Role of serine/threonine protein kinases in the induction of JE, a platelet-derived growth factor inducible gene

Platelet-derived growth factor (PDGF) and serum both stimulate the transcription of the mouse early response gene, JE. JE and its human homolog, macrophage chemotactic protein-1 (MCP-1), encode potent monocyte chemotactic factors. JE/MCP-1 is a member of the chemokine superfamily of small inducible genes whose products are multifaceted mediators of inflammatory and immune responses. We now report evidence that the serine/threonine kinase inhibitors H7 and H8 but not HA1004, W-7, and ML-7 inhibit the transcriptional induction of the JE gene by serum whereas the phosphatase inhibitor, okadaic acid, increases JE expression. Downregulation of protein kinase C by prior exposure to TPA does not inhibit the induction of JE by serum, nor does it affect the inhibition of JE induction by H7. These results suggest that one or more serine/threonine kinases may be important in the signal transduction mechanism that leads to the induction of the JE gene.

The chemokines IL-8, monocyte chemoattractant protein-1, and I-309 are monomers at physiologically relevant concentrations

The chemokines are a family of immune mediators involved in a wide range of inflammatory processes, most importantly as chemoattractants of monocytes, neutrophils, lymphocytes, and fibroblasts to sites of inflammation. Nuclear magnetic resonance and x-ray crystallographic studies have shown that IL-8 and macrophage-inflammatory protein-1 beta (MIP-1 beta) form noncovalent dimers and that platelet factor-4 (PF-4) forms noncovalent dimers and tetramers, leading to the assumption that, as a family, the chemokines would form multimeric structures. In this study, we analyze the association states of the chemokines IL-8, monocyte chemoattractant protein-1 (MCP-1), and I-309, by using a combination of size exclusion HPLC, sedimentation equilibrium ultracentrifugation, and chemical cross-linking. We find that the association states of MCP-1 and IL-8 are characterized by an equilibrium between monomers and dimers: although dimers predominate at concentrations above 100 microM, these chemokines are almost exclusively monomeric at the nanomolar concentrations at which they display maximal chemotactic activity. I-309, by contrast, remains a monomer at all concentrations tested. I-309 contains two additional cysteine residues (C26 and C68) that are not found in any other members of the chemokine family. We used cyanogen bromide and trypsin digestion strategies to demonstrate that these two residues are linked in a unique intramolecular disulfide bond. Furthermore, by using site-directed mutagenesis, we show that the integrity of this bond is crucial for protein secretion.

A new monoclonal antibody (5D3-F7) which recognizes human monocyte-chemotactic protein-1 but not related chemokines. Development of a sandwich ELISA and in situ detection of producing cells

Chemokines are a superfamily of structurally related cytokines involved in leukocyte recruitment in normal and neoplastic tissues. The availability of non-cross-reacting reagents specific for each member of the C-C and C-X-C family is important for careful characterization of their in vitro and in vivo production and relevance. Here we describe a novel, highly specific, mAb against monocyte chemotactic protein-1 (MCP-1). The 5D3-F7 mAb (IgG1,kappa) recognizes human recombinant and natural MCP-1 in ELISA, immunoprecipitation and immunoblot analysis. As a source of natural MCP-1 we used the 8387 human sarcoma line which produces spontaneously MCP-1 and responds to TNF with increased expression and release. The 5D3-F7 mAb inhibited the chemotactic activity of MCP-1 for monocytes. Using the 5D3-F7 mAb and a polyclonal rabbit anti-MCP-1 serum, a sandwich ELISA was developed. In both the direct and the sandwich ELISA, the 5D3-F7 mAb recognized human MCP-1, but not the closely related C-C chemokines MCP-1, MCP-2, MCP-3, MIP-1 alpha, and RANTES and the C-X-C chemokines IL-8, gro alpha and NAP-2. In culture supernatants the sensitivity of the sandwich ELISA was approximately equal to 30 pg/ml. The sandwich ELISA permitted detection of MCP-1 in resting or cytokine-stimulated endothelial, mesothelial and Kaposi's sarcoma cells. Preliminary immunohistochemical analysis revealed production of MCP-1 by macrophage-like cells at sites of inflammation. The 5D3-F7 mAb provides a novel, highly specific reagent with which to investigate the in vitro and in vivo production and role of MCP-1.

NF-kappa B and Sp1 regulate transcription of the human monocyte chemoattractant protein-1 gene

Expression of the human monocyte chemoattractant protein-1 (hMCP-1) is ubiquitous in various cell types and is increased by a wide variety of stimuli. We initially found that the effects of various stimuli, including IL-1 beta, TNF-alpha, and 2-O-tetradecanoylphorbol 13-acetate, on the expression of hMCP-1 mRNA were quite different among A172 glioblastoma cells, HT1080 fibrosarcoma cells, and SKLMS1 leiomyosarcoma cells. These findings suggested that hMCP-1 expression is regulated both in a stimulus-specific and a tissue-specific manner. To elucidate the mechanism underlying this stimulus-specific and tissue-specific regulation, we isolated a hMCP-1 5'-flanking genomic DNA fragment and sequenced it extensively up to bp 3011 upstream from the transcriptional start site. Among many putative cis-elements, we identified two cis-elements critical for the transcription of the hMCP-1 gene. The first element is a remote kappa B binding site located far upstream between bp -2612 and -2603 that was important for IL-1 beta-, TNF-alpha-, and 2-O-tetradecanoylphorbol 13-acetate-induced enhancer activity. Mutation at the kappa B consensus site resulted in a complete loss of these stimulus-induced enhancer activities. The second element is a GC box located between bp -64 and -59 that was important for the maintenance of basal transcriptional activity. Overexpression of rSp1 resulted in increased hMCP-1 transcriptional activity, possibly suggesting the role of Sp1 in controlling basal hMCP-1 transcription via this GC box. These results together indicate that hMCP-1 expression is controlled by at least two distinct regulatory elements: a kappa B site and a GC box that seem to be associated with stimulus-specific and tissue-specific regulation, respectively.

IFN-gamma selectively inhibits lipopolysaccharide-inducible JE/monocyte chemoattractant protein-1 and KC/GRO/melanoma growth-stimulating activity gene expression in mouse peritoneal macrophages

IFN-gamma and LPS have both been shown to stimulate enhanced chemoattractant cytokine gene expression in mononuclear phagocytes. In this report, IFN-gamma was found to suppress LPS-induced chemokine mRNA expression in a cell type- and gene-specific fashion. Expression of JE (monocyte chemoattractant protein-1) and KC (GRO/melanoma growth-stimulating activity) mRNA in macrophages stimulated with LPS was markedly suppressed by IFN-gamma in a dose- and time-dependent fashion. LPS-induced IP-10 mRNA was unaffected by IFN-gamma under identical experimental conditions. This effect was cell type-specific because JE and KC mRNA expression in LPS-stimulated murine endothelial cells, TNF-alpha-stimulated endothelial cells, and NIH-3T3 cells were unaffected by IFN-gamma. The IFN-gamma-mediated suppression of LPS-stimulated KC mRNA expression was independent of protein synthesis and mediated at the transcriptional level. These observations indicate that IFN-gamma may function as a negative regulatory signal for the expression of some proinflammatory cytokines in macrophages. The cell type-dependent differential behavior of individual members of the chemokine family may be an important determinant of the cellular composition and outcome of an inflammatory response.

Localized expression of mRNA for phagocyte-specific chemotactic cytokines in human periodontal infections

In bacterial infections, mononuclear and polymorphonuclear phagocytes are key components of host defenses. Recent investigations have indicated that chemokines are able to recruit and activate phagocytes. In particular, interleukin-8 (IL-8) attracts polymorphonuclear leukocytes (PMNs), while monocyte chemoattractant protein-1 (MCP-1) is selective for cells of the monocyte/macrophage lineage. In this investigation, we analyzed the in situ expression of IL-8 and MCP-1 mRNAs in human periodontal infections. Specific mRNA was detected by in situ hybridization using 35S-labeled riboprobes in frozen tissue sections. Phagocytes (PMNs and macrophages) were specifically detected as elastase-positive or CD68+ cells by a three-stage immunoperoxidase technique. Results indicated that expression of phagocyte-specific cytokines was confined to selected tissue locations and, in general, paralleled phagocyte infiltration. In particular, IL-8 expression was maximal in the junctional epithelium adjacent to the infecting microorganisms; PMN infiltration was more prominent in the same area. MCP-1 was expressed in the chronic inflammatory infiltrate and along the basal layer of the oral epithelium. Cells of the monocyte/macrophage lineage were demonstrated to be present in the same areas. The observed expression pattern may be the most economic way to establish a cell-type-selective chemotactic gradient within the tissue that is able to effectively direct polymorphonuclear phagocyte migration toward the infecting microorganisms and modulate mononuclear phagocyte infiltration in the surrounding tissues. This process may optimize host defenses and contribute to containing leukocyte infiltration to the infected and inflamed area, thus limiting tissue damage.

Interleukin-4 acts as a potent stimulator for expression of monocyte chemoattractant JE/MCP-1 in mouse peritoneal macrophages

The recruitment of monocyte/macrophages to inflammatory sites is one of the important events in inflammatory reactions. We show herein that interleukin-4 (IL-4) acts as a potent stimulator for expression of monocyte chemoattractant JE/MCP-1 in mouse peritoneal macrophages. IL-4 induced the JE/MCP-1 gene expression in dose and time dependent fashion. Run-on assay suggests that IL-4 stimulates the JE/MCP-1 gene expression at transcriptional level. Monocyte chemotactic activity was detected in culture medium of the cytokine-treated cells. The chemotactic activity in the culture supernatant was completely neutralized by anti-JE/MCP-1 antiserum.

Retinoic acid suppression of c-fos gene inhibits expression of tumor necrosis factor-alpha-induced monocyte chemoattractant JE/MCP-1 in clonal osteoblastic MC3T3-E1 cells

Our previous study (Hanazawa, S., Takeshita, A., Amano, S., Semba, T., Nirazuka, T., Katoh, H., and Kitano, S. (1993) J. Biol. Chem. 268, 9526-9532) demonstrated that tumor necrosis factor-alpha (TNF-alpha) induces monocyte chemoattractant JE/MCP-1 expression via c-fos and c-jun genes following protein kinase C activation in osteoblastic MC3T3-E1 cells. In the present study, we examined the effect of retinoic acid (RA) on the cytokine-induced JE/MCP-1 expression in the cells. RA significantly inhibited the JE/MCP-1 gene expression by at least 6 h of pretreatment, and the inhibition was pretreatment time-dependent and occurred at the transcriptional level of the JE/MCP-1 gene expression. The RA-induced inhibition of the JE/MCP-1 gene product was also evidenced by both an assay involving immunoprecipitation with JE/MCP-1-specific antiserum and an assay for monocyte chemotaxis. Also, RA stimulated the gene expression of three different subclasses of RA receptor. RA pretreatment transcriptionally suppressed the expression of the c-fos gene but not that of the c-jun gene in TNF-alpha-treated cells. Antisense oligonucleotide to c-fos gene inhibited the cytokine-induced JE/MCP-1 gene expression in the cells. Furthermore, RA inhibited activator protein-1 binding to 12-O-tetradecanoylphorbol 13-acetate-response element (TRE) in the cells treated with TNF-alpha, suggesting that RA acts as a potent negative regulator for activator protein-1 binding activity to TRE in the osteoblastic cells.

Characterization of the bovine monocyte chemoattractant protein-1 gene

Bovine monocyte chemoattractant protein-1 (bovine MCP-1) cDNA has recently been characterized and shown to be highly expressed in bovine seminal vesicles. In an attempt to isolate the MCP-1 gene, we screened a bovine genomic lambda EMBL-3 library with an MCP-1 specific probe pH42. A positive clone lambda MCP1 was subjected to restriction analysis and a pH42-positive EcoRI-fragment of 3.8 kb was subcloned and sequenced. The bovine MCP-1 gene consists of three exons separated by two introns. We undertook to identify homologous sequences 5'-upstream of the transcriptional start site within the genes of rat, mouse, human and bovine MCP-1. Six conserved sequence stretches located within 400 bp upstream of the transcriptional start site in MCP-1 genes were detected. Interestingly an approximately 45 bp long region, displaying identities in the range of 68-72% relative to the human sequence, covers in the rat gene the -141/88 region responsible for TPA induction of gene expression.

Expression of intercellular adhesion molecule-1 on rat cardiac myocytes by monocyte chemoattractant protein-1

OBJECTIVE

Cytokine induction of intercellular adhesion molecule-1 (ICAM-1) on cardiac myocytes may be a critical step in cardiac inflammation associated with acute myocardial infarction and myocarditis. The aim of this study was to investigate the involvement of monocyte chemoattractant protein-1 (MCP-1), a homologue of mouse JE, in the neutrophil-myocyte adhesion in vitro.

METHODS

MCP-1/JE and ICAM-1 mRNA expression in cultured neonatal rat cardiac myocytes was evaluated by northern blot analysis. ICAM-1 molecule content on myocytes was determined by ELISA. For adherence assay, myocytes and neutrophils were co-incubated and the number of bounded neutrophils was counted.

RESULTS

MCP-1/JE transcripts were not clearly observed in cultured neonatal rat cardiac myocytes; however, its transcripts were clearly detected by exposure to interleukin 1 alpha (100 U.ml-1), lipopolysaccharide (1 microgram.ml-1), or hypoxia (95% N2 + 5% CO2). In ELISA analysis, the expression of ICAM-1 molecules on cardiac myocytes was significantly stimulated by MCP-1 in a dose dependent manner, and the effect of MCP-1 was observed as early as at 6 h. In northern blot analysis, ICAM-1 mRNA expression was constitutively observed in myocytes, and the expression was markedly stimulated by exposure to MCP-1 with a peak elevation at 2 h. In adherence assay, MCP-1 stimulated the adhesion of rat neutrophils to rat cardiac myocytes, and this effect of MCP-1 was inhibited by an anti-ICAM-1 MAb.

CONCLUSIONS

These results suggest that cardiac myocytes produce MCP-1, which could in turn promote the adhesion of neutrophils to myocytes via ICAM-1 expression, suggesting the involvement of MCP-1 in cardiac inflammation associated with acute myocardial infarction and myocarditis.

Expression of monocyte chemoattractant protein-1 in delayed type hypersensitivity reactions in the skin

BACKGROUND

Monocyte chemoattractant Protein-1 (MCP-1) is a potent chemotactic factor for monocytes. Because many inflammatory dermatoses are characterized by mononuclear cell infiltrates, it is reasonable to postulate that MCP-1 might be involved in their pathogenesis. To date, no in vivo studies have been published concerning the expression of MCP-1 in this context. The aim of this study was to elucidate the expression of MCP-1 in human inflammatory skin diseases which are thought to involve delayed type hypersensitivity reactions.

EXPERIMENTAL DESIGN

Expression of MCP-1 was examined in normal skin and three classes of inflammatory skin reactions by immunohistochemistry experiments utilizing a monospecific MCP-1 antiserum. The distribution of monocytes/macrophages and T lymphocytes was determined by immunohistochemistry using antibodies to specific cell surface markers.

RESULTS

Immunostaining with MCP-1 antiserum demonstrated strong MCP-1 expression in lichenoid dermatitis, dermal hypersensitivity reactions, and spongiotic dermatitis. In contrast, normal skin showed minimal MCP-1 expression in the dermis. The cell types displaying MCP-1 expression were endothelial cells of dermal microvessels that were surrounded by lymphocytic infiltrates and monocytes/macrophages at the periphery of the perivascular infiltrates. Occasionally, MCP-1-positive mononuclear cells were present both in the infiltrates and in a diffuse pattern in the surrounding dermis. Keratinocytes were found to produce MCP-1 constitutively in normal skin and in inflamed conditions. The pattern of MCP-1 expression was similar to the pattern observed for monocyte/macrophage distribution, whereas the pattern of MCP-1 expression was different from the pattern of T lymphocyte distribution.

CONCLUSIONS

We observed an enhanced expression of MCP-1 in inflammatory skin conditions. The expression of MCP-1 provides a mechanistic explanation for the increased recruitment of monocytes/macrophages in cell-mediated immune response such as delayed type hypersensitivity reactions in the skin.

cDNA cloning and functional expression of a human monocyte chemoattractant protein 1 receptor

A novel human G-protein-coupled seven-transmembrane-type receptor gene, 24-1, has been cloned from THP-1 cells. The 24-1 was 56% and 34% identical to the macrophage inflammatory protein-1 alpha (MIP-1 alpha) receptor and the interleukin-8 (IL-8) receptors at the amino acid level, respectively. To examine the ligand specificity of the receptor, we have established a stable transfectant of this gene with human kidney 293 cells. Monocyte chemoattractant protein-1 (MCP-1) induced a rapid increase of Ca++ influx in the 24-1-transfectant, while other C-C chemokines tested did not. This indicates that the 24-1 encodes the human MCP-1 receptor.

C/EBP-related protein 2 confers lipopolysaccharide-inducible expression of interleukin 6 and monocyte chemoattractant protein 1 to a lymphoblastic cell line

C/EBP-related proteins 2 and 3 (CRP2 and CRP3) are differentially expressed by P388 lymphoblasts and their derivative P388D1(IL1) macrophages. We have ectopically expressed CRP2, the predominant CRP in macrophages, in P388 lymphoblasts. The expression of CRP2 is sufficient to confer the lipopolysaccharide (LPS)-inducible expression of interleukin 6 and monocyte chemoattractant protein 1 to lymphoblasts, which normally do not display LPS induction of inflammatory cytokines. Consistent with these findings, the expression of CRP2 antisense RNA blocks the LPS induction of IL-6 expression in P388D1(IL1) macrophages. This work clearly establishes the essential role of CRP2 in the induction of cytokine genes by LPS. Additionally, these data add MCP-1 to the list of cytokines showing an involvement of CRP2 in their expression.

Human astrocytomas and glioblastomas express monocyte chemoattractant protein-1 (MCP-1) in vivo and in vitro

Expression of the monocyte chemoattractant protein-1 (MCP-1) was examined in human central nervous system tumours (glioblastomas and astrocytomas) and normal human brain. Northern blot analysis demonstrated constitutive expression of MCP-1 mRNA in 6 of 12 glioblastoma cell lines. Expression could be stimulated by interleukin (IL)-1 beta and tumour necrosis factor (TNF)-alpha in all cell lines tested. Immunoprecipitation demonstrated secretion of both isoforms, MCP-1 alpha and -beta, of the MCP-1 protein. Reverse-transcription polymerase chain reaction and Northern blot analysis on tissues demonstrated MCP-1 mRNA expression in 17 of 17 glioblastomas, 3 of 6 anaplastic astrocytomas and 6 of 6 low-grade astrocytomas, as well as in fetal brain but not in normal adult brain. In situ hybridization on 2 glioblastomas and 1 low-grade astrocytoma indicates that neoplastic astrocytes and endothelial cells express MCP-1 mRNA in vivo. Moreover, tumour cyst fluids of glioblastomas and astrocytomas were able to induce monocyte chemoattraction in an in vitro assay. This chemotactic activity was specifically neutralized by anti-MCP-1 antibodies in 9 of 10 samples, further demonstrating the production of bioactive MCP-1 in vivo and supporting an important role for this factor in the infiltration of monocytes/macrophages into tumour tissue.

Identification and characterization of a promiscuous chemokine-binding protein in a human erythroleukemic cell line

The erythrocyte chemokine receptor is a cell surface protein that binds a wide array of chemokines including interleukin-8 (IL-8), melanoma growth stimulating activity (MGSA), monocyte chemotactic protein-1 (MCP-1), and RANTES (Regulated on Activation, Normal T Expressed and Secreted). This protein has also been identified as the Duffy blood group antigen, a cell surface receptor for the malarial parasite Plasmodium vivax. In the present study, we have identified a chemokine receptor-like binding protein in a human erythroleukemic cell line (HEL), which, based on its molecular properties, may be related to the erythrocyte chemokine receptor. Saturation binding studies with 125I-IL-8 revealed a single class of IL-8 binding sites in HEL cells with a KD of 7.4 +/- 1.9 nM and a receptor density of 12,818 +/- 965 binding sites/cell. In competition studies unlabeled IL-8 MGSA, MCP-1, and RANTES were fully able to inhibit the binding of 125I-IL-8 to HEL cells. Chemical cross-linking with radiolabeled IL-8 resulted in a cross-linked species of 60 kDa in membranes from HEL cells. The labeling was specific since it was inhibited by pre-incubation with 1 microM unlabeled IL-8 or MGSA. A monoclonal antibody (Fy6) to the human erythrocyte Duffy blood group antigen/chemokine receptor blocked the binding of IL-8 and other chemokines to the HEL cell chemokine receptor-like binding protein. Cell membranes from HEL cells and from erythrocyte ghosts were subjected to SDS-PAGE and analyzed by Western blotting with anti-Fy6. The antibody bound to a molecule with a molecular mass of 50 kDa in HEL cell membranes and 40 kDa in erythrocyte ghosts. Northern blot analysis of mRNA revealed that the HEL chemokine-binding protein hybridized to a cDNA probe to the Duffy antigen/chemokine receptor.

Targeted disruption of the c-fos gene demonstrates c-fos-dependent and -independent pathways for gene expression stimulated by growth factors or oncogenes

The c-fos proto-oncogene is believed to play a pivotal role in transducing growth factor-mediated signals from the extracellular milieu into the nucleus. c-fos protein dimerizes with c-jun and related proteins and mediates transcription via AP-1 sites. Using c-fos-deficient mice generated through gene knockout techniques, we derived 3T3-type cell lines from primary embryonic fibroblasts. The c-fos-deficient cells grow normally under optimal culture conditions and show only a slight reduction in growth rate in low serum culture compared with control cells. They also express mRNA for most of the Fos and Jun family members at normal levels. The overall levels of AP-1 DNA binding activity are normal and several genes (c-jun, MCP1, metallothionein) known to contain functional AP-1 sites are expressed normally in the c-fos-deficient and control cells. In contrast, mRNA for the metalloproteases stromelysin (MMP-3) and type I collagenase (MMP-1), which are often induced by oncogenes and growth factors and have been implicated in tumor invasiveness, cannot be induced by epidermal growth factor or platelet-derived growth factor in c-fos-deficient cells. Transformation of mutant cells with polyoma middle T oncogene essentially restores wild-type levels of stromelysin expression, while transformation with v-src leads to only a weak induction of the metalloprotease. These results clearly demonstrate that some AP-1-dependent genes require c-fos for full expression while others do not; oncogenes may activate expression of metalloproteases via either fos-dependent or fos-independent mechanisms. These results also imply that c-fos may play an important regulatory role in the invasive behavior of malignant tumors, independent of any role this proto-oncogene might play in cell growth per se.

Expression of monocyte chemoattractant protein 1 in human osteoblastic cells stimulated by proinflammatory mediators

Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokine superfamily of genes that induces chemotaxis of monocytes in inflammatory processes. The effects of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), transforming growth factor beta (TGF-beta), platelet-derived growth factor (PDGF-BB), parathyroid hormone (PTH), and 1,25(OH)2D3 on MCP-1 expression in human osteoblastic cells were compared. Inflammatory or proinflammatory cytokines stimulated the production of MCP-1 in normal human osteoblastic cells as determined by RIA. The osteotrophic mediators PTH and 1,25(OH)2D3 and PDGF-BB had no effect on MCP-1 expression. In further studies, the steady-state mRNA and MCP-1 protein levels in two human osteoblastic cell lines, MG-63 and SaOS-2, were examined. MCP-1 expression at both the protein and mRNA levels was greatly increased by IL-1 beta and TNF-alpha. At the mRNA level, IL-1 beta and TNF-alpha strongly induced MCP-1 expression; TGF-beta and IL-6 induced MCP-1 but to a lesser extent. No significant changes in MCP-1 mRNA or MCP-1 protein secretion were observed when cells were treated with PDGF-BB, PTH, and 1,25(OH)2D3. When tested on preosteoclasts, MCP-1 was shown to have no effect on the formation of multinucleated, tartrate-resistant acid phosphatase (TRAP)-positive osteoclastic cells.

Lipopolysaccharide induces monocyte chemoattractant protein production by rat mesangial cells

Lipopolysaccharide, a potent pro-inflammatory constituent of bacterial cell walls, is capable of promoting glomerular inflammation, by both activating circulating inflammatory cells and local interactions with renal parenchymal cells. We sought to determine whether lipopolysaccharide was capable of promoting glomerular inflammation by directly stimulating mesangial cell production of monocyte chemoattractant protein 1, a recently described cytokine capable of eliciting recruitment of mononuclear phagocytes into inflammatory foci. Northern hybridization analysis revealed dose and time-dependent induction of mRNA coding for monocyte chemoattractant protein 1 in quiescent rat mesangial cells treated with lipopolysaccharide. Lipopolysaccharide-elicited induction of monocyte chemoattractant protein mRNA was detectable after 1 hour and persisted for at least 30 hours. Media isolated from rat mesangial cell cultures stimulated by lipopolysaccharide possessed monocyte chemotactic activity that was detectable at 8 hours and peaked at 24 hours; an antimonocyte chemoattractant protein antibody blocked 87% of this chemotactic activity. We suggest that lipopolysaccharide, released from bacterial cell walls, promotes glomerular inflammation by stimulating mesangial cell production of monocyte chemoattractant protein 1.

Mouse macrophage derived monocyte chemotactic protein-3: cDNA cloning and identification as MARC/FIC

When the mouse macrophage cell line WEHI-3 is triggered with LPS it produces proteases and secondary cytokines including interleukin-6 and chemokines. In an attempt to isolate the mouse homologue of the human monocyte chemotactic protein-3 (MCP-3), a cDNA library from LPS-stimulated WEHI-3 cells was screened with the full-size human MCP-3 cDNA. The longest cDNA out of several positive clones was sequenced and encoded a protein of 97 residues. Except for a third codon letter mismatch it was identical to the mouse MARC cDNA and encoded the MARC protein. The murine Fic cDNA, which encodes a Marc-mutant protein with an arginine substitution for alanine, was not identified in the other sequenced homologous isolates. Similar to the human system, in which MCP-3 is most related to MCP-1, MURINE MCP-3 was found to be more homologous to mouse MCP-1/JE than to other murine C-C chemokines. We therefore postulate that MARC/FIC is the mouse MCP-3.

Structure/activity analysis of human monocyte chemoattractant protein-1 (MCP-1) by mutagenesis. Identification of a mutated protein that inhibits MCP-1-mediated monocyte chemotaxis

Monocyte chemoattractant protein-1 (MCP-1) is a monocyte-specific chemoattractant and activator and is a member of the chemokine-beta family of cytokines. To identify regions of MCP-1 which are required for its biological activity, we constructed human MCP-1 mutants that were expressed in eukaryotic cells and tested for their ability to attract monocytes in vitro. Deletion of amino acids 2-8 destroyed activity, suggesting that the amino-terminal region is necessary for activity. Within the deleted region, mutation of aspartate 3 to alanine produced a protein with 9% of wild-type activity, whereas mutation of asparagine 6 to alanine produced a protein with 52.9% of wild-type activity. Mutation of amino acids within the first intercysteine loop yielded variable results. Changing tyrosine 28 to aspartate or arginine 30 to leucine each produced proteins with essentially no monocyte chemoattractant activity. The side chains of these amino acids are predicted to point into a putative receptor binding cleft, and these loss-of-function mutations are consistent with this model. Also consistent is the retention of 60% of wild-type activity after mutation of serine 27 to glutamine, since the side chain of serine 27 is predicted to point away from the binding cleft. However, mutation of arginine 24, which lies outside of this area, to phenylalanine produced a protein with only 5% of wild-type activity, suggesting more complex interactions. Truncations of the carboxyl terminus, as well as mutation of aspartate 68 to leucine, generated proteins with 10-20% of wild-type activity. (Another carboxyl-terminal insertional mutation demonstrated that O-linked carbohydrate in MCP-1 alpha may be added to a threonine in the carboxyl-terminal region.) These findings are consistent with a structural model of dimeric MCP-1 which is similar to interleukin-8, in which amino acids that point into a cleft between the two carboxyl-terminal alpha-helices of the subunits are important for receptor binding. In addition, however, amino acids at the amino terminus and others outside of the interhelical cleft are also essential for activity. The carboxyl-terminal alpha-helix is not required for signaling per se but is required for maximal specific activity. Finally, four mutant proteins partially inhibited the ability of wild-type MCP-1 to attract monocytes in vitro.(ABSTRACT TRUNCATED AT 400 WORDS)

Regulation of chemokine production by the oxidative metabolism of L-arginine in a human mixed lymphocyte reaction

Previous studies have shown that during the development of a mixed lymphocyte reaction (MLR) levels of the chemotactic cytokines IL-8 and MCP-1 (members of the C-X-C and C-C supergene families, respectively) increase in a time-dependent fashion, and that the production of these chemokines correlates with the magnitude of responsiveness to alloantigen. Furthermore, the responsiveness to alloantigen in the context of a MLR has been shown to be regulated by the oxidative metabolism of L-arginine. We postulated that competitive antagonism of the L-arginine metabolic pathway in a human MLR may alter the production of members of the C-C and C-X-C chemokine families. To test this hypothesis, mononuclear cells were isolated from healthy individuals and subjected to a one-way MLR in the presence or absence of varying concentrations of an L-arginine competitive inhibitor, NG-methyl-L-arginine (NMA: 50 to 500 microM). When the MLR was performed in the presence of NMA (500 microM), the production of IL-8 increased twofold (P < 0.05) and ENA-78 increased fivefold (P < 0.05), while MCP-1 and MIP-1 alpha were not significantly altered. These findings suggest that NMA, an inhibitor of the L-arginine metabolic pathway, may regulate the production of specific C-X-C chemokines, IL-8 and ENA-78, during a MLR. In contrast, the production of MCP-1 and MIP-1 alpha, members of the C-C chemokine family, does not appear to be regulated by this inhibitor of the oxidative metabolism of L-arginine in the context of a MLR.

Induction of monocyte chemotactic proteins MCP-1 and MCP-2 in human fibroblasts and leukocytes by cytokines and cytokine inducers. Chemical synthesis of MCP-2 and development of a specific RIA

Monocyte chemotactic proteins (MCP) belong to a group of structurally and functionally related factors, called chemokines. To facilitate additional characterization of the recently identified MCP-2, the 76-residue protein was chemically synthesized. The synthetic 7-kDa monomeric protein was chemotactic for monocytes at 1 nM and was biochemically similar to natural MCP-2. Sensitive radioimmunoassays for both MCP-1 and MCP-2 were developed. These RIAs were specific in that no cross-reactivity could be observed, and other chemokines or cytokines were not detected. Induction of MCP-1 and MCP-2 in human diploid fibroblasts and peripheral blood leukocytes as well as osteosarcoma, epidermal carcinoma, and melanoma cells by the cytokines IL-1 beta, IFN-beta, and IFN-gamma and cytokine inducers such as dsRNA, virus, endotoxin, mitogen, and phorbol ester was studied. In connective tissue cells, IL-1 beta was the best inducer of MCP-1, but IFN-gamma was a superior inducer of MCP-2. Mononuclear cells also proved to be a source of MCP-1 and MCP-2 when stimulated by most of the inducers tested. Granulocytes, however, were inefficient producers. Measles virus induced MCP-1 and MCP-2 in most cell types. In general, the yields of MCP-2 were at least 10-fold lower than those of MCP-1. It is concluded that, although MCP-2 is often coproduced with MCP-1, regulation of expression of the two chemokines is not identical. It remains to be studied under which pathological conditions MCP-2 is released in vivo and whether MCP-1 and MCP-2 can activate different target cells.

Macrophages, monocyte chemoattractant peptide-1, and TGF-beta 1 in experimental hydronephrosis

Early cellular and molecular derangements have been evaluated as potential pivotal factors for the late development of interstitial fibrosis after experimental hydronephrosis. In this study, we delineated the kinetics of renal cortical macrophage infiltration as well as the cortical expression of transforming growth factor-beta 1 (TGF-beta 1) and monocyte chemoattractant peptide-1 (MCP-1) at 12, 48, and 96 h after unilateral ureteral obstruction (UUO). Interstitial macrophage number in the obstructed kidney versus the contralateral unobstructed kidney (CUK) significantly increased by 12 (11.1 +/- 0.9 vs. 4.5 +/- 0.6), 48 (27.5 +/- 0.9 vs. 4.0 +/- 0.8), and 96 h (71.4 +/- 4.6 vs. 3.2 +/- 0.4) after UUO. MCP-1 mRNA was detected from 12 to 96 h in the obstructed kidney but was absent in the CUK specimens at all time points. Apical tubular MCP-1 expression, on immunolabeling, was present from 12 through 96 h after UUO in the obstructed kidney but not the CUK specimen. On Northern analysis, there were highly significant 2.6-, 5.8-, and 7.0-fold increments in renal cortical TGF-beta 1 mRNA levels at 12, 48, and 96 h, respectively, in the obstructed kidney versus the CUK specimen. Intracellular TGF-beta 1, on immunolabeling, was detected only in the obstructed kidneys of UUO rats at all three time points and was confined to peritubular cells of the renal interstitium. A significant (P < 0.005) correlation (r = 0.95) between interstitial macrophage number and cortical TGF-beta 1 mRNA levels was noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic rejection in experimental cardiac transplantation in a rat model

The most significant pathologic finding in chronically rejected organ grafts is diffuse concentric intimal proliferation in the arterial system. To develop a reproducible model of chronic vascular rejection in cardiac grafts which we could then use to study the pathogenesis and therapy of this disease process, we exchanged heterotopic cardiac allografts across minor histocompatibility barriers using commercially available Lewis rats as donors and F-344 rats as recipients. We found that all long-term surviving allografts developed diffuse graft arteriosclerotic lesions which were virtually identical in appearance to those seen in chronically rejected human cardiac grafts. Immunohistochemical studies confirm that end-stage lesions are similar in composition to human lesions and are made up predominantly of vascular smooth muscle cells with occasional monocytes and T cells. Analysis of continuous series of rejecting allografts demonstrates that a distinct inflammatory stage precedes smooth muscle cell accumulation in areas of intimal thickening, suggesting that mononuclear cells play a role in the developing lesion. Endothelial expression of class II and ICAM-1 probably underlies early mononuclear cell adherence to the endothelium. Analysis using quantitative RT-PCR and immunocytochemistry confirms MCP-1 is expressed by ED1-positive monocyte/macrophages in rejecting cardiac grafts, suggesting this chemoattractant may help drive mononuclear cell accumulation in the expanding intima. Immunohistochemical labelling of PDGF, TNF and IL-1 beta in vascular lesions suggests these factors may trigger intimal vascular smooth muscle cell proliferation in chronically rejecting allografts, as they, along with protein S, were closely associated with sites of intimal hyperplasia and smooth muscle cell proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression and localization of messenger RNA and protein for monocyte chemoattractant protein-1 in human malignant glioma

Expression of monocyte chemoattractant protein-1 (MCP-1) in human glioma cell lines and surgical specimens was studied by Northern blot analysis, reverse-transcription polymerase chain reaction, in situ hybridization, and immunohistochemistry. The samples tested consisted of 11 human glioma cell lines and eight specimens of human malignant glioma (seven from glioblastomas and one from a malignant ependymoma). Messenger ribonucleic acid (mRNA) of MCP-1 was detected by either Northern blot or reverse-transcription polymerase chain reaction analysis in all cell lines and tumor specimens examined. In vivo expression of MCP-1 mRNA and protein was found predominantly in glioma cells with large and pleomorphic nuclei rather than in areas of small nucleated glioma cells. Adjacent brain tissue did not produce a significant level of MCP-1 mRNA or protein. Tumor vessels with endothelial proliferation expressed a moderate level of MCP-1 protein. Macrophages were found among the glioma cells, and the degree of macrophage infiltration was grossly correlated with the level of MCP-1 expression. The study results suggest that MCP-1 produced by the glioma cells may mediate macrophage infiltration into the glioma tissue.