Background: Decompensated cirrhosis patients are more prone to bacterial infections. Myeloid-derived suppressor cells (MDSCs) expand in sepsis patients and disrupt immune cell functions. Granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy helps in restoring immune cell functions and resolving infections. Its role in MDSC modulation in cirrhosis with sepsis is not well understood. Methods: A total of 164 decompensated cirrhotic-62 without (w/o), 72 with sepsis, and 30 with sepsis treated with GM-CSF-and 15 healthy were studied. High-dimensional flow cytometry was performed to analyze MDSCs, monocytes, neutrophils, CD4 T cells, and Tregs at admission and on days 3 and day 7. Ex vivo co-cultured MDSCs with T cells were assessed for proliferation and apoptosis of T cells and differentiation to Tregs. Plasma factors and mRNA levels were analyzed by cytokine-bead assay and qRT-PCR. Results: Frequencies of MDSCs and Tregs were significantly increased (p = 0.011 and p = 0.02) with decreased CD4 T cells (p = 0.01) in sepsis than w/o sepsis and healthy controls (HCs) (p = 0.000, p = 0.07, and p = 0.01) at day 0 and day 7. In sepsis patients, MDSCs had increased IL-10, Arg1, and iNOS mRNA levels (p = 0.016, p = 0.043, and p = 0.045). Ex vivo co-cultured MDSCs with T cells drove T-cell apoptosis (p = 0.03, p = 0.03) with decreased T-cell proliferation and enhanced FOXP3+ expression (p = 0.044 and p = 0.043) in sepsis compared to w/o sepsis at day 0. Moreover, blocking the MDSCs with inhibitors suppressed FOXP3 expression. GM-CSF treatment in sepsis patients significantly decreased MDSCs and FOXP3+ Tregs but increased CD4 T-cell functionality and improved survival. Conclusion: MDSCs have an immunosuppressive function by expanding FOXP3+ Tregs and inhibiting CD4+ T-cell proliferation in sepsis. GM-CSF treatment suppressed MDSCs, improved T-cell functionality, and reduced Tregs in circulation.Keywords: GM-CSF; Tregs; immune modulation; liver cirrhosis; myeloid-derived suppressor cells; sepsis.

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乐备实（上海优宁维生物科技股份有限公司旗下全资子公司），是国内专注于提供高质量蛋白检测以及组学分析服务的实验服务专家，自2018年成立以来，乐备实不断寻求突破，公司的服务技术平台已扩展到单细胞测序、空间多组学、流式检测、超敏电化学发光、Luminex多因子检测、抗体芯片、PCR Array、ELISA、Elispot、PLA蛋白互作、多色免疫组化、DSP空间多组学等30多个，建立起了一套涵盖基因、蛋白、细胞以及组织水平实验的完整检测体系。

 
我们可提供从样本运输、储存管理、样本制备、样本检测到检测数据分析的全流程服务。凭借严格的实验室管理流程、标准化实验室操作、原始数据储存体系以及实验项目管理系统，已经为超过3000家客户单位提供服务，年检测样本超过100万，受到了广大客户的信任与支持。