The association of Pro12Ala polymorphism of peroxisome proliferator-activated receptor-gamma gene with serum osteoprotegerin levels in healthy Korean women.

Recent evidences suggest that the activation of peroxisome proliferator-activated receptor (PPAR)-gamma, which is an important transcriptional factor in adipocyte differentiation, also plays an important role in the bone microenvironment. The objective of the study was to clarify whether Pro12Ala polymorphism was related to the serum OPG levels and bone mineral metabolism in healthy Korean women. In 239 Korean women (mean age 51 years), who participated in medical check-up program in a health promotion center, anthropometric measurements, lumbar spine and femoral neck bone mineral density (BMD), bone turnover markers, such as serum total alkaline phosphatase (ALP) levels, urine deoxypyridinoline levels, and 24-h urine calcium excretion were measured. Serum levels of OPG were measured with ELISA method. DNAs were extracted from the samples and the genotyping of the Pro12Ala polymorphism (rs1801282) in the PPAR-gamma gene was performed via an allelic discrimination assay using a TaqMan probe. In addition, we examined the haplotype analysis between two polymorphisms of PPAR-gamma gene, Pro12Ala in exon B and C161T in exon 6 (rs3856806). Allelic frequencies were 0.950 for Pro allele and 0.050 for Ala allele, which was in compliance with Hardy- Weinberg equilibrium, and there was no Ala12Ala genotype among the genotyped subjects. Mean serum OPG level was significantly lower (P=0.035), and serum total ALP was significantly higher (P=0.014) in the Pro12Ala genotype group compared with the Pro12Pro genotype group, which were consistently significant even after adjustment for weight, height, and serum follicle stimulating hormone (FSH). In multiple regression analysis with serum OPG as the dependent variable and age, weight, ALP, femoral neck BMD and Pro12Ala genotype included in the model, only Pro12Ala genotype was significant determinant of serum OPG level (b=??0.136, P=0.035). The haplotype analysis with C161T polymorphism revealed that subjects with Ala and T alleles showed significantly lower serum OPG levels compared with those with Pro12Pro/CC genotype, which were consistently significant even after adjustment for age, weight, height and FSH (P=0.010). This result suggests statistically significant association of Pro12Ala polymorphisms with serum OPG levels in Korean females.

Factors affecting the serum levels of adipokines in Korean male patients with nonalcoholic fatty liver disease.

BACKGROUND/AIMS: Adipokines are associated with various metabolic disorders including insulin resistance, obesity, and dyslipidemia. Metabolic disorders have also been reported to be associated with nonalcoholic fatty liver disease (NAFLD). The aim of this study was to determine the relationship between the serum adipokine levels and the degrees of hepatic fat infiltration in NAFLD. This study also attempted to determine the independent factors influencing the serum adipokine levels in NAFLD. METHODOLOGY: Sixty-five Korean male patients were enrolled in this study. The degree of hepatic fat infiltration was classified into the following three groups according to the ultrasonographic findings: Group I, normal liver; Group II, mild fatty liver; and Group III, moderate to severe fatty liver. The anthropometric parameters, fasting serum adipokine levels including leptin, adiponectin and resistin were measured in all subjects. The level of insulin resistance was estimated using the HOMA-IR. RESULTS: The serum leptin levels increased with increasing degree of hepatic fat infiltration (mean +/- SD: Group I, 2.052 +/- 1.071; Group II, 2.879 +/- 1.016; and Group III, 4.457 +/- 1.965 ng/mL, P < 0.001). However, the serum adiponectin and resistin levels were similar. The fasting serum insulin level was only a related factor for the changes in the serum leptin levels (P = 0.004). There were no related factors for the change in the serum adiponectin and resistin levels. CONCLUSIONS: This study suggests an indirect role for leptin in the pathogenesis of NAFLD by inducing insulin resistance, resulting in increased fasting serum insulin level.

[The relationship between serum adiponectin level and serum alanine aminotransferase elevation in Korean male with nonalcoholic fatty liver disease].

BACKGROUND/AIMS: Nonalcoholic fatty liver disease (NAFLD) comprises a large part of chronic liver diseases. Recently it was reported that adipokines are closely associated with the common risk factors for NAFLD, such as obesity, diabetes, dyslipidemia, and insulin resistance. We aimed to evaluate the changes in serum adiponectin, resistin and leptin concentrations related to alanine aminotransferase (ALT) elevations in Korean men with NAFLD. METHODS: We studies 38 men who were diagnosed with fatty liver by abdominal ultrasonography. None had a history of excessive alcohol consumption, autoimmune hepatitis, inherited or metabolic liver disease or viral hepatitis. The subjects were divided into two groups. One group had normal levels of ALT (n=28) and the other had increased ALT (n=10). We compared anthropometrical parameters, biochemical items and serum adipokine levels between these two groups. RESULTS: Serum adiponectin levels were lower in the increased ALT group than in the normal ALT group (3.89 +/- 1.77 vs 7.01 +/- 2.54 microgram/dL, P=0.001). But there were no significant differences in serum leptin and resistin levels between two groups (4.02 +/- 2.04 vs 3.26 +/- 1.41 ng/mL, p=0.245, 80.14 +/- 14.8 vs 80.5 +/- 11.34 ng/mL, P=0.937, respectively). Multiple linear regression analyses demonstrated that the serum adiponectin level is inversely correlated with serum ALT level and that the serum aspartate aminotransferase (AST) level is positively correlated with the serum ALT level. CONCLUSIONS: Our study shows that hypoadiponectinemia is associated with an ALT elevation in patients with NAFLD. Adiponectin may play an indirect role in the development of NAFLD.

The relationship between four single nucleotide polymorphisms in the promoter region of the osteoprotegerin gene and aortic calcification or coronary artery disease in Koreans.

OBJECTIVE: Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of the NF-kappaB ligand (RANKL). OPG has been shown to be an important inhibitor of osteoclastogenesis and arterial calcification in animal models. OPG has been proposed as a link molecule between osteoporosis and arterial calcification, but the relationship between the OPG gene and the cardiovascular system in human populations is unclear. Thus, the aim of this study was to investigate the relationship between OPG gene polymorphisms and aortic calcification or coronary artery disease in Koreans. DESIGN AND PATIENTS: Genotyping of four polymorphisms, A163G, G209A, T245G and T950C, in the promoter region of the OPG gene was performed in 251 healthy Korean women (mean age 51.3 +/- 6.9 years) and in a second study population consisting of 100 patients who underwent coronary angiography (mean age 57.0 +/- 11.9 years), by allelic discrimination using the 5' nuclease polymerase chain reaction assay. Cardiovascular risk factors and serum OPG levels were measured and aortic calcification in thoracic and abdominal aorta was examined by simple radiological methods. RESULTS: In the first study population, the prevalence of aortic calcification increased significantly as the subjects grew older. The frequencies of mutant alleles were significantly higher in the subjects with aortic calcification compared with those without aortic calcification in G209A and T950C polymorphisms, although these significances were lost after adjustment for age. No significant relationship was found between OPG gene polymorphisms and serum OPG levels or cardiovascular risk factors. In the second study group, there were no associations between OPG promoter genotypes and aortic calcification, serum OPG levels, or coronary artery disease. CONCLUSIONS: We observed that the four polymorphisms in the promoter region of the OPG gene were not associated with aortic calcification or coronary artery disease in Koreans. Further studies are needed to clarify this relationship.

Effects of two common polymorphisms of peroxisome proliferator-activated receptor-gamma gene on metabolic syndrome.

BACKGROUND: Peroxisome proliferator-activated receptor (PPAR)gamma is involved mainly in adipocyte differentiation and has been suggested to play an important role in the pathogenesis of insulin resistance and atherosclerosis. We investigated the frequencies of two common polymorphisms of PPARgamma gene, exon 6 C-->T substitution and exon B Pro12Ala in healthy subjects and analyzed the correlations between the different genotypes and insulin resistance, metabolic syndrome and cardiovascular risk factors. METHODS: Anthropometric measurements, fasting glucose, insulin and lipid profiles were measured in 253 Korean females. Homeostatic model assessments and quantitative insulin sensitivity check indices were calculated. Metabolic syndrome was diagnosed according to the NCEP-ATP III guidelines and the Western Pacific Region of WHO for obesity criteria for waist circumference. Polymerase chain reaction (PCR)-restriction fragment-length polymorphism and real-time PCR were performed for genotyping of the DNAs. RESULTS: For C161T polymorphism, allele frequencies were 0.804 and 0.196 for T allele, and 0.947 for proline and 0.053 for alanine. There was no Ala12Ala homozygote in the population. No differences were seen in the mean values of age, body mass index (BMI), blood pressure, fasting blood glucose level, fasting insulin levels, HOMA and QUICKI among different genotypes when analyzed as a whole, except that subjects with Pro12Ala had significantly higher body weight than those with Pro12Pro genotype. However, mean BMI, percent body fat and weight showed significant differences between genotypes in younger age group (< or =50 years). Although overall prevalence of metabolic syndrome had no association with the genotypes, the prevalence of decreased high-density lipoprotein cholesterol component was lower in those with the T allele than in those with the CC genotype. There was no association of the genotypes with glucose tolerance status. When the subjects were divided into four groups according to the combination of the genetic alleles of the two polymorphisms, subjects having Pro12Ala and T allele, simultaneously, showed significantly higher mean weight than those without Ala allele. Pro12Ala polymorphism seems to affect body weight, similar to the previous studies, and the effect was potentiated with the presence of T allele of C161T polymorphism. CONCLUSIONS: Although either polymorphism failed to show significant association with insulin resistance, the fact that the prevalence of decreased HDL-C was lower in those with the T allele of C161T polymorphism suggests that this polymorphism might have a protective effect on atherosclerotic lipid profiles, which needs further investigation.

The effects of C161-->T polymorphisms in exon 6 of peroxisome proliferator-activated receptor-gamma gene on bone mineral metabolism and serum osteoprotegerin levels in healthy middle-aged women.

OBJECTIVE: We evaluated the association of different genotypes in C161-->T substitution in exon 6 of peroxisome proliferator-activated receptor-gamma (PPARgamma) gene with bone turnover markers, bone mineral density (BMD), and serum osteoprotegerin (OPG) in female subjects to reveal the role of PPARgamma in bone. STUDY DESIGN: In 263 healthy Korean women (mean age 52 years), anthropometric measurements were taken along with measurements of lumbar spine and femoral neck BMD, bone turnover markers, such as alkaline phosphatase, serum calcium, phosphorus, 24-hour urine calcium, phosphorus excretion, and urine deoxypyridinoline. Serum follicular stimulating hormone levels were measured and serum OPG levels were measured with the enzyme-linked immunosorbent assay method. Polymerase chain reaction-restriction fragment length polymorphism was performed. RESULTS: Allele frequencies were 0.804 for the C allele and 0.196 for the T allele. There were no differences in mean age, body mass index, BMD, and bone turnover markers among different genotypes, and the subjects with T alleles had significantly lower serum OPG levels. There were no differences in the prevalence of metabolic bone diseases according to the genotypes. When analyzed according to the menopausal status, only postmenopausal subjects with T alleles showed significantly lower serum OPG levels. CONCLUSION: The frequencies of C161-->T substitution in exon 6 of the PPARgamma gene in Korean females were similar to other races and women with T alleles showed significantly lower serum OPG levels and it was especially noted for postmenopausal subjects, which supports the possible concurrent association of PPARgamma and OPG with estrogen status in female subjects.

Circulating osteoprotegerin levels are associated with age, waist-to-hip ratio, serum total cholesterol, and low-density lipoprotein cholesterol levels in healthy Korean women.

Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of nuclear factor I masculine B ligand. Osteoprotegerin has been shown to be an important inhibitor of osteoclastogenesis and arterial calcification in animal models. Recently, OPG has been proposed as a link molecule between osteoporosis and arterial calcification, but the relationship between circulating OPG levels and cardiovascular disease in human populations is unclear. Thus, the aim of this study was to investigate the relationship between circulating OPG levels and cardiovascular risk factors in healthy Korean women. The subjects were 286 women aged 37 to 73 (mean +/- SD, 51.5 +/- 6.9 years). We examined blood pressure, body mass index, and waist-to-hip ratio. Serum concentrations of OPG were determined by enzyme-linked immunosorbent assay. Fasting plasma glucose levels, serum lipid profiles, insulin levels, and serum follicle-stimulating hormone (FSH) levels were determined by standard methods and homeostasis model assessment of insulin resistance was calculated. We observed a significant association between serum OPG levels and age, waist-to-hip ratio, total cholesterol, low-density lipoprotein cholesterol, and FSH levels (P < .05). Among the metabolic components, the older, obese, and hypercholsterolemic subjects had higher serum OPG levels (P < .05). However, no significant relationship was found between serum OPG levels and blood pressure and fasting plasma glucose levels. We found that mean serum OPG levels were about 11% greater in postmenopausal women (mean +/- SD, 1358.5 +/- 380.0 pg/mL) than in premenopausal women (mean +/- SD, 1228.8 +/- 407.7 pg/mL, P < .001). In multiple regression analysis with OPG as the dependent variable, serum FSH and low-density lipoprotein cholesterol levels were the significant predictor for serum OPG level (R(2) = 0.051, P < .05). In conclusion, our results show that circulating OPG levels are partly associated with cardiovascular risk factors and menopausal status in healthy Korean women. Out findings suggest that OPG may be an important paracrine factor of cardiovascular disease in the female population.

Relationship of serum osteoprotegerin levels with coronary artery disease severity, left ventricular hypertrophy and C-reactive protein.

OPG (osteoprotegerin) is an inhibitor of osteoclastogenesis and recent work suggests it has a role in atherosclerosis. Therefore we measured serum OPG levels in patients with coronary artery disease, compared the serum OPG levels among the different groups according to the number of stenotic vessels and determined whether there was any correlation with aortic calcification, LV (left ventricular) mass index and serum CRP (C-reactive protein) levels. Subjects (n=100; mean age, 57 years) who underwent coronary angiograms were enrolled. Blood pressure, body mass index, fasting blood glucose, lipid profiles and CRP levels were measured and the LV mass indices were calculated using ECGs. Serum OPG levels were measured by ELISA. The presence of calcification in the aortic notch was checked by a chest X-ray. The subjects were divided into four groups according to the number of stenotic vessels. The mean serum OPG levels increased significantly as the number of stenotic vessels increased, and the mean serum OPG levels were higher in the group with three-vessel disease compared with the groups with no- or one-vessel disease. The mean serum CRP level was significantly higher in the group with three-vessel disease compared with the groups with no-, one- and two-vessel disease. Age and LV mass index showed significant positive correlations with serum OPG levels, although significance was lost after an adjustment for age. Serum CRP levels were positively correlated with serum OPG levels even after an adjustment for age. There were no differences in serum OPG levels according to the presence of fasting hyperglycaemia or aortic calcification. In conclusion, serum OPG level was related to the severity of stenotic coronary arteries and serum CRP levels. LV mass indices showed no significant correlation with OPG levels. The precise mechanism for the role of OPG in atherosclerosis needs to be investigated further.

The relationship between circulating osteoprotegerin levels and bone mineral metabolism in healthy women.

OBJECTIVE: Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the RANK ligand. Moreover, OPG has been shown to be an important inhibitor of osteoclastogenesis in animal models. However, the relationship between circulating OPG levels and female bone status in human populations is unclear. In this study we undertook to investigate the relationship between circulating OPG levels and bone mineral metabolism in healthy women. PATIENTS AND MEASUREMENTS: Our subjects were 287 women aged 37-73 years (mean age 51.5 years). The serum concentrations of OPG were determined by enzyme-linked immunosorbent assay (ELISA). The biochemical markers of bone turnover and FSH were measured using standard methods. Bone mineral densities at the lumbar spine and femoral neck were measured by dual-energy X-ray absorptiometry. RESULTS: Postmenopausal women had a significantly higher mean value of serum OPG than premenopausal women (1358.5 +/- 32.5 pg/ml vs. 1228.8 +/- 33.3 pg/ml, P < 0.01). Serum OPG levels were positively correlated with age (r = 0.169, P < 0.01), as were urine deoxypyridinoline levels (r = 0.133, P < 0.05) and serum FSH levels (r = 0.187, P < 0.01) in a bivariate correlation analyses. In a multiple regression analysis, only urine calcium excretion was identified as a significant predictor for serum OPG levels. CONCLUSIONS: Circulating OPG levels were found to be associated with urine calcium excretion and menopause in healthy women. Our observations suggest that circulating OPG levels reflect an antiresorptive activity in bone, and they are related to endogenous oestrogen levels.

Age, body mass index, current smoking history, and serum insulin-like growth factor-I levels associated with bone mineral density in middle-aged Korean men.

Osteoporosis is a growing health problem in women and in men. This cross-sectional study examined the association of anthropometric, lifestyle, and hormonal factors with bone mineral density (BMD) in 152 healthy Korean middle-aged men. Smoking habits and alcohol consumption were assessed by interview. Serum testosterone and insulin-like growth factor-I (IGF-I) levels were measured by radioimmunoassay, and serum growth hormone (GH) levels were measured by immunoradiometric assay. GH stimulation tests were performed after the ingestion of 500 mg of L-dopa. BMD was measured at the lumbar spine and at the femoral neck by dual-energy X-ray absorptiometry. Of the middle-aged men, 3.9% were osteoporotic and 28.3% were osteopenic at the lumbar spine site, and 5.9% were osteoporotic and 45.4% were osteopenic at the femoral neck site. Lumbar spine BMD correlated significantly with body mass index (BMI), and femoral neck BMD correlated significantly with age, BMI, and serum IGF-I levels. The lowest quartile group for serum IGF-I levels showed the lowest femoral neck BMD. Osteoporotic men by lumbar spine BMD showed significant differences from the normal BMD group in terms of BMI and smoking habits. Also, osteoporotic men by femoral neck BMD were significantly different for mean age, BMI, and serum IGF-I levels compared with the normal BMD group. On multiple regression analysis, BMI was found to be the only independent predictor of lumbar spine BMD, whereas both BMI and serum IGF-I levels were found to be the independent predictors of femoral neck BMD. Overall, 28.3%-45.4% of middle-aged Korean men were osteopenic. We suggest that higher age, a lower BMI, current smoking history, and lower serum IGF-I levels are risk factors for lower BMD in middle-aged Korean men; however, serum testosterone levels and GH secretory capacity were not found to be correlated with BMD.

The skeletal site-differential changes in bone mineral density following bone marrow transplantation: 3-year prospective study.

Loss of bone mass is usually detected after bone marrow transplantation (BMT) during the early post-transplant period. However, little is known about the long-term effects of BMT on bone metabolism. We have prospectively investigated 11 patients undergoing BMT. Bone mineral density (BMD) was measured before BMT, and 1, 2, and 3 yr after BMT. Serum markers of bone turnover were serially measured before BMT and 1, 2, 3, 4, and 12 weeks, 6 months, and 1 yr after BMT. The mean change in the lumbar spine (L2-4) BMD, calculated as the percent change from the baseline to the level at 1, 2, and 3 yr was -4.7% (NS), -1.1% (NS), and +6.4% (p<0.05), respectively. The mean change in the total proximal femur BMD from the baseline to the level at 1, 2, and 3 yr was -8.5% (p<0.01), -8.7% (p<0.05) and -5.6% (p<0.05), respectively. In summary, there was little decline in lumbar BMD at 1 yr following BMT and gradual recovery until 3 yr. In contrast, femoral BMD decreased much more than the lumbar area at 1 yr and did not recover until 3 yr. The mechanism of skeletal site-selective differences in the changes of BMD needs to be elucidated.

Circulating IL-8 and IL-10 in euthyroid sick syndromes following bone marrow transplantation.

It is generally agreed that euthyroid sick syndromes (ESS) are associated with an increased production of cytokines. However, there has been scarce data on the relationship thyroid hormone changes and cytokines among the patients undergoing bone marrow transplantation (BMT). Because interleukin-8 (IL-8) has been identified as a potent proinflammatory and interleukin-10 (IL-10) as an antiinflammatory cytokine, we studied the relation between thyroid hormone parameters and these cytokines following BMT. We studied 80 patients undergoing allogeneic BMT. Serum T3 decreased to nadir at post-BMT 3 weeks. Serum T4 was the lowest at the post-BMT 3 months. Serum TSH sharply decreased to nadir at 1 week and gradually recovered. Serum free T4 significantly increased during 3 weeks and then returned to basal level. Mean levels of serum IL-8 significantly increased at 1 week after BMT. Mean levels of serum IL-10 significantly increased until 4 weeks after BMT. No significant correlation was found between serum thyroid hormone parameters and cytokines (IL-8, IL-10) after adjusting steroid doses during the entire study period. In conclusion, ESS developed frequently following allogeneic BMT and cytokine levels were increased in post-BMT patients. However, no significant correlation was found between serum thyroid hormone parameters and these cytokines.

The effect of bone marrow transplantation on the osteoblastic differentiation of human bone marrow stromal cells.

Osteoporosis is a serious and relatively common complication of transplantation procedures. However, little is known about the exact mechanism or severity of osteoporosis complicated by bone marrow transplantation (BMT). We conducted both ex vivo and clinical studies to identify the mechanism and extent of bone loss after BMT. In a prospective clinical study, we intended to identify the changes in bone turnover markers and bone mineral density (BMD) after BMT. During a 1-yr follow-up, BMD was measured before BMT and 1 yr after BMT in 67 patients undergoing BMT. Biochemical markers of bone formation and resorption were measured in all patients at short-term intervals during the yearlong follow-up. In ex vivo study, we cultured human bone marrow cells of normal controls and BMT recipients in osteogenic medium and compared their osteogenic potential. Using a DNA fingerprinting method, we also investigated the origin of bone marrow stromal cells that were harvested 3-4 wk after BMT. In a clinical study of 67 patients undergoing BMT, the mean serum carboxy-terminal cross-linked telopeptide of type I collagen increased progressively until 4 wk after BMT. Thereafter, it began to decrease and reached basal values after 1 yr. Serum osteocalcin decreased progressively until 3 wk after BMT and reached basal values after 3 months. One year after BMT, lumbar spine BMD had decreased by 3.3% (P < 0.05), and total proximal femoral BMD had decreased by 8.9% (P < 0.001). For the ex vivo study, bone marrow was obtained from healthy donors (n = 7) and transplant recipients (n = 7). Then, mononuclear cells including marrow stromal cells were isolated and cultured to osteoblastic lineage. Alkaline phosphatase activities of each group were measured by the time course of secondary culture, and the mineralizing potentials were compared between the two groups. Cells cultured in our system showed characteristics of osteoblast-like cells differentiated from marrow stromal cells. They were initially in a fibroblastic-like spindle shape and became cuboidal with the formation of nodules that were later confluent. The cells were stained to both alkaline phosphatase histochemistry and Von Kossa histochemistry, demonstrating that these cells were of osteoblastic lineage differentiating from marrow stromal cells. The mean time required for the near-confluence in the primary culture was 15 and 22.9 d in healthy donors and transplant recipients, respectively (P = 0.003). Alkaline phosphatase activity was significantly lower in the bone marrow recipients than in the healthy donors at d 7 and 10 of the secondary cultures. The period at which peak activity of alkaline phosphatase was reached was also delayed in the osteoblasts derived from BMT recipient bone marrow compared with those of healthy donors. Using Von Kossa histochemistry, much more mineralization was observed in osteoblasts of healthy donors than those of BMT recipients. After BMT, although the peripheral mononuclear cells in the recipients were of donor origin, the bone marrow stromal cells were of recipient origin according to the PCR analysis using YNZ 22 mini-satellite probe. In conclusion, the differentiation of bone marrow stromal cells into osteoblasts was impaired after BMT, and this might contribute to post-BMT bone loss.