Variation of adhesion molecule expression on human umbilical vein endothelial cells upon multiple cytokine application

Immune cells and inflammatory mediators cause endothelial dysfunction in a vascular microphysiological system

Functional assessment of endothelium serves as an important indicator of vascular health and is compromised in vascular disorders including hypertension, atherosclerosis, and preeclampsia. Endothelial dysfunction in these cases is linked to dysregulation of the immune system involving both changes to immune cells and increased secretion of inflammatory cytokines. Herein, we utilize a well-established microfluidic device to generate a 3-dimensional vascular microphysiological system (MPS) consisting of a tubular blood vessel lined with human umbilical vein endothelial cells (HUVECs) to evaluate endothelial function measured via endothelial permeability and Ca2+ signaling. We evaluated the effect of a mixture of factors associated with inflammation and cardiovascular disease (TNFα, VEGF-A, IL-6 at 10 ng ml-1 each) on vascular MPS and inferred that inflammatory mediators contribute to endothelial dysfunction by disrupting the endothelial barrier over a 48 hour treatment and by diminishing coordinated Ca2+ activity over a 1 hour treatment. We also evaluated the effect of peripheral blood mononuclear cells (PBMCs) on endothelial permeability and Ca2+ signaling in the HUVEC MPS. HUVECs were co-cultured with PBMCs either directly wherein PBMCs passed through the lumen or indirectly with PBMCs embedded in the supporting collagen hydrogel. We revealed that phytohemagglutinin (PHA)-M activated PBMCs cause endothelial dysfunction in MPS both through increased permeability and decreased coordinated Ca2+ activity compared to non-activated PBMCs. Our MPS has potential applications in modeling cardiovascular disorders and screening for potential treatments using measures of endothelial function.

Activation of human vascular endothelium in melanoma metastases induces ICAM-1 and E-selectin expression and results in increased infiltration with effector lymphocytes

Lymphocytic infiltration into melanoma tissue is an important prerequisite for effective antitumoral immunity. However, analysis of human metastatic melanoma has shown that leucocyte adhesion receptor expression on melanoma blood vessels is very low or absent, thereby impairing the entry of cytotoxic lymphocytes into tumor tissue. We hypothesized that adhesion molecules can be induced on melanoma vasculature allowing better infiltration of cytotoxic lymphocytes. Quantitative real-time PCR and immunofluorescence staining indicated that the adhesion molecules ICAM-1 (CD54) and E-selectin (CD62E) can be significantly induced by intralesional application of TNF alpha in tissue from human melanoma metastases either in vitro or in vivo when grafted onto immunodeficient NSG (NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ) mice that preserved human vessels. Furthermore, activated human autologous CD3⁺ lymphocytes were injected intravenously into mice bearing melanoma xenografts treated with TNF-α or PBS in addition to the leucocyte chemoattractant TARC (CCL17). Significantly increased numbers of CD8⁺ cells were detected in TNF-α-treated melanoma metastases compared with PBS-treated controls. In addition, tumor cell apoptosis was enhanced and melanoma cell proliferation reduced as shown by TUNEL assay and KI-67 staining. We conclude that adhesion molecules can be induced on human melanoma vasculature resulting in significantly improved homing of activated autologous cytotoxic T cells to melanoma tissue and inhibition of melanoma cell proliferation. These observations should be considered when designing protocols for immunotherapy of malignant melanoma.

CX3CL1 binding protein-2 (CBP2) of Plasmodium falciparum binds nucleic acids

Several exported Plasmodium falciparum (Pf) proteins contribute to malaria biology through their involvement in cytoadherence, immune evasion and host cell remodelling. Many of these exported proteins and other host molecules are present in iRBC (infected red blood cell) generated extracellular vesicles (EVs), which are responsible for host cell modification and parasite development. CX3CL1 binding proteins (CBPs) present on the surface of iRBCs have been reported to contribute to cytoadhesion by binding with the chemokine 'CX3CL1' via their extracellular domains. Here, we have characterized the cytoplasmic domain of CBP2 to understand its function in parasite biology using biochemical and biophysical methods. Recombinant cytoplasmic CBP2 (cCBP2) binds nucleic acids showing interaction with DNA/RNA. cCBP2 shows dimer formation under non-reducing conditions highlighting the role of disulphide bonds in its oligomerization while ATP binding leads to structural changes in the protein. In vitro interaction studies depict its binding with a Maurer's cleft resident protein 'PfSBP1', which is influenced by ATP binding of cCBP2. Our results suggest CBP2 as a two-transmembrane (2TM) receptor responsible for targeting EVs and delivering cargo to host endothelial cells. We propose CBP2 as an important molecule having roles in cytoadherence and immune modulation through its extracellular and cytoplasmic domains respectively.

Network of Mediators for Vascular Inflammation and Leakage Is Dysbalanced during Cytoreductive Surgery for Late-Stage Ovarian Cancer

Background

Cytoreductive surgery (CS) in late-stage ovarian cancer patients is often challenging due to extensive volume shifts, and high fluid intake may provoke postoperative complications. Expression of vasoactive mediators is altered in cancer patients, which may affect systemic vascular function. We sought to assess how serum levels of vasoactive markers and mediators change during CS in ovarian cancer.

Methods

Following IRB approval and informed consent, pre- and postoperative serum samples were analyzed in 26 late-stage ovarian cancer patients using multiplex protein arrays and ELISA.

Results

The proinflammatory cytokines and chemokines IL-6, IL-8, and CCL2 were significantly elevated after 24 hrs compared to the baseline values, with IL-6 and IL-8 being most prominently increased. While ANGPT1 remained unchanged after surgery, its competitive antagonist ANGPT2 was significantly increased. In contrast, serum levels of the ANGPT receptor TIE2 were decreased to 0.6 of the baseline values. While VEGF-D, E-selectin, P-selectin, ICAM-1, and PECAM-1 remained unchanged, serum activity of both thrombomodulin and syndecan-1 was significantly increased following surgery.

Conclusion

We identified a regulatory network of acute-phase reaction during CS in late-stage ovarian cancer. This suggests that IL-6 exerts positive regulation of other proinflammatory mediators and, by upregulating ANGPT2 and suppressing ANGPT1, induces a serum profile that promotes vascular leakage. This may contribute to the observed hemodynamic alterations during CS procedures.

E-Selectin and markers of HIV disease severity, inflammation and coagulation in HIV-infected treatment-naïve individuals

Background

E-selectin has been shown to play a role in atherosclerosis and to be increased in HIV-infected individuals due to chronic immune activation. There is a paucity of studies on E-selectin in HIV-infected treatment-naïve individuals.

Objectives

This study aimed to determine whether E-selectin levels were increased in HIV-infected treatment-naïve individuals and whether these correlated with markers of disease severity, inflammation and coagulation to determine if this population is at risk for cardiovascular disease (CVD).

Methods

E-selectin levels were determined in 114 HIV-infected treatment-naive and 66 HIV-negative individuals, compared between groups and correlated with markers of disease severity, inflammation and coagulation.

Results

There were statistically significant differences (p<0.01) in levels of WCC, CD4⁺ count, %CD38/8, albumin, IgG, hsCRP and D-dimer between groups and no statistically significant differences in E-selectin (p=0.84) and fibrinogen (p=0.65) levels. E-selectin correlated with age (p=0.02) and gender (p=0.01).

Conclusion

E-selectin was a poor marker in this setting. There was no correlation with any of the markers of disease severity, inflammation and coagulation. E-selectin is most likely raised in an acute inflammatory setting, rather than chronic stage of HIV-infection. We recommend that other markers be utilized to identify patients at increased risk of CVD; as these were significantly increased untreated in individuals.

RNA expression profiling of renal allografts in a nonhuman primate identifies variation in NK and endothelial gene expression

RNA transcript expression estimates are a promising method to study the mechanisms and classification of renal allograft rejections. Here we use the Nanostring platform to profile RNA expression in renal allografts in a nonhuman primate (NHP), the Cynomolgus monkey. We analyzed protocol and indication 278 archival renal allograft samples, both protocol and indication from 76 animals with diagnoses of chronic antibody-mediated rejection (CAMR), acute cellular rejection (TCMR), and MIXED (both CAMR and TCMR), plus normals and samples with no pathological rejection using a Cynomolgus-specific probe set of 67 genes. Analysis identified RNA expression heterogeneity of endothelial and NK genes within CAMR and TCMR, including the stages of CAMR. Three factors were partitioned into additional groups. One group with the longest allograft survival time is pure CAMR without NK or CD3. Three mixed groups show variation in NK and CD3. TCMR was split into 2 groups with variation in NK genes. Additional validation of the complete gene-set correlated many of the genes with diagnoses of CAMR, MIXED, and TCMR rejections and with Banff histologic criteria defined in human subjects. These NHP data demonstrate the utility of RNA expression profiling to identify additional heterogeneity of endothelial and NK RNA gene expressions.

Platelets from flowing blood attach to the inflammatory chemokine CXCL16 expressed in the endothelium of the human vessel wall

Endothelial chemokine CXC motif ligand 16 (CXCL16) expression is associated with atherosclerosis, while platelets, particularly those attaching to atherosclerotic plaque, contribute to all stages of athero-sclerotic disease. This investigation was designed to examine the role of CXCL16 in capturing platelets from flowing blood. CXCL16 was expressed in human atherosclerotic plaques, and lesion severity in human carotid endarterectomy specimens was positively correlated with CXCL16 levels. CXCL16 expression in plaques was co-localised with platelets deposited to the endothelium. Immobilised CXCL16 promoted CXCR6-dependent platelet adhesion to the human vessel wall, endothelial cells and von Willebrand factor during physiologic flow. At low shear, immobilised CXCL16 captured platelets from flowing blood. It also induced irreversible platelet aggregation and a rise in intra-platelet calcium levels. These results demonstrate that endothelial CXCL16’s action on platelets is not only limited to platelet activation, but that immobilised CXCL16 also acts as a potent novel platelet adhesion ligand, inducing platelet adhesion to the human vessel wall.

Naïve T cells are activated by autologous HCMV-infected endothelial cells through NKG2D and can control HCMV transmission in vitro

Apart from classical antigen-presenting cells (APCs) like dendritic cells and macrophages, there are semiprofessional APCs such as endothelial cells (ECs) and Langerhans' cells. Human cytomegalovirus (HCMV) infects a wide range of cell types including the ECs which are involved in the trafficking and homing of T cells. By investigating the interaction of naïve T cells obtained from HCMV-seronegative umbilical cord blood with autologous HCMV-infected human umbilical vein ECs (HUVECs), we could show that the activation of naïve T cells occurred after 1 day of peripheral blood mononuclear cell (PBMC) exposure to HCMV-infected HUVECs. The percentage of activated T cells increased over time and the activation of naïve T cells was not induced by either autologous uninfected HUVECs or by autologous HCMV-infected fibroblasts. The activation of T cells occurred also when purified T cells were co-cultured with HCMV-infected HUVECs. In addition, in most of the donors only CD8⁺ T cells were activated, when the purified T cells were exposed to HCMV-infected HUVECs. The activation of naïve T cells was inhibited when the NKG2D receptor was blocked on the surface of T cells and among the different NKG2D ligands, we identified two ligands (ULBP4 and MICA) on HCMV-infected HUVECs which might be the interaction partners of the NKG2D receptor. Using a functional cell culture assay, we could show that these activated naïve T cells specifically inhibited HCMV transmission. Altogether, we identified a novel specific activation mechanism of naïve T cells from the umbilical cord by HCMV-infected autologous HUVECs through interaction with NKG2D.

The impact of acute high-intensity interval exercise on biomarkers of cardiovascular health in type 2 diabetes

PURPOSE

High-intensity interval training (HIIT) interventions improve cardiovascular health, yet the acute effects on circulating and functional biomarkers of cardiovascular function are unclear in individuals with type 2 diabetes (T2D). To explore this, we conducted two investigations to examine the acute response to HIIT in individuals with T2D.

METHODS

Study 1 measured blood pressure, endothelial-dependent dilation, circulating measures of endothelial activation, and troponin T, 30 min and 2 h after HIIT (7 × 1-min intervals) in T2D (n = 8) and age-matched normoglycemic controls (CTL; n = 8). Study 2 assessed circulating measures of endothelial activation and troponin T, 30 min, and 24 h after HIIT (10 × 1-min intervals) in ten previously trained T2D men.

RESULTS

In study 1, markers of endothelial function and activation within the first 2 h after HIIT did not differ from baseline between T2D and CTL participants, except at 30 min after HIIT for glucose, which was reduced more in T2D than CTL (by -0.8 ± 1.2 mmol/L, p = 0.04), and VCAM-1, which was reduced more 30 min after HIIT in CTL compared to T2D (by -187 ± 221 ng/mL, p = 0.05). Study 2 saw no significant difference in any circulating markers of endothelial activation and troponin T, 30 min, and 24 h after HIIT in trained T2D males.

CONCLUSION

Exploratory findings from these two studies suggest that acute HIIT does not substantially alter circulating and functional markers of cardio(vascular) health in individuals with T2D who are unaccustomed (study 1) and accustomed to HIIT (study 2).

Cultures and co-cultures of human blood mononuclear cells and endothelial cells for the biocompatibility assessment of surface modified AISI 316L austenitic stainless steel

Samples of AISI 316L austenitic stainless steel were subjected either to grinding and polishing procedure, or to grinding and then low temperature glow-discharge nitriding treatment, or to grinding, nitriding and subsequently coating with collagen-I. Nitrided samples, even if only ground, show a higher corrosion resistance in PBS solution, in comparison with ground and polished AISI 316L. Biocompatibility was evaluated in vitro by incubating the samples with either peripheral blood mononuclear cells (PBMC) or human umbilical vein endothelial cells (HUVEC), tested separately or in co-culture. HUVEC-PBMC co-culture and co-incubation of HUVEC with PBMC culture medium, after the previous incubation of PBMC with metallic samples, allowed to determine whether the incubation of PBMC with the different samples might affect HUVEC behaviour. Many biological parameters were considered: cell proliferation, release of cytokines, matrix metalloproteinases (MMPs) and sICAM-1, gelatinolytic activity of MMPs, and ICAM-1 protein expression. Nitriding treatment, with or without collagen coating of the samples, is able to ameliorate some of the biological parameters taken into account. The obtained results point out that biocompatibility may be successfully tested in vitro, using cultures of normal human cells, as blood and endothelial cells, but more than one cell line should be used, separately or in co-culture, and different parameters should be determined, in particular those correlated with inflammatory phenomena.

Infected erythrocyte-derived extracellular vesicles alter vascular function via regulatory Ago2-miRNA complexes in malaria

Malaria remains one of the greatest public health challenges worldwide, particularly in sub-Saharan Africa. The clinical outcome of individuals infected with Plasmodium falciparum parasites depends on many factors including host systemic inflammatory responses, parasite sequestration in tissues and vascular dysfunction. Production of pro-inflammatory cytokines and chemokines promotes endothelial activation as well as recruitment and infiltration of inflammatory cells, which in turn triggers further endothelial cell activation and parasite sequestration. Inflammatory responses are triggered in part by bioactive parasite products such as hemozoin and infected red blood cell-derived extracellular vesicles (iRBC-derived EVs). Here we demonstrate that such EVs contain functional miRNA-Argonaute 2 complexes that are derived from the host RBC. Moreover, we show that EVs are efficiently internalized by endothelial cells, where the miRNA-Argonaute 2 complexes modulate target gene expression and barrier properties. Altogether, these findings provide a mechanistic link between EVs and vascular dysfunction during malaria infection.

Correlation of E-selectin concentrations with carotid intima-media thickness and cardio-metabolic profile of mixed ancestry South Africans: a cross-sectional study

Background E-selectin, an adhesion molecule, is a specific marker of endothelial dysfunction. High concentrations have been reported in type 2 diabetes and disorders with high risk of cardiovascular disease (CVD). Measurement of carotid intima-media thickness (CIMT) is a surrogate marker of early atherosclerosis. We examined the relationship between E-selectin concentrations, CIMT and cardio-metabolic traits in normo- and hyperglycaemic mixed ancestry South Africans. Methods E-selectin concentrations were determined in 308 subjects from the Cape Town Bellville South Community-based study on a mixed ancestry population. Their correlation with CIMT and cardio-metabolic profile used robust correlations and linear regression models. Results E-selectin concentrations were significantly higher in the hyperglycaemic (median 139.8 µg/L) compared to the normoglycaemic group (median 118.8 µg/L), ( p = 0.0007). Significant differences between the two groups were found for markers of glycaemia and adiposity, but not for CIMT. Significant correlations were found between E-selectin and age, markers of glycaemia and inflammation, central obesity and lipid variables. Associations remained significant only with age, hyperglycaemia and C-reactive protein in robust linear regression models. In similar regressions models, age and gender were the main predictors of CIMT, which was not associated with E-selectin. Conclusions E-selectin concentrations in this study were associated with hyperglycaemia, possibly reflecting early endothelial damage. However, E-selectin was not useful to assess CIMT, a marker of subclinical atherosclerosis, which appeared to be determined by ageing and male gender.

Chebulagic acid inhibits the LPS-induced expression of TNF-α and IL-1β in endothelial cells by suppressing MAPK activation

Inflammatory response in the vasculature, including the overexpression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β, has been demonstrated to increase the risk of thrombosis development. Chebulagic acid (CA) is a key chemical component in the traditional Mongolian anti-thrombotic drug Garidi-13, and has been suggested to exert anti-inflammatory and anti-infective effects. The present study aimed to evaluate the regulatory impact of CA on a number of biological processes, including lipopolysaccharide (LPS)-induced inflammation, LPS-promoted mitogen-activated protein kinase (MAPK) activation and the expression of toll-like receptor (TLR)4 in EA.hy926 human endothelial cells. The results indicated that CA significantly inhibited the LPS-induced upregulation of TNF-α and IL-1β in a dose- and time-dependent manner. Furthermore, LPS-activated MAPK signaling was inhibited by CA treatment in the EA.hy926 cells. However, TLR4, which serves a key function in LPS-induced inflammation as the receptor of LPS, was not regulated by the CA treatment. In summary, the results of the present study indicate that CA inhibits the LPS-induced promotion of TNF-α and IL-1β in endothelial cells by suppressing MAPK activation, which may contribute to the anti-thrombotic effect of Garidi-13.

Immune imbalance in nasal polyps of Caucasian chronic rhinosinusitis patients is associated with a downregulation of E-selectin

Chronic rhinosinusitis with nasal polyps (CRSwNP) in Caucasians is a chronic Th2 inflammatory disease of the nasal and paranasal mucosa and the recruitment of leukocytes to the site of inflammation is poorly understood. We studied mRNA and protein expression profiles of adhesion molecules in nasal polyp and associated inferior turbinate tissues using molecular, biochemical, and immunohistological methods. Analysis showed a strongly decreased E-selectin expression in nasal polyps with a significant difference between eosinophil and neutrophil counts in nasal polyps and balanced counts in inferior turbinates. E-selectin expression is known to be downregulated in a Th2 milieu and has an essential role in immunosurveillance by locally activating neutrophil arrest and migratory function. A downregulation of E-selectin may come along with an immune imbalance in Caucasian nasal polyps due to a significant inhibition of neutrophil recruitment. Therefore, we suggest that an upregulation of E-selectin and the associated influx of neutrophils may play a significant role in the resolution of inflammation as well as for the pathophysiology of nasal polyps of Caucasian chronic rhinosinusitis patients.

Soluble adhesion molecules correlate with surface expression in an in vitro model of endothelial activation

Endothelial activation is a pivotal event in the development and progression of inflammation. Central to endothelial activation is the up-regulation of cellular adhesion molecules (CAMs) including E-selectin (CD62E), ICAM-1 (CD54), VCAM-1 (CD106) and PECAM-1 (CD31). These CAMs are also found in soluble forms (sCAMs). In this in vitro study of endothelial activation, we examined whether the levels of sCAMs correlate with the endothelial surface expression of CAMs in a dose-dependent and time-dependent manner. Such a correlation would support the use of sCAMs as surrogate markers for endothelial activation in inflammatory conditions. Human umbilical vein endothelial cells (HUVEC) were cultured with various concentrations of TNF-α for 8 hr and at a fixed concentration of TNF-α for various durations. The levels of soluble and surface-bound E-selectin, ICAM-1, VCAM-1 and PECAM-1 were quantified by flow cytometry. TNF-α stimulation increased CAM and sCAM expression in a dose-dependent and time-dependent manner. There was a significant positive correlation between the levels of ICAM-1 and sICAM-1 and between the levels of VCAM and sVCAM-1 in both the dose-response and time-response experiments. A positive correlation between the levels of E-selectin and sE-selectin was observed in the time-response experiment. This study supports the use of sCAMs as potential biomarkers of endothelial activation. In particular, the use of sICAM-1, sVCAM-1 and sE-selectin seems promising.

Tumour necrosis factor α enhances CCL2 and ICAM-1 expression in peripheral nerve microvascular endoneurial endothelial cells

Recruitment and trafficking of autoreactive leucocytes across the BNB (blood-nerve barrier) is an early pathological insult in GBS (Guillain-Barré syndrome), an aggressive autoimmune disorder of the PNS (peripheral nervous system). Whereas the aetiology and pathogenesis of GBS remain unclear, pro-inflammatory cytokines, including TNFα (tumour necrosis factor α), are reported to be elevated early in the course of GBS and may initiate nerve injury by activating the BNB. Previously, we reported that disrupting leucocyte trafficking in vivo therapeutically attenuates the course of an established animal model of GBS. Here, PNMECs (peripheral nerve microvascular endothelial cells) that form the BNB were harvested from rat sciatic nerves, immortalized by SV40 (simian virus 40) large T antigen transduction and subsequently challenged with TNFα. Relative changes in CCL2 (chemokine ligand 2) and ICAM-1 (intercellular adhesion molecule 1) expression were determined. We report that TNFα elicits marked dose- and time-dependent increases in CCL2 and ICAM-1 mRNA and protein content and promotes secretion of functional CCL2 from immortalized and primary PNMEC cultures. TNFα-mediated secretion of CCL2 promotes, in vitro, the transendothelial migration of CCR2-expressing THP-1 monocytes. Increased CCL2 and ICAM-1 expression in response to TNFα may facilitate recruitment and trafficking of autoreactive leucocytes across the BNB in autoimmune disorders, including GBS.

Alpha-tocopherol and BAY 11-7082 reduce vascular cell adhesion molecule in human aortic endothelial cells

BACKGROUND

In endothelial dysfunction, vascular cell adhesion molecule-1 (VCAM-1), E-selectin and intercellular adhesion molecule-1 (ICAM-1) expression (collectively termed cell adhesion molecules; CAMs) increase at sites of atherosclerosis and are stimulated by proinflammatory cytokines such as tumor necrosis factor-α (TNF-α).

METHODS

We evaluated the effect of alpha-tocopherol (AT; 10-150 µM) and BAY 11-7082 (BAY; 0.1 or 1 µM) on CAMs mRNA expression as well as their protein in soluble release form (sCAMs) in human aortic endothelial cells (HAECs) activated by TNF-α (1 or 10 ng/ml). Also, we determined the extent of lymphocyte adhesion to activated HAECs.

RESULTS

BAY reduced VCAM-1, E-selectin and ICAM-1 mRNA expression by 30, 30 and 10%, respectively. Furthermore, protein reduction of sVCAM-1 by 70%, sE-selectin by 51% and sICAM-1 by 25% compared to HAECs stimulated by TNF-α was observed (p < 0.05). AT (50, 75 and 150 µM) decreased VCAM-1 mRNA expression by 30% and sVCAM-1 protein by 33% compared to HAECs stimulated by TNF-α (p < 0.05). TNF-α-activated HAEC adhesion to human Jurkat T lymphocytes was higher compared to nonactivated HAECs (p < 0.05). BAY (2 and 5 µM) reduced this lymphocyte adhesion (p < 0.05).

CONCLUSION

BAY reduces all the CAMs studied as well as cell adhesion, while AT selectively inhibits VCAM-1; both induce endothelial dysfunction improvement.

Vascular effects of glycoprotein130 ligands--part I: pathophysiological role

The vessel wall is no longer considered as only an anatomical barrier for blood cells but is recognized as an active endocrine organ. Dysfunction of the vessel wall occurs in various disease processes including atherosclerosis, hypertension, peripheral artery disease, aneurysms, and transplant and diabetic vasculopathies. Different cytokines were shown to modulate the behavior of the cells, which constitute the vessel wall such as immune cells, endothelial cells and smooth muscle cells. Glycoprotein 130 (gp130) is a common cytokine receptor that controls the activity of a group of cytokines, namely, interleukin (IL)-6, oncostatin M (OSM), IL-11, ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine (CLC), IL-27, and neuropoietin (NP). Gp130 and associated cytokines have abundantly diverse functions. Part I of this review focuses on the pathophysiological functions of gp130 ligands. We specifically describe vascular effects of these molecules and discuss the respective underlying molecular and cellular mechanisms.

Interleukin-33 induces expression of adhesion molecules and inflammatory activation in human endothelial cells and in human atherosclerotic plaques

OBJECTIVE

Interleukin (IL)-33 is the most recently described member of the IL-1 family of cytokines and it is a ligand of the ST2 receptor. While the effects of IL-33 on the immune system have been extensively studied, the properties of this cytokine in the cardiovascular system are much less investigated. Methods/Results- We show here that IL-33 promoted the adhesion of human leukocytes to monolayers of human endothelial cells and robustly increased vascular cell adhesion molecule-1, intercellular adhesion molecule-1, endothelial selectin, and monocyte chemoattractant protein-1 protein production and mRNA expression in human coronary artery and human umbilical vein endothelial cells in vitro as well as in human explanted atherosclerotic plaques ex vivo. ST2-fusion protein, but not IL-1 receptor antagonist, abolished these effects. IL-33 induced translocation of nuclear factor-κB p50 and p65 subunits to the nucleus in human coronary artery endothelial cells and human umbilical vein endothelial cells and overexpression of dominant negative form of IκB kinase 2 or IκBα in human umbilical vein endothelial cells abolished IL-33-induced adhesion molecules and monocyte chemoattractant protein-1 mRNA expression. We detected IL-33 and ST2 on both protein and mRNA level in human carotid atherosclerotic plaques.

CONCLUSIONS

We hypothesize that IL-33 may contribute to early events in endothelial activation characteristic for the development of atherosclerotic lesions in the vessel wall, by promoting adhesion molecules and proinflammatory cytokine expression in the endothelium.

MRI of inducible P-selectin expression in human activated platelets involved in the early stages of atherosclerosis

The noninvasive imaging of atherosclerotic plaques at an early stage of atherogenesis remains a major challenge for the evaluation of the pathologic state of patients at high risk of acute coronary syndromes. Recent studies have emphasized the importance of platelet-endothelial cell interactions in atherosclerosis-prone arteries at early stages, and the prominent role of P-selectin in the initial loose contact between platelets and diseased vessel walls. A specific MR contrast agent was developed here for the targeting, with high affinity, of P-selectin expressed in large amounts on activated platelets and endothelial cells. For this purpose, PEGylated dextran/iron oxide nanoparticles [PEG, poly(ethylene glycol)], named versatile ultrasmall superparamagnetic iron oxide (VUSPIO) particles, labeled with rhodamine were coupled to an anti-human P-selectin antibody (VH10). Flow cytometry and microscopy experiments on human activated platelets were highly correlated with MRI (performed at 4.7 and 0.2 T), with a 50% signal decrease in T(2) and T(1) values corresponding to the strong labeling of activated vs resting platelets. The number of 1000 VH10-VUSPIO nanoparticles attained per activated platelet appeared to be optimal for the detection of hypo- and hyper-signals in the platelet pellet on T(2) - and T(1) -weighted MRI. Furthermore, in vivo imaging of atherosclerotic plaques in ApoE mice at 4.7 T showed a spatial resolution adapted to the imaging of intimal thickening and a hypo-signal at 4.7 T, as a result of the accumulation of VH10-VUSPIO nanoparticles in the plaque. Our work provides support for the further assessment of the use of VH10-VUSPIO nanoparticles as a promising imaging modality able to identify the early stages of atherosclerosis with regard to the pertinence of both the target and the antibody-conjugated contrast agent used.

Integrated pathways for neutrophil recruitment and inflammation in leprosy

Neutrophil recruitment is pivotal to the host defense against microbial infection, but it also contributes to the immunopathology of disease. We investigated the mechanism of neutrophil recruitment in human infectious disease by means of bioinformatic pathways analysis of the gene expression profiles in the skin lesions of leprosy. In erythema nodosum leprosum (ENL), which occurs in patients with lepromatous leprosy and is characterized by neutrophil infiltration in lesions, the most overrepresented biological functional group was cell movement, including E-selectin, which was coordinately regulated with interleukin 1beta (IL-1beta). In vitro activation of Toll-like receptor 2 (TLR2), up-regulated in ENL lesions, triggered induction of IL-1beta, which together with interferon gamma induced E-selectin expression on and neutrophil adhesion to endothelial cells. Thalidomide, an effective treatment for ENL, inhibited this neutrophil recruitment pathway. The gene expression profile of ENL lesions comprised an integrated pathway of TLR2 and Fc receptor activation, neutrophil migration, and inflammation, providing insight into mechanisms of neutrophil recruitment in human infectious disease.

Interferon-gamma limits Th1 lymphocyte adhesion to inflamed endothelium: a nitric oxide regulatory feedback mechanism

CD4(+) T helper (Th1 and Th2) cell localization to a site of inflammation is important for the development, maintenance and regulation of an immune response. The factors that regulate Th1 and Th2 cell recruitment into tissue are not fully understood. The aim of the present study was to examine the effect of different cytokine microenvironments on the recruitment of Th1 and Th2 lymphocytes into tissue. Fluorescently labelled Th1 or Th2 lymphocyte-endothelial interactions were observed via intravital microscopy of the cytokine-treated cremaster muscle. Our results show that TNF-alpha alone is sufficient to maximally recruit Th1 cells. Surprisingly, treatment with TNF-alpha + IFN-gamma significantly decreased Th1 adhesion and emigration in comparison to TNF-alpha treatment alone. The decreased adhesion of Th1 cells in response to TNF-alpha + IFN-gamma reflected a decreased ability to bind to ICAM-1 and was iNOS-dependent. This phenomenon was not observed with Th2 cells. These results suggest that IFN-gamma may play a key immunomodulatory role in the recruitment of different T lymphocyte subsets. Indeed, blockade of IFN-gamma or iNOS function during the Th1-mediated contact hypersensitivity response resulted in an acceleration and exacerbation of the late-phase inflammatory response.

Validity of a patient-derived system of tissue-specific human endothelial cells: interleukin-6 as a surrogate marker in the coronary system

The aim of our study was to evaluate the relevance of tissue- and species-specific endothelial cells (EC) to study EC-dependent mechanisms in inflammatory-mediated tissue injury. We established an isolation protocol for highly purified EC (pEC) preparations of different origin and compared EC-specific inflammatory responses. Fluorescence-activated cell separation was used to obtain pEC cultures from different human arterial (coronary artery, internal thoracic artery) and venous (umbilical vein, saphenous vein) vessels. All pEC were analyzed for growth kinetics, morphology, release of cytokines/chemokines, and expression of E-selectin. For all different EC cultures, purities of ≥99% were reproducibly achieved. The EC isolation did not affect EC growth, morphology, and function. However, characterization of pEC from different vessel materials revealed an intrinsic, tissue-specific functional heterogeneity of EC cultures. Despite an arterial and venous difference in the secretion of IL-8 and monocyte chemoattractant protein-1, especially EC from coronary arteries produced significantly more IL-6 compared with other EC types, independent of age, gender, and disease of the cell donors. In contrast, the expression of E-selectin was not affected. We conclude that the proposed isolation protocol allows the generation of a pEC bank, enabling us to study tissue-specific aspects at the level of the endothelium.

Altered detection of molecules associated with leukocyte traffic in HUVECs derived from newborns with a strong family history of myocardial infarction

Atherosclerosis is a chronic inflammatory disease. As such, recruitment of immune cells is a significant event. Tightly controlled signaling molecules regulate leukocyte adhesion and migration to the tissues. The aim of this study was to determine if human umbilical vein endothelial cells (HUVECs) derived from healthy newborns with a strong family history of myocardial infarction (FHMI) showed variations in the presence of molecules related with leukocyte traffic and migration, in comparison to control healthy newborns. For this purpose, we evaluated the labeling of sialic acid containing glycoproteins, tight junction claudins and the cytoskeleton, using lectin- and immunocytochemistry in HUVECs from individuals with and without a strong FHMI. Our results show important differences in the labeling of alpha-2,3 or alpha-2,6 sialic acid-containing glycoconjugates, a disarrangement of actin filaments secondary to the absence of cytoplasmic claudin-5 immunopositivity and an increase in the binding of FHMI HUVECs to CD3+ Jurkat cells. It is possible that these differences relate to a predisposition for early appearance of atherosclerotic lesions.

Tumor necrosis factor-alpha up-regulates glucuronosyltransferase gene expression in human brain endothelial cells and promotes T-cell adhesion

Stimulation of human brain microvascular endothelial cells (SV-HCECs) with tumor necrosis factor-alpha (TNF-alpha) up-regulates sulfoglucuronosyl paragloboside (SGPG) synthesis in a dose- and time-dependent manner. After TNF-alpha exposure at a concentration of 50 ng/ml for 24 hr, we observed a seven- to tenfold elevation of SGPG concentration. Interleukin-1beta (IL-1beta) at a concentration of 10 ng/ml and the combined doses of TNF-alpha and IL-1beta were less effective than TNF-alpha alone. TNF-alpha also stimulated T-cell (Jurkat) adhesion with SV-HCECs via SGPG-L-selectin recognition: this was determined by double-label immunofluorescent staining with SGPG and L-selectin antibodies. The number of T cells bound to SV-HCECs after different cytokine stimulations was proportional to the SGPG concentration, and the cell attachment was inhibited by anti-SGPG and anti-L-selectin antibodies, respectively. Our data unequivocally establish that inflammatory cytokines, particularly TNF-alpha, stimulate the glucuronosyltransferse, GlcAT-P, and GlcAT-S, gene expression in brain endothelial cells and promote T-cell adhesion via SGPG-L-selectin recognition, a preliminary step for onset of neuroinflammation.

Bovine recombinant IFNγ induces endothelial cell gene transcription of immunoregulatory molecules and upregulates PMN and PBMC adhesion on bovine endothelial cells

Interferon gamma (IFNgamma) is an important modulator of immune responses acting on multiple cell types, such as lymphocytes, macrophages or endothelial cells. We investigated the effects of recombinant bovine IFNgamma on bovine umbilical vein endothelial cells (BUVEC) for the level of polymorphonuclear neutrophil cell (PMN)- and peripheral blood mononuclear cell (PBMC)-adhesion as well as the gene transcription of endothelial cell-derived adhesion molecules (E-selectin, P-selectin, VCAM-1, ICAM-1), chemokines (CXCL1, CXCL8, CXCL10, CCL2, CCL5), GM-CSF, iNOS and COX-2 in comparison to TNFalpha-stimulation. IFNgamma strongly induced PMN and PBMC adhesion on BUVEC involving CD4(+), CD8(+) and gammadelta-TCR(+) (WC1(+)) lymphocytes. Furthermore, IFNgamma-stimulation led to a strong upregulation in the transcription of VCAM-1, ICAM-1, CXCL10 and CCL2 genes and to a low to moderate increase in the E- and P-selectin, CXCL1, CXCL8, CCL5, COX-2 and iNOS gene transcripts, but failed to enhance GM-CSF gene transcription. These results indicate that IFNgamma can be considered an important activator of endothelial cells in the bovine system, most probably by influencing the outcome of inflammatory responses through selective upregulation of immunoregulatory molecules.

Role of T lymphocytes and interferon-gamma in ischemic stroke

BACKGROUND

Although lymphocyte recruitment and activation are associated with cerebral ischemia-reperfusion (I/R) injury, the contributions of specific lymphocyte subpopulations and lymphocyte-derived interferon-gamma (IFN-gamma) to stroke remain unknown. The objectives of this study were to define the contribution of specific populations of lymphocytes to the inflammatory and prothrombogenic responses elicited in the cerebral microvasculature by I/R and to investigate the role of T-cell-associated IFN-gamma in the pathogenesis of ischemic stroke.

METHODS AND RESULTS

Middle cerebral artery occlusion was induced for 1 hour (followed by 4 or 24 hours of reperfusion) in wild-type mice and mice deficient in lymphocytes (Rag1(-/-)), CD4+ T cells, CD8+ T cells, B cells, or IFN-gamma. Platelet and leukocyte adhesion was assessed in cortical venules with intravital video microscopy. Neurological deficit and infarct volume were determined 24 hours after reperfusion. Rag1(-/-), CD4+ T-cell(-/-), CD8+ T-cell(-/-), and IFN-gamma(-/-) mice exhibited comparable significant reductions in I/R-induced leukocyte and platelet adhesion compared with wild-type mice exposed to I/R. Infarct volume was reduced and I/R-induced neurological deficit was improved in immunodeficient Rag1(-/-) mice. These protective responses were reversed in Rag1(-/-) mice reconstituted with either wild-type or, to a lesser extent, IFN-gamma(-/-) splenocytes. B-cell-deficient mice failed to show improvement against ischemic stroke injury.

CONCLUSIONS

These findings indicate that CD4+ and CD8+ T lymphocytes, but not B lymphocytes, contribute to the inflammatory and thrombogenic responses, brain injury, and neurological deficit associated with experimental stroke. Although IFN-gamma plays a pivotal role in stroke-induced inflammatory responses, T lymphocytes appear to be a minor source of this cytokine.

Mosaic tumor vessels: cellular basis and ultrastructure of focal regions lacking endothelial cell markers

Endothelial cells of blood vessels in tumors may be thin, fragile, and defective in barrier function. We found previously that the endothelium of vessels in human colon carcinoma xenografts in mice is a mosaic structure. Approximately 85% of tumor vessels have uniform CD31 and/or CD105 immunoreactivity, but the remainder have focal regions that lack these common endothelial markers. The present study assessed the ultrastructure of the vessel lining and the integrity of the basement membrane in these regions. Using immunolabeling and confocal microscopy, we identified blood vessels that lacked CD31 and CD105 immunoreactivity and then analyzed the ultrastructure of these vessels by transmission electron microscopy. Eleven percent of vessels in orthotopic tumors and 24% of vessels in ectopic tumors had defects in CD31 and CD105 staining measuring on average 10.8 microm (range, 1-41.2 microm). Ultrastructural studies identified endothelial cells at 92% of CD31- and CD105-negative sites in orthotopic tumors and 70% of the sites in ectopic tumors. Thus, most regions of tumor vessels that lack CD31 and CD105 immunoreactivity represent attenuated endothelial cells with abnormal expression of endothelial cell markers, but some are gaps between endothelial cells. More than 80% of the defects lacked immunoreactivity for multiple basement membrane proteins.

HUVECs from newborns with a strong family history of myocardial infarction overexpress adhesion molecules and react abnormally to stimulating agents

Atherosclerosis is a complex disease involved in major fatal events such as myocardial infarction and stroke. It is the result of interactions between metabolic, dietetic and environmental risk factors acting on a genetic background that could result in endothelial susceptibility. Our aim was to determine the patterns of expression of adhesion molecules and whether phosphatidylserine is translocated to the cell surface of human umbilical vein endothelial cells (HUVECs) isolated from healthy newborns born to parents with a strong family history of myocardial infarction under TNF-alpha or oxLDL stimulated conditions. Compared to control HUVECs, experimental cords showed: (a) a four-fold increase in VCAM-1 expression under basal conditions, which showed no change after stimulation with the pro-atherogenic factors; (b) a two-fold increase in basal P-selectin expression that reached a 10-fold increase with any of the pro-atherogenic factors; (c) a basal ICAM-1 expression similar to P-selectin that was not modified by the pro-atherogenic molecules; (d) a similar PECAM-1 expression. Unexpectedly, phospathidylserine expression in experimental cord HUVECs was significantly increased (211 817 versus 3354 TFU) but was not associated to apoptotic death as the percentage of dead cells induced by TNF-alpha treatment was very low (0.55 versus 9.87% in control HUVECs). The latter result was corroborated by TUNEL staining. T cell adherence to HUVECs was highly up-regulated in the genetically predisposed samples. The analysis of nonpooled HUVECs, from newborns to family predisposed myocardial-infarction individuals, might represent a useful strategy to identify phenotypical and functional alterations, and hopefully, to take early preventive actions.

Synergistic induction of tissue factor by coagulation factor Xa and TNF: evidence for involvement of negative regulatory signaling cascades

Enzymes of the blood coagulation pathway enhance the inflammatory response leading to endothelial dysfunction, accounting, in part, for the vascular complications occurring in sepsis and cardiovascular disease. The responses of endothelial cell activation include induction of the expression of tissue factor (TF), a membrane glycoprotein that promotes thrombosis, and of E-selectin, a cell adhesion molecule that promotes inflammation. In this report, we demonstrate synergistic interactions between the coagulation factor Xa (fXa) and the proinflammatory cytokines TNF, IL-1beta, and CD40L, leading to enhanced expression of TF and E-selectin in endothelial cells. A detailed analysis of the molecular pathways that could account for this activity of fXa showed that fXa inhibited the cytokine-induced expression of dual specificity phosphatases, MAP kinase phosphatase-L, -4, -5, and -7, blocking a negative regulatory effect on c-Jun N-terminal kinase. The synergistic interaction between fXa and TNF was also involved in the inhibition of A20 and IkappaBalpha expression in the IkappaB kinase-NF-kappaB pathway. The data indicate that inhibition of negative regulatory signaling accounts for the amplification of cytokine-induced endothelial cell activation by fXa.

What do we mean by the term "inflammation"? A contemporary basic science update for sports medicine

Most practicing sports medicine clinicians refer to the concept of "inflammation" many times a day when diagnosing and treating acute and overuse injuries. What is meant by this term? Is it a "good" or a "bad" process? The major advances in the understanding of inflammation in recent years are summarised, and some clinical implications of the contemporary model of inflammation are highlighted.

Effects of Porphyromonas gingivalis antigens and proinflammatory cytokines on human coronary artery endothelial cells

OBJECTIVE

Individuals with periodontitis have been cited as having a significantly increased risk of developing coronary heart disease. Although accumulating evidence suggests that periodontal infection is involved in the development and progression of atherosclerosis, the underlying mechanisms remain to be elucidated. In the present study, we examined how periodontal infection could contribute to endothelial dysfunction.

METHODS

Human coronary arterial endothelial cells were stimulated with tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, both of which are reported to be elevated in the serum of periodontitis patients. Cells were also stimulated with lipopolysaccharide, outer membrane protein and heat shock protein 60 derived from Porphyromonas gingivalis, a representative periodontopathic bacterium which is known to stimulate myeloid cells.

RESULTS

Although TNF-alpha and IL-1beta, at concentrations a little higher than those in sera of periodontitis patients, up-regulated the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, P. gingivalis antigens had only a slight stimulatory effect.

CONCLUSION

Experiments in which the total pathogen burden is considered, rather than a single species of bacteria, would increase our understanding of the contribution of which periodontal infection to atherogenesis.

Whole blood-mediated endothelial permeability and adhesion molecule expression: a model study into the effects of bacteria and antibiotics

AIM

To investigate whether the inflammatory response of cultured endothelial cells, as induced by conditioned plasma, depends on the bacterial species or type of antibiotic used for incubation with whole blood.

MATERIALS AND METHODS

Blood from healthy volunteers was stimulated ex vivo with different microorganisms, and with bacteria killed with different antibiotics. The resultant plasmas were incubated on monolayers of cultured human endothelial cells, followed by measurement of their permeability to albumin and expression of E-selectin and intercellular adhesion molecule-1.

RESULTS

Incubation of Escherichia coli in blood yielded plasmas that induced a marked increase in endothelial permeability and E-selectin expression. The response to Bacteroides fragilis or Enterococcus faecalis was generally weaker. Similar effects were observed after incubation of whole blood with lipopolysaccharide (LPS). Much of the permeability and adhesion molecule response to E. coli remained after removal of intact microorganisms from the culture. Whereas antibiotic treatment of E. coli with imipenem or cefuroxime resulted in a divergent production of tumour necrosis factor-alpha (TNF-alpha) in blood, no significant differences between these treatments were observed with respect to the plasma-induced endothelial response.

CONCLUSION

Bacteria differ in their capacity to generate a whole blood-mediated increase of endothelial permeability and adhesion molecule expression; this response depends, at least in part, on the presence of soluble bacterial components, such as LPS. Whereas treatment with various antibiotics may generate varying amounts of TNF-alpha, these differences are not translated into differences in endothelial permeability or adhesion molecule expression.

Platelet endothelial cell adhesion molecule in cell signaling and thrombosis

Platelet endothelial cell adhesion molecule (PECAM-1) is a member of the superfamily of immunoglobulins. This cell adhesion molecule has been implicated to mediate the adhesion and trans-endothelial migration of T lymphocytes/monocytes into the vascular wall, a critical step in the initiation of atherogenesis. Current thinking, however, posits that PECAM-1 by virtue of being a scaffolding molecule may well play a role in several signal transduction reactions. As a consequence, this cell adhesion molecule may be responsible for several biological and pathophysiological functions such as thrombosis, and inflammation. Evidence has also been put forward for a potential role of PECAM-1 in apoptosis and atherosclerosis. This article focuses on the structure of PECAM-1 and its role in intracellular signaling and implications in health and disease.

Methotrexate markedly reduces the expression of vascular E-selectin, cutaneous lymphocyte-associated antigen and the numbers of mononuclear leucocytes in psoriatic skin

A positive correlation between disease severity and the frequency of cutaneous lymphocyte-associated antigen (CLA)-positive T cells in the blood of untreated patients with psoriasis has been previously observed. A dose-dependent inverse relationship between disease severity and the frequency of circulating CLA(+) T cells in psoriasis patients on methotrexate (MTX) treatment is reported. Circulating T cells from a patient with psoriasis were monitored for CLA expression on a daily basis for 5 weeks. A decrease in the intensity and frequency of CLA(+) mononuclear leucocytes was consistently observed in the blood during the first 3-4 days after each MTX intake, but the CLA expression increased thereafter until the next weekly dose was taken. The MTX treatment of this patient was then discontinued for 16 days, and a marked subjective exacerbation was reported within 9 days, which was confirmed objectively (laser Doppler perfusion imaging) after 11 and 16 days. Biopsies taken 4 days after the last MTX intake showed only a few mononuclear leucocytes in lesional skin, but the exacerbation coincided with a marked increase in CLA expression by mononuclear blood leucocytes, followed by an increase in endothelial E-selectin and a striking influx of CLA(+) mononuclear cells into lesional skin. Conversely, a clinical improvement after the patient resumed the MTX treatment was associated with reduction in CLA expression by mononuclear cells in the blood, downregulation of endothelial E-selectin and an approximate threefold decrease in mononuclear leucocyte infiltration of lesional skin. No MTX-associated changes were detected in the expression of very late antigen-4, vascular cell-adhesion molecule-1 nor the late activation marker CD25. It is concluded that MTX decreases the expression of CLA and E-selectin and that this may be a major mechanism for the therapeutic effect of MTX on psoriatic skin lesions.

Recruitment of IFN-gamma-producing (Th1-like) cells into the inflamed retina in vivo is preferentially regulated by P-selectin glycoprotein ligand 1:P/E-selectin interactions

Although there is evidence that altering the Th1/Th2 balance toward Th2 cells may be important in the resolution of Th1-type autoimmune disease, adoptive transfer of Th2 cells is not effective in protecting against Th1-type disease and may cause disease. Therefore, we examined the recruitment of Th1- and Th2-like cells into the retina in the murine autoimmune disease experimental autoimmune uveoretinitis. CD4 T cells were polarized in vitro to IFN-gamma-producing Th1-like cells and non-IFN-gamma-producing Th2-like cells, labeled, and adoptively transferred. Trafficking to the retina in vivo was evaluated by scanning laser ophthalmoscopy and infiltration by confocal microscopy. There were more rolling and adherent Th1-like cells and they rolled more slowly than did Th2-like cells. Th1-like cells were preferentially recruited into the retinal parenchyma at both initiation and resolution. Surface P-selectin glycoprotein ligand 1 (PSGL-1) and LFA-1 were up-regulated on both populations but were expressed at higher levels on Th1-like cells. Up-regulation of CD44 expression was higher on Th2-like cells. P-selectin, E-selectin, and ICAM-1 are up-regulated on postcapillary venules in the retina. Pretreatment of Th1-like cells with anti-PSGL-1 inhibited rolling and infiltration of Th1-like cells but not Th2-like cells, providing direct in vivo evidence for the inability of Th2 to respond to P/E-selectin despite increased expression of PSGL-1. Anti-LFA-1 pretreatment inhibited infiltration of both Th1- and Th2-like cells, but more so Th-1. We suggest that random trafficking of activated T cells (both Th1 and Th2) across the blood-retina barrier is mediated by CD44:CD44R and LFA-1:ICAM-1, whereas preferential recruitment of Th1 cells is mediated by PSGL-1:P/E-selectin.

Increased transendothelial migration of scleroderma lymphocytes

BACKGROUND

CD4+ T lymphocytes play an important part in the pathogenesis of scleroderma (systemic sclerosis, SSc) and predominate in perivascular SSc skin lesions. Both soluble and membrane bound adhesion molecules are overexpressed in SSc, possibly influencing lymphocyte/endothelial cell (EC) contact.

OBJECTIVE

To assess the transendothelial migration capacity of peripheral lymphocytes in vitro.

PATIENTS AND METHODS

Collagen was covered with human umbilical vein endothelial cells (HUVEC), and peripheral blood mononuclear cells (PBMC) of patients and matched healthy controls (HC) were added in parallel experiments. Before and after fractionated harvest of non-adherent, bound, and migrated lymphocytes, the CD4/CD8 ratio and the lymphocytic expression of activation markers and adhesion molecules were analysed by fluorocytometry.

RESULTS

13 (SD 12)% of the SSc PBMC migrated compared with only 5 (5)% HC PBMC (p<0.0002); this increase was primarily due to the migration of CD3+ T lymphocytes and mainly to a larger proportion of CD4+ cells within this CD3+ fraction (71 (SD 14)% for SSc v 56 (14)% for HC, p<0.03), leading to an increased CD4/CD8 ratio among migrated SSc lymphocytes in comparison with controls (3.3 (1.5) v 1.62 (0.93), p<0.006). Among migrated SSc CD4+ T lymphocytes, the frequency of HLA-DR+ cells was increased; migrated lymphocytes highly expressed the adhesion molecules CD11a, CD49d, CD29, and CD44.

CONCLUSION

Transendothelial migration of CD4+ T lymphocytes is enhanced in SSc, and migrating cells exhibit an activated phenotype. The data suggest that activated CD3+CD4+ lymphocytes as found in SSc peripheral blood are prone to transvascular migration, thus contributing to the formation of typical perivascular lymphocytic infiltrates.

Phenotypic and functional differences between human saphenous vein (HSVEC) and umbilical vein (HUVEC) endothelial cells

The vascular endothelial cell (EC) plays an essential role in the pathogenesis of inflammation, transplant rejection and tumour metastasis. Most research on vascular ECs uses human umbilical vein endothelial cells (HUVECs). However, HUVECs are derived from immune-naive foetal tissue, and show significant functional differences from adult vascular endothelium. In this paper, we characterise an alternative model based on human saphenous vein ECs (HSVECs), describe their culture conditions and provide a detailed functional comparison with HUVECs. Compared with HUVECs, HSVECs show an increased sensitivity to ox-LDL and a reduced response to cytokines, as indicated by adhesion molecule expression as well as leukocyte adhesion and transmigration. With respect to their ability to present antigen, HSVECs have a higher level of HLA-DR, CD40 and ICOS-L following cytokine stimulation. In addition, HSVECs upregulate the costimulatory ligand CD80 (B7.1) following CD40 ligation, and support allogeneic T cell proliferation, while HUVECs fail to express CD80. Due to differential expression of adhesion molecules, poorly differentiated tumour cell lines also showed more adhesion to HSVECs than to HUVECs. These results indicate that HSVECs have advantages over HUVECs for studying adult vascular endothelial pathology in vitro.

Effect of postprandial hypertriglyceridemia and hyperglycemia on circulating adhesion molecules and oxidative stress generation and the possible role of simvastatin treatment

Adhesion molecules, particularly intracellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, and E-selectin, have been associated with cardiovascular disease. Elevated levels of these molecules have been reported in diabetic patients. Postprandial hypertriglyceridemia and hyperglycemia are considered risk factors for cardiovascular disease, and evidence suggests that postprandial hypertriglyceridemia and hyperglycemia may induce an increase in circulating adhesion molecules. However, the distinct role of these two factors is a matter of debate. Thirty type 2 diabetic patients and 20 normal subjects ate three different meals: a high-fat meal, 75 g of glucose alone, and a high-fat meal plus glucose. Glycemia, triglyceridemia, plasma nitrotyrosine, ICAM-1, VCAM-1, and E-selectin were assayed during the tests. Subsequently, diabetic subjects took simvastatin 40 mg/day or placebo for 12 weeks. The three tests were performed again at baseline, between 3 and 6 days after starting the study, and at the end of each study. High-fat load and glucose alone produced an increase of nitrotyrosine, ICAM-1, VCAM-1, and E-selectin plasma levels in normal and diabetic subjects. These effects were more pronounced when high fat and glucose were combined. Short-term simvastatin treatment had no effect on lipid parameters, but reduced the effect on adhesion molecules and nitrotyrosine, which was observed during every different test. Long-term simvastatin treatment was accompanied by a lower increase in postprandial triglycerides, which was followed by smaller variations in ICAM-1, VCAM-1, E-selectin, and nitrotyrosine during the tests. This study shows an independent and cumulative effect of postprandial hypertriglyceridemia and hyperglycemia on ICAM-1, VCAM-1, and E-selectin plasma levels, suggesting oxidative stress as a common mediator of such effects. Simvastatin shows a beneficial effect on oxidative stress and the plasma levels of adhesion molecules, which may be ascribed to a direct effect in addition to the lipid-lowering action of the drug.

Lovastatin inhibits Rho-regulated expression of E-selectin by TNFalpha and attenuates tumor cell adhesion

E-selectin mediated cell-cell adhesion plays an important role in inflammatory processes and extravasation of tumor cells. Tumor necrosis factor-alpha (TNF-alpha) induces E-selectin gene and protein expression in primary human endothelial cells (HUVEC) and in an endothelial cell line (EA.hy-926). As shown by ELISA and FACS analyses, HMG-CoA reductase inhibitors (e.g., lovastatin) impair the TNF-alpha stimulated increase in E-selectin protein expression. Similar results were obtained for E-selectin mRNA expression and promoter activity, indicating that the effect of lovastatin is based on inhibition of gene expression. The effective inhibitory concentration of lovastatin was in a physiologically relevant range (IC50<0.1 microM). Lovastatin-mediated block of TNF-alpha induced E-selectin expression is due to inhibition of protein geranylgeranylation rather than farnesylation. Down-regulation of Rho signaling by coexpression of dominant-negative Rho mutants (i.e RhoA, RhoB and Rac) impaired TNF-alpha driven E-selectin gene expression, indicating Rho signaling to be essential for transcriptional activation of the E-selectin gene. Inhibition of E-selectin expression by lovastatin gives rise to a significant reduction in TNF-alpha stimulated adhesion of colon carcinoma cells to HUVEC. Furthermore, low concentration of lovastatin (i.e., < or =1 microM) attenuated TNF-alpha induced tumor cell invasion in vitro. The data support the view that statins might be clinically useful in protection against E-selectin mediated metastasis.

Mitochondrial reactive oxygen species regulate spatial profile of proinflammatory responses in lung venular capillaries

Cytokine-induced lung expression of the endothelial cell (EC) leukocyte receptor P-selectin initiates leukocyte rolling. To understand the early EC signaling that induces the expression, we conducted real-time digital imaging studies in lung venular capillaries. To compare receptor- vs nonreceptor-mediated effects, we infused capillaries with respectively, TNF-alpha and arachidonate. At concentrations adjusted to give equipotent increases in the cytosolic Ca(2+), both agents increased reactive oxygen species (ROS) production and EC P-selectin expression. Blocking the cytosolic Ca(2+) increases abolished ROS production; blocking ROS production abrogated P-selectin expression. TNF-alpha, but not arachidonate, released Ca(2+) from endoplasmic stores and increased mitochondrial Ca(2+). Furthermore, Ca(2+) depletion abrogated TNF-alpha responses partially, but arachidonate responses completely. These differences in Ca(2+) mobilization by TNF-alpha and arachidonate were reflected in spatial patterning in the capillary in that the TNF-alpha effects were localized at branch points, while the arachidonate effects were nonlocalized and extensive. Furthermore, mitochondrial blockers inhibited the TNF-alpha- but not the arachidonate-induced responses. These findings indicate that the different modes of Ca(2+) mobilization determined the spatial patterning of the proinflammatory response in lung capillaries. Responses to TNF-alpha revealed that EC mitochondria regulate the proinflammatory process by generating ROS that activate P-selectin expression.

Endothelial adhesion molecule expression in an in vitro model of inflammation

BACKGROUND

Cytokines influence the expression of adhesion molecules and hence, regulate the passage of leucocytes from the blood to the site of inflammation causing leucocyte accumulation and the modulation of the nature and progression of inflammatory responses. They form a complex communication network causing results which are not determined by the effects of a single cytokine but especially by the interaction of several cytokines.

METHOD

For the determination of adhesion molecule expression on the surface of enzymatically detached endothelial cells, flow cytometry is applied. Fluorescence-conjugated mouse monoclonal antibodies directed against VCAM-1, ICAM-1, PECAM-1, CD34, E- and P-selectin are used.

RESULTS

We clearly demonstrate that ICAM-1, PECAM-1, P-selectin and CD34 are-in relation to an incubation cocktail containing solely TNF-alpha, IL-1beta and IFN-gamma-altered antagonistically by the supplementary addition of the inflammatory cytokines IL-2 and IL-6 as well as the anti-inflammatory cytokines IL-4 and IL-10, whereas VCAM-1 is synergistically enhanced under the same test conditions.

CONCLUSION

The results of our in vitro investigations show that the effects of a single cytokine within a multi-component cytokine combination on endothelial adhesion molecule expression are strongly influenced by the nature of the other cytokines present in the combination tested.