Tumor necrosis factor alpha, CYP 17, urokinase, and interleukin 10 gene polymorphisms in postmenopausal women: correlation to bone mineral density and susceptibility to osteoporosis

Risk Genetic Variants (IL-10) for Osteoporosis in Han Population from Northwest China

Background

Osteoporosis (OP) is a common metabolic bone disease characterized by loss of bone mass. IL-10 is considered to be a powerful immune and inflammatory suppressor. This study aimed to assess association between genetic loci in IL-10 and susceptibility to OP.

Methods

Association analysis between IL-10 genetic loci and OP risk through SNPStats online software. FPRP analysis (false-positive report probability) verified whether the positive results were noteworthy findings. Linkage disequilibrium (LD) and haplotype analysis were completed by Haploview 4.2 and SNPStats. Multi-factor dimensionality reduction (MDR) was used to assess interaction of SNP-SNP in susceptibility to OP.

Results

Allele "G" of IL-10-rs1554286 (OR = 1.21, p = 0.013), allele "C" of IL-10-rs1518111 (OR = 1.22, p = 0.011), allele "C" of IL-10-rs3024490 (OR = 1.20, p = 0.018), and allele "G" of IL-10-rs1800871 (OR = 1.21, p = 0.015) were risk factors for OP. In females, smoking, drinking, or aging ≤60 years old participants, the above genetic loci are also significantly associated with the increased risk of OP. FPRP analysis showed that all positive results are noteworthy findings. There are significant differences in serum levels of uric acid, mean hemoglobin concentration, or mean hemoglobin among different genotypes of IL-10 gene loci. MDR showed that four loci model composed rs1554286, rs1518111, rs3021094, and rs1800871 is the best model for predicting OP risk.

Conclusion

IL-10-rs1554286, -rs1518111, -rs3021094, and -rs1800871 are risk factors for susceptibility to OP.

Cytokine-mediated immunomodulation of osteoclastogenesis

Cytokines are an important set of proteins regulating bone homeostasis. In inflammation induced bone resorption, cytokines, such as RANKL, TNF-α, M-CSF, are indispensable for the differentiation and activation of resorption-driving osteoclasts, the process we know as osteoclastogenesis. On the other hand, immune system produces a number of regulatory cytokines, including IL-4, IL-10 and IFNs, and limits excessive activation of osteoclastogenesis and bone loss during inflammation. These unique properties make cytokines powerful targets as rheostat to maintain bone homeostasis and for potential immunotherapies of inflammatory bone diseases. In this review, we summarize recent advances in cytokine-mediated regulation of osteoclastogenesis and provide insights of potential translational impact of bench-side research into clinical treatment of bone disease.

Association of TGF-β1 and IL-10 Gene Polymorphisms with Osteoporosis in a Study of Taiwanese Osteoporotic Patients

Osteoporosis is a rising health threat in the increasingly aging world population. It is a common skeletal disease strongly linked to genetic predisposition. We aim to identify the effects of the anti-inflammatory TGF-β1- and IL-10-specific single-nucleotide polymorphism (SNP) combination on the risk for osteoporosis. We investigated and analyzed the relationships between three TGF-β1 SNPs (-509C/T, +869 T/C and +29T/C), one IL-10 SNP (+1927A/C) and the level of bone mineral density (BMD), as well as the risk of osteoporosis in Taiwanese osteoporotic patients. A total of 217 subjects were recruited, including 88 osteoporotic patients and 129 healthy controls, for SNPs, BMD and clinical characteristics statistical analyses. Females with TGF-β1 SNP (-509 C/C) and IL-10 SNP (+1927 C/C) genotypes showed a great benefit for femoral neck T-scores. However, the combination of TGF-β1 SNP (-509 T/T) and IL-10 SNP (+1927 A/A) genotypes in all subjects showed a significant decrease in total hip BMD T-scores. The TGF-β1 SNP (-509 C/T) genotype in all subjects and TGF-β1 SNP (-509 T/T) and IL-10 SNP (+1927 A/C) genotypes in males showed positive effects on body height. The combination of the many SNPs in the anti-inflammatory TGF-β1 and IL-10 genes may be cooperatively involved in the development of osteoporosis. Our data suggested that the specific SNP combination of TGF-β1 (-509) and IL-10 (+1927) may act as a predictive factor for postmenopausal osteoporosis in Taiwanese women.

The associations of TNF-α gene polymorphisms with bone mineral density and risk of osteoporosis: A meta-analysis

OBJECTIVE

Fracture is a common consequence of osteoporosis and is associated with high morbidity and mortality. Recently, increasing evidence has suggested that polymorphisms in tumor necrosis factor-α (TNF-α) gene were associated with osteoporosis risk and bone mineral density (BMD), but results remain conflicting. We herein performed a meta-analysis based on evidence currently available from the literature to make a more precise estimation of these relationships.

METHODS

The PubMed, EMBASE, Cochrane Library, CNKI (China National Knowledge Infrastructure) and Wan Fang databases were searched for eligible studies. Articles meeting the inclusion criteria were comprehensively reviewed and all available data were accumulated. The pooled odds ratios (ORs) or mean differences (MDs) and corresponding 95% confidence intervals (CIs) were applied to assess the strength of the relationships.

RESULTS

A total of 15 studies involving 5273 subjects were included in our meta-analysis. The GG genotype of TNF-α G308A was associated with an increased risk of osteoporosis under a mutant model (GG vs GA+AA: OR = 0.63, 95% CI: 0.51-0.77, P < 0.0001, I²  = 31%). Additionally, we also observed a significant association between G308A polymorphism and BMD of lumbar spine (AA vs GG: P = 0.01, I²  = 53%). However, TNF-α T1031C, C857T and C863A polymorphisms had no obvious impacts on osteoporosis risk.

CONCLUSIONS

The present meta-analysis demonstrated that TNF-α G308A polymorphism may act as a potential candidate biomarker for screening, diagnosis, and treatment of osteoporosis, which will help improve individualized therapy of osteoporosis patients in clinics.

TNF-α and IL10 gene polymorphisms in women with postmenopausal osteoporosis

OBJECTIVE

Postmenopausal osteoporosis is a common disorder characterized by decreased bone mineral density (BMD). Proinflammatory cytokines are among the significant factors involved in bone turnover. They are the stimulants of bone resorption, acting directly on osteoclasts and osteoclast precursors. In this study, we examined the TNF-α (-308G>A) (rs1800629) and IL10 (-1082G>A) (rs1800896), (-592C>A) (rs1800872) polymorphisms in postmenopausal women with BMD T-scores less than and greater than or equal to -2.5 SD.

STUDY DESIGN

This study included 224 postmenopausal women with BMD T-scores lower than -2.5 SD (mean: -3.02±0.53) and 238 postmenopausal women with BMD T-scores -2.5 SD and greater (mean: -1.33±0.51).

RESULTS

There was a decrease in the frequency of IL10 1082 G allele carriers (GG and GA genotypes) in women with T-scores below -2.5 SD (GG+GA vs AA: OR=0.65, 95% CI=0.44-0.97, p=0.037). With regard to the TNF-α -308 G>A polymorphism, in the women with T-scores below -2.5 SD, the increased frequency of GG homozygotes and G allele carriers was detected (AA+GA vs GG: OR=0.54, 95% CI=0.35-0.82, p=0.004).

CONCLUSIONS

The results of our study suggest an association between TNF-α -308G>A and IL10 -1082G>A polymorphisms and postmenopausal osteoporosis.

Interleukin-10 inhibits bone resorption: a potential therapeutic strategy in periodontitis and other bone loss diseases

Periodontitis and other bone loss diseases, decreasing bone volume and strength, have a significant impact on millions of people with the risk of tooth loss and bone fracture. The integrity and strength of bone are maintained through the balance between bone resorption and bone formation by osteoclasts and osteoblasts, respectively, so the loss of bone results from the disruption of such balance due to increased resorption or/and decreased formation of bone. The goal of therapies for diseases of bone loss is to reduce bone loss, improve bone formation, and then keep healthy bone density. Current therapies have mostly relied on long-term medication, exercise, anti-inflammatory therapies, and changing of the life style. However there are some limitations for some patients in the effective treatments for bone loss diseases because of the complexity of bone loss. Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine, and recent studies have indicated that IL-10 can contribute to the maintenance of bone mass through inhibition of osteoclastic bone resorption and regulation of osteoblastic bone formation. This paper will provide a brief overview of the role of IL-10 in bone loss diseases and discuss the possibility of IL-10 adoption in therapy of bone loss diseases therapy.

Association between osteoporosis and polymorphisms of the IL-10 and TGF-beta genes in Turkish postmenopausal women

Osteoporosis is a multifactorial disease in which genetic determinants are modulated by hormonal, environmental and nutritional factors. The balance between bone resorption and bone formation seems to be regulated by a variety of growth factors and cytokines. An important clinical risk factor in the pathogenesis of osteoporosis is the presence of genetic polymorphisms in susceptibility genes. In this study, we investigated the association between osteoporosis and interleukin 10 (IL-10) -597 C > A and transforming growth factor β1 (TGF-β1) T869C (also named Leu10 > Pro) polymorphisms in Turkish postmenopausal women. Genomic DNA obtained from 255 individuals (152 osteoporotic and 103 healthy controls). The DNA sample was isolated from peripheral bloods by salting-out method and analyzed by the techniques of PCR-RFLP. Genotype and allele frequencies were calculated and data were analyzed using the χ(2) test. We found a statistically significant difference between the groups with respect to IL-10 genotype distribution (p = 0.001) and allele frequencies (p < 0.0002). However, we did not found any difference between the groups with regarding TGF-β1 genotype distribution and allele frequencies (p > 0.05). In the combined genotype analysis, IL-10/TGF-β1 CCCC combine genotype was also estimated risk factor for osteoporosis in Turkish postmenopausal women (p = 0.026). To our knowledge, this is the first report to examine IL-10 gene -597 C > A polymorphism and osteoporosis in Turkish population.

Interleukin (IL)-1beta, IL-1 receptor antagonist, IL-6, IL-8, IL-10, and tumor necrosis factor alpha gene polymorphisms in patients with febrile seizures

Inflammation and genetics may play a role in the pathogenesis of febrile seizures (FSs). We aimed to test whether interleukin-1beta (IL-1beta), IL-1 receptor antagonist (IL-1 Ra), IL-6 promoter, IL-8, IL-10, or tumor necrosis factor (TNF) gene polymorphisms could be used as markers of susceptibility to FSs. An association study was performed among a cohort of 104 patients with FSs and 143 normal control subjects. There was no significant difference between patients and controls in the distribution of allele frequencies of the IL-1beta promoter, IL-1beta exon 5, IL-6 promoter, IL-8, IL-10, or TNF-alpha gene polymorphisms. In contrast, the IL-1 Ra-I homozygote was more frequent in patients with FSs than in healthy controls (93.2% vs. 83.92%, chi(2)=4.51, P=0.034). In addition, individuals homozygous for the IL-1 Ra-I genotype were more than twice as likely to develop FSs than individuals heterozygous for the IL-1 Ra-I/II genotype (OR, 2.63, 95% CI: 1.08-6.39; chi(2)=4.55, P=0.033). We conclude that the IL-1 Ra gene might be one of the useful markers for predicting susceptibility to FSs.

Genetics of osteoporosis: accelerating pace in gene identification and validation

Osteoporosis is characterized by low bone mineral density and structural deterioration of bone tissue, leading to an increased risk of fractures. It is the most common metabolic bone disorder worldwide, affecting one in three women and one in eight men over the age of 50. In the past 15 years, a large number of genes have been reported as being associated with osteoporosis. However, only in the past 4 years we have witnessed an accelerated pace in identifying and validating osteoporosis susceptibility loci. This increase in pace is mostly due to large-scale association studies, meta-analyses, and genome-wide association studies of both single nucleotide polymorphisms and copy number variations. A comprehensive review of these developments revealed that, to date, at least 15 genes (VDR, ESR1, ESR2, LRP5, LRP4, SOST, GRP177, OPG, RANK, RANKL, COLIA1, SPP1, ITGA1, SP7, and SOX6) can be reasonably assigned as confirmed osteoporosis susceptibility genes, whereas, another >30 genes are promising candidate genes. Notably, confirmed and promising genes are clustered in three biological pathways, the estrogen endocrine pathway, the Wnt/beta-catenin signaling pathway, and the RANKL/RANK/OPG pathway. New biological pathways will certainly emerge when more osteoporosis genes are identified and validated. These genetic findings may provide new routes toward improved therapeutic and preventive interventions of this complex disease.

Association between polymorphisms in tumor necrosis factor (TNF) and TNF receptor genes and circulating TNF, soluble TNF receptor levels, and bone mineral density in postmenopausal Korean women

OBJECTIVE

The aim of the present study was to investigate the relationship of polymorphisms in the tumor necrosis factor (TNF)-alpha, TNF-beta, and TNF receptor (TNFR) genes to circulating TNF, soluble TNFR (sTNFR) levels, and bone mineral density (BMD) in women.

METHODS

The TNF-alpha G(-308)A, C(-857)T, C(-863)A, T(-1031)C, TNF-beta A252G, TNFRI A36G, TNFRII T676G, A1663G, A1668G, and C1690T polymorphisms were analyzed in 377 postmenopausal Korean women. The levels of serum TNF-alpha, TNF-beta, sTNFRI, sTNFRII, and bone turnover markers were measured. BMD was examined by dual energy x-ray absorptiometry.

RESULTS

After adjustment for age, body mass index, and years since menopause, no significant differences in BMD of the lumbar spine and femoral neck and serum levels of bone turnover markers were detected, according to single polymorphisms in TNF and TNFR genes and combined polymorphisms. However, the frequencies of the TT genotype of TNF-alpha T(-1031)C polymorphism, the non-AA genotype of TNF-beta A252G polymorphism, and the GG genotype of TNFRII A1663G polymorphism were significantly higher in osteoporotic women than in women with normal BMD, respectively (P < 0.05). The TNFRII T676G polymorphism affected the serum sTNFRI and sTNFRII levels. The serum sTNFRII levels in the CC genotype of TNFRII C1690T polymorphism were the highest, with a G or C allele dose effect, and the TNFRII G676C/C1690T haplotype genotype also affected serum sTNFRII levels.

CONCLUSIONS

TNF-alpha T(-1031)C, TNF-beta A252G, and TNFRII A1663G polymorphisms may be genetic factors for osteoporosis in Korean postmenopausal women, and the TNFRII T676G and C1690T polymorphisms and their combined polymorphism affected serum sTNFRII levels. The TNFRII T676G polymorphism also affected the serum sTNFRI levels.

High-density association study of 383 candidate genes for volumetric BMD at the femoral neck and lumbar spine among older men

Genetics is a well-established but poorly understood determinant of BMD. Whereas some genetic variants may influence BMD throughout the body, others may be skeletal site specific. We initially screened for associations between 4608 tagging and potentially functional single nucleotide polymorphisms (SNPs) in 383 candidate genes and femoral neck and lumbar spine volumetric BMD (vBMD) measured from QCT scans among 862 community-dwelling white men >or=65 yr of age in the Osteoporotic Fractures in Men Study (MrOS). The most promising SNP associations (p < 0.01) were validated by genotyping an additional 1156 white men from MrOS. This analysis identified 8 SNPs in 6 genes (APC, DMP1, FGFR2, FLT1, HOXA, and PTN) that were associated with femoral neck vBMD and 13 SNPs in 7 genes (APC, BMPR1B, FOXC2, HOXA, IGFBP2, NFATC1, and SOST) that were associated with lumbar spine vBMD in both genotyping samples (p < 0.05). Although most associations were specific to one skeletal site, SNPs in the APC and HOXA gene regions were associated with both femoral neck and lumbar spine BMD. This analysis identifies several novel and robust genetic associations for volumetric BMD, and these findings in combination with other data suggest the presence of genetic loci for volumetric BMD that are at least to some extent skeletal-site specific.

Molecular genetic studies of gene identification for osteoporosis

This review comprehensively summarizes the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of September 2007. It is intended to constitute a sequential update of our previously published reviews covering the available data up to the end of 2004. Evidence from candidate gene-association studies, genome-wide linkage and association studies, as well as functional genomic studies (including gene-expression microarray and proteomics) on osteogenesis and osteoporosis, are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. The major results of all studies are tabulated for comparison and ease of reference. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.

Assessment of laboratory measurements and -308 TNFalpha gene promoter polymorphisms in normal bone mineral density

The aim of this study was to identify and evaluate laboratory parameters associated with normal bone mineral density (BMD) and to test if -308 tumour necrosis factor (TNF) alpha gene promoter polymorphisms could influence BMD. We performed a comparative cross-sectional study of four main groups: young healthy individuals (20-30 years); subjects aged 50 years or over with normal BMD; osteoporotic subjects aged 50 years or over; osteoporotic women with active rheumatoid arthritis. Variables assessed included anthropometric features, diet intake, lifestyle, calcium-phosphorus balance, markers of bone turnover, sexual hormones, hormones related with body mass and growth, cytokines involved in inflammation and bone turnover, and -308 TNF alpha gene promoter polymorphisms. One hundred fifty-nine subjects were evaluated. Across the four groups, zinc serum levels were higher in men as compared to women. In addition, zinc serum levels were also higher in individuals with normal BMD as compared to osteoporotic subjects. Serum calcium levels were higher in normal BMD group. On the other hand, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were significantly higher in normal bone mass postmenopausal women and men as compared to age-matched osteoporotic groups. Finally, leptin was significantly lower in men, after correcting these results for body mass index values. The remaining variables assessed had a similar distribution among the different studied groups. In our population, low serum levels of leptin and high serum levels of zinc, calcium, FSH, and LH were associated with a higher BMD.

Polymorphisms of tumor necrosis factor-alpha, interleukin-10, cytochrome P450 3A5 and ABCB1 in Chinese liver transplant patients treated with immunosuppressant tacrolimus

BACKGROUND

Cytokine production in the host immune response after transplantation may contribute to the variable CYP3A-dependent drug disposition. We investigated the effect of TNF-alpha, IL-10, CYP3A5 and ABCB1 polymorphisms on immunosuppressant tacrolimus pharmacokinetics in liver transplant patients.

METHODS

Genetic polymorphisms in TNF-alpha, IL-10, CYP3A5 and ABCB1 were studied in 70 liver transplant recipients and 70 donors. Tacrolimus dosage and blood concentration were investigated at 1, 2 and 3 weeks after transplantation.

RESULTS

The IL-10 G-1082A polymorphism in recipients was significantly associated with tacrolimus concentration/dose (C/D) ratios (IL-10-1082GG < GA < AA) within the first 3weeks posttransplantation (P < 0.05). Recipients with the capacity for low IL-10 production (-1082AA) carrying CYP3A5 non-expressor (CYP3A5()3/()3) liver had the highest C/D ratios (mean: 172.4, 161.7, 160.3 for 1, 2 and 3 weeks posttransplantation, respectively), whereas recipients with intermediate or high production of IL-10 (-1082GA or GG) engrafted with CYP3A5 expressor (CYP3A5()1 carrier) liver were found to have the lowest ratios (96.4, 78.0 and 75.4, respectively, P < 0.01).

CONCLUSIONS

The IL-10 G-1082A and CYP3A5()3 polymorphisms may influence the interindividual variability of tacrolimus pharmacokinetics in Chinese liver transplant patients. This finding provided a new interpretation for the variable immunosuprressant disposition after transplantation.

An application of bioinformatics and text mining to the discovery of novel genes related to bone biology

The treatment and management of complex genetic diseases such as osteoporosis can greatly benefit from the integration of relevant research across many different disciplines. We created a text mining tool that analyzes the PubMed literature database and integrates the available genomic information to provide a detailed mapping of the genes and their interrelationships within a particular network such as osteoporosis. The results obtained from our text mining program show that existing genomic data within the PubMed database can effectively be used to predict potentially novel target genes for osteoporosis research that have not previously been reported in the literature. To filter the most significant findings, we developed a ranking system to rate our predicted novel genes. Some of our predicted genes ranked higher than those currently studied, suggesting that they may be of particular interest from a therapeutic standpoint. A preliminary analysis of the current biomedical literature in our research area using our tool suggests that S100A12, as well as a group of SMAD genes previously unstudied in relation to osteoporosis, may be highly relevant to the mechanism of action of bisphosphonates, that the function of osteocytes may be influenced by a family of important interleukins and interleukin-related molecules, and that the FYN oncogene may play an important role in regulating the apoptosis of bone cells in the context of degenerative bone diseases. An evaluation of our tool's predictive ability with an analysis of PubMed literature published before the year 2000 in the area of osteoporosis research shows that many of its top-rated novel target genes from that analysis were later studied and shown to be relevant to osteoporosis in the period between 2000 and 2006. We believe that our tool will be beneficial to researchers in the field of orthopaedics seeking to identify novel target genes in their research area, and it will allow them to delve deeper into the complex interplay between genes, biological systems and diseases.

Adiposity and bone mineral density of Chilean elderly women in relation to toll-like receptor 4 gene polymorphisms

BACKGROUND

It has been proposed that the toll-like receptor-4 gene (TLR4) may participate in the development of obesity and osteoporosis, in addition to its well-known role in the immune response. On the other hand, the adipose tissue of obese subjects shows an increased expression of the proinflammatory cytokine, tumour necrosis factor-alpha (TNF-alpha), which is released after lipopolysaccharide recognition by TLR4.

AIM

To estimate the allele/genotype frequencies and linkage disequilibrium measures of Asp299Gly and Thr399Ile polymorphisms of the TLR4 gene in the Chilean elderly population, and to screen for their association with variables related to adiposity or bone mineral density.

SUBJECTS AND METHODS

The study group included 227 unrelated Chilean elderly women (61-95 years) recruited from a population-based sample. Adiposity and bone mineral density measures were obtained using dual-energy X-ray absorptiometry.

RESULTS

The allele frequencies for TNF -308A, TLR4 299Gly and TLR4 -399Ile were 9.3%, 4.6% and 4.4%, respectively, with Asp299Gly and Thr399Ile being in strong linkage disequilibrium (D' = 0.88). Although seriously restricted by the low frequency of the allele variants, no relevant association between genotypes and adiposity-related variables were found. Likewise, no significant association between osteoporosis status (categorized as osteoporosis, osteopenia or normal status) with TLR4 Asp299Gly or TNF -308G>A genotypes was found.

CONCLUSION

It is unlikely that TLR4 Asp299Gly, TLR4 Thr399Ile or TNF -308G>A polymorphisms have a major influence on adiposity, bone mineral density or osteoporosis status in Chilean elderly women.

Interleukin-10 inhibits osteoclastogenesis by reducing NFATc1 expression and preventing its translocation to the nucleus

Background

IL-10 has a potent inhibitory effect on osteoclastogenesis. In vitro and in vivo studies confirm the importance of this cytokine in bone metabolism, for instance IL-10-deficient mice develop the hallmarks of osteoporosis. Although it is known that IL-10 directly inhibits osteoclastogenesis at an early stage, preventing differentiation of osteoclast progenitors to preosteoclasts, the precise mechanism of its action is not yet clear. Several major pathways regulate osteoclastogenesis, with key signalling genes such as p38, TRAF6, NF-κB and NFATc1 well established as playing vital roles. We have looked at gene expression in eleven of these genes using real-time quantitative PCR on RNA extracted from RANKL-treated RAW264.7 monocytes.

Results

There was no downregulation by IL-10 of DAP12, FcγRIIB, c-jun, RANK, TRAF6, p38, NF-κB, Gab2, Pim-1, or c-Fos at the mRNA level. However, we found that IL-10 significantly reduces RANKL-induced NFATc1 expression. NFATc1 is transcribed from two alternative promoters in Mus musculus and, interestingly, only the variant transcribed from promoter P1 and beginning with exon 1 was downregulated by IL-10 (isoform 1). In addition, immunofluorescence studies showed that IL-10 reduces NFATc1 levels in RANKL-treated precursors and suppresses nuclear translocation. The inhibitory effect of IL-10 on tartrate-resistant acid phosphatase-positive cell number and NFATc1 mRNA expression was reversed by the protein kinase C agonist phorbol myristate acetate, providing evidence that interleukin-10 disrupts NFATc1 activity through its effect on Ca²⁺ mobilisation.

Conclusion

IL-10 acts directly on mononuclear precursors to inhibit NFATc1 expression and nuclear translocation, and we provide evidence that the mechanism may involve disruption of Ca²⁺ mobilisation. We detected downregulation only of the NFATc1 isoform 1 transcribed from promoter P1. This is the first report indicating that one of the ways in which IL-10 directly inhibits osteoclastogenesis is by suppressing NFATc1 activity.

Adiposity, estradiol, and genetic variants of steroid-metabolizing enzymes as determinants of bone mineral density

OBJECTIVES

Bone mineral density (BMD) is a complex trait resulting from the interplay of genetic and acquired factors. The objective of this study was to explore the influence of several anthropometric, lifestyle, genetic, and hormonal factors on BMD and analyze the possible differences in men and women.

METHODS

We studied 572 individuals over 50 years of age (381 postmenopausal women and 191 men). Lumbar spine and femoral neck BMD were measured by dual energy x-ray absorptiometry. The free estrogen index (FEI) was calculated as the ratio of serum estradiol to sex hormone binding globulin in 241 individuals. Three polymorphisms in the genes coding for 17-hydroxylase/liase, sulfotransferase, and 5alpha-reductase were studied in DNA isolated from blood cells.

RESULTS

Body mass index was strongly correlated to spine and femoral BMD both in women and in men (r = 0.32-0.49; P < 0.001). FEI was also independently correlated with spine BMD in both sexes (r = 0.23 and 0.34, P < 0.01), and with femoral neck in women (r = 0.30). Women with G alleles of the sulfotransferase gene tended to have higher spine BMD than those with C alleles (P = 0.025). No other genotype-related differences in BMD were found.

CONCLUSIONS

In conclusion, the results of this study point toward body weight and estradiol levels as major factors determining BMD both in women and in men. A common polymorphism of the sulfotransferase gene also appears to be associated to spine BMD in women.