CXCR3 ligands are augmented during the pathogenesis of pulmonary sarcoidosis.

We and other investigators have hypothesised that the CXC chemokine receptor (CXCR)3/CXCR3 ligand biological axis is involved in the formation of sarcoid lung granulomas; however, significant discrepancies in the current literature remain. In an effort to clarify previous conflicting findings, we performed the largest observational study to date of interferon-inducible ELR(-) (lacking the sequence glutamic acid-leucine-arginine) CXC chemokines in sarcoid bronchoalveolar fluid (BALF). BALF chemokine levels from sarcoid patients (n = 72) and healthy controls (n = 8) were measured with the ELISA method. Immunohistochemical staining was performed for CXCR3 and its ligands. BALF CXC chemokine ligand (CXCL)10 levels from sarcoid patients were not significantly increased compared with controls. BALF CXCL11 levels from sarcoid patients demonstrated a trend towards elevation; subgroup analysis by stage showed significant BALF CXCL11 elevation in stage I sarcoid patients compared with controls. BALF CXCL9 levels were elevated from sarcoid patients compared with controls. CXC11, CXCL9 and CXCR3 were expressed from epithelioid histiocytes, multinucleated giant cells and other inflammatory cells forming sarcoid lung granulomas. Our data suggest that CXCL9 and CXCL11 are important mediators in recruiting CXCR3-expressing cells. Importantly, we have made the novel observation that both lymphocytes and cells of monocyte linage express CXCR3 and are involved in the formation of sarcoid lung granulomas.

CCL19 reduces tumour burden in a model of advanced lung cancer.

Epstein-Barr virus-induced molecule 1 ligand chemokine (CCL19) is a CC chemokine that chemoattracts both dendritic cells (DC) and T lymphocytes. We evaluated the antitumour efficacy of CCL19 in a murine model of spontaneous bronchoalveolar cell carcinoma. These transgenic mice (CC-10 TAg) express the SV40 large T antigen under the Clara Cell promoter, develop bilateral, multifocal, pulmonary carcinomas and die at 4 months owing to progressive pulmonary tumour burden. To mimic therapy in late-stage disease, 3-month-old transgenic mice were treated with recombinant CCL19 (0.5 microg dose(-1)) by intranodal (axillary lymph node region) injection three times per week for 4 weeks. CCL19 treatment led to a marked reduction in tumour burden with extensive mononuclear infiltration of the tumours compared to diluent treated controls. Flow cytometric analyses showed significant increases in CD4 and CD8T cell subsets as well as DC in the lungs of CCL19-treated mice. Lung tissue cytokine profiles showed a shift towards immune stimulatory molecules with a decrease in the immunosuppressive cytokine TGF-beta. Our findings show that CCL19 may serve as a potential immune stimulator and provide a strong rationale for the evaluation of CCL19 in cancer immunotherapy.

Chemokines as therapeutic targets in non-small cell lung cancer.

Angiogenesis, defined as the generation of new blood vessels from pre-existing vessels, is one of life's essential processes. Inflammation and angiogenesis, while distinct and separable, are closely related processes. One of the hallmarks of chronic inflammation is granulation tissue, a prominent feature of which is neovascularization. Whenever tissue constituents proliferate, repair, or hypertrophy, such change must be accompanied by a proportional increase in capillary blood supply to assure delivery of nutrients, and removal of metabolic waste. This absolute dependence suggests two characteristics of angiogenesis. First, under normal conditions the process must be tightly controlled. Second, in the absence of such strict control, abnormal physiology, or disease is likely to result. The role of angiogenesis in solid tumor growth has attracted a great deal of attention as a potential therapeutic target. Lung cancer is a particularly devastating disease in industrialized countries. The majority of patients with lung cancer are faced with very poor therapeutic options, and gaining insight to the mechanism of angiogenesis in this disease has obvious implications for the design of therapeutic agents. Research in our laboratories has demonstrated that chemokines (chemotactic cytokines) are pivotal determinants of the angiogenic activity of non-small cell lung cancer (NSCLC). This review will focus on the evidence supporting the central role of these molecules in lung cancer angiogenesis, and focus on potential novel means of targeting this family of angiogenic regulators.

ENA-78 is an important angiogenic factor in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic and often fatal disorder. Fibroplasia and deposition of extracellular matrix are dependent, in part, on angiogenesis and vascular remodeling. We obtained open lung biopsies from patients undergoing thoracic surgery for reasons other than interstitial lung disease (control) (n = 78) and from patients with IPF (n = 91). We found that levels of epithelial neutrophil-activating peptide 78 (ENA-78) were greater from tissue specimens of IPF patients, as compared with control subjects. When ENA-78 was depleted from IPF tissue specimens, tissue-derived angiogenic activity was markedly reduced. Immunolocalization of ENA-78 demonstrated that hyperplastic Type II pneumocytes and macrophages were the predominant cellular sources of ENA-78. These findings support the notion that ENA-78 may be an important additional factor that regulates angiogenic activity in IPF.

The regulation of interleukin-8 by hypoxia in human macrophages--a potential role in the pathogenesis of the acute respiratory distress syndrome (ARDS).

BACKGROUND: The acute respiratory distress syndrome (ARDS) represents a form of severe acute inflammatory lung disease. We have previously demonstrated significantly raised interleukin-8 (IL-8) levels in the lungs of at-risk patients that progress to ARDS, and identified the alveolar macrophage as an important source of this chemokine. We wished to extend this study in a well-defined group of patients with major trauma, and to investigate potential mechanisms for rapid intrapulmonary IL-8 generation. MATERIALS AND METHODS: Patients with major trauma underwent bronchoalveolar lavage (BAL) and IL-8 levels were measured in BAL fluid by ELISA. Human macrophages were derived from peripheral blood monocytes from healthy volunteers. Rabbit alveolar macrophages were obtained from ex-vivo lavage of healthy rabbit lungs. Macrophages were culture under normoxic or hypoxic (PO2 26 mmHg) conditions. IL-8 and other proinflammatory mediator expression was measured by ELISA, northern blotting or multi-probe RNase protection assay. RESULTS: In patients with major trauma, IL-8 levels were significantly higher in patients that progressed to ARDS compared to those that did not (n = 56, P = 0.0001). High IL-8 levels negatively correlated with PaO2/FiO2 (r = -0.56, P < 0.001). In human monocyte derived macrophages hypoxia rapidly upregulated IL-8 protein (within 2 hours) and mRNA expression (within 30 mins). Acute hypoxia also increased rabbit alveolar macrophage IL-8 expression. Hypoxia increased DNA binding activity of AP-1 and C/EBP but not NF-kappaB. Hypoxia induced HIF-1 expression, but cobaltous ions and desferrioxamine did not mimic hypoxic IL-8 induction. Hypoxia downregulated a range of other proinflammatory mediators, including MCP-1 and TNF-alpha. Both the pattern of cytokine expression and transcription factor activation by hypoxia was different to that seen with endotoxin. CONCLUSIONS: Rapidly raised intrapulmonary IL-8 levels are associated with ARDS progression in patients with major trauma. Acute hypoxia, a clinically relevant stimulus, rapidly and selectively upregulates IL-8 in macrophages associated with a novel pattern of transcription factor activation. Acute hypoxia may represent one of potentially several proinflammatory stimuli responsible for rapid intrapulmonary IL-8 generation in patients at-risk of ARDS.

Monokine induced by IFN-gamma is a dominant factor directing T cells into murine cardiac allografts during acute rejection.

The use of chemokine antagonism as a strategy to inhibit leukocyte trafficking into inflammatory sites requires identification of the dominant chemokines mediating recruitment. The chemokine(s) directing T cells into cardiac allografts during acute rejection remain(s) unidentified. The role of the CXC chemokines IFN-gamma inducible protein 10 (IP-10) and monokine induced by IFN-gamma (Mig) in acute rejection of A/J (H-2(a)) cardiac grafts by C57BL/6 (H-2(b)) recipients was tested. Intra-allograft expression of Mig was observed at day 2 posttransplant and increased to the time of rejection at day 7 posttransplant. IP-10 mRNA and protein production were 2.5- to 8-fold lower than Mig. Whereas allografts were rejected at day 7-9 in control recipients, treatment with rabbit antiserum to Mig, but not to IP-10, prolonged allograft survival up to day 19 posttransplant. At day 7 posttransplant, allografts from Mig antiserum-treated recipients had marked reduction in T cell infiltration. At the time of rejection in Mig antiserum-treated recipients (i.e., days 17-19), intra-allograft expression of macrophage-inflammatory protein-1alpha, -1beta, and their ligand CCR5 was high, whereas expression of CXCR3, the Mig receptor, was virtually absent. Mig was produced by the allograft endothelium as well as by recipient allograft-infiltrating macrophages and neutrophils, indicating the synergistic interactions between innate and adaptive immune compartments during acute rejection. Collectively, these results indicate that Mig is a dominant recruiting factor for alloantigen-primed T cells into cardiac allografts during acute rejection. Although Mig antagonism delays acute heart allograft rejection, the results also suggest that the alloimmune response circumvents Mig antagonism through alternative mechanisms.

Overexpression of CXC chemokines by an adrenocortical carcinoma: a novel clinical syndrome.

A patient with adrenocortical carcinoma presented with fever, leukocytosis, and increased acute phase reactants. The tumor was infiltrated with neutrophils. Immunohistochemical staining of the tumor showed positive signal for epithelial neutrophil-activating protein-78, an angiogenic and chemotactic CXC chemokine. Conditioned medium from tumor-derived cells (RL-251) showed high concentration of IL-8, epithelial neutrophil-activating protein-78, Gro alpha, and Gro gamma, angiogenic CXC chemokines with a potential role in tumorigenesis. An adrenal cancer/severe combined immunodeficiency mouse chimera was developed. Mice grew tumors rapidly, and circulating levels of IL-8 and epithelial neutrophil-activating protein-78 were detected. In contrast, animals transplanted with NCI-H295 cells, a nonchemokine-secreting cell line, grew tumors more slowly and did not have detectable chemokine levels. Similar to the patient, mice with RL-251 tumors developed marked leukocytosis and neutrophilia, and their tumors were infiltrated with neutrophils. Mice were passively immunized with epithelial neutrophil-activating protein-78 antisera. A marked decrease in tumor growth was observed. Potential for chemokine production by other adrenocortical tumors was investigated by RT-PCR in archival material. Six of seven adrenal carcinomas and one of three adenomas had cDNA for IL-8; six of seven carcinomas and the three adenomas had cDNA for epithelial neutrophil-activating protein-78. We concluded that the clinical presentation of this case resulted from increased tumor production of chemotactic chemokines. Through their angiogenic and chemotactic properties these chemokines may play an important role in adrenal tumorigenesis.

Interleukin-8 stimulates human immunodeficiency virus type 1 replication and is a potential new target for antiretroviral therapy.

Production of the C-X-C chemokines interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) in macrophages is stimulated by exposure to human immunodeficiency virus type 1 (HIV-1). We have demonstrated previously that GRO-alpha then stimulates HIV-1 replication in both T lymphocytes and macrophages. Here we demonstrate that IL-8 also stimulates HIV-1 replication in macrophages and T lymphocytes. We further show that increased levels of IL-8 are present in the lymphoid tissue of patients with AIDS. In addition, we demonstrate that compounds which inhibit the actions of IL-8 and GRO-alpha via their receptors, CXCR1 and CXCR2, also inhibit HIV-1 replication in both T lymphocytes and macrophages, indicating potential therapeutic uses for these compounds in HIV-1 infection and AIDS.

Human immunodeficiency virus type 1 (HIV-1)-induced GRO-alpha production stimulates HIV-1 replication in macrophages and T lymphocytes.

We examined the early effects of infection by CCR5-using (R5 human immunodeficiency virus [HIV]) and CXCR4-using (X4 HIV) strains of HIV type 1 (HIV-1) on chemokine production by primary human monocyte-derived macrophages (MDM). While R5 HIV, but not X4 HIV, replicated in MDM, we found that the production of the C-X-C chemokine growth-regulated oncogene alpha (GRO-alpha) was markedly stimulated by X4 HIV and, to a much lesser extent, by R5 HIV. HIV-1 gp120 engagement of CXCR4 initiated the stimulation of GRO-alpha production, an effect blocked by antibodies to CXCR4. GRO-alpha then fed back and stimulated HIV-1 replication in both MDM and lymphocytes, and antibodies that neutralize GRO-alpha or CXCR2 (the receptor for GRO-alpha) markedly reduced viral replication in MDM and peripheral blood mononuclear cells. Therefore, activation of MDM by HIV-1 gp120 engagement of CXCR4 initiates an autocrine-paracrine loop that may be important in disease progression after the emergence of X4 HIV.

Interleukin-8 administration enhances venous thrombosis resolution in a rat model.

BACKGROUND: Therapy for deep vein thrombosis (DVT) resolution in those patients in whom a complication or contraindication to anticoagulation occurs is limited. As prior work suggests that thrombus maturation involves early influx of neutrophils (PMN) and neovascularization, we hypothesized that administering the proinflammatory/proangiogenic chemokine interleukin (IL)-8 might accelerate thrombus resolution. MATERIALS AND METHODS: An established rodent model of DVT (inferior vena cava [IVC] ligation) was used whereby daily intravenous recombinant human IL-8 (1 microg) or vehicle control was administered, with sacrifice at 4 and 8 days. Prior to sacrifice and at harvest, duplex ultrasound of the DVT and femoral venous pressure measurements were performed. Thrombi were analyzed by immunohistochemical techniques for PMN, monocytes, and neovascularization; for chemokines, by enzyme-linked immunoassay; and fibrosis, by hydroxyproline assay and trichrome staining. RESULTS: IL-8 accelerated thrombus dissolution 4 days after IVC ligation, with 6-fold increased thrombus blood flow by duplex ultrasound and a 23% increased absolute femoral venous pressure compared with controls (both P < 0.05). These findings may be partially explained by the fact that animals receiving IL-8, as compared with controls, had 2.5-fold greater thrombus neovascularization (with a trend continuing to 8 days) and increased PMN at 4 days. Thrombus vascular endothelial growth factor was significantly reduced at 8 days postligation, while monocyte chemotactic protein-1 and macrophage inflammatory protein-1alpha were not altered by IL-8 administration. At 8 days post-IVC-ligation, fibrosis was 12-fold greater with IL-8 treatment compared with controls. CONCLUSIONS: A proinflammatory/proangiogenic thrombus milieu, as conferred by IL-8, enhances thrombus resolution and underscores the important relationship between neovascularity and inflammation.

Up-Regulation of Bcl-2 in microvascular endothelial cells enhances intratumoral angiogenesis and accelerates tumor growth.

Vascular endothelial growth factor (VEGF) has been shown to be a potent mediator of angiogenesis that functions as a survival factor for endothelial cells by up-regulating Bcl-2 expression. We have recently reported that human dermal microvascular endothelial cells (HDMECs) seeded in biodegradable sponges and implanted into severe combined immunodeficient (SCID) mice organize into functional human microvessels that transport mouse blood cells. In this study, we implanted sponges seeded with OSCC-3 (oral squamous cell carcinoma) or SLK (Kaposi's sarcoma) together with endothelial cells into SCID mice to generate human tumors vascularized with human microvessels. This model system was used to examine the role of both endothelial cell Bcl-2 and the proangiogenic chemokine interleukin-8 (IL-8) on tumor growth and intratumoral microvascular density. Coimplantation of HDMECs overexpressing Bcl-2 (HDMEC-Bcl-2) and tumor cells resulted in a 3-fold enhancement of tumor growth when compared with the coimplantation of control HDMECs and tumor cells. This was associated with increased intratumoral microvascular density and enhanced endothelial cell survival. To determine whether the enhanced neovascularization mediated by Bcl-2 overexpression in endothelial cells was influenced by the synthesis of endogenous mediators of angiogenesis, we screened these cells for expression of VEGF, basic fibroblast growth factor (bFGF), and IL-8 by ELISA. HDMEC-Bcl-2 cells and VEGF-treated HDMECs exhibited a 15-fold and 4-fold increase, respectively, in the expression of the proangiogenic chemokine IL-8 in vitro, whereas the expression of VEGF and bFGF remained unchanged. Transfection of antisense Bcl-2 into HDMECs blocked VEGF-mediated induction of IL-8. Conditioned media from HDMEC-Bcl-2 induced proliferation and sprouting of endothelial cells in vitro and neovascularization in rat corneas. Anti-IL-8 antibody added to HDMEC-Bcl-2 conditioned media markedly reduced the potency of these responses. SCID mice bearing VEGF-producing tumor implants that were treated with anti-lL-8 antibody exhibited a 43% reduction in microvessel density and a 50% reduction in tumor weight compared with treatment with a nonspecific antibody. These results demonstrate that the up-regulation of Bcl-2 expression in endothelial cells that constitute tumor microvessels enhances intratumoral microvascular survival and density and accelerates tumor growth. Furthermore, endothelial cells that overexpress Bcl-2 have more angiogenic potential than control cells, and IL-8-neutralizing antibodies attenuate their angiogenic activity in vitro and in vivo.

Elevated levels of interleukin-8 in donor lungs is associated with early graft failure after lung transplantation.

Increased levels of the neutrophil chemokine interleukin (IL)-8 in the lungs of severe trauma patients can predict subsequent development of acute respiratory distress syndrome. Because the lungs of brain-dead organ donors can contain high levels of IL-8, we hypothesized that this may predispose to early graft failure in the recipient after lung transplantation. Twenty-six organ donors prospectively satisfying clinical criteria for lung donation underwent bronchoalveolar lavage and lung biopsy to determine the effect of neutrophil infiltration and IL-8 expression in the donor lung on graft function and survival in 26 respective recipients after lung transplantation. Nine recipients developed severe graft dysfunction, of whom six subsequently died (median survival: 24 d [range: 5 to 39 d]); all others survived beyond 6 mo. The IL-8 signal in the donor lung correlated with the percent neutrophils in bronchoalveolar lavage fluid (BALF) before implantation (42.4 +/- 7.24 [mean +/- SE]%, p = 0.03) and with the degree of impairment in graft oxygenation after implantation (p = 0.01). An increased level of IL-8 in the donor BALF was associated with the development of severe early graft dysfunction (p = 0.027) and with early recipient mortality (p = 0.0034). Use of donor lungs with high IL-8 levels is associated with a poor prognosis after lung transplantation. Attenuating the donor's inflammatory response before organ retrieval may improve early outcome after lung transplantation, and help maximize lung use from the existing donor pool.

Regulation of angiogenesis by the C-X-C chemokines interleukin-8 and epithelial neutrophil activating peptide 78 in the rheumatoid joint.

OBJECTIVE: Angiogenesis, the growth of new blood vessels, is vital to the ingress of inflammatory leukocytes in rheumatoid arthritis (RA) synovial tissue and to the growth and proliferation of RA pannus. The factors that mediate the growth of new blood vessels have not been completely defined. This study examined the ability of Glu-Leu-Arg (ELR)-containing chemokines to induce angiogenesis in the RA joint. METHODS: To reflect angiogenic activity in vivo, we selected a model using whole human synovial tissue rather than isolated cells. Tissues were examined by immunohistochemistry and enzyme-linked immunosorbent assay, and tissue homogenates were immunoneutralized and assayed for their ability to induce endothelial cell chemotaxis and rat corneal neovascularization. RESULTS: Cells expressing interleukin-8 (IL-8) and epithelial neutrophil activating peptide 78 (ENA-78) were located in proximity to factor VIII-related antigen-immunopositive endothelial cells. RA homogenates produced more IL-8 and ENA-78 compared with normal synovial tissue homogenates. Moreover, homogenates from RA synovial tissue produced significantly more chemotactic activity for endothelial cells in vitro and angiogenic activity in the rat cornea in vivo than did normal synovial tissue homogenates. The effects of IL-8 and ENA-78 accounted for a significant proportion of the chemotactic activity of endothelial cells and angiogenic activity found in RA synovial tissue homogenates. CONCLUSION: These results indicate that the ELR-containing chemokines IL-8 and ENA-78 are important contributors to the angiogenic activity found in the inflamed RA joint. It is possible that efforts aimed at down-regulating these chemokines offer a novel targeted therapy for the treatment of RA.

The murine CC chemokine, 6C-kine, inhibits tumor growth and angiogenesis in a human lung cancer SCID mouse model.

The recently described CC chemokine, 6C-kine, is unique in that it contains -six rather than the usual four conserved cysteines typical of this family. Furthermore, murine 6C-kine binds to one of the CXC chemokine receptors CXCR3, in addition to its other known receptor CCR7. We have shown that two other ligands of CXCR3, IP-10 and MIG, are potent inhibitors of tumor growth in severe combined immunodeficiency (SCID) mice. We postulated that murine 6C-kine may also inhibit tumor growth via inhibition of angiogenesis in this model. SCID mice (n = 6 per group) inoculated with A549 human lung cancer cells were treated with either 6C-kine (100 ng intra-tumor injection every other day) or control protein for 8 weeks. Tumors from murine 6C-kine-treated mice (288 +/- 26 mm3) were significantly smaller than tumors from control treated mice (788 +/- 156 mm3, P = 0.005). Additionally, murine 6C-kine reduced metastases compared with controls (0.5 +/- 0.3 vs 3.0 +/- 1.2 metastases per animal, P = 0.05). Tumor vascularity (as assessed by vessel density counting) was reduced in murine 6C-kine-treated mice compared with controls. Murine 6C-kine had no direct effect on proliferation of A549 cells, and there were no differences in the infiltration of leukocyte sub-populations, assessed by flow cytometry, in the treatment groups. Interestingly, human 6C-kine, unlike murine 6C-kine, does not bind CXCR3 and had no anti-tumor effect in the same model. These data suggest that murine 6Ckine has anti-tumor effects independent of its leukocyte-recruiting activity. Furthermore, while not confirmatory, these data lend further support to the fact that CXCR3 may be the receptor for angiostatic CXC chemokines.

Complete regression of established spontaneous mammary carcinoma and the therapeutic prevention of genetically programmed neoplastic transition by IL-12/pulse IL-2: induction of local T cell infiltration, Fas/Fas ligand gene expression, and mammary epithelial apoptosis.

Using a novel transgenic mouse model of spontaneous mammary carcinoma, we show here that the IL-12/pulse IL-2 combination can induce rapid and complete regression of well-established autochthonous tumor in a setting where the host immune system has been conditioned by the full dynamic process of neoplastic progression and tumorigenesis. Further, this regimen inhibits neovascularization of established mammary tumors, and does so in conjunction with potent local induction of genes encoding the IFN-gamma- and TNF-alpha-inducible antiangiogenic chemokines IFN-inducible protein 10 and monokine induced by IFN-gamma. In contrast to untreated juvenile C3(1)TAg mice in which histologically normal mammary epithelium predictably undergoes progressive hyperplasia, atypical changes, and ultimately transition to overt carcinoma, the current studies also demonstrate a unique preventative therapeutic role for IL-12/pulse IL-2. In juvenile mice, early administration of IL-12/pulse IL-2 markedly limits the expected genetically programmed neoplastic transition within the mammary epithelium and does so in conjunction with enhancement of constitutive Fas and pronounced induction of local Fas ligand gene expression, T cell infiltration, and induction of apoptosis within the mammary epithelium. These events occur in the absence of a durable Ag-specific memory response. Thus, this novel model system demonstrates that the potent therapeutic activity of the IL-12/pulse IL-2 combination rapidly engages potent apoptotic and antiangiogenic mechanisms that remain active during the delivery of IL-12/pulse IL-2. The results also demonstrate that these mechanisms are active against established tumor as well as developing preneoplastic lesions.

Improved survival in tumor-bearing SCID mice treated with interferon-gamma-inducible protein 10 (IP-10/CXCL10).

Tumor growth requires angiogenesis, which in turn requires an imbalance in the presence of angiogenic and angiostatic factors. We have shown that the CXC chemokine family, consisting of members that are either angiogenic or angiostatic, is a major determinant of tumor-derived angiogenesis in non-small-cell lung cancer (NSCLC). Intratumor injection of interferon-inducible protein 10 (IP-10, or CXCL10), an angiostatic CXC chemokine, led to reduced tumor growth in a SCID mouse model of NSCLC. In this study, we hypothesized that treatment with CXCL10 would, by restoring the angiostatic balance, improve long-term survival in NSCLC-bearing SCID mice. To test this hypothesis, A549 NSCLC cells were injected in the subcutis of the flank, followed by intratumor injections with CXCL10 continuously (group I), or for ten weeks (group II), or a control group (human serum albumin). Median survival was 169, 130, and 86 days respectively (P<0.0001). We extended these studies to examine the mechanism of prolonged survival in CXCL10-treated mice. CXCL10 treatment inhibited lung metastases, but was dependent upon continued treatment, and was associated with an increased rate of apoptosis in the primary tumor, with no direct effect on the proliferation of the NSCLC cells. Furthermore, the inhibition of lung metastases was due to the angiostatic effect of CXCL10 on the primary tumor, since the rate of apoptosis within lung metastases was unaffected. These data suggest that anti-angiogenic therapy of human lung cancer should be continued indefinitely to realize persistent benefit, and confirms the anti-metastatic capacity of localized angiostatic therapy.

Novel protective effects of stem cell factor in a murine model of acute septic peritonitis. Dependence on MCP-1.

Mast cells participate in the host response during sepsis and have been shown to have a protective effect in a murine model of acute septic peritonitis and multi-organ failure initiated by cecal ligation and puncture (CLP). Stem cell factor (SCF) is a hematopoietic cytokine important in mast cell proliferation and activation. In the present study, we examined the protective effects of a single intraperitoneal injection of SCF given 2 hours before CLP surgery in mice. Four days after the CLP surgery, SCF pretreatment significantly improved mouse survival from 29 to 56% and mast cells were absolutely required for this effect. Immunoneutralization studies revealed that the SCF-stimulated release of monocyte chemoattractant protein-1 (MCP-1) into the septic peritoneal cavity contributed to the protective effect of SCF in this model. One potential cellular source of MCP-1 was the SCF-activated mast cell. In addition, SCF pretreatment significantly augmented circulating levels of SCF and the immunomodulatory cytokine interleukin-10 in septic mice, in part because the SCF pretreatment seemed to promote the release of both mediators from the liver. Additional hepatic effects of SCF treatment included an accelerated expression of hepatic levels of signal transducer and activator of transcription-3 (STAT-3) in CLP mice pretreated with SCF. Taken together, the findings from the present study demonstrate that the intraperitoneal delivery of SCF has a major protective effect in a murine model of CLP.

Chemokine C10 promotes disease resolution and survival in an experimental model of bacterial sepsis.

Previous studies have suggested that the C-C chemokine C10 is involved in the chronic stages of host defense reactions. The present study addressed the role of C10 in a murine model of septic peritonitis, induced by cecal ligation and puncture (CLP). Unlike other C-C chemokines, C10 levels in the peritoneal wash were increased approximately 30-fold above baseline levels at 48 h after CLP surgery. Immunoneutralization of peritoneal C10 levels with polyclonal anti-C10 antiserum during CLP-induced peritonitis negatively impacted mouse survival over 4 days. In contrast, when 500 ng of recombinant murine C10 was administered immediately after CLP surgery, the 4-day survival rate increased from 20% to over 60%. The C10 therapy appeared to facilitate a rapid and significant enhancement of the levels of tumor necrosis factor alpha (TNF-alpha) and monocyte chemoattractant protein-1 (MCP-1) and a later increase in interleukin-13 (IL-13) levels in the peritoneal cavity. In vitro studies showed that the combination of IL-1beta and C10 markedly augmented TNF-alpha synthesis by peritoneal macrophages and that C10 synthesis was induced in these cells following their exposure to IL-13. At 24 h after CLP surgery, only 25% of C10-treated mice were bacteremic versus 85% of the control group that exhibited dissemination of bacteria into the circulation. The lack of bacteremia in C10-treated mice appeared to be related, in part, to in vitro evidence that C10 significantly enhanced the bacterial phagocytic activity of peritoneal macrophages. In addition, in vivo evidence suggested that C10 therapy significantly reduced the amount of material that leaked from the damaged gut. Taken together, the results of this study demonstrate that the C10 chemokine rapidly promotes disease resolution in the CLP model through its direct effects on the cellular events critically involved in host defense during septic peritonitis.

The CXC chemokine receptor 2, CXCR2, is the putative receptor for ELR+ CXC chemokine-induced angiogenic activity.

We have previously shown that members of the ELR(+) CXC chemokine family, including IL-8; growth-related oncogenes alpha, beta, and gamma; granulocyte chemotactic protein 2; and epithelial neutrophil-activating protein-78, can mediate angiogenesis in the absence of preceding inflammation. To date, the receptor on endothelial cells responsible for chemotaxis and neovascularization mediated by these ELR(+) CXC chemokines has not been determined. Because all ELR(+) CXC chemokines bind to CXC chemokine receptor 2 (CXCR2), we hypothesized that CXCR2 is the putative receptor for ELR(+) CXC chemokine-mediated angiogenesis. To test this postulate, we first determined whether cultured human microvascular endothelial cells expressed CXCR2. CXCR2 was detected in human microvascular endothelial cells at the protein level by both Western blot analysis and immunohistochemistry using polyclonal Abs specific for human CXCR2. To determine whether CXCR2 played a functional role in angiogenesis, we determined whether this receptor was involved in endothelial cell chemotaxis. We found that microvascular endothelial cell chemotaxis in response to ELR(+) CXC chemokines was inhibited by anti-CXCR2 Abs. In addition, endothelial cell chemotaxis in response to ELR(+) CXC chemokines was sensitive to pertussis toxin, suggesting a role for G protein-linked receptor mechanisms in this biological response. The importance of CXCR2 in mediating ELR(+) CXC chemokine-induced angiogenesis in vivo was also demonstrated by the lack of angiogenic activity induced by ELR(+) CXC chemokines in the presence of neutralizing Abs to CXCR2 in the rat corneal micropocket assay, or in the corneas of CXCR2(-/-) mice. We thus conclude that CXCR2 is the receptor responsible for ELR(+) CXC chemokine-mediated angiogenesis.