Abstract Background Eldecalcitol is an analog of 1,25-dihydroxyvitamin D3 that improves bone mineral density; however, the effect of eldecalcitol on the risk of fractures is unclear. The objective of ...this study is to examine whether eldecalcitol is superior to alfacalcidol in preventing osteoporotic fractures. This trial is registered with ClinicalTrials.gov, number NCT00144456. Methods and results This 3 year randomized, double-blind, active comparator, superiority trial tested the efficacy of daily oral 0.75 μg eldecalcitol versus 1.0 μg alfacalcidol for prevention of osteoporotic fractures. 1054 osteoporotic patients 46 to 92 years old were randomly assigned 1:1 to receive eldecalcitol (n = 528) or alfacalcidol (n = 526). Patients were stratified by study site and serum 25-hydroxyvitamin D level. Patients with low serum 25-hydroxyvitamin D levels (< 50 nmol/L) were supplemented with 400 IU/day vitamin D3 . Primary end point was incident vertebral fractures. Secondary end points included any non-vertebral fractures and change in bone mineral density and bone turnover markers. Compared with the alfacalcidol group, the incidence of vertebral fractures was lower in eldecalcitol group after 36 months of treatment (13.4 vs. 17.5%; hazard ratio, 0.74; predefined 90% confidence interval CI, 0.56–0.97). Eldecalcitol reduced turnover markers and increased bone mineral density more strongly than alfacalcidol. Eldecalcitol reduced the incidence of three major non-vertebral fractures, which was due to a marked reduction in wrist fractures by a post-hoc analysis (1.1 vs. 3.6%; hazard ratio, 0.29; 95% CI, 0.11–0.77). Among the adverse events, the incidence of increase in serum and urinary calcium was higher in the eldecalcitol group, without any difference in glomerular filtration rate between the two groups. Conclusions Eldecalcitol is more efficacious than alfacalcidol in preventing vertebral and wrist fractures in osteoporotic patients with vitamin D sufficiency, with a safety profile similar to alfacalcidol.
Reduced mechanical stress is a major cause of osteoporosis in the elderly, and the osteocyte network, which comprises a communication system through processes and canaliculi throughout bone, is ...thought to be a mechanosensor and mechanotransduction system; however, the functions of osteocytes are still controversial and remain to be clarified. Unexpectedly, we found that overexpression of BCL2 in osteoblasts eventually caused osteocyte apoptosis. Osteoblast and osteoclast differentiation were unaffected by BCL2 transgene in vitro. However, the cortical bone mass increased due to enhanced osteoblast function and suppressed osteoclastogenesis at 4 months of age, when the frequency of TUNEL-positive lacunae reached 75%. In the unloaded condition, the trabecular bone mass decreased in both wild-type and BCL2 transgenic mice at 6 weeks of age, while it decreased due to impaired osteoblast function and enhanced osteoclastogenesis in wild-type mice but not in BCL2 transgenic mice at 4 months of age. Rankl and Opg were highly expressed in osteocytes, but Rankl expression in osteoblasts but not in osteocytes was increased at unloading in wild-type mice but not in BCL2 transgenic mice at 4 months of age. Sost was locally induced at unloading in wild-type mice but not in BCL2 transgenic mice, and the dissemination of Sost was severely interrupted in BCL2 transgenic mice, showing the severely impaired osteocyte network. These findings indicate that the osteocyte network is required for the upregulation of Rankl in osteoblasts and Sost in osteocytes in the unloaded condition. These findings suggest that the osteocyte network negatively regulate bone mass by inhibiting osteoblast function and activating osteoclastogenesis, and these functions are augmented in the unloaded condition at least partly through the upregulation of Rankl expression in osteoblasts and that of Sost in osteocytes, although it cannot be excluded that low BCL2 transgene expression in osteoblasts contributed to the enhanced osteoblast function.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To investigate the role of calcium/calmodulin-dependent protein kinase IV (CaMK4) in the development of joint injury in a mouse model of arthritis and patients with RA.
Camk4-deficient, ...Camk4flox/floxLck-Cre, and mice treated with CaMK4 inhibitor KN-93 or KN-93 encapsulated in nanoparticles tagged with CD4 or CD8 antibodies were subjected to collagen-induced arthritis (CIA). Inflammatory cytokine levels, humoral immune response, synovitis, and T-cell activation were recorded. CAMK4 gene expression was measured in CD4+ T cells from healthy participants and patients with active RA. Micro-CT and histology were used to assess joint pathology. CD4+ and CD14+ cells in patients with RA were subjected to Th17 or osteoclast differentiation, respectively.
CaMK4-deficient mice subjected to CIA displayed improved clinical scores and decreased numbers of Th17 cells. KN-93 treatment significantly reduced joint destruction by decreasing the production of inflammatory cytokines. Furthermore, Camk4flox/floxLck-Cre mice and mice treated with KN93-loaded CD4 antibody-tagged nanoparticles developed fewer Th17 cells and less severe arthritis. CaMK4 inhibition mitigated IL-17 production by CD4+ cells in patients with RA. The number of in vitro differentiated osteoclasts from CD14+ cells in patients with RA was significantly decreased with CaMK4 inhibitors.
Using global and CD4-cell-targeted pharmacologic approaches and conditionally deficient mice, we demonstrate that CaMK4 is important in the development of arthritis. Using ex vivo cell cultures from patients with RA, CaMK4 is important for both Th17 generation and osteoclastogenesis. We propose that CaMK4 inhibition represents a new approach to control the development of arthritis.
Src knockout (KO) and RANKL KO mice both exhibit near complete osteopetrosis in terms of 3D-bone volume (BV) fraction by micro-CT, whereas the serum CTX concentration of Src KO is apparently normal ...and that of RANKL KO is 30% of wild-type (WT) despite the fact that they lack osteoclasts. By histomorphometry we found that, whereas eroded surface (ES) and osteoid surface (OS) are zero values in RANKL KO, they are indistinguishable from WT in Src KO; because of marked increase in bone surface (BS), ES/BS and OS/BS of Src KO are 30–40% of WT. While RANKL KO lack both osteoclasts and osteoblasts, Src KO reveal increased numbers of osteoclasts and indistinguishable numbers of osteoblasts compared with WT; again, on the basis of BS, N.Oc/BS is comparable to WT and N.Ob/BS is markedly decreased in Src KO. The apparently increased number of total osteoclasts may be due to increased expression of RANKL found in Src KO bone in vivo. Src has a gene dosage-dependent effect on osteoclast function in vitro, with Src
−/−
osteoclasts completely lacking bone-resorbing function as determined by CTX release on dentin. Thus, Src KO osteoclasts retain some bone-resorbing function in vivo. The number of osteocytes is proportionally increased in RANKL KO, while Src KO mice have relative osteocyte deficiency, raising the possibility that RANKL and Src has an unrecognized role in osteocyte survival.
Chemokines have recently been reported to be involved in pathological bone destruction. However, the physiological roles of chemokines in bone metabolism in vivo have not been well documented. We ...analyzed the bone phenotypes in Cx3cr1-deficient mice. The mice exhibited slight but significant increases in trabecular and cortical thickness, reduced numbers of osteoclasts and increased rates of osteoid formation. Although the morphometric parameters showed marginal differences, the Cx3cr1-deficient bones showed an elevated expression of Osterix/SP7, which encodes an essential transcriptional factor for osteoblasts, whereas the gene Osteocalcin/Bglap, which encodes a late marker, was downregulated. The levels of transcripts for various osteoclastic markers, such as receptor activator of NF-κB (RANK)/TNFRSF11A, receptor activator of NF-κB ligand (RANKL)/TNFSF11, tartrate-resistant acid phosphatase 5b (TRAP5B)/ACP5B, Cathepsin K(CTSK), MMP3 and MMP13, were significantly decreased in the Cx3cr1-deficient bones. Cultured Cx3cr1-deficient osteoblastic cells showed inverse temporal patterns of osteoblastic marker expression and reduced calcium deposition. Furthermore, in vitro studies and immunofluorescence staining against CX3CR1 and CX3CL1 suggested a role for the CX3CR1-CX3CL1 axis in an early stage of osteoblast differentiation, possibly through their trans and cis interactions. Cultured Cx3cr1-deficient pre-osteoclasts showed impaired differentiation, mainly due to a deficiency of the CD115(+)CD11b(lo) osteoclastogenic population of myeloid-lineage precursors. The treatment of bone-marrow-derived osteoclastic cultures with recombinant CX3CL1 at different time points suggested that the CX3CR1-CX3CL1 axis favors the maintenance of osteoclastic precursors, but not differentiated osteoclasts. These observations uncovered novel roles of the CX3CR1-CX3CL1 axis in the differentiation of both osteoblasts and osteoclasts.
Introduction
This study compared the clinical usefulness of minodronate (50 mg/4 weeks) plus alfacalcidol (1 μg/day) (Group M) with that of alfacalcidol alone (1 μg/day) (Group A) for treating ...glucocorticoid-induced osteoporosis.
Materials and methods
The primary endpoints were the changes from baseline in lumbar spine (LS) bone mineral density (BMD) and the cumulative incidence of vertebral fracture at 24 months; secondary endpoints included the changes from baseline in total hip (TH) BMD and bone turnover markers.
Results
Of 164 patients enrolled, 152 (Group M,
n
= 75; Group A,
n
= 77) were included in the analysis of efficacy. At each time point and at 24 months, LS BMD and TH BMD were significantly higher in Group M than in Group A. The 152 patients were divided into two subgroups that were previously treated with glucocorticoids for ≤ 3 months or > 3 months. In both subgroups, the changes from baseline in LS BMD and TH BMD from baseline at 24 months had increased more in Group M than in Group A. There were no differences found in the incidence of vertebral fracture between the groups, because the number of enrolled patients was lesser than that initially expected. In Group M, both bone formation and resorption markers significantly decreased from baseline at 3 months and maintained at 6, 12, and 24 months.
Conclusions
Minodronate plus alfacalcidol was more effective than alfacalcidol alone in increasing BMD and was effective in increasing BMD for both prevention and treatment. Therefore, minodronate can be a good candidate drug for the treatment of glucocorticoid-induced osteoporosis.
Hypertension and osteoporosis are two major age‐related disorders; however, the underlying molecular mechanism for this comorbidity is not known. The renin‐angiotensin system (RAS) plays a central ...role in the control of blood pressure and has been an important target of antihypertensive drugs. Using a chimeric RAS model of transgenic THM (Tsukuba hypertensive mouse) expressing both the human renin and human angiotensinogen genes, we showed in this study that activation of RAS induces high turnover osteoporosis with accelerated bone resorption. Transgenic mice that express only the human renin gene were normotensive and yet exhibited a low bone mass, suggesting that osteoporosis occurs independently of the development of hypertension per se. Ex vivo cultures showed that angiotensin II (AngII) acted on osteoblasts and not directly on osteoclast precursor cells and increased osteoclastogenesis‐supporting cytokines, RANKL and vascular endothelial growth factor (VEGF), thereby stimulating the formation of osteoclasts. Knockdown of AT2 receptor inhibited the AngII activity, whereas silencing of the AT1 receptor paradoxically enhanced it, suggesting a functional interaction between the two AngII receptors on the osteoblastic cell surface. Finally, treatment of THM mice with an ACE inhibitor, enalapril, improved osteoporosis and hypertension, whereas treatment with losartan, an angiotensin receptor blockers specific for AT1, resulted in exacerbation of the low bone mass phenotype. Thus, blocking the synthesis of AngII may be an effective treatment of osteoporosis and hypertension, especially for those afflicted with both conditions.
The International Society for Clinical Densitometry (ISCD) has developed Official Positions for the clinical use of dual-energy X-ray absorptiometry (DXA) and non-DXA technologies. While only DXA can ...be used for diagnostic classification according to criteria established by the World Health Organization, DXA and some other technologies may predict fracture risk and be used to monitor skeletal changes over time. ISCD task forces reviewed the evidence for clinical applications of non-DXA techniques and presented reports with recommendations at the 2007 ISCD Position Development Conference. Here we present the ISCD Official Positions for quantitative computed tomography (QCT) and peripheral QCT (pQCT), with supporting medical evidence, rationale, controversy, and suggestions for further study. QCT is available for bone mineral density measurements at the spine, hip, forearm, and tibia. The ISCD Official Positions presented here focus on QCT of the spine and pQCT of the forearm. Measurements at the hip may have clinical relevance, as this is an important fracture site; however, due to limited medical evidence, definitive advice on its use in clinical practice cannot be provided until more data emerge.
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