Summary
Background
Osteoporosis is a prevalent skeletal disorder characterized by reduced bone mineral density and microarchitectural deterioration of bone tissue, resulting in bone fragility and ...low-trauma fractures. Imaging techniques are routinely used to detect low bone mass; however, they are unable to identify deterioration of bone quality. Recently, microRNAs have emerged as regulators of bone remodelling and potentially also as a new class of sensitive biomarkers of bone health to aid in diagnosis and treatment monitoring of osteoporosis.
Methods
To identify new plasma-based biomarkers associated with osteoporosis we analyzed microRNAs isolated from plasma samples of 74 postmenopausal women divided into osteoporotic (
N =
17) and control groups (
N =
57). A prior microRNA screening was performed where a few showed promise for further analysis. Quantitative polymerase chain reaction was used to investigate differences in expression of let-7d-5p, let-7e-5p, miR-30d-5p, miR-30e-5p, miR-126-3p, miR-148a-3p, miR-199a-3p, miR-423-5p and miR-574-5p between the two groups. Furthermore, correlation analysis between microRNA expression levels and patient bone mineral density measurements and fracture risk assessment tool (FRAX) as well as trabecular bone scores were performed.
Results
Expression of miR-148a-3p was significantly higher (
p
= 0.042) in the osteoporotic patient group compared to the controls. In addition, we identified correlations between miR-126-3p (ρ = 0.253,
p
= 0.032) and 423-5p (ρ = −0.230,
p
= 0.049) and parameters of bone quality and quantity.
Conclusion
The results from our study, together with the functional role of miR-148a-3p in bone suggest that this microRNA could be considered as a potential new plasma-based biomarker for pathological changes associated with osteoporosis.
Cathepsin K and MMP-9 are considered to be the most abundant proteases in osteoclasts. TRAP is a marker for osteoclasts, and there is increasing evidence of its proteolytic role in bone resorption. ...RANKL is a recently discovered regulator of osteoclast maturation and activity and induces expression of many genes. This study compared cathepsin K, MMP-9, TRAP, RANKL, OPG, and osteocalcin gene expression in the proximal femur of patients with osteoarthritis with that of patients with femoral neck fracture. Fifty-six patients undergoing arthroplasty because of osteoarthritis or femoral neck fracture were included in the study. Total mRNA was extracted from the bone samples obtained from the intertrochanteric region of the proximal femur. Real-time RT-PCR was used to quantify CTSK (cathepsin K), MMP-9 (matrix metalloproteinase 9), ACP5 (TRAP), TNFSF11 (RANKL), TNFRSF11B (OPG), and BGLAP (osteocalcin) mRNAs. The levels of mRNAs coding for MMP-9 and osteocalcin indicated higher expression in the osteoarthritic group (P = 0.011, P = 0.001, respectively), whereas RANKL expression and the ratio RANKL/OPG were both significantly lower in the osteoarthritic group than in the fracture group. Expression of cathepsin K, MMP-9, and TRAP relative to RANKL was significantly higher in the osteoarthritic group. Ratios of all three proteolytic enzymes relative to formation marker osteocalcin were higher in the fracture group. Gene expression of cathepsin K, MMP-9, TRAP, RANKL, OPG, and osteocalcin and the association between their mRNA levels pointed to higher bone resorption and bone formation in osteoarthritis, differences in balance between them, and differences in regulation of bone resorption in osteoarthritic and osteoporotic bone.
Accumulating evidence connects polycystic ovary syndrome (PCOS) with increased risk of cardiovascular disease. Endothelial dysfunction is present in PCOS and represents an early, reversible marker of ...cardiovascular damage. As androgens and renin-angiotensin-aldosterone system are implicated in the atherogenesis process of PCOS, we tested the hypothesis that treatment with spironolactone, an androgen and mineralocorticoid receptor blocking drug, might reverse endothelial dysfunction in PCOS.
A total of 30 non-obese PCOS patients, compared with 20 body mass index matched control subjects, were evaluated. PCOS patients were given spironolactone 100 mg daily in 21-day long intervals followed by a 7-day pause, for 6 months.
Flow-mediated dilatation (FMD), glyceryl trinitrate-induced dilatation, free testosterone, androstenedione, DHEA-sulfate, total, low-density lipoprotein (LDL)-, high-density lipoprotein-cholesterol, and triglycerides were determined at baseline and after 6 months.
Results are expressed as median (25-75th percentile). At baseline, FMD was significantly lower in PCOS patients than in controls: 6.0 (0.0-11.7) vs 10.2 (6.8-15.9) %, P=0.018. This difference disappeared after 6 months of spironolactone treatment, as FMD in PCOS patients significantly increased to 8.3 (5.7-10.3) %, P=0.034, and was no longer different from controls. In PCOS patients, serum androgen levels did not change during treatment, while total and LDL-cholesterol decreased significantly from 4.8 (4.1-5.1) mmol/l to 4.4 (3.9-4.8) mmol/l and from 2.5 (2.1-3.1) to 2.2. (2.1-2.5) mmol/l, P<0.05 and P<0.05 respectively.
Treatment with spironolactone normalized endothelial function and improved cholesterol levels in non-obese PCOS patients.
Genetic factors influencing the pathogenesis of osteoporosis are still largely unknown. We employed genome-wide gene expression approach in order to discover novel genes involved in the pathogenesis ...of osteoporosis. To this end, primary cultures of osteoblasts isolated from osteoporotic and non-osteoporotic human bone tissue samples were prepared. One thousand six hundred six genes were found to be differentially expressed, indicating increased demand for protein synthesis and decreased cell proliferation rate in osteoblasts from osteoporotic tissue as compared to osteoblasts from non-osteoporotic tissue. At first, top four genes, based on the microarray data and potential role in bone metabolism, were further studied in bone tissue samples of 55 patients. PTN and COL15A1 were both downregulated in osteoporotic bone tissue (6.2- and 3.4-fold, respectively, both p<0.05), while IBSP and CXCL2 were both upregulated (5.7-fold, p<0.05, and 2.1-fold, p>0.05). Further biostatistical analysis of the microarray data by gene set enrichment analysis suggested oxidative stress may have an important part in the pathogenesis of osteoporosis. Thus, secondly, we tested it by an in vitro assay on human osteosarcoma cell line cells treated with hydrogen peroxide. After 72 h of treatment with 500 microM hydrogen peroxide, the upregulation of the same genes involved in the response to oxidative stress as on the microarrays was observed: MT1G (metallothionein 1G, 22.1-fold, p<0.05), TXNRD1 (thioredoxin reductase 1, 3.7-fold, p<0.05), AOX1 (aldehyde oxidase 1, 24.5-fold, p<0.05) and GSR (glutathione reductase, 4.7-fold, p<0.05). Our results present a novel list of genes and metabolic pathways that may be associated with the pathogenesis of osteoporosis. PTN, CXCL2, COL15A1, IBSP, AOX1, MT1G, GSR and TXNRD1 are candidate genes for further studies in the assessment of the genetic susceptibility to osteoporosis. In addition, differences in protein synthesis, cell proliferation rate and response to oxidative stress may also be involved in the pathogenesis of osteoporosis.
1alpha,25-dihydroxyvitamin D(3) upregulates tumour necrosis factor superfamily member 11 (TNFSF11) that codes for the receptor activator of nuclear factor kappaB ligand (RANKL), and downregulates ...osteoprotegerin (OPG) expression. We have analyzed the individual effects of polymorphisms in the vitamin D receptor gene (VDR), OPG and TNFSF11, and searched for interactions between them. Six hundred and forty one subjects were evaluated: 239 osteoporotic and 228 non-osteoporotic post-menopausal, 57 pre-menopausal women and 117 elderly men. The subjects were genotyped for BsmI, FokI and Cdx2 in VDR, K3N in OPG and -290C>T, -643C>T and -693G>C in TNFSF11 gene. Bone mineral density (BMD) and biochemical markers were measured. In the osteoporotic women, femoral neck BMD (BMD-fn) showed associations with BsmI(VDR) and Cdx2(VDR) (P=0.015 and 0.047 respectively), and lumbar spine BMD (BMD-ls) with K3N(OPG) and -290C>T(TNFSF11) (P=0.021 and 0.017). No association with BMD was found in the non-osteoporotic women. In the pre-menopausal women, the Cdx2(VDR) polymorphism was associated with BMD-fn and total hip BMD (P=0.011 and 0.011). In elderly men, FokI(VDR) was associated with BMD-fn and BMD-ls (P=0.040 and 0.036). Interestingly, the -290C>T(TNFSF11)-K3N(OPG) combination was associated with BMD-th (P=0.041) in the osteoporotic women. In the non-osteoporotic women, the combination K3N(OPG)-Cdx2(VDR) was associated with BMD-ls, BMD-th and BMD-fn (P=0.032, 0.049 and 0.022), and the combination -290C>T(TNFSF11)-K3N(OPG) with BMD-fn (P=0.029). For the first time, the presence of gene-gene interactions between VDR, OPG and TNFSF11 genes was studied. Our results strongly suggest further confirmation of their combined influence on larger cohorts.
Abstract Objectives Osteoprotegerin (OPG) inhibits osteoclast function by acting as a decoy receptor for receptor activator of nuclear factor-κB ligand (RANKL), thus being an important candidate gene ...for osteoporosis. Three recent genome-wide association studies also identified the TNFRSF11B gene, coding for OPG, as playing a key role in bone mineral density (BMD) regulation. As variations in the TNFRSF11B gene could alter the susceptibility to osteoporosis, the aim of study was to investigate association of two TNFRSF11B gene polymorphisms with BMD and serum OPG concentration in postmenopausal women. Study design 478 postmenopausal women were genotyped for the presence of TNFRSF11B gene polymorphisms 245T > G (rs3134069) and 1181G > C (rs2073618). BMDs and serum OPG concentrations were measured. Results Two common haplotypes GT and CT occurred in 41.2% and 52.4% of subjects. In osteoporotic postmenopausal women, lumbar spine BMD was associated with polymorphisms 245T > G and 1181G > C, as well as with CT haplotype ( p values 0.013, 0.006 and 0.006, respectively). Additionally, femoral neck BMD showed the association with 245T > G ( p = 0.047). No other statistically significant associations with BMD were found for the studied SNPs and haplotypes. No association with serum OPG concentration was shown in any of the studied groups. Conclusions Our results suggest that, in postmenopausal osteoporosis, polymorphisms 245T > G and 1181G > C, as well as haplotype CT in TNFRSF11B gene influence BMD.
Genetic factors play an important role in the pathogenesis of osteoporosis. The genes involved are, however, still largely unknown. In the present study, we have investigated whether sequence ...variations in the estrogen receptor beta (
ERβ) gene are associated with bone mineral density (BMD) and biochemical markers of bone turnover in 79 Slovenian postmenopausal women with osteoporosis. We also assessed the response by BMD and bone markers to antiresorptive therapy with bisphosphonate alendronate. All eight exons of
ERβ gene were amplified by polymerase chain reaction and screened for mutations by single-strand conformation polymorphism analysis. Potentially mutated samples were found only in exon 5 and sequence analysis identified the presence of a silent mutation in codon 328 with a nucleotide substitution GTG to GTA. For easier detection of this silent mutation, the
RsaI restriction fragment length polymorphism analysis was developed. The frequencies of genotypes were as follows: Rr 5.1% and RR 94.9%. Between both genotypes, no significant differences in baseline lumbar spine and femoral neck BMD or in bone markers osteocalcin and deoxypyridinoline were observed. Similarly, no significant difference between RR and Rr genotypes in BMD or bone markers after 1 year of therapy was found. The increase in lumbar spine BMD after therapy was the only parameter that approached statistical significance (
P=0.099). Patients with genotype Rr showed a smaller increase compared to those with RR. Our results suggest that
RsaI polymorphism of
ERβ gene is probably not an important genetic determinant of BMD and does not significantly influence the responsiveness to alendronate therapy.
Receptor activator of nuclear factor κB (RANK) is one of the proteins in regulation of osteoclastogenesis via RANK/RANKL/OPG. Gene that codes for RANK protein (
TNFRSF11A) was associated with ...osteoporotic fractures in a recent genome-wide association study. As variations in the RANK gene could alter its expression and activity, the aim of our study was to evaluate the influence of four RANK gene polymorphisms on bone mineral density (BMD) and biochemical markers.
We evaluated 467 postmenopausal women and 117 elderly men. All subjects were genotyped for the presence of RANK polymorphisms −670G>C, +34694C>T, +34901G>A and +35966insdelC. BMD and biochemical markers were measured.
Significant associations of +35966insdelC with BMD at lumbar spine (BMD-ls), total hip (BMD-th) and femoral neck (BMD-fn) were found in postmenopausal women (
p
=
0.020, 0.024 and 0.034), but not in men. Significant gene–gene interaction was proved for two RANK polymorphisms in combination with OPG and RANKL polymorphisms studied previously in postmenopausal women. Firstly, RANK/RANKL (+34901G>A/−290C>T) combination was associated with BMD-fn, BMD-th and BMD-ls (
p
=
0.034, 0.016 and 0.050), and secondly, RANK/OPG combination (+35966insdelC/K3N) showed influence on BMD-fn and BMD-ls (
p
=
0.043 and 0.039).
Our results suggest that gene–gene interactions between RANK and OPG, and RANK and RANKL influence BMD in postmenopausal women.
The Wnt pathway has a bifunctional role in bone mass regulation, influencing osteoblasts and osteoclasts. The Wnt pathway genes are therefore candidate genes for susceptibility to osteoporosis. In ...our study, we focused on the effects of polymorphisms in selected Wnt pathway genes: low-density lipoprotein receptor-related proteins 5 and 6 (
LRP5
and
LRP6
), Dickkopf1 (
DKK1
), sclerostin (
SOST
), and β-catenin (
CTNNB1
). We genotyped 652 subjects for the following polymorphisms: A1330V in
LRP5
; I1062V in
LRP6
; E232K in
DKK1
; D32Y, G34V, and N287S in
CTNNB1
; and -1397_-1396insGGA in
SOST
. Bone mineral density (BMD) was also measured. The allele frequencies were as follows: for A1330V C:T = 87%:13%, for I1062V C:T = 20%:80%, and for -1397_-1396insGGA-:GGA = 64%:36%. The studied nucleotide changes in the
DKK1
and
CTNNB1
genes were shown not to be polymorphic. In a Slovenian population, no association was shown between lumbar spine and femoral neck BMD in A1330V (
P
= 0.151 and 0.243) and in I1062V (
P
= 0.209 and 0.405). We observed a difference between
SOST
genotypes, corresponding to an allele dose effect, which was borderline significant for lumbar spine and femoral neck BMD (
P
= 0.047 and 0.085); but this did not survive the adjustment for multiple testing. These results indicate that a larger sample size would be necessary to detect these subtle effects. Our results suggest that A1330V in
LRP5
, I1062V in
LRP6
, and -1397_-1396insGGA in
SOST
are not associated with BMD in the Slovenian population.
Tumour necrosis factor superfamily member 11 (TNFSF11) gene, that codes for receptor activator of nuclear factor-kappaB ligand, is one of the candidate genes for the genetic susceptibility to ...osteoporosis. As variations in the TNFSF11 gene promoter could alter its expression, the aim of the study was to evaluate the functional influence of three polymorphisms in the promoter and to investigate their association with bone mineral density (BMD) and biochemical markers in postmenopausal women. A total of 404 postmenopausal women were genotyped for the presence of TNFSF11 gene promoter polymorphisms -290C>T, -643C>T and -693G>C. Two common haplotypes, CCG and TTC, which occur in 44.3 and 49.3% of subjects respectively, were subjected to functional analysis. Amplified fragments were cloned into pGL3-basic reporter plasmid, which was co-transfected with pRL-TK plasmid into HEK293 cells. Dual luciferase reporter assay was performed. BMD and biochemical markers were measured. Reporter gene analysis showed significantly higher luciferase activity in CCG than in TTC haplotype (P=0.018). Both showed association with lumbar spine BMD (BMD-ls; P=0.005 and 0.007 for TTC and CCG respectively), whereas in femoral neck there was no association with BMD. In postmenopausal osteoporosis, association with BMD-ls was established in -290C>T, -643C>T and -693G>C (P values: 0.001, 0.041 and 0.013 respectively). Association with femoral neck BMD was shown in -693G>C (P=0.049). No association was found with biochemical markers in any of the groups. Our results suggest that in postmenopausal osteoporosis, TNFSF11 gene promoter polymorphisms -290C>T, -643C>T and -693G>C play a functional role in the genetic regulation of BMD.
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