Interleukin-1 beta and tumor necrosis factor-alpha in normal/infertile men

Cytokines play an important role in intercellular communications. Human sperm contains a wide spectrum of cytokines. such as interleukin-1 beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha). Their effects on semen quality are subject to debate. The aim of this study was to determine concentrations of IL-1beta and TNF-alpha in normal fertile men and in different groups of male infertility in an attempt to clarify the physiology and suggest possible clinical uses. Sixty-six subfertile male patients with varicocele (n = 22). infection of accessory genital glands (n = 14), varicocele plus infection (n = 4), chronic epididymitis (n = 8). post-renal transplantation status (n = 5), idiopathic oligoasthenoteratospermia (n = 9), cryptorchidism (n = 1), and homozygous beta-thalassemia (n = 3) as well as 5 male controls were studied through history, physical examination, spermiograms, plasma basal hormonal levels, and IL-1beta and TNF-alpha levels in seminal fluid. There was no significant statistical difference regarding IL-1beta and TNF-alpha among fertile men and subfertile patients of any cause. 1L-1beta and TNF-alpha were in tight positive correlation (p<.001). Determination of IL-1beta and TNF-alpha does not provide useful information in male routine infertility workup. Nevertheless, a better understanding of these mediators in semen of normal men and infertile patients may contribute to a new approach to the management of male infertility.     

Interleukin-1beta and tumor necrosis factor-alpha, but not interleukin-6, stimulate osteoprotegerin ligand gene expression in human osteoblastic cells.

Recent studies have identified osteoprotegerin ligand (OPG-L) as the essential factor required for osteoclastogenesis, and that the effects are prevented by its soluble receptor, osteoprotegerin (OPG). However, there are limited data at present on the regulation of OPG-L expression in human osteoblastic cells by other cytokines. Because interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and IL-6 all increase osteoclastogenesis, we assessed whether OPG-L mRNA steady-state levels were regulated by these cytokines in human osteoblastic cells. By northern analysis, IL-1beta (5 nmol/L) and TNF-alpha (9 nmol/L) increased OPG-L mRNA steady-state levels by up to two- to three-fold in normal marrow stromal cells (MS), an immortalized marrow stromal cell line (hMS), and the osteosarcoma cell line, MG-63, whereas IL-6 (2 nmol/L, with or without its soluble receptor) had no effect on OPG-L mRNA levels in any of these cells. IL-1beta and TNF-alpha increased OPG-L mRNA steady-state levels in the normal MS cells and the hMS cell line in a time- and dose-dependent fashion by up to 4.1-fold and up to 2.6-fold, respectively. Our data are thus consistent with the hypothesis that the proinflammatory and bone-resorbing cytokines, IL-1beta and TNF-alpha, but not IL-6, may stimulate osteoclastogenesis by inducing the expression of OPG-L.     

Differential effects of tumor necrosis factor-alpha and interleukin-1beta on cell death in human articular chondrocytes

OBJECTIVE: The death of chondrocytes by apoptosis is characteristic of degenerative joint diseases, such as osteoarthritis (OA). Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) have been shown to play an important role in the development of OA. In this study we analyzed the effects of TNF-alpha and IL-1beta on cell death in normal human chondrocytes. METHODS: Normal human chondrocytes were isolated from knee cartilage obtained at autopsy from 30 adult cadaveric donors. The cells were stimulated with TNF-alpha (10 ng/ml) or IL-1beta (5 ng/ml) in the presence or absence of Ro 31-8220 (Ro: a structurally related analog of bisindolylmaleimide that inhibits mitogen-activated protein kinase phosphatase 1 [MKP-1]) (Ro; 10 microM), an MKP-1 inhibitor, which induces apoptosis in chondrocytes. Apoptosis was evaluated by flow cytometry (propidium iodide) and nuclear morphology was evaluated with 4',6'-dianidino-2-phenylindole dihydrochloride. The expressions of caspase-8, -7 and -3 and Bcl-2 were analyzed by Western blot and the activation of caspase-3 and -8 was measured by flow cytometry. Prostaglandin E2 (PGE2) was evaluated by enzyme-linked immunosorbent assay. RESULTS: At 24 h the percentage of apoptotic (hypodiploid) nuclei induced by TNF-alpha+Ro was higher than the level induced by Ro alone. The combination of IL-1beta (5 ng/ml) with Ro did not show a synergistic effect. A morphological analysis demonstrated that treatment with TNF-alpha+Ro resulted in a large number of cells with condensed nuclei and DNA fragmentation. Western blot studies indicated that IL-1beta+Ro did not induce the time-dependent activation of caspase-8, -7 and -3 as seen with TNF-alpha+Ro. As quantified by flow cytometry, TNF-alpha+Ro induced a higher level of caspase-3 and -8 activation than that seen with IL-1beta+Ro. Pre-incubation for 2h with caspase inhibitors for caspase-3, -7, -8 and pan-caspase significantly decreased the hypodiploid DNA peak induced by treatment with TNF-alpha+Ro at 24 h. Indomethacin increased the cell death induced by IL-1beta+Ro; however, apoptosis induced by TNF-alpha+Ro was not modified by indomethacin. CONCLUSIONS: These results confirm that TNF-alpha and IL-1beta regulate apoptosis differently in this human chondrocyte model and that the differing effects of these cytokines are PGE2-independent. Indomethacin potentiates the effect of IL-1 on cell death and this may explain the reported effect of indomethacin on the progression of joint destruction.     

Regulation of tumor necrosis factor-alpha and tumor necrosis factor converting enzyme in human osteoarthritis.

A snake venom-like protease isolated by a differential display screen between normal and osteoarthritis (OA)-affected cartilage (designated as cSVP) has a cDNA sequence identical to tumor necrosis factor (TNF)alpha convertase enzyme (TACE) and belongs to the adamalysin group of proteases. It has unique structural properties and when expressed in baculovirus, cleaves preferentially proTNFalpha to TNFalpha. The OA-affected cartilage has upregulated mRNA for TNFalpha and TACE as compared to normal cartilage. TNFalpha and TACE regulate inflammatory mediators in OA-affected cartilage which can be inhibited by both soluble TNFalpha receptors and inhibitors of TACE. These experiments demonstrate a functional paracrine/autocrine role of TNFalpha in OA-affected cartilage that is modulated by upregulated levels of chondrocyte-derived TACE.     

Cytokines, tumor necrosis factor-alpha and interleukin-1beta, differentially regulate apoptosis in osteoarthritis cultured human chondrocytes

OBJECTIVE: This study addresses the effects of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) on cell death in human chondrocytes. METHODS: Osteoarthritis (OA) human chondrocytes stimulated with Actinomycin-D (ActD) were used as a cellular apoptotic model. Caspase family mRNA expression and protein synthesis were analyzed by the ribonuclease protection assay and Western-blot, respectively. Cell viability and apoptosis were evaluated using the 3-[4,5-dimethylthiazol-2yl] 2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, respectively. Prostaglandin E2 (PGE2) and nitric oxide (NO) were evaluated by enzyme-linked immunosorbent assay (ELISA) and the Griess method, respectively. RESULTS: TNF-alpha and IL-1beta differentially affected the pattern of caspase mRNA expression by human chondrocytes. TNF-alpha induced a gradual increase in caspase-1 and -8 mRNA levels that was not seen with IL-1beta. The time sequence of caspase-3 and -7 inductions by TNF-alpha differs from that induced by IL-1beta. Cell viability was not modified by TNF-alpha or IL-1beta in cultured chondrocytes. Then, we employed ActD as a model to facilitate cell death. Treatment with TNF-alpha and ActD (TNF-alpha/ActD) increased cell death induced by ActD (23%). Treatment with IL-1beta and ActD (IL-1beta/ActD) did not modulate ActD-induced cell death. Similarly, IL-1beta/ActD did not induce an increase in the activation of caspase-3 and -7 and poly (ADP-ribose) polymerase (PARP) cleavage observed by the incubation with TNF-alpha/ActD. These different effects were not due to bcl-2 or mcl-1 levels. Inhibition of PGE2 synthesis by indomethacin increased the cell death induced by IL-1beta/Act-D (59%). An inhibitor of caspase-8 significantly reduced only the TNF-alpha/ActD-induced cell death (58%). CONCLUSION: TNF-alpha and IL-1beta differentially regulate the apoptotic pathway in human chondrocytes. This difference is dependent on PGE2 and caspase-8 levels.     

Rapamycin inhibits release of tumor necrosis factor-alpha from human vascular smooth muscle cells

Neointimal proliferation with plaque formation is the principal cause of coronary artery disease. In the neointima, inflammatory cytokines like tumor necrosis factor-alpha (TNF-alpha) are expressed by vascular smooth muscle cells (VSMCs). These cytokines stimulate proliferation and migration of VSMCs, events that are crucial to neointima formation. Stents, liberating rapamycin, have been shown to reduce neointima formation in human coronary arteries. The purpose of this study was to determine if rapamycin could inhibit the production of TNF-alpha by VSMCs. With institutional review board approval, VSMCs were cultured from saphenous vein segments obtained from five patients. Cells were identified as VSMC by immunostaining for smooth muscle alpha-actin. Cells were exposed to bacterial lipopolysaccharide (LPS), LPS plus rapamycin, or LPS plus isoproterenol for 24 hours. Cells with no treatment served as controls. The culture medium was then removed and analyzed for TNF-alpha. Additionally, the effect of treatment on viability was determined by assay of mitochondrial activity. TNF-alpha released into the culture medium is expressed as pg TNF-alpha/mg cell protein. Statistical analysis was by ANOVA. In control cells, TNF-alpha was undetectable in the culture medium. The addition of LPS (10 microg/mL) increased TNF-alpha release to 4312 +/- 705 pg/mg at 24 hours. The addition of 1 ng/mL rapamycin with LPS reduced TNF-alpha production 50 per cent (P < 0.01 vs LPS alone). A similar reduction of TNF-alpha release was seen with 1 microM isoproterenol. LPS, rapamycin, or isoproterenol did not affect cell viability. These data show that rapamycin effectively inhibits the release of TNF-alpha from VSMCs stimulated with inflammatory mediators like LPS. Rapamycin is as effective as agents that raise intracellular cyclic AMP (e.g., isoproterenol). Therefore, a potential mechanism for the effectiveness of rapamycin-releasing stents is reduction of inflammatory cytokine expression by VSMCs.     

Isoproterenol inhibits bacterial lipopolysaccharide-stimulated release of tumor necrosis factor-alpha from human heart tissue

Recent evidence suggests that inflammatory cytokines, particularly tumor necrosis factor alpha (TNF-alpha), may play a role in heart disease. Elevated plasma levels of the cytokine have been reported in congestive heart failure and severe angina and after myocardial infarction. The exact role of TNF-alpha in heart disease and how production is stimulated and regulated in the heart are current areas of investigation. Regarding regulation of production, isoproterenol elevates cyclic AMP and inhibits TNF-alpha release in macrophages. Therefore we hypothesized that stimulation of beta-adrenergic receptors of the sympathetic nervous system would inhibit release of the cytokine from heart tissue. With Institutional Review Board approval and patient consent atrial tissue was obtained during preparation for cardiac bypass. The tissue was divided into segments, placed in culture medium, and incubated for various times in the presence or absence of lipopolysaccharide (LPS) (20 microg/mL) and/or isoproterenol (1 microM). The medium was removed and analyzed for biologically active TNF-alpha by the L929 cell cytotoxicity assay. Tissue samples were weighed and TNF-alpha release was expressed as pg TNF-alpha/mg tissue. Initially, to determine the time course of release, measurements were made at 2, 5, 10, 15, 30, 60, 120, 180, and 360 minutes after the addition of LPS. Elevated TNF-alpha levels in the culture medium were reliably detected at 360 minutes after exposure to LPS. In atrial tissue obtained from seven patients TNF-alpha released into the culture medium at 360 minutes was 6 +/- 3 pg/mg tissue. In the presence of LPS, levels of the cytokine in the culture medium increased to 604 +/- 233 pg/mg tissue (P < 0.05 vs LPS alone). When isoproterenol and LPS were simultaneously added to the culture medium release of TNF-alpha was reduced by 87 per cent to 82 +/- 40 pg/mg tissue (P < 0.05 vs LPS alone). Our results show that activation of the beta-adrenergic receptor inhibits myocardial production of TNF-alpha. This finding suggests that the sympathetic nervous system inhibits production of the cytokine and that impaired sympathetic function in heart failure may play a role in the elevated levels of TNF-alpha.     

Expression of integrin alpha5beta1 and the relationship to collagen and elastin content in human suprarenal and infrarenal aortas

The infrarenal aorta is especially prone to the development of aneurysm, suggesting an intrinsic structural and molecular difference in different parts of the aorta. Previous study from this laboratory has implicated a potential role of integrin alpha5beta1 in maintaining aortic integrity. The aim of this study was to investigate the expression of integrin alpha5beta1 and the relationship to collagen and elastin content between 2 different aortic segments. In this study, the variation of smooth muscle cells and the localization of integrin alpha5beta1 in the suprarenal and infrarenal aorta tissues removed from organ donors were studied immunohistochemically. The biochemical analysis for matrix proteins and integrin alpha5beta1 protein was done by Western Blot on the corresponding tissues. All interested protein content was normalized to the smooth muscle alpha-actin protein. No significant difference of smooth muscle cells density between the 2 segments of aortas was observed. Integrin alpha5beta1 was localized in the outer layer of all aortic media. The authors found that the ratio of collagen/elastin in infrarenal aortas was significantly increased 2-fold because elastin content in infrarenal aortas decreased 49% as compared with suprarenal aortas. Integrin alpha5beta1 content relative to its specific ligand-collagen-did not differ between these 2 different aortic segments. These results suggest that the infrarenal aorta differed biochemically from the suprarenal aorta. A decrease in infrarenal elastin without a corresponding decrease in collagen and integrin alpha5beta1 may affect the compliance and integrity of the distal aorta. These intrinsic anatomic differences may be important in the susceptibility of the infrarenal aortas to aneurysm formation.     

Lack of plasma interleukin-1 beta or tumor necrosis factor-alpha elevation during unfavorable hemodialysis conditions.

Plasma interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) were determined by ELISA in 17 healthy controls, 23 HD patients, 10 continuous ambulatory peritoneal dialysis patients, and 15 chronic renal failure patients, as well as in 2 HD patients experiencing pyrogenic reactions. Another group of 10 chronic HD patients were dialyzed for 2.5 h, 5 with first-use Cuprophan membranes and 5 with first-use high-flux cellulose triacetate membranes. The mean bacterial and endotoxin concentrations of the dialysate used for HD treatments during the study period were 18,440 +/- 530 CFU/mL (mean +/- SEM) and 976 +/- 205 pg/mL, respectively. Blood specimens were obtained intradialysis and postdialysis for cytokine assay and were incubated to augment cytokine production. There was no difference in plasma IL-1 beta or TNF-alpha concentrations among the healthy controls, continuous ambulatory peritoneal dialysis patients, chronic renal failure patients, or HD patients. Neither cytokine increased significantly during or after HD. Two patients experiencing pyrogenic reactions had plasma TNF-alpha concentrations of 537 and 413 pg/mL, compared with matched controls of 6 and 0 pg/mL. Il-1 beta concentration did not differ from controls. We conclude that: (1) plasma IL-1 beta and TNF-alpha are not chronically elevated in chronic renal failure, continuous ambulatory peritoneal dialysis, or HD patients; (2) HD with new Cuprophan or cellulose triacetate membranes and high concentrations of dialysate endotoxin and bacteria does not cause elevation of circulating IL-1 beta or TNF-alpha; and (3) pyrogenic reactions might be mediated by TNF-alpha.     

The role of tumor necrosis factor-alpha and interleukin-1beta in ischemia-reperfusion injury of the rat small intestine.

BACKGROUND: To determine the role of tumor necrosis factor (TNF) and interleukin (IL)-1 in small-intestinal ischemia-reperfusion (I-R) injury, we investigated the effect of FR 167653, a specific IL-1 and TNF inhibitor, on warm I-R injury of the rat small intestine. MATERIALS AND METHODS: Male rats treated with either saline (NS group) or FR 167653 (FR group) underwent 150 min of warm small-intestinal ischemia by applying a vascular clip at the origin of the superior mesenteric artery. In addition to the survival analyses, we investigated plasma TNF-alpha and endotoxin levels, intestinal tissue TNF-alpha and IL-1beta levels, hematocrit values and the amount of exudates in the intestinal lumen, glutamic aspartate aminotransferase (AST), and histological findings up to 120 min after reperfusion. RESULTS: TNF-alpha and IL-1beta levels in the intestinal tissue, and plasma TNF-alpha and endotoxin levels, were significantly (P < 0.05) reduced in the FR group. Severe mucosal damage on histological findings (120 min after reperfusion) and a large amount of intraluminal exudates (60 min after reperfusion) were shown in the NS group, but these findings were significantly (P < 0.05) ameliorated in the FR group. Serum AST levels in the NS group increased 120 min after reperfusion, but this change was significantly (P<0.05) reduced in the FR group. The 30-day survival rate was 80% in the FR group and 30% in the NS group (P<0.05). CONCLUSIONS: Dual inhibition of TNF and IL-1 effectively alleviated intestinal I-R injury, suggesting the key role of TNF and IL-1 in this pathophysiology.     

The effect of tumor necrosis factor-alpha on human malignant glial cells.

The influence of human recombinant tumor necrosis factor-alpha has been assessed on a cell line (U-251) derived from a human malignant glial tumor. The results of this study demonstrate that tumor necrosis factor-alpha at doses of 50 and 100 ng/ml: 1) did not have cytotoxic or cytostatic effects on the U-251 cell line; 2) significantly increased the intracellular activity of manganese superoxide dismutase but had no effect on copper and zinc superoxide dismutase, catalase, or glutathione peroxidase activity; and 3) did not significantly alter the intracellular or extracellular general protease and collagenase type IV activity of these cells. The resistance of the U-251 cell line to tumor necrosis factor-alpha cytotoxicity may be related in part to the high intrinsic manganese superoxide dismutase activity present in this cell line combined with the ability of this cell line to induce substantial amounts of protective manganese superoxide dismutase activity in response to tumor necrosis factor-alpha.     

Interleukin-1 beta stimulates human mesangial cells to synthesize and release interleukins-6 and -8.

Interleukin-1 beta (IL-1 beta) and tumor necrosis factor (TNF) have been reported to stimulate human mesangial cells (HMC) to proliferate and synthesize eicosanoids. We have examined whether they also induce HMC to release cytokines. In this study we show that both IL-1 and TNF stimulate HMC to release IL-6 and IL-8. Cycling and quiescent HMC were stimulated with various concentrations of either recombinant IL-1 beta or TNF for 1 to 24 hours. IL-1 beta at doses as low as 6 pg/ml stimulated mesangial cells to synthesize mRNA for both IL-6 and IL-8 as assessed by Northern analysis; mRNA for tubulin remained constant, which demonstrated a specific increase in mRNA. Secretion of IL-6 and IL-8 into the culture medium increased (4.5 to 18 ng/ml and 4 to 40 ng/ml, respectively) measured by ELISAs. TNF had similar effects but only in high concentrations (greater than 100 ng/ml). IL-1 beta did not stimulate cells to proliferate, as measured by 3H thymidine incorporation. TNF caused proliferation but only in concentrations over 100 ng/ml. We conclude that IL-1 beta is a potent stimulator of human mesangial cell production of IL-6 and IL-8, both of which may influence injury in nephritis. TNF also stimulates mesangial cells but only in pharmacological doses.     

Interleukin-1 and tumor necrosis factor stimulate the formation of human osteoclastlike cells in vitro

Interleukin-1 (IL-1) alpha and beta and tumor necrosis factor (TNF) alpha and beta are potent stimulators of bone resorption in vitro and in vivo. However, the mechanisms underlying this increased bone resorption have not been clearly defined. Increased bone resorption can result from increased activity of individual osteoclasts, increased numbers of osteoclasts, or both. Therefore, we have used a long-term human marrow culture system that forms multinucleated cells (MNC) with the characteristics of osteoclasts to examine the effects of IL-1 and TNF on osteoclast formation. Human recombinant IL-1 alpha and IL-1 beta, and human recombinant TNF-alpha and TNF-beta stimulated MNC formation from 4- to 60-fold. IL-1 alpha, IL-1 beta, TNF-alpha, and TNF-beta significantly increased MNC formation at very low concentrations: 2.5 x 10(-13) M for IL-1 alpha and IL-1 beta, 10(-11) M for TNF-alpha, and 10(-10) M for TNF-beta In addition, these cytokines enhanced MNC formation in the presence of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], a potent osteotropic factor that stimulates MNC formation by stimulating fusion of mononuclear precursor cells. Simultaneous addition of IL-1 and TNF to the cultures resulted in a synergistic stimulation of MNC formation. These results suggest that: (1) IL-1 and TNF stimulate bone resorption in part by increasing osteoclast formation and (2) an extremely low concentration of these factors can synergistically increase osteoclast formation in the absence of other factors, such as 1,25-(OH)2D3. These data suggest that synergistic interactions among cytokines play an important role in maintaining bone cell activity in normal and pathologic states.     

Early tumor necrosis factor-alpha release from the pulmonary macrophage in lung ischemia-reperfusion injury

OBJECTIVE: Tumor necrosis factor-alpha is a proinflammatory mediator required for the development of experimental lung ischemia-reperfusion injury. The alveolar macrophage is a rich source of tumor necrosis factor-alpha in multiple models of acute lung injury. The present study was undertaken to determine whether the alveolar macrophage is an important source of tumor necrosis factor-alpha in lung ischemia-reperfusion injury and whether suppression of its function protects against injury. METHODS: Left lungs of Long-Evans rats underwent normothermic ischemia for 90 minutes and reperfusion for up to 4 hours. Treated animals received gadolinium chloride, a rare earth metal that inhibits macrophage function. Injury was quantitated via lung tissue neutrophil accumulation (myeloperoxidase content), lung vascular permeability, and bronchoalveolar lavage fluid leukocyte, cytokine, and chemokine content. Separate samples were generated for immunohistochemistry. RESULTS: Tumor necrosis factor-alpha secretion occurred at 15 minutes of reperfusion and was localized to the alveolar macrophage by immunohistochemistry. In gadolinium-treated animals, lung vascular permeability was reduced by 66% at 15 minutes (P <.03) of reperfusion and by 34% at 4 hours (P <.02) of reperfusion. Suppression of macrophage function resulted in a 35% reduction in lung myeloperoxidase content (P <.03) and similar reductions in bronchoalveolar lavage leukocyte accumulation. Tumor necrosis factor-alpha and microphage inflammatory protein-1alpha protein levels were markedly reduced in the bronchoalveolar lavage of gadolinium-treated animals by enzyme-linked immunosorbent assay. CONCLUSIONS: The alveolar macrophage secretes tumor necrosis factor-alpha protein by 15 minutes of reperfusion, which orchestrates the early events that eventually result in lung ischemia-reperfusion injury at 4 hours. Gadolinium pretreatment markedly reduces tumor necrosis factor-alpha elaboration, resulting in significant protection against lung ischemia-reperfusion injury.     

肿瘤坏死因子-α在心肌缺血预处理中的变化及其意义

目的 探讨缺血预处理(IP)对心肌细胞的保护机制.方法 在我院行瓣膜置换手术的患者36例,根据是否采取缺血预处理分为预处理组(20例)和对照组(16例),比较两组炎症因子肿瘤坏死因子(TNF)-α和心肌细胞bcl-2、Caspase-3的变化,观察IP对机体炎症反应的影响.结果 两组患者细胞因子TNF-α均在主动脉开放6 h时达到高峰,术后5 d恢复到术前水平.预处理组开放后6 h、术后1 d、术后2 d TNF-α水平明显低于对照组(P＜0.05).复灌后对照组心肌细胞bcl-2蛋白表达轻度提高,与阻断前比较差异无统计学意义;而复灌后IP组心肌细胞bcl-2蛋白表达明显提高,与阻断前和对照组比较,差异有统计学意义(P＜0.05).对照组复灌后心肌细胞Caspase-3、TNF-α蛋白表达显著提高,IP组心肌细胞中Caspase-3、TNF-α蛋白表达也增高,但比对照组降低,两组间差异有统计学意义(P＜0.05).术后2 d血清TNF-α与bcl-2呈负相关;术后2 d血清及开放后心肌TNF-α与Caspase-3有相关性.结论 缺血预处理可能通过降低机体的炎症反应途径达到心肌细胞保护的效果.     

Heparin and enoxaparin enhance endotoxin-induced tumor necrosis factor-alpha production in human monocytes

OBJECTIVE: To determine whether heparin or the low-molecular-weight heparin enoxaparin alter lipopolysaccharide (LPS)-induced monocyte activation. SUMMARY BACKGROUND DATA: Heparin is widely used in clinical practice to inhibit the coagulation cascade. However, heparin also is a naturally occurring glucosaminoglycan and a pleiotropic immunomodulator that binds to a variety of proteins. LPS is a component of gram-negative bacteria and is thought to be responsible for many of the deleterious effects seen in sepsis. The binding of LPS to CD14 induces a signaling cascade that results in the release of many inflammatory mediators, including tumor necrosis factor-alpha (TNF-alpha). METHODS: Monocytes from healthy volunteers were isolated and cultured in the presence of saline, LPS (10 ng/ml), heparin (0.1 to 1000 microg/ml), or enoxaparin (0.1 to 1000 microg/ml). In blocking experiments, cells were pretreated for 60 minutes with the monoclonal anti-CD14 antibody MY4 (10 microg/ml) or with isotype-matched control IgG2 (10 microg/ml). TNF-alpha values were measured with enzyme-linked immunosorbent assay. Significance was assessed with analysis of variance. RESULTS: Heparin (10 to 1000 microg/ml) and enoxaparin (1000 microg/ml) significantly enhanced LPS-induced TNF-alpha release. Heparin (1000 microg/ml) or enoxaparin (1000 microg/ml) did not produce TNF-alpha in the absence of LPS. Blockade of CD14 abrogated both LPS-induced TNF-alpha release and the effect of heparin or enoxaparin to enhance LPS-induced TNF-alpha release. CONCLUSIONS: The effect of heparin to enhance LPS-induced TNF-alpha release is a biologic phenomenon that reveals a novel and potentially important host defense mechanism during endotoxemia and sepsis. Binding of LPS to CD14 is necessary to induce this phenomenon, suggesting that both heparin and enoxaparin induce signaling mechanisms that are downstream from the initial binding of LPS on CD14.