Induction Of Adhesion Molecules Research Articles

Direct Pro-Inflammatory Effect of C-Reactive Protein on Human Pulmonary Artery Endothelial Cells

C-reactive protein (CRP) has a prognostic role in cardiovascular and pulmonary diseases. Recent data suggest its pro-inflammatory effects in atherosclerotic lesion formation. This raises the hypothesis of whether or not CRP has pro-inflammatory effects on pulmonary vasculature by inducing the production of endothelin-1 (ET)-1, a potent vasoconstrictor and proliferative cytokine, and expression of adhesion molecules which could culminate in inflammatory cell recruitment and vascular injury. Human pulmonary artery endothelial cells (HPAECs) were cultured and incubated with 25μg/ml of human recombinant CRP and with interleukin (IL)-1β 10ng/ml, a well-known activator of endothelial cells, which served as a positive control for 24 hours. Expression of vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1 was assessed by flow cytometry. Secretion of ET-1 from HPAECs was also evaluated. In this study we show that incubation of HPAECs with human recombinant CRP for 24 hours induced a significant increase in ICAM-1 expression (from 610 to 6553 mean fluorescence intensity, p < 0.005) and VCAM-1 expression (from 212 to 303 mean fluorescence intensity, p < 0.05), as compared to control. Adhesion molecule induction was similar to that observed in endothelial cells activated with IL-1β. Likewise, CRP potentiated the ET-1 production by HPAECs. The levels of ET-1 were significantly higher at 24 hours (control 19.94±3 vs CRP 46.54±18 pg/ml, p < 0.05). In conclusion, this study makes a novel observation that CRP induces expression of adhesion molecules and secretion of ET-1 in HPAECs. Our study provides the first evidence that CRP exerts direct proinflammatory effects on pulmonary artery endothelial cells.

Kruppel-like factors and vascular inflammation: implications for atherosclerosis.

Kruppel-like factors and vascular inflammation: implications for atherosclerosis.

Protective effects of (−)-epigallocatechin-3-gallate against TNF-α-induced lung inflammation via ROS-dependent ICAM-1 inhibition

Oxidative stresses are considered to play an important role in the induction of cell adhesion molecules and proinflammatory cytokines implicated in inflammatory processes. Heme oxygenase (HO)-1 and suppressors of cytokine signaling (SOCS)-3 exert several biological functions, including antiapoptotic and anti-inflammatory effects. Here, we report that HO-1 and SOCS-3 were induced in A549 cells and human pulmonary alveolar epithelial cells (HPAEpiCs) treated with (−)-epigallocatechin-3-gallate (EGCG). EGCG protected against tumor necrosis factor (TNF)-α-mediated lung inflammation by down-regulation of oxidative stress and intercellular adhesion molecule (ICAM)-1 expression in A549 cells or HPAEpiCs and the lungs of mice. EGCG inhibited TNF-α-induced ICAM-1 expression, THP-1 cells adherence, pulmonary hematoma and leukocyte (eosinophils and neutrophils) count in bronchoalveolar lavage fluid in mice. In addition, EGCG also attenuated TNF-α-induced oxidative stress, p47phox translocation, MAPKs activation, and STAT-3 and activating transcription factor (ATF)2 phosphorylation. EGCG also reduced the formation of a TNFR1/TRAF2/Rac1/p47phox complex. Moreover, in this study, the observed suppression of TNF-α-stimulated ICAM-1 expression and reactive oxygen species (ROS) generation by EGCG was abrogated by transfection with siRNA of SOCS-3 or HO-1. These results suggested that HO-1 or SOCS-3 functions as a suppressor of TNF-α signaling, not only by inhibiting adhesion molecules expression but also by diminishing intracellular ROS production and STAT-3 and ATF2 activation in A549 cells or HPAEpiCs and the lungs of mice.

Characterization of retinal expression of vascular cell adhesion molecule (VCAM-1) during experimental autoimmune uveitis

Leukocyte adhesion to the blood retinal barrier is a critical step in the pathogenesis of non-infectious uveitis and is mediated in part through the induction of adhesion molecules on retinal cells. Here, we have investigated the retinal expression of Vascular Cell Adhesion Molecule 1 (VCAM-1) in mouse experimental models of non-infectious uveitis. For each eyes, a histological score was given, and the expression of VCAM-1 analyzed by immunohistology. Co-labellings for GFAP, endoglin, aquaporin 4 and recoverin were also performed in order to determine which cell type expressed VCAM-1. In low grade uveitis, obtained after adoptive transfer of semi-purified autoreactive lymphocytes, VCAM-1 was only punctually expressed in the internal limiting membrane and epithelial cells of the ciliary body. Using the same adoptive transfer protocol, we found that, in correlation with disease severity, the staining extended to all internal limiting membranes, vasculitis lesions, Müller cell extensions, outer limiting membranes and RPE cells. VCAM-1 expression in the inner limiting membrane and Müller cell extensions co-stained with GFAP expression. In vasculitis lesions, VCAM-1 co-localized with either GFAP and endoglin expression. The labeling in the outer limiting membrane, did not exactly co-stained with AQ4 (Müller cells marker) or recoverin (photoreceptor marker) and the nature of this expression remained unexplained. Finally, VCAM-1 expression was also analyzed in classical experimental autoimmune uveitis eyes, and a similar pattern of expression was found. In conclusion VCAM-1 is expressed on all blood retinal barrier cells during experimental non-infectious uveitis and might thus play an important role in inflammatory cell recruitment during disease development.

PMO-120 Kupffer cell derived interleukin (IL)-18 induces hepatic inflammation by promoting lymphocyte subsets recruitment on hepatic endothelial cells

IntroductionIL-18, known as interferon-γ inducing factor, is a potent pro-inflammatory cytokine implicated in liver allograft rejection, viral hepatitis and hepatocellular carcinoma progression, where it plays an important role in cell-mediated...

Suppression of adhesion molecule expression by phenanthrene-containing extract of bulbils of Chinese Yam in vascular smooth muscle cells through inhibition of MAPK, Akt and NF-κB

Atherosclerosis is a chronic inflammatory disease associated with increased expression of adhesion molecules in vascular smooth muscle cells (VSMCs). The objective of this study was to examine the in vitro effects of extract from aerial Bulbil of Dioscorea batatas Decne (Db-Ex) on the ability to suppress the expression of adhesion molecules induced by TNF-α. We also identified bioactive components from a methanol extract. VSMCs pre-exposed to Db-Ex (10–100μg/ml) were stimulated with TNF-α (10ng/ml). Preincubation of VSMCs for 2h with Db-Ex dose-dependently inhibited TNF-α-induced adhesion of THP-1 monocytic cells and mRNA and protein expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). Db-Ex treatment decreased ROS production and the amount of phosphorylated form of p38, ERK, JNK and Akt in TNF-α-stimulated cells, suggesting that Db-Ex inhibits adhesion molecule expression possibly through MAPK and Akt regulation. Db-Ex also suppressed TNF-α-activation NK-κB. This effect was mediated through degradation of IκBα and nuclear translocation of the p65 subunit of NF-κB. These results suggest that Db-Ex inhibits monocyte adhesion and the TNF-α-mediated induction of adhesion molecules in VSMC by downregulating the MAPK/Akt/NF-κB signaling pathway, which may explain the ability of Db-Ex to suppress inflammation within the atherosclerotic lesion.

Abstract 222: D-Series Resolvins Modulate Postinjury Signaling Pathways in Vascular Smooth Muscle Cells

Introduction: Recent work suggests that the resolution of inflammation is an active process involving specialized molecules that are locally generated. D-series resolvins (RvD) are endogenous pro-resolving lipid mediators derived from the ω-3 polyunsaturated fatty acid docosahexaenoic acid (DHA). VSMC activation following vascular injury leads to neointimal hyperplasia which may reflect a relative “resolution deficit” in the vessel wall. Objectives: We sought to determine the effects of RvD on injury-related inflammatory and growth factor signaling pathways in VSMC, using in vitro and in vivo models. Hypothesis: We hypothesize that RvD will attenuate VSMC activation responses and modulate vascular injury. Methods: Human VSMC were treated with cytokines (TNF-α, IL-1β), growth factors (PDGF, AngII) or oxidant stress (H 2 O 2 ) in the presence of RvD1 or RvD2 (.01-100 nM), and phenotype was assessed by cytotoxicity, proliferation, migration (transwell), monocyte adhesion (U937) and adhesion molecule expression (qPCR and flow cytometry) assays. NZW rabbits (N=4) underwent bilateral femoral balloon injury with intraluminal delivery of RvD2 (10 nM vs vehicle control) to examine acute effects (3 days) on the injury response. Results: RvD treatment of VSMC produced dose-dependent inhibition of VSMC proliferation (max %inhibition: RvD1 58.8%, p<0.01, RvD2 63.1%, p<0.01), migration (RvD1 66.1%, p<0.01%, RvD2 68.8%, p<0.01), monocyte adhesion (RvD1 36.0%, p<0.01, RvD2 41.0%, p<0.01), and inducible adhesion molecule expression (VCAM-1: RvD1 70.5%, p<0.01, RvD2 77.2%, p<0.01; ICAM-1: RvD1 65.4%, p<0.01, RvD2 72.1%, p<0.01) without measurable cytotoxicity. In the rabbit model of balloon arterial injury, proliferation was significantly reduced at 3 days in RvD2 treated vessels (%inhibition 57%, p<0.01). Conclusion: RvD broadly inhibit VSMC activation responses and may modulate the vascular injury response in-vivo .

Hodgkin and Reed-Sternberg cells modulate endothelial cell function in classical Hodgkin lymphoma (61.9)

Abstract Growth and survival of neoplastic Hodgkin and Reed-Sternberg cells (H-RS) cells in classical Hodgkin lymphoma (cHL) is dependent on cell-cell contact and soluble mediator signals derived from the inflammatory infiltrate within the lesion. However, the mechanisms underlying recruitment of the inflammatory infiltrate, particularly T cells, into lesional lymph nodes remain unclarified. In this study, we test the hypothesis that H-RS cells secrete soluble mediators to induce endothelial cell (EC) activation to modulate T cell recruitment in cHL. We examined in-vitro interactions, under static and flow conditions, between freshly isolated T cell subsets and EC treated with conditioned medium (CM) harvested from the H-RS cell line, KM-H2. Both CM-stimulated EC and TNFα-stimulated EC support CD4+ naive and memory T-cell interactions under flow conditions. Both CD4+ naive and memory T cell demonstrated enhanced transmigration across CM-stimulated EC monolayers in response to CXCL12 as compared to TNFα-stimulated or unstimulated EC. Our data show that the upregulation of inducible adhesion molecules on CM-stimulated EC is dependent on the NFκB pathway; but the dominant mediator involved is not TNFα. However, blockade of cyclooxygenase activity in KM-H2 cells partially attenuated the efficacy of the CM in activating EC. These findings suggest that H-RS cells secrete soluble mediators that can modulate endothelial cell function and influence recruitment of T cells into the cHL lesion.

HMGB‐1 induces c‐kit+ cell microvascular rolling and adhesion via both toll‐like receptor‐2 and toll‐like receptor‐4 of endothelial cells

High-mobility group box 1 (HMGB-1) is a strong chemo-attractive signal for both inflammatory and stem cells. The aim of this study is to evaluate the mechanisms regulating HMGB-1–mediated adhesion and rolling of c-kit+ cells and assess whether toll-like receptor-2 (TLR-2) and toll-like receptor-4 (TLR-4) of endothelial cells or c-kit+ cells are implicated in the activation of downstream migration signals to peripheral c-kit+ cells. Effects of HMGB-1 on the c-kit+ cells/endothelial interaction were evaluated by a cremaster muscle model in wild-type (WT), TLR-2 (−/−) and Tlr4 (LPS-del) mice. The mRNA and protein expression levels of endothelial nitric oxide synthase were determined by quantitative real-time PCR and immunofluorescence staining. Induction of crucial adhesion molecules for rolling and adhesion of stem cells and leukocytes were monitored in vivo and in vitro. Following local HMGB-1 administration, a significant increase in cell rolling was detected (32.4 ± 7.1% in ‘WT’ versus 9.9 ± 3.2% in ‘control’, P < 0.05). The number of firmly adherent c-kit+ cells was more than 13-fold higher than that of the control group (14.6 ± 5.1 cells/mm2 in ‘WT’ versus 1.1 ± 1.0 cells/mm2 in ‘control’, P < 0.05). In knockout animals, the fraction of rolling cells did not differ significantly from control levels. Firm endothelial adhesion was significantly reduced in TLR-2 (−/−) and Tlr4 (LPS-del) mice compared to WT mice (1.5 ± 1.4 cells/mm2 in ‘TLR-2 (−/−)’ and 2.4 ± 1.4 cells/mm2 in ‘Tlr4 (LPS-del)’ versus 14.6 ± 5.1 cells/mm2 in ‘WT’, P < 0.05). TLR-2 (−/−) and Tlr4 (LPS-del) stem cells in WT mice did not show significant reduction in rolling and adhesion compared to WT cells. HMGB-1 mediates c-kit+ cell recruitment via endothelial TLR-2 and TLR-4.

Epstein-Barr virus induces adhesion molecule CD226 (DNAM-1) expression during primary B cell transformation into lymphoblastoid cell lines

Epstein-Barr virus (EBV), an oncogenic herpesvirus associated with Burkitt’s lymphoma and other AIDS-related B cell malignancies, transforms primary human B cells into lymphoblastoid cell lines (LCLs) ex vivo. As LCLs express viral gene products similar to those found in EBV-mediated cancers, LCLs provide a practical model for tumorigenesis. Previous unpublished findings from our lab indicate that LCLs constitutively express the adhesion molecule CD226 (DNAM-1), found on virtually all peripheral blood NK cells, T cells, and monocytes, but only a small subset (~3%) of B cells. Although CD226 is known to mediate T-cell differentiation and cytotoxicity, NK cell cytotoxicity, NKT cell apoptosis, and monocyte extravasion, CD226 function in B cells remains relatively unstudied. Biochemically, CD226 functions to support the interaction between the intracellular adhesion molecules LFA-1 and ICAM-1. Here, we demonstrate that EBV specifically induces CD226 expression in primary human B cells and EBV-negative B lymphoblasts during viral-mediated proliferation and outgrowth. EBV infection of primary B cells increased CD226 surface expression 5-fold during early proliferation and approximately 30-fold upon transformation into LCLs. EBV-converted Burkitt’s lymphoma cells constitutively express CD226, while EBV-negative B cell lymphomas do not. Additionally, we demonstrate that LMP-1, an EBV latency III membrane oncoprotein, induces CD226 expression in EBV-negative Burkitt’s lymphoma cells. Finally, we demonstrate that the NFκB pathway regulates CD226 expression. Indeed, B cell lymphomas with high NFκB activity (activated B cell-like diffuse large B-cell lymphomas) express CD226 at higher levels than B cell lymphomas with low NFκB activity (germinal center B cell-like diffuse large B cell lymphomas). As CD226 supports the interaction between LFA-1 and ICAM-1, which is critical to maintain the constitutive aggregation of EBV-transformed B cells, we propose that EBV-mediated induction of CD226 drives cell-cell contact ensuring B cell survival. These data suggest that CD226, a newly identified EBV-induced cell adhesion molecule, may play a key role in the pathogenesis of AIDS-associated and other B cell lymphomas.

Streptococcus oralis coaggregation receptor polysaccharides induce inflammatory responses in human aortic endothelial cells

Streptococcus oralis, belonging to the oral viridans group streptococci, has been detected in human cardiovascular lesions including infective endocarditis and atheromatous plaques. The organism has coaggregation receptor polysaccharides (RPS) on the cell wall, which function as receptors for surface adhesins on other members of the oral biofilm community. The present study examined the capacity of S. oralis RPS to induce inflammatory responses in human aortic endothelial cells (HAECs). Purified RPS was used to stimulate HAECs, and the induction of cytokines, adhesion molecules and Toll-like receptors (TLRs) was examined. Involvement of RPS in HAEC invasion by S. oralis was also examined. RPS-stimulated HAECs produced more cytokines (interleukin-6, interleukin-8 and monocyte chemoattractant protein-1) and intercellular adhesion molecule-1 than non-stimulated HAECs. The messenger RNA (mRNA) expression of cytokines and adhesion molecules in RPS-stimulated HAECs increased markedly compared with that in non-stimulated HAECs. Upregulation of TLR-2 mRNA expression was demonstrated in RPS-stimulated HAECs. Moreover, TLR-2 mRNA expression and cytokine production were reduced by the incubation of HAECs with inhibitors against p38 mitogen-activated protein kinase and nuclear factor-κB. An RPS-defective mutant of S. oralis showed greater invasion into HAECs than an RPS-possessing strain. However, HAECs invaded by the RPS-defective mutant produced less cytokines than HAECs invaded by the RPS-possessing strain, indicating that RPS can stimulate HAECs intracellularly. These results suggest that S. oralis RPS may be an important contributor to the pathogenesis of cardiovascular diseases such as infective endocarditis and atherosclerosis.

γ-Oryzanol Reduces Adhesion Molecule Expression in Vascular Endothelial Cells via Suppression of Nuclear Factor-κB Activation

γ-Oryzanol (γ-ORZ) is a mixture of phytosteryl ferulates purified from rice bran oil. In this study, we examined whether γ-ORZ represents a suppressive effect on the lipopolysaccharide (LPS)-induced adhesion molecule expression on vascular endothelium. Treatment with LPS elevated the mRNA expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin in bovine aortic endothelial cells (BAECs). Pretreatment with γ-ORZ dose-dependently decreased the LPS-mediated expression of these genes. Western blotting also revealed that pretreatment with γ-ORZ dose-dependently inhibited LPS-induced VCAM-1 expression in human umbilical vein endothelial cells. Consistently, pretreatment with γ-ORZ dose-dependently reduced LPS-induced U937 monocyte adhesion to BAECs. In immunofluorescence, LPS caused nuclear factor-κB (NF-κB) nuclear translocation in 40% of BAECs, which indicates NF-κB activation. Pretreatment with γ-ORZ, as well as its components (cycloartenyl ferulate, ferulic acid, or cycloartenol), dose-dependently inhibited LPS-mediated NF-κB activation. Collectively, our results suggested that γ-ORZ reduced LPS-mediated adhesion molecule expression through NF-κB inhibition in vascular endothelium.

Interleukin-1 receptor type-1 in non-hematopoietic cells is the target for the pro-atherogenic effects of interleukin-1 in apoE-deficient mice

ObjectivesInterleukin (IL)-1 produced by vascular and bone marrow-derived cells exerts proinflammatory effects in these cell types by binding to IL-1 receptor type-1 (IL-1R1). We have previously shown that bone marrow-derived IL-1α and IL-1β are critical for atherogenesis in apoE knockout (KO) mice. The aim of the present study was to investigate whether IL-1R1 on vascular wall resident or bone marrow-derived cells mediates IL-1's effects in atherogenesis. Methods and resultsWe generated apoE−/−/IL-1R1−/− double knockout (DKO) mice and created radiation chimeras. Aortic sinus lesion area was 20–47% lower in DKO compared to apoE KO mice with similar plasma lipids. The production of IL-1α and IL-1β upon stimulation with LPS was not altered in IL-1R1−/− compared to IL-1R1+/+ peritoneal macrophages. DKO mice transplanted with IL-1R1+/+ bone marrow-derived cells had reduced (48%) aortic sinus lesion compared to apoE KO mice while specific deficiency of IL-1R1 in bone marrow-derived cells did not attenuate atherosclerosis. The mRNA levels of genes that promote macrophage recruitment to the vascular wall, namely CD68, VCAM-1, ICAM-1 and MCP-1 were lower in aortas from DKO compared to apoE KO mice. Finally, blockade of IL-1R1 with IL-1R antagonist (IL-1Ra) resulted in complete abrogation of IL-1β-induced expression of adhesion and chemotactic molecules and IL-1α, in isolated human umbilical vein endothelial cells (HUVEC). ConclusionsVascular wall resident cells are the main targets for the pro-atherogenic effects of bone marrow-derived IL-1 through IL-1R1, partly by induction of adhesion and chemotactic molecules in endothelial cells.

P1-12-08: Induction of Adhesion Molecules on Target Cells Maximizes Antibody-Dependent Cell-Mediated Cytotoxicity of Anti-Her2 Therapeutic Antibody with High Fucose Glycan.

Abstract Background: Antibody-dependent cell-mediated cytotoxicity (ADCC) is one pivotal effector function of certain therapeutic antibodies. ADCC is the lysis of antibody-coated target cells by effector cells expressing Fc receptors (FcR) that recognize the fragment crystallizable (Fc) region of the bound antibody. Higher fucosylated terminal glycan on Fc results in significantly lower ADCC activity because core fucose sterically hinders the binding of Fc region to FcR on effector cells. The role of adhesion molecules in ADCC is unclear but it has been reported that adhesion molecules help better orientation of effector cells (natural killer cells) toward adhesion molecule-coated beads. We hypothesize that a preferable association of effector cells and target cells mediated by adhesion molecules may compensate ADCC loss due to the steric hindrance of high core fucose on Fc. Recombinant humanized monoclonal anti-Her2 antibodies (anti-Her2 rhuMAb) at various fucosylation levels have been used in this study to evaluate the role of adhesion molecules in ADCC of antibodies with high fucose glycan. Materials and Methods: Natural killer (NK) cell line transfected with FcR were used as effector cells. Her2-expressing breast cancer cell lines BT-474 and SK-BR3 were used as target cells. Adhesion molecules were induced in target cells by incubation with 50ng/ml of recombinant human tumor necrosis factor (TNFa) for 1–2 days. Anti-Her2 rhuMAbs with different Fc fucosylation (G0-F from &amp;lt;1% to &amp;gt;2%) were added in the co-culture of effector cells and target cells. ADCC activities were quantitated by target cells lysis assessment using Europium-TDA release assay. Results: Untreated BT-474 or SK-BR3 target cells had very little adhesion molecule expression. A high fucosylated anti-Her2 rhuMAb induced 52% of target cell lysis, which represented two-thirds of cell lysis by a low fucosylated Ab. Increment of E:T ratio could not maximize ADCC activities. With TNFa treatment, target cell lysis was increased from 52% to 100% by high fucose rhuMAb. This enhancement of ADCC activities is probably due to the expression of adhesion molecules such as ICAM-1 and VCAM-1, which was shown to be up-regulated by 100-fold on target cells in the presence of TNFa. Our data suggested that ADCC activities in Her2-expressing breast cancer cell lines were HER2−specific, anti-HER2 rhuMAb-dependent and adhesion molecules were indispensible for the enhanced ADCC activities. Discussion: rhuMAbs produced in Chinese hamster ovary (CHO) cell lines may contain various Fc fucosylation, hence various ADCC activities. Although up-regulation of adhesion molecules alone cannot lyse target cells directly, our data suggested maximized ADCC activities by rhuMAbs with high Fc fucosylation level could be achieved by induction of adhesion molecule expression on target cells. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-12-08.

What Fans the Fire

It is now widely accepted that inflammation and immunity play important roles in the pathogenesis of atherosclerosis and diabetes mellitus. Over the past 3 decades, it has been demonstrated that cells of both the innate and adaptive immune systems contribute to the progression of atherosclerosis and modulation of plaque stability.1 Similarly, recent studies in experimental models of obesity and type II diabetes mellitus have shown that not only macrophages, but also T cells and B cells are involved in the modulation of adipose depots and the development of insulin resistance.2–5 However, even with all that is known about the important cellular players in atherogenesis, a clear understanding of the mechanisms by which immune cells influence arterial plaque formation is lacking. Article see p 2933 Macrophages are considered the predominant cell involved in foam cell formation and atherosclerotic plaque development. Numerous studies have linked macrophage activation in atherosclerosis to Toll-like receptors (TLRs) and have demonstrated that “danger signals” such as oxidized low-density lipoprotein (LDL), heat shock proteins, and other products of oxidative stress induce adhesion molecule and chemokine production by cells of the vessel wall and by direct activation of macrophages in the lesion. For example, TLRs such as TLR-4, TLR-2, and TLR-6 (in concert with the scavenger receptor CD36 and TLR-4),6–10 are activated by oxidized LDL and may exacerbate the inflammatory nature of the atherosclerotic plaque. In addition to macrophages, other immune cells, including natural killer (NK) cells, T cells, and a unique group of cells, NK T (NKT) cells, have been identified in atherosclerotic plaques of both humans and mice, and depletion of these cells by either antibodies or genetic approaches has shown that these lymphocytes play important roles in lesion formation.1 Specifically, NK and CD4+ T helper 1 (Th1) …

VEGFR2 signalling contributes to increased endothelial susceptibility to TNF-α under chronic non-uniform shear stress

ObjectivesVascular endothelial growth factor receptor 2 (VEGFR2), a tyrosine kinase receptor activated by VEGF and shear stress, is critically involved in endothelial mechanotransduction. We investigated the role of VEGFR2 in non-uniform shear stress-induced endothelial susceptibility to inflammatory stimuli. MethodsEndothelial cells (ECs) were exposed to non-uniform shear stress, followed by stimulation with TNF-α. ECs were transfected with siRNAs against VEGFR2. Alternatively, ECs were treated with blocking antibody against VEGFR2, or with inhibitors of VEGFR2 (ZM 323881), PI3K (LY 294002), or Src-kinase (PP2). THP-1 monocytes were used for dynamic adhesion assays. Endothelial protein expression was determined by immunofluorescence. ResultssiRNA against VEGFR2 decreased VEGFR2 protein expression by 40% as determined by Western blotting. In endothelial cells exposed to non-uniform shear stress, VEGFR2 knockdown inhibited TNF-α-induced NF-κB translocation to the nucleus, and the upregulation of VCAM-1 and E-selectin. Consequently, monocytic cell recruitment to endothelium under non-uniform shear stress conditions was reduced. Similar effects were observed by blocking VEGFR2 activity using a specific inhibitor ZM 323881, or an antibody against VEGFR2 before TNF-α stimulation. Inhibition of PI3K with LY 294002 significantly reduced non-uniform shear stress-induced endothelial susceptibility to TNF-α, whereas blocking Src-kinase with PP2 was ineffective. ConclusionVEGFR2 is critically involved in adhesion molecule induction and monocytic cell recruitment to endothelium in response to non-uniform shear stress and TNF-α. Targeting the mechanosensory cascade can prevent endothelial activation in atherosclerosis-prone regions.

Role of vascular endothelial growth factor, interleukin-2 and tumor necrosis factor-alpha in diabetic retinopathy

Background Diabetic retinopathy (DR) is a progressive vision-threatening complication of diabetes mellitus,but its pathogenic mechanism is still unclear. Recent studies showed that it may be associated with the inflammation response of retinal capillary. Cytokines can cause induction of proinflammatory and adhesion molecules and thereby increase monocyte endothelial cell adhesion, which is now accepted as the early key event in the development of DR. Objective The present study was to determine the relationship between the stages of DR and the levels of serum vascular endothelial growth factor (VEGF) , interleukin-2 ( IL-2 ), tumor necrosis factor-alpha (TNF-α) in diabetic patients. Methods This was a pilot case-controlled study. Ninety patients with type 2 diabetes mellitus were included in this clinical trial and 30 healthy individuals were enrolled as controls. The patients were grouped into the non-diabetic retinopathy(NDR) group,background DR group and proliferative DR(PDR) group according to the results from ophthalmoscopic examination and fundus fluorescein angiography(FFA) ,with 30 patients for each group. The levels of serum VEGF,IL-2,TNF-α were assayed by ELISA and compared among the 4 groups.Written informed consent was obtained from each subject before received any related medical examination to this study. Results The mean serum VEGF levels were(217.35±27. 87)ng/L,(298.31±49.26)ng/L,and(341.23±40. 18)ng/L, respectively, and mean serum IL-2 levels were( 12. 12± 1. 57 )ng/L, (16.43 ±2. 26 )ng/L, and (21.36±0. 86) ng/L,respectively and mean serum TNF-α levels were( 11.63±0. 94) ng/L, ( 17. 52±0. 65) ng/L,and(22. 01±0. 87 ) ng/L respectively in the patients with NDR ,background DR and PDR, showing significant differences from healthy controls with( 193.46±37. 39 ) ng/L for serum VEGF, ( 8. 99 ±0. 57 ) ng/L for serum IL-2 and ( 7.31 ±0. 52 ) ng/L for serum TNF-α ( F =126. 38, P＜0. 0 1 ;F =120. 37, P＜0. 01 ;F =99. 84, P＜0. 01 ). The levels of serum VEGF, IL-2, and TNF-α in the patients with the NDR,background DR and PDR were increased significantly. The level of serum VEGF showed the positively significant correlation with serum IL-2 level and TNF-α level ( r =0. 749, P ＜ 0.01 ; r =0. 631,P＜0. 01 ). The serum levels of VEGF, IL-2 and TNF-α showed a significantly positive correlation with the prolongation and severity of DR(r=0. 791 ,P＜0. 01 ;r=0. 665 ,P＜0. 01 ;r=0. 632,P＜0. 01 ). Conclusions VEGF, IL-2 and TNF-α play active roles in the generation and development of diabetic retinopathy, and the level of serum VEGF is closely associated with the levels of serum IL-2 and TNF-α. during the development of DR. Key words: Type 2 diabetes mellitus; Diabetic retinopathy; Vascular endothelial growth factor; Interleukin-2; Tumor necrosis factor-alpha

Monocytic microparticles activate endothelial cells in an IL-1β–dependent manner

AbstractMicroparticles (MPs) are shed from activated and dying cells. They can transmit signals from cell to cell, locally or at a distance through the circulation. Monocytic MPs are elevated in different diseases, including bacterial infections. Here, we investigated how monocytic MPs activate endothelial cells. We found that MPs from lipopolysaccharide (LPS)–treated THP-1 monocytic cells bind to and are internalized by human endothelial cells. MPs from LPS-treated THP-1 cells, but not untreated cells, induced phosphorylation of ERK1/2, activation of the nuclear factor-κB pathway and expression of cell adhesion molecules intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. Similar results were observed using MPs from LPS-treated peripheral blood mononuclear cells. We next investigated the mechanism by which monocytic MPs activated endothelial cells and found that they contain IL-1β and components of the inflammasome, including apoptosis-associated speck-like protein containing a CARD, caspase-1, and NLRP3. Importantly, knockdown of NLRP3 in THP-1 cells reduced the activity of the MPs and blockade of the IL-1 receptor on endothelial cells decreased MP-dependent induction of cell adhesion molecules. Therefore, monocytic MPs contain IL-1β and may amplify inflammation by enhancing the activation of the endothelium.

Leukocyte rolling and adhesion via ICAM-1 signals to endothelial permeability. Focus on “Leukocyte rolling and adhesion both contribute to regulation of microvascular permeability to albumin via ligation of ICAM-1”

THE VASCULAR ENDOTHELIUM plays a vital role in the inflammatory response by induction and surface expression of adhesion molecules and chemokines. At sites of acute inflammation, blood flow is increased and postcapillary venules exhibit increased permeability (leakiness) and support the influx of blood leukocytes, primarily neutrophils. The relationship between neutrophil influx and increased vessel permeability has been a topic of investigation for decades. Many investigations have reported a direct neutrophil-dependent increase in vessel permeability during inflammation using in vivo and in vitro models (reviewed in Ref. 4). One aspect that has received increased attention is whether endothelial cell adhesion molecules contribute to the regulation of vessel permeability, in addition to their well-characterized role in neutrophil rolling and adhesion. Intercellular adhesion molecule-1 (ICAM-1, also known as CD54) is an immunoglobulin superfamily member that is abundantly expressed on the endothelial cell surface and is enriched at endothelial cell borders in vivo and in vitro (2, 12, 14, 17). ICAM-1 surface expression is upregulated in endothelial cells by proinflammatory cytokines like TNF-, IL-1, IFN-, or bacterial endotoxins, and ICAM-1 serves as a receptor for leukocyte 2-integrins (LFA-1 and Mac-1) (reviewed in Ref. 15). In an experiment of nature, patients with leukocyte adhesion deficiency-1 (LAD-1) have a severe primary immune deficiency in which blood neutrophils fail to localize to sites of inflammation or injury. This defect occurs because patients’ neutrophils either lack 2-integrins or contain mutations in these molecules. Studies using neutrophils from LAD-1 patients or 2-integrin-deficient mice clearly demonstrate that these cells have normal selectin-dependent rolling on activated endothelium but fail to stably arrest and transmigrate. Additional studies have demonstrated that endothelial-expressed ICAM-1 contributes to both kinetics of leukocyte rolling and arrest in vivo as determined by intravital microscopy of the cremaster muscle microcirculation in ICAM-1 / mice (16). In this issue of American Journal of Physiology-Cell Physiology, Sumagin and colleagues (18) use elegant in vivo studies to demonstrate that microvascular permeability in the cremaster muscle model is regulated by leukocyte engagement of ICAM-1. The authors monitored permeability (Ps) in cremaster microcirculation by efflux of luminal fluorescent-tagged albumin by fluorescence confocal intravital microscopy. Prior studies by Sarelius and colleagues (19) in the same model demonstrated that ICAM-1 engagement induced a localized increase in vessel permeability in unstimulated arterioles and in TNF-stimulated venules. In agreement with this finding ,4ho f TNF- stimulation of arterioles and venules in ICAM-1 knockout (KO) animals did not result in increased vessel permeability as compared with wild-type (WT) mice under identical conditions. Similar results were seen with 2-integrin KO mice. In the current study, the authors provide further evidence linking ICAM-1 expression to regulation of endothelial permeability. Comparisons between unstimulated venules and TNF--treated venules reveal that neutrophil rolling regulates venule permeability in unstimulated venules while leukocyte adhesion regulates venule permeability in TNF--stimulated venules. The 2-integrin-blocking antibodies, which inhibit neutrophil arrest on endothelium, reduced the vessel permeability, and this was further reduced by treatment with a combination of 2-integrin and P-selectin blocking antibodies that inhibits both rolling and arrest. Interestingly, the reduction in venule permeability observed by blockade of P-selectin and 2-integrin function were suggested to be due to insufficient ICAM-1 engagement due to the absence of rolling leukocytes. To examine the role that neutrophils play, circulating neutrophils were depleted by antineutrophil GR-1 antibody treatment. Notably, depletion of neutrophils caused a marked decrease in

Tumor necrosis factor alpha (TNF-α) autoregulates its expression and induces adhesion molecule expression in asthma

Subjects with mild asthma underwent repeated low-dose allergen exposure and bronchial biopsies were examined for the expression of TNF-α and adhesion molecules. Bronchial biopsies from moderately severe asthmatics were then tested in an explant culture system to assess the effect of Der p and CDP-870, a TNF-α blocking pegylated-antibody Fab, on expression of TNF-α and adhesion molecules. Low-dose allergen challenge significantly upregulated sub-mucosal mast cells, TNF-α(+) cells, and VCAM. When bronchial explants were exposed to Der p and CDP 870 for 24h, CDP 870 caused a significant reduction in TNF-α release both at baseline and following stimulation with Der p allergen. The bronchial biopsies showed significant upregulation of TNF-α positive cells and ICAM-1 following exposure to Der p (p=0.03) and this was reduced in the presence of CDP-870. So, allergen exposure up-regulates TNF-α expression in asthma and down-stream targets, including adhesion molecules that contribute to airway inflammation.