Down-regulation of neutrophil functions by the ELR+CXC chemokine platelet basic protein

Blood ◽  
2000 ◽  
Vol 96 (9) ◽  
pp. 2965-2972 ◽  
Author(s):  
Jan E. Ehlert ◽  
Andreas Ludwig ◽  
Tobias A. Grimm ◽  
Buko Lindner ◽  
Hans-Dieter Flad ◽  
...  
Keyword(s):  
Amino Acids ◽  
Binding Sites ◽  
Chemokine Receptors ◽  
Cell Activation ◽  
Basic Protein ◽  
Cathepsin G ◽  
Terminal Part ◽  
Down Regulation ◽  
Cxc Chemokine ◽  
Continuous Accumulation

Abstract The platelet-derived neutrophil-activating peptide 2 (NAP-2, 70 amino acids) belongs to the ELR+ CXC subfamily of chemokines. Similar to other members of this group, such as IL-8, NAP-2 activates chemotaxis and degranulation in neutrophils (polymorphonuclear [PMN]) through chemokine receptors CXCR-1 and CXCR-2. However, platelets do not secrete NAP-2 as an active chemokine but as the C-terminal part of several precursors that lack PMN-stimulating capacity. As we have previously shown, PMN themselves may liberate NAP-2 from the precursor connective tissue-activating peptide III (CTAP-III, 85 amino acids) by proteolysis. Instead of inducing cell activation, continuous accumulation of the chemokine in the surroundings of the processing cells results in the down-regulation of specific surface-expressed NAP-2 binding sites and in the desensitization of chemokine-induced PMN degranulation. Thus, NAP-2 precursors may be regarded as indirect mediators of functional desensitization in neutrophils. In the current study we investigated the biologic impact of another major NAP-2 precursor, the platelet basic protein (PBP, 94 amino acids). We show that PBP is considerably more potent than CTAP-III to desensitize degranulation and chemotaxis in neutrophils. We present data suggesting that the high desensitizing capacity of PBP is based on its enhanced proteolytic cleavage into NAP-2 by neutrophil-expressed cathepsin G and that it involves efficient down-regulation of surface-expressed CXCR-2 while CXCR-1 is hardly affected. Correspondingly, we found PBP and, less potently, CTAP-III to inhibit CXCR-2– but not CXCR-1– dependent chemotaxis of neutrophils toward NAP-2. Altogether our findings demonstrate that the anti-inflammatory capacity of NAP-2 is governed by the species of its precursors.

Down-regulation of neutrophil functions by the ELR+CXC chemokine platelet basic protein

Blood ◽  
2000 ◽  
Vol 96 (9) ◽  
pp. 2965-2972 ◽  
Author(s):  
Jan E. Ehlert ◽  
Andreas Ludwig ◽  
Tobias A. Grimm ◽  
Buko Lindner ◽  
Hans-Dieter Flad ◽  
...  
Keyword(s):  
Amino Acids ◽  
Binding Sites ◽  
Chemokine Receptors ◽  
Cell Activation ◽  
Basic Protein ◽  
Cathepsin G ◽  
Terminal Part ◽  
Down Regulation ◽  
Cxc Chemokine ◽  
Continuous Accumulation

The platelet-derived neutrophil-activating peptide 2 (NAP-2, 70 amino acids) belongs to the ELR+ CXC subfamily of chemokines. Similar to other members of this group, such as IL-8, NAP-2 activates chemotaxis and degranulation in neutrophils (polymorphonuclear [PMN]) through chemokine receptors CXCR-1 and CXCR-2. However, platelets do not secrete NAP-2 as an active chemokine but as the C-terminal part of several precursors that lack PMN-stimulating capacity. As we have previously shown, PMN themselves may liberate NAP-2 from the precursor connective tissue-activating peptide III (CTAP-III, 85 amino acids) by proteolysis. Instead of inducing cell activation, continuous accumulation of the chemokine in the surroundings of the processing cells results in the down-regulation of specific surface-expressed NAP-2 binding sites and in the desensitization of chemokine-induced PMN degranulation. Thus, NAP-2 precursors may be regarded as indirect mediators of functional desensitization in neutrophils. In the current study we investigated the biologic impact of another major NAP-2 precursor, the platelet basic protein (PBP, 94 amino acids). We show that PBP is considerably more potent than CTAP-III to desensitize degranulation and chemotaxis in neutrophils. We present data suggesting that the high desensitizing capacity of PBP is based on its enhanced proteolytic cleavage into NAP-2 by neutrophil-expressed cathepsin G and that it involves efficient down-regulation of surface-expressed CXCR-2 while CXCR-1 is hardly affected. Correspondingly, we found PBP and, less potently, CTAP-III to inhibit CXCR-2– but not CXCR-1– dependent chemotaxis of neutrophils toward NAP-2. Altogether our findings demonstrate that the anti-inflammatory capacity of NAP-2 is governed by the species of its precursors.

CXC chemokine ligand 4 (CXCL4) down-regulates CC chemokine receptor expression on human monocytes

2010 ◽  
Vol 18 (1) ◽  
pp. 124-139 ◽  
Author(s):  
Franziska Schwartzkopff ◽  
Frank Petersen ◽  
Tobias Alexander Grimm ◽  
Ernst Brandt
Keyword(s):  
Chemokine Receptors ◽  
Receptor Expression ◽  
Cell Surface Expression ◽  
Human Monocytes ◽  
Down Regulation ◽  
Cc Chemokine ◽  
Tnf Α ◽  
Cxc Chemokine ◽  
Chemokine Ligand ◽  
Chemokine Ligands

During acute inflammation, monocytes are essential in abolishing invading micro-organisms and encouraging wound healing. Recruitment by CC chemokines is an important step in targeting monocytes to the inflamed tissue. However, cell surface expression of the corresponding chemokine receptors is subject to regulation by various endogenous stimuli which so far have not been comprehensively identified. We report that the platelet-derived CXC chemokine ligand 4 (CXCL4), a known activator of human monocytes, induces down-regulation of CC chemokine receptors (CCR) 1, −2, and −5, resulting in drastic impairment of monocyte chemotactic migration towards cognate CC chemokine ligands (CCL) for these receptors. Interestingly, CXCL4-mediated down-regulation of CCR1, CCR2 and CCR5 was strongly dependent on the chemokine’s ability to stimulate autocrine/paracrine release of TNF-α. In turn, TNF-α induced the secretion CCL3 and CCL4, two chemokines selective for CCR1 and CCR5, while the secretion of CCR2-ligand CCL2 was TNF-α-independent. Culture supernatants of CXCL4-stimulated monocytes as well as chemokine-enriched preparations thereof reproduced CXCL4-induced CCR down-regulation. In conclusion, CXCL4 may act as a selective regulator of monocyte migration by stimulating the release of autocrine, receptor-desensitizing chemokine ligands. Our results stress a co-ordinating role for CXCL4 in the cross-talk between platelets and monocytes during early inflammation.

scholarly journals Cathepsin G binding to human platelets. Evidence for a specific receptor

1990 ◽  
Vol 266 (1) ◽  
pp. 55-62 ◽  
Author(s):  
M A Selak ◽  
J B Smith
Keyword(s):  
Binding Sites ◽  
Room Temperature ◽  
Cell Activation ◽  
Human Platelets ◽  
Cathepsin G ◽  
Native Enzyme ◽  
Hill Coefficient ◽  
Specific Receptor ◽  
Binding Studies ◽  
Binding Curves

We have shown previously that purified human neutrophil cathepsin G is a strong platelet agonist. We now demonstrate that cathepsin G exhibits saturable, reversible binding to human platelets which is characteristic of binding to a specific receptor. At room temperature, cathepsin G displayed apparent positive co-operativity of binding, as indicated by sigmoidal binding curves and a Hill coefficient greater than unity. By contrast, binding curves conducted with native enzyme at 0.5 degrees C displayed a much smaller degree of sigmoidicity, and binding studies performed with phenylmethanesulphonyl fluoride-treated enzyme at 22-25 degrees C exhibited hyperbolic binding curves. The concentrations of cathepsin G required to give half-saturation (S0.5) with inhibitor-treated enzyme or with native enzyme at either room temperature or 0.5 degrees C were all similar, suggesting that sigmoidal binding curves did not result from an alteration in the affinity of the binding sites for cathepsin G. However, platelets bound approximately twice as many molecules of native enzyme as molecules of phenylmethanesulphonyl fluoride-treated cathepsin G per cell. From these observations it can be inferred that the apparent positive co-operativity may in part reflect the exposure of binding sites due to the proteolytic activity of cathepsin G. However, this conclusion is not supported by experiments conducted with subsaturating cathepsin G concentrations, which demonstrated that ligand binding did not show an expected increase at longer time intervals. Measurement of Ca2+ mobilization and cathepsin G binding in the same platelet suspensions demonstrated that elevations in cytosolic free Ca2+ concentration had achieved near-maximal levels in the presence of 15 micrograms of cathepsin G/ml, whereas maximal binding was observed at approx. 35 micrograms/ml, indicating that only a fraction of the total binding sites need be occupied to elicit platelet activation. Pretreatment of platelets with forskolin or phorbol 12-myristate 13-acetate (PMA) decreased cathepsin G binding by approx. 60% and 40% respectively, indicating that the receptor may be desensitized or down-regulated by phosphorylation due to protein kinases. Since forskolin and PMA could diminish receptor availability by activating negative feedback mechanisms, inhibition of negative signal-transduction pathways could conversely play a role in the up-regulation of cathepsin G binding. In any event, these results show that cathepsin G is an agonist that must bind to platelets to initiate processes associated with cell activation, and suggest a role for cathepsin G in platelet function.

scholarly journals Down-regulation of T Cell Activation following Inhibition of Dipeptidyl Peptidase IV/CD26 by the N-terminal Part of the Thromboxane A2 Receptor

2000 ◽  
Vol 275 (29) ◽  
pp. 22180-22186 ◽  
Author(s):  
Sabine Wrenger ◽  
Jürgen Faust ◽  
Carmen Mrestani-Klaus ◽  
Annett Fengler ◽  
Angela Stöckel-Maschek ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Terminal Part ◽  
Down Regulation ◽  
Thromboxane A2 Receptor

scholarly journals B Cell–attracting Chemokine 1, a Human CXC Chemokine Expressed in Lymphoid Tissues, Selectively Attracts B Lymphocytes via BLR1/CXCR5

1998 ◽  
Vol 187 (4) ◽  
pp. 655-660 ◽  
Author(s):  
Daniel F. Legler ◽  
Marcel Loetscher ◽  
Regula Stuber Roos ◽  
Ian Clark-Lewis ◽  
Marco Baggiolini ◽  
...  
Keyword(s):  
Amino Acids ◽  
T Lymphocytes ◽  
B Cell ◽  
B Lymphocytes ◽  
Human Blood ◽  
Dna Sequences ◽  
Chemokine Receptors ◽  
Expressed Sequence Tag ◽  
Lymphoid Tissues ◽  
Cxc Chemokine

Although most leukocytes, T lymphocytes in particular, respond to several different chemokines, there is virtually no information on chemokine activities and chemokine receptors in B lymphocytes. A putative chemokine receptor, BLR1, that is expressed in Burkitt's lymphoma cells and B lymphocytes was cloned a few years ago. Deletion of the gene for BLR1 yielded mice with abnormal primary follicles and germinal centers of the spleen and Peyer's patches, reflecting the inability of B lymphocytes to migrate into B cell areas. By screening expressed sequence tag DNA sequences, we have identified a CXC chemokine, termed B cell–attracting chemokine 1 (BCA-1), that is chemotactic for human B lymphocytes. BCA-1 cDNA encodes a protein of 109 amino acids with a leader sequence of 22 residues. The mature protein shares 23–34% identical amino acids with known CXC chemokines and is constitutively expressed in secondary lymphoid organs. BCA-1 was chemically synthesized and tested for activity on murine pre–B cells 300-19 transfected with BLR1 and on human blood B lymphocytes. In transfected cells, BCA-1 induced chemotaxis and Ca2+ mobilization demonstrating that it acts via BLR1. Under the same conditions, no activity was obtained with 10 CXC and 19 CC chemokines, lymphotactin, neurotactin/fractalkine and several other peptide ligands. BCA-1 was also a highly effective attractant for human blood B lymphocytes (which express BLR1), but was inactive on freshly isolated or IL-2–stimulated T lymphocytes, monocytes, and neutrophils. In agreement with the nomenclature rules for chemokine receptors, we propose the term CXCR5 for BLR1. Together with the observed disturbance of B cell colonization in BLR1/ CXCR5-deficient mice, the present results indicate that chemotactic recruitment by locally produced BCA-1 is important for the development of B cell areas of secondary lymphoid tissues.

Neutrophil Elastase Potentiates Cathepsin G-lnduced Platelet Activation

1992 ◽  
Vol 68 (05) ◽  
pp. 570-576 ◽  
Author(s):  
Mary A Selak
Keyword(s):  
Neutrophil Elastase ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Creatine Phosphate ◽  
Dense Granule ◽  
Cathepsin G ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations

SummaryWe have previously demonstrated that human neutrophil cathepsin G is a strong platelet agonist that binds to a specific receptor. This work describes the effect of neutrophil elastase on cathepsin G-induced platelet responses. While platelets were not activated by high concentrations of neutrophil elastase by itself, elastase enhanced aggregation, secretion and calcium mobilization induced by low concentrations of cathepsin G. Platelet aggregation and secretion were potentiated in a concentration-dependent manner by neutrophil elastase with maximal responses observable at 200 nM. Enhancement was observed when elastase was preincubated with platelets for time intervals of 10–60 s prior to addition of a low concentration of cathepsin G and required catalytically-active elastase since phenylmethanesulphonyl fluoride-inhibited enzyme failed to potentiate cell activation. Neutrophil elastase potentiation of platelet responses induced by low concentrations of cathepsin G was markedly inhibited by creatine phosphate/creatine phosphokinase and/or indomethacin, indicating that the synergism between elastase and cathepsin G required the participation of ADP and thromboxane A2. On the other hand, platelet responses were not attenuated by the PAF antagonist BN 52021, signifying that PAF-acether did not play a role in elastase potentiation. At higher concentrations porcine pancreatic elastase exhibits similar effects to neutrophil elastase, demonstrating that the effect of elastase was not unique to the neutrophil protease. While neutrophil elastase failed to alter the ability of cathepsin G to hydrolyze a synthetic chromogenic substrate, preincubation of platelets with elastase increased the apparent affinity of cathepsin G binding to platelets. In contrast to their effect on cathepsin G-induced platelet responses, neither neutrophil nor pancreatic elasatse potentiated aggregation or dense granule release initiated by ADP, PAF-acether, arachidonic acid or U46619, a thromboxane A2 mimetic. Moreover, unlike its effect on cathepsin G, neutrophil elastase inhibited thrombin-induced responses. The current observations demonstrate that elastase can potentiate platelet responses mediated by low concentrations of cathepsin G, suggesting that both enzymes may function synergistically to activate platelets under conditions where neutrophil degranulation occurs.

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