1. |
- Lionikaite, Vikte, et al.
(author)
-
Clinically relevant doses of Vitamin A decrease cortical bone mass in mice
- 2018
-
In: Journal of Endocrinology. - 0022-0795 .- 1479-6805. ; 239:3, s. 389-402
-
Journal article (peer-reviewed)abstract
- Excess vitamin A has been associated with decreased cortical bone thickness and increased fracture risk. While most studies in rodents have employed high dosages of vitamin A for short periods of time, we investigated the bone phenotype in mice after longer exposure to more clinically relevant doses. For 1, 4 and 10 weeks, mice were fed a control diet (4.5µg retinyl acetate/g chow), a diet modeled from the human upper tolerable limit (UTL; 20µg retinyl acetate/g chow) and a diet three times UTL (supplemented; 60µg retinyl acetate/g chow). Time-dependent decreases in periosteal circumference and bone mineral content were noted with the supplemented dose. These reductions in cortical bone resulted in a significant time-dependent decrease of predicted strength and a non-significant trend toward reduced bone strength as analyzed by three-point bending. Trabecular bone in tibiae and vertebrae remained unaffected when vitamin A was increased in the diet. Dynamic histomorphometry demonstrated that bone formation was substantially decreased after 1 week of treatment at the periosteal site with the supplemental dose. Increasing amount of vitamin A decreased endocortical circumference, resulting in decreased marrow area, a response associated with enhanced endocortical bone formation. In the presence of bisphosphonate, vitamin A had no effect on cortical bone, suggesting that osteoclasts are important, even if effects on bone resorption were not detected by osteoclast counting, genes in cortical bone or analysis of serum TRAP5b and CTX. In conclusion, our results indicate that even clinically relevant doses of vitamin A have a negative impact on the amount of cortical bone. © 2018 The authors Published by Bioscientifica Ltd.
|
|
2. |
- Conaway, H. H., et al.
(author)
-
Activation of dimeric glucocorticoid receptors in osteoclast progenitors potentiates RANKL induced mature osteoclast bone resorbing activity
- 2016
-
In: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 93, s. 43-54
-
Journal article (peer-reviewed)abstract
- Glucocorticoid (GC) therapy is the greatest risk factor for secondary osteoporosis. Pathogenic mechanisms involve an initial increase in bone resorption followed by decreased bone formation. To gain a better understanding of the resorptive activity of GCs, we have used mouse bone marrow macrophages (BMM) to determine if GCs can directly modulate RANKL stimulated osteoclast formation and/or activity. In agreement with previous studies, experiments performed in plastic wells showed that GCs (dexamethasone, hydrocortisone, and prednisolone) inhibited osteoclast number and size during the initial phases of RANKL stimulated osteoclastogenesis; however, in prolonged cultures, decreased apoptosis was observed and escape from GC induced inhibition occurred with an enhanced number of osteoclasts formed, many with an increased area. When BMM cells were seeded on bone slices, GCs robustly enhanced RANKL stimulated formation of resorption pits and release of CTX without affecting the number or size of osteoclasts formed and with no effect on apoptosis. Stimulation of pit formation was not associated with increased life span of osteoclasts or an effect on mRNA expression of several osteoclastic or osteoclastogenic genes. The potentiation of RANKL induced CTX release by dexamethasone was significantly less in BMM cells from mice with conditional knockout of the osteoclastic glucocorticoid receptor and completely absent in cells from GRdim mice, which carry a point mutation in one dimerizing interface of the GC receptor. These data suggest that: 1. Plastic is a poor medium to use for studying direct effects of GCs on osteoclasts 2. GCs can enhance bone resorption without decreasing apoptosis, and 3. A direct enhancement of RANKL mediated resorption is stimulated by the dimeric GC-receptor. © 2016 Elsevier Inc.
|
|
3. |
|
|
4. |
- Henning, Petra, 1974, et al.
(author)
-
Retinoid receptors in bone and their role in bone remodeling
- 2015
-
In: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 6
-
Journal article (peer-reviewed)abstract
- Vitamin A (retinol) is a necessary and important constituent of the body which is provided by food intake of retinyl esters and carotenoids. Vitamin A is known best for being important for vision, but in addition to the eye, vitamin A is necessary in numerous other organs in the body, including the skeleton. Vitamin A is converted to an active compound, all-trans-retinoic acid (ATRA), which is responsible for most of its biological actions. ATRA binds to intracellular nuclear receptors called retinoic acid receptors (RARα, RARβ, RARγ). RARs and closely related retinoid X receptors (RXRα, RXRβ, RXRγ) form heterodimers which bind to DNA and function as ligand-activated transcription factors. It has been known for many years that hypervitaminosis A promotes skeleton fragility by increasing osteoclast formation and decreasing cortical bone mass. Some epidemiological studies have suggested that increased intake of vitamin A and increased serum levels of retinoids may decrease bone mineral density and increase fracture rate, but the literature on this is not conclusive. The current review summarizes how vitamin A is taken up by the intestine, metabolized, stored in the liver, and processed to ATRA. ATRA's effects on formation and activity of osteoclasts and osteoblasts are outlined, and a summary of clinical data pertaining to vitamin A and bone is presented. © 2015 Henning, Conaway and Lerner.
|
|
5. |
|
|
6. |
- Lionikaite, Vikte, et al.
(author)
-
Effects of retinoids on physiologic and inflammatory osteoclastogenesis in vitro
- 2018
-
In: Journal of leukocyte biology. - 1938-3673. ; 104:6, s. 1133-1145
-
Journal article (peer-reviewed)abstract
- Increased intake of vitamin A (retinoids) is associated with decreased bone mass and increased fracture risk in humans. Mechanistic studies in rodents have shown that hypervitaminosis A results in decreased bone mass caused by an increase in periosteal osteoclasts while simultaneously decreasing endocortic osteoclasts. In vivo and ex vivo bone organ cultures have demonstrated that excess retinoids increase osteoclast formation due to increased receptor activator of nuclear factor kappa B-ligand (RANKL) expression. In vitro, studies using murine bone marrow macrophages (BMM) have shown that retinoids inhibit osteoclast formation induced by recombinant RANKL. These opposing in vivo/ex vivo versus in vitro effects may elucidate why excess retinoids affect periosteal and endocortic osteoclast formation differently. In addition, it has been reported that retinoids can inhibit osteoclast formation under inflammatory conditions such as experimentally induced arthritis in mice. In the present study, we have compared the effect of all-trans-retinoic acid (ATRA) on physiologically and inflammatory induced osteoclastogenesis. ATRA inhibited physiologically induced (RANKL) osteoclast formation of human peripheral blood monocytes and mouse BMM as well as human monocytes stimulated with the pro-inflammatory compounds, TNF-α and LPS. The inhibition was due to impeded differentiation, rather than fusion, of mononucleated progenitor cells. ATRA disrupted differentiation by interfering with osteoclastogenic intracellular signaling. In line with this view, overexpression of Tnfrsf11a (encodes for RANK) in BMM could not overcome the inhibition of osteoclastogenesis by ATRA. The data suggest that ATRA inhibits both physiologic and inflammatory osteoclast differentiation of progenitors from the bone marrow and peripheral blood. ©2018 Society for Leukocyte Biology.
|
|
7. |
- Moverare-Skrtic, Sofia, et al.
(author)
-
B4GALNT3 regulates glycosylation of sclerostin and bone mass
- 2023
-
In: eBioMedicine. - 2352-3964. ; 91
-
Journal article (peer-reviewed)abstract
- Background Global sclerostin inhibition reduces fracture risk efficiently but has been associated with cardiovascular side effects. The strongest genetic signal for circulating sclerostin is in the B4GALNT3 gene region, but the causal gene is unknown. B4GALNT3 expresses the enzyme beta-1,4-N-acetylgalactosaminyltransferase 3 that transfers N-acetylgalactosamine onto N-acetylglucosaminebeta-benzyl on protein epitopes (LDN-glycosylation). Methods To determine if B4GALNT3 is the causal gene, B4galnt3 / mice were developed and serum levels of total sclerostin and LDN-glycosylated sclerostin were analysed and mechanistic studies were performed in osteoblast-like cells. Mendelian randomization was used to determine causal associations. Findings B4galnt3 / mice had higher circulating sclerostin levels, establishing B4GALNT3 as a causal gene for circulating sclerostin levels, and lower bone mass. However, serum levels of LDN-glycosylated sclerostin were lower in B4galnt3 / mice. B4galnt3 and Sost were co-expressed in osteoblast-lineage cells. Overexpression of B4GALNT3 increased while silencing of B4GALNT3 decreased the levels of LDN-glycosylated sclerostin in osteoblast-like cells. Mendelian randomization demonstrated that higher circulating sclerostin levels, genetically predicted by variants in the B4GALNT3 gene, were causally associated with lower BMD and higher risk of fractures but not with higher risk of myocardial infarction or stroke. Glucocorticoid treatment reduced B4galnt3 expression in bone and increased circulating sclerostin levels and this may contribute to the observed glucocorticoid-induced bone loss. Interpretation B4GALNT3 is a key factor for bone physiology via regulation of LDN-glycosylation of sclerostin. We propose that B4GALNT3-mediated LDN-glycosylation of sclerostin may be a bone-specific osteoporosis target, separating the anti-fracture effect of global sclerostin inhibition, from indicated cardiovascular side effects. Funding Found in acknowledgements.
|
|
8. |
- Movérare-Skrtic, Sofia, et al.
(author)
-
Osteoblast-derived WNT16 represses osteoclastogenesis and prevents cortical bone fragility fractures.
- 2014
-
In: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 20:11, s. 1279-88
-
Journal article (peer-reviewed)abstract
- The WNT16 locus is a major determinant of cortical bone thickness and nonvertebral fracture risk in humans. The disability, mortality and costs caused by osteoporosis-induced nonvertebral fractures are enormous. We demonstrate here that Wnt16-deficient mice develop spontaneous fractures as a result of low cortical thickness and high cortical porosity. In contrast, trabecular bone volume is not altered in these mice. Mechanistic studies revealed that WNT16 is osteoblast derived and inhibits human and mouse osteoclastogenesis both directly by acting on osteoclast progenitors and indirectly by increasing expression of osteoprotegerin (Opg) in osteoblasts. The signaling pathway activated by WNT16 in osteoclast progenitors is noncanonical, whereas the pathway activated in osteoblasts is both canonical and noncanonical. Conditional Wnt16 inactivation revealed that osteoblast-lineage cells are the principal source of WNT16, and its targeted deletion in osteoblasts increases fracture susceptibility. Thus, osteoblast-derived WNT16 is a previously unreported key regulator of osteoclastogenesis and fracture susceptibility. These findings open new avenues for the specific prevention or treatment of nonvertebral fractures, a substantial unmet medical need.
|
|
9. |
- Nilsson, Karin H., et al.
(author)
-
RSPO3 is important for trabecular bone and fracture risk in mice and humans
- 2021
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
-
Journal article (peer-reviewed)abstract
- Genetic association signals for fractures have been reported at the RSPO3 locus, but the causal gene and the underlying mechanism are unknown. Here, the authors show that RSPO3 exerts an important role for vertebral trabecular bone mass and bone strength in mice and fracture risk in humans. With increasing age of the population, countries across the globe are facing a substantial increase in osteoporotic fractures. Genetic association signals for fractures have been reported at the RSPO3 locus, but the causal gene and the underlying mechanism are unknown. Here we show that the fracture reducing allele at the RSPO3 locus associate with increased RSPO3 expression both at the mRNA and protein levels, increased trabecular bone mineral density and reduced risk mainly of distal forearm fractures in humans. We also demonstrate that RSPO3 is expressed in osteoprogenitor cells and osteoblasts and that osteoblast-derived RSPO3 is the principal source of RSPO3 in bone and an important regulator of vertebral trabecular bone mass and bone strength in adult mice. Mechanistic studies revealed that RSPO3 in a cell-autonomous manner increases osteoblast proliferation and differentiation. In conclusion, RSPO3 regulates vertebral trabecular bone mass and bone strength in mice and fracture risk in humans.
|
|
10. |
- Persson, Emma, et al.
(author)
-
Activation of Shc1 allows oncostatin M to induce RANKL and osteoclast formation more effectively than leukemia inhibitory factor
- 2019
-
In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 10:MAY
-
Journal article (peer-reviewed)abstract
- Background and Purpose: The gp130 family of cytokines signals through receptors dimerizing with the gp130 subunit. Downstream signaling typically activates STAT3 but also SHP2/Ras/MAPK pathways. Oncostatin M (OSM) is a unique cytokine in this family since the receptor (OSMR) activates a non-redundant signaling pathway by recruitment of the adapter Shc1. We have studied the functional relevance of Shc1 for OSM-induced bone resorption. Experimental Approach: Osteoblasts were stimulated with OSM and STAT3 and Shc1 activations were studied using real-time PCR and Western blots. The role of STAT3 and Shc1 for OSM-induced RANKL expression and osteoclast formation was studied by silencing their mRNA expressions. Effects of OSM were compared to those of the closely related cytokine leukemia inhibitory factor (LIF). Key Results: OSM, but not LIF, induced the mRNA and protein expression of Shc1 and activated phosphorylation of Shc1 in the osteoblasts. Silencing of Shc1 decreased OSM-induced activation of STAT3 and RANKL expression. Silencing of STAT3 had no effect on activation of Shc1, but prevented the OSM-mediated increase of RANKL expression. Silencing of either Shc1 or STAT3 in osteoblasts decreased formation of osteoclasts in OSM-stimulated co-cultures of osteoblasts and macrophages. In agreement with these observations, OSM was a more potent and robust stimulator than LIF of RANKL formation and bone resorption in mouse calvariae and osteoclast formation in bone marrow cultures. Conclusions and Implications: Activation of the Shc1-dependent STAT3 signaling is crucial for OSM-induced osteoclast formation. Inhibition of Shc1 is a potential mechanism to specifically inhibit OSM-induced bone resorption. © 2019 Persson, Souza, Floriano-Marcelino, Conaway, Henning and Lerner. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
|
|
11. |
- Schwab, A M, et al.
(author)
-
Stimulation of resorption in cultured mouse calvarial bones by thiazolidinediones.
- 2005
-
In: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 146:10, s. 4349-61
-
Journal article (peer-reviewed)abstract
- Dosage-dependent release of 45Ca was observed from prelabeled mouse calvarial bones after treatment with two thiazolidinediones, troglitazone and ciglitazone. Release of 45Ca by ciglitazone was decreased by the osteoclast inhibitors acetazolamide, calcitonin, 3-amino-1-hydroxypropylidene-1,1-bisphosphonate, and IL-4, but not affected by the peroxisome proliferator-activated receptor gamma antagonist, GW 9662, the mitotic inhibitor, hydroxyurea, or indomethacin. Enhanced expression of receptor activator of nuclear factor-kappaB ligand (RANKL) mRNA and protein and decreased osteoprotegerin (OPG) mRNA and protein were noted after ciglitazone treatment of calvariae. Ciglitazone and RANKL each caused increased mRNA expression of osteoclast markers: calcitonin receptor, tartrate-resistant acid phosphatase, cathepsin K, matrix metalloproteinase-9, integrin beta3, and nuclear factor of activated T cells 2. OPG inhibited mRNA expression of RANKL stimulated by ciglitazone, mRNA expression of osteoclast markers stimulated by ciglitazone and RANKL, and 45Ca release stimulated by troglitazone and ciglitazone. Increased expression of IL-1alpha mRNA by ciglitazone was not linked to resorption stimulated by the thiazolidinedione. Ciglitazone did not increase adipogenic gene expression but enhanced osteocalcin mRNA in calvariae. In addition to exhibiting sensitivity to OPG, data indicate that stimulation of osteoclast differentiation and activity by thiazolidinediones may occur by a nonperoxisome proliferator-activated receptor gamma-dependent pathway that does not require cell proliferation, prostaglandins, or IL-1alpha but is characterized by an increased RANKL to OPG ratio.
|
|
12. |
- Zheng, J., et al.
(author)
-
Mendelian Randomization Analysis Reveals a Causal Influence of Circulating Sclerostin Levels on Bone Mineral Density and Fractures
- 2019
-
In: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 34:10, s. 1824-1836
-
Journal article (peer-reviewed)abstract
- In bone, sclerostin is mainly osteocyte-derived and plays an important local role in adaptive responses to mechanical loading. Whether circulating levels of sclerostin also play a functional role is currently unclear, which we aimed to examine by two-sample Mendelian randomization (MR). A genetic instrument for circulating sclerostin, derived from a genomewide association study (GWAS) meta-analysis of serum sclerostin in 10,584 European-descent individuals, was examined in relation to femoral neck bone mineral density (BMD; n = 32,744) in GEFOS and estimated bone mineral density (eBMD) by heel ultrasound (n = 426,824) and fracture risk (n = 426,795) in UK Biobank. Our GWAS identified two novel serum sclerostin loci, B4GALNT3 (standard deviation [SD]) change in sclerostin per A allele (beta = 0.20, p = 4.6 x 10(-49)) and GALNT1 (beta = 0.11 per G allele, p = 4.4 x 10(-11)). B4GALNT3 is an N-acetyl-galactosaminyltransferase, adding a terminal LacdiNAc disaccharide to target glycocoproteins, found to be predominantly expressed in kidney, whereas GALNT1 is an enzyme causing mucin-type O-linked glycosylation. Using these two single-nucleotide polymorphisms (SNPs) as genetic instruments, MR revealed an inverse causal relationship between serum sclerostin and femoral neck BMD (beta = -0.12, 95% confidence interval [CI] -0.20 to -0.05) and eBMD (beta = -0.12, 95% CI -0.14 to -0.10), and a positive relationship with fracture risk (beta = 0.11, 95% CI 0.01 to 0.21). Colocalization analysis demonstrated common genetic signals within the B4GALNT3 locus for higher sclerostin, lower eBMD, and greater B4GALNT3 expression in arterial tissue (probability >99%). Our findings suggest that higher sclerostin levels are causally related to lower BMD and greater fracture risk. Hence, strategies for reducing circulating sclerostin, for example by targeting glycosylation enzymes as suggested by our GWAS results, may prove valuable in treating osteoporosis. (c) 2019 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc.
|
|
13. |
- Brand, H S, et al.
(author)
-
Family 2 cystatins inhibit osteoclast-mediated bone resorption in calvarial bone explants.
- 2004
-
In: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 35:3, s. 689-96
-
Journal article (peer-reviewed)abstract
- Osteoclastic bone resorption depends on the activity of various proteolytic enzymes, in particular those belonging to the group of cysteine proteinases. Biochemical studies have shown that cystatins, naturally occurring inhibitors of these enzymes, inhibit bone matrix degradation. Since the mechanism by which cystatins exert this inhibitory effect is not completely resolved yet, we studied the effect of cystatins on bone resorption microscopically and by Ca-release measurements. Calvarial bone explants were cultured in the presence or absence of family 2 cystatins and processed for light and electron microscopic analysis, and the culture media were analyzed for calcium release. Both egg white cystatin and human cystatin C decreased calcium release into the medium significantly. Microscopic analyses of the bone explants demonstrated that in the presence of either inhibitor, a high percentage of osteoclasts was associated with demineralized non-degraded bone matrix. Following a 24-h incubation in the presence of cystatin C, 41% of the cells were adjacent to areas of demineralized non-degraded bone matrix, whereas in controls, this was only 6%. If bone explants were cultured with both PTH and cystatin C, 60% of the osteoclasts were associated with demineralized non-degraded bone matrix, compared to 27% for bones treated with PTH only (P < 0.01). Our study provides evidence that cystatins, the naturally occurring inhibitors of cysteine proteinases, reversibly inhibit bone matrix degradation in the resorption lacunae adjacent to osteoclasts. These findings suggest the involvement of cystatins in the modulation of osteoclastic bone degradation.
|
|
14. |
- Brommage, Robert, et al.
(author)
-
NOTUM inhibition increases endocortical bone formation and bone strength
- 2019
-
In: Bone Research. - : Springer Science and Business Media LLC. - 2095-4700 .- 2095-6231. ; 7:2
-
Journal article (peer-reviewed)abstract
- The disability, mortality and costs caused by non-vertebral osteoporotic fractures are enormous. Existing osteoporosis therapies are highly effective at reducing vertebral but not non-vertebral fractures. Cortical bone is a major determinant of non-vertebral bone strength. To identify novel osteoporosis drug targets, we phenotyped cortical bone of 3 366 viable mouse strains with global knockouts of druggable genes. Cortical bone thickness was substantially elevated in Notum(-/-) mice. NOTUM is a secreted WNT lipase and we observed high NOTUM expression in cortical bone and osteoblasts but not osteoclasts. Three orally active small molecules and a neutralizing antibody inhibiting NOTUM lipase activity were developed. They increased cortical bone thickness and strength at multiple skeletal sites in both gonadal intact and ovariectomized rodents by stimulating endocortical bone formation. Thus, inhibition of NOTUM activity is a potential novel anabolic therapy for strengthening cortical bone and preventing non-vertebral fractures.
|
|
15. |
- Conaway, H. Herschel, et al.
(author)
-
Glucocorticoids employ the monomeric glucocorticoid receptor to potentiate vitamin D3 and parathyroid hormone–induced osteoclastogenesis
- 2019
-
In: The FASEB Journal. - : Federation Amer Soc Exp Biol. - 0892-6638 .- 1530-6860. ; 33:12, s. 14394-14409
-
Journal article (peer-reviewed)abstract
- Glucocorticoid (GC) therapy decreases bone mass and increases the risk of fractures. We investigated interactions between the GC dexamethasone (DEX) and the bone resorptive agents 1,25(OH)2-vitamin D3 (D3) and parathyroid hormone (PTH) on osteoclastogenesis. We observed a synergistic potentiation of osteoclast progenitor cell differentiation and formation of osteoclasts when DEX was added to either D3- or PTH-treated mouse bone marrow cell (BMC) cultures. Cotreatment of DEX with D3 or PTH increased gene encoding calcitonin receptor (Calcr), acid phosphatase 5, tartrate resistant (Acp5), cathepsin K (Ctsk), and TNF superfamily member 11 (Tnfsf11) mRNA, receptor activator of NF-κB ligand protein (RANKL), numbers of osteoclasts on plastic, and pit formation and release of C-terminal fragment of type I collagen from cells cultured on bone slices. Enhanced RANKL protein expression caused by D3 and DEX was absent in BMC from mice in which the GC receptor (GR) was deleted in stromal cells/osteoblasts. Synergistic interactions between DEX and D3 on RANKL and osteoclast formation were present in BMC from mice with attenuated GR dimerization. These data demonstrate that the GR cooperates with D3 and PTH signaling, causing massive osteoclastogenesis, which may explain the rapid bone loss observed with high dosages of GC treatment.
|
|
16. |
- Conaway, H Herschel, et al.
(author)
-
Retinoids and bone
- 2011
-
In: Contemporary aspects of endocrinology. - : InTech. - 9789533073576 ; , s. 443-454
-
Book chapter (other academic/artistic)
|
|
17. |
- Conaway, H Herschel, et al.
(author)
-
Retinoids inhibit differentiation of hematopoietic osteoclast progenitors.
- 2009
-
In: The FASEB journal. - Bethesda, Md. : Wiley. - 1530-6860 .- 0892-6638. ; 23:10, s. 3526-38
-
Journal article (peer-reviewed)abstract
- Whether vitamin A promotes skeletal fragility, has no effect on fracture rate, or protects against bone loss is unclear. In the present study, effects of retinoids on osteoclast differentiation in cultured mouse bone marrow cells (BMCs), bone marrow macrophages (BMMs), spleen cells, and RAW264.7 cells were evaluated by analyzing osteoclast formation and expression of genes important in signal transduction and osteoclast function. All-trans-retinoic acid (ATRA) did not stimulate osteoclastogenesis in BMCs, but inhibited hormone and RANKL-induced gene expression and formation of osteoclasts. In BMMs, spleen cells, and RAW264.7 cells, osteoclast differentiation and formation stimulated by M-CSF/RANKL were inhibited (IC(50) = 0.3 nM) by ATRA. The effect was exerted at an early step of RANKL-induced differentiation. ATRA also abolished increases of the transcription factors c-Fos and NFAT2 stimulated by RANKL and suppressed down-regulation of the antiosteoclastogenic transcription factor MafB. By comparing effects of several compounds structurally related to ATRA, as well as by using receptor antagonists, evaluation pointed to inhibition being mediated by RARalpha, with no involvement of PPARbeta/delta. The results suggest that activation of RARalpha by retinoids in myeloid hematopoietic precursor cells decreases osteoclast formation by altering expression of the transcription factors c-Fos, NFAT2, and MafB.
|
|
18. |
- Conaway, H Herschel, et al.
(author)
-
Retinoids stimulate periosteal bone resorption by enhancing the protein RANKL, a response inhibited by monomeric glucocorticoid receptor.
- 2011
-
In: The Journal of biological chemistry. - 1083-351X .- 0021-9258. ; 286:36, s. 31425-36
-
Journal article (peer-reviewed)abstract
- Increased vitamin A (retinol) intake has been suggested to increase bone fragility. In the present study, we investigated effects of retinoids on bone resorption in cultured neonatal mouse calvarial bones and their interaction with glucocorticoids (GC). All-trans-retinoic acid (ATRA), retinol, retinalaldehyde, and 9-cis-retinoic acid stimulated release of (45)Ca from calvarial bones. The resorptive effect of ATRA was characterized by mRNA expression of genes associated with osteoclast differentiation, enhanced osteoclast number, and bone matrix degradation. In addition, the RANKL/OPG ratio was increased by ATRA, release of (45)Ca stimulated by ATRA was blocked by exogenous OPG, and mRNA expression of genes associated with bone formation was decreased by ATRA. All retinoid acid receptors (RARα/β/γ) were expressed in calvarial bones. Agonists with affinity to all receptor subtypes or specifically to RARα enhanced the release of (45)Ca and mRNA expression of Rankl, whereas agonists with affinity to RARβ/γ or RARγ had no effects. Stimulation of Rankl mRNA by ATRA was competitively inhibited by the RARα antagonist GR110. Exposure of calvarial bones to GC inhibited the stimulatory effects of ATRA on (45)Ca release and Rankl mRNA and protein expression. This inhibitory effect was reversed by the glucocorticoid receptor (GR) antagonist RU 486. Increased Rankl mRNA stimulated by ATRA was also blocked by GC in calvarial bones from mice with a GR mutation that blocks dimerization (GR(dim) mice). The data suggest that ATRA enhances periosteal bone resorption by increasing the RANKL/OPG ratio via RARα receptors, a response that can be inhibited by monomeric GR.
|
|
19. |
- Conaway, H Herschel, et al.
(author)
-
Vitamin a metabolism, action, and role in skeletal homeostasis.
- 2013
-
In: Endocrine reviews. - : The Endocrine Society. - 1945-7189 .- 0163-769X. ; 34:6, s. 766-97
-
Journal article (peer-reviewed)abstract
- Vitamin A (retinol) is ingested as either retinyl esters or carotenoids and metabolized to active compounds such as 11-cis-retinal, which is important for vision, and all-trans-retinoic acid, which is the primary mediator of biological actions of vitamin A. All-trans-retinoic acid binds to retinoic acid receptors (RARs), which heterodimerize with retinoid X receptors. RAR-retinoid X receptor heterodimers function as transcription factors, binding RAR-responsive elements in promoters of different genes. Numerous cellular functions, including bone cell functions, are mediated by vitamin A; however, it has long been recognized that increased levels of vitamin A can have deleterious effects on bone, resulting in increased skeletal fragility. Bone mass is dependent on the balance between bone resorption and bone formation. A decrease in bone mass may be caused by either an excess of resorption or decreased bone formation. Early studies indicated that the primary skeletal effect of vitamin A was to increase bone resorption, but later studies have shown that vitamin A can not only stimulate the formation of bone-resorbing osteoclasts but also inhibit their formation. Effects of vitamin A on bone formation have not been studied in as great a detail and are not as well characterized as effects on bone resorption. Several epidemiological studies have shown an association between vitamin A, decreased bone mass, and osteoporotic fractures, but the data are not conclusive because other studies have found no associations, and some studies have suggested that vitamin A primarily promotes skeletal health. In this presentation, we have summarized how vitamin A is absorbed and metabolized and how it functions intracellularly. Vitamin A deficiency and excess are introduced, and detailed descriptions of clinical and preclinical studies of the effects of vitamin A on the skeleton are presented.
|
|
20. |
- Funck-Brentano, Thomas, et al.
(author)
-
Porcupine inhibitors impair trabecular and cortical bone mass and strength in mice
- 2018
-
In: Journal of Endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 238:1, s. 13-23
-
Journal article (peer-reviewed)abstract
- WNT signaling is involved in the tumorigenesis of various cancers and regulates bone homeostasis. Palmitoleoylation of WNTs by Porcupine is required for WNT activity. Porcupine inhibitors are under development for cancer therapy. As the possible side effects of Porcupine inhibitors on bone health are unknown, we determined their effects on bone mass and strength. Twelve-week-old C57BL/6N female mice were treated by the Porcupine inhibitors LGK974 (low dose = 3 mg/kg/day; high dose = 6 mg/kg/day) or Wnt-C59 (10 mg/kg/day) or vehicle for 3 weeks. Bone parameters were assessed by serum biomarkers, dual-energy X-ray absorptiometry, mu CT and histomorphometry. Bone strength was measured by the 3-point bending test. The Porcupine inhibitors were well tolerated demonstrated by normal body weight. Both doses of LGK974 and Wnt-C59 reduced total body bone mineral density compared with vehicle treatment (P < 0.001). Cortical thickness of the femur shaft (P < 0.001) and trabecular bone volume fraction in the vertebral body (P < 0.001) were reduced by treatment with LGK974 or Wnt-C59. Porcupine inhibition reduced bone strength in the tibia (P < 0.05). The cortical bone loss was the result of impaired periosteal bone formation and increased endocortical bone resorption and the trabecular bone loss was caused by reduced trabecular bone formation and increased bone resorption. Porcupine inhibitors exert deleterious effects on bone mass and strength caused by a combination of reduced bone formation and increased bone resorption. We suggest that cancer targeted therapies using Porcupine inhibitors may increase the risk of fractures.
|
|
21. |
- Henning, Petra, 1974, et al.
(author)
-
Stimulation of osteoclast formation and bone resorption by glucocorticoids: Synergistic interactions with the calcium regulating hormones parathyroid hormone and 1,25(OH)2-vitamin D3
- 2022
-
In: Vitamins and Hormones Vol 120 Parathyroid Hormone. - : Elsevier. - 0083-6729. ; , s. 231-270
-
Book chapter (other academic/artistic)abstract
- Osteoporosis is a significant health problem, with skeletal fractures increasing morbidity and mortality. Excess glucocorticoids (GC) represents the leading cause of secondary osteoporosis. The first phase of glucocorticoid-induced osteoporosis is increased bone resorption. In this Chapter, in vitro studies of the direct glucocorticoid receptor (GR) mediated cellular effects of GC on osteoclasts to affect bone resorption and indirect effects on osteoblast lineage cells to increase the RANKL/OPG ratio and stimulate osteoclastogenesis and bone resorption are reviewed in detail, together with detailed descriptions of in vivo effects of GC in different portions of the skeleton in research animals and humans. Brief sections are devoted to contrasting functions of GC in osteonecrosis, vitamin D formation, in vitro and in vivo bone resorptive actions dependent on vitamin D receptor and vitamin D toxicity, as well as the molecular basis of GR action. Included are also more detailed assessments of the interactions of GC with the major calcium regulating hormones, 1,25(OH)2-vitamin D3 and parathyroid hormone, describing the in vitro increases in RANKL/OPG ratios, osteoclastogenesis and synergistic bone resorption that occurs when GC is combined with either 1,25(OH)2-vitamin D3 or parathyroid hormone. Additionally, a molecular basic for the synergistic interaction of GC with 1,25(OH)2-vitamin D3 is provided along with a suggested molecular basic for the interaction between GC and parathyroid hormone.
|
|
22. |
- Henning, Petra, 1974, et al.
(author)
-
WNT16 is Robustly Increased by Oncostatin M in Mouse Calvarial Osteoblasts and Acts as a Negative Feedback Regulator of Osteoclast Formation Induced by Oncostatin M
- 2021
-
In: Journal of Inflammation Research. ; 14, s. 4723-4741
-
Journal article (peer-reviewed)abstract
- Background: Bone loss is often observed adjacent to inflammatory processes. The WNT signaling pathways have been implicated as novel regulators of both immune responses and bone metabolism. WNT16 is important for cortical bone mass by inhibiting osteoclast differentiation, and we have here investigated the regulation of WNT16 by several members of the pro-inflammatory gp130 cytokine family. Methods: The expression and regulation of Wnt16 in primary murine cells were studied by qPCR, scRNAseq and in situ hybridization. Signaling pathways were studied by siRNA silencing. The importance of oncostatin M (OSM)-induced WNT16 expression for osteoclastogenesis was studied in cells from Wnt16-deficient and wild-type mice. Results: We found that IL-6/sIL-6R and OSM induce the expression of Wnt16 in primary mouse calvarial osteoblasts, with OSM being the most robust stimulator. The induction of Wnt16 by OSM was dependent on gp130 and OSM receptor (OSMR), and downstream signaling by the SHC1/STAT3 pathway, but independent of ERK. Stimulation of the calvarial cells with OSM resulted in enhanced numbers of mature, oversized osteoclasts when cells were isolated from Wnt16 deficient mice compared to cells from wild-type mice. OSM did not affect Wnt16 mRNA expression in bone marrow cell cultures, explained by the finding that Wnt16 and Osmr are expressed in distinctly different cells in bone marrow, nor was osteoclast differentiation different in OSM-stimulated bone marrow cell cultures isolated from Wnt16-/- or wild-type mice. Furthermore, we found that Wnt16 expression is substantially lower in cells from bone marrow compared to calvarial osteoblasts. Conclusion: These findings demonstrate that OSM is a robust stimulator of Wnt16 mRNA in calvarial osteoblasts and that WNT16 acts as a negative feedback regulator of OSMinduced osteoclast formation in the calvarial bone cells, but not in the bone marrow.
|
|
23. |
- Johansson, Helena, 1981, et al.
(author)
-
High serum adiponectin predicts incident fractures in elderly men: Osteoporotic fractures in men (MrOS) Sweden
- 2012
-
In: Journal of Bone and Mineral Research. - : Wiley. - 1523-4681 .- 0884-0431. ; 27:6, s. 1390-1396
-
Journal article (peer-reviewed)abstract
- Adipocytes and osteoblasts share a common progenitor, and there is, therefore, potential for both autocrine and endocrine effects of adiponectin on skeletal metabolism. The aim of the present study was to determine whether high serum adiponectin was associated with an increased risk of fracture in elderly men. We studied the relationship between serum adiponectin and the risk of fracture in 999 elderly men drawn from the general population and recruited to the Osteoporotic Fractures in Men (MrOS) study in Gothenburg, Sweden. Baseline data included general health questionnaires, lifestyle questionnaires, body mass index (BMI), bone mineral density (BMD), serum adiponectin, osteocalcin, and leptin. Men were followed for up to 7.4 years (average, 5.2 years). Poisson regression was used to investigate the relationship between serum adiponectin, other risk variables and the time-to-event hazard function of fracture. Median levels of serum adiponectin at baseline were 10.4 mu g/mL (interquartile range, 7.714.3). During follow-up, 150 men sustained one or more fractures. The risk of fracture increased in parallel with increasing serum adiponectin (hazard ratio [HR]/SD, 1.46; 95% confidence interval [CI], 1.231.72) and persisted after multivariate-adjusted analysis (HR/SD, 1.30; 95% CI, 1.091.55). Serum adiponectin shows graded stepwise association with a significant excess risk of fracture in elderly men that was independent of several other risk factors for fracture. Its measurement holds promise as a risk factor for fracture in men. (C) 2012 American Society for Bone and Mineral Research.
|
|
24. |
- Kaneko, H, et al.
(author)
-
Effects of prostaglandin E2 and lipopolysaccharide on osteoclastogenesis in RAW 264.7 cells.
- 2007
-
In: Prostaglandins, leukotrienes, and essential fatty acids. - Edinburgh : Elsevier BV. - 0952-3278 .- 1532-2823. ; 77:3-4, s. 181-6
-
Journal article (peer-reviewed)abstract
- INTRODUCTION: Prostaglandins (PGs) can act on both hematopoietic and osteoblastic lineages to enhance osteoclast formation. METHODS: We examined PGE2 stimulated osteoclastogenesis in RAW 264.7 cells and the role of endogenous PGE2 in lipopolysaccharide (LPS) stimulated osteoclastogenesis. RESULTS: RANKL (1-100 ng/ml) increased formation of osteoclasts, defined as tartrate resistant acid phosphatase multinucleated cells, with peak effects at 30 ng/ml. Addition of PGE2 (0.01-1.0 microM) to RANKL (30 ng/ml) dose dependently increased osteoclast number 30-150%. Use of NS-398 (0.1 microM) or indomethacin (Indo, 1.0 micro M) to block endogenous PG synthesis had little effect on the response to RANKL alone but significantly decreased the response to PGE2. Addition of LPS (100 ng/ml) to RANKL increased osteoclast number 50%, and this response was significantly decreased by NS-398 and Indo. RANKL and PGE2 produced small, additive increases in COX-2 mRNA levels, while LPS produced a larger increase. PG release into the medium was not increased by RANKL and PGE2 but markedly increased by LPS. CONCLUSION: We conclude that RANKL stimulated osteoclastogenesis can be enhanced by PGE2 and LPS though direct effects on the hematopoietic cell lineage and that these effects may be mediated in part by induction of COX-2 and enhanced intracellular PG production.
|
|
25. |
- Lewerin, Catharina, 1961, et al.
(author)
-
High plasma osteocalcin is associated with low blood haemoglobin in elderly men: the MrOS Sweden Study
- 2016
-
In: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 280:4, s. 398-406
-
Journal article (peer-reviewed)abstract
- BACKGROUND: It has been suggested that osteoblasts are involved in the regulation of haematopoietic stem cells. Whether osteocalcin, which is derived from osteoblasts and is metabolically active, influences blood haemoglobin (Hb) levels is not known. OBJECTIVE: To determine whether plasma osteocalcin is a determinant of Hb in elderly men. METHODS: A total of 993 men (mean age 75.3 +/- 3.2 years) participated in the population-based MrOS (osteoporotic fractures in men) study. Plasma osteocalcin concentration was evaluated in relation to Hb and adjustments were made for potential confounders (i.e. age, body mass index, erythropoietin, total oestradiol, fasting insulin, adiponectin, ferritin and cystatin C). RESULTS: Hb correlated (age adjusted) negatively with osteocalcin in the total study group (r = -0.12, P < 0.001) as well as in the subgroup of nondiabetic men (r = -0.16, P < 0.001). In nondiabetic men with higher osteocalcin levels, it was more likely that Hb would be in the lowest quartile (odds ratio per SD decrease in osteocalcin 1.32, 95% confidence interval 1.13-1.53). Quartiles of Hb were negatively associated (age adjusted) with osteocalcin (P < 0.001). Anaemic men (47/812) (Hb <130 g L-1 ) had significantly higher mean osteocalcin levels than nonanaemic men (33.9 vs. 27.1 mug L-1 , P < 0.001). In multiple stepwise linear regression analyses (adjusted for age, body mass index, total oestradiol, adiponectin, erythropoietin, fasting insulin, cystatin C, leptin, ferritin and holotranscobalamin), osteocalcin was an independent predictor of Hb concentration in nondiabetic men (P < 0.05). CONCLUSIONS: These data add further support to the evidence indicating that the bone-specific protein osteocalcin has several endocrine functions targeting the pancreas, testes, adipocytes, brain. An additional novel finding is that osteocalcin may also have a paracrine function as a regulator of haematopoiesis.
|
|
26. |
- Lewerin, Catharina, 1961, et al.
(author)
-
High serum adiponectin is associated with low blood haemoglobin in elderly men: the Swedish MrOS study
- 2015
-
In: Journal of Internal Medicine. - : Wiley. - 1365-2796 .- 0954-6820. ; 278:1, s. 68-76
-
Journal article (peer-reviewed)abstract
- Objectives: Blood haemoglobin (Hb) concentration declines in elderly men, whilst the level of the adipocyte-derived protein adiponectin increases with age. The association between erythropoiesis and adiponectin in elderly men is unclear. The aim of this study was to determine whether adipokines such as adiponectin and leptin are associated with anaemia and Hb concentration in elderly community-dwelling men. Design and setting: The Gothenburg part of the population-based Swedish Osteoporotic Fractures in Men (MrOS) cohort (n=1010; median age 75.3years, range 69-81). Main outcome measures: We investigated the associations between levels of adiponectin and Hb before and after adjusting for potential confounders [i.e. age, body composition, erythropoietin (EPO), total oestradiol, leptin, cystatin C and iron and B vitamin status]. Results: In these elderly men, age was negatively associated with Hb (r=-0.12, P<0.001) and positively associated with adiponectin level (r=0.13, P<0.001). In age-adjusted partial correlations, Hb and adiponectin levels were negatively correlated (r=-0.20, P<0.001); this association remained significant after multivariable adjustment for age, body composition, EPO, fasting insulin, sex hormones, leptin and ferritin. Age-adjusted mean adiponectin concentrations were significantly higher in anaemic men (66/1005; Hb <130gL(-1)) compared to nonanaemic men (14.0 vs. 11.7 gmL(-1), P<0.05). In multivariate analysis, adiponectin together with EPO, total oestradiol, insulin, albumin, transferrin saturation, HDL cholesterol, cystatin C, total body fat mass and free thyroxine, but not leptin, explained 35% of the variation in Hb level. These results remained essentially unchanged after exclusion of men with diabetes. Conclusions: Serum adiponectin, but not leptin, was negatively and independently associated with Hb. This finding suggests a possible role of adiponectin in the age-related decline in Hb level observed in apparently healthy elderly men.
|
|
27. |
- Lionikaite, Vikte, et al.
(author)
-
Vitamin A decreases the anabolic bone response to mechanical loading by suppressing bone formation
- 2019
-
In: FASEB journal : official publication of the Federation of American Societies for Experimental Biology. - : Federation of American Societies for Experimental Biology. - 1530-6860 .- 0892-6638. ; 33:4, s. 5237-5247
-
Journal article (peer-reviewed)abstract
- Increased vitamin A consumption is associated with decreased cortical bone mass and increased fracture risk in humans. Rodent studies have demonstrated that hypervitaminosis A increases cortical bone resorption, whereas the importance of the effects on bone formation is less well defined. We used an experimental model of increased bone formation by loading of the tibiae to investigate the effect of vitamin A on bone formation. Control [retinol activity equivalents (RAE) 4.5 µg/g chow] or vitamin A (RAE 60 µg/g chow) diets were given to female C57BL/6N mice for 4 wk, after which the tibiae were subjected to axial loading on alternate days for 2 wk, while the diets were continued. Vitamin A inhibited the loading-induced increase in trabecular and cortical bone volume. This was attributed to inhibition of loading-induced increase in osteoblast number and activity, and expression of osteoblastic genes Sp7, Alpl, and Col1a1 in cortical bone. Vitamin A, loading, and combination thereof also resulted in site-specific effects on bone composition measured by Raman spectroscopy. In summary, a clinically relevant dose of vitamin A suppresses the loading-induced gain of bone mass by decreasing bone formation. These observations may have implications for regulation of bone mass caused by physical activity and the risk of osteoporosis in humans.-Lionikaite, V., Henning, P., Drevinge, C., Shah, F. A., Palmquist, A., Wikström, P., Windahl, S. H., Lerner, U. H. Vitamin A decreases the anabolic bone response to mechanical loading by suppressing bone formation.
|
|
28. |
- Makitie, R. E., et al.
(author)
-
An ARHGAP25 variant links aberrant Rac1 function to early-onset skeletal fragility
- 2021
-
In: JBMR Plus. - : Wiley. - 2473-4039. ; 5:7
-
Journal article (peer-reviewed)abstract
- Ras homologous guanosine triphosphatases (RhoGTPases) control several cellular functions, including cytoskeletal actin remodeling and cell migration. Their activities are downregulated by GTPase-activating proteins (GAPs). Although RhoGTPases are implicated in bone remodeling and osteoclast and osteoblast function, their significance in human bone health and disease remains elusive. Here, we report defective RhoGTPase regulation as a cause of severe, early-onset, autosomal-dominant skeletal fragility in a three-generation Finnish family. Affected individuals (n = 13) presented with multiple low-energy peripheral and vertebral fractures despite normal bone mineral density (BMD). Bone histomorphometry suggested reduced bone volume, low surface area covered by osteoblasts and osteoclasts, and low bone turnover. Exome sequencing identified a novel heterozygous missense variant c.652G>A (p.G218R) in ARHGAP25, encoding a GAP for Rho-family GTPase Rac1. Variants in the ARHGAP25 5 ' untranslated region (UTR) also associated with BMD and fracture risk in the general population, across multiple genomewide association study (GWAS) meta-analyses (lead variant rs10048745). ARHGAP25 messenger RNA (mRNA) was expressed in macrophage colony-stimulating factor (M-CSF)-stimulated human monocytes and mouse osteoblasts, indicating a possible role for ARHGAP25 in osteoclast and osteoblast differentiation and activity. Studies on subject-derived osteoclasts from peripheral blood mononuclear cells did not reveal robust defects in mature osteoclast formation or resorptive activity. However, analysis of osteosarcoma cells overexpressing the ARHGAP25 G218R-mutant, combined with structural modeling, confirmed that the mutant protein had decreased GAP-activity against Rac1, resulting in elevated Rac1 activity, increased cell spreading, and membrane ruffling. Our findings indicate that mutated ARHGAP25 causes aberrant Rac1 function and consequently abnormal bone metabolism, highlighting the importance of RhoGAP signaling in bone metabolism in familial forms of skeletal fragility and in the general population, and expanding our understanding of the molecular pathways underlying skeletal fragility. (c) 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
|
|
29. |
- Moverare-Skrtic, Sofia, et al.
(author)
-
Osteoblast-derived NOTUM reduces cortical bone mass in mice and the NOTUM locus is associated with bone mineral density in humans
- 2019
-
In: Faseb Journal. - 0892-6638. ; 33:10, s. 11163-11179
-
Journal article (peer-reviewed)abstract
- Osteoporosis is a common skeletal disease, affecting millions of individuals worldwide. Currently used osteoporosis treatments substantially reduce vertebral fracture risk, whereas nonvertebral fracture risk, mainly caused by reduced cortical bone mass, has only moderately been improved by the osteoporosis drugs used, defining an unmet medical need. Because several wingless-type MMTV integration site family members (WNTs) and modulators of WNT activity are major regulators of bone mass, we hypothesized that NOTUM, a secreted WNT lipase, might modulate bone mass via an inhibition of WNT activity. To characterize the possible role of endogenous NOTUM as a physiologic modulator of bone mass, we developed global, cell-specific, and inducible Notum-inactivated mouse models. Notum expression was high in the cortical bone in mice, and conditional Notum inactivation revealed that osteoblast lineage cells are the principal source of NOTUM in the cortical bone. Osteoblast lineage-specific Notum inactivation increased cortical bone thickness via an increased periosteal circumference. Inducible Notum inactivation in adult mice increased cortical bone thickness as a result of increased periosteal bone formation, and silencing of Notum expression in cultured osteoblasts enhanced osteoblast differentiation. Large-scale human genetic analyses identified genetic variants mapping to the NOTUM locus that are strongly associated with bone mineral density (BMD) as estimated with quantitative ultrasound in the heel. Thus, osteoblast-derived NOTUM is an essential local physiologic regulator of cortical bone mass via effects on periosteal bone formation in adult mice, and genetic variants in the NOTUM locus are associated with BMD variation in adult humans. Therapies targeting osteoblast-derived NOTUM may prevent nonvertebral fractures.-Moverare-Skrtic, S., Nilsson, K. H., Henning, P., Funck-Brentano, T., Nethander, M., Rivadeneira, F., Coletto Nunes, G., Koskela, A., Tuukkanen, J., Tuckermann, J., Perret, C., Souza, P. P. C., Lerner, U. H., Ohlsson, C. Osteoblast-derived NOTUM reduces cortical bone mass in mice and the NOTUM locus is associated with bone mineral density in humans.
|
|
30. |
- Movérare-Skrtic, Sofia, et al.
(author)
-
The bone-sparing effects of estrogen and WNT16 are independent of each other
- 2015
-
In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 112:48, s. 14972-14977
-
Journal article (peer-reviewed)abstract
- Wingless-type MMTV integration site family (WNT)16 is a key regulator of bone mass with high expression in cortical bone, and Wnt16-/- mice have reduced cortical bone mass. As Wnt16 expression is enhanced by estradiol treatment, we hypothesized that the bone-sparing effect of estrogen in females isWNT16-dependent. This hypothesis was tested in mechanistic studies using two genetically modified mouse models with either constantly high osteoblastic Wnt16 expression or no Wnt16 expression. We developed a mouse model with osteoblast-specific Wnt16 overexpression (Obl-Wnt16). These mice had several-fold elevated Wnt16 expression in both trabecular and cortical bone compared with wild type (WT) mice. Obl- Wnt16 mice displayed increased total body bone mineral density (BMD), surprisingly caused mainly by a substantial increase in trabecular bone mass, resulting in improved bone strength of vertebrae L3. Ovariectomy (ovx) reduced the total body BMD and the trabecular bone mass to the same degree in Obl-Wnt16 mice and WT mice, suggesting that the bone-sparing effect of estrogen is WNT16-independent. However, these bone parameters were similar in ovx Obl- Wnt16 mice and sham operated WT mice. The role of WNT16 for the bone-sparing effect of estrogen was also evaluated in Wnt16-/- mice. Treatment with estradiol increased the trabecular and cortical bone mass to a similar extent in both Wnt16-/- and WT mice. In conclusion, the bone-sparing effects of estrogen and WNT16 are independent of each other. Furthermore, loss of endogenous WNT16 results specifically in cortical bone loss, whereas overexpression of WNT16 surprisingly increases mainly trabecular bone mass. WNT16- targeted therapies might be useful for treatment of postmenopausal trabecular bone loss.
|
|
31. |
- Nilsson, Karin H., et al.
(author)
-
Estradiol and RSPO3 regulate vertebral trabecular bone mass independent of each other
- 2022
-
In: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 322:3
-
Journal article (peer-reviewed)abstract
- Osteoporosis is an age-dependent serious skeletal disease that leads to great suffering for the patient and high social costs, especially as the global population reaches higher age. Decreasing estrogen levels after menopause result in a substantial bone loss and increased fracture risk, whereas estrogen treatment improves bone mass in women. RSPO3, a secreted protein that modulates WNT signaling, increases trabecular bone mass and strength in the vertebrae of mice, and is associated with trabecular density and risk of distal forearm fractures in humans. The aim of the present study was to determine if RSPO3 is involved in the bone-sparing effect of estrogens. We first observed that estradiol (E2) treatment increases RSPO3 expression in bone of ovariectomized (OVX) mice, supporting a possible role of RSPO3 in the bone-sparing effect of estrogens. As RSPO3 is mainly expressed by osteoblasts in the bone, we used a mouse model devoid of osteoblast-derived RSPO3 (Runx2-creRspo3flox/flox mice) to determine if RSPO3 is required for the bone-sparing effect of E2 in OVX mice. We confirmed that osteoblast-specific RSPO3 inactivation results in a substantial reduction in trabecular bone mass and strength in the vertebrae. However, E2 increased vertebral trabecular bone mass and strength similarly in mice devoid of osteoblast-derived RSPO3 and control mice. Unexpectedly, osteoblast-derived RSPO3 was needed for the full estrogenic response on cortical bone thickness. In conclusion, although osteoblast-derived RSPO3 is a crucial regulator of vertebral trabecular bone, it is required for a full estrogenic effect on cortical, but not trabecular, bone in OVX mice. Thus, estradiol and RSPO3 regulate vertebral trabecular bone mass independent of each other.NEW & NOTEWORTHY Osteoblast-derived RSPO3 is known to be a crucial regulator of vertebral trabecular bone. Our new findings show that RSPO3 and estrogen regulate trabecular bone independent of each other, but that RSPO3 is necessary for a complete estrogenic effect on cortical bone.
|
|
32. |
- Nilsson, Karin H., et al.
(author)
-
GREM2 inactivation increases trabecular bone mass in mice
- 2024
-
In: SCIENTIFIC REPORTS. - 2045-2322. ; 14:1
-
Journal article (peer-reviewed)abstract
- Osteoporosis is a common skeletal disease affecting millions of individuals world-wide, with an increased risk of fracture, and a decreased quality of life. Despite its well-known consequences, the etiology of osteoporosis and optimal treatment methods are not fully understood. Human genetic studies have identified genetic variants within the FMN2/GREM2 locus to be associated with trabecular volumetric bone mineral density (vBMD) and vertebral and forearm fractures, but not with cortical bone parameters. GREM2 is a bone morphogenetic protein (BMP) antagonist. In this study, we employed Grem2-deficient mice to investigate whether GREM2 serves as the plausible causal gene for the fracture signal at the FMN2/GREM2 locus. We observed that Grem2 is moderately expressed in bone tissue and particularly in osteoblasts. Complete Grem2 gene deletion impacted mouse survival and body growth. Partial Grem2 inactivation in Grem2 +/- female mice led to increased trabecular BMD of femur and increased trabecular bone mass in tibia due to increased trabecular thickness, with an unchanged cortical thickness, as compared with wildtype littermates. Furthermore, Grem2 inactivation stimulated osteoblast differentiation, as evidenced by higher alkaline phosphatase (Alp), osteocalcin (Bglap), and osterix (Sp7) mRNA expression after BMP-2 stimulation in calvarial osteoblasts and osteoblasts from the long bones of Grem2 -/- mice compared to wildtype littermates. These findings suggest that GREM2 is a possible target for novel osteoporotic treatments, to increase trabecular bone mass and prevent osteoporotic fractures.
|
|
33. |
- Nilsson, Karin H., et al.
(author)
-
Osteocyte- and late osteoblast-derived NOTUM reduces cortical bone mass in mice
- 2021
-
In: American Journal of Physiology-Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 320:5
-
Journal article (peer-reviewed)abstract
- Osteoporosis is a common skeletal disease, with increased risk of fractures. Currently available osteoporosis treatments reduce the risk of vertebral fractures, mainly dependent on trabecular bone, whereas the effect on nonvertebral fractures, mainly dependent on cortical bone, is less pronounced. WNT signaling is a crucial regulator of bone homeostasis, and the activity of WNTs is inhibited by NOTUM, a secreted WNT lipase. We previously demonstrated that conditional inactivation of NOTUM in all osteoblast lineage cells increases the cortical but not the trabecular bone mass. The aim of the present study was to determine if NOTUM increasing cortical bone is derived from osteoblast precursors/early osteoblasts or from osteocytes/late osteoblasts. First, we demonstrated Notum mRNA expression in Dmp1-expressing osteocytes and late osteoblasts in cortical bone using in situ hybridization. We then developed a mouse model with inactivation of NOTUM in Dmp1-expressing osteocytes and late osteoblasts (Dmp1-creNotum(flox/flox) mice). We observed that the Dmp1-creNotum(flox/flox) mice displayed a substantial reduction of Notum mRNA in cortical bone, resulting in increased cortical bone mass and decreased cortical porosity in femur but no change in trabecular bone volume fraction in femur or in the lumbar vertebrae L5 in Dmp1-creNotum(flox/flox) mice as compared with control mice. In conclusion, osteocytes and late osteoblasts are the principal source of NOTUM in cortical bone, and NOTUM derived from osteocytes/late osteoblasts reduces cortical bone mass. These findings demonstrate that inhibition of osteocyte/ late osteoblast-derived NOTUM might be an interesting pharmacological target to increase cortical bone mass and reduce non vertebral fracture risk. NEW & NOTEWORTHY NOTUM produced by osteoblasts is known to regulate cortical bone mass. Our new findings show that NOTUM specifically derived by DMP1-expressing osteocytes and late osteoblasts regulates cortical bone mass and not trabecular bone mass.
|
|
34. |
- Ohlsson, Claes, 1965, et al.
(author)
-
Inducible Wnt16 inactivation: WNT16 regulates cortical bone thickness in adult mice.
- 2018
-
In: The Journal of endocrinology. - 1479-6805. ; 237:2, s. 113-122
-
Journal article (peer-reviewed)abstract
- Substantial progress has been made in the therapeutic reduction of vertebral fracture risk in patients with osteoporosis, but non-vertebral fracture risk has been improved only marginally. Human genetic studies demonstrate that the WNT16 locus is a major determinant of cortical bone thickness and non-vertebral fracture risk and mouse models with life-long Wnt16 inactivation revealed that WNT16 is a key regulator of cortical thickness. These studies, however, could not exclude that the effect of Wnt16 inactivation on cortical thickness might be caused by early developmental and/or growth effects. To determine the effect of WNT16 specifically on adult cortical bone homeostasis, Wnt16 was conditionally ablated in young adult and old mice through tamoxifen-inducible Cre-mediated recombination using CAG-Cre-ER; Wnt16flox/flox (Cre-Wnt16flox/flox) mice. First, 10-week-old Cre-Wnt16flox/flox and Wnt16flox/flox littermate control mice were treated with tamoxifen. Four weeks later, Wnt16 mRNA levels in cortical bone were reduced and cortical thickness in femur was decreased in Cre-Wnt16flox/flox mice compared to Wnt16flox/flox mice. Then, inactivation of Wnt16 in 47-week-old mice (evaluated four weeks later) resulted in a reduction of Wnt16 mRNA levels, cortical thickness and cortical bone strength with no effect on trabecular bone volume fraction. Mechanistic studies demonstrated that the reduced cortical bone thickness was caused by a combination of increased bone resorption and reduced periosteal bone formation. In conclusion, WNT16 is a crucial regulator of cortical bone thickness in young adult and old mice. We propose that new treatment strategies targeting the adult regulation of WNT16 might be useful to reduce fracture risk at cortical bone sites.
|
|
35. |
- Ohlsson, Claes, 1965, et al.
(author)
-
WNT16 overexpression partly protects against glucocorticoid-induced bone loss
- 2018
-
In: American Journal of Physiology-Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 314:6
-
Journal article (peer-reviewed)abstract
- Therapeutic use of glucocorticoids (GCs) is a major cause of secondary osteoporosis, but the molecular mechanisms responsible for the deleterious effects of GCs in bone are only partially understood. WNT16 is a crucial physiological regulator of bone mass and fracture susceptibility, and we hypothesize that disturbed WNT16 activity might be involved in the deleterious effects of GC in bone. Twelve-week-old female Obl-Wnt16 mice (WNT16 expression driven by the rat procollagen type I alpha 1 promoter) and wild-type (WT) littermates were treated with prednisolone (7.6 mg.kg(-1).day(-1)) or vehicle for 4 wk. We first observed that GC treatment decreased the Wnt16 mRNA levels in bone of female mice (-56.4 +/- 6.1% compared with vehicle, P < 0.001). We next evaluated if WNT16 overexpression protects against GC-induced bone loss. Dual-energy X-ray absorptiometry analyses revealed that GC treatment decreased total body bone mineral density in WT mice (-3.9 +/- 1.2%, P = 0.028) but not in Obl-Wnt16 mice (+1.3 +/- 1.4%, nonsignificant). Microcomputed tomography analyses showed that GC treatment decreased trabecular bone volume fraction (BV/TV) of the femur in WT mice (P = 0.019) but not in Obl-Wnt16 mice. Serum levels of the bone formation marker procollagen type I N-terminal propeptide were substantially reduced by GC treatment in WT mice (-50.3 +/- 7.0%, P = 0.008) but not in Obl-Wnt16 mice (-3.8 +/- 21.2%, nonsignificant). However, the cortical bone thickness in femur was reduced by GC treatment in both WT mice and Obl-Wnt16 mice. In conclusion. GC treatment decreases Wnt16 mRNA levels in bone and WNT16 overexpression partly protects against GC-induced bone loss.
|
|
36. |
- Palmqvist, Py, et al.
(author)
-
Inhibition of hormone and cytokine-stimulated osteoclastogenesis and bone resorption by interleukin-4 and interleukin-13 is associated with increased osteoprotegerin and decreased RANKL and RANK in a STAT6-dependent pathway.
- 2006
-
In: The Journal of biological chemistry. - 0021-9258 .- 1083-351X. ; 281:5, s. 2414-29
-
Journal article (peer-reviewed)abstract
- Interleukin (IL)-4 and IL-13 are cytokines that inhibit bone resorption. Data showing an inhibitory effect of IL-4 and IL-13 on RANK mRNA in mouse calvariae were first reported at the 22nd American Society for Bone and Mineral Research Meeting (Lerner, U.H., and Conaway, H. H. 2000) J. Bone Min. Res. 15, Suppl. 1, Abstr. SU 230). In the present study, release of 45Ca from cultured mouse calvarial bones stimulated by different cytokines, peptides, and steroid hormones was inhibited by IL-4 and IL-13. IL-4 and IL-13 decreased receptor activator of nuclear factor-kappaB ligand (RANKL) and RANK mRNA and increased osteoprotegerin (OPG) mRNA in calvariae. Additionally, the cytokines decreased RANKL protein and increased OPG protein in calvarial bones. In osteoblasts isolated from calvariae, both an increase in RANKL mRNA and a decrease in OPG mRNA and protein elicited by vitamin D3 were reversed by IL-4 and IL-13. IL-4 and IL-13 decreased the number of tartrate-resistant acid phosphatase positive multinucleated cells and the mRNA expression of calcitonin receptor, tartrate-resistant acid phosphatase, and cathepsin K in mouse spleen cells and bone marrow macrophages (BMM) treated with macrophage colony-stimulating factor and RANKL. Inhibition of mRNA for RANK and the transcription factor NFAT2 was also noted in spleen cell and BMM cultures treated with IL-4 and IL-13. In addition, RANK mRNA and RANK protein were decreased by IL-4 and IL-13 in RAW 264.7 cells. Osteoblasts, spleen cells, and BMM expressed mRNA for the four proteins making up the IL-4 and IL-13 receptors. No effects by IL-4 on bone resorption and osteoclast formation or on RANKL and RANK mRNA expression were seen in Stat6-/- mice. The data indicate that IL-4 and IL-13, via a STAT6-dependent pathway, inhibit osteoclast differentiation and bone resorption by activating receptors on osteoblasts and osteoclasts that affect the RANKL/RANK/OPG system.
|
|
37. |
- Palmqvist, Py, et al.
(author)
-
Interleukin-4 and interleukin-13 inhibit the expression of leukemia inhibitory factor and interleukin-11 in fibroblasts.
- 2012
-
In: Molecular immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 49:4, s. 601-10
-
Journal article (peer-reviewed)abstract
- Cytokines produced by inflammatory or resident mesenchymal cells play important modulatory roles in the pathogenesis of inflammation induced bone loss. In the present study, the effects of IL-4 and IL-13 on the expression of three osteotropic cytokines in the IL-6 family expressed in human gingival fibroblasts were studied. IL-4Rα and IL-13Rα1 mRNA were constitutively expressed in human gingival fibroblasts. The inflammatory cytokines IL-1β and TNF-α increased expression of IL-6, LIF, and IL-11 mRNA and protein in the gingival fibroblasts. Addition of IL-4 or IL-13 had no effect on IL-6 expression, but significantly inhibited LIF and IL-11 mRNA and protein stimulated by IL-1β and TNF-α. No involvement of NF-κB or STAT1 was observed in the inhibition. STAT6 was phosphorylated at Y641 by treatment with IL-4 and knockdown of STAT6 with siRNA decreased the inhibition of IL-11 and LIF expression by IL-4 in IL-1β and TNF-α stimulated cells. This study suggests that activation of STAT6 by IL-4 and IL-13, through type 2 IL-4 receptors, inhibits production of IL-11 and LIF stimulated by IL-1β and TNF-α in human gingival fibroblasts. A negative modulatory role of IL-4 and IL-13 in osteotropic cytokine production could be a mechanism playing an important inhibitory role in inflammation induced periodontitis.
|
|
38. |
- Stattin, Eva-Lena, et al.
(author)
-
SNX10 gene mutation leading to osteopetrosis with dysfunctional osteoclasts
- 2017
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
-
Journal article (peer-reviewed)abstract
- Autosomal recessive osteopetrosis (ARO) is a heterogeneous disorder, characterized by defective osteoclastic resorption of bone that results in increased bone density. We have studied nine individuals with an intermediate form of ARO, from the county of Vasterbotten in Northern Sweden. All afflicted individuals had an onset in early infancy with optic atrophy, and in four patients anemia was present at diagnosis. Tonsillar herniation, foramen magnum stenosis, and severe osteomyelitis of the jaw were common clinical features. Whole exome sequencing, verified by Sanger sequencing, identified a splice site mutation c.212 + 1 G > T in the SNX10 gene encoding sorting nexin 10. Sequence analysis of the SNX10 transcript in patients revealed activation of a cryptic splice site in intron 4 resulting in a frame shift and a premature stop (p.S66Nfs * 15). Haplotype analysis showed that all cases originated from a single mutational event, and the age of the mutation was estimated to be approximately 950 years. Functional analysis of osteoclast progenitors isolated from peripheral blood of patients revealed that stimulation with receptor activator of nuclear factor kappa-B ligand (RANKL) resulted in a robust formation of large, multinucleated osteoclasts which generated sealing zones; however these osteoclasts exhibited defective ruffled borders and were unable to resorb bone in vitro.
|
|
39. |
- Swanson, Charlotte, 1975, et al.
(author)
-
Glucocorticoid regulation of osteoclast differentiation and expression of receptor activator of nuclear factor-kappaB (NF-kappaB) ligand, osteoprotegerin, and receptor activator of NF-kappaB in mouse calvarial bones.
- 2006
-
In: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 147:7, s. 3613-22
-
Journal article (peer-reviewed)abstract
- In the present study, dexamethasone treatment of neonatal mouse calvarial bones increased mRNA expression of tartrate-resistant acid phosphatase, calcitonin receptor (CTR), cathepsin K, carbonic anhydrase II, osteoprotegerin (OPG), and receptor activator of nuclear factor-kappaB (RANK) as well as mRNA and protein expression of RANK ligand (RANKL). The increase in OPG mRNA noted with dexamethasone was in contrast to 1,25(OH)(2)-vitamin D3 (D3) treatment, which decreased OPG expression. Stimulation of (45)Ca release by dexamethasone and hydrocortisone in calvariae was blocked by OPG. Stimulation of RANKL, RANK, OPG, and CTR mRNA expression by dexamethasone in calvariae was blocked by the glucocorticoid receptor antagonist RU 38,486. Greater than additive potentiations of CTR mRNA and RANKL mRNA and protein were observed when D3 and dexamethasone were combined. Vitamin D receptor mRNA was increased by dexamethasone and D3, whereas glucocorticoid receptor (GR) mRNA was decreased by dexamethasone and unaffected by D3. No synergistic interaction between dexamethasone and D3 on either vitamin D receptor or GR mRNA expression was noted. The data demonstrate that dexamethasone-induced bone resorption in calvarial bones is associated with increased differentiation of osteoclasts and regulation of the RANKL-RANK-OPG system. The increase in OPG expression and the decrease of GR expression noted with dexamethasone offer an explanation for why bone breakdown in mouse calvariae treated with glucocorticoids is less than that caused by resorptive agents like D3. The synergistic stimulation of RANKL by dexamethasone and D3 offers an explanation of how glucocorticoids and D3 interact to potentiate bone resorption.
|
|
40. |
- Windahl, Sara H, 1971, et al.
(author)
-
Estrogen Receptor-alpha is required for the Osteogenic Response to mechanical loading in a Ligand-Independent manner involving its activation function 1 but Not 2
- 2013
-
In: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 28:2, s. 291-301
-
Journal article (peer-reviewed)abstract
- Estrogen receptor-alpha (ER alpha) is crucial for the adaptive response of bone to loading but the role of endogenous estradiol (E2) for this response is unclear. To determine in vivo the ligand dependency and relative roles of different ERa domains for the osteogenic response to mechanical loading, gene-targeted mouse models with (1) a complete ERa inactivation (ER alpha(-/-)), (2) specific inactivation of activation function 1 (AF-1) in ER alpha (ER alpha AF-1(0)), or (3) specific inactivation of ER alpha AF-2 (ER alpha AF- 2(0)) were subjected to axial loading of tibia, in the presence or absence (ovariectomy [ovx]) of endogenous E2. Loading increased the cortical bone area in the tibia mainly as a result of an increased periosteal bone formation rate (BFR) and this osteogenic response was similar in gonadal intact and ovx mice, demonstrating that E2 (ligand) is not required for this response. Female ER alpha(-/-) mice displayed a severely reduced osteogenic response to loading with changes in cortical area (-78% +/- 15%, p < 0.01) and periosteal BFR (-81% +/- 9%, p < 0.01) being significantly lower than in wild-type (WT) mice. ER alpha AF-1(0) mice also displayed a reduced response to mechanical loading compared with WT mice (cortical area -40% +/- 11%, p < 0.05 and periosteal BFR -41% +/- 8%, p < 0.01), whereas the periosteal osteogenic response to loading was unaffected in ER alpha AF-2(0) mice. Mechanical loading of transgenic estrogen response element (ERE)-luciferase reporter mice did not increase luciferase expression in cortical bone, suggesting that the loading response does not involve classical genomic ERE-mediated pathways. In conclusion, ERa is required for the osteogenic response to mechanical loading in a ligand-independent manner involving AF-1 but not AF-2. (C) 2013 American Society for Bone and Mineral Research.
|
|
41. |
- Windahl, Sara H, 1971, et al.
(author)
-
Mechanical load, sex hormones, and bone modeling
- 2015. - 2
-
In: Biological mechanisms of tooth movement. - Chichester, UK : Wiley Blackwell. - 9781118916148 - 9781118688878 ; , s. 82-96
-
Book chapter (peer-reviewed)abstract
- Skeletal tissue is made up of two structurally different types of bones: cortical (compact) bone, forming an outer shell in all flat and long bones, and cancellous (trabecular) bone arranged in spicules in the inner marrow cavity of bones. Interestingly, bone cells are also controlled by signaling molecules in the peripheral and central nervous system such as catecholamines and serotonin, and by bacteria in the gastrointestinal tract. Differentiated osteoblasts are the cells that form new bone, and at the same time are crucial for differentiation of bone-resorbing osteoclasts. It has been found that receptors for most hormones and cytokines stimulating osteoclast formation are expressed by osteoblasts. Moreover, osteocytes respond to mechanical load through membrane-bound receptors. The sex hormone receptors contain stretches of amino acids called nuclear localization signals, which cooperate in the transfer of the steroid receptors to the nucleus where they are mainly located in most cells.
|
|
42. |
- Windahl, Sara H., et al.
(author)
-
Mechanical load, sex hormones, and bone modeling
- 2021. - 3
-
In: Biological Mechanisms of Tooth Movement. - : John Wiley & Sons. - 9781119608912 - 9781119608936 ; , s. 100-116
-
Book chapter (peer-reviewed)abstract
- Mechanical loading as a result of load-bearing physical activity is an important regulator of both bone mass and bone microarchitecture. Sex hormone receptor signaling involves several separate signaling cascades in a tissue-specific manner, affecting osteoclastic resorption, osteoblastic bone formation, bone modeling and remodeling, and is also an important determinant of bone mass. Interestingly, estrogen receptors play an important role in load-induced modeling of bone, an effect surprisingly found to be independent of estrogen. Modeling of jaw bones in response to orthodontic tooth movement is dependent on several factors where reshaping of bone by osteoclast and osteoblast activities are of major importance. Although not much studied, loading, sex hormones, and their receptors are likely to affect orthodontic tooth movement. This chapter gives an overview of bone cell differentiation and function and describes the role of sex hormone receptors in mechanical loading, and their possible role in orthodontic tooth movement.
|
|
43. |
- Alfredson, Håkan, et al.
(author)
-
cDNA-arrays and real-time quantitative PCR techniques in the investigation of chronic Achilles tendinosis.
- 2003
-
In: Journal of Orthopaedic Research. - 0736-0266 .- 1554-527X. ; 21:6, s. 970-975
-
Journal article (peer-reviewed)abstract
- The aetiology and pathogenesis of chronic painful Achilles tendinosis are unknown. This investigation aimed to use cDNA arrays and real-time quantitative polymerase chain reaction (real-time PCR) technique to study tendinosis and control tissue samples. Five patients (females mean age 57.1+/-4.3 (years+/-SD)) with chronic painful Achilles tendinosis were included. From all patients, one biopsy was taken from the area with tendinosis and one from a clinically normal area (control) of the tendon. The tissue samples were immediately immersed in RNAlater and frozen at -80 degrees C until RNA extraction. Portions of pooled RNA from control and tendinosis sites, respectively, were transcribed to cDNA, radioactively labelled (32P), hybridized to cDNA expression arrays, and exposed to phosphoimager screens over night. Expressions of specific genes, shown to be regulated in the cDNA array analysis, were analyzed in the individual samples using real-time PCR. cDNA arrays showed that gene expressions for matrix-metalloproteinase-2 (MMP-2), fibronectin subunit B (FNRB), vascular endothelial growth factor (VEGF), and mitogen-activated protein kinase p38 (MAPKp38) were up-regulated, while matrix-metalloproteinase-3 (MMP-3) and decorin were down-regulated, in tendinosis tissue compared with control tissue. Using real-time PCR, 4/5 and 3/5 patients showed up-regulation of MMP-2 and FNRB mRNA, respectively. For decorin, VEGF, and MAPKp38, real-time PCR revealed a great variability among patients. Interestingly, the mRNAs for several cytokines and cytokine receptors were not regulated, indicating the absence of an inflammatory process in chronic painful Achilles tendinosis. In conclusion, cDNA-arrays and real-time PCR can be used to study differences in gene expression levels between tendinosis and control tendon tissue.
|
|
44. |
- Andersson, Martin K, et al.
(author)
-
Effects on osteoclast and osteoblast activities in cultured mouse calvarial bones by synovial fluids from patients with a loose joint prosthesis and from osteoarthritis patients.
- 2007
-
In: Arthritis research & therapy. - : Springer Science and Business Media LLC. - 1478-6362 .- 1478-6354. ; 9:1
-
Journal article (peer-reviewed)abstract
- Aseptic loosening of a joint prosthesis is associated with remodelling of bone tissue in the vicinity of the prosthesis. In the present study, we investigated the effects of synovial fluid (SF) from patients with a loose prosthetic component and periprosthetic osteolysis on osteoclast and osteoblast activities in vitro and made comparisons with the effects of SF from patients with osteoarthritis (OA). Bone resorption was assessed by the release of calcium 45 (45Ca) from cultured calvariae. The mRNA expression in calvarial bones of molecules known to be involved in osteoclast and osteoblast differentiation was assessed using semi-quantitative reverse transcription-polymerase chain reaction (PCR) and real-time PCR. SFs from patients with a loose joint prosthesis and patients with OA, but not SFs from healthy subjects, significantly enhanced 45Ca release, effects associated with increased mRNA expression of calcitonin receptor and tartrate-resistant acid phosphatase. The mRNA expression of receptor activator of nuclear factor-kappa-B ligand (rankl) and osteoprotegerin (opg) was enhanced by SFs from both patient categories. The mRNA expressions of nfat2 (nuclear factor of activated T cells 2) and oscar (osteoclast-associated receptor) were enhanced only by SFs from patients with OA, whereas the mRNA expressions of dap12 (DNAX-activating protein 12) and fcrgamma (Fc receptor common gamma subunit) were not affected by either of the two SF types. Bone resorption induced by SFs was inhibited by addition of OPG. Antibodies neutralising interleukin (IL)-1alpha, IL-1beta, soluble IL-6 receptor, IL-17, or tumour necrosis factor-alpha, when added to individual SFs, only occasionally decreased the bone-resorbing activity. The mRNA expression of alkaline phosphatase and osteocalcin was increased by SFs from patients with OA, whereas only osteocalcin mRNA was increased by SFs from patients with a loose prosthesis. Our findings demonstrate the presence of a factor (or factors) stimulating both osteoclast and osteoblast activities in SFs from patients with a loose joint prosthesis and periprosthetic osteolysis as well as in SFs from patients with OA. SF-induced bone resorption was dependent on activation of the RANKL/RANK/OPG pathway. The bone-resorbing activity could not be attributed solely to any of the known pro-inflammatory cytokines, well known to stimulate bone resorption, or to RANKL or prostaglandin E2 in SFs. The data indicate that SFs from patients with a loose prosthesis or with OA stimulate bone resorption and that SFs from patients with OA are more prone to enhance bone formation.
|
|
45. |
- Belibasakis, Georgios N., 1976-
(author)
-
Cellular and molecular responses of periodontal connective tissue cells to Actinobacillus actinomycetemcomitans cytolethal distending toxin
- 2004
-
Doctoral thesis (other academic/artistic)abstract
- Actinobacillus actinomycetemcomitans is present in elevated proportions and numbers in dental bacterial biofilms of patients with localized aggressive periodontitis. This variant of periodontal disease, occurring in adolescents and young adults, is characterized by rapid and severe destruction of the connective tissues and bone supporting the teeth, eventually culminating in tooth loss. The cytolethal distending toxin (Cdt) is a newly discovered bacterial protein toxin, uniquely present in A. actinomycetemcomitans among all known to-date oral bacterial species. The Cdt has the capacity to inhibit mammalian cell growth, but its putative role in the pathogenesis of the disease is unclear. The aim of this in vitro work has been to study the effects of A. actinomycetemcomitans on periodontal connective tissue cell cultures, and to evaluate the possible involvement of its Cdt. A. actinomycetemcomitans inhibited the proliferation of gingival and periodontal ligament fibroblasts, as a result of a combined arrest at the G1 and G2/M phases of the cell cycle. This growth inhibition was non-lethal and the cells remained metabolically active, although their DNA synthesis was reduced. The intoxicated cells exhibited increased size and irregular structure, characterized by distension and elongation. This cellular enlargement occurred in both G1 and G2/M phase arrested cells. The Cdt of A. actinomycetemcomitans was responsible for the observed growth inhibition, as well as the concomitant morphological alterations. The possible induction of inflammatory cytokines related to bone resorption was investigated in response to A. actinomycetemcomitans, and the involvement of Cdt was evaluated. Extensive focus was given to the study of receptor activator of NF-κB ligand (RANKL) expression, a membrane-bound ligand that signals osteoclast progenitors to differentiate and fuse into mature osteoclasts, activating bone resorption. It was demonstrated that A. actinomycetemcomitans induced RANKL mRNA and protein expression in the cells studied, but did not affect the expression of its decoy receptor, osteoprotegerin. This induction was solely attributed to its Cdt, as demonstrated by the use of a cdt-knockout A. actinomycetemcomitans strain, purified recombinant Cdt, and antibodies blocking the Cdt. In addition, this event was not mediated by pro-inflammatory cytokines known to stimulate RANKL. Interleukin-6 mRNA and protein expression were also enhanced by A. actinomycetemcomitans, but Cdt had limited involvement in this enhancement. In conclusion, two distinct mechanisms by which A. actinomycetemcomitans Cdt may be involved in the pathogenesis of localized aggressive periodontitis are proposed. Firstly, the growth arrest of the resident fibroblasts may impair the physiological connective tissue remodelling equilibrium and lead to connective tissue attachment loss. Secondly, the induction of RANKL by these cells, residing in the proximity of the alveolar bone, may locally stimulate osteoclastogenesis and promote alveolar bone resorption. This work also provides further insights to the understanding of Cdt mechanisms of action, contributing to the global characterization of the toxin’s virulence.
|
|
46. |
- Belibasakis, G N, et al.
(author)
-
Cytokine responses of human gingival fibroblasts to Actinobacillus actinomycetemcomitans cytolethal distending toxin.
- 2005
-
In: Cytokine. - : Elsevier BV. - 1043-4666 .- 1096-0023. ; 30:2, s. 56-63
-
Journal article (peer-reviewed)abstract
- Actinobacillus actinomycetemcomitans is implicated in the pathogenesis of localized aggressive periodontitis, and has the capacity to express a cytolethal distending toxin (Cdt). Gingival fibroblasts (GF) are resident cells of the periodontium, which can express several osteolytic cytokines. The aims of this study were a) to investigate the role of Cdt in A. actinomycetemcomitans-induced expression of osteolytic cytokines and their cognate receptors in GF and b) to determine if the previously demonstrated induction of receptor activator of NFkappaB ligand (RANKL) by A. actinomycetemcomitans is mediated by these pro-inflammatory cytokines or by prostaglandin E(2) (PGE(2)). A. actinomycetemcomitans clearly induced interleukin (IL)-6, IL-1beta, and to a minimal extent, tumor necrosis factor (TNF)-alpha mRNA expression. At the protein level, IL-6 but not IL-1beta or TNF-alpha expression was stimulated. The mRNA expression of the different receptor subtypes recognizing IL-6, IL-1beta and TNF-alpha was not affected. A cdt-knockout strain of A. actinomycetemcomitans had similar effects on cytokine and cytokine receptor mRNA expression, compared to its parental wild-type strain. Purified Cdt stimulated IL-6, but not IL-1beta or TNF-alpha protein biosynthesis. Antibodies neutralizing IL-6, IL-1 or TNF-alpha, and the PGE(2) synthesis inhibitor indomethacin, did not affect A. actinomycetemcomitans-induced RANKL expression. In conclusion, a) A. actinomycetemcomitans induces IL-6 production in GF by a mechanism largely independent of its Cdt and b) A. actinomycetemcomitans-induced RANKL expression in GF occurs independently of IL-1, IL-6, TNF-alpha, or PGE(2).
|
|
47. |
- Belibasakis, G N, et al.
(author)
-
The cytolethal distending toxin induces receptor activator of NF-kappaB ligand expression in human gingival fibroblasts and periodontal ligament cells.
- 2005
-
In: Infection and immunity. - 0019-9567 .- 1098-5522. ; 73:1, s. 342-51
-
Journal article (peer-reviewed)abstract
- Actinobacillus actinomycetemcomitans is associated with localized aggressive periodontitis, a disease characterized by rapid loss of the alveolar bone surrounding the teeth. Receptor activator of NF-kappaB Ligand (RANKL) and osteoprotegerin (OPG) are two molecules that regulate osteoclast formation and bone resorption. RANKL induces osteoclast differentiation and activation, whereas OPG blocks this process by acting as a decoy receptor for RANKL. The purpose of this study was to investigate the effect of A. actinomycetemcomitans on the expression of RANKL and OPG in human gingival fibroblasts and periodontal ligament cells. RANKL mRNA expression was induced in both cell types challenged by A. actinomycetemcomitans extract, whereas OPG mRNA expression remained unaffected. Cell surface RANKL protein was also induced by A. actinomycetemcomitans, whereas there was no change in OPG protein secretion. A cytolethal distending toxin (Cdt) gene-knockout strain of A. actinomycetemcomitans did not induce RANKL expression, in contrast to its wild-type strain. Purified Cdt from Haemophilus ducreyi alone, or in combination with extract from the A. actinomycetemcomitans cdt mutant strain, induced RANKL expression. Pretreatment of A. actinomycetemcomitans wild-type extract with Cdt antiserum abolished RANKL expression. In conclusion, A. actinomycetemcomitans induces RANKL expression in periodontal connective tissue cells. Cdt is crucial for this induction and may therefore be involved in the pathological bone resorption during the process of localized aggressive periodontitis.
|
|
48. |
- Bergmann, Berglind, et al.
(author)
-
Antibiotics with Interleukin-15 inhibition reduces joint inflammation and bone erosions but not cartilage destruction in Staphylococcus aureus-induced arthritis.
- 2018
-
In: Infection and immunity. - 1098-5522. ; 86:5
-
Journal article (peer-reviewed)abstract
- Background:Staphylococcus aureus-induced arthritis causes rapid joint destruction, often leading to disabling joint damage despite antibiotics. We have previously shown that IL-15 inhibition without antibiotics is beneficial in S. aureus-induced arthritis. We therefore hypothesized that inhibition of IL-15, in combination with antibiotics, might represent a useful therapy that would both reduce inflammation and joint destruction, but preserve the host's ability to clear the infection.Methods: Female wildtype C57BL/6 mice were intravenously inoculated with the TSST-1-producing LS-1 strain of S. aureus with 0.8x108S. aureus LS-1/mouse. Three days later the treatment was started consisting of cloxacillin followed by flucloxacillin, together with either anti-IL-15 antibodies (aIL-15ab) or control antibodies. Outcomes included survival, weight change, bacterial clearance, and joint damage.Results: The addition of aIL-15ab to antibiotics in S. aureus-induced arthritis reduced synovitis and bone erosions compared to controls. The number of bone-resorbing osteoclasts in the joints was reduced, whereas cartilage destruction was not significantly altered. Importantly, the combination therapy did not adversely affect the clinical outcome of S. aureus-induced arthritis, such as survival, weight change or compromise the host's ability to clear the infection.Conclusions: As the clinical outcome of S. aureus-induced arthritis was not affected, the addition of aIL-15ab to antibiotics ought to be safe. Taken together, the combination of aIL-15ab and antibiotics is a beneficial, but not optimal, treatment of S. aureus-induced arthritis as it reduces synovitis and bone erosions but has a limited effect on cartilage destruction.
|
|
49. |
|
|
50. |
|
|