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)

We examined the roles of interleukin-1 Type I receptor (IL-1R1) and tumor necrosis factor receptor 1 (TNFR1) in bone metabolism using mice rendered deficient in these receptors by gene targeting. Sections of decalcified paraffin-embedded calvariae and humeri from 11- to 12-week-old mice deficient in IL-1 Type I receptor (IL-1R1-/-) or TNF receptor 1 (TNFR1-/-) were examined by histomorphometry. Wild-type mice (C57BL/6J x 129/J, WILD) served as controls. Interleukin-6 (IL-6) production in primary osteoblastic and bone marrow stromal cell cultures in response to parathyroid hormone (PTH, 100 ng/ml), IL-1 alpha (10 ng/ml), and TNF-alpha (10 ng/ml) was also examined. IL-1R1-/- and TNFR1-/- mice were viable and appeared phenotypically normal. However, the body weights of the IL-1R1-/- mice were 30% less than WILD, while the TNFR1-/- mice weighed 30% more than WILD mice of equivalent age. Calvariae and humeri of IL-1R1-/- and TNFR1-/- mice were normal with respect to trabecular bone volume, osteoclast number, osteoclast surface, growth plate widths, and cortical thickness. Receptor deficiency was confirmed by determining the ability of PTH, IL-1 alpha, and TNF-alpha to stimulate IL-6 in the media of primary calvaria-derived osteoblastic cell cultures from CD-1 and cytokine receptor-deficient mice. After 24 h of treatment, IL-1 alpha and TNF-alpha did not stimulate IL-6 production in osteoblasts from IL-1R1-/- and TNFR1-/- mice, respectively. In contrast, PTH increased IL-6 levels in the cells from all mice. IL-6 protein levels in bone marrow supernatants and conditioned media from untreated bone marrow stromal cells were undetectable in WILD, IL-1R1-/-, and TNFR1-/- mice. PTH, IL-1 alpha and TNF-alpha increased IL-6 mRNA and protein production in the WILD bone marrow stromal cells. In contrast, PTH and TNF-alpha increased IL-6 mRNA and protein levels in IL-1R1-/- bone marrow stromal cells while IL-1 alpha had no effect. These findings demonstrate that normal bone development in mice can occur in the absence of IL-1R1 or TNFR1 expression.
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PMID:Interleukin-6 expression and histomorphometry of bones from mice deficient in receptors for interleukin-1 or tumor necrosis factor. 891 81

In 70 patients with stage III multiple myeloma (MM) the authors studied spontaneous and lipopolysaccharide-induced production of interleukin-1 (IL-1) and interleukin-6 (IL-6) by blood and bone marrow mononuclear cells, concentration of parathyroid hormone and vitamin D3 in the serum. Bone marrow density was measured at photon absorption (Gambro), in patients treated with osteoprotectors bonefos and oxidevit before and after therapy (3.5-6 month course). It is shown that in MM there is a pathogenetic association between production of osteotropic IL-1, IL-6 and bone demineralization. The cases with reduced concentration of Ca and P ions in the serum (4 and 5.7% of patients, respectively) and increased PTH concentration (7%) suggest the existence of new, extratumor mechanisms of osteolysis. It is found that biphosphonates are optimal osteoprotectors. Bonefos (chlodronat, Lieras, Finland) arrests osteolysis proved by a significant increase of bone marrow density and clinical effect.
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PMID:[The extratumor mechanisms of osteolysis in multiple myeloma and the means for their correction]. 892 74

Interleukin-6 (IL-6) is known to enhance osteoclast recruitment, and thereby bone resorption. Thus, IL-6 has been proposed to mediate hypercalcemia in multiple myeloma and the enhanced osteoclastic activity seen in postmenopausal osteoporosis. We recently reported that the calcium concentration in plasma affects IL-6 secretion from mononuclear blood cells. To investigate the underlying mechanism, we have studied the effect of calcium on IL-6 formation in mononuclear blood cells ex vivo and in vitro. Thirteen healthy volunteers were given 1 g of calcium orally after overnight fasting. Plasma levels of ionized calcium (pCa2+) and serum levels of parathyroid hormone (sPTH) were measured after 2 and 4 h, with all subjects still fasting. After 2 h, pCa2+ was increased and sPTH decreased in all 13 persons. IL-6 secretion ex vivo from mononuclear blood cells drawn 4 h after calcium intake was increased 185% as compared with IL-6 secretion from cells drawn just before calcium intake. In control experiments without calcium intake, there was no alteration in pCa2+ and no effect on IL-6 secretion from mononuclear blood cells. In vitro studies revealed that stimulation of isolated mononuclear blood cells with physiological concentrations of calcium dose-dependently increased IL-6 secretion with an estimated EC50 at 1.2 mM Ca2+. No effect on the IL-6 secretion was seen following treatment of the isolated mononuclear blood cells with PTH or calcitonin. These observations demonstrate that the plasma calcium concentration affects IL-6 secretion from mononuclear blood cells. The in vitro data indicate the involvement of a direct calcium sensing mechanism. These findings might have implications in hypercalcemia and should also be borne in mind when considering the role of cytokines in osteoporosis.
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PMID:Regulation of interleukin-6 secretion from mononuclear blood cells by extracellular calcium. 904 Oct 54

The expression of aromatase, the enzyme responsible for estrogen biosynthesis, has been studied in THP-1 cells of human mononuclear leukemic origin, which exhibit high rates of aromatase activity. These cells have the capacity to differentiate in the presence of vitamin D into cells with osteoclast-like properties. Differentiated cells displayed higher rates of aromatase than undifferentiated cells, and, in both cases, activity was stimulated 10- to 20-fold by dexamethasone. Phorbol esters also increased aromatase activity, but the effect was the same in differentiated as in undifferentiated cells. In a similar fashion to adipose stromal cells, serum potentiated the response to dexamethasone but had no effect on phorbol ester-stimulated activity. By contrast to its action in adipose stromal cells, (Bu)2cAMP markedly inhibited aromatase activity of THP-1 cells, as did factors whose actions are mediated by cAMP, such as PTH and PTH-related peptide. This was true of control cells, as well as of dexamethasone- and phorbol ester-stimulated cells. Previously we have shown that type 1 cytokines as well as tumor necrosis factor-alpha stimulate aromatase activity of adipose stromal cells in the presence of dexamethasone. By contrast, interleukin-6, interleukin-11, and leukemia-inhibitory factor had no effect on aromatase activity of THP-1 cells, whereas tumor necrosis factor-alpha, oncostatin M, and platelet-derived growth factor were slightly inhibitory of aromatase activity. Exon-specific Southern analysis of rapid amplification of cDNA ends-amplified transcripts was employed to examine the distribution of the various 5'-termini of aromatase transcripts. In the control group, most of the clones contained transcripts specific for the proximal promoter II, whereas in dexamethasone-treated cells, most transcripts contained exon I.4. In the phorbol ester-treated cells, a broader spectrum of transcripts was present, with equal proportions of I.4, II, and I.3-containing clones. Additionally, one clone containing a new sequence, exon I.6, was found. This was shown to be located about 1 kb upstream of exon II. By contrast, all clones from cells treated with (Bu)2cAMP contained promoter II-specific sequences. In addition to these transcripts, two clones in the library from the dexamethasone-treated cells contained the sequence previously defined as the brain-specific sequence, 1f. In one of these, the 1f sequence was fused downstream of exon I.4, indicative that its expression likely employed promoter I.4. These results point to similarities and important differences between aromatase expression in THP-1 cells and other cells such as adipose stromal cells, indicative of unique regulatory pathways governing aromatase expression in these cells.
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PMID:Estrogen biosynthesis in THP1 cells is regulated by promoter switching of the aromatase (CYP19) gene. 938 92

We examined sequential changes of bone-resorbing cytokines and bone metabolic markers and the effect of ovarian hormones on bone metabolism during the menstrual cycle in 10 healthy Japanese women, aged 22-43 yr, with normal ovarian function. Serum soluble interleukin-6 receptor (sIL-6R) showed a significant variation; a rise during the early and late follicular periods followed by a fall during the early luteal period (P = 0.0423, P = 0.0334) and an increase during the mid and late luteal periods. There were significant changes in the levels of markers of bone formation: a rise in serum bone-specific alkaline phosphatase (ALP) during the mid and late follicular (P = 0.0265) periods and a fall in serum carboxyl-terminal propeptide of type I procollagen (PICP) during the midluteal period (P = 0.0161). As for the levels of bone resorption markers, urinary type I collagen C-telopeptide breakdown products (CTx) and free deoxypyridinoline (D-Pyr) decreased significantly during the early and midfollicular periods, urinary free D-Pyr and serum pyridinoline cross-linked carboxyl-terminal telopeptide of type I collagen (ICTP) (P = 0.0440) increased significantly during the early luteal period, and urinary CTx, free D-Pyr, and serum ICTP decreased significantly during the late luteal period (P = 0.0170-0.0008). The serum PTH level was significantly higher during the follicular than the luteal period (P = 0.0132). Serum sIL-6R significantly correlated with urinary CTx (r = 0.190, P < 0.05) and serum ALP (r = 0.209, P < 0.05) and serum estradiol with intact osteocalcin (r = 0.309, P < 0.0005) and serum ALP (r = 0.181, P < 0.05). These observations strongly suggest that cyclic variations in the levels of bone formation and resorption markers and of a bone-resorbing cytokine may be modulated by cyclic changes in serum steroid hormones during the menstrual period. In addition, the specific days of biochemical events in the menstrual cycle are crucial for evaluating osteoclastic and osteoblastic activities in pre- and perimenopausal women or in women starting GnRH agonist therapy.
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PMID:Serum soluble interleukin-6 receptor and biochemical markers of bone metabolism show significant variations during the menstrual cycle. 946 35

PTH recruits and activates osteoclasts to cause bone resorption. These actions of PTH are thought to be mediated indirectly via type 1 PTH/PTH-related peptide receptors (PTH1Rs) expressed by adjacent marrow stromal or osteoblastic cells, although some evidence suggests that PTH may act directly on early hematopoietic osteoclast progenitors. We have established clonal, conditionally immortalized, PTH-responsive, bone marrow stromal cell lines from mice that harbor both a transgene encoding a temperature-sensitive mutant of the simian virus 40 large T antigen and deletion of a single allele of the PTH1R gene. Of 60 stromal cell lines isolated, 45 expressed functional PTH1Rs. During coculture with normal murine spleen cells, 5 of 42 such cell lines could support formation of tartrate-resistant acid phosphatase-positive, multinucleated cells (TRAP+ MNCs) in response to 1,25-dihydroxyvitamin D3, but only 2 of these did so in response to PTH. One of these, MS1 cells, expressed numerous cytokines and proteins characteristic of the osteogenic lineage and showed increased production of interleukin-6 in response to PTH. MS1 cells supported dose-dependent induction by rat (r) PTH-(1-34) (0.1-100 nM) of TRAP+ MNCs that expressed calcitonin receptors and formed resorption lacunae on dentine slices. This effect of PTH, which required cell to cell contact between MS1 and spleen cells, was mimicked by coadministration of cAMP analog and phorbol ester but only partially by either agent alone. The carboxyl-terminal fragment rPTH-(53-84) also induced osteoclast-like cell formation, but the maximal effect was only 30% as great as that of rPTH-(1-34). Importantly, rPTH-(1-34) induced TRAP+ MNC formation even when PTH1R-/- osteoclast progenitors (from fetal liver of mice homozygous for ablation of the PTH1R gene) were cocultured with MS1 cells. We conclude that activation of PTH1Rs on cells of the osteoclast lineage is not required for PTH-(1-34)-induced osteoclast formation in the presence of appropriate PTH-responsive marrow stromal cells. MS1 cells provide a useful model for further study of PTH regulation of osteoclastogenesis.
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PMID:Conditionally immortalized murine bone marrow stromal cells mediate parathyroid hormone-dependent osteoclastogenesis in vitro. 952 82

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

A series of 4-phenylthiazole derivatives were synthesized and tested their inhibitory effect on the interleukin-6 secretion stimulated by PTH in osteoblastic cells. SCRC2941-18, 2-amino-4-(4-chlorophenyl)-5-methylthiazole, was found to be the most potent inhibitor in the derivatives. Furthermore, SCRC2941-18 significantly suppressed the bone weight loss in the ovariectomized mice, an osteoporosis model.
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PMID:4-Phenylthiazole derivatives inhibit IL-6 secretion in osteoblastic cells and suppress bone weight loss in ovariectomized mice. 1023 Jun 19

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

Prostaglandins (PG) E1, E2 and F2alpha induce bone resorption in isolated neonatal parietal bone cultures, and an associated increase in interleukin-6 (IL-6) production. Indomethacin had little effect on the response to PGE2, or the relatively non-selective EP receptor agonists 11-deoxy PGE1 and misoprostol, but blocked the effects of PGF2alpha and the F receptor agonist fluprostenol, indicating an indirect action via release of other prostaglandins. It is more likely that there is positive autoregulation of prostaglandins production in this preparation mediated via stimulation of F receptors. The effects of selective EP receptor agonists sulprostone (EP1,3) and 17-phenyl trinor PGE2(EP1), indicated the involvement of EP2 and/or EP4 receptors, which signal via cAMP. The relatively weak increase in IL-6 production by misoprostol (with respect to resorption) suggests that these responses are controlled by different combination of EP2 and EP4 receptors. The PKA activator, forskolin, induced small increases in bone resorption at lower concentrations (50-500 ng/ml) but a reversal of this effect, and inhibition of resorption induced by other stimuli (PTH, PGE2), at higher concentrations (0.5-5 microg/ml). IL-6 production was markedly increased only at the higher concentrations. The inhibitory effect of forskolin may be a calcitonin-mimetic effect. PMA induced both resorption and IL-6 production which were both blocked by indomethacin, indicating a role for PKC in the control of prostaglandin production.
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PMID:Mechanisms involved in prostaglandin-induced increase in bone resorption in neonatal mouse calvaria. 1123 79


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