Anti-platelet effects of epigallocatechin-3-gallate in addition to the concomitant aspirin, clopidogrel or ticagrelor treatment

BACKGROUND/AIMS: Although epigallocatechin-3-gallate (EGCG), which is found in high contents in the dried leaves of green tea, has been reported to have an anti-platelet effect, synergistic effects of EGCG in addition to current anti-platelet medications remains to be elucidated. METHODS: Blood samples were obtained from 40 participants who took aspirin (ASA, n = 10), clopidogrel (CPD, n = 10), ticagrelor (TCG, n = 10) and no anti-platelet medication (Control, n = 10). Ex vivo platelet aggregation and adhesion under various stimulators were analyzed by multiple electrode aggregometry (MEA) and Impact-R systems. PAC-1 and P-selectin expressions in human platelets were analyzed by flow cytometry. RESULTS: In MEA analysis, adenosine diphosphate (ADP) and thrombin receptor activating peptide (TRAP)-induced platelet aggregations were lower in the CPD and the TCG groups; arachidonic acid (AA)-induced platelet aggregation was lower in the ASA group, whereas collagen (COL)-induced platelet aggregations were comparable among four groups. EGCG significantly reduced ADP- and COL-induced platelet aggregation in dose-dependent manner (ADP, p = 0.04; COL, p < 0.01). There were no additional suppressions of platelet aggregation stimulated by AA in the ASA group, and by ADP in the CPD and TCG groups. Moreover, EGCG suppressed shear stress-induced platelet adhesion on Impact-R, and had no effect on P-selectin and PAC-1 expressions. CONCLUSIONS: Ex vivo treatment of EGCG inhibited platelet adhesion and aggregation without changes in P-selectin and PAC-1 expression. There was no additional suppressions in platelet aggregation stimulated by AA in the ASA group and ADP in the CPD and TCG groups.

Epithelial cell adhesion efficacy of a novel peptide identified by panning on a smooth titanium surface / 国际口腔科学杂志·英文版

Epithelial attachment via the basal lamina on the tooth surface provides an important structural defence mechanism against bacterial invasion in combating periodontal disease. However, when considering dental implants, strong epithelial attachment does not exist throughout the titanium-soft tissue interface, making soft tissues more susceptible to peri-implant disease. This study introduced a novel synthetic peptide (A10) to enhance epithelial attachment. A10 was identified from a bacterial peptide display library and synthesized. A10 and protease-activated receptor 4-activating peptide (PAR4-AP, positive control) were immobilized on commercially pure titanium. The peptide-treated titanium showed high epithelial cell migration ability during incubation in platelet-rich plasma. We confirmed the development of dense and expanded BL (stained by Ln5) with pericellular junctions (stained by ZO1) on the peptide-treated titanium surface. In an adhesion assay of epithelial cells on A10-treated titanium, PAR4-AP-treated titanium, bovine root and non-treated titanium, A10-treated titanium and PAR4-AP-treated titanium showed significantly stronger adhesion than non-treated titanium. PAR4-AP-treated titanium showed significantly higher inflammatory cytokine release than non-treated titanium. There was no significant difference in inflammatory cytokine release between A10-treated and non-treated titanium. These results indicated that A10 could induce the adhesion and migration of epithelial cells with low inflammatory cytokine release. This novel peptide has a potentially useful application that could improve clinical outcomes with titanium implants and abutments by reducing or preventing peri-implant disease.

Role of Coagulation Factor 2 Receptor during Respiratory Pneumococcal Infections

Coagulation factor 2 receptor (F2R), also well-known as a protease-activated receptor 1 (PAR1), is the first known thrombin receptor and plays a critical role in transmitting thrombin-mediated activation of intracellular signaling in many types of cells. It has been known that bacterial infections lead to activation of coagulation systems, and recent studies suggest that PAR1 may be critically involved not only in mediating bacteria-induced detrimental coagulation, but also in innate immune and inflammatory responses. Community-acquired pneumonia, which is frequently caused by Streptococcus pneumoniae (S. pneumoniae), is characterized as an intra-alveolar coagulation and an interstitial neutrophilic inflammation. Recently, the role of PAR1 in regulating pneumococcal infections has been proposed. However, the role of PAR1 in pneumococcal infections has not been clearly understood yet. In this review, recent findings on the role of PAR1 in pneumococcal infections and possible underlying molecular mechanisms by which S. pneumoniae regulates PAR1-mediated immune and inflammatory responses will be discussed.

Determinación de la fosfatasa ácida tartrato resistente en muestras óseas decalcificadas de cerdo Sus domesticus / Determining tartrate-resistant acid phosphatase in decalcified bone samples pig Sus domesticus

Introducción: Las técnicas de Inmuno - histoquímica son hoy en día una de las herramientas más importantes en el diag- nostico histopatológico, sin embargo la manipulación de las muestras y el método de procesamiento puede llevar a cambios en la estructura de las proteínas que llevan a enmascaramiento de antígenos, dificultan - do la identificación con anticuerpos. Entre los diferentes métodos de recuperación an- tigénico propuestos en la literatura, el de calor húmedo con Vaporera ha tenido gran aceptación por su simplicidad, control y bajo costo. Objetivo: En el presente trabajo se propone un protocolo de recuperación antigénica con calor húmedo, en muestras de tejido óseo que ya habían sido previamente fijadas en formaldehido, decalcificadas con etilen - diaminotetraacético (EDTA), e incluidas en parafina. Materiales y método: Se utilizaron mues- tras de tejido óseo de cerdo que habían sido preparadas con técnicas convencionales, pertenecientes a la colección del laboratorio de patología de la Universidad del Valle. Se realizó refijacion en glutaraldehido y se empleó una vaporera para intensificar la exposición de antígenos. Se utilizó como anticuerpo primario el anti TRAP de DEKO®, monoclonal, originado en ratón, y como secundario el KIT UltraVision LP Large Volume Detection System HRP Polymer ®. Resultados: En todas las muestras expues- tas al anticuerpo primario en diluciones 1:20 y 1:40 se observó inmunotinción de células mononucleares compatibles con pre osteoclastos, y células gigantes mul - tinucleadas compatibles con osteoclastos. Conclusiones: La recuperación antigénica con calor húmedo es un método confiable en la recuperación antigénica de muestras óseas fijadas con formaldehido...(Au)

ntroduction: Nowadays, Immunohisto - chemistry are one of the most important techniques in the histopathological diagno - sis. Despite of handling and processing cau - tions, both of them may generate changes in the protein structure, masking antigens, preventing antibody identification. Among different antigen retrieval methods propo- sed by the literature, the humid heat with Steamer has been widely accepted for its simplicity, control and low cost. Objective: In this paper a protocol for humid heat antigen retrieval use in bone tissue samples that had been previously fixed in formaldehyde, decalcified with ethylenediaminetetraacetic (EDTA ), and embedded in paraffin is proposed. Materials and methods: Samples of pig's bone that had been prepared with conven- tional techniques, from the collection of the pathology laboratory of the University of Valle were used. New fixed process was performed in glutaraldehyde and a steamer was used to enhance antigen exposure. The anti-TRAP DEKOs ®, mouse monoclonal antibody was used as primary antibody, and the KIT UltraVision LP Large Volume Detection System HRP Polymer ® was used as a secondary antibody. Results: In all samples exposed to primary antibody in 1:20 and 1:40 dilutions immu - nostaining mononuclear cells compatible with preosteoclasts were observed; im - munostaining multinucleated giant cells consistent with osteoclasts were described. Conclusions: Humid heat for antigenic recovery is a reliable method for the reco- very of bone antigen samples fixed with formaldehyde...(Au)

Promoting effect of thrombin on proliferation of bone marrow-derived mesenchymal stem cells and its mechanisms / 中国实验血液学杂志

This study was aimed to investigate the growth-promoting activity of thrombin on mesenchymal stem cells (MSC) and its mechanisms. Human bone marrow MSC were cultured in serum-free medium supplemented with graded concentrations of thrombin, and the proliferation status of MSC was detected by MTT test. The expression levels of protease-activated receptors (PAR) and c-MYC gene were detected by PCR. Activated Akt signaling pathway was revealed by Western blot, and specific inhibitors of the signaling pathways were used to confirm the effects. The results showed that thrombin stimulated MSC proliferation in a dose-dependent manner; the minimal concentration of thrombin for stimulating MSC growth was 0.5 U/ml, and the promoting effect reached its maximum when thrombin at a dose of 8 U/ml was employed. PCR results showed that MSC expressed the two types of PAR1 and PAR2. After PAR1 was blocked with a specific inhibitor SCH79797, the growth-promoting effect of thrombin was inhibited, while this phenomenon was not observed when MSC were exposed to FSLLRY-NH2, a specific inhibitor for PAR2. Further experiments showed that after exposure to thrombin, the AKT signaling pathway in MSC was promptly activated, and c-MYC expression was greatly up-regulated. Meanwhile, when LY294002, a specific AKT inhibitor, was added into the culture medium, the up-regulation of c-MYC expression was reduced, accompanied by the low rate of MSC growth. It is concluded that thrombin can stimulate MSC proliferation by eliciting PAR1-mediated AKT activation and subsequent up-regulation of c-MYC expression.

Roles of protease-activated receptor-1 in thrombin-induced brain injury and neurogenesis in rats / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the roles of protease-activated receptors (PARs) in thrombin-induced brain injury and neurogenesis in rats.</p><p><b>METHODS</b>Ninety male SD rats were randomly assigned to receive intra-hippocampus injection of NS, thrombin or specific agonists of 3 protease-activated receptors (PAR-1, PAR-3 and PAR-4), respectively. At 1,3 and 7 d after injection, the area of the hippocampus was determined with HE staining, the density and morphology of astrocyte were detected with GFAP staining, degenerated neurons were detected with Fluoro-Jade C staining, and the neurogenesis was examined with DCX staining.</p><p><b>RESULTS</b>Compared to NS injection, the area of the hippocampus significantly increased at 1-3 d and decreased at 7 d after the injection of thrombin and PAR-1 agonist (P<0.05). In addition, injection of thrombin and PAR-1 agonist significantly increased the density of astrocyte and Fluoro-Jade C positive cells at 1-7 d after injection (P<0.05), and significantly increased the density of DCX positive cells at 3-7 d after injection(P<0.05). The injection of PAR-3 agonist and PAR-4 agonist had no affect on the area of the hippocampus, the density of astrocyte, Fluoro-Jade C positive cells and DCX positive cells.</p><p><b>CONCLUSION</b>The activation of protease-activated receptor-1 may be related to the thrombin-induced brain injury and neurogenesis in rat hippocampus.</p>

Basic Data for Reference Intervals in Koreans for Parameters Produced by Multiplate Platelet Function Analyzer

BACKGROUND: The Multiplate analyzer (Dynabyte GmbH) has been recently introduced as a platelet function test for patients taking antiplatelet drugs. The study aimed at providing basic data for determining the reference interval of parameters produced by Multiplate in Koreans and to study the factors that influence those parameters. METHODS: Blood was collected from 35 healthy volunteers (female 18, male 17) into tubes containing hirudin or 3.2% sodium citrate. Whole blood platelet aggregations triggered by adenosine-5'-diphosphate (ADP), ADP-high sensitive (ADP+PGE1 only in hirudin samples), arachidonic acid (AA), collagen or thrombin receptor activator peptide (TRAP) were investigated using Multiplate according to the manufacturer's instructions. Data from healthy volunteers for the area under the curve (AUC) were determined from the central 95th percentile of the results. RESULTS: The values of AUC in hirudin samples for all agonists were significantly higher than those in sodium citrate samples. The AUC values in hirudin (sodium citrate) samples were as follows: ADP 38-107 (18-119) U; ADP+PGE1 16-91 U; AA 64-156 (32-117) U; collagen 53-112 (26-108) U; and TRAP 81-163 (49-149) U. The parameters from Multiplate were significantly correlated with leukocyte counts, but not with hematocrit levels. CONCLUSIONS: Although our data were derived from only 35 subjects, the results are expected to be helpful in determining the reference interval at a single institute and may serve as basic data for future cumulative data of reference intervals from multiple institutes in Korea.

Effects of Salivae Miltiorrhizae Liguspyragine Hydrochloride and Glucose Injection on the levels of main platelet thrombin receptors in chronic haemodialysis patients / 中国结合医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of Salvia Miltiorrhiza Liguspyragine Hydrochloride and Glucose Injection (, SLGI) on the expression of platelet membrane receptors proteinase-activated receptor-1 (PAR1) and proteinase-activated receptor-4 (PAR4) in end-stage renal disease (ESRD) patients on chronic haemodialysis (HD).</p><p><b>METHODS</b>Eighty-six ESRD patients on HD (treated group) were treated with SLGI, 7 days as one therapeutic course, for two successive courses. The previous therapies were unchanged. Flow cytometry was used to assess the expression of platelet PAR1 and PAR4 in the patients, and turbidity method was used to determine the platelet maximum aggregation rate (MAR). Meanwhile, renal function was measured. The final data were compared with those before treatment and with those in the normal control group (54 healthy subjects).</p><p><b>RESULTS</b>Compared with the normal control group, the expressions of PAR1 and PAR4 and platelet MAR in ESRD patients on HD was significantly higher before treatment (P=0.001, P=0.006, and P=0.008); after treatment with SLGI, the above indices in patients were remarkably decreased (P=0.036 and P=0.046), except PAR4 (P=0.067), but still higher than those in the normal control group, however, it was not statistically significant.</p><p><b>CONCLUSIONS</b>(1) The overexpression of PAR1 and PAR4 might lead to increased platelet aggregation and this could be one of the reasons for the thrombotic events in ESRD patients on HD. (2) SLGI was able to down-regulate the expression of PAR1 in ESRD patients on HD, improve platelet function, and regulate platelet activation.</p>

PAR-1 regulation of intracellular Ca²(+) mobilization in pulmonary giant cell carcinoma cell line PLA801D/PLA801C / 中华病理学杂志

<p><b>OBJECTIVES</b>To investigate molecular mechanisms of PAR-1 regulation on intracellular Ca²(+) mobilization in lung giant cell carcinoma cells in vitro and its involvement in tumor metastasis.</p><p><b>METHODS</b>Free intracellular Ca²(+) ([Ca²(+)]i) was measured in lung giant cell carcinoma PLA801C and PLA801D cells by confocal microscopy. Sense and anti-sense PAR-1 expression vectors were transfected into PLA801C (C+)and PLA801D(D-) cells, respectively. The effects of PAR-1 expression were investigated by thrombin and TRAP-induced mobilization of [Ca²(+)]i in the C+ and D-cells.</p><p><b>RESULTS</b>There were significant differences of the mean values of [Ca²(+)]i between PLA801D (59.55) and PLA801C cells (35.46, P < 0.01). The mean [Ca²(+)]i of C+ cells (45.77) was significantly higher than that of its control CV cells (35.46, P < 0.05), and the mean [Ca²(+)]i of D-cells (48.42) was significantly lower than that of its control DV cells (59.55, P < 0.05). The peaks of [Ca²(+)]i of C+ and CV cells were 48.19 ± 9.84 and 45.64 ± 9.87 (P < 0.05) respectively at 80 s and 100 s after thrombin treatment, but were 111.31 ± 25.00 and 52.93 ± 11.21 (P < 0.05) respectively at 60 s after TRAP treatment. The peaks of [Ca²(+)]i of D- and DV cells were 40.71 ± 5.89 and 61.07 ± 21.36 (P < 0.05) respectively at 60 s after thrombin treatment, but were 84.98 ± 11.23 and 102.58 ± 21.48 (P < 0.05) respectively at 40 s after TRAP treatment.</p><p><b>CONCLUSIONS</b>The high metastatic potential of PLA801D and PLA801C may be related to [Ca²(+)]i of the tumor cells. PAR-1 may play an important role in the metastasis of lung giant cell carcinoma cells by up-regulating the intracellular Ca²(+).</p>

Role of phosphatidylinositol 3-kinase and myosin light chain kinase during the activation of thrombin receptors / 中国实验血液学杂志

The objective of study was to compare the influences of wortmannin on platelet aggregation and platelet membrane surface glycoproteins GPIb expression after thrombin receptor activation, and to investigate the role of phosphatidylinositol 3-kinase (PI3-K) and myosin light chain kinase (MLCK) in the course of thrombin receptor activation. Peptide SFLLRN (PAR1-AP) and AYPGKF (PAR4-AP) were used for stimulating platelet, and the changes of platelet aggregation and GPIb were analyzed with 100 nmol/L wortmannin (inhibitor of PI3-K) and 10 micromol/L wortmannin (inhibitor of MLCK). The results indicated that the platelet activation was influenced by either concentration of wortmannin in response to PAR stimulation. Platelet aggregation was apparently inhibited by 10 micromol/L wortmannin through both PAR peptides, and was slightly inhibited by 100 nmol/L wortmannin only under PAR1-AP activation. In addition, GPIbalpha internalization was partly inhibited by 100 nmol/L wortmannin in response to PAR1 (p < 0.05 at 1, 2, 5 min) and PAR4 (p < 0.05 at 2, 5, 10 min) activation. Meanwhile, 10 micromol/L wortmannin induced little change for GPIbalpha centralisation in the course of PAR activation, with a delayed restoration of surface GPIbalpha observed under PAR1-AP activation, and no change of GPIbalpha redistribution existed under PAR4-AP activation. It is concluded that the different roles of PI3-K and MLCK exist in the course of thrombin receptor activation. PI3-K accelerates the short course of GPIb centralisation for two PAR signal pathways, while MLCK inhibits the restoration of GPIbalpha in PAR1 pathway.

Effect of xiaoyu zhixue tablet on expression of thrombin receptor glycoproteins Eb/IX/V and glycoprotein Ibalpha in patients with hemorrhagic thrombopathy / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the effect of Xiaoyu Zhixue Tablet (XYZXT) on expression of platelet membrane glycoproteins (GP) Ib/IX/V complex and its component GP Ibalpha in patients with hemorrhagic thrombopathy, so as to explore its possible mechanism.</p><p><b>METHODS</b>Ninety-eight patients with hemorrhagic thrombopathy were randomly assigned to two groups, the TCM group (68 cases) treated with XYZXT and the Western medicine group (30 cases) treated with adrenosin, vitamins C, K and P, for 6 months totally. The hemostatic effect and the platelet aggregation recovery rate in the two groups were observed. And expressions of GPIb/IX/V complex and GP Ibalpha were analyzed by flow cytometry in both groups before and after treatment as well as in 34 healthy persons for control.</p><p><b>RESULTS</b>The hemostatic effective rate was 89.7% in the TCM group and 46.7% in the Western medicine group (u= 5.68, P < 0.01); the platelet aggregation recovery rate in the two groups was 67.6% and 3.3% respectively (chi2 = 34. 49, P < 0.01). The fluorescence intensity of GPIb/IX/V complex and GPIbalpha were lower in both groups before treatment than those of the healthy control (P < 0.05), but after treatment the two markers elevated in the TCM group, approaching the control (P > 0.05), and significantly higher than those in the Western medicine group (P < 0.05).</p><p><b>CONCLUSION</b>The partial mechanism of XYZXT in treating hemorrhagic thrombopathy might be its regulation on the expression of thrombin receptor at the receptor protein level.</p>

Effect of protein kinase C and calcium on the thrombin receptors activation / 中华血液学杂志

<p><b>OBJECTIVE</b>To compare the effects of protein kinase C (PKC) and calcium (Ca2+) on platelet aggregation and platelet membrane surface GP I b expression in thrombin receptors activation, and investigate the role of Gq signal transduction pathway in such activation.</p><p><b>METHODS</b>Peptide SFLLRN (PARI-AP) and AYPGKF (PAR4-AP) were used to stimulate platelet, and the effects of Ro-31-2220 (inhibitor of PKC) and BAPTA/AM (calcium chelator) on the platelet aggregation and GP I b were analyzed.</p><p><b>RESULTS</b>Either 25 micromol/L PAR1 or 250 micromol/L PAR4 peptide could induce absolute platelet aggregation with a reversible internalization of GP I b. Platelet aggregation was inhibited by Ro-31-2220 or BAPTA while the morphological change curve still occurred upon PARs activation. In addition, Ro-31-2220 decreased GP I b centralization upon PAR1 stimulation [(87.00 +/- 0.04)% and (73.00 +/- 0.08)%, respectively at 1, 2 min, P<0.05], albeit it blocked the internalization of GP I b in PAR4 activation [(44.00 +/- 0.01)% and (46.00 +/- 0.05)%, respectively at 10, 30 min, P <0.05]. Meanwhile, GP I b internalization was blocked by BAPTA in both peptides [(94.00 +/- 0.08)% and (95.00 +/- 0.00)% at 1 min, (92.00 +/- 0.02)% and (94.00 +/- 0.01)% at 2 min, (91.00 +/- 0.02)% and (91.00 +/- 0.02)% at 5 min, (90.00 +/- 0.04)% and (87.00 +/- 0.03)% at 10 min, respectively, P <0.05].</p><p><b>CONCLUSION</b>PKC and calcium play an important role in thrombin receptor activation. Calcium is closely correlated with such activation, being similar in the two PARs signal pathways. PK C promotes GP I b centralization in PAR1 pathway and accelerates GP I b return to membrane surface in PAR4 pathway.</p>

Thrombin and tumor metastasis - review / 中国实验血液学杂志

Thrombin is a multifunctional serine protease that plays a key role in a variety of physiological and pathological conditions. In addition to the role in hemostasis and coagulation, thrombin has other numerous biological activities affecting inflammation, immune responses, tissue repair and wound healing. Apart from its physiological role thrombin activates the oncogenic potential of both normal and malignant cells and leads a metastatic phenotype. It is a potent mitogen for many tumor cells. It potentiates the proliferative response of tumor cells to some growth factors, increases the adhesive properties to the platelets and invasion processes of tumor cells to the extracellular matrix, enhances the metastatic capacity of tumor cells, activates angiogenesis and remodels the microenvironment of the tumor. The cellular biological effects of thrombin are mediated at least in part by a new subfamily of G-protein-coupled receptors designated proteinase-activited receptors (PARs). Thrombin has a bilateral effect on tumor cells:enhanced growth at low concentration, impaired growth/apoptosis at higher concentration. In this papers, the biological function of thrombin, thrombin and tumors, and thrombin receptors etc were reviewed.

Thrombin and angiogenesis of cancer--review / 中国实验血液学杂志

Thrombin is the most important factor in hemostasis. In recent years, it has been found that thrombin is a potent mitogen capable of inducing cellular functions. Therefore, it is proved to be of importance in promoting the growth, metastasis and angiogenesis of cancer. Anticoagulant therapy not only reduce the characteristic hypercoagulability of cancer, but also inhibits growth and metastasis of cancer, and alters the fundamental biology of cancer. In this paper thrombin and its receptor, relationship of thrombin and its receptor with cancer growth, metastasis and angiogenesis, the mechanisms of thrombin influence on cancer angiogenesis, as well as application prospects on anti-angiogenesis and anti-coagulation therapy were reviewed.

Functions of thrombin receptors in the reversible distribution of platelet surface glycoprotein I balpha in activated platelets / 中华血液学杂志

<p><b>OBJECTIVE</b>To detect the redistribution of platelet surface glycoprotein (GP)Ib alpha and cytoskeleton reorganization in the course of thrombin receptor activation, and investigate the mechanism of GPIb alpha re-translocation and the role of thrombin receptors in platelet signal transduction.</p><p><b>METHODS</b>The thrombin receptor activating peptide (PAR1-AP, TRAP) was used for stimulating platelet at different time points (0 - 60 min), then the platelet surface GPIb alpha and P-selectin were examined with flow cytometry, and the alterations of GPIb alpha, actin and myosin were analyzed in cytoskeleton by Western blot and GPIb alpha immunoprecipitation. Cytochalasin D and/or Apyrase VII were used for investigating their inhibitory effect on platelet activation.</p><p><b>RESULTS</b>An increase of P-selectin and reversible internalization of GPIb alpha were observed within platelets upon TRAP activation, and transient changes of actin, myosin and GPIb alpha/myosin, GPIb alpha/actin association were also found in this course. These changes were apparently blocked by cytochalasin D, which inhibited the incorporation of GPIb alpha, actin and myosin into cytoskeleton. Apyrase VII had a weak effect on GPIb alpha internalization, although it accelerated the return of GPIb alpha to platelet surface. In addition, Apyrase VII also quickened the GPIb alpha disappearance in cytoskeleton and the dissociation of GPIb/myosin or GPIb/actin during activation.</p><p><b>CONCLUSION</b>Thrombin receptor activation takes part in platelet signal transduction, inducing a reversible redistribution of GPIb alpha. This process is related to cytoskeleton reorganisation and ADP.</p>

Mechanism of action of protease-activated receptors 1 and 4 in platelet activation / 中国实验血液学杂志

This study was designed to compare the effects of protease-activated receptor 1 (PAR-1) and protease-activated receptor 4 (PAR-4) to the expression of platelet surface GPIbalpha and cytoskeleton reorganization, then to investigate the role of PARs in platelet signal transmission. PAR1 (25 micromol/L) and PAR4 (250 micromol/L) were used to stimulate platelet at different time points (0 - 60 minutes), and the platelet surface GPIbalpha, actin and myosin and P-selectin were detected with flow cytometry, the alteration of GPIbalpha, actin and myosin in cytoskeleton was compared by Western blot, the membrane cytoskeleton followed GPIbalpha immunoprecipitation was analyzed. The results showed that an increase of P-selectin and reversible decrease of GPIbalpha expression were obtained after platelet activation by PAR1 o r PAR4, and a different kinetics of redistribution of GPIbalpha was found for the two peptides all over the time course (P < 0.05). PAR1 acted more potently and rapidly than PAR4, but the effect of PAR4 persisted longer in the course of platelet activation. Meanwhile, there was a transient change of actin, myosin and GPIbalpha in cytoskeleton proteins. Similar redistribution was also found in GPIbalpha/myosin and GPIbalpha/actin association. It is concluded that PAR1 and PAR4 possess an important role in platelet signal transmission. Either of the receptors can mediate platelet activation and GPIbalpha redistribution, which is correlated with cytoskeleton reorganization. PAR1 acts more rapidly, and effect of PAR4 persists longer.

Expression of antisense thrombin receptor gene inhibits intimal hyperplasia of rat carotid artery after balloon injury / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the mechanism of restenosis after angioplasty and to clarify the effect of thrombin and its receptor on restenosis development.</p><p><b>METHODS</b>Balloon catheter-induced injury was adopted to induce intimal hyperplasia of the carotid arteries in rats. Antisense thrombin receptor (ATR) cDNA was transfected by perfusing recombinant LXSN ATR plasmid/nanoparticle complex into the segment of the injured carotid artery.</p><p><b>RESULTS</b>PCR result showed integration of the recombined gene. Dot blot showed the expression of antisense TR mediated by recombinant LXSN ATR plasmid/nanoparticle complex in the wall of common carotid arteries of the experimental group rats, which enabled to inhibit TR gene expression and intimal hyperplasia of the injured arteries.</p><p><b>CONCLUSIONS</b>Thrombin and its receptor play an important role in the formation of neointima after the injury, which provides a potential clue in developing a new approach for prevention and treatment of restenosis after angioplasty.</p>

Effect of antisense thrombin receptor and p21 double gene co-expression system on the proliferation and apoptosis in human aortic smooth muscle cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To focus on the study of the effect on proliferation and apoptosis of human aortic smooth muscle cells (ASMC) by adeno-associated virus (AAV) vector carrying antisense thrombin receptor (ATR) and p21 double gene co-expression system.</p><p><b>METHODS</b>Cultured human AMSC was infected with recombinant AAV containing ATR, p21 single gene and AP double gene respectively. The integration and expression of genes were confirmed by semi-quantitative RT-PCR. The anti-proliferation effect was determined by MTT assay. Cell cycle and apoptotic cell counts were measured through Flow Cytometry. The rate of apoptotic cells was examined with acridine orange/ethidium bromide(AO/EB) stain.</p><p><b>RESULTS</b>RT-PCR indicated that the exogenous genes had been integrated into ASMC. The rates of cell survival were decreased by 16.67%, 21.60%, and 29.4% and the cell counts of G0/G1 phase were (61.8 +/- 2.9)%, (82.5 +/- 4.0)%, (80.4 +/- 6.1)% in ATR, p21 and AP group respectively after rAAV infected 4 days. The level and area of apoptotic peak were greater in AP double gene than ATR and p21 single gene. Cell stain indicated that apoptotic cells were (7.2 +/- 3.3)%, (10.7 +/- 5.6)%, and (18.3 +/- 2.7)% in each transgene group compared with (1.5 +/- 0.8)% in control group.</p><p><b>CONCLUSION</b>AP double gene co-expression system has powerful effect for inhibiting proliferation and inducing apoptosis ASMC than ATR and p21 single gene and that is a superior way for gene therapy to restenosis.</p>

The activation of platelet aggregation by human cholangiocarcinoma cells is mediated through thrombin receptor.

Tumor cell induced platelet aggregation (TCIPA) played an importance role in early state of thrombosis in cancer patients. In addition, TCIPA was recognized as one important step in metastatic cascade. Cholangiocarcinoma, one of the most common cancers in the north-eastern part of Thailand, associated with thrombosis was reported. The authors investigated the effects of cholangiocarcinoma cells on platelet function as measured by platelet aggregation. Primary human cholangiocarcinoma (HuCCA) cells were established in our laboratory. Cells were cultured as standard techniques and grown to confluence until used, after which cells were replaced with fresh medium (Dulbeco Modified Eargle's Medium, DMEM) without serum for 24, 48 and 72 h. Then, the conditioned medium (CM) was collected. CM (24, 48 and 72 h) from HuCCA failed to induce platelet aggregation, whereas, HuCCA pellets induced platelet aggregation and potentiated platelet aggregation induced by submaximal concentration of thrombin. Interestingly, platelet aggregation induced by HuCCA was inhibited by hirudin (thrombin receptor antagonist; 10, 20 and 40 U) in a dose dependent manner. Thus, cholangiocarcinoma cells can induce platelet aggregation in a direct tumor cell-platelet contact via thrombin receptor. Therefore, the use of antiplatelet agents especially via thrombin receptors may help to prevent TCIPA or metastasis by CCA.

Genetic Variants of Thromobomodulin Gene as Risk Factors for Myocardial Infarction

Thrombomodulin (TM) is thrombin receptor present on the luminal surface of endothelial cells. Because the thrombin-TM complex acts as an anticoagulant, the functional variants or deficiency of TM may lead to increment of thrombotic tendency. In this study, we screened the genetic variants of the TM gene in patients with myocardial infarction (MI) and analyzed the genotype to elucidate the effects of genetic variations of TM gene on the development of the MI. We screened a promoter region and coding sequence of the TM gene using single strand conformation polymorphism-heteroduplex analysis and identified three common genetic variants: those were TM G-33A, TM Ala455Val, and TM C1922T. The genotype frequencies were investigated in the patients with MI (n=234) and control subjects (n=291) by the method of allele-specific oligomer hybridization. The frequencies of mutant genotypes (TM -33A, TM 455Val, and TM 1922T) were higher in patient group compared to the control subjects in males while there were no significant differences in females. In the multiple logistic regression analysis, TM 455Val and TM 1922T alleles were independent risk factors for MI (OR[95% CI: 1.799[1.125-2.878] p=0.014 and 5.624[1.019-31.025], p=0.048, respectively) in males. However, the genetic variations were not independent risk factors for MI in females. There were significant linkage disequilibriums among three genetic variants. These linkage disequilibriums explain the similar effects of three genetic variants on the development of MI. To investigate the effect of the TM G-33A mutation on TM promoter activity, the two TM promoter constructs (pTM-355 and pTM-125, bearing TM -33G or TM -33A) containing of firefly luciferase gene were transfected into HepG2, BAE, and CHO cells. The promoter activities were higher in the promoter constructs with TM -33G compared to the constructs with TM -33A in pTM-355. These results suggest the possibility of the positive predisposing effect of TM -33A allele on MI in males. The functional study for TM Ala455Val and TM C1922T should be followed to elucidate the genotype effects of these mutations on the development of MI. In this study, we identified three genetic variants of TM gene and showed the significant associations between genetic variants and MI in males. These results proposed that TM gene is an attractive candidate for genetic risk factor for MI in Koreans.