FSH with bone turnover markers (BTMs) and bone mineral density (BMD) in healthy women undergoing menopausal transition. METHODS: A total of 487 healthy women (age 35-65 years, 50 ± 8.5 years) were enrolled in this study. Serum FSH, BTMs, and BMD at lumbar spine and total hip were measured in these subjects. RESULTS: Follicle-stimulating hormone was positively correlated with various BTMs (r = 0.339-0.583, all p < 0.001) and negatively correlated with lumbar spine and total hip BMD (r = -0.629 and -0.514, all p < 0.001). After adjusting for age and body mass index, the partial correlation coefficients of FSH with BTMs and BMD remained significant. Estimating from the regression equation, for every 10 IU/L increase in serum FSH, BTMs increased by 0.38-3.6 units, and BMD decreased by 0.03-0.05 g/cm2 , respectively. Multiple linear regression analysis showed that FSH was a positive factor for serum bone-specific alkaline phosphatase, osteocalcin, and N-telopeptide of collagen type 1 (ß = 0.188-0.403, all p < 0.001), and a negative factor for lumbar spine BMD and serum C-telopeptide of collagen type 1 (ß = -0.629 and -0.183, all p < 0.001). CONCLUSIONS: This study suggests that serum FSH levels are an independent risk factor for BTMs and BMD in menopause-transitioning women, particularly for serum BAP and lumbar spine BMD.

Relationship between bone mineral density and fragility fracture risk: a case-control study in Changsha, China.

BACKGROUND: Fragility fracture is associated with bone mineral density (BMD), and most databases used in related researches are instrument-matched. Little is known about the relationship between BMD and fragility fracture risk of native Chinese, especially using local databases as reference databases. OBJECTIVE: To investigate relationship between BMD and risk of fragility fracture in native China. METHODS: 3,324 cases, including 2,423 women (67.7 ± 8.9 years) and 901 men (68.4 ± 11.6 years) having radiological fragility fractures and 3,324 age- and gender-matched controls participated in the study. We measured BMD at posteroanterior spine and hip using dual-energy X-ray absorptiometry (DXA), calculated BMD measurement parameters based on our own BMD reference database. RESULTS: BMDs and mean T-scores were lower in case group (with clinical fragility) than in control group (without clinical fragility). In patients with fragility fractures, prevalence of lumbar osteoporosis, low bone mass, and normal BMD were 78.9 %, 19.3 %, and 1.8 %, respectively, in women, and 49.5, 44.8 %, and 5.7 %, respectively, in men. In hip, these prevalence rates were 67.2 %, 28.4 %, and 4.4 % in females, and 43.2 %, 45.9 %, and 10.9 % in males, respectively, showing differences between females and males. Multivariate Cox regression analysis showed that after adjusting age, height, weight, and body mass index, fracture hazard ratio (HR) increased by 2.7-2.8 times (95 % CI 2.5-3.1) and 3.6-4.1 times (95 %CI 3.0-5.1) for women and men respectively with decreasing BMD parameters. In both sexes, risk of fragility fracture increased approximately 1.6-1.7 times (95 % CI 1.5-1.8) for every 1 T-score reduction in BMD. CONCLUSIONS: Risk of clinical fragility fracture increases with decreasing BMD measurement parameters and anthropometric indicators in native China, and fracture HR varies from gender and site.

Glucagon-Like Peptide-1 (GLP-1) Receptor Agonist Liraglutide Alters Bone Marrow Exosome-Mediated miRNA Signal Pathways in Ovariectomized Rats with Type 2 Diabetes.

BACKGROUND Compared with normal postmenopausal women, estrogen deficiency and hyperglycemia in postmenopausal women with type 2 diabetes (T2DM) lead to more severe bone property degradation. Liraglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist, has been reported to improve bone condition among people with T2DM but the precise mechanisms remain unclear. Exosomes work as mediators in cell-to-cell communication, delivering functional miRNAs between cells. We aimed to explore the role of exosomes in T2DM-related bone metabolic disorders and the bone protective mechanisms of liraglutide. MATERIAL AND METHODS We made comparative analyses of bone marrow-derived exosomal miRNAs from ovariectomized (OVX) control rats, OVX + T2DM rats, and OVX + T2DM + liraglutide-treated rats. miRNA profiles were generated using high-throughput sequencing. Target gene prediction and pathway analysis were performed to investigate the signal pathway alterations. Three miRNAs were randomly chosen to validate their absolute expression levels by real-time quantitative PCR. RESULTS Bone marrow-derived exosomal miRNAs were different with respect to miRNA numbers, species, and expression levels. miRNA spectra varied under T2DM condition and after liraglutide treatment. By bioinformatics analysis, we found T2DM and liraglutide administration lead to significant changes in exosomal miRNAs which targeted to insulin secretion and insulin-signaling pathway. Wnt signaling pathway alteration was the critical point regarding bone metabolism. CONCLUSIONS Our findings show the selective packaging of functional miRNA cargoes into exosomes due to T2DM and liraglutide treatment. Bone marrow exosome-mediated Wnt signaling pathway alteration may play a part in the bone protective effect of liraglutide.

Age-related bone turnover markers and osteoporotic risk in native Chinese women.

BACKGROUND: The rate of bone turnover is closely related to osteoporosis risk. We investigated the correlation between bone turnover markers and BMD at various skeletal sites in healthy native Chinese women, and to study the effect of changes in the levels of bone turnover markers on the risk of osteoporosis. METHODS: A cross-section study of 891 healthy Chinese women aged 20-80 years was conducted. The levels of serum osteocalcin (OC), bone-specific alkaline phosphatase (BAP), serum cross-linked N-terminal telopeptides of type I collagen (sNTX), cross-linked C-terminal telopeptides of type I collagen (sCTX), urinary NTX (uNTX), urinary CTX (uCTX) and total urinary deoxypyridinoline (uDPD) were determined. BMD at the posteroanterior spine and the hip was measured using DXA. RESULTS: Pearson's correlation coefficient found significant negative correlation between bone turnover marker and BMD T-score at different skeletal sites (r = -0.08 to -0.52, all P = 0.038-0.000). After adjustments for age and body mass index, the partial correlation coefficients between the OC, BAP, sNTX, sCTX and uCTX, and the T-scores at various skeletal sites were still significant. After adjustment of height and weight, the correlation coefficients between most BTMs and PA lumbar spine BMD were also significant. Multiple linear regression analysis showed that bone turnover markers were negative determinants of T-scores. BAP and OC accounted for 33.1% and 7.8% of the variations in the T-scores of the PA spine, respectively. Serum OC, BAP, uDPD, and sNTX accounted for 0.4-21.9% of the variations in the femoral neck and total hip T-scores. The bone turnover marker levels were grouped as per quartile intervals, and the T-scores, osteoporosis prevalence and risk were found to markedly and increase with increase in bone turnover marker levels. CONCLUSIONS: This study clarified the relationship between bone turnover markers and osteoporosis risk in native Chinese women. Bone turnover marker levels were found to be important determinants of BMD T-scores. Furthermore, osteoporotic risk significantly increased with increase in the levels of bone turnover markers.

Effect of Body Surface Area on Severe Osteoporotic Fractures: A Study of Osteoporosis in Changsha China.

Clinical vertebral fractures and femoral neck fractures are severe osteoporotic fractures that increase morbidity and mortality. Anthropometric variables are associated with an increased risk of osteoporotic fractures, but it is not clear whether body surface area (BSA) has an effect on clinically severe osteoporotic fractures. The study included total of 3,694 cases of clinical vertebral fractures and femoral neck fractures (2,670 females and 1,024 males) and 3,694 controls without fractures who were matched with the cases by sex and age. There was a significant positive correlation between BSA and bone mineral density (BMD) in female and male fracture patients (females: r = 0.430-0.471, P < 0.001; males: r = 0.338-0.414, P < 0.001). There was a significant systematic increase in BMD in both genders at various skeletal sites, grouped by BSA quartile. The osteoporosis rates of the lumbar spine (97.9%), femoral neck (92.4%) and total hip (87.1%) in the female Q1 group were significantly higher than those in the Q4 group (P < 0.001), which were 80.0%, 57.9% and 36.9%, respectively, in the Q4 group; the osteoporosis rates of the lumbar spine, femoral neck, and total hip were 53.9%, 59.4%, and 36.3% in the male Q1 group, and 15.2%, 21.9%, and 7.03% in the Q4 group, which were significantly lower than those in the Q1 group (P < 0.001). In age-adjusted Cox regression models, the risk of fracture in the remaining three groups (Q2, Q3, and Q4) for weight, BMI, and BSA for both genders, compared with the highest quartile (Q1 by descending quartile stratification) were significantly higher. In models adjusted for age and BMD, only men in the BSA Q3 (HR = 1.55, 95% CI = 1.09-2.19) and BSA Q4 groups (HR = 1.41, 95% CI = 1.05-1.87) had significantly higher fracture risks. In models adjusted for age, height, weight, BMI, and BSA, low BMD was the greatest fracture risks for both sexes. Our results showed that BSA was closely related to BMD, prevalence of osteoporosis, and fracture risk, and that a decline in BSA may be a new potential risk factor for osteoporotic fractures in Chinese men.

Novel homozygous protein-truncating mutation of BBS9 identified in a Chinese consanguineous family with Bardet-Biedl syndrome.

BACKGROUND: Bardet-Biedl syndrome (BBS) is a rare and genetically heterogeneous disease with a broad spectrum of clinical features, including but not limited to rod-cone dystrophy, postaxial polydactyly, central obesity, intellectual disability, hypogonadism, and renal dysfunction. Twenty-one BBS (Bardet-Biedl syndrome) genes have been identified to date. There is minimal mutation information on BBS in Chinese populations and the exact pathogenic mechanism of the null mutation of BBS9 remains unknown. METHODS: A patient from a Chinese consanguineous family presented with polydactyly, truncal obesity, intellectual disability, genital anomaly, and retinitis pigmentosa was analyzed in this study. Blood DNA and RNA were extracted from the blood of the proband and the parents. The proband was screened for mutations by whole-exome sequencing. The likely pathogenic mutation detected in the proband was further confirmed by the Sanger sequence in the family. Real-time RT-PCR was used to measure the expression of BBS9 in the proband and the control. RESULTS: Targeted exome sequencing identified a novel homozygous null mutation (NM_198428.3: c.445C>T) in the 6th exon of the BBS9 gene in the proband and Sanger sequencing was used to validate the heterozygosity in the parents. The mutation was validated to induce the nonsense-mediated decay of BBS9 messenger RNAs by real-time RT-PCR. CONCLUSIONS: The molecular findings helped to explain the clinical manifestations. The novel homozygous pathogenic variation expanded the mutational spectrum of the BBS9 gene in the Chinese population and will help to understand the pathogenic mechanism of BBS9 null mutation.

[The effects of glucocorticoid on expression of cannabinoid-1 receptors in osteoclasts from tibial proximal metaphysis of rats].

OBJECTIVE: To explore the molecular mechanism of glucocorticoid (GC)-induced osteoporosis (GIOP). METHODS: Thirty-two female SD rats after matching body weight were divided randomly into three groups: baseline group (n = 10), control group (n = 11) and GC-treated group (n = 11). The administration time was 9 weeks. Bone mineral density (BMD) was measured with dual energy X-ray absorptiometry. A high resolution micro-CT was used to quantify the densitometric and microarchitectural properties of trabeculae in the proximal metaphysis of right tibia. In situ hybridization histochemistry and immunohistochemistry were used to detect the expression of cannabinoid type 1 receptor (CB1R) in the proximal metaphysis of left tibia. RESULTS: At the end of the experiment, whole-body BMD in vivo in the control group [(0.156 +/- 0.008) g/cm(2)] was higher than that in the baseline group [(0.147 +/- 0.006) g/cm(2)], while the whole-body BMD in vivo [(0.147 +/- 0.006) g/cm(2)] and total BMD in vitro at femurs in the GC-treated group [(0.220 +/- 0.011) g/cm(2)] was lower than those in the control group [(0.240 +/- 0.024) g/cm(2)]. Compared with the baseline group and control group, there was a remarkable decrease in the volumetric BMD, tissue BMD, trabecular number and trabecular connectivity (P < 0.05) in the GC-treated group, while there was a significant increase in trabecular separation (P < 0.05) and trabecular thickness also increased in the proximal metaphysis of tibiae in the GC-treated group. The expression level of CB1R mRNA and protein in osteoclasts in the GC-treated group was markedly higher than that in the baseline group and control group (P < 0.05). There was a close correlation between the expression level of CB1R mRNA, protein in osteoclasts and some microarchitectural parameters in the proximal metaphysis in the GC-treated group (P < 0.05). CONCLUSIONS: The administration of GC is associated with a decrease in BMD and deterioration in microarchitecture of trabecular bone in rats tibiae. Glucocorticoid may up-regulate the CB1R expression level in osteoclasts and this may be a kind of molecular mechanism of GIOP.

Relationship between age-related reference values of serum osteoprotegerin and leptin in native Chinese women and compared with those in women of other races.

BACKGROUND: Osteoprotegerin (OPG) and leptin are important cellular factors in the regulation of bone remodeling. We investigated the serum OPG and leptin in Chinese women. METHODS: The serum OPG and leptin in 690 Chinese women aged 20-81 y were measured by an ELISA. The values of OPG and leptin in women of other races were acquired from previous reports on the same. RESULTS: The geometric mean values (+/- SD) of the serum OPG and leptin in Chinese women were 3.42+/-1.91 pmol/l and 10.5+/-1.99 microg/l, respectively. Further, the serum OPG (4.39+/-1.85 vs 2.74+/-1.81) and leptin (11.4+/-2.21 vs 9.68+/-1.81) in postmenopausal women were significantly higher than in premenopausal women. The serum OPG in middle-aged Chinese women was significantly higher than that in middle-aged Austrian and Icelandic women; however, this is quite contrary to the results obtained in the case of old-aged women. The values of serum leptin in Chinese women were significantly lower than those in white, black, and Mexican American women. CONCLUSIONS: These results provide reliable reference values for OPG and leptin in Chinese adult women. The serum of OPG and leptin differ with ethnicity.

Quantitative associations between osteocyte density and biomechanics, microcrack and microstructure in OVX rats vertebral trabeculae.

Osteocytes actively regulate bone modeling and remodeling, direct skeletal mineralization, and regulate calcium/phosphate homeostasis and extracellular matrix metabolism; yet the specific role of osteocytes in maintaining bone structural integrity and strength is unknown. Studies have shown that the density of osteocytes decreases with age and estrogen deficiency, as seen in postmenopausal women. Here, we examined the relationships between osteocyte density and the related variables, including biomechanics, bone mineral density, microcrack and microstructure of vertebral trabeculae, in ovariectomized rats. We found that osteocyte density correlated with some of the parameters that determine the biomechanical quality of bone. Our findings suggest that osteocytes could play a crucial role in maintaining the mechanical quality of bone, and osteocyte density could be considered as an alternative index in assessing bone quality.

[Dynamic effects of glucocorticoid on bone mineral density and microarchitecture: experiment with rats].

OBJECTIVE: To investigate the Dynamic effects of glucocorticoid (GC) on bone mineral density and microarchitecture time-related changes of trabecular bone in bone mineral density (BMD) and microarchitecture in glucocorticoid-treated rats. METHODS: Fifty-two 3.5-month-old female SD rats were randomly divided into 3 groups. Ten rats were killed at the beginning of experiment with their right tibiae taken out as the baseline group; 22 rats underwent subcutaneous injection of methylprednisolone once daily (GC-treated group), and the other 20 rats underwent subcutaneous injection of normal saline once daily as control group. One and 9 weeks after the beginning of experiment 11 and 10 rats from GCT Group and control group each were killed with their right tibiae taken out. High resolution micro-CT was used to identify the densitometric and microarchitectural properties of the trabecula in the proximal metaphysic of tibia. RESULTS: Compared with the control group the values of volumetric BMD (vBMD), tissue BMD (tBMD), bone volume fraction (BVF), trabecular number (Tb.N), degree of anisotropy (DA), and trabecular connectivity (Conn.D) in the trabecular bone at different time-points, of the GCT group all decreased; and the values in the ninth week were the lowest (all P < 0.05). The values of trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), and structure model index (SMI) at different time-points of the GCT group were higher than those of the control group. A time-related analysis within the GCT group showed there was a declination in BVF, Conn.D, Tb.N, and DA with administration time, but Tb.Th and Tb.Sp were increased significantly (all P < 0.05). The mean values of Tb.Th in the first week and the ninth week of GCT Group were (0.076 +/- 0.020) mm and (0.086 +/- 0.026) mm respectively, both higher than the baseline value [(0.067 +/- 0.014) mm] and the values of the control group in the first and ninth weeks [(0.075 +/- 0.022) mm and (0.072 +/- 0.009) mm respectively]. CONCLUSION: Administration of GC time dependently decreases the BMD and causes deterioration in microarchitecture of trabecular bone; and the remaining trabeculae seem thicken to increase their strength as compensation.

[Nanomechanical properties of vertebral trabeculae in ovariectomized rats].

OBJECTIVE: To study the nanomechanical properties of the vertebral trabeculae of ovariectomized rat using nanoindentation. METHODS: Twenty 10-month-old SD rats were randomly divided into 2 equal groups: ovariectomized (OVX) group and Sham operation (SHAM) group. Fifteen weeks post-operationally dual energy X-ray absorptiometry was used to measure the bone mineral density (BMD) of the total body and of the sixth lumbar vertebra. Then the rats were killed. The BMD values of the sixth lumbar vertebrae were measured by DXA. Bone histomorphometry was performed on the proximal metaphysis of the right tibia. Three of the sixth lumbar vertebrae were randomly selected from each group and embedded in methyl methacrylate. Each vertebra was cut into two parts along the transverse direction in the middle point of longitudinal axis so as to expose the trabeculae on the cross section. The lower part was polished, trabeculae were randomly selected from 4 places, and 5 points from each place were randomly selected to undergo nanoindentation so as to measure the nanomechanical properties. RESULTS: Compared with the SHAM rats, the BMD of the sixth lumbar vertebra of the OVX rats was reduced significantly (P < 0.05). The histomorphometry of the tibia showed an increase in trabecular separation and a decrease in trabecular bone area fraction (both P < 0.05); the trabecular number and thickness decreased in these 2 groups, however, without significant difference between them. Nanoindentation tests showed that the values of hardness and elastic modulus of the trabeculae of the OVX rats were 0.91 GPa +/- 0.13 GPa and 21.01 GPa +/- 2.48 GPa respectively, not significantly different from those of the SHAM rats, 0.90 GPa +/- 0.09 GPa and 22.03 GPa +/- 2.44 GPa respectively. CONCLUSION: A novel technique, nanoindentation is able to directly measure the nanomechanical properties of trabeculae. Estrogen deficiency after ovariectomy induces significant osteoporotic change, but has no significant influence on the trabecular nanomechanical properties.

Gender differences in a reference database of age-related femoral neck geometric parameters for Chinese population and their association with femoral neck fractures.

Femoral neck geometric parameters (FNGPs) are closely related to the strength of the femoral neck and the risk of fragility fractures. No reference database is available for FNGPs for Chinese population, and gender-related differences in FNGPs as well as their association with the risk of femoral neck fractures are unknown. This investigation aimed to set up reference databases for FNGPs, understand gender-related differences in FNGPs, and examine the association between FNGPs and the risk of osteoporotic fractures of the femoral neck. This study included 5268 females and 2156 males (aged 15-91years) from Chinese population. A total of 384 patients (282 females and 102 males) had sustained femoral neck fractures; 384 age- and sex-matched individuals without any fractures served as controls. Femoral neck DXA images were used to measure bone mineral density (BMD) and eight FNGPs. Our results showed that the age-related trends of FNGPs were fitted with the best goodness-of-fit by applying the cubic regression model. The trends shown by FNGPs were significantly different between male and female subjects, and the fitting curves were significantly higher in male subjects. After adjustments were made for age, height, weight, and body mass index, Cox regression analysis showed that changes in all FNGPs were related to increased hazard ratios (HRs) of femoral neck fractures. After further adjustment was made for BMD of the femoral neck, the HRs related to a cortical thickness (CT) decrease and buckling ratio (BR) increase in females went up by 3.35-folds (95% CI: 2.75-4.07) and 1.86-folds (95% CI: 1.33-2.60), respectively. In males, the HRs related to the decrease in CT and cross-sectional area (CSA) increased by 3.21-folds (95% CI: 2.32-4.45) and 1.88-folds (95% CI: 1.03-3.44), respectively. In conclusions, the reference databases of FNGPs established in this study will assist in the evaluation and prediction of femoral neck fracture risk in the clinic. The decrease in CT and increase in BR of the femoral neck were independent risk factors for osteoporotic fractures of the femoral neck in females from mainland China, while a decrease in CT and CSA were risk factors in male.

Effects of 17 beta-estradiol on the expression of interstitial collagenases-8 and -13 (MMP-8 and MMP-13) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in ovariectomized rat osteoblastic cells.

Estrogen plays an important role in maintaining normal bone metabolism via the direct or indirect regulation of bone cells. Osteoblastic cells, as the target cells of estrogen, can secrete multiple matrix metalloproteinases (MMPs) that participate in bone remodeling. It has been demonstrated that bone loss induced by estrogen deficiency is closely related to the abnormal expression of multiple MMPs in osteoblastic cells. However, the regulating action of estrogen on the expression of interstitial collagenases MMP-8 and MMP-13 in osteoblastic cells in vivo remains unclear. We used an ovariectomized osteoporotic rat model to analyze the changes in the histomorphometric parameters of bone after and without treatment with 17beta-estradiol (E(2)); We also used immunohistochemistry and in situ hybridization to observe changes in the expression of mRNA and the proteins MMP-8, MMP-13 and TIMP-1 in osteoblastic cells in rat proximal tibia. In this study, we found that in the ovariectomized rat the expression of MMP-13 mRNA and protein increased markedly, whereas the expression of MMP-8 and TIMP-1 mRNA and protein did not change significantly. Our analysis showed that the expression of MMP-13 protein was correlated positively to bone trabecular separation, osteoid surface area, and negatively to trabecular numbers and the percentage of trabecula bone volume/total tissue volume. Our results suggest that MMP-13 plays an important role in estrogen deficiency-induced bone loss, while estrogen can inhibit bone resorption and reduce bone turnover rate by down-regulating the expression of MMP-13 in osteoblastic cells.

[Digital speckle correlation method: a technique to evaluate the tensile property of articular cartilage].

OBJECTIVE: To establish a new technique for evaluation of the tensile property of articular cartilage using digital speckle correlation method (DSCM). METHODS: Three specimens of whole layer articular cartilage of the size of 10 mm x 4 mm were prepared from the cartilage of head of femur replaced from a 52-year-old male suffering from fracture of neck of femur (old control), the amputated tibia plateau of a 16-year-old female suffering from osteosarcoma (young control), and the cartilage of head of femur of a 19-year-old female suffering from spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDT-PA) and then underwent DSCM in U and V fields. RESULTS: The specimens of the 2 controls showed a smooth surface of cartilage and homologous deformation while the specimen of the SEDT-PA patient showed a rough surface of cartilage and deformation with increased undulation. Under a changed loading of 3.3 N the values of average strain of cartilage were 3800, 8800, and 9500 micro epsilon, and the values of tensile elastic modularity were 227.23, 89.59, and 127.25 MPa respectively for the old control, young control, and SEDT-PA patient. The numbers of pixel in U field after 20 pixels were moved in the X direction were significantly different between the old control subject and the SEDT-PA patient (0.101 +/- 0.022 vs 0.220 +/- 0.053, P = 0.023). The numbers of pixel in V field after 20 pixels were moved in the Y direction were significantly different among the old control subject and the SEDT-PA patient. Differences were also significant among the three kinds of cartilage (0.055 +/- 0.018, 0.196 +/- 0.057 vs 0.658 +/- 0.144, both P < 0.05). CONCLUSION: DSCM is a reliable technique to measure the tensile property of articular cartilage, especially for evaluation of small specimens. SEDT-PA is characterized by a dramatic decrease of tensile property, causing destruction and loss of the articular cartilage.

[Pathology and molecular pathogenesis of spondyloepiphyseal dysplasia tarda with progressive arthropathy caused by compound CCN6 heterogeneous gene mutations].

OBJECTIVE: To characterize the clinical manifestations, features of roentgenography and MR imaging, and the pathology of articular cartilage and matrix of spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDT-PA), to screen the mutations of the disease-causing CCN6 gene, and try to elucidate the molecular pathogenesis of SEDT-PA. METHODS: A questionnaire survey on the clinical manifestations and history was conducted among a pedigree of SEDT-PA with 57 persons (53 living members) in tolal, including 2 probands, a 19-year old female and a 9-year old male. Physical examination and roentgenography and MR imaging were used on the 2 probands to characterize the features of their joints and articular cartilage. The femoral head extracted during replacement of hip of the proband 1 underwent hematoxylin-eosin staining and toludine blue (TB) staining to observe the pathological changes and ultra-microstructure of the articular chondrocytes and cartilage matrix using electron microscopy. Peripheral blood samples were collected from these 53 living members and 100 healthy controls. PCR was used to examine and sequence the exons of CCN6. 3D-conformational illustration of mutant CCN6 proteins were predicted using the Prospect Software. RESULTS: The clinical manifestations, radiology, and MR imaging established the diagnosis of SEDT-PA. Pathologic examination demonstrated that the articular cartilage chondrocytes became hyper-proliferative and immature, while the density and diameter of matrix collagens were dramatically decreased. Mutation studies showed the two probands carried a deletion (840delT) mutation in maternal allele, that caused the truncated CCN6 protein to miss 43 residues in C-terminus; and a substitution mutation (1000T-->C, Ser334Pro) in paternal allele, which was also inherited down to other 4 members in the SEDT-PA kindred. The predicted 3D-conformational changes of the truncated mutant and the Ser334Pro mutant CCN6 proteins demonstrated that in comparison with the wild CCN6 protein, the single long peptide loop in the region from signal peptide to the beginning 24 amino acid residues in the first domain (IGFBP) was subjected to folding into two smaller cross-loops accompanied with a much shorter C-terminus in 840 delT truncated mutant CCN6 protein, and no substantial 3D-conformational change of Ser334Pro mutant CCN6 protein was detected except for the C-terminal peptide towards the opposite direction. CONCLUSION: Novel 840delT mutation of CCN6 gene is the leading cause of SEDT-PA though coexistence of T1000C substitution is necessary for the clinical onset of SEDT-PA, in which marked abnormalities of cartilage chondrocytes and matrix are morphologically and functionally presented.

[Effects of parathyroid hormone on osteoprotegerin expression and osteoprotegerin ligand and their related cytokines in human osteoblasts].

OBJECTIVE: To investigate the pathway and mechanism of parathyroid hormone (PTH) in regulating bone resorption. METHODS: We observed the regulative effects of PTH on the expression of osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL) and their related cytokines (M-CSF and TRAIL) in human osteoblasts (HOBs). The expressions of OPG, OPGL, M-CSF, and TRAIL mRNA were determined by RT-PCR. The expressions of OPG and OPGL proteins were measured by Western blotting. RESULTS: PTH down-regulated the expression of OPG but up-regulated the expressions of OPGL, M-CSF and TRAIL in HOBs. CONCLUSION: PTH can promote the bone resorption by decreasing the expression of OPG, increasing the expressions of some bone-resorbing cytokines such as OPGL, M-CSF, and TRAIL in osteoblasts, and then stimulating the osteoclast differentiation and activity.

[Effects of long-term replacement therapy of compound nylestriol tablet or low-dose 17 beta-estradiol on the expression of nerve growth factor in OVX rat hippocampal formation].

OBJECTIVE: To determine the effects of long-term estrogen deficiency and replacement therapy of compound nylestriol tablet or low-dose 17 beta-estradiol on the expression of nerve growth factor (NGF) in rat hippocampal formation. METHODS: Fifty 7 month-old female Sprague-Dawley rats were randomly divided into 5 groups: normal control, sham operated (SHAM), ovariectomized (OVX), OVX plus 17 beta-estradiol (OVX/ERT), and OVX plus compound nylestriol tablet (OVX/NL) groups. Immunohistochemistry of NGF was used to quantitatively determine the levels of expression of NGF using cell counting and imaging system in ovariectomized rat hippocampal formation. RESULTS: The number and optical density of NGF-positive neurons of all hippocampal subregions and dentate gyrus in OVX rats were obviously lower than those of the normal control, SHAM, OVX/NL, and OVX/ERT rats. CONCLUSION: Long-term estrogen deficiency can lead to a decrease of NGF expression in hippocampal formation, while the replacement of low-dose 17 beta-estradiol or compound nylestriol tablet can equally preserve the expression of NGF to a normal level, showing a neurotrophic effect of estrogen.

[Compound nylestriol tablet to prevent bone loss in osteoporotic rats].

OBJECTIVE: To investigate the effects of compound nylestriol tablet (CNT), containing nylestriol and levonorgestrel with a ratio of 1:0.3) and its components on the osteoporotic rat model induced by retinoic acid (RA) and ovariectomy (OVX). METHODS: We randomly divided 144 female SD rats (aged 7-month-old) into 12 groups (12 in each). In addition, 120 female SD rats aged 4-month were randomly divided into 10 groups (10 in each). Three dosage levels of CNT (0.039, 0.117 and 0.39 mg/kg body weight, daily), nylestriol (NYL, 0.30, 0.09 and 0.03 mg/kg body weight, daily) and levonorgestrel (LEV, 0.09, 0.027 and 0.009 mg/kg body weight, daily) were designed to prevent the bone loss of the osteoporotic rat model induced by RA and OVX respectively. Serum total calcium (Ca), phosphate (Pi), ALP, triglyceride (TG), total cholesterol (TC), HDL-C, total body BMD, isolated left femoral BMD and femoral Ca, and Pi after ashing were determined. RESULTS: Osteoporotic models could be induced by RA (70 mg/kg body weightdaily given intragastrically for 14 days) or by ovariectomy; CNT and its components had the preventive effects on bone loss in both models; The preventive effect of CNT was dose-dependent and stronger than its components; Many observed markers showed us the levels of high and moderate CNT given to be the strongest, corresponding to an optimal choice of the moderate dose CNT about one tablet per week in adult women. CONCLUSIONS: CNT therapy can prevent the bone loss of RA-induced and OVX-induced osteoporotic rats, and its therapeutic and preventive effect is better than its components used alone.