RESEARCH ARTICLE Differential Contribution of Acute and Chronic Inflammation to the Development of

Based on the notion that inflammation favors tumorigenesis, our experiments comparatively assessed the influence of acute and chronic inflammation on the development of a murine mammary tumor (4T1). In addition, we characterized angiogenic and inflammatory markers in the tumor tissue and systemically. Subcutaneous implantation of polyether-polyurethane sponge discs in Balb/c mice was used to host 4T1 tumor cells (1x106), which were inoculated intraimplant 24h or 10 days post implantation. Flow cytometric analysis of enzyme-digested implants revealed that, after 24 hours, the population of leukocytes was primarily characterized by neutrophils (42.53 % +/- 8.45) andmonocytes (37.53 % +/- 7.48), with some lymphocytes (16.27 % +/- 4.0) and a few dendritic cells (1.82 % +/- 0.36). At 10 days, macrophages were predominant (37.10 % +/- 4.54), followed by lymphocytes (28.1 % +/- 4.77), and monocytes (22.33 % +/- 3.05), with some dendritic cells (13.60 % +/- 0.55) and neutrophils (11.07 % +/-2.27). A mammary tumor grown in a chronic inflammatory environment was 2-fold when com-pared with one grown in acute inflammation and 5-fold when compared with tumor alone. The levels of pro-angiogenic cytokine (VEGF-Vascular Endothelial Growth Factor) were higher i