An in vivo genome wide gene expression study of circulating monocytes suggested GBP1, STAT1 and CXCL10 as novel risk genes for the differentiation of peak bone mass.

Peak bone mass (PBM) is an important determinant of osteoporosis. Circulating monocytes serve as early progenitors of osteoclasts and produce important molecules for bone metabolism. To search for genes functionally important for PBM variation, we performed a whole genome gene differential expression study of circulating monocytes in human premenopausal subjects with extremely low (N=12) vs. high (N=14) PBM. We used Affymetrix HG-U133 plus2.0 GeneChip arrays. We identified 70 differential expression probe sets (p<0.01) corresponding to 49 unique genes. After false discovery rate adjustment, three genes [STAT1, signal transducer and activator of transcription 1; GBP1, guanylate binding protein 1; CXCL10, Chemokine (C-X-C motif) ligand 10] expressed significantly differentially (p<0.05). The RT-PCR results independently confirmed the significantly differential expression of GBP1 gene, and the differential expression trend of STAT1. Functional analyses suggested that the three genes are associated with the osteoclastogenic processes of proliferation, migration, differentiation, migration, chemotaxis, adhesion. Therefore, we may tentatively hypothesize that the three genes may potentially contribute to differential osteoclastogenesis, which may in the end lead to differential PBM. Our results indicate that the GBP1, STAT1 and CXCL10 may be novel risk genes for the differentiation of PBM at the monocyte stage.

Proteomic analysis of circulating monocytes in Chinese premenopausal females with extremely discordant bone mineral density.

Osteoporosis (OP) is a major public health problem, mainly characterized by low bone mineral density (BMD). Circulating monocytes (CMCs) may serve as progenitors of osteoclasts and produce a wide variety of factors important to bone metabolism. However, the specific action mechanism of CMCs in the pathogenesis of OP is far from clear. We performed a comparative protein expression profiling study of CMCs in Chinese premenopausal females with extremely discordant BMD, identified a total of 38 differentially expressed proteins, and confirmed with Western blotting five proteins: ras suppressor protein1 (RSU1), gelsolin (GSN), manganese-containing superoxide dismutase (SOD2), glutathione peroxidase 1(GPX1), and prolyl 4-hydroxylase beta subunit (P4HB). These proteins might affect CMCs' trans-endothelium, differentiation, and/or downstream osteoclast functions, thus contribute to differential osteoclastogenesis and finally lead to BMD variation. The findings promote our understanding of the role of CMCs in BMD determination, and provide an insight into the pathogenesis of human OP.

Establishment of peak bone mineral density in Southern Chinese males and its comparisons with other males from different regions of China.

Peak bone mineral density (PBMD) is an important determinant of osteoporotic fracture and a precondition for correct diagnosis of osteoporosis. The objective of this study was to establish the reference data of PBMD at the lumber spine and hip in Southern Chinese males. Bone mineral density (BMD) was measured at the lumbar spine and hip (femoral neck, trochanter, intertrochanter, and total) in 1155 Chinese men aged 15-39 years, using dual-energy X-ray absorptiometry (DXA). We utilized a fit curve method to determine the best age range over which to calculate PBMD. Our results indicated that the PBMD was observed at the age range of 18-25 years at the various sites. The mean value and standard deviation of PBMD was 0.753 +/- 0.117, 1.156 +/- 0.148, 0.896 +/- 0.120, 0.989 +/- 0.122, and 0.980 +/- 0.116 g/cm2 at the trochanter, intertrochanter, femoral neck, total hip, and spine, respectively. When the present PBMD reference was compared with the documented PBMD reference of males from other regions of China, we found great difference in standardized PBMD between Changsha males and those from other regions of China. The PBMD for Chinese males in Changsha at the various sites were 3.19%-11.33% lower than that for American Caucasian males. In conclusion, the PBMD at the spine and hip may be used as normal reference data for Southern Chinese males in Changsha instead of documented PBMD from other regions of China and the manufacturer's reference data.

Evaluating the correlation and prediction of trunk fat mass with five anthropometric indices in Chinese females aged 20-40 years.

BACKGROUND AND AIMS: Obesity is a worldwide problem, and excess trunk fat mass (FM(trunk)) has been associated with an increased risk of diseases. The early measurement of FM(trunk) has potential importance to evaluate trunk obesity. We sought to evaluate the correlation and predication of FM(trunk) with five anthropometric indices in Chinese females. METHODS AND RESULTS: A sample of 850 China females aged 20-40 years were recruited and divided into four age groups with a 5-year range in each group. Five anthropometric indices were measured or calculated. FM(trunk) in kg was measured using a dual-energy X-ray absorptiometry scanner. Principal component analysis (PCA) and multiple regression analysis were performed to develop prediction equations. There was an increasing trend of FM(trunk) and five anthropometric indices in successively older age groups. Four formed principal components (PCs) interpreted over 99% of the total variation of five relative anthropometric indices in all age groups. Regression analyses showed that four PCs combined explained a greater variance (R(2)=45.2-81.6%) in FM(trunk) than did each of the five indices alone (R(2)=2.4-72.2%). CONCLUSIONS: Our results suggested that there is an increasing trend of FM(trunk) and five anthropometric indices with aging; that age obviously influences the relationship of FM(trunk) and the anthropometric indices studied; and that the accuracy of predicting the FM(trunk) using five anthropometric indices combined is greater than using the five indices alone.

Correlation and prediction of trunk fat mass with four anthropometric indices in Chinese males.

To increase our understanding of the relationships of trunk fat mass (FMtrunk) and four anthropometric indices in Chinese males, 1090 males aged 20-40 years were randomly recruited from the city of Changsha, China. Waist circumference (WC) and hip circumference (HC) were measured using standardized equipment, and three other anthropometric indices of BMI, waist:hip ratio (WHR) and conicity index (CoI) were calculated using weight, height, HC and WC. FMtrunk (in kg) was measured using a Hologic QDR 4500 W dual-energy X-ray absorptiometry scanner. There was an increasing trend of FMtrunk, %FMtrunk (percentage of FMtrunk) and BMI, WC, WHR, CoI in successively older age groups (e.g. the mean FMtrunk values were 4.63 (SD 2.58), 5.39 (SD 2.74), 5.93 (SD 2.82), 6.57 (SD 2.94) in four 5-year age groups, respectively). FMtrunk and %FMtrunk were significantly correlated with four anthropometric indices with the Pearson's correlation coefficients ranging from 0.25 to 0.86. Principal component analysis was performed to form three principal components that interpreted over 99.5% of the total variation of four related anthropometric indices in all age groups, with over 65% of the total variation accounted by principal component 1. Multiple regression analyses showed that three principal components explained a greater variance (R(2) 70.0-80.1%) in FMtrunk than did BMI or WC alone (R(2) 57.8-74.1%). The present results suggest that there is an increasing trend of FMtrunk and four anthropometric indices in successively older age groups; that age has important effects on the relationships of FMtrunk and studied anthropometric indices; and that the accuracy of predicting FMtrunk using four anthropometric indices is higher than using BMI or WC alone.

Receiver-operating characteristic analyses of body mass index, waist circumference and waist-to-hip ratio for obesity: Screening in young adults in central south of China.

BACKGROUND & AIMS: Recent data suggest that current obesity diagnostic criterion based on body mass index (BMI) above 30 in Caucasians may not be appropriate for Asian populations. Our aim was to identify the usefulness of BMI, waist circumference (WC) and waist-to-hip ratio (WHR) in screening for obesity in an Asian population. METHODS: A cross-sectional sample of 1109 males and 879 females aged 20-45-yr were recruited. Height, weight, WC, hip circumference and percentage body fat (PBF) were measured in all subjects. Then receiver-operating characteristic analyses were used to evaluate the performances of the three anthropometric indices. RESULTS: BMI, WC and WHR showed strong positive correlation with PBF (r=0.47-0.75) in both males and females within both age groups. True-positive rates ranged from 82.4% to 94.1% and 68.8% to 86.3% in males and females, respectively. True-negative rates ranged from 64.1% to 84.7% and from 56.9% to 79.0%, respectively. The areas under the curves (AUCs) for WC and BMI were high (0.76-0.92) in both sexes and divided age groups (20-30-yr and 31-45-yr), and those for WHR were a little lower (0.74-0.88). CONCLUSIONS: BMI and WC are two important predictors for obesity in Chinese, and WHR is an alternative.

The VDR, COL1A1, PTH, and PTHR1 gene polymorphisms are not associated with bone size and height in Chinese nuclear families.

We tested the relationship of the ApaI, Eco31I, BstBI, and (AAAG)n polymorphisms in the vitamin D receptor (VDR), collagen type I alpha-1 (COL1A1), parathyroid hormone (PTH), and parathyroid hormone (PTH)/PTH-related peptide receptor (PTHR1) genes with variations in bone size (BS) and height. Population stratification, total-family association, and within-family association were used to test these relationships in 400 Chinese nuclear families with a total of 1256 individuals. The BS at hip and spine was measured using a Hologic QDR 2000 dual-energy X-ray absorptiometry (DXA) scanner. The minor allele frequencies were 29.2%, 36.0%, and 14.0% for the VDR-ApaI, COL1A1-Eco31I, and PTH-BstBI markers, respectively. (AAAG)5 and (AAAG)6 of the PTHR1 gene are two major alleles in the Chinese people. Significant population stratification was found between the spine BS and PTHR1-(AAAG)5 (P = 0.048) and PTHR1-(AAAG)6 (P = 0.023), as well as between PTHR1-(AAAG)5 and height (P = 0.048), but we did not detect any significant within-family association or total-family association between the VDR, COL1A1, PTH, and PTHR1 gene polymorphisms and the variations in BS and height in our sample. Our results do not support that the VDR, COL1A1, PTH, and PTHR1 genes have an important influence on the variation in BS and height in our Chinese population.

Bone mineral density and five prominent candidate genes in Chinese men: associations, interaction effects and their implications.

OBJECTIVES: Osteoporosis constitutes a serious health problem in old people. Bone mineral density (BMD) is determined by multiple genetic and environmental factors. The genetic control of BMD and osteoporosis is better understood in women, but much less in men. The present study evaluated the relationship of COL1A2, BGP, IL-6, AHSG and PTH genes defined by MspI, HindIII, BsrBI, SacI and BstBI restriction enzymes, respectively, with BMD in Chinese males. METHODS: A total of 258 unrelated healthy Chinese men aged 50-80 years were recruited. BMD at spine (L1-4) and femoral neck were measured by a Hologic 2000+ densitometer and adjusted by significant covariates of age, height and weight. All the subjects were genotyped at the upper five polymorphic sites by PCR-RFLP procedure. RESULTS: We revealed significant association of the AHSG gene with the spine BMD (P = 0.006), even after adjusting for multiple testing in our study. Carriers of 1*1 and 2*2 genotypes of AHSG gene had, respectively, approximately 5.1 and 8.1% higher spine BMD than those of 1*2 genotype. For the other four genes, no evidence of association was found (P > 0.10). No significant evidence of gene-by-gene interaction was found by two-way factorial ANOVA on the BMD variation. CONCLUSIONS: The results suggest that the AHSG gene is associated with the spine BMD in Chinese men. The present study represents the first effort to simultaneously investigate the effects of single gene locus as well as gene-by-gene interactions of multiple genes on BMD variation in Chinese men.

The (GT)n polymorphism and haplotype of the COL1A2 gene, but not the (AAAG)n polymorphism of the PTHR1 gene, are associated with bone mineral density in Chinese.

Collagen type I alpha2 (COL1A2) and parathyroid hormone (PTH)/PTH-related peptide receptor (PTHR1) are two prominent candidate genes for bone mineral density (BMD). To test their importance for BMD variation in Chinese, we recruited 388 nuclear families composed of both parents and at least one healthy daughter with a total of 1,220 individuals, and simultaneously analyzed population stratification, total-family association, and within-family association between BMD at the spine and hip and the (GT)n marker in the intron 1 of the COL1A2 gene and the (AAAG)n marker in the P3 promoter of PTHR1 gene. We also performed these association analyses with haplotypes of the MspI and (GT)n polymorphisms in the COL1A2 gene. Significant within-family association was found between the M(GT)12 haplotype and trochanter BMD (P<0.001). Individuals with this haplotype have, on average, 9.53% lower trochanter BMD than the non-carriers. Suggestive evidence of the within-family association was detected between the (GT)17 allele and BMD at the spine (P=0.012), hip (P=0.011), femoral neck (P=0.032), trochanter (P=0.023), and intertrochanter (P=0.034). The association was confirmed by subsequent permutation tests. For the association, the proportion of phenotypic variance explained by the detected markers ranged from 1.2 to 3.9%, with the highest 3.9% at the trochanter for the M(GT)12 haplotype. This association indicates that there is strong linkage disequilibrium between the polymorphisms (MspI and GT repeat polymorphism) in the COL1A2 gene and a nearby quantitative trait locus (QTL) underlying BMD variation in Chinese, or the markers themselves may have an important effect on the variation of BMD. On the other hand, no significant within-family association, population stratification and total-family association between the PTHR1 polymorphism and BMD were found in our Chinese population.

Lack of association between the HindIII RFLP of the osteocalcin (BGP) gene and bone mineral density (BMD) in healthy pre- and postmenopausal Chinese women.

In Caucasian populations, the polymorphic restriction endonuclease HindIII marker of the osteocalcin (also known as BGP, for bone Gla protein) gene has recently been reported to be associated with bone mass, a major risk determinant of osteoporosis. In this study, we investigated the relationship between the BGP HindIII polymorphism and bone mineral density (BMD) in 388 premenopausal (31.18 +/- 5.92 years) and 169 postmenopausal (58.90 +/- 6.27 years) Chinese women. The BMD of spine and hip was measured by dual-energy X-ray absorptiometry (DEXA). All the study subjects were genotyped at the HindIII site of the BGP gene by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) detecting methods. The BGP alleles were designated according to the absence ( H) or presence ( h) of the HindIII restriction site. We did not find any significant difference in spine and hip BMD across BGP genotypes in either pre- or postmenopausal women or the combined group. Our result is not consistent with recent reports that the HindIII marker of the BGP gene is associated with osteoporosis. The different findings may reflect inter-population differences in the association (i.e., linkage disequilibrium) of molecular markers with BMD, and indicate the limit of using the HindIII marker of the BGP gene as a genetic marker to discern women susceptible to low BMD and thus osteoporosis in Chinese.

Polymorphisms of four bone mineral density candidate genes in Chinese populations and comparison with other populations of different ethnicity.

Studies on polymorphisms of candidate genes and their association with bone mineral density (BMD) have been reported in many populations, but few have been reported in Chinese populations. We investigated polymorphisms of the following five commonly used markers of four prominent BMD candidate genes with the purpose of identifying useful genetic markers for osteoporosis genetic research in Chinese: the Sp1 and RsaI polymorphisms of the collagen type 1 alpha l (Col1a1) gene, the -174G/C promoter polymorphism of the interleukin 6 (IL-6) gene, the Asn363Ser polymorphism of the glucocorticoid receptor (GR) gene, and the T --> C polymorphism in intron 5 of the transforming growth factor beta(1) (TGF-beta(1)) gene. We evaluated these polymorphisms using PCR-RFLP in samples of at least 124 random individuals. We compared the polymorphisms of these five markers with other populations using the chi(2) test and Fisher's exact two-tailed test. For the RsaI polymorphism, only three heterozygotes but no variant homozygote were identified. For the -174G/C polymorphic site, only one GC heterozygote and no CC homozygote were found. Alleles s, Ser, and A(1) at the Sp1, Asn363Ser, and T --> C marker sites that have been found to be polymorphic in other populations were not found in Chinese. Significant differences of allele and genotype frequency distributions were observed at these polymorphisms ( P < 0.001) after comparing with other populations. Our results suggest that variant alleles of the five markers are absent or too rare to be useful genetic makers in Chinese, despite the fact that they have been commonly used as polymorphic markers in osteoporosis genetic research in other populations.