Consist with the decreased proportion of M2 macrophages, the CD206 expression in tumor by immunostaining and the mRNA levels of representative M2 genes (Arginase1, CD206, Trem2 and Ym1) by qPCR were also markedly down-regulated in colonic tumors of H. pylori-infected CAC mice (Fig 4B–4D). This evidence concerns the gene TREM2 and colonic neoplasm.