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At least 343 records · Page 19Linked to original sources
PubMed2003

Microarray analysis of tumor necrosis factor alpha induced gene expression in U373 human glioblastoma cells.

BACKGROUND: Tumor necrosis factor alpha (TNF) is able to induce a variety of biological responses in the nervous system including inflammation and neuroprotection. Human astrocytoma cells U373 have been widely used as a model for inflammatory cytokine actions in the nervous system. Here we used cDNA microarrays to analyze the time course of the transcriptional response from 1 h up to 12 h post TNF treatment in comparison to untreated U373 cells. TNF activated strongly the NF-kappaB transcriptional pathway and is linked to other pathways via the NF-kappaB target genes JUNB and IRF-1. Part of the TNF-induced gene expression could be inhibited by pharmacological inhibition of NF-kappaB with pyrrolidine-dithiocarbamate (PDTC). NF-kappaB comprises a family of transcription factors which are involved in the inducible expression of genes regulating neuronal survival, inflammatory response, cancer and innate immunity. RESULTS: In this study we show that numerous genes responded to TNF (> 880 from 7500 tested) with a more than two-fold induction rate. Several novel TNF-responsive genes (about 60% of the genes regulated by a factor > or = 3) were detected. A comparison of our TNF-induced gene expression profiles of U373, with profiles from 3T3 and Hela cells revealed a striking cell-type specificity. SCYA2 (MCP-1, CCL2, MCAF) was induced in U373 cells in a sustained manner and at the highest level of all analyzed genes. MCP-1 protein expression, as monitored with immunofluorescence and ELISA, correlated exactly with microarray data. Based on these data and on evidence from literature we suggest a model for the potential neurodegenerative effect of NF-kappaB in astroglia: Activation of NF-kappaB via TNF results in a strongly increased production of MCP-1. This leads to a exacerbation of neurodegeneration in stoke or Multiple Sclerosis, presumably via infiltration of macrophages. CONCLUSIONS: The vast majority of genes regulated more than 3-fold were previously not linked to tumor necrosis factor alpha as a search in published literature revealed. Striking co-regulation for several functional groups such as proteasome and ribosomal proteins were detected.

Cell Line, Tumor↗
PubMed2006

An investigation of polymorphisms in the 17q11.2-12 CC chemokine gene cluster for association with multiple sclerosis in Australians.

BACKGROUND: Multiple sclerosis (MS) is a disorder of the central nervous system (CNS) characterised by inflammation and neuronal degeneration. It is believed to result from the complex interaction of a number of genes, each with modest effect. Chemokines are vital to the migration of cells to sites of inflammation, including the CNS, and many are implicated in MS pathogenesis. Most of the CC chemokine genes are encoded in a cluster on chromosome 17q11.2-12, which has been identified in a number of genome wide screens as being potentially associated with MS. METHODS: We conducted a two-stage analysis to investigate the chemokine gene cluster for association with MS. After sequencing the chemokine genes in several DNA pools to identify common polymorphisms, 12 candidate single-nucleotide polymorphisms (SNPs) were genotyped in a cohort of Australian MS trio families. RESULTS: Marginally significant (uncorrected) transmission distortion was identified for four of the SNPs after stratification for several factors. We also identified marginally significant (uncorrected) transmission distortion for haplotypes encompassing the CCL2 and CCL11 genes, using two independent cohorts, which was consistent with recent reports from another group. CONCLUSION: Our results implicate several chemokines as possibly being associated with MS susceptibility, and given that chemokines and their receptors are suitable targets for therapeutic agents, further investigation is warranted in this region.

Australia↗
PubMed2005

TNF-alpha-induced chemokine production and apoptosis in human neural precursor cells.

Recent studies have shown that proinflammatory cytokines damage rodent neural precursor cells (NPCs), a source of self-renewing, multipotent cells that play an important role in the developing as well as adult brain. In this study, the effects of tumor necrosis factor alpha (TNF-alpha) on cytokine and chemokine production by human NPCs (>98% nestin- and >90% A2B5-positive), obtained from 6- to 8-week-old fetal brain specimens, were evaluated. NPCs stimulated with this proinflammatory cytokine were found to produce abundant amounts of the chemokines monocyte chemoattractant protein 1 (MCP-1)/CC chemokine ligand 2 (CCL2) and interferon-inducible protein 10 (IP-10)/CXC chemokine ligand 10 (CXCL10) in a time- and concentration-dependent manner. TNF-alpha treatment also induced NPC apoptosis. Receptors for TNF [TNFRI (p55) and TNFRII (p75)] mRNA were constitutively expressed on NPCs. However, only TNFRI was involved in TNF-alpha-induced chemokine production and apoptosis by NPCs, as anti-TNFRI but not anti-TNFRII antibodies blocked the stimulatory effect. TNF-alpha treatment induced p38 mitogen-activated protein kinase (MAPK) phosphorylation in NPCs, and SB202190, an inhibitor of p38 MAPK, blocked TNF-alpha-induced chemokine production. Thus, this study demonstrated that NPCs constitutively express receptors for TNF-alpha, which when activated, trigger via a p38 MAPK signaling pathway production of two chemokines, MCP-1/CCL2 and IP-10/CXCL10, which are involved in infectious and inflammatory diseases of the brain.

Apoptosis↗
PubMed2004

MCP-1-dependent signaling in CCR2(-/-) aortic smooth muscle cells.

Monocyte chemoattractant protein-1 (MCP-1, CCL2) is a mediator of inflammation that has been implicated in the pathogenesis of a wide variety of human diseases. CCR2, a heterotrimeric G-coupled receptor, is the only known receptor that functions at physiologic concentrations of MCP-1. Despite the importance of CCR2 in mediating MCP-1 responses, several recent studies have suggested that there may be another functional MCP-1 receptor. Using arterial smooth muscle cells (SMC) from CCR2(-/-) mice, we demonstrate that MCP-1 induces tissue-factor activity at physiologic concentrations. The induction of tissue factor by MCP-1 is blocked by pertussis toxin and 1,2-bis(O-aminophenyl-ethane-ethan)-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, suggesting that signal transduction through the alternative receptor is G(alphai)-coupled and dependent on mobilization of intracellular Ca(2+). MCP-1 induces a time- and concentration-dependent phosphorylation of the mitogen-activated protein kinases p42/44. The induction of tissue factor activity by MCP-1 is blocked by PD98059, an inhibitor of p42/44 activation, but not by SB203580, a selective p38 inhibitor. These data establish that SMC possess an alternative MCP-1 receptor that signals at concentrations of MCP-1 that are similar to those that activate CCR2. This alternative receptor may be important in mediating some of the effects of MCP-1 in atherosclerotic arteries and in other inflammatory processes.

Animals↗
PubMed2003

Migration of human blood dendritic cells across endothelial cell monolayers: adhesion molecules and chemokines involved in subset-specific transmigration.

Distinct subsets of dendritic cells (DCs) are present in blood, probably "en route" to different tissues. We have investigated the chemokines and adhesion molecules involved in the migration of myeloid (CD11c(+)) and plasmacytoid (CD123(+)) human peripheral blood DCs across vascular endothelium. Among blood DCs, the CD11c(+) subset vigorously migrated across endothelium in the absence of any chemotactic stimuli, whereas spontaneous migration of CD123(+) DCs was limited. In bare cell migration assays, myeloid DCs responded with great potency to several inflammatory and homeostatic chemokines, whereas plasmacytoid DCs responded poorly to all chemokines tested. In contrast, the presence of endothelium greatly favored transmigration of plasmacytoid DCs in response to CXCL12 (stromal cell-derived factor-1) and CCL5 (regulated on activation, normal T expressed and secreted). Myeloid DCs exhibited a very potent transendothelial migration in response to CXCL12, CCL5, and CCL2 (monocyte chemoattractant protein-1). Furthermore, we explored whether blood DCs acutely switch their pattern of migration to the lymph node-derived chemokine CCL21 (secondary lymphoid-tissue chemokine) in response to microbial stimuli [viral double-stranded (ds)RNA or bacterial CpG-DNA]. A synthetic dsRNA rapidly enhanced the response of CD11c(+) DCs to CCL21, whereas a longer stimulation with CpG-DNA was needed to trigger CD123(+) DCs responsive to CCL21. Use of blocking monoclonal antibodies to adhesion molecules revealed that both DC subsets used platelet endothelial cell adhesion molecule-1 to move across activated endothelium. CD123(+) DCs required beta(2) and beta(1) integrins to transmigrate, whereas CD11c(+) DCs may use integrin-independent mechanisms to migrate across activated endothelium.

Antibodies, Monoclonal↗
PubMed2005

Viral double-stranded RNA aggravates lupus nephritis through Toll-like receptor 3 on glomerular mesangial cells and antigen-presenting cells.

How viral infections trigger autoimmunity is poorly understood. A role for Toll-like receptor 3 (TLR3) was hypothesized in this context as viral double-stranded RNA (dsRNA) activates dendritic cells to secrete type I interferons and cytokines that are known to be associated with the disease activity in systemic lupus erythematosus (SLE). Immunostaining of nephritic kidney sections of autoimmune MRL(lpr/lpr) mice revealed TLR3 expression in infiltrating antigen-presenting cells as well as in glomerular mesangial cells. TLR3-positive cultured mesangial cells that were exposed to synthetic polyinosinic-cytidylic acid (pI:C) RNA in vitro produced CCL2 and IL-6. pI:C RNA activated macrophages and dendritic cells, both isolated from MRL(lpr/lpr) mice, to secrete multiple proinflammatory factors. In vivo, a single injection of pI:C RNA increased serum IL-12p70, IL-6, and IFN-alpha levels. A course of 50 microg of pI:C RNA given every other day from weeks 16 to 18 of age aggravated lupus nephritis in pI:C-treated MRL(lpr/lpr) mice. Serum DNA autoantibody levels were unaltered upon systemic exposure to pI:C RNA in MRL(lpr/lpr) mice, as pI:C RNA, in contrast to CpG-DNA, failed to induce B cell activation. It therefore was concluded that viral dsRNA triggers disease activity of lupus nephritis by mechanisms that are different from those of bacterial DNA. In contrast to CpG-DNA/TLR9 interaction, pI:C RNA/TLR3-mediated disease activity is B cell independent, but activated intrinsic renal cells, e.g., glomerular mesangial cells, to produce cytokines and chemokines, factors that can aggravate autoimmune tissue injury, e.g., lupus nephritis.

Animals↗
PubMed2000

Defective expression of the monocyte chemotactic protein-1 receptor CCR2 in macrophages associated with human ovarian carcinoma.

Monocyte chemotactic protein-1 (MCP-1, CCL2) is an important determinant of macrophage infiltration in tumors, ovarian carcinoma in particular. MCP-1 binds the chemokine receptor CCR2. Recent results indicate that proinflammatory and anti-inflammatory signals regulate chemokine receptor expression in monocytes. The present study was designed to investigate the expression of CCR2 in tumor-associated macrophages (TAM) from ovarian cancer patients. TAM isolated from ascitic or solid ovarian carcinoma displayed defective CCR2 mRNA (Northern blot and PCR) and surface expression and did not migrate in response to MCP-1. The defect was selective for CCR2 in that CCR1 and CCR5 were expressed normally in TAM. CCR2 gene expression and chemotactic response to MCP-1 were decreased to a lesser extent in blood monocytes from cancer patients. CCR2 mRNA levels and the chemotactic response to MCP-1 were drastically reduced in fresh monocytes cultured in the presence of tumor ascites from cancer patients. Ab against TNF-alpha restored the CCR2 mRNA level in monocytes cultured in the presence of ascitic fluid. The finding of defective CCR2 expression in TAM, largely dependent on local TNF production, is consistent with previous in vitro data on down-regulation of chemokine receptors by proinflammatory molecules. Receptor inhibition may serve as a mechanism to arrest and retain recruited macrophages and to prevent chemokine scavenging by mononuclear phagocytes at sites of inflammation and tumor growth. In the presence of advanced tumors or chronic inflammation, systemic down-regulation of receptor expression by proinflammatory molecules leaking in the systemic circulation may account for defective chemotaxis and a defective capacity to mount inflammatory responses associated with advanced neoplasia.

Ascites↗
PubMed2003

C-C chemokine ligand 2/monocyte chemoattractant protein-1 directly inhibits NKT cell IL-4 production and is hepatoprotective in T cell-mediated hepatitis in the mouse.

T cell-mediated liver diseases are associated with elevated serum levels of C-C chemokine ligand 2 (CCL2)/monocyte chemoattractant protein-1 (MCP-1). However, the extent to which the actions of CCL2/MCP-1 contribute to the pathogenesis of T cell-mediated hepatitis remains incompletely understood. Con A-induced hepatitis is a liver-specific inflammation mediated by activated T cells and is driven by an up-regulation of the hepatic expression of TNF-alpha, IFN-gamma, and IL-4. The present study examined the role of CCL2/MCP-1 in the pathogenesis of T cell-mediated hepatitis induced by Con A administration in the mouse. We demonstrate a novel hepatoprotective role for CCL2/MCP-1 during Con A-induced hepatitis, because CCL2/MCP-1 neutralization strikingly enhanced hepatic injury, both biochemically and histologically, after Con A administration. Furthermore, CCL2/MCP-1 neutralization was associated with a significant reduction in the hepatic levels of TNF-alpha and IFN-gamma, but with a significant increase in hepatic IL-4 levels. Moreover, IL-4 production and CCR2 expression by Con A-stimulated CD3(+)NK1.1(+) T cells was significantly reduced by rMCP-1 treatment in vitro. In summary, we propose that CCL2/MCP-1 fulfills a novel anti-inflammatory role in T cell-mediated hepatitis by inhibiting CD3(+)NK1.1(+) T cell-derived IL-4 production through direct stimulation of its specific receptor CCR2. These findings may have direct clinical relevance to T cell-mediated hepatitis.

Animals↗
PubMed2003

Host response to malaria during pregnancy: placental monocyte recruitment is associated with elevated beta chemokine expression.

Malaria during pregnancy is associated with poor birth outcomes, particularly low birth weight. Recently, monocyte infiltration into the placental intervillous space has been identified as a key risk factor for low birth weight. However, the malaria-induced chemokines involved in recruiting and activating placental monocytes have not been identified. In this study, we determined which chemokines are elevated during placental malaria infection and the association between chemokine expression and placental monocyte infiltration. Placental malaria infection was associated with elevations in mRNA expression of three beta chemokines, macrophage-inflammatory protein 1 (MIP-1) alpha (CCL3), monocyte chemoattractant protein 1 (MCP-1; CCL2), and I-309 (CCL1), and one alpha chemokine, IL-8 (CXCL8); all correlated with monocyte density in the placental intervillous space. Placental plasma concentrations of MIP-1 alpha and IL-8 were increased in women with placental malaria and were associated with placental monocyte infiltration. By immunohistochemistry, we localized placental chemokine production in malaria-infected placentas: some but not all hemozoin-laden maternal macrophages produced MIP-1 beta and MCP-1, and fetal stromal cells produced MCP-1. In sum, local placental production of chemokines is increased in malaria, and may be an important trigger for monocyte accumulation in the placenta.

Birth Weight↗
PubMed2003

Blocking the monocyte chemoattractant protein-1/CCR2 chemokine pathway induces permanent survival of islet allografts through a programmed death-1 ligand-1-dependent mechanism.

Islet allografts are subject to rapid rejection through host cellular immune responses involving mononuclear cell recruitment and tissue injury. Interruption of leukocyte recruitment through chemokine receptor targeting is of therapeutic benefit in various experimental models, but little is known about the contribution of chemokine pathways to islet allograft rejection. We found that murine islets produce monocyte chemoattractant protein-1 (MCP-1; CCL2) in vitro and that islet allograft rejection was associated with intragraft expression of MCP-1 and its receptor, CCR2. We therefore investigated whether MCP-1 and CCR2 are required for the rejection of fully MHC-disparate islet allografts. Wild-type mice treated with blocking anti-MCP-1 mAb plus a brief, subtherapeutic course of rapamycin had long-term islet allograft survival, in contrast to the effect of treatment with either mAb or rapamycin alone. CCR2(-/-) mice treated with rapamycin also maintained islet allografts long-term. Both MCP/CCR2- and rapamycin-sensitive signals were required for maximal proliferation of alloreactive T cells, suggesting that MCP-1/CCR2 induce rejection by promoting alloreactive T cell clonal expansion and homing and migration. Prolonged islet allograft survival achieved by blockade of the MCP-1/CCR2 pathway plus rapamycin therapy was accompanied by a mononuclear cell infiltrate expressing the inhibitory receptor, programmed death-1 (PD-1), and its ligand (PD-L1, B7-H1), and prolongation of islet allograft survival was abrogated by anti-PD-L1 mAb therapy. These data show that the blockade of MCP-1 binding to CCR2 in conjunction with subtherapeutic immunosuppression can have profound effects on islet allograft survival and implicate the expression of the PD-1/PD-L1 pathway in the regulation of physiologic responses in vivo.

Animals↗
PubMed2004

Essential contribution of monocyte chemoattractant protein-1/C-C chemokine ligand-2 to resolution and repair processes in acute bacterial pneumonia.

Neutrophil infiltration is the first step in eradication of bacterial infection, but neutrophils rapidly die after killing bacteria. Subsequent accumulation of macrophage lineage cells, such as alveolar macrophages (AMs), is essential to remove dying neutrophils, which are a source of injurious substances. Macrophage lineage cells can promote tissue repair, by producing potential growth factors including hepatocyte growth factor (HGF). However, it remains elusive which factor activates macrophage in these processes. Intratracheal instillation of Pseudomonas aeruginosa caused neutrophil infiltration in the airspace; subsequently, the numbers of total AMs and neutrophil ingested AMs were increased. Bronchoalveolar lavage (BAL) fluid levels of monocyte chemoattractant protein (MCP)-1/CC chemokine ligand-2 (CCL2), a potent macrophage-activating factor, were increased before the increases in the number of AM ingesting neutrophils and HGF levels in BAL fluid. Immunoreactive MCP-1 proteins were detected in alveolar type II epithelial cells and AMs only after P. aeruginosa infection. The administration of anti-MCP-1/CCL2 Abs reduced the increases in the number of AM-ingesting neutrophils and HGF levels in BAL fluid, and eventually aggravated lung tissue injury. In contrast, the administration of MCP-1/CCL2 enhanced the increases in the number of AM ingesting neutrophils and HGF levels in BAL fluid, and eventually attenuated lung tissue injury. Furthermore, MCP-1/CCL2 enhanced the ingestion of apoptotic neutrophils and HGF production by a mouse macrophage cell line, RAW 267.4, in a dose-dependent manner. Collectively, MCP-1/CCL2 has a crucial role in the resolution and repair processes of acute bacterial pneumonia by enhancing the removal of dying neutrophils and HGF production by AMs.

Acute Disease↗
PubMed2004

Unusual chemokine receptor antagonism involving a mitogen-activated protein kinase pathway.

Antagonism of chemokines on chemokine receptors constitutes a new regulatory principle in inflammation. Eotaxin (CCL11), an agonist for CCR3 and an attractant of eosinophils, basophils, and Th2 lymphocytes, was shown to act as an antagonist for CCR2, which is widely expressed on leukocytes and is essential for inflammatory responses. In this report we provide direct evidence for a novel mechanism how chemokine receptor function can be arrested by endogenous ligands. We show that binding of eotaxin to CCR2 stimulates the mitogen-activated protein kinases extracellular signal-regulated kinase 1/2 (ERK1/2). Activation of the mitogen-activated protein kinase kinase 1/2-ERK pathway is indispensable for eotaxin-mediated attenuation of CCR2 function, as inhibition of ERK phosphorylation abolishes the arresting effect. ERK is also activated by CCR2 agonists, e.g., monocyte chemoattractant protein-1 (CCL2). However, the involved pathways are different, although in either case coupling of CCR2 to pertussis toxin-sensitive heterotrimeric G proteins is necessary. The results are in agreement with the view that CCR2 could assume different activation states depending on the ligand it encounters. With respect to actin polymerization and calcium mobilization, the different activation states lead to agonistic and antagonistic responses. It is conceivable that the intracellular signal transduction pathway that is activated by eotaxin could cause an attenuation of proinflammatory responses mediated by CCR2.

Animals↗
PubMed2004

Proinflammatory chemokines, such as C-C chemokine ligand 3, desensitize mu-opioid receptors on dorsal root ganglia neurons.

Pain is one of the hallmarks of inflammation. Opioid receptors mediate antipain responses in both the peripheral nervous system and CNS. In the present study, pretreatment of CCR1: mu-opioid receptor/HEK293 cells with CCL3 (MIP-1alpha) induced internalization of mu-opioid receptors and severely impaired the mu-opioid receptor-mediated inhibition of cAMP accumulation. Immunohistochemical staining showed that CCR1 and mu-opioid receptors were coexpressed on small to medium diameter neurons in rat dorsal root ganglion. Analysis of ligand-induced calcium flux showed that both types of receptors were functional. Pretreatment of neurons with CCL3 exhibited an impaired [D-Ala(2),N-MePhe(4),Gly-o15]enkephalin-elicited calcium response, indicative of the heterologous desensitization of mu-opioid receptors. Other chemokines, such as CCL2, CCL5, and CXCL8, exhibited similar inhibitory effects. Our data indicate that proinflammatory chemokines are capable of desensitizing mu-opioid receptors on peripheral sensory neurons, providing a novel potential mechanism for peripheral inflammation-induced hyperalgesia.

Animals↗
PubMed2005

Monocyte chemoattractant protein-1 and CCR2 interactions are required for IFN-alpha/beta-induced inflammatory responses and antiviral defense in liver.

IFN-alpha/beta-mediated functions promote production of MIP-1alpha (or CCL3) by mediating the recruitment of MIP-1alpha-producing macrophages to the liver during early infection with murine CMV. These responses are essential for induction of NK cell inflammation and IFN-gamma delivery to support effective control of local infection. Nevertheless, it remains to be established if additional chemokine functions are regulated by IFN-alpha/beta and/or play intermediary roles in supporting macrophage trafficking. The chemokine MCP-1 (or CCL2) plays a distinctive role in the recruitment of macrophages by predominantly stimulating the CCR2 chemokine receptor. Here, we examine the roles of MCP-1 and CCR2 during murine CMV infection in liver. MCP-1 production preceded that of MIP-1alpha during infection and was dependent on IFN-alpha/beta effects for induction. Resident F4/80(+) liver leukocytes were identified as primary IFN-alpha/beta responders and major producers of MCP-1. Moreover, MCP-1 deficiency was associated with a dramatic reduction in the accumulation of macrophages and NK cells, as well as decreased production of MIP-1alpha and IFN-gamma in liver. These responses were also markedly impaired in mice with a targeted disruption of CCR2. Furthermore, MCP-1- and CCR2-deficient mice exhibited increased viral titers and elevated expression of the liver enzyme alanine aminotransferase in serum. These mice also had widespread virus-induced liver pathology and succumbed to infection. Collectively, these results establish MCP-1 and CCR2 interactions as factors promoting early liver inflammatory responses and define a mechanism for innate cytokines in regulation of chemokine functions critical for effective localized antiviral defenses.

Animals↗
PubMed2005

Viral IL-6 blocks neutrophil infiltration during acute inflammation.

Pathologies arising as a consequence of human herpesvirus-8 (HHV8) infections are closely associated with the autocrine activity of a HHV8 encoded IL-6 (vIL-6), which promotes proliferation of infected cells and their resistance to apoptosis. In this present report, studies show that vIL-6 may also be important in influencing the host's immunological response to secondary infections. Using peritoneal inflammation as a model of acute bacterial infection, vIL-6 was found to specifically block neutrophil recruitment in vivo through regulation of inflammatory chemokine expression. This response was substantiated in vitro where activation of STAT3 in human peritoneal mesothelial cells by vIL-6 was associated with enhanced CCL2 release. Although vIL-6 did not effect CXCL8 production, IL-1beta-induced secretion of this neutrophil-activating chemokine was significantly suppressed by vIL-6. These data suggest that vIL-6 has the capacity to suppress innate immune responses and thereby influence the outcome of opportunistic infections in HHV8-associated disease.

Acute Disease↗
PubMed2006

A novel model of demyelinating encephalomyelitis induced by monocytes and dendritic cells.

Local inflammation may be a precipitating event in autoimmune processes. In this study, we demonstrate that regulated influx of monocytes and dendritic cells (DC) into the CNS causes an acute neurological syndrome that results in a demyelinating encephalomyelitis. Expansion of monocytes and DC by conditional expression of Flt3 ligand in animals expressing CCL2 in the CNS promoted parenchymal cell infiltration and ascending paralysis in 100% of the mice within 9 days of Flt3 ligand induction. Depletion of circulating monocytes and DC reduced disease incidence and severity. Unlike the classical models of experimental autoimmune encephalomyelitis, depletion of CD4+ and CD8+ T cells did not affect disease induction. T cells and demyelinating lesions were observed in the CNS at a later stage as a result of organ-specific inflammation. We propose that alterations in the numbers or function of monocytes and DC coupled to dysregulated expression of chemokines in the neural tissues, favors development of CNS autoimmune disease.

Acute Disease↗
PubMed2006

Cutting Edge: TLR3 stimulation suppresses experimental autoimmune encephalomyelitis by inducing endogenous IFN-beta.

Experimental autoimmune encephalomyelitis is a well-characterized model of cell-mediated autoimmunity. TLRs expressed on APCs recognize microbial components and induce innate immune responses, leading to the elimination of invading infectious agents. Certain TLR agonists have been reported to have adjuvant properties in CNS autoimmune inflammatory demyelination. We report in this study that TLR3 stimulation by polyinosinic-polycytidylic acid, a double-stranded RNA analog, suppresses relapsing demyelination in a murine experimental autoimmune encephalomyelitis model. Disease suppression is associated with the induction of endogenous IFN-beta and the peripheral induction of the CC chemokine CCL2. These data indicate that a preferential activation of the MyD88-independent, type I IFN-inducing TLR pathway has immunoregulatory potential in this organ-specific autoimmune disease.

Animals↗
PubMed2006

The Duffy antigen modifies systemic and local tissue chemokine responses following lipopolysaccharide stimulation.

The Duffy blood group Ag (dfy) binds selective CXC and CC chemokines at high affinity and is expressed on erythrocytes and endothelial cells. However, it does not transmit a signal via G proteins, as occurs with other seven-transmembrane receptors. We hypothesized that dfy functions as a chemokine reservoir and regulates inflammation by altering soluble chemokine concentrations in the blood and tissue compartments. We determined whether Duffy Ag "loss-of-function" phenotypes (human and murine) are associated with alterations in plasma chemokine concentrations during the innate inflammatory response to LPS. Plasma CXCL8 and CCL2 concentrations from humans homozygous for the GATA-1 box polymorphism, a dfy polymorphism that abrogates erythrocyte chemokine binding, were higher than in heterozygotes following LPS stimulation of their whole blood in vitro. Similarly, dfy(-/-) mice showed higher plasma MIP-2 concentrations than dfy(+/+) mice following LPS stimulation of whole blood in vitro. We then determined the relative contributions of erythrocyte and endothelial Duffy Ag in modifying chemokine concentrations and neutrophil recruitment in the lungs following intratracheal LPS administration in dfy(-/-) and dfy(+/+) mice reconstituted with dfy(-/-) or dfy(+/+) marrow. Mice lacking endothelial dfy expression had higher MIP-2 and keratinocyte chemoattractant concentrations in the airspaces. Mice lacking erythrocyte dfy had higher MIP-2 and keratinocyte chemoattractant concentrations in the lung tissue vascular space, but lower plasma chemokine concentrations associated with attenuated neutrophil recruitment into the airspaces. These data indicate that dfy alters soluble chemokine concentrations in blood and local tissue compartments and enhances systemic bioavailability of chemokines produced during local tissue inflammation.

Adolescent↗