scholarly journals Porphyromonas gingivalis RgpA-Kgp Proteinase-Adhesin Complexes Penetrate Gingival Tissue and Induce Proinflammatory Cytokines or Apoptosis in a Concentration-Dependent Manner

2008 ◽  
Vol 77 (3) ◽  
pp. 1246-1261 ◽  
Author(s):  
Neil M. O'Brien-Simpson ◽  
Rishi D. Pathirana ◽  
Glenn D. Walker ◽  
Eric C. Reynolds
Keyword(s):  
Connective Tissue ◽  
Porphyromonas Gingivalis ◽  
Intercellular Adhesion Molecule ◽  
Gingival Tissue ◽  
Dependent Manner ◽  
Intercellular Adhesion Molecule 1 ◽  
Concentration Dependent Manner ◽  
Proinflammatory Mediators ◽  
Low Concentrations ◽  
High Concentrations

ABSTRACT The RgpA-Kgp proteinase-adhesin complexes of Porphyromonas gingivalis were observed, using immunostaining, in human gingival tissue associated with periodontitis but not in healthy tissue. The staining pattern suggested a concentration gradient from the subgingival plaque into the subjacent gingival connective tissue. Intense immunostaining was observed in areas displaying gross disturbance of tissue architecture. P. gingivalis cells and the RgpA-Kgp complexes at low concentrations were shown to stimulate secretory intercellular adhesion molecule 1, interleukin-8 (IL-8), IL-6, and macrophage chemoattractant protein secretion from cultured human epithelial (KB) and fibroblast (MRC-5) cells. However, at high concentrations a reduction in the level of these mediators was observed. In contrast, macrophage inflammatory protein 1α and IL-1α were stimulated only at high P. gingivalis cell concentrations. P. gingivalis cells and the RgpA-Kgp complexes were shown to induce apoptosis in KB and MRC-5 cells in a time- and dose-dependent manner. These data suggest that the RgpA-Kgp complexes penetrate the gingival connective tissue; at low concentrations distal from the plaque the complexes stimulate the secretion of proinflammatory mediators, while at high concentrations proximal to the plaque they induce apoptosis and attenuate the secretion of proinflammatory mediators.

Neutrophil Elastase Potentiates Cathepsin G-lnduced Platelet Activation

1992 ◽  
Vol 68 (05) ◽  
pp. 570-576 ◽  
Author(s):  
Mary A Selak
Keyword(s):  
Neutrophil Elastase ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Creatine Phosphate ◽  
Dense Granule ◽  
Cathepsin G ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations

SummaryWe have previously demonstrated that human neutrophil cathepsin G is a strong platelet agonist that binds to a specific receptor. This work describes the effect of neutrophil elastase on cathepsin G-induced platelet responses. While platelets were not activated by high concentrations of neutrophil elastase by itself, elastase enhanced aggregation, secretion and calcium mobilization induced by low concentrations of cathepsin G. Platelet aggregation and secretion were potentiated in a concentration-dependent manner by neutrophil elastase with maximal responses observable at 200 nM. Enhancement was observed when elastase was preincubated with platelets for time intervals of 10–60 s prior to addition of a low concentration of cathepsin G and required catalytically-active elastase since phenylmethanesulphonyl fluoride-inhibited enzyme failed to potentiate cell activation. Neutrophil elastase potentiation of platelet responses induced by low concentrations of cathepsin G was markedly inhibited by creatine phosphate/creatine phosphokinase and/or indomethacin, indicating that the synergism between elastase and cathepsin G required the participation of ADP and thromboxane A2. On the other hand, platelet responses were not attenuated by the PAF antagonist BN 52021, signifying that PAF-acether did not play a role in elastase potentiation. At higher concentrations porcine pancreatic elastase exhibits similar effects to neutrophil elastase, demonstrating that the effect of elastase was not unique to the neutrophil protease. While neutrophil elastase failed to alter the ability of cathepsin G to hydrolyze a synthetic chromogenic substrate, preincubation of platelets with elastase increased the apparent affinity of cathepsin G binding to platelets. In contrast to their effect on cathepsin G-induced platelet responses, neither neutrophil nor pancreatic elasatse potentiated aggregation or dense granule release initiated by ADP, PAF-acether, arachidonic acid or U46619, a thromboxane A2 mimetic. Moreover, unlike its effect on cathepsin G, neutrophil elastase inhibited thrombin-induced responses. The current observations demonstrate that elastase can potentiate platelet responses mediated by low concentrations of cathepsin G, suggesting that both enzymes may function synergistically to activate platelets under conditions where neutrophil degranulation occurs.

scholarly journals Relaxation of Androgens on Rat Thoracic Aorta: Testosterone Concentration Dependent Agonist/Antagonist l-Type Ca2+ Channel Activity, and 5β-Dihydrotestosterone Restricted to l-Type Ca2+ Channel Blockade

Endocrinology ◽  
2008 ◽  
Vol 149 (5) ◽  
pp. 2517-2526 ◽  
Author(s):  
Luis M. Montaño ◽  
Eduardo Calixto ◽  
Alejandra Figueroa ◽  
Edgar Flores-Soto ◽  
Verónica Carbajal ◽  
...  
Keyword(s):  
Thoracic Aorta ◽  
Dependent Manner ◽  
Camp Production ◽  
Concentration Dependent Manner ◽  
Selective Blockade ◽  
Low Concentrations ◽  
Agonist Property ◽  
Rat Thoracic Aorta ◽  
High Concentrations ◽  
Androgen Effects

Androgen vasorelaxing action is a subject of recent interest. We investigated the involvement of l-type voltage-operated Ca2+ channels (L-VOCCs), K+ channels, intracellular Ca2+ concentration ([Ca2+]i), and cAMP in the vasorelaxing effect of testosterone and 5β-dihydrotestosterone (5β-DHT) on rat thoracic aorta. Isolated aortic rings were used to study the vasorelaxing potency of testosterone and 5β-DHT on KCl- and noradrenaline-induced contractions. Patch-clamp was used to analyze androgen effects on Ca2+ inward and K+ outward currents. The fluorescence technique was used to evaluate [Ca2+]i in single myocytes; moreover, simultaneous measurements of [Ca2+]i and vascular contraction were evaluated. 5β-DHT was more potent than testosterone to relax KCl-induced contraction, but they were equipotent to relax noradrenaline contraction. l-type Ca2+ currents were blocked by nifedipine, both androgens, and an estrogen in a concentration-dependent manner, and the order of potency was: testosterone > nifedipine > 5β-DHT > 17β-estradiol. We observed that testosterone has different mechanism of action by the concentration range used: at nm concentrations it was a powerful L-VOCCs antagonist, whereas at μm concentrations it was observed that: 1) its Ca2+ antagonist property is reverted by increasing the l-type inward Ca2+ currents (Ca2+ agonist property); and 2) the [Ca2+]i and cAMP production was increased. The total K+ currents were unaffected by testosterone or 5β-DHT. The data show that 5β-DHT-induced vasorelaxation is due to its selective blockade on L-VOCCs (from nm to μm concentrations), but testosterone-induced vasorelaxation involves concentration-dependent additional mechanisms: acting as an L-VOCCs antagonist at low concentrations, and increasing [Ca2+]i and cAMP production at high concentrations.

scholarly journals Fibrin serves as a divalent ligand that regulates neutrophil-mediated melanoma cells adhesion to endothelium under shear conditions

2012 ◽  
Vol 302 (8) ◽  
pp. C1189-C1201 ◽  
Author(s):  
Tugba Ozdemir ◽  
Pu Zhang ◽  
Changliang Fu ◽  
Cheng Dong
Keyword(s):  
Immune Cell ◽  
Melanoma Cells ◽  
Flow Chamber ◽  
Polymorphonuclear Neutrophils ◽  
Host Cells ◽  
Intercellular Adhesion Molecule ◽  
Dependent Manner ◽  
Intercellular Adhesion Molecule 1 ◽  
Concentration Dependent Manner ◽  
Human Pmns

Elevated soluble fibrin (sFn) levels are characteristic of melanoma hematogeneous dissemination, where tumor cells interact intimately with host cells. Melanoma adhesion to the blood vessel wall is promoted by immune cell arrests and tumor-derived thrombin, a serine protease that converts soluble fibrinogen (sFg) into sFn. However, the molecular requirement for sFn-mediated melanoma-polymorphonuclear neutrophils (PMNs) and melanoma-endothelial interactions under physiological flow conditions remain elusive. To understand this process, we studied the relative binding capacities of sFg and sFn receptors e.g., αvβ3integrin and intercellular adhesion molecule-1 (ICAM-1) expressed on melanoma cells, ICAM-1 on endothelial cells (EC), and CD11b/CD18 (Mac-1) on PMNs. Using a parallel-plate flow chamber, highly metastatic melanoma cells (1205Lu and A375M) and human PMNs were perfused over an EC monolayer expressing ICAM-1 in the presence of sFg or sFn. It was found that both the frequency and lifetime of direct melanoma adhesion or PMN-facilitated melanoma adhesion to the EC in a shear flow were increased by the presence of sFn in a concentration-dependent manner. In addition, sFn fragment D and plasmin-treated sFn failed to increase melanoma adhesion, implying that sFn-bridged cell adhesion requires dimer-mediated receptor-receptor cross-linking. Finally, analysis of the respective kinetics of sFn binding to Mac-1, ICAM-1, and αvβ3by single bond cell tethering assays suggested that ICAM-1 and αvβ3are responsible for initial capture and firm adhesion of melanoma cells. These results provide evidence that sFn enhances melanoma adhesion directly to ICAM-1 on the EC, while prolonged shear-resistant melanoma adhesion requires interactions with PMNs.

Expression and self-regulatory function of cardiac interleukin-6 during endotoxemia

2000 ◽  
Vol 279 (5) ◽  
pp. H2241-H2248 ◽  
Author(s):  
Hiroshi Saito ◽  
Cam Patterson ◽  
Zhaoyong Hu ◽  
Marschall S. Runge ◽  
Ulka Tipnis ◽  
...  
Keyword(s):  
Feedback Mechanism ◽  
Intercellular Adhesion Molecule ◽  
Regulatory Function ◽  
Heart Cells ◽  
Intercellular Adhesion Molecule 1 ◽  
Negative Feedback Mechanism ◽  
Proinflammatory Mediators ◽  
Tnf Α

Interleukin (IL)-6 reportedly has negative inotropic and hypertrophic effects on the heart. Here, we describe endotoxin-induced IL-6 in the heart that has not previously been well characterized. An intraperitoneal injection of a bacterial lipopolysaccharide into C57BL/6 mice induced IL-6 mRNA in the heart more strongly than in any other tissue examined. Induction of mRNA for two proinflammatory cytokines, IL-1β and tumor necrosis factor (TNF)-α, occurred rapidly before the induction of IL-6 mRNA and protein. Although stimulation of isolated rat neonatal myocardial cells with IL-1β or TNF-α induced IL-6 mRNA in vitro, nonmyocardial heart cells produced higher levels of IL-6 mRNA upon stimulation with IL-1β. In situ hybridization and immunohistochemical analyses localized the IL-6 expression primarily in nonmyocardial cells in vivo. Endotoxin-induced expression of cardiac IL-1β, TNF-α, and intercellular adhesion molecule 1 was augmented in IL-6-deficient mice compared with control mice. Thus cardiac IL-6, expressed mainly by nonmyocardial cells via IL-1β action during endotoxemia, is likely to suppress expression of proinflammatory mediators and to regulate itself via a negative feedback mechanism.

Effects of polymethoxylated flavone metabolites on apoB100 secretion and MTP activity in Huh7.5 cells

2021 ◽  
Vol 18 ◽  
Author(s):  
Danielle R. Gonçalves ◽  
Thais B. Cesar ◽  
John A. Manthey ◽  
Paulo I. Costa
Keyword(s):  
Lipid Synthesis ◽  
Dependent Manner ◽  
Transfer Protein ◽  
Low Concentrations ◽  
Wide Range ◽  
Cell Assays ◽  
Polymethoxylated Flavones ◽  
High Concentrations

Background: Citrus polymethoxylated flavones (PMFs) reduce the synthesis of liver lipoproteins in animal and in vitro cell assays, but few studies have evaluated the direct effects of their metabolites on this highly regulated process. Objective: To investigate the effects of representative metabolites of PMF on the secretion of liver lipoproteins using the mammalian cell Huh7.5. Method: In this study, the influences of three PMFs and five previously isolated PMF metabolites on hepatic apoB-100 secretion and microsomal transfer protein (MTP) activity were evaluated. Tangeretin (TAN), nobiletin (NOB) and 3,5,6,7,8,3′,4′-heptamethoxyflavone (HMF), and their glucuronides (TAN-Gluc, NOB-Gluc and HMF-Gluc) and oxidatively demethylated metabolites (TAN-OH, NOB-OH, HMF-OH) were incubated with Huh7.5 cells to measure their inhibitory effects on lipid synthesis. Results: The results showed that TAN, HMF and TAN-OH reduced the secretion of apoB-100 in a dose-dependent manner, while NOB and the other tested metabolites showed no inhibition. MTP activity in the Huh7.5 cells was significantly reduced in the presence of low concentrations of TAN, and in high concentrations of NOB-OH. This study also showed that PMFs and PMF metabolites produced a wide range of effects on apoB-100 secretion and MTP activity. Conclusion: The results suggest that while PMFs and their metabolites control dyslipidemia in vivo, the inhibition of MTP activity cannot be the only pathway influenced by these compounds.

scholarly journals Effect of Lonicera caerulea var. emphyllocalyx Fruit on Biofilm Formed by Porphyromonas gingivalis

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Masaaki Minami ◽  
Hiroshi Takase ◽  
Mineo Nakamura ◽  
Toshiaki Makino
Keyword(s):  
Oral Cavity ◽  
Porphyromonas Gingivalis ◽  
Aspiration Pneumonia ◽  
Biofilm Formation ◽  
Bacterial Colonization ◽  
Bacterial Biofilm ◽  
Dependent Manner ◽  
Electron Microscopic ◽  
Concentration Dependent Manner ◽  
Lonicera Caerulea

Porphyromonas gingivalis is an important pathogenic anaerobic bacterium that causes aspiration pneumonia. This bacterium frequently forms biofilms in the oral cavity and in respiratory tract-associated medical devices. Bacterial colonization that occurs in association with this biofilm formation is the main reason for incurable aspiration pneumonia. The Lonicera caerulea var. emphyllocalyx (LCE) fruit has been used in folk medicine in Hokkaido, the northern part of Japan. The aim of this study was to elucidate one of the antimicrobial mechanisms of LCE methanol extract (LCEE)—the inhibitory effect of LCEE on biofilm formation by P. gingivalis. Our results show that LCEE significantly reduced biofilm formation by three different P. gingivalis isolates in a concentration- and time-dependent manner that were quantified by the adsorption of safranin red. When LCEE was added to biofilms already formed by P. gingivalis, LCEE did not degrade the biofilm. However, treatment with LCEE significantly promoted the removal of existing biofilm by vibration compared to that of control. We also confirmed biofilm formation in LCEE-treated P. gingivalis in tracheal tubes using scanning electron microscopic (SEM) analysis. Cyanidin 3-O-glucoside (C3G), one of the components of LCE, also inhibited the formation of biofilm by P. gingivalis in a concentration-dependent manner. Our results reveal that LCEE may be an effective antibacterial substance for P. gingivalis-induced aspiration pneumonia because of its role in the suppression of bacterial biofilm formation in the oral cavity.

Vascular Protective Effects of Xanthotoxin and Its Action Mechanism in Rat Aorta and Human Vascular Endothelial Cells

2020 ◽  
Vol 57 (6) ◽  
pp. 313-324
Author(s):  
Li-Hua Cao ◽  
Ho Sub Lee ◽  
Zhe-Shan Quan ◽  
Yun Jung Lee ◽  
Yu Jin
Keyword(s):  
Endothelial Cells ◽  
Cell Adhesion ◽  
Adhesion Molecule ◽  
Molecular Mechanisms ◽  
Umbilical Vein ◽  
Neuroprotective Effect ◽  
Intercellular Adhesion Molecule ◽  
Dependent Manner ◽  
Protective Effects ◽  
Concentration Dependent Manner

<b><i>Objective:</i></b> Xanthotoxin (XAT) is a linear furanocoumarin mainly extracted from the plants <i>Ammi majus</i> L. XAT has been reported the apoptosis of tumor cells, anti-convulsant, neuroprotective effect, antioxidative activity, and vasorelaxant effects. This study aimed to investigate the vascular protective effects and underlying molecular mechanisms of XAT. <b><i>Methods:</i></b> XAT’s activity was studied in rat thoracic aortas, isolated with aortic rings, and human umbilical vein endothelial cells (HUVECs). <b><i>Results:</i></b> XAT induced endothelium-dependent vasodilation in a concentration-dependent manner in the isolated rat thoracic aortas. Removal of endothelium or pretreatment of aortic rings with L-NAME, 1<i>H</i>-[1,2,4]-oxadiazolo-[4,3-<i>a</i>]-quinoxalin-1-one, and wortmannin significantly inhibited XAT-induced relaxation. In addition, treatment with thapsigargin, 2-aminoethyl diphenylborinate, Gd<sup>3+</sup>, and 4-aminopyridine markedly attenuated the XAT-induced vasorelaxation. XAT increased nitric oxide production and Akt- endothelial NOS (eNOS) phosphorylation in HUVECs. Moreover, XAT attenuated the expression of TNF-α-induced cell adhesion molecules such as intercellular adhesion molecule, vascular cell adhesion molecule-1, and E-selectin. However, this effect was attenuated by the eNOS inhibitors L-NAME and asymmetric dimethylarginine. <b><i>Conclusions:</i></b> This study suggests that XAT induces vasorelaxation through the Akt-eNOS-cGMP pathway by activating the K<sub>V</sub> channel and inhibiting the L-type Ca<sup>2+</sup> channel. Furthermore, XAT exerts an inhibitory effect on vascular inflammation, which is correlated with the observed vascular protective effects.

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