UNIPROT:P05231 - FACTA Search

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Query: UNIPROT:P05231 (interleukin-6)
23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The induction of interleukin-6 (IL-6), using a proinflammatory cytokine (tumor necrosis factor-alpha), was studied in a human osteoblast cell line (MG-63) in relation to p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappaB transcription factor. When added to MG-63 cells, tumor necrosis factor-alpha (TNF-alpha) had a stimulatory effect on the production of IL-6, and this elevation was significantly reduced by SB203580, a specific p38 MAPK inhibitor. In addition, the stimulation of IL-6 release was also reduced by pyrrolidine dithiocarbamate (PDTC) or NF-kappaB SN50, which has been reported to be a potent NF-kappaB inhibitor. Both the NF-kappaB inhibitors in the presence of SB203580 had a more inhibitory effect on IL-6 release. In this study, TNF-alpha stimulated NF-kappaB binding affinity as well as p38 MAP kinase activation, leading to the release of IL-6. However, the specific inhibitor of p38 MAPK, SB203580, had no effect on TNF-alpha-induced NF-kappaB activation and both NF-kappaB inhibitors failed to reduce the p38 MAPK activation in the TNF-alpha-stimulated osteoblasts. In addition, inhibition of p38 MAPK partially, but significantly, impaired TNF-alpha-regulated release of osteocalcin, an important differentiation marker in osteoblasts. These results strongly suggest that both p38 MAPK and NF-kappaB are required in TNF-alpha-induced IL-6 synthesis and that these two TNF-alpha-activated pathways can be primarily dissociated. Furthermore, p38 MAPK may play a significant role in differentiation in MG-63 cells.
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PMID:The p38 mitogen-activated protein kinase pathway regulates interleukin-6 synthesis in response to tumor necrosis factor in osteoblasts. 1116 42

Interleukin-13 (IL-13) inhibits cell proliferation and stimulates interleukin-6 (IL-6) formation in isolated human osteoblasts (hOBs). Because the related cytokine, interleukin-4 (IL-4), is known to exert effects similar to IL-13 in other tissues, and because IL-4 has been implicated as a regulator of bone metabolism, we compared the effects of IL-13 and IL-4 on cell proliferation, IL-6 synthesis, the expression of osteoblastic phenotypic markers in hOB cultures. Also, the receptor proteins mediating these effects in hOBs have been partly characterized. IL-4 and IL-13 dose-dependently inhibited [(3)H]-thymidine incorporation into the DNA of human osteoblasts and stimulated secretion of IL-6 into culture supernatants. IL-13 and IL-4 also increased the mRNA levels of IL-6, as measured by RNAse protection assay. Furthermore, IL-13 and IL-4 dose-dependently enhanced alkaline phosphatase (ALP) activity, but did not affect osteocalcin or collagen type I synthesis. IL-4 was tenfold more potent than IL-13 in inducing both ALP activity and IL-6 secretion, whereas the cytokines were equipotent as inhibitors of cell proliferation. The expression of mRNA for receptor subunits previously implicated in IL-4 and IL-13 signaling was investigated by reverse transcriptase-polymerase chain reaction. IL-13R, IL-13Ralpha, and IL-4Ralpha mRNA were repeatedly detected in hOBs, whereas mRNA for IL-2Rgamma(C) was not detected. Receptor-blocking antibodies to IL-4Ralpha inhibited the induction of IL-6 formation by both IL-4 and IL-13, indicating that both cytokines utilize this receptor subunit in signaling. However, the antibodies did not affect the IL-4/-13-induced inhibition of [(3)H]-thymidine incorporation or the stimulation of alkaline phosphatase (ALP), suggesting that IL-4Ralpha does not mediate these effects of IL-4/-13 in hOBs. We conclude that the cytokines IL-13 and IL-4, through sharing of receptor components, induce similar effects on hOBs, causing inhibition of cell proliferation, stimulation of IL-6, and enhanced ALP activity.
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PMID:Interleukin (IL)-13 and IL-4 inhibit proliferation and stimulate IL-6 formation in human osteoblasts: evidence for involvement of receptor subunits IL-13R, IL-13Ralpha, and IL-4Ralpha. 1124 56

We have investigated the expression and synthesis of potential bone-resorbing cytokines, interleukin-6 (IL-6), interleukin-1 (IL-1), and tumor necrosis factor (TNF) in rheumatoid arthritic (RA) and osteoarthritic (OA) bone, two common diseases which are associated with bone loss. Primary human osteoblast (hOB) cultures were established to determine the temporal mRNA expression of IL-6, IL-1 (alpha and beta), and TNF (alpha and beta) in relation to osteoblast growth and phenotypic genes. IL-6 mRNA levels were found to be significantly higher (P < 0.04) in both OA hOB (17 patients) and RA hOB (10 patients) compared to normal (NO) hOB (9 patients) and reached five-fold increases in OA hOB and 13-fold increases in RA hOB. Maximal levels of IL-6 are expressed at Day 21 which corresponds to the mineralization stage reflected by decreasing collagen I (alpha(1)), osteopontin, bone sialoprotein, alkaline phosphatase mRNA levels, while osteocalcin (OC) mRNA levels increased. IL-6 protein levels also were significantly higher (P < 0.05) in OA hOB and RA hOB compared to NO hOB. These increases were not attributable to sex or age of the donor bone. Neither the mRNA encoding IL-1(alpha and beta) and TNF(alpha and beta) nor the related proteins were detectable. These results indicate that differentiated OA hOB and RA hOB within a bone tissue-like matrix constitutively express and secrete high levels of IL-6. This inherent property suggests that these osteoblasts, independent of local inflammatory parameters, can contribute to enhanced recruitment of osteoclast progenitors and thereby bone resorption.
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PMID:Increased mRNA expression and protein secretion of interleukin-6 in primary human osteoblasts differentiated in vitro from rheumatoid and osteoarthritic bone. 1132 21

Central hyposomatotropism and hypothyroidism have been inferred in long-stay intensive care patients. Pronounced hypoandrogenism presumably also contributes to the catabolic state of critical illness. Accordingly, the present study appraises the mechanism(s) of failure of the gonadotropic axis in prolonged critically ill men by assessing the effects of pulsatile GnRH treatment in this unique clinical context. To this end, 15 critically ill men (mean +/- SD age, 67 +/- 12 yr; intensive care unit stay, 25 +/- 9 days) participated, with baseline values compared with those of 50 age- and BMI-matched healthy men. Subjects were randomly allocated to 5 days of placebo or pulsatile iv GnRH administration (0.1 microg/kg every 90 min). LH, GH, and TSH secretion was quantified by deconvolution analysis of serum hormone concentration-time series obtained by sampling every 20 min from 2100-0600 h at baseline and on nights 1 and 5 of treatment. Serum concentrations of gonadal and adrenal steroids, T(4), T(3), insulin-like growth factor I (IGF), and IGF-binding proteins as well as circulating levels of cytokines and selected metabolic markers were measured. During prolonged critical illness, pulsatile LH secretion and mean LH concentrations (1.8 +/- 2.2 vs. 6.0 +/- 2.2 IU/L) were low in the face of extremely low circulating total testosterone (0.27 +/- 0.18 vs. 12.7 +/- 4.07 nmol/L; P < 0.0001) and relatively low estradiol (E(2); 58.3 +/- 51.9 vs. 85.7 +/- 18.6 pmol/L; P = 0.009) and sex hormone-binding globulin (39.1 +/- 11.7 vs. 48.6 +/- 27.8 nmol/L; P = 0.01). The molar ratio of E(2)/T was elevated 37-fold in ill men (P < 0.0001) and correlated negatively with the mean serum LH concentrations (r = -0.82; P = 0.0002). Pulsatile GH and TSH secretion were suppressed (P < or = 0.0004), as were mean serum IGF-I, IGF-binding protein-3, and acid-labile subunit concentrations; thyroid hormone levels; and dehydroepiandrosterone sulfate. Morning cortisol was within the normal range. Serum interleukin-1beta concentrations were normal, whereas interleukin-6 and tumor necrosis factor-alpha were elevated. Serum tumor necrosis factor-alpha was positively correlated with the molar E(2)/testosterone ratio and with type 1 procollagen; the latter was elevated, whereas osteocalcin was decreased. Ureagenesis and breakdown of bone were increased. C-Reactive protein and white blood cell counts were elevated; serum lactate levels were normal. Intermittent iv GnRH administration increased pulsatile LH secretion compared with placebo by an increment of +8.1 +/- 8.1 IU/L at 24 h (P = 0.001). This increase was only partially maintained after 5 days of treatment. GnRH pulses transiently increased serum testosterone by +174% on day 2 (P = 0.05), whereas all other endocrine parameters remained unaltered. GnRH tended to increase type 1 procollagen (P = 0.06), but did not change serum osteocalcin levels or bone breakdown. Ureagenesis was suppressed (P < 0.0001), and white blood cell count (P = 0.0001), C-reactive protein (P = 0.03), and lactate level (P = 0.01) were increased by GnRH compared with placebo infusions. In conclusion, hypogonadotropic hypogonadism in prolonged critically ill men is only partially overcome with exogenous iv GnRH pulses, pointing to combined hypothalamic-pituitary-gonadal origins of the profound hypoandrogenism evident in this context. In view of concomitant central hyposomatotropism and hypothyroidism, evaluating the effectiveness of pulsatile GnRH intervention together with GH and TSH secretagogues will be important.
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PMID:Five-day pulsatile gonadotropin-releasing hormone administration unveils combined hypothalamic-pituitary-gonadal defects underlying profound hypoandrogenism in men with prolonged critical illness. 1144 92

Bisphosphonates are potent inhibitors of osteoclastic activity and reduce the disease-related skeletal complications when they are used in combination with chemotherapy in patients with multiple myeloma (MM). Pamidronate also inhibits apoptosis of primary osteoblastic cells and probably induces apoptosis on human MM cells and osteoclasts. It has been reported that interferon-alpha (IFN-alpha) decreases bone resorption and that low doses of IFN-alpha result in a significant increase in serum osteocalcin (OSC). The aim of this study was to determine the effects of pamidronate treatment on biochemical markers of bone resorption [cross-linked N-telopeptides of type I collagen (NTx)], bone formation [bone alkaline phosphatase (BAP) and OSC], disease activity [beta2-microglobulin, CRP, paraprotein], and interleukin-6 (IL-6) in patients with MM in plateau phase under IFN-alpha maintenance. The above parameters were evaluated in 28 patients (13 M, 15 F, median age 70 years) during maintenance treatment, before the addition of pamidronate and after 1, 3, 6, 9, 12, and 14 months of the combined therapy. The addition of pamidronate to maintenance treatment resulted in a significant reduction of NTx, IL-6, beta2-microglobulin, CRP from the 3rd month and paraprotein from the 6th month of treatment, whereas BAP and OSC were significantly increased from the 6th month. These changes continued during the 14-month follow-up of the combined treatment. Multivariate analysis showed a significant negative correlation between changes of BAP and OSC and the patients' age. The greater increase of the bone formation markers was observed in younger patients. These results suggest that, in addition to the inhibition of osteoclastic activity, pamidronate in combination with IFN-alpha was shown to induce bone formation in patients with MM in the plateau phase.
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PMID:Pamidronate increases markers of bone formation in patients with multiple myeloma in plateau phase under interferon-alpha treatment. 1168 35

Interleukin-6 (IL-6) has been attributed to induction of osteoclastogenic-precursor cell proliferation and maturation. Estrogens suppress IL-6 production in stromal/osteoblastic cells in vitro. Conversely, estrogen withdrawal is associated with increased IL-6 production. IL-6 is therefore thought to be an important mediator of the increased bone resorption after menopause. However, evidence supporting a rise in the expression of IL-6 or the IL-6 receptor in human bone tissue with menopause is still lacking. To address this question, we established a 5'-nuclease assay to quantitate the expression of human IL-6 and the gp80 subunit of the IL-6 receptor in human bone samples. The number of mRNA copies was normalized to the number of copies of beta actin mRNA. Osteocalcin expression served as an independent control. The study population consisted of 169 women (mean age 52.4 +/- 11.6 years) who underwent surgery for early breast cancer. Serum IL-6 was measured by enzyme-linked immunosorbent assay, serum crosslaps as a marker of bone resorption were measured by electrochemiluminescent assay, and serum osteocalcin was measured by chemoluminescence assays. RNA expression of osteocalcin in bone tissue from early postmenopausal women was higher compared with premenopausal women. Local expression was positively associated with circulating osteocalcin and crosslaps concentrations. Postmenopausal women also had higher circulating IL-6 concentrations. In contrast, bone samples from postmenopausal women lacked an increased expression of either IL-6 or gp80 compared with bone samples from premenopausal women. In conclusion, we failed to detect local increases in IL-6 or IL-6 receptor expression in human bone tissue with menopause. If direct changes in the IL-6 system in bone tissue are involved in postmenopausal bone loss, these changes appear to be below the detection limit of our assay system.
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PMID:Expression of Interleukin-6 (IL-6) and IL-6 receptor mRNA in human bone samples from pre- and postmenopausal women. 1179 88

Weightlessness induces bone loss in humans and animal models. We employed the NASA-approved Rotating Wall Vessel bioreactor (RWV) to develop osteoblast-like cell cultures under microgravity and evaluate osteoblast phenotype and cell function. Rat osteoblast-like cell line (ROS.SMER#14) was grown in the RWV at a calculated gravity of 0.008g. For comparison, aliquots of cells were grown in conventional tissue culture dishes or in Non-Rotating Wall Vessels (N-RWV) maintained at unit gravity. In RWV, osteoblasts showed high levels of alkaline phosphatase expression and activity, and elevated expression of osteopontin, osteocalcin, and bone morphogenetic protein 4 (BMP-4). In contrast, the expression of osteonectin, bone sialoprotein II and BMP-2 were unaltered compared to cells in conventional culture conditions. These observations are consistent with a marked osteoblast phenotype. However, we observed that in RWV osteoblasts showed reduced proliferation. Furthermore, DNA nucleosome-size fragmentation was revealed both morphologically, by in situ staining with the Thymine-Adenine binding dye bis-benzimide, and electrophoretically, by DNA laddering. Surprisingly, no p53, nor bcl-2/bax, nor caspase 8 pathways were activated by microgravity, therefore the intracellular cascade leading to programmed cell death remains to be elucidated. Finally, consistent with an osteoclast-stimulating effect by microgravity, osteoblasts cultured in RWV showed upregulation of interleukin-6 (IL-6) mRNA, and IL-6 proved to be active at stimulating osteoclast formation and resorbing activity in vitro. We conclude that under microgravity, reduced osteoblast life span and enhanced IL-6 expression may result in inefficient osteoblast- and increased osteoclast-activity, respectively, thus potentially contributing to bone loss in individuals subjected to weightlessness.
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PMID:Characterization of the osteoblast-like cell phenotype under microgravity conditions in the NASA-approved Rotating Wall Vessel bioreactor (RWV). 1189 60

Plasma osteocalcin, a marker of osteoblastic activity, decreases after major abdominal and gynaecological surgery. Increased cortisol secretion and other hormonal and inflammatory components of the peri-operative stress response may play a role in mediating this response. We assessed the effects of three different anaesthetic techniques on peri-operative osteocalcin concentrations. Thirty-six female patients undergoing elective total hip replacement were randomly assigned to receive propofol, propofol plus 'three-in-one' block or etomidate as part of a general anaesthetic technique. We measured plasma osteocalcin and serum cortisol, bone specific alkaline phosphatase, interleukin-6, plasma epinephrine, norepinephrine, plasma glucose and cystatin C concentrations for up to 3 days after surgery. Etomidate successfully inhibited the cortisol response to surgery but plasma osteocalcin declined in all patients. This was accompanied by increased plasma catecholamines, interleukin-6 and glucose concentrations, and decreased cystatin C-values. Inhibition of the cortisol response to surgery failed to prevent a decrease in plasma osteocalcin concentrations after surgery, suggesting that other factors such as cytokines or catecholamines may play a significant role.
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PMID:Osteocalcin and the hormonal, inflammatory and metabolic response to major orthopaedic surgery. 1193 88

Anabolic hormones, mechanical loading, and the obese protein leptin play separate roles in maintaining bone mass. We have previously shown that leptin, as well as its receptor, are expressed by normal human osteoblasts. Consequently, we have investigated how leptin affects proliferation, differentiation, and apoptosis of human osteoblasts. Iliac crest osteoblasts, incubated with either leptin (100 ng/ml), calcitriol (1,25(OH)(2)D(3); 10(-9) M) or 1-84 human parathyroid hormone (PTH; 10(-8) M), were cultured for 35 consecutive days and assayed for expression of various differentiation-related marker genes (as estimated by RT-PCR), de novo collagen synthesis, proliferation, in vitro mineralization, and osteoclast signaling. The effects of leptin on protection against retinoic acid (RA; 10(-7) M) induced apoptosis, as well as transition into preosteocytes, were also tested. Leptin exposure enhanced cell proliferation and collagen synthesis over both control condition and PTH exposure. Leptin inhibited in vitro calcified nodule production after 1-2 weeks in culture, however, subsequent to 4-5 weeks, leptin significantly stimulated mineralization. The mineralization profile throughout the entire incubation period was almost undistinguishable from the one induced by PTH. In comparison, 1,25(OH)(2)D(3) generally reduced proliferation and collagen production rates, whereas mineralization was markedly enhanced. Leptin exposure (at 2 and 5 weeks) significantly enhanced the expression of TGFbeta, IGF-I, collagen-Ialpha, ALP, and osteocalcin mRNA. Leptin also protected against RA-induced apoptosis, as estimated by soluble DNA fractions and DNA laddering patterns subsequent to 10 days of culture. The expression profiles of Bax-alpha and Bcl-2 mRNAs indicated that leptin per se significantly protected against apoptosis throughout the entire incubation period. Furthermore, the osteoblast marker OSF-2 was diminished, whereas the CD44 osteocyte marker gene expression was stimulated, indicating a transition into preosteocytes. In terms of osteoclastic signaling, leptin significantly augmented the mRNA levels of both interleukin-6 (IL-6) and osteoprotegerin (OPG). In summary, continuous leptin exposure of iliac crest osteoblasts, promotes collagen synthesis, cell differentiation and in vitro mineralization, as well as cell survival and transition into preosteocytes. Leptin may also facilitate osteoblastic signaling to the osteoclast.
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PMID:Leptin stimulates human osteoblastic cell proliferation, de novo collagen synthesis, and mineralization: Impact on differentiation markers, apoptosis, and osteoclastic signaling. 1196 22

Technetium 99m-2-methoxyisobutil-isonitrile (Tc-99m-MIBI), also called sestaMIBI, has been used successfully to detect malignant tumours at diagnosis. Recently, it has been proposed as a safe and effective tracer in patients with multiple myeloma (MM). The purpose of this study was to demonstrate the value of the Tc-99m-MIBI uptake in disease detection and to assess the correlation between the uptake of this scintigraphy agent and prognostic factors in newly diagnosed MM patients. Thirty-five untreated patients were enrolled in the study. Tc-99m-MIBI scanning was performed in 33 patients after intravenous injection of 7.4 MBq/kg. Whole-body anterior and posterior scans were obtained after 30 min, 60 min, 2 and 4 h. The correlation between known prognostic factors of MM and the intensity of Tc-99m-MIBI uptake was assessed. Our results showed seven patients with an intensity score of I0, 12 patients with I1, eight patients with I2 and six patients with a score of I3. There was a positive correlation between Tc-99m-MIBI intensity and C-reactive protein (CRP; r=0.506, P < 0.01), erythrocyte sedimentation rate (ESR; r=0.368, P < 0.05), beta2- microglobulin (beta2M; r=0.749, P < 0.001), interleukin-6 (IL-6; r=0.823, P < 0.001), soluble Interleukin-6 receptor (sIL-6r; r=0.806, P < 0.001), serum calcium (r=0.578, P < 0.001) and bone alkaline phosphatase (BAP; r=0.472, P < 0.01). An inverse correlation was found between Tc-99m-MIBI intensity and osteocalcin (OC) and type I procollagen carboxyterminal propeptide (PICP). In conclusion, the results of this study suggest that more extensive disease activity, as determined by high levels of CRP, beta2M, IL-6 and sIL-6r correlated with a higher uptake of the radiotracer.
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PMID:Correlation between the uptake of Tc-99m-sestaMIBI and prognostic factors in patients with multiple myeloma. 1206 79

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