Exosomal HSP70 Mediates Immunosuppressive Activity Of The Myeloid-Derived Suppressor Cells Via Phosphorylationof Stat3

Objective:To investigate the effects of exosomes derived from Renca cell on the expansion and activation of MDSCs and explore the mechanismMethods:Exosomes derived from Renca cells were separated and purified by sucrose gradient centrifugation. The morphology and component of the exosomes were analyzed by Electron microscopy and Western blotting respectively; MDSCs proportion was detected with Flow cytometry; VEGF and IL-6 produced in culture supernatants was quantified with ELISA kits. The changes of mRNA and protein expressions of ARG-1 and iNOS were examined by RT-PCR and Western blotting, the changes in the protein expression of p-Stat3,TLR2 and MyD88 were detected by Western blotting.Results:Exosomes were successfully purified by sucrose gradient centrifugation. Compared with the control cells, MDSCs treated by the exosomal Hsp70(E-Hsp70) showed enhanced expansion and activation. E-Hsp70 treatment upregulated ARG-1 and iNOS mRNA and protein expression, the quantity of IL-6 and VEGF in the serum was significantly higher than the control cells. When E-Hsp70were added, upregulated the expression of p-Stat3 and MyD88.Conclusion:Exosomes derived from Renca cells can promote the expansion and activation of MDSCs. Further studies are required to investigate the potential of exosomes applied for effective new targets for the Renal cell carcinoma treatment.