Role of MDSCs in SLE is still controversial
MDSCs are the myeloid precursors of dendritic cells, macrophages, and granulocytes 81, 82. They play a regulatory role81, 83, 84 in the immune system by suppressing T cell proliferation 82, secreting regulatory cytokines85, and inducing T cell apoptosis86. Recent research has indicated that MDSCs can enhance the expansion of the regulatory B cells, both in vivo andin vitro 87. However, the role that MDSCs play in SLE has not yet been thoroughly deciphered.
Some researchers believe that MDSCs can promote the progression of lupus, based on the evidence that MDSCs accumulate in many organs in SLE and chronic inflammation conditions 88. MDSCs have been shown to significantly decrease the differentiation of CD4+ T cells to Th1 and to suppress the secretion of TNF-α, IL-6, and IFN-γ83. Simultaneously, when accumulated, MDSCs have the potential to differentiate into macrophage and dendritic cells, in response to inflammatory cytokines, such as TNF-α, IL-6, and IFN-γ89, 90; these have been found to be significantly increased in SLE 91. Macrophage and dendritic cells have also been regarded to positively contribute to the pathogenesis of SLE 92, 93. Previous research has also demonstrated that the transfer of MDSCs into lupus mice significantly ameliorates the symptoms of SLE, including preventing autoantibody secretion and relieving renal tissue injuries87. Simultaneously, the infusion of MDSCs has been shown to decrease follicular helper T cells, Th1 cells, and Th17 cells in the spleens of lupus mice. MDSCs have also been found to enhance the expansion of the regulatory B cells and their frequency via inducible nitric oxide synthase 87.