Intracellular Adhesion Molecule-1 Expression Research Articles

Inhibitory effect of betulinic acid on TNF‐α‐induced adhesion molecule and its related signaling

Vascular inflammation is an important event in the development of vascular diseases including atherosclerosis. In the present study, we investigated whether betulinic acid (BA) inhibits vascular inflammation process induced by tumor necrosis factor‐alpha (TNF‐α) in human umbilical vein endothelial cells (HUVEC). Pretreatment with BA was significantly blocked TNF‐α‐induced expression levels of cell adhesion molecules such as vascular cell adhesion molecule‐1 (VCAM‐1), intracellular adhesion molecule‐1 (ICAM‐1), and endothelial cell selectin (E‐selectin). Gelatin zymography results showed that TNF‐α‐induced metalloproteinase (MMP)‐2 and MMP‐9 activities were prevented by pretreatment with BA. Real time qRT‐PCR data also showed that BA suppressed TNF‐α‐induced increase in VCAM‐1, ICAM‐1, and E‐selectin mRNA expression levels. In addition, BA inhibited the TNF‐α‐induced intracellular reactive oxygen species (ROS) production. Furthermore, pretreatment with BA significantly inhibited the translocation to nucleus and transcriptional activity of NF‐κB increased by TNF‐α. In conclusion, the present data suggested that BA could suppress TNF‐α‐induced vascular inflammatory process, due to the inhibition of ROS and NF‐κB activation in HUVEC.

Nuclear factor kappaB-mediated down-regulation of adhesion molecules: Possible mechanism for inhibitory activity of bigelovin against inflammatory monocytes adhesion to endothelial cells

The flowers of Inula britannica L. var. chinensis (Rupr.) Reg. (Compositae) are used in traditional medicine to treat asthma, chronic bronchitis, and acute pleurisy in China and Korea. However, the pharmacological actions of Inula britannica L. var. chinensis on endothelial cells and inflammatory monocytes are not clear. In this study, we investigated whether bigelovin, a sesquiterpene lactone isolated from the flowers of Inula britannica L. var. chinensis, inhibits monocyte adhesion and adhesion molecule expression in brain endothelial cells. We measured tumor necrosis factor-α (TNF-α)-enhanced Raw264.7 monocyte binding to brain endothelial cells and the levels of cell adhesion molecules, including vascular adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), and endothelial-selectin (E-selectin) on the surface of brain endothelial cells. Bigelovin significantly inhibited these in a dose-dependent manner without affecting cell viability. Furthermore, bigelovin suppressed the nuclear factor kappaB (NF-κB) promoter-driven luciferase activity, NF-κB activation, and degradation of NF-κB inhibitor protein alpha (IκBα). These results indicate that bigelovin inhibits inflammatory monocyte adhesion to endothelial cells and the expression of VCAM-1, ICAM-1, and E-selectin by blocking IκBα degradation and NF-κB activation.

Influence of Iodide Excess and Interferon-γ on Human Primary Thyroid Cell Proliferation, Thyroglobulin Secretion, and Intracellular Adhesion Molecule-1 and Human Leukocyte Antigen-DR Expression

The effect of iodide on thyroid cell proliferation and function in vivo or in cultured thyroid cells has been previously reported and is still controversial. The aim of this study was to clarify these conflicting results by examining if prolonged high iodide exposition with or without interferon (IFN)-gamma has an effect on human primary thyroid cell proliferation, thyroglobulin (Tg) production, and intercellular adhesion molecule-1 (ICAM-1) and human leukocyte antigen (HLA)-DR expression. Primary human thyroid cells were used. Cells were cultured in Coon's modified Ham's F-12 medium supplemented with 5% fetal calf serum in monolayer conditions to induce proliferation and were aggregated for molecular expression and Tg production analysis. HLA-DR and ICAM-1 expression were measured by flow cytometry and Tg by immunometric assay. Potassium iodide (KI) was more potent in arresting primary human thyroid cell proliferation as compared to sodium iodide and the effect was mediated by its action at G0/G1 and G2/M phases of the cell cycle. There were no signs of apoptosis or necrosis. An excess of KI alone did not change the expression of HLA-DR and Tg production, but gradually increased ICAM-1. Low-dose IFN-gamma and excess KI in combination transiently inhibited HLA-DR expression, while ICAM-1 was expressed at a higher level than with IFN-gamma alone. Tg production was moderately increased with low-dose IFN-gamma. However, a combination of high-dose KI with low-dose IFN-gamma significantly decreased Tg secretion, compared with IFN-gamma alone. Augmented ICAM-1 in the presence of iodide excess and low-dose IFN-gamma could induce secretion of proinflammatory cytokines and lymphocytic infiltration in the thyroid gland. Decreased Tg production in the presence of KI excess and IFN-gamma could explain the development of hypothyroidism after adding iodide in a diet of subjects that already have lymphocytic infiltration and/or mild inflammation in the thyroid gland.

Vascular endothelial growth factor up-regulates the expression of intracellular adhesion molecule-1 in retinal endothelial cells via reactive oxygen species, but not nitric oxide

Background The vascular endothelial growth factor (VEGF) is involved in the initiation of retinal vascular leakage and nonperfusion in diabetes. The intracellular adhesion molecule-1 (ICAM-1) is the key mediator of the effect of VEGFs on retinal leukostasis. Although the VEGF is expressed in an early-stage diabetic retina, whether it directly up-regulates ICAM-1 in retinal endothelial cells (ECs) is unknown. In this study, we provided a new mechanism to explain that VEGF does up-regulate the expression of ICAM-1 in retinal ECs. Methods Bovine retinal ECs (BRECs) were isolated and cultured. Immunohistochemical staining was performed to identify BRECs. The cultured cells were divided into corresponding groups. Then, VEGF (100 ng/ml) and other inhibitors were used to treat the cells. Cell lysate and the cultured supernatant were collected, and then, the protein level of ICAM-1 and phosphorylation of the endothelial nitric oxide synthase (eNOS) were detected using Western blotting. Griess reaction was used to detect nitric oxide (NO). Results Western blotting showed that the VEGF up-regulated the expression of ICAM-1 protein and increased phosphorylation of the eNOS in retinal ECs. Neither the block of NO nor protein kinase C (PKC) altered the expression of ICAM-1 or the phosphorylation of eNOS. The result of the Western blotting also showed that inhibition of phosphatidylinositol 3-kinase (PI3K) or reactive oxygen species (ROS) significantly reduced the expression of ICAM-1. Inhibition of PI3K also reduced phosphorylation of eNOS. Griess reaction showed that VEGF significantly increased during NO production. When eNOS was blocked by L-NAME or PI3K was blocked by LY294002, the basal level of NO production and the increment of NO caused by VEGF could be significantly decreased. Conclusion ROS-NO coupling in the retinal endothelium may be a new mechanism that could help to explain why VEGF induces ICAM-1 expression and the resulting leukostasis in diabetic retinopathy.

Triglyceride-rich lipoprotein lipolysis releases neutral and oxidized FFAs that induce endothelial cell inflammation

Triglyceride-rich lipoprotein (TGRL) lipolysis products provide a pro-inflammatory stimulus that can alter endothelial barrier function. To probe the mechanism of this lipolysis-induced event, we evaluated the pro-inflammatory potential of lipid classes derived from human postprandial TGRL by lipoprotein lipase (LpL). Incubation of TGRL with LpL for 30 min increased the saturated and unsaturated FFA content of the incubation solutions significantly. Furthermore, concentrations of the hydroxylated linoleates 9-hydroxy ocatadecadienoic acid (9-HODE) and 13-HODE were elevated by LpL lipolysis, more than other measured oxylipids. The FFA fractions elicited pro-inflammatory responses inducing TNFalpha and intracellular adhesion molecule expression and reactive oxygen species (ROS) production in human aortic endothelial cells (HAECs). The FFA-mediated increase in ROS was blocked by both the cytochrome P450 2C9 inhibitor sulfaphenazole and NADPH oxidase inhibitors. Compared with linoleate, 13-HODE was found to be a more potent inducer of ROS production in HAECs, an activity that was insensitive to both NADPH oxidase and cytochrome P450 inhibitors. Therefore, although the oxidative metabolism of FFA in endothelial cells can produce inflammatory responses, TGRL lipolysis can also release preformed mediators of oxidative stress (e.g., HODEs) that may influence endothelial cell function in vivo by stimulating intracellular ROS production.

Phosphomannopentaose sulfate (PI-88) inhibits retinal leukostasis in diabetic rat

Retinal leukostasis, mediated by intracellular adhesion molecule-1 (ICAM-1) and vascular endothelial growth factor (VEGF), has been implicated in the pathogenesis of early diabetic retinopathy. Phosphomannopentaose sulfate (PI-88) is a highly sulfonated oligosaccharide which inhibits heparanase activity and competes with heparan sulfate binding to growth factors. In this study, we evaluated whether PI-88 could inhibit retinal leukostasis in strepotzotocin(STZ)-induced diabetic rat and elucidated the possible mechanisms. Diabetes was induced in Sprague–Dawley rats by intraperitoneal injection (i.p.) of STZ. Three months after induction, diabetic rats were administered PI-88 (25 mg/kg body weight) or vehicle solution daily via i.p. for 14 consecutive days. Leukostasis was analyzed on retinal flatmounts by concanavalin A and CD45 immunofluorescence staining. Retinal function was analyzed by electroretinography (ERG). ICAM-1 and VEGF levels in retinas were studied by Western blot and enzyme-linked immunosorbent assay (ELISA) respectively. The systemic administration of PI-88, but not vehicle, significantly decreased the number of adherent leukocytes in retinas by 52.24% ( P < 0.001) and led to significant preservation (about 50%, P < 0.001) of scotopic ERG a- and b-wave amplitudes in treated diabetic rats as compared to those of diabetic control rats. These changes were associated with downregulation of ICAM-1 (45%, P < 0.001) and VEGF (26.83 ± 2.01 versus 40.8 ± 3.24 pg/mg, P < 0.01) in retinas of PI-88 treated diabetic rats as compared to those of diabetic control rats. PI-88 significantly inhibited retinal leukostasis and reversed retinal dysfunction by a mechanism that may include decreased ICAM-1 and VEGF expression in diabetic rats. Our data suggests that PI-88 is a promising agent for the treatment of diabetic retinopathy.

Oncostatin M Enhances the Antiviral Effects of Type I Interferon and Activates Immunostimulatory Functions in Liver Epithelial Cells

Oncostatin M (OSM) is released together with type I interferon (IFN) by activated dendritic cells, suggesting a concerted action of these cytokines in the biological response against infection. We found that OSM increases the antiviral effect of IFN-alpha in Huh7 hepatoma cells infected with hepatitis A or hepatitis C virus and synergizes with IFN-alpha in the induction of antiviral genes. The combination of OSM and IFN-alpha led to upregulation of both STAT1 and STAT3 together with intense and prolonged activation of STAT1, STAT3, and Jak1. OSM with or without IFN-alpha also activated p38 mitogen-activated protein kinase, which is known to enhance transcription of IFN-alpha-inducible genes. Interestingly, OSM combined with IFN-alpha strongly induced immunoproteasome genes and other genes involved in antigen processing and presentation. Moreover, OSM, alone or in combination with IFN-alpha, upregulated relevant innate immunity molecules and increased the expression of intracellular adhesion molecule 1 and interleukin-15 receptor alpha (IL-15Ralpha) in liver cells. Hepatoma cells transfected with a plasmid encoding a viral antigen were able to activate effector T cells when pretreated with IFN-alpha plus OSM but not with each cytokine separately. Also, OSM, more than IFN-alpha, augmented the ability of Huh7 cells to transpresent IL-15 to responding lymphocytes and increased the immunostimulatory activity of liver epithelial cells by presenting a short viral peptide to sensitized cytotoxic T cells. In conclusion, OSM enhances the antiviral effects of type I interferon and cooperates with it in the induction of adaptive immune responses to pathogens. These findings may have therapeutic implications.

Activated protein C prevents hepatic ischaemia–reperfusion injury in rats

Hepatic ischaemia-reperfusion injury (IRI) is a serious complication of liver surgery, especially extended hepatectomy and liver transplantation. Activated protein C (APC), a potent anticoagulant serine protease, has been shown to have cell-protective properties by virtue of its anti-inflammatory and anti-apoptotic activities. The present study was designed to examine the cytoprotective effects of APC in a 60-min warm-IRI rat model. Following a single intravenous injection of APC before reperfusion, APC exerted cytoprotective effects 4 h after reperfusion, as evidenced by: (i) decreased levels of transaminase and improved histological findings of IRI, (ii) reduced infiltration and activation of neutrophils, macrophages and T cells, (iii) reduced expression of tumour necrosis factor-alpha, (iv) reduced expression of P-selectin and intracellular adhesion molecule-1, (v) inhibited coagulation and attenuated sinusoidal endothelial cell injury, (vi) improved hepatic microcirculation and (vii) decreased transferase-mediated dUTP nick end-labelling-positive cells. These effects of APC were observed 4 h but not 24 h after reperfusion. However, multiple injections of APC after reperfusion significantly decreased the levels of transaminase and the activity of myeloperoxidase, and improved histological findings of IRI 24 h after reperfusion. These results suggest that APC is a promising therapeutic option for hepatic warm-IRI; however, multiple injections of APC are necessary to maintain its cell-protective action over the long term.

The melanoma antigen gene and the expression of soluble intercellular adhesion molecule-1 mRNA in Egyptian hepatocellular carcinoma patients: their clinicopathological and prognostic significance

In Egypt, the incidence of Hepatocellular Carcinoma (HCC) is predicted to increase significantly over the next decades due to the high prevalence of Hepatitis C Virus (HCV). This study investigated soluble Intracellular Adhesion Molecule-1 (sICAM-1) and Melanoma Antigen Genes (MAGE-1 and 3) expression in the Peripheral Blood Mononuclear Cells (PBMCs) of HCC patients to evaluate their prognostic significance in early detection of HCC. The study was conducted on 35 HCC patients, ten cirrhotic patients and ten healthy volunteers. MAGE-1 and MAGE-3 transcripts were detected by conventional qualitative Polymerase Chain Reaction (PCR) while sICAM-1 transcripts were traced by quantitative Real Time-PCR (RT-PCR). MAGE-1, MAGE-3 and MAGE-1/3 transcripts were detected in 51.4%, 42.9% and 31.43% of HCC patients, respectively, while all cirrhotic patients and normal controls had negative results. MAGE gene expression was positively correlated to serum a-Fetoprotein (AFP), the stage of HCC and the size of the tumour, but not to age, sex or liver functions. sICAM-1 mRNA was significantly higher in HCC patients than in cirrhotic and normal individuals. These results indicate that routine follow up of sICAM-1 and MAGE-1/3 transcripts in PBMCs of patients with chronic liver disease might be useful in monitoring their possible progress towards malignancy.

Platelet-derived growth factor BB promotes the migration of bone marrow-derived mesenchymal stem cells towards C6 glioma and up-regulates the expression of intracellular adhesion molecule-1

Recent studies have indicated that bone marrow-derived mesenchymal stem cells (BMSCs) have the capacity of migrating towards gliomas. However, few data are available about the molecular mechanism responsible for this migratory capacity. The aim of our study was to investigate the role of platelet-derived growth factor BB (PDGFBB) in the migration of BMSCs towards C6 glioma and evaluate the effect of PDGFBB on the migrating capacity and intercellular adhesion molecule-1 (ICAM-1) expression of BMSCs. The chemokinetic activity of BMSCs in response to C6 glioma-conditioned medium and recombinant rat PDGFBB was analyzed by in vitro migration assay. The effect of PDGFBB on the expression of ICAM-1 was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence. Our data showed that C6 glioma-conditioned medium significantly increased the migration of BMSCs, which could be partially blocked by a PDGFBB neutralizing antibody. Recombinant rat PDGFBB enhanced the migration of BMSCs in a concentration-dependent way from 5 to 50 ng/ml. Moreover, RT-PCR and immunofluorescence showed that 12 h of 20 ng/ml PDGFBB incubation could up-regulate the ICAM-1 expression of BMSCs. Our data also revealed that SB203580, an inhibitor of p38 mitogen-activated protein kinase (MAPK), significantly decreased the PDGFBB-induced migration and ICAM-1 expression of BMSCs. These results demonstrate that PDGFBB contributes to the migration of BMSCs towards C6 glioma and up-regulates the expression of ICAM-1, and that p38MAPK is an important signaling molecule correlating with the signal transduction of PDGFBB-induced migration and ICAM-1 expression of BMSCs.

Anti-Chemokine Autoantibody:Chemokine Immune Complexes Activate Endothelial Cells via IgG Receptors

Our previous studies revealed that the presence in lung fluids of anti-IL-8 autoantibody:IL-8 immune complexes is an important prognostic indicator for the development and outcome of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Anti-IL-8:IL-8 complexes purified from lung edema fluids trigger chemotaxis of neutrophils, induce activation of these cells, and regulate their apoptosis, all via IgG receptor, FcgammaRIIa. Importantly, increased levels of FcgammaRIIa are present in lungs of patients with ARDS, where FcgammaRIIa is partially associated with anti-IL-8:IL-8 complexes. In the current study, we demonstrate the ability of anti-IL-8:IL-8 complexes to promote an inflammatory phenotype of human umbilical vein endothelial cells via interaction with FcgammaRIIa. Human umbilical vein endothelial cells cultured in the presence of the complexes become activated, as shown by increased phosphorylation of ERK, JNK, and Akt, and augmented nuclear translocation of NF-kappaB. Anti-IL-8:IL-8 complexes also up-regulate expression of intracellular adhesion molecule (ICAM)-1 on the cell surface. Furthermore, we detected increased levels of ICAM-1 on lung endothelial cells from mice in which lung injury was induced by generating immune complexes in alveolar spaces. On the other hand, ICAM-1 expression was unchanged in lungs of gamma chain-deficient mice, lacking receptors that interact with immune complexes. Moreover, in lung tissues from patients with ARDS, anti-IL-8:IL-8 complexes were associated with endothelial cells that expressed higher levels of ICAM-1. Our current findings implicate that anti-chemokine autoantibody:chemokine immune complexes, such as IL-8:IL-8 complexes, may contribute to pathogenesis of lung inflammation by inducing activation of endothelial cells through engagement of IgG receptors.

RAGE mediates oxidized LDL-induced pro-inflammatory effects and atherosclerosis in non-diabetic LDL receptor-deficient mice

Receptor for advanced glycation end products (RAGE) plays a pivotal role in the genesis of diabetic vascular diseases. To further explore the mechanisms underlying atherosclerosis under non-diabetic conditions, we examined the effect of RAGE deficiency on atherosclerosis in hyperlipidaemic mice. RAGE-/- mice were crossed with low-density lipoprotein receptor-deficient (LDLr-/-) mice to generate the double knockout (DKO) mice. After feeding with high-fat diet for 12 weeks, aortic atherosclerotic lesions were analysed histologically in these mice. Although there were no differences in serum levels of glucose and known RAGE ligands between DKO and LDLr-/- mice, DKO mice exhibited a significant decrease in the size and macrophage content in atherosclerotic lesions compared with LDLr-/- mice. Expression of intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 in the aorta was lower in DKO mice than in LDLr-/- mice. Fluorescence-based assays revealed that oxidative stress in the vessel wall was attenuated in DKO mice than in LDLr-/- mice. Cell culture experiments revealed that RAGE mediated oxidative LDL-induced activation of p42/44 mitogen-activated protein kinases and oxidative stress in macrophages. Oxidative LDL may be a ligand of RAGE in the hyperlipidaemic state. RAGE inactivation inhibits the atherosclerosis through reducing oxLDL-induced pro-inflammatory responses and oxidative stress in hyperlipidaemia.

Corticosteroid enhances TNF‐α‐mediated leukocyte adhesion to pulmonary microvascular endothelial cells

Some severe asthma patients are characterized by elevated levels of tumor necrosis factor alpha (TNF-alpha) and neutrophilic inflammation in the airways. Although such phenotypic changes in asthma might contribute to corticosteroid refractoriness, the role of TNF-alpha in the process remains unclear. TNF-alpha exerts its biological effects mainly by acting on the vascular endothelium, and thereby upregulates leukocyte recruitment into inflamed tissues. The aim of this study was to investigate the effects of dexamethasone (DEX) on the TNF-alpha-mediated responses of human microvascular endothelial cells from lung blood vessels (HMVEC-LBl) in vitro. HMVEC-LBl were cultured with TNF-alpha in the presence and absence of DEX. The effects of DEX on various TNF-alpha-mediated responses, such as the expressions of chemokines and cellular adhesion molecules, leukocyte adhesion were determined. TNF-alpha significantly induced growth-related oncogene alpha (GRO-alpha), interleukin 8 (IL-8), regulated on activation, normal T-cell expressed and secreted (RANTES) and interferon-inducible protein 10 (IP-10) productions and cell surface expressions of intracellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) on HMVEC-LBl. TNF-alpha-induced GRO-alpha and IL-8 were slightly attenuated by DEX treatment (reaches to 89% and 79%, respectively), whereas expressions of IP-10, ICAM-1 and VCAM-1 were significantly enhanced by the same treatment (up to 172%, 152% and 139%, respectively). Correspondingly, in vitro adhesion of eosinophils and neutrophils to TNF-alpha-treated HMVEC-LBl were significantly enhanced by DEX. Some proinflammatory effects of DEX, a corticosteroid, were found in TNF-alpha-mediated in vitro reactions of pulmonary microvascular endothelial cells, i.e. chemokine productions and leukocyte adhesion. These in vitro results may explain, at least in part, the corticosteroid refractoriness accompanied by a marked increase in TNF-alpha production that is seen in severe asthmatic patients.

Role of Hydrogen Sulfide in the Development of Atherosclerotic Lesions in Apolipoprotein E Knockout Mice

We explored the effect of hydrogen sulfide (H(2)S) on atherosclerotic progression, particularly on intracellular adhesion molecule-1 (ICAM-1) in apolipoprotein-E knockout (apoE(-/-)) mice and human umbilical vein endothelial cells (HUVECs). ApoE(-/-) mice were treated with sodium hydrosulfide (NaHS) or DL-propargylglycine (PPG); HUVECs were pretreated with NaHS. Compared with control mice, apoE(-/-) mice showed decreased plasma H(2)S level and aortic H(2)S production but increased plasma ICAM-1 and aortic ICAM-1 protein and mRNA. Compared with apoE(-/-) mice, apoE(-/-)+NaHS mice showed increased plasma H(2)S level, but decreased size of atherosclerotic plaque and plasma and aortic ICAM-1 levels, whereas apoE(-/-)+PPG mice showed decreased plasma H(2)S level but enlarged plaque size and increased plasma and aortic ICAM-1 levels. NaHS suppressed ICAM-1 expression in tumor necrosis factor (TNF)-alpha-treated HUVECs. NaHS inhibited IkappaB degradation and NF-kappaB nuclear translocation in HUVECs treated with TNF-alpha. The vascular CSE/H(2)S pathway was disturbed in apoE(-/-) mice. H(2)S exerted an antiatherogenic effect and inhibited ICAM-1 expression in apoE(-/-) mice. H(2)S inhibited ICAM-1 expression in TNF-alpha-induced HUVECs via the NF-kappaB pathway.

Filamin B Mediates ICAM-1-driven Leukocyte Transendothelial Migration

During inflammation, the endothelium mediates rolling and firm adhesion of activated leukocytes. Integrin-mediated adhesion to endothelial ligands of the Ig-superfamily induces intracellular signaling in endothelial cells, which promotes leukocyte transendothelial migration. We identified the actin cross-linking molecule filamin B as a novel binding partner for intracellular adhesion molecule-1 (ICAM-1). Immune precipitation as well as laser scanning confocal microscopy confirmed the specific interaction and co-localization of endogenous filamin B with ICAM-1. Importantly, clustering of ICAM-1 promotes the ICAM-1-filamin B interaction. To investigate the functional consequences of filamin B binding to ICAM-1, we used small interfering RNA to reduce filamin B expression in ICAM-1-GFP expressing HeLa cells. We found that filamin B is required for the lateral mobility of ICAM-1 and for ICAM-1-induced transmigration of leukocytes. Reducing filamin B expression in primary human endothelial cells resulted in reduced recruitment of ICAM-1 to endothelial docking structures, reduced firm adhesion of the leukocytes to the endothelium, and inhibition of transendothelial migration. In conclusion, this study identifies filamin B as a molecular linker that mediates ICAM-1-driven transendothelial migration.

Nuclear bile acid receptor farnesoid X receptor meets nuclear factor-κB: New insights into hepatic inflammation

Nuclear bile acid receptor farnesoid X receptor meets nuclear factor-κB: New insights into hepatic inflammation

Endothelial CD81 is a marker of early human atherosclerotic plaques and facilitates monocyte adhesion

In a recent report, we established at the genome-wide level those genes that are specifically upregulated in the endothelium of atherosclerotic plaques in human arteries. As the transcriptome data revealed that mRNA for the tetraspanin family member CD81 is significantly and specifically upregulated in the endothelium overlying early atheroma, we set out to validate these results on the protein level, and investigate the functional consequences of CD81 upregulation. Immunohistochemical analysis in an independent set of donor arteries verified in the endothelium of early human atherosclerotic lesions the enhanced expression of CD81, which appears oxidative stress-dependent. Using lentiviral overexpression and silencing in human umbilical endothelial cells, we established in an in vitro flow adhesion assay that elevated endothelial CD81 is associated with increased monocyte adhesion to non-activated CD81-transduced endothelial cells, approaching the levels normally only attained after tumour necrosis factor alpha stimulation. The CD81 effect was dependent on both intracellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), as it was abolished in the presence of a mixture of anti-ICAM-1 and anti-VCAM-1 antibodies. Flow cytometry revealed that increased CD81 levels did not increase total ICAM-1 and VCAM-1 surface expression. Instead, it concentrated the available adhesion molecules into membrane clusters, as indicated by confocal and electron microscopy. CD81 also colocalized with ICAM-1 and VCAM-1 in the adhesion rings around bound monocytes. Endothelial CD81 upregulated in early human atheroma has the potential to play a crucial role in the initial stages of atherosclerotic plaque formation by increasing monocyte adhesion prior to the full-blown inflammatory response.

Systemic not just mesenteric lymph causes acute lung injury following hemorrhagic shock

Recent studies have demonstrated a significant role for factor(s) present in mesenteric lymph following hemorrhagic shock in the etiology of post-hemorrhagic shock acute lung injury (ALI). Earlier studies have shown that ischemia-reperfusion insults to systemic tissue beds can also result in ALI. We therefore hypothesized that factors in systemic lymph may cause lung injury after hemorrhagic shock; this was studied in vitro. Confluent human pulmonary microvascular endothelial cells (HMVEC) maintained in a 2-chamber cell culture system were exposed to systemic lymph obtained from dogs exposed to sham operation or hemorrhagic shock and resuscitation. HMVEC injury was indexed by apoptosis (% Apo, Hoechst staining) and permeability to albumin (microL/min). HMVEC activation was indexed by surface expression of intracellular adhesion molecule-1 (ICAM-1) expressed as mean fluorescence intensity using flow cytometry. There was a 2-fold increase in HMVEC permeability and apoptotic rate after incubation with postshock systemic lymph. A similar effect was noted with ICAM expression, which was 2.5 fold higher after incubation with postshock lymph. These biologic effects were first noted with the 120-minute postresuscitation lymph. Lymph obtained during shock or from sham animals had no effect. Pulmonary microvascular endothelial dysfunction is evident after exposure to lymph obtained from systemic sites after hemorrhagic shock. The "unique" properties ascribed to post-hemorrhagic shock mesenteric lymph in causing ALI seem to be shared by lymph from systemic sites as well.

Nitro-oleic acid protects the mouse kidney from ischemia and reperfusion injury

Nitroalkene derivatives of linoleic acid (nitrolinoleic acid; LNO2) and nitro-oleic acid (OA-NO2) are endogenous lipid products with potent anti-inflammatory properties. The present study was undertaken to evaluate the therapeutic potential of OA-NO2 in a mouse model of renal ischemia-reperfusion (I/R) injury. B6129SF2/J mice were subjected to bilateral renal ischemia for 30 min, followed by 24 h of reperfusion. Fifty minutes after ischemia, mice received intraperitoneal (ip) injections of OA-NO2 (500 microg/kg; I/R OA-NO2), vehicle for OA-NO2 (i.e., 0.8 ml/kg ethanol; I/R veh), or oleic acid (500 microg/kg; I/R OA) every 6 h during the 24-h recovery period. A sham-operated group was not subjected to ischemia and received 0.8 ml/kg ethanol ip every 6 h during the 24-h recovery period (sham veh). While plasma urea and creatinine were elevated (P<0.05) in I/R veh vs. sham veh mice, the severity was less (P<0.05) in I/R OA-NO2 animals. Indices of histological damage, polymorphonucleocyte infiltration, together with expression of intracellular adhesion molecule-1, interleukin-1beta, and tumor necrosis factor-alpha, p47(phox), and gp91(phox) were greater in I/R veh vs. sham veh mice, but were attenuated (P<0.05) in I/R OA-NO2 animals. Because indices of renal dysfunction were similar between I/R veh and I/R OA mice (P>0.05), but less (P<0.05) in I/R OA-NO2 animals compared with both groups, protection from bilateral renal ischemia is afforded by the nitrated but not free form of oleic acid. Together, delayed administration of nitrated fatty acid OA-NO2 attenuates renal I/R injury in the mouse likely via inhibition of the inflammatory response.

LPS induces inflammatory responses in human aortic vascular smooth muscle cells via Toll-like receptor 4 expression and nitric oxide production

Inflammation is an important event in the development of vascular diseases such as hypertension, atherosclerosis, and restenosis. In addition, the stimulation of Toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) induces the release of critical proinflammatory cytokines that activate potent immune responses. In this study, LPS was found to induce TLR4 expression and increased nitric oxide (NO) production by increasing the expression of inducible nitric oxide synthase (iNOS). Furthermore, LPS was found to induce interleukin (IL)-8 and vascular endothelial growth factor (VEGF) production, as well as intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression. Taken together, these results indicate that LPS induces inflammatory responses in HASMC. Moreover, NOS inhibitor (L-NAME) and anti-TLR 4 mAb reduced the LPS-induced NO, IL-8 and VEGF production and ICAM-1 expression. Additionally, TLR4 expression was reduced by NOS inhibitor. Taken together, these results indicate that LPS-induced inflammatory responses are regulated by TLR4 expression and NO production.