Inflammation, inflammatory cells and angiogenesis: decisions and indecisions

Identification of a potent endothelium-derived angiogenic factor

The secretion of angiogenic factors by vascular endothelial cells is one of the key mechanisms of angiogenesis. Here we report on the isolation of a new potent angiogenic factor, diuridine tetraphosphate (Up4U) from the secretome of human endothelial cells. The angiogenic effect of the endothelial secretome was partially reduced after incubation with alkaline phosphatase and abolished in the presence of suramin. In one fraction, purified to homogeneity by reversed phase and affinity chromatography, Up4U was identified by MALDI-LIFT-fragment-mass-spectrometry, enzymatic cleavage analysis and retention-time comparison. Beside a strong angiogenic effect on the yolk sac membrane and the developing rat embryo itself, Up4U increased the proliferation rate of endothelial cells and, in the presence of PDGF, of vascular smooth muscle cells. Up4U stimulated the migration rate of endothelial cells via P2Y2-receptors, increased the ability of endothelial cells to form capillary-like tubes and acts as a potent inducer of sprouting angiogenesis originating from gel-embedded EC spheroids. Endothelial cells released Up4U after stimulation with shear stress. Mean total plasma Up4U concentrations of healthy subjects (N=6) were sufficient to induce angiogenic and proliferative effects (1.34 ± 0.26 nmol L(-1)). In conclusion, Up4U is a novel strong human endothelium-derived angiogenic factor.

Preliminary evidence of sustained expression of angiopoietin-2 during monocyte differentiation in chronic hepatitis C

BACKGROUND

Monocytes are essential precursors of antigen-presenting cells, such as macrophages and dendritic cells, and contribute to the pathogenesis of chronic inflammatory diseases and cancer.

AIMS

As Tie2-expressing monocytes (TEMs) are increased in the peripheral blood of patients with chronic hepatitis C (CHC), we aimed to examine the expression of Tie2 and angiopoietins (Ang1 and Ang2) during monocyte differentiation and maturation in CHC.

METHODS

The expression of Tie2, CD11b, CD80, CD83, CD86 and MHC-II was measured by flow cytometry in peripheral blood monocytes and monocytes-derived cells (Mo-DCs) from nine healthy subjects and eight CHC patients whose HCV infection was unresolved after combination therapy. Ang1 and Ang2 levels were measured in cellular supernatants by ELISA.

RESULTS

Mo-DCs from CHC patients expressed differential patterns of maturation markers compared with controls--primarily with regard to CD80. Tie2 was downregulated during monocyte differentiation in controls and CHC patients, whereas Ang1 expression was constant. However, Ang2 levels fell significantly during the differentiation of control monocytes, in contrast with those from CHC patients in whom Ang2 expression remained stable throughout differentiation.

CONCLUSIONS

Altered expression of the Ang/Tie2 system in monocytes and Mo-DCs from CHC patients might account for the inflammatory and angiogenic disorders that are related to CHC. An increased understanding of Ang/Tie2 system regulation might be helpful in designing strategies to prevent CHC progression.

Role of platelet chemokines, PF-4 and CTAP-III, in cancer biology

With the recent addition of anti-angiogenic agents to cancer treatment, the angiogenesis regulators in platelets are gaining importance. Platelet factor 4 (PF-4/CXCL4) and Connective tissue activating peptide III (CTAP-III) are two platelet-associated chemokines that modulate tumor angiogenesis, inflammation within the tumor microenvironment, and in turn tumor growth. Here, we review the role of PF-4 and CTAP-III in the regulation of tumor angiogenesis; the results of clinical trial using recombinant PF-4 (rPF-4); and the use of PF-4 and CTAP-III as cancer biomarkers.

Cannabidiol inhibits angiogenesis by multiple mechanisms

BACKGROUND AND PURPOSE

Several studies have demonstrated anti-proliferative and pro-apoptotic actions of cannabinoids on various tumours, together with their anti-angiogenic properties. The non-psychoactive cannabinoid cannabidiol (CBD) effectively inhibits the growth of different types of tumours in vitro and in vivo and down-regulates some pro-angiogenic signals produced by glioma cells. As its anti-angiogenic properties have not been thoroughly investigated to date, and given its very favourable pharmacological and toxicological profile, here, we evaluated the ability of CBD to modulate tumour angiogenesis.

EXPERIMENTAL APPROACH

Firstly, we evaluated the effect of CBD on human umbilical vein endothelial cell (HUVEC) proliferation and viability - through [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and FACS analysis - and in vitro motility - both in a classical Boyden chamber test and in a wound-healing assay. We next investigated CBD effects on different angiogenesis-related proteins released by HUVECs, using an angiogenesis array kit and an ELISA directed at MMP2. Then we evaluated its effects on in vitro angiogenesis in treated HUVECs invading a Matrigel layer and in HUVEC spheroids embedded into collagen gels, and further characterized its effects in vivo using a Matrigel sponge model of angiogenesis in C57/BL6 mice.

KEY RESULTS

CBD induced HUVEC cytostasis without inducing apoptosis, inhibited HUVEC migration, invasion and sprouting in vitro, and angiogenesis in vivo in Matrigel sponges. These effects were associated with the down-modulation of several angiogenesis-related molecules.

CONCLUSIONS AND IMPLICATIONS

This study reveals that CBD inhibits angiogenesis by multiple mechanisms. Its dual effect on both tumour and endothelial cells supports the hypothesis that CBD has potential as an effective agent in cancer therapy.

Inflammation and oxidative stress in angiogenesis and vascular disease

Recent evidence suggests that processes of inflammation and angiogenesis are interconnected, especially in human pathologies. Newly formed blood vessels enable the continuous recruitment of inflammatory cells, which release a variety of proangiogenic cytokines, chemokines, and growth factors and further promote angiogenesis. These series of positive feedback loops ultimately create a vicious cycle that exacerbates inflammation, transforming it into the chronic process. Recently, this concept of reciprocity of angiogenesis and inflammation has been expanded to include oxidative stress as a novel mechanistic connection between inflammation-driven oxidation and neovascularization. Production of reactive oxygen species results from activation of immune cells by proinflammatory stimuli. As oxidative stress can lead to chronic inflammation by activating a variety of transcription factors including NF-κB, AP-1, and PPAR-γ, inflammation itself has a reciprocal relationship with oxidative stress. This review discusses the recent findings in the area bridging neovascularization and oxidation and highlights novel mechanisms of inflammation- and oxidative stress-driven angiogenesis.

Role of macrophage targeting in the antitumor activity of trabectedin

There is widespread interest in macrophages as a therapeutic target in cancer. Here, we demonstrate that trabectedin, a recently approved chemotherapeutic agent, induces rapid apoptosis exclusively in mononuclear phagocytes. In four mouse tumor models, trabectedin caused selective depletion of monocytes/macrophages in blood, spleens, and tumors, with an associated reduction of angiogenesis. By using trabectedin-resistant tumor cells and myeloid cell transfer or depletion experiments, we demonstrate that cytotoxicity on mononuclear phagocytes is a key component of its antitumor activity. Monocyte depletion, including tumor-associated macrophages, was observed in treated tumor patients. Trabectedin activates caspase-8-dependent apoptosis; selectivity for monocytes versus neutrophils and lymphocytes is due to differential expression of signaling and decoy TRAIL receptors. This unexpected property may be exploited in different therapeutic strategies.

Eicosanoids and adipokines in breast cancer: from molecular mechanisms to clinical considerations

Chronic inflammation is one of the foremost risk factors for different types of malignancies, including breast cancer. Additional risk factors of this pathology in postmenopausal women are weight gain, obesity, estrogen secretion, and an imbalance in the production of adipokines, such as leptin and adiponectin. Various signaling products of transcription factor, nuclear factor-kappaB, in particular inflammatory eicosanoids, reactive oxygen species (ROS), and cytokines, are thought to be involved in chronic inflammation-induced cancer. Together, these key components have an influence on inflammatory reactions in malignant tissue damage when their levels are deregulated endogenously. Prostaglandins (PGs) are well recognized in inflammation and cancer, and they are solely biosynthesized through cyclooxygenases (COXs) from arachidonic acid. Concurrently, ROS give rise to bioactive isoprostanes from arachidonic acid precursors that are also involved in acute and chronic inflammation, but their specific characteristics in breast cancer are less demonstrated. Higher aromatase activity, a cytochrome P-450 enzyme, is intimately connected to tumor growth in the breast through estrogen synthesis, and is interrelated to COXs that catalyze the formation of both inflammatory and anti-inflammatory PGs such as PGE(2), PGF(2α), PGD(2), and PGJ(2) synchronously under the influence of specific mediators and downstream enzymes. Some of the latter compounds upsurge the intracellular cyclic adenosine monophosphate concentration and appear to be associated with estrogen synthesis. This review discusses the role of COX- and ROS-catalyzed eicosanoids and adipokines in breast cancer, and therefore ranges from their molecular mechanisms to clinical aspects to understand the impact of inflammation.

FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.

Inhibiting delta-6 desaturase activity suppresses tumor growth in mice

Recent studies have shown that a tumor-supportive microenvironment is characterized by high levels of pro-inflammatory and pro-angiogenic eicosanoids derived from omega-6 (n−6) arachidonic acid (AA). Although the metabolic pathways (COX, LOX, and P450) that generate these n−6 AA eicosanoids have been targeted, the role of endogenous AA production in tumorigenesis remains unexplored. Delta-6 desaturase (D6D) is the rate-limiting enzyme responsible for the synthesis of n−6 AA and increased D6D activity can lead to enhanced n−6 AA production. Here, we show that D6D activity is upregulated during melanoma and lung tumor growth and that suppressing D6D activity, either by RNAi knockdown or a specific D6D inhibitor, dramatically reduces tumor growth. Accordingly, the content of AA and AA-derived tumor-promoting metabolites is significantly decreased. Angiogenesis and inflammatory status are also reduced. These results identify D6D as a key factor for tumor growth and as a potential target for cancer therapy and prevention.

The role of stromal myofibroblast and extracellular matrix in tumor angiogenesis

Tumor angiogenesis, the building of blood vessels in an expanding tumor mass, is an elegantly coordinated process that dictates tumor growth and progression. Stromal components of the tumor microenvironment, such as myofibroblasts and the extracellular matrix, collaborate with tumor cells in regulating development. Such myofibroblasts and the extracellular matrix have ever-expanding roles in the angiogenic process as well. This review summarizes how stromal myofibroblasts and the extracellular matrix can modulate tumor angiogenesis, highlighting recent findings.

Notch signaling in developmental and tumor angiogenesis

The discovery that Notch, a key regulator of cell fate determination, is functional in the vasculature has greatly improved our understanding of differentiation and specialization of vessels. Notch signaling has been proven to be critical for arterial specification, sprouting angiogenesis, and vessel maturation. In newly forming vascular sprouts, Notch promotes the distinction between the leading "tip" endothelial cell and the growing "stalk" cell, the endothelial cells that eventually form a new capillary. Notch signaling has also been implicated in vessel stability by regulating vascular mural cell function. More recently, macrophages carrying an activated Notch have been implicated in shaping the course of new sprout formation. Tumor vessels abide by similar principles and use Notch signaling in similar ways. An exciting discovery, made by several researchers, shows that blocking Notch function in tumor vasculature provides a means by which to suppress tumor growth. The authors discuss the developmental and physiological role of Notch in the vasculature and apply this knowledge to an overview of how Notch targeting in the tumor environment can affect tumor angiogenesis and growth.

Anti-inflammatory treatment increases angiogenesis during early fracture healing

OBJECTIVES

Both inflammation and angiogenesis are crucial for normal fracture healing. The goal of this work was to determine how anti-inflammatory treatment affects angiogenesis during early stages of fracture repair.

METHODS

Tibia fractures were created in adult mice and animals were treated with indomethacin (2 mg/kg/day), a non-steroidal anti-inflammatory drug, or PBS once a day beginning from 1 day before fracture and continuing to 6 days after fracture. Animals were killed at 7, 14, and 28 days after injury for histomorphometric analysis of fracture healing. A second group of animals were killed at 3 and 7 days after injury to measure tissue levels of VEGF and interleukin-1 beta (IL-1β). A third group of animals were killed at 3 and 7 days after injury for stereology analysis of macrophage and neutrophil infiltration and tissue vascularization.

RESULTS

Indomethacin significantly decreased bone and cartilage formation at 7 days after fracture compared to controls. Indomethacin decreased the tissue levels of IL-1β at 3 days after fracture but did not affect the recruitment of macrophages or neutrophils to injured limbs. Indomethacin-treated fractures had similar length density and surface density of vasculature as the controls at 3 days after injury. At 7 days after fracture, vasculature in indomethacin-treated fractures exhibited higher length density and surface density than that in controls. By 28 days after injury, indomethacin-treated fractures still exhibited defects in fracture repair.

CONCLUSIONS

Anti-inflammatory treatments using indomethacin impair bone and cartilage formation and increase tissue vascularization in the callus during early fracture healing.

Cancer prevention by targeting angiogenesis

Healthy individuals can harbour microscopic tumours and dysplastic foci in different organs in an undetectable and asymptomatic state for many years. These lesions do not progress in the absence of angiogenesis or inflammation. Targeting both processes before clinical manifestation can prevent tumour growth and progression. Angioprevention is a chemoprevention approach that interrupts the formation of new blood vessels when tumour cell foci are in an indolent state. Many efficacious chemopreventive drugs function by preventing angiogenesis in the tumour microenvironment. Blocking the vascularization of incipient tumours should maintain a dormancy state such that neoplasia or cancer exist without disease. The current limitations of antiangiogenic cancer therapy may well be related to the use of antiangiogenic agents too late in the disease course. In this Review, we suggest mechanisms and strategies for using antiangiogenesis agents in a safe, preventive clinical angioprevention setting, proposing different levels of clinical angioprevention according to risk, and indicate potential drugs to be employed at these levels. Finally, angioprevention may go well beyond cancer in the prevention of a range of chronic disorders where angiogenesis is crucial, including different forms of inflammatory or autoimmune diseases, ocular disorders, and neurodegeneration.

Angiogenesis: a phenomenon which aggravates chronic liver disease progression

It has become increasingly clear that angiogenesis occurring during chronic wound healing and fibrogenesis provides a key contribution to disease progression and complications. The association of fibrogenesis and angiogenesis should be regarded as crucial in the modern evaluation of liver disease progression and in the search for therapeutic targets. Physiological hepatic angiogenesis occurs during liver regeneration, contributing to the formation of new functional sinusoids. Pathological angiogenesis in liver is characterized by intrahepatic vascular remodeling with capillarization of the sinusoids and development of intrahepatic shunts, which lead to increased hepatic resistance and decreased effective hepatocyte perfusion. The problem of angiogenesis in chronic hepatitis C and nonalcoholic fatty liver disease has not been fully resolved. This manuscript briefly describes pathogenesis of new blood vessel formation in chronic hepatitis and potential role of angiogenesis in disease progression.

Midkine acts as proangiogenic cytokine in hypoxia-induced angiogenesis

The cytokine midkine (MK) promotes tumor growth mainly by inducing angiogenesis. Here, we identified the source of MK in the vascular system under hypoxic conditions and demonstrated the relevance of MK during ischemia of normal tissue. Hypoxia increased MK protein expression in human polymorphonuclear neutrophils (PMN), monocytes, and human umbilical vein endothelial cells (HUVEC) compared with normoxia. Immunoelectron microscopy showed elevated cell surface expression of MK in PMN and monocytes during hypoxia. However, only HUVEC released significant amounts of soluble MK during hypoxia compared with normoxia (301 ± 81 pg/ml vs. 158 ± 45 pg/ml; P < 0.05). Exogenous MK induced neovascularization in a chorioallantoic membrane (CAM) assay compared with negative control as measured by counting the number of branching points per visual field (1,074 ± 54 vs. 211 ± 70; P < 0.05). In a hind limb ischemia model, the angiogenic response was almost completely absent in MK-deficient mice, whereas control animals showed a profound angiogenic response measured as proliferating endothelial cells per visual field (45 ± 30 vs. 169 ± 34; P < 0.01). These unanticipated results identified endothelial cells as the source of soluble MK in the vascular system during hypoxia and defined MK as a pivotal player of angiogenesis during ischemia in nonmalignant tissue.

Macrophages and mesenchymal stromal cells support survival and proliferation of multiple myeloma cells

Multiple myeloma (MM) is characterized by almost exclusive tropism of malignant cells for the bone marrow (BM) milieu. The survival and proliferation of malignant plasma cells have been shown to rely on interactions with nonmalignant stromal cells, in particular mesenchymal stromal cells (MSCs), in the BM microenvironment. However, the BM microenvironment is composed of a diverse array of cell types. This study examined the role of macrophages, an abundant component of BM stroma, as a potential niche component that supports malignant plasma cells. We investigated the proliferation of MM tumour cell lines when cultured alone or together with MSCs, macrophages, or a combination of MSCs and macrophages, using the carboxyfluorescein succinimidyl ester assay. Consistently, we observed increased proliferation of MM cell lines in the presence of either MSCs or macrophages compared to cell line-only control. Furthermore, the combined co-culture of MSCs plus macrophages induced the greatest degree of proliferation of myeloma cells. In addition to increased proliferation, MSCs and macrophages decreased the rate of apoptosis of myeloma cells. Our in vitro studies provide evidence that highlights the role of macrophages as a key component of the BM microenvironment facilitating the growth of malignant plasma cells in MM.

Fibroblast growth factor-2 is an important factor that maintains cellular immaturity and contributes to aggressiveness of osteosarcoma

Osteosarcoma is the most frequent, nonhematopoietic, primary malignant tumor of bone. Histopathologically, osteosarcoma is characterized by complex mixtures of different cell types with bone formation. The role of environmental factors in the formation of such a complicated tissue structure as osteosarcoma remains to be elucidated. Here, a newly established murine osteosarcoma model was used to clarify the roles of environmental factors such as fibroblast growth factor-2 (Fgf2) or leukemia-inhibitory factor (Lif) in the maintenance of osteosarcoma cells in an immature state. These factors were highly expressed in tumor environmental stromal cells, rather than in osteosarcoma cells, and they potently suppressed osteogenic differentiation of osteosarcoma cells in vitro and in vivo. Further investigation revealed that the hyperactivation of extracellular signal-regulated kinase (Erk)1/2 induced by these factors affected in the process of osteosarcoma differentiation. In addition, Fgf2 enhanced both proliferation and migratory activity of osteosarcoma cells and modulated the sensitivity of cells to an anticancer drug. The results of the present study suggest that the histology of osteosarcoma tumors which consist of immature tumor cells and pathologic bone formations could be generated dependent on the distribution of such environmental factors. The combined blockade of the signaling pathways of several growth factors, including Fgf2, might be useful in controlling the aggressiveness of osteosarcoma.

Effects of CO(2) pneumoperitoneum on peritoneal macrophage function and peritoneal metastasis in mice with gastric cancer

BACKGROUND

Whether laparoscopy with CO(2) pneumoperitoneum affects the peritoneal metastasis of gastric cancer is a pressing question. In light of the important impact change in peritoneal macrophage function has on the peritoneal metastasis of gastric cancer, this study investigated the change in peritoneal macrophage function in gastric cancer in the CO(2) pneumoperitoneum environment, as well as its effect on the peritoneal metastasis of gastric cancer.

METHODS

An orthotopic transplantation model of murine forestomach carcinoma was established using the 615 mouse line. The mice bearing tumors were randomly divided into four groups (30 mice each group): anesthesia alone, laparotomy, mini-laparotomy, and CO(2) insufflation. After the operation, peritoneal macrophages were collected from 6 mice in each group and cultured. The phagocytosis of neutral red by macrophages and the levels of NO, TNF-α, IL-10, and VEGF produced by macrophages were measured after 12, 24, 48, and 72 h of culture. The remaining mice were observed after 2 weeks for the rate of peritoneal metastasis of forestomach carcinoma cells and the total weight of implanted nodules.

RESULTS

In the laparotomy group, 4 mice died intraoperatively and 2 died in the CO(2) insufflation group. The uptake of neutral red by peritoneal macrophages and the levels of NO, TNF-α, IL-10, and VEGF secreted by peritoneal macrophages in the laparotomy group and mini-laparotomy group after 12 h of culture were all significantly higher than those in the anesthesia-alone group (p < 0.05). The corresponding levels in the CO(2) insufflation group after 12 h were all significantly lower than those in the anesthesia-alone group (p < 0.05). There were no significant differences among the four groups at 24, 48, and 72 h after culture. Comparing with those in the laparotomy group, the uptake of neutral red by peritoneal macrophages and the levels of NO, TNF-α, IL-10, and VEGF secreted by peritoneal macrophages in the CO(2) insufflation group were all significantly lower after 12 h of culture (p < 0.05), but did not differ significantly at 24, 48, and 72 h of culture (p > 0.05), and did not differ significantly in the mini-laparotomy group at all the time (p > 0.05). The rate of peritoneal metastasis of mouse forestomach carcinoma was 50% in the laparotomy group, 45.83% in the mini-laparotomy group, and 45.45% in the CO(2) insufflation group; this difference was not statistically significant (p > 0.05). The total weight of implanted nodules of mouse forestomach carcinoma was 1.02 ± 0.38 g in the laparotomy group, 0.97 ± 0.41 g in the mini-laparotomy group, and 0.93 ± 0.45 g in the CO(2) insufflation group, which was not a statistically significant difference (p > 0.05).

CONCLUSION

CO(2) pneumoperitoneum neither significantly changes the phagocytosis and cytokine secretion functions of peritoneal macrophages in gastric cancer-bearing mice nor significantly promotes peritoneal metastasis of gastric cancer.

Insulin-like growth factor binding protein-4 differentially inhibits growth factor-induced angiogenesis

An in-depth understanding of the molecular and cellular complexity of angiogenesis continues to advance as new stimulators and inhibitors of blood vessel formation are uncovered. Gaining a more complete understanding of the response of blood vessels to both stimulatory and inhibitory molecules will likely contribute to more effective strategies to control pathological angiogenesis. Here, we provide evidence that endothelial cell interactions with structurally altered collagen type IV may suppress the expression of insulin-like growth factor binding protein-4 (IGFBP-4), a well documented inhibitor of the IGF-1/IGF-1R signaling axis. We report for the first time that IGFBP-4 differentially inhibits angiogenesis induced by distinct growth factor signaling pathways as IGFBP-4 inhibited FGF-2- and IGF-1-stimulated angiogenesis but failed to inhibit VEGF-induced angiogenesis. The resistance of VEGF-stimulated angiogenesis to IGFBP-4 inhibition appears to depend on sustained activation of p38 MAPK as blocking its activity restored the anti-angiogenic effects of IGFBP-4 on VEGF-induced blood vessel growth in vivo. These novel findings provide new insight into how blood vessels respond to endogenous inhibitors during angiogenesis stimulated by distinct growth factor signaling pathways.

Regulation of inflammation in cancer by eicosanoids

Inflammation in the tumor microenvironment is now recognized as one of the hallmarks of cancer. Endogenously produced lipid autacoids, locally acting small molecule lipid mediators, play a central role in inflammation and tissue homeostasis, and have recently been implicated in cancer. A well-studied group of autacoid mediators that are the products of arachidonic acid metabolism include: the prostaglandins, leukotrienes, lipoxins and cytochrome P450 (CYP) derived bioactive products. These lipid mediators are collectively referred to as eicosanoids and are generated by distinct enzymatic systems initiated by cyclooxygenases (COX 1 and 2), lipoxygenases (5-LOX, 12-LOX, 15-LOXa, 15-LOXb), and cytochrome P450s, respectively. These pathways are the target of approved drugs for the treatment of inflammation, pain, asthma, allergies, and cardiovascular disorders. Beyond their potent anti-inflammatory and anti-cancer effects, non-steroidal anti-inflammatory drugs (NSAIDs) and COX-2 specific inhibitors have been evaluated in both preclinical tumor models and clinical trials. Eicosanoid biosynthesis and actions can also be directly influenced by nutrients in the diet, as evidenced by the emerging role of omega-3 fatty acids in cancer prevention and treatment. Most research dedicated to using eicosanoids to inhibit tumor-associated inflammation has focused on the COX and LOX pathways. Novel experimental approaches that demonstrate the anti-tumor effects of inhibiting cancer-associated inflammation currently include: eicosanoid receptor antagonism, overexpression of eicosanoid metabolizing enzymes, and the use of endogenous anti-inflammatory lipid mediators. Here we review the actions of eicosanoids on inflammation in the context of tumorigenesis. Eicosanoids may represent a missing link between inflammation and cancer and thus could serve as therapeutic target(s) for inhibiting tumor growth.

Peripheral blood monocyte subsets predict antiviral response in chronic hepatitis C

BACKGROUND

Hepatitis C virus infection evolves into chronic progressive liver disease in a significant percentage of patients. Monocytes constitute a diverse group of myeloid cells that mediate innate and adaptive immune response. In addition to proinflammatory CD16+ monocytes, a Tie-2+ subgroup - Tie-2 expressing monocytes (TEMs) - that has robust proangiogenic potential has been recently defined.

AIM

To study the heterogeneity of peripheral blood monocytes in chronic hepatitis C (CHC) patients and to examine their proposed pathophysiological roles on disease progression and response to antiviral therapy.

METHODS

We studied CD16+ and Tie-2+ peripheral monocyte subpopulations in 21 healthy subjects and 39 CHC patients in various stages of disease and responses to antiviral treatment using flow cytometry. Expression profiles of proangiogenic and tissue remodelling factors in monocyte supernatants were measured using ELISA and protein arrays. Intrahepatic expression of CD14, CD31 and Tie-2 was analysed using immunofluorescence.

RESULTS

Increases of certain peripheral monocyte subsets were observed in the blood of CHC patients, wherein those cells with proinflammatory (CD16+) or proangiogenic (TEMs) potential expanded (P < 0.005, both). Notably, TEMs were significantly increased in nonresponders, particularly those with lower CD16 expression. In addition, many angiogenic factors were differentially expressed by peripheral monocytes from control or CHC patients, such as angiopoietin-1 and angiogenin (P < 0.05). Interestingly, intrahepatic TEMs were distinguished within portal infiltrates of CHC patients.

CONCLUSIONS

These findings suggest for the first time the relevance of peripheral monocytes phenotypes for the achievement of response to treatment. Hence, the study of monocyte subset regulation might effect improved CHC prognoses and adjuvant therapies.

Immunohistochemical expression of vascular endothelial growth factor and matrix metalloproteinase-9 in radicular and residual radicular cysts

Objective

This study assessed and compared the immunoexpression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) in radicular cysts (RCs) and residual radicular cysts (RRCs), relating them to the angiogenic index and the intensity of the inflammatory infiltrate.

Material and Methods

Twenty RCs and 10 RRCs were evaluated by immunohistochemistry using anti-VEGF and anti-MMP-9 antibodies. The angiogenic index was determined by microvessel count (MVC) using anti-von Willebrand factor antibody.

Results

The expression of both VEGF and MMP-9 was higher in RCs than in RRCs. RCs and RRCs presented strong epithelial expression of VEGF, irrespective of the intensity of the inflammatory infiltrate. Lesions with strong expression of MMP-9 showed significantly higher number of immunopositive cells for VEGF (p<0.05) and higher MVC (p<0.05). Lesions with dense inflammatory infiltrate exhibited significantly higher MVC (p<0.05) and higher number of immunopositive cells for VEGF (p<0.05). There was a positive correlation between both MVC (p<0.05) and the quantity of immunopositive cells for VEGF (p<0.05), with intensity of the inflammatory infiltrate. In addition, it was observed a positive correlation between the number of immunopositive cells for VEGF and MVC (p<0.05).

Conclusions

VEGF and MMP-9 might play important roles in the angiogenesis in RCs and RRCs. In these lesions, the expression of these molecules and the MVC is closely related to the intensity of the inflammatory infiltrate. The expression of VEGF in the epithelial lining of RCs and RRCs might be important for the enlargement of these lesions.

Inhibition of B16 murine melanoma metastasis and enhancement of immunity by fever-range whole body hyperthermia

PURPOSE

Whole body hyperthermia (WBH) has been regarded as a promising alternative therapy to cure late stage cancer with metastasis. As the final biological and therapeutic effects are dependent on the specific protocol, the potential of using a microwave-based WBH approach for metastasis inhibition is established and its typical results are discussed.

MATERIALS AND METHODS

The effectiveness of a 30-min whole body hyperthermia (WH) on animals, raised to a rectal temperature of 40.2° ± 0.3°C for 30  min followed by 84 h observation by 2450 MHz microwave irradiation, were evaluated. In an experimental lung metastasis model by injection of B16-F10 melanoma, lungs were removed from sacrificed mice 16 days after tumour implantation, and the expression of heat shock protein, inter-cellular adhesion molecule 1 (ICAM-1), proliferating cell nuclear antigen (PCNA) and cyclin D(1) was examined. CD4(+), CD8(+) and NK cell subpopulation in peripheral blood were measured by flow cytometry before and after the last treatment.

RESULTS

The best therapeutic effect was obtained when the mice were treated with WBH in combination with the initial chemotherapy with cis-diaminodichloroplatinum (CDDP) and dacarbazine (DTIC) (p < 0.05). The WBH alone has an advantage of reduced toxicity and lower cost. Heat shock protein (HSP) expression increased in the hyperthermia groups. Reduction of PCNA and cyclin D(1) was observed in the mice treated with WH alone or in combination with chemotherapy. In the hyperthermia groups, CD4(+)/CD8(+) decreased while the NK increased slightly.

CONCLUSIONS

The whole body hyperthermia protocol described in this work inhibits B16 tumour metastasis by inhibiting cell proliferation, neovascularisation and stimulating favourable immune responses. It demonstrated that WBH treatment benefits therapy of metastasis cancers.

Evaluation of the phenotype pattern of macrophages isolated from malignant and non-malignant pleural effusions

Macrophages are among the infiltrate components of most malignant tumors. Tumor-associated macrophages (TAMs) may secrete a variety of humoral factors, which promote or inhibit tumor growth. In general, depending on their activation pathway, macrophages exhibit two different patterns of phenotype, M1 or M2. It is assumed that TAMs comprise pattern M2. In the malignant pleural effusion, macrophages are a frequent component of cytological evaluation. In this microenvironment, TAMs could be involved in the development of immunity. The phenotype of macrophages represented in malignant and non-malignant pleural effusions is unknown. In this study, macrophages were isolated from 38 pleural effusions (15 malignant and 23 non-malignant) and the expression of a variety of immune mediators and their receptors was assessed to determine the type of activation (M1 vs. M2). The expression of mRNA was analyzed for IL-1β, IL-4, IL-6, IL-10, IL-11, IL-18, TNFα, TGFβ1, IL1R1, IL1RAP, TLR2, TLR4, VLA4, CD62L, MMP2, MMP9, VEGFA, PDGFA, and PDGFB. In immunohistochemical evaluation, the expressions of CD68, mesothelin, MAC387, IL-1β, IL-6, IL-10, IL-12, TNFα, and CD105 were assessed. The cytoplasmic expression of IFNγ, TNFα, IL-6, and IL-10 and the surface expression of CD11a, CD14, CD15, CD16, CD23, CD25, CD45, CD54, CD62L, CD69, VLA2, VLA3, VLA4, VLA6, TLR2, TLR4, and CCR7 were tested using flow cytometry. In supernatants from macrophages cultures, TNFα, IL-1β, IL-6, IL-8, IL-10, IL-12, MCP1, and VEGF were investigated by cytometric beads array method (CBA flex sets) and TGFβ1 by ELISA. Our results indicate that macrophages from malignant and non-malignant pleural effusions differ from each other and suggest that macrophages isolated from non-malignant effusions show a pattern comparable to M1 while those isolated from malignant effusions express similarity to M2 phenotype, but they have not shown a classical M2 pattern.

Macrophage polarization in the maculae of age-related macular degeneration: a pilot study

Macrophages can be polarized to exhibit either pro-inflammatory M1 or pro-angiogenic M2 phenotypes, but have high phenotypic plasticity. This pilot study investigated macrophage polarization in the macular retina and choroid of age-related macular degeneration (AMD) and non-AMD subjects, as well as in AMD choroidal neovascular membranes (CNVM). All specimens were evaluated for routine histopathology. Quantitative real-time polymerase chain reaction for representative M1 (CXCL11) and M2 (CCL22) transcripts were performed on macular choroidal trephines (MCT) of 19 AMD and nine non-AMD eye bank eyes, on the microdissected macular retinal cells from the archived slides of five geographic atrophic AMD, five exudative/neovascular AMD, and eight normal autopsied eyes, and on microdissected inflammatory cells from two surgically removed CNVM that did not respond to anti-vascular endothelial growth factor (VEGF) therapy. High M2-chemokine transcript and a low ratio of M1 to M2 chemokine transcript were found in aging non-AMD MCT. Advanced AMD maculae had a higher M1 to M2 chemokine transcript ratio compared to normal autopsied eyes. Macrophages in the two CNVM of patients unresponsive to anti-VEGF therapy were polarized toward either M1 or M2 phenotypes. The number of M2 macrophages was increased compared to M1 macrophages in normal aging eyes. A pathological shift of macrophage polarization may play a potential role in AMD pathogenesis.

Control of leucocyte differentiation from embryonic stem cells upon vasculogenesis and confrontation with tumour tissue

Embryonic stem (ES) cells spontaneously differentiate capillary-like structures as well as leucocytes such as monocytes/macrophages, neutrophils, natural killer (NK) cells and cytototoxic T lymphocytes. The interplay between vasculogenesis and leucocyte differentiation as well as the population of tumour tissues with ES cell-derived leucocytes and endothelial cells is, however, not sufficiently specified. In the present study, gene expression of the cell surface markers CD68 and CD14 (expressed on monocytes and macrophages), Mac-1 (CD11b) (expressed on granulocytes, monocytes and NK cells) and CD16 (expressed on neutrophils) was investigated in murine CGR8 ES cells in relation to the endothelial cell markers CD31 and vascular endothelial (VE)-cadherin. Expression of leucocyte markers increased from day 7–8 of cell culture on. Furthermore, addition of macrophage colony-stimulating factor to the cell culture medium resulted in a threefold increase in the number of CD68⁺ monocytes/macrophages. Treatment of embryoid bodies with lipopolysaccharide (LPS) up-regulated CD14 thus suggesting functionality of the CD14 LPS receptor. Differentiation of vascular structures positive for CD31 and VE-cadherin preceded leucocyte differentiation by 2 days (i.e. from day 5–6 on) suggesting that vasculogenesis may be a determinant of leucocyte differentiation. Consequently the Flk-1 antagonist SU5416 which inhibits vasculogenesis of ES cells significantly blunted leucocyte differentiation. Confrontation culture of embryoid bodies with multicellular breast tumour spheroids initiated significant increase of leucocyte cell numbers and invasion of leucocytes into the tumour tissue. In summary our data demonstrate that during ES cell differentiation vasculogenesis precedes leucocyte differentiation, and point towards the direction that leucocyte cell invasion into tumour tissue may initiate the pro-inflammatory microenvironment necessary for tumour vascularization.

Biology of metastatic renal cell carcinoma

In the past ten years we have made exceptional progresses in the understanding of RCC biology, particularly by recognizing the crucial pathogenetic role of activation of the HIF/VEGF and mTOR pathways. This has resulted in the successful clinical development of anti-angiogenic and mTOR-targeted drugs, which have profoundly impacted on the natural history of the disease and have improved the duration and quality of RCC patient lives. However, further improvements are still greatly needed: 1) even in patients who obtain striking clinical responses early in the course of treatment, disease will ultimately escape control and progress to a treatment-resistant state, leading to therapeutic failure; 2) prolonged disease control usually requires 'continuous' treatment, even across different treatment lines, making the impact of chronic, low-grade, toxicities on quality of life greater and precluding, for most patients, the possibility of experiencing 'drug-free holidays'; 3) although we have successfully identified classes of drugs (or molecular mechanisms of action) that are effective in a substantial proportion of patients, we still fall short of molecular predictive factors that identify individual patients who will (or will not) benefit from a specific intervention and still proceed on a trial-and-error basis, far from a truly 'personalized' therapeutic approach; 4) finally (and perhaps most importantly), even in the best case scenario, currently available treatments inevitably fail to definitively 'cure' metastatic RCC patients. In this review we briefly summarize recent developments in the understanding of the molecular pathogenesis of RCC, the development of resistance/escape mechanisms, the rationale for sequencing agents with different mechanisms of action, and the importance of host-related factors. Unraveling the complex mechanisms by which RCC shapes host microenvironment and immune response and therapeutic treatments, in turn, shape both cancer cell biology and tumor-host interactions may hold the key to future advances in such a complex and challenging disease.

Myeloid angiogenic cells act as alternative M2 macrophages and modulate angiogenesis through interleukin-8

Endothelial progenitor cells (EPCs) promote angiogenesis, and clinical trials have shown such cell therapy to be feasible for treating ischemic disease. However, clinical outcomes have been contradictory owing to the diverse range of EPC types used. We recently characterized two EPC subtypes, and identified outgrowth endothelial cells as the only EPC type with true progenitor and endothelial characteristics. By contrast, myeloid angiogenic cells (MACs) were shown to be monocytic cells without endothelial characteristics despite being widely described as "EPCs." In the current study we demonstrated that although MACs do not become endothelial cells or directly incorporate into a microvascular network, they can significantly induce endothelial tube formation in vitro and vascular repair in vivo. MAC-derived interleukin-8 (IL-8) was identified as a key paracrine factor, and blockade of IL-8 but not vascular endothelial growth factor (VEGF) prevented MAC-induced angiogenesis. Extracellular IL-8 transactivates VEGFR2 and induces phosphorylation of extracellular signal-regulated kinases. Further transcriptomic and immunophenotypic analysis indicates that MACs represent alternative activated M2 macrophages. Our findings demonstrate an unequivocal role for MACs in angiogenesis, which is linked to paracrine release of cytokines such as IL-8. We also show, for the first time, the true identity of these cells as alternative M2 macrophages with proangiogenic, antiinflammatory and pro-tissue-repair properties.

Hox transcription factor regulation of adult bone-marrow-derived cell behaviour during tissue repair and regeneration

INTRODUCTION

Bone marrow offers a valuable source of stem/progenitor cells that contribute to the repair of injured tissues. Failure in the function of these cells results in delayed or reduced tissue repair. Identification of factors that can correct these defects is critical to treating the underlying dysfunction. Notably, homeobox (Hox) transcription factors have been identified as having significant effects on BMDC behaviour, including differentiation, migration and adhesion in injured tissue, and may provide a basis for future therapies.

AREAS COVERED

Hox protein regulation of bone-marrow-derived cell (BMDC) differentiation, factors that influence BMDC behaviour in response to injury, the effects of the diabetic environment on BMDCs, methods that can be used to reprogramme BMDCs, and the use of Hox transcription factors to correct BMDC behaviour.

EXPERT OPINION

Hox gene therapy has been successfully employed to change cell behaviour using ex vivo 'reprogramming' strategies overexpressing selected Hox genes in BMDCs to direct the fate of these cells to the desired cell type, promoting tissue repair.

Role of tyrosine kinase inhibitors in tumor immunology

Various immune cells are involved in both innate and acquired immunity against tumors. NK cells and cytotoxic T lymphocytes play a role as effector cells to directly kill tumor cells. On the other hand, antigen-presenting cells, particularly dendritic cells, control tumor-specific immune responses. In addition, much focus has been paid on the immune regulatory cells in tumor sites, including CD4(+)CD25(+) regulatory T cells and myeloid-derived suppressor cells. The recent advances in molecular-targeted therapy for cancer have provided small-molecule kinase inhibitors, which are effective for several hematopoietic malignancies as well as solid tumors in the clinical setting. Most drugs generally have inhibitory effects on several kinases, including tyrosine kinases, which are critical molecules for the survival, proliferation, migration and invasion of tumor cells. Since the host immune surveillance against tumors affects tumor progression, it is of interest to understand how these molecular-targeted drugs affect immune function in the tumor-bearing host. Besides this, there are emerging findings that myeloid cells could be involved in tumor angiogenesis. In this article, we address the role of tyrosine kinase inhibitors in tumor immunology by summarizing their effects on myeloid cells, such as antigen-presenting cells and regulatory cells, and their role in tumor immunity and angiogenesis.

Identification and validation of SRC and phospho-SRC family proteins in circulating mononuclear cells as novel biomarkers for pancreatic cancer

There is an urgent need to develop novel markers of pancreatic cancer to facilitate early diagnosis. Pancreatic carcinoma is characterized by marked stroma formation with a high number of infiltrating tumor-associated macrophages (TAMs) that originate from circulating mononuclear cells (MNCs). We hypothesized that differential analysis of protein expression and phosphorylation in circulating MNCs from healthy nude mice and nude mice bearing orthotopic human pancreatic cancer would identify a surrogate marker of pancreatic cancer. These differences were analyzed by two-dimensional gel electrophoresis followed by Western blot analysis using antibody against phosphorylated tyrosine proteins (pY). Protein and phosphorylated protein spots of interest were identified by mass spectrometry and validated by Western blot analysis as candidate markers for pancreatic cancer. We found that the expression and phosphorylation of Src family proteins were significantly higher in circulating MNCs from mice bearing pancreatic cancer than in circulating MNCs from healthy mice. TAMs in mice with pancreatic tumors also had higher Src family protein expression and phosphorylation than resident macrophages in the pancreas of healthy mice. The expression and phosphorylation of Src family proteins were correlated with tumor weight; however, increased Src expression and phosphorylation also occurred in MNCs from mice with chronic pancreatitis. This is the first report to explore novel pancreatic tumor markers in circulating MNCs. Although the specificity of the marker for pancreatic cancer was low, it could be used to monitor the disease or to select high-risk patients with chronic pancreatitis.

Characteristics of human Ewing/PNET sarcoma models

Ewing/PNET (peripheral neuroepithelioma) tumors are rare aggressive bone sarcomas occurring in young people. Rare-disease clinical trials can require global collaborations and many years. In vivo models that as accurately as possible reflect the clinical disease are helpful in selecting therapeutics with the most promise of positive clinical impact. Human Ewing/PNET sarcoma cell lines developed over the past 45 years are described. Several of these have undergone genetic analysis and have been confirmed to be those of Ewing/PNET sarcoma. The A673 Ewing sarcoma line has proven to be particularly useful in understanding the biology of this disease in the mouse. The chromosomal translocation producing the EWS/FLI1 fusion transcript characterizes clinical Ewing sarcoma. Cell lines that express this genetic profile are confirmed to be those of Ewing sarcoma. The A673 Ewing sarcoma line grows in culture and as a xenograft in immunodeficient mice. The A673 model has been used to study Ewing sarcoma angiogenesis and response to antiangiogenic agents. Many Ewing sarcoma clinical specimens express the cell surface protein endosialin. Several Ewing sarcoma cell lines, including the A673 line, also express cell surface endosialin when grown as subcutaneous tumor nodules and as disseminated disease; thus the A673 is a useful model for the study of endosialin biology and endosialin-directed therapies. With the advent of tools that allow characterization of clinical disease to facilitate optimal treatment, it becomes imperative, especially for rare tumors, to develop preclinical models reflecting disease subsets. Ewing PNET sarcomas are a rare disease where models are available.

Corticosteroids modulate angiogenic soluble factors in ulcerative colitis patients

AIMS

The aim of this study was to compare angiogenic factors in serum levels of active ulcerative colitis (UC) patients and in healthy controls, and to analyze these angiogenic levels depending on the achievement of remission after oral corticosteroid treatment throughout treatment, and according to the Truelove-Witts activity index.

METHODS

Blood samples were collected from 13 patients receiving oral corticosteroids for treatment of UC flares at three different intervals--baseline, during, and after treatment--and from 26 healthy controls. Vascular endothelial growth factor (VEGF), placental growth factor (PlGF), VEGF receptor 1 (VEGFR1), angiopoietins (Ang) 1 and 2, and its receptor Tie2 were assayed by ELISA.

RESULTS

While VEGF and Ang2 levels in UC patients were higher than in healthy controls (P < 0.05), UC patients showed lower levels of Ang1 than healthy individuals (P < 0.05). In UC patients who achieved clinical remission after corticosteroid treatment, a statistically significant higher baseline serum level of PlGF was observed (22 ± 5 vs. 18 ± 2; P < 0.05). Angiogenic factor levels varied during treatment; however, they did not show a statistically significant correlation to the activity of the disease.

CONCLUSIONS

VEGF, Ang1, and Ang2 levels showed statistically significant differences between UC patients and healthy controls. Although determination of PlGF serum levels before corticosteroid treatment might be helpful to anticipate the response by UC patients, no angiogenic pattern that could accurately predict "a priori" this response to corticosteroid treatment was observed. Corticosteroids altered temporarily circulating levels of VEGF, angiopoietins and Tie2. No correlation was found between systemic levels of angiogenic factors and the clinical activity of UC.

Angiogenesis and parasitic helminth-associated neovascularization

Successful metazoan parasitism, among many other factors, requires a supply of nutrients and the removal of waste products. There is a prerequisite for a parasite-defined vasculature. The angiogenic mechanism(s) involved presumably depend on the characteristics of the tissue- and vascular system-dwelling, parasitic helminths. Simplistically, 2 possibilities or a combination of both have been considered in this review. The multifactorial induction of parasitic helminth-associated neovascularization could arise through, either a host-, a parasite- or a host-/parasite-dependent, angiogenic switch. Most studies appear to support the first and third hypotheses, but evidence exists for the intrahepatic cestodeEchinococcus multilocularis, the free-living nematodeCaenorhabditis elegansand the intravascular trematodeSchistosoma mansonifor the second inference. In contrast, the nematode anti-coagulant protein NAPc2 from adultAncylostoma caninumis also an anti-angiogenic factor.

Regulation of endothelial cell functions by basement membrane- and arachidonic acid-derived products

Angiogenesis, the formation of new blood vessels from preexisting vasculature, is required for normal physiological as well as pathological events. The angiogenic process requires endothelial cells to proliferate, migrate, and undergo tubulogenesis. These multistep processes necessitate secretion of pro-angiogenic growth factors, activation of specific intracellular signaling, and interaction of endothelial cells with basement membrane (BM) extracellular matrix components. The generation and release of angiogenic molecules are highly regulated and are influenced by numerous factors, including BM-derived fragments, proteolytic enzymes, as well as metabolites of arachidonic acid (AA). The interactions between these key modulators of angiogenesis is extremely complex, as AA metabolites can regulate the synthesis of soluble angiogenic factors, BM components, as well as enzymes capable of cleaving BM components, which result in the generation of pro- and/or anti-angiogenic products. Furthermore, some BM-derived fragments can alter the expression of AA-converting enzymes and consequently the synthesis of angiogenic factors. In this review we describe the relationship between BM components and AA metabolites with respect to the regulation of endothelial cell functions in health and disease.

Cross-talk between tumor and myeloid cells: how to tip the balance in favor of antitumor immunity

Myeloid differentiation is often disturbed in cancer, leading to reduced frequencies of immunostimulatory dendritic cells and an over-representation of immunosuppressive immature myeloid cells, granulocytes and macrophages. As a result of this skewed myeloid differentiation, a highly immunosuppressive myeloid subset becomes prevalent during cancer development; these myeloid-derived suppressor cells are also recruited as a collateral to certain protumorigenic inflammatory processes, resulting in an effective downregulation of T-cell-mediated immune surveillance and antitumor immunity. In this article, some of the important myeloid cell subsets and mediators involved in cancer-related immune suppression are reviewed. Furthermore, cross-talk between tumors and the myeloid compartment, and ways in which it can suppress effective cell-mediated immunity, are discussed, as well as possible therapeutic approaches to tip the balance in favor of antitumor immunity.

Pulmonary dendritic cells in lungs of preterm infants: neglected participants in bronchopulmonary dysplasia?

Preterm infants are at risk for bronchopulmonary dysplasia (BPD), a chronic lung disease characterized by disrupted alveolar remodeling and microvascular dysangiogenesis. The pathogenesis of BPD is multifactorial, with contributions from antenatal and/or postnatal infection and inflammation. The potential role of dendritic cells, critical immune regulatory cells with potent angiogenic activities, remains undetermined. We studied the prevalence and topography of dendritic cells in postmortem lungs of short- and long-term ventilated preterm infants born between 23 and 29 weeks in gestation. Controls were age-matched infants who had lived less than 12 hours. Dendritic cells were identified by anti-DC-SIGN immunohistochemistry and were co-localized with endothelial and smooth muscle cells by double immunofluorescence. Lungs of early and late control infants without evidence of antenatal infection contained scattered DC-SIGN-positive dendritic cells in the peripheral lung parenchyma. Lungs of early control infants with a history of chorioamnionitis/antenatal infection and lungs of short- or long-term ventilated preterm infants showed a dramatic (more than 3-fold) increase in dendritic cells. Double labeling highlighted a close association between dendritic cells and small- or medium-sized pulmonary vessels. In conclusion, we demonstrated that dendritic cells are an integral component of normal postcanalicular lung development. Antenatal infection and ventilation/BPD are associated with significant pulmonary recruitment of dendritic cells. The recently described angiogenic effects of dendritic cells and their intimate association with the pulmonary microvasculature indicate that dendritic cells may participate in BPD-associated dysangiogenesis. Elucidation of the role of this immunovascular axis may lead to novel therapeutic approaches to BPD.

Angiogenesis is present in experimental autoimmune encephalomyelitis and pro-angiogenic factors are increased in multiple sclerosis lesions

Background

Angiogenesis is a common finding in chronic inflammatory diseases; however, its role in multiple sclerosis (MS) is unclear. Central nervous system lesions from both MS and experimental autoimmune encephalomyelitis (EAE), the animal model of MS, contain T cells, macrophages and activated glia, which can produce pro-angiogenic factors. Previous EAE studies have demonstrated an increase in blood vessels, but differences between the different phases of disease have not been reported. Therefore we examined angiogenic promoting factors in MS and EAE lesions to determine if there were changes in blood vessel density at different stages of EAE.

Methods

In this series of experiments we used a combination of vascular casting, VEGF ELISA and immunohistochemistry to examine angiogenesis in experimental autoimmune encephalomyelitis (EAE). Using immunohistochemistry we also examined chronic active MS lesions for angiogenic factors.

Results

Vascular casting and histological examination of the spinal cord and brain of rats with EAE demonstrated that the density of patent blood vessels increased in the lumbar spinal cord during the relapse phase of the disease (p < 0.05). We found an increased expression of VEGF by inflammatory cells and a decrease in the recently described angiogenesis inhibitor meteorin. Examination of chronic active human MS tissues demonstrated glial expression of VEGF and glial and blood vessel expression of the pro-angiogenic receptor VEGFR2. There was a decreased expression of VEGFR1 in the lesions compared to normal white matter.

Conclusions

These findings reveal that angiogenesis is intimately involved in the progression of EAE and may have a role in MS.

Atu027 prevents pulmonary metastasis in experimental and spontaneous mouse metastasis models

PURPOSE

Atu027, a novel RNA interference therapeutic, has been shown to inhibit lymph node metastasis in orthotopic prostate cancer mouse models. The aim of this study is to elucidate the pharmacologic activity of Atu027 in inhibiting hematogenous metastasis to the target organ lung in four different preclinical mouse models.

EXPERIMENTAL DESIGN

Atu027 compared with vehicle or control small interfering RNA lipoplexes was tested in two experimental lung metastasis models (Lewis lung carcinoma, B16V) and spontaneous metastasis mouse models (MDA-MB-435, MDA-MB-231, mammary fat pad). Different dosing schedules (repeated low volume tail vein injections) were applied to obtain insight into effective Atu027 treatment. Primary tumor growth and lung metastasis were measured, and tissues were analyzed by immunohistochemistry and histology. In vitro studies in human umbilical vein endothelial cells were carried out to provide an insight into molecular changes on depletion of PKN3, in support of efficacy results.

RESULTS

Intravenous administration of Atu027 prevents pulmonary metastasis. In particular, formation of spontaneous lung metastasis was significantly inhibited in animals with large tumor grafts as well as in mice with resected primary mammary fat pad tumors. In addition, we provide evidence that an increase in VE-cadherin protein levels as a downstream result of PKN3 target gene inhibition may change endothelial function, resulting in reduced colonization and micrometastasis formation.

CONCLUSION

Atu027 can be considered as a potent drug for preventing lung metastasis formation, which might be suitable for preventing hematogenous metastasis in addition to standard cancer therapy.

Reperfusion of chronic tissue ischemia: nitrite and dipyridamole regulation of innate immune responses

Chronic and intermittent ischemic vascular disorders represent a burgeoning clinical challenge. Previous studies have focused on the idea that therapeutic angiogenesis strategies could alleviate tissue ischemia; however, it is now appreciated that vascular disease is not simply limited to vascular wall cells but also influenced by simultaneously occurring inflammatory responses. Our laboratory has discovered that pharmacological treatment of permanent tissue ischemia with dipyridamole significantly augments ischemic tissue reperfusion, angiogenesis, and arteriogenesis over time. We have found that the beneficial effects of dipyridamole therapy are due to its ability to increase tissue nitric oxide bioavailability that corrects tissue redox imbalance. Importantly, we have also discovered that dipyridamole treatment invoking nitric oxide (NO) production significantly downregulates various innate immune response genes during chronic ischemic tissue injury. These findings demonstrate that dipyridamole-induced production of nitrite/NO significantly decreases inflammatory responses while increasing vascular growth in ischemic tissues.

The tumor microenvironment of colorectal cancer: stromal TLR-4 expression as a potential prognostic marker

Background

Colorectal cancer can be efficiently treated when found at early stages, thus the search for novel markers is of paramount importance. Since inflammation is associated with cancer progression and angiogenesis, we investigated expression of cytokines like IL-6 and other mediators that play a key role in the innate immune system, in particular toll like receptor 4 (TLR4), in the microenvironment of lesions from different stages of colon disease progression, from ulcerative colitis to adenoma and adenocarcinoma to find useful markers.

Methods

The presence of inflammatory cells and expression of key cytokines involved in the inflammation process were quantified by immunohistochemistry in specific tissue compartments (epithelial, stromal, endothelial) by immunohistochemistry. A murine azoxymethane/dextran sulfate model in which Tir8, a negative regulator of the inflammatory response, was ablated was used to confirm the clinical observations. 116 Archival tissue samples from patients with different stages of colorectal disease: 13 cases of ulcerative colitis (UC), 34 tubular or tubulo-villous adenomas (AD), and 53 infiltrating adenocarcinomas. 16 specimens of healthy mucosa surgically removed with the cancerous tissue were used as a control.

Results

The differences between healthy tissues and the diverse lesions was characterized by a marked inflammatory-angiogenic reaction, with significantly (P < 0.05) higher numbers of CD68, CD15, and CD31 expressing cells in all diseased tissues that correlated with increasing grade of malignancy. We noted down-regulation of a potential modulator molecule, Hepatocyte Growth Factor, in all diseased tissues (P < 0.05). TLR-4 and IL6 expression in the tumor microenvironment were associated with adenocarcinoma in human samples and in the murine model. We found that adenocarcinoma patients (pT1-4) with higher TLR-4 expression in stromal compartment had a significantly increased risk in disease progression. In those patients with a diagnosis of pT3 (33 cases) colon cancer, those with very high levels of TLR-4 in the tumor stroma relapsed significantly earlier than those with lower expression levels.

Conclusions

These data suggest that high TLR-4 expression in the tumor microenvironment represents a possible marker of disease progression in colon cancer.

Co-evolution of cancer microenvironment reveals distinctive patterns of gastric cancer invasion: laboratory evidence and clinical significance

Background

Cancer invasion results from constant interactions between cancer cells and their microenvironment. Major components of the cancer microenvironment are stromal cells, infiltrating inflammatory cells, collagens, matrix metalloproteinases (MMP) and newly formed blood vessels. This study was to determine the roles of MMP-9, MMP-2, type IV collagen, infiltrating macrophages and tumor microvessels in gastric cancer (GC) invasion and their clinico-pathological significance.

Methods

Paraffin-embedded tissue sections from 37 GC patients were studied by Streptavidin-Peroxidase (SP) immunohistochemical technique to determine the levels of MMP-2, MMP-9, type IV collagen, macrophages infiltration and microvessel density (MVD). Different invasion patterns were delineated and their correlation with major clinico-pathological information was explored.

Results

MMP2 expression was higher in malignant gland compared to normal gland, especially nearby the basement membrane (BM). High densities of macrophages at the interface of cancer nests and stroma were found where BM integrity was destroyed. MMP2 expression was significantly increased in cases with recurrence and distant metastasis (P = 0.047 and 0.048, respectively). Infiltrating macrophages were correlated with serosa invasion (P = 0.011) and TNM stage (P = 0.001). MVD was higher in type IV collagen negative group compared to type IV collagen positive group (P = 0.026). MVD was related to infiltrating macrophages density (P = 0.040). Patients with negative MMP9 expression had better overall survival (OS) compared to those with positive MMP9 expression (Median OS 44.0 vs 13.5 mo, P = 0.036). Median OS was significantly longer in type IV collagen positive group than negative group (Median OS 25.5 vs 10.0 mo, P = 0.044). The cumulative OS rate was higher in low macrophages density group than in high macrophages density group (median OS 40.5 vs 13.0 mo, P = 0.056). Median OS was significantly longer in low MVD group than high MVD group (median OS 39.0 vs 8.5 mo, P = 0.001). The difference of disease-free survival (DFS) between low MVD group and high MVD group was not statistically significant (P = 0.260). Four typical patterns of cancer invasion were identified based on histological study of the cancer tissue, including Washing pattern, Ameba-like pattern, Spindle pattern and Linear pattern.

Conclusions

Proteolytic enzymes MMP9, MMP2 and macrophages in stroma contribute to GC progression by facilitating the angiogenesis. Cancer invasion patterns may help predict GC metastasis.