Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P05231 (interleukin-6)
 23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A substrain of the senescence-accelerated mouse, SAMP6 (senescence-accelerated mouse prone 6), spontaneously develops osteoporosis early in life. Therefore, this strain is a useful animal model for developing new strategies for the treatment of osteoporosis in humans. We succeeded in treating osteoporosis in SAMP6 mice after the onset of this disease, using a newly developed method of bone marrow transplantation (BMT): Allogeneic bone marrow cells obtained from normal mouse strains were directly injected into the bone marrow cavity of irradiated SAMP6 mice (intra-bone marrow BMT [IBM-BMT]). After the treatment with IBM-BMT, hematolymphoid cells were completely reconstituted by donor-derived cells, and bone marrow stromal cells were also found to be of donor origin. The treated SAMP6 mice showed histologically-normal trabecular bone. In addition, bone mineral density and urinary deoxypiridinoline, a hallmark of bone destruction, were normalized. When the message levels of cytokines (tumor necrosis factor alpha, interleukin-6 [IL-6], IL-11, and receptor activator of nuclear factor-kappa B ligand [RANKL]) were examined, IL-11, RANKL (from bone marrow stromal cells), and IL-6 (from osteoclasts), which regulate bone remodeling, were restored to levels similar to those in normal B6 mice. These findings indicate that not only the hemopoietic system but also the bone marrow microenvironment were normalized after IBM-BMT, resulting in an amelioration of the imbalance between bone absorption and formation.
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PMID:Treatment of senile osteoporosis in SAMP6 mice by intra-bone marrow injection of allogeneic bone marrow cells. 1610 54

Increasing data from epidemiological and in vitro studies show that the isoflavonoids, genistein and daidzein, and the flavonols, quercetin and kaempferol, are protective against postmenopausal bone loss. However, the physiological mechanisms for these effects are not well understood. We now report that kaempferol exerts profound antiosteoclastogenic effects by acting on both osteoblasts and osteoclasts. Kaempferol but not quercetin dose-dependently inhibited tumor necrosis factor alpha (TNFalpha)-induced production of the osteoclastogenic cytokines interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1/CCL2) in osteoblasts. The effect on IL-6 was posttranscriptional, whereas kaempferol reduced MCP-1 mRNA levels. In addition, in mouse primary calvarial osteoblasts, kaempferol but not quercetin blocked TNFalpha-induced translocation of the nuclear factor kappaB (NF-kappaB) subunit p65 from the cytoplasm to the nucleus. However, TNFalpha-stimulated intracellular ROS production was unaltered by kaempferol. In RAW264.7 cells, a monocyte/macrophage precursor for osteoclasts, both kaempferol and quercetin dose-dependently inhibited the receptor activator of NF-kappaB ligand (RANKL)-induced immediate-early oncogene c-fos expression at 6 h. After 3-5 days, both flavonols robustly inhibited RANKL-induced expression of the osteoclastic differentiation markers, RANK and calcitonin receptor. Consistent with down regulation of these osteoclastic differentiation markers, both flavonols strongly attenuated the RANKL-induced formation of multinucleated osteoclasts. However, kaempferol was more potent than quercetin in inhibiting RANKL-stimulated effects on RAW264.7 cells. Thus, our data indicate that kaempferol exerts profound antiosteoclastogenic effects by specifically antagonizing TNF receptor family action on bone cells at two distinct levels, by disrupting production of osteoclastogenic cytokines from osteoblasts and attenuating osteoclast precursor cell differentiation.
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PMID:Differential activity of kaempferol and quercetin in attenuating tumor necrosis factor receptor family signaling in bone cells. 1643 28

The physiological effects of the flavone, apigenin on bone cells were studied. We first show that apigenin inhibits tumor necrosis factor alpha (TNFalpha)- and interferon gamma (IFNgamma)-induced secretion of several osteoclastogenic cytokines from MC3T3-E1 mouse calvarial osteoblast cell line. Ligands of the TNF receptor family constitute the most potent osteoclastic cytokines. In MC3T3-E1 cells, apigenin dose-dependently (from 5 to 20 microM) inhibits TNFalpha-induced production of the osteoclastogenic cytokines, IL-6 (interleukin-6), RANTES (regulated upon activation, normal T cell-expressed and -secreted), monocyte chemoattractant protein-1 (MCP-1) and MCP-3. In addition, apigenin inhibits IFNgamma-stimulated secretion of monokines, CXCL-9, and -10 in MC3T3-E1 cells. Next, we show that apigenin strongly inhibits differentiation of 3T3-L1 preadipocytes to adipocytes with attendant inhibition of adipocyte differentiation-induced IL-6, MCP-1, and leptin production. Inhibition of adipogenic differentiation by apigenin could be due to induction of osteogensis as it robustly upregulates mRNA levels of bone morphogenetic protein-6 (BMP-6). Finally, the presence of apigenin inhibited osteoclast differentiation from the RAW 264.7 cell line by reducing receptor activator of nuclear factor kappa ligand (RANKL)-induced expression of tartrate-resistant acid phosphatase (TRAP), RANK, and calcitonin receptor but not CCR1, resulting in the inhibition of multinucleated osteoclast formation. Similarly, apigenin inhibited expression of the osteoclast differentiation markers TRAP, RANK, and c-Fms in osteoclast precursor cells obtained from mouse bone marrow following treatment with RANKL and macrophage colony stimulating factor (MCSF). Furthermore, apigenin induced apoptosis of mature osteoclasts obtained from rabbit long bone and inhibited bone resorption. In all instances, a structurally related compound, flavone had no significant effect. These data suggest that apigenin has multiple effects on all three bone cells that could prevent bone loss in vivo.
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PMID:Attenuation of osteoclastogenesis and osteoclast function by apigenin. 1675 Jan 76

The OPG/RANKL/RANK system regulates osteoclastogenesis. Both cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) and interleukin-6 (IL-6) are reported to induce osteoclast differentiation. The mechanisms underlying these signaling pathways on the OPG/RANKL/RANK system are not fully understood. We herein demonstrate that COX-2 and PGE2 stimulated osteoclastogenesis through inhibition of OPG secretion, stimulation of RANKL production by osteoblasts, and upregulation of RANK expression in osteoclasts. PGE2 also stimulated IL-6 production, and IL-6, in turn, increased PGE2 secretion, COX-2, and EP4/EP2 expression in bone cells. These findings provide evidence of interactive effect of PGE2 and IL-6 signaling pathways in osteoclastogenesis via effect on the OPG/RANKL/RANK system.
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PMID:Interactive effect of interleukin-6 and prostaglandin E2 on osteoclastogenesis via the OPG/RANKL/RANK system. 1683 22

Bone mineral density (BMD) is a primary risk indicator of osteoporotic fractures, which are largely determined by the actions of multiple genes. Genetic linkage studies have seldom explored epistatic interaction of genes for BMD. To evaluate potential genetic interactions for BMD at the femoral neck (FN) we conducted a variance component linkage analysis, to test epistatic effects between the genomic region containing the COL1A1 (collagen type I alpha 1) gene and the genomic regions containing genes regulating osteoclast differentiation (e.g. TNFRSF11A encoding RANK (receptor for activation of nuclear factor kappa B), TNFSF11 encoding RANKL (RANK ligand), IL1A (interleukin-1 alpha), IL6 (interleukin-6), etc) in 3998 Caucasian subjects from 434 pedigrees. We detected significant epistatic interactions between the regions containing COL1A1 with IL6 (p=0.004) and TNFRSF1B encoding TNFR2 (tumor necrosis factor receptor 2) (p=0.003), respectively. In summary, we identified the epistatic effects on BMD between regions containing several prominent candidate genes. Our results suggested that the IL6 and TNFRSF1B genes may regulate FN BMD variation through interactions with the COL1A1 gene, which should be substantiated by other, or population-based, association studies.
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PMID:Epistatic interactions between genomic regions containing the COL1A1 gene and genes regulating osteoclast differentiation may influence femoral neck bone mineral density. 1733 Oct 78

Total hip arthroplasty is one of the most commonly performed and successful elective orthopaedic procedures. However, numerous failure mechanisms limit the long-term success including aseptic osteolysis, aseptic loosening, infection, and implant instability. Aseptic osteolysis and subsequent implant failure occur because of a chronic inflammatory response to implant-derived wear particles. To reduce particulate debris and their consequences, implants have had numerous design modifications including high-molecular-weight polyethylene sockets and noncemented implants that rely on bone ingrowth for fixation. Surgical techniques have improved cementation with the use of medullary plugs, cement guns, lavage of the canal, pressurization, centralization of the stem, and reduction in cement porosity. Despite these advances, aseptic osteolysis continues to limit implant longevity. Numerous proinflammatory cytokines, such as interleukin-1, interleukin-6, tumor necrosis factor-alpha, and prostaglandin E2, have proosteoclastogenic effects in response to implant-derived wear particles. However, none of these cytokines represents a final common pathway for the process of particle-induced osteoclast differentiation and maturation. Recent work has identified the fundamental role of the RANKL-RANK-NF-kappaB pathway not only in osteoclastogenesis but also in the development and function the immune system. Thus, the immune system and skeletal homeostasis may be linked in the process of osteoclastogenesis and osteolysis.
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PMID:The biology of aseptic osteolysis. 1762 Aug 15

Osteoporosis represents a major healthcare burden, affecting approximately 10 million people aged over 50 years in the United States and with another 30 million or more at risk. One of the major contributing factors to osteoporosis is withdrawal of estrogen during menopause in women. Human and animal experiments have implicated pro-inflammatory cytokines as primary mediators of the accelerated bone loss at menopause including interleukin-1, tumor necrosis factor-alpha, and interleukin-6. Increased production of pro-inflammatory cytokines is associated with osteoclastic bone resorption in a number of disease states including rheumatoid arthritis, periodontitis, and multiple myeloma; estrogen withdrawal is associated with increased production of pro-inflammatory cytokines, and exposure of bone cultures to supernatants from activated leukocytes is associated with increased bone resorption. A major advance has been the discovery of RANKL, its receptor RANK, and the endogenous inhibitor osteoprotegerin. The binding of RANKL to RANK is essential for the differentiation and activation of osteoclasts and mediates the actions of essentially all known stimulators of osteoclastic bone resorption. RANKL expression is heightened in post- compared with pre-menopausal women, and this effect is attenuated by estrogen replacement therapy. RANKL is also a therapeutic target; a human antibody with high specificity and affinity to RANKL is currently under clinical evaluation for the treatment of osteoporosis in post-menopausal women and of metastatic bone disease in cancer patients with bone metastasis. Early data are promising.
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PMID:Osteoporosis and inflammation. 1824 May 39

Interleukin-6 (IL-6) is a multifunctional cytokine produced by various cells to regulate hematopoiesis, inflammation, immune responses, and bone homeostasis. IL-6 is also known to modulate the differentiation of osteoblasts and osteoclasts. IL-6 is believed to play a positive regulatory role in osteoclast differentiation by inducing the expression of receptor activator of NF-kappaB ligand (RANKL) on the surface of osteoblasts: RANKL then interacts with RANK expressed on osteoclast progenitors, inducing osteoclast differentiation via the RANK signaling pathway, which involves NF-kappaB, JNK, and p38. In this report, we demonstrate that IL-6 can also directly act on osteoclast progenitors to suppress their differentiation via an inhibition of RANK signaling pathways. IL-6 specifically suppressed RANK-mediated IkappaB degradation and JNK activation. Microarray analysis revealed that costimulation with IL-6 and RANKL up-regulates the transcription of MKP1 and MKP7, which encode enzymes that dephosphorylate JNK, and down-regulates the transcription of Senp2 and Cul4A, which are related to the ubiquitin pathway. Thus, IL-6 directly acts on osteoclast progenitors and suppresses their differentiation by regulating the transcription of specific genes related to MAPK phosphatases and the ubiquitin pathway.
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PMID:Interleukin-6 directly inhibits osteoclast differentiation by suppressing receptor activator of NF-kappaB signaling pathways. 1829 9

The stress and inflammatory responses to burn injury are associated with bone loss. The stress response entails production of large amounts of endogenous glucocorticoids that decrease osteoblasts on the mineralization surface of bone and decreases differentiation of marrow stromal cells into osteoblasts, thereby decreasing the amount of bone formation. Deficiency of osteoblasts also blocks osteoclastogenesis thus leading to low bone turnover and bone loss. The inflammatory response generates cytokines such as interleukin 1-beta and interleukin-6, which normally increase osteoclastogenic bone resorption via stimulation of osteoblast production of RANK ligand. However, in the absence of osteoblasts as a target we postulate that they attack the parathyroid gland chief cells and up-regulate the calcium-sensing receptor. The consequence of this upregulation is the lowering of the circulating calcium necessary to suppress parathyroid hormone production and the development of hypocalcemia and urinary calcium wasting. It is the parathyroid hormone suppression that causes us to postulate acute deficiency of 1,25-dihydroxyvitamin D and the consequence of this for post-burn metabolism could include derepression of the gene that controls renin production, leading to elevated levels of angiotensin II, which can contribute to insulin resistance, as can vitamin D deficiency itself. Moreover, the skin from burned patients cannot synthesize vitamin D normally. Thus vitamin D supplementation is the only means by which to ensure vitamin D sufficiency for burn victims. The proper requirement for vitamin D in acutely burned patients remains unknown.
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PMID:The interaction between burn injury and vitamin D metabolism and consequences for the patient. 1878 7

Recent research into periodontal disease pathology focuses on the role of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in periodontal bone destruction processes. RANKL regulates the differentiation of osteoclast by binding to its specific receptor RANK, while OPG inhibits the differentiation of osteoclasts by binding RANKL and therefore preventing RANKL to bind RANK. The aim of the present study was to investigate the influence of Porphyromonas gingivalis lipopolysaccharide (LPS) and interleukin-6 (IL-6) on RANKL and OPG expression and release in periodontal ligament (PDL) cells. Human PDL cells were stimulated for 48 h with purified P. gingivalis LPS and IL-6. OPG and sRANKL release were assessed by using enzyme-linked immunosorbent assay technique. OPG and RANKL expression was quantitatively measured by using the real-time PCR technique. Whereas P. gingivalis LPS induced sRANKL release, expression was only slightly increased, IL-6 did not show an effect on RANKL expression or release. In conclusion the data demonstrate that stimulation of PDL cells with P. gingivalis LPS leads to an increased release of sRANKL, rather than increased RANKL expression. Through this action, P. gingivalis LPS may exert its biological effect on osteoclast formation and bone resorption.
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PMID:Influence of lipopolysaccharide and interleukin-6 on RANKL and OPG expression and release in human periodontal ligament cells. 1977 43


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