Human endothelial cells express CCR2 and respond to MCP-1: direct role of MCP-1 in angiogenesis and tumor progression

Tissue and Serum Angiogenic Activity Is Associated With Low Prevalence of Ischemic Complications in Patients With Giant-Cell Arteritis

Background— Vascular inflammatory lesions from patients with giant-cell arteritis show a remarkable amount of neovascularization, but its clinical implications have never been investigated.

Methods and Results— To assess the clinical relevance of neovascularization in giant-cell arteritis, angiogenesis was measured in temporal artery sections from 31 patients with biopsy-proven giant-cell arteritis by staining endothelial cells with Ulex europaeus lectin. Angiogenesis was highly variable among these patients. Patients without ischemic complications had higher tissue angiogenesis scores than patients with ischemic events (5.69±0.6 versus 2.91±0.6, P =0.003). Angiogenesis was also more prominent in patients with a strong acute phase response (score: 5.31±0.6) compared with those with a weak systemic inflammatory reaction (2.30±0.44; P =0.0007). Serum angiogenic activity was studied in an additional series of 38 biopsy-proven patients. Sera from patients without ischemic events tended to be more active in stimulating human umbilical vein endothelial cell growth (optical density ×1000, 270±15 versus 192±14, P =0.065) and differentiation into capillary-like structures (107±5 versus 84±8 relative units, P =0.0058) than patients with ischemic complications. Sera from patients without ischemic events had more in vivo full angiogenic activity tested in the chick chorioallantoic membrane than sera from patients with ischemic complications.

Conclusion— Inflammation-induced angiogenic activity may play a compensatory role for ischemia in patients with giant-cell arteritis.

The use of (99m)technetium-labeled MCP-1 to assess graft coronary artery disease in rat cardiac allografts

BACKGROUND

Monocyte chemoattractant protein-1 (MCP-1) is associated with the development of graft coronary artery disease (GCAD) following cardiac transplantation. This study assessed whether technetium 99m ((99m)Tc)-labeled MCP-1 binds its receptors in chronic cardiac transplants and thereby provides a potential modality to assess GCAD.

METHODS

Allogeneic (PVG-->ACI, n = 9) and syngeneic (ACI-->ACI, n = 9) rat heterotopic heart transplants were performed. Allograft recipients were treated with 7.5 mg/kg per day of Cyclosporin A for 10 days until tolerance was achieved. After 90 days, animals were injected intravenously with (99m)Tc-MCP-1 and killed after 1 hour. Radioactivity of heart tissues was measured and standardized to uptake in the overall blood pool. Two-dimensional (99m)Tc-MCP-1 uptake (autoradiographs) was imaged by exposing 50-microm sections on a phosphoimager overnight. ED-1 staining of monocyte/macrophages was performed on serial sections. Additional sections were stained with elastin von Gieson and hematoxylin. Hearts were scored for luminal narrowing and intima/media ratio (I/M) with computerized image analysis.

RESULTS

Allografts exhibited significantly more luminal narrowing (22.5 +/- 10.7% vs 2.6 +/- 4.6, p = 0.0005) and higher I/M (0.173 +/- 0.151 vs 0.015 +/- 0.029, p = 0.0088) than isografts. The ratio of (99m)Tc-MCP-1 uptake in allografts (1.04 +/- 0.4) was greater than that of isograft controls (0.72 +/- 0.11, p = 0.03). Pixel counts of autoradiographs and ED-1-stained sections demonstrated a modest correlation between the two (R(2) = 0.50). No significant differences were seen in acute rejection scores.

CONCLUSION

(99m)Tc-MCP-1 uptake was higher in allografts vs isografts and was consistent with a greater degree of GCAD. These data demonstrating increased radiopharmaceutical uptake in hearts with GCAD provide a foundation for the development of a potentially non-invasive imaging assay of this disease process in heart transplantation.

Characterization of chemokines and their receptors in the central nervous system: physiopathological implications

Chemokines represent key factors in the outburst of the immune response, by activating and directing the leukocyte traffic, both in lymphopoiesis and in immune surveillance. Neurobiologists took little interest in chemokines for many years, until their link to acquired immune deficiency syndrome-associated dementia became established, and thus their importance in this field has been neglected. Nevertheless, the body of data on their expression and role in the CNS has grown in the past few years, along with a new vision of brain as an immunologically competent and active organ. A large number of chemokines and chemokine receptors are expressed in neurons, astrocytes, microglia and oligodendrocytes, either constitutively or induced by inflammatory mediators. They are involved in many neuropathological processes in which an inflammatory state persists, as well as in brain tumor progression and metastasis. Moreover, there is evidence for a crucial role of CNS chemokines under physiological conditions, similar to well known functions in the immune system, such as proliferation and developmental patterning, but also peculiar to the CNS, such as regulation of neural transmission, plasticity and survival.

Angiogenesis and chemokines in rheumatoid arthritis and other systemic inflammatory rheumatic diseases

Angiogenesis, the formation of new vessels, is important in the pathogenesis of rheumatoid arthritis (RA) and other inflammatory diseases. Chemotactic cytokines termed chemokines mediate the ingress of leukocytes, including neutrophils and monocytes into the inflamed synovium. In this review, authors discuss the role of the most important angiogenic factors and angiogenesis inhibitors, as well as relevant chemokines and chemokine receptors involved in chronic inflammatory rheumatic diseases. RA was chosen as a prototype to discuss these issues, as the majority of studies on the role of angiogenesis and chemokines in inflammatory diseases were carried out in arthritis. However, other systemic inflammatory (autoimmune) diseases including systemic lupus erythematosus (SLE), systemic sclerosis (SSc), Sjögren's syndrome (SS), mixed connective tissue disease (MCTD), polymyositis/dermatomyositis (PM/DM) and systemic vasculites are also discussed in this context. As a number of chemokines may also play a role in neovascularization, this issue is also described here. Apart from discussing the pathogenic role of angiogenesis and chemokines, authors also review the regulation of angiogenesis and chemokine production by other inflammatory mediators, as well as the important relevance of neovascularization and chemokines for antirheumatic intervention.

Possible co-regulation of genes associated with enhanced progression of mammary adenocarcinomas

Tumor progression is a multistep process in which alterations in the expression of numerous gene products may give rise to highly malignant cellular variants. In the present study, we analyzed the differential expression of several genes in cellular variants of mammary adenocarcinomas with high or low malignancy potential, which originated in a common ancestor. To assess the generality of our findings, high and low malignancy variants were derived from two different mammary adenocarcinoma cell lines, namely DA3 and CSML cells. Of major importance is the fact that the differences between high- and low-malignancy variants observed in one system of mammary adenocarcinoma cells (DA3 cells) were identically reproduced in the other system of mammary adenocarcinoma cells (CSML cells). The high malignancy variants of tumors both DA3-high and CSML-high (previously called CSML-100), expressed higher levels of factors that induce monocyte migration than the low malignancy DA3-low and CSML-low (previously called CSML-0) variants. In addition, it was found that DA3-high and CSML-high cell variants expressed higher levels of monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6) and matrix metalloproteinases (MMPs) than the low malignancy variants (DA3-low and CSML-low). These results suggest that MCP-1, IL-6 and MMPs potentially contribute to mammary adenocarcinoma progression and that their expression is regulated by a common pathway. The expression of MCP-1, IL-6 and MMPs in both DA3-high and CSML-high cells was up-regulated by tumor necrosis factor alpha (TNFalpha). The fact that TNFalpha exerted similar effects on the expression of these three factors in both cell systems raises the possibility of a coordinated co-regulation of tumor-promoting factors.

Chemokines and chemokine receptors in the pathogenesis of systemic sclerosis

Abstract  Activation of the immune system and increased synthesis of extracellular matrix proteins by fibroblasts are hallmarks in the pathogenesis of systemic sclerosis (SSc). The mechanisms that initiate the accumulation of inflammatory cells are still unknown. Chemokines are a family of small molecules that are divided into subfamilies according to the position of NH2-terminal cysteine motif. A new nomenclature for chemokines recently has been introduced in an attempt to overcome the confusion resulting from a number of different names for the same chemokines. Recent data indicate that chemokines, and in particular MCP-1 (CCL2), might be involved in the pathogenesis of SSc at different levels. MCP-1 is highly upregulated in skin specimens from SSc patients compared with those from healthy controls. Dermal fibroblasts release MCP-1, which is able to induce and perpetuate the migration of inflammatory cells into the skin. Interestingly, data from animal models, as well as from in vitro studies, indicate that MCP-1 might also be involved in the increased synthesis of extracellular matrix proteins, by either direct or indirect mechanisms. In conclusion, chemokines represent interesting candidates for target-directed therapies for SSc. This concept has to be confirmed by further studies using animal models for SSc and other fibrotic diseases.

Cytokines and therapy in COPD: a promising combination?

COPD is a major health problem, with patients showing a progressively declining, largely irreversible, change in lung function. This is associated with chronic airways inflammation and structural remodeling, including loss of alveolar walls, and goblet cell metaplasia with mucus hypersecretion. Inflammatory cells may contribute to the airway remodeling via secretion of proteases, fibrotic or mitogenic growth factors, and cytokines. In turn, airway remodeling may contribute to the clinical symptoms of COPD. Currently available therapies are directed to improvement of clinical symptoms and reduction of the airways inflammation. The commonly used glucocorticosteroids are expected to reduce the inflammation by acting on kinases or transcription factors necessary for expression of pro-inflammatory cytokines or chemokines. However, several long-term and short-term studies showed that glucocorticosteroids are rather ineffective in improving lung function and reducing the airway inflammation in patients with COPD. New therapeutic strategies may reduce the inflammation and alleviate the clinical symptoms of COPD. Tumor necrosis factor-alpha, interleukin-8, and monocyte chemoattractant protein-1 are important chemotactic proteins for macrophages and neutrophils, the predominant inflammatory cells associated with COPD. As lung levels of these cytokines are higher in COPD compared to non-COPD patients, they may represent targets for novel therapies.

Role of monocytes and macrophages in adult angiogenesis: a light at the tunnel's end

In spite of sustained efforts, there are still gaps in our understanding of angiogenesis as it takes place in vivo. Older observations and a number of recent developments strongly involve the blood mononuclear cell population, collectively known as monocytes (MC), in the normal and pathological adult angiogenesis. An emerging paradigm should eventually incorporate the established biochemical cross talk between MC and their descendents, tissular macrophages (Mph), and the endothelial cells (EC); additionally, it should account for both the intercellular cooperation at the morphological level and the phenotypic overlap between the two cell populations. This focused review puts together the pieces of this puzzle in such a way as to suggest an alternative angiogenic model applicable to adult animals, and particularly to pathological conditions. A working hypothesis is put forward, which is centered on the preformation of capillary lumen as a "tunnel" drilled by penetrating MC/Mph. The tunnels may be colonized in a later stage by sprouts, circulating progenitor endothelial cells (CPEC) or transdifferentiated EC. Thus, MC/Mph are suggested to be included among the targets of therapeutic manipulation of angiogenesis.

Graves' disease is associated with an altered CXCR3 and CCR5 expression in thyroid-derived compared to peripheral blood lymphocytes

The mechanisms by which T cells accumulate in the thyroid and support the autoimmune process in patients with Graves' disease (GD) are poorly understood. Chemokines and their receptors may be involved in this process. We have analysed the expression of CXCR3 and CCR5 as Th1-specific chemokine receptors, CCR3 as a marker for Th2 cells, CXCR4 (expressed on unprimed, naive T cells) and CCR2 (known to be involved in autoimmunity) on peripheral blood (PBL) and thyroid-derived lymphocytes (TL) using flow cytometry. Chemokine receptor expression on PBL of GD patients (n = 16) did not differ from that of normal controls (n = 10). In GD, CXCR3+ (67.3 +/- 4.0% versus 45.7 +/- 2.1%) and CCR5+ T cells (42.5 +/- 3.4% versus 18.8 +/- 2.1%) showed a significant enrichment in the TL compared to PBL. The positive cells were contributed mainly by the CD4+CD45R0+ subset. TL are mostly primed CD45R0+ T cells, but surprisingly, they had significantly higher levels of CXCR4+ cells among TL (96.2 +/- 1.0%) compared to PBL (66.8 +/- 4.2%). However, CXCR4 has been induced during in vitro isolation of TL. There was no correlation between chemokine receptors and the level of TSH-receptor and thyroid peroxidase autoantibodies. CCR3+ and CCR2+ cells remained unchanged in TL compared to PBL. We could confirm the results using RT PCR and immunohistology. In summary, TL showed a different chemokine receptor pattern compared to PBL from the same patient. This indicates a role for CXCR3 and CCR5 in the recruitment of T cells to the thyroid in GD.

Interleukin-13 gene therapy reduces inflammation, vascularization, and bony destruction in rat adjuvant-induced arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by synovial pannus formation, leukocyte infiltration, and angiogenesis. Adenoviral production of interleukin-13 (IL-13) reduces levels of proinflammatory mediators in an explant model of RA synovial tissue in vitro. To assess this approach in an animal model of arthritis, we compared intra-articular injections of an adenovirus producing rat IL-13 (AxCArIL-13), a control virus, and rat ankles receiving phosphate-buffered saline (PBS) in rat adjuvant-induced arthritis (AIA). We demonstrate that IL-13 levels are normally low in ankles throughout the course of rat AIA. We show that administration of AxCArIL-13 before arthritis onset significantly reduces ankle circumference, paw volume, bony destruction, the number of polymorphonuclear cells (PMNs), the quantity of blood vessels, and levels of monocyte chemoattractant protein (MCP)-1 in ankles. When administered as a treatment to inflamed ankles, AxCArIL-13 decreases articular index scores, paw volumes, bony destruction, vascularization, tumor necrosis factor-alpha (TNF-alpha) levels, and the quantity of monocytes, lymphocytes, and PMNs. Thus, increasing IL-13 levels significantly ameliorates the course of rat AIA, suggesting that similar strategies for the treatment of human RA are worthy of further study.

Expression of monocyte chemoattractant protein-1 and distribution of immune cell populations in the bovine corpus luteum throughout the estrous cycle

This study characterizes the expression of monocyte chemoattractant protein-1 (MCP-1) and the relative distribution of immune cell populations in the bovine corpus luteum throughout the estrous cycle. Immunodetectable MCP-1 was evident in corpora lutea of cows at Days 6, 12, and 18 postovulation (Day 0 = ovulation, n = 4 cows/stage). Day 6 corpora lutea contained minimal MCP-1 that was confined primarily to blood vessels. In contrast, relatively intense staining for MCP-1 was observed in corpora lutea from Days 12 and 18 postovulation. MCP-1 was again most evident in the cells of the vasculature, but it was also observed surrounding individual luteal cells, particularly by Day 18. An increase in immunohistochemical expression of MCP-1 on Days 12 and 18 postovulation corresponded with increases in MCP-1 mRNA and protein in corpora lutea as determined by Northern blot analysis and ELISA. Monocytes and macrophages were the most abundant immune cells detected in the bovine corpus luteum, followed by CD8+ and CD4+ T lymphocytes. In all instances, Day 6 corpora lutea contained fewer immune cells than corpora lutea from Days 12 and 18. In conclusion, increased expression of MCP-1 was accompanied by the accumulation of immune cells in the corpora lutea of cows during the latter half of the estrous cycle (Days 12-18 postovulation). These results support the hypothesis that MCP-1 promotes immune cell recruitment into the corpus luteum to facilitate luteal regression. These results also raise a provocative issue, however, concerning the recruitment of immune cells several days in advance of the onset of luteal regression.

Chemokine expression in myocardial ischemia: MIP-2 dependent MCP-1 expression protects cardiomyocytes from cell death

Chemokines are small molecular weight proteins that play important roles in inflammation. Originally described as chemotactic cytokines, chemokines stimulate the influx of leukocytes into specific tissue compartments. These molecules also modulate gene expression in both infiltrating and resident cells to mediate a vast array of cellular functions, and their importance in disease processes has been well documented. This study examined the expression of chemokines during myocardial ischemia and established a pathway by which two, MIP-2 and JE/MCP-1, modulate cardiac myocyte viability during this process. To focus on the direct effects of chemokines on these cells, a mouse model of ischemia without reperfusion was used. The expression of chemokines and chemokine receptors was induced in the left ventricular free wall as early as 1 h post-ischemia, with the most significant increases in MIP-2 (CXCL2) and JE/MCP-1 (CCL2). Expression of their respective receptors, CXCR2 and CCR2, was also induced. Similar changes in gene expression occurred at the mRNA and protein levels in isolated neonatal mouse cardiac myocytes stimulated by hypoxia. Antibody to MIP-2 inhibited hypoxia-induced JE/MCP-1 expression, demonstrating that MIP-2 is critical for this event. Moreover, in vivo intramyocardial injection of either an adenovirus expressing MIP-2 or the recombinant protein itself was sufficient to upregulate JE/MCP-1 production even in the absence of ischemia. Thus, MIP-2 regulates JE/MCP-1 expression both in cell culture and in vivo. Furthermore, JE/MCP-1 markedly decreased hypoxia-induced cell death in cultured cardiac myocytes. Thus, JE/MCP-1 appears to mediate an unanticipated survival pathway in target cardiac myocytes themselves. These findings indicate an important role for MIP-2 and JE/MCP-1 in regulating the response of cardiac myocytes to myocardial ischemia.

Increased Tie2 expression, enhanced response to angiopoietin-1, and dysregulated angiopoietin-2 expression in hemangioma-derived endothelial cells

Infantile hemangiomas are endothelial tumors that grow rapidly in the first year of life and regress slowly during early childhood. Although hemangiomas are well-known vascular lesions, little is known about the mechanisms that cause the excessive endothelial cell proliferation in these most common tumors of infancy. To investigate the molecular basis of hemangioma, we isolated endothelial cells from several proliferative-phase lesions and showed that these cells are clonal and exhibit abnormal properties in vitro (E. Boye, Y. Yu, G. Paranya, J. B. Mulliken, B. R. Olsen, J. Bischoff: Clonality and altered behavior of endothelial cells from hemangiomas. J Clin Invest 2001, 107:745-752). Here, we analyzed mRNA expression patterns of genes required for angiogenesis, including members of the vascular endothelial growth factor (VEGF)/VEGF receptor family and the angiopoietin/Tie family, in hemangioma-derived and normal endothelial cells. KDR, Flt-1, Tie1, Tie2, and angiopoietin-2 (Ang2) were strongly expressed in cultured hemangioma-derived endothelial cells and in hemangioma tissue. In contrast, there was little expression of angiopoietin-1 (Ang1) or VEGF. We found Tie2 mRNA and protein up-regulated with a concomitant increase in cellular responsiveness to Ang1 in most hemangioma-derived endothelial cells. Ang2 mRNA was down-regulated in response to serum in hemangioma-derived endothelial cells, but not in normal endothelial cells, suggesting altered regulation. These findings implicate Tie2 and its ligands Ang1 and Ang2 in the pathogenesis of hemangioma.

Brief murine myocardial I/R induces chemokines in a TNF-alpha-independent manner: role of oxygen radicals

Early chemokine induction in the area at risk of an ischemic-reperfused (I/R) myocardium is first seen in the venular endothelium. Reperfusion is associated with several induction mechanisms including increased extracellular tumor necrosis factor (TNF)-alpha, reactive oxygen intermediate (ROI) species formation, and adhesion of leukocytes to the venular endothelium. To test the hypothesis that chemokine induction in cardiac venules can occur by ROIs in a TNF-alpha-independent manner, and in the absence of leukocyte accumulation, we utilized wild-type (WT) and TNF-alpha double-receptor knockout mice (DKO) in a closed-chest mouse model of myocardial ischemia (15 min) and reperfusion (3 h), in which there is no infarction. We demonstrate that a single brief period of I/R induces significant upregulation of the chemokines macrophage inflammatory protein (MIP) -1 alpha, -1 beta, and -2 at both the mRNA and protein levels. This induction was independent of TNF-alpha, whereas levels of these chemokines were increased in both WT and DKO mice. Chemokine induction was seen predominantly in the endothelium of small veins and was accompanied by nuclear translocation of nuclear factor-kappa B and c-Jun (AP-1) in venular endothelium. Intravenous infusion of the oxygen radical scavenger N-2-mercaptopropionyl glycine (MPG) initiated 15 min before ischemia and maintained throughout reperfusion obviated chemokine induction, but MPG administration after reperfusion had begun had no effect. The results suggest that ROI generation in the reperfused myocardium rapidly induces C-C and C-X-C chemokines in the venular endothelium in the absence of infarction or irreversible cellular injury.

Inflammatory chemokine transport and presentation in HEV: a remote control mechanism for monocyte recruitment to lymph nodes in inflamed tissues

Interstitial fluid is constantly drained into lymph nodes (LNs) via afferent lymph vessels. This conduit enables monocyte-derived macrophages and dendritic cells to access LNs from peripheral tissues. We show that during inflammation in the skin, a second recruitment pathway is evoked that recruits large numbers of blood-borne monocytes to LNs via high endothelial venules (HEVs). Inhibition of monocyte chemoattractant protein (MCP)-1 blocked this inflammation-induced monocyte homing to LNs. MCP-1 mRNA in inflamed skin was over 100-fold upregulated and paralleled MCP-1 protein levels, whereas in draining LNs MCP-1 mRNA induction was much weaker and occurred only after a pronounced rise in MCP-1 protein. Thus, MCP-1 in draining LNs was primarily derived from inflamed skin. In MCP-1(-/-) mice, intracutaneously injected MCP-1 accumulated rapidly in the draining LNs where it enhanced monocyte recruitment. Intravital microscopy showed that skin-derived MCP-1 was transported via the lymph to the luminal surface of HEVs where it triggered integrin-dependent arrest of rolling monocytes. These findings demonstrate that inflamed peripheral tissues project their local chemokine profile to HEVs in draining LNs and thereby exert "remote control" over the composition of leukocyte populations that home to these organs from the blood.

Monocyte chemoattractant protein-1 and its receptor CCR-2 in piglet lungs exposed to inhaled nitric oxide and hyperoxia

Monocyte chemoattractant protein-1 (MCP-1), acting through its C-C chemokine receptor 2 (CCR-2), has important roles in inflammation, angiogenesis, and wound repair. The individual and combined effects of inhaled nitric oxide (NO) and hyperoxia on lung MCP-1 and CCR-2 in relation to lung leukocyte dynamics are unknown. Because MCP-1 gene is up-regulated by oxidants, we hypothesized that inhaled NO with hyperoxia will increase MCP-1 production and CCR-2 expression more than either gas alone. We randomly assigned young piglets to breathe room air (RA), RA+50 ppm NO (RA+NO), O(2), or O(2)+NO for 1 or 5 d before sacrifice. Lungs were lavaged and tissues preserved for hybridization studies, Western blotting, histology, and immunohistochemistry. The results show that lung MCP-1 production and alveolar macrophage count were significantly elevated in the 5-d O(2) and O(2)+NO groups relative to the RA group (p < or = 0.05). In contrast, lung CCR-2 abundance was diminished in the O(2) group (p </= 0.05), but not in the O(2)+NO group, compared with the RA group. No difference was detected in any variable studied at 24 h. CCR-2 distribution was similar in all groups with staining of alveolar septa, macrophages, vascular endothelium, and the luminal epithelial surface of airways. We conclude that although hyperoxia increases MCP-1 in young piglet lungs, it also decreases CCR-2 abundance, which may limit participation of MCP-1 in alveolar macrophage recruitment. Inhaled NO, unlike hyperoxia, has no significant independent effect, but its concurrent administration during hyperoxia attenuates the decremental effect of hyperoxia on CCR-2 abundance.

Monocyte adhesion to human vein grafts: a marker for occult intraoperative injury?

OBJECTIVE

Monocyte adhesion to the vessel wall is believed to be an important initiating event in atherosclerosis and intimal hyperplasia. We hypothesized that occult intraoperative vein injury induces an immediate increase in monocyte adhesion that may be critical to the development of vein graft disease.

METHODS

Vein segments were obtained from patients (n = 23) undergoing lower extremity bypass. The initial segment (V1, n = 17) was excised immediately at the time of conduit harvest. A second segment (V2, n = 23) was obtained from the distal conduit just before performing the distal anastomosis. Segments were incubated with radiolabeled THP-1 cells (monocytoid cell line) for 1 hour at 37 degrees C, then rinsed and solubilized for determination of bound radioactivity. In a subset of grafts (n = 4), THP-1 cells were preincubated with monoclonal antibody (mAB) 7E3 (which binds to the monocyte integrin Mac-1 at its fibrinogen [Fg]-binding site) or control (mAB 14E11). Fg deposition and endothelial coverage were evaluated by immunohistochemistry (n = 10). Statistical analysis was performed using the paired t test and analysis of variance. Follow-up graft patency data were obtained and correlated with adhesion values using an exact test (StatXact, Cytel Software, Cambridge, Mass).

RESULTS

Monocyte adhesion was significantly increased after surgical manipulation (V1, 2400 +/- 770 versus V2, 7343 +/- 1555 cells/cm(2); P <.02). Fg deposition was abundant in V2 sections and not seen in V1. Monocyte adhesion to V2 segments was significantly reduced (58% of control, P <.01) by 7E3 treatment. Graft follow-up was complete with a mean interval of 11 months. Higher V2 adhesion values were associated with occluded grafts (P =.07). The median value for the six occluded grafts was 6234 cells/cm(2) versus 3892 cells/cm(2) for the 17 patent grafts.

CONCLUSIONS

Monocyte adhesion to the vein wall is immediately increased after surgical manipulation and is inhibited by mAB 7E3. Early monocyte adhesion to vein grafts is likely to involve interactions between Mac-1 and Fg. Heightened levels of monocyte adhesion at implantation may be a marker for subsequent vein graft failure.

Enhanced anti-tumor effects of herpes simplex virus thymidine kinase/ganciclovir system by codelivering monocyte chemoattractant protein-1 in hepatocellular carcinoma

The therapeutic efficacy of herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system in many types of tumors is unsatisfactory due to the insufficient spread of gene transfer and insufficient cell killing. In the current study, we investigated whether adenovirally delivered monocyte chemoattractant protein (MCP)-1 potentiates the antitumor effects of the HSV-tk/GCV system in hepatocellular carcinoma (HCC) cells. Subcutaneous tumor foci of the human HCC cell line, HuH7, established in athymic mice were directly transduced with a recombinant adenovirus (rAd) harboring an HSV-tk gene driven by a human alpha-fetoprotein promoter, followed by GCV administration. Subsequently, another rAd expressing MCP-1 under the universal CAG promoter was injected. The growth of tumors was markedly suppressed by codelivering HSV-tk and MCP-1 genes compared to that by either HSV-tk/GCV or MCP-1 delivery. In the tumor tissues, monocyte/macrophage infiltration was detected immunohistochemically. The antitumor effects of the rAd expressing MCP-1 were markedly reduced by the administration of carrageenan, a compound known to inactivate macrophage. These results indicate that adenovirally delivered MCP-1 enhanced the antitumor effects of the HSV-tk/GCV system synergistically by recruitment/activation of macrophages in tumor tissues, suggesting an effective immunotherapy for HCC and other lineages of tumors when used adjuvantly with a suicide gene.

Synergistic effect of indomethacin with adriamycin and cisplatin on tumor growth

In this study, we have examined the antitumor effect of combined administrations of indomethacin (IND) with chemotherapeutic drugs on tumor growth. Colon 26 clone 20 (C20) cells and monocyte chemotactant protein-1 (MCP-1) transfected C20 cells (C20betaA-2-1) were used and these cells were inoculated into the footpad of BALB/c mice. At day 1 after tumor inoculation, treatment with 0.001% IND via the drinking water was commenced. At days 4, 6, and 8, adriamycin or cisplatin was administered intravenously at a dose of 5 mg/kg or intraperitoneally at a dose of 2 mg/kg, respectively. Although IND, adriamycin and cisplatin only partially reduced the growth of the C20 tumors after treatment with each drug on its own, a marked synergistic effect was observed when they were given in combination. A synergistic effect between IND and cisplatin on C20betaA-2-1 was also observed. However, IND itself showed no suppression of C20betaA-2-1 tumor growth. These results suggest that combination of indomethacin with chemotherapeutic drugs could be an effective form of cancer chemotherapy. The observed effects may be dependent on the expression of MCP-1.

Attenuation of hypoxia-ischemia-induced monocyte chemoattractant protein-1 expression in brain of neonatal mice deficient in interleukin-1 converting enzyme

Interleukin-1beta (IL-1beta) upregulates expression of the chemokine monocyte chemoattractant protein-1 (MCP-1) in many experimental models. In neonatal rodent brain, hypoxia-ischemia rapidly stimulates expression of this chemokine, although the role of IL-1beta in regulating this response is unknown. Interleukin-1 converting enzyme (ICE) is a cysteine protease that cleaves inactive pro-IL-1beta to generate mature IL-1beta. Neonatal mice with a homozygous deletion of ICE (ICE -/-) are resistant to moderate, but not to severe cerebral hypoxic-ischemic insults, relative to their wild-type controls. We hypothesized that their resistance to moderate hypoxic-ischemic insults is mediated by suppression of the acute inflammatory response to brain injury in the absence of IL-1beta, and that hypoxia-ischemia induced MCP-1 expression would be attenuated in ICE -/- animals. To test this hypothesis, paired litters of 9-10-day-old ICE -/- and wild-type mice underwent right carotid ligation, followed by 40, 70 or 120 min exposure to 10% O2 and ischemia-induced changes in MCP-1 mRNA and protein were compared, using a semi-quantitative reverse-transcription polymerase chain reaction assay and an ELISA, respectively. With a lesioning protocol that elicits minimal injury in wild-types (ligation+40 min 10% O2), there was an attenuation of hypoxia-ischemia-induced MCP-1 production at 8 h post-hypoxia; in contrast, in animals that underwent longer periods of hypoxia-ischemia the magnitude of injury-induced induced MCP-1 production did not differ between wild-type and ICE -/- animals. These results demonstrate both that the acute inflammatory response to hypoxia-ischemia is attenuated in ICE -/- animals, and also that hypoxic-ischemic brain injury stimulates MCP-1 expression even in the absence of IL-1beta activity.

Chemokines and their receptors in the central nervous system

Chemokines are a family of proteins associated with the trafficking of leukocytes in physiological immune surveillance and inflammatory cell recruitment in host defence. They are classified into four classes based on the positions of key cystiene residues: C, CC, CXC, and CX3C. Chemokines act through both specific and shared receptors that all belong to the superfamily of G-protein-coupled receptors. Besides their well-established role in the immune system, several recent reports have demonstrated that these proteins also play a role in the central nervous system (CNS). In the CNS, chemokines are constitutively expressed by microglial cells, astrocytes, and neurons, and their expression can be increased after induction with inflammatory mediators. Constitutive expression of chemokines and chemokine receptors has been observed in both developing and adult brains, and the role played by these proteins in the normal brain is the object of intense study by many research groups. Chemokines are involved in brain development and in the maintenance of normal brain homeostasis; these proteins play a role in the migration, differentiation, and proliferation of glial and neuronal cells. The chemokine stromal cell-derived factor 1 and its receptor, CXCR4, are essential for life during development, and this ligand-receptor pair has been shown to have a fundamental role in neuron migration during cerebellar formation. Chemokine and chemokine receptor expression can be increased by inflammatory mediators, and this has in turn been associated with several acute and chronic inflammatory conditions. In the CNS, chemokines play an essential role in neuroinflammation as mediators of leukocyte infiltration. Their overexpression has been implicated in different neurological disorders, such as multiple sclerosis, trauma, stroke, Alzheimer's disease, tumor progression, and acquired immunodeficiency syndrome-associated dementia. An emerging area of interest for chemokine action is represented by the communication between the neuroendocrine and the immune system. Chemokines have hormone-like actions, specifically regulating the key host physiopathological responses of fever and appetite. It is now evident that chemokines and their receptors represent a plurifunctional family of proteins whose actions on the CNS are not restricted to neuroinflammation. These molecules constitute crucial regulators of cellular communication in physiological and developmental processes.

Eotaxin (CCL11) induces in vivo angiogenic responses by human CCR3+ endothelial cells

Chemokines are attractants and regulators of cell activation. Several CXC family chemokine members induce angiogenesis and promote tumor growth. In contrast, the only CC chemokine, reported to play a direct role in angiogenesis is monocyte-chemotactic protein-1. Here we report that another CC chemokine, eotaxin (also known as CCL11), also induced chemotaxis of human microvascular endothelial cells. CCL11-induced chemotactic responses were comparable with those induced by monocyte-chemotactic protein-1 (CCL2), but lower than those induced by stroma-derived factor-1alpha (CXCL12) and IL-8 (CXCL8). The chemotactic activity was consistent with the expression of CCR3, the receptor for CCL11, on human microvascular endothelial cells and was inhibited by mAbs to either human CCL11 or human CCR3. CCL11 also induced the formation of blood vessels in vivo as assessed by the chick chorioallantoic membrane and Matrigel plug assays. The angiogenic response induced by CCL11 was about one-half of that induced by basic fibroblast factor, and it was accompanied by an inflammatory infiltrate, which consisted predominantly of eosinophils. Because the rat aortic sprouting assay, which is not infiltrated by eosinophils, yielded a positive response to CCL11, this angiogenic response appears to be direct and is not mediated by eosinophil products. This suggests that CCL11 may contribute to angiogenesis in conditions characterized by increased CCL11 production and eosinophil infiltration such as Hodgkin's lymphoma, nasal polyposis, endometriosis, and allergic diathesis.

Low-Level Monocyte Chemoattractant Protein-1 Stimulation of Monocytes Leads to Tumor Formation in Nontumorigenic Melanoma Cells

Tumors commonly produce chemokines for recruitment of host cells, but the biological significance of tumor-infiltrating inflammatory cells, such as monocytes/macrophages, for disease outcome is not clear. Here, we show that all of 30 melanoma cell lines secreted monocyte chemoattractant protein-1 (MCP-1), whereas normal melanocytes did not. When low MCP-1-producing melanoma cells from a biologically early, nontumorigenic stage were transduced to overexpress the MCP-1 gene, tumor formation depended on the level of chemokine secretion and monocyte infiltration; low-level MCP-1 secretion with modest monocyte infiltration resulted in tumor formation, whereas high secretion was associated with massive monocyte/macrophage infiltration into the tumor mass, leading to its destruction within a few days after injection into mice. Tumor growth stimulated by monocytes/macrophages was due to increased angiogenesis. Vessel formation in vitro was inhibited with mAbs against TNF-alpha, which, when secreted by cocultures of melanoma cells with human monocytes, induced endothelial cells under collagen gels to form branching, tubular structures. These studies demonstrate that the biological effects of tumor-derived MCP-1 are biphasic, depending on the level of secretion. This correlates with the degree of monocytic cell infiltration, which results in increased tumor vascularization and TNF-alpha production.

Chemokines and angiogenesis

Chemokines mediate the ingress of leukocytes, including neutrophils and monocytes, into the inflamed synovium. Among the four known chemokine families, C-X-C and C-C chemokines seem to be of outstanding importance in this process. Angiogenesis, the formation of new vessels, is also important in the pathogenesis of rheumatoid arthritis. In this review, the authors discuss the role of the most important chemokines in the pathogenesis of rheumatoid synovitis. The most relevant angiogenic factors and angiogenesis inhibitors involved in rheumatoid arthritis are also discussed. Because certain chemokines may also play a role in neovascularization, chemokines and the process of angiogenesis are described in this context as well. Apart from discussing the pathogenic role of these factors, the authors also review the important relevance of chemokines and angiogenesis for therapeutic intervention.

Chemokines as regulators of T cell differentiation

Chemokines play well established roles as attractants of naïve and effector T cells. New studies indicate that chemokines also have roles in regulating T cell differentiation. Blocking Gi protein-coupled receptor signaling by pertussis toxin as well as deficiencies in G alpha 12, chemokine receptor 2 (CCR2), CCR5, chemokine ligand 2 (CCL2, also known as monocyte chemoattractant protein 1, or MCP-1), CCL3 (macrophage inflammatory protein 1 alpha, or MIP-1 alpha) and CCL5 (RANTES) have all been found to have effects on the magnitude and cytokine polarity of the T cell response. Here we focus on findings in the CCL2-CCR2 and CCL3-CCR5 ligand-receptor systems. The roles of these molecules in regulating T cell fate include possible indirect effects on antigen-presenting cells and direct effects on differentiating T cells. Models to account for the action of chemokines and G protein-coupled receptor signals in regulating T cell differentiation are discussed.

I-309 binds to and activates endothelial cell functions and acts as an angiogenic molecule in vivo

Several chemokines have been shown to act as angiogenic molecules or to modulate the activity of growth factors such as fibroblast growth factor 2 (FGF-2) and vascular endothelial growth factor (VEGF). The detection of the CC chemokine receptor (CCR) 8 message in human umbilical vein endothelial cells (HUVECs) by reverse transcription– polymerase chain reaction (RT-PCR) and RNase protection assay (RPA), prompted us to investigate the potential role exerted by the CC chemokine I-309, a known ligand of such receptor, in both in vitro and in vivo angiogenesis assays. We show here that I-309 binds to endothelial cells, stimulates chemotaxis and invasion of these cells, and enhances HUVEC differentiation into capillary-like structures in an in vitro Matrigel assay. Furthermore, I-309 is an inducer of angiogenesis in vivo in both the rabbit cornea and the chick chorioallantoic membrane assay (CAM).

CC chemokine receptor-2 is not essential for the development of antigen-induced pulmonary eosinophilia and airway hyperresponsiveness

Monocyte chemoattractant proteins-1 and -5 have been implicated as important mediators of allergic pulmonary inflammation in murine models of asthma. The only identified receptor for these two chemokines to date is the CCR2. To study the role of CCR2 in a murine model of Ag-induced asthma, we compared the pathologic and physiological responses of CCR2(-/-) mice with those of wild-type (WT) littermates following immunization and challenge with OVA. OVA-immunized/OVA-challenged (OVA/OVA) WT and CCR2(-/-) mice developed significant increases in total cells recovered by bronchoalveolar lavage (BAL) compared with their respective OVA-immunized/PBS-challenged (OVA/PBS) control groups. There were no significant differences in BAL cell counts and differentials (i.e., macrophages, PMNs, lymphocytes, and eosinophils) between OVA/OVA WT and CCR2(-/-) mice. Serologic evaluation revealed no significant difference in total IgE and OVA-specific IgE between OVA/OVA WT mice and CCR2(-/-) mice. Lung mRNA expression and BAL cytokine protein levels of IL-4, IL-5, and IFN-gamma were also similar in WT and CCR2(-/-) mice. Finally, OVA/OVA CCR2(-/-) mice developed increased airway hyper-responsiveness to a degree similar to that in WT mice. We conclude that following repeated airway challenges with Ag in sensitized mice, the development of Th2 responses (elevated IgE, pulmonary eosinophilia, and lung cytokine levels of IL-4 and IL5) and the development of airway hyper-responsiveness are not diminished by a deficiency in CCR2.