GDF15 and escherichia coli infection: The results showed that at 0.5 h of E. coli infection, the colony count of macrophages in the GDF15 treatment group was significantly higher than that of the PBS treatment group (P < 0.05), that is, the phagocytic function of macrophages in the GDF15 treatment group was higher than that of the PBS treatment group; at the same time, we also observed the sterilization ratio of the GDF15 treatment group was much higher than that of the PBS treatment group, indicating that the macrophages of the GDF15 treatment group had stronger bactericidal function (Figure 12).