Effects of bone disease and calcium supplementation on antioxidant enzymes in postmenopausal women

Effect of selenium supplementation on musculoskeletal health in older women: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Observational and preclinical studies show associations between selenium status, bone health, and physical function. Most adults in Europe have serum selenium below the optimum range. We hypothesised that selenium supplementation could reduce pro-resorptive actions of reactive oxygen species on osteoclasts and improve physical function.

METHODS

We completed a 6-month randomised, double-blind, placebo-controlled trial. We recruited postmenopausal women older than 55 years with osteopenia or osteoporosis at the Northern General Hospital, Sheffield, UK. Participants were randomly assigned 1:1:1 to receive selenite 200 μg, 50 μg, or placebo orally once per day. Medication was supplied to the site blinded and numbered by a block randomisation sequence with a block size of 18, and participants were allocated medication in numerical order. All participants and study team were masked to treatment allocation. The primary endpoint was urine N-terminal cross-linking telopeptide of type I collagen (NTx, expressed as ratio to creatinine) at 26 weeks. Analysis included all randomly assigned participants who completed follow-up. Groups were compared with analysis of covariance with Hochberg testing. Secondary endpoints were other biochemical markers of bone turnover, bone mineral density, short physical performance battery, and grip strength. Mechanistic endpoints were glutathione peroxidase, highly sensitive C-reactive protein, and interleukin-6. This trial is registered with EU clinical trials, EudraCT 2016-002964-15, and ClinicalTrials.gov, NCT02832648, and is complete.

FINDINGS

120 participants were recruited between Jan 23, 2017, and April 11, 2018, and randomly assigned to selenite 200 μg, 50 μg, or placebo (n=40 per group). 115 (96%) of 120 participants completed follow-up and were included in the primary analysis (200 μg [n=39], 50 μg [n=39], placebo [n=37]). Median follow-up was 25·0 weeks (IQR 24·7-26·0). In the 200 μg group, mean serum selenium increased from 78·8 (95% CI 73·5-84·2) to 105·7 μg/L (99·5-111·9). Urine NTx to creatinine ratio (nmol bone collagen equivalent:mmol creatinine) did not differ significantly between treatment groups at 26 weeks: 40·5 (95% CI 34·9-47·0) for placebo, 43·4 (37·4-50·5) for 50 μg, and 42·2 (37·5-47·6) for 200 μg. None of the secondary or mechanistic endpoint measurements differed between treatment groups at 26 weeks. Seven (6%) of 120 participants were withdrawn from treatment at week 13 due to abnormal thyroid-stimulating hormone concentrations (one in the 200 μg group, three in the 50 μg group, and three in the placebo group) and abnormal blood glucose (one in the 50 μg group). There were three serious adverse events: a non-ST elevation myocardial infarction at week 18 (in the 50 μg group), a diagnosis of bowel cancer after routine population screening at week 2 (in the placebo group), and a pulmonary embolus due to metastatic bowel cancer at week 4 (in the 200 μg group). All severe adverse events were judged by the principal investigator as unrelated to trial medication.

INTERPRETATION

Selenium supplementation at these doses does not affect musculoskeletal health in postmenopausal women.

FUNDING

UK National Institute for Health Research Efficacy and Mechanism Evaluation programme.

Molecular mechanisms of osteoporotic hip fractures in elderly women

A common manifestation of age-related bone loss and resultant osteoporosis are fractures of the hip. Age-related osteoporosis is thought to be determined by a number of intrinsic factors including genetics, hormonal changes, changes in levels of oxidative stress, or an inflammatory status associated with the aging process. The aim of this study was to investigate gene expression and bone architecture in bone samples derived from elderly osteoporotic women with hip fractures (OP) in comparison to bone samples from age matched women with osteoarthritis of the hip (OA). Femoral heads and adjacent neck tissue were collected from 10 women with low-trauma hip fractures (mean age 83±6) and consecutive surgical hip replacement. Ten bone samples from patients undergoing hip replacement due to osteoarthritis (mean age 80±5) served as controls. One half of each bone sample was subjected to gene expression analysis. The second half of each bone sample was analyzed by microcomputed tomography. From each half, samples from four different regions, the central and subcortical region of the femoral head and neck, were analyzed. We could show a significantly decreased expression of the osteoblast related genes RUNX2, Osterix, Sclerostin, WNT10B, and Osteocalcin, a significantly increased ratio of RANKL to Osteoprotegerin, and a significantly increased expression of the enzymes superoxide dismutase 2 (SOD2) and glutathione peroxidase GPX3, and of the inflammatory cytokine IL6 in bone samples from hip fracture patients compared to controls. Major microstructural changes in OP bone were seen in the neck and were characterized by a significant decrease of bone volume, trabecular number, and connectivity density and a significant increase of trabecular separation. In conclusion, our data give evidence for a decreased expression of osteoblast related genes and increased expression of osteoclast related genes. Furthermore, increased expression of SOD2 and GPX3 suggest increased antioxidative activity in bone samples from elderly osteoporotic women with hip fractures.

Calcium plus vitamin D supplementation influences biomarkers of inflammation and oxidative stress in overweight and vitamin D-deficient women with polycystic ovary syndrome: a randomized double-blind placebo-controlled clinical trial

OBJECTIVE

This study was conducted to determine the effects of calcium plus vitamin D supplementation on inflammatory factors and biomarkers of oxidative stress among overweight vitamin D-deficient women with polycystic ovary syndrome (PCOS).

DESIGN, PATIENTS AND MEASUREMENTS

This randomized double-blind placebo-controlled clinical trial was performed among 104 overweight vitamin D-deficient women diagnosed with PCOS aged 18-40 years. Participants were randomly divided into four groups. Group A received 1000 mg calcium daily and vitamin D placebo weekly (N = 26), group B 50000 IU vitamin D weekly and calcium placebo daily (N = 26), group C 1000 mg calcium daily plus 50000 IU vitamin D weekly (N = 26) and group D calcium placebo daily plus vitamin D placebo weekly (N = 26) for 8 weeks. Fasting blood samples were taken at baseline and 8 weeks after intervention to measure inflammatory factors and biomarkers of oxidative stress.

RESULTS

After 8 weeks, individuals taking calcium plus vitamin D supplements had greater decreases in homoeostatic model assessment beta-cell function (HOMA-B) score (-11·1 vs -8·6, -3·4 and 13·7, respectively, P = 0·03), serum high-sensitivity C-reactive protein (hs-CRP) (-948·3 vs 802·3, -383·8 and 618·2 ng/ml, respectively, P = 0·04) and plasma malondialdehyde (MDA) concentrations (-0·6 vs -0·5, -0·1 and 0·6 μmol/l, respectively, P = 0·009), and significant increases in plasma total antioxidant capacity (TAC) (35·2 vs 21·1, 22·5 and -153·8 mmol/l, respectively, P = 0·006) and glutathione (GSH) levels (216·0 vs 3·9, -47·5 and -160·8 μmol/l, respectively, P = 0·001) compared with calcium alone, vitamin D alone and placebo groups. Calcium plus vitamin D cosupplementation did not influence plasma NO and catalase levels.

CONCLUSIONS

We found that calcium plus vitamin D cosupplementation for 8 weeks among overweight and vitamin D-deficient women with PCOS had beneficial effects on inflammatory factor and biomarkers of oxidative stress.

Correlation between bone mineral density and oxidative stress in postmenopausal women

BACKGROUND

Postmenopausal osteoporosis affects large fraction of elderly women. Oxidative stress (OS) appears to be involved in its pathogenesis. The scarcity of human studies focusing on the correlation between bone mineral density (BMD) and OS in postmenopausal women has prompted us to study on this issue.

MATERIALS AND METHODS

We conducted a cross sectional study in 95 subjects, between 21-65 years of age, including postmenopausal osteoporotic females (n = 35), healthy postmenopausal females (n = 30) and healthy females in reproductive age group (n = 30). We measured serum antioxidant activity of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and total antioxidant power (TAP). BMD was obtained at lumbar spine and femur neck by dual-energy X-ray absorptiometry scan. Osteoporosis was considered when subjects had a BMD of 2.5 standard deviations or more below the mean value for young adults.

RESULTS

Serum GPx, SOD, catalase and TAP level were found significantly lower in osteoporotic postmenopausal group as compared to healthy postmenopausal women and women in healthy reproductive age group healthy reproductive women (P < 0.005). but correlation between BMD and serum antioxidants were not found to be statistically significant (P > 0.005).

CONCLUSION

These findings support that oxidative stress plays an important role in pathogenesis of postmenopausal osteoporosis. We did not find any significant association between BMD and serum level of antioxidants (P > 0.05). The failure to detect this association does not preclude the role of OS in osteoporosis because OS is complex and dynamic process.

BMD values and GSTM3 gene polymorphisms in combination with GSTT1/GSTM1 genes: a genetic association study in Slovenian elderly

BACKGROUND

Much research suggests that oxidative stress is associated with osteoporosis development. Glutathione S-transferases mu3 (GSTM3) are an important group of detoxifying enzymes that eliminate oxidative stress-related products.

OBJECTIVES

To examine the associations of functional GSTM3 gene polymorphisms (Val224Ile and insdelAGG), their haplotypes and, in combination with GSTT1-null and GSTM1-null polymorphisms, with bone mineral density (BMD) measured at femoral neck (_fn), lumbar spine (_ls) and total hip (_th) and biochemical bone turnover markers in 593 Slovenian elderly women and 119 Slovenian elderly men.

METHODS

GSTM3, GSTT1-null and GSTM1-null gene polymorphisms using sizing denaturing high-performance liquid chromatography, triplex PCR method or real-time PCR; BMD_fn, BMD_ls, BMD_th values using dual energy X-ray absorptiometry, and plasma osteocalcin, serum bone alkaline phosphatase and free soluble tumor necrosis factor (ligand) superfamily, member 11 (sRANKL) concentrations using a solid-phase, two-site chemiluminescent enzyme-labeled immunometric assay, radioimmunoassay or enzyme immunoassay were determined. Statistical analysis was performed using one-way and two-way ANCOVA with adjustment for potential confounders (age, height and weight).

RESULTS

The (borderline) significant differences in BMD_th and BMD_fn values between genotype subgroups of Val224Ile polymorphism of GSTM3 gene (p = 0.057 and 0.053, respectively) with the lowest BMD values among heterozygotes and between 224Ile-insAGG haplotype subgroups (p = 0.048 and 0.019, respectively) were found. Significant differences of BMD_fn between the 224Ile-delAGG haplotype subgroups were observed (p = 0.012). Association of 224Val-insAGG with BMD_fn was of borderline significance (p = 0.062).

CONCLUSION

The results of our study demonstrate the genetic association between detoxifying enzyme GSTM3 and BMD variation, suggesting that the Val224Ile polymorphism and 224Ile-insAGG haplotype could be used for further evaluation of the impact of GSTs gene polymorphisms on osteoporosis, using larger cohorts in searching for osteoporosis risk markers.