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Gary E Gilbert - One of the best experts on this subject based on the ideXlab platform.
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Lactadherin Inhibits Secretory Phospholipase A2 Activity on Pre-Apoptotic Leukemia Cells
PloS one, 2013Co-Authors: Steffen Nyegaard, Jan T Rasmussen, Valerie A. Novakovic, Gary E GilbertAbstract:Secretory phospholipase A2 (sPLA2) is a critical component of insect and snake venoms and is secreted by mammalian leukocytes during inflammation. Elevated secretory PLA2 concentrations are associated with autoimmune diseases and septic shock. Many sPLA2’s do not bind to plasma membranes of quiescent cells but bind and digest phospholipids on the membranes of stimulated or apoptotic cells. The capacity of these phospholipases to digest membranes of stimulated or apoptotic cells correlates to the exposure of phosphatidylserine. In the present study, the ability of the phosphatidyl-L-serine-binding protein, Lactadherin to inhibit phospholipase enzyme activity has been assessed. Inhibition of human secretory phospholipase A2-V on phospholipid vesicles exceeded 90%, whereas inhibition of Naja mossambica sPLA2 plateaued at 50–60%. Lactadherin inhibited 45% of activity of Naja mossambica sPLA2 and >70% of human secretory phospholipase A2-V on the membranes of human NB4 leukemia cells treated with calcium ionophore A23187. The data indicate that Lactadherin may decrease inflammation by inhibiting sPLA2.
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Putative Phospholipid “scramblase” of Scott Syndrome, TMEM16F/Ano6, Mediates Phosphatidylserine Exposure On Filopodia and Cell Margins of Viable Endothelial Cells.
Blood, 2012Co-Authors: Jialan Shi, Gary E GilbertAbstract:Abstract 2180 Background: The Scott Syndrome, a rare inherited bleeding disorder, is characterized by defective exposure of phosphatidylserine (PS) on stimulated platelets, resulting in decreased support for the prothrombinase and factor Xase complexes. Prior reports indicate delay of apoptosis-related PS exposure and decreased release of PS-rich membrane microparticles from platelets, red cells, and lymphocytes from Mrs. Scott9s blood. Recent reports indicate that TMEM16F/Ano6, an 8-transmembrane domain protein homologous with Cl− channels is defective in Mrs. Scott9s immortalized lymphocytes and defective in another proband with Scott Syndrome. Furthermore, a gain of function mutation in this protein imparts constitutive PS exposure to immortalized lymphocytic cells. However, prior studies do not indicate the extent to which TMEM16F participates in the regulated, reversible pathway of PS exposure vs. the pre-apoptotic PS exposure or whether endothelial cells are affected. We have recently observed that TNFα-treated endothelial cells support assembly of the prothrombinase complex on filopodia and membrane margins. The prothrombinase-supporting membrane sites are characterized by PS exposure and convex curvature. We asked whether TMEM16F contributes to the PS exposure that supports prothrombinase complex assembly on filopodia and membrane margins of stimulated endothelial cells. Methods: We utilized two polyclonal antibodies against TMEM16F peptides to localize protein expression in both resting and TNFα-treated Human Umbilical Vein Endothelial Cells (HUVECs) by confocal microscopy. TMEM16F localization was compared to PS exposure, detected by binding of fluorescein-labeled Lactadherin; also prothrombinase assembly, detected by binding of fluorescein-maleimide labeled factor Va and EGRck-biotin-Alexa 647-steptavidin labeled factor Xa. TMEM16F shRNA, delivered by lentivirus vectors, was utilized to knockdown TMEM16F expression on HUVECs while control HUVECs were treated with an empty vector or with GFP-containing lentivirus vector. Endothelial cell-supported prothrombinase activity was measured over HUVECs grown in microtiter wells. Results: HUVECs grew to confluent monolayers on gelatin-coated cover slips. Anti-TMEM16F antibody staining of fixed, permeabilized cells showed primary localization to the nucleus and perinuclear cytoplasm. Both TMEM16F antibodies also stained small regions of the cell margins and filopodia when HUVECs were treated with TNFα, 10 ng/ml, for 24 hours. Dim TMEM16F staining co-localized with Lactadherin staining, in these cells, demonstrating proximity of the protein to PS exposure. Quantitative analyses showed 57 ± 4% reduction of TEMEM16F, as judged by flow cytometry. Quantitation of TMEM16F staining of adherent cells indicated a reduction of 55 ± 5%. HUVECs bound factor Va, like Lactadherin, selectively on filopodia and fibrils near the retracted edges of endothelial cells. Factor Xa co-localized the sites of factor Va, indicating formation of prothrombinese complex assembly. However, The assembly of the prothrombinase complex on TNFα-treated HUVECs treated with TMEM16F shRNA, was decreased by 60 ± 5% as judged by quantitative confocal microscopy. Prothrombinase activity was reduced by 57 ± 3% on TNFα-treated HUVECs compared to control HUVECs. PS exposure was also delayed in pre-apoptotic HUVECS treated with 10 μM A23187. Conclusion: A fraction of TMEM16F is localized near, and linked to regulated PS exposure on stressed endothelial cells. Reduction of TMEM16F decreases PS exposure and focal procoagulant activity supported by these viable cells. Decreased TMEM16F also decreases the rate of pre-apoptotic PS exposure. Disclosures: Shi:Brigham and Women9s Hospital: Use of Lactadherin to detect phosphataidylserine, Use of Lactadherin to detect phosphataidylserine Patents & Royalties. Gilbert:Brigham and Women9s Hospital: Use of Lactadherin to detect phosphataidylserine, Use of Lactadherin to detect phosphataidylserine Patents & Royalties.
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putative phospholipid scramblase of scott syndrome tmem16f ano6 mediates phosphatidylserine exposure on filopodia and cell margins of viable endothelial cells
Blood, 2012Co-Authors: Jialan Shi, Gary E GilbertAbstract:Abstract 2180 Background: The Scott Syndrome, a rare inherited bleeding disorder, is characterized by defective exposure of phosphatidylserine (PS) on stimulated platelets, resulting in decreased support for the prothrombinase and factor Xase complexes. Prior reports indicate delay of apoptosis-related PS exposure and decreased release of PS-rich membrane microparticles from platelets, red cells, and lymphocytes from Mrs. Scott9s blood. Recent reports indicate that TMEM16F/Ano6, an 8-transmembrane domain protein homologous with Cl− channels is defective in Mrs. Scott9s immortalized lymphocytes and defective in another proband with Scott Syndrome. Furthermore, a gain of function mutation in this protein imparts constitutive PS exposure to immortalized lymphocytic cells. However, prior studies do not indicate the extent to which TMEM16F participates in the regulated, reversible pathway of PS exposure vs. the pre-apoptotic PS exposure or whether endothelial cells are affected. We have recently observed that TNFα-treated endothelial cells support assembly of the prothrombinase complex on filopodia and membrane margins. The prothrombinase-supporting membrane sites are characterized by PS exposure and convex curvature. We asked whether TMEM16F contributes to the PS exposure that supports prothrombinase complex assembly on filopodia and membrane margins of stimulated endothelial cells. Methods: We utilized two polyclonal antibodies against TMEM16F peptides to localize protein expression in both resting and TNFα-treated Human Umbilical Vein Endothelial Cells (HUVECs) by confocal microscopy. TMEM16F localization was compared to PS exposure, detected by binding of fluorescein-labeled Lactadherin; also prothrombinase assembly, detected by binding of fluorescein-maleimide labeled factor Va and EGRck-biotin-Alexa 647-steptavidin labeled factor Xa. TMEM16F shRNA, delivered by lentivirus vectors, was utilized to knockdown TMEM16F expression on HUVECs while control HUVECs were treated with an empty vector or with GFP-containing lentivirus vector. Endothelial cell-supported prothrombinase activity was measured over HUVECs grown in microtiter wells. Results: HUVECs grew to confluent monolayers on gelatin-coated cover slips. Anti-TMEM16F antibody staining of fixed, permeabilized cells showed primary localization to the nucleus and perinuclear cytoplasm. Both TMEM16F antibodies also stained small regions of the cell margins and filopodia when HUVECs were treated with TNFα, 10 ng/ml, for 24 hours. Dim TMEM16F staining co-localized with Lactadherin staining, in these cells, demonstrating proximity of the protein to PS exposure. Quantitative analyses showed 57 ± 4% reduction of TEMEM16F, as judged by flow cytometry. Quantitation of TMEM16F staining of adherent cells indicated a reduction of 55 ± 5%. HUVECs bound factor Va, like Lactadherin, selectively on filopodia and fibrils near the retracted edges of endothelial cells. Factor Xa co-localized the sites of factor Va, indicating formation of prothrombinese complex assembly. However, The assembly of the prothrombinase complex on TNFα-treated HUVECs treated with TMEM16F shRNA, was decreased by 60 ± 5% as judged by quantitative confocal microscopy. Prothrombinase activity was reduced by 57 ± 3% on TNFα-treated HUVECs compared to control HUVECs. PS exposure was also delayed in pre-apoptotic HUVECS treated with 10 μM A23187. Conclusion: A fraction of TMEM16F is localized near, and linked to regulated PS exposure on stressed endothelial cells. Reduction of TMEM16F decreases PS exposure and focal procoagulant activity supported by these viable cells. Decreased TMEM16F also decreases the rate of pre-apoptotic PS exposure. Disclosures: Shi:Brigham and Women9s Hospital: Use of Lactadherin to detect phosphataidylserine, Use of Lactadherin to detect phosphataidylserine Patents & Royalties. Gilbert:Brigham and Women9s Hospital: Use of Lactadherin to detect phosphataidylserine, Use of Lactadherin to detect phosphataidylserine Patents & Royalties.
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Lactadherin C2 Domain Exhibits Ptd-L-Ser Specificity and Anticoagulant Properties Distinct From Homologous Factor VIII C2 Domain and Full-Length Lactadherin
Blood, 2012Co-Authors: Valerie A. Novakovic, Jialan Shi, Eugene R Gilbert, Gary E GilbertAbstract:Abstract 1105 Background: Lactadherin (aka mfg-e8) is a milk-fat globule membrane protein with a domain structure of EGF1-EGF2-C1-C2, where the lectin-like C1 and C2 domains are homologous to the membrane binding domains of factor VIII and factor V. Like factor VIII and factor V, Lactadherin exhibits calcium-independent membrane binding that is selective for phosphatidyl-L-serine (Ptd-L-Ser). Lactadherin also binds preferentially to convex membranes, competes efficiently for binding sites of factor VIII and factor V, and can function as an anticoagulant via competition for these binding sites. On stressed endothelial cells Lactadherin binds to filopodia and the cell margins, identifying sites that have exposed Ptd-L-Ser and support assembly of the prothrombinase complex. The crystallographic structure of the Lactadherin C2 domain (Lact-C2) and structure-function studies have shown that membrane binding is mediated by a longer β-hairpin turn, with different residues than fVIII-C2 and fV-C2. Further, we have shown that Lact-C2 maintains specificity for phosphatidylserine, in contrast to fVIII-C2, and that fluorescent fusion proteins containing Lact-C2 can be used as intracellular phosphatidylserine probes (Yeung et al. Science 2008;319:210). However, the extent to which Lact-C2 retains the membrane binding and anticoagulant properties of full-length Lactadherin, has not been studied. Methods: Lact-C2 was produced in E. coliand purified by metal ion chromatography followed by gel filtration. Competition experiments were performed by flow cytometry using phospholipid bilayers supported by glass microspheres to determine Lact-C29s ability to block binding sites of FITC-labeled Lactadherin, or fluorescein-labeled factor VIII and factor V. Lact-C2 was also labeled with FITC to measure its binding to sonicated or 100 nm diameter, extruded vesicles with varying PS content in order to assess Ptd-L-Ser selectivity and membrane curvature sensitivity. Two-step amidolytic factor Xase and prothrombinase assays were used to assess the ability of Lact-C2 to block activity. Fluorescence microscopy experiments were used to compare the binding of Alexa 647-labeled Lact-C2 vs. FITC-labeled Lactadherin on staurosphorine-treated HeLa cells. Results: Lact-C2 showed stereospecific binding to Ptd-L-Ser vs. Ptd-D-Ser in vesicles of 4% and 10% PS. Lact-C2 was sensitive to vesicle curvature, detecting as little as 1% Ptd-L-Ser on sonicated vesicles but requiring 4% Ptd-L-Ser on extruded vesicles. Lact-C2 competed for 89% of Lactadherin binding sites and 84% of factor VIII binding sites. Inhibition of factor Xase activity plateaued at 89% reduction vs. >99% reduction for Lactadherin. Lact-C2 also competed for 61% of factor V binding sites corresponding to an 82% reduction in prothrombinase activity. We are currently comparing the distribution of binding sites for Lact-C2 vs. Lactadherin on stressed HeLa cells, with preliminary data showing distinct, but overlapping, binding site distribution. Discussion: Lact-C2 exhibits stereospecific Ptd-L-Ser binding and convex curvature preference similar to full-length Lactadherin. Lact-C2 contrasts with fVIII-C2 in Ptd-L-Ser specificity and capacity to compete with factor VIII and inhibit factor Xase activity and prothrombinase activity. These results provide a framework for interpreting experiments in which Lact-C2 is used as an anticoagulant or as a calcium-independent probe for exposed membrane Ptd-L-Ser. Lact-C2 is able to bind to only a subset of Lactadherin binding sites, highlighting the importance of the Lactadherin C1 domain for high affinity binding and underscoring the largely unappreciated complexity of phospholipid membrane binding sites. Disclosures: Shi:Brigham and Women9s Hospital: Use of Lactadherin to detect phosphataidylserine, Use of Lactadherin to detect phosphataidylserine Patents & Royalties.
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Phagocytosis by macrophages and endothelial cells inhibits procoagulant and fibrinolytic activity of acute promyelocytic leukemia cells
Blood, 2011Co-Authors: R. Xie, Gary E Gilbert, Jin Zhou, Chunyan Gao, Valerie A. Novakovic, Jiuxin Zhu, Jing Wang, Jialan ShiAbstract:The coagulopathy of acute promyelocytic leukemia (APL) is mainly related to procoagulant substances and fibrinolytic activators of APL blasts, but the fate of these leukemic cells is unknown. The aim of this study was to investigate the removal of APL blasts by macrophages and endothelial cells in vitro and consequent procoagulant and fibrinolytic activity of APL cells. We found that human umbilical vein endothelial cells as well as THP-1 and monocyte-derived macrophages bound, engulfed, and subsequently degraded immortalized APL cell line NB4 and primary APL cells. Lactadherin promoted phagocytosis of APL cells in a time-dependent fashion. Furthermore, factor Xa and prothrombinase activity of phosphatidylserine-exposed target APL cells was time-dependently decreased after incubation with phagocytes (THP-1-derived macrophages or HUVECs). Thrombin production on target APL cells was reduced by 40%-45% after 2 hours of coincubation with phagocytes and 80% by a combination of Lactadherin and phagocytes. Moreover, plasmin generation of target APL cells was inhibited 30% by 2 hours of phagocytosis and ∼ 50% by Lactadherin-mediated engulfment. These results suggest that engulfment by macrophages and endothelial cells reduce procoagulant and fibrinolytic activity of APL blasts. Lactadherin and phagocytosis could cooperatively ameliorate the clotting disorders in APL.
Jan T Rasmussen - One of the best experts on this subject based on the ideXlab platform.
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Lactadherin orthologs inhibit migration of human, porcine and murine intestinal epithelial cells.
Food science & nutrition, 2017Co-Authors: Steffen Nyegaard, Trine Andreasen, Jan T RasmussenAbstract:Lactadherin was originally described due to its appearance in milk, but is abundantly expressed especially by professional and nonprofessional phagocytes. The proteins has been shown to have a multitude of bioactive effects, including inhibition of inflammatory phospholipases, induction of effero- and phagocytosis, prevent rotavirus induced gastroenteritis, and modulate intestinal homeostasis by regulating epithelial cell migration. The level of expression seems to be important in a row of serious pathologies linked to the intestinal epithelial barrier function, vascular- and autoimmune disease. This study examines the ability of Lactadherin to modulate migration of intestinal epithelium. A cell exclusion assay is used to quantify the ability of human, bovine and murine Lactadherin orthologs to affect migration of primary small intestine epithelium cells. Previous reports show that recombinant murine Lactadherin stimulate rat small intestine cell migration. The present study could not confirm this. Conversely, 10 μg/ml Lactadherin inhibits migration. Therefore, as Lactadherins enteroprotective properties is well established using in vivo models we conclude that the protective effects are linked to Lactadherins ability operate as an opsonin, or other modulating effects, and not a direct Lactadherin-cell induction of migration. Thus, the molecular mechanism behind the enteroprotective role of Lactadherin remains to be established.
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MFG-E8 as a Marker for Apoptotic, Stressed and Activated Cells
MFG-E8 and Inflammation, 2014Co-Authors: Kristine Blans, Jan T RasmussenAbstract:Milk fat globule-epidermal growth factor-factor 8 (MFG-E8)/Lactadherin’s ability to specifically recognize phosphatidylserine (PS) in membranes has been recognized as an excellent tool in a variety of scientific and clinical contexts. An asymmetric pattern of phospholipids across cellular membranes in eukaryotes is a fundamental property in maintaining normal cell function. However, randomization of phospholipids is an equally important event when cells are activated leading to exposure of the otherwise hidden PS crucial in orchestrating downstream events in apoptosis and coagulation. Lactadherin has in recent years been recognized as a sensitive PS binding protein for visualizing apoptosis and as an anticoagulant. Compared to the benchmark PS-probe, annexin V, Lactadherin seems to be superior in several PS binding properties. Numerous studies show the usefulness of Lactadherin in monitoring cell health in vitro and in vivo, in detecting cell-derived PS exposing microparticles, or for exploring mechanisms in apoptosis. Moreover, radio-labeled Lactadherin has been proposed as a non-invasive marker in the clinic for imaging of apoptotic events. Lactadherins PS recognition owes to the proteins C-domains, and has been used in recombinant exosome engineering in addressing proteins of interest to surfaces of nano-membrane particles. This chapter outlines the use of Lactadherin as a PS binding protein, based on several publications where many of these are conducted in collaboration with us, and reflects our experimental experiences with the protein over several years.
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Lactadherin Inhibits Secretory Phospholipase A2 Activity on Pre-Apoptotic Leukemia Cells
PloS one, 2013Co-Authors: Steffen Nyegaard, Jan T Rasmussen, Valerie A. Novakovic, Gary E GilbertAbstract:Secretory phospholipase A2 (sPLA2) is a critical component of insect and snake venoms and is secreted by mammalian leukocytes during inflammation. Elevated secretory PLA2 concentrations are associated with autoimmune diseases and septic shock. Many sPLA2’s do not bind to plasma membranes of quiescent cells but bind and digest phospholipids on the membranes of stimulated or apoptotic cells. The capacity of these phospholipases to digest membranes of stimulated or apoptotic cells correlates to the exposure of phosphatidylserine. In the present study, the ability of the phosphatidyl-L-serine-binding protein, Lactadherin to inhibit phospholipase enzyme activity has been assessed. Inhibition of human secretory phospholipase A2-V on phospholipid vesicles exceeded 90%, whereas inhibition of Naja mossambica sPLA2 plateaued at 50–60%. Lactadherin inhibited 45% of activity of Naja mossambica sPLA2 and >70% of human secretory phospholipase A2-V on the membranes of human NB4 leukemia cells treated with calcium ionophore A23187. The data indicate that Lactadherin may decrease inflammation by inhibiting sPLA2.
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Imaging the myocardium at risk with 99mTc-Lactadherin administered after reperfusion in a porcine model
Nuclear medicine and biology, 2013Co-Authors: Runa Hyldgaard Poulsen, Jan T Rasmussen, Christian W. Heegaard, Lise Falborg, Hans Erik Bøtker, Lasse S. Waehrens, Michael RehlingAbstract:Abstract Introduction Phosphatidylserine is translocated from the inner to the outer leaflet of the plasma membrane in the early stages of apoptosis and necrosis and in reversibly injured cells. In rabbit hearts, ischemia followed by reperfusion results in exposure of phosphatidylserine on myocytes unaffected by apoptosis or necrosis. Lactadherin was recently introduced as a highly sensitive phosphatidylserine ligand. We hypothesized that ischemic myocardial cell damage can be identified by radio-labeled Lactadherin and that the ischemic area at risk (AAR) can be visualized retrospectively after reperfusion. Methods Left anterior descending coronary artery in pigs was occluded for 20 minutes, 45 minutes or 45 minutes preceded by ischemic preconditioning. In all three groups, 99m Tc-Lactadherin was injected intravenously 30 minutes after reperfusion. The AAR was demarcated by Evans blue and the infarct size by 2,3,5,-triphenyltetrazodium chloride staining. Results The regional myocardial uptake of 99m Tc-Lactadherin closely correlated with the AAR (r = .83, P = .001). The area of 99m Tc–Lactadherin uptake was unaltered by a shorter duration of ischemia and ischemic preconditioning (P = .23) despite significantly different infarct development (P = .001). Conclusion The results suggest that 99m Tc–Lactadherin can be used as a sensitive marker for AAR imaging when injected 30 minutes after reperfusion following acute ischemia.
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Pharmacokinetics of the phosphatidylserine tracers 99mTc-Lactadherin and 99mTc-annexin V in pigs.
EJNMMI research, 2013Co-Authors: Runa H Poulsen, Jan T Rasmussen, Christian W. Heegaard, June A Ejlersen, Christian Flø, Lise Falborg, Michael RehlingAbstract:Phosphatidylserine (PS) is a phospholipid normally located in the inner leaflet of the cell membrane. PS is translocated from the inner to the outer leaflet of the plasma membrane during the early stages of apoptosis and in necrosis. In cell and animal studies, reversible PS externalisation to the outer membrane leaflet has been observed in viable cells. Hence, PS markers have been proposed as markers of both reversibly and irreversibly damaged cells. The purpose of this experimental study in pigs was to investigate the kinetics of the newly introduced PS marker technetium-99m-labelled Lactadherin (99mTc-Lactadherin) in comparison with the well-known PS tracer 99mTc-annexin V with special reference to the renal handling of the tracers. The effective dose for humans was estimated from the biodistribution in 24 mice. Nine anaesthetised pigs randomly allocated into two treatment groups were administered a single injection of either 99mTc-Lactadherin or 99mTc-annexin V. Renal perfusion was assessed by simultaneous injection of 51Cr-EDTA. Throughout the examinations, planar, dynamic scintigraphy of the trunk was performed, urine was collected and arterial and renal vein blood was sampled. The effective dose was estimated using the adult male phantom from the RADAR website. 99mTc-Lactadherin was cleared four times faster from plasma than 99mTc-annexin V, 57 ± 13 ml/min (mean ± SD) versus 14 ± 2 ml/min. 99mTc-Lactadherin had a predominant uptake in the liver, whereas 99mTc-annexin V was primarily taken up by the kidneys. The estimated effective human dose after single injection of 99mTc-Lactadherin and 99mTc-annexin V was 5.8 and 11 μSv/MBq, respectively. The high hepatic uptake of 99mTc-Lactadherin compromises the use of 99mTc-Lactadherin for imaging PS externalisation in the liver. Due to scatter from the liver, the use of in vivo visualisation of PS externalisation in the lower thorax and upper abdomen by 99mTc-Lactadherin is challenged, but not precluded. In contrast to 99mTc-annexin, 99mTc-Lactadherin has a low renal uptake and may be the preferred tracer for imaging PS externalisation in the kidneys. The effective dose after injection of 99mTc-Lactadherin and 99mTc-annexin was low. Recommendations regarding the clinical use of 99mTc-Lactadherin must await tracer kinetic studies in patients.
Perumal Thiagarajan - One of the best experts on this subject based on the ideXlab platform.
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PLATELETS AND THROMBOPOIESIS Lactadherin and clearance of platelet-derived microvesicles
2016Co-Authors: Swapan K Dasgupta, Polly A Niravath, Ricardo V Bellera, Shigekazu Nagata, Hanan Abdel-monem, Kimberly Langlois, O E. Rumbaut, Perumal ThiagarajanAbstract:The transbilayer movement of phospha-tidylserine from the inner to the outer leaflet of the membrane bilayer dur-ing platelet activation is associated with the release of procoagulant phosphatidylserine-rich small mem-brane vesicles called platelet-derived microvesicles. We tested the effect of Lactadherin, which promotes the phagocytosis of phosphatidylserine-expressing lymphocytes and red blood cells, in the clearance of platelet mi-crovesicles. Platelet-derived micro-vesicles were labeled with BODIPY-maleimide and incubated with THP-1– derived macrophages. The extent of phagocytosis was quantified by flow cytometry. Lactadherin promoted phago-cytosis in a concentration-dependent manner with a half-maximal effect at approximately 5 ng/mL. Lactadherin-deficient mice had increased number of platelet-derived microvesicles in their plasma compared with their wild-type littermates (950 165 vs 4760 650; P .02) and generated 2-fold more thrombin. In addition, splenic macro-phages from Lactadherin-deficient mice showed decreased capacity to phagocy-tose platelet-derived microvesicles. In an in vivo model of light/dye-induced endothelial injury/thrombosis in the cremasteric venules, Lactadherin-deficient mice had significantly shorter time for occlusion compared with their wild-type littermate controls (5.93 0.43 minutes vs 9.80 1.14 min-utes;P .01). These studies show that Lactadherin mediates the clearance of phosphatidylserine-expressing platelet-derived microvesicles from the circula-tion and that a defective clearance can induce a hypercoagulable state. (Blood. 2009;113:1332-1339
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Lactadherin and clearance of platelet derived microvesicles
Blood, 2009Co-Authors: Swapan K. Dasgupta, Hanan Abdelmonem, Polly A Niravath, Anhquyen Le, Ricardo V Bellera, Kimberly W Langlois, Rolando E Rumbaut, Shigekazu Nagata, Perumal ThiagarajanAbstract:The transbilayer movement of phosphatidylserine from the inner to the outer leaflet of the membrane bilayer during platelet activation is associated with the release of procoagulant phosphatidylserine-rich small membrane vesicles called platelet-derived microvesicles. We tested the effect of Lactadherin, which promotes the phagocytosis of phosphatidylserine-expressing lymphocytes and red blood cells, in the clearance of platelet microvesicles. Platelet-derived microvesicles were labeled with BODIPY-maleimide and incubated with THP-1–derived macrophages. The extent of phagocytosis was quantified by flow cytometry. Lactadherin promoted phagocytosis in a concentration-dependent manner with a half-maximal effect at approximately 5 ng/mL. Lactadherin-deficient mice had increased number of platelet-derived microvesicles in their plasma compared with their wild-type littermates (950 ± 165 vs 4760 ± 650; P = .02) and generated 2-fold more thrombin. In addition, splenic macrophages from Lactadherin-deficient mice showed decreased capacity to phagocytose platelet-derived microvesicles. In an in vivo model of light/dye-induced endothelial injury/thrombosis in the cremasteric venules, Lactadherin-deficient mice had significantly shorter time for occlusion compared with their wild-type littermate controls (5.93 ± 0.43 minutes vs 9.80 ± 1.14 minutes;P = .01). These studies show that Lactadherin mediates the clearance of phosphatidylserine-expressing platelet-derived microvesicles from the circulation and that a defective clearance can induce a hypercoagulable state.
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Lactadherin and Clearance of Platelet-Derived Microvesicles.
Blood, 2008Co-Authors: Swapan K. Dasgupta, Polly A Niravath, Ricardo V Bellera, Rolando E Rumbaut, Shigekazu Nagata, Hanan Abdel-monem, Kimberly Langlois, Perumal ThiagarajanAbstract:Abstract Objective— In platelets, as in most mammalian cells, the anionic phospholipids such as phosphatidylserine are present only in the inner leaflet of the membrane bilayer. During platelet activation, phosphatidylserine moves from the inner to the outer leaflet of the membrane bilayer. The transbilayer movement of phosphatidylserine is responsible for platelet procoagulant activity as the exposed phosphatidylserine provides high affinity binding sites for the assembly of the prothrombinase and tenase complex. Externalization of anionic phospholipids in platelet is accompanied by the release of phosphatidylserine-rich microvesicles. These microvesicles account for the procoagulant activity of plasma by providing an efficient catalytic surface. Lactadherin, also known milk fat globule-EGF 8, is a 45 kDa glycoprotein secreted by macrophages. Lactadherin contains EGF-like domains at the amino terminus and two C-domains at the carboxy terminus that share homology to the phosphatidylserinebinding domains of blood coagulation factors V and VIII. Lactadherin binds to apoptotic lymphocytes and phosphatidylserine-expressing red blood cells via the C-domains and anchors them to macrophage integrins via its RGD sequence in the EGF domain. We have examined the role of Lactadherin in clearance of phosphatidylserine-rich platelet-derived microvesicles. Methods and Results—Platelet-derived microvesicles were labeled with the fluorophore BODIPY-maleimide and incubated with THP-1 cell derived macrophages. The extent of phagocytosis was quantified by measuring the intracellular fluorescence by flow cytometry. Lactadherin promoted phagocytosis in a concentration-dependent manner with a half-maximal effect at ~ 5 ng/ml. A monoclonal antibody to Lactadherin and a carboxy terminal fragment of Lactadherin inhibited Lactadherin-dependent phagocytosis. Lactadherin-deficient mice had increased number of microvesicles in their plasma and generated more thrombin compared to their wild type littermates. In addition, splenic macrophages from Lactadherin-deficient mice showed decreased capacity to phagocytose platelet microvesicles. Finally, in a in vivo model of light/dye-induced endothelial injury/ thrombosis model, Lactadherin-deficient mice, showed enhanced thrombus formation (5.93 ± 0.43 min) compared to their wild-type littermates ( 9.80 ± 1.14 min; P=0.01, n=9 in each group) in the cremastric venules. Conclusion— Our studies show that Lactadherin mediates the clearance of PS expressing platelet-derived microvesicles from the circulation and that a defective clearance can induce a hypercoagulable state.
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Role of Lactadherin in the clearance of phosphatidylserine-expressing red blood cells.
Transfusion, 2008Co-Authors: Swapan K. Dasgupta, Shigekazu Nagata, Hanan Abdel-monem, Prasenjit Guchhait, Perumal ThiagarajanAbstract:BACKGROUND: In red blood cells (RBCs) anionic phospholipids, such as phosphatidylserine, are present in the inner leaflet of the membrane bilayer. Exposure of phosphatidylserine occurs during senescence and during long-term storage of RBCs and is considered as the tag for removal from the circulation by macrophages. Lactadherin is a phosphatidylserine-binding glycoprotein secreted by macrophages that promotes the engulfment of phosphatidylserine-expressing apoptotic lymphocytes. This study investigates the role of Lactadherin in the phagocytosis of phosphatidylserine-expressing RBCs. STUDY DESIGN AND METHODS: Transbilayer movement of phosphatidylserine was induced in RBCs either by storage beyond 30 days or by treatment with calcium ionophore A23187 and N-ethylmaleimide. Phosphatidylserine-expressing RBCs were incubated with phorbol ester–stimulated THP-1, and phagocytosis was determined by measuring the pseudoperoxidase activity of hemoglobin. The in vivo clearance of phosphatidylserine-enriched RBCs was measured in Lactadherin-deficient mice and in their littermate controls. RESULTS: Lactadherin promoted phagocytosis of phosphatidylserine-expressing RBCs by macrophages in a concentration-dependent manner. Splenic macrophages from Lactadherin-deficient mice had diminished capacity to phagocytose phosphatidylserine-expressing RBCs. The life span of RBCs in Lactadherin-deficient mice was similar to wild-type littermate controls in vivo. However, when an excess of phosphatidylserine-expressing RBCs were infused, there was only a mild impairment in the clearance in Lactadherin-deficient mice compared to wild-type littermate controls. CONCLUSION: These results show that clearance of phosphatidylserine-expressing RBCs is not diminished in a significant way in Lactadherin-deficient mice under physiologic conditions and suggest the presence of redundant pathways.
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Lactadherin mediates sickle cell adhesion to vascular endothelial cells in flowing blood
Haematologica, 2007Co-Authors: Prasenjit Guchhait, Swapan K Dasgupta, Sarvari Venkata Yellapragada, José A. López, Perumal ThiagarajanAbstract:Increased exposure of sickle red blood cells to phosphatidylserine promotes its adhesion to the endothelium. A monoclonal antibody to Lactadherin, a phosphatidylserine binding protein, inhibits sickle cell adhesion to histamine-stimulated endothelial cells in flowing blood. Added Lactadherin enhances the adhesion via the integrin αVβ3. These results indicate that Lactadherin can mediate phosphatidyl-serine-expressing sickle cell adhesion to the endothelium.
Jialan Shi - One of the best experts on this subject based on the ideXlab platform.
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The Exposure of Phosphatidylserine Influences Procoagulant Activity in Retinal Vein Occlusion by Microparticles, Blood Cells, and Endothelium
Hindawi Limited, 2018Co-Authors: Xueqing Deng, Zengxiang Dong, Feng Wang, Jialan ShiAbstract:The pathogenesis of hypercoagulability in retinal vein occlusion (RVO) is largely unknown. Whether the exposure of phosphatidylserine (PS) and microparticle (MPs) release will affect procoagulant activity (PCA) in RVO needs to be investigated. Objectives. To evaluate PS expression, circulating MPs, and the corresponding PCA in RVO patients. Twenty-five RVO patients were compared with 25 controls. PS-positive cells were detected by flow cytometry. Cell-specific MPs were measured by Lactadherin for PS and relevant CD antibody. We explored PCA with coagulation time, purified coagulation complex assays, and fibrin production assays. In RVO, MPs from platelets, erythrocytes, leukocyte, and endothelial cells were increased and the exposure of PS was elevated significantly when compared with controls. In addition, we showed that circulating MPs in RVO patients were mostly derived from platelets, representing about 60–70% of all MPs, followed by erythrocytes and leukocytes. Moreover, PS exposure, ECs, and MPs in RVO lead to shortened clotting time with upregulation of FXa and thrombin formation obviously. Importantly, ECs treated with RVO serum which bounded FVa and FXa explicitly suggested the damage of retinal vein endothelial cells. Furthermore, Lactadherin can inhibit the combination between PS and coagulation factors by approximately 70% and then exert an anticoagulant effect. In summary, circulating MPs and exposed PS from different cells may contribute to the increased PCA in patients with RVO. Lactadherin can be used for PS detection and an anticoagulant agent
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Indolic Uremic Solutes Enhance Procoagulant Activity of Red Blood Cells through Phosphatidylserine Exposure and Microparticle Release
MDPI AG, 2015Co-Authors: Chunyan Gao, Weijun Dong, Wen Song, Debin Cui, Jialan ShiAbstract:Increased accumulation of indolic uremic solutes in the blood of uremic patients contributes to the risk of thrombotic events. Red blood cells (RBCs), the most abundant blood cells in circulation, may be a privileged target of these solutes. However, the effect of uremic solutes indoxyl sulfate (IS) and indole-3-acetic acid (IAA) on procoagulant activity (PCA) of erythrocyte is unclear. Here, RBCs from healthy adults were treated with IS and IAA (mean and maximal concentrations reported in uremic patients). Phosphatidylserine (PS) exposure of RBCs and their microparticles (MPs) release were labeled with Alexa Fluor 488-Lactadherin and detected by flow cytometer. Cytosolic Ca2+ ([Ca2+]) with Fluo 3/AM was analyzed by flow cytometer. PCA was assessed by clotting time and purified coagulation complex assays. We found that PS exposure, MPs generation, and consequent PCA of RBCs at mean concentrations of IS and IAA enhanced and peaked in maximal uremic concentrations. Moreover, 128 nM Lactadherin, a PS inhibitor, inhibited over 90% PCA of RBCs and RMPs. Eryptosis or damage, by indolic uremic solutes was due to, at least partially, the increase of cytosolic [Ca2+]. Our results suggest that RBC eryptosis in uremic solutes IS and IAA plays an important role in thrombus formation through releasing RMPs and exposing PS. Lactadherin acts as an efficient anticoagulant in this process
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Homocysteine induces procoagulant activity of red blood cells via phosphatidylserine exposure and microparticles generation.
Amino acids, 2014Co-Authors: R. Xie, Jialan Shi, De-xin Jia, Cunyan Gao, Jianhua Zhou, Hong Sui, Xiaoli Wei, Tingting Zhang, Yu Han, Yuxian BaiAbstract:Increased homocysteine (Hcy) levels in plasma correlate with the risk of thromboic events. Red blood cells (RBCs), the most abundant blood cells in circulation, also play an active role in the process of thrombus formation. However, the effect of Hcy on procoagulant activity (PCA) of RBCs is unclear. In the present study, RBCs from healthy adults were treated with Hcy (8, 20, 80, 200, 800 μmol/L) for 24 h. Phosphatidylserine (PS) exposure of RBCs and red blood cell-derived microparticles (RMPs) release were detected using Alexa Fluor 488-Lactadherin. PCA was assessed by coagulation time and purified clotting complexes testes. We found that Hcy treatment dose dependently enhanced PS exposure and consequent PCA of RBCs. Hcy also elevated the formation of procoagulant RMPs, with statistical significance at 800 μmol/L of Hcy. Moreover, 128 nmol/L Lactadherin inhibited about 90 % PCA of RBCs and RMPs. Our data suggest that PS exposure and RMPs shedding are key sources for Hcy-induced PCA of RBCs. Lactadherin could be used to modulate the anticoagulant and procoagulant balance in this process.
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Chemotherapy induces enhanced procoagulant activity through phosphatidylserine exposure in acute lymphoblastic leukemia.
Thrombosis research, 2013Co-Authors: Xiushuai Dong, Jin Zhou, Jialan Shi, Xiaomin Zhang, Xi Chen, Yinglan Jin, Haibin Dai, Jinghua WangAbstract:Abstract Introduction Thromboembolism is a serious complication in patients with acute lymphoblastic leukemia (ALL). Coagulation disorders can be induced and worsened by cytotoxic drugs; however, the mechanisms are largely unknown. Our study aims to investigate the effects of daunorubicin (DNR) and L-asparaginase (L-ASP) on phosphatidylserine (PS) exposure and the procoagulant activity (PCA) of Jurkat/ALL cells. The anticoagulant properties of Lactadherin were also explored. Materials and Methods Jurkat cells and cells from 10 newly diagnosed patients with ALL were treated with DNR or L-ASP. Flow cytometry and confocal microscopy were used to quantify and locate PS exposure, respectively. PCA was evaluated using coagulation assays and purified coagulation complex assays. Lactadherin, a glycoprotein of the milk fat globule membrane with stereospecific binding to phosphatidyl-L-serine, was used as a probe for the detection of exposed PS. Results Untreated Jurkat/ALL cells exhibited higher PS exposure and greater PCA than mononuclear cells (MNCs). The PCA of cells treated with DNR or L-ASP was markedly increased. Flow cytometry and confocal microscopy indicated that the increased PCA occurred in parallel with PS exposure. The blocking of PS with Lactadherin prolonged the coagulation time and inhibited approximately 85-90% of the activities of procoagulant enzyme complexes in Jurkat/ALL cells. Conclusions Our results indicate that DNR and L-ASP increased the PCA of Jurkat/ALL cells through PS exposure and played a critical role in inducing thrombosis in ALL patients. Lactadherin is an ideal probe for PS detection at an early stage and a potential anticoagulant to improve the hypercoagulability of ALL patients.
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Putative Phospholipid “scramblase” of Scott Syndrome, TMEM16F/Ano6, Mediates Phosphatidylserine Exposure On Filopodia and Cell Margins of Viable Endothelial Cells.
Blood, 2012Co-Authors: Jialan Shi, Gary E GilbertAbstract:Abstract 2180 Background: The Scott Syndrome, a rare inherited bleeding disorder, is characterized by defective exposure of phosphatidylserine (PS) on stimulated platelets, resulting in decreased support for the prothrombinase and factor Xase complexes. Prior reports indicate delay of apoptosis-related PS exposure and decreased release of PS-rich membrane microparticles from platelets, red cells, and lymphocytes from Mrs. Scott9s blood. Recent reports indicate that TMEM16F/Ano6, an 8-transmembrane domain protein homologous with Cl− channels is defective in Mrs. Scott9s immortalized lymphocytes and defective in another proband with Scott Syndrome. Furthermore, a gain of function mutation in this protein imparts constitutive PS exposure to immortalized lymphocytic cells. However, prior studies do not indicate the extent to which TMEM16F participates in the regulated, reversible pathway of PS exposure vs. the pre-apoptotic PS exposure or whether endothelial cells are affected. We have recently observed that TNFα-treated endothelial cells support assembly of the prothrombinase complex on filopodia and membrane margins. The prothrombinase-supporting membrane sites are characterized by PS exposure and convex curvature. We asked whether TMEM16F contributes to the PS exposure that supports prothrombinase complex assembly on filopodia and membrane margins of stimulated endothelial cells. Methods: We utilized two polyclonal antibodies against TMEM16F peptides to localize protein expression in both resting and TNFα-treated Human Umbilical Vein Endothelial Cells (HUVECs) by confocal microscopy. TMEM16F localization was compared to PS exposure, detected by binding of fluorescein-labeled Lactadherin; also prothrombinase assembly, detected by binding of fluorescein-maleimide labeled factor Va and EGRck-biotin-Alexa 647-steptavidin labeled factor Xa. TMEM16F shRNA, delivered by lentivirus vectors, was utilized to knockdown TMEM16F expression on HUVECs while control HUVECs were treated with an empty vector or with GFP-containing lentivirus vector. Endothelial cell-supported prothrombinase activity was measured over HUVECs grown in microtiter wells. Results: HUVECs grew to confluent monolayers on gelatin-coated cover slips. Anti-TMEM16F antibody staining of fixed, permeabilized cells showed primary localization to the nucleus and perinuclear cytoplasm. Both TMEM16F antibodies also stained small regions of the cell margins and filopodia when HUVECs were treated with TNFα, 10 ng/ml, for 24 hours. Dim TMEM16F staining co-localized with Lactadherin staining, in these cells, demonstrating proximity of the protein to PS exposure. Quantitative analyses showed 57 ± 4% reduction of TEMEM16F, as judged by flow cytometry. Quantitation of TMEM16F staining of adherent cells indicated a reduction of 55 ± 5%. HUVECs bound factor Va, like Lactadherin, selectively on filopodia and fibrils near the retracted edges of endothelial cells. Factor Xa co-localized the sites of factor Va, indicating formation of prothrombinese complex assembly. However, The assembly of the prothrombinase complex on TNFα-treated HUVECs treated with TMEM16F shRNA, was decreased by 60 ± 5% as judged by quantitative confocal microscopy. Prothrombinase activity was reduced by 57 ± 3% on TNFα-treated HUVECs compared to control HUVECs. PS exposure was also delayed in pre-apoptotic HUVECS treated with 10 μM A23187. Conclusion: A fraction of TMEM16F is localized near, and linked to regulated PS exposure on stressed endothelial cells. Reduction of TMEM16F decreases PS exposure and focal procoagulant activity supported by these viable cells. Decreased TMEM16F also decreases the rate of pre-apoptotic PS exposure. Disclosures: Shi:Brigham and Women9s Hospital: Use of Lactadherin to detect phosphataidylserine, Use of Lactadherin to detect phosphataidylserine Patents & Royalties. Gilbert:Brigham and Women9s Hospital: Use of Lactadherin to detect phosphataidylserine, Use of Lactadherin to detect phosphataidylserine Patents & Royalties.
Kentaro Otani - One of the best experts on this subject based on the ideXlab platform.
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Surface Modification with Lactadherin Augments the Attachment of Sonazoid Microbubbles to Glycoprotein IIb/IIIa.
Ultrasound in medicine & biology, 2019Co-Authors: Kentaro Otani, Atsunori Kamiya, Takahiro Miyazaki, Ayumi Koga, Ayako Inatomi, Mariko Harada-shibaAbstract:Arginine-glycine-aspartate (RGD)-carrying microbubbles (MBs) have been utilized as a specific contrast agent for glycoprotein IIb/IIIa (αIIbβ3 integrin)-expressing activated platelets in ultrasound molecular imaging. Recently, we found that surface modification with Lactadherin provides the RGD motif on the surface of phosphatidylserine-containing clinically available MBs, Sonazoid. Here, we examined the potential of Lactadherin-bearing Sonazoid MBs to be targeted MBs for glycoprotein IIb/IIIa using the custom-designed in vitro settings with recombinant αIIbβ3 integrin, activated platelets or erythrocyte-rich human clots. By modification of the surface with Lactadherin, a large number of Sonazoid MBs were attached to the αIIbβ3 integrin-coated and platelet-immobilized plate. Additionally, the video intensity of clots after incubation with Lactadherin-bearing Sonazoid MBs was significantly higher than that with unmodified Sonazoid MBs, implying the number of attached Sonazoid MBs was increased by the modification with Lactadherin. Our results suggest that the Lactadherin-bearing Sonazoid MBs have the potential to be thrombus-targeted MBs.
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surface modification with Lactadherin augments the attachment of sonazoid microbubbles to glycoprotein iib iiia
Ultrasound in Medicine and Biology, 2019Co-Authors: Kentaro Otani, Atsunori Kamiya, Takahiro Miyazaki, Ayumi Koga, Ayako Inatomi, Mariko HaradashibaAbstract:Arginine-glycine-aspartate (RGD)-carrying microbubbles (MBs) have been utilized as a specific contrast agent for glycoprotein IIb/IIIa (αIIbβ3 integrin)-expressing activated platelets in ultrasound molecular imaging. Recently, we found that surface modification with Lactadherin provides the RGD motif on the surface of phosphatidylserine-containing clinically available MBs, Sonazoid. Here, we examined the potential of Lactadherin-bearing Sonazoid MBs to be targeted MBs for glycoprotein IIb/IIIa using the custom-designed in vitro settings with recombinant αIIbβ3 integrin, activated platelets or erythrocyte-rich human clots. By modification of the surface with Lactadherin, a large number of Sonazoid MBs were attached to the αIIbβ3 integrin-coated and platelet-immobilized plate. Additionally, the video intensity of clots after incubation with Lactadherin-bearing Sonazoid MBs was significantly higher than that with unmodified Sonazoid MBs, implying the number of attached Sonazoid MBs was increased by the modification with Lactadherin. Our results suggest that the Lactadherin-bearing Sonazoid MBs have the potential to be thrombus-targeted MBs.
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Simplified Preparation of αvβ3 Integrin-Targeted Microbubbles Based on a Clinically Available Ultrasound Contrast Agent: Validation in a Tumor-Bearing Mouse Model.
Ultrasound in medicine & biology, 2018Co-Authors: Kentaro Otani, Hirohito Nishimura, Atsunori Kamiya, Mariko Harada-shibaAbstract:Abstract The usefulness of ultrasound molecular imaging with αvβ3 integrin-targeted microbubbles for detecting tumor angiogenesis has been demonstrated. Recently, we developed αvβ3 integrin-targeted microbubbles by modifying clinically available microbubbles (Sonazoid, Daiichi-Sankyo Pharmaceuticals, Tokyo, Japan) with a secreted glycoprotein (Lactadherin). The aims of our present study were to simplify the preparation of Lactadherin-bearing Sonazoid and to examine the diagnostic utility of Lactadherin-bearing Sonazoid for αvβ3 integrin-expressing tumor vessels by using SK-OV-3-tumor–bearing mice. By incubating 1.2 × 107 Sonazoid microbubbles with 1.0 µg Lactadherin, the complicated washing and centrifugation steps during the microbubble preparation could be omitted with no significant reduction in labeling ratio of Lactadherin-bearing Sonazoid. In addition, the number of Sonazoid microbubbles accumulated in the SK-OV-3 tumor was significantly increased by modifying Sonazoid with Lactadherin. Our data suggest that the Lactadherin-bearing Sonazoid is an easily prepared and potentially clinically translatable targeted microbubble for αvβ3 integrin-expressing vessels.
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Feasibility of Lactadherin-Bearing Clinically Available Microbubbles as Ultrasound Contrast Agent for Angiogenesis
Molecular Imaging and Biology, 2013Co-Authors: Kentaro Otani, Kenichi YamaharaAbstract:Objectives Phagocytosis of apoptotic cells is carried out through bridging of phosphatidylserine (PS)-expressing apoptotic cells and integrin αvβ3-expressing phagocytes with Lactadherin. The objective of this study was to examine whether microbubbles targeted to integrin αvβ3 could be produced by conjugating a PS-containing clinically available ultrasound contrast agent with Lactadherin. Materials and Methods PS-containing perfluorobutane-filled microbubbles were incubated with R-phycoerythrin (PE)-labeled Lactadherin, and the presence of PE-positive bubbles was examined by FACS analysis. Secondly, the attachment of Lactadherin to integrin αvβ3-expressing cells (human umbilical vein endothelial cells (HUVEC)) was also examined by FACS analysis. Finally, the adhesion of PS-containing bubbles to HUVEC was examined using a parallel plate flow chamber. The number of adherent bubbles with or without the intermediation of Lactadherin was compared. Results The more Lactadherin was added to the bubble suspension, the more PE-positive bubbles were detected. The size of bubbles was not increased even after conjugation with Lactadherin (2.90 ± 0.04 vs. 2.81 ± 0.02 μm). Binding between Lactadherin and HUVEC was also confirmed by FACS analysis. The parallel plate flow chamber study revealed that the number of PS-containing bubbles adherent to HUVEC was increased about five times by the intermediation of Lactadherin (12.1 ± 6.0 to 58.7 ± 33.1 bubbles). Conclusion Because integrin αvβ3 is well-known to play a key role in angiogenesis, the complex of PS-containing bubbles and Lactadherin has feasibility as a clinically translatable targeted ultrasound contrast agent for angiogenesis.
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Feasibility of Lactadherin-bearing clinically available microbubbles as ultrasound contrast agent for angiogenesis.
Molecular imaging and biology, 2013Co-Authors: Kentaro Otani, Kenichi YamaharaAbstract:Objectives Phagocytosis of apoptotic cells is carried out through bridging of phosphatidylserine (PS)-expressing apoptotic cells and integrin αvβ3-expressing phagocytes with Lactadherin. The objective of this study was to examine whether microbubbles targeted to integrin αvβ3 could be produced by conjugating a PS-containing clinically available ultrasound contrast agent with Lactadherin.
