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)

The effects of a polymethylmetacrylate (PMMA) powder with a diameter between 0.5 and 25 mu m have been studied in vitro on several human osteoblast populations obtained from different sources. Parameters of cell activity such as cell growth, collagen synthesis, osteocalcin, and interleukin-6 (IL-6) production have been evaluated. Cell proliferation and collagen synthesis were inhibited after exposure to bone cement, whereas osteocalcin and IL-6 production were stimulated. These results suggest that PMMA particles could affect osteoblast activity in a way that could contribute, together with other factors, to periprosthetic osteolysis through two different pathways: a reduced periprosthetic bone formation due to the reduced osteoblast proliferation and collagen synthesis, and an osteoblast-mediated activation of osteoclastic bone resorption as suggested by the increased osteocalcin and IL-6 synthesis. In fact, osteocalcin has been demonstrated to have a role in osteoclast recruitment to bone surfaces, and IL-6 is known to induce osteoclastogenesis and to directly stimulate bone resorption.
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PMID:Response of human osteoblasts to polymethylmetacrylate In vitro. 950 63

The effect of 2 months of treatment with the oral growth hormone (GH) secretagogue MK-677 on markers of bone metabolism was determined in healthy obese male subjects. This was a randomized, double-blind, parallel, placebo-controlled study. Twenty-four healthy obese males, 19-49 years of age, with body mass index > 30 kg/m2 were treated with MK-677 (25 mg/day; n = 12) or placebo (n = 12) for 8 weeks. MK-677 increased markers of bone formation; a 23% increase in the carboxy-terminal propeptide of type I procollagen levels and a 28% increase in procollagen III peptide levels were seen with as little as 2 weeks of MK-677 treatment (p < 0.01 and p = 0.001 vs. placebo, respectively) while a 15% increase in serum levels of osteocalcin was not detected until 8 weeks of treatment (p < 0.01 vs. placebo). Markers of bone resorption were induced within 2 weeks of treatment with MK-677; serum levels of the carboxy-terminal cross-linked telopeptide of type I collagen were increased 26% at 8 weeks (p = 0.001 vs. placebo), and urine hydroxyproline/creatinine and calcium/creatinine ratios at 8 weeks were increased by 23% (p < 0.05 vs. placebo) and 46% (p < 0.05 vs placebo), respectively, MK-677 increased serum insulin-like growth factor binding protein-5 (IGFBP-5) by 43-44% after 2-8 weeks of treatment (p < 0.01 vs. placebo). Serum IGFBP-4 was increased by 25% after 2 weeks of treatment (p < 0.001 vs. placebo) but no significant change from baseline was observed after 8 weeks of treatment. Plasma interleukin-6 was not significantly changed by active treatment. In conclusion, short-term treatment of healthy obese male volunteers with the GH secretagogue MK-677 increases markers of both bone resorption and formation. Large increases in serum levels of IGF-1 and IGFBP-5 and a transient increase in serum IGFBP-4 were found. Future long-term studies are needed to investigate if prolonged treatment with MK-677 increases bone mass.
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PMID:Treatment with the oral growth hormone secretagogue MK-677 increases markers of bone formation and bone resorption in obese young males. 966 Oct 80

Several studies were performed in female rats to determine dose and time course changes in mRNA levels for matrix proteins in bone after a single administration of ethanol. As expected, dose-dependent transient increases in blood ethanol were measured. Additionally, there was mild hypocalcemia with no change in immunoreactive parathyroid hormone. Coordinated dose-dependent increases in mRNA for type 1 collagen, osteonectin, and osteocalcin were noted in the proximal tibial metaphysis 6 hr after ethanol was given, with the peak values occurring at a dose of 1.2 g/kg (0.4 ml). Similar increases in mRNA levels for matrix proteins were noted in lumbar vertebrae after ethanol treatment. The changes were specific for bone; ethanol had no effect on mRNA levels for matrix proteins in the uterus or liver, although the mRNA concentrations tended to be reduced in uterus. Message levels for several cytokines implicated in the regulation of bone turnover were also assayed; mRNA levels for transforming growth factor-beta1, transforming growth factor-beta2, interferon-gamma, and interleukin-6 were unchanged at doses ranging from 0.14 to 1.7 g/kg. At the highest dose of ethanol, the mRNA level for tumor necrosis factor-alpha was elevated while the level for insulin-like growth factor-1 was reduced. The time course effects of ethanol (0.4 ml dose) were determined in a separate experiment. Ethanol resulted in a transient increase in mRNA levels for the three bone matrix proteins assayed. However, matrix protein synthesis, as determined by incorporation of 3H-proline into the proximal tibial metaphysis, was not changed after 6 hr. The changes in mRNA levels for the matrix proteins were preceded by brief, transient decreases in mRNA levels for interleukin-1beta, interferon-gamma, and migration inhibitory factor, and followed by a more prolonged decrease in the mRNA level for insulin-like growth factor-1. A subsequent study was performed to determine the effects of repetitive daily treatment with ethanol on rat bone. After 7 days, there were highly significant decreases in the mRNA level for type 1 collagen, as well as decreased bone formation. These results suggest that ethanol may alter bone metabolism by disturbing signal transduction pathways that regulate the expression of genes for bone matrix proteins, skeletal growth factors, and cytokines.
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PMID:Effects of ethanol on gene expression in rat bone: transient dose-dependent changes in mRNA levels for matrix proteins, skeletal growth factors, and cytokines are followed by reductions in bone formation. 980 46

Interleukin-6, synthesized by osteoblasts in response to PTH, stimulates osteoclastogenesis and bone resorption in vitro, and it has been implicated in the pathogenesis of bone loss in several clinical situations. The aim of this study was to evaluate whether serum levels of interleukin-6 were increased in patients with renal osteodystrophy, and to investigate the possible relationships between serum interleukin-6 and PTH levels on one hand, and serum interleukin-6 and bone remodeling markers on the other. Serum interleukin-6 (IL-6), intact PTH, osteocalcin, bone alkaline phosphatase (BAP) and carboxyterminal telopeptide of Type 1 collagen (ICTP) were measured in 86 uremic patients. IL-6 (median [range] 16.5 [1.0-430] pg/ml), PTH (279.8 [11-2004] pg/ml), osteocalcin (143.8 [8-921] ng/ml), BAP (20.9 [6-169] U/I) and ICTP (38.8 [1.5-181.5] microg/l) were higher than normal. IL-6 levels correlated with PTH (r= 0.22, p = 0.04) and with ICTP (r = 0.31, p = 0.004). A stronger correlation was found between PTH and circulating bone remodeling markers (r = 0.66 for osteocalcin, r = 0.56 for BAP, and r = 0.39 for ICTP). The correlation between PTH and IL-6 was stronger in those patients (n = 15) with severe secondary hyperparathyroidism (r= 0,71, p = 0.003). On the other hand, in the group of patients (n = 41) with PTH lower than 250 pg/ml, there was no correlation between IL-6 and PTH, while IL-6 correlated with ICTP (r = 0.44, p = 0.006). Serum IL-6 correlates with ICTP which suggests that it may mediate bone resorption in renal osteodystrophy.
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PMID:Serum interleukin-6 in renal osteodystrophy: relationship with serum PTH and bone remodeling markers. 1007 43

The mass and architecture of the skeletal system adapt, to some extent, to their mechanical environment. A site-specific bone loss of 1-2% is observed in astronauts and in-flight animals after 1 month of spaceflight. Biochemical data of astronauts and histomorphometric analysis of rat bones show that the change in bone mass is a result of decreased bone formation in association with normal (or increased) bone resorption. The changes in bone formation appear to be due in part to decreased osteoblast differentiation, matrix maturation, and mineralization. Recent data show that spaceflight alters the mRNA level for several bone-specific proteins in rat bone, suggesting that the characteristics of osteoblasts are altered during spaceflight. A possible underlying mechanism is that osteoblasts themselves are sensitive to altered gravity levels as suggested by several studies investigating the effect of microgravity on osteoblasts in vitro. Changes in cell and nuclear morphology were observed as well as alterations in the expression of growth factors (interleukin-6 and insulin-like growth factor binding proteins) and matrix proteins (collagen type I and osteocalcin). Taken together, this altered cellular function in combination with differences in local or systemic factors may mediate the effects of spaceflight on bone physiology.
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PMID:The effect of microgravity on morphology and gene expression of osteoblasts in vitro. 1035 54

In the current study, we examined the effects of minocycline on the osteopenia of ovariectomized (OVX) aged rats using the marrow ablation model. This injury induces rapid bone formation followed by bone resorption in the marrow cavity. Old female rats were randomly divided into five groups: sham, OVX, OVX + minocycline (5-15 mg/day, orally), OVX + 17 beta-estradiol (25 micrograms/day, subcutaneously), and OVX + both agents. Rats were OVX, treated with minocycline and/or estrogen, followed by marrow ablation. Bone samples were collected 16 days post-marrow ablation. X-ray radiography of bones operated on showed that treatment of OVX old rats with minocycline increased bone mass in diaphyseal region. Diaphyseal bone mineral density (BMD) was measured by DEXA scan. Diaphyseal BMD of OVX rats was increased 17-25% by treatment with 5-15 mg of minocycline or 17 beta-estradiol. The effects of minocycline and estrogen treatments on the expression of osteoblast and osteoclast markers were also examined. Northern and dot blot analysis of RNA samples showed that treatment of OVX aged rats with minocycline increased the expression of type I collagen (COL I) (49%) and decreased that of interleukin-6 (IL-6) (31%). In contrast, estrogen treatment decreased the expression of interleukin-6 (IL-6) (39%), carbonic anhydrase II (CA II) (36%), and osteopontin (OP) (37%). Neither minocycline nor 17 beta-estradiol had an effect on the expression of osteocalcin (OC) and alkaline phosphatase (AP). To elucidate the mechanism by which minocycline prevented the loss of bone in OVX aged rats, we examined the colony-formation potential of bone marrow stromal cells in ex vivo cultures. Minocycline stimulated the colony-forming efficiency of marrow stromal cells derived from old animals. We have therefore concluded that the modest increase in BMD noted in OVX aged rats, in response to minocycline treatment, may be due to a change in bone remodeling that favors bone formation; and the anabolic effect of minocycline is likely due to its effect on the expression of COL I and/or the metabolism of osteoprogenitor cells.
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PMID:Treatment of osteoporosis with MMP inhibitors. 1041 30

Human growth hormone with 22,000 Dal (22K-hGH) stimulates proliferation and differentiation of osteoblasts as well as production of interleukin-6 in vitro and bone formation and remodeling in vivo. To investigate whether hGH isoform with 20Kd (20K-hGH), which accounts for 10% of circulating hGH, elicits similar metabolic effects on skeletal tissues, we studied the biological effects of 20K-hGH in cultured human osteoblast-like cells (HOB). HOB were obtained from trabecular bone explants and cultured in alpha-MEM supplemented with 10% FCS. In subconfluent cultures, 22K- and 20K-hGH stimulated [3H]thymidine incorporation by 62 +/- 27% and 63 +/- 23%, respectively (mean +/- SD, n=8, P>0.1). In confluent cultures, 22K- and 20K-hGH increased alkaline phosphatase activity by 38 +/- 23% and 41 +/- 23% (P>0.1), respectively, and increased the osteocalcin concentration in the presence of 10(-9) M 1,25-(OH)2D3 by 50% and 47% (P>0.1), respectively. Furthermore, both hGHs doubled the interleukin-6 (IL-6) concentration in the conditioned medium. RT-PCR analysis revealed that 22K- and 20K- hGH increased IL-6 gene expression 2.2 +/- 0.6 and 2.4 +/- 0.7 -fold, respectively. In summary, we have demonstrated that 20K-hGH elicits equipotent anabolic effects on HOB and stimulates to the same extent the production of IL-6, a cytokine which initiates osteoclastogenesis. These in vitro findings suggest that 22K- and 20K-hGH may equipotently stimulate bone remodeling and elicit anabolic effects on skeletal tissue when administered in vivo.
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PMID:Osteo-anabolic effects of human growth hormone with 22K- and 20K Daltons on human osteoblast-like cells. 1042 76

In this study we evaluated the role of cytokines and insulin-like growth factor (IGF) system in mediating the skeletal changes that occur during puberty by determining the relationship between serum levels of cytokines and IGF system components vs. 1) bone formation and resorption parameters in serum and urine, 2) bone density, and 3) metacarpal bone indexes in 65 pubertal girls. Lumbar bone mineral density and metacarpal width increased significantly both between Tanner stages (TS) II and III and between TS III and IV, whereas metacarpal length and serum levels of stimulatory IGF system components increased significantly only between TS II and III. Biochemical markers of bone turnover were significantly less in TS IV girls than in TS II and III girls. In general, serum levels of IGF system components showed a significant positive correlation to bone density in TS II and III girls, whereas bone resorption markers corrected for creatinine showed a significant negative correlation to bone density in TS III and IV girls. Serum levels of IGF system components showed a significant positive correlation to serum osteocalcin levels as well as metacarpal width in TS II girls, whereas urinary levels of bone resorption markers showed a significant negative correlation to metacarpal width in TS IV girls. Serum levels of interleukin-6 were decreased during late puberty and were negatively correlated with bone density in TS III and IV girls. Our data are consistent with a model in which the sex steroid hormone-induced increase in the IGF system leads to an increase in longitudinal growth and periosteal bone expansion, whereas the sex steroid hormone-induced reduction in bone turnover (possibly via cytokines) leads to an increase in cortical thickness via endosteal regulation.
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PMID:Studies on the potential mediators of skeletal changes occurring during puberty in girls. 1044 84

A genetic contribution to bone mass determination was first described in the early 70s. Elucidation of gene contribution to this has since been attempted through studies analyzing associations between bone mass acquisition and/or maintenance and polymorphic variations of several genes. The first to be described was the vitamin D receptor gene (VDR), initially claimed to contribute to almost 75% of the genetic variation in bone mineral density (BMD) in twin and general population studies. Not all of the studies published to date conclude that a clear relationship exists between polymorphic VDR alleles and BMD, and the molecular basis for the VDR gene polymorphisms influence on bone mineralization has not yet been clarified. Since then, other genes with a significant role in bone metabolism such as estradiol receptor, collagen type 1alpha1, TGF-beta1, interleukin-6, calcitonin receptor, alpha2-HS-glycoprotein, osteocalcin, calcium-sensing receptor, interleukin-1 receptor antagonist, beta3-adrenergic receptor, apolipoprotein E, PTH, IGF-I and glucocorticoid receptor have been analyzed. Some polymorphic variations in these genes have been associated in some works with significant differences in BMD, with even more significant contributions when associations of different gene polymorphisms were analyzed. Again, the molecular basis for the contribution of these alleles to bone mass determination has not yet been described. A different approach has been attempted by linkage analysis of loci involved in bone density in pedigrees with low BMD using BMD as a quantitative trait. Recent results do not confirm, in these families, any association with any of the previously reported genes, but rather with other as yet unidentified genes. The genetic contribution to mild variations in the general population, as a result of environmental and endogenous individual influences, probably differs completely from that providing a pathologic BMD.
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PMID:Genetic determinants of bone mass. 1046 Oct 16

Periodontal ligament cells may play an important role in the successful regeneration of the periodontium. We investigated the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2), one of the most potent growth factors that stimulates osteoblast differentiation and bone formation, on cell growth and osteoblastic differentiation in human periodontal ligament cells (HPLC) isolated from four adult patients. rhBMP-2 induced no significant changes in cell growth in any of the HPLCs. rhBMP-2 at concentrations over 50 ng/mL significantly stimulated alkaline phosphatase (ALPase) activity and parathyroid hormone (PTH)-dependent 3', 5'-cyclic adenosine monophosphate accumulation, which are early markers of osteoblast differentiation, in the HPLCs. rhBMP-2 (500 ng/mL) also slightly enhanced the level of PTH/PTH-related peptide receptor mRNA expression in these cells. While interleukin-1 beta enhanced ALPase activity stimulated with rhBMP-2, tumor necrosis factor-alpha inhibited the rhBMP-2-stimulated activity. Interleukin-6 induced no significant changes in ALPase activity stimulated with rhBMP-2. Although HPLCs, whether treated with rhBMP-2 or not, could not produce measurable amounts of osteocalcin, which is a marker of more mature osteoblasts, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] induced osteocalcin mRNA expression and protein synthesis in these cells. rhBMP-2 inhibited 1,25(OH)2D3-induced osteocalcin synthesis in HPLCs at both the mRNA and protein levels. These results suggest that rhBMP-2 provides an anabolic effect on periodontal regeneration by stimulation of osteoblastic differentiation in human periodontal ligament cells, and that this stimulatory effect is differentially modulated by inflammatory cytokines during the course of periodontal regeneration.
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PMID:Recombinant human bone morphogenetic protein-2 stimulates osteoblastic differentiation in cells isolated from human periodontal ligament. 1052 Sep 67


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