Identification of causal metabolites related to multiple autoimmune diseases.

Observational studies provide evidence that metabolites may be involved in the development of autoimmune diseases (ADs), but whether it is causal is still unknown. Based on the large-scale genome-wide association studies (GWAS) summary statistics, we performed two-sample Mendelian randomization (MR) to evaluate the causal associations between human blood metabolites and multiple ADs, which were inflammatory bowel disease (IBD), ulcerative colitis (UC), crohns disease (CD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), multiple sclerosis (MS), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). After Bonferroni adjustment, we identified 6 causal features of metabolites, i.e., glycerol 2-phosphate for T1D, hexadecanedioate, phenylacetylglutamine and laurylcarnitine for RA, glycine and arachidonate (20:4n6) for CD. Comprehensive sensitive analysis was further performed to validate the robustness of associations. We also observed some overlaps of metabolites among different ADs, implying similar or shared underlying mechanisms in such pathogenic processes. Multivariable MR analysis was then conducted to avoid potential pleiotropic effect of other complex traits. After controlling for several common traits, multivariable MR analysis ruled out most of potential pleiotropic effects and validated independence of identified metabolites. Finally, metabolic pathway analysis was performed based on suggestive metabolites for each AD respectively and a total of seven metabolic pathways were identified. In conclusion, this study provided novel insights into investigating causal role of blood metabolites in development of multiple ADs through a comprehensive genetic pathway.

Unraveling the relationship between high-sensitivity C-reactive protein and frailty: evidence from longitudinal cohort study and genetic analysis.

BACKGROUND: This study aimed to investigate the association of high-sensitivity C-reactive protein (hs-CRP) with incident frailty as well as its effects on pre-frailty progression and regression among middle-aged and older adults. METHODS: Based on the frailty index (FI) calculated with 41 items, 6890 eligible participants without frailty at baseline from China Health and Retirement Longitudinal Study (CHARLS) were categorized into health, pre-frailty, and frailty groups. Logistic regression models were used to estimate the longitudinal association between baseline hs-CRP and incident frailty. Furthermore, a series of genetic approaches were conducted to confirm the causal relationship between CRP and frailty, including Linkage disequilibrium score regression (LDSC), pleiotropic analysis, and Mendelian randomization (MR). Finally, we evaluated the association of hs-CRP with pre-frailty progression and regression. RESULTS: The risk of developing frailty was 1.18 times (95% CI: 1.03-1.34) higher in participants with high levels of hs-CRP at baseline than low levels of hs-CRP participants during the 3-year follow-up. MR analysis suggested that genetically determined hs-CRP was potentially positively associated with the risk of frailty (OR: 1.06, 95% CI: 1.03-1.08). Among 5241 participants with pre-frailty at baseline, we found pre-frailty participants with high levels of hs-CRP exhibit increased odds of progression to frailty (OR: 1.39, 95% CI: 1.09-1.79) and decreased odds of regression to health (OR: 0.84, 95% CI: 0.72-0.98) when compared with participants with low levels of hs-CRP. CONCLUSIONS: Our results suggest that reducing systemic inflammation is significant for developing strategies for frailty prevention and pre-frailty reversion in the middle-aged and elderly population.

PKM2 is a Novel Osteoporosis-Associated Protein in Chinese.

Purpose:Osteoporosis is characterized by low bone mineral density (BMD) and high risk of osteoporotic fracture (OF). Peripheral blood monocytes (PBM) can differentiate into osteoclasts to resorb bone. This study was to identify PBM-expressed proteins significant for osteoporosis in Chinese Han elderly population (>65 years), and focused on two phenotypes of osteoporosis: low BMD and OF. METHODS: Label-free quantitative proteomics was employed to profile PBM proteome and to identify differentially expressed proteins (DEPs) between OF (N=27) vs. non-fractured (NF, N=24) subjects and between low BMD (N=12) vs. high BMD (N=12) subjects in women. Western blotting (WB) was conducted to validate differential expression, and ELISA to evaluate translational value for secretory protein of interest. RESULTS: We discovered 59 DEPs with fold change (FC)>1.3 (P<1×10-5), and validated the significant up-regulation of pyruvate kinase isozyme 2 (PKM2) with osteoporosis (P<0.001). PKM2 protein upregulation with OF was replicated with PBM in men (P=0.04). Plasma PKM2 protein level was significantly elevated with OF in an independent sample (N=100, FC=1.68, P=0.01). Pursuant functional assays showed that extracellular PKM2 protein supplement not only promoted monocyte trans-endothelial migration, growth, and osteoclast differentiation (marker gene expression), but also inhibited osteoblast growth, differentiation (ALP gene expression), and activity. CONCLUSION: The above findings suggest that PKM2 protein is a novel osteoporosis-associated functional protein in Chinese Han elderly population. It may serve as a risk biomarker and drug target for osteoporosis.

Rheumatoid arthritis and osteoporosis: shared genetic effect, pleiotropy and causality.

Rheumatoid arthritis (RA) is associated with increased localized and generalized bone loss, but the complex genetic mechanism between them is still unknown. By leveraging large-scale genome-wide association studies summary statistics and individual-level datasets (i.e. UK Biobank), a series of genetic approaches were conducted. Linkage disequilibrium score regression reveals a shared genetic correlation between RA and estimated bone mineral density (eBMD) (rg = -0.059, P = 0.005). The PLACO analysis has identified 74 lead (8 novel) pleiotropic loci that could be mapped to 99 genes, the genetic functions of which reveal the possible mechanism underlying RA and osteoporosis. In European, genetic risk score (GRS) and comprehensive Mendelian randomization (MR) were utilized to evaluate the causal association between RA and osteoporosis in European and Asian. The increase in GRS of RA could lead to a decrease of eBMD (beta = -0.008, P = 3.77E-6) and a higher risk of facture [odds ratio (OR) = 1.012, P = 0.044]. MR analysis identified that genetically determined RA was causally associated with eBMD (beta = -0.021, P = 4.14E-05) and fracture risk (OR = 1.036, P = 0.004). Similar results were also observed in Asian that osteoporosis risk could be causally increased by RA (OR = 1.130, P = 1.04E-03) as well as antibodies against citrullinated proteins-positive RA (OR = 1.083, P = 0.015). Overall, our study reveals complex genetic mechanism between RA and osteoporosis and provides strong evidence for crucial role of RA in pathogenesis of osteoporosis.

A novel long non-coding RNA, lnc-RNU12, influences the T-cell cycle via c-JUN and CCNL2 in rheumatoid arthritis.

OBJECTIVES: Long non-coding RNAs (lncRNAs) play important roles in RA pathogenesis. However, specific lncRNAs that regulate gene expression in RA pathogenesis are poorly known. This study was undertaken to characterize a novel lncRNA (lnc-RNU12) that has a lower-than-normal expression level in RA patients. METHODS: We performed initial genome-wide lncRNA microarray screening in peripheral blood mononuclear cells from 28 RA cases and 18 controls. Multiple methods were used to validate the detected associations between lncRNAs and RA. Furthermore, we identified the source and characteristics of the highlighted lncRNAs, detected the target genes, and determined the functional effect on immune cells through lncRNA knock-down in Jurkat T cell lines. RESULTS: lnc-RNU12 was downregulated in peripheral blood mononuclear cells and T cell subtypes of RA patients and was genetically associated with RA risk. lnc-RNU12 mediates the effect of microbiome alterations on RA risk. Activation of T cells caused low expression of lnc-RNU12. Knock-down of lnc-RNU12 in Jurkat T cells caused cell cycle S-phase arrest and altered the expression of protein-coding genes related to the cell cycle and apoptosis (e.g. c-JUN, CCNL2, CDK6, MYC, RNF40, PKM, VPS35, DNAJB6 and FLCN). Finally, c-JUN and CCNL2 were identified as target genes of lnc-RNU12 at the mRNA and protein expression levels. RNA-binding protein immunoprecipitation assays verified the interaction between lnc-RNU12 and the two proteins (c-Jun and cyclin L2) in Jurkat cells. CONCLUSIONS: Our study suggested that lnc-RNU12 was involved in the pathogenesis of RA by influencing the T cell cycle by targeting c-JUN and CCNL2.

Establishment of reference intervals for bone turnover markers in healthy Chinese older adults.

BACKGROUND: Reference ranges for bone turnover markers (BTMs) are still lacking in the healthy Chinese population. AIM: To establish reference intervals for BTMs and to investigate the correlations between BTMs and bone mineral density (BMD) in Chinese older adults. SUBJECTS AND METHODS: A community-based cross-sectional study was conducted among 2511 Chinese subjects aged over 50 yrs residing in Zhenjiang, Southeast China. Reference intervals for BTMs (i.e. procollagen type I N-terminal propeptide, P1NP; ß cross-linked C-terminal telopeptide of type I collagen, ß-CTX) were calculated as the central 95% range of all measurements in Chinese older adults. RESULTS: The reference intervals of P1NP, ß-CTX and P1NP/ß-CTX were 15.8-119.9 ng/mL, 0.041-0.675 ng/mL and 49.9-1261.5 for females and 13.6-111.4 ng/mL, 0.038-0.627 ng/mL and 41.0-1269.1 for males, respectively. In the multiple linear regression analysis, only ß-CTX was negatively associated with BMD after adjusting for age and body mass index (BMI) in both sex-stratified groups (all p < .05). CONCLUSION: This study established age- and sex-specific reference intervals for BTMs in a large sample of healthy Chinese participants ≥ 50 and < 80 years of age and explored the correlations between BTMs and BMD, which provides an effective reference for the assessment of bone turnover in the clinical practice of osteoporosis.

Why SNP rs3755955 is associated with human bone mineral density? A molecular and cellular study in bone cells.

SNP rs3755955 (major/minor allele: G/A) located in Iduronidase-Alpha-L- (IDUA) gene was reported to be significant for human bone mineral density (BMD). This follow-up study was to uncover the underlying association mechanism through molecular and cellular functional assays relevant to bone. We tested the effects of single nucleotide polymorphisms (SNP) rs3755955 (defined allele G as wild-type and allele A as variant-type) on osteoblastic and osteoclastic functions, as well as protein phosphorylation in stably transfected human fetal osteoblast (hFOB) cell and mononuclear-macrophage (RAW264.7) cell. In hFOB cells, transfection with variant-type IDUA significantly decreased osteoblastic gene expression (OPN, COL1A1 and RANKL) (p < 0.01), impeded cell proliferation (p < 0.05), stimulated cell apoptosis (p < 0.001) and decreased ALP enzyme activity, as compared with that of wild-type IDUA transfection. In RAW264.7 cells, transfection with variant-type IDUA significantly inhibited cell apoptosis (p < 0.01), promoted osteoclastic precursor cell migration (p < 0.0001), growth (p < 0.01), osteoclastic gene expression (TRAP, RANK, Inte-αv and Cath-K) (p < 0.05) and TRAP enzyme activity (p < 0.001), as compared with that of wild-type IDUA transfection. In both hFOB and RAW264.7 cells, the total protein and IDUA protein-specific phosphorylation levels were significantly reduced by variant IDUA transfection, as compared with that of wild-type IDUA transfection (p < 0.05). Variant allele A of phosSNP rs3755955 in IDUA gene regulates protein phosphorylation, inhibits osteoblast function and promotes osteoclastic activity. The SNP rs3755955 could alter IDUA protein phosphorylation, significantly regulates human osteoblastic and osteoclastic gene expression, and influences the growth, differentiation and activity of osteoblast and osteoclast, hence to affect BMD.

Body Surface Area (BSA) is a Better Osteoporosis Associated Anthropometric Parameter Than Other Anthropometric Parameters in Elderly Population.

Body surface area (BSA) is widely used for adjusting drug dose, while few studies have yet systematically evaluated its association with osteoporosis and compared its advantage with other anthropometric parameters in osteoporotic risk prediction. A total of 10,021 Chinese individuals aged over 65 years were enrolled in our study. Bone mineral density (BMD) was measured, and demographic information was also collected. Pearson correlation analysis, receiver operating characteristic (ROC) curves and predictive analysis were performed to assess the clinical practice of BSA for osteoporosis. BSA had the strongest correlation with BMD (0.544, p < 0.001) compared with conventional anthropometric indices. Besides, BSA had the highest power in osteoporosis prediction, with an area under the curve (AUC) reaching 0.81. After incorporating BSA into the osteoporosis risk prediction model, the AUC improved from 0.82 to 0.83 (p < 0.01). We found BSA provided additional diagnostic value beyond conventional anthropometric information with continuous and category NRIs were 30.40% (p < 0.01) and 3.29% (p < 0.01), respectively, and the IDI was 1.85% (p < 0.01). BSA was positively associated with osteoporosis and showed superior discriminative ability for osteoporosis risk prediction compared with other anthropometric parameters in the Chinese elderly population.

Does obesity mediate the relationship between diabetes and osteoporosis in Chinese elderly population?

OBJECTIVES: Diabetes mellitus (DM), osteoporosis (OP), and obesity (OB) are three complex diseases. OB is associated with both DM and OP, but it is unclear whether OB mediates association between DM and OP. The study aimed to investigate the potential mediation effects of OB on association between DM and bone mineral density (BMD) by the causal inference tests (CIT). METHODS: A total of 5682 Chinese aged over 65 years were enrolled in an ongoing cohort: Osteoporosis Preventive Project (OPP). Obesity-related indexes, including body mass index (BMI), waist circumference, and waist circumference-hip circumference-ratio (WHR), and BMD at total hip (TH) and femur neck (FN) were measured. RESULTS: Subjects with DM had significant greater values of age, weight, BMI, waist circumference, WHR, and BMD than non-DM subjects. BMD at TH and FN was significantly associated with DM (p < 0.05) with adjustment of age both in males and females. Further CIT showed that OB-related indexes (BMI, waist circumference, and WHR) are significantly mediators in the associations between DM and BMD in females, but not in males. Furthermore, the mediation effects of waist circumference were detected on DM and TH BMD in the females of normal-weight group. CONCLUSIONS: Obesity-related indexes, especially waist circumference, serve as significant mediator(s) between DM and OP in Chinese female elderly. Diabetes increases BMD by increasing obesity-related indexes. The findings established the intermediate role of OB underlying the association between DM and OP in human population.

PhosSNPs-Regulated Gene Network and Pathway Significant for Rheumatoid Arthritis.

OBJECTIVES: Peripheral blood mononuclear cells (PBMCs) are critical for immunity and participate in multiple human diseases, including rheumatoid arthritis (RA). PhosSNPs are nonsynonymous SNPs influencing protein phosphorylation, thus probably modulate cell signaling and gene expression. We aimed to identify phosSNPs-regulated gene network/pathway potentially significant for RA. METHODS: We collected genome-wide phosSNP genotyping data and transcriptome-wide mRNA expression data from PBMCs of a Chinese sample. We discovered and verified with public datasets differentially expressed genes (DEGs) associated with RA, and replicated RA-associated SNPs in our study sample. We performed a targeted expression quantitative trait locus (eQTL) study on significant phosSNPs and DEGs. RESULTS: We identified 29 nominally significant eQTL phosSNPs and 83 target genes, and constructed comprehensive regulatory/interaction networks, highlighting the vital effects of two eQTL phosSNPs (rs371513 and rs4824675, FDR <0.05) and four critical node genes (HSPA4, NDUFA2, MRPL15, and ATP5O). Besides, two node/key genes NDUFA2 and ATP5O, regulated by rs371513, were significantly enriched in mitochondrial oxidative phosphorylation pathway. Besides, four pairs of eQTL effects were replicated independently in whole blood and/or transformed fibroblasts. CONCLUSIONS: The findings delineated a potential role of protein phosphorylation and genetic variations in RA and warranted the significant roles of phosSNPs in regulating RA-associated genes expression in PBMCs. The results pointed out the relevance and significance of oxidative phosphorylation pathway to RA.

The effect of a body shape index (ABSI) and its interaction with low estimated glomerular filtration rate (eGFR) on osteoporosis in elderly Chinese.

BACKGROUND: Both obesity and chronic kidney disease (CKD) contribute to osteoporosis risk, but the effect of a newly developed index (e.g., a body shape index, ABSI) of central obesity and its interaction with low estimated glomerular filtration rate (eGFR) on osteoporosis remains unknown. METHODS: A total of 2534 Chinese individuals were enrolled in our ongoing cohort study: Osteoporosis Preventive Project. ABSI and eGFR were calculated as obesity-related indexes and renal function markers, respectively. A logistic regression model was used to estimate the association between osteoporosis and related clinical parameters (e.g., ABSI, eGFR), and to assess the additive and multiplicative interactions between risk factors and osteoporosis. Relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP) and synergy index (SI) were calculated to assess the additive interaction. RESULTS: High ABSI was significantly associated with an increased risk of osteoporosis in participants compared with the lowest quartile of ABSI in both crude and adjusted models. Individuals in the lower quartiles of eGFR had a significantly increased risk of osteoporosis compared with those in the highest quartiles in crude models. After adding age and other variables in the model, the association was abolished. In addition, after adjusting for variables, high ABSI with low eGFR (RERI: 0.45, 95% CI: 0.15-0.75; AP: 0.39, 95% CI: 0.17-0.60) still displayed a noticeable interaction on the risk of osteoporosis. The multiplicative interactive effect between high ABSI with low eGFR on osteoporosis was statistically significant in the multivariable-adjusted model (P < 0.05). CONCLUSION: Our study indicated that higher ABSI increases the risk of osteoporosis independently and synergistically with low eGFR in Chinese elderly adults. The findings increase our understanding of the interactions of osteoporosis risk factors and may help provide potential interventions for osteoporosis.

Novel microbiota-related gene set enrichment analysis identified osteoporosis associated gut microbiota from autoimmune diseases.

INTRODUCTION: Gut microbiota is now considered to be a hidden organ that interacts bidirectionally with cellular responses in numerous organs belonged to the immune, bone, and nervous systems. Here, we aimed to investigate the relationships between gut microbiota and complex diseases by utilizing multiple publicly available genome-wide association. MATERIALS AND METHODS: We applied a novel microbiota-related gene set enrichment analysis approach to detect the associations between gut microbiota and complex diseases by processing genome-wide association studies (GWASs) data sets of six autoimmune diseases (including celiac disease (CeD), inflammatory bowel diseases (IBD), multiple sclerosis (MS), primary biliary cirrhosis (PBC), type 1 diabetes (T1D) and primary sclerosing cholangitis (PSC)) and osteoporosis (OP). RESULTS: The family Oxalobacteraceae and genus Candidatus_Soleaferrea were found to be correlated with all of the six autoimmune diseases (FDR adjusted P < 0.05). Moreover, we observed that the six autoimmune diseases except PBC shared 3 overlapping features (including family Peptostreptococcaceae, order Gastranaerophilales and genus Romboutsia). For all of the six autoimmune diseases and BMDs (LS-BMD and TB-BMD), an association signal was observed for genus Candidatus_Soleaferrea (FDR adjusted P < 0.05). Notably, FA / FN-BMD shared the maximum number of overlapping microbial features (e.g., genus Ruminococcaceae_UCG009, Erysipelatoclostridium and Ruminococcaceae_UCG013). CONCLUSION: Our study found that part of the gut microbiota could be novel regulators of BMDs and autoimmune diseases via the effects of its metabolites and may lead to a better understanding of the role played by gut microbiota in the communication of the microbiota-skeletal/immune-gut axis.

The obesity indices mediate the relationships of blood lipids and bone mineral density in Chinese elders.

OBJECTIVE: It is unclear what role does obesity (OB) index play between blood lipid and bone mineral density (BMD). SUBJECTS: This study recruited a total of 4,558 Chinese elders >65 years. OB indices: waist circumference (WC), body mass index (BMI), waist-hip-ratio (WHR); blood lipid parameters: low density lipoprotein (LDL); total cholesterol (TC), triglyceride (TG), and BMDs at femur neck (FN), total hip (TH), and lumbar spine (LS) were measured. The t-test and multiple linear regression analysis were used to detect the differences of variables. Casual inference test (CIT) were performed to test potential mediators underlying the associations between blood lipid and BMD. RESULTS: The blood lipids were positively associated with BMD (p < 0.05) after adjustment of age and sex (Model 1) both in total subjects and in sex-stratified subjects. The CIT showed that OB indices had significant mediation effects on the associations between blood lipid (TG and LDL) and BMD in total subjects and males. Comparably, the correlations of TG and BMD are most likely mediated by BMI and WC. CONCLUSIONS: This study represented the first effort to report that OB indices, especially BMI and WC, served as significant mediators between blood lipid (TG and LDL) and BMD in Chinese elderly.

Identification of Potential Pleiotropic Genes for Immune and Skeletal Diseases Using Multivariate MetaCCA Analysis.

Background: Immune and skeletal systems physiologically and pathologically interact with each other. Immune and skeletal diseases may share potential pleiotropic genetics factors, but the shared specific genes are largely unknown. Objective: This study aimed to investigate the overlapping genetic factors between multiple diseases (including rheumatoid arthritis (RA), psoriasis, osteoporosis, osteoarthritis, sarcopenia, and fracture). Methods: The canonical correlation analysis (metaCCA) approach was used to identify the shared genes for six diseases by integrating genome-wide association study (GWAS)-derived summary statistics. The versatile Gene-based Association Study (VEGAS2) method was further applied to refine and validate the putative pleiotropic genes identified by metaCCA. Results: About 157 (p<8.19E-6), 319 (p<3.90E-6), and 77 (p<9.72E-6) potential pleiotropic genes were identified shared by two immune diseases, four skeletal diseases, and all of the six diseases, respectively. The top three significant putative pleiotropic genes shared by both immune and skeletal diseases, including HLA-B, TSBP1, and TSBP1-AS1 (p

The different correlations between obesity and osteoporosis after adjustment of static mechanical loading from weight and fat free mass.

OBJECTIVES: To explore complex correlations between obesity (OB) and osteoporosis (OP) after adjustment of static mechanical loading from weight and fat free mass (FFM). METHODS: A total of 3749 Chinese aged ≥65 years were selected from our ongoing cohort study. OB indices and bone mineral density (BMD) were measured for each subject. Linear regression analyses were performed to explore the correlations between OB indices and OP under three adjustment models (unadjusted, adjusted with weight and adjusted with FFM). RESULTS: Under no adjustment, three general obesity indices (body mass index: BMI, fat mass: FM, and percentage FM: PFM) were positively associated with BMD at three skeletal sites (P<0.001) in the regression analyses. However, after the adjustment with weight, these associations were mostly significant but reverse i.e., negatively in direction. After adjustment with FFM, the three indices were still positively and significantly (P<0.001) associated with BMD but regression coefficients were smaller compared to the unadjusted associations. Similar associations were observed for central adiposity and lower limb adiposity indices. CONCLUSIONS: The combined relation of OB to OP due to the physiological factors secreted from adipose tissues and the static mechanical loading from FM is positive in direction.

Global Public Interests and Dynamic Trends in Osteoporosis From 2004 to 2019: Infodemiology Study.

BACKGROUND: With the prolonging of human life expectancy and subsequent population aging, osteoporosis (OP) has become an important public health issue. OBJECTIVE: This study aimed to understand the global public search interests and dynamic trends in "osteoporosis" using the data derived from Google Trends. METHODS: An online search was performed using the term "osteoporosis" in Google Trends from January 1, 2004, to December 31, 2019, under the category "Health." Cosinor analysis was used to test the seasonality of relative search volume (RSV) for "osteoporosis." An analysis was conducted to investigate the public search topic rising in RSV for "osteoporosis." RESULTS: There was a descending trend of global RSV for "osteoporosis" from January 2004 to December 2014, and a slowly increasing trend from January 2015 to December 2019. Cosinor analysis showed significant seasonal variations in global RSV for "osteoporosis" (P=.01), with a peak in March and a trough in September. In addition, similar decreasing trends of RSV for "osteoporosis" were found in Australia, New Zealand, Ireland, and Canada from January 2004 to December 2019. Cosinor test revealed significant seasonal variations in RSV for "osteoporosis" in Australia, New Zealand, Canada, Ireland, UK, and USA (all P<.001). Furthermore, public search rising topics related to "osteoporosis" included denosumab, fracture risk assessment tool, bone density, osteopenia, osteoarthritis, and risk factor. CONCLUSIONS: Our study provided evidence about the public search interest and dynamic trends in OP using web-based data, which would be helpful for public health and policy making.

Newly developed hip geometry parameters are associated with hip fracture.

BACKGROUND: The conventional and newly developed geometry parameters at the femoral neck have formed a large geometry profile and their relationship with hip fracture was largely unknown. We aimed to evaluate the relationship between the geometry profile and hip fracture in Chinese. METHODS: The hip geometry profile contains seven conventional geometry parameters at femoral neck (FN) and thirty newly developed parameters at three sub-regions (Narrow Neck, NN; Intertrochanter, IT; Femoral shaft, FS) of the total hip. Based on 6294 recruited Chinese (≥65 years), 97 subjects with osteoporotic fracture (OF) history and 388 matched controls were selected. The t test, Chi-square statistic, conditional logistic regression model were used. RESULTS: Three geometric parameters (endocortical diameter, ED; cortical thickness, CT; buckling ratio, BR) have consistent differences at all the sites between the cases and controls (p < 0.01). Conventional geometry parameters (e.g., cross-sectional area, CSA; BR) and the newly developed parameters (e.g., NN_ED, NN_Outer Diameter, IT_ED) were identified as the risk factors of hip fracture independent of BMD. The additional predictive ability of the hip geometric parameters, over BMD alone, (receiver operating characteristic curve (ROC) analysis) was improved. Especially at NN, the area of ROC used single NN_BMD is only 0.596, but increased rapidly at 0.705 when combined with the hip geometric parameters. CONCLUSIONS: This study found that three newly developed hip geometry parameters are associated with hip fracture. The results will increase our understanding of the determinants of fracture and provide potential clue for future prevention of fracture in Chinese Population.

Protein array test detected three osteoporosis related plasma inflammatory cytokines in Chinese postmenopausal women.

Inflammatory cytokines were involved in pathological conditions of osteoporosis (OP). However, the specific OP-associated inflammatory cytokines are still awaiting to be detected by using a systemic method. Herein, we adopted an extreme sampling scheme and examined inflammatory cytokines between subjects with low and high bone mineral density (BMD) through protein microarray. First, 8 candidate cytokines including B lymphocyte chemoattractant (BLC), osteopontin (OPN) and insulin-like growth factor-binding protein 4 (IGFBP4) were identified in the discovery extreme sampling subgroup. Then, the different expressions for BLC, OPN and IGFBP4 were validated and replicated in two independent extreme sampling subgroups. Further functional experiments showed that the cytokine BLC was involved in bone metabolism by inhibiting bone formation and promoting bone resorption. Together, this study further revealed that inflammatory cytokines were closely related with OP, and that they highlighted critical roles of BLC in the pathogenesis of OP.

Global correlation analysis for miRNA and protein expression profiles in human peripheral blood mononuclear cells.

Micro-RNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression at protein level by protein translation inhibition or mRNA degradation. However, the global correlation patterns between miRNA and protein have not been studied yet. To establish the global correlation patterns in human peripheral blood mononuclear cells (PBMCs), this study conducted multiple types of miRNA-protein correlation analyses in 28 Chinese subjects. Pearson correlation analysis showed a negative but relatively small global correlation in each subject. Among the 371 constructed miRNA-protein pairs (60 unique miRNAs, and 150 unique proteins), 10.5% of pairs have significant correlations (P < 0.05). Some highlighted miRNAs (e.g., hsa-miR-590-3p, hsa-miR-520d-3p) exerted significant regulation on multiple genes. Simultaneously, some genes (e.g., HSP90B1) were targeted by multiple miRNAs. The target genes associated with miRNAs tend to enrich in some important GO terms: biological processes (e.g., gene expression, protein binding and RNA binding), and molecular functions (protein binding: GO:0005515; RNA binding: GO:0003723). The results provided a global view of the miRNA-protein expression correlation profile in human PBMCs, which would facilitate in-depth investigation of biological functions of key miRNAs/proteins and better understanding of the pathogenesis underlying PBMC related diseases.

Why SNP rs227584 is associated with human BMD and fracture risk? A molecular and cellular study in bone cells.

A large number of SNPs significant for osteoporosis (OP) had been identified by genome-wide association studies. However, the underlying association mechanisms were largely unknown. From the perspective of protein phosphorylation, gene expression regulation, and bone cell activity, this study aims to illustrate association mechanisms for representative SNPs of interest. We utilized public databases and bioinformatics tool to identify OP-associated SNPs which potentially influence protein phosphorylation (phosSNPs). Associations with hip/spine BMD, as well as fracture risk, in human populations for one significant phosSNP, that is, rs227584 (major/minor allele: C/A, EAS population) located in C17orf53 gene, were suggested in prior meta-analyses. Specifically, carriers of allele C had significant higher BMD and lower risk of low-trauma fractures than carriers of A. We pursued to test the molecular and cellular functions of rs227584 in bone through osteoblastic cell culture and multiple assays. We identified five phosSNPs significant for OP (P < 0.01). The osteoblastic cells, which was transfected with wild-type C17orf53 (allele C at rs227584, P126), demonstrated specific interaction with NEK2 kinase, increased expression levels of osteoblastic genes significantly (OPN, OCN, COL1A1, P < 0.05), and promoted osteoblast growth and ALP activity, in contrast to those transfected with mutant C17orf53 (allele A at rs227584, T126). In the light of the consistent evidences between the present functional study in human bone cells and the prior association studies in human populations, we conclude that the SNP rs227584, via altering protein-kinase interaction, regulates osteoblastic gene expression, influences osteoblast growth and activity, hence to affect BMD and fracture risk in humans.