Monika H. E. Christensen

Glucocorticoid replacement therapy and pharmacogenetics in Addison's disease: effects on bone.

UNLABELLED Context Patients with primary adrenal insufficiency (Addisons disease) receive more glucococorticoids than the normal endogenous production, raising concern about adverse effects on bone. OBJECTIVE To determine i) the effects of glucocorticoid replacement therapy on bone, and ii) the impact of glucocorticoid pharmacogenetics. DESIGN, SETTING AND PARTICIPANTS A cross-sectional study of two large Addisons cohorts from Norway (n=187) and from UK and New Zealand (n=105). MAIN OUTCOME MEASURES Bone mineral density (BMD) was measured; the Z-scores represent comparison with a reference population. Blood samples from 187 Norwegian patients were analysed for bone markers and common polymorphisms in genes that have been associated with glucocorticoid sensitivity. RESULTS Femoral neck BMD Z-scores were significantly reduced in the patients (Norway: mean -0.28 (95% confidence intervals (CI) -0.42, -0.16); UK and New Zealand: -0.21 (95% CI -0.36, -0.06)). Lumbar spine Z-scores were reduced (Norway: -0.17 (-0.36, +0.01); UK and New Zealand: -0.57 (-0.78, -0.37)), and significantly lower in males compared with females (P=0.02). The common P-glycoprotein (ABCB1) polymorphism C3435T was significantly associated with total BMD (CC and CT>TT P=0.015), with a similar trend at the hip and spine. CONCLUSIONS BMD at the femoral neck and lumbar spine is reduced in Addisons disease, indicating undesirable effects of the replacement therapy. The findings lend support to the recommendations that 15-25 mg hydrocortisone daily is more appropriate than the higher conventional doses. A common polymorphism in the efflux transporter P-glycoprotein is associated with reduced bone mass and might confer susceptibility to glucocorticoid induced osteoporosis.

Seasonal and age-related differences in serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and parathyroid hormone in patients from Western Norway.

Abstract Objective. The aim of this study was to investigate the seasonal and age-related variation of vitamin D and PTH serum concentrations in a large general patient population in Western Norway. Design. A retrospective study was conducted at the Hormone laboratory, Haukeland University Hospital, Bergen, Norway. All analyses of 25-hydroxyvitamin D (25(OH)D) (n = 8325), 1,25-dihydroxyvitamin D (1,25(OH)2D) (n = 4509) and PTH (n = 4203) requested from private practitioners from 2005 to 2008 were included. All three analytes were available in 1551 subjects. Subjects. Mean age of the study population was 49.8 years and 70.9% of the samples were from women. Results. The highest concentrations of 25(OH)D and 1,25(OH)2D were observed in July–September. In April 43% of the studied population had 25(OH)D concentrations below 50 nmol/L. There was a positive correlation between 25(OH)D and 1,25(OH)2D (p < 0.001). The levels of 25(OH)D and PTH were negatively correlated (p < 0.001) while 1,25(OH)2D and PTH showed a weak positive correlation (p = 0.015). We observed higher concentrations of 25(OH)D (p = 0.003) and lower 1,25(OH)2D levels (p < 0.001) in the older age groups. PTH increased throughout the whole age span (p < 0.001). Conclusion. We observed a seasonal variation in 25(OH)D and 1,25(OH)2D with low serum concentrations during winter/early spring while PTH showed an inverse pattern. Higher levels of PTH in winter and the elderly may reflect an impaired vitamin D status that may affect calcium homeostasis and bone health.

Primary hyperparathyroidism influences the expression of inflammatory and metabolic genes in adipose tissue.

Background Primary hyperparathyroidism (PHPT) is characterised by increased production of parathyroid hormone (PTH) resulting in elevated serum calcium levels. The influence on bone metabolism with altered bone resorption is the most studied clinical condition in PHPT. In addition to this, patients with PHPT are at increased risk of non-skeletal diseases, such as impaired insulin sensitivity, arterial hypertension and increased risk of death by cardiovascular diseases (CVD), possibly mediated by a chronic low-grade inflammation. The aim of this study was to investigate whether adipose tissue reflects the low-grade inflammation observed in PHPT patients. Methodology/Principal Findings Subcutaneous fat tissue from the neck was sampled from 16 non-obese patients with PHPT and from 16 patients operated for benign thyroid diseases, serving as weight-matched controls. RNA was extracted and global gene expression was analysed with Illumina BeadArray Technology. We found 608 differentially expressed genes (q-value<0.05), of which 347 were up-regulated and 261 were down-regulated. Gene ontology analysis showed that PHPT patients expressed increased levels of genes involved in immunity and defense (e.g. matrix metallopeptidase 9, S100 calcium binding protein A8 and A9, CD14, folate receptor 2), and reduced levels of genes involved in metabolic processes. Analysis of transcription factor binding sites present in the differentially expressed genes corroborated the up-regulation of inflammatory processes. Conclusions/Significance Our findings demonstrate that PHPT strongly influences gene regulation in fat tissue, which may result in altered adipose tissue function and release of pathogenic factors that increase the risk of CVD.

1,25-Dihydroxyvitamin D and the Vitamin D Receptor Gene Polymorphism Apa1 Influence Bone Mineral Density in Primary Hyperparathyroidism

OBJECTIVE Parathyroid hormone (PTH) and vitamin D are the most important hormones regulating calcium metabolism. In primary hyperparathyroidism (PHPT) excessive amounts of PTH are produced. Bone turnover is enhanced, leading to reduced bone mineral density and elevated levels of serum calcium. The aim of this study was to investigate relations between serum levels of 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)(2)D) and bone mineral density, as well as known genetic polymorphisms in the vitamin D receptor and enzymes metabolising vitamin D in patients with PHPT. DESIGN/SUBJECTS We conducted a cross-sectional study of 52 patients with PHPT. RESULTS Mean level of 25(OH)D was 58.2 nmol/L and median 1,25(OH)(2)D level was 157 pmol/L. Among our patients with PHPT 36.5% had 25(OH)D levels below 50 nmol/L. Serum 1,25(OH)(2)D was inversely correlated to bone mineral density in distal radius (p = 0.002), but not to bone mineral density at lumbar spine or femoral neck. The vitamin D receptor polymorphism Apa1 (rs7975232) was associated with bone mineral density in the lumbar spine. CONCLUSIONS The results suggest that PHPT patients with high blood concentrations of 1,25(OH)(2)D may have the most deleterious skeletal effects. Randomized, prospective studies are necessary to elucidate whether vitamin D supplementation additionally increases serum 1,25(OH)(2)D and possibly enhances the adverse effects on the skeleton in patients with PHPT.

Vitamin B6 status and interferon-γ-mediated immune activation in primary hyperparathyroidism.

Primary hyperparathyroidism (PHPT) has been associated with low‐grade inflammation and elevated risk of cardiovascular disease (CVD). In inflammatory conditions, interferon‐γ (IFN‐γ) activity is enhanced and a decreased circulating concentration of vitamin B6 is often observed. Such changes in IFN‐γ activity or vitamin B6 levels have been associated with increased incidence of CVD. The aim of the study was to investigate systemic markers of IFN‐γ‐mediated immune activation, such as neopterin, the kynurenine‐to‐tryptophan ratio (KTR) and kynurenine pathway metabolites, as well as B6 vitamers in patients with PHPT.

Novel inflammatory biomarkers in primary hyperparathyroidism.

OBJECTIVE Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and increased risk of cardiovascular disease (CVD). The aim of the study was to investigate systemic levels of pro-inflammatory proteins that previously have not been examined in patients with PHPT. The selection of the pro-inflammatory biomarkers included in this study, MMP9, S100A4, S100A8/A9 and the receptors sCD14 and RAGE, was based on a previous microarray screen of mRNAs in adipose tissue from PHPT patients. DESIGN A prospective study was conducted on a total of 57 patients with PHPT and a control group of 20 healthy blood donors. METHODS PHPT patients with normalisation of serum calcium levels after parathyroidectomy were followed for 6 months. Forty-two patients participated in the longitudinal study, in which blood samples were taken at inclusion, and 1, 3 and 6 months after surgery. RESULTS We observed increased serum levels of MMP9 (P=0.029), S100A4 (P<0.001) and sCD14 (P=0.002) in the 57 patients with PHPT compared to the control-group. During 6 months of follow up, S100A4 (P=0.022) and sCD14 (0.002) decreased significantly, while serum levels of MMP9 increased (P=0.025). CONCLUSIONS The results demonstrate an increased inflammatory response in PHPT patients shown by elevated MMP9, S100A4 and sCD14 at inclusion. During the 6 months of follow-up, MMP9 increased further, possibly due to the tissue repair process after parathyroidectomy. S100A4 and sCD14 decreased after surgery demonstrating a partial reversal of the systemic inflammation.

Estradiol determines the effects of PTH on ERα-dependent transcription in MC3T3-E1 cells

Bone remodeling is a continuous process regulated by several hormones such as estrogens and parathyroid hormone (PTH). Here we investigated the influence of PTH on estrogen receptor alpha (ERα)-dependent transcriptional activity in MC3T3-E1 osteoblasts. Cells that were transfected with an ER-responsive reporter plasmid and treated with PTH showed increased luciferase activity. However, in the presence of 17β-estradiol, we observed that PTH inhibited ERα-mediated transcription. cAMP mimicked the effects by PTH, and the findings were confirmed in COS-1 cells transfected with expression vector encoding the catalytic subunit of cAMP-dependent protein kinase (PKA). Furthermore, PTH exhibited specific effects on the mRNA expression of the decoy receptor osteoprotegerin (OPG) and the receptor activator of NF kappa-B ligand (RANKL) in MC3T3-E1 osteoblasts. In the absence of 17β-estradiol, PTH and cAMP enhanced the OPG/RANKL ratio, whereas, OPG/RANKL was suppressed when estradiol was present. In conclusion, our results indicate that the presence of estradiol determines whether PTH and cAMP stimulates or inhibits ERα-dependent activity and the OPG/RANKL mRNA expression in an osteoblastic cell line.

Physiological effects of combined thermal and electrical muscle stimulation (cTEMS) in healthy individuals: A pilot study

Objective. Adding superficial heat to electrical muscle stimulation may provide added effects. In this pilot study we investigated the effects on oxygen consumption of combined thermal and electrical muscle stimulation at different levels of heat and modes of electrical stimulation. Design. An observational clinical pilot study. Subjects. A total of 14 healthy persons aged 30–70 years. Methods. Subjects were randomly assigned to stimulation with different electrical pulse types in random order. At 38.2°C and 40.7°C heat intensity we measured peak oxygen uptake, capillary lactate, catecholamines, growth hormone and hemodynamics at 20% of the maximum output (194 mA) and at each individuals maximal stimulation intensity. Results. Multivariate analyses showed that electrical stimulation significantly increased peak oxygen uptake and the levels of lactate, catecholamine and growth hormone. Increasing the heat during electrical stimulation gave additional hemodynamic response and rise in growth hormone. We observed a dose-response relationship in peak oxygen uptake for increase in stimulation intensity. The highest oxygen uptake was observed with biphasic continuous stimulation at 7 Hz (p < 0.001). Conclusions. Biphasic low frequency electrical muscle stimulation elicited the highest oxygen uptake; higher stimulation intensity was not obtained by adding heat.

Inflammatory markers, the tryptophan-kynurenine pathway, and vitamin B status after bariatric surgery

Objective Obesity is associated with increased inflammation and insulin resistance. In conditions with chronic immune activation, low plasma vitamin B6-levels are described, as well as an increased kynurenine:tryptophan-ratio (KTR). We investigated circulating tryptophan, kynurenine and its metabolites, neopterin, B-vitamins, CRP, and HbA1c in individuals with obesity before and after bariatric surgery. Methods This longitudinal study included 37 patients with severe obesity, scheduled for bariatric surgery. Blood samples were taken at inclusion and at three months and one year postoperatively. Results We observed significant positive correlations between HbA1c and both 3-hydroxy-kynurenine and 3-hydroxyanthranilic acid at inclusion. After surgery, fasting glucose, HbA1C and triglycerides decreased, whereas HDL-cholesterol increased. Tryptophan, kynurenine and its metabolites, except for anthranilic acid, decreased during weight loss. The KTR and CRP decreased while vitamin B6 increased during the year following operation, indicating reduced inflammation (all p<0.05). Conclusions In patients with obesity subjected to bariatric surgery, levels of 3-hydroxykynurenine and 3-hydroxyanthranilic acid seemed to be positively correlated to impaired glucose tolerance. One year following surgery, plasma levels of the kynurenine metabolites were substantially decreased, along with a metabolic improvement. The relation of circulating kynurenine pathway metabolites with biomarkers of metabolic impairment in patients with obesity needs further evaluation.