Distinct types of tumors exhibit differential grade of inflammation and angiogenesis in mice.

Inflammation, angiogenesis and cytokine production are common features of almost, if not all tumors. However, the extent of these processes induced by different types of tumors has not been evaluated. We investigated the growth pattern of the experimental metastatic tumors, B16F10 melanoma, CT26.WT colon and 4T1 mammary cells inoculated in the flank of syngeneic mice and determined the degree of inflammation, angiogenesis, and production level of pro-inflammatory and pro-angiogenic cytokines within the tumors. In addition, we have analyzed vascular changes in the interface between the tumors and the adjacent cutaneous tissue and levels of relevant pro-inflammatory and pro-angiogenic cytokines systemically. The weight of tumors 15 days post-inoculation of 10(6) cells was markedly different. Melanomas were 2 and 10-fold heavier than colon and mammary tumors, respectively. Locally, CT26.WT tumor cells induced more vessels in cutaneous tissue adjacent to the tumors but systemically, the plasma levels of VEGF were higher (approximately 2-fold) in 4T1 tumor-bearing mice compared with the other two tumors. Mammary tumors presented the most prominent inflammatory content as assessed by a range of markers (inflammatory enzymes and cytokines). The vascular index, as determined by the intra-tumor amount of hemoglobin and number of vessels in hot spot areas, was also higher (approximately 2-fold) in melanomas compared with the other two tumors. These findings showing that distinct tumor types determine differential grade of inflammation, angiogenesis and host interaction in mice may provide new insights to tailor differential therapeutic approach based on the status of tumor biomarkers.

Kint3-4 promotes apoptosis and inhibition of angiogenesis in solid Ehrlich Tumor / Kint3-4 promove apoptose e inibição da angiogênese no tumor sólido de Ehrlich

A proteína Kint3-4 (PKint3-4), codificadora da angiostatina, é reconhecida por sua potencialidade antiangiogênica. O presente estudo teve como objetivo avaliar o efeito da proteína Kint3-4 no crescimento do tumor sólido de Ehrlich. Para isso, foram analisados a curva de desenvolvimento tumoral, o índice apoptótico e a dosagem de hemoglobina, a fim de se avaliar a angiogênese, em 20 camundongos Swiss fêmeas, inoculadas com o tumor sólido de Ehrlich em seus coxins plantares. Os resultados demonstraram a participação de PKint3-4 na indução à apoptose de células neoplásicas, na diminuição da concentração de hemoglobina e, principalmente, na diminuição do desenvolvimento tumoral. Sugere-se que a ação antitumoral, determinada pela sequência proteica utilizada, possa estar associada ao papel antiangiogênico da angiostatina, que indiretamente aumentaria o índice apoptótico das células neoplásicas, e/ou a uma ação direta da proteína Kint3-4 sobre essas células, estimulando-as a sofrerem apoptose.

Mast cells and angiogenesis in canine mammary tumor / Mastócitos e angiogênese nos tumores mamários caninos

The correlation between microvessel density and mast cells density in canine mammary tumors was studied. Sixty-five samples of canine mammary tumors, being 24 benign and 41 malignant, were analyzed. The routine Toluidine Blue staining method was used to assess the mast cells. To evaluate angiogenesis, the immunohistochemical expression of CD31 was assessed. There was no significant difference in either mast cells (P=0.44) or microvessel density (P=0.77) between malignant and benign tumors. A positive correlation was observed between microvessel density and mast cells (r=0.39; P=0.011) in malignant tumors. These results suggest that mast cells may play a role in canine mammary malignant tumors development, promoting angiogenesis, similar to some tumors described in the human species.

Estimou-se a correlação entre a densidade de microvasos e a densidade de mastócitos em tumores mamários caninos. Sessenta e cinco amostras de tumores mamários caninos - 24 benignos e 41 malignos - foram analisadas, pela técnica rotineira de coloração com Azul de Toluidina para avaliação da densidade de mastócitos. Para a avaliação da angiogênese, foi utilizada a técnica de imunoistoquímica para expressão de CD31. Não foram observadas diferenças significativas de mastócitos (P=0.44) ou densidade microvascular (P=0.77) entre tumores malignos e benignos. A correlação entre densidade microvascular e densidade de mastócitos foi positiva (r=0,39; P=0,011) em tumores malignos. Estes resultados sugerem que os mastócitos podem exercer um importante papel no desenvolvimento de tumores mamários malignos caninos mediante promoção da angiogênese, similarmente a alguns tumores descritos na espécie humana.

Tumor growth, angiogenesis and inflammation in mice lacking receptors for platelet activating factor (PAF).

Tumor growth is associated with angiogenesis and inflammation and the endogenous lipid, platelet activating factor (PAF), is a pro-inflammatory and pro-angiogenic mediator. We therefore measured tumor growth, angiogenesis and inflammation in normal (WT) mice and those lacking the receptor for PAF, through gene deletion (PAFR-KO). Growth of solid tumors derived from colon 26 cells was not altered but that from Ehrlich cells was markedly (5-fold) increased in the PAFR-KO mice, relative to the WT strain. Angiogenesis, as tumor content of VEGF or hemoglobin, was increased in both tumors from the mutant strain. Inflammation, as neutrophil and macrophage accumulation and chemokine (CXCL2 and CCL2) content of tumors, was decreased or unchanged in the tumors implying an overall decrease in the inflammatory response in the PAFR-KO strain. We also assessed growth of the Ehrlich tumor in its ascites form, after i.p. injection. Here growth (ascites volume) was inhibited by about 30%, but neutrophil and macrophage numbers were increased in the ascites fluid from the PAFR-KO mice. Angiogenesis in the peritoneal wall, which is not invaded by the tumor cells, was increased but leukocyte infiltration decreased in the mutant strain. Our results show, unexpectedly, that tumor-induced angiogenesis was increased in mice lacking response to PAF, from which we infer that in normal (WT) mice, PAF is anti-angiogenic. Further, although growth was still associated with angiogenesis in PAFR-KO mice, growth was not correlated with inflammation (leukocyte accumulation).

Cellular proliferation, differentiation and apoptosis in polyether-polyurethane sponge implant model in mice.

The integration of implanted material to host organism requires spatial and temporal organization of several cellular processes, such as proliferation, differentiation and apoptosis. Despite the clinical relevance of these processes, there is little information regarding the sequence of such events in synthetic matrices. Here, we present a combination of techniques used to characterize the fibrovascular response in subcutaneous polyether-polyurethane sponge implants in mice at days 4, 7, 10 and 14 postimplantation. The AgNOR technique was modified and used as a surrogate marker for proliferating and activated cells invading the implant. The number of AgNOR-stained cells increased progressively from day 4 (606+/-76) to day 14 (2146+/-71) postimplantation. The number of TUNEL-positive (apoptotic index) cells also increased progressively from day 4 (459+/-40) to day 14 (1157+/-119) postimplantation. However, the ratio of TUNEL-labeled/proliferating cells had its highest peak in the early phase of the process remaining stable until day 14. Using Picrosirius staining it was shown that thin collagen increased from day 4, peaking at day 10 and falling markedly at day 14, whereas dense collagen increased progressively during the whole period. These experiments hold potential to investigate not only distinct phases of tissue repair induced by synthetic matrices but also to study underlying mechanisms involved.

Angiogenesis and inflammation in skeletal muscle in response to ascites tumor in mice.

This study addresses the interaction between Ehrlich ascites tumor and skeletal abdominal muscle, presenting quantitative analysis of ascites-induced angiogenesis and inflammation in this tissue of mice bearing-tumor. Time-dependent changes in the muscle (cellular activity, angiogenesis, inflammation and cytokines production) were assessed by morphometric, functional, and biochemical parameters at days 1, 4 and 8 after i.p. inoculation of Ehrlich tumor cells (2.5 x 10(7)). The number of cells stained with AgNOR technique (argyrophilic nucleolar organizer region) in the muscle, together with MTS assay used as markers of cellular activity increased progressively in parallel with the out flow rate of sodium fluorescein (blood flow index), hemoglobin content (vascular index) and VEGF production. Likewise, the inflammatory process in the muscle, as assessed by myeloperoxidase (MPO) and n-acethylglucosaminidase (NAG) activities and the levels of the chemokines, keratinocyte-derived chemokine (CXC1-3/KC) and macrophage-chemoattractant protein (CCL2/MCP-1) increased with tumor development. The combination of techniques used to describe angiogenesis and inflammation in a muscle model system has proved to be suited for quantitative measurements of microvascular changes and cellular infiltration occurring in the abdominal muscle wall of ascites-bearing mice. This study holds potential for investigating events and mechanisms associated with skeletal muscle response to neoplasic stimulus.

Murine chemokine CXCL2/KC is a surrogate marker for angiogenic activity in the inflammatory granulation tissue.

OBJECTIVES: A wide range of compounds inhibit formation of new blood vessels in a variety of models, accompanied by decreases in pro-angiogenic cytokines. The authors sought a surrogate marker for the complex process of neovascularization by correlating inhibition of cytokine production with anti-angiogenic effect. METHODS: Three anti-angiogenic compounds, clotrimazole (120 mg kg(-1) day(-1)), thalidomide (100 mg kg(-1) day(-1)), and rosiglitazone (10 mg kg(-1) day(-1)), were used to inhibit angiogenesis developing over 9 days, in sponges implanted subcutaneously in Swiss mice. Angiogenesis was assessed by hemoglobin content and by histology. Content of cytokines in implants was measured by specific immunoassays and accumulation of neutrophils or macrophages in implants by measuring myeloperoxidase or N-acetylglucosaminidase activity, respectively. RESULTS: These compounds caused equal inhibition of angiogenesis (about 40%). However, implant levels of vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF-alpha) or the macrophage chemoattractant cytokine, CCL2/MCP-1/JE, and accumulation of macrophages were more variably inhibited. Only the neutrophil chemokine, CXCL2/KC, was inhibited equally by the three compounds, in this model. CONCLUSIONS: Anti-angiogenic effect was most clearly and closely correlated with levels of the chemokine KC. Thus, measurement of the chemokine KC might provide an adequate surrogate marker for the functional process of neovascularization in our model.

Inhibition of inflammatory angiogenesis by distant subcutaneous tumor in mice.

We investigated angiogenesis, inflammatory cells accumulation and endogenous production of cytokines in sponge implants of tumor-bearing mice. Seven days after inoculation of Ehrlich tumor cells (2.5 x 10(6)), sponge discs were implanted subcutaneously in the dorsa of mice to induce the formation of fibrovascular tissue. The implants of tumor-bearing and non tumor-bearing animals were assessed for neovascularization and leukocyte accumulation, together with levels of relevant cytokines, vascular endothelial growth factor VEGF), tumor necrosis factor alpha (TNF-alpha), CXCL1-3/KC and CCL2/JE. In the implants of tumor-bearing animals angiogenesis (assessed by hemoglobin content and VEGF levels in the implants) and leukocyte accumulation (assessed by myeloperoxidase -MPO- and N- acetylglucosaminidase-NAG-enzyme activities) were all significantly less than those in the implants of non tumor-bearing animals. Although the chemokine CXCL1-3/KC was lower in the implants of tumor-bearing animals, the chemokine CCL2/JE was increased in this group. The production of TNF-alpha in the implants was not modified by the presence of the subcutaneous tumor. The combination of the methodologies used in this study has provided a novel approach to investigate the interaction between two distinct proliferating tissues that share common features (angiogenesis, cell recruitment, inflammation) and has shown that the predominant inhibitory effect of a tumor mass over repair process is associated with altered cytokine production.

Vasodilator effect of angiotensin-(1-7) in mature and sponge-induced neovasculature.

Angiotensin-(1-7) (Ang-(1-7)), a peptide constituent of the renin-angiotensin system, has been shown to act as a vasodilator mediator in pre-existing (skin) and newly formed vasculatures (14-day-old sponge implants). Blood flow was determined by the outflow rate of sodium fluorescein applied intradermally or intraimplant and the results were expressed in t(1/2) values (time taken for the fluorescence to reach 50% of the peak in the systemic circulation). We showed that the t(1/2) value was significantly lower (4.1+/-0.46) in the implants compared with the cutaneous vasculature (5.7+/-0.5). Ang-(1-7) 20 ng was able to decrease t(1/2) values in both vasculatures. The specific receptor antagonist, D-Ala7-Ang-(1-7) (A-779), prevented Ang-(1-7)-induced vasodilation and altered the basal vascular tone of the implants. The vasodilator effect was also abolished by nitric oxide (NO) synthase inhibitors in both vasculatures and by indomethacin in the implant. Selective AT(1) and AT(2) receptor antagonists did not alter the vasodilation induced by the peptide. These results establish the vasodilator effect of Ang-(1-7) in the cutaneous and implant vasculature and that the peptide is produced endogenously by the fibrovascular tissue, and suggest that this peptide contributes for the vasodilation found in newly formed vascular beds (wound healing, chronic inflammatory processes and tumors).