Purification and amino acid analysis of two human glioma-derived monocyte chemoattractants

Mercury compounds induce a rapid increase in procoagulant activity of monocyte-like U937 cells

When monocytic leukaemia line U937 cells were incubated in the presence of HgCl2 there was a rapid increase in tissue factor (TF)-dependent procoagulant activity, reaching a maximum (equivalent to the total TF activity observed when cells had been subjected to a freeze/thaw cycle) after 15 min at 50 microM HgCl2 and after 30 min at 10 microM HgCl2. Two other heavy metal compounds, AgNO3 and phenylmercuric acetate, caused a similar increase in TF activity. The increase was independent of protein synthesis. Other reagents tested, CdCl2, ZnCl2, NiCl2, ADP, FMLP and monocyte chemotactic factor (MCF-1), did not cause a rapid increase in functional activity, when tested under the same experimental conditions. The addition of HgCl2 to the cells causes, in a concentration-dependent manner, a 10-12-fold increase in intracellular calcium (Cai) which coincides with increase in TF activity. Calcium ionophore also caused an increase in TF activity of the U937 cells. Upon treatment with HgCl2 the cell surface of U937 cells showed a large increase in the level of phosphatidylserine (PS) on the cell surface (as measured by potentiation of the rate of activation of prothrombin by factor Xa-factor Va) but with no change in the level of TF antigen on the cell surface. We consider that the TF is present on the cell surface of the monocyte but relatively inactive towards the physiological substrate, factor X (FX), until HgCl2 causes a change in the polarity of the cell membrane exposing PS on the outer leaflet by a mechanism likely to be enhanced by the increase in intracellular calcium.

Monocyte chemoattractant protein 1 acts as a T-lymphocyte chemoattractant

We have utilized a transendothelial lymphocyte chemotaxis assay to identify and purify a lymphocyte chemoattractant in supernatants of mitogen-stimulated peripheral blood mononuclear cells. Amino acid sequence analysis revealed identity with monocyte chemoattractant protein 1 (MCP-1), a chemoattractant previously thought to be specific for monocytes. Recombinant MCP-1 is chemoattractive for purified T lymphocytes and for CD3+ lymphocytes in peripheral blood lymphocyte preparations. The T-cell response to MCP-1 is dose-dependent and chemotactic, rather than chemokinetic. Phenotyping of chemoattracted T lymphocytes shows they are an activated memory subset. The response to MCP-1 by T lymphocytes can be duplicated in the absence of an endothelial monolayer and the majority of T-lymphocyte chemotactic activity in mitogen-stimulated peripheral blood mononuclear cell supernatants can be neutralized by antibody to MCP-1. Thus, MCP-1 is the major lymphocyte chemoattractant secreted by mitogen-stimulated peripheral blood mononuclear cells and is capable of acting as a potent T-lymphocyte, as well as monocyte, chemoattractant. This may help explain why monocytes and T lymphocytes of the memory subset are always found together at sites of antigen-induced inflammation.

Differential regulation of the JE gene encoding the monocyte chemoattractant protein (MCP-1) in cervical carcinoma cells and derived hybrids

Malignant human papillomavirus type 18 (HPV18)-positive cervical carcinoma cells can be reverted to a nonmalignant phenotype by generation of somatic cell hybrids with normal human fibroblasts. Although nontumorigenic hybrids, their tumorigenic segregants, and the parental HeLa cells have similar in vitro properties, inoculation only of nontumorigenic cells into nude mice results in a selective suppression of HPV18 transcription which precedes cessation of cellular growth. Our present study, aimed at understanding the differential regulation in vitro and in vivo, shows that the JE gene, encoding the monocyte chemoattractant protein (MCP-1), is expressed only in nontumorigenic hybrids. Although the gene, including its regulatory region, is intact, no JE (MCP-1) mRNA is detected in the tumorigenic segregants and in other malignant HPV-positive cervical carcinoma cell lines. Tests of several monocyte-derived cytokines showed that only tumor necrosis factor alpha strongly induces the JE (MCP-1) gene in nontumorigenic cells and that this is accompanied by a dose-dependent reduction of HPV transcription. The JE (MCP-1) up-regulation occurs within 2 h and does not require de novo protein synthesis. The response to tumor necrosis factor alpha seems to be mediated by an NF-kappa B-related mechanism, since the induction can be completely abrogated by pretreating the cells with an antioxidant such as pyrrolidine dithiocarbamate. Interestingly, cocultivation of nonmalignant hybrids with monocyte-enriched fractions from human peripheral blood also results in an induction of the JE (MCP-1) gene and a concomitant suppression of HPV18 transcription. Neither effect is observed in malignant cells. These data suggest that JE (MCP-1) may play a pivotal role in the intercellular communication by triggering an intracellular pathway which negatively interferes with viral transcription in HPV-positive nontumorigenic cells.

Molecular cloning and functional expression of two monocyte chemoattractant protein 1 receptors reveals alternative splicing of the carboxyl-terminal tails

Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokine family of cytokines that mediate leukocyte chemotaxis. The potent and specific activation of monocytes by MCP-1 may mediate the monocytic infiltration of tissues in atherosclerosis and other inflammatory diseases. We have isolated cDNAs that encode two MCP-1-specific receptors with alternatively spliced carboxyl tails. Expression of the receptors in Xenopus oocytes conferred robust mobilization of intracellular calcium in response to nanomolar concentrations of MCP-1 but not to related chemokines. The MCP-1 receptors are most closely related to the receptor for the chemokines macrophage inflammatory protein 1 alpha and RANTES (regulated on activation, normal T expressed and secreted). The identification of the MCP-1 receptor and cloning of two distinct isoforms provide powerful tools for understanding the specificity and signaling mechanisms of this important chemokine.

Human monocyte chemoattractant protein-1 expressed in a baculovirus system

Human monocyte chemoattractant protein-1 (hMCP-1) was produced using a baculovirus system. The hMCP-1 cDNA was inserted into the genomic DNA of Autographa californica nuclear polyhedrosis virus (AcNPV) using a transfer vector, pJVP10Z. Spodoptera frugiperda insect cells, which were infected with this recombinant virus, secreted recombinant hMCP-1 (re-hMCP-1) at the level of 10-20 micrograms/ml of culture medium. This product was shown to chemoattract monocytes. Three distinct bands of 11, 11.5 and 12 kDa were revealed by immunoblotting analysis, and this heterogeneity was assigned to differences in carbohydrate processing. N-terminal amino-acid sequence analysis of the purified product revealed identity with hMCP-1. Thus, in this system, re-hMCP-1 was produced in large quantities and modified in a manner similar to native hMCP-1.

Protection against lethal bacterial infection in mice by monocyte-chemotactic and -activating factor

Chemotactic factors regulate the recruitment of neutrophils, lymphocytes, or monocytes-macrophages to infectious and inflammatory sites. The purpose of this study was to determine whether monocyte-chemotactic and -activating factor (MCAF [MCP-1], a JE gene product) also influences the host defense mechanism against microbial infection. We evaluated the effect of recombinant human MCAF on the survival rate of mice systemically infected with Pseudomonas aeruginosa or Salmonella typhimurium. The administration of 2.5 micrograms of MCAF 6 h before infection completely protected the mice from lethal infection. Mice with cyclophosphamide-induced leukopenia exhibiting increased susceptibility to P. aeruginosa were also endowed with resistance by the same dose of MCAF. Administration of MCAF at -6 h was critical, since MCAF given either earlier or later than -6 h failed to rescue mice from lethal infection. The in vivo effect on the survival of mice paralleled the reduced recovery of viable P. aeruginosa or S. typhimurium from the peritoneal cavity, i.e., the number of recovered bacteria from the MCAF (2.5 micrograms per mouse)-treated mice was reduced to less than 2% of control mice for P. aeruginosa and 4% of control mice for S. typhimurium at 24 h. Since MCAF exhibited chemotaxis on murine macrophages as well as enhanced phagocytosis and killing of bacteria in vitro, the activation of macrophages, followed by the recruitment into the peritoneal cavity, is responsible for eliminating bacteria and thus enhancing the survival rate.

Regulation of monocyte chemoattractant protein-1 expression in adult human non-neoplastic astrocytes is sensitive to tumor necrosis factor (TNF) or antibody to the 55-kDa TNF receptor

Infiltration of the central nervous system (CNS) by monocytes is a characteristic of many non-malignant disease processes, although the signals regulating such traffic are unclear. Tumor necrosis factor (TNF) and other inflammatory cytokines have been shown to elicit production of monocyte chemoattractant activity in glioma cells, but the regulation of such activity in non-neoplastic adult astrocytes has not been examined. We previously observed that TNF constituted a proliferative signal for non-neoplastic adult human astrocytes in vitro involving the 55-kDa TNF receptor. In the present study, we demonstrate that TNF exposure enhances the expression of monocyte chemoattractant protein-1 (MCP-1) mRNA and functional monocyte chemoattractant activity in non-neoplastic astrocytes. Results indicated that MCP-1 mRNA expression was maximal within 3 h, and was further augmented by the protein synthesis inhibitor cycloheximide (CY). Antibody (htr-9) directed against the 55-kDa TNF receptor also elicited MCP-1 mRNA expression while antibody to the 75-kDa TNF receptor (utr-1) was ineffective. Secretion of monocyte chemoattractant activity was significantly greater in TNF- or htr-9-treated astrocytes than in utr-1-treated or untreated controls; activity was abolished by treatment with antibody to MCP-1. These findings suggest that non-neoplastic adult human astrocytes may contribute to CNS inflammatory responses by mediating recruitment of peripheral blood monocytes.

Detection of monocyte chemotactic and activating factor (MCAF) in normal blood and urine using a sensitive ELISA

We developed a highly sensitive enzyme-linked immunosorbent assay (ELISA) for human monocyte chemotactic and activating factor (MCAF), an inflammatory cytokine that plays an important role in the recruitment of blood monocytes to areas of inflammation. The ELISA, which is based on a sandwich method using two newly-developed monoclonal antibodies, could quantitatively detect MCAF in the range between 2.5 pg/ml (50 fg/sample) to 300 pg/ml after incubation for a total of 2 h, and showed no cross-reactivity with various structurally-related IL-8 superfamily proteins. It was not affected by blood or urine components non-specifically, and thus was directly applicable to clinical specimens. When serum and urine samples from healthy subjects were measured, they all turned out to contain detectable levels of MCAF (more than 30 pg/ml). By gel-filtration column chromatography analysis, MCAF in the body fluids was eluted as a single peak at the position corresponding to the molecular weight of 10 kD, suggesting that it exists as a monomer form, free from carrier proteins. The established ELISA here is expected to be effectively used for the further investigations on the relationship of MCAF with various inflammatory diseases.

Expression and modulation of a mononuclear phagocyte differentiation antigen (PAM-1) during in vitro maturation of peripheral blood monocytes

Human macrophages obtained by in vitro maturation of peripheral blood monocytes express a surface antigen, PAM-1, recognized by a monoclonal antibody and typical of pulmonary alveolar and tissue macrophages. PAM-1, undetectable in freshly isolated peripheral blood monocytes, was expressed in monocyte-derived macrophages after 3 days of in vitro adherent culture and was maximal after 14-15 days (50%-60% of positive cells). Similar levels of PAM-1 positivity were observed in non-adherent monocyte-derived macrophages suggesting that cell adhesion was not a critical requisite for the expression of this antigen. Bacterial lipopolysaccharide and a monocyte chemotactic protein preparation respectively suppressed and upregulated PAM-1 expression in monocyte-derived macrophages. In contrast, interferon-gamma, although enhancing the levels of class II HLA-DR antigen in monocyte-derived macrophages, did not influence the kinetics of appearance and the levels of PAM-1 in these cells. Thus, expression of PAM-1, which is restricted to certain stages of the monocyte-macrophage differentiation pathway, is also differentially modulated by activation signals, which can be present in the micro-environment of inflammed tissues.

Increased expression of monocyte chemoattractant protein-1 in anti-thymocyte antibody-induced glomerulonephritis

The infiltration of monocytes-macrophages in the glomerulus is one of the hallmarks of glomerulonephritis and may play an important pathogenetic role. Monocyte chemoattractant protein-1 (MCP-1) and colony stimulating factor-1 (CSF-1) are monocyte-specific cytokines with chemoattractant and activating activities for monocytes. MCP-1 and CSF-1 can be generated by several cell types, including glomerular mesangial cells, and can be stimulated by cytokines and immune complexes. To study the expression of CSF-1 and MCP-1 in a model of proliferative glomerulonephritis we used Northern blot analysis and immuno-histochemistry. The glomerular lesion was induced in rats by the i.v. injection of a heterologous anti-thymocyte antiserum (ATS), directed against an antigen which is localized on glomerular mesangial cells. Northern blot analysis revealed comparable amounts of CSF-1 in glomeruli isolated from control untreated rats, and from rats after 30 minutes to three weeks of injection of ATS antibody. In control glomeruli no mRNA levels for MCP-1 were detectable, but increased markedly 30 minutes after the induction of the nephritis, were then reduced at 24 hours and increased again at 5 and 21 days after induction of the disease. The increase in mRNA levels for MCP-1 30 minutes or 24 hours after ATS injection was markedly attenuated if rats were complement depleted by cobra venom injection. These time points following antibody injection were associated with mesangial immune complex formation (30 min), mesangiolysis (24 hr) and proliferative glomerulonephritis (5 and 21 days). By immunohistology the presence of MCP-1 was demonstrated in glomeruli with a predominant mesangial distribution. The mesangial immunofluorescence for MCP-1 followed a pattern similar to that of the mRNA for MCP-1 after induction of the disease process, that is, it increased after 30 minutes, decreased after 24 hours and was increased again at three weeks. Within 30 minutes of the antibody injection an increased infiltration of monocytes-macrophages was observed in the glomeruli, which was maintained up to three weeks of induction of the glomerulonephritis. When the rats were decomplemented with cobra venom factor prior to the i.v. injection of ATS, the expression of MCP-1 in glomeruli remained low and the influx of monocytes/macrophages did not appear. We conclude that MCP-1 is increased early on in glomeruli of rats with immune-mediated mesangial proliferative glomerulonephritis. This increase is mediated by complement activation secondary to the in situ immune complex formation at the glomerular mesangium.(ABSTRACT TRUNCATED AT 400 WORDS)

Synergic in vitro effects of interleukin-2 and tau-interferon on the migration of blood monocytes from control subjects and patients with lung cancer

BACKGROUND

Macrophages can play a major role against cancer by exerting their cytotoxic activity against tumor cells. The presence of macrophages in tumor stroma is related to the recruitment of circulating blood monocytes through the release of chemotactic factors by cancer cells. However, fewer blood monocytes from patients with cancer, such as lung cancer, migrate from in vivo and in vitro, compared with blood monocytes control subjects.

METHODS

Two cytokines, interleukin-2 (IL-2) and tau-interferon (tau-INF), proposed in the treatment of cancer, were tested for their ability to modulate the migratory response in modified Boyden chemotactic chambers of blood monocytes obtained from control subjects and patients with lung cancer in the presence of two chemotactic factors: N-formylmethionyl-leucyl-phenylalanine and complement fraction C5a (C5a).

RESULTS

Incubation with IL-2 and tau-INF resulted in a dose-dependent depression of the migration of blood monocytes from control subjects and patients with lung cancer. IL-2 depression was induced by IL-2 concentrations of 10(5) units/ml, and tau-IFN effects were measured for concentrations of 100 mu/ml. Furthermore, when low concentrations of IL-2 were tested in combination with low concentrations of tau-IFN, dose-dependent depression of blood monocyte migration occurred.

CONCLUSIONS

Dose-dependent depression of blood monocyte migration may modulate the inflammatory component of tumor stroma in patients with lung cancer treated with these cytokines. It may also explain, in part, the high incidence of infections in patients treated with IL-2.

Analysis of monocyte chemoattractant protein 1-mediated lung injury using rat lung organ cultures

Using a rat lung organ culture system, we analyzed the role of monocyte chemoattractant protein 1 (MCP 1) in leukocyte to lung adhesive interactions and monocyte-mediated lung injury. Quantitative leukocyte to lung adhesive interactions were examined using an adaptation of the Woodruff-Stamper frozen section binding assay. Pretreatment of organ cultures with recombinant human tumor necrosis factor (rhTNF alpha) resulted in a protein synthesis-dependent increase in the adhesiveness of lung tissue for peripheral blood monocytes. Adhesion of monocytes to lung tissue was not increased above baseline after 7 hours but increased more than twofold by 24 hours and persisted through 48 hours. Binding of monocyte to lung tissue was further increased when recombinant rat MCP 1 was added to monocyte suspensions immediately before being layered onto lung sections derived from either TNF alpha-treated or untreated organ cultures. Addition of antibody directed against rat CD11b/c resulted in a moderate reduction in monocyte binding. TNF or lipopolysaccharide-induced activation of mononuclear cells in the presence of [3H]leucine-labeled organ cultures resulted in lung injury as assessed by radioisotope release. Mononuclear cell-mediated organ culture injury could be partially inhibited with anti-rat MCP 1 antibody, anti-rat CD11b/c antibody, or antioxidants including catalase and deferoxamine. Anti-MCP 1 and anti-CD11b/c increased the absolute numbers of monocytes that could be retrieved from monocyte-lung co-cultures while catalase and deferoxamine did not. In vitro studies revealed that isolated rat peripheral blood monocytes produce O2- in response to MCP 1. These data provide a functional correlate for recent in vitro studies which suggest that MCP 1 may mediate leukocyte adhesive processes by up-regulating beta 2 integrin expression on monocytes. This study provides evidence that monocytes activated by MCP 1 can damage lung tissue through an oxidant-mediated mechanism. Monocyte chemoattractant protein 1 may participate in the pathogenesis of monocyte-mediated lung injury by modulating inflammatory cell adhesion as well as through monocyte activation.

Expression of monocyte chemoattractant protein-1 (MCP-1) by rat alveolar macrophages during chronic lung injury

Using a well-characterized model of bleomycin-induced pulmonary fibrosis in the rat, we determined that there was a time-dependent elaboration of monocyte chemotactic activity in bronchoalveolar lavage fluid. Northern hybridization analysis revealed markedly increased expression of rat monocyte chemoattractant protein-1 (MCP-1) mRNA in alveolar macrophages (AMs) from rats following induction of pulmonary fibrosis. Monocyte chemotactic activity was also significantly increased in conditioned media from AMs retrieved from injured rat lungs. These data suggest that one important role of AMs in the pathogenesis of chronic inflammatory lung injury and pulmonary fibrosis is the regulation of monocyte recruitment and activation within the lung secondary to secretion of monocyte chemoattractants including MCP-1.

MCP-1 mRNA expression in basal keratinocytes of psoriatic lesions

In addition to hyperproliferation of keratinocytes, psoriasis is characterized by pronounced leukocytic infiltration. In contrast to the epidermal localization of neutrophils and T lymphocytes, macrophages are almost exclusively restricted to the dermal compartment. By immunohistologic analysis, these dermal macrophages were mainly encountered in the papillary dermis and arranged along the rete ridges in close proximity to proliferating keratinocytes. Monocyte chemoattractant protein (MCP-1) anti-sense RNA probes yielded abundant signals over the proliferating basal keratinocytes of the tips of the rete ridges, and, to a lesser extent, in cells in the papillae. Thus, the strongest MCP-1 message in psoriatic lesions is found above the dermal-epidermal junction and this may explain the characteristic sub-basal distribution of dermal macrophages. These results suggest that MCP-1 is important in regulating the interaction between proliferating keratinocytes and dermal macrophages in psoriasis pathogenesis.

Interferon-gamma regulation of human renal cortical epithelial cell-derived monocyte chemotactic peptide-1

The chemoattractant signal(s) that results in the transmigration of monocytes/macrophage into the tubulointerstitium during acute inflammation is not known. Monocyte chemotactic peptide-1 (MCP-1), a recently described chemotactic cytokine, may function as both a potent monocyte chemotaxin and activator in renal inflammation. We have studied the proinflammatory conditions in which cultured human renal cortical epithelial cells (RCEC) of tubular origin may be stimulated to produce MCP-1. RCEC were stimulated in a dose-time dependent manner with: IL-1 beta (0.01 to 1.0 ng/ml), TNF (0.1 to 10 ng/ml), LPS (0.1 to 10 micrograms/ml) or INF-gamma (10-1000 U/ml). Conditioned media from RCEC stimulated with either IL-1 beta or INF-gamma produced a monocyte chemoattractant activity which was significantly suppressed with neutralizing antibody to MCP-1. Stimulation of RCEC with either IL-1 beta or INF-gamma resulted in a significant (4- to 5-fold) increase in steady state levels of MCP-1 mRNA. MCP-1 antigenic peptide in RCEC conditioned media was significantly increased over control (2- to 2.5-fold) after stimulation with either IL-1 beta or IFN-gamma. In contrast, production of interleukin-8 (IL-8), a neutrophil chemotactic cytokine, was not stimulated by IFN-gamma in RCEC. Thus, the chemokine signaling repertoire of renal tubule cells may be selectively controlled by IFN-gamma.

Transformation-associated cytokine 9E3/CEF4 is chemotactic for chicken peripheral blood mononuclear cells

9E3/CEF4, which is released from transformed chicken embryo fibroblasts (CEF), is a member of the platelet factor 4 family of inflammatory proteins and may be the avian homolog of interleukin-8. Since the function of 9E3/CEF4 is unknown, we examined the effect of the protein on mitogenicity and chemotaxis, as well as its expression, in fibroblasts and peripheral blood cells. 9E3/CEF4 mRNA was expressed in chicken peripheral blood monocytes, and its expression was stimulated by incubation of the monocytes with lipopolysaccharide or phorbol myristic acetate. Boyden double-membrane analysis of chemotaxis showed that 9E3/CEF4 was chemotactic for chicken peripheral blood mononuclear cells, as well as for heterophils. Untransformed CEF and CEF transformed with Rous sarcoma virus also migrated to 9E3/CEF4 protein, as measured by Boyden single-membrane analysis. 9E3/CEF4 was slightly mitogenic for CEF, causing a doubling of [3H]thymidine uptake when added to serum-starved CEF.9E3/CEF4 was found associated not only with the cell and in the culture medium of Rous sarcoma virus-transformed CEF but also with the extracellular matrix. The in vivo role of 9E3/CEF4 may be involved with chemotaxis and metastasis, rather than with direct stimulation of mitogenicity.

Detection of monocyte chemoattractant protein-1 in human atherosclerotic lesions by an anti-monocyte chemoattractant protein-1 monoclonal antibody

The infiltration of blood monocytes into the subendothelial space is thought to be one of the most important pathologic events in early atherogenesis. To examine the mechanism of monocyte migration in early atherosclerotic lesions we investigated immunohistochemically the production of monocyte chemoattractant protein-1 (MCP-1) in various atherosclerotic lesions, including diffuse intimal thickening, fatty streaks, and atheromatous plaques, obtained during autopsies of patients of various ages. A highly specific anti-MCP-1 monoclonal antibody that does not cross-react with neutrophil-activating, attractant protein-1/interleukin-8 or platelet proteins that have an amino acid sequence similar to MCP-1 was used to localize MCP-1 in situ. To characterize the cells constituting the atherosclerotic lesions a panel of monoclonal and polyclonal antibodies that are specific to smooth muscle cells (HHF-35), monocyte/macrophages (HAM56, Leu-M3, Leu-M5, EBM11, and PM-2K), and endothelial cells (anti-von Willebrand factor) was used. Double immunohistochemical staining with anti-MCP-1 and one of the cell type-specific antibodies was performed to identify the nature of MCP-1-positive cells. Endothelial cells stained positively for MCP-1 in nine of 14 diffuse intimal thickening lesions. Scattered macrophages in thickened intima also were positive for MCP-1. Endothelial staining of MCP-1 was observed in 14 of 21 fatty streak lesions. Subendothelial macrophages were strongly stained for MCP-1 in all fatty streak lesions examined. Subendothelial macrophages were stained for MCP-1 in atherosclerotic plaques; however, endothelial cells were only slightly positive for MCP-1. A few smooth muscle cells in the intima were positive for MCP-1 in atheromatous plaques. From these results it is concluded that the cell populations positive for MCP-1 are different in early and advanced atherosclerotic lesions, and that the endothelial cells and subendothelial macrophages are considered to be the major sources of MCP-1 in early atherosclerotic lesions.

Enhanced production of the chemotactic cytokines interleukin-8 and monocyte chemoattractant protein-1 in human abdominal aortic aneurysms

Inflammatory leukocytes play a central role in the pathogenesis of human atherosclerotic disease, from early atherogenesis to the late stages of atherosclerosis, such as aneurysm formation. We have shown previously that human abdominal aortic aneurysms are characterized by the presence of numerous chronic inflammatory cells throughout the vessel wall (Am J Pathol 1990, 137: 1199-1213). The signals that attract lymphocytes and monocytes into the aortic wall in aneurysmal disease remain to be precisely defined. We have studied the production of the chemotactic cytokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) by aortic tissues obtained from 47 subjects. We compared the antigenic production of these cytokines by explants of: 1) human abdominal aneurysmal tissue, 2) occlusive (atherosclerotic) aortas, and 3) normal aortas. IL-8, which is chemotactic for neutrophils, lymphocytes, and endothelial cells was liberated in greater quantities by abdominal aortic aneurysms than by occlusive or normal aortas. Using immunohistochemistry, macrophages, and to a lesser degree endothelial cells, were found to be positive for the expression of antigenic IL-8. Similarly, MCP-1, a potent chemotactic cytokine for monocytes/macrophages, was released by explants from abdominal aortic aneurysms in greater quantities than by explants from occlusive or normal aortas. Using immunohistochemistry, the predominant MCP-1 antigen-positive cells were macrophages and to a lesser extent smooth muscle cells. Our results indicate that human abdominal aortic aneurysms produce IL-8 and MCP-1, both of which may serve to recruit additional inflammatory cells into the abdominal aortic wall, hence perpetuating the inflammatory reaction that may result in the pathology of vessel wall destruction and aortic aneurysm formation.

Studies of binding and internalization of human recombinant monocyte chemotactic and activating factor (MCAF) by monocytic cells

Recombinant human monocyte chemotactic and activating factor (MCAF) was iodinated and specific binding sites for this cytokine were detected on human peripheral blood monocytes, the monocytic leukemia cell line THP-1, and on PMA-differentiated HL60 and U937 cell lines. The binding sites were specific for MCAF since other polypeptide cytokines and the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP) failed to compete for 125I-rhMCAF binding. Steady-state binding experiments at 4 degrees C revealed the presence of 13,000 and 18,000 receptor sites/cell on monocytes and THP-1 cells with Kd values of 22.5 nM and 25.7 nM, respectively. Compared to a human natural MCAF, rhMCAF was less potent in inducing maximal monocyte migration. Human natural MCAF similarly competed more efficiently for 125I-rhMCAF binding than unlabelled rhMCAF. The ligand-receptor association was highly temperature-dependent, with maximal ligand uptake at 37 degrees C accompanied by internalization of the ligand-receptor complexes. The internalized 125I-MCAF was progressively degraded and released into the culture medium starting at 30 min. Lysosomotropic ammonium chloride could inhibit the degradation of this ligand suggesting the involvement of lysosomal enzymes in the proteolytic digestion. Incubation with cycloheximide did not block the rapid reappearance of MCAF receptors within 20 min on the cell surface indicative of receptor recycling rather than new protein synthesis. These data indicate that monocytic cells express specific receptors for rhMCAF which can be dynamically regulated by MCAF.

The product of a novel growth factor-activated gene, fic, is a biologically active "C-C"-type cytokine

We have characterized a new member of the superfamily of proinflammatory peptides encoded by a growth factor-inducible gene, fic, previously isolated by differential screening of a cDNA library of mRNA from serum-stimulated NIH 3T3 cells. Immunoprecipitation analyses showed that the protein was rapidly induced following serum stimulation and secreted unglycosylated into the medium. The fic protein, FIC, shows highest sequence homology (57%) to human and rabbit monocyte chemoattractant protein 1 (MCP-1), an established monocyte activator. To determine the biological activity of FIC and to compare it with that of mouse MCP-1 (muMCP-1), both proteins were expressed in the baculovirus system. FIC and muMCP-1 were purified to near homogeneity by a two-step chromatography protocol. Both proteins elicited changes in intracellular calcium concentration in human monocytes. The effect was dependent on external Ca2+ and was inhibited by pretreatment of cells with pertussis toxin. FIC did not desensitize human monocytes to the three related cytokines muMCP-1, human MCP-1 (huMCP-1), and huMCP-2. However, pretreatment with muMCP-1 or huMCP-1, but not with huMCP-2, desensitized human monocytes to FIC. Specific binding of [125I]FIC was found in human monocytes, mouse monocytic cultured cells, and human endothelial cells but not in lymphocytes, neutrophils, or primary mouse fibroblasts. Scatchard analysis of the binding of [125I]FIC to human monocytes showed the presence of two classes of receptors, with apparent KdS of 1.2 and 7.7 nM and receptor numbers per cell of 2,400 and 6,300, respectively. FIC, muMCP-1, and huMCP-1 competed to the same extent for the binding of [125I]FIC to human monocytes, contrary to huMCP-2, which competed very ineffectively, if at all.

The product of a novel growth factor-activated gene, fic, is a biologically active "C-C"-type cytokine

We have characterized a new member of the superfamily of proinflammatory peptides encoded by a growth factor-inducible gene, fic, previously isolated by differential screening of a cDNA library of mRNA from serum-stimulated NIH 3T3 cells. Immunoprecipitation analyses showed that the protein was rapidly induced following serum stimulation and secreted unglycosylated into the medium. The fic protein, FIC, shows highest sequence homology (57%) to human and rabbit monocyte chemoattractant protein 1 (MCP-1), an established monocyte activator. To determine the biological activity of FIC and to compare it with that of mouse MCP-1 (muMCP-1), both proteins were expressed in the baculovirus system. FIC and muMCP-1 were purified to near homogeneity by a two-step chromatography protocol. Both proteins elicited changes in intracellular calcium concentration in human monocytes. The effect was dependent on external Ca2+ and was inhibited by pretreatment of cells with pertussis toxin. FIC did not desensitize human monocytes to the three related cytokines muMCP-1, human MCP-1 (huMCP-1), and huMCP-2. However, pretreatment with muMCP-1 or huMCP-1, but not with huMCP-2, desensitized human monocytes to FIC. Specific binding of [125I]FIC was found in human monocytes, mouse monocytic cultured cells, and human endothelial cells but not in lymphocytes, neutrophils, or primary mouse fibroblasts. Scatchard analysis of the binding of [125I]FIC to human monocytes showed the presence of two classes of receptors, with apparent KdS of 1.2 and 7.7 nM and receptor numbers per cell of 2,400 and 6,300, respectively. FIC, muMCP-1, and huMCP-1 competed to the same extent for the binding of [125I]FIC to human monocytes, contrary to huMCP-2, which competed very ineffectively, if at all.

Tumor necrosis factor-alpha induces cell type and tissue-specific expression of chemoattractant cytokines in vivo

Recombinant murine tumor necrosis factor-alpha (TNF-alpha) was shown to be a strong, systemic stimulus in vivo for members of the chemoattractant cytokine gene families (JE, KC, IP-10). The three genes showed differential sensitivity to TNF-alpha, and their expression demonstrated differential tissue specificity. IP-10 was the most strongly induced messenger RNA and was seen in the liver, kidney, and spleen but very poorly in the lung or skin. JE exhibited a similar pattern, though the magnitude of expression was markedly lower. KC expression was seen only in the liver of TNF-alpha-treated mice. The time course of expression for IP-10 was rapid and transient and showed strong dose dependence. In mice treated with TNF-alpha intravenously, messenger RNA was localized in the splenic stroma but not in adherent macrophages or nonadherent lymphocytes. In situ hybridization found the majority of intercrime expression in the splenic red pulp with little or no expression seen in the white pulp. In vitro, TNF-alpha was a potent stimulus of chemoattractant messenger RNA expression in fibroblasts but not in inflammatory peritoneal macrophages. These results indicate that TNF-alpha may be an important stimulus for chemoattractant cytokine gene expression in vivo, and the primary cell types responsible may be either stromal fibroblasts, microvascular endothelium, and/or a subset of anchored mononuclear phagocytes.

Phagocytosis of Mycobacterium tuberculosis or particulate stimuli by human monocytic cells induces equivalent monocyte chemotactic protein-1 gene expression

Phagocytosis of Mycobacterium tuberculosis by human monocytes or macrophages is classically followed by granuloma formation in vivo. Granuloma are comprised of cells of the monocyte lineage together, in many instances, with antigen-specific T lymphocytes. Development of granuloma depends upon recruitment of both cell types, but recruitment of monocytes is pivotal as these cells secrete anti-mycobacterial cytokines and IL-8, a T cell chemoattractant. We have therefore investigated gene regulation of Monocyte Chemotactic Protein 1 (MCP-1), an important monocyte chemotactic cytokine, following phagocytosis of particulate material (latex beads and zymosan) and live M. tuberculosis by two human monocytic cell lines. In THP-1 cells and phenotypically more differentiated Mono Mac 6 cells, MCP-1 mRNA accumulation was first detectable by Northern analysis of 4 hours and increased over 24 hours. Magnitude and kinetics of MCP-1 gene expression was independent of the biochemical nature of the phagocytic stimulus, M. tuberculosis strain virulence or pre-treatment with anti-TNF. In contrast to the uniform effect of different phagocytic stimuli on MCP-1 gene expression, we have shown that M. tuberculosis but not latex or zymosan, increased IL-8 gene expression, a chemotactic agent for T cells. In additional experiments with THP-1 cells infected with human immunodeficiency virus (HIV), viral infection did not alter MCP-1 gene expression following phagocytosis. MCP-1 gene expression appears to be a conserved antigen-independent response of human monocytic cells which is activated following particulate phagocytosis. MCP-1 gene expression may thus be involved in recruitment of monocytes during granuloma formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of monocyte chemotactic protein-1 in human type B synoviocytes. Synergistic effect of tumor necrosis factor alpha and interferon-gamma

OBJECTIVE

Since local secretion of chemotactic factors could contribute substantially to the homing of monocytes to the rheumatoid synovium, we investigated the ability of type B, or "fibroblast-like," synoviocytes isolated from the synovial tissue of patients with rheumatoid arthritis to synthesize and secrete the novel cytokine monocyte chemotactic protein 1 (MCP-1).

METHODS

Synthesis and secretion of MCP-1 was determined by immunoprecipitation following metabolic labeling of MCP-1 with 35S-cysteine. MCP-1 gene regulation was assessed by Northern blot analysis.

RESULTS

Unstimulated type B synoviocytes released little or no MCP-1, although low levels of MCP-1 messenger RNA (mRNA) were detected. However, incubation of these cells with tumor necrosis factor alpha (TNF alpha) resulted in a time- and dose-dependent release of MCP-1 into the supernatant, and expression of MCP-1 mRNA. Use of cycloheximide and actinomycin D confirmed that TNF alpha was inducing MCP-1 expression at both the transcriptional and translational levels. Treatment of the synoviocytes with interferon-gamma (IFN gamma) also stimulated an increase in both the steady-state levels of MCP-1 mRNA, as well as MCP-1 protein synthesis and secretion. In addition, TNF alpha and IFN gamma in combination exerted a synergistic effect on both MCP-1 mRNA accumulation and protein secretion.

CONCLUSION

These studies demonstrate that the MCP-1 gene is regulated by TNF alpha and IFN gamma in type B synoviocytes and indicate that these cells may play an important role in the recruitment of inflammatory cells to the rheumatoid synovial environment, via the production of novel chemotactic cytokines such as MCP-1.

Common target for 12-O-tetradecanoylphorbol-13-acetate and ras in the transcriptional enhancer of the growth factor-inducible JE gene

JE gene expression in the mouse osteoblast cell line MC3T3-E1 is activated transiently by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). In ras-transformed MC3T3-E1 cells the JE gene is constitutively expressed at a high level, whereas in their raf-transformed counterparts it is not constitutively expressed or inducible by TPA. Using these cells, we investigated a specific sequence recognized by nuclear factors in the 5'-upstream region of the rat JE gene. By gel-mobility shift assays, we determined that the amount of nuclear factors that bind to the region -130 to -96 bp upstream from the cap site of the rat JE gene (JE-1 probe) increased after TPA treatment of MC3T3-E1 cells. However, in the ras transformants it was elevated constitutively, and in the raf transformants it was not detectable. Both unlabeled JE-1 probe and a probe containing a TPA-responsive element (TGACTCA) competed with the binding of these nuclear factors. Preincubation of the nuclear extracts with fos- or jun-specific antibodies interfered with the binding of the factors to the JE-1 probe. The essential sequence in the JE-1 element for the binding of nuclear factors was found to be TTACTCA. c-fos and c-jun proteins synthesized in vitro could bind to the DNA fragment containing this sequence, but the binding was weaker than to the TPA-responsive element (TGACTCA). These results suggest that the sequence TTACTCA in the JE-1 element is a common target of TPA and ras and that protein complexes containing fos- and jun-related proteins recognize the sequence.

Immunoglobulin E plus antigen challenge induces a novel intercrine/chemokine in mouse mast cells

In an attempt to characterize genes participating in the allergic late phase reaction, we have isolated a novel intercrine/chemokine (called MARC) from a cDNA library of the stimulated mouse mast cell line, CPII. As measured by Northern blotting, it is strongly upregulated at the mRNA level after the physiological challenge of the cells with immunoglobulin (Ig)E plus antigen. Unstimulated cells completely lack significant, stable expression, as do a number of other, different cell lines (uninduced and induced) and mouse tissues. In contrast to the Northern blot analysis, a polymerase chain reaction (PCR) analysis, performed on CPII cells and on Percoll gradient purified mouse peritoneal mast cells, revealed a basal level of transcription in the uninduced stage. After 2 h of IgE plus antigen challenge, a quantitative reverse transcriptase-PCR, using a spiked in MIMIC, showed a level of transcripts more than 100-fold higher in the CPII cells and 5-20-fold higher in purified mouse peritoneal cavity mast cells. This rapid induction after the Fc epsilon RI challenge, the identification of the gene as a member of the chemokine family, and its upregulated expression in peritoneal mast cells, all suggest an involvement in certain acute and chronic pathological mast cell-driven diseases.

Monocyte chemoattractant protein-1 (MCP-1) expression in human articular cartilage. Induction by peptide regulatory factors and differential effects of dexamethasone and retinoic acid

Monocyte influx and activation in synovial joints are important in the pathogenesis of both degenerative and inflammatory arthropathies. In this study, we demonstrate the potential of articular cartilage to directly modulate these events. IL-1-stimulated human articular chondrocytes transcribed 0.7-kb monocyte chemoattractant protein-1 (MCP-1) mRNA. In situ hybridization of cartilage organ cultures revealed MCP-1 transcripts in chondrocytes in the superficial tangential zone within 2 h of stimulation with IL-1. Chondrocytes in deeper layers responded by 4 h and reached maximum MCP-1 mRNA levels by 8-12 h. IL-1-stimulated cartilage organ and chondrocyte monolayer cultures released functional monocyte chemotactic activity. This was neutralized by a monoclonal antibody specific for MCP-1, and was associated with the synthesis and secretion of immunoreactive 13-kD and 15-kD isoforms of MCP-1. Regulators and signal transduction pathways involved with the expression of the MCP-1 gene in chondrocytes were analyzed. Steady-state mRNA levels were increased by the known chondrocyte activators IL-1, tumor necrosis factor alpha, LPS, platelet-derived growth factor, and transforming growth factor beta. In addition, leukemia inhibitory factor induced MCP-1 gene expression and protein synthesis, identifying this cytokine as a new regulator of chondrocyte function. Dexamethasone blunted the induction of MCP-1 gene expression by IL-1 and by activators of protein kinase A as well as protein kinase C signal transduction pathways. In contrast, retinoic acid strongly increased phorbol myristate acetate-induced MCP-1 expression and potentiated the effects of IL-1 and LPS. In conclusion, chondrocytes express MCP-1 in response to factors that are present in cartilage or synovium. This provides a mechanism by which cartilage can play an active role in the initiation and progression of arthritis.

Enhanced production of monocyte chemoattractant protein-1 in rheumatoid arthritis

Cells within the synovial tissue may recruit mononuclear phagocytes into the synovial fluid and tissues of arthritic patients. We investigated the production of the chemotactic cytokine monocyte chemoattractant protein-1 (MCP-1) using sera, synovial fluid, synovial tissue, as well as macrophages and fibroblasts isolated from synovial tissues from 80 arthritic patients. MCP-1 levels were significantly higher (P less than 0.05) in synovial fluid from RA patients (mean 25.5 +/- 8.1 ng/ml [SE]) compared to synovial fluid from osteoarthritis (OA) patients (0.92 +/- 0.08), or from patients with other arthritides (2.9 +/- 1.5). MCP-1 levels in RA sera (8.44 +/- 2.33) were significantly greater than MCP-1 in normal sera (0.16 +/- 0.06). The quantities of RA synovial fluid IL-8, which is chemotactic for neutrophils and lymphocytes, and MCP-1 were strongly positively correlated (P less than 0.05). To examine the cellular source of MCP-1, RA synovial tissue macrophages and fibroblasts were isolated. Synovial tissue fibroblasts did not express MCP-1 mRNA, but could be induced to produce MCP-1 by stimulation with either IL-1 beta, tumor necrosis factor-alpha (TNF-alpha), or LPS. In contrast, unlike normal peripheral blood monocytes or alveolar macrophages, RA synovial tissue macrophages constitutively expressed MCP-1 mRNA and antigen. Immunohistochemical analysis of synovial tissue showed that a significantly greater percentage of RA macrophages (50 +/- 8%) as compared to either OA macrophages (5 +/- 2) or normal macrophages (1 +/- 0.3) reacted with anti-MCP-1 antibodies. In addition, the synovial lining layer reacted with MCP-1 in both RA and OA synovial tissues. In contrast, only a minority of synovial fibroblasts (18 +/- 8%) from RA synovium were positive for immunolocalization of MCP-1. These results suggest that synovial production of MCP-1 may play an important role in the recruitment of mononuclear phagocytes during inflammation associated with RA and that synovial tissue macrophages are the dominant source of this cytokine.

Mechanism for the recruitment of macrophages to cancer site. In vivo concentration gradient of monocyte chemotactic activity

BACKGROUND

Tumor stroma is characterized by the development of new blood vessels, an inflammatory cell infiltration, and a fibrotic reaction. The inflammatory component of tumor stroma plays an important role in the modulation of tumor expansion. In this respect, macrophages constitute a major part of the inflammatory cell infiltration and can exert cytotoxic activity against tumor cells. The accumulation of macrophages in the vicinity of the tumor suggests their recruitment from circulating blood monocytes through the local release of chemotactic factors for monocytes.

METHODS

To detect the existence of a concentration gradient of monocyte chemotactic activity (MCA) between the tumor vicinity and blood vessels, malignant pleural effusions defined by the local presence of cancer cells were evaluated for quantification of MCA.

RESULTS

Unlike nonmalignant pleural effusions, malignant pleural effusions were characterized by the presence of increased levels of MCA, and in lung adenocarcinoma (a cancer with high inflammatory cell infiltration), pleural levels of MCA were significantly greater than in small cell lung carcinoma (a cancer with low inflammatory cell reaction). An MCA concentration gradient between pleural fluid and plasma was present in malignant effusions because pleural MCA levels in all cancer types were significantly greater than MCA levels in the plasma of the same patients.

CONCLUSIONS

Thus, an increased local level of MCA is a feature of cancers with high inflammatory cell infiltration, and the presence of an in vivo concentration gradient of MCA suggests the direct role of this biologic activity in recruiting blood monocytes to the cancer site.

Effect of acute inflammatory lung injury on the expression of monocyte chemoattractant protein-1 (MCP-1) in rat pulmonary alveolar macrophages

Using a well-characterized rat model of immune complex-mediated acute inflammatory lung injury, we determined that there is a time-dependent elaboration of monocyte chemotactic activity in bronchoalveolar lavage fluid. Monocyte chemotactic activity is also significantly enhanced in culture supernatants from pulmonary alveolar macrophages (PAMs) from injured rat lungs. Northern hybridization analysis revealed markedly increased expression of rat monocyte chemoattractant protein 1 (MCP-1) mRNA in PAMs obtained from rats with immune complex-induced lung injury. The increased expression of MCP-1 mRNA and associated increase in monocyte chemotactic activity present in culture supernatants of PAMs from injured rat lungs suggest that PAMs may participate in the pathogenesis of acute inflammatory lung injury by the secretion of monocyte chemoattractants including MCP-1.

The origin and function of tumor-associated macrophages

Tumor-associated macrophages (TAM) have a complex relationship with the neoplastic cells of the tumor. On the one hand, the two cell types produce reciprocal growth factors and may be considered to have a symbiotic relationship. On the other hand, TAM can be activated to inhibit tumor growth and destroy neoplastic cells. Here, Alberto Mantovani and colleagues describe this delicate balance and the prospects for its therapeutic manipulation.

Monocyte chemotactic protein 1 is a potent activator of human basophils

Cytokines belonging to the RANTES/SIS family are highly induced in a number of pathophysiological processes such as autoimmune disorders, cancers, atherosclerosis, and chronic inflammation. However, apart from their chemotactic activity on monocytes and particular lymphocyte types, the biological activities in the human system of this recently discovered cytokine family are largely unknown. Here we report that one family member, described as monocyte chemotactic protein 1 (MCP-1), strongly activates mature human basophils in a pertussis toxin-sensitive manner. MCP-1 causes a rise in the cytosolic free calcium level in basophils and monocytes, but not in other blood leukocyte types, and triggers basophil degranulation at low concentrations (ED50 = 3-10 nM). Thus, MCP-1 is a cytokine capable of directly inducing histamine release by basophils. Furthermore, MCP-1 promotes the formation of leukotriene C4 by basophils pretreated with interleukin 3 (IL-3), IL-5, or granulocyte/macrophage colony-stimulating factor. MCP-1-induced basophil mediator release may play an important role in allergic inflammation and other pathologies expressing MCP-1.

JE mRNA accumulates rapidly in aortic injury and in platelet-derived growth factor-stimulated vascular smooth muscle cells

The early response to vascular injury is characterized by migration of inflammatory cells, including monocytes, and platelets to the damaged vessel wall. These inflammatory cells may serve as a source of growth factors and cytokines that stimulate vascular smooth muscle cell (VSMC) migration and proliferation associated with intimal hyperplasia. JE is a platelet-derived growth factor (PDGF)-inducible "early" gene that encodes a monocyte chemoattractant and, as such, could play an important role in inflammation. We now report that JE mRNA levels are increased in intact aorta after balloon injury. The time course of this increase, with maximal levels at 4 hours, is similar to that seen in PDGF-treated cultured rat aortic VSMCs. The accumulation of JE mRNA in cultured VSMCs is accompanied by a marked increase in the secretion of JE protein. The elevation of JE mRNA levels in VSMCs shows specificity for PDGF, because angiotensin II, alpha-thrombin, and epidermal growth factor fail to increase JE mRNA levels. In contrast to 3T3 fibroblasts, the accumulation of JE mRNA in VSMCs in response to PDGF is predominantly due to an increase in JE mRNA stability. The accumulation of JE mRNA in VSMCs stimulated by PDGF appears to occur via a novel pathway(s) independent of Ca2+ mobilization, Na(+)-H+ exchange, protein kinase C activation, or elevation in cAMP levels. These findings suggest that VSMCs may take part in the early inflammatory response after injury through the production of JE, a potent monocyte chemoattractant. Finally, our data suggest that JE may be a marker for PDGF-specific effects on VSMCs, both in vitro and in vivo. Thus, in addition to direct effects on VSMC growth and migration, PDGF may play a role in the early inflammatory response after vascular injury by inducing chemoattractants, such as that encoded by JE.

A sensitive ELISA for the detection of human monocyte chemoattractant protein-1 (MCP-1)

The recruitment of monocytes into tissue is associated with both acute and chronic inflammation. Although monocyte migration is measured in vitro by monocyte chemotaxis, this technique is often difficult to determine the specific quantitative contribution of a monocyte chemotaxin. We have developed a sensitive sandwich ELISA for the detection of monocyte chemoattractant protein-1 (MCP-1), a highly specific monocyte activating/chemotactic peptide. Polyclonal antibodies were generated from rabbits. The IgG fraction of the antiserum was isolated by a protein A column, with a portion of the antibodies biotinylated. Avidin-conjugated horse radish peroxidase was used for enzymatic, colorimetric analysis. The lower threshold for detection of MCP-1 was 50 pg/ml, and the ELISA was specific for MCP-1, since it failed to recognize other cytokines in a dose-dependent fashion. Furthermore, this ELISA had the capacity to measure endothelial cell and pulmonary fibroblast-derived MCP-1. The development of a sensitive ELISA for the detection MCP-1 is significant, since it will allow the measurement MCP-1 from biologically relevant fluids, and aid in establishing whether MCP-1 is present in disease.

Macrophage infiltration and growth of sarcoma clones expressing different amounts of monocyte chemotactic protein/JE

Tumor-derived chemotactic factors (TDCF) have been identified and thought to play a role in the regulation of macrophage infiltration in neoplastic tissues. The present study was designed to assess the in vivo relevance of the TDCF molecularly identified as monocyte chemotactic protein/JE, by investigating murine sarcoma clones expressing different levels of MCP/JE. The 1D3 clone derived from the B77 RSV-induced sarcoma expressed appreciable levels of MCP/JE mRNA and, concomitantly, chemotactic activity for mononuclear phagocytes. In contrast, the 5B11 clone from the same tumor had undetectable levels of MCP/JE transcripts and little or no chemotactic activity. The chemotactic activity of 1D3 cells was blocked by an appropriate specific antiserum. The in vitro growth rate of the 2 sarcoma lines was identical. Upon in vivo transplantation, the 1D3 clone showed a substantially higher level of tumor-associated macrophages (28.9%; range 21%-34%) than the 5B11 clone (16.6%; range 13%-20%). 5B11-induced tumors appeared earlier and grew faster than those induced by 1D3. The difference in growth rate and in macrophage infiltration between 1D3 and 5B11 clones was also evident upon transplantation into nude mice. These results are consistent with the hypothesis that TDCF, identified as MCP/JE, is one important determinant of macrophage infiltration in tumors.

Expression and secretion of leukocyte chemotactic cytokines by normal human melanocytes and melanoma cells

The capacity of human melanocytes and melanoma cells to produce IL-8 and monocyte chemotactic and activating factor (MCAF) was investigated. Melanocytes expressed mRNA for IL-8 and MCAF, when stimulated with either IL-1 alpha or TNF alpha, but not when stimulated with IL-6, IFN gamma, or LPS alone. IL-8 and MCAF could be induced in a dose-dependent fashion with doses as low as 0.1 ng/ml TNF alpha and 0.5 ng/ml IL-1 alpha. IL-8 and MCAF mRNA were rapidly expressed and peaked between 2 and 4 h for IL-8 and between 4 and 8 h for MCAF. This correlated well with the accumulation of IL-8 antigen as measured by a radioimmunoassay. Supernatants from melanocyte cultures stimulated with either IL-1 alpha or TNF alpha and separated on a heparin-Sepharose column became positive for neutrophil and monocyte chemotactic activity in a dose- and time-dependent fashion. When IFN gamma was added to melanocyte cultures stimulated with suboptimal doses of TNF alpha there was a synergistic increase in secreted IL-8 protein and monocyte chemotactic activity. These data provide further evidence for the possible role of melanocytes in the initiation of an inflammatory reaction. Three different malignant melanoma cell lines stimulated with either TNF alpha or IL-1 alpha expressed IL-8 mRNA, but not mRNA for MCAF. The IL-8 mRNA signal corresponded well with the amount of secreted IL-8 protein. These data suggest that IL-8 and MCAF may play a role in growth regulation and spreading of melanomas.

Expression of monocyte chemotactic protein and interleukin-8 by cytokine-activated human vascular smooth muscle cells

The present study was designed to investigate the capacity of human vascular smooth muscle cells (SMCs) to produce a cytokine chemotactic for monocytes (monocyte chemotactic protein [MCP]) and by way of comparison, a related polypeptide activator of neutrophils (known as interleukin-8 [IL-8] or neutrophil activating protein-1 [NAP-1]. On exposure to IL-1, SMCs released high levels of chemotactic activity for monocytes, which could be removed by absorption with anti-MCP antibodies. MCP production by activated SMCs was comparable to that of IL-1-stimulated umbilical vein endothelial cells. Activated SMCs released appreciable levels of IL-8, as determined by a specific enzyme-linked immunosorbent assay, but little chemotactic activity for neutrophils. IL-1-treated SMCs expressed high levels of both MCP and IL-8 mRNA transcripts, as assessed by Northern blot analysis. Tumor necrosis factor and bacterial lipopolysaccharide but not IL-6 also induced MCP and IL-8 gene expression in SMCs. Nuclear runoff analysis revealed that IL-1 augmented transcription of the MCP and IL-8 genes. The capacity of SMCs to produce a cytokine (MCP) that recruits and activates circulating mononuclear phagocytes may be of considerable importance in the pathogenesis of vascular diseases (e.g., vasculitis and atherosclerosis) that are characterized by monocyte infiltration of the vessel wall.

Initial characterization of the carbohydrate structure of MCP-1

MCP-1 is the principle monocyte chemoattractant produced by tumor cells in vitro. We previously identified different isoforms of MCP-1. Here we report that two predominant isoforms of MCP-1 (13 kD and 9 kD) can be distinguished by lectin binding. The results indicate that the disaccharide galactose-beta 1-3D-N-acetyl galactosamine is present on the 13 kD MCP-1 isoform but not the 9 kD isoform. Glycosylation of the 13 kD MCP-1 isoform does not appear to significantly change its antigenic properties and also does not affect its capacity to induce monocyte migration.

Suppression of tumor formation in vivo by expression of the JE gene in malignant cells

The early growth response gene JE encodes a monocyte chemoattractant, MCP-1. The JE/MCP-1 protein attracts and stimulates human monocytes and induces monocyte-mediated inhibition of tumor cell growth in vitro. Expression of human or murine JE/MCP-1 in Chinese hamster ovary (CHO) cells completely suppressed their ability to form tumors in nude mice. Coinjection of JE/MCP-1-expressing cells with nonexpressing CHO cells or with HeLa cells also prevented tumor formation. Since JE/MCP-1 expression had no discernible effect on the tranformed phenotype of these cells in vitro, the suppressive effect depends on host animal factors. These factors are likely to be components of the inflammatory response, because JE/MCP-1-expressing cells elicited a predominantly monocytic infiltrate at the site of injection. Our results suggest that JE/MCP-1 protein may be useful in cancer therapy.

Chemoattractant(s) in culture supernatants of HTLV-I-Infected T-cell lines

Supernatants obtained from four HTLV-I transformed cell lines (MT2, MT4, C91/PL, and 81-66/45) induced in vitro migration of monocytes, polymorphonuclear leukocytes (PMN), and lymphocytes. The MT2, C91/PL, and 81-66/45 cell lines expressed both lymphotoxin (LT) and tumor necrosis factor (TNF-alpha) mRNA transcripts, and had TNF biological activity. In contrast, the MT4 cells did not express LT mRNA, had low levels of TNF-alpha transcript, and no TNF activity in the supernatant. Anti-TNF-alpha MAb, which blocks the chemotactic activity of recombinant TNF-alpha, had no inhibitory effect on the induction of migration by the MT2 and MT4 supernatants. Hence, no correlation was evident between TNF and chemotactic activity in supernatants of different HTLV-I-infected cell lines. Upon fractionation on Sephadex G50, the monocyte chemoattractant(s) eluted with two peaks in the 8-12 kD region, a size compatible with the chemotactic cytokines IL-8 and monocyte chemotactic protein (MCP). However, anti-IL-8 and anti-MCP antibodies did not have any effect, and Northern blot analysis showed that HTLV-I-transformed cell lines did not express mRNA transcripts of either IL-8 and MCP. These results demonstrate that HTLV-I transformed T-cell lines produce chemoattractant(s) active on PMN and monocytes, distinct from LT, TNF-alpha, IL-8, and MCP. Production of chemoattractants may play a role in the pathogenesis of diseases associated with HTLV-I infection.

Production and identification of natural monocyte chemotactic protein from virally infected murine fibroblasts. Relationship with the product of the mouse competence (JE) gene

Primary cultures of mouse embryonic fibroblasts and confluent monolayers of mouse fibroblastoid cells (L929) were found to secrete a chemotactic factor specific for monocytes. It biological activity was deduced from both the migration distance under agarose and the number of migrated monocytes in the micropore filter method. The monocyte chemotactic protein (MCP) was inducible in these cells by double-stranded RNA and by infection with virus. In embryonic fibroblasts MCP was also produced in response to the cytokines interleukin-1 (IL-1) and tumor necrosis factor (TNF). Under all conditions for induction of MCP tested no production of chemotactic activity for granulocytes could be detected. MCP activity from virally infected L929 cells was concentrated and purified by sequential adsorption to controlled pore glass, heparin-Sepharose chromatography, ion-exchange FPLC and reversed-phase HPLC. Pure MCP was found to occur mainly as a 7-8-kDa protein. Although the mature protein possessed a blocked NH2-terminus, it was identified by enzymatic cleavage and sequence analysis of an internal fragment. The sequence obtained corresponded to a part of the cDNA-derived protein sequence of the murine 'competence' (JE) gene, inducible in fibroblasts by cytokines and virus. In all probability the 7-8-kDa MCP form represents the natural product of the mouse gene JE. Murine MCP can thus be classified in the novel family of small inducible inflammatory proteins.