Stimulation with thromboxane A2 (TXA2) receptor agonist enhances ICAM-1, VCAM-1 or ELAM-1 expression by human vascular endothelial cells

A previous study reported that intercellular adhesion molecule-1 (ICAM-1) expression by human vascular endothelial cells (HUVEC) is augmented by intracellular signal transmission mainly through the protein kinase C (PKC) system stimulated by TXA₂ receptors. In the present study, we show that a TXA₂ receptor agonist, U46619, augments the expression of not only ICAM-1, but also vascular cell adhesion molecule-1 (VCAM-1) or endothelial leucocyte adhesion molecule-1 (ELAM-1) in HUVEC both at protein and mRNA levels. Pretreatment with SQ29,548 (a TXA₂ receptor antagonist) or PKC inhibitors greatly diminished the extent of U46619-induced mRNA accumulation and surface expression of the adhesion molecules. An inhibitor of nuclear factor κB (NF-κB) activation, PDTC, diminishes U46619-induced VCAM-1 mRNA accumulation. NAC, which inhibits NF-κB and activation protein 1 (AP-1) binding activity, inhibits the expression of ICAM-1 or ELAM-1 at protein and mRNA levels. These findings suggest that ICAM-1 or ELAM-1 expression of HUVEC stimulated via TXA₂ receptors is augmented by induction of NF-κB and AP-1 binding activity through the PKC system, and that VCAM-1 expression is augmented by induction of NF-κB binding activity.     

Effects of anti-rheumatic gold salts on NF-kappa B mobilization and tumour necrosis factor-alpha (TNF-alpha)-induced neutrophil-dependent cytotoxicity for human endothelial cells

We have previously shown that the gold-containing disease-modifying anti-rheumatic drugs, auranofin (AF) and gold sodium aurothiomalate (GSTM) reduce human umbilical vein endothelial cell (HUVEC) adhesion molecule expression and neutrophil (PMN) adherence. AF diminishes E-selectin and intercellular adhesion molecule-1 (ICAM-1) on cytokine-activated HUVEC, while GSTM decreases only E-selectin. Since tight adhesion is critical for PMN to damage EC, we tested whether these drugs modulated human PMN-mediated injury to TNF-alpha-activated HUVEC in vitro (as measured by 51Cr release). Here we show that TNF-alpha caused a prominent PMN-mediated cytotoxicity that was dose-dependently reduced when AF and GSTM were added to the assay system. We also found that a potent inhibitor of NF-kappaB, pyrrolidine dithiocarbamate (PDTC) in a dose-dependent manner impaired TNF-alpha-induced cytotoxicity, indicating a role of NF-kappaB activation in cytokine-induced endothelial injury. To examine the effects of AF and GSTM on TNF-alpha-induced NF-kappaB activation this was measured in HUVEC nuclear extracts by an electrophoretic mobility shift assay. AF, but not GSTM, decreased TNF-alpha-induced NF-kappaB activation in HUVEC. Thus, in this in vitro model of vasculitis, AF and GSTM dose dependently reduced TNF-alpha-mediated neutrophil-dependent cytotoxicity for HUVEC, and AF, but not GSTM, inhibited NF-kappaB mobilization, thereby providing possible mechanisms for effects of AF and GSTM.     

血管紧张素Ⅱ对单核细胞趋化蛋白及基因调节的意义

目的　观察血管紧张素Ⅱ (AⅡ )对人单核细胞株THP 1分泌单核细胞趋化因子 (MCP 1)蛋白及基因的影响。方法　利用ELISA法检测AⅡ作用后THP 1分泌MCP 1的表达 ,利用RT PCR检测其MCP 1的mRNA表达。结果　 4种不同浓度的AⅡ (1× 10 -6、1× 10 -7、1× 10 -8、1× 10 -9mol/L)刺激THP 12 4h后 ,MCP 1蛋白及mRNA的表达明显增加 ,且呈浓度依赖性。结论　AⅡ可调节THP 1细胞MCP 1基因及蛋白的表达 ,AⅡ可通过致炎症作用参与动脉粥样硬化的发病过程     

高浓度的糖刺激人肾小球内皮细胞表达单核细胞趋化蛋白-1的影响

目的 :探讨高浓度的糖对培养的人肾小球内皮细胞 (HUGEC)表达单核细胞趋化蛋白 1(MCP 1)的影响 ,以及HUGEC的条件培养基对单核细胞 (MC)的趋化作用及抗MCP 1抗体对MC迁移的影响。方法 :采用原位杂交技术和细胞ELISA法 ,观察MCP 1的表达 ;用改良的Boyden小室微孔滤膜法 ,测定高浓度的糖刺激HUGEC后的条件培养基 ,对MC的趋化作用 ,以及抗MCP 1抗体对MC迁移的影响。结果 :(1)在低浓度的糖(含 5 .5mmol/LD 葡萄糖 )条件下培养的HUGECMCP 1mRNA呈弱表达。高浓度的糖 (含 2 5mmol/LD 葡萄糖 )刺激后 ,8h即出现MCP 1表达增强 ,于 16h达高峰。(2 )高浓度的糖刺激HUGEC后的条件培养基 ,对MC具有明显的趋化作用 ;抗MCP 1抗体可抑制其作用。结论 :在高浓度的糖诱导下 ,人HUGECMCP 1的表达增强 ,其条件培养基对MC具有趋化作用 ,从而可能招引单核细胞迁入内皮下间隙。     

Infection of human endothelial cells with Staphylococcus aureus induces the production of monocyte chemotactic protein-1 (MCP-1) and monocyte chemotaxis.

Bacterial infection coincides with migration of leucocytes from the circulation into the bacterium-infected tissue. Recently, we have shown that endothelial cells, upon binding and ingestion of Staphylococcus aureus, exhibit proinflammatory properties including procoagulant activity and increased intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression on the cell surface, resulting in hyperadhesiveness, mainly for monocytes. The enhanced extravasation of monocytes to bacterium-infected sites is facilitated by the local production of chemotactic factors. From another study we concluded that the locally produced chemokine MCP-1 is important in the recruitment of monocytes to the peritoneal cavity in a model of bacterial peritonitis. In the present study we investigated whether cultured human endothelial cells after infection with bacteria produce and release MCP-1, which in turn stimulates monocyte chemotaxis. We observed that endothelial cells released significant amounts of MCP-1 within 48 h after ingestion of S. aureus. This was dependent on the number and the virulence of the bacteria used to infect the endothelial cells. The kinetics as well as the amount of MCP-1 released by S. aureus-infected endothelial cells differed markedly from that released by endothelial cells upon stimulation with IL-1beta. Supernatant from S. aureus-infected or IL-1beta-stimulated cells promoted monocyte chemotaxis which was almost entirely abrogated in the presence of neutralizing anti-MCP-1 antibody, indicating that most of the chemotactic activity was due to the release of MCP-1 into the supernatant. Our findings support the notion that endothelial cells can actively initiate and sustain an inflammatory response after an encounter with pathogenic microorganisms, without the intervention of macrophage-derived proinflammatory cytokines.     

TNF receptor-associated factor-1 (TRAF1) negatively regulates Toll/IL-1 receptor domain-containing adaptor inducing IFN-beta (TRIF)-mediated signaling

Toll-like receptor 3 (TLR3) plays an important role in antiviral responses through recognizing viral double-stranded RNA produced during viral infection and mediating induction of type I IFN. TRIF is a Toll/IL-1 receptor (TIR) domain-containing adaptor protein that is associated with TLR3 and critically involved in TLR3-mediated signaling. In yeast two-hybrid screens, we identified TNF receptor-associated factor (TRAF)1 as a TRIF-interacting protein. The TRAF-C domain of TRAF1 and the TIR domain of TRIF were responsible for their interaction. Overexpression of TRAF1 inhibited TRIF- and TLR3-mediated activation of NF-kappaB, IFN-stimulated response element and the IFN-beta promoter. Overexpression of TRIF caused caspase-dependent cleavage of TRAF1. The cleaved N-terminal but not C-terminal fragment of TRAF1 was responsible for inhibiting TRIF signaling. Mutation of the caspase cleavage site of TRAF1 or addition of the caspase inhibitor crmA inhibited TRAF1 cleavage and abolished the ability of TRAF1 to inhibit TRIF signaling, suggesting that TRIF-induced cleavage of TRAF1 is required for its inhibition of TRIF signaling. Our findings provide a novel mechanism for negative regulation of TRIF-mediated signaling.     

Colonic epithelial cells induce endothelial cell expression of ICAM-1 and VCAM-1 by a NF-kappaB-dependent mechanism.

Epithelial cells are positioned in close proximity to endothelial cells. A non-contact coculture system was used to investigate whether colonic epithelial cells activated with various cytokines are able to provide signals that can modulate ICAM-1 and VCAM-1 expression on endothelial cells. Coculture of human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMEC-1) with TNF-alpha/IFN-gamma-stimulated human colon epithelial cell lines led to a significant up-regulation of endothelial ICAM-1 and VCAM-1 expression. Increased ICAM-1 and VCAM-1 expression by endothelial cells was accompanied by an increase in endothelial cell NF-kappaB p65 and NF-kappaB-DNA-binding activity. Inhibition of endothelial NF-kappaB activation using the proteosome inhibitors MG-132 and BAY 11-7082 resulted in a significant decrease of ICAM-1 expression, indicating an important role for NF-kappaB in this response. This cross-talk may represent a biological mechanism for the gut epithelium to control the colonic inflammatory response and the subsequent immune cell recruitment during inflammation.     

Low-density lipoproteins enhance transforming growth factor-beta 1 (TGF-beta 1) and monocyte chemotactic protein-1 (MCP-1) expression induced by cyclosporin in human mesangial cells.

Cyclosporin (CsA) is widely used in the treatment of renal disease and transplantation, which are often complicated by alterations of lipid metabolism. Both chronic administration of CsA and hyperlipidaemia have been shown to evoke an early macrophage influx and have progressively led to glomerular and interstitial sclerosis. MCP-1 is the major monocyte chemoattractant secreted by stimulated mesangial cells and TGF-beta 1 is a key mediator of fibrogenesis in chronic progressive renal fibrosis. Thus, the combined effect of CsA and low-density lipoprotein (LDL) on the gene and protein expression of MCP-1 and TGF-beta 1 in cultured human mesangial cells (HMC) was explored. Both agents induced an early and persistent increase of MCP-1 and TGF-beta 1 mRNA levels and protein release. The simultaneous addition of CsA and LDL did not display any additive effect on target gene expression, but it caused a synergistic effect on MCP-1 and TGF-beta 1 protein secretion into culture medium. On the other hand, CsA and LDL had different effects on cell proliferation: the latter increased DNA synthesis, whereas CsA inhibited both spontaneous and mitogen-stimulated mesangial cell growth. The study concludes that CsA and LDL display an additive effect on TGF-beta 1 and MCP-1 synthesis and release by HMC, thus possibly co-operating to induce an early macrophage influx and the subsequent mesangial expansion and increased extracellular matrix deposition. However, in contrast they seem to modulate HMC proliferation differently, which is a further critical event intimately involved in the development of glomerulosclerosis.     

Interleukin-1 beta enhances and interferon-gamma suppresses activin A actions by reciprocally regulating activin A and follistatin secretion from bone marrow stromal fibroblasts.

Activin A is a multi-functional cytokine with a potent stimulation on erythroid cell differentiation in the bone marrow. The actions of activin A are determined by a balance of the levels of activin A and its inhibitor, follistatin (FS). However, the regulation of its actions in the bone marrow has been unclear. Here we show that bone marrow-derived stromal fibroblasts are the major source of activin A and FS in the bone marrow, and that the production of activin A is enhanced by interleukin-1beta (IL-1beta) and lipopolysaccharide (LPS), whereas interferon-gamma (IFN-gamma) inhibits the secretion of activin A by stromal fibroblasts. Concomitantly, IL-1beta as well as LPS inhibits and IFN-gamma stimulates FS secretion from stromal fibroblasts. Thus, these cytokines potently regulate activin A actions by reciprocal modulation of activin A and FS secretion from stromal fibroblasts. Because activin A exhibits anti-inflammatory effects in various tissues, up-regulation of activin A actions by IL-1beta and endotoxin in the bone marrow may play a protective role against inflammatory processes as well as anaemia. The present results also suggest that the inhibitory effect of IFN-gamma on erythropoiesis is mediated at least in part by a suppression of activin A actions in bone marrow.     

Estradiol reduces basal and cytokine induced monocyte adhesion to endothelial cells

OBJECTIVE: To investigate the effect of 17beta-estradiol (E2) on binding of monocytes to human aortic endothelial cells (HAECs) with or without cytokine induction. METHODS: Confluent monolayers of HAECs were incubated with or without E2 for 48 h prior to the monocyte adhesion assay. In studies with cytokines, 1 ng/ml tumor necrosis factor-alpha (TNF-alpha), 20 U/ml interleukin-1beta (IL-1beta) or both were added to the culture medium for the final 24 or 4 h. For the measurement of monocyte adhesion, 3H-thymidine labeled human THP-1 monocytes (4 x 10(5) cells per well) were added to the confluent monolayer of HAECs and incubated at 37 degrees C for 90 min. The unbound THP-1 cells were removed by gentle washing, and bound cells were digested with NaOH and quantified by measuring radioactivity. RESULTS: When HAECs were pretreated for 48 h with E2 the basal adhesion of THP-1 cells was reduced by an average of 28%. Estrogen significantly reduced cytokine-induced adhesion by 30-35% when the cytokines were added for 4 h. When the cytokine treatment was prolonged to 24 h, pretreatment of HAECs with E2 had no effect on THP-1 cell adhesion. CONCLUSIONS: E2 reduces basal and short-term cytokine induced monocyte binding to HAECs. Since monocyte adhesion to vascular endothelial cells is one of the initial steps in the pathogenesis of atherosclerosis, E2 may mediate vascular protection by reducing monocyte-endothelial cell binding in the early stages of atherogenesis.     

Cholera toxin activates dendritic cells through dependence on GM1-ganglioside which is mediated by NF-kappaB translocation

Cholera toxin (CT) is a potent adjuvant; however, the mechanism for its ability to enhance mucosal immunity has not been fully elucidated. We report here that CT exerts its adjuvant properties by signaling through the GM1 ganglioside receptor. When ganglioside-defective mice were given the antigen (Ag) ovalbumin (OVA) with CT by the oral route, CT failed to support either OVA-specific antibody or CD4+ T cell responses. In vitro treatment of murine bone marrow-derived dendritic cells (DC) with CT induced full maturation as evidenced by up-regulation of the costimulatory molecules, as well as by an enhanced ability to effectively present OVA for Ag-specific T cell responses. On the other hand, ganglioside-defective DC failed to differentiate to full function as Ag-presenting cells in response to CT. Since ganglioside-defective DC showed a mature phenotype after stimulation with lipopolysaccharide (LPS), the effects of CT on DC was independent of signal transduction through adjuvant receptor for LPS, the Toll-like receptor 4. Furthermore, CT also induced nuclear translocation of nuclear factor (NF)-kappaB in DC in a GM1-dependent fashion. These results highlight gangliosides expressed by DC for recognition of the non-self protein bacterial enterotoxin, which employ a unique signaling pathway to induce both innate and adaptive immunity.     

CYR61 modulates the vascular endothelial growth factor C expression of decidual NK cells via PI3K/AKT pathway

Citation Zhang X, Ding L, Diao Z, Yan G, Sun H, Hu Y. CYR61 modulates the vascular endothelial growth factor C expression of decidual NK cells via PI3K/AKT pathway. Am J Reprod Immunol 2012; 67: 216–223 Problem Either vascular endothelial growth factor C (VEGFC) or CYR61 plays an important role in placental development and may be involved in pre‐eclampsia. Decidual natural killer (dNK) cells are the main source of VEGFC in the maternal–fetal interface. However, it is unclear about CYR61 on the regulation of VEGFC secretion in dNK cells. Method of study Decidual natural killer cells were isolated from decidual tissues of first trimester of pregnancy with anti‐human CD56–conjugated microbeads. Integrin αvβ3 was detected using immunofluorescent staining. dNK cells were cultured in the presence of CYR61, anti‐human αvβ3 integrin antibody (LM609), PI3K inhibitor (LY294002), or MEK inhibitor (U0126). VEGFC mRNA and protein were evaluated by real‐time PCR and ELISA, respectively. Results Exogenous CYR61 induced the expression of VEGFC in dNK cells in both mRNA and protein levels. Integrin αvβ3 was strongly expressed on dNK cell surface. Anti‐αvβ3 integrin antibody inhibited the effect of CYR61 on VEGFC expression. LY294002, but not U0126, significantly reduced this promotion effect of CYR61 on dNK cells. Conclusions The upregulation of VEGFC secretion mainly depends on CYR61 binding with integrin αvβ3 on the surface of dNK cells. PI3K/AKT, rather than the ERK/MAPK signal, is involved in the regulation.     

Extracellular lysosome-associated membrane protein-1 (LAMP-1) mediates autoimmune disease progression in the NOD model of type 1 diabetes

Treatment (from 5 to 25 weeks of age) with a novel blocking monoclonal antibody, mAb I-10, directed against the plasma membrane (pm) form of LAMP-1, protected against development of autoimmune diabetes in the NOD mouse. A shorter course of treatment, i.e. from 5 to 12 weeks of age, significantly reduced the occurrence of insulitis as well as disease onset. Interfering with pm-LAMP-1 required continuous treatment as tolerance was not observed when treatment was stopped, and no higher proportion of cells with a T regulatory phenotype (e.g. CD4(+)CD25(+)) were induced. The mechanism appears to involve modulating a proinflammatory cytokine, as the proportion of pancreatic-infiltrating IFN-gamma-positive cells was significantly reduced in the mAb I-10-treated group. These results demonstrate an unexpected role for pm-LAMP-1 in autoimmune disease progression, and suggest that further investigation should be performed to understand how this molecule modulates IFN-gamma-driven responses.