RANKL synthesized by articular chondrocytes contributes to juxta-articular bone loss in chronic arthritis.

INTRODUCTION: The receptor activator nuclear factor-kappaB ligand (RANKL) diffuses from articular cartilage to subchondral bone. However, the role of chondrocyte-synthesized RANKL in rheumatoid arthritis-associated juxta-articular bone loss has not yet been explored. This study aimed to determine whether RANKL produced by chondrocytes induces osteoclastogenesis and juxta-articular bone loss associated with chronic arthritis. METHODS: Chronic antigen-induced arthritis (AIA) was induced in New Zealand (NZ) rabbits. Osteoarthritis (OA) and control groups were simultaneously studied. Dual X-ray absorptiometry of subchondral knee bone was performed before sacrifice. Histological analysis and protein expression of RANKL and osteoprotegerin (OPG) were evaluated in joint tissues. Co-cultures of human OA articular chondrocytes with peripheral blood mononuclear cells (PBMCs) from healthy donors were stimulated with macrophage-colony stimulating factor (M-CSF) and prostaglandin E2 (PGE2), then further stained with tartrate-resistant acid phosphatase. RESULTS: Subchondral bone loss was confirmed in AIA rabbits when compared with controls. The expression of RANKL, OPG and RANKL/OPG ratio in cartilage were increased in AIA compared to control animals, although this pattern was not seen in synovium. Furthermore, RANKL expression and RANKL/OPG ratio were inversely related to subchondral bone mineral density. RANKL expression was observed throughout all cartilage zones of rabbits and was specially increased in the calcified cartilage of AIA animals. Co-cultures demonstrated that PGE2-stimulated human chondrocytes, which produce RANKL, also induce osteoclasts differentiation from PBMCs. CONCLUSIONS: Chondrocyte-synthesized RANKL may contribute to the development of juxta-articular osteoporosis associated with chronic arthritis, by enhancing osteoclastogenesis. These results point out a new mechanism of bone loss in patients with rheumatoid arthritis.

Variant rs9939609 in the FTO gene is associated with obesity in an adult population from Spain.

OBJECTIVE: Recently independent studies, including genome-wide scans, have shown that variation in the fat mass and obesity associated gene (FTO) were significantly associated with obesity in populations of European origin. DESIGN AND METHODS: In this study we examined the association between rs9939609 FTO variant and obesity related parameters in a population based-study of 732 unrelated individuals (46.9% males and 53.1% females; ages 35-74 years) from the province of Segovia in Central Spain (Castille). RESULTS: The AA genotype was significantly more frequent in obese individuals (defined as body mass index >or= 30 kg/m(2), n = 207; 80 males and 127 females) than in non-obese (19.9%vs. 13.7%, P = 0.026). In addition to increased obesity, AA homozygous individuals had higher waist circumference than individuals with AT heterozygous and TT homozygous genotypes. The minor A-allele of rs9939609 was associated with an increased odds ratio (OR) for obesity [OR 1.51, 95% confidence interval (CI) 1.10-2.12] as compared to the TT genotype. This difference was also statistically significant even after the adjustment for sex and age (OR 1.46, 95% CI 1.02-2.07). CONCLUSIONS: Our results support the association of FTO gene variants with obesity, including parameters of visceral (abdominal) obesity, in an adult general population from Spain. Overall we confirm the previously reported association studies between variants in FTO gene and the risk of obesity.

Association of ENPP1 (PC-1) K121Q polymorphism with obesity-related parameters in subjects with metabolic syndrome.

BACKGROUND: The metabolic syndrome (MS), a cluster of several metabolic disorders, is increasingly being recognized as a risk factor for cardiovascular disease. Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), originally described as a plasma cell allo-antigen and named plasma cell membrane glycoprotein (PC-1), is an inhibitor of insulin-induced activation of the insulin receptor. The single nucleotide polymorphism (SNP) K121Q in the ENPP1 gene has been studied in relation to obesity, insulin resistance and other features of MS in several populations with conflicting results. We therefore investigate the role of the K121Q SNP in the ENPP1 gene in MS in Caucasians from the province of Segovia in Central Spain (Castille). DESIGN AND METHODS: We recruited 794 unrelated persons (46.5% males and 53.5% females), ages 35-74 years from a cross-sectional population-based epidemiological survey in the province of Segovia in Central Spain (Castille). Obesity-related anthropometric measurements included BMI, waist circumference, blood pressure and lipid profile. MS was defined by International Diabetes Federation (IDF) guidelines. K121Q PC-1 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: The 121Q allele was associated with an increased BMI and waist circumference among subjects fulfilling the criteria for MS. These differences remained statistically significant even after the adjustment for sex, age and degree of glucose tolerance (beta = 1.347, P = 0.017 and beta = 2.824, P = 0.046; for BMI and waist circumference, respectively). Moreover, among type 2 diabetic patients those carrying the 121Q allele had higher BMI and higher leptin levels than subjects carrying the K121K genotype. CONCLUSIONS: Our results suggest that the ENPP1121Q allele might contribute to the genetic susceptibility to abdominal obesity among subjects with MS.

Is the plasminogen activator inhibitor-1 gene a candidate gene predisposing to hypertension? Results from a population-based study in Spain.

BACKGROUND: Studies in humans and mice suggest that plasminogen activator inhibitor-1 (PAI-1) might be a candidate gene for arterial hypertension. Our aims were to analyse whether the functional 4G/5G PAI-1 polymorphism represents a risk marker for the development of arterial hypertension regardless of hypertension-related metabolic variables. METHODS: Eight hundred and fifteen unrelated individuals (387 men, age 35-74 years) from a cross-sectional, population-based, epidemiological survey in the province of Segovia (Spain) were studied. Anthropometric/biochemical parameters--body mass index, waist circumference, diastolic and systolic blood pressures, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, fasting glucose, insulin, C-reactive protein, and PAI-1 levels--were analysed. The 4G/5G PAI-1 genotypes were established by restriction fragment length polymorphism. Insulin resistance was estimated by the homeostasis model assessment. Tobacco consumption data were obtained using a standard questionnaire. RESULTS: The 4G/4G PAI-1 genotype was significantly associated with a high prevalence of arterial hypertension. This association remained statistically significant even after adjustment for hypertension-related metabolic variables in our population (adjusted odds ratio, 1.858; 95% confidence interval, 1.135-3.018; P = 0.013). CONCLUSION: Our results show that the 4G/4G PAI-1 genotype appears to be associated with an elevated relative risk of developing arterial hypertension, regardless of PAI-1 levels and other hypertension-related factors, in a representative sample of the Spanish population.

Calpain-5 gene variants are associated with diastolic blood pressure and cholesterol levels.

BACKGROUND: Genes implicated in common complex disorders such as obesity, type 2 diabetes mellitus (T2DM) or cardiovascular diseases are not disease specific, since clinically related disorders also share genetic components. Cysteine protease Calpain 10 (CAPN10) has been associated with T2DM, hypertension, hypercholesterolemia, increased body mass index (BMI) and polycystic ovary syndrome (PCOS), a reproductive disorder of women in which isunlin resistance seems to play a pathogenic role. The calpain 5 gene (CAPN5) encodes a protein homologue of CAPN10. CAPN5 has been previously associated with PCOS by our group. In this new study, we have analysed the association of four CAPN5 gene variants(rs948976A>G, rs4945140G>A, rs2233546C>T and rs2233549G>A) with several cardiovascular risk factors related to metabolic syndrome in general population. METHODS: Anthropometric measurements, blood pressure, insulin, glucose and lipid profiles were determined in 606 individuals randomly chosen from a cross-sectional population-based epidemiological survey in the province of Segovia in Central Spain (Castille), recruited to investigate the prevalence of anthropometric and physiological parameters related to obesity and other components of the metabolic syndrome. Genotypes at the four polymorphic loci in CAPN5 gene were detected by polymerase chain reaction (PCR). RESULTS: Genotype association analysis was significant for BMI (p < or = 0.041), diastolic blood pressure (p = 0.015) and HDL-cholesterol levels (p = 0.025). Different CAPN5 haplotypes were also associated with diastolic blood pressure (DBP) (0.0005 < or = p < or = 0.006) and total cholesterol levels (0.001 < or = p < or = 0.029). In addition, the AACA haplotype, over-represented in obese individuals, is also more frequent in individuals with metabolic syndrome defined by ATPIII criteria (p = 0.029). CONCLUSION: As its homologue CAPN10, CAPN5 seems to influence traits related to increased risk for cardiovascular diseases. Our results also may suggest CAPN5 as a candidate gene for metabolic syndrome.

Endothelial nitric oxide synthase haplotypes are associated with features of metabolic syndrome.

BACKGROUND: The metabolic syndrome, a cluster of several metabolic disorders, is increasingly being recognized as a risk factor for cardiovascular disease. Endothelium-derived nitric oxide facilitates skeletal muscle glucose uptake, and data from animal models indicate that endothelial nitric oxide synthase (eNOS) gene-null mice present with a phenotype of insulin resistance, hypertension, and hypertriglyceridemia, much like that observed in humans with metabolic syndrome. We used haplotype tagging single nucleotide polymorphisms (htSNPs) to investigate the role of genetic variation in the eNOS gene (NOS3) in metabolic syndrome in humans. METHODS: We recruited 738 unrelated persons from a cross-sectional population-based epidemiological survey in the province of Segovia in Central Spain (Castille). Metabolic syndrome was defined according to the recently modified National Cholesterol Education Program Adult Treatment Panel III guidelines. RESULTS: Haplotype analysis showed a statistically significant association between some NOS3 gene variants and features of metabolic syndrome. Relative to the most common haplotype, 121, the haplotype 212 was associated with an increased odds ratio (OR) for metabolic syndrome [OR = 1.81, 95% confidence interval (CI) 1.15-2.84], and for decreased HDL-cholesterol concentrations (OR 1.52, 95% CI 1.01-2.29), and with increased mean values for the homeostasis model assessment of insulin resistance (P = 0.043), and triglycerides (P = 0.026). CONCLUSIONS: Our results suggest that genetic variation at the eNOS locus is associated with features of metabolic syndrome, and might represent a new genetic susceptibility component for insulin resistance, hypertriglyceridemia, and low HDL-cholesterol concentrations.

Interaction of the -308G/A promoter polymorphism of the tumor necrosis factor-alpha gene with single-nucleotide polymorphism 45 of the adiponectin gene: effect on serum adiponectin concentrations in a Spanish population.

BACKGROUND: We investigated whether interactions of the -308G/A polymorphism in the promoter region of the tumor necrosis factor-alpha (TNF-alpha) gene with single-nucleotide polymorphisms (SNPs) 45 and 276 of the adiponectin gene are associated with circulating adiponectin and soluble TNF-alpha receptor 2 (sTNFR2) concentrations in a Spanish population. METHODS: We performed anthropometric and physiologic measurements in 809 unrelated participants recruited with a simple random sampling approach from respondents to a cross-sectional population-based epidemiologic survey in the province of Segovia in central Spain (Castille). RESULTS: The 2-h postload glucose and serum insulin concentrations were higher in -308A allele carriers than in -308G/G individuals homozygous for the TNF-alpha gene. Plasma concentrations of sTNFR2 were positively correlated with body mass index, waist-to-hip ratio, and sagittal abdominal diameter among individuals with type 2 diabetes. Individuals with type 2 diabetes and the -308A allele had higher sTNFR2 and lower adiponectin concentrations than -308G homozygotes. Moreover, individuals carrying both the TNF-alpha -308A allele and the G allele of SNP 45 in the adiponectin gene had the highest prevalence of impaired glucose tolerance (adjusted odds ratio, 1.26; 95% confidence interval, 1.01-1.56; P = 0.038) and had lower adiponectin concentrations (beta = -0.090; P = 0.005) than individuals without these genotypes. CONCLUSIONS: Our findings are the first to indicate that a higher incidence of impaired glucose tolerance and low circulating adiponectin concentration may be associated with interaction between the -308G/A promoter polymorphism of the TNF-alpha gene and SNP 45 in the adiponectin gene.