scholarly journals Soluble L-selectin is present in human plasma at high levels and retains functional activity.

1992 ◽  
Vol 119 (1) ◽  
pp. 229-238 ◽  
Author(s):  
B Schleiffenbaum ◽  
O Spertini ◽  
T F Tedder
Keyword(s):  
Human Plasma ◽  
Functional Activity ◽  
Potential Role ◽  
Dependent Manner ◽  
High Endothelial Venules ◽  
Peripheral Lymph ◽  
Specific Attachment ◽  
Normal Human ◽  
Dose Dependent

L-selectin expressed by granulocytes, lymphocytes, and monocytes is responsible for initial leukocyte attachment to inflamed endothelium and high endothelial venules of peripheral lymph nodes. After leukocyte activation in vitro, L-selectin is rapidly shed from the cell surface. In this study, shed L-selectin (sL-selectin) from both lymphocytes and neutrophils was demonstrated to be present in high levels in human plasma by Western blot analysis and using a quantitative ELISA. In serum from normal human blood donors, a mean sL-selectin level of 1.6 +/- 0.8 micrograms/ml (n = 63) was found by ELISA. In addition, semipurified sL-selectin from plasma inhibited L-selectin-specific attachment of lymphocytes to cytokine-activated endothelium in a dose-dependent manner. L-selectin-dependent leukocyte attachment was completely inhibited at sL-selectin concentrations of 8-15 micrograms/ml, while physiological concentrations of sL-selectin caused a small but consistent inhibition of lymphocyte attachment. sL-selectin in plasma also inhibited anti-L-selectin mAb (2-5 micrograms/ml) binding to the surface of leukocytes. Interestingly, one epitope present within the EGF-like domain of L-selectin was lost in sL-selectin, suggesting a conformational change in the structure of the receptor after shedding. The presence of serum sL-selectin with functional activity indicates a potential role for sL-selectin in the regulation of leukocyte attachment to endothelium.

scholarly journals High molecular weight kininogen inhibits thrombin-induced platelet aggregation and cleavage of aggregin by inhibiting binding of thrombin to platelets

Blood ◽  
1991 ◽  
Vol 77 (3) ◽  
pp. 500-507 ◽  
Author(s):  
RN Puri ◽  
F Zhou ◽  
CJ Hu ◽  
RF Colman ◽  
RW Colman
Keyword(s):  
Molecular Weight ◽  
Platelet Aggregation ◽  
Plasma Concentration ◽  
Human Plasma ◽  
Shape Change ◽  
Dependent Manner ◽  
Normal Human Plasma ◽  
High Molecular Weight Kininogen ◽  
Normal Human ◽  
Dose Dependent

In this study we show that high molecular weight kininogen (HK) inhibited alpha-thrombin-induced aggregation of human platelets in a dose-dependent manner with complete inhibition occurring at plasma concentration (0.67 mumol/L) of HK. HK (0.67 mumol/L) also completely inhibited thrombin-induced cleavage of aggregin (Mr = 100 Kd), a surface membrane protein that mediates adenosine diphosphate (ADP)- induced shape change, aggregation, and fibrinogen binding. The inhibition of HK was specific for alpha- and gamma-thrombin-induced platelet aggregation, because HK did not inhibit platelet aggregation induced by ADP, collagen, calcium ionophore (A23187), phorbol myristate acetate (PMA), PMA + A23187, or 9,11-methano derivative of prostaglandin H2 (U46619). These effects were explained by the ability of HK, at physiologic concentration, to completely inhibit binding of 125I-alpha-thrombin to washed platelets. As a result of this action of HK, this plasma protein also completely inhibited thrombin-induced secretion of adenosine triphosphate, blocked intracellular rise in Ca2+ in platelets exposed to alpha- and gamma-thrombin, inhibited thrombin- induced platelet shape change, and blocked the ability of thrombin to antagonize the increase in intracellular cyclic adenosine monophosphate (cAMP) levels induced by iloprost. Because elevation of cAMP is known to inhibit binding of thrombin to platelets, we established that HK did not increase the intracellular concentration of platelet cAMP. Finally, HK did not inhibit enzymatic activity of thrombin. To study the role of HK in the plasma environment, we used gamma-thrombin to avoid fibrin formation by alpha-thrombin. Platelet aggregation induced by gamma- thrombin was also inhibited by HK in a dose-dependent manner. The EC50 (concentration to produce 50% of the maximum rate of aggregation) of gamma-thrombin for washed platelets was 7 nmol/L and increased to 102 nmol/L when platelets were suspended in normal human plasma. The EC50 for platelet aggregation induced by alpha-thrombin in plasma deficient in total kininogen was 40 nmol/L. When supplemented with HK at plasma concentration (0.67 mumol/L), the EC50 increased to 90 nmol/L, a value similar to that for normal human plasma. These results indicate that (1) HK inhibits thrombin-induced platelet aggregation and cleavage of aggregin by inhibiting binding of thrombin to platelets; (2) HK is a specific inhibitor of platelet aggregation induced by alpha- and gamma- thrombin; and (3) HK plays a role in modulating platelet aggregation stimulated by alpha-thrombin in plasma.

Cleavage of Recombinant and Plasma-Derived VWF by Human ADAMTS13

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1415-1415
Author(s):  
Hanspeter Rottensteiner ◽  
Katalin Varadi ◽  
Susanne Vejda ◽  
Hartmut J. Ehrlich ◽  
Friedrich Scheiflinger ◽  
...  
Keyword(s):  
Shear Stress ◽  
Human Plasma ◽  
Phase 1 ◽  
Dependent Manner ◽  
Normal Human ◽  
Typical Satellite ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Kinetics Of

Abstract Abstract 1415 A recombinant human CHO-expressed von Willebrand factor (rVWF) consisting of ultra-high molecular weight (UHMW) multimers resembles the VWF stored in Weibel-Palade bodies of endothelial cells. Once secreted into plasma, UHMW multimers are rapidly cleaved by ADAMTS13 and are usually missing in plasma-derived VWF (pdVWF). Here we analyzed in vitro whether the kinetics of cleavage of rVWF by ADAMTS13 is similar to that of pdVWF. The kinetics of ADAMTS13-mediated proteolysis of rVWF were explored under denaturing conditions (1.5 M urea) or under shear stress so as to expose the ADAMTS13 cleavage site of VWF. Multiple assays showed that rVWF was efficiently cleaved by ADAMTS13. UHMW multimers disappeared within seconds at physiological concentrations of ADAMTS13. Using lower concentrations of ADAMTS13 (10-30 mU/ml, equivalent to 1–3% of normal human plasma), UHMW were cleaved within 30 minutes. The typical satellite bands appeared very early in an ADAMTS13 dose-dependent manner. Virtually the same results were obtained when human plasma was used as a source for ADAMTS13. Although pdVWF differs from rVWF in its multimeric structure, the decrease in activity was similar for rVWF and pdVWF. Finally, the extent of ADAMTS13 cleavage was similar for rVWF and pdVWF when exposed to shear stress using a cone-plate viscometer. Our data clearly indicate that rVWF is a good substrate for ADAMTS13. Ongoing phase 1 studies demonstrated that rVWF is indeed processed by the protease when administered in humans with severe VWD. Disclosures: Rottensteiner: Baxter Innovations GmbH: Employment. Varadi:Baxter Innovations GmbH: Employment. Vejda:Baxter Innovations GmbH: Employment. Ehrlich:Baxter Innovations GmbH: Employment. Scheiflinger:Baxter Innovations GmbH: Employment. Schwarz:Baxter Innovations GmbH: Employment. Turecek:Baxter Innovations GmbH: Employment.

scholarly journals Anti-inflammatory Effect of the Peptide LKEKK

2021 ◽  
Vol 6 (5) ◽  
Keyword(s):  
High Specificity ◽  
Dependent Manner ◽  
Thymosin Α1 ◽  
Tnf Α ◽  
Normal Human ◽  
Anti Inflammatory ◽  
Interferon Α2 ◽  
Dose Dependent

We have established that the peptide LKEKK (Np5) corresponding to the sequence 16-20 of thymosin-α1 and to the sequence 131-135 of interferon-α2, in the concentration range 50 300 µg/ear reduces in a dose-dependent manner phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin edema in mice .Tested in parallel peptide with inverted sequence (iNp5, KKEKL, 150-300 µg/ear) was inactive, indicating high specificity of the Np5 action. In the concentration range of 5 20 µM Np5 significantly decrease the TNF-α-induced production by normal human keranocytes of pro-inflammatory mediators IL-6 and IL-1β. Thus, Np5t has a pronounced anti-inflammatory activity in vivo and in vitro.

Kinetics of Human VWF Cleavage by Human ADAMTS13: Comparison of Recombinant and Plasma-Derived VWF

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4092-4092
Author(s):  
Hanspeter Rottensteiner ◽  
Katalin Varadi ◽  
Susanne Vejda ◽  
Jutta Schreiner ◽  
Herbert Gritsch ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Human Plasma ◽  
Degradation Kinetics ◽  
Dependent Manner ◽  
Normal Human Plasma ◽  
Normal Plasma ◽  
Normal Human ◽  
Typical Satellite ◽  
Kinetics Of

Abstract A recombinant human CHO-expressed von Willebrand factor (rVWF) which consists of ultra-high molecular weight (UHMW) multimers resembles the VWF that is stored in Weibel-Palade bodies of endothelial cells. Once secreted into plasma, UHMW multimers are rapidly cleaved by ADAMTS13 and therefore are usually missing in VWF purified from plasma. We analyzed in vitro whether the cleavage of rVWF by ADAMTS13 is similar to the cleavage of plasma VWF by ADAMTS13, using a standard assay that depends on denaturing conditions (1.5 M urea) to expose the ADAMTS13 cleavage site of VWF. We explored the kinetics of ADAMTS13-mediated proteolysis of rVWF over time by exposing 1 VWF:Ag IU/ml of rVWF to various concentrations of recombinant and plasma-derived purified ADAMTS13, ranging from 4 mU/ml to 1 U/ml (corresponding to 0.4 to 100% of the normal human plasma concentration), and to ADAMTS13 present in normal human plasma and VWF-deficient plasma. The multimeric structure and function of VWF were analyzed by multiple assays to compare VWF before, during, and after proteolytic cleavage. In addition, the degradation kinetics of recombinant VWF were compared with those of a plasma-derived VWF product. Recombinant VWF was cleaved rapidly and with the same efficiency using recombinant or plasma-derived ADAMTS13. With 0.5 U/ml pADAMTS13 or rADAMTS13, VWF:RCo activity was below the detection limit of 0.17 IU/ml after 15 s. UHMW multimers disappeared within seconds at physiological concentrations of 0.5–1.0 U/ml ADAMTS13 (50–100% of the normal plasma concentration). Furthermore, UHMW were cleaved within 30 minutes with much lower concentrations of 10–30 mU/ml ADAMTS13 (1–3% of normal plasma concentration). The typical satellite bands appeared very early in an ADAMTS13 dose-dependent manner. Although plasma-derived VWF differs substantially from rVWF in its multimeric structure, the decrease in activity was similar for the recombinant and plasma-derived VWF. Specific cleavage of rVWF (3 IU VWF:Ag/ml) by rADAMTS13 (5 U/ml) was also demonstrated without urea under shear stress in the presence of platelets, detected by a monoclonal antibody (N10) that recognizes VWF only when cleaved by ADAMTS13. The combined data show that ADAMTS13 is able to readily cleave human rVWF even at low concentrations and that the UHMW multimeric fraction of human rVWF is removed within minutes by ADAMTS13 in vitro.

CCR7-mediated physiological lymphocyte homing involves activation of a tyrosine kinase pathway

Blood ◽  
2003 ◽  
Vol 101 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Jens V. Stein ◽  
Silvia F. Soriano ◽  
Christine M'rini ◽  
César Nombela-Arrieta ◽  
Gonzalo González de Buitrago ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Chemotactic Response ◽  
Dependent Manner ◽  
High Endothelial Venules ◽  
Peripheral Lymph ◽  
Primary Mouse ◽  
Multistep Process ◽  
Dose Dependent ◽  
Mouse Lymphocytes ◽  
B And T Lymphocytes

Abstract Homing of blood-borne lymphocytes to peripheral lymph nodes (PLNs) is a multistep process dependent on the sequential engagement of L-selectin, which mediates lymphocyte rolling along the luminal surface of high endothelial venules (HEVs), followed by activation of lymphocyte integrins and transmigration through HEVs. Within lymphoid tissue, B and T lymphocytes then migrate toward specific microenvironments such as B-cell follicles and the paracortex, respectively. The lymphocyte-expressed chemokine receptor CCR7 is playing an important role during this process, as its HEV-presented ligands CCL19 and CCL21 can trigger rapid integrin activation under flow in addition to inducing a chemotactic response, which may participate in transmigration and/or interstitial migration. Here, we report that Tyrphostin (Tyr) AG490, a pharmacological inhibitor of Janus family tyrosine kinases (Jaks), blocked the chemotactic response of primary mouse lymphocytes to CCL19 and CCL21 in a dose-dependent manner. Furthermore, Tyr AG490 inhibited rapid CCL21-mediated up-regulation of α4 and β2 integrin adhesiveness in static adhesion assays and under physiological flow, whereas adhesion induced by phorbol myristate acetate remained unaltered. Using intravital microscopy of subiliac PLNs in mice, we found that adoptively transferred Tyr AG490–treated lymphocytes adhered significantly less in HEVs compared with control cells, although L-selectin–mediated rolling was similar in both samples. Finally, we observed rapid Jak2 phosphorylation in CCL21-stimulated primary mouse lymphocytes. Thus, our study suggests a role for Jak tyrosine kinases during CCR7-mediated lymphocyte recirculation.

scholarly journals Anti-inflammatory Effect of the Peptide LKEKK

2021 ◽  
Vol 6 (5) ◽  
Keyword(s):  
High Specificity ◽  
Dependent Manner ◽  
Thymosin Α1 ◽  
Tnf Α ◽  
Normal Human ◽  
Anti Inflammatory ◽  
Interferon Α2 ◽  
Dose Dependent

We have established that the peptide LKEKK (Np5) corresponding to the sequence 16-20 of thymosin-α1 and to the sequence 131-135 of interferon-α2, in the concentration range 50 300 µg/ear reduces in a dose-dependent manner phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin edema in mice .Tested in parallel peptide with inverted sequence (iNp5, KKEKL, 150-300 µg/ear) was inactive, indicating high specificity of the Np5 action. In the concentration range of 5 20 µM Np5 significantly decrease the TNF-α-induced production by normal human keranocytes of pro-inflammatory mediators IL-6 and IL-1β. Thus, Np5t has a pronounced anti-inflammatory activity in vivo and in vitro.

scholarly journals High molecular weight kininogen inhibits thrombin-induced platelet aggregation and cleavage of aggregin by inhibiting binding of thrombin to platelets

Blood ◽  
1991 ◽  
Vol 77 (3) ◽  
pp. 500-507 ◽  
Author(s):  
RN Puri ◽  
F Zhou ◽  
CJ Hu ◽  
RF Colman ◽  
RW Colman
Keyword(s):  
Molecular Weight ◽  
Platelet Aggregation ◽  
Plasma Concentration ◽  
Human Plasma ◽  
Shape Change ◽  
Dependent Manner ◽  
Normal Human Plasma ◽  
High Molecular Weight Kininogen ◽  
Normal Human ◽  
Dose Dependent

Abstract In this study we show that high molecular weight kininogen (HK) inhibited alpha-thrombin-induced aggregation of human platelets in a dose-dependent manner with complete inhibition occurring at plasma concentration (0.67 mumol/L) of HK. HK (0.67 mumol/L) also completely inhibited thrombin-induced cleavage of aggregin (Mr = 100 Kd), a surface membrane protein that mediates adenosine diphosphate (ADP)- induced shape change, aggregation, and fibrinogen binding. The inhibition of HK was specific for alpha- and gamma-thrombin-induced platelet aggregation, because HK did not inhibit platelet aggregation induced by ADP, collagen, calcium ionophore (A23187), phorbol myristate acetate (PMA), PMA + A23187, or 9,11-methano derivative of prostaglandin H2 (U46619). These effects were explained by the ability of HK, at physiologic concentration, to completely inhibit binding of 125I-alpha-thrombin to washed platelets. As a result of this action of HK, this plasma protein also completely inhibited thrombin-induced secretion of adenosine triphosphate, blocked intracellular rise in Ca2+ in platelets exposed to alpha- and gamma-thrombin, inhibited thrombin- induced platelet shape change, and blocked the ability of thrombin to antagonize the increase in intracellular cyclic adenosine monophosphate (cAMP) levels induced by iloprost. Because elevation of cAMP is known to inhibit binding of thrombin to platelets, we established that HK did not increase the intracellular concentration of platelet cAMP. Finally, HK did not inhibit enzymatic activity of thrombin. To study the role of HK in the plasma environment, we used gamma-thrombin to avoid fibrin formation by alpha-thrombin. Platelet aggregation induced by gamma- thrombin was also inhibited by HK in a dose-dependent manner. The EC50 (concentration to produce 50% of the maximum rate of aggregation) of gamma-thrombin for washed platelets was 7 nmol/L and increased to 102 nmol/L when platelets were suspended in normal human plasma. The EC50 for platelet aggregation induced by alpha-thrombin in plasma deficient in total kininogen was 40 nmol/L. When supplemented with HK at plasma concentration (0.67 mumol/L), the EC50 increased to 90 nmol/L, a value similar to that for normal human plasma. These results indicate that (1) HK inhibits thrombin-induced platelet aggregation and cleavage of aggregin by inhibiting binding of thrombin to platelets; (2) HK is a specific inhibitor of platelet aggregation induced by alpha- and gamma- thrombin; and (3) HK plays a role in modulating platelet aggregation stimulated by alpha-thrombin in plasma.

Presence and Possible Origin of ɛ(γ-Glutamyl)Lysine Isodipeptide in Human Plasma

1992 ◽  
Vol 67 (01) ◽  
pp. 060-062 ◽  
Author(s):  
J Harsfalvi ◽  
E Tarcsa ◽  
M Udvardy ◽  
G Zajka ◽  
T Szarvas ◽  
...  
Keyword(s):  
Human Plasma ◽  
Fibrinolytic Therapy ◽  
Normal Human Plasma ◽  
Normal Human ◽  
Hplc Technique ◽  
Significant Change

Summaryɛ(γ-glutamyl)lysine isodipeptide has been detected in normal human plasma by a sensitive HPLC technique in a concentration of 1.9-3.6 μmol/1. Incubation of in vitro clotted plasma at 37° C for 12 h resulted in an increased amount of isodipeptide, and there was no further significant change when streptokinase was also present. Increased in vivo isodipeptide concentrations were also observed in hypercoagulable states and during fibrinolytic therapy.

Oxygenation of 18-hydroxycorticosterone as the final reaction for aldosterone biosynthesis

1984 ◽  
Vol 107 (3) ◽  
pp. 395-400 ◽  
Author(s):  
Itaru Kojima ◽  
Etsuro Ogata ◽  
Hiroshi Inano ◽  
Bun-ichi Tamaoki
Keyword(s):  
Carbon Monoxide ◽  
Hydroxysteroid Dehydrogenase ◽  
Dependent Manner ◽  
In Vitro Production ◽  
Mitochondrial Preparation ◽  
Final Reaction ◽  
Vitro Production ◽  
Dose Dependent ◽  
Cytochrome P 450

Abstract. Incubation of 18-hydroxycorticosterone with the sonicated mitochondrial preparation of bovine adrenal glomerulosa tissue leads to the production of aldosterone, as measured by radioimmunoassay. The in vitro production of aldosterone from 18-hydroxycorticosterone requires both molecular oxygen and NADPH, and is inhibited by carbon monoxide. Cytochrome P-450 inhibitors such as metyrapone, SU 8000. SU 10603, SKF 525A, amphenone B and spironolactone decrease the biosynthesis of aldosterone from 18-hydroxycorticosterone. These results support the conclusion that the final reaction in aldosterone synthesis from 18-hydroxycorticosterone is catalyzed by an oxygenase, but not by 18-hydroxysteroid dehydrogenase. By the same preparation, the production of [3H]aldosterone but not [3H]18-hydroxycorticosterone from [1,2-3H ]corticosterone is decreased in a dose-dependent manner by addition of non-radioactive 18-hydroxycorticosterone.

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