Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Heparin Cofactor II”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2002

Plasma levels of heparin cofactor II (HCII) and thrombin-HCII complex in patients with disseminated intravascular coagulation.

Plasma levels of heparin cofactor II (HCII), thrombin-HCII complex (THC), antithrombin (AT), and thrombin-AT complex (TAT) were evaluated in patients with disseminated intravascular coagulation (DIC) associated with several underlying diseases. Plasma levels of AT were significantly reduced in almost all underlying diseases associated with DIC, but the plasma levels of HCII and HCII/AT ratio were significantly reduced only in patients with infections. While the plasma level of TAT was significantly increased in patients with all underlying diseases associated with DIC, the increase of THC was not significant. Plasma levels of AT were significantly reduced in DIC and pre-DIC associated with almost all underlying diseases, but those of HCII were significantly reduced only in DIC and pre-DIC patients with inflammatory diseases. The plasma levels of TAT were significantly increased in DIC, pre-DIC, and non-DIC patients with all underlying diseases, and those of THC were significantly increased in DIC and pre-DIC patients with inflammatory diseases. The plasma levels of THC were not significantly increased in non-DIC patients of any disease group. The decrease of AT may be caused by thrombin generation or inflammatory reaction that occurs in DIC associated with underlying diseases, while the decrease of HCII might be caused by both thrombin generation and inflammatory reaction. Finally, AT inhibits thrombin more strongly than HCII in several underlying diseases associated with DIC except for inflammatory diseases. In inflammatory diseases, HCII might play an important role in preventing the onset of DIC.

Antithrombin III↗
PubMed1993

Affinity chromatography of sulphated polysaccharides separately fractionated on antithrombin III and heparin cofactor II immobilized on concanavalin A--sepharose.

Three sulphated polysaccharides, dermatan sulphate, fucan and heparin, were fractionated according to their affinity towards antithrombin III (ATIII) and heparin cofactor II (HCII), the two main physiological thrombin (IIa) inhibitors. Both inhibitors were immobilized on concanavalin A-Sepharose, which binds to the glycosylated chains of the proteins while the protein-binding site for the polysaccharide remains free. Each polysaccharide was fractionated into bound and unbound fractions either for ATIII or HCII. The eluted fractions were tested for their ability to catalyse ATIII/IIa and HCII/IIa interactions. The possible presence of a unique binding site for ATIII and HCII, on each sulphated polysaccharide, was also studied.

Animals↗
PubMed1989

Interaction of thrombin with heparin cofactor II and antithrombin III on prostacyclin production by cultured endothelial cells.

To investigate the physiologic function of heparin cofactor II (HCII), endothelial cells from human umbilical vein were incubated in vitro for 20 min with 0.5 NIH U/ml thrombin in the presence of HCII or antithrombin III (ATIII), and prostacyclin production determined by radioimmunoassay for 6-keto-prostaglandin F1 alpha, the stable metabolite of prostacyclin. Although ATIII at 20 mInh.U/ml slightly but significantly inhibited thrombin-induced prostacyclin production, neither unfractionated heparin (UFH) nor low molecular weight heparin (LMWH) at 1 U/ml accelerated the inhibitory effect of ATIII. HCII at 10 and 20 mInh.U/ml did not decrease thrombin stimulation of prostacyclin production in the presence or absence of UFH or LMWH. However, HCII caused a marked decrease in the thrombin-stimulated prostacyclin prostacyclin production in the presence of 2 mg/ml dermatan sulfate (DS). The significant inhibition by HCII occurred when the DS concentrations were 0.2 microgram/ml and higher. From these results we suggest that HCII may prevent a prostacyclin-induced inhibition of platelet aggregation for hemostasis when plasma is exposed to vascular smooth muscle cells or fibroblasts which synthesize a significant amount of DS.

Antithrombin III↗
PubMed1990

Interaction of heparin cofactor II with neutrophil elastase and cathepsin G.

We investigated the interaction of the human plasma proteinase inhibitor heparin cofactor II (HC) with human neutrophil elastase and cathepsin G in order to examine 1) proteinase inhibition by HC, 2) inactivation of HC, and 3) the effect of glycosaminoglycans on inhibition and inactivation. We found that HC inhibited cathepsin G, but not elastase, with a rate constant of 6.0 x 10(6) M-1 min-1. Inhibition was stable, with a dissociation rate constant of 1.0 x 10(-3) min-1. Heparin and dermatan sulfate diminished inhibition slightly. Both neutrophil elastase and cathepsin G at catalytic concentrations destroyed the thrombin inhibition activity of HC. Inactivation was accompanied by a dramatic increase in heat stability, as occurs with other serine proteinase inhibitors. Proteolysis of HC (Mr 66,000) produced a species (Mr 58,000) that retained thrombin inhibition activity, and an inactive species of Mr 48,000. Amino acid sequence analysis led to the conclusion that both neutrophil elastase and cathepsin G cleave HC at Ile66, which does not affect HC activity, and at Val439, near the reactive site Leu444, which inactivates HC. Since cathepsin G is inhibited by HC and also inactivates HC, we conclude that cathepsin G participates in both reactions simultaneously so that small amounts of cathepsin G can inactivate a molar excess of HC. High concentrations of heparin and dermatan sulfate accelerated inactivation of HC by neutrophil proteinases, with heparin having a greater effect. Heparin and dermatan sulfate appeared to alter the pattern, and not just the rate, of proteolysis of HC. We conclude that while HC is an effective inhibitor of cathepsin G, it can be proteolyzed by neutrophil proteinases to generate first an active inhibitor and then an inactive molecule. This two-step mechanism might be important in the generation of chemotactic activity from the amino-terminal region of HC.

Amino Acid Sequence↗
PubMed1987

The role of heparin cofactor II in the modulation of hemostasis.

Human plasma contains two distinct heparin dependent thrombin inhibitors; antithrombin III (ATIII) and Heparin cofactor II (HCII). The latter is also known as antithrombin BM, because of its moderate binding affinity to heparin. The protein is distinct from ATIII by immunological and functional criteria as well as by its amino acid sequence. HCII selectively inhibits thrombin by forming a 1:1 molar complex with the protease and has no activity towards other coagulation serine proteases. Dermatan sulphate, a glycosaminoglycan, specifically activates HCII and increases its thrombin neutralizing activity by over a thousand fold. Dermatan sulphate does not catalyze the activity of ATIII. Human fibroblasts have been shown to accelerate the neutralization of thrombin by HCII. These cells can synthesize proteoglycans containing dermatan sulphate. Current evidence would thus suggest that extravascular tissues are the major sites of action of HCII. The specificity of dermatan sulphate for HCII has allowed the development of functional assays for this protein. Reduced levels have been observed in patients with significant hepatocellular dysfunction and in association with disseminated intravascular coagulation. Two families have been reported with hereditary HCII deficiency and recurrent thrombosis (both venous and arterial). Although these observations suggest a role for HCII in the modulation of hemostatic system, further studies are required to define the importance of HCII deficiency as a marker of thrombosis.

Antithrombin III↗
PubMedDate not supplied

Effect of sulfated xylans during the interaction of [125I]-thrombin with antithrombin III or heparin cofactor II of human plasma.

[125I]-Labeled thrombin was incubated with human plasma and its interactions with the two plasma protease inhibitors antithrombin III (AT-III) or heparin cofactor II (HC-II) were investigated in the presence of oat spelts xylan sulfate (OSXS), sodium pentosan polysulfate (SP-54), and the results were compared with heparin and dermatan sulfate. Addition of OSXS or SP-54 enhanced the complexation of thrombin with HC-II or with both AT-III and HC-II depending upon the concentration and the duration of the interactions of the sulfated compounds with plasma. During the 30 s interaction, OSXS and SP-54 enhanced both AT-III-thrombin and HC-II-thrombin interaction while heparin was more selective and enhanced only the AT-III-thrombin interaction. However after a 2 min interaction, heparin showed an increase in the HC-II-thrombin interaction at higher concentrations. The complexations of AT-III-thrombin and HC-II-thrombin were reversed in the presence of 200 micrograms/ml of SP-54 during a 30 s interaction or in presence of 100 micrograms/ml of OSXS during a 2 min interaction. The Western blotting method of detecting thrombin showed that during the 10 s interaction, heparin enhanced the thrombin-AT-III complex formation while OSXS enhanced the thrombin-HC-II complex formation.

Antithrombin III↗
PubMed1991

Immobilization of dermatan sulphate on a silica matrix and its possible use as an affinity chromatography support for heparin cofactor II purification.

Dermatan sulphate (DS) is a glycosaminoglycan which catalyses specifically thrombin inhibition by a plasmatic inhibitor, Heparin cofactor II (HCII). DS was insolubilized on a silica matrix to study its interaction with HCII. The immobilization of DS was performed with a good yield on a silica previously coated with polysaccharides in order to neutralize the negatively charged silanol groups. The value of the affinity constant of insolubilized DS for HCII, measured by the adsorption isotherm, is consistent with the value obtained for soluble DS. The DS bound to the silica matrix was also tested as a chromatographic support for the purification of HCII from human plasma; the optimum conditions for HCII adsorption and desorption were determined. The eluted HCII was obtained with a good yield (21%) and with no contamination by antithrombin III, the other main plasmatic inhibitor of thrombin.

Chromatography, Affinity↗
PubMed2004

Homozygous deficiency of heparin cofactor II: relevance of P17 glutamate residue in serpins, relationship with conformational diseases, and role in thrombosis.

BACKGROUND: Heparin cofactor II (HCII) is a hepatic serpin with significant antithrombin activity that has been implicated in coagulation, inflammation, atherosclerosis, and wound repair. Recent data obtained in mice lacking HCII suggest that this serpin might inhibit thrombosis in the arterial circulation. However, the clinical relevance and molecular mechanisms associated with deficiency of HCII in humans are unclear. METHODS AND RESULTS: We studied the first family with homozygous HCII deficiency, identifying a Glu428Lys mutation affecting a conserved glutamate at the hinge (P17) of the reactive loop. No carrier reported arterial thrombosis, and only 1 homozygous HCII-deficient patient developed severe deep venous thrombosis, but she also had a de novo Glu100Stop nonsense truncation in the antithrombin gene. CONCLUSIONS: Our results confirm the key structural role of the P17 glutamate in serpins. The same mutation causes conformational instability and polymerization in 3 serpins: Drosophila necrotic, human alpha1-antitrypsin, and human HCII, which explains their plasma deficiency. In the family under study here, however, plasma HCII deficiency was not associated with a significant clinical phenotype.

Adult↗
PubMed2003

Localization of heparin cofactor II in injured human skin: a potential role in wound healing.

The physiologic function of the serpin heparin cofactor II (HCII) is not fully understood. We have hypothesized that HCII functions as an extravascular inhibitor of thrombin. Thrombin formed at a site of injury has been hypothesized to contribute to migration and proliferation of fibroblasts and smooth muscle cells involved in wound healing. To begin to test our hypothesis, we examined the immunohistochemical localization of HCII in human skin and compared it to that of the closely related serpin, antithrombin (ATIII). In skin specimens with acute wounds, there was diffuse HCII and ATIII staining in areas of hemorrhage. In healing skin wounds ATIII was primarily associated with mast cells, while HCII was associated with mononuclear phagocytes in the dermis. Blood monocytes isolated from healthy donors also stained for HCII protein. However, in situ hydridization and RT-PCR studies failed to show significant HCII mRNA expression either in macrophages in wounded skin or in peripheral blood leukocytes. HCII localization is not due to nonspecific uptake of plasma proteins, since ATIII had a very different distribution in wounded skin. These findings support the notion that HCII could function as an extravascular thrombin inhibitor and might play a role in the regulation of wound healing.

Antithrombin III↗
PubMed2006

Decreased heparin cofactor II activity is associated with impaired endothelial function determined by brachial ultrasonography and predicts cardiovascular events.

BACKGROUND: Heparin cofactor II (HCII) could inactivate thrombin after binding to dermatan sulfate at injured arterial walls, and has been shown to be a novel and independent antiatherosclerotic factor. However, the relation between plasma HCII activity and peripheral vascular endothelial function remains unclear. METHODS: A total of 199 patients (mean age, 63+/-14 years) were enrolled and followed up for a median period of 24 months. Endothelial function was assessed using brachial ultrasonography to determine endothelium dependent flow-mediated vasodilation (FMD). Cox regression analyses were conducted for the 199 subjects, with cardiovascular events being defined as myocardial infarction (MI), percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), ischemic stroke, and peripheral artery revascularization. RESULTS: A total of 31 patients (16%) had cardiovascular events. Patients with cardiovascular events had significantly lower HCII activity (112+/-34 versus 127+/-34%, p=0.027) and lower antithrombin III (ATIII) activity (82+/-12 versus 88+/-13%, p=0.014) than those without events. By multivariate analysis, age (p=0.012), hsCRP (p=0.020) and HCII activity (p=0.035) were correlated with FMD. Kaplan-Meier analysis was performed and showed plasma HCII (p=0.036) and ATIII activities (p=0.005) were predictors of cardiovascular events. By Cox regression analysis, plasma HCII activity (p=0.026) could be an independent predictor of future cardiovascular events, but not ATIII. CONCLUSIONS: The present study demonstrates that plasma HCII activity is positively correlated with endothelial vasodilator function. Furthermore, plasma HCII activity could be a predictor of future cardiovascular events in patients with suspected coronary artery disease, suggesting its role in atherosclerosis.

Aged↗
PubMed1990

Hereditary heparin cofactor II deficiency and thrombosis: report of six patients belonging to two separate kindreds.

We describe six patients belonging to two families with congenital heparin cofactor II deficiency (HC II). The affected members had low levels of HC II antigen and activity, and no abnormalities in HC II electrophoretic mobility were detected in the presence of heparin or dermatan sulphate during the first migration of crossed immunoelectrophoresis. These data suggested that patients had a type I (true) HC II deficiency. The association of thrombotic manifestations with congenital HC II deficiency has not been completely clarified. In these two families, thrombotic events occurred in two out of six affected members. In addition, there was a high incidence of spontaneous abortion in the affected females. Finally, the association of congenital HC II deficiency with angiomatosis was also observed in one patient.

Abortion, Habitual↗
PubMed2006

Investigating serpin-enzyme complex formation and stability via single and multiple residue reactive centre loop substitutions in heparin cofactor II.

INTRODUCTION: Following thrombin cleavage of the reactive centre (P1-P1'; L444-S445) of the serpin heparin cofactor II (HCII), HCII traps thrombin (IIa) in a stable inhibitory complex. To compare HCII to other serpins we substituted: the P13-P5' residues of HCII with those of alpha(1)-proteinase inhibitor (alpha(1)-PI), alpha(1)-PI (M358R), or antithrombin (AT); the P4-P1, P3-P1, and P2-P1 residues of HCII with those of AT; and made L444A/H/K/M or R point mutations. We also combined L444R with changes in the glycosaminoglycan binding domain collectively termed MutD. MATERIALS AND METHODS: Variants were made by site-directed mutagenesis, expressed in bacteria, purified and characterized electrophoretically and kinetically. RESULTS AND CONCLUSIONS: Of the P13-P5' mutants, only the alpha(1)-PI-loop variant retained anti-IIa activity, but less than the corresponding L444M. Heparin-catalyzed rate constants for IIa inhibition were reduced vs. wild-type (WT) by at most three-fold for all P1 mutants save L444A (reduced 20-fold). L444R and L444K inhibited IIa>50- and >6-fold more rapidly than WT in heparin-free reactions, but stoichiometries of inhibition were increased for all variants. HCII-IIa complexes of all P1 variants were stable in the absence of heparin, but those of the L444K and L444R variants released active IIa over time with heparin. Limited proteolysis of these two groups of HCII-IIa complexes produced different fragmentation patterns consistent with conformational differences. The combination of either substituted AT residues at P2, P3, and P4, or the MutD mutations with L444R resulted in complex instability with or without heparin. This is the first description of HCII-IIa complexes of transient stability forming in the absence of heparin, and may explain the extent to which the reactive centre loop of HCII differs from that of AT.

Amino Acid Substitution↗
PubMed1986

Pentosan polysulphate: activation of heparin cofactor II or antithrombin III according to molecular weight fractionation.

The relative potency of pentosan polysulphate in activation of heparin cofactor II/thrombin interaction has been compared to heparin and dermatan sulphate and found to be within the same order. A skewed distribution of molecular weight forms was observed upon gel filtration of pentosan polysulphate with an average molecular weight of 4500 daltons. Two peaks of activity were observed in activation of heparin cofactor II. The greatest activity was observed in high molecular weight fractions (5-fold greater than that of average molecular weight) and a concentration-dependent profile indicated a template mechanism of action. A lower peak of activity was observed at average molecular weight and the effect of increasing concentrations of this material on activity indicated a mechanism involving binding to proteinase inhibitor or proteinase alone. Potentiation of antithrombin III/thrombin interaction was observed only in fractions greater than the average molecular weight. Concentration-dependent profiles indicated binding to antithrombin III and thrombin was a requisite of activation. A fraction of low molecular weight showed no property of activation of antithrombin III or heparin cofactor II/thrombin interaction. Three fractions of high, average and low molecular weights tested in clotting assays showed relative potencies corresponding to those observed in the purified systems.

Antithrombin III↗
PubMed1983

Activation of heparin cofactor II by dermatan sulfate.

We have tested the ability of various glycosaminoglycans to increase the rate of inhibition of thrombin by heparin cofactor II (HCII) and by antithrombin III (ATIII) isolated from human plasma. Heparin, dermatan sulfate, and heparan sulfate from bovine liver (in order of decreasing activity) activated HCII. In contrast, only heparin and bovine liver heparan sulfate activated ATIII, whereas dermatan sulfate was inactive at concentrations less than or equal to 1 mg/ml. Heparan sulfate from human aorta, chondroitin 4-sulfate, chondroitin 6-sulfate, keratan sulfate, and hyaluronic acid had little or no activity with either HCII or ATIII. The second order rate constant for the thrombin-HCII reaction reached a maximum value of 6.4 X 10(8) M-1 min-1 in the presence of 250-500 micrograms/ml of dermatan sulfate compared to 3.8 X 10(8) M-1 min-1 in the presence of 40-80 micrograms/ml of heparin. When 125I-thrombin was incubated with plasma in the presence of greater than or equal to 100 micrograms/ml of dermatan sulfate, the protease became complexed exclusively with HCII, suggesting that HCII is the only thrombin inhibitor in human plasma that can be activated by dermatan sulfate.

Animals↗
PubMed1991

Inhibitory effect of heparin cofactor II on thrombin-stimulated prostacyclin production by cultured vascular smooth muscle cells.

We investigated the effect of heparin cofactor II (HCII) on thrombin-induced prostacyclin (PGI2) production by A10 cells, an established cell line of vascular smooth muscle cells from murine aorta. Confluent monolayers of A10 cells were incubated with 0.1 NIH U/ml of thrombin for 30 min in the presence of antithrombin III (ATIII) or HCII, and PGI2 production by the cells was measured by radioimmunoassay as 6-keto-prostaglandin F1a, the stable metabolite of PGI2. ATIII at 40 mInh.U/ml and more significantly inhibited thrombin-induced PGI2 production by A10 cells, but HCII at the same doses did only slightly. However, when A10 cells were preincubated with HCII for 30 min before exposure to thrombin, the PGI2 production was markedly inhibited. The medium conditioned by A10 cells for 30 min did not enhance the inhibitory effect of HCII on thrombin-induced PGI2 production by the cells. On the other hand, A10 cells synthesized both dermatan sulfate and heparan sulfate which are capable of activating HCII. From these results, it was suggested that HCII would be activated by glycosaminoglycans (GAGs) such as dermatan sulfate of the cell layers and could inhibit thrombin-induced PGI2 production. HCII may be a modulator of thrombin on the physiological functions of vascular smooth muscle cells, reacting to the cell surface GAGs.

Antithrombin III↗
PubMed1992

Elevated levels of thrombin-heparin cofactor II complex in plasma from patients with disseminated intravascular coagulation.

An ELISA assay for quantitation of the thrombin-heparin cofactor II complex (T-HC II) in plasma was developed. Plasma was incubated with immobilized, specific antibodies to human thrombin. The second, biotinylated antibody was directed against human HC II. The assay was insensitive to thrombin-antithrombin complex (TAT) and to uncomplexed HC II. In plasma samples from 31 normal individuals (aged 21-68, mean 43.3 years), the T-HC II ranged 0.3-6.1 ng/ml; median 1.5, mean 2.0, and SD 1.6 ng/ml. In plasma samples from 13 patients with disseminated intravascular coagulation (DIC), T-HC II ranged 0.4-30.0 (median 13.5) ng/ml. In plasma samples from 6 patients in which the clinical suspicion of DIC was not verified, T-HC II complex ranged 1.4-14.3 (median 3.6) ng/ml. In plasma samples with elevated T-HC II levels, TAT was usually elevated, and on the average more than was T-HC II. These results indicate that HC II contributes significantly to the inactivation of in vivo generated thrombin.

Adolescent↗