The phenotype of macrophages can influence their expression of costimulatory molecules (CD80 and CD86) or inhibitory molecules, including CTLA4, which regulates T cells' activation.[24] Besides, genes expressed on the surface of macrophages, including CD163, TLR9, and MHC II, inflammatory factors including IL‐1β, IL12B, and IL10RA, chemokines (CXCL11, CXCL14, CXCL10, CCL17, CCL22, CCL19, CCL5, CCL8, and CXCL9), and the metalloprotease MMP9, were significantly upregulated in the E. coli group, suggesting that E. coli infection can induce macrophage polarization (Figure 2E). Here, MMP9 is linked to escherichia coli infection.