Cloning and sequencing of the cDNA for human monocyte chemotactic and activating factor (MCAF)

TNF-α promotes expression of inflammatory factors by upregulating nicotinamide adenine dinucleotide phosphate oxidase-2 expression in human gingival fibroblasts

Background/purpose

Periodontitis is a chronic infectious disease. The oxidative stress environment can cause or exacerbate the inflammation in periodontitis. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) may be the most important source of reactive oxygen species (ROS) in periodontal tissues. The pathological mechanism of periodontitis may be related to the increased ROS caused by enhanced NOX activity. The purpose was to investigate the effect of tumor necrosis factor (TNF-α) on inflammatory cytokines and ROS, and the role of NOX-2 in human gingival fibroblasts (HGFs).

Materials and methods

HGFs were cultured and divided into the normal control group (NC group) and the inflammatory model group (TNF-α group) induced by 10 ng/ml TNF-α. Thereafter, NOX-2 siRNA was used to knock down NOX-2 gene expression. Quantitative real-time PCR was applied to detect IL-6, MCP-1, and NOX-2 mRNA levels. The levels of IL-6 and MCP-1 protein were examined by ELISA. The level of NOX-2 was evaluated by Western blot. ROS expression was measured by the fluorescence microplate.

Results

The mRNA and protein expression levels of IL-6, MCP-1, and NOX-2 were significantly increased, and the expression of ROS was significantly elevated in response to 10 ng/ml TNF-α. Compared with the si-NC group, the mRNA and protein expression levels of IL-6 and MCP-1 were significantly down-regulated and ROS expression was significantly decreased in the si-NOX2 group stimulated by 10 ng/ml TNF-α.

Conclusion

TNF-α promotes the expression of NOX-2 in human gingival fibroblasts and enhances the expression of inflammatory factors and ROS in human gingival fibroblasts through the upregulation of NOX-2 partly.

Thirty-five years since the discovery of chemotactic cytokines, interleukin-8 and MCAF: A historical overview

Inflammation is a host defense response to various invading stimuli, but an excessive and persistent inflammatory response can cause tissue injury, which can lead to irreversible organ damage and dysfunction. Excessive inflammatory responses are believed to link to most human diseases. A specific type of leukocyte infiltration into invaded tissues is required for inflammation. Historically, the underlying molecular mechanisms of this process during inflammation were an enigma, compromising research in the fields of inflammation, immunology, and pathology. However, the pioneering discovery of chemotactic cytokines (chemokines), monocyte-derived neutrophil chemotactic factor (MDNCF; interleukin [IL]-8, CXCL8) and monocyte chemotactic and activating factor (MCAF; monocyte chemotactic factor 1 [MCP-1], CCL2) in the late 1980s finally enabled us to address this issue. In this review, we provide a historical overview of chemokine research over the last 35 years.

CCL2 regulation of MST1-mTOR-STAT1 signaling axis controls BCR signaling and B-cell differentiation

Chemokines are important regulators of the immune system, inducing specific cellular responses by binding to receptors on immune cells. In SLE patients, decreased expression of CCL2 on mesenchymal stem cells (MSC) prevents inhibition of B-cell proliferation, causing the characteristic autoimmune phenotype. Nevertheless, the intrinsic role of CCL2 on B-cell autoimmunity is unknown. In this study using Ccl2 KO mice, we found that CCL2 deficiency enhanced BCR signaling by upregulating the phosphorylation of the MST1-mTORC1-STAT1 axis, which led to reduced marginal zone (MZ) B cells and increased germinal center (GC) B cells. The abnormal differentiation of MZ and GC B cells were rescued by in vivo inhibition of mTORC1. Additionally, the inhibition of MST1-mTORC1-STAT1 with specific inhibitors in vitro also rescued the BCR signaling upon antigenic stimulation. The deficiency of CCL2 also enhanced the early activation of B cells including B-cell spreading, clustering and signalosome recruitment by upregulating the DOCK8-WASP-actin axis. Our study has revealed the intrinsic role and underlying molecular mechanism of CCL2 in BCR signaling, B-cell differentiation, and humoral response.

Targeting FROUNT with disulfiram suppresses macrophage accumulation and its tumor-promoting properties

Tumor-associated macrophages affect tumor progression and resistance to immune checkpoint therapy. Here, we identify the chemokine signal regulator FROUNT as a target to control tumor-associated macrophages. The low level FROUNT expression in patients with cancer correlates with better clinical outcomes. Frount-deficiency markedly reduces tumor progression and decreases macrophage tumor-promoting activity. FROUNT is highly expressed in macrophages, and its myeloid-specific deletion impairs tumor growth. Further, the anti-alcoholism drug disulfiram (DSF) acts as a potent inhibitor of FROUNT. DSF interferes with FROUNT-chemokine receptor interactions via direct binding to a specific site of the chemokine receptor-binding domain of FROUNT, leading to inhibition of macrophage responses. DSF monotherapy reduces tumor progression and decreases macrophage tumor-promoting activity, as seen in the case of Frount-deficiency. Moreover, co-treatment with DSF and an immune checkpoint antibody synergistically inhibits tumor growth. Thus, inhibition of FROUNT by DSF represents a promising strategy for macrophage-targeted cancer therapy.

The cytoplasmic protein FROUNT can bind to chemokine receptors and enhance chemokine signalling. Here, the authors show that inhibiting FROUNT in macrophages either by knockdown of the gene or using the anti-alcoholism drug disulfiram, results in a reduction in tumour growth.

MIP-1α and MCP-1 as salivary biomarkers in periodontal disease

Aim

Chemokines released by different host cells when exposed to the components of periodontopathic bacteria induce and maintain an inflammatory response in the periodontium. The aim of the study was to estimate the salivary levels of two chemokines, macrophage inflammatory protein-1 alpha (MIP-1α) and monocyte chemo attractant protein-1 (MCP-1) in health, gingivitis and periodontitis and to evaluate their role as reliable salivary biomarkers in discriminating gingivitis and periodontitis from health.

Methods

A cross sectional study was designed to estimate the levels of MIP-1α and MCP-1 in whole unstimulated saliva from 75 patients who were divided into healthy (Group 1, n = 25), gingivitis (Group 2, n = 25) and chronic generalized periodontitis (Group 3, n = 25). MIP-1α and MCP-1 levels were estimated by using ELISA and were correlated with clinical parameters. ROC curve analysis was done to determine the sensitivity and specificity of these biomarkers in distinguishing periodontal disease from health.

Results

Both the biomarkers were detected in all the saliva samples. There was a statistically significant difference in the concentration of both the analytes in Group 3 and Group 2 compared with Group 1 (p < 0.001). ROC curve analysis showed 100% sensitivity and specificity for MIP-1α and MCP-1 in discriminating periodontitis from health. For discriminating gingivitis from health, MIP-1α had a higher sensitivity and specificity (100% & 88% respectively) compared to MCP-1(84.1% & 80% respectively).

Conclusion

There is a substantial increase in the concentration of both MIP-1α and MCP-1 with increasing severity of periodontal disease. Both the analytes showed promising results as biomarkers for discriminating periodontal disease from health.

Chemokine isoforms and processing in inflammation and immunity

The first dimension of chemokine heterogeneity is reflected by their discovery and purification as natural proteins. Each of those chemokines attracted a specific inflammatory leukocyte type. With the introduction of genomic technologies, a second wave of chemokine heterogeneity was established by the discovery of putative chemokine-like sequences and by demonstrating chemotactic activity of the gene products in physiological leukocyte homing. In the postgenomic era, the third dimension of chemokine heterogeneity is the description of posttranslational modifications on most chemokines. Proteolysis of chemokines, for instance by dipeptidyl peptidase IV (DPP IV/CD26) and by matrix metalloproteinases (MMPs) is already well established as a biological control mechanism to activate, potentiate, dampen or abrogate chemokine activities. Other posttranslational modifications are less known. Theoretical N-linked and O-linked attachment sites for chemokine glycosylation were searched with bio-informatic tools and it was found that most chemokines are not glycosylated. These findings are corroborated with a low number of experimental studies demonstrating N- or O-glycosylation of natural chemokine ligands. Because attached oligosaccharides protect proteins against proteolytic degradation, their absence may explain the fast turnover of chemokines in the protease-rich environments of infection and inflammation. All chemokines interact with G protein-coupled receptors (GPCRs) and glycosaminoglycans (GAGs). Whether lectin-like GAG-binding induces cellular signaling is not clear, but these interactions are important for leukocyte migration and have already been exploited to reduce inflammation. In addition to selective proteolysis, citrullination and nitration/nitrosylation are being added as biologically relevant modifications contributing to functional chemokine heterogeneity. Resulting chemokine isoforms with reduced affinity for GPCRs reduce leukocyte migration in various models of inflammation. Here, these third dimension modifications are compared, with reflections on the biological and pathological contexts in which these posttranslational modifications take place and contribute to the repertoire of chemokine functions and with an emphasis on autoimmune diseases.

A Potential Contribution of Chemokine Network Dysfunction to the Depressive Disorders

In spite of many years of research, the pathomechanism of depression has not yet been elucidated. Among many hypotheses, the immune theory has generated a substantial interest. Up till now, it has been thought that depression is accompanied by the activation of inflammatory response and increase in pro-inflammatory cytokine levels. However, recently this view has become controversial, mainly due to the family of small proteins called chemokines. They play a key role in the modulation of peripheral function of the immune system by controlling immune reactions, mediating immune cell communication, and regulating chemotaxis and cell adhesion. Last studies underline significance of chemokines in the central nervous system, not only in the neuromodulation but also in the regulation of neurodevelopmental processes, neuroendocrine functions and in mediating the action of classical neurotransmitters. Moreover, it was demonstrated that these proteins are responsible for maintaining interactions between neuronal and glial cells both in the developing and adult brain also in the course of diseases. This review outlines the role of chemokine in the central nervous system under physiological and pathological conditions and their involvement in processes underlying depressive disorder. It summarizes the most important data from experimental and clinical studies.

Soluble overexpression and purification of bioactive human CCL2 in E. coli by maltose-binding protein

Human chemokine (C-C motif) ligand 2 (hCCL2) is a small cytokine in the CC chemokine family that attracts monocytes, memory T lymphocytes, and natural killer cells to the site of tissue injury- or infection-induced inflammation. hCCL2 has been implicated in the pathogeneses of diseases characterized by monocytic infiltrates, including psoriasis, rheumatoid arthritis, atherosclerosis, multiple sclerosis, and insulin-resistant diabetes. The prokaryotic overexpression of hCCL2 has been investigated previously in an attempt to develop biomedical applications for this factor, but this has been hampered by protein misfolding and aggregation into inclusion bodies. In our present study, we screened 7 protein tags-Trx, GST, MBP, NusA, His8, PDI, and PDIb'a'-for their ability to allow the soluble overexpression of hCCL2. Three tags-MBP, His8, and PDI-solubilized more than half of the expressed hCCL2 fusion proteins. Lowering the expression temperature to 18 °C significantly further improved the solubility of all fusion proteins. MBP was chosen for further study based on its solubility, expression level, ease of purification, and tag size. MBP-CCL2 was purified using conventional chromatography and cleaved using TEV or Factor Xa proteases. Biological activity was assessed using luciferase and cell migration assays. Factor Xa-cleaved hCCL2 was found to be active and TEV-cleaved hCCL2 showed relatively less activity. This is probably because the additional glycine residues present at the N-terminus of hCCL2 following TEV digestion interfere with the binding of hCCL2 to its receptor.

Identification of a binding element for the cytoplasmic regulator FROUNT in the membrane-proximal C-terminal region of chemokine receptors CCR2 and CCR5

Chemokine receptors mediate the migration of leucocytes during inflammation. The cytoplasmic protein FROUNT binds to chemokine receptors CCR2 [chemokine (C-C motif) receptor 2] and CCR5, and amplifies chemotactic signals in leucocytes. Although the interaction between FROUNT and chemokine receptors is important for accurate chemotaxis, the interaction mechanism has not been elucidated. In the present study we identified a 16-amino-acid sequence responsible for high-affinity binding of FROUNT at the membrane-proximal C-terminal intracellular region of CCR2 (CCR2 Pro-C) by yeast two-hybrid analysis. Synthesized peptides corresponding to the CCR2 Pro-C sequence directly interacted with FROUNT in vitro. CCR2 Pro-C was predicted to form an amphipathic helix structure. Residues on the hydrophobic side are completely conserved among FROUNT-binding receptors, suggesting that the hydrophobic side is the responsible element for FROUNT binding. The L316T mutation to the hydrophobic side of the predicted helix decreased the affinity for FROUNT. Co-immunoprecipitation assays revealed that the CCR2 L316T mutation diminished the interaction between FROUNT and full-length CCR2 in cells. Furthermore, this mutation impaired the ability of the receptor to mediate chemotaxis. These findings provide the first description of the functional binding element in helix 8 of CCR2 for the cytosolic regulator FROUNT that mediates chemotactic signalling.

CC chemokine receptors and chronic inflammation--therapeutic opportunities and pharmacological challenges

Chemokines are a family of low molecular weight proteins with an essential role in leukocyte trafficking during both homeostasis and inflammation. The CC class of chemokines consists of at least 28 members (CCL1-28) that signal through 10 known chemokine receptors (CCR1-10). CC chemokine receptors are expressed predominantly by T cells and monocyte-macrophages, cell types associated predominantly with chronic inflammation occurring over weeks or years. Chronic inflammatory diseases including rheumatoid arthritis, atherosclerosis, and metabolic syndrome are characterized by continued leukocyte infiltration into the inflammatory site, driven in large part by excessive chemokine production. Over years or decades, persistent inflammation may lead to loss of tissue architecture and function, causing severe disability or, in the case of atherosclerosis, fatal outcomes such as myocardial infarction or stroke. Despite the existence of several clinical strategies for targeting chronic inflammation, these diseases remain significant causes of morbidity and mortality globally, with a concomitant economic impact. Thus, the development of novel therapeutic agents for the treatment of chronic inflammatory disease continues to be a priority. In this review we introduce CC chemokine receptors as critical mediators of chronic inflammatory responses and explore their potential role as pharmacological targets. We discuss functions of individual CC chemokine receptors based on in vitro pharmacological data as well as transgenic animal studies. Focusing on three key forms of chronic inflammation--rheumatoid arthritis, atherosclerosis, and metabolic syndrome--we describe the pathologic function of CC chemokine receptors and their possible relevance as therapeutic targets.

Autoantibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial disorder with multigenic inheritance and various environmental factors implicated in its aetiopathogenesis. Despite the multiple mechanisms involved in the aetiology of SLE being elusive, recent studies have made progress in our understanding of the pathogenic mechanisms via abnormal regulation of cell-mediated and humoral immunity that lead to tissue damage. The heterogeneity of the clinical manifestations probably reflects the complexity of the disease pathogenesis itself. The immune system in SLE is characterised by a complex interplay between overactive B cells, abnormally activated T cells and antigen-presenting cells. This interplay leads to the production of an array of inflammatory cytokines, apoptotic cells, diverse autoantibodies and immune complexes that in turn activate effector cells and the complement system, leading to tissue injury and damage which are the hallmarks of the clinical manifestations. SLE patients have dysregulation of inflammatory cytokines, chemokines and immune response-related genes, as well as of the genes involved in apoptosis, signal transduction and the cell cycle.

Monocyte Chemoattractant Protein 1 (MCP-1) in obesity and diabetes

Monocyte Chemoattractant Protein-1 (MCP-1) is the first discovered and most extensively studied CC chemokine, and the amount of studies on its role in the etiologies of obesity- and diabetes-related diseases have increased exponentially during the past two decades. This review attempted to provide a panoramic perspective of the history, regulatory mechanisms, functions, and therapeutic strategies of this chemokine. The highlights of this review include the roles of MCP-1 in the development of obesity, diabetes, cardiovascular diseases, insulitis, diabetic nephropathy, and diabetic retinopathy. Therapies that specifically or non-specifically inhibit MCP-1 overproduction have been summarized.

Macrophage infiltration predicts a poor prognosis for human ewing sarcoma

Ewing sarcoma-primitive neuroectodermal tumor (EWS) is associated with the most unfavorable prognosis of all primary musculoskeletal tumors. The objective of the present study was to investigate whether tumor-associated macrophages (TAMs) affect the development of EWS. TAMs were isolated from mouse xenografts using CD11b magnetic beads and examined for their cytokine expression and osteoclastic differentiation. To evaluate the role of TAMs in xenograft formation, liposome-encapsulated clodronate was used to deplete TAMs in mice. Macrophage infiltration and tumor microvascular density were histologically evaluated in 41 patients with EWS, and association with prognosis was examined using Kaplan-Meier survival analysis. In mouse EWS xenografts, TAMs expressed higher concentrations of cytokines including interleukin-6, keratinocyte-derived chemokine, and monocyte chemotactic protein-1. TAMs were more capable than normal monocytes of differentiating into tartrate-resistant acid phosphatase-positive giant cells. Depleting macrophages using liposome-encapsulated clodronate significantly inhibited development of EWS xenografts. In human EWS samples, higher levels of CD68-positive macrophages were associated with poorer overall survival. In addition, enhanced vascularity, increase in the amount of C-reactive protein, and higher white blood cell counts were also associated with poor prognosis and macrophage infiltration. TAMs seem to enhance the progression of EWS by stimulating both angiogenesis and osteoclastogenesis. Further investigation of the behavior of TAMs may lead to development of biologically targeted therapies for EWS.

Neutrophil-dominant experimental autoimmune uveitis in CC-chemokine receptor 2 knockout mice

PURPOSE

Murine experimental autoimmune uveitis (EAU) is an animal model of human uveitis. It has been demonstrated that ocular-infiltrating macrophages are crucial for EAU induction, and monocyte chemoattractant protein-1 (MCP-1) was actually upregulated in the eye. CC chemokine receptor-2 (CCR2) is the receptor of MCP-1, and macrophages fail to recruit particular lesions in CCR2 knockout (KO) mice. To confirm the role of macrophages in EAU, we examined EAU in CCR2 KO mice.

METHODS

CCR2 KO mice and wild-type (WT) mice that had the same genetic background were immunized with human interphotoreceptor retinoid-binding protein peptide 1-20 emulsified in complete Freund's adjuvant. At multiple time-points, EAU severity was evaluated based on microscopic fundus observation and histological examination. To examine the phenotype of retinal-infiltrating cells, single cells were prepared from the eye and analysed by flow cytometry.

RESULTS

In WT mice, EAU was induced at the peak of day 16 and marked macrophage infiltration was observed. Although macrophages failed to be recruited into the eye in CCR2 KO mice, severe uveitis was induced unexpectedly. Flow cytometry and histology revealed that most of the infiltrating cells were neutrophils. We also compared the intraocular chemokine concentrations between WT mice and KO mice. Two CXC chemokine (monokine induced by interferon-γ and interferon-γ-inducible protein-10) were upregulated in KO mice.

CONCLUSION

Interphotoreceptor retinoid-binding protein peptide immunization caused neutrophil-dominant uveitis in CCR2 KO mice. In the absence of macrophages, neutrophils can be alternatively recruited and can cause tissue damage.

Tag SNP polymorphism of CCL2 and its role in clinical tuberculosis in Han Chinese pediatric population

BACKGROUND

Chemokine (C-C motif) ligand 2 CCL2/MCP-1 is among the key signaling molecules of innate immunity; in particular, it is involved in recruitment of mononuclear and other cells in response to infection, including tuberculosis (TB) and is essential for granuloma formation.

METHODOLOGY/PRINCIPAL FINDINGS

We identified a tag SNP for the CCL2/MCP-1 gene (rs4586 C/T). In order to understand whether this SNP may serve to evaluate the contribution of the CCL2 gene to the expression of TB disease, we further analysed distribution of its alleles and genotypes in 301 TB cases versus 338 non-infected controls (all BCG vaccinated) representing a high-risk pediatric population of North China. In the male TB subgroup, the C allele was identified in a higher rate (P = 0.045), and, acting dominantly, was found to be a risk factor for clinical TB (P = 0.029). Homozygous TT genotype was significantly associated with lower CSF mononuclear leukocyte (ML) counts in patients with tuberculous meningitis (TBM) (P = 0.001).

CONCLUSIONS/SIGNIFICANCE

The present study found an association of the CCL2 tag SNP rs4586 C allele and pediatric TB disease in males, suggesting that gender may affect the susceptibility to TB even in children. The association of homozygous TT genotype with decreased CSF mononuclear leukocyte (ML) count not only suggests a clinical significance of this SNP, but indicates its potential to assist in the clinical assessment of suspected TBM, where delay is critical and diagnosis is difficult.

Effect of posttranslational processing on the in vitro and in vivo activity of chemokines

The CXC and CC chemokine gene clusters provide an abundant number of chemotactic factors selectively binding to shared G protein-coupled receptors (GPCR). Hence, chemokines function in a complex network to mediate migration of the various leukocyte subsets, expressing specific GPCRs during the immune response. Further fine-tuning of the chemokine system is reached through specific posttranslational modifications of the mature proteins. Indeed, enzymatic processing of chemokines during an early phase of inflammation leads to activation of precursor molecules or cleavage into even more active or receptor specific chemokine isoforms. At a further stage, proteolytic processing leads to loss of GPCR signaling, thereby providing natural chemokine receptor antagonists. Finally, further NH(2)-terminal cleavage results in complete inactivation to dampen the inflammatory response. During inflammatory responses, the two chemokines which exist in a membrane-bound form may be released by proteases from the cellular surface. In addition to proteolytic processing, citrullination and glycosylation of chemokines is also important for their biological activity. In particular, citrullination of arginine residues seems to reduce the inflammatory activity of chemokines in vivo. This goes along with other positive and negative regulatory mechanisms for leukocyte migration, such as chemokine synergy and scavenging by decoy receptors.

MCP-1: chemoattractant with a role beyond immunity: a review

BACKGROUND

Monocyte Chemoattractant Protein (MCP)-1, a potent monocyte attractant, is a member of the CC chemokine subfamily. MCP-1 exerts its effects through binding to G-protein-coupled receptors on the surface of leukocytes targeted for activation and migration. Role of MCP-1 and its receptor CCR2 in monocyte recruitment during infection or under other inflammatory conditions is well known.

METHOD

A comprehensive literature search was conducted from the websites of the National Library of Medicine (http://www.ncbl.nlm.nih.gov) and Pubmed Central, the US National Library of Medicine's digital archive of life sciences literature (http://www.pubmedcentral.nih.gov/). The data was assessed from books and journals that published relevant articles in this field.

RESULT

Recent and ongoing research indicates the role of MCP-1 in various allergic conditions, immunodeficiency diseases, bone remodelling, and permeability of blood - brain barrier, atherosclerosis, nephropathies and tumors.

CONCLUSION

MCP-1 plays an important role in pathogenesis of various disease states and hence MCP-1 inhibition may have beneficial effects in such conditions.

Chapter 1. Isolation, identification, and production of posttranslationally modified chemokines

Chemokines attract cells during the development of lymphoid tissues, leukocyte homing, and pathologic processes such as cancer and inflammation. Limited posttranslational modification of chemokines may significantly alter the glycosaminoglycan and/or receptor binding properties and signaling potency of these chemotactic proteins. To compare the in vitro and in vivo biologic activities of posttranslationally modified chemokine isoforms, considerable amounts of pure chemokine isoforms are required. This chapter describes a number of chromatographic techniques that are useful for the isolation of natural, posttranslationally modified chemokines from primary human cell cultures. In addition, combination of immunologic assays and biochemical techniques such as automated Edman degradation and mass spectrometry are used for the identification of modifications. Alternate methods for the generation of specific chemokine isoforms are discussed such as modification of chemokines by specific enzymes and total chemical syntheses and folding of chemokine isoforms. In particular, in vitro processing of chemokines by the protease aminopeptidase N/CD13 and citrullination or deamination of chemokines by peptidyl arginine deiminases (PAD) are described as methods for the confirmation or generation of posttranslationally modified chemokine isoforms.

A role of monocyte chemoattractant protein-4 (MCP-4)/CCL13 from chondrocytes in rheumatoid arthritis

We studied the role of monocyte chemoattractant (MCP)-4/CCL13 in the pathogenesis of rheumatoid arthritis (RA). MCP-4 was highly expressed in cartilage from RA patients. Interferon-gamma significantly stimulated MCP-4/CCL13 production in human chondrocytes, and this effect was enhanced in combination with interleukin-1beta or tumor necrosis factor-alpha. MCP-4/CCL13 induces the phosphorylation of extracellular signal-regulated kinase in fibroblast-like synoviocytes and activates cell proliferation, and PD98059 completely inhibits these effects. These data suggest that interferon-gamma in combination with interleukin-1beta/tumor necrosis factor-alpha activates the production of MCP-4/CCL13 from chondrocytes in RA joints, and that secreted MCP-4/CCL13 enhances fibroblast-like synoviocyte proliferation by activating the extracellular signal-regulated kinase mitogen-activated protein kinase cascade.

Monocyte chemoattractant protein-1 transfection induces angiogenesis and tumorigenesis of gastric carcinoma in nude mice via macrophage recruitment

PURPOSE

Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that has various roles in tumor development and progression. We previously reported that expression of MCP-1 is associated with macrophage infiltration and tumor vessel density in human gastric carcinomas. The present study was undertaken to obtain direct evidence that MCP-1 participates in recruitment of macrophages and induction of angiogenesis.

EXPERIMENTAL DESIGN

We did transfection experiments to analyze the role of MCP-1 in tumorigenicity and angiogenesis in gastric carcinoma in nude mice. The human MCP-1 gene cloned into the BCMGS-Neo expression vector was transfected into the human gastric carcinoma TMK-1 cell line. We examined tumor volumes with the ectopic s.c. xenograft model and tumorigenicity with the orthotopic gastric xenograft model. We determined intratumor microvessel counts and tumor-infiltrating macrophage counts by immunohistochemical staining.

RESULTS

There was no difference in in vitro proliferation between MCP-1-transfected TMK-1 cells and mock-transfected (control) cells; however, MCP-1 transfectants induced tumor growth in ectopic xenografts and increased tumorigenicity and induced lymph node metastases and ascites in orthotopic xenografts. In both ectopic and orthotopic xenograft models, strong infiltration of macrophages was observed within and around the tumors after implantation of MCP-1 transfectants whereas fewer macrophages were seen after inoculation of control cells. The microvessel density was significantly higher in tumors produced by MCP-1 transfectants than in control tumors.

CONCLUSIONS

MCP-1 produced by gastric carcinoma cells may regulate angiogenesis via macrophage recruitment. MCP-1 may be a potential target for antiangiogenic therapy for gastric carcinoma.

Synthetic, site-specific biotinylated analogs of human MCP-1

Human monocyte chemoattractant protein 1 (MCP-1, CCL2) is a 8.6-kDa protein that has been implicated in a number of diseases including atherosclerosis, rheumatoid arthritis, chronic obstructive pulmonary disease and cancer. As part of a program to identify antibodies against MCP-1, we synthesized site-specific, biotinylated human MCP-1 analogs to be used for panning of an antibody phage display library. In contrast to material obtained from random biotinylation, the site-specific biotinylated analogs were homogeneous and retained full activity.

Prostaglandin E2 promotes degranulation-independent release of MCP-1 from mast cells

Mast cells (MCs) are common components of inflammatory infiltrates and a source of proangiogenic factors. Inflammation is often accompanied by vascular changes. However, little is known about modulation of MC-derived proangiogenic factors during inflammation. In this study, we evaluated the effects of the proinflammatory mediator prostaglandin E2 (PGE2) on MC expression and release of proangiogenic factors. We report that PGE2 dose-dependently induces primary MCs to release the proangiogenic chemokine monocyte chemoattractant protein-1 (MCP-1). This release of MCP-1 is complete by 2 h after PGE2 exposure, reaches levels of MCP-1 at least 15-fold higher than background, and is not accompanied by degranulation or increased MCP-1 gene expression. By immunoelectron microscopy, MCP-1 is detected within MCs at a cytoplasmic location distinct from the secretory granules. Dexamethasone and cyclosporine A inhibit PGE2-induced MCP-1 secretion by approximately 60%. Agonists of PGE2 receptor subtypes revealed that the EP1 and EP3 receptors can independently mediate MCP-1 release from MCs. These observations identify PGE2-induced MCP-1 release from MCs as a pathway underlying inflammation-associated angiogenesis and extend current understanding of the activities of PGE2.

Synthesis and biological characterization of human monocyte chemoattractant protein 1 (MCP-1) and its analogs

Novel analogs of human monocyte chemoattractant protein 1 (MCP-1) were designed, synthesized and characterized to be used as tools to generate monoclonal antibodies as potential human therapeutics. MCP-1 and three analogs were synthesized by step-wise Fmoc solid phase synthesis. After oxidation to form the two-disulfide bonds, affinity chromatography using an immobilized mouse anti-human MCP-1 monoclonal antibody (mAb) was utilized for a simple and highly effective purification procedure for the proteins. The final products were extensively characterized and compared with recombinant human MCP-1 (rhMCP-1). All proteins showed identical binding with mouse anti-human MCP-1 mAbs as measured by surface plasmon resonance. Synthetic MCP-1 and the analogs were comparable to recombinant MCP-1 in competition radio-ligand binding to CCR2 receptors on THP-1 cells, and MCP-1-induced, calcium mobilization and chemotaxis assays.

Human neutrophils synthesize IL-8 in an IgE-mediated activation

It has been demonstrated that neutrophils are responsible for the release of large amounts of the inflammatory chemokine interleukin-8 (IL-8), associated with inflammation. To further define the mechanisms implicated, we have analyzed the response of human neutrophils from allergic patients to specific antigens or challenge with anti-immunoglobulin (Ig)E antibodies. Neutrophils showed a dose- and time-dependent production of IL-8. The release of the cytokine was parallel to expression of IL-8 mRNA analyzed by the polymerase chain reaction. This expression was transient-it occurred after 3 h of anti-IgE treatment and was maintained for 18 h. Trifluoperazine, EGTA, reduced nicotinamide adenine dinucleotide phosphate-oxidase inhibitors, and reactive oxygen species (ROS) scavengers inhibited IL-8 production, indicating a critical dependence of calcium and oxidative stress. Moreover, an inhibitory effect of cyclosporin A, an immunosuppressor that inhibits calcineurin activity, on IL-8 release and IL-8 mRNA expression was observed. This is the first evidence of the involvement of ROS and calcium/calcineurin in IgE-dependent IL-8 production. These findings open new perspectives into the functional role of neutrophils in IgE-associated diseases.

hTERT-promoter-based tumor-specific expression of MCP-1 effectively sensitizes cervical cancer cells to a low dose of cisplatin

Cervical cancers at advanced stages or with recurrent status are mainly treated by platinum-based chemotherapy, such as cisplatin. However, a novel strategy to reduce the minimally effective dose is required to prevent severe adverse effects that limit the effectiveness of the treatment. Monocyte chemoattractant protein-1 (MCP-1) is a subtype of chemokines that can promote monocyte/macrophage infiltration and enhance their phagocytosis at not only sites of inflammatory lesions but also of tumors. The present study applies MCP-1-based gene therapy to treat cervical cancers. To achieve tumor-specific expression of MCP-1, retroviral expression vector was constructed using the human telomerase reverse transcriptase gene (hTERT) promoter. Retroviral expression of MCP-1 into cervical cancer ME180 cells did not affect their proliferation either in vitro or in vivo. However, when combined with a suboptimal low dose of cisplatin, tumor formation was obviously reduced in clones transduced with MCP-1, but not in control clones. Histological examination revealed that a substantial number of macrophages infiltrated the tumor sites of MCP-1-transduced cells, but not of controls. These findings suggest that MCP-1 expression sensitizes cervical cancer cells to an otherwise ineffective low dose of cisplatin, possibly by inducing the migration of macrophages to eradicate tumor cells. This system may be a novel strategy for chemotherapy combined with immunogene therapy against otherwise intractable cervical cancers.

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

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

Potential involvement of monocyte chemoattractant protein (MCP)-1/CCL2 in IL-4-mediated tumor immunity through inducing dendritic cell migration into the draining lymph nodes

We previously observed that IL-4 gene transduction into a mouse colon 26 adenocarcinoma cell line abrogated its tumorigenicity due to the generation of anti-tumor CTL. DEC-205- and CD11c-double positive cells were increased in the lymph nodes of mice injected with IL-4-transfected cells between 2 and 3 days after the tumor injection, compared with those injected with parental cells. Most of these double positive cells expressed CD86 antigen. Among the chemokines with chemotactic activities against dendritic cells, monocyte chemoattractant protein (MCP)-1/CCL2, ABCD-1/CCL22, and liver and activation-regulated chemokine (LARC)/CCL20 gene expression was enhanced no later than 3 days after the tumor injection, in the draining lymph nodes of IL-4-transfected cell bearing mice. Moreover, gene expression of the receptor for MCP-1/CCL2, CCR2, was enhanced in the draining lymph nodes of the mice injected with IL-4-transfected cells, and most DEC-205-positive cells in the lymph nodes expressed CCR2. Finally, the administration of anti-MCP-1/CCL2 antibodies retarded the rate of tumor regression in mice injected with IL-4-tranfected cells, concomitantly with a decrease in DEC-205- and CD11c-double positive cell number in the draining lymph nodes. Thus, locally produced MCP-1/CCL2 may be responsible for IL-4-mediated tumor rejection presumably based on the induction of dendritic cell migration into the draining lymph nodes.

Induction of IL-8 and monoclyte chemoattractant protein-1 by doxorubicin in human small cell lung carcinoma cells

We previously demonstrated doxorubicin-induced urokinase expression in human H69 SCLC cells by the microarray technique using Human Cancer CHIP version 2 (Takara Shuzo, Kyoto, Japan), in which 425 human cancer-related genes were spotted on glass plates (Kiguchi et al., Int J Cancer 2001;93:792-7). Microarray analysis also revealed significant induction of IL-8, a member of the CXC chemokines. We have, therefore, extended the observation by testing the effects of doxorubicin on expression of the chemokine family and provide here definitive evidence that doxorubicin induces IL-8 and MCP-1, one of the CC chemokines, at least in 2 human SCLC cells, H69 and SBC-1. IL-8 antigen levels, measured by ELISA, were markedly increased in both H69 and SBC-1 conditioned media after doxorubicin treatment, in parallel with mRNA levels; and this was dependent on the dose of doxorubicin. The ribonuclease protection assay, using a multiprobe template set for human chemokines, revealed induction of not only IL-8 but also MCP-1 in doxorubicin-treated H69 cells. MCP-1 antigen levels increased approximately 100-fold in doxorubicin-treated H69 cells. RT-PCR using specific primers for MCP-1 suggested that doxorubicin also induced MCP-1 expression in SBC-1 and SBC-3 SCLC cells. Futhermore, CAT analysis using IL-8 promoter implicated the PEA3 transcriptional factor, whose binding site was located immediately upstream of the AP-1 and NF-kappaB binding sites. Thus, it is suggested that doxorubicin induces IL-8 and MCP-1 chemokines in human SCLC cells by activating gene expression, in which at least PEA3 is involved. IL-8 and MCP-1 are major chemoattractants for neutrophils and monocytes/macrophages, respectively; therefore, extensive induction of IL-8 and MCP-1 may provoke the interaction between inflammatory/immune cells and tumor cells under doxorubicin stimulation and influence many aspects of tumor cell biology.

Keratinocyte gene therapy: cytokine gene expression in local keratinocytes and in circulation by introducing cytokine genes into skin

Using the plasmid DNA injection method, we introduced cytokine genes into skin to determine whether systemic expression of cytokine genes is possible. Eight human cytokine [interleukin-4 (IL-4), IL-6, IL-10, transforming growth factor beta1 (TGF-beta1), monocyte chemotactic and activating factor (MCAF), granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma)] gene expression vectors were constructed and injected into rat skin. Transgenic cytokines in local keratinocytes and in the sera were assayed with ELISA. Our results showed that transgenic cytokines were markedly increased in keratinocytes at the injection site. The serum concentrations of IL-4, 6, 10 and TauGF-beta1 reached levels high enough to have systemic biologic effects. However, other cytokines used in this study could not be detected in the sera. Moreover, the serum transgenic IL-10 level after subcutaneous injection was significantly higher than after intramuscular injection. We suggest that keratinocytes can be used as a bioreactor to achieve systemic expression of cytokine genes by DNA injection, but the transgenic protein level in circulation depends on different kinds of cytokine. This level also depends on different target cells used for gene transfer.

Leucocyte chemotaxis: Examination of mitogen-activated protein kinase and phosphoinositide 3-kinase activation by Monocyte Chemoattractant Proteins-1, -2, -3 and -4

Monocyte Chemoattractant Proteins (MCPs) form a distinct, structurally-related subclass of CC chemokines. They are major chemoattractants for monocytes and T lymphocytes. The MCPs bind to specific G-protein-coupled receptors, initiating a signal cascade within the cell. Though the signal transduction pathways involved in MCP-1-mediated chemotaxis have been studied, the signalling pathways through which MCP-2, -3 and -4 trigger cell migration are not established. In this study, we examined the mitogen-activated protein kinase (MAPK) activation elicited by the MCPs (1-4) and its specific role in chemotaxis. Within 2 min, the MCPs (1-4) elicited a rapid and transient activation of MAPK in peripheral blood mononuclear cells and in HEK-293 cells expressing CCR2b. U0126, an inhibitor of MAPK-kinase (MEK) activation, not only prevented extracellular signal-regulated kinase 1/2 (ERK1/2) activation but also significantly inhibited the MCP-mediated chemotaxis. PI3K inhibitors Wortmannin and LY294002 also partially inhibited the MCP-induced chemotaxis. However, these compounds did not significantly inhibit ERK1/2 activation. As PI3K inhibitors partially inhibit the MCP-mediated chemotaxis but do not significantly effect ERK1/2 activation, these data suggest that co-ordinated action of distinct signal pathways is required to produce chemokine-mediated chemotaxis.

Chemokines in immunity

Chemokines are a superfamily of small, heparin-binding cytokines that induce directed migration of various types of leukocytes through interactions with a group of seven-transmembrane G protein-coupled receptors. At present, over 40 members have been identified in humans. Until a few years ago, chemokines were mainly known as potent attractants for leukocytes such as neutrophils and monocytes, and were thus mostly regarded as the mediators of acute and chronic inflammatory responses. They had highly complex ligand-receptor relationships and their genes were regularly mapped on chromosomes 4 and 17 in humans. Recently, novel chemokines have been identified in rapid succession, mostly through application of bioinformatics on expressed sequence tag databases. A number of surprises have followed the identification of novel chemokines. They are constitutively expressed in lymphoid and other tissues with individually characteristic patterns. Most of them turned out to be highly specific for lymphocytes and dendritic cells. They have much simpler ligand-receptor relationships, and their genes are mapped to chromosomal loci different from the traditional chemokine gene clusters. Thus, the emerging chemokines are functionally and genetically quite different from the classical "inflammatory chemokines" and may be classified as "immune (system) chemokines" because of their profound importance in the genesis, homeostasis and function of the immune system. The emergence of immune chemokines has brought about a great deal of impact on the current immunological research, leading us to a better understanding on the fine traffic regulation of lymphocytes and dendritic cells. The immune chemokines and their receptors are also likely to be important future targets for therapeutic intervention of our immune responses.

Lack of CCR2 results in increased mortality and impaired leukocyte activation and trafficking following infection of the central nervous system with a neurotropic coronavirus

In the present study, we evaluated the role of CCR2 in a model of viral-induced neurologic disease. An orchestrated expression of chemokines, including the CCR2 ligands monocyte chemoattractant protein-1/CCL2 and monocyte chemoattractant protein-3/CCL7, occurs within the CNS following infection with mouse hepatitis virus (MHV). Infection of mice lacking CCR2 (CCR2(-/-)) with MHV resulted in increased mortality and enhanced viral recovery from the brain that correlated with reduced (p < or = 0.04) T cell and macrophage/microglial (determined by F4/80 Ag expression, p < or = 0.004) infiltration into the CNS. Moreover, MHV-infected CCR2(-/-) mice displayed a significant decrease in Th1-associated factors IFN-gamma (p < or = 0.001) and RANTES/CCL5 (p < or = 0.002) within the CNS as compared with CCR2(+/+) mice. Further, peripheral CD4(+) and CD8(+) T cells from immunized CCR2(-/-) mice displayed a marked reduction in IFN-gamma production in response to viral Ag and did not migrate into the CNS of MHV-infected recombination-activating gene (RAG)1(-/-) mice following adoptive transfer. In addition, macrophage/microglial infiltration into the CNS of RAG1(-/-) mice receiving CCR2(-/-) splenocytes was reduced (p < or = 0.05), which correlated with a reduction in the severity of demyelination (p < or = 0.001) as compared with RAG1(-/-) mice receiving splenocytes from CCR2(+/+) mice. Collectively, these results indicate an important role for CCR2 in host defense and disease by regulating leukocyte activation and trafficking.

Inhibition of monocyte chemoattractant protein-1 expression in cytokine-treated human lung epithelial cells by thiazolidinedione

STUDY OBJECTIVE

Several lung diseases are characterized by the presence of increased numbers of activated macrophages. The recruitment and activation of peripheral blood monocytes are potentially critical regulatory events for the control of pulmonary inflammation. The chemokine monocyte chemoattractant protein (MCP)-1 is a potent chemoattractant for monocytes. MCP-1 is produced by lung epithelial cells during the course of inflammatory lung diseases. In the present study, we examined the effects of a thiazolidinedione (TZD), which is used to improve the insulin resistance of individuals with diabetes mellitus, on MCP-1 expression in a human lung epithelial cell line, A549.

MEASUREMENTS AND RESULTS

In A549 cells, interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha induced endogenous MCP-1 protein secretion and messenger RNA expression. The TZD inhibited the increase of MCP-1 secretion by IL-1beta and TNF-alpha treatment. The TZD inhibited the expression of MCP-1 messenger RNA with IL-1beta treatment, but not with TNF-alpha treatment. This observation was confirmed by the results of a monocyte chemotactic assay. The transcriptional activity of human MCP-1 promoter in A549 cells paralleled the endogenous messenger RNA expression by cytokines and TZD treatment.

CONCLUSIONS

Our findings indicated that the suppression of the expression of MCP-1 could be accomplished by TZD treatment, raising the possibility that TZD may be of therapeutic value in several lung diseases in which MCP-1 plays an important role.

Functional differences between monocyte chemotactic protein-1 receptor A and monocyte chemotactic protein-1 receptor B expressed in a Jurkat T cell

The monocyte chemotactic protein-1 (MCP-1) receptor (MCP-1R) is expressed on monocytes, a subpopulation of memory T lymphocytes, and basophils. Two alternatively spliced forms of MCP-1R, CCR2A and CCR2B, exist and differ only in their carboxyl-terminal tails. To determine whether CCR2A and CCR2B receptors function similarly, Jurkat T cells were stably transfected with plasmids encoding the human CCR2A or CCR2B gene. Nanomolar concentrations of MCP-1 induced chemotaxis in the CCR2B transfectants that express high, intermediate, and low levels of MCP-1R. Peak chemotactic activity was shifted to the right as receptor number decreased. Five-fold more MCP-1 was required to initiate chemotaxis of the CCR2A low transfectant, but the peak of chemotaxis was similar for the CCR2A and CCR2B transfectants expressing similar numbers of receptors. MCP-1-induced chemotaxis was sensitive to pertussis toxin, implying that both CCR2A and CCR2B are G(i)alpha protein coupled. MCP-1 induced a transient Ca(2+) flux in the CCR2B transfectant that was partially sensitive to pertussis toxin. In contrast, MCP-1 did not induce Ca(2+) flux in the CCR2A transfectant. Since MCP-1 can stimulate chemotaxis of the CCR2A transfectant without inducing Ca(2+) mobilization, Ca(2+) flux may not be required for MCP-1-induced chemotaxis in the Jurkat transfectants. These results indicate that functional differences exist between the CCR2A and CCR2B transfectants that can be attributed solely to differences in the carboxyl-terminal tail.

Up-regulation of monocyte chemoattractant protein-1 in tubulointerstitial lesions of human diabetic nephropathy

BACKGROUND

We previously described that monocyte chemoattractant protein-1 (MCP-1) plays an important role in progressive glomerular and interstitial damage in inflammatory renal diseases. However, the expression of MCP-1 in diabetic nephropathy remains to be investigated.

METHODS

We examined whether locally expressed MCP-1 participates in human diabetic nephropathy via recruiting and activating monocytes/macrophages (Mphi). Urinary and serum MCP-1 levels were measured by enzyme-linked immunosorbent assay in 45 patients with diabetic nephropathy. The presence of MCP-1 in diseased kidneys was determined by immunohistochemical and in situ hybridization analyses.

RESULTS

Urinary MCP-1 levels were significantly elevated in patients with diabetic nephrotic syndrome and advanced tubulointerstitial lesions. Moreover, urinary levels of MCP-1 were well correlated with the number of CD68-positive infiltrating cells in the interstitium. In contrast, serum MCP-1 levels remained similar to those of healthy volunteers. Furthermore, we detected the MCP-1-positive cells in the interstitium of diabetic nephropathy via both immunohistochemical and in situ hybridization analyses.

CONCLUSION

These observations suggest that locally produced MCP-1 may be involved in the development of advanced diabetic nephropathy, especially in the formation of tubulointerstitial lesions possibly through Mphi recruitment and activation. Moreover, up-regulation of MCP-1 may be a common pathway involved in the progressive tubulointerstitial damage in diabetic nephropathy as well as inflammatory renal diseases.

Induction of the chemokines interleukin-8 and IP-10 by human immunodeficiency virus type 1 tat in astrocytes

A finding commonly observed in human immunodeficiency virus type 1 (HIV-1)-infected patients is invasion of the brain by activated T cells and infected macrophages, eventually leading to the development of neurological disorders and HIV-1-associated dementia. The recruitment of T cells and macrophages into the brain is likely the result of chemokine expression. Indeed, earlier studies revealed that levels of different chemokines were increased in the cerebrospinal fluid of HIV-1-infected patients whereas possible triggers and cellular sources for chemokine expression in the brain remain widely undefined. As previous studies indicated that HIV-1 Tat, the retroviral transactivator, is capable of inducing a variety of cellular genes, we investigated its capacity to induce production of chemokines in astrocytes. Herein, we demonstrate that HIV-1 Tat(72aa) is a potent inducer of MCP-1, interleukin-8 (IL-8), and IP-10 expression in astrocytes. Levels of induced IP-10 protein were sufficiently high to induce chemotaxis of peripheral blood lymphocytes. In addition, Tat(72aa) induced IL-8 expression in astrocytes. IL-8 mRNA induction was seen less then 1 h after Tat(72aa) stimulation, and levels remained elevated for up to 24 h, leading to IL-8 protein production. Tat(72aa)-mediated MCP-1 and IL-8 mRNA induction was susceptible to inhibition by the MEK1/2 inhibitor UO126 but was only modestly decreased by the inclusion of the p38 mitogen-activated protein kinase (MAPK) inhibitor SB202190. In contrast, Tat-mediated IP-10 mRNA induction was suppressed by SB202190 but not by the MEK1/2 inhibitor UO126. These findings indicate that MAPKs play a major role in Tat(72aa)-mediated chemokine induction in astrocytes.

Molecular analysis of the inhibition of monocyte chemoattractant protein-1 gene expression by estrogens and xenoestrogens in MCF-7 cells

Xenoestrogens (XEs) are a diverse group of chemicals that mimic estrogenic actions and may have adverse effects on human health. The influence of these compounds on cytokine production or immune system function remains unclear. In this study we have examined the effects of 17beta-estradiol (E2) and XEs on chemoattractant cytokine (chemokine) production and analyzed the molecular mechanism. Monocyte chemoattractant protein-1 (MCP-1), also termed monocyte chemotactic and activating factor, is a member of the chemokine family and attracts mainly blood monocytes. Human mammary tumor cell line MCF-7 cells produce a large quantity of MCP-1 in response to interleukin-1alpha (IL-1alpha). Addition of E2 to MCF-7 cells inhibited MCP-1 production in a dose-dependent manner. XEs, bisphenol A, and NP also inhibited MCP-1 production, although the potency was 3-4 orders of magnitude lower than that of E2. E2, bisphenol A, and NP inhibited MCP-1 messenger RNA expression in MCF-7 cells. Two closely located nuclear factor-kappaB sites, A1 and A2, have been identified in the promoter of the human MCP-1 gene. A luciferase construct containing this enhancer region (pGLM-ENH) was activated by IL-1alpha, and a mutation at either the A1 or A2 site resulted in a loss of IL-1alpha responsiveness. Treatment with E2 or XEs decreased the IL-1alpha-inducible pGLM-ENH luciferase activity significantly. In an electrophoretic mobility shift assay and supershift analysis, we found that treatment with E2 or XEs diminished the IL-1alpha-induced complex formation with both A1 and A2 probes, which was identified immunochemically to consist of nuclear factor-kappaB, p50, and p65. The IL-1alpha-induced p50/c-Rel complex to the A2 probe was also, to a lesser extent, decreased by E2 or XE treatment. The effects of E2 and XEs on the expression of MCP-1 seem to be much more dramatic than the effects of these agents on the promoters used in the luciferase assay, suggesting the involvement of an additional site(s) of the promoter region of the MCP-1 gene or posttranscriptional regulation of MCP-1 gene expression by E2 and XEs. This work represents the first report describing possible regulation of immune system function by XEs through inhibiting chemokine production.

Rat macrophage inflammatory protein-1alpha, a CC chemokine, acts as a neutrophil chemoattractant in vitro and in vivo

Recombinant rat macrophage inflammatory protein-1alpha (rMIP-1alpha) at a concentration of 3x10(-8) M had strong neutrophil chemotactic activity, though the potency of rMIP-1alpha was less than that of cytokine-induced neutrophil chemoattractant (CINC)-1 at lower concentrations. In addition, rMIP-1alpha induced neutrophil chemotaxis in vivo when rMIP-1alpha was injected into the preformed air-pouch on the back of rats. The adhesion of rMIP-1alpha-treated neutrophils to fibrinogen significantly increased, reaching a maximum adhesion at 10(-8) M. Stimulation of neutrophils with rMIP-1alpha induced a transient increase in intracellular free [Ca2+] dose-dependently. rMIP-1alpha still induced an increase in the intracellular [Ca2+] of rat neutrophils stimulated first with CINC-1, CINC-3 or C5a, suggesting that rat neutrophils have a specific receptor for rMIP-1alpha. Supporting these findings, an additive increase in chemotactic potency was found when both rMIP-1alpha and CINC-were added to the lower wells of Boyden chamber in vitro. In addition, high levels of rMIP-1alpha were detected in the inflammatory site of air-pouch/carrageenan-induced inflammation in rats. Our results suggest that rMIP-1alpha acts as a neutrophil chemoattractant and, together with CINCs, plays an important role in infiltration of neutrophils into inflammatory sites in rats.

Identification of a novel dexamethasone-sensitive RNA-destabilizing region on rat monocyte chemoattractant protein 1 mRNA

Glucocorticoids are potent anti-inflammatory agents widely used in the treatment of human disease. We have previously shown that the inflammatory cytokine monocyte chemoattractant protein 1 (MCP-1) is regulated posttranscriptionally by glucocorticoids in arterial smooth muscle cells (SMC). To elucidate the mechanism mediating this effect, in vitro-transcribed radiolabeled MCP-1 mRNA was incubated with cytoplasmic extracts from SMC and analyzed by gel electrophoresis. Extracts from SMC treated with platelet-derived growth factor (PDGF) did not degrade the transcripts for up to 3 h. In contrast, extracts from cells treated with 1 microM dexamethasone (Dex) alone or in combination with PDGF degraded the probe with a half-life of approximately 15 min. Dex had maximal effect at concentrations above 0.01 microM and was effective on both rat and human MCP-1 transcripts. By deletion analysis, the Dex-sensitive region of the MCP-1 mRNA was localized to the initial 224 nucleotides (nt) at the 5' end and did not involve an AU-rich sequence in the 3' untranslated end. The 224-nt region conferred Dex sensitivity to heterologous mRNA. These studies provide new insights into the molecular mechanisms underlying the effect of glucocorticoids on gene expression.