scholarly journals CLL-Derived Exosomes Turn Endothelial Cells into IL-6 Producing Cells

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1547-1547
Author(s):  
Orit Uziel ◽  
Lian Lipshtein ◽  
Zinab Sarsor ◽  
Einat Beery ◽  
Shaked Bogen ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Conflicts Of Interest ◽  
Dependent Manner ◽  
Cell Of Origin ◽  
Neoplastic Cells ◽  
Apoptotic Pathway ◽  
Humoral Factors ◽  
Treatment Naïve ◽  
Gradual Accumulation

Abstract CLL is characterized by gradual accumulation of mature appearing long-lived lymphocytes that travel in blood and reside in lymph nodes, spleen and bone marrow. In these sites, pro inflammatory humoral factors support the survival and proliferation of the neoplastic cells. Previous studies showed that levels of the proinflammatory cytokine IL-6 are at least 10 folds higher in patients with CLL compared with healthy individuals. Yet, which cells produce and secrete IL-6 and what triggers this cellular activity in CLL is unknown. Secreted by all types of cells, exosomes are nano-scaled particles that travel in blood and carry a cargo that at least partially reflects the molecular makeup of its cell of origin. Exosomes, including those originating from neoplastic cells, function as stable intercellular transport vehicles that deliver their cargo to cells that engulf them. For example, CLL-derived exosomes are taken up by mesenchymal stromal cells, transforming them to cancer associated fibroblasts. Given the appropriate stimulation, endothelial cells produce IL-6 which provides CLL cells with a survival advantage. Therefore, we hypothesized that CLL-exosomes turn endothelial cells into "IL-6-secreting cells". To test this hypothesis, we transfected vein-derived (HUVECs) and arterial-derived (HAOEC) endothelial cells with exosomes that we isolated from the peripheral blood of 45 treatment naïve patients. We found that endothelial cells take-up CLL-exosomes in a dose- and time- dependent manner. Since CLL cells are protected from apoptosis in IL-6 rich environment, we wondered whether CLL-exosomes turn endothelial cells into IL-6-producing cells. To test this, we exposed endothelial cells to CLL-exosomes and found 50% increase in IL-6 levels, suggesting that the endothelial-exposed cells produced and secreted IL-6. Subsequently, we filtered out this growth medium and added CLL cells to this IL-6 enriched medium. After 15 minutes, STAT3 became phosphorylated and there was 40% decrease in the rate of apoptosis, indicating that IL-6 activated STAT3-dependent anti-apoptotic pathway. Phosphor-proteomics analysis of endothelial cells that were loaded with CLL-exosomes revealed 23 phosphor-proteins that were upregulated. Network analysis unraveled the central role of phosphor-b-catenin. To test whether b-catenin induces IL-6 in these cells, we transfected HUVECs with a b-catenin containing plasmid. We found by ELISA 30% increase in the levels of IL-6 in the culture medium and by chromatin immunoprecipitation assay an increased binding of 3 transcription factors (NFkB, LEF/TCF, and CEBP) to the IL-6 promoter. Taken together, we found that CLL cells communicate with endothelial cells through exosomes that they release. Once these exosomes are taken up by endothelial, they turn them into IL-6 producing cells, which in turn contributes to CLL cells' survival. Disclosures No relevant conflicts of interest to declare.

Endothelial Cells Are Essential to Sense Lipopolysaccharide in a MYD88-Dependent Manner and to Subsequently Induce Emergency Myelopoiesis

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 641-641
Author(s):  
Steffen Boettcher ◽  
Rahel Gerosa ◽  
Ramin Radpour ◽  
Markus G. Manz
Keyword(s):  
Endothelial Cells ◽  
Conflicts Of Interest ◽  
Critical Role ◽  
Hematopoietic Cells ◽  
Clinical Signs ◽  
Dependent Manner ◽  
Perivascular Cells ◽  
Hematopoietic Stem ◽  
Emergency Myelopoiesis

Abstract Abstract 641 Severe systemic infections evoke a number of characteristic clinical signs such as fever, neutrophilia and the appearance of immature myeloid precursors in the circulation (left-shift). This reflects a well-regulated hematopoietic response program to enhance myeloid cell output during times of increased hematopoietic demand, a condition which is referred to as 'emergency myelopoiesis'. Important molecular components of the emergency myelopoiesis cascade, such as cytokines and transcription factors involved, have been elucidated. However, the initial steps of emergency myelopoiesis involving pathogen recognition and translation into accelerated bone marrow (BM) myelopoiesis have only been inferred from findings on Toll-like receptor (TLR) expression on immature hematopoietic stem and progenitor cells (HSPCs) as well as on mature hematopoietic cells (e.g. macrophages). Accordingly, it has been assumed that both immature as well as mature hematopoietic cells are involved in sensing infection and inducing emergency myelopoiesis directly and indirectly, respectively. Surprisingly, by generating reciprocal BM chimeric animals mice with TLR4−/− hematopoiesis on a wild-type (WT) nonhematopoietic background (TLR4−/−→WT mice) and WT hematopoiesis on a TLR4−/− nonhematopoietic background (WT→TLR4−/−mice), we demonstrated that LPS-Induced emergency myelopoiesis depends on TLR4-expressing nonhematopoietic cells (Boettcher et al., J Immunol. 2012 Jun 15;188(12):5824–8.). However, the precise identity and localization of the nonhematopoietic cell type crucial for sensing gramnegative infection-derived lipopolysaccharide (LPS) has remained elusive to date. We now have addressed this fundamental question using BM transplantation experiments and Cre-loxP recombination technology. BM chimeric mice with a myeloid differentiation primary response gene 88 (Myd88)-deficiency in the hematopoietic lineage (MYD88−/−→WT mice) showed a normal LPS response indistinguishable to control (WT→WT) mice, while knocked out Myd88 within the nonhematopoietic compartment (WT→MYD88−/− mice) led to a non-responsiveness towards LPS similar to controls (Myd88−/−→Myd88−/− mice). These results are in line with our earlier data, thus confirming the critical role of the TLR4/MYD88 pathway in nonhematopoietic cells for the induction of emergency myelopoiesis. In order to specifically delete TLR-MyYD88-downstream signaling in various nonhematopoietic cells including BM Nestin+ mesenchymal stem cells (MSCs) and their progeny, perivascular cells, endothelial cells, and hepatocytes, we generated Nes-Cre;Myd88fl/fl, Pdgfrb-Cre;Myd88fl/fl, Tek-Cre;Myd88fl/fl, and Alb-Cre;Myd88fl/fl mice, respectively. We observed a normal increase in the frequency of BM CD11b+Gr-1low immature myeloid precursors accompanied by a decrease of BM CD11b+Gr-1high mature myeloid cells upon LPS stimulation characteristic for efficient emergency myelopoiesis in Nes-Cre;Myd88fl/fl, Pdgfrb-Cre;Myd88fl/fl, and Alb-Cre;Myd88fl/fl mice as compared to control mice. Furthermore, we measured highly-elevated plasma G-CSF levels in these mouse strains upon LPS injection. Hence, intact TLR signaling in mesenchymal stromal cells incl. Nestin+ MSCs, perivascular cells as well as hepatocytes is dispensable for induction of emergency myelopoiesis. Strikingly, Tek-Cre;Myd88fl/fl mice were completely non-responsive towards LPS stimulation as assessed by the above-mentioned parameters. Our results thus demonstrate a fundamental and unanticipated role of the endothelium for sensing of systemically spread pathogens and subsequent stimulation of BM emergency myelopoiesis. Disclosures: No relevant conflicts of interest to declare.

Abstract 218: Pericytic Laminin Regulates Blood-Brain Barrier Integrity in an Age-Dependent Manner

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Yao Yao ◽  
Jyoti Gautam ◽  
Xuanming Zhang
Keyword(s):  
Endothelial Cells ◽  
Basement Membrane ◽  
Blood Brain Barrier ◽  
Vessel Density ◽  
Brain Barrier ◽  
Dependent Manner ◽  
Vascular Integrity ◽  
Blood Brain ◽  
Age Dependent

Introduction: Laminin, a major component of the basement membrane, plays an important role in blood brain barrier (BBB) regulation. At the neurovascular unit, astrocytes, brain endothelial cells, and pericytes synthesize and deposit different laminin isoforms into the basement membrane. Previous studies from our laboratory showed that loss of astrocytic laminin induces age-dependent and region-specific BBB breakdown and intracerebral hemorrhage, suggesting a critical role of astrocytic laminin in vascular integrity maintenance. Laminin α4 (predominantly generated by endothelial cells) has been shown to regulate vascular integrity at embryonic/neonatal stage. The role of pericytic laminin in vascular integrity, however, remains elusive. Methods: We investigated the function of pericyte-derived laminin in vascular integrity using laminin conditional knockout mice. Specifically, laminin floxed mice were crossed with PDGFRβ-Cre line to generate mutants (PKO) with laminin deficiency in PDGFRβ + cells, which include both pericytes and vascular smooth muscle cells (vSMCs). To distinguish the contribution of pericyte- and vSMC-derived laminin, we also generated a vSMC-specific condition knockout line (TKO) by crossing the laminin floxed mice with Transgelin-Cre mice. In this study, mice of both genders on a C57Bl6 background were used. At least 5-6 animals were used in biochemical and histological analyses in this study. Results: Pericyte-derived laminin was abrogated in all PKO mice. However, only old but not young PKO mice showed signs of BBB breakdown and reduced vessel density, suggesting age-dependent changes. Consistent with these data, further mechanistic studies revealed reduced tight junction proteins, diminished AQP4 expression, and deceased pericyte coverage in old but not young PKO mice. In addition, neither BBB disruption nor decreased vessel density was observed in TKO mice, suggesting that these vascular defects are due to loss of pericyte- rather than vSMC-derived laminin. Conclusions: These results strongly suggest that pericyte-derived laminin active regulates BBB integrity and vessel density in an age-dependent manner. I would like this abstract to be considered for the Stroke Basic Science Award.

Anti-Leukemia and Multiple Myeloma Selective Activity of CXCR4 Antagonist 4F-Benzoyl-TN14003 Involves Apoptotic Death Pathway.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3857-3857
Author(s):  
Katia Beider ◽  
Michal Begin ◽  
Michal Abraham ◽  
Hanna Wald ◽  
Ido Weiss ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Hematological Malignancies ◽  
Conflicts Of Interest ◽  
K562 Cells ◽  
Jurkat Cells ◽  
G1 Arrest ◽  
Dependent Manner ◽  
Hl60 Cells

Abstract Abstract 3857 Poster Board III-793 The chemokine receptor CXCR4 and its ligand CXCL12 are involved in the development and progression of a diverse number of hematological malignancies, including leukemia, lymphoma and multiple myeloma (MM). Binding CXCL12 to CXCR4 activates a variety of intracellular signal transduction pathways and effector molecules that regulate cell chemotaxis, adhesion, survival, apoptosis and proliferation. It was previously shown that CXCR4 signaling can directly induce caspase-independent cell apoptosis through the interaction with the HIV gp120 envelope protein. In the present study we investigated the effect of CXCR4 specific antagonists 4F-benzoyl-TN14003 (T140) and AMD3100 on the survival and proliferation of different human hematological cancer cells. Here, we demonstrate that T140, but not AMD3100, exhibits preferential cytotoxicity towards malignant cells of hematopoietic origin, as compared to primary normal cells or solid prostate and breast tumor cells. The in vitro treatment with T140, but not with AMD3100, significantly decreased the number of viable chronic myeloid leukemia K562 cells, acute T cell leukemia Jurkat cells, acute promyelocytic leukemia NB4 and HL60 cells, and four different MM cell lines (U266, NCI-H929, RPMI8226 and ARH77), demonstrating the highest sensitivity to T140 (p<0.01). Notably, T140 inhibited the growth of freshly isolated leukemia and MM cells obtained from consenting patients. T140 inhibits the growth of MM and leukemic cells by inducing their apoptotic cell death. The apoptotic changes in the cells were associated with morphological changes, phosphatidylserine externalization, sub-G1 arrest, DNA double-stranded breaks, decrease in mitochondrial membrane potential, release of cytochrome c, and caspase 3 activation. The important role of CXCR4 in T140-mediated cell death was confirmed by demonstrating that CXCR4 over-expression in NB4 and K562 cells increased their sensitivity to T140. Furthermore, pretreatment of NB4 and HL60 cells with AMD3100 abolishes the effect of T140 on these cells, indicating the involvement of CXCR4 in T140-induced apoptosis. Importantly, the combination with novel anti-myeloma agent bortezomib significantly augments anti-myeloma activity of T140. The anti leukemic and MM effect of T140 was confirmed in xenograft in vivo tumor models. Subcutaneous (s.c.) or intra-peritoneal (i.p.) injections of T140 (100 or 300 mcg/mouse) significantly reduced, in a dose-dependent manner, the tumor size in immuno-deficient mice that were previously inoculated s.c. with human acute leukemia cells NB4 or MM cells RPMI8226 (p<0.01). Tumors from animals treated with T140 had smaller sizes and weights, larger necrotic areas and high apoptotic scores. Taken together, these data support the unique anti-cancer effect of T140 in hematological malignancies and indicate the potential therapeutic role of T140 in MM and leukemia patients. Disclosures: No relevant conflicts of interest to declare.

Neutrophils Clearance by Endothelial Cells Regulates Homeostasis and Coagulation.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3782-3782
Author(s):  
Wen Li ◽  
Shuchuan Liu ◽  
Yueyue Fu ◽  
Jinxiao Hou ◽  
Xiushuai Dong ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Kupffer Cells ◽  
Milk Fat ◽  
Conflicts Of Interest ◽  
Umbilical Vein ◽  
Large Fraction ◽  
Background Level ◽  
Procoagulant Activity ◽  
Phagocytic Cells

Abstract Abstract 3782 Neutrophils, also called polymorphonuclear leukocytes (PMN's) have a half-life of only 6 hours in the blood. Inflammation can further shorten the circulating life-time. A large fraction of the bone marrow capacity is committed to ongoing production of these short-lived cells but the manner of their clearance from the circulation is less well understood. We have previously demonstrated that PMN's are cleared by liver macrophages. However, the details of PMN adhesion-induced PMN clearance in the liver are unknown. The aim of this study is to evaluate a pathway of PMNs clearance by endothelial cells, which are not ordinarily considered phagocytes. Lactadherin is a glycoprotein of milk fat globules and is also secreted by stimulated macrophages. Lactadherin binds phosphatidylserine on apoptotic cells via tandem lectin-homology domains with homology to factor VIII and binds αvβ3 and αvβ5 integrins on phagocytic cells via an RGD sequence in an epithelial growth factor domain. Lactadherin aids in engulfment of senescent lymphocytes by splenic macrophages and mediates an anti-inflammatory response. We utilized lactadherin as a probe to detect phosphatidylserine exposure on aging PMN's and evaluated the lactadherin-dependent engulfment of these PMN's by endothelial cells. Cultured human PMNs from healthy donors, with 95% purity, were 40% and 96% PS-exposure positive at 9 and 24 h, respectively. They displayed a parallel increase in procoagulant supporting, activity related to the PS exposure. Coculture of the aging PMNs and human umbilical vein endothelial cells resulted in phagocytosis of the PMN's, observed by confocal microscopy and electron microscopy. Exogenous lactadherin increased phagocytosis by 3–5 fold during 120 minutes of observation. An anti-lactadherin RGD antibody and an anti-lactadherin C2 domain antibody inhibited phagocytosis to approx 1/2 the background level suggesting that lactadherin secreted by PMN's or neutrophils contributes to the base level of phagocytosis. Clearance of the senescent neutrophils by endothelial cells decreased procoagulant activity >70% and blockade of neutrophil PS with lactadherin reduced procoagulant activity by > 90% indicating the potential role of neutrophil uptake in limiting prothrombotic activity. In a rat model of neutrophil homeostasis we injected low dose lipopolysaccharide (LPS) and gadolinium chloride intravenously to increase the number circulating PMN's and block clearance by Kupffer cells. This allowed observation of PMN adhesion and sequestration in the liver. The number of PMNs peaked at 9 h and decreased to the normal range at 24 h after blockade of Kupffer cells. Blocking the endothelial P-selectin significantly delayed PMN's removal in the liver. Injection of lactadherin promoted the PMNs accumlation and removal. The current results suggest that ECs contribute to maintaining the homeostasis of PMNs in the circulation and a possible role of lactadherin in the EC-mediated clearance. Our results also indicate that lactadherin-mediated clearance may limit procoagulant or prothrombotic activity of senescent PMN's. Disclosures: No relevant conflicts of interest to declare.

Apolipoprotein(a)-Dependent Inhibition of Pericellular Plasminogen Activation Is Mediated by Specific Cellular Receptors

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2236-2236
Author(s):  
Rocco Romagnuolo ◽  
Michael B Boffa ◽  
Marlys L Koschinsky
Keyword(s):  
Cell Surface ◽  
Plasminogen Activator ◽  
Conflicts Of Interest ◽  
Cell Surface Receptor ◽  
Dependent Manner ◽  
Plasminogen Activation ◽  
Apolipoprotein A ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator

Abstract Abstract 2236 Lipoprotein(a) [Lp(a)] has been identified as an independent risk factor for cardiovascular diseases such as coronary heart disease. Lp(a) levels vary over 1000-fold within the human population and Lp(a) possesses both proatherogenic and prothrombotic properties due to the LDL-like moiety and apolipoprotein(a) [apo(a)] components, respectively. Apo(a) is highly homologous to plasminogen and thus can potentially interfere with plasminogen activation. Plasmin generated in the context of fibrin mediates the breakdown of blood clots, which are the causative factors in heart attacks and strokes. Plasmin generated on the surface of vascular cells plays a role in cell migration and proliferation, two of the fibroproliferative inflammatory events that underlie atherosclerosis. Previous studies have suggested that apo(a) may inhibit pericellular plasminogen activation on the basis of observations that apo(a) decreases plasminogen binding to cells. We have undertaken analysis of the mechanism by which apo(a) may interfere with pericellular plasminogen activation to allow for a more definitive description of the role of Lp(a) within the vasculature. Plasminogen activation was found to be markedly inhibited by the recombinant apo(a) variant 17K, in a dose dependent manner, on human umbilical vein endothelial cells (HUVECs), human monocytic leukemia cells (THP-1), THP-1 macrophages, and smooth muscle cells. The strong lysine binding site in kringle IV type 10, as well as kringle V appear to be required for this effect since apo(a) variants lacking these elements (17KΔAsp and 17KΔV, respectively) failed to inhibit activation. However, the role of lysine-dependent binding of apo(a) itself to the cells is not clear. Carboxypeptidase treatment of cells did not decrease apo(a) binding, and apo(a) does not compete directly for plasminogen binding to the cells. Rather, apo(a) and plasminogen may bind to the cells as a complex. We next attempted to identify the cell-surface receptor(s) that mediate plasminogen activation on the cell surface as well as its inhibition by apo(a). Urokinase-type plasminogen activator receptor (uPAR) has been previously shown to bind to urokinase-type plasminogen activator (uPA), vitronectin, and β3 integrins. uPAR is involved in the remodeling of the extracellular matrix (ECM) through regulation of plasminogen activation. We found evidence that uPAR is a potential receptor for both plasminogen and apo(a). Knockdown of uPAR in HUVECs results in decreased binding of plasminogen, 17K and, to a lesser extent, 17KΔAsp and 17KΔV. Similar experiments in SMCs revealed no changes in binding. A decrease in tPA-mediated plasminogen activation following uPAR knockdown occurred in HUVECs, and addition of 17K did not result in any further decrease. Overexpression of uPAR in THP-1 macrophages leads to greater than a two fold increase in 17K and plasminogen binding. Plasminogen activation increases over two-fold as a result of overexpression of uPAR, while 17K blunts the effect of uPAR overexpression. These results indicate that uPAR plays a crucial role in both plasminogen and apo(a) binding to the cell surface of specific cells and inhibition by apo(a) of plasminogen activation. Macrophage-1-antigen (Mac-1) receptor consists of CD11b (αM) and CD18 (β2) integrin and has been previously shown to recognize uPA and control migration and adhesion. Furthermore, αVβ3 has been previously shown to bind to vitronectin and the uPA-uPAR complex which promotes cell adhesion through binding of both vitronectin and αVβ3 integrins. We found that blocking the αM, β2, or αVβ3 receptors with monoclonal antibodies in THP-1 cells leads to a decrease in plasminogen activation, as well as a blunting of the inhibitory effects of apo(a) on plasminogen activation. These results indicate a role for Mac-1 and αVβ3 in apo(a) binding and inhibition of plasminogen activation. In conclusion, we have demonstrated, for the first time, the role of specific receptors in binding of apo(a) to vascular cell surfaces and in mediating the inhibitory effect of apo(a) on pericellular plasminogen activation. Disclosures: No relevant conflicts of interest to declare.

Flt3 Kinase Regulates Microvesicle Transfer of miRNA Between AML and Stromal Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1492-1492
Author(s):  
Noah Hornick ◽  
Jianya Huan ◽  
Jeffrey W Tyner ◽  
Peter Kurre
Keyword(s):  
Cell Lines ◽  
Stromal Cells ◽  
Conflicts Of Interest ◽  
Membrane Vesicles ◽  
Mirna Expression Profile ◽  
Cell Phenotype ◽  
Cell Of Origin ◽  
Hematopoietic Stem ◽  
Global Comparison

Abstract Abstract 1492 The presence of an internal tandem duplication in the receptor tyrosine kinase Flt3 (Flt3-ITD) is found in 25–30% of cytogenetically normal AML and confers a worsened prognosis, including an increased likelihood for relapse after hematopoietic stem cell transplantation (HSCT). This tendency toward relapse, combined with the improved capacity of Flt3-ITD+ disease to resist chemotherapy, may imply mechanisms of resistance beyond those present in leukemias lacking this mutation. Microvesicles and exosomes, membrane-bound extracellular vesicles that capture cell-specific protein and RNA, have previously been isolated from the serum of CLL patients (Ghosh et al., Blood 2010 Mar 4;115(9): 1755–64). We recently observed that vesicles are constitutively produced by both AML cell lines and by AML blasts isolated from patients. Using light scatter analysis and transmission electron microscopy, we found that vesicles produced by the HL60 (Flt3-ITD-) and Molm14 (Flt3-ITD+) cell lines, as well as by AML patient cells, predominantly fall within the 30–100nm range, generally considered to specify exosomes. To demonstrate vesicle transfer to neighboring cells, we labeled vesicles produced by the HL-60 cell line with the fluorescent membrane dye PKH-26 and imaged their uptake by stromal cells. Internalization of labeled exosomes was detectable within 15 minutes following exposure, and occurred at approximately 27 particles per cell by 2 hours (n=20). This result indicates rapid uptake of exosomes by non-phagocytic bystander cells, and supports a potential role for the vesicle content in altering the cell phenotype. We next tested for the presence of certain candidate mRNAs in the AML cell lines HEL, HL-60, MOLM-14, and U937, and in vesicles produced by those cell lines. We detected several relevant mRNAs, including nucleophosmin-1 and Flt3-ITD, in the vesicle preparations. During a more global comparison of vesicle and cell-of-origin RNA spectra using bioanalyzer analysis, we found that the RNA in microvesicles from (Flt3-ITD+) MOLM14 cells contained no detectable ribosomal RNA, but a markedly increased proportion of small RNA transcripts, suggesting that miRNA content might be increased. An initial screen of cultured MOLM-14 cells in the presence and absence of a small-molecule Flt3 inhibitor (AC220) and microvesicles isolated from the culture supernatant revealed several candidate miRNAs, including let-7a, miR-99b, and miR-155, whose expression varied with the presence of inhibitor. Our results not only support a role for Flt3 kinase activation in determining the miRNA expression profile, but provide evidence for the kinase-regulated incorporation of miRNA into cell membrane vesicles. The recent description of several AML subtypes, including Flt3-ITD+ disease with unique miRNA profiles, and the role of miRNA as potent regulators of both microenvironmental function and immune responses provides strong motivation to evaluate the role of vesicles in AML therapy evasion. Disclosures: No relevant conflicts of interest to declare.

Role of G proteins in shear stress-mediated nitric oxide production by endothelial cells

1994 ◽  
Vol 267 (3) ◽  
pp. C753-C758 ◽  
Author(s):  
M. J. Kuchan ◽  
H. Jo ◽  
J. A. Frangos
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Shear Stress ◽  
G Protein ◽  
G Proteins ◽  
No Production ◽  
Dependent Manner ◽  
Protein Activation ◽  
Synthase Inhibitor

Exposure of cultured endothelial cells to shear stress resulting from well-defined fluid flow stimulates the production of nitric oxide (NO). We have established that an initial burst in production is followed by sustained steady-state NO production. The signal transduction events leading to this stimulation are not well understood. In the present study, we examined the role of regulatory guanine nucleotide binding proteins (G proteins) in shear stress-mediated NO production. In endothelial cells not exposed to shear stress, AIF4-, a general activator of G proteins, markedly elevated the production of guanosine 3',5'-cyclic monophosphate (cGMP). Pretreatment with NO synthase inhibitor N omega-nitro-L-arginine completely blocked this stimulation. Incubation with guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), a general G protein inhibitor, blocked the flow-mediated burst in cGMP production in a dose-dependent manner. Likewise, GDP beta S inhibited NOx (NO2 + NO3) production for the 1st h. However, inhibition was not detectable between 1 and 3 h. Pertussis toxin (PTx) had no effect on the shear response at any time point. The burst in NO production caused by a change in shear stress appears to be dependent on a PTx-refractory G protein. Sustained shear-mediated production is independent of G protein activation.

Permeability of endothelial monolayers to albumin is increased by bradykinin and inhibited by prostaglandins

2001 ◽  
Vol 280 (4) ◽  
pp. L732-L738 ◽  
Author(s):  
Pierre J. Farmer ◽  
Sylvie G. Bernier ◽  
Andrée Lepage ◽  
Gaétan Guillemette ◽  
Domenico Regoli ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Adenylate Cyclase ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Intracellular Level ◽  
Concentration Dependent Manner ◽  
Aortic Endothelial Cells ◽  
Endothelial Monolayers ◽  
Bovine Aortic Endothelial Cells

Using monolayers of bovine aortic endothelial cells (BAEC) in modified Boyden chambers, we examined the role of prostaglandins (PGs) in the bradykinin (BK)-induced increase of albumin permeability. BK induced a concentration-dependent increase of the permeability of BAEC, which reached 49.9 ± 1% at the concentration of 10−8 M. Two inhibitors of the prostaglandin G/H synthase, indomethacin (2.88 μM) and ibuprofen (10 μM), potentiated BK-induced permeability 1.8- and 3.9-fold, respectively. Exogenously administered PGE2and iloprost, a stable analog of prostacyclin, attenuated the effect of BK in a concentration-dependent manner. Butaprost equally reduced the effect of BK, suggesting the participation of the EP2receptor in this phenomenon. However, the EP4-selective antagonist AH-23848 did not significantly inhibit the protective effect of PGE2. The inhibitory effect of PGE2 was reversed by the adenylate cyclase inhibitor MDL-12330A (10 μM). These results suggest that BK-induced increase of permeability of BAEC monolayer to 125I-labeled albumin is negatively regulated by PGs. This postulated autocrine activity of PGs may involve an increase in the intracellular level of cAMP.

Abstract 570: Cystathionine γ-Lyase Modulates Flow-dependent Vascular Remodeling

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Shuai Yuan ◽  
Arif Yurdagul ◽  
Jonette M Green ◽  
Sibile Pardue ◽  
Christopher G Kevil ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Remodeling ◽  
Oscillatory Flow ◽  
Carotid Arteries ◽  
Dependent Manner ◽  
Disturbed Flow ◽  
Sulfane Sulfur ◽  
Nitrite Level

Disturbed flow causes endothelial dysfunction and development of atherosclerotic lesions. The gaseous signaling molecule H 2 S and cystathionine γ-lyase (CSE), its major enzymatic source in the vasculature, protect against cardiovascular diseases including atherosclerosis, peripheral artery disease, and cardiac ischemia in a nitric oxide (NO) dependent manner. Therefore, we sought to investigate the role of CSE in the endothelial response to disturbed flow. Wild-type C57Bl/6 (WT) and CSE knockout (CSE-/-) mice underwent partial carotid ligation to induce disturbed flow in the left carotid with the right carotid serving as an internal control. Additionally, endothelial cells isolated from WT and CSE-/- mice were exposed to oscillatory flow, a model of disturbed flow, in vitro. While disturbed flow decreased endothelial CSE mRNA expression, CSE protein expression showed strong induction under disturbed flow conditions both in vitro and in vivo. This induction correlated with enhanced free sulfide and sulfane sulfur production in WT but not in CSE-/- mice. Intimal mRNA isolated 2 days post-ligation showed increased VCAM-1 and ICAM-1 expression in WT mice which was prevented in CSE-/- mice. Similarly, endothelial cells isolated from CSE-/- mice show reduced NF-B activation and proinflammatory gene expression in response to oscillatory flow in vitro. Morphometric analysis of carotid arteries collected 7 days post-ligation revealed reduced macrophage infiltration and medial thickening in the ligated carotid of CSE-/- mice. Interestingly, ligation increased the carotid nitrite level in WT mice but not in CSE-/- mice. However, nitrite level of the non-ligated carotid was significantly higher in the CSE-/- mice compared to WT mice. Shear induced phosphorylation of eNOS Ser1179 in vitro was not different between WT and CSE knockout endothelial cells, suggesting alternative regulatory mechanisms. Collectively, CSE in mouse carotid arteries plays a critical role in flow dependent vascular remodeling, which may be mediated by CSE derived free sulfide and sulfane sulfur. CSE deficiency completely inhibits disturbed flow-induced NF-κB activation and macrophage recruitment, consistent with the role of inflammation in vascular remodeling.

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