肿瘤坏死因子a促进人冠状动脉内皮细胞的凋亡

背景：研究表明冠状动脉内皮细胞凋亡参与了动脉粥样硬化的发生、发展过程。 目的：观察肿瘤坏死因子a对人冠状动脉内皮细胞的诱导损伤作用。 方法：取对数生长期的人冠状动脉内皮细胞c-12221,分别加入含0(对照),200,400,600 mg/L肿瘤坏死因子a的培养液,采用MTT检测细胞增殖率变化,Hoechst 33258/PI双染观察凋亡细胞形态变化,Annexin V-FITC和PI双染流式检测细胞凋亡率变化,高内涵活细胞成像系统检测细胞线粒体膜电位变化。 结果与结论：肿瘤坏死因子a呈剂量依赖性抑制人冠状动脉内皮细胞的增殖。Hoechst 33258/PI染色观察可见凋亡细胞染色质凝集、细胞核碎裂成碎片等典型细胞凋亡的特征性变化,不同质量浓度肿瘤坏死因子a组细胞凋亡率高于对照组(P < 0.05),线粒体膜电位低于对照组(P < 0.05),且呈剂量依赖性。表明肿瘤坏死因子a呈剂量依赖性促进人冠状动脉内皮细胞凋亡,抑制其增殖,作用机制与线粒体凋亡通路有关。     

Interleukin-1 alpha and tumor necrosis factor alpha cause placental injury in the rat.

Bacterial endotoxins (LPS) causes placental injury and fetal demise in pregnant animals. Because several biological effects of LPS are mediated by interleukin-1 (IL-1) and tumor necrosis factor (TNF), the hypothesis that these cytokines could cause placental injury similar to that seen in LPS-treated pregnant rats was tested. On day 12 of gestation, rats were injected intraperitoneally with saline, LPS, native or heat-inactivated (HI) rHIL 1 alpha, or rH-TNF alpha. Seven days later, grossly abnormal implantation sites and fetal demise were observed in rats injected with rHIL-1, rHTNF, or LPS but not in those injected with saline or HI-cytokines. Necrosis of placental, decidual, and fetal tissues was observed in cytokine-treated animals. The necrosis was more severe in LPS-treated rats, in which no fetal remains were identifiable. These data suggest that IL-1 and TNF may play a role in the fetoplacental injury observed in LPS-treated pregnant rats.     

Tumor necrosis factor alpha upregulates human microglial cell production of interleukin-10 in vitro.

Interleukin (IL)-10 appears to play an important regulatory role in the systemic inflammatory response; however, production of IL-10 within the human central nervous system has not been described. Using cultures of human fetal microglial cells, the resident macrophages of the brain, we investigated the production and regulation of bioactive IL-10. Lipopolysaccharide stimulated acute release of tumor necrosis factor (TNF)-alpha (peak by 8 h) and delayed production of IL-10 (over a 48-h period) in microglial cell cultures. Treatment of microglial cell cultures with TNF-alpha and IL-6 resulted in a dose-dependent release of IL-10. These cytokines also induced expression of IL-10 mRNA. Treatment of microglial cell cultures with IL-10 markedly inhibited TNF-alpha and IL-6 production. These findings suggest that during inflammation within the brain, acute release of TNF-alpha and IL-6 by activated microglia could promote subsequent release of IL-10, which functions to minimize the potential neurotoxic effects of proinflammatory cytokines.     

Tumor necrosis factor alpha,interleukin 1 alpha,and interleukin 6 mRNA expressed by human astrocytoma cells after infection by three different strains ofToxoplasma gondii

The role of cytokines in the pathogenesis of toxoplasmosis remains unknown to a large extent, especially in the case of reactivation that occurs in immunocompromised patients. To assess the importance of tumor necrosis factor alpha (TNFα), interleukin 1 alpha (IL1 α), and interleukin 6 (IL6), we studied the expression of these three cytokines by human astrocytoma cells after infection by three different strains ofToxoplasma gondii. The virulent RH strain, the intermediate 76K strain, and the cystogenic Prugniaud strain did not induce significantly different levels of expression of the cytokine messenger RNAs when the cytokines were studied at 1, 3, 6, and 24 h after parasitic infection. These results could indicate that infection byT. gondii strains of different virulence do not involve strong differences in TNFα, IL1α, or IL6 expression by human astrocytoma cells.     

Tumor necrosis factor alpha stimulates killing of Mycobacterium tuberculosis by human neutrophils

The ability of human neutrophils to aid in defense against pulmonary infection with Mycobacterium tuberculosis is controversial. In this study, we have shown that neutrophils respond to and phagocytose M. tuberculosis in human lesions. Neutrophils from healthy individuals were able to kill significant fractions of an inoculum of M. tuberculosis within 1 h of phagocytosis, and this ability was enhanced by tumor necrosis factor alpha but not by gamma interferon. The mycobactericidal mechanism was nonoxidative, as inhibitors of reactive oxygen or reactive nitrogen intermediates did not interfere with killing. However, the mycobactericidal mechanism was associated with increased exposure of intracellular M. tuberculosis to neutrophil defensins. In vitro, human neutrophil peptides 1 to 3 were not able to kill the bacilli even at much higher levels. These studies support the concept that human neutrophils are directly involved in defense against infection with M. tuberculosis.     

Tumor necrosis factor reduces lifespan of human endothelial cells in vitro

Tumor necrosis factor (TNF) is known to regulate the proliferation and function of vascular endothelial cells (ECs). We have examined the effects of TNF on the growth and aging of human ECs of different origins and compared them with those in human normal diploid fibroblasts. The results obtained were as follows: (1) TNF reduces the growth rate and in vitro life span of ECs in both dose- and treatment length-dependent fashions; (2) ECs are significantly more sensitive to TNF than fibroblasts; and (3) the life span shortening effect of TNF on ECs increases as a function of in vitro cell age. These results suggest that the aging of ECs is modified by TNF exposure.     

Tumor necrosis factor receptors in lymphoid tissues and lymphomas. Source and site of action of tumor necrosis factor alpha.

Tumor necrosis factor alpha (TNF alpha), which is produced by germinal center dendritic reticulum cells (DRC) in lymphoid tissue, plays a regulatory role in a local immune response. However no information is available on the nature and location of cells responding to this cytokine. Thus TNF receptor distribution was investigated in situ by immunohistochemistry using monoclonal antibodies directed against the p75 and p55 receptor proteins. Receptor expression was unique and restricted to the lymphoreticular tissue. The p75 receptor was found on activated lymphocytes and interdigitating reticulum cells of the T-cell area, whereas the p55 receptor was confined to the germinal center DRCs, which are the main site of TNF alpha production. The two receptor proteins were expressed on distinct cell populations of the lymphoid system and no coexpression was observed. Preliminary results indicate that TNF receptor (TNFR) expression is regulated; Upregulation of TNFR proteins was found in reactive hyperplasia together with increased TNF alpha expression. In lymphoproliferative disorders, expression of the p75 receptor and TNF alpha was found mainly in high-grade malignant non-Hodgkin lymphomas. In summary, TNF alpha produced by germinal center DRCs might regulate an in vivo immune response through autocrine and paracrine pathways. Thus TNF alpha might signal, through the distinct TNFR proteins, the p55 and p75 receptor, which are expressed on different cell types in lymphoid tissue.     

Tumor necrosis factor alpha and the anemia associated with murine malaria.

The anemia associated with malaria is complex, and multiple factors contribute to its severity. An increased destruction and a decreased production of erythrocytes are involved; however, the mechanisms responsible remain unclear. Tumor necrosis factor alpha (TNF-alpha), released by macrophages in response to infection, is thought to play a role through its ability to inhibit erythropoiesis. In these studies we have examined erythropoiesis in mice infected with Plasmodium berghei and in mice infused with recombinant TNF-alpha via implanted osmotic pumps. In both groups of mice there was (i) a reduction of pluripotent stem cells in the bone marrow and a concomitant increase in the spleen, (ii) a reduction of erythroid progenitor cells, and (iii) a reduced incorporation of 59Fe into erythrocytes. When P. berghei-infected mice were given antiserum against recombinant murine TNF, erythropoiesis was partially restored. There was a significant increase in bone marrow stem cells, erythroid progenitor cells, and 59Fe incorporation into erythrocytes in P. berghei-infected mice that had been treated with anti-TNF. How TNF may act, directly or indirectly, to inhibit erythropoiesis is not yet clear. These results demonstrate that TNF mediates, in part, the anemia associated with malaria.     

Tumor necrosis factor alpha and interleukin 1 alpha enhance lipopolysaccharide-mediated bovine endothelial cell injury.

Alveolar macrophages (AMs) are important in the host response to aerogenous pulmonary bacterial infections, such as Pasteurella haemolytica-induced pneumonia in cattle. Previous work has shown that AMs enhance P. haemolytica-mediated pulmonary endothelial cell (EC) damage in vitro. The purpose of this study was to determine the mechanism of AM-enhanced EC damage using an in vitro AM-EC coculture system consisting of AMs cultured on culture plate insert membranes and ECs in the underlying chamber. The addition of lipopolysaccharide (LPS) to the culture plate insert chamber resulted in EC damage indicated by 51Cr release, which was enhanced in the presence of AMs. To determine the role of AM-secreted cytokines, recombinant human interleukin 1 alpha (IL-1) or tumor necrosis factor alpha (TNF) was added to ECs simultaneously with varying concentrations of LPS. Although TNF and IL-1 alone had only marginal toxic effects on ECs, the simultaneous treatment of TNF or IL-1 with LPS greatly increased the LPS cytotoxic effect on ECs. In addition, IL-1 receptor antagonist eliminated the IL-1 enhancement of LPS-mediated EC toxicity. These results suggest that macrophage-secreted cytokines synergistically enhance LPS-mediated pulmonary EC damage.     

Tumor necrosis factor alpha regulates in vivo intrapulmonary expression of ICAM-1.

Lung injury following deposition of IgG immune complexes is neutrophil-dependent and requires both tumor necrosis factor alpha (TNF alpha) and CD18. In the current studies, we have evaluated the relationship between TNF alpha and expression of intracellular adhesion molecule-1 (ICAM-1) in vitro and in vivo. In both rat pulmonary artery endothelial cells and human umbilical vein endothelial cells, TNF alpha induced an early (within 60 minutes) increase in ICAM-1 expression, followed by a peak at 6 to 8 hours, with relatively stable expression at 24 hours. Expression of E-selectin did not show the early phase (within 60 minutes) of up-regulation, peaked at 4 hours, and then declined thereafter. Using a radioimmunochemical assay in vivo, it was demonstrated that intrapulmonary deposition of IgG immune complexes caused a progressive increase in ICAM-1 expression in lung over an 8-hour period. In animals pretreated with antibody to TNF alpha, the intrapulmonary expression of ICAM-1 was significantly reduced. These results were confirmed by immunoperoxidase analysis of lung tissue. It was also shown that airway instillation of TNF alpha caused up-regulation of ICAM-1 in lung. These data support the concept that deposition of IgG immune complexes in lung induces intrapulmonary up-regulation of ICAM-1 in a manner that is TNF alpha-dependent.     

Detection of perforin and tumour necrosis factor alpha mRNA expressing cells in sclerosing lymphocytic lobulitis of the breast.

The contribution of a cellular immune response to tissue destruction in sclerosing lymphocytic lobulitis of the breast is not well understood. In this study, comparison of one case with two age matched control cases showed an increased frequency of activated perforin mRNA expressing cells at the site of tissue destruction in lobulitis. Along with the detection of tumour necrosis factor alpha (TNF alpha) mRNA expressing cells in the infiltrates, the striking association of perforin expressing activated cytotoxic cells with remaining gland parenchyma and the high level of perforin mRNA suggests activation of cytotoxic cells in situ. These findings are evidence that cell mediated cytotoxicity plays a significant role in the destruction of mammary gland tissue in sclerosing lymphocytic lobulitis.     

Tumor necrosis factor alpha in children with sickle cell disease in stable condition.

Tumor necrosis factor alpha (TNF-alpha) is known to induce wasting in humans and animals. This study was undertaken to determine TNF-alpha concentrations in children with sickle cell disease (SCD) and whether high TNF-alpha levels are more likely to be present in children with growth deficits, infection, or pain crisis. Tumor necrosis factor alpha was measured using enzyme immunoassay in 143 blood samples obtained from 101 children. Mean TNF-alpha levels were higher in patients (50 pg/mL) than in 21 control children (19 pg/mL) and in 26 laboratory employees (20 pg/mL). During the follow-up period, 35%, 38%, and 28% of children with SCD had infection, pain crisis, or a blood transfusion, respectively. Mean TNF-alpha concentrations were higher in children who had an infection than in those who did not. No significant effect of pain crisis or blood transfusion was observed. Tumor necrosis factor alpha concentrations were above normal (> 40 pg/mL) in 15% of controls, 34% of children with SCD, and 52% of children with SCD who had an infection and 33% of those who did not. A higher percentage of children who had elevated TNF-alpha levels had weight (46% versus 31%) or height (50% versus 28.6%) deficits than children who had normal TNF-alpha levels. These results indicate that most children with SCD in stable condition have normal TNF-alpha concentrations and that those with high TNF-alpha levels are more likely to have growth deficits.     

Interleukin-6 and tumour necrosis factor alpha are expressed by keratinocytes but not by Langerhans cells.

The presence of human cytokines was examined in parallel skin biopsies and epidermal single cell preparations obtained from normal individuals. Using biotin-avidin-peroxidase and immunofluorescence techniques and antibodies against recombinant cytokines, a granular intercellular/membrane-associated staining for interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF alpha), but not IL-1 alpha or beta, was observed. An epidermal cytoplasmic staining pattern was also detected, which was most pronounced using the anti-rIL-6 antiserum. In the epidermal single cell preparations, membrane-associated staining was detected for both IL-6 and TNF alpha. Double staining revealed that CD1-positive Langerhans cells (LC) failed to express any of the examined cytokines. In vitro binding of rIL-6 or rTNF alpha to skin sections and epidermal single cell preparations indicated that the cell surface-associated IL-6 and TNF alpha originally demonstrated on keratinocytes were truly membrane-bound. Finally, co-cultivation of epidermal cells with an IL-6 responsive cell line, B9, and testing of epidermal cell supernatants in this assay, indicated that the in vivo membrane-bound IL-6 had biological activity.     

Low-affinity receptors for tumour necrosis factor-alpha, interferon-gamma and granulocyte-macrophage colony-stimulating factor are expressed on human placental syncytiotrophoblast.

Scatchard binding analysis has been employed to characterize expression of low-affinity receptors for tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) by isolated human placental syncytiotrophoblast microvillous plasma membrane (StMPM) vesicles. Trophoblastic receptors for the c-kit ligand (stem cell factor) could not be identified using the same methods. No high-affinity receptors could be detected for GM-CSF or IFN-gamma, but a minority of high-affinity TNF-alpha receptors were identified. Cross-inhibition studies indicated the low-affinity receptors to be specific for each cytokine rather than to be non-specific cytokine-binding factors. Only relatively high-affinity receptors for TNF-alpha and IFN-gamma could be detected on the BeWo human choriocarcinoma cytotrophoblast cell line, whereas receptor affinity for GM-CSF was similar to that on syncytiotrophoblast. Immunohistochemical staining has confirmed expression of IFN-gamma receptor by syncytiotrophoblast: in contrast, staining for the established TNF-R1 and TNF-R2 receptors was associated mainly with placental vascular endothelium. These low-affinity cytokine receptors could reflect unique biological responses of foetal syncytiotrophoblast in the presence of local concentrations of maternal cytokine.     

Tumor necrosis factor alpha enhances the adenoviral transduction of CD34+ hematopoietic progenitor cells

The purpose of this study was to improve the transduction efficiency of adenoviral vectors (Ad) in human CD34+ hematopoietic progenitor cells. CD34+ cells from cord blood or mobilized peripheral blood were incubated with tumor necrosis factor-alpha (TNF-alpha). After removal of free TNF-alpha, the cells were infected with an Ad encoding green fluorescent protein (GFP). One day later, viable cells were counted and analyzed for GFP and CD34 by flow cytometry. To visualize vectoral trafficking, CD34+ cells were incubated with fluorophore-conjugated Ad. Plating efficiencies of hematopoietic progenitors before and after transduction were evaluated by methylcellulose assays. Pretreatment with TNF-alpha increased the transduction efficiency more than twofold (39.2% versus 15.5%) in a dose-dependent manner and strongly improved the survival of GFP-positive CD34+ cells. Time course experiments showed that TNF-alpha incubation times as short as 10 minutes were still effective. Neutralizing antibodies to TNF receptor II and RGD peptides diminished the TNF-alpha-dependent increase in transduction efficiency. No TNF-alpha-dependent increase in adenoviral receptors (coxsackie-adenovirus receptor, alphavbeta3-integrin) occurred. Analysis of viral binding demonstrated a significantly higher incidence of local concentrations of Ad along the cell surface (caps) in virus-positive cells of the TNF-alpha-treated group. Plating efficiency, especially the formation of granulocyte-macrophage colony forming units, was enhanced by TNF-alpha pretreatment. We conclude that brief incubation with TNF-alpha before addition of the Ad significantly increased the Ad transduction efficiency in CD34+ cells, and improved post-transduction survival of progenitors of the granulocyte-macrophage lineage. This finding correlates with increased Ad capping at the cell surface and suggests an alteration of Ad trafficking.     

Recombinant human tumor necrosis factor alpha promotes adherence of Staphylococcus aureus to cultured human endothelial cells.

Tumor necrosis factor (TNF), a potent inflammatory mediator secreted by monocytes during inflammation, was shown to significantly increase the adherence of Staphylococcus aureus to cultured human umbilical vein endothelial cells in vitro. The stimulatory effect of TNF was dose dependent and was bimodal with respect to time; bacterial adhesion peaked after 4 and 16 h of stimulation with recombinant human TNF-alpha. The ability of TNF-alpha to augment staphylococcal adherence to endothelial cells was contingent upon the presence of plasma factors. Thus, the complex interaction among cytokines (such as TNF), plasma factor(s), and the endothelium serves to modulate bacterial adherence to endothelial cells.     

Concentrations of immunoreactive human tumor necrosis factor alpha produced by human mononuclear cells in vitro

The concentrations of tumor necrosis factor (TNF) produced by human peripheral blood mononuclear cells (MNC) were measured using a radioimmunoassay (RIA) for human TNF. This was developed using a rabbit antiserum against human recombinant TNF (Hu rTNF), and Hu rTNF labeled with Na125I by a modification of the chloramine T method. This RIA does not detect human lymphotoxin, interleukin-1 alpha or beta, interleukin 2, interleukin 6, interferon alpha or gamma, granulocyte-macrophage-colony stimulating factor, and C5a des arg. A good correlation (r = 0.89) was found between the RIA and the cytolytic bioassay for TNF. The sensitivity of the RIA is between 3 and 78 pg/ml (median 11 pg/ml). The mean concentration of TNF in 24-h culture supernatants of human MNC exposed to different concentrations of lipopolysaccharide (LPS) was found to increase in dose-dependent fashion and then level off between 50 and 100 ng/ml. The concentrations of IL-1 beta and alpha detected by specific RIAs in these supernatants were between 0.2 and 19 ng/ml and 0.04 and 1 ng/ml, respectively. The amount of TNF produced by human MNC in vitro was determined in a cohort of 50 normal volunteers. Without exogenous stimuli, TNF concentrations were almost always below the detection limit; with 0.5 ng/ml LPS, the median concentration of TNF was 2 ng/ml, and with PHA the median was 3.8 ng/ml. In cultures performed in the presence of indomethacin significantly (p less than 0.005) more TNF was produced. Using this RIA, we could detect TNF in the circulation of mice injected with Hu rTNF. When plasma samples of patients with febrile illnesses were added directly to the RIA, TNF was not detectable, with the exception of patients with malaria. These studies demonstrate the range and sensitivity of LPS-induced and mitogen-induced production of immunoreactive TNF by human MNC in vitro without interference of similar cytokines in bioassays.     

Tumor necrosis factor alpha increases human cerebral endothelial cell Gb3 and sensitivity to Shiga toxin

Hemolytic uremic syndrome (HUS) is associated with intestinal infection by enterohemorrhagic Escherichia coli strains that produce Shiga toxins. Globotriaosylceramide (Gb3) is the functional receptor for Shiga toxin, and tumor necrosis factor alpha (TNF-alpha) upregulates Gb3 in both human macrovascular umbilical vein endothelial cells and human microvascular brain endothelial cells. TNF-alpha treatment enhanced Shiga toxin binding and sensitivity to toxin. This upregulation was specific for Gb3 species containing normal fatty acids (NFA). Central nervous system (CNS) pathology in HUS could involve cytokine-stimulated elevation of endothelial NFA-Gb3 levels. Differential expression of Gb3 species may be a critical determinant of Shiga toxin toxicity and of CNS involvement in HUS.