anti-CCL2 Antibody Research Articles

Tobacco Smoke Exposure Disrupts CCL20 Production and Antimicrobial Activity by Respiratory Epithelial Cells. (B173)

Abstract The mechanism whereby tobacco smoke (TS) exposure increases the risk of infection is unknown. We tested the hypothesis that exposure to TS suppresses production of respiratory tract CCL20, a defensin-like antimicrobial peptide characterized primarily as a chemokine. When nasal washes from human subjects exposed to TS within the last two years were compared to nasal washes from individuals not exposed for more than 20 years, the latter had approximately six times more CCL20 than the former. In studies of polarized human bronchial epithelial cells (Beas-2b) grown in antibiotic-free media, CCL20 was released preferentially to the apical surface of the cell cultures. When cells were treated with tobacco smoke extract (TSE), CCL20 mRNA and secreted protein levels decreased by approximately half. In bacterial survival assays conducted with apically-collected conditioned media, media collected from TSE-treated cells killed significantly fewer CFU than media from non-TSE-treated cells; assays conducted with media treated with anti-CCL20 antibody resulted in abolition of its bacteriocidal activity. Statistically similar results were obtained in assays using rhCCL20 instead of apical media. These results demonstrate that TS exposure disrupts important antimicrobial activity and signaling by respiratory epithelial cells, a condition which may lead to increased susceptibility to infection.

Chemokine Complexity

William of Ockham (of Ockham's Razor fame) and Albert Einstein both urged us to keep it simple, but biology, perhaps in comparison to philosophy or physics, is often a more complicated matrix. An example of the complex nature of nature is the case of chemokine action in mediating inflammatory disease. Thus, chemokines were associated initially with the development of inflammatory and allergic disease primarily through their role as chemoattractant cytokines. In turn, increased lung levels of the chemokine CCL5 in patients with asthma and in mouse models of asthma (1, 2) were presumed to cause further recruitment of inflammatory cells, especially eosinophils, into airway tissue and consequent worsening of airway disease. However, this view of CCL5, and chemokines in general, turns out to be quite naive, as underscored by an additional article in the current issue of the AJRCMB (3). In this new article, Koya and colleagues (pp 147–154) show that CCL5 selectively dampens the long-term effect of allergen challenge in mice (3). In this model, prolonged allergen exposure (out to 48 d after initial sensitization) led to airway hyperreactivity and mucous cell metaplasia, and administration of CCL5 decreased these traits, whereas treatment with anti-CCL5 antibody significantly increased them. Administration of CCL5 also caused an increase while anti-CCL5 antibody caused a decrease in BAL fluid levels of IFN-γ as well as IFN-γ-producing CD4 T cells. Moreover, anti–IFN-γ antibody treatment caused an increase in airway hyperreactivity. Together, the results suggest that CCL5 somehow stimulates the generation of IFN-γ–producing Th1 cells that protect against a prolonged allergic response. Whether concomitant changes in lung IL-12 levels are linked to this mechanism remains uncertain. Similarly, why this action takes place after longer- but not shorter-term allergen exposure still needs to be defined, but presumably relies on the delayed development of an activated Th1 cell population.

CCL2 as a trigger of manifestations of compensatory anti-inflammatory response syndrome in mice with severe systemic inflammatory response syndrome

Patients with compensatory anti-inflammatory response syndrome (CARS) are at a higher risk for infection with various opportunistic pathogens. CARS develops commonly in association with the manifestation of systemic inflammatory response syndrome (SIRS). In the present study, the role of SIRS-associated soluble factors on the CARS development was examined in mice with pancreatitis, a carrier of typical SIRS. Following the production of SIRS-related cytokines [tumor necrosis factor alpha and interleukin (IL)-1beta], CC chemokine ligand 2 (CCL2), IL-4, and IL-10 (typical CARS cytokines) were detected in the sera of mice with pancreatitis. CCL2 has been described as an essential chemokine for the T helper cell type 2 manifestation. CARS effector cells (cells with an ability to produce IL-4 and IL-10) were not generated from normal T cells after stimulation with SIRS-related cytokines. However, these cells were generated from normal T cells after cultivation with peripheral blood neutrophils (PMN) from SIRS mice in a dual-chamber transwell. Normal T cells did not convert to CARS effector cells after transwell cultures with PMN from normal mice. CCL2 was detected in culture fluids of PMN from SIRS mice, and PMN from normal mice did not produce CCL2 into their culture fluids. CARS effector cells did not appear in PMN-depleted SIRS mice or SIRS mice treated with anti-CCL2 monoclonal antibody, and these cells were demonstrated in PMN-depleted SIRS mice after treatment with recombinant murine CCL2. These results indicate that CCL2 produced by PMN from SIRS mice is an active molecule on the SIRS-associated CARS manifestation.

Transactivation of CXCR4 by the Insulin-like Growth Factor-1 Receptor (IGF-1R) in Human MDA-MB-231 Breast Cancer Epithelial Cells

In the multimolecular environment in tissues and organs, cross-talk between growth factor and G protein-coupled receptors is likely to play an important role in both normal and pathological responses. In this report, we demonstrate transactivation of the chemokine receptor CXCR4 by the growth factor insulin-like growth factor (IGF)-1 is required for IGF-1-induced cell migration in metastatic MDA-MB-231 cells. The induction of chemotaxis in MDA-MB-231 cells by IGF-1 was inhibited by pretreatment of the cells with pertussis toxin (PTX) and by RNAi-mediated knockdown of CXCR4. Transactivation of the CXCR4 pathway by IGF-1 occurred independently of CXCL12, the chemokine ligand of CXCR4. Neither CXCR4 knockdown nor PTX had any effect on the ability of IGF-1 to activate IGF-1R, suggesting that CXCR4 and G proteins are activated subsequent to, or independently of, phosphorylation of IGF-1R by IGF-1. Coprecipitation studies revealed the presence of a constitutive complex containing IGF-1R, CXCR4, and the G protein subunits, G(i)alpha2 and Gbeta, and stimulation of MDA-MB-231 cells with IGF-1 led to the release of G(i)alpha2 and Gbeta from CXCR4. Based on our findings, we propose that CXCR4 constitutively forms a complex with IGF-1R in MDA-MB-231 cells, and that this interaction allows IGF-1 to activate migrational signaling pathways through CXCR4, G(i)alpha2 and Gbeta.

CCL2 and CCL5 mediate leukocyte adhesion in experimental autoimmune encephalomyelitis—an intravital microscopy study

Experimental autoimmune encephalomyelitis (EAE) models multiple sclerosis (MS) and is characterized by marked mononuclear cell influx in the brain. Several studies have demonstrated a role for chemokines during EAE. It remains to be determined whether these mediators modulate EAE primarily by mediating leukocyte influx into the CNS or by modifying lymphocyte activation and/or trafficking into lymphoid organs. After induction of EAE with MOG 35–55, leukocyte recruitment peaked on day 14 and correlated with symptom onset, TNF-α production and production of CCL2 and CCL5. Levels of CXCL-10 and CCL3 were not different from control animals. Using intravital microscopy, we demonstrated that leukocyte rolling and adhesion also peaked at day 14. Treatment with anti-CCL2 or anti-CCL5 antibodies just prior to the intravital microscopy prevented leukocyte adhesion, but not rolling. Our data suggest that induction of leukocyte adhesion to the brain microvasculature is an important mechanism by which CCL2 and CCL5 participate in the pathophysiology of EAE.

Natural killer T cells infiltrate neuroblastomas expressing the chemokine CCL2.

CD1d-restricted Vα24-Jα18–invariant natural killer T cells (iNKTs) are potentially important in tumor immunity. However, little is known about their localization to tumors. We analyzed 98 untreated primary neuroblastomas from patients with metastatic disease (stage 4) for tumor-infiltrating iNKTs using TaqMan® reverse transcription polymerase chain reaction and immunofluorescent microscopy. 52 tumors (53%) contained iNKTs, and oligonucleotide microarray analysis of the iNKT+ and iNKT− tumors revealed that the former expressed higher levels of CCL2/MCP-1, CXCL12/SDF-1, CCL5/RANTES, and CCL21/SLC. Eight tested neuroblastoma cell lines secreted a range of CCL2 (0–21.6 ng/ml), little CXCL12 (≤0.1 ng/ml), and no detectable CCL5 or CCL21. CCR2, the receptor for CCL2, was more frequently expressed by iNKT compared with natural killer and T cells from blood (P < 0.001). Supernatants of neuroblastoma cell lines that produced CCL2 induced in vitro migration of iNKTs from blood of patients and normal adults; this was abrogated by an anti-CCL2 monoclonal antibody. CCL2 expression by tumors was found to inversely correlate with MYCN proto-oncogene amplification and expression (r = 0.5, P < 0.001), and MYCN-high/CCL2-low expression accurately predicted the absence of iNKTs (P < 0.001). In summary, iNKTs migrate toward neuroblastoma cells in a CCL2-dependent manner, preferentially infiltrating MYCN nonamplified tumors that express CCL2.

CCL2, a product of mice early after systemic inflammatory response syndrome (SIRS), induces alternatively activated macrophages capable of impairing antibacterial resistance of SIRS mice.

Infection associated with systemic inflammatory response syndrome (SIRS) is a major cause of morbidity and mortality in patients with major surgery, polytrauma, and severe burn injury. In previous studies, mice with severe pancreatitis (a mouse model of SIRS, SIRS mice) have been shown to be greatly susceptible to various infections. In the present study, a mechanism involved in the impaired resistance of SIRS mice to infectious complications was investigated. Sera from SIRS mice impaired the resistance of normal mice to infectious complications induced by cecal ligation and puncture (CLP). CC chemokine ligand 2 (CCL2) was detected in sera of SIRS mice. Resident macrophages (RMphi) cultured with SIRS mouse sera converted to alternatively activated macrophages (AAMphi), which were also demonstrated in mice treated with recombinant murine CCL2. However, AAMphi were not demonstrated in mice injected with SIRS mouse sera and anti-CCL2 monoclonal antibody (mAb) in combination. Furthermore, normal mice that received SIRS mouse sera and anti-CCL2 mAb resisted CLP-induced infectious complications. These results indicate that the resistance of SIRS mice to infectious complications is impaired by AAMphi generated from RMphi in response to SIRS-associated CCL2 production.

Endogenous CCL2 (monocyte chemotactic protein-1) modulates human immunodeficiency virus type-1 replication and affects cytoskeleton organization in human monocyte–derived macrophages

AbstractCC chemokine ligand 2 (CCL2) is constitutively expressed at high levels in human peripheral blood monocytes, and its expression is further up-modulated during their differentiation into macrophages as well as in the course of HIV infection. To investigate the role of endogenous CCL2 on HIV replication and macrophage function, CCL2’s activity was neutralized by specific antibodies. Infection of monocyte-derived macrophages with laboratory-adapted HIV-1 or primary viral isolates in the continuous presence of anti-CCL2 antibody resulted in significantly lower p24 Gag antigen release with respect to control cultures. Interestingly, CCL2 neutralization did not affect the early steps of the HIV life cycle but resulted in the intracellular accumulation of p24 Gag antigen. Simultaneously, remarkable changes in cell morphology and size occurred in cell cultures maintained in the presence of anti-CCL2 antibody. These results suggest that CCL2 may represent an autocrine factor important for enhancing virion production likely by affecting the macrophage cytoskeleton. (Blood. 2003;102:2334-2337)

Astrocytes are the major intracerebral source of macrophage inflammatory protein-3alpha/CCL20 in relapsing experimental autoimmune encephalomyelitis and in vitro.

Macrophage inflammatory protein-3alpha/CCL20 is a recently identified chemokine that binds to CCR6 and acts as a chemoattractant for memory/differentiated T-cells, B-cells, and immature dendritic cells. We have previously reported that CCL20 and CCR6 mRNAs are expressed in the CNS of SJL mice with experimental autoimmune encephalomyelitis (EAE) and that CCL20 is produced by CNS-infiltrating leukocytes at disease onset and, additionally, by intraparenchymal astrocyte-like cells during disease relapses. In this study, we provide further immunohistochemical evidence that astrocytes represent the main CNS source of CCL20 during EAE. Moreover, we show that the proinflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha, but not interferon-gamma, induce expression of CCL20 mRNA and secretion of CCL20 protein in cultures of mouse brain-derived astrocytes. We also show that supernatants from cytokine-activated astrocytes stimulate the migration of polarized T helper cells and that this effect is partially inhibited by anti-CCL20 antibody. These findings suggest that, through secretion of CCL20, astrocytes could play an important role in orchestrating the recruitment of specific leukocyte subsets to the inflamed CNS and in regulating CNS-targeted immune responses.