ARG1 and neoplasm: In H22 tumor-bearing mice, Met@MPs significantly enhanced the protein expression of CD80 and CD86 (M1-related markers), while decreased the mRNA expression of Arg1, Mrc1 and Mgl1, and protein expression of CD206 (M2-related markers).Meanwhile, the targeted macrophages effectively reconstituted the anti-tumor immune microenvironment by reducing the number of Tregs and MDSCs in tumor tissue and increasing the recruitment of CD8+ T cells.