24Nov 2017
MPubmed

Stem Cells Transl Med. 2017 Oct;6(10):1930-1939. doi: 10.1002/sctm.17-0054

Age-related (type-II) osteoporosis is a common and debilitating condition driven in part by the loss of bone marrow (BM) mesenchymal stromal cells (MSC) and their osteoblast progeny, leading to reduced bone formation. Current pharmacological regiments targeting age-related osteoporosis do not directly treat the disease by increasing bone formation, but instead use bisphosphonates to reduce bone resorption-a treatment designed for postmenopausal (type-I) osteoporosis. Recently, the bone regenerative capacity of MSCs has been found within a very rare population of skeletal stem cells (SSCs) residing within the larger heterogeneous BM-MSC pool. The osteoregenerative potential of SSCs would be an ideal candidate for cell-based therapies to treat degenerative bone diseases such as osteoporosis. However, to date, clinical and translational studies attempting  to improve bone formation through cell transplantation have used the larger, nonspecific, MSC pool. In this review, we will outline the physiological basis of age-related osteoporosis, as well as discuss relevant preclinical studies that use exogenous MSC transplantation with the aim of treating osteoporosis in murine models

Kiernan J, Davies JE, Stanford WL

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24Nov 2017
MPubmed

J Cell Physiol. 2017 Oct 14. doi: 10.1002/jcp.26216

The global prevalence of vitamin D deficiency appears to be increasing, and the impact of this on human health is important because of the association of vitamin D insufficiency with increased risk of osteoporosis, cardiovascular disease and some cancers. There are few studies on the genetic factors that can influence vitamin D levels. In particular, the data from twin and family-based studies have reported that circulating vitamin D concentrations are partially determined by genetic factors. Moreover, it has been shown that genetic variants (e.g., mutation) and alteration (e.g., deletion, amplification, inversion) in genes involved in the metabolism, catabolism, transport, or binding of vitamin D to it receptor, might affect vitamin D level. However, the underlying genetic determinants of plasma 25-hydroxyvitamin D3 [25(OH)D] concentrations remain to be elucidated. Furthermore, the association between epigenetic modifications such as DNA methylation and vitamin D level has now been reported in several studies. The aim of current review was to provide an overview of the possible value of loci associated to vitamin D metabolism, catabolism, and transport as well epigenetic  modification and environmental factors influencing vitamin D status.

Bahrami A, Sadeghnia HR, Tabatabaeizadeh SA, Bahrami-Taghanaki H, Behboodi N, Esmaeili H, A Ferns G, Mobarhan MG, Avan A

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24Nov 2017
MPubmed

Diabetes Res Clin Pract. 2017 Oct 18;134:153-160. doi:10.1016/j.diabres.2017.10.011

AIMS: To determine the relative risk of incident hip fracture in patients with type 1 diabetes and matched controls and to compare hip fracture rates in age- and sex-matched patients with type 1 versus type 2 diabetes. METHODS: Longitudinal observational study of 121 adults with type 1 diabetes. Age and sex matching was possible for 93 pairs of type 1 and type 2 participants. The main outcome measure was incident hip fracture hospitalisation. CONCLUSIONS: Hip fracture risk is markedly elevated in type 1 diabetes compared with age and sex-matched individuals without diabetes and with type 2 diabetes from the same population.

Hamilton EJ, Davis WA, Bruce DG, Davis TME

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24Nov 2017
MPubmed

Bone. 2018 Jan;106:22-27. doi: 10.1016/j.bone.2017.10.005

Sarcopenia and osteoporosis are among the late complications of type 1 diabetes (T1D) in adults. The aim of this study was to assess volumetric bone mineral density (BMD) and dynamic muscle function in adolescents with T1D and to assess the clinical and biochemical predictors of their musculoskeletal system. METHODS: Ninety-five children and adolescents (59 boys and 36 girls, mean age 16.2±1.2years) with T1D were included in this cross-sectional study. Study participants were divided into two groups according to the duration of the disease (<6years and >9years, respectively). CONCLUSION: T1D influences the musculoskeletal system in adolescence. Decreased muscle function could contribute to the osteoporosis reported in adult diabetic patients.

Maratova K, Soucek O, Matyskova J, Hlavka Z, Petruzelkova L, Obermannova B, Pruhova S, Kolouskova S, Sumnik Z

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24Nov 2017
MPubmed

J Bone Miner Res. 2017 Nov 4. doi: 10.1002/jbmr.3337

Denosumab reduces bone resorption and vertebral and nonvertebral fracture risk. Denosumab discontinuation increases BTMs 3 months after a scheduled dose is omitted, reaching above-baseline levels by 6 months, and decreases BMD to baseline levels by 12 months. We analyzed the risk of new or worsening vertebral fractures, especially multiple vertebral fractures, in participants who discontinued denosumab during the FREEDOM study or its Extension. Participants received ≥2 doses of denosumab or placebo Q6M, discontinued treatment, and stayed in the study ≥7 months after the last dose. Of 1001 participants who discontinued denosumab during FREEDOM or Extension, the vertebral fracture rate increased from 1.2 per 100 participant-years during the on-treatment period to 7.1, similar to participants who received and then discontinued placebo (N=470; 8.5 per 100 participant-years). Among participants with ≥1 off-treatment vertebral fracture, the proportion with multiple (>1) was larger among those who discontinued denosumab (60.7%) than placebo (38.7%; p=0.049), corresponding to a 3.4% and 2.2% risk of multiple vertebral fractures, respectively. The odds (95% CI) of developing multiple vertebral fractures after stopping denosumab were 3.9 (2.1-7. 2) times higher in those with prior vertebral fractures, sustained before or during treatment, than those without, and 1.6 (1.3-1.9) times higher with each additional year of off-treatment follow-up; among participants with available off-treatment total hip (TH) BMD measurements, the odds were 1.2 (1.1-1.3) times higher per 1% annualized TH BMD loss. The rates (per 100 participant-years) of nonvertebral fractures during the off-treatment period were similar (2.8, denosumab; 3.8, placebo). The vertebral fracture rate increased upon denosumab discontinuation to the level observed in untreated participants. A majority of participants who sustained a vertebral fracture after discontinuing denosumab had multiple vertebral fractures, with greatest risk in participants with a prior vertebral fracture. Therefore, patients who discontinue denosumab should rapidly transition to an alternative antiresorptive treatment.

Cummings SR, Ferrari S, Eastell R, Gilchrist N, Beck Jensen JE, McClung M, Roux C, Törring O, Valter I, Wang AT, Brown JP

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24Nov 2017
MPubmed

Bone. 2017 Oct;103:159-167. doi: 10.1016/j.bone.2017.06.027

Parathyroid hormone (PTH) and Notch receptors regulate bone formation by governing the function of osteoblastic cells. To determine whether PTH interacts with Notch signaling as a way to control osteoblast function, we tested the effects of PTH on Notch activity in osteoblast- and osteocyte-enriched cultures.

Induction of Notch signaling in osteocytes did not alter the inhibitory effect of PTH on Sost expression, but reduced the stimulation of Tnfsf11 mRNA levels by PTH. In agreement with these in vitro observations, male mice administered with PTH displayed suppressed Hey1 and HeyL expression in parietal bones. Transactivation experiments with a Notch reporter construct and electrophoretic mobility shift assays in osteoblast-enriched cells suggest that PTH acts by decreasing the capacity of Rbpjκ to bind to DNA. In conclusion, downregulation of Notch in osteoblasts and osteocytes may represent a mechanism contributing to the anabolic effects of PTH in bone.

Zanotti S, Canalis E

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20Oct 2017
MPubmed

2017 Aug 5;105:11-17. doi: 10.1016/j.bone.2017.08.003. [Epub ahead of print] Review.

CONCLUSION:

There appears to be an increased risk of multiple vertebral fractures after discontinuation of denosumab although strong evidence for such an effect and for measures to prevent the occurring bone loss is lacking. Clinicians and patients should be aware of this potential risk. Based on available data, a re-evaluation should be performed after 5years of denosumab treatment. Patients considered at high fracture risk should either continue denosumab therapy for up to 10years or be switched to an alternative treatment. For patients at low risk, a decision to discontinue denosumab could be made after 5years, but bisphosphonate therapy should be considered to reduce or prevent the rebound increase in bone turnover. However, since the optimal bisphosphonate regimen post-denosumab is currently unknown continuation of denosumab can also be considered until results from ongoing trials become available. Based on current data, denosumab should not be stopped without considering alternative treatment in order to prevent rapid BMD loss and a potential rebound in vertebral fracture risk.

Tsourdi E, Langdahl B, Cohen-Solal M, Aubry-Rozier B, Eriksen EF, Guañabens N, Obermayer-Pietsch B, Ralston SH, Eastell R, Zillikens MC.

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20Oct 2017
MPubmed

Nat Med. 2017 Sep;23(9):1072-1079. doi: 10.1038/nm.4385. Epub 2017 Aug 21.

Aging is associated with increased cellular senescence, which is hypothesized to drive the eventual development of multiple comorbidities. Here we investigate a role for senescent cells in age-related bone loss through multiple approaches. In particular, we used either genetic (i.e., the INK-ATTAC ‘suicide’ transgene encoding an inducible caspase 8 expressed specifically in senescent cells) or pharmacological (i.e., ‘senolytic’ compounds) means to eliminate senescent cells. We also inhibited the production of the proinflammatory secretome of senescent cells using a JAK inhibitor (JAKi). In aged (20- to 22-month-old) mice with established bone loss, activation of the INK-ATTAC caspase 8 in senescent cells or treatment with senolytics or the JAKi for 2-4 months resulted in higher bone mass and strength and better bone microarchitecture than in vehicle-treated mice. The beneficial effects of targeting senescent cells were due to lower bone resorption with either maintained (trabecular) or higher (cortical) bone formation as compared to vehicle-treated mice. In vitro studies demonstrated that senescent-cell conditioned medium impaired osteoblast mineralization and enhanced osteoclast-progenitor survival, leading to increased osteoclastogenesis. Collectively, these data establish a causal role for senescent cells in bone loss with aging, and demonstrate that targeting these cells has both anti-resorptive and anabolic effects on bone. Given that eliminating senescent cells and/or inhibiting their proinflammatory secretome also improves cardiovascular function, enhances insulin sensitivity, and reduces frailty, targeting this fundamental mechanism to prevent age-related bone loss suggests a novel treatment strategy not only for osteoporosis, but also for multiple age-related comorbidities.

Farr JN, Xu M, Weivoda MM, Monroe DG, Fraser DG, Onken JL, Negley BA, Sfeir JG, Ogrodnik MB, Hachfeld CM, LeBrasseur NK, Drake MT, Pignolo RJ, Pirtskhalava T, Tchkonia T, Oursler MJ, Kirkland JL, Khosla S

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20Oct 2017
MPubmed

N Engl J Med. 2017 Sep 11. doi: 10.1056/NEJMoa1708322. [Epub ahead of print]

We enrolled 4093 postmenopausal women with osteoporosis and a fragility fracture and randomly assigned them in a 1:1 ratio to receive monthly subcutaneous romosozumab (210 mg) or weekly oral alendronate (70 mg) in a blinded fashion for 12 months, followed by open-label alendronate in both groups. The primary end points were the cumulative incidence of new vertebral fracture at 24 months and the cumulative incidence of clinical fracture (nonvertebral and symptomatic vertebral fracture) at the time of the primary analysis (after clinical fractures had been confirmed in ≥330 patients). Secondary end points included the incidences of nonvertebral and hip fracture at the time of the primary analysis. Serious cardiovascular adverse events, osteonecrosis of the jaw, and atypical femoral fractures were adjudicated.

Results Over a period of 24 months, a 48% lower risk of new vertebral fractures was observed in the romosozumab-to-alendronate group (6.2% [127 of 2046 patients]) than in the alendronate-to-alendronate group (11.9% [243 of 2047 patients]) (P<0.001). Clinical fractures occurred in 198 of 2046 patients (9.7%) in the romosozumab-to-alendronate group versus 266 of 2047 patients (13.0%) in the alendronate-to-alendronate group, representing a 27% lower risk with romosozumab (P<0.001). The risk of nonvertebral fractures was lower by 19% in the romosozumab-to-alendronate group than in the alendronate-to-alendronate group (178 of 2046 patients [8.7%] vs. 217 of 2047 patients [10.6%]; P=0.04), and the risk of hip fracture was lower by 38% (41 of 2046 patients [2.0%] vs. 66 of 2047 patients [3.2%]; P=0.02). Overall adverse events and serious adverse events were balanced between the two groups. During year 1, positively adjudicated serious cardiovascular adverse events were observed more often with romosozumab than with alendronate (50 of 2040 patients [2.5%] vs. 38 of 2014 patients [1.9%]). During the open-label alendronate period, adjudicated events of osteonecrosis of the jaw (1 event each in the romosozumab-to-alendronate and alendronate-to-alendronate groups) and atypical femoral fracture (2 events and 4 events, respectively) were observed. Conclusions In postmenopausal women with osteoporosis who were at high risk for fracture, romosozumab treatment for 12 months followed by alendronate resulted in a significantly lower risk of fracture than alendronate alone.

Saag KG, Petersen J, Brandi ML, Karaplis AC, Lorentzon M, Thomas T, Maddox J, Fan M, Meisner PD, Grauer A.

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20Oct 2017
MPubmed

J Bone Miner Res. 2017 Sep;32(9):1907-1914. doi: 10.1002/jbmr.3177. Epub 2017 Jul 7.

The objective was to study the effect of parathyroidectomy (PTX) compared with observation (OBS) on bone mineral density (BMD) in g/cm2 and T-scores and on biochemical markers of bone turnover (P1NP and CTX-1) in a prospective randomized controlled study of patients with mild PHPT after 5 years of follow-up. Of 191 patients with mild PHPT randomized to either PTX or OBS, 145 patients remained for analysis after 5 years (110 with validated DXA scans).

A significant decrease in P1NP (p < 0.001) and CTX-1 (p < 0.001) was found in the PTX group only. A significant positive treatment effect of surgery compared with observation on BMD (g/cm2 ) was found for the lumbar spine (LS) (p = 0.011), the femoral neck (FN) (p < 0.001), the ultradistal radius (UDR) (p = 0.042), and for the total body (TB) (p < 0.001) but not for the radius 33% (Rad33), where BMD decreased significantly also in the PTX group (p = 0.012).

However, compared with baseline values, there was no significant BMD increase in the PTX group, except for the lumbar spine. In the OBS group, there was a significant decrease in BMD (g/cm2 ) for all compartments (FN, p < 0.001; Rad33, p = 0.001; UDR, p = 0.006; TB, p < 0.001) with the exception of the LS, where BMD was stable. In conclusion, parathyroidectomy improves BMD and observation leads to a small but statistically significant decrease in BMD after 5 years.

Lundstam K, Heck A, Godang K, Mollerup C, Baranowski M, Pernow Y, Aas T, Hessman O, Rosén T, Nordenström J, Jansson S, Hellström M, Bollerslev J; SIPH Study Group.

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