Saliva from Lutzomyia longipalpis induces CC chemokine ligand 2/monocyte chemoattractant protein-1 expression and macrophage recruitment

Saliva of bloodfeeding arthropods has been incriminated in facilitating the establishment of parasite in their host. We report on the leukocyte chemoattractive effect of salivary gland homogenate (SGH) from Lutzomyia longipalpis on saliva-induced inflammation in an air pouch model. SGH (0.5 pair/animal) was inoculated in the air pouch formed in the back of BALB/c or C57BL/6 mice. L. longipalpis SGH induced a significant influx of macrophages in BALB/c but not in C57BL/6 mice. SGH-induced cell recruitment reached a peak at 12 h after inoculation and was higher than that induced by the LPS control. This differential cell recruitment in BALB/c mice was directly correlated to an increase in CCL2/MCP-1 expression in the air pouch lining tissue. In fact, treatment with bindarit, an inhibitor of CCL2/MCP-1 synthesis, and also with a specific anti-MCP-1 mAb resulted in drastic reduction of macrophage recruitment and inhibition of CCL2/MCP-1 expression in the lining tissue. CCL2/MCP-1 production was also seen in vitro when J774 murine macrophages were exposed to L. longipalpis SGH. The SGH effect was abrogated by preincubation with serum containing anti-SGH IgG Abs as well as in mice previously sensitized with L. longipalpis bites. Interestingly, the combination of SGH with Leishmania chagasi induced an increased recruitment of neutrophils and macrophages when compared with L. chagasi alone. Taken together these results suggest that SGH not only induces the recruitment of a greater number of macrophages by enhancing CCL2/MCP-1 production but also synergizes with L. chagasi to recruit more inflammatory cells to the site of inoculation.     

Expression of monocyte chemoattractant protein-1 and CC chemokine receptor 2 in non-small cell lung cancer and its significance

Expression of monocyte chemoattractant protein-1 (MCP-1) and CC chemokine receptor 2 (CCR2) and its significance has been demonstrated in some cancer cells in recent clinical studies. However, the role of tumor MCP-1 and CCR2 expression in non-small cell lung cancer (NSCLC) remains unknown. The aim of the present study was to investigate the prognostic significance of MCP-1 and CCR2 expression in NSCLC cells. The relationship between MCP-1 and CCR2 expression in NSCLC cancer cells was examined by immunohistochemical staining of surgical specimens from 134 patients. Sixty-five of these patients had follow-up records. Kaplan–Meier analysis and Cox regression model were used to assess overall survival according to the presence or absence of MCP-1 and CCR2 expression in tumor cells. MCP-1 was detected in cancer cells of 107 NSCLC (79.9 %) and CCR2 was detected in cancer cells of 39 NSCLC (29.1 %). MCP-1 expression was correlated with sex, smoking habits, histology, and tumor size. Presence of MCP-1 in tumor cells was associated with better overall survival (P = 0.018). By multivariate analysis, MCP-1 expression in cancer cells showed an independent prognostic factor for overall survival (P = 0.002, hazard ratio [HR] = 0.256, 95 % confidence interval [CI] = 0.106–0.616). There was no significant relationship between CCR2 expression in tumor cells and clinical and pathological characteristics. Also, no significant positive correlation between MCP-1 and CCR2 expression was revealed by Spearman correlation analysis. Our data indicate that MCP-1 is overexpressed in NSCLC cells. Its expression in cancer cells is associated with better survival in NSCLC patients.     

Design and receptor interactions of obligate dimeric mutant of chemokine monocyte chemoattractant protein-1 (MCP-1)

Chemokine-receptor interactions regulate leukocyte trafficking during inflammation. CC chemokines exist in equilibrium between monomeric and dimeric forms. Although the monomers can activate chemokine receptors, dimerization is required for leukocyte recruitment in vivo, and it remains controversial whether dimeric CC chemokines can bind and activate their receptors. We have developed an obligate dimeric mutant of the chemokine monocyte chemoattractant protein-1 (MCP-1) by substituting Thr(10) at the dimer interface with Cys. Biophysical analysis showed that MCP-1(T10C) forms a covalent dimer with similar structure to the wild type MCP-1 dimer. Initial cell-based assays indicated that MCP-1(T10C) could activate chemokine receptor CCR2 with potency reduced 1 to 2 orders of magnitude relative to wild type MCP-1. However, analysis of size exclusion chromatography fractions demonstrated that the observed activity was due to a small proportion of MCP-1(T10C) being monomeric and highly potent, whereas the majority dimeric form could neither bind nor activate CCR2 at concentrations up to 1 μM. These observations help to reconcile previous conflicting results and indicate that dimeric CC chemokines do not bind to their receptors with affinities approaching those of the corresponding monomeric chemokines.     

Differential roles of CC chemokine ligand 2/monocyte chemotactic protein-1 and CCR2 in the development of T1 immunity

CCR2 and its major ligand, chemokine ligand 2 (CCL2)/monocyte chemotactic protein-1, have been found to influence T1/T2 immune response polarization. Our objective was to directly compare the roles of CCR2 and CCL2 in T1/T2 immune response polarization using a model of pulmonary Cryptococcus neoformans infection. Either deletion of CCR2 or treatment of wild-type mice with CCL2 neutralizing Ab produced significant and comparable reductions in macrophage and T cell recruitment into the lungs following infection. Both CCL2 neutralization and CCR2 deficiency resulted in significantly diminished IFN-gamma production, and increased IL-4 and IL-5 production by lung leukocytes (T1 to T2 switch), but only CCR2 deficiency promoted pulmonary eotaxin production and eosinophilia. In the lung-associated lymph nodes (LALN), CCL2-neutralized mice developed Ag-specific IFN-gamma-producing cells, while CCR2 knockout mice did not. LALN from CCR2 knockout mice also had fewer MHCII(+)CD11c(+) and MHCII(+)CD11b(+) cells, and produced significantly less IL-12p70 and TNF-alpha when stimulated with heat-killed yeast than LALN from wild-type or CCL2-neutralized mice, consistent with a defect in APC trafficking in CCR2 knockout mice. Neutralization of CCL2 in CCR2 knockout mice did not alter immune response development, demonstrating that the high levels of CCL2 in these mice did not play a role in T2 polarization. Therefore, CCR2 (but not CCL2) is required for afferent T1 development in the lymph nodes. In the absence of CCL2, T1 cells polarize in the LALN, but do not traffic from the lymph nodes to the lungs, resulting in a pulmonary T2 response.     

Differential monocyte chemoattractant protein-1 and chemokine receptor 2 expression by murine lung fibroblasts derived from Th1- and Th2-type pulmonary granuloma models.

Recent studies suggest that monocyte chemoattractant protein-1 (MCP-1) is involved in fibrosis through the regulation of profibrotic cytokine generation and matrix deposition. Changes in MCP-1, C-C chemokine receptor 2 (CCR2), procollagen I and III, and TGF beta were examined in fibroblasts cultured from normal lung and from nonfibrotic (i.e., Th1-type) and fibrotic (i.e., Th2-type) pulmonary granulomas. Th2-type fibroblasts generated 2-fold more MCP-1 than similar numbers of Th1-type or normal fibroblasts after 24 h in culture. Unlike normal and Th1-type fibroblasts, Th2-type fibroblasts displayed CCR2 mRNA at 24 h after IL-4 treatment. By flow cytometry, CCR2 was present on 40% of untreated Th2-type fibroblasts, whereas CCR2 was present on <20% of normal and Th1-type fibroblasts after similar treatment. IL-4 increased the number of normal fibroblasts with cell-surface CCR2 but IFN-gamma-treatment of normal and Th2-type fibroblasts significantly decreased the numbers of CCR2-positive cells in both populations. Western blot analysis showed that total CCR2 protein expression was markedly increased in untreated Th2-type fibroblasts compared with normal and Th1-type fibroblasts. IL-4 treatment enhanced CCR2 protein in Th1- and Th2-type fibroblasts whereas IFN-gamma treatment augmented CCR2 protein in normal and Th1-type fibroblasts. All three fibroblast populations exhibited MCP-1-dependent TGF-beta synthesis, but only normal and Th2-type fibroblasts showed a MCP-1 requirement for procollagen mRNA expression. Taken together, these findings suggest that lung fibroblasts are altered in their expression of MCP-1, TGF-beta, CCR2, and procollagen following their participation in pulmonary inflammatory processes, and these changes may be important during fibrosis.     

Differential expression of the isoforms for the monocyte chemoattractant protein-1 receptor, CCR2, in monocytes.

Two isoforms of human CCR2, the receptor for monocyte chemoattractant protein-1 (MCP-1), have been identified but their relative expression in monocytes and contribution to inflammatory responses mediated by MCP-1 remain uncertain. All available information on CCR2 expression is based on mRNA data because isoform-specific antibodies were not available until now. To analyze the relative expression of each isoform, we made two antibodies that specifically recognized CCR2A and CCR2B. Examination of receptor protein with these isoform-specific antibodies showed that the total expression of CCR2B in monocytes was about 10-fold higher than that of CCR2A with an equal distribution between the cell surface and intracellular pools. A detailed analysis using purified plasma membranes demonstrated that about 90% of all CCR2 on the cell surface were composed of CCR2B. The relatively abundant expression of CCR2B on the cell surface suggests a principal role of this isoform as a mediator of monocyte responses to MCP-1 in inflammation.     

Role of the monocyte chemoattractant protein-1/C-C chemokine receptor 2 signaling pathway in transient receptor potential vanilloid type 1 ablation-induced renal injury in salt-sensitive hypertension

Our recent studies indicate that the transient receptor potential vanilloid type 1 (TRPV1) channel may act as a potential regulator of monocyte/macrophage recruitment to reduce renal injury in salt-sensitive hypertension. This study tests the hypothesis that deletion of TRPV1 exaggerates salt-sensitive hypertension-induced renal injury due to enhanced inflammatory responses via monocyte chemoattractant protein-1 (MCP-1)/C-C chemokine receptor 2 (CCR2)-dependent pathways. Wild type (WT) and TRPV1-null mutant (TRPV1^−/−) mice were subjected to uninephrectomy and deoxycorticosterone acetate (DOCA)-salt treatment for four weeks with or without the selective CCR2 antagonist, RS504393. DOCA-salt treatment increased systolic blood pressure (SBP) to the same degree in both strains, but increased urinary excretion of albumin and 8-isoprostane and decreased creatinine clearance with greater magnitude in TRPV1^−/− mice compared to WT mice. DOCA-salt treatment also caused renal glomerulosclerosis, tubulointerstitial injury, collagen deposition, monocyte/macrophage infiltration, proinflammatory cytokine and chemokine production, and NF-κB activation in greater degree in TRPV1^−/− mice compared to WT mice. Blockade of the CCR2 with RS504393 (4 mg/kg/day) had no effect on SBP in DOCA-salt-treated WT or TRPV1^−/− mice compared to their respective controls. However, treatment with RS504393 ameliorated renal dysfunction and morphological damage, and prevented the increase in monocyte/macrophage infiltration, cytokine/chemokine production, and NF-κB activity in both DOCA-salt hypertensive strains with a greater effect in DOCA-salt-treated TRPV1^−/− mice compared to DOCA-salt-treated WT mice. No differences in CCR2 protein expression in kidney were found between DOCA-salt-treated WT and TRPV1^−/− mice with or without RS504393 treatment. Our studies for the first time indicate that deletion of TRPV1 aggravated renal injury in salt-sensitive hypertension via enhancing MCP-1/CCR2 signaling-dependent inflammatory responses.     

A non-glycosaminoglycan-binding variant of CC chemokine ligand 7 (monocyte chemoattractant protein-3) antagonizes chemokine-mediated inflammation

A non-glycosaminoglycan (GAG)-binding variant of the pleiotropic chemokine CCL7 was generated by mutating to alanine the basic (B) amino acids within an identified (44)BXBXXB(49) GAG-binding motif. Unlike wild-type (wt) CCL7, the mutant sequence had no affinity for heparin. However, the mutant retained a normal affinity for CCR1, CCR2b, and CCR3, and produced a normal calcium flux in mononuclear leukocytes. Both the wt and mutant proteins elicited an equal leukocyte chemotactic response within a solute diffusion gradient but, unlike the wt protein, the mutant failed to stimulate cell migration across a model endothelium. The number of leukocytes recruited to murine air pouches by the mutant sequence was lower than that recruited by wt CCL7. Furthermore, the presence of a mixture of a mutant and wt CCL7 within the air pouch elicited no significant cell accumulation. Cell recruitment also failed using a receptor-sharing mixture of mutant CCL7 and wt CCL5 or a nonreceptor sharing mixture of mutant CCL7 and wt CXCL12. The potential of the mutant sequence to modulate inflammation was confirmed by demonstration of its ability to inhibit the chemotactic response generated in vitro by synovial fluid from patients with active rheumatoid arthritis. A further series of experiments suggested that the non-GAG-binding mutant protein could potentially induce receptor desensitization before, and at a site remote from, any physiological recognition of GAG-bound chemokines. These data demonstrate that GAG binding is required for chemokine-driven inflammation in vivo and also suggest that a non-GAG-binding chemokine receptor agonist can inhibit the normal vectorial leukocyte migration mediated by chemokines.     

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

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

Induction of low dose oral tolerance in monocyte chemoattractant protein-1- and CCR2-deficient mice

The chemokine monocyte chemoattractant protein-1 (MCP-1) and its receptor CCR2 have been shown to play an important role in the migration and trafficking of macrophages and Th1 effector cells in experimental autoimmune encephalomyelitis. Also, MCP-1 has been reported to regulate oral tolerance induction by inhibition of Th1 cell-related cytokines and by the ability of Abs to MCP-1 to inhibit oral tolerance. This study demonstrates that neither MCP-1 nor its receptor CCR2 is required for the induction of oral tolerance. Mice deletional for either MCP-1 or CCR2 had suppressed cell-proliferative and Th1 responses following oral administration and immunization with myelin oligodendrocyte glycoprotein (MOG(35-55)). TGF-beta was up-regulated in fed and immunized deletional mice, while IL-4 was absent from deletional mice, but up-regulated in controls. Decreased experimental autoimmune encephalomyelitis severity was found in MOG(35-55)-fed MCP-1 deletional mice, indicating induction of oral tolerance. These results demonstrate that MCP-1 is not required for induction of oral tolerance and that MCP-1 and CCR2 are essential for up-regulation of IL-4 in tolerized mice.     

单核细胞趋化蛋白-1在糖尿病肾病中的作用

糖尿病肾病是多因素引起的复杂性疾病,近年研究发现炎症反应参与了该病的发生与发展.单核细胞趋化蛋白-1是趋化因子CC亚家族的一员,在募集巨噬细胞等炎性细胞参与炎症反应中扮演着重要的角色.其趋化单核巨噬细胞于糖尿病肾组织中,可介导溶酶体释放,产生氧自由基,促进单核巨噬细胞表达β1-转化生长因子(transforming growth factor β1,TGF-β1),而广泛浸润臣噬细胞加剧了肾小球基底膜增厚、细胞外基质堆积,进而发展为肾小球硬化和间质纤维化.深入研究单核细胞趋化蛋白-1在糖尿病肾病中的作用,可望为糖尿病肾病的预防和治疗提供新的思路和途径.     

HIV-infected patients with lipodystrophy have higher rates of carotid atherosclerosis: the role of monocyte chemoattractant protein-1

Individuals with HIV-1 infection are at increased risk for cardiovascular events, and lipodystrophy is generally associated with pro-atherogenic metabolic disturbances. We conducted a case-control study to assess the presence of sub-clinical atherosclerosis in HIV-1-infected patients with or without lipodystrophy (LD) and to evaluate the influence of monocyte chemoattractant protein-1 (MCP-1) on the development of both carotid atherosclerosis and LD. The study population consisted of 43 patients with LD and 86 patients without LD. We determined carotid intima-media thickness (IMT), MCP-1 concentrations in plasma, and MCP-1 genotype (presence or absence of the -2518G allele). HIV-1-infected patients with LD showed increased risk (OR=3.71, 95% CI=1.10-12.47, p=0.03) for sub-clinical atherosclerosis, and MCP-1 plasma concentration was significantly correlated with IMT in these patients (Pearson=0.31, p=0.03). Furthermore, presence of LD was a determinant for MCP-1 plasma concentration (beta=0.18, p=0.05). In summary, HIV-1-infected patients with clinically manifest LD are at higher risk for atherosclerosis and our observations support the relationship between inflammation and atherosclerotic disease.     

Role of MAPKs in development and differentiation: lessons from knockout mice

The ERK, p38MAPK, JNK mitogen-activated protein kinases (MAPKs) are intracellular signaling pathways that play a pivotal role in many essential cellular processes such as proliferation and differentiation. These cascades are activated by a large variety of stimuli and display a high degree of homology. So far, seven MAPK isoforms have been invalidated in mice leading to the discovery of their important functions in development and differentiation. As we could expect because of their multiple and specific properties in vitro, knockout (KO) of MAPK pathways leads to distinct phenotypes in mice. Surprisingly, into a given cascade, KOs of the various isoforms assign specific non-redundant biological functions to each isoform, without compensation by the others. These results emphasize the notion that, although initiated by the same external stimuli, these intracellular cascades activate kinase isoforms each with its own specific role.     

Monocyte chemoattractant protein-1/CC chemokine ligand 2 enhances apoptotic cell removal by macrophages through Rac1 activation

Apoptotic cell removal (efferocytosis) is an essential process in the regulation of inflammation and tissue repair. We have shown that monocyte chemoattractant protein-1/CC chemokine ligand 2 (MCP-1/CCL2) enhances efferocytosis by alveolar macrophages in murine bacterial pneumonia. However, the mechanism by which MCP-1 exerts this effect remains to be determined. Here we explored that hypothesis that MCP-1 enhances efferocytosis through a Rac1/phosphatidylinositol 3-kinase (PI3-kinase)-dependent mechanism.We assessed phagocytosis of apoptotic cells by MCP-1 treated murine macrophages in vitro and in vivo. Rac activity in macrophages was measured using a Rac pull down assay and an ELISA based assay (GLISA). The downstream Rac1 activation pathway was studied using a specific Rac1 inhibitor and PI3-kinase inhibitor in in vitro assays.MCP-1 enhanced efferocytosis of apoptotic cells by murine alveolar macrophages (AMs), peritoneal macrophages (PMs), the J774 macrophage cell line (J774s) in vitro, and murine AMs in vivo. Rac1 activation was demonstrated in these cell lines. The effect of MCP-1 on efferocytosis was completely negated by the Rac1 inhibitor and PI3-kinase inhibitor.We demonstrated that MCP-1 enhances efferocytosis in a Rac1-PI3 kinase-dependent manner. Therefore, MCP-1-Rac1-PI3K interaction plays a critical role in resolution of acute lung inflammation.     

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

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

Increased expression levels of monocyte CCR2 and monocyte chemoattractant protein-1 in patients with diabetes mellitus

Increased monocyte recruitment into subendothelial space in atherosclerotic lesions is one of the hallmarks of diabetic angiopathy. The aim of this study was to determine the state of peripheral blood monocytes in diabetes associated with atherosclerosis. Diabetic patients treated with/without an oral hypoglycemic agent and/or insulin for at least 1 year were recruited (n=106). We also included 24 non-diabetic control subjects. We measured serum levels of monocyte chemoattractant protein (MCP)-1, fasting plasma glucose (FPG), HbA1c, total cholesterol, triglyceride, body mass index (BMI), high sensitivity CRP (hs-CRP) and evaluated CCR2, CD36, CD68 expression on the surface of monocytes. Serum MCP-1 levels were significantly (p<0.05) higher in diabetic patients than in normal subjects. In diabetic patients, serum MCP-1 levels correlated significantly with FPG, HbA1c, triglyceride, BMI, and hs-CRP. The expression levels of CCR2, CD36, and CD68 on monocytes were significantly increased in diabetic patients and were more upregulated by MCP-1 stimulation. Our data suggest that elevated serum MCP-1 levels and increased monocyte CCR2, CD36, CD68 expression correlate with poor blood glucose control and potentially contribute to increased recruitment of monocytes to the vessel wall in diabetes mellitus.     

Monocyte chemoattractant protein-1 induces scavenger receptor expression and monocyte differentiation into foam cells

Accumulation of monocytes and the entrapment of oxidized-low-density lipoprotein (ox-LDL) in monocytes are important in the differentiation into "foam" macrophages and the pathogenesis of atherosclerosis. We investigated the role of monocyte chemoattractant protein-1 (MCP-1) in the expression of scavenger receptor (SCR) by using resting monocytes prepared by counterflow centrifugal elutriation. Our results showed that: (1) MCP-1 increased the expression of CD36 SCR by flow cytometric analysis. (2) MCP-1 increased incorporation of 125I-labeled ox-LDL and oil red O staining. (3) MCP-1 and ox-LDL enhanced in vitro transendothelial monocyte migration. (4) These functions were mediated at least in part via extracellular signal-regulated kinase (ERK) pathway. (5) MCP-1 and ox-LDL did not induce monocyte proliferation. Our results imply that MCP-1 is involved in the inflammatory process of atherosclerosis through the induction of SCR expression via the ERK pathway and differentiation of monocytes into foam macrophages, as well as induction of monocyte migration.     

Adenoviral-mediated overexpression of monocyte chemoattractant protein-1 differentially alters the development of Th1 and Th2 type responses in vivo

The expression of chemokines during an immune response may participate in determining the intensity and type of the developing immune response. In the present study, we have examined the effect of overexpressing monocyte chemoattractant protein (MCP)-1 at the site of immunization during different stages of Th1- and Th2-type granulomatous responses. The overexpression of MCP-1 by MCP-1 adenovirus during the sensitization phase of the purified protein derivative Th1-type model significantly reduced the elicitation of the granulomatous response. In contrast, the overexpression of MCP-1 during the sensitization phase of the schistosome egg Ag Th2 response led to an enhanced granulomatous reaction. When cytokines were examined upon restimulation of splenocytes ex vivo, an altered cytokine profile was observed, as compared with control mice. IFN-gamma and IL-12 were significantly reduced in the purified protein derivative Th1-type response, whereas IL-10 and IL-13 were up-regulated in the schistosome egg Ag Th2-type response. The regulation of the immune response was further examined by using the MCP-1 adenovirus at later time points during the elicitation phase. When MCP-1 was overexpressed during the elicitation phase of the responses, neither the Th1-type nor the Th2-type granuloma was altered. Likewise, the cytokine profiles after restimulation of splenocytes ex vivo were unchanged. Thus, the function of MCP-1 may depend on the stage and type of immune response.