VCAM-1 signals during lymphocyte migration: role of reactive oxygen species

Mechanisms of transendothelial migration of leukocytes

A great deal of progress has been made recently in understanding the molecules and mechanisms that regulate transendothelial migration of leukocytes, or diapedesis, a critical step in the inflammatory response. This review focuses mainly on the active role of the endothelial cell in this process as it occurs at endothelial cell borders. It discusses some of the many molecules that have been reported to play a role in transendothelial migration and asks why so many molecules seem to be involved. The concept is emerging that diapedesis itself can be dissected into sequential steps controlled by specific molecule(s) at the endothelial cell border. Several mechanisms have been shown to play a critical role in transendothelial migration including signals derived from clustering of apically disposed intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, disruption or loosening of adherens junctions, and targeted recycling of platelet/endothelial cell adhesion molecule and other molecules from the recently described lateral border recycling compartment. A hypothesis that integrates the various known mechanisms is proposed.

Molecular basis of leukocyte-endothelium interactions during the inflammatory response

The process of leukocyte extravasation, a critical step in the inflammatory response, involves the migration of leukocytes from the bloodstream towards target tissues, where they exert their effector function. Leukocyte extravasation is orchestrated by the combined action of cellular adhesion receptors and chemotactic factors, and involves radical morphological changes in both leukocytes and endothelial cells. Thus, it constitutes an active process for both cell types and promotes the rapid and efficient influx of leukocytes to inflammatory foci without compromising the integrity of the endothelial barrier. This article provides a review of leukocyte extravasation from both molecular and mechanical points of view, with a particular emphasis on the most recent findings on the topic. It includes a description of newly revealed steps in the adhesion cascade, such as slow rolling motion, intraluminal crawling and alternative pathways for transcellular migration, and discusses the functional role of novel adhesion receptors, the spatiotemporal organization of receptors at the plasma membrane and the signaling pathways that control different phases of the extravasation process.

Altered hepatic mRNA expression of immune response and apoptosis-associated genes after acute and chronic psychological stress in mice

Using a combination of transcriptional profiling and Ingenuity Pathway Analysis (IPA, www.ingenuity.com) we investigated acute and chronic psychological stress induced alterations of hepatic gene expression of BALB/c mice. Already after a 2-h single stress session, up-regulation of several LPS and glucocorticoid-sensitive immune response genes and markers related to oxidative stress and apoptotic processes were observed. Support for the existence of oxidative stress was gained by measuring increased protein carbonylation, but no alterations of immune responsiveness or cell death were measured in mice after acute stress compared to the control group. When animals were repeatedly stressed during 4.5-days, we found reduced transcription of antigen presentation molecules, altered mRNA levels of immune cell signaling mediators and persisting high expression of apoptosis-related genes. These alterations were associated with a measurable immune suppression characterized by a reduced ability to clear experimental Salmonella typhimurium infection from the liver and a heightened hepatocyte apoptosis. Moreover, genes associated with anti-oxidative functions and regenerative processes were induced in the hepatic tissue of chronically stressed mice. These findings indicate that modulation of the immune response and of apoptosis-related genes is initiated already during a single acute stress exposure. However, immune suppression will only manifest in repeatedly stressed mice which additionally show induction of protective and liver regenerative genes to prevent further hepatocyte damage.

A HaemAtlas: characterizing gene expression in differentiated human blood cells

Hematopoiesis is a carefully controlled process that is regulated by complex networks of transcription factors that are, in part, controlled by signals resulting from ligand binding to cell-surface receptors. To further understand hematopoiesis, we have compared gene expression profiles of human erythroblasts, megakaryocytes, B cells, cytotoxic and helper T cells, natural killer cells, granulocytes, and monocytes using whole genome microarrays. A bioinformatics analysis of these data was performed focusing on transcription factors, immunoglobulin superfamily members, and lineage-specific transcripts. We observed that the numbers of lineage-specific genes varies by 2 orders of magnitude, ranging from 5 for cytotoxic T cells to 878 for granulocytes. In addition, we have identified novel coexpression patterns for key transcription factors involved in hematopoiesis (eg, GATA3-GFI1 and GATA2-KLF1). This study represents the most comprehensive analysis of gene expression in hematopoietic cells to date and has identified genes that play key roles in lineage commitment and cell function. The data, which are freely accessible, will be invaluable for future studies on hematopoiesis and the role of specific genes and will also aid the understanding of the recent genome-wide association studies.

Characterization of gene expression profiles for different types of mast cells pooled from mouse stomach subregions by an RNA amplification method

Background

Mast cells (MCs) play pivotal roles in allergy and innate immunity and consist of heterogenous subclasses. However, the molecular basis determining the different characteristics of these multiple MC subclasses remains unclear.

Results

To approach this, we developed a method of RNA extraction/amplification for intact in vivo MCs pooled from frozen tissue sections, which enabled us to obtain the global gene expression pattern of pooled MCs belonging to the same subclass. MCs were isolated from the submucosa (sMCs) and mucosa (mMCs) of mouse stomach sections, respectively, 15 cells were pooled, and their RNA was extracted, amplified and subjected to microarray analysis. Known marker genes specific for mMCs and sMCs showed expected expression trends, indicating accuracy of the analysis.

We identified 1,272 genes showing significantly different expression levels between sMCs and mMCs, and classified them into clusters on the basis of similarity of their expression profiles compared with bone marrow-derived MCs, which are the cultured MCs with so-called 'immature' properties. Among them, we found that several key genes such as Notch4 had sMC-biased expression and Ptgr1 had mMC-biased expression. Furthermore, there is a difference in the expression of several genes including extracellular matrix protein components, adhesion molecules, and cytoskeletal proteins between the two MC subclasses, which may reflect functional adaptation of each MC to the mucosal or submucosal environment in the stomach.

Conclusion

By using the method of RNA amplification from pooled intact MCs, we characterized the distinct gene expression profiles of sMCs and mMCs in the mouse stomach. Our findings offer insight into possible unidentified properties specific for each MC subclass.

ICAM-1-mediated endothelial nitric oxide synthase activation via calcium and AMP-activated protein kinase is required for transendothelial lymphocyte migration

As a gatekeeper of leukocyte trafficking the vasculature fulfills an essential immune function. We have recently shown that paracellular transendothelial lymphocyte migration is controlled by intercellular adhesion molecule 1 (ICAM-1)-mediated vascular endothelial cadherin (VEC) phosphorylation [Turowski et al., J. Cell Sci. 121, 29-37 (2008)]. Here we show that endothelial nitric oxide synthase (eNOS) is a critical regulator of this pathway. ICAM-1 stimulated eNOS by a mechanism that was clearly distinct from that utilized by insulin. In particular, phosphorylation of eNOS on S1177 in response to ICAM-1 activation was regulated by src family protein kinase, rho GTPase, Ca(2+), CaMKK, and AMPK, but not Akt/PI3K. Functional neutralization of any component of this pathway or its downstream effector guanylyl cyclase significantly reduced lymphocyte diapedesis across the endothelial monolayer. In turn, activation of NO signaling promoted lymphocyte transmigration. The eNOS signaling pathway was required for T-cell transmigration across primary rat and human microvascular endothelial cells and also when shear flow was applied, suggesting that this pathway is ubiquitously used. These data reveal a novel and essential role of eNOS in basic immune function and provide a key link in the molecular network governing endothelial cell compliance to diapedesis.

Induction of ICAM-1 and VCAM-1 on the mouse lingual lymphatic endothelium with TNF-alpha

This study investigated the TNF-α-induced ICAM-1 and VCAM-1 expression on mouse lingual lymphatic vessels. All podoplanin-positive lymphatic vessels expressed PECAM-1. In the lamina propria mucosae of TNF-α-treated tongue, almost all initial lymphatics expressed ICAM-1. There were initial lymphatics with the VCAM-1 expression and also the vessels without the expression. In the tunica muscularis of TNF-α-treated tongue, collecting lymphatic vessels expressed ICAM-1, but rarely expressed VCAM-1 whereas blood vessels simultaneously expressed ICAM-1 and VCAM-1. The ICAM-1-positive rate increased with TNF-α to 75% from 10% on initial lymphatics, and to 40% from 0% on collecting lymphatic vessels while it increased to 90% from 45% on blood vessels. The VCAM-1-positive rate increased with TNF-α to 30% from 0% on initial lymphatics, and to 5% from 0% on collecting lymphatic vessels while it increased to 75% from 5% on blood vessels. These findings suggest that the lingual lymphatic endothelium has the ability to express ICAM-1, and VCAM-1 to a lesser extent than the ICAM-1 induction with TNF-α, and that the ICAM-1 and VCAM-1 induction predominantly occurs in the initial lymphatics compared with collecting lymphatic vessels.

Involvement of native TRPC3 proteins in ATP-dependent expression of VCAM-1 and monocyte adherence in coronary artery endothelial cells

Background- Vascular cell adhesion molecule-1 (VCAM-1) is critical in monocyte recruitment to the endothelium, a key event in development of atherosclerotic lesions. Stimulation of human coronary artery endothelial cells (HCAECs) with ATP positively modulates VCAM-1 expression and function through a mechanism involving Ca(2+) signaling. We here examined the role of Ca(2+) influx and native TRPC3 channels in that mechanism.

METHODS AND RESULTS

Omission of extracellular Ca(2+) or pretreatment of cells with channel blockers markedly reduced ATP-induced VCAM-1 and monocyte adhesion. Using a siRNA strategy and real-time fluorescence, we found that native TRPC3 proteins contribute to constitutive and ATP-regulated Ca(2+) influx. ATP-dependent upregulation of VCAM-1 was accompanied by an increase in basal cation entry and TRPC3 expression. Notably, TRPC3 knock-down resulted in a dramatic reduction of ATP-induced VCAM-1 and monocyte adhesion.

CONCLUSIONS

These findings indicate that in HCAECs, native TRPC3 proteins form channels that contribute to constitutive and ATP-dependent Ca(2+) influx, and that TRPC3 expression and function are fundamental to support VCAM-1 expression and monocyte binding. This is the first evidence to date relating native TRPC3 proteins with regulated expression of cell adhesion molecules in coronary endothelium, and suggests a potential pathophysiological role of TRPC3 in coronary artery disease.

Increased incidence of urinary matrix metalloproteinases as predictors of disease in pediatric patients with inflammatory bowel disease

BACKGROUND

Matrix metalloproteinases (MMPs) are a family of metal-dependent enzymes responsible for the degradation and remodeling of extracellular matrix and basement membrane proteins that occurs during both normal physiologic activity and disease. It has been suggested that MMPs may also play a role in the pathogenesis of inflammatory bowel disease (IBD) by mediating mucosal breakdown in response to an enhanced inflammatory cascade. We previously demonstrated that elevated urinary MMP levels are independent predictors of disease status in cancer patients. Here we demonstrate that elevated urinary MMP levels may be biomarkers of disease activity in patients with IBD.

METHODS

We analyzed 95 urine samples prospectively collected from 55 children and young adults with known or suspected IBD who presented for evaluation to the Gastrointestinal Procedure Unit at Children's Hospital Boston. Urinary MMPs were analyzed in patients by zymography and compared to 40 age- and sex-matched controls.

RESULTS

Urinary MMP levels were significantly elevated (P < 0.0001) in patients with IBD, as well as in each subgroup (Crohn's disease or ulcerative colitis), relative to controls. Multiple logistic regression revealed that urinary MMP-2 and MMP-9 NGAL levels were independent predictors of Crohn's disease and ulcerative colitis (P < 0.0001).

CONCLUSIONS

These data are the first to demonstrate that urinary MMPs may represent novel noninvasive biomarkers for use in the evaluation of patients with IBD.

Molecular mechanisms of felodipine suppressing atherosclerosis in high-cholesterol-diet apolipoprotein E-knockout mice

Oxidative stress and inflammation processes are key components of atherosclerosis, from fatty streak formation to plaque rupture and thrombosis. Evidence has revealed that calcium-channel blockers (CCB) could retard atherogenesis, but the exact mechanisms have not been fully elucidated. The present study was undertaken to investigate the potential effects and molecular mechanisms of the CCB felodipine on the process of atherosclerosis in high-cholesterol-diet (HCD) apolipoprotein E-knockout (ApoE KO) mice. Adult male ApoE KO mice were given a normal diet (ND) or HCD and were randomized to no treatment or felodipine (5 mg / kg per day for 12 weeks). The ApoE KO mice with HCD were associated with a marked increase in plasma lipid levels, atherosclerotic lesion area, and the expressions of NADPH oxidase subunits (p47 and Rac-1), nuclear factor-kappaB (NF-kappaB) in nucleus, phosphor-inhibitors of kappaB (p-IkappaB), tumor necrosis-alpha (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), and vascular cell-adhesion molecule-1 (VCAM-1). These changes were suppressed in mice that were treated with felodipine (5 mg/kg per day for 12 weeks) concomitant with HCD administration, with no significant change in systolic blood pressure and plasma lipid levels. The results suggest that felodipine can attenuate atherosclerosis, and this effect is partly related to inhibition of oxidative stress and inflammatory signal-transduction pathways, which lead to decreases in the expression of inflammatory cytokines.

Leukocyte adhesion molecule and chemokine production through lipoteichoic acid recognition by toll-like receptor 2 in cultured human lymphatic endothelium

We have recently reported that the human lymphatic endothelium has toll-like receptor 4 (TLR4)-mediated lipopolysaccharide recognition mechanisms that induce the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Although ligand engagement with TLR2 enables activation of the MyD88-dependent pathway similarly to TLR4, whether TLR2 ligands such as lipoteichoic acid (LTA) trigger the activation of lymphatic endothelium remains unclear. This study has been designed to investigate the expression dynamics of LTA-induced leukocyte adhesion molecules and chemokines in cultured human lymphatic endothelium (LEC). Reverse transcription/polymerase chain reaction (RT-PCR) and real-time quantitative PCR analyses have shown that LEC usually expresses TLR2 and increases TLR2 gene expression on LTA treatment. Indeed, LTA-treated LEC increases the expression of E-selectin, ICAM-1, and VCAM-1 but does not alter the gene expression of ICAM-2, ICAM-3, junctional adhesion molecule-1 (JAM-1), JAM-3, or platelet endothelial cell adhesion molecule-1 (PECAM-1). The expression of LTA-induced E-selectin, ICAM-1, and VCAM-1 in LEC is suppressed by anti-TLR2 but not by anti-TLR4 and is also suppressed by TLR2-specific short interfering RNA (siRNA) but not by siRNA for TLR4. The expression of CCL2, CCL5, and CCL20 (Cys-Cys motif chemokines) and of CXCL1, CXCL3, CXCL5, CXCL6, and CXCL8 (Cys-X-Cys motif chemokines) was induced in LEC with LTA. These data suggest that the human lymphatic endothelial phenotype has TLR2-mediated LTA-recognition mechanisms, resulting in increased expression of inflammatory leukocyte adhesion molecules and phagocyte-attractive chemokines. The human lymphatic endothelium may thus function to collect leukocytes from tissues into lymphatic vessels by means of immunologically functional molecules.

Plasma pentraxin 3 in patients with chronic kidney disease: associations with renal function, protein-energy wasting, cardiovascular disease, and mortality

BACKGROUND AND OBJECTIVES

Plasma protein pentraxin 3 concentrations are elevated in a wide range of diseased states. However, no study has evaluated protein pentraxin 3 in patients with chronic kidney disease.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Plasma protein pentraxin 3 concentrations were analyzed in relation to GFR, inflammation, cardiovascular disease, and protein-energy wasting in 71 patients with stages 3 to 4 chronic kidney disease, 276 patients with stage 5 chronic kidney disease, and 61 control subjects. Survival (5 yr) in patients with stage 5 chronic kidney disease was analyzed in relation to protein pentraxin 3 levels.

RESULTS

Both patient groups with chronic kidney disease had higher protein pentraxin 3 concentrations than control subjects, with the highest concentration in patients with stage 5 chronic kidney disease. In all patients with chronic kidney disease, protein pentraxin 3 correlated negatively with GFR and positively with inflammatory markers. Patients with protein-energy wasting, inflammation, and cardiovascular disease had higher concentrations of protein pentraxin 3 than their counterparts. Patients with high protein pentraxin 3 levels had higher all-cause and cardiovascular mortality. After adjustment for age, gender, C-reactive protein, and cardiovascular disease, all-cause mortality was still significantly higher in patients with high protein pentraxin 3. Finally, protein pentraxin 3 showed a predictive value of mortality similar to that of IL-6 and better than C-reactive protein.

CONCLUSION

Plasma protein pentraxin 3 increases as GFR declines and is associated with the presence of cardiovascular disease and protein-energy wasting. Furthermore, in patients with chronic kidney disease, elevated protein pentraxin 3 predicted all-cause mortality.

Propionyl-L-Carnitine Prevents Age-Related Myocardial Remodeling in the Rabbit

Age-related cardiac remodeling is characterized by changes in myocardial structure, which include fibrosis (ie, increased collagen concentration). The pathogenetic mechanisms of age-related cardiac changes and possible pharmacologic interventions are still a matter of investigation. A morphometric analysis of collagen accumulation was performed in Sirius Red-stained left ventricular sections of 3-month-old and 5-6-year-old animals after a 9-month period of propionyl-L-carnitine treatment (PLC; 120 mg Kg(-1) day(-1) per os); aged rabbits showed decreased interstitial collagen accumulation and no changes in cellularity and apoptotic rate compared to controls. Age-related expression of vascular cell adhesion molecule-1 (VCAM-1)-positive microvessels was also reduced in PLC-treated rabbits. In vitro, the 16-hour, 10-microM PLC treatment reduced collagen type 1 and VCAM-1 transcripts, which were investigated by reverse transcription-polymerase chain reaction, more markedly in cardiac fibroblasts from aged donors. In the latter, the anti-VCAM-1 antibody treatment was found to be associated with a reduction in collagen type I transcripts. Our results demonstrated that long-term PLC treatment partially prevents age-related interstitial remodeling and suggests that a more complex interstitial cell-to-cell signaling regulates senescent myocardium properties.

Endothelial signaling by Ig-like cell adhesion molecules

The migration of leukocytes across the endothelial lining of the vascular wall requires a complicated series of adhesion and signaling events. Endothelial Ig-like cell adhesion molecules (IgCAMs) such as intercellular adhesion molecule-1 play an important role, not only as ligands for leukocyte integrins, but also as signaling initiators. Clustering these IgCAMs triggers a wide range of events in the endothelial cells' interior, of which activation of Rho-like GTPases, induction of cytoskeletal changes, and the transient modulation of cell-cell contact are key events. This review discusses recent insights into this IgCAM-driven endothelial signaling and its consequences for leukocyte transendothelial migration.

B-1a cells are imprinted by the microenvironment in spleen and peritoneum

B-1a cells are found mainly in the peritoneal cavity of mice but are also present in the spleen. Gene expression profiling defined many genes differentially expressed in B-1a cells from these two sites. To see whether this gene expression pattern was imprinted by the particular microenvironment, peritoneal or spleen cells from recombinant L2 mice mainly consisting of B-1a cells were adoptively transferred into Rag1-/- mice. Re-isolated peritoneal and splenic B-1a cells were analyzed for expression of three indicator genes--vcam-1, adamdec1 and spi-c. The expression of these genes was up-regulated in splenic and down-regulated in peritoneal cells. This particular pattern was observed for peritoneal or splenic donor cells transferred either intraperitoneally or intravenously. Similar results were obtained when levels of surface IgM or frequencies of Mac-1+ B-1 cells were compared after transfer. This suggests that the environment induces the particular genetic program of B-1a cells and argues against an independent ontogeny.

Platelet inhibitors in non-ST-segment elevation acute coronary syndromes and percutaneous coronary intervention: glycoprotein IIb/IIIa inhibitors, clopidogrel, or both?

The role of glycoprotein (Gp) IIb/IIIa receptor antagonists remains controversial and these agents are infrequently utilized during non-ST-segment elevation acute coronary syndromes (NSTE-ACS) despite American Heart Association/American College of Cardiology guidelines. Despite recommendations, the NRMI-4 (National Registry of Myocardial Infarction 4) and CRUSADE (Can rapid risk stratification of unstable angina patients suppress adverse outcomes with early implementation of the ACC/AHA guidelines?) registries observed that only 25%-32% of eligible patients received early Gp IIb/IIIa therapy, despite a 6.3% absolute mortality reduction in NRMI-4 and a 2% absolute mortality reduction in CRUSADE. A pooled analysis of Gp IIb/IIIa data from these registries suggest a major reduction in mortality (Odds Ratio = 0.43, 95% Confidence Index 0.25-0.74, p = 0.002) with early Gp IIb/IIIa therapy, yet clinicians fail to utilize this option in NSTE-ACS. The evidence-based approach to NSTE-ACS involves aspirin, clopidogrel, low-molecular weight heparins, or unfractionated heparin in concert with Gp IIb/Ila receptor antagonists, however, newer percutaneous coronary intervention (PCI)-based trials challenge current recommendations. Novel strategies emerging in NSTE-ACS include omitting Gp IIb/Ila inhibitors altogether or using Gp IIb/IIIa inhibitors with higher doses of clopidogrel in selected patients. The ISAR-REACT (Intracoronary stenting and antithrombotic regimen-Rapid early action for coronary treatment) and ISAR-SWEET (ISAR-Is abciximab a superior way to eliminate elevated thrombotic risk in diabetics) trials question the value of abciximab when 600 mg of clopidogrel concurrently administered during PCI. The CLEAR-PLATELETS (Clopidogrel loading with eptifibatide to arrest the reactivity of platelets) and PEACE (Platelet activity extinction in non-Q-wave MI with ASA, clopidogrel, and eptifibatide) trials suggest more durable platelet inhibition when Gp IIb/IIIa inhibitors are used with higher doses clopidogrel. The ISAR-COOL (ISAR: Cooling off strategy) trial found no difference in ischemic outcomes when Gp IIb/IIIa inhibitors were excluded and ARMYDA-2 (Antiplatelet therapy for reduction of myocardial damage during angioplasty) suggested higher doses of clopidogrel are more appropriate during PCI when Gp IIb/IIIa inhibitors are not utilized. This constellation of new trials forces reconsideration of current recommendations in regards to patient risk stratification, choice of antithrombotic therapy, doses, and timing. These new data will impact emerging guidelines and updates are currently in progress.

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.

FoxOs are lineage-restricted redundant tumor suppressors and regulate endothelial cell homeostasis

Activated phosphoinositide 3-kinase (PI3K)-AKT signaling appears to be an obligate event in the development of cancer. The highly related members of the mammalian FoxO transcription factor family, FoxO1, FoxO3, and FoxO4, represent one of several effector arms of PI3K-AKT signaling, prompting genetic analysis of the role of FoxOs in the neoplastic phenotypes linked to PI3K-AKT activation. While germline or somatic deletion of up to five FoxO alleles produced remarkably modest neoplastic phenotypes, broad somatic deletion of all FoxOs engendered a progressive cancer-prone condition characterized by thymic lymphomas and hemangiomas, demonstrating that the mammalian FoxOs are indeed bona fide tumor suppressors. Transcriptome and promoter analyses of differentially affected endothelium identified direct FoxO targets and revealed that FoxO regulation of these targets in vivo is highly context-specific, even in the same cell type. Functional studies validated Sprouty2 and PBX1, among others, as FoxO-regulated mediators of endothelial cell morphogenesis and vascular homeostasis.

Blood-brain barrier: structural components and function under physiologic and pathologic conditions

The blood-brain barrier (BBB) is the specialized system of brain microvascular endothelial cells (BMVEC) that shields the brain from toxic substances in the blood, supplies brain tissues with nutrients, and filters harmful compounds from the brain back to the bloodstream. The close interaction between BMVEC and other components of the neurovascular unit (astrocytes, pericytes, neurons, and basement membrane) ensures proper function of the central nervous system (CNS). Transport across the BBB is strictly limited through both physical (tight junctions) and metabolic barriers (enzymes, diverse transport systems). A functional polarity exists between the luminal and abluminal membrane surfaces of the BMVEC. As a result of restricted permeability, the BBB is a limiting factor for the delivery of therapeutic agents into the CNS. BBB breakdown or alterations in transport systems play an important role in the pathogenesis of many CNS diseases (HIV-1 encephalitis, Alzheimer's disease, ischemia, tumors, multiple sclerosis, and Parkinson's disease). Proinflammatory substances and specific disease-associated proteins often mediate such BBB dysfunction. Despite seemingly diverse underlying causes of BBB dysfunction, common intracellular pathways emerge for the regulation of the BBB structural and functional integrity. Better understanding of tight junction regulation and factors affecting transport systems will allow the development of therapeutics to improve the BBB function in health and disease.

Transcriptional regulation of VCAM-1 expression by tumor necrosis factor-alpha in human tracheal smooth muscle cells: involvement of MAPKs, NF-kappaB, p300, and histone acetylation

Tumor necrosis factor-alpha (TNF-alpha) has been shown to induce the expression of adhesion molecules in airway resident cells and contribute to inflammatory responses. Here, the roles of mitogen-activated protein kinases (MAPKs) and NF-kappaB in TNF-alpha-induced expression of vascular cell adhesion molecule (VCAM)-1 were investigated in human tracheal smooth muscle cells (HTSMCs). TNF-alpha-enhanced expression of VCAM-1 protein and mRNA as well as phosphorylation of p42/p44 MAPK, p38, and JNK were significantly attenuated by inhibitors of MEK1/2 (U0126), p38 (SB202190), and JNK (SP600125). Transfection with dominant negative mutants of MEK1/2, ERK1, ERK2, p38, and JNK attenuated TNF-alpha-induced VCAM-1 expression. Furthermore, TNF-alpha-induced VCAM-1 expression was significantly blocked by a selective NF-kappaB inhibitor helenalin. TNF-alpha-stimulated translocation of NF-kappaB into the nucleus and degradation of IkappaB-alpha was blocked by helenalin, but not by U0126, SB202190, or SP600125. VCAM-1 promoter activity was enhanced by TNF-alpha in HTSMCs transfected with VCAM-1-Luc, which was inhibited by helenalin, U0126, SB202190, and SP600125. Most surprisingly, VCAM-1 expression was also significantly blocked by a selective inhibitor of p300, curcumin. NF-kappaB transcription factor and p300 were associated with the VCAM-1 promoter, which was dynamically linked to histone H3 acetylation stimulated by TNF-alpha, as determined by chromatin immunoprecipitation assay. Moreover, the resultant enhancement of VCAM-1 expression increased the adhesion of polymorphonuclear cells (PMNs) to monolayer of HTSMCs, which was blocked by helenalin, U0126, SB202190, or SP600125. These results suggest that in HTSMCs, activation of MAPK pathways, NF-kappaB, and p300 is essential for TNF-alpha-induced VCAM-1 expression.

TNF-alpha-secreting monocytes are recruited into the brain of cholestatic mice

Signaling occurs between the liver and brain in cholestatic liver disease, giving rise to sickness behaviors such as fatigue. However, the signaling pathways involved are poorly defined. Circulating inflammatory mediator levels are increased in cholestasis, leading to speculation that they may be capable of activating circulating immune cells that subsequently could gain access to the brain. Indeed, we have identified that at day 10 after bile duct resection-induced cholestasis, there is activation of circulating monocytes that express tumor necrosis factor alpha (TNF-alpha) in conjunction with increased expression of adhesion molecules by cerebral endothelium. Moreover, using intravital microscopy, we have identified markedly enhanced leukocytes rolling along cerebral endothelial cells, mediated by P-selectin, in bile duct-resected (BDR) but not control mice. In addition, we have identified increased infiltration of monocytes (but not lymphocytes) into the brains of BDR mice and found that these infiltrating monocytes produce TNF-alpha. Furthermore, infiltration of TNF-alpha-secreting monocytes into the brains of cholestatic mice is associated with a broad activation of resident brain macrophages to produce TNF-alpha. In conclusion, cholestasis is associated with an activation of cerebral endothelium that recruits TNF-alpha-producing monocytes into the brain. We hypothesize that enhanced TNF-alpha release within the brain may contribute to the development of cholestasis-associated sickness behaviors, including fatigue.

Role of matrix metalloproteinases in inflammatory bowel disease

Recent evidence demonstrates that the increased expression and activity of matrix metalloproteinases (MMPs) may contribute to intestinal tissue injury and inflammation in inflammatory bowel disease, and that MMP inhibition might be a new therapeutic approach to controlling inflammatory response. In addition, MMPs may play a crucial role in physiological and pathophysiological reactions such as leukocyte accumulation into inflamed tissue, cytokine production from inflammatory and epithelial cells, T lymphocyte homing to the intestine, wound healing and proliferation of epithelial cells, and intestinal innate immunity. This review focuses on recent progress in elucidating the biological and pathological roles of MMPs in inflammatory bowel disease.

Zinc deficiency increases plasma lipids and atherosclerotic markers in LDL-receptor-deficient mice

Low zinc concentration can be associated with an increased risk of cardiovascular diseases. In the current study, we hypothesize that zinc deficiency can increase and zinc supplementation can decrease proatherosclerotic events in LDL receptor knock-out (LDL-R-/-) mice fed a moderate-fat diet. Mice were fed either a zinc-deficient (0 micromol Zn/g), a control (0.45 micromol Zn/g), or a zinc-supplemented (1.529 micromol Zn/g) diet for 4 wk. Mice fed the zinc-deficient diet had significantly increased concentrations of cholesterol and triacylglycerides in the VLDL and HDL fractions. Zinc supplementation decreased these lipid variables compared with control mice. We detected significantly higher concentrations of glutathione reductase mRNA in the thoracic aortae of zinc-deficient mice. Furthermore, inflammatory markers, such as nuclear factor-kappaB and vascular cell adhesion molecule-1, were significantly increased in zinc-deficient mice compared with mice of the control or supplemented groups. In addition, zinc deficiency significantly reduced the DNA binding activity of peroxisome proliferator activate receptors (PPARs) in liver extracts. Interestingly, mRNA expression levels of PPARgamma were significantly increased in thoracic aortae of zinc-deficient mice, indicating an adaptation process to decreased PPAR signaling. These data provide in vivo evidence of zinc deficiency inducing proinflammatory events in an atherogenic mouse model. These data also suggest that adequate zinc may be a critical component in protective PPAR signaling during atherosclerosis.

Rho GTPases and leucocyte-induced endothelial remodelling

Leucocytes in the bloodstream respond rapidly to inflammatory signals by crossing the blood vessel wall and entering the tissues. This process involves adhesion to, and subsequent transmigration across, the endothelium, mediated by a cascade of interactions between adhesion molecules and stimulation of intracellular signalling pathways in both leucocytes and endothelial cells. This leads to changes in endothelial cell morphology that assist leucocyte extravasation, including endothelial cell contraction, intercellular junction disruption, increased permeability, remodelling of the endothelial apical surface and alterations in vesicle trafficking. Rho GTPases play a central role in many of the endothelial responses to leucocyte interaction. In this review, we discuss recent findings on leucocyte-induced alterations to endothelial cells, and the roles of Rho GTPases in these responses.

Unconjugated bilirubin inhibits VCAM-1-mediated transendothelial leukocyte migration

During lymphocyte migration, engagement of VCAM-1 stimulates the generation of endothelial cell-derived reactive oxygen species (ROS) and activation of matrix metalloproteinases, facilitating endothelial retraction. Because bilirubin is a potent antioxidant, we examined the hypothesis that this bile pigment inhibits VCAM-1-dependent cellular events. The migration of isolated murine splenic lymphocytes across monolayers of murine endothelial cell lines (which constitutively express VCAM-1) is significantly inhibited by physiological concentrations of bilirubin, in the absence of an effect on lymphocyte adhesion. Bilirubin administration also suppresses VCAM-1-stimulated ROS generation and reduces endothelial cell matrix metalloproteinase activity. In a murine asthma model characterized by VCAM-1-dependent airway inflammation, treatment of C57BL6/J mice with i.p. bilirubin decreases the total leukocyte count in the lung parenchyma and lavage fluid, through specific inhibition of eosinophil and lymphocyte infiltration. Blood eosinophil counts were increased in bilirubin-treated animals, while VCAM-1 expression in the capillary endothelium and cytokine levels in both lung lavage and supernatants from cultured lymph node lymphocytes were unchanged, suggesting that bilirubin inhibits leukocyte migration.

CONCLUSION

bilirubin blocks VCAM-1-dependent lymphocyte migration in vitro and ameliorates VCAM-1-mediated airway inflammation in vivo, apparently through the suppression of cellular ROS production. These findings support a potential role for bilirubin as an endogenous immunomodulatory agent.

HIV-1 Tat protein-induced VCAM-1 expression in human pulmonary artery endothelial cells and its signaling

Expression of cell adhesion molecule in endothelial cells upon activation by human immunodeficiency virus (HIV) infection is associated with the development of atherosclerotic vasculopathy. We postulated that induction of vascular cell adhesion molecule-1 (VCAM-1) by HIV-1 Tat protein in endothelial cells might represent an early event that could culminate in inflammatory cell recruitment and vascular injury. We determined the role of HIV-1 Tat protein in VCAM-1 expression in human pulmonary artery endothelial cells (HPAEC). HIV-1 Tat protein treatment significantly increased cell-surface expression of VCAM-1 in HPAEC. Consistently, mRNA expression of VCAM-1 was also increased by HIV-1 Tat protein as measured by RT-PCR. HIV-1 Tat protein-induced VCAM-1 expression was abolished by the NF-kappaB inhibitor pyrrolidine dithiocarbamate (PDTC) and the p38 MAPK inhibitor SB-203580. Furthermore, HIV-1 Tat protein enhanced DNA binding activity of NF-kappaB, facilitated nuclear translocation of NF-kappaB subunit p65, and increased production of reactive oxygen species (ROS). Similarly to VCAM-1 expression, HIV-1 Tat protein-induced NF-kappaB activation and ROS generation were abrogated by PDTC and SB-203580. These data indicate that HIV-1 Tat protein is able to induce VCAM-1 expression in HPAEC, which may represent a pivotal early molecular event in HIV-induced vascular/pulmonary injury. These data also suggest that the molecular mechanism underlying the HIV-1 Tat protein-induced VCAM-1 expression may involve ROS generation, p38 MAPK activation, and NF-kappaB translocation, which are the characteristics of pulmonary endothelial cell activation.

E-Selectin Early Overexpression Induced by Allogeneic Activation in Isolated Mouse Lung

BACKGROUND

The interaction between host lymphocytes and graft endothelial cells plays an important role in graft rejection.

METHODS

Using our model of isolated ventilated lung from female mouse perfused with fresh blood from either isogeneic or allogeneic male mouse for 3 hours without noticeable ischemia, we have investigated the kinetics of the early events after endothelial cell triggering by E-selectin engagement.

RESULTS

Isogeneic perfusion induced nonspecific endothelial cell activation, which was characterized by up-regulation of E-selectin, intercellular adhesion molecule (ICAM)-1, and of the pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, and lymphotoxin-alpha (mRNAs by real-time polymerase chain reaction). Allogeneic perfusion was characterized after 3 hours by an additional loose adhesion of lymphocytes mediated by the E-selectin and related to the allogeneic activation of endothelial cells. These in turn expressed the I-A molecule (immunostaining). ICAM-1 and lymphocyte function-associated antigen (LFA)-3 mRNA levels were significantly increased in lung extracts after 2 hours, then vascular cell adhesion molecule (VCAM)-1 and TNF-alpha mRNAs after 3 hours without evidence of TNF-alpha production (enzyme-linked immunoadsorbent assay). The major participation of the E-selectin in early allogeneic activation by way of the protein kinase (PK)C pathway was confirmed by using a neutralizing anti-CD62E monoclonal antibody or the inhibitory PKC 19-31 fragment.

CONCLUSIONS

Altogether, our results demonstrate that E-selectin expression (1) is not a consequence of TNF-alpha triggering, (2) up-regulates its own expression and expression of I-A, VCAM-1, TNF-alpha, and lymphotoxin-alpha mRNAs, and (3) down-regulates expression of LFA-3 and ICAM-1 mRNAs. In conclusion, in our physiologic model, the E-selectin highly participates in the loose adhesion of allogeneic lymphocytes and in the early activation of endothelial cell and therefore in structural and functional lung alterations.

Transactivation of epidermal growth factor receptor mediates catecholamine-induced growth of vascular smooth muscle

Stimulation of alpha1-adrenoceptors induces proliferation of vascular smooth muscle cells (SMCs) and contributes to arterial remodeling. Although activation of NAD(P)H oxidase and generation of reactive oxygen species (ROS) are required, little is known about this pathway. In this study, we examined the hypothesis that epidermal growth factor receptor (EGFR) transactivation and extracellular regulated kinases (ERK) are involved in alpha1-adrenoceptor-mediated SMC growth. Phenylephrine increased protein synthesis in association with a rapid (< or =5 minutes) and sustained (> or =60 minutes) doubling of phosphorylation of EGFR and ERK1/2, but not p38 or JNK in the media of rat aorta maintained in organ culture. Antagonists of EGFR phosphotyrosine activity (AG-1478) and ERK phosphorylation (PD-98059, U-0126) abolished phenylephrine-induced protein synthesis, whereas antagonists of p38 or JNK phosphorylation had no specific effect. A competitive antagonist (P22) for heparin binding EGF-like growth factor (HB-EGF) blocked phenylephrine-induced protein synthesis, as did downregulation of pro-HB-EGF (CRM197). Phenylephrine-induced protein synthesis was inhibited by neutralizing antibody to HB-EGF and absent in HB-EGF-/- SMCs. Inhibitors of metalloproteinases (BiPS, KB-R7785) also blocked adrenergic growth. The neutralizing antibody against HB-EGF had no effect on the two-fold increase in ROS generation induced by phenylephrine (DCF fluorescence), suggesting that stimulation of NAD(P)H oxidase by alpha1-adrenoceptor occupation precedes HB-EGF release. Cell culture studies confirmed and extended these findings. These data suggest that alpha1-adrenoceptor-mediated SMC growth requires ROS-dependent shedding of HB-EGF, transactivation of EGFR, and activation of the MEK1/2-dependent MAP kinase pathway. This trophic pathway may link sympathetic activity to arterial wall growth in adaptive remodeling and hypertrophic disease.

Oxygen free radicals and redox biology of organelles

The presence and supposed roles of reactive oxygen species (ROS) were reported in literature in a myriad of instances. However, the breadth and depth of their involvement in cellular physiology and pathology, as well as their relationship to the redox environment can only be guessed from specialized reports. Whatever their circumstances of formation or consequences, ROS seem to be conspicuous components of intracellular milieu. We sought to verify this assertion, by collecting the available evidence derived from the most recent publications in the biomedical field. Unlike other reviews with similar objectives, we centered our analysis on the subcellular compartments, namely on organelles, grouped according to their major functions. Thus, plasma membrane is a major source of ROS through NAD(P)H oxidases located on either side. Enzymes of the same class displaying low activity, as well as their components, are also present free in cytoplasm, regulating the actin cytoskeleton and cell motility. Mitochondria can be a major source of ROS, mainly in processes leading to apoptosis. The protein synthetic pathway (endoplasmic reticulum and Golgi apparatus), including the nucleus, as well as protein turnover, are all exquisitely sensitive to ROS-related redox conditions. The same applies to the degradation pathways represented by lysosomes and peroxisomes. Therefore, ROS cannot be perceived anymore as a mere harmful consequence of external factors, or byproducts of altered cellular metabolism. This may explain why the indiscriminate use of anti-oxidants did not produce the expected "beneficial" results in many medical applications attempted so far, underlying the need for a deeper apprehension of the biological roles of ROS, particularly in the context of the higher cellular order of organelles.

Evidence for a mitochondrial impact of trimetazidine during cold ischemia and reperfusion

In organ transplantation, ischemia-reperfusion injury (IRI) has been implicated in delayed graft function (DGF) as well as in short- and long-term complications. Using an autotransplant pig kidney model, changes in renal function and morphology were determined after different periods of cold ischemia in kidneys preserved in the University of Wisconsin solution (UW), high-Na(+) version of UW (HEH) or Celsior (CEL) a newly developed high-Na(+) solution, with or without trimetazidine (TMZ). Kidney function was better preserved in CEL, UW and particularly HEH in combination with TMZ, particularly after 48 and 72 h. Mitochondria integrity was improved in TMZ-preserved groups. This study indicates that TMZ is efficiently protective against IRI even after prolonged preservation and in different preservation solutions.

Recent advances in vascular inflammation: C-reactive protein and other inflammatory biomarkers

PURPOSE OF REVIEW

Inflammatory vascular diseases are initiated and perpetuated by the interaction of immune cells with cells of the affected vessel wall. This is directed by a network of chemical messengers, which, in a state of vascular health, exist as balanced but opposing forces. Our understanding of this highly complex process has advanced significantly in the last several decades. The detection of vascular inflammation and monitoring of this activity have long been attempted in systemic vasculitis, and, more recently, in atherosclerosis. Markers of vascular inflammation used thus far have been of limited value; few provide both adequate sensitivity and specificity for any particular disease. New insights into the pathophysiology of vascular inflammation have identified other potential markers that may improve detection and monitoring of these conditions.

RECENT FINDINGS

Immunomodulatory mediators of the inflammatory cascade have been identified, and their roles are being defined. There are recent data that implicate various cytokines, proteases, adhesion molecules, and acute phase proteins as participants in the generation of vascular inflammation.

CONCLUSION

The pursuit of highly sensitive and specific markers of vascular inflammation has produced a wealth of information that has been instrumental in advancing our comprehension of this complex process. Further studies will establish the role of these new markers in the diagnosis, monitoring, and prognostication of inflammatory vascular disease.

Calcium mobilization and Rac1 activation are required for VCAM-1 (vascular cell adhesion molecule-1) stimulation of NADPH oxidase activity

VCAM-1 (vascular cell adhesion molecule-1) plays an important role in the regulation of inflammation in atherosclerosis, asthma, inflammatory bowel disease and transplantation. VCAM-1 activates endothelial cell NADPH oxidase, and this oxidase activity is required for VCAM-1-dependent lymphocyte migration. We reported previously that a mouse microvascular endothelial cell line promotes lymphocyte migration that is dependent on VCAM-1, but not on other known adhesion molecules. Here we have investigated the signalling mechanisms underlying VCAM-1 function. Lymphocyte binding to VCAM-1 on the endothelial cell surface activated an endothelial cell calcium flux that could be inhibited with anti-alpha4-integrin and mimicked by anti-VCAM-1-coated beads. VCAM-1 stimulation of calcium responses could be blocked by an inhibitor of intracellular calcium mobilization, a calcium channel inhibitor or a calcium chelator, resulting in the inhibition of NADPH oxidase activity. Addition of ionomycin overcame the calcium channel blocker suppression of VCAM-1-stimulated NADPH oxidase activity, but could not reverse the inhibitory effect imposed by intracellular calcium blockage, indicating that both intracellular and extracellular calcium mobilization are required for VCAM-1-mediated activation of NADPH oxidase. Furthermore, VCAM-1 specifically activated the Rho-family GTPase Rac1, and VCAM-1 activation of NADPH oxidase was blocked by a dominant negative Rac1. Thus VCAM-1 stimulates the mobilization of intracellular and extracellular calcium and Rac1 activity that are required for the activation of NADPH oxidase.

Blood-brain barrier disruption in multiple sclerosis

The blood-brain barrier (BBB) is a complex organization of cerebral endothelial cells (CEC), pericytes and their basal lamina, which are surrounded and supported by astrocytes and perivascular macrophages. Collectively these cells separate and form the compartments of the cerebral vascular space and the cerebral interstitium under normal conditions. Without the BBB, the 'interior milieu' of the central nervous system (CNS) would be flooded by humoral neurotransmitters and formed blood elements that upset normal CNS functions and lead to vascular/neural injury. Dysregulation of the BBB and transendothelial migration of activated leukocytes are among the earliest cerebrovascular abnormalities seen in multiple sclerosis (MS) brains and parallel the release of inflammatory cytokines/chemokines. Mechanisms for breakdown of the BBB in MS are incompletely understood, but appear to involve direct effects of these cytokines/ chemokines on endothelial regulation of BBB components, as well as indirect cytokine/chemokine-dependent leukocyte mediated injury. Unique endothelial structural features of the BBB include highly organized endothelial tight junctions, the absence of class II major histocompatibility complex, abundant mitochondria and a highly developed transport system in CEC. Exposure of endothelium to proinflammatory cytokines (IFN-gamma, TNF-alpha and IL-1beta) interrupts the BBB by disorganizing cell-cell junctions, decreases the brain solute barrier, enhances leukocyte endothelial adhesion and migration as well as increases expression of class II MHC and promotes shedding of endothelial 'microparticles' (EMP). In this review we examine interactions between cytokines/chemokines, activated leukocytes, adhesion molecules and activated CEC in the pathogenesis of BBB failure in MS.

Oxidative stress in malaria parasite-infected erythrocytes: host–parasite interactions

Experimenta naturae, like the glucose-6-phosphate dehydrogenase deficiency, indicate that malaria parasites are highly susceptible to alterations in the redox equilibrium. This offers a great potential for the development of urgently required novel chemotherapeutic strategies. However, the relationship between the redox status of malarial parasites and that of their host is complex. In this review article we summarise the presently available knowledge on sources and detoxification pathways of reactive oxygen species in malaria parasite-infected red cells, on clinical aspects of redox metabolism and redox-related mechanisms of drug action as well as future prospects for drug development. As delineated below, alterations in redox status contribute to disease manifestation including sequestration, cerebral pathology, anaemia, respiratory distress, and placental malaria. Studying haemoglobinopathies, like thalassemias and sickle cell disease, and other red cell defects that provide protection against malaria allows insights into this fine balance of redox interactions. The host immune response to malaria involves phagocytosis as well as the production of nitric oxide and oxygen radicals that form part of the host defence system and also contribute to the pathology of the disease. Haemoglobin degradation by the malarial parasite produces the redox active by-products, free haem and H(2)O(2), conferring oxidative insult on the host cell. However, the parasite also supplies antioxidant moieties to the host and possesses an efficient enzymatic antioxidant defence system including glutathione- and thioredoxin-dependent proteins. Mechanistic and structural work on these enzymes might provide a basis for targeting the parasite. Indeed, a number of currently used drugs, especially the endoperoxide antimalarials, appear to act by increasing oxidant stress, and novel drugs such as peroxidic compounds and anthroquinones are being developed.

Evidence for a protective role of trimetazidine during cold ischemia: targeting inflammation and nephron mass

Ischemia-reperfusion injury (IRI) is associated with an increased risk of acute rejection, delayed graft function, or chronic graft dysfunction. Mitochondria plays a central role in this process. Using an autotransplant pig kidney model, changes in renal function and morphology were determined after different periods of cold ischemia in kidneys preserved in the University of Wisconsin solution (UW), high-Na(+) version of UW (HEH) or Celsior (CEL) a newly developed high-Na(+) solution, with or without trimetazidine (TMZ). Kidney function was better preserved in HEH after 24 hr and particularly 48- and 72-hr cold storage than in CEL and UW. TMZ improved the preservation quality when added to the different solutions tested, particularly after 48- and 72-hr cold storage. Interstitial fibrosis and tubular atrophy were reduced in HEH with TMZ. CD4(+) T-cell infiltration was also modulated by the preservation conditions. Peripheral-type benzodiazepine receptor (PBR) positive cells infiltration was also modulated by preservation conditions. TMZ was efficient to reduce IRI when added in the various preservation solutions. These results suggest that protection of the mitochondrial function should be a major target to limit IRI. In addition, this study outlines the role of CD4(+) T cells and PBR expression in inflammatory responses after IRI.

Mice that Lack Endothelial Nitric Oxide Synthase Are Protected against Functional and Structural Modifications Induced by Acute Peritonitis

ABSTRACT. Pharmacologic studies suggest that the release of nitric oxide (NO) by endothelial NO synthase (eNOS) contributes to functional alterations of the peritoneal membrane (PM) induced by acute peritonitis. In this study, peritoneal permeability parameters in a mouse model of peritoneal dialysis were characterized, and the effects of eNOS deletion on the PM structure and permeability at baseline and after catheter-induced bacterial peritonitis were examined. Exposure of C57BL/6 mice to standard dialysate yielded a transport of urea and glucose, a sodium sieving, and a net ultrafiltration that were remarkably similar to the values obtained in rats. In comparison with controls, mice with catheter-induced peritonitis were characterized by structural changes in the PM (mononuclear cells infiltrate, vascular proliferation), upregulation of endothelial and inducible NOS, increased permeability for urea and glucose, decreased ultrafiltration, and increased protein loss in the dialysate. Comparison of eNOS wild-type and knockout mice revealed that the permeability modifications and structural changes induced by acute peritonitis were significantly reversed in eNOS knockout mice, resulting in a net increase in ultrafiltration. In contrast, the deletion of eNOS in mouse peritoneum was not reflected by permeability modifications or structural changes at baseline. These results are the first to take advantage of a knockout mouse model to demonstrate directly the crucial importance of eNOS in the permeability and structural modifications caused by acute peritonitis. The characterization of this mouse model suggests that genetically modified mice represent useful tools to investigate the molecular bases of the peritoneal changes during peritoneal dialysis.

Vascular NAD(P)H oxidases: specific features, expression, and regulation

The importance of reactive oxygen species (ROS) in vascular physiology and pathology is becoming increasingly evident. All cell types in the vascular wall produce ROS derived from superoxide-generating protein complexes similar to the leukocyte NADPH oxidase. Specific features of the vascular enzymes include constitutive and inducible activities, substrate specificity, and intracellular superoxide production. Most phagocyte enzyme subunits are found in vascular cells, including the catalytic gp91phox (aka, nox2), which was the earliest member of the newly discovered nox family. However, smooth muscle frequently expresses nox1 rather than gp91phox, and nox4 is additionally present in all cell types. In cell culture, agonists increase ROS production by activating multiple signals, including protein kinase C and Rac, and by upregulating oxidase subunits. The oxidases are also upregulated in vascular disease and are involved in the development of atherosclerosis and a significant part of angiotensin II-induced hypertension, possibly via nox1 and nox4. Likewise, enhanced vascular oxidase activity is associated with diabetes. Therefore, members of this enzyme family appear to be important in vascular biology and disease and constitute promising targets for future therapeutic interventions.