Identification of a functional NF-kappa B site in the platelet endothelial cell adhesion molecule-1 promoter

E2F2 modulates cell adhesion through the transcriptional regulation of PECAM1 in multiple myeloma

Multiple myeloma (MM) is the second most common haematological malignancy. Despite the development of new drugs and treatments in recent years, the therapeutic outcomes of patients are not satisfactory. It is necessary to further investigate the molecular mechanism underlying MM progression. Herein, we found that high E2F2 expression was correlated with poor overall survival and advanced clinical stages in MM patients. Gain- and loss-of-function studies showed that E2F2 inhibited cell adhesion and consequently activated cell epithelial-to-mesenchymal transition (EMT) and migration. Further experiments revealed that E2F2 interacted with the PECAM1 promoter to suppress its transcriptional activity. The E2F2-knockdown-mediated promotion of cell adhesion was significantly reversed by the repression of PECAM1 expression. Finally, we observed that silencing E2F2 significantly inhibited viability and tumour progression in MM cell models and xenograft mouse models respectively. This study demonstrates that E2F2 plays a vital role as a tumour accelerator by inhibiting PECAM1-dependent cell adhesion and accelerating MM cell proliferation. Therefore, E2F2 may serve as a potential independent prognostic marker and therapeutic target for MM.

Sexually dimorphic prelimbic cortex mechanisms play a role in alcohol dependence: protection by endostatin

Angiogenesis or proliferation of endothelial cells plays a role in brain microenvironment homeostasis. Previously we have shown enhanced expression of markers of angiogenesis in the medial prefrontal cortex during abstinence in an animal model of ethanol dependence induced by chronic intermittent ethanol vapor (CIE) and ethanol drinking (ED) procedure. Here we report that systemic injections of the angiogenesis inhibitor endostatin reduced relapse to drinking behavior in female CIE-ED rats without affecting relapse to drinking in male CIE-ED rats, and female and male nondependent ED rats. Endostatin did not alter relapse to sucrose drinking in both sexes. Endostatin reduced expression of platelet endothelial cell adhesion molecule-1 (PECAM-1) in all groups; however, rescued expression of tight junction protein claudin-5 in the prelimbic cortex (PLC) of female CIE-ED rats. In both sexes, CIE-ED enhanced microglial activation in the PLC and this was selectively prevented by endostatin in female CIE-ED rats. Endostatin prevented CIE-ED-induced enhanced NF-kB activity and expression and Fos expression in females and did not alter reduced Fos expression in males. Analysis of synaptic processes within the PLC revealed sexually dimorphic adaptations, with CIE-ED reducing synaptic transmission and altering synaptic plasticity in the PLC in females, and increasing synaptic transmission in males. Endostatin prevented the neuroadaptations in the PLC in females via enhancing phosphorylation of CaMKII, without affecting the neuroadaptations in males. Our multifaceted approach is the first to link PLC endothelial cell damage to the behavioral, neuroimmune, and synaptic changes associated with relapse to ethanol drinking in female subjects, and provides a new therapeutic strategy to reduce relapse in dependent subjects.

Cyclosporine A and Tacrolimus Induce Functional Impairment and Inflammatory Reactions in Endothelial Progenitor Cells

Immunosuppressants are a mandatory therapy for transplant patients to avoid rejection of the transplanted organ by the immune system. However, there are several known side effects, including alterations of the vasculature, which involve a higher occurrence of cardiovascular events. While the effects of the commonly applied immunosuppressive drugs cyclosporine A (CsA) and tacrolimus (Tac) on mature endothelial cells have been addressed in several studies, we focused our research on the unexplored effects of CsA and Tac on endothelial colony-forming cells (ECFCs), a subgroup of endothelial progenitor cells, which play an important role in vascular repair and angiogenesis. We hypothesized that CsA and Tac induce functional defects and activate an inflammatory cascade via NF-κB signaling in ECFCs. ECFCs were incubated with different doses (0.01 µM–10 µM) of CsA or Tac. ECFC function was determined using in vitro models. The expression of inflammatory cytokines and adhesion molecules was explored by quantitative real-time PCR and flow cytometry. NF-κB subunit modification was assessed by immunoblot and immunofluorescence. CsA and Tac significantly impaired ECFC function, including proliferation, migration, and tube formation. TNF-α, IL-6, VCAM, and ICAM mRNA expression, as well as PECAM and VCAM surface expression, were enhanced. Furthermore, CsA and Tac led to NF-κB p65 subunit phosphorylation and nuclear translocation. Pharmacological inhibition of NF-κB by parthenolide diminished CsA- and Tac-mediated proinflammatory effects. The data of functional impairment and activation of inflammatory signals provide new insight into mechanisms associated with CsA and Tac and cardiovascular risk in transplant patients.

Convergence: Lactosylceramide-Centric Signaling Pathways Induce Inflammation, Oxidative Stress, and Other Phenotypic Outcomes

Lactosylceramide (LacCer), also known as CD17/CDw17, is a member of a large family of small molecular weight compounds known as glycosphingolipids. It plays a pivotal role in the biosynthesis of glycosphingolipids, primarily by way of serving as a precursor to the majority of its higher homolog sub-families such as gangliosides, sulfatides, fucosylated-glycosphingolipids and complex neutral glycosphingolipids—some of which confer “second-messenger” and receptor functions. LacCer is an integral component of the “lipid rafts,” serving as a conduit to transduce external stimuli into multiple phenotypes, which may contribute to mortality and morbidity in man and in mouse models of human disease. LacCer is synthesized by the action of LacCer synthase (β-1,4 galactosyltransferase), which transfers galactose from uridine diphosphate galactose (UDP-galactose) to glucosylceramide (GlcCer). The convergence of multiple physiologically relevant external stimuli/agonists—platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), stress, cigarette smoke/nicotine, tumor necrosis factor-α (TNF-α), and in particular, oxidized low-density lipoprotein (ox-LDL)—on β-1,4 galactosyltransferase results in its phosphorylation or activation, via a “turn-key” reaction, generating LacCer. This newly synthesized LacCer activates NADPH (nicotinamide adenine dihydrogen phosphate) oxidase to generate reactive oxygen species (ROS) and a highly “oxidative stress” environment, which trigger a cascade of signaling molecules and pathways and initiate diverse phenotypes like inflammation and atherosclerosis. For instance, LacCer activates an enzyme, cytosolic phospholipase A2 (cPLA2), which cleaves arachidonic acid from phosphatidylcholine. In turn, arachidonic acid serves as a precursor to eicosanoids and prostaglandin, which transduce a cascade of reactions leading to inflammation—a major phenotype underscoring the initiation and progression of several debilitating diseases such as atherosclerosis and cancer. Our aim here is to present an updated account of studies made in the field of LacCer metabolism and signaling using multiple animal models of human disease, human tissue, and cell-based studies. These advancements have led us to propose that previously unrelated phenotypes converge in a LacCer-centric manner. This LacCer synthase/LacCer-induced “oxidative stress” environment contributes to inflammation, atherosclerosis, skin conditions, hair greying, cardiovascular disease, and diabetes due to mitochondrial dysfunction. Thus, targeting LacCer synthase may well be the answer to remedy these pathologies.

CD31 as a Therapeutic Target in Atherosclerosis

The potential of CD31 as a therapeutic target in atherosclerosis has been considered ever since its cloning in the 1990s, but the exact role played by this molecule in the biologic events underlying atherosclerosis has remained controversial, resulting in the stalling of any therapeutic perspective. Due to the supposed cell adhesive properties of CD31, specific monoclonal antibodies and recombinant proteins were regarded as blocking agents because their use prevented the arrival of leukocytes at sites of acute inflammation. However, the observed effect of those compounds likely resulted from the engagement of the immunomodulatory function of CD31 signaling. This was acknowledged only later though, upon the discovery of CD31's 2 intracytoplasmic tyrosine residues called immunoreceptor tyrosine inhibitory motifs. A growing body of evidence currently points at a therapeutic potential for CD31 agonists in atherothrombosis. Clinical observations show that CD31 expression is altered at the surface of leukocytes infiltrating unhealed atherothrombotic lesions and that the physiological immunomodulatory functions of CD31 are lost at the surface of blood leukocytes in patients with acute coronary syndromes. On the contrary, translational studies using candidate therapeutic molecules in laboratory animals have provided encouraging results: synthetic peptides administered to atherosclerotic mice as systemic drugs in the acute phases of atherosclerotic complications favor the healing of wounded arteries, whereas the immobilization of CD31 agonist peptides onto coronary stents implanted in farm pigs favors their peaceful integration within the coronary arterial wall.

APC/Cdh1 targets PECAM-1 for ubiquitination and degradation in endothelial cells

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a member of the immunoglobulin superfamily and is expressed by hematopoietic and endothelial cells (ECs). Recent studies have shown that PECAM-1 plays a crucial role in promoting the development of the EC inflammatory response in the context of disturbed flow. However, the mechanistic pathways that control PECAM-1 protein stability remain largely unclear. Here, we identified PECAM-1 as a novel substrate of the APC/Cdh1 E3 ubiquitin ligase. Specifically, lentivirus-mediated Cdh1 depletion stabilized PECAM-1 in ECs. Conversely, overexpression of Cdh1 destabilized PECAM-1. The proteasome inhibitor MG132 blocked Cdh1-mediated PECAM-1 degradation. In addition, Cdh1 promoted K48-linked polyubiquitination of PECAM-1 in a destruction box-dependent manner. Furthermore, we demonstrated that compared with pulsatile shear stress (PS), oscillatory shear stress decreased the expression of Cdh1 and the ubiquitination of PECAM-1, therefore stabilizing PECAM-1 to promote inflammation in ECs. Hence, our study revealed a novel mechanism by which fluid flow patterns regulate EC homeostasis via Cdh1-dependent ubiquitination and subsequent degradation of PECAM-1.

Indomethacin reduces rates of aortic dissection and rupture of the abdominal aorta by inhibiting monocyte/macrophage accumulation in a murine model

Aortic dissection is a life-threatening condition, which is characterised by separation of the constituent layers of the aortic wall. We have recently shown that monocyte/macrophage infiltration into the aortic wall is a pathogenic mechanism of the condition. In the present study, we investigated whether the anti-inflammatory agent, indomethacin, could inhibit monocyte/macrophage accumulation in the aortic wall and ensuing dissection. Indomethacin was administered (from 3 days prior with daily oral administration) to mice in which aortic dissection was induced using beta-aminopropionitrile (BAPN) and angiotensin II (Ang II) infusion (2 weeks). Indomethacin prevented death from abdominal aortic dissection and decreased incidence of aortic dissection by as high as 40%. Histological and flow cytometry analyses showed that indomethacin administration resulted in inhibition of monocyte transendothelial migration and monocyte/macrophage accumulation in the aortic wall. These results indicate that indomethacin administration reduces rate of onset of aortic dissection in a murine model of the condition.

Platelet Endothelial Cell Adhesion Molecule-1 and Oligodendrogenesis: Significance in Alcohol Use Disorders

Alcoholism is a chronic relapsing disorder with few therapeutic strategies that address the core pathophysiology. Brain tissue loss and oxidative damage are key components of alcoholism, such that reversal of these phenomena may help break the addictive cycle in alcohol use disorder (AUD). The current review focuses on platelet endothelial cell adhesion molecule 1 (PECAM-1), a key modulator of the cerebral endothelial integrity and neuroinflammation, and a targetable transmembrane protein whose interaction within AUD has not been well explored. The current review will elaborate on the function of PECAM-1 in physiology and pathology and infer its contribution in AUD neuropathology. Recent research reveals that oligodendrocytes, whose primary function is myelination of neurons in the brain, are a key component in new learning and adaptation to environmental challenges. The current review briefly introduces the role of oligodendrocytes in healthy physiology and neuropathology. Importantly, we will highlight the recent evidence of dysregulation of oligodendrocytes in the context of AUD and then discuss their potential interaction with PECAM-1 on the cerebral endothelium.

The use of the soluble adhesion molecules sE-selectin, sICAM-1, sVCAM-1, sPECAM-1 and their ligands CD11a and CD49d as diagnostic and prognostic biomarkers in septic and critically ill non-septic ICU patients

Endothelial activation is pivotal in the development and escalation of sepsis. Central to endothelial activation is the endothelial up-regulation of cellular adhesion molecules (CAMs) including E-selectin, ICAM-1, VCAM-1, and PECAM-1. Shed CAMs are also found in circulating soluble forms (sCAMs). We investigated whether sCAMs can be used as biomarkers for the differentiation between septic and non-septic patients. Furthermore, we investigated lymphocyte and monocyte expression of LFA-1 (CD11a/CD18) and VLA-4 (CD49d/CD29) ligands for ICAM-1 and VCAM-1, respectively. Twenty-one septic and 15 critically ill non-septic patients were included. All patients had an APACHE II score above 13 at ICU admission. Fifteen healthy volunteers served as controls. Flow cytometry was used to estimate levels of sE-selectin, sICAM-1, sVCAM-1, sPECAM-1, and the cellular expression of CD11a and CD49d. Levels of sE-selectin, sICAM-1 and sPECAM-1 were higher in the septic patients compared with the non-septic patients and controls at admission and during the observation period. Lymphocyte and monocyte expression of CD11a and CD49d was suppressed or unaltered in the septic patients compared with the non-septic patients and controls. Levels of sE-selectin, sICAM-1, and sPECAM-1 were able to discriminate between septic and non-septic patients, indicating that sCAMs may be potential diagnostic biomarkers of sepsis.

Endothelial LSP1 Modulates Extravascular Neutrophil Chemotaxis by Regulating Nonhematopoietic Vascular PECAM-1 Expression

During inflammation, leukocyte-endothelial cell interactions generate molecular signals that regulate cell functions. The Ca(2+)- and F-actin-binding leukocyte-specific protein 1 (LSP1) expressed in leukocytes and nonhematopoietic endothelial cells is pivotal in regulating microvascular permeability and leukocyte recruitment. However, cell-specific function of LSP1 during leukocyte recruitment remains elusive. Using intravital microscopy of cremasteric microvasculature of chimeric LSP1-deficient mice, we show that not neutrophil but endothelial LSP1 regulates neutrophil transendothelial migration and extravascular directionality without affecting the speed of neutrophil migration in tissue in response to CXCL2 chemokine gradient. The expression of PECAM-1-sensitive α6β1 integrins on the surface of transmigrated neutrophils was blunted in mice deficient in endothelial LSP1. Functional blocking studies in vivo and in vitro elucidated that α6β1 integrins orchestrated extravascular directionality but not the speed of neutrophil migration. In LSP1-deficient mice, PECAM-1 expression was reduced in endothelial cells, but not in neutrophils. Similarly, LSP1-targeted small interfering RNA silencing in murine endothelial cells mitigated mRNA and protein expression of PECAM-1, but not ICAM-1 or VCAM-1. Overexpression of LSP1 in endothelial cells upregulated PECAM-1 expression. Furthermore, the expression of transcription factor GATA-2 that regulates endothelial PECAM-1 expression was blunted in LSP1-deficient or LSP1-silenced endothelial cells. The present study unravels endothelial LSP1 as a novel cell-specific regulator of integrin α6β1-dependent neutrophil extravascular chemotactic function in vivo, effective through GATA-2-dependent transcriptional regulation of endothelial PECAM-1 expression.

The Cytokinome Profile in Patients with Hepatocellular Carcinoma and Type 2 Diabetes

Understanding the dynamics of the complex interaction network of cytokines, defined as ‘‘cytokinome’’, can be useful to follow progression and evolution of hepatocellular carcinoma (HCC) from its early stages as well as to define therapeutic strategies. Recently we have evaluated the cytokinome profile in patients with type 2 diabetes (T2D) and/or chronic hepatitis C (CHC) infection and/or cirrhosis suggesting specific markers for the different stages of the diseases. Since T2D has been identified as one of the contributory cause of HCC, in this paper we examined the serum levels of cytokines, growth factors, chemokines, as well as of other cancer and diabetes biomarkers in a discovery cohort of patients with T2D, chronic hepatitis C (CHC) and/or CHC-related HCC comparing them with a healthy control group to define a profile of proteins able to characterize these patients, and to recognize the association between diabetes and HCC. The results have evidenced that the serum levels of some proteins are significantly and differently up-regulated in all the patients but they increased still more when HCC develops on the background of T2D. Our results were verified also using a separate validation cohort. Furthermore, significant correlations between clinical and laboratory data characterizing the various stages of this complex disease, have been found. In overall, our results highlighted that a large and simple omics approach, such as that of the cytokinome analysis, supplemented by common biochemical and clinical data, can give a complete picture able to improve the prognosis of the various stages of the disease progression. We have also demonstrated by means of interactomic analysis that our experimental results correlate positively with the general metabolic picture that is emerging in the literature for this complex multifactorial disease.

Lancemaside A from Codonopsis lanceolata modulates the inflammatory responses mediated by monocytes and macrophages

In this study, we aimed to examine the cellular and molecular mechanisms of lancemaside A from Codonopsis lanceolata (Campanulaceae) in the inflammatory responses of monocytes (U937 cells) and macrophages (RAW264.7 cells). Lancemaside A significantly suppressed the inflammatory functions of lipopolysaccharide- (LPS-) treated RAW264.7 cells by suppressing the production of nitric oxide (NO), the expression of the NO-producing enzyme inducible NO synthase (iNOS), the upregulation of the costimulatory molecule CD80, and the morphological changes induced by LPS exposure. In addition, lancemaside A diminished the phagocytic activity of RAW264.7 cells and boosted the neutralizing capacity of these cells when treated with the radical generator sodium nitroprusside (SNP). Interestingly, lancemaside A strongly blocked the adhesion activity of RAW264.7 cells to plastic culture plates, inhibited the cell-cell and cell-fibronectin (FN) adhesion of U937 cells that was triggered by treatment with an anti-β1-integrin (CD29) antibody and immobilized FN, respectively. By evaluating the activation of various intracellular signaling pathways and the levels of related nuclear transcription factors, lancemaside A was found to block the activation of inhibitor of κB kinase (IKK) and p65/nuclear factor- (NF-) κB. Taken together, our findings strongly suggest that the anti-inflammatory function of lancemaside A is the result of its strong antioxidative and IKK/NF-κB inhibitory activities.

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.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) preserves gut barrier function by blocking neutrophil-endothelial cell adhesion after hemorrhagic shock and resuscitation in mice

BACKGROUND

We have shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF) protects the intestines from injury in several different animal models, including hemorrhagic shock and resuscitation (HS/R). The current study was designed to explore the mechanisms underlying the anti-inflammatory role of HB-EGF in preservation of gut barrier function after injury.

METHODS

In vivo, HS/R was induced in wild-type and neutropenic mice, with or without administration of HB-EGF, and intestinal permeability determined by use of the everted gut sac method. In vitro, cultured human umbilical vein endothelial cells (HUVECs) and freshly isolated human peripheral blood mononuclear cells (PMNs) were used to determine the effects of HB-EGF on HUVEC-PMN adhesion, reactive oxygen species production in PMN, adhesion molecule expression in HUVEC and PMN, and the signaling pathways involved.

RESULTS

We found that administration of HB-EGF to healthy mice led to preservation of gut barrier function after HS/R. Likewise, induction of neutropenia in mice also led to preservation of gut barrier function after HS/R. Administration of HB-EGF to neutropenic mice did not lead to further improvement in gut barrier function. In vitro studies showed that HB-EGF decreased neutrophil-endothelial cell (PMN-EC) adherence by down-regulating adhesion molecule expression in EC via the phosphoinositide 3-kinase-Akt pathway, and by inhibiting adhesion molecule surface mobilization and reactive oxygen species production in PMN.

CONCLUSION

These results indicate that HB-EGF preserves gut barrier function by inhibiting PMN and EC activation, thereby blocking PMN-EC adherence after HS/R in mice, and support the future use of HB-EGF in disease states manifested by hypoperfusion injury.

Effects of erythropoietin on ICAM-1 and PECAM-1 expressions on human umbilical vein endothelial cells subjected to oxidative stress

The protective effect of erythropoietin (Epo) is based on its ability to reduce oxidation and to stabilize the cells. The aim of the study was to evaluate the influence of Epo on malonyl dialdehyde (MDA), intercellular adhesion molecule-1 (ICAM-1) (CD54) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) (CD31) levels on human umbilical vein endothelial cells (HUVECs) stimulated by tumour necrosis factor-α (TNF-α). HUVECs were incubated with Epo (10-40 IU ml⁻¹) or TNF-α (10-40 ng ml⁻¹) alone or preincubated with Epo (20 IU ml⁻¹) and subsequently stimulated with TNF-α (10-40 ng ml⁻¹). MDA concentrations were measured using the high-performance liquid chromatography, whereas ICAM-1 and PECAM-1 expressions were evaluated by flow cytometry. Incubation with Epo resulted in a decrease in MDA and the increased expressions of ICAM-1 and PECAM-1. Exposure to TNF-α reflected an increase in MDA, ICAM-1 and PECAM-1 levels. These changes were inhibited by preincubation with Epo. The cytoprotective activity proven in this study points to new applications and therapeutic possibilities for Epo.

Depletion of tissue plasminogen activator attenuates lung ischemia-reperfusion injury via inhibition of neutrophil extravasation

Ischemia-reperfusion (IR) injury following lung transplantation remains a major source of early morbidity and mortality. Histologically, this inflammatory process is characterized by neutrophil infiltration and activation. We previously reported that lung IR injury was significantly attenuated in plasminogen activator inhibitor-1-deficient mice. In this study, we explored the potential role of tissue plasminogen activator (tPA) in a mouse lung IR injury model. As a result, tPA knockout (KO) mice were significantly protected from lung IR injury through several mechanisms. At the cellular level, tPA KO specifically blocked neutrophil extravasation into the interstitium, and abundant homotypic neutrophil aggregation (HNA) was detected in the lung microvasculature of tPA KO mice after IR. At the molecular level, inhibition of neutrophil extravasation was associated with reduced expression of platelet endothelial cell adhesion molecule-1 mediated through the tPA/ LDL receptor-related protein/NF-κB signaling pathway, whereas increased P-selectin triggered HNA. At the functional level, tPA KO mice incurred significantly decreased vascular permeability and improved lung function following IR. Protection from lung IR injury in tPA KO mice occurs through a fibrinolysis-independent mechanism. These results suggest that tPA could serve as an important therapeutic target for the prevention and treatment of acute IR injury after lung transplantation.

PM2.5 and PM10 induce the expression of adhesion molecules and the adhesion of monocytic cells to human umbilical vein endothelial cells

Exposure to airborne particles has been associated with an increase in cardiopulmonary events. Endothelial cells could be playing an important role in the response to airborne particles due their involvement in proinflammatory events, and there is some evidence of particle translocation from lung into circulation. One of the initiating events of inflammation is endothelial activation. We determined the concentration-response effect of a particulate matter with different aerodynamic sizes (PM2.5 [particulate matter with aerodynamic diameter of 2.5 microm and less] and PM10 [particulate matter with aerodynamic diameter of 10 microm and less]) obtained from Mexico City on human umbilical vein endothelial cells (HUVEC). The adhesion of monocytic U937 cells to HUVEC and the expression of early (E- and P-selectins) and late (ICAM-1, PECAM-1, VCAM-1) adhesion molecules were tested. Adhesion of U937 cells to HUVEC was evaluated by coculture experiments using [3H]thymidine-labeled U937 cells and the expression of adhesion molecules was evaluated by flow cytometry. Tumor necrosis factor (TNF)-alpha was used as a positive control of endothelial activation. Our results showed that both PM2.5 and PM10 induced the adhesion of U937 cells to HUVEC, and their maximal effect was observed at 20 microg/cm2. This adhesion was associated with an increase in the expression of all adhesion molecules evaluated for PM10, and E-selectin, P-selectin, and ICAM-1 for PM2.5. In general, maximum expression of adhesion molecules induced by PM2.5 and PM10 was obtained with 20 microg/cm2; however, PM10-induced expression was observed from 5 microg/cm2. E-selectin and ICAM-1 had the strongest expression in response to particles. In conclusion, PM2.5 and PM10 induce the activation of HUVEC, leading to monocytic adhesion via the expression of adhesion molecules, suggesting that these particles may participate in the development of inflammatory diseases. The role of these events in the development of diseases such as atherosclerosis is likely to be evaluated.

Atheroprotective effect of CD31 receptor globulin through enrichment of circulating regulatory T-cells

OBJECTIVES

This study was designed to evaluate whether replacing CD31 (PECAM-1) signaling can restore the regulation of lymphocyte activation and improve experimental atherosclerosis.

BACKGROUND

Atherosclerosis, the principal cause of myocardial infarction and stroke, is due to the development of a pathogenic immune response within the vascular wall and is aggravated by the reduction of regulatory T-cells. CD31, a transmembrane adhesion molecule with inhibitory signaling functions, is physiologically expressed on blood and vascular resting cells but is lost in pathologic conditions associated with atherosclerosis.

METHODS

Replacement therapy with a CD31 receptor globulin (Rg) was delivered by in vivo gene transfer in 6-week-old apolipoprotein E knockout mice (n = 14 per group) every 5 weeks for 6 months. Control groups were treated with a truncated CD31Rg or with vehicle alone. At the end of the study, plaque size and morphology and blood T-cell compartment were analyzed in all mice.

RESULTS

Atherosclerotic lesions of CD31Rg-treated mice were smaller (p < 0.01) and showed less neovascularization and intraplaque hemorrhage (p < 0.05) compared with control subjects. Furthermore, circulating regulatory T-cells were increased in vivo (p < 0.01) and showed normal suppressive function on proliferation of conventional T-cells in vitro. Indeed, CD31Rg treatment led to blunted blood T-cell activation (p < 0.05) and reduced T-cell infiltration within plaques (p < 0.01).

CONCLUSIONS

Our data suggest that CD31 plays a key role in the regulation of the immune response linked to atherosclerosis. CD31-targeting therapeutic approaches may therefore be envisaged for preventing and treating atherosclerotic diseases.

Effects of TNF-alpha on leukocyte adhesion molecule expressions in cultured human lymphatic endothelium

TNF-alpha alters leukocyte adhesion molecule expression of cultured endothelial cells like human umbilical vein endothelial cells (HUVEC). This study was designed to investigate the changes in vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and platelet endothelial cell adhesion molecule-1 (PECAM-1) expression with TNF-alpha stimulation in cultured human neonatal dermal lymphatic endothelial cells (HNDLEC). The real-time quantitative PCR analysis on HNDLEC showed that TNF-alpha treatment leads to increases of VCAM-1 and ICAM-1 mRNAs to the 10.8- and 48.2-fold levels of untreated cells and leads to a reduction of PECAM-1 mRNA to the 0.42-fold level of untreated cells. Western blot and immunohistochemical analysis showed that TNF-alpha leads to VCAM-1 and ICAM-1 expressions that were inhibited by antiserum to human TNF receptor or by AP-1 inhibitor nobiletin. In flow cytometry analysis, the number of VCAM-1- and ICAM-1-positive cells increased, and PECAM-1-positive cells decreased with TNF-alpha treatment. Regarding protein amounts produced in cells and amounts expressed on the cell surface, VCAM-1 and ICAM-1 increased in HNDLEC and HUVEC, and PECAM-1 decreased in HNDLEC in a TNF-alpha concentration-dependent manner. VCAM-1, ICAM-1, and PECAM-1 protein amounts in TNF-alpha-stimulated cells were lower in HNDLEC than in HUVEC. This suggests that the lymphatic endothelium has the TNF-alpha-induced signaling pathway, resulting in increased VCAM-1 and ICAM-1 expression to a weaker extent than blood endothelium and PECAM-1 reduction to a stronger extent than blood endothelium.

Anti-inflammatory effects of the advanced glycation end product inhibitor LR-90 in human monocytes

Ligation of advanced glycation end products (AGEs) with their receptor (RAGE) plays an important role in the development of various diabetes complications, including atherosclerosis. Monocyte activation, adhesion, and migration are key events in the pathogenesis of atherosclerosis. Previous studies showed that AGEs and S100b, a specific RAGE ligand, could augment monocyte inflammatory responses via RAGE. In this study, we examined whether LR-90, a compound belonging to a new class of AGE inhibitor, could inhibit inflammatory responses in human monocytes. Human THP-1 cells were pretreated with LR-90 and then stimulated with S100b. LR-90 significantly inhibited S100b-induced expression of RAGE and other proinflammatory genes including monocyte chemoattractant protein-1, interferon-gamma-inducible protein-10, and cyclooxygenase-2 in a dose-dependent manner. These inhibitory effects may be exerted via inhibition of nuclear factor-kappaB (NF-kappaB) activation, as LR-90 suppressed both S100b-and tumor necrosis factor-alpha-induced IkappaB-alpha degradation as well as NF-kappaB promoter transcriptional activity. LR-90 also prevented oxidative stress in activated monocytes, as demonstrated by its inhibitory effects on S100b-induced expression of NADPH oxidase and intracellular superoxide production. In addition, LR-90 blocked S100b-induced monocyte adhesion to human umbilical vein endothelial cell. These new data show that, in addition to its AGE inhibitory effects, LR-90 has novel anti-inflammatory properties and might therefore have additional protective effects against diabetic vascular complications.

Detection of differentially expressed glycogenes in trabecular meshwork of eyes with primary open-angle glaucoma

PURPOSE

To identify differentially expressed glycogenes in trabecular meshwork (TM) of eyes with primary open-angle glaucoma (POAG).

METHODS

Total RNA was isolated from TM of cadaveric eyes derived from donors with diagnosed glaucomas of different etiologies and from normal control subjects. RNA was amplified and hybridized to the GLYCOv2 oligonucleotide microarray that contains probes for carbohydrate-binding proteins, glycosyltransferases, and other genes involved in the regulation of glycosylation. Statistical analysis was used to identify differentially expressed genes between normal and POAG samples.

RESULTS

This study revealed that POAG TM and normal TM have distinct gene expression profiles. Of the 2001 genes on the array, 19 genes showed differential expression of greater than 1.4-fold in POAG. Mimecan and activinA, which have been shown to be upregulated in models of glaucoma, were both found to be elevated in POAG TM. Many genes were identified for the first time to be differentially regulated in POAG. Among the upregulated genes were: (1) cell adhesion molecules including platelet endothelial cell adhesion molecule-1 and P-selectin, both of which are targets of NFkappaB, which has been shown to be activated in glaucomatous TM; (2) lumican, a core protein of keratan sulfate proteoglycans; and (3) the receptor for IL6, a cytokine that has been shown to be upregulated in TM in response to elevated intraocular pressure. Among the downregulated genes were chondroitin-4-O-sulfotransferase involved in the synthesis of chondroitin sulfate chains and the receptor for PDGFbeta, a growth factor that has been shown to stimulate both TM cell proliferation and phagocytic activity. Results for several genes were confirmed by RTq-PCR.

CONCLUSIONS

Microarray technology was used to show, for the first time, that POAG TM has a distinct glycogene expression profile. Differentially expressed glycogenes identified in this study have not been previously investigated for their role in the pathogenesis of POAG and thus are novel factors for further study of the mechanism of the disease and for their possible use as diagnostic markers.

Genomic structure, organization and promoter analysis of the human F11R/F11 receptor/junctional adhesion molecule-1/JAM-A

The F11-receptor (F11R) (a.k.a. JAM-1, JAM-A, CD321) is a cell adhesion molecule of the immunoglobulin superfamily involved in platelet adhesion, secretion and aggregation. In addition, the F11R plays a critical role in the function of endothelial cells and in platelet adhesion to inflamed endothelium. In the present study, we used partial sequences of the human F11R gene, F11R cDNAs, and information in unannotated human genome databases, to delineate the F11R gene. We found that the F11R gene is composed of 13 exons (E1a, 1b, 1c, E1-E10) encoding two groups of mRNAs differing in length and sequence at their 5' UTRs, referred to as type 1 and type 2 messages. Type 1 cDNAs are shorter at the 5' end and contain a region not found within type 2 messages. Type 1 mRNAs are present in endothelial cells (EC), platelets, white blood cells and in the cell lines CMK, HeLa, K562, HOG and A549, while type 2 messages are limited to EC. Type 1 messages contain exons E1-E10 whereas type 2 messages usually contain exons E1a, 1c, part of E1 and E2-E10. The translation start site is localized in the 3' end of E1, common for both type 1 and type 2 messages. Expression of these messages is regulated by two alternative promoters, P1 and P2. P1 is a TATA-less promoter containing an initiator element, multiple transcription start sites, several GC and CCAAT boxes, and GATA, NF-kappaB and ets consensus sequences. The cloned P1 drives efficient expression of the luciferase reporter gene. A high level of similarity between human P1 and its rat and mouse counterparts was observed. Promoter P2, located upstream of P1, contains a TATA box, GC boxes, a CCAAT box and GATA and ets consensus sequences. 3' RACE provided evidence for variability in the 3' UTR due to the presence of two polyadenylation signals. The finding of multiple regulatory sites in the promoters supplements the biochemical evidence that the F11R has several different roles in the functional repertoire of endothelial cells, platelets and other cells. In particular, the presence of NF-kappaB provides additional evidence to the significance of the F11R function in the initiation of inflammatory thrombosis.

Alterations of renal phenotype and gene expression profiles due to protein overload in NOD-related mouse strains

BACKGROUND

Despite multiple causes, Chronic Kidney Disease is commonly associated with proteinuria. A previous study on Non Obese Diabetic mice (NOD), which spontaneously develop type 1 diabetes, described histological and gene expression changes incurred by diabetes in the kidney. Because proteinuria is coincident to diabetes, the effects of proteinuria are difficult to distinguish from those of other factors such as hyperglycemia. Proteinuria can nevertheless be induced in mice by peritoneal injection of Bovine Serum Albumin (BSA). To gain more information on the specific effects of proteinuria, this study addresses renal changes in diabetes resistant NOD-related mouse strains (NON and NOD.B10) that were made to develop proteinuria by BSA overload.

METHODS

Proteinuria was induced by protein overload on NON and NOD.B10 mouse strains and histology and microarray technology were used to follow the kidney response. The effects of proteinuria were assessed and subsequently compared to changes that were observed in a prior study on NOD diabetic nephropathy.

RESULTS

Overload treatment significantly modified the renal phenotype and out of 5760 clones screened, 21 and 7 kidney transcripts were respectively altered in the NON and NOD.B10. Upregulated transcripts encoded signal transduction genes, as well as markers for inflammation (Calmodulin kinase beta). Down-regulated transcripts included FKBP52 which was also down-regulated in diabetic NOD kidney. Comparison of transcripts altered by proteinuria to those altered by diabetes identified mannosidase 2 alpha 1 as being more specifically induced by proteinuria.

CONCLUSION

By simulating a component of diabetes, and looking at the global response on mice resistant to the disease, by virtue of a small genetic difference, we were able to identify key factors in disease progression. This suggests the power of this approach in unraveling multifactorial disease processes.

Non-viral delivery of ribozymes for cancer gene therapy

Ribozymes are RNA molecules with the capacity to effect sequence-specific cleavage of other transcripts. Since their initial discovery, there has been considerable interest in the development of ribozymes and other RNA therapeutics for gene therapy, particularly in the realm of cancer. However, as with other gene therapy applications, the delivery of ribozyme-based therapeutics to the target tissues of interest has represented a significant obstacle to the maturation of this technology to the clinical arena. This review will discuss the progress made so far in the use of non-viral methods for the systemic delivery of ribozymes for cancer gene therapy.

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.

Isolation of a Regulatory Region of Activin Receptor-Like Kinase 1 Gene Sufficient for Arterial Endothelium-Specific Expression

Activin receptor-like kinase 1 (Acvrl1; Alk1) is a type I receptor for transforming growth factor-beta (TGF-beta). ALK1 plays a pivotal role in vascular development and is involved in the development of hereditary hemorrhagic telangiectasia 2 (HHT2), a dominantly inherited vascular disorder, and pulmonary hypertension. We have previously shown that Alk1 is expressed predominantly in arterial endothelial cells (ECs). Despite recent discoveries of a number of artery-specific genes, the regulatory elements of these genes have not been characterized. To investigate the cis-acting elements essential for the artery-specific Alk1 expression, we have generated a series of transgenic constructs with various lengths and regions of Alk1 genomic fragments connected to a LacZ reporter gene, and analyzed the reporter gene expression in transgenic mice. We found that a 9.2-kb genomic fragment, which includes 2.7-kb promoter region and the entire intron 2, is sufficient to drive arterial endothelium-specific expression. The defined regulatory region, as well as the transgenic mouse lines, would be invaluable resources in studying the mechanisms underlying angiogenesis, arteriogenesis, and vascular disorders, such as HHT and pulmonary hypertension. The full text of this article is available online at http://circres.ahajournals.org.

Lactosylceramide recruits PKCalpha/epsilon and phospholipase A2 to stimulate PECAM-1 expression in human monocytes and adhesion to endothelial cells

Despite the importance of platelet/endothelial cell adhesion molecule-1 (PECAM-1, CD31) in the adhesion and diapedesis of monocytes/lymphocytes, little is known about the mechanisms by which it is regulated. We explored the role of a glycosphingolipid, lactosylceramide (LacCer), in modulating PECAM-1 expression and cell adhesion in human monocytes. We observed that LacCer specifically exerted a time-dependent increase in PECAM-1 expression in U-937 cells. Maximal increase in PECAM-1 protein occurred after incubation with LacCer for 60 min. LacCer activated PKCalpha and -epsilon by translocating them from cytosol to membrane. This was accompanied by the activation of phospholipase A(2) (PLA(2)) and the increase of cell adhesion, which were abrogated by chelerythrine chloride, 2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl)-maleimide and 12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo(3,4-c)-carbazole (GO 6976) (PKC inhibitors). Similarly, bromoenol lactone (a Ca(2+)-independent PLA(2) inhibitor) and methyl arachidonyl fluorophosphonate (an inhibitor of cytosolic PLA(2) and Ca(2+)-independent PLA(2)) inhibited LacCer-induced PLA(2) activity. Bromophenacyl bromide (a PLA(2) inhibitor) abrogated LacCer-induced PECAM-1 expression, and this was bypassed by arachidonic acid. Furthermore, the arachidonate-induced up-regulation of PECAM-1 was abrogated by indomethacin [a cyclooxygenase (COX)-1 and -2 inhibitor] or N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (a COX-2 inhibitor) but not nordihydroguaiaretic acid (a lipoxygenase inhibitor). In sum, PKCalpha/epsilon are the primary targets for the activation of LacCer. Downstream activation of intracellular Ca(2+)-independent PLA(2) and/or cytosolic PLA(2) results in the production of arachidonic acid, which in turn serves as a precursor for prostaglandins that subsequently stimulate PECAM-1 expression and cell adhesion. These findings may be relevant in explaining the role of LacCer in the regulation of PECAM-1 and related pathophysiology.

Identification of gene function and functional pathways by systemic plasmid-based ribozyme targeting in adult mice

To date, functional genomic studies have been confined to either cell-based assays or germline mutations, using transgenic or knockout animals. However, these approaches are often unable either to recapitulate complex biologic phenotypes, such as tumor metastasis, or to identify the specific genes and functional pathways that produce serious diseases in adult animals. Although the transcription factor NF-kappaB transactivates many metastasis-related genes in cells, the precise genes and functional-pathways through which NF-kappaB regulates metastasis in tumor-bearing hosts are poorly understood. Here, we show that the systemic delivery of plasmid-based ribozymes targeting NF-kappaB in adult, tumor-bearing mice suppressed NF-kappaB expression in metastatic melanoma cells, as well as in normal cell types, and significantly reduced metastatic spread. Plasmid-based ribozymes suppressed target-gene expression with sequence specificity not achievable by using synthetic oligonucleotide-based approaches. NF-kappaB seemed to regulate tumor metastasis through invasion-related, rather than angiogenesis-, cell-cycle- or apoptosis-related pathways in tumor-bearing mice. Furthermore, ribozymes targeting either of the NF-kappaB-regulated genes, integrin beta(3) or PECAM-1 (a ligand-receptor pair linked to cell adhesion), reduced tumor metastasis at a level comparable to NF-kappaB. These studies demonstrate the utility of gene targeting by means of systemic, plasmid-based ribozymes to dissect out the functional genomics of complex biologic phenotypes, including tumor metastasis.

Expression of CD31 by cells of extensive ductal in situ and invasive carcinomas of the breast

CD31, an adhesion molecule expressed by endothelial cells, leukocytes, and platelets, is used in surgical pathology as a marker of normal and neoplastic vascularization. During the assessment of angiogenesis in breast carcinomas, CD31 expression was observed in a single case of large (5.2 cm diameter) high nuclear grade ductal carcinoma in situ (HG-DCIS) associated with poorly differentiated invasive ductal carcinoma (G3-IDC). Expression was limited to the cell membrane. This study focused on 32 HG-DCIS> or = 2 cm, either pure or associated with IDC. Cancer cells wereCD31(+) in 11 cases. Double staining using anti-CD31 monoclonal antibody (MAb) and anti-CD44 MAb, the anti-hyaluronate receptor, showed that foci of CD31(+) and CD44(-) tumour cells could be traced throughout the glandular tree, marking the intraductal diffusion of tumour up to Paget's cells at the nipple. The associated G3-IDC and their lymph node metastases were instead CD31(+) and CD44(+). CD31(+) tumours were oestrogen receptor (ER)(-), frequently p53(+) and c-erb-B2(+), and infiltrated by CD4(+) T lymphocytes. Normal and hyperplastic epithelia were constantly CD31(-). Other endothelial markers (e.g Factor VIII-RA and CD34) were not expressed by carcinoma cells, as was CD38, the CD31 ligand. In conclusion, CD31 expression is a feature acquired by breast cancer cells in the DCIS model. CD31 expression mainly correlates with tumour cells spreading within the ductal system. Finally, the invasive phenotype requires the co-expression of CD31 and CD44.

Structural characterization and chromosomal localization of the mouse cDNA and gene encoding the bone tyrosine phosphatase, mOST-PTP

Tyrosine kinases and phosphatases are regulators of the steady-state levels of phosphotyrosine proteins and, in this way, are key players in determining the functional state of the cell. As a unique member of the protein tyrosine phosphatase (PTP) superfamily, osteotesticular PTP (OST-PTP) is a receptor protein whose expression is highly regulated during osteoblast differentiation and in response to modulators of bone remodeling such as parathyroid hormone and vitamin D3. To explore the molecular mechanisms and signaling pathways important in the regulation of this gene, we characterized the structural organization of the mouse OST-PTP cDNA and gene and determined its chromosomal localization. The mouse cDNA is approximately 5.5 kb including 5.1 kb of coding sequence, 315 bp 5' UTR and 102 bp 3' UTR. It is expressed as a single approximately 5.8 kb transcript in day 8 differentiated MC3T3 osteoblasts. Although highly homologous to the rat OST-PTP cDNA, the mouse cDNA possesses a 74 bp insert in the 5' UTR which contains several potential transcription factor binding sites such as AP-2 and NFkappaB. The mouse OST-PTP (mOST-PTP) gene is a single copy gene encompassing 35 exons and spanning only 20.65 kb. As such, it is the smallest gene of the characterized receptor PTP genes. This is due to the lack of large introns and the conserved spatial organization of exons which encode specific protein motifs in the mOST-PTP molecule. Sequence analysis of the putative mOST-PTP promoter revealed basal elements as well as many potential cis-acting regulatory elements with relevance to gene regulation in bone. Of particular interest is the single osteoblast specific element known as osteocalcin specific element 2 (OSE2) found at position -1867, as well as numerous VDRE and NFkappaB sites found throughout the promoter and the 5' UTR. Fluorescence in situ hybridization studies have shown that mOST-PTP localizes to mouse chromosome 1, region F-G which is syntenic to the segment of human chromosome 1q32-33. This characterization of the mOST-PTP cDNA and gene will facilitate future experiments exploring the mechanisms of regulation of this phosphatase during osteogenesis.