Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chemokine receptors are rapidly desensitized and internalized following ligand binding, a process that attenuates receptor-mediated responses. However, the physiological settings in which this process occurs are not clear. Therefore, we examined the fate of CXCR3, a chemokine receptor preferentially expressed on activated T cells following contact with endothelial cells. By immunofluorescence microscopy and flow cytometry, we found that CXCR3 was rapidly internalized when T cells were incubated with IFN-gamma-activated human saphenous vein endothelial cells (HSVEC), but not with resting HSVEC. Similar results were obtained using human CXCR3-transfected murine 300-19 B cells. CXCR3 down-regulation was significantly more pronounced when T cells were in contact with HSVEC than with their supernatants, suggesting that CXCR3 ligands were efficiently displayed on the surface of HSVEC. Using neutralizing mAbs to IFN-induced protein-10 (CXCL10), monokine induced by IFN-gamma (CXCL9), and IFN-inducible T cell alpha chemoattractant (I-TAC; CXCL11), we found that even though I-TAC was secreted from IFN-gamma-activated HSVEC to lower levels than IFN-induced protein-10 or the monokine induced by IFN-gamma, it was the principal chemokine responsible for CXCR3 internalization. This correlated with studies using recombinant chemokines, which revealed that I-TAC was the most potent inducer of CXCR3 down-regulation and of transendothelial migration. Known inhibitors of chemokine-induced chemotaxis, such as pertussis toxin or wortmannin, did not reduce ligand-induced internalization, suggesting that a distinct signal transduction pathway mediates internalization. Our data demonstrate that I-TAC is the physiological inducer of CXCR3 internalization and suggest that chemokine receptor internalization occurs in physiological settings, such as leukocyte contact with an activated endothelium.
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PMID:CXCR3 internalization following T cell-endothelial cell contact: preferential role of IFN-inducible T cell alpha chemoattractant (CXCL11). 1173 30

The CC chemokine eotaxin/CCL11 is known to bind to the receptor CCR3 on eosinophils and Th2-type lymphocytes. In this study, we demonstrate that CCR3 is expressed on a subpopulation of primary human dermal microvascular endothelial cells and is up-regulated by TNF-alpha. We found that incubation of human dermal microvascular endothelial cells with recombinant eotaxin/CCL11 suppresses TNF-alpha-induced production of the neutrophil-specific chemokine IL-8/CXCL8. The eotaxin/CCL11-suppressive effect on endothelial cells was not seen on IL-1beta-induced IL-8/CXCL8 release. Eotaxin/CCL11 showed no effect on TNF-alpha-induced up-regulation of growth-related oncogene-alpha or IFN-gamma-inducible protein-10, two other CXC chemokines tested, and did not affect production of the CC chemokines monocyte chemoattractant protein-1/CCL2 and RANTES/CCL5, or the adhesion molecules ICAM-1 and E-selectin. These results suggest that eotaxin/CXCL11 is not effecting a general suppression of TNF-alphaR levels or signal transduction. Suppression of IL-8/CXCL8 was abrogated in the presence of anti-CCR3 mAb, pertussis toxin, and wortmannin, indicating it was mediated by the CCR3 receptor, G(i) proteins, and phosphatidylinositol 3-kinase signaling. Eotaxin/CCL11 decreased steady state levels of IL-8/CXCL8 mRNA in TNF-alpha-stimulated cells, an effect mediated in part by an acceleration of IL-8 mRNA decay. Eotaxin/CCL11 may down-regulate production of the neutrophil chemoattractant IL-8/CXCL8 by endothelial cells in vivo, acting as a negative regulator of neutrophil recruitment. This may play an important biological role in the prevention of overzealous inflammatory responses, aiding in the resolution of acute inflammation or transition from neutrophilic to mononuclear/eosinophilic inflammation.
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PMID:Eotaxin/CCL11 suppresses IL-8/CXCL8 secretion from human dermal microvascular endothelial cells. 1188 59

The chemokines CXCL9, 10, and 11 exert their action via CXC chemokine receptor-3 (CXCR3), a receptor highly expressed on activated T cells. These interferon gamma (IFNgamma)-induced chemokines are thought to be crucial in directing activated T cells to sites of inflammation. As such, they play an important role in several chronic inflammatory diseases including ulcerative colitis, multiple sclerosis, artherosclerosis, and delayed-type hypersensitivity reactions of the skin. In this study, we first demonstrate that in COS-7 cells heterologously expressing CXCR3, CXCL11 is a potent activator of the pertussis toxin (PTX)-sensitive p44/p42 mitogen-activated protein kinase (MAPK) and Akt/phosphatidylinositol 3 kinase (PI3K) pathways. Next, we show that these signal transduction pathways are also operative and PTX sensitive in primary human T cells expressing CXCR3. Importantly, abrogation of these signaling cascades by specific inhibitors did not block the migration of T cells toward CXCR3 ligands, suggesting that MAPK and Akt activation is not crucial for CXCR3-mediated chemotaxis of T cells. Finally, we demonstrate that CXCR3-targeting chemokines control T-cell migration via PTX-sensitive, phospholipase C pathways and phosphatidylinositol kinases other than class I PI3Kgamma.
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PMID:CXCR3-mediated chemotaxis of human T cells is regulated by a Gi- and phospholipase C-dependent pathway and not via activation of MEK/p44/p42 MAPK nor Akt/PI-3 kinase. 1275 Jan 73

The mechanism by which osteoblasts (OB) interact and modulate the phenotype and proliferation of T lymphocytes during inflammation is not well known. The effects of two regulatory cytokines, TNFalpha and IFNgamma, on the expression of CD54 (ICAM-1) and CD106 (VCAM-1) adhesion molecules and the CXCR3 ligands (CXCL9, CXCL10, CXCL11), were assessed in a primary culture of human OB by real-time PCR, flow cytometry, and immunohistochemistry. In addition, we functionally evaluated the recruitment and proliferation of T lymphocytes grown with resting or stimulated OB. According to the present data IFNgamma, either alone or in combination with TNFalpha, significantly up-regulates the expression of CD54 and CD106 and induces the expression and release of CXCL9, CXCL10, CXCL11 in OB. The supernatant of TNFalpha- and IFNgamma-activated OB induces the recruitment of T lymphocytes more significantly than stimulation by CXCR3 ligands. T lymphocyte proliferation is significantly enhanced by direct contact with TNFalpha- and IFNgamma-activated OB or by incubation with the supernatant of TNFalpha- and IFNgamma-activated OB. Blocking experiments with anti-CD11a, anti-CD49d, anti-CXCR3, and Bordetella pertussis toxin demonstrate that adhesion molecules and the CXCR3 chemokine receptor play a key role in the proliferation of T lymphocytes. The present study demonstrates the involvement of adhesion molecules (CD11a and CD49d) and chemokine receptor (CXCR3) in the mechanism by which OB recruit, interact, and modulate T lymphocyte proliferation under inflammatory conditions.
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PMID:Recruitment and proliferation of T lymphocytes is supported by IFNgamma- and TNFalpha-activated human osteoblasts: Involvement of CD54 (ICAM-1) and CD106 (VCAM-1) adhesion molecules and CXCR3 chemokine receptor. 1475 44

We demonstrate the expression of S1P(1,3,4,5) the receptors for sphingosine 1-phosphate (S1P), and LPA(1,2,3) the receptors for lysophosphatidic acid (LPA) in T helper 1 (Th1) and T helper 2 (Th2) cells. S1P and LPA induce the chemotaxis of Th1 and Th2 cells, an activity that is resistant to pertussis toxin (PTX) pretreatment in Th1, but is sensitive in Th2 cells. Also, I-TAC-induced Th1 and eotaxin-induced Th2 cell chemotaxis are blocked by PTX pretreatment. LPA but not S1P induces calcium flux response in Th1 and Th2 cells, which is due to the influx of extracellular calcium and is mediated by receptor activation, since EGTA and suramin (SUR) completely abrogate LPA-induced the release of calcium. No cross-desensitization is observed between thapsigargin (TG) and LPA in both cell types. PTX and SUR but not EGTA inhibit I-TAC- or eotaxin-induced [Ca(2+)](i) release in Th1 and Th2 cells. Our results indicate that lysophospholipids and chemokines stimulate different signal transduction pathways.
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PMID:Lysophospholipids and chemokines activate distinct signal transduction pathways in T helper 1 and T helper 2 cells. 1521 60

Uridine nucleotides and UDP-glucose are endogenous molecules, which are released into the extracellular environment in a lytic manner after cell damage, as well as by regulated nonlytic mechanisms. Recently, a UDP-glucose-specific G(i) protein-coupled P2Y receptor, namely P2Y(14), has been cloned. In this study, we demonstrated expression of the P2Y(14) mRNA in human lung epithelial cells and in the epithelial cell lines A549 and BEAS-2B. Evidence of functional expression of the P2Y(14) receptor in these cell lines was provided by calcium measurements after stimulation with uridine 5'-diphosphoglucose (UDP-glc). Experiments with pertussis toxin and the Ca(2+)-chelator EGTA revealed participation of pertussis toxin-sensitive G(i/o)-proteins in the mobilization of Ca(2+)-ions from intracellular stores by UDP-glc. Moreover, UDP-glc increased secretion of the potent neutrophil chemoattractant CXCL8/IL-8 in A549 and BEAS-2B cells in a pertussis toxin-sensitive manner. Moreover, reverse transcription and quantitative polymerase chain reaction revealed that UDP-glc modulated mRNA levels of IL-8/CXCL8. However, stimulation of A549 and BEAS-2B cells with UDP-glc neither modified basal nor cytokine-induced secretion of the CXC-chemokines CXCL9/MIG, CXCL10/IP-10, and CXCL11/I-TAC. In addition, UDP-glc did not affect proliferation of the two cell lines. In summary, our data provide evidence for a distinct physiologic role of P2Y(14) in the selective release of specific chemokines from human airway epithelial cells.
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PMID:The P2Y14 receptor of airway epithelial cells: coupling to intracellular Ca2+ and IL-8 secretion. 1610 83

Intestinal myofibroblasts have been implicated in the pathogenesis of chronic inflammatory conditions such as Crohn's disease via interactions with an elaborate network of cytokines, growth factors, and other inflammatory mediators. CXCR3 is a Galpha(i) protein-coupled receptor that binds the proinflammatory chemokines CXCL9, CXCL10, and CXCL11, which are released from the intestinal epithelium. The three CXCR3 ligands shared the ability to activate biochemical (e.g., PI3K and MAPK activation) and functional events (actin reorganization) in intestinal myofibroblasts. However, CXCL11 is unique in its ability to elevate intracellular calcium. Surprisingly, although CXCR3 mRNA is detectable in these myofibroblasts, there is no detectable surface expression of CXCR3. Furthermore, the biochemical responses and actin reorganization stimulated by the CXCR3 ligands in intestinal myofibroblasts are insensitive to the Galpha(i) inhibitor, pertussis toxin. This suggests either the existence of differential receptor coupling mechanisms in myofibroblasts for CXCR3 that are distinct from those observed in PBLs and/or that these cells express a modified or variant CXCR3 compared with the CXCR3 expressed on PBLs.
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PMID:The chemokines CXCL9, CXCL10, and CXCL11 differentially stimulate G alpha i-independent signaling and actin responses in human intestinal myofibroblasts. 1621 Jun 47

The chemokine receptor CXCR3 is predominantly expressed on activated T and natural killer (NK) cells. CXCR3 and its ligands, CXCL11, CXCL10, and CXCL9, play a major role in T-helper 1 (Th1)-dependent inflammatory responses. CXCL11 is the most dominant physiological inducer of adhesion, migration, and internalization of CXCR3. To study the role of CXCR3 carboxyl-terminus and the third intracellular (3i) loop in chemokine-mediated migration, adhesion, and CXCR3 internalization, we generated CXCR3 receptors mutated in their distal (Ser-Thr domain) or proximal (trileucine domain) membrane carboxyl terminus, and/or the third intracellular loop. We found that migration of CXCR3-expressing HEK 293 cells toward CXCL11 was pertussis toxin-dependent and required the membrane proximal carboxyl terminus of CXCR3. Internalization induced by CXCL11 and protein kinase C (PKC) activation was also regulated by the membrane proximal carboxyl terminus; however, only CXCL11-induced internalization required the LLL motif of this region. Internalization and Ca(2+) flux induced by CXCL11 were independent of the 3i loop S245, whereas migration at high CXCL11 concentrations, integrin-dependent adhesion, and actin polymerization were S245 dependent. Our findings indicate that CXCL11-dependent CXCR3 internalization and cell migration are regulated by the CXCR3 membrane proximal carboxyl terminus, whereas adhesion is regulated by the 3i loop S245. Thus, distinct conformational changes induced by a given CXCR3 ligand trigger different downstream effectors of adhesion, motility, and CXCR3 desensitization.
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PMID:Role of CXCR3 carboxyl terminus and third intracellular loop in receptor-mediated migration, adhesion and internalization in response to CXCL11. 1636 92

Human airway epithelial cells (HAEC) constitutively express the CXC chemokine receptor CXCR3, which regulates epithelial cell movement. In diseases such as chronic obstructive pulmonary disease and asthma, characterized by denudation of the epithelial lining, epithelial cell migration may contribute to airway repair and reconstitution. This study compared the potency and efficacy of three CXCR3 ligands, I-TAC/CXCL11, IP-10/CXCL10, and Mig/CXCL9, as inducers of chemotaxis in HAEC and examined the underlying signaling pathways involved. Studies were performed in cultured HAEC from normal subjects and the 16-HBE cell line. In normal HAEC, the efficacy of I-TAC-induced chemotaxis was 349 +/- 88% (mean +/- SE) of the medium control and approximately one-half the response to epidermal growth factor, a highly potent chemoattractant. In normal HAEC, Mig, IP-10, and I-TAC induced chemotaxis with similar potency and a rank order of efficacy of I-TAC = IP-10 > Mig. Preincubation with pertussis toxin completely blocked CXCR3-induced migration. Of interest, intracellular [Ca(2+)] did not rise in response to I-TAC, IP-10, or Mig. I-TAC induced a rapid phosphorylation (5-10 min) of two of the three MAPKs, i.e., p38 and ERK1/2. Pretreatment of HAEC with the p38 inhibitor SB 20358 or the PI3K inhibitor wortmannin dose-dependently inhibited the chemotactic response to I-TAC. In contrast, the ERK1/2 inhibitor U0126 had no effect on chemotaxis. These data indicate that in HAEC, CXCR3-mediated chemotaxis involves a G protein, which activates both the p38 MAPK and PI3K pathways in a calcium-independent fashion.
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PMID:CXCR3 chemokine receptor-induced chemotaxis in human airway epithelial cells: role of p38 MAPK and PI3K signaling pathways. 1646 4

G protein-coupled receptors (GPCRs) convey extracellular stimulation into dynamic intracellular action, leading to the regulation of cell migration and differentiation. T lymphocytes express G alpha(i2) and G alpha(i3), two members of the G alpha(i/o) protein family, but whether these two G alpha(i) proteins have distinguishable roles guiding T cell migration remains largely unknown because of a lack of member-specific inhibitors. This study details distinct G alpha(i2) and G alpha(i3) effects on chemokine receptor CXCR3-mediated signaling. Our data showed that G alpha(i2) was indispensable for T cell responses to three CXCR3 ligands, CXCL9, CXCL10, and CXCL11, as the lack of G alpha(i2) abolished CXCR3-stimulated migration and guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) incorporation. In sharp contrast, T cells isolated from G alpha(i3) knock-out mice displayed a significant increase in both GTPgammaS incorporation and migration as compared with wild type T cells when stimulated with CXCR3 agonists. The increased GTPgammaS incorporation was blocked by G alpha(i3) protein in a dose-dependent manner. G alpha(i3)-mediated blockade of G alpha(i2) activation did not result from G alpha(i3) activation, but instead resulted from competition or steric hindrance of G alpha(i2) interaction with the CXCR3 receptor via the N terminus of the second intracellular loop. A mutation in this domain abrogated not only G alpha(i2) activation induced by a CXCR3 agonist but also the interaction of G alpha(i3) to the CXCR3 receptor. These findings reveal for the first time an interplay of G alpha(i) proteins in transmitting G protein-coupled receptor signals. This interplay has heretofore been masked by the use of pertussis toxin, a broad inhibitor of the G alpha(i/o) protein family.
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PMID:Inhibition of G alpha i2 activation by G alpha i3 in CXCR3-mediated signaling. 1728 75


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