FOXP3 and neoplasm: Similar to the research of Calcinotto et al., whose study showed that extracellular microenvironment acidification (pH, 6.0–6.5) has a negative effect on the function of human and mammalian tumor-infiltrating T cells, resulting in a decrease in its anti-tumor ability (36), our data also demonstrated that acidic microenvironment in HIRI downregulates the iTreg function and Foxp3 expression and promotes apoptosis of iTregs.