ABSTRACT
Objective To investigate the effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the generation of human myeloid derived suppressor cells (MDSCs) relied on peripheral blood monocytes,and to establish efficient induction system in vitro of MDSCs.Methods Kidney transplantation recipients between January and March 2017 were included in this study.Purified CD14 + cells isolated from peripheral blood were cultured in the presence of GM-CSF with different concentrations for 7 days.Phenotypes and immunosuppressive abilities of induced MDSCs (iMDSCs) were investigated with FACS analyses.Inducible nitric oxide synthase (iNOS) mRNA expression was detected by qRT-PCR to determine the influence of iNOS-pathway on the immunosuppressive abilities of iMDSCs.Results A total of 11 recipients were included in this study.HLA-DR expression decreased sharply after the culture with GM-CSF.iMDSCs showed the similar phenotype characteristics with monocytic-MDSCs (M-MDSCs) as well as significant ability to suppress T cells proliferation and cytokines production.iMDSCs expressed higher levels of iNOS than monocytes,and the inhibitor effects of iMDSCs were significantly reduced after treatment with L-NMMA (1 mmol/L).The variations of phenotype and suppressive ability were concentrationdependent,and more significant changes could be revealed in the group of 10 μg/L GM-CSF.Conclusion GM-CSF-treated peripheral blood monocytes can be efficiently transformed to M-MDSCs,and suppress T cells proliferation and cytokines secretion via iNOS-dependent pathway.These results may contribute to establish MDSCs induction system,which would provide a basis for the clinical application of MDSCs.
ABSTRACT
Objective To investigate the effects of commonly used inductive agents on peripheral blood monocytic myeloid-derived suppressor cells (M-MDSCs) in renal transplantation recipients and to discuss their possible mechanism.Methods The enrolled patients received rabbit anti-thymocyte globulin (rATG) or basiliximab for induction therapy,with the maintenance immunosuppressive regimen of tacrolimus,mycophenolate mofetil and steroid.The number of CD11 b + CD33 + HLA-DR-CD14 + CD1 5-M-MDSCs and cytokine levels in peripheral blood,including interferon-γ(IFN-γ),interleukin-2 (IL-2),IL-4 and IL-6,were measured by flow cytometry before and 1 week,2 weeks,1 month,2 months,3 months after operation.Results A total of 47 recipients (29 given rATG 29,and 18 given basiliximab) were included in this study.Compared to the patients with basiliximab,asignificant increase in the frequency of M-MDSCs was observed in the rATG group at 2nd month after operation (5.5％ ± 2.8％ vs.3.8％ ± 1.6％,P＜0.001) and at 3rd month after operation (7.0 ％ ± 3.1％vs.4.1％ ± 2.3 ％,P＜ 0.001),while there was no significant difference in the cell number between the two groups.In the cytokine detection,levels of IL-2 and IL-4 in the rATG-treated recipients were significantly higher at 2nd weekpostoperation (Pr2 =0.032,and PIL-4 =0.019)and 1st month postoperation (PIL-2 =0.024,PIL-4 ＜0.001) than the basiliximab group.Conclusions ATG promotes the expansion of M-MDSCs,which is associated with the secretion of IL-2 and IL-4 due to the lymphocytes depletion.The synergistic immunosuppressive effect may contribute to the induction of immune tolerance.