ABSTRACT: To compare tumor associated macrophage (TAM) from naïve and sepsis surviving mice we have employed Agilent microarrays slides with almost 60,000 genes (39,430 mRNA and 16,251 long non coding RNAs). Other experiments we conducted demonstrated TAM accumulation was increased in post-sepsis subjects. For this reason, we asked if TAM from post-sepsis mice could also exhibit a different gene expression profile. Sepsis was induced by cecal and ligation puncture. Naïve mice were used as control group. All animals were treated with ertapenem (20 mg/kg, i.p., 6 hours after surgery, and then each 12 hours for 3 days). B16-F10 melanoma (30,000 cells) were injected subcutaneously at day 14 after sepsis induction. Fourteen days after tumor inoculation, animals were killed and tumors were harvested and digested (collagenase and DNAse). TAM was isolated by a Percoll gradient (70/30) followed by a 1-hour adhesion protocol, reaching a purity of ~75%. For comparative reasons, we assessed TAM from post-sepsis (n = 4), TAM from naïve mice (n = 4), bone marrow derived macrophage from naïve (n = 4) and from post-sepsis (n = 4), M1-polarized macrophage (n = 4) and M2-polarized macrophage (n = 4). We found only minor gene expression differences between TAM from naïve and from post-sepsis mice (61 genes were up-regulated and 98 genes were down-regulated, fold-change > 0.58 or < -0.58, and p < 0.01). We found genes related to leukocyte activation were down-regulated in TAM from post-sepsis mice (e.g. Ccr7, Cd86, H2-Ab1), as well as genes related to antigen processing and presentation of peptide or polysaccharide antigen via MHC class II (H2-DMb1, Cd74, H2-Eb1, H2-Ob). A gene related to M2 polarization was up-regulated (Marco). Also, we found a down-regulation of Nfkbid in post-sepsis-derived TAM. This led us to hypothesize TAM from post-sepsis mice exhibit a more M2-like phenotype, which may in part contribute to post-sepsis tumor expansion.
