Abstract 471: Systemic Chymase Inhibition Directs Atherosclerotic Plaques Towards a Stable Phenotype in ApoE Deficient Mice

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Ilze Bot ◽  
Sandra H van Heiningen ◽  
Jurgen Fingerle ◽  
Hans Hilpert ◽  
Theo van Berkel ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
Control Diet ◽  
Mast Cell Activation ◽  
Human Coronary Artery ◽  
Plaque Stability ◽  
Peritoneal Mast Cells ◽  
Chymase Inhibitor

Activated mast cells have been identified at the site of rupture in human coronary artery plaques and appear to contribute considerably to plaque progression and stability. We and others have previously demonstrated that the mast cell constituents chymase and tryptase promote apoptosis of plaque cells. In this study, we aimed to investigate whether inhibition of mast cell chymase by a specific chymase inhibitor indeed has a beneficial effect on plaque stability. Preincubation of 48/80 activated MC/9 murine mast cells or freshly isolated peritoneal mast cells with chymase inhibitor RO5010226 – 000 – 004 (RO501; 1 μM) inhibited mast cell activation, as illustrated by a decreased β-hexosaminidase activity in the releasate (−41% compared to control MC/9 cells, *P=0.04, and −80% compared to control peritoneal mast cells, *P=0.02) as well as chymase release and activity (−71% and −65%, *P=0.04, respectively). Next, we addressed whether chymase inhibition also was effective in vivo. Atherosclerotic carotid artery lesions were induced in ApoE −/− mice by perivascular collar placement; during lesion development mast cells were activated by a DNP challenge once weekly for 4 weeks. Concomitantly, a subset of mice received the chymase inhibitor (50 mg/kg/day, n=14) as diet supplement, leading to continuous serum concentrations of ~2 μM or control diet (n=12). After 6 weeks, the advanced plaques were analyzed for size and stability. While plaque size did not differ, collagen content of the lesions was 2-fold enhanced in mice treated with the chymase inhibitor compared to controls (RO501: 1.4 ± 0.5% versus controls: 0.7 ± 0.2%). This was accompanied by a significant decrease in necrotic core size of the plaques (RO501: 52 ± 3% versus controls: 41 ± 4%, *P=0.04) as well as by an increased plaque cellularity (RO501: 2.6 ± 0.1*10 3 versus controls: 2.3 ± 0.1*10 3 cells/mm 2 tissue). In agreement with these data we did observe increased peritoneal leukocyte numbers in the RO501 treated mice (RO501: 4.2 ± 1.1*10 6 cells versus 2.2 ± 0.3*10 6 cells in controls, *P=0.04). In conclusion, our data suggest that chymase inhibition indeed results in enhanced plaque stability, identifying chymase inhibition as a new therapeutic approach in the prevention of acute coronary syndromes.

Abstract 1947: Chymase Inhibition Reduces the Incidence of Intraplaque Hemorrhage and Induces a Stable Atherosclerotic Plaque Phenotype in ApoE Deficient Mice

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Ilze Bot ◽  
Marijke M Westra ◽  
Sandra H van Heiningen ◽  
Hans Hilpert ◽  
Inge M Lankhuizen ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Atherosclerotic Plaque ◽  
Cell Activation ◽  
Mast Cell Activation ◽  
Intraplaque Hemorrhage ◽  
Plaque Stability ◽  
Plaque Destabilization

Mast cells are abundantly present in perivascular tissue during atherosclerotic plaque progression and were previously demonstrated to contribute significantly to plaque destabilization. In this study, we aimed to investigate to what extent inhibition of chymase, one of the mast cell proteases, could enhance plaque stability. We demonstrated earlier that the specific chymase inhibitor RO501 (1 μM) was able to quench mast cell activation in vitro , as illustrated by a decreased β-hexosaminidase (−41% and −80%, respectively; P<0.05) as well as chymase activity in the releasate of activated MC/9 and peritoneal mast cells (−71% and −65%, respectively; P<0.05). Next, we assessed whether chymase inhibition was also effective in vivo. Atherosclerotic carotid artery lesions were induced in ApoE −/− mice by perivascular collar placement and mast cells were activated by DNP challenge systemically during lesion development. RO501 (50 mg/kg/day) was administered as diet supplement, leading to serum concentrations of ~2 μM. While plaque size after 6 weeks of treatment did not differ, collagen content of the lesions was 2-fold enhanced in mice treated with RO501 compared to controls (1.4 ± 0.5% and 0.7 ± 0.2%, respectively). This was accompanied by a significant decrease in necrotic core size of the plaques (controls: 52 ± 3% versus RO501: 41 ± 4%, P<0.05). To determine the effects of chymase inhibition after acute mast cell activation in advanced plaques, perivascular mast cells were focally activated in the adventitia of advanced lesions in ApoE −/− mice, which were treated with RO501 as described above. At three days after focal mast cell challenge, the incidence of intraplaque hemorrhage (IPH) was inhibited from 23% in control mice to 4.5% in RO501 treated mice, while also the plaque erythrocyte area was reduced by >90% from 1.2 ± 0.6*10 3 to 0.1 ± 0.08*10 3 μm 2 (P<0.05). Also, we observed a reduction in apoptotic cells (RO501: 0.68 ± 0.20% vs. 1.01 ± 0.36% for IPH negative controls and 1.23 ± 0.42% for IPH + plaques). In conclusion, our data suggest that chymase inhibition at least partly prevents the detrimental effects of perivascular mast cells on plaque stability, identifying chymase inhibition as a new therapeutic approach in the prevention of acute coronary syndromes.

scholarly journals Mast cell activation is not required for induction of airway hyperresponsiveness by ozone in mice

1999 ◽  
Vol 86 (1) ◽  
pp. 202-210 ◽  
Author(s):  
N. Noviski ◽  
J. P. Brewer ◽  
W. A. Skornik ◽  
S. J. Galli ◽  
J. M. Drazen ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Airway Hyperresponsiveness ◽  
Essential Role ◽  
Cell Activation ◽  
Mast Cell Degranulation ◽  
Mast Cell Activation ◽  
Polymorphonuclear Cell ◽  
Pulmonary Parenchyma

Exposure to ambient ozone (O3) is associated with increased exacerbations of asthma. We sought to determine whether mast cell degranulation is induced by in vivo exposure to O3in mice and whether mast cells play an essential role in the development of pulmonary pathophysiological alterations induced by O3. For this we exposed mast cell-deficient WBB6F1- kitW/ kitW-v( kitW/ kitW-v) mice and the congenic normal WBB6F1(+/+) mice to air or to 1 or 3 parts/million O3for 4 h and studied them at different intervals from 4 to 72 h later. We found evidence of O3-induced cutaneous, as well as bronchial, mast cell degranulation. Polymorphonuclear cell influx into the pulmonary parenchyma was observed after exposure to 1 part/milllion O3only in mice that possessed mast cells. Airway hyperresponsiveness to intravenous methacholine measured in vivo under pentobarbital anesthesia was observed in both kitW/ kitW-vand +/+ mice after exposure to O3. Thus, although mast cells are activated in vivo by O3and participate in O3-induced polymorphonuclear cell infiltration into the pulmonary parenchyma, they do not participate detectably in the development of O3-induced airway hyperresponsiveness in mice.

scholarly journals The rat c-kit ligand, stem cell factor, induces c-kit receptor-dependent mouse mast cell activation in vivo. Evidence that signaling through the c-kit receptor can induce expression of cellular function.

1992 ◽  
Vol 175 (1) ◽  
pp. 245-255 ◽  
Author(s):  
B K Wershil ◽  
M Tsai ◽  
E N Geissler ◽  
K M Zsebo ◽  
S J Galli
Keyword(s):  
Mast Cell ◽  
Stem Cell ◽  
Mast Cells ◽  
Stem Cell Factor ◽  
Cell Activation ◽  
Mast Cell Activation ◽  
Tyrosine Kinase Receptor ◽  
Kit Ligand ◽  
Kit Receptor

Interactions between products of the mouse W locus, which encodes the c-kit tyrosine kinase receptor, and the Sl locus, which encodes a ligand for c-kit receptor, which we have designated stem cell factor (SCF), have a critical role in the development of mast cells. Mice homozygous for mutations at either locus exhibit several phenotypic abnormalities including a virtual absence of mast cells. Moreover, the c-kit ligand SCF can induce the proliferation and maturation of normal mast cells in vitro or in vivo, and also can result in repair of the mast cell deficiency of Sl/Sld mice in vivo. We now report that administration of SCF intradermally in vivo results in dermal mast cell activation and a mast cell-dependent acute inflammatory response. This effect is c-kit receptor dependent, in that it is not observed when SCF is administered to mice containing dermal mast cells expressing functionally inactive c-kit receptors, is observed with both glycosylated and nonglycosylated forms of SCF, and occurs at doses of SCF at least 10-fold lower on a molar basis than the minimally effective dose of the classical dermal mast cell-activating agent substance P. These findings represent the first demonstration in vivo that a c-kit ligand can result in the functional activation of any cellular lineage expressing the c-kit receptor, and suggest that interactions between the c-kit receptor and its ligand may influence mast cell biology through complex effects on proliferation, maturation, and function.

scholarly journals IgE Enhances Mouse Mast Cell FcεRI Expression In Vitro and In Vivo: Evidence for a Novel Amplification Mechanism in IgE-dependent Reactions

1997 ◽  
Vol 185 (4) ◽  
pp. 663-672 ◽  
Author(s):  
Masao Yamaguchi ◽  
Chris S. Lantz ◽  
Hans C. Oettgen ◽  
Ildy M. Katona ◽  
Tony Fleming ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
Immunoglobulin E ◽  
Specific Antigen ◽  
Mast Cell Activation ◽  
Proinflammatory Mediators ◽  
Mouse Mast Cell

The binding of immunoglobulin E (IgE) to high affinity IgE receptors (FcεRI) expressed on the surface of mast cells primes these cells to secrete, upon subsequent exposure to specific antigen, a panel of proinflammatory mediators, which includes cytokines that can also have immunoregulatory activities. This IgE- and antigen-specific mast cell activation and mediator production is thought to be critical to the pathogenesis of allergic disorders, such as anaphylaxis and asthma, and also contributes to host defense against parasites. We now report that exposure to IgE results in a striking (up to 32-fold) upregulation of surface expression of FcεRI on mouse mast cells in vitro or in vivo. Moreover, baseline levels of FcεRI expression on peritoneal mast cells from genetically IgE-deficient (IgE −/−) mice are dramatically reduced (by ∼83%) compared with those on cells from the corresponding normal mice. In vitro studies indicate that the IgE-dependent upregulation of mouse mast cell FcεRI expression has two components: an early cycloheximide-insensitive phase, followed by a later and more sustained component that is highly sensitive to inhibition by cycloheximide. In turn, IgE-dependent upregulation of FcεRI expression significantly enhances the ability of mouse mast cells to release serotonin, interleukin-6 (IL-6), and IL-4 in response to challenge with IgE and specific antigen. The demonstration that IgE-dependent enhancement of mast cell FcεRI expression permits mast cells to respond to antigen challenge with increased production of proinflammatory and immunoregulatory mediators provides new insights into both the pathogenesis of allergic diseases and the regulation of protective host responses to parasites.

Spiraeoside inhibits mast cells activation and IgE-mediated allergic responses by suppressing phospholipase C-γ-mediated signaling

2015 ◽  
Vol 93 (3) ◽  
pp. 227-235 ◽  
Author(s):  
Jung Kuk Kim ◽  
Young-Kyo Seo ◽  
Sehoon Park ◽  
Soo-Ah Park ◽  
Seyoung Lim ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Phospholipase C ◽  
Cell Activation ◽  
Mapk Signaling ◽  
Mast Cell Activation ◽  
Tnf Α ◽  
Ige Mediated ◽  
Subsequent Activation

Mast cells are responsible for IgE-mediated allergic responses through the secretion of various inflammatory cytokines and mediators. Therefore, the pharmacological regulation of mast cell activation is an important goal in the development of novel anti-allergic drugs. In this study, we found that spiraeoside (SP) inhibits mast cell activation and allergic responses in vivo. SP dose-dependently inhibited the degranulation induced by IgE-antigen (Ag) stimulation in RBL-2H3 mast cells without cytotoxic effects. At the molecular level, SP reduced the Ag-induced phosphorylation and subsequent activation of phospholipase C-γ2 (PLC-γ2). Moreover, SP inhibited the phosphorylation of spleen tyrosine kinase (Syk), linker for activation of T cells (LAT), and downstream MAPKs, such as ERK1/2, p38, and JNK, eventually attenuating expression of TNF-α and IL-4. Finally, we found that SP significantly inhibited IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. Taken together, our results strongly suggest that SP suppresses IgE-mediated mast cell activation and allergic responses by inhibiting Lyn-induced PLC-γ2/MAPK signaling in mast cells.

scholarly journals S100A4 Is Critical for a Mouse Model of Allergic Asthma by Impacting Mast Cell Activation

2021 ◽  
Vol 12 ◽  
Author(s):  
Tongqian Wu ◽  
Lan Ma ◽  
Xiaoqian Jin ◽  
Jingjing He ◽  
Ke Chen ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Calcium Binding ◽  
Cell Activation ◽  
Allergic Diseases ◽  
Lavage Fluid ◽  
Mast Cell Activation ◽  
Asthma Model

BackgroundThe calcium-binding protein S100A4 demonstrates important regulatory roles in many biological processes including tumorigenesis and inflammatory disorders such as allergy. However, the specific mechanism of the contribution of S100A4 to allergic diseases awaits further clarification.ObjectiveTo address the effect of S100A4 on the regulation of mast cell activation and its impact on allergy.MethodsBone marrow-derived cultured mast cells (BMMCs) were derived from wild-type (WT) or S100A4-/- mice for in vitro investigation. WT and S100A4-/- mice were induced to develop a passive cutaneous anaphylaxis (PCA) model, a passive systemic anaphylaxis (PSA) model, and an ovalbumin (OVA)-mediated mouse asthma model.ResultsFollowing OVA/alum-based sensitization and provocation, S100A4-/- mice demonstrated overall suppressed levels of serum anti-OVA IgE and IgG antibodies and proinflammatory cytokines in serum, bronchoalveolar lavage fluid (BALF), and lung exudates. S100A4-/- mice exhibited less severe asthma signs which included inflammatory cell infiltration in the lung tissue and BALF, and suppressed mast cell recruitment in the lungs. Reduced levels of antigen reencounter-induced splenocyte proliferation in vitro were recorded in splenocytes from OVA-sensitized and challenged mice that lacked S100A4-/-. Furthermore, deficiency in the S100A4 gene could dampen mast cell activation both in vitro and in vivo, evidenced by reduced β-hexosaminidase release and compromised PCA and PSA reaction. We also provided evidence supporting the expression of S100A4 by mast cells.ConclusionS100A4 is required for mast cell functional activation, and S100A4 may participate in the regulation of allergic responses at least partly through regulating the activation of mast cells.

scholarly journals Chymase released from hypoxia-activated cardiac mast cells cleaves human apoA-I at Tyr192 and compromises its cardioprotective activity

2018 ◽  
Vol 59 (6) ◽  
pp. 945-957 ◽  
Author(s):  
Ilona Kareinen ◽  
Marc Baumann ◽  
Su Duy Nguyen ◽  
Katariina Maaninka ◽  
Andrey Anisimov ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
Mast Cell Activation ◽  
Low Flow ◽  
Human Coronary Artery ◽  
Functional Protein ◽  
Rat Hearts ◽  
Highly Sensitive

ApoA-I, the main structural and functional protein of HDL particles, is cardioprotective, but also highly sensitive to proteolytic cleavage. Here, we investigated the effect of cardiac mast cell activation and ensuing chymase secretion on apoA-I degradation using isolated rat hearts in the Langendorff perfusion system. Cardiac mast cells were activated by injection of compound 48/80 into the coronary circulation or by low-flow myocardial ischemia, after which lipid-free apoA-I was injected and collected in the coronary effluent for cleavage analysis. Mast cell activation by 48/80 resulted in apoA-I cleavage at sites Tyr192 and Phe229, but hypoxic activation at Tyr192 only. In vitro, the proteolytic end-product of apoA-I with either rat or human chymase was the Tyr192-truncated fragment. This fragment, when compared with intact apoA-I, showed reduced ability to promote migration of cultured human coronary artery endothelial cells in a wound-healing assay. We propose that C-terminal truncation of apoA-I by chymase released from cardiac mast cells during ischemia impairs the ability of apoA-I to heal damaged endothelium in the ischemic myocardium.

scholarly journals SWAP-70 Regulates c-kit-Induced Mast Cell Activation, Cell-Cell Adhesion, and Migration

2004 ◽  
Vol 24 (23) ◽  
pp. 10277-10288 ◽  
Author(s):  
Raja Rajeswari Sivalenka ◽  
Rolf Jessberger
Keyword(s):  
Mast Cell ◽  
Cell Adhesion ◽  
Mast Cells ◽  
Cell Activation ◽  
Mast Cell Activation ◽  
Calcium Flux ◽  
Mutant Cells

ABSTRACT SWAP-70, an unusual phosphatidylinositol-3-kinase-dependent protein that interacts with the RhoGTPase Rac, is highly expressed in mast cells. Cultured bone marrow mast cells (BMMC) from SWAP-70−/− mice are reduced in FcεRI-triggered degranulation. This report describes the hitherto-unknown role of SWAP-70 in c-kit receptor signaling, a key proliferation and differentiation pathway in mast cells. Consistent with the role of Rac in cell motility and regulation of the actin cytoskeleton, mutant cells show abnormal actin rearrangements and are deficient in migration in vitro and in vivo. SWAP-70−/− BMMC are impaired in calcium flux, in proper translocation and activity of Akt kinase (required for mast cell activation and survival), and in translocation of Rac1 and Rac2 upon c-kit stimulation. Adhesion to fibronectin is reduced, but homotypic cell association induced through c-kit is strongly increased in SWAP-70−/− BMMC. Homotypic association requires extracellular Ca2+ and depends on the integrin αLβ2 (LFA-1). ERK is hyperactivated upon c-kit signaling in adherent and dispersed mutant cells. Together, we suggest that SWAP-70 is an important regulator of specific effector pathways in c-kit signaling, including mast cell activation, migration, and cell adhesion.

scholarly journals Sinomenine potentiates P815 cell degranulation via upregulation of Ca2+ mobilization through the Lyn/PLCγ/IP3R pathway

2016 ◽  
Vol 29 (4) ◽  
pp. 676-683 ◽  
Author(s):  
Nan Wang ◽  
Rui Liu ◽  
Yanping Liu ◽  
Ruirui Zhang ◽  
Langchong He
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Drug Allergy ◽  
Cell Activation ◽  
Mast Cell Activation ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sinomenium Acutum ◽  
Underlying Mechanisms

Mast cells are vital mediators of drug allergy and, therefore, studying the relationship between drug allergy and mast cells is essential. Sinomenine is the principal active component of Sinomenium acutum, which has anti-inflammatory and anti-immune effects, and is used to treat various rheumatoid diseases. However, allergic responses to sinomenine are frequently reported. Therefore, this study assessed the effects of sinomenine on mast cell activation to characterize its allergic effects and the underlying mechanisms. Enzyme-linked immunosorbent assay (ELISA), western blot analyses, and degranulation assays were performed to measure pro-inflammatory and allergic mediators in P815 cells. The allergenic effects of sinomenine were also determined in mice by using active general anaphylaxis (ASA). The results indicated that sinomenine induced inositol-1,4,5-trisphosphate (IP3) production and the release of histamine, interleukin (IL)-6, and endoplasmic reticulum Ca2+ in P815 cells. Furthermore, sinomenine upregulated the phosphorylation of sarcoma (Src), phospholipase C (PLC)-γ1, and IP3 receptor (R). Therefore, sinomenine induced concentration-dependent mast cell activation directly in vitro. Furthermore, our in vivo data identified an appropriate intravenous dose that did not induce these allergic effects, thereby providing information for the potential safe clinical use of sinomenine.

Sign in / Sign up

Export Citation Format

Share Document