Troglitazone, a PPAR-γ activator prevents endothelial cell adhesion molecule expression and lymphocyte adhesion mediated by TNF-α

Background  

Cytokine mediated induction of the mucosal addressin cell adhesion molecule-1(MAdCAM-1) expression is associated with the onset and progression of inflammatory bowel disease (IBD).     

Mechanisms of MAdCAM-1 gene expression in human intestinal microvascular endothelial cells

Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is a homing receptor preferentially expressed on gut-associated endothelial cells that plays a central role in leukocyte traffic into the mucosal immune compartment. Although the molecular mechanisms underlying endothelial ICAM-1 or E-selectin expression have been intensively investigated, the mechanisms that regulate human MAdCAM-1 expression have not been defined. We report MAdCAM-1 gene and protein expression in primary cultures of human intestinal microvascular endothelial cells (HIMEC) that was not demonstrated in human umbilical vein endothelial cells. Similar to ICAM-1 and E-selectin expression, MAdCAM-1 gene expression in HIMEC was inducible with TNF-, IL-1, or LPS activation. However, in striking contrast to ICAM-1 and E-selectin expression, MAdCAM-1 mRNA and protein expression in HIMEC was heavily dependent on culture duration and/or cellular density, suggesting a prominent role for cell-cell interaction among these endothelial cells in the expression of the mucosal addressin. MAdCAM-1 expression was inhibited by both SN-50 (NF-B inhibitor) and LY-294002 [phosphatidylinositol 3-kinase (PI3-K) inhibitor], whereas ICAM-1 and E-selectin expression was inhibited by SN-50 but not by LY-294002. The Akt phosphorylation by TNF- or LPS was greater at higher cell density, demonstrating a pattern similar to that of MAdCAM-1 expression. NF-B activation was not affected by cellular density in HIMEC. MAdCAM-1 expression in human gut endothelial cells is regulated by distinct signaling mechanisms involving both NF-B and PI3-K/Akt. These data also suggest that PI3-K/Akt is involved in the gut-specific differentiation of HIMEC, which results in expression of the mucosal addressin MAdCAM-1. cell adhesion molecules; nuclear factor-B; phosphatidylinositol 3-kinase     

TNF-alpha -induced endothelial cell adhesion molecule expression is cytochrome P-450 monooxygenase dependent

It is strongly suspected thatcytokine-induced gene expression in inflammation is oxidant mediated;however, the intracellular sources of signaling oxidants remaincontroversial. In inflammatory bowel disease (IBD) proinflammatorycytokines, such as TNF-, trigger gene expression of endothelialadhesion molecules including mucosal addressin cell adhesion molecule-1(MAdCAM-1). MAdCAM-1 plays an essential role in gut inflammation bygoverning the infiltration of leukocytes into the intestine. Severalgroups suggest that endothelial-derived reduced NADP (NADPH) oxidaseproduces signaling oxidants that control the expression of adhesionmolecules (E-selectin, ICAM-1, VCAM-1). In addition to NADPH oxidase,cytochrome P-450 (CYP450) monooxygenases have also beenshown to trigger cytokine responses. We found that in high endothelialvenular cells (SVEC4-10), multiple inhibitors of CYP450 monooxygenases(SKF-525a, ketoconazole, troleandomycin, itraconazole) attenuatedTNF- induction of MAdCAM-1, whereas NADPH oxidase inhibition (PR-39)did not. Conversely, E-selectin, ICAM-1, and VCAM-1 inductionrequires both NADPH oxidase and CYP450-derived oxidants. We show herethat MAdCAM-1 induction may depend exclusively on CYP450-derivedoxidants, suggesting that CYP450 blockers might represent a possiblenovel therapeutic treatment for human IBD.

     

Regulation and distribution of MAdCAM-1 in endothelial cells in vitro

Mucosal addressin cell adhesion molecule-1(MAdCAM-1) is a 60-kDa endothelial cell adhesion glycoprotein thatregulates lymphocyte trafficking to Peyer's patches and lymph nodes.Although it is widely agreed that MAdCAM-1 induction is involved inchronic gut inflammation, few studies have investigated regulation ofMAdCAM-1 expression. We used two endothelial lines [bEND.3 (brain) and SVEC (high endothelium)] to study the signal paths that regulate MAdCAM-1 expression in response to tumor necrosis factor (TNF)- using RT-PCR, blotting, adhesion, and immunofluorescence. TNF- induced both MAdCAM-1 mRNA and protein in a dose- and time-dependent manner. This induction was tyrosine kinase (TK), p42/44, p38mitogen-activated protein kinase (MAPK), and nuclear factor(NF)-B/poly-ADP ribose polymerase (PARP) dependent. Because MAdCAM-1is regulated via MAPKs, we examined mitogen/extracellularsignal-regulated kinase (MEK)-1/2 activation in SVEC. We found thatMEK-1/2 is activated by TNF- within minutes and is dependent on TKand p42/44 MAPKs. Similarly, TNF- activated NF-B through TK,p42/44, p38 MAPKs, and PARP pathways in SVEC cells. MAdCAM-1 was alsoshown to be frequently distributed to endothelial junctions both invitro and in vivo. Cytokines like TNF- stimulate MAdCAM-1 inhigh endothelium via TK, p38, p42/22 MAPKs, and NF-B/PARP.MAdCAM-1 expression requires NF-B translocation through both directp42/44 and indirect p38 MAPK pathways in high endothelial cells.

     

Methicillin resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> adhesion to human umbilical vein endothelial cells demonstrates wall shear stress dependent behaviour

Background  

Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly prevalent pathogen capable of causing severe vascular infections. The goal of this work was to investigate the role of shear stress in early adhesion events.     

CYP450 dietary inhibitors attenuate TNF-alpha-stimulated endothelial molecule expression and leukocyte adhesion

Enhanced expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) and other endothelial cell adhesion molecules (ECAMs) are associated with the onset and progression of inflammatory bowel disease (IBD). We show in this study that two cytochrome P-450 (CYP450) inhibitors from Citrus paradis (grapefruit), bergamottin, and 6',7'-dihydroxybergamottin (DHB) block tumor necrosis factor (TNF)--stimulated expression of MAdCAM-1 in cultured endothelial cells and also reduce ₄₇-dependent lymphocyte adhesion. Bergamottin (20–50 µM) or DHB (10–30 µM) pretreatment dose-dependently reduced TNF--mediated expression of MAdCAM-1 and lymphocyte adhesion. Bergamottin and DHB also prevented expression of two other ECAMs, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (but not E-selectin). SKF-525a, a specific CYP450 inhibitor, also blocked the expression of MAdCAM-1 mediated by TNF-. Similar to SKF-525a (20 µM), bergamottin (20 µM) and DHB (20 µM) directly inhibited the activity of CYP450 3A4. These results suggest that natural CYP450 inhibitors may be effective in reducing ECAM expression and leukocyte adhesion and therefore be useful in the clinical treatment of inflammatory states like IBD. cytochrome P-450; inflammatory bowel disease; lymphocytes; mucosal adhesion cell adhesion molecule-1     

Role of type 1 and type 3 fimbriae in <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> biofilm formation

Background  

Klebsiella pneumoniae is an important gram-negative opportunistic pathogen causing primarily urinary tract infections, respiratory infections, and bacteraemia. The ability of bacteria to form biofilms on medical devices, e.g. catheters, has a major role in development of many nosocomial infections. Most clinical K. pneumoniae isolates express two types of fimbrial adhesins, type 1 fimbriae and type 3 fimbriae. In this study, we characterized the role of type 1 and type 3 fimbriae in K. pneumoniae biofilm formation.     

Regulation of soluble vascular endothelial growth factor receptor (sFlt-1/sVEGFR-1) expression and release in endothelial cells by human follicular fluid and granulosa cells

Background  

During the female reproductive cycle, follicular development and corpus luteum formation crucially depend on the fast generation of new blood vessels. The importance of granulosa cells and follicular fluid in controlling this angiogenesis is still not completely understood. Vascular endothelial growth factor (VEGF) produced by granulosa cells and secreted into the follicular fluid plays an essential role in this process. On the other hand, soluble VEGF receptor-1 (sFlt-1) produced by endothelial cells acts as a negative modulator for the bioavailability of VEGF. However, the regulation of sFlt-1 production remains to be determined.     

Identification of a human immunodominant B-cell epitope within the immunoglobulin A1 protease of <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis>

Background  

The IgA1 protease of Streptococcus pneumoniae is a proteolytic enzyme that specifically cleaves the hinge regions of human IgA1, which dominates most mucosal surfaces and is the major IgA isotype in serum. This protease is expressed in all of the known pneumococcal strains and plays a major role in pathogen's resistance to the host immune response. The present work was focused at identifying the immunodominant regions of pneumococcal IgA1 protease recognized by the human antibody response.     

Thioredoxin reductase is a key factor in the oxidative stress response of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> WCFS1

Background  

Thioredoxin (TRX) is a powerful disulfide oxido-reductase that catalyzes a wide spectrum of redox reactions in the cell. The aim of this study is to elucidate the role of the TRX system in the oxidative stress response in Lactobacillus plantarum WCFS1.     

Two common nonsynonymous paraoxonase 1 (<Emphasis Type="Italic">PON1</Emphasis>) gene polymorphisms and brain astrocytoma and meningioma

Background  

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.     

Cloning and expression of <Emphasis Type="Italic">R-Spondin1</Emphasis>in different vertebrates suggests a conserved role in ovarian development

Background  

R-Spondin1 (Rspo1) is a novel regulator of the Wnt/β-catenin signalling pathway. Loss-of-function mutations in human RSPO1 cause testicular differentiation in 46, XX females, pointing to a role in ovarian development. Here we report the cloning and comparative expression analysis of R-SPONDIN1 orthologues in the mouse, chicken and red-eared slider turtle, three species with different sex-determining mechanisms. Evidence is presented that this gene is an ancient component of the vertebrate ovary-determining pathway.     

Expression and shedding of endothelial protein C receptor in prostate cancer cells

Background  

Increasing evidences show that beyond its role in coagulation, endothelial protein C receptor (EPCR) interferes with carcinogenesis. Pro-carcinogenic effects of EPCR were linked with a raised generation of activated protein C (aPC) and anti-apoptotic signalling. This study was carried out to analyze the expression, cell surface exposition, and shedding of EPCR in normal and malignant prostate cell lines.     

Identification of critical residues in Gap3 of <Emphasis Type="Italic">Streptococcus parasanguinis</Emphasis> involved in Fap1 glycosylation,fimbrial formation and <Emphasis Type="Italic">in vitro</Emphasis>adhesion

Background  

Streptococcus parasanguinis is a primary colonizer of human tooth surfaces and plays an important role in dental plaque formation. Bacterial adhesion and biofilm formation are mediated by long peritrichous fimbriae that are composed of a 200 kDa serine rich glycoprotein named Fap1 (fimbriae-associated protein). Glycosylation and biogenesis of Fap1 are modulated by a gene cluster downstream of the fap1 locus. A gene encoding a glycosylation-associated protein, Gap3, was found to be important for Fap1 glycosylation, long fimbrial formation and Fap1-mediated biofilm formation.     

Soluble L1CAM promotes breast cancer cell adhesion and migration <Emphasis Type="Italic">in vitro</Emphasis>, but not invasion

Background  

Neural recognition molecule L1CAM, which is a key protein involved in early nervous system development, is known to be abnormally expressed and shed in several types of cancers where it participates in metastasis and progression. The distinction of L1CAM presence in cancerous vs. normal tissues has suggested it to be a new target for cancer treatment. Our current study focused on the potential role of soluble L1CAM in breast cancer cell adhesion to extracellular matrix proteins, migration, and invasion.     

<Emphasis Type="Italic">Brucella suis</Emphasis> urease encoded by <Emphasis Type="Italic">ure</Emphasis> 1 but not <Emphasis Type="Italic">ure</Emphasis> 2 is necessary for intestinal infection of BALB/c mice

Background  

In prokaryotes, the ureases are multi-subunit, nickel-containing enzymes that catalyze the hydrolysis of urea to carbon dioxide and ammonia. The Brucella genomes contain two urease operons designated as ure1 and ure2. We investigated the role of the two Brucella suis urease operons on the infection, intracellular persistence, growth, and resistance to low-pH killing.