Jeppe Gram

Six novel missense mutations in the LDL receptor-related protein 5 (LRP5) gene in different conditions with an increased bone density.

Bone is a dynamic tissue that is subject to the balanced processes of bone formation and bone resorption. Imbalance can give rise to skeletal pathologies with increased bone density. In recent years, several genes underlying such sclerosing bone disorders have been identified. The LDL receptor-related protein 5 (LRP5) gene has been shown to be involved in both osteoporosis-pseudoglioma syndrome and the high-bone-mass phenotype and turned out to be an important regulator of peak bone mass in vertebrates. We performed mutation analysis of the LRP5 gene in 10 families or isolated patients with different conditions with an increased bone density, including endosteal hyperostosis, Van Buchem disease, autosomal dominant osteosclerosis, and osteopetrosis type I. Direct sequencing of the LRP5 gene revealed 19 sequence variants. Thirteen of these were confirmed as polymorphisms, but six novel missense mutations (D111Y, G171R, A214T, A214V, A242T, and T253I) are most likely disease causing. Like the previously reported mutation (G171V) that causes the high-bone-mass phenotype, all mutations are located in the aminoterminal part of the gene, before the first epidermal growth factor-like domain. These results indicate that, despite the different diagnoses that can be made, conditions with an increased bone density affecting mainly the cortices of the long bones and the skull are often caused by mutations in the LRP5 gene. Functional analysis of the effects of the various mutations will be of interest, to evaluate whether all the mutations give rise to the same pathogenic mechanism.

Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone

We conducted this study to assess the prevalence of vitamin D insufficiency in a population of normal perimenopausal women, to examine the influence of sun exposure and vitamin D intake on the concentration of 25-hydroxyvitamin D (25OHD) and to examine the association between parathyroid hormone (PTH) and 25OHD. A total of 2016 healthy women aged 45-58, who had recently undergone a natural menopause, were enrolled over a 2.5-year period in the Danish Osteoporosis Prevention Study. A marked seasonal fluctuation of 25OHD was seen, with an abrupt rise in June and high values until October. The fluctuation could be related to number of hours of sunshine per month with a two months time lag. Dietary vitamin D intake, vitamin supplementation, sunlight exposure, and use of sun-bed were all significantly related to 25OHD concentrations. Sun exposure seemed to contribute the most. The overall prevalence of vitamin D deficiency (defined as serum ) was 7 %. However, in the subgroup avoiding direct sunshine and abstaining from vitamin D supplementation 32.8 % were vitamin D deficient in the winter-spring period. Although mean PTH was increased in the group with low serum 25OHD, PTH was not a sensitive marker of hypovitaminosis D in the individual, as only 16 % of those with vitamin D deficiency had PTH levels above normal range. Thus, we have shown, that healthy middle-aged Danish women are prone to vitamin D insufficiency in the winter-spring period, if they avoid sun exposure in the summer period and abstain from vitamin D supplementation.

Acidification of the Osteoclastic Resorption Compartment Provides Insight into the Coupling of Bone Formation to Bone Resorption

Patients with defective osteoclastic acidification have increased numbers of osteoclasts, with decreased resorption, but bone formation that remains unchanged. We demonstrate that osteoclast survival is increased when acidification is impaired, and that impairment of acidification results in inhibition of bone resorption without inhibition of bone formation. We investigated the role of acidification in human osteoclastic resorption and life span in vitro using inhibitors of chloride channels (NS5818/NS3696), the proton pump (bafilomycin) and cathepsin K. We found that bafilomycin and NS5818 dose dependently inhibited acidification of the osteoclastic resorption compartment and bone resorption. Inhibition of bone resorption by inhibition of acidification, but not cathepsin K inhibition, augmented osteoclast survival, which resulted in a 150 to 300% increase in osteoclasts compared to controls. We investigated the effect of inhibition of osteoclastic acidification in vivo by using the rat ovariectomy model with twice daily oral dosing of NS3696 at 50 mg/kg for 6 weeks. We observed a 60% decrease in resorption (DPYR), increased tartrate-resistant acid phosphatase levels, and no effect on bone formation evaluated by osteocalcin. We speculate that attenuated acidification inhibits dissolution of the inorganic phase of bone and results in an increased number of nonresorbing osteoclasts that are responsible for the coupling to normal bone formation. Thus, we suggest that acidification is essential for normal bone remodeling and that attenuated acidification leads to uncoupling with decreased bone resorption and unaffected bone formation.

Hormonal replacement therapy reduces forearm fracture incidence in recent postmenopausal women — results of the Danish Osteoporosis Prevention Study

OBJECTIVESnTo study the fracture reducing potential of hormonal replacement therapy (HRT) in recent postmenopausal women in a primary preventive scenario.nnnMETHODSnProspective controlled comprehensive cohort trial: 2016 healthy women aged 45-58 years, from three to 24 months past last menstrual bleeding were recruited from a random sample of the background population. Mean age was 50. 8+/-2.8 years, and the number of person years followed was 9335.3. There were two main study arms: a randomised arm (randomised to HRT; n=502, or not; n=504) and a non-randomised arm (on HRT; n=221, or not; n=789 by own choice). First line HRT was oral sequential oestradiol/norethisterone in women with intact uterus and oral continuous oestradiol in hysterectomised women.nnnRESULTSnAfter five years, a total of 156 fractures were sustained by 140 women. There were 51 forearm fractures in 51 women. By intention-to-treat analysis (n=2016), overall fracture risk was borderline statistically significantly reduced (RR=0.73, 95% CI: 0.50-1.05), and forearm fracture risk was significantly reduced (RR=0.45, 95% CI: 0.22-0.90) with HRT. Restricting the analysis to women who had adhered to their initial allocation of either HRT (n=395) or no HRT (n=977) showed a significant reduction in both the overall fracture risk (RR=0.61, 95% CI: 0.39-0.97) and the risk of forearm fractures (RR=0.24, 95% CI: 0.09-0.69). Compliance with HRT was 65% after five years.nnnCONCLUSIONSnIt is possible to reduce the number of forearm fractures and possibly the total number of fractures in recent postmenopausal women by use of HRT as primary prevention.

Cross calibration of QDR-2000 and QDR-1000 dual-energy X-ray densitometers for bone mineral and soft-tissue measurements

Replacement of dual energy X-ray densitometry (DXA) equipment may be necessary in many labs with time, or new equipment may be added. In this context we compared patient scans between a Hologic QDR-1000W and a QDR-2000 (n = 29-43, depending on anatomic region) and between QDR-2000 single beam (SB) and fan beam (FB) modes (n = 40-62) as a quality control measure. A total of 83 subjects (79 females and four males) with a wide range of bone mineral densities (BMD) were studied. There was a linear relationship between results with the QDR-1000W and QDR-2000 in SB mode, and between SB and FB mode on the QDR-2000, but the magnitude of the coefficients and constants differed for the different anatomic regions. In SB mode the QDR-2000 underestimated whole body and forearm BMD by 3% relative to the QDR-1000W, even after cross calibration using a spine phantom. Femoral total BMD was slightly, but not significantly, underestimated. Thus, additional postanalysis correction had to be applied to forearm and whole-body scans. In FB with the QDR-2000, spine and whole-body BMD was underestimated by 3%, but femur total and neck BMD was overestimated by 2.2 and 2.8%, respectively, compared with SB scans on the same device. Soft-tissue composition with FB (enhanced analysis protocol) on the QDR-2000 differed greatly from that obtained using SB (standard protocol). Lean tissue mass was 4 kg lower and fat mass 4 kg higher in FB mode.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormone Replacement Therapy Dissociates Fat Mass and Bone Mass, and Tends to Reduce Weight Gain in Early Postmenopausal Women: A Randomized Controlled 5-Year Clinical Trial of the Danish Osteoporosis Prevention Study†

The aim of this study was to study the influence of hormone replacement therapy (HRT) on weight changes, body composition, and bone mass in early postmenopausal women in a partly randomized comprehensive cohort study design. A total of 2016 women ages 45–58 years from 3 months to 2 years past last menstrual bleeding were included. One thousand were randomly assigned to HRT or no HRT in an open trial, whereas the others were allocated according to their preferences. All were followed for 5 years for body weight, bone mass, and body composition measurements. Body weight increased less over the 5 years in women randomized to HRT (1.94 ± 4.86 kg) than in women randomized to no HRT (2.57 ± 4.63, p = 0.046). A similar pattern was seen in the group receiving HRT or not by their own choice. The smaller weight gain in women on HRT was almost entirely caused by a lesser gain in fat. The main determinant of the weight gain was a decline in physical fitness. Women opting for HRT had a significantly lower body weight at inclusion than the other participants, but the results in the self‐selected part of the study followed the pattern found in the randomized part. The change in fat mass was the strongest predictor of bone changes in untreated women, whereas the change in lean body mass was the strongest predictor when HRT was given. Body weight increases after the menopause. The gain in weight is related to a decrease in working capacity. HRT is associated with a smaller increase in fat mass after menopause. Fat gain protects against bone loss in untreated women but not in HRT‐treated women. The data suggest that womens attitudes to HRT are more positive if they have low body weight, but there is no evidence that the conclusions in this study are skewed by selection bias.

Cytokines and bone loss in a 5-year longitudinal study : Hormone replacement therapy suppresses serum soluble interleukin-6 receptor and increases interleukin-1-receptor antagonist : The Danish Osteoporosis Prevention Study

The proinflammatory cytokines interleukin‐1β (IL‐1β) and IL‐6 may play a central role in the acceleration of postmenopausal bone loss, but observational studies have led to contradictory results. Estrogen‐dependent changes in the production of IL‐1 receptor antagonist (IL‐1ra) and the soluble IL‐6 receptor (sIL‐6R) potentially modify cytokine bioactivity. We therefore assessed the impact of menopause and hormone replacement therapy (HRT) on cytokines and activity modifiers in serum within a 5‐year longitudinal study. One hundred sixty perimenopausal women (age 50.1 ± 2.8 years) were randomized to HRT or no treatment. Serum IL‐6 increased with age (r = 0.16; p < 0.05), but cytokines did not correlate with baseline bone mineral density (BMD). HRT led to small increases in IL‐1ra (p < 0.001) and IL‐6 (p < 0.05), with a decrease in sIL‐6R (p < 0.01) and no change in IL‐1β. No changes were observed in the control group. IL‐1ra was inversely correlated with bone loss at the ultradistal forearm (r = 0.29; p < 0.05) and to a lesser degree at the spine (r = 0.20; p = 0.09). In addition, there was a weak positive correlation between sIL‐6R and bone loss at the ultradistal forearm (r = 0.26; p < 0.05). High IL‐6 levels were associated with slower bone loss (spine r = 0.31, p < 0.01) and controlling for age did not diminish this association. The percent change in sIL‐6R during HRT was correlated with the bone loss at the femoral neck (r = −0.29; p < 0.01) and weakly with bone loss in the spine (r = −0.16; p = 0.17). In conclusion, serum IL‐1ra and sIL‐6R are influenced by HRT and are associated with the rate of bone loss in perimenopausal women.

Localization of a gene for autosomal dominant osteopetrosis (Albers-Schonberg disease) to chromosome 1p21.

Albers-Schönberg disease, the classical form of osteopetrosis, is an autosomal dominant condition with generalized increased skeletal density due to reduced bone resorption. Characteristic radiological findings are generalized osteosclerosis, with, most typically, end-plate sandwichlike thickening of the vertebrae (Rugger-Jersey spine) and the bone-within-bone (endobones) phenomenon. We studied an extended kindred with Albers-Schönberg disease and found linkage with several markers from chromosome 1p21. The Albers-Schönberg gene is located in a candidate region of approximately 8.5 cM flanked by markers D1S486 and D1S2792. A maximum LOD score (Z(max)) of 4.09 was obtained in multipoint analysis at loci D1S239/D1S248. Possible linkage of osteopetrosis to this chromosomal region was analyzed because the CSF-1 gene, which is mutated in the op/op mouse model for osteopetrosis, is located in 1p21. However, SSCP and mutation analysis in patients did not reveal any abnormality, which excludes the CSF-1 gene as the disease-causing gene. This was confirmed by refined physical mapping of the CSF-1 gene outside the candidate region for the Albers-Schönberg gene. The identification of the molecular defect underlying Albers-Schönberg disease will therefore be dependent on the isolation of other genes from an 8.5-cM candidate region on chromosome 1p21.

Premenopausal smoking and bone density in 2015 perimenopausal women

The importance of cigarette smoking in relation to bone mass remains uncertain, especially in younger women. In a recent meta‐analysis including 10 studies in premenopausal women no effect was seen in this age group. We used baseline data from a large national cohort study (Danish Osteoporosis Prevention Study [DOPS]) to study the cumulated effect of pre‐ and perimenopausal smoking on bone mineral density (BMD) measured shortly after the cessation of cyclic bleedings. Baseline observations on 2015 recently menopausal women were available. Eight hundred thirty‐two women were current smokers and 285 were exsmokers. Significant negative associations of cigarette smoking coded as current, ex‐, or never smoking were seen on bone mass in the lumbar spine (P = 0.012), femoral neck (P < 0.001), and total body (P < 0.001). Quantitatively, the differences between current smokers and never smokers were limited to 1.6, 2.9, and 1.9%, respectively. A statistical interaction was found between smoking and fat mass, indicating that women in the highest tertile of fat mass were unaffected by cigarette smoking. Serum vitamin D levels and osteocalcin were inversely related to the number of cigarettes smoked per day (r = 0.11 and P < 0.001; r = 0.17 and P = 0.04), respectively. Bone alkaline phosphatase (BALP) and urinary hydroxyproline (U‐OHP) were unaffected by current smoking. The average cumulated effect of premenopausal smoking on bone is small but biologically significant. Reduced body mass in smokers explains part of the negative effect on the skeleton and a complex interaction between smoking and fat mass on the skeleton is indicated. Serum levels of 25‐hydroxyvitamin D (25‐OHD) and osteocalcin are lower in smokers, which may effect rate of bone loss.

Improving compliance with hormonal replacement therapy in primary osteoporosis prevention

OBJECTIVESnTo evaluate whether introduction of treatment alternatives would improve compliance with hormonal replacement therapy (HRT) as primary osteoporosis prevention in women not tolerating the first line osteoporosis prevention schedule.nnnMATERIAL AND METHODSnFollow-up in four hospitals participating in the Danish Osteoporosis Prevention Study. A total of 706 peri- and postmenopausal women aged 45-57 years between 3 and 24 months from last menstrual bleeding took part, 489 women were randomised to HRT and 217 received HRT by personal choice. A total of 135 (19%) women were hysterectomised. HRT was given as oral or transdermal oestradiol supplemented with progestogen. If the initial treatment allocation was not acceptable several alternatives were available in a pragmatic approach.nnnRESULTSnCompliance with first treatment schedule was lower in women with intact uterus (at 5 years: 48.3 +/- 2.4% compliance) than in hysterectomised (64.7 +/- 5.8%, P < 0.001 in a Cox analysis) but did not differ after the introduction of HRT alternatives (67.0 +/- 2.9 vs 77.8 +/- 5.9, P = 0.12). Compliance decreased with increasing age at treatment start (RR = 1.11, P < 0.001) in women with intact uterus but not in hysterectomised women (P = 0.96). Headache/migraine was more frequent among women with intact uterus on oral sequential oestrogen plus progestogen than among hysterectomised women receiving oral continuous oestrogen (RR = 11.3, P < 0.01).nnnCONCLUSIONSnIt seems possible to maintain a high HRT compliance by a pragmatic approach including offering alternative HRT formulations to women not tolerating the primary HRT. Further research into long-term compliance with HRT and cost-benefit is warranted.