Fig. 8.

Summary of hPMSC-mediated PD-1 expression on CD4⁺IL-10⁺ T cells and mitigation of liver damage in GVHD model mice. The oxidative stress aggravated during GVHD and indirectly induced by the imbalance in the percentage of CD4⁺IL-10⁺T cells and the expression of PD-1 on CD4⁺IL-10⁺T cells. These factors elicited the inflammatory and redox response in the GVHD liver and resulted in the occurrence of liver damage. The hPMSCs can enhance Nrf2 activation and attenuate the activation of NF-κB, which reduces the oxidative stress and increase the percentage of CD4⁺IL-10⁺T cells by suppressing the CD4⁺IL-10⁺T cell apoptosis induced by PD-1 in CD4⁺IL-10⁺T cells. Both effects reduce the inflammatory and redox responses, further alleviating the liver damage observed in GVHD mice