Known players, new interplay in atherogenesis: Chronic shear stress and carbamylated-LDL induce and modulate expression of atherogenic LR11 in human coronary artery endothelium

2014 ◽  
Vol 111 (02) ◽  
pp. 323-332 ◽  
Author(s):  
Eva-Theres Gensberger ◽  
Susanna Scharrer ◽  
Heinz Regele ◽  
Klaus Aumayr ◽  
Chantal Kopecky ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Ldl Receptor ◽  
Low Density ◽  
High Shear ◽  
High Shear Stress ◽  
Human Coronary Artery ◽  
Static Conditions

SummaryIn this study we examined whether low-density lipoprotein (LDL) receptor family members represent a link between blood flow characteristics and modified low-density lipoproteins involved in endothelial injury, a pivotal factor in atherogenesis. We demonstrated the expression of pro-atherogenic LDL receptor relative (LR11) for the first time in human coronary artery endothelial cells (HCAEC) in vitro and in vivo. Next, LR11 expression and regulation were explored in HCAEC cultured conventionally or on the inner surface of hollow fiber capillaries under exposure to shear stress for 10 days in the presence or absence of LDL. There was no LR11 expression under static conditions. When exposed to chronic low shear stress (2.5 dynes/cm2) transmembrane and soluble endothelial-LR11 were detected in high levels irrespective of the type of LDL added (carbamylated or native). In contrast, chronic high shear stress (25 dynes/cm2) inhibited the LR11-inducing effect of LDL such that transmembrane and soluble LR11 expression became non-detectable with native LDL. Carbamylated LDL significantly counteracted this atheroprotective effect of high shear stress as shown by lower, yet sustained expression of soluble and transmembrane LR11. Oxidised LDL showed similar effects compared to carbamylated LDL but caused significantly lower LR11 expression under chronic high shear stress. Medium from HCAEC under LR11-inducing conditions enhanced vascular smooth muscle cell migration, which was abrogated by the anti-LR11 antibody. Expression of LR11 depended entirely on p38MAPK phosphorylation. We conclude that coronary endothelial LR11 expression modulated by LDL and chronic shear stress contributes to atherogenesis. LR11 and p38MAPK are potential targets for prevention of atherosclerosis.

Platelet Aggregation and Activation under Complex Patterns of Shear Stress

2002 ◽  
Vol 88 (11) ◽  
pp. 817-821 ◽  
Author(s):  
Jian-ning Zhang ◽  
Angela Bergeron ◽  
Qinghua Yu ◽  
Carol Sun ◽  
Larry McIntire ◽  
...  
Keyword(s):  
Shear Stress ◽  
Platelet Aggregation ◽  
Platelet Activation ◽  
Low Flow ◽  
High Shear ◽  
High Shear Stress ◽  
Fast Flow ◽  
Low Shear

SummaryArterial stenosis results in a complex pattern of blood flow containing an extremely fast flow in the throat of stenosis and a post-stenosis low flow. The fast flow generates high shear stress that has been demonstrated in vitro to activate and aggregate platelets. One potential problem of these in vitro studies is that platelets are invariably exposed to a high shear stress for a period that is significantly longer than they would have experienced in vivo. More importantly, the role of the poststenosis low flow in platelet activation and aggregation has not been determined. By exposing platelets to a shear profile that contains both high and low shear segments, we found that platelets aggregate when they are exposed to a high shear stress of 100 dyn/cm2 for as short as 2.5 s, a period that is significantly shorter than those previously reported (30–120 s). Platelet aggregation under this condition requires a low shear exposure immediately after a high shear pulse, suggesting that post-stenosis low flow enhances platelet aggregation. Furthermore, platelet aggregation under this condition is not activation-dependent because the CD62P expression of sheared platelets is significantly less than that of platelets treated with ADP. Based on these findings, we propose that shear-induced platelet aggregation may be a process of mechanical crosslinking of platelets, requiring minimal platelet activation. This process may function as a protective mechanism to prevent in vivo irreversible platelet activation and aggregation under temporary high shear.

scholarly journals MPST but not CSE is the primary regulator of hydrogen sulfide production and function in the coronary artery

2016 ◽  
Vol 310 (1) ◽  
pp. H71-H79 ◽  
Author(s):  
Maggie M. Kuo ◽  
Dae Hee Kim ◽  
Sandeep Jandu ◽  
Yehudit Bergman ◽  
Siqi Tan ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Coronary Artery ◽  
Ex Vivo ◽  
Human Coronary Artery ◽  
Sodium Hydrosulfide ◽  
Physiological Relevance ◽  
Hydrogen Sulfide Production ◽  
And Function

Hydrogen sulfide (H2S) has emerged as an important gasotransmitter in the vasculature. In this study, we tested the hypothesis that H2S contributes to coronary vasoregulation and evaluated the physiological relevance of two sources of H2S, namely, cystathionine-γ-lyase (CSE) and 3-mercaptypyruvate sulfertransferase (MPST). MPST was detected in human coronary artery endothelial cells as well as rat and mouse coronary artery; CSE was not detected in the coronary vasculature. Rat coronary artery homogenates produced H2S through the MPST pathway but not the CSE pathway in vitro. In vivo coronary vasorelaxation response was similar in CSE knockout mice, wild-type mice (WT), and WT mice treated with the CSE inhibitor propargylglycine, suggesting that CSE-produced H2S does not have a significant role in coronary vasoregulation in vivo. Ex vivo, the MPST substrate 3-mercaptopyruvate (3-MP) and H2S donor sodium hydrosulfide (NaHS) elicited similar coronary vasoreactivity responses. Pyruvate did not have any effects on vasoreactivity. The vasoactive effect of H2S appeared to be nitric oxide (NO) dependent: H2S induced coronary vasoconstriction in the presence of NO and vasorelaxation in its absence. Maximal endothelial-dependent relaxation was intact after 3-MP and NaHS induced an increase in preconstriction tone, suggesting that endothelial NO synthase activity was not significantly inhibited. In vitro, H2S reacted with NO, which may, in part explain the vasoconstrictive effects of 3-MP and NaHS. Taken together, these data show that MPST rather than CSE generates H2S in coronary artery, mediating its effects through direct modulation of NO. This has important implications for H2S-based therapy in healthy and diseased coronary arteries.

Platelets, after Exposure to a High Shear Stress, Induce IL-10-Producing, Mature Dendritic Cells In Vitro

2004 ◽  
Vol 172 (9) ◽  
pp. 5297-5303 ◽  
Author(s):  
Masao Hagihara ◽  
Ayako Higuchi ◽  
Noriko Tamura ◽  
Yoko Ueda ◽  
Kaori Hirabayashi ◽  
...  
Keyword(s):  
Shear Stress ◽  
Dendritic Cells ◽  
High Shear ◽  
High Shear Stress

Abstract 273: Shear Stress--Induced Atherosclerotic Plaque Regression Explained by Increased Macrophage Efferocytosis and Migration

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Stefania Simeone ◽  
Talin Ebrahimian ◽  
Veronique Michaud ◽  
Stephanie Lehoux
Keyword(s):  
Shear Stress ◽  
High Fat Diet ◽  
Cell Movement ◽  
Atherosclerotic Plaques ◽  
High Shear ◽  
High Fat ◽  
Mmp Inhibitor ◽  
Plaque Regression ◽  
Static Conditions

Atherosclerotic plaques form in regions of low blood flow, whereas vessels exposed to high shear stress remain lesion-free. Using a model of arteriovenous fistula (AVF) in mice, we have previously shown that exposing established atherosclerotic plaques to elevated shear stress leads to lesion regression and increased matrix metalloproteinase (MMP) activity. MMP inhibition abolished shear stress-induced plaque regression and macrophage migration, suggesting that facilitating inflammatory cell movement within the plaque contributes to regression. We hypothesized that increased shear stress also leads to more efficient efferocytosis, another important hallmark of regression. LDLR-/- mice were placed on a high-fat diet. Sham and AVF surgery was performed at week 12 and mice were kept on a high-fat diet for a further 4 weeks (wk16). Control mice were sacrificed at wk12. The AVF procedure increases the shear stress in the brachiocephalic artery (BCA) but does not alter serum lipid levels. Using 3D echocardiography between wk12 and wk16, we observed that plaques progressed in the BCA of sham mice, whereas the AVF plaques regressed. Furthermore, the size of the necrotic core was significantly smaller in the AVF plaques than sham and control (P<0.05). This could be due to increased efferocytosis in the AVF, as verified using an in vitro model of the plaque environment. Endothelial cells (EC) were co-cultured with macrophages in a system wherein ECs are exposed to high or no shear stress and macrophages are exposed to the EC effluent. Uptake of apoptotic cells by macrophages was 50% higher in the high shear vs. static conditions (P<0.01). The MMP inhibitor, GM6001, had no effect on efferocytosis. However, a cytokine array on the co-culture effluent revealed interesting candidates. CCL3 and GMCSF, both of which have been associated with enhanced efferocytosis, were more highly expressed in high shear conditions vs. static. Our findings suggest that shear stress increases efferocytosis, leading to smaller necrotic cores through a mechanism that probably involves altered cytokine production. The combination of more efficient cell migration and efferocytosis in the presence of increased shear stress likely leads to plaque regression.

Shear Stress Initiates Cyclophilin D-Dependent Phosphatidylserine Exposure and Integrin αIIbβ3 Cleavage in Platelets

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3301-3301
Author(s):  
Fang Liu ◽  
Shawn M Jobe
Keyword(s):  
Shear Stress ◽  
Extracellular Calcium ◽  
Stress Conditions ◽  
High Shear ◽  
Cyclophilin D ◽  
High Shear Stress ◽  
Integrin Αiibβ3 ◽  
Platelet Accumulation ◽  
Platelet Formation

Abstract Abstract 3301 When platelets are simultaneously stimulated by multiple agonists, such as thrombin and collagen, a subpopulation of procoagulant platelets is formed that is characterized by phosphatidylserine (PS) exposure, integrin αIIbβ3 inactivation, and a rounded morphology in a process that is dependent on the mitochondrial permeability transition pore (mPTP) regulatory protein cyclophilin D (CypD). Recently, we have found that, in the absence of platelet CypD, platelet accumulation is markedly accentuated both in vitro and in vivo indicating that CypD-dependent procoagulant platelet formation may limit thrombus growth. Interestingly, the importance of CypD in limiting platelet accumulation was most evident in shear stress conditions consistent with arterial flow. In low (300 s−1) and high (1500 s−1) shear conditions, CypD null platelet accumulation was increased 1.5- and 4-fold compared to wild type platelets, respectively. Platelet activation and procoagulant platelet formation were examined in various shear conditions. In platelets subjected to increasing shear, PS exposure, but not P-selectin expression or integrin αIIbβ3 activation, was observed in a platelet subpopulation. When subjected to high shear in vitro as many as 70 % of platelets expressed high levels of PS on their surface within 5 min, and shear-dependent PS exposure was observed in as little as 30 seconds in high shear stress conditions. Previously we demonstrated that agonist-initiated PS exposure is closely associated with integrin αIIbβ3 cleavage and inactivation. In shear-treated, as in strongly-stimulated platelets, integrin αIIbβ3 cleavage was closely associated with PS exposure. PS exposure and integrin αIIbβ3 cleavage were not observed in the absence of VWF. In contrast to agonist-initiated PS exposure, shear stress-induced PS exposure was observed even in the absence of extracellular calcium. In a previous study, platelet PS exposure and apoptosis induced by ristocetin were found to be closely associated with an increase in the expression of the BH3-proteins, Bax and Bak. This finding, along with the observation that shear-stress dependent PS exposure occurred even in the absence of extracellular calcium led us to examine the role of Bax and Bak. However, shear stress-induced PS exposure was unaffected in Bax/Bak null platelets. In contrast, both shear stress-induced PS exposure and integrin αIIbβ3 cleavage were markedly blunted in CypD null platelets. Furthermore, shear stress induced-PS exposure was closely associated with loss of mitochondrial transmembrane potential, together indicating the importance of mPTP formation in the regulation of PS exposure in high shear stress conditions. These data identify a novel VWF- and CypD-dependent pathway that results in rapid PS exposure and integrin αIIbβ3 cleavage in high-shear stress conditions. This shear stress-initiated pathway of PS exposure, distinct from thrombin-collagen initiated PS exposure, does not require extracellular calcium and is not associated with P-selectin expression. Disclosures: Jobe: Baxter: Membership on an entity's Board of Directors or advisory committees.

Absolute hypoxic exercise training enhances in vitro thrombin generation by increasing procoagulant platelet-derived microparticles under high shear stress in sedentary men

2013 ◽  
Vol 124 (10) ◽  
pp. 639-649 ◽  
Author(s):  
Yu-Wen Chen ◽  
Yi-Ching Chen ◽  
Jong-Shyan Wang
Keyword(s):  
Shear Stress ◽  
Exercise Training ◽  
Thrombin Generation ◽  
Coagulation Factor ◽  
Strenuous Exercise ◽  
Factor V ◽  
High Shear ◽  
High Shear Stress ◽  
Vigorous Exercise

HS (high shear) stress associated with artery stenosis facilitates TG (thrombin generation) by increasing the release of procoagulant PDMPs (platelet-derived microparticles). Physical exercise and hypoxia may paradoxically modulate vascular thrombotic risks. The aim of the present study was to investigate how exercise training with/without hypoxia affected TG mediated by PDMPs under physio-pathological shear flows. A total of 75 sedentary males were randomly divided into five groups (n=15 in each group): 21% O2 [NC (normoxic control)] or 15% O2 [HC (hypoxic control)] at rest or were trained at 50% of peak work rate under 21% O2 [NT (normoxic training)] or 15% O2 [HAT (hypoxic-absolute training)], or 50% of HR (heart rate) reserve under 15% O2 [HRT (hypoxic-relative training)] for 30 min/day, 5 days/week for 4 weeks. The PDMP characteristics and dynamic TG were measured by flow cytometry and thrombinography respectively. Before the intervention, strenuous exercise markedly increased the PDMP count (14.8%) and TG rate (19.5%) in PDMP-rich plasma at 100 dynes/cm2 of shear stress (P<0.05). After the interventions, both NT and HRT significantly attenuated the enhancement of HS-induced PDMPs (4.7 and 4.9%) and TG rate (3.8 and 3.0%) (P<0.05) by severe exercise. Conversely, HAT notably promoted the PDMP count (37.3%) and TG rate (38.9%) induced by HS (P<0.05), concurrent with increasing plasma TF (tissue factor) and coagulation factor V levels at rest or following exercise. We conclude that both HRT and NT depress similarly HS-mediated TG during exercise, but HAT accelerates the prothrombotic response to vigorous exercise. These findings provide new insights into how exercise training under a hypoxic condition influences the risk of thrombosis associated with stenotic arteries.

Genomic analysis of immediate/early response to shear stress in human coronary artery endothelial cells

2002 ◽  
Vol 12 (1) ◽  
pp. 25-33 ◽  
Author(s):  
D. G. Peters ◽  
X.-C. Zhang ◽  
P. V. Benos ◽  
E. Heidrich-O’Hare ◽  
R. E. Ferrell
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Coronary Artery ◽  
Expression Profiles ◽  
Primary Cultures ◽  
Cdna Microarrays ◽  
Immediate Early ◽  
Laminar Shear Stress ◽  
Human Coronary Artery

The involvement of shear stress in the pathogenesis of vascular disease has motivated efforts to define the endothelial cell response to applied shear stress in vitro. A central question has been the mechanisms by which endothelial cells perceive and respond to changes in fluid flow. We have utilized cDNA microarrays to characterize the immediate/early genomic response to applied laminar shear stress (LSS) in primary cultures of human coronary artery endothelial cells (HCAECs). Cells were exposed, in a parallel plate flow chamber, to 0, 15, or 45 dyn/cm2 LSS for 1 h, and gene expression profiles were determined using human GEM1 cDNA microarrays. We find that a high proportion of LSS-responsive genes are transcription factors, and these are related by their involvement in growth arrest. These likely play a central role in the reprogramming of endothelial homeostasis following the switch from a static to a shear-stressed environment. LSS-responsive genes were also found to encode factors involved in vasoreactivity, signal transduction, antioxidants, cell cycle-associated genes, and markers of cytoskeletal function and dynamics.

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