hPMSCs protects against aging-induced oxidative damage of CD4+ T cells through activating Akt-mediated Nrf2 antioxidant signaling

Background: Mesenchymal stem cells (MSCs) was considered as regenerative therapeutic approach in both acute and chronic diseases. However, whether MSCs regulate the antioxidant metabolism of CD4+ T cells and weaken immunosenescence remains unclear. Here, we reported the protective effects of hPMSCs in aging-related CD4+ T cell senescence and identified the underlying mechanisms using a D-gal induced mouse aging model.Methods: In vivo study, 40 male C57BL/6 mice (8 weeks) were randomly divided into four groups: control group, D-gal group, hPMSC group and PBS group. In in vitro experiment, human naive CD4+ T (CD4CD45RA) cells were prepared using a naive CD4+ T cell isolation kit II and pretreated with the Akt inhibitor LY294002 and Nrf2 inhibitor ML385. Then, isolated naive CD4+ T cell were cocultured with hPMSCs for 72 h in the absence or presence of anti-CD3/CD28 Dynabeads and IL-2 as a mitogenic stimulus. Intracellular ROS changes were detected by flow cytometry. The activities of the antioxidant enzymes superoxide dismutase, glutathione peroxidase and catalase were measured by colorimetric analysis. The senescent T cells were detected SA-β-gal stain. The expression of aging related proteins were detected by Western blotting, RT-PCR and confocal microscopy.Results: We found that hPMSC treatment markedly decreased the ROS level, SA-β-gal positive cells number, senescence-associated secretory phenotype (IL-6 and OPN) expression and aging-related protein (P16 and P21) expression in senescent CD4+ T cells. Furthermore, hPMSC treatment effectively upregulated Nrf2 nuclear translocation and the expression of downstream target genes (HO-1, CAT, GCLC and NQO1) in senescent CD4+ T cells. Moreover, in vitro studies revealed that hPMSCs attenuated CD4+ T cell senescence by upregulating the Akt/GSK-3β/Fyn pathway to activate Nrf2 functions. Conversely, the antioxidant effects of hPMSCs were blocked by the Akt inhibitor LY294002 and Nrf2 inhibitor ML385 in senescent CD4+ T cells.Conclusions: Our results indicate that hPMSCs attenuate D-gal induced CD4+ T cell senescence by activating Nrf2-mediated antioxidant defenses and that upregulation of Nrf2 by hPMSCs is regulated via the Akt/GSK-3β/Fyn pathway.