Myeloid-derived suppressor cells (MDSCs) are pathologically activated and relatively immature myeloid cells that have been implicated in the immunological regulation of many pathologic conditions. Phenotypically and morphologically, MDSCs are similar to neutrophils (PMN-MDSCs) and monocytes (M-MDSCs). However, they have potent suppressive activity and distinct gene expression profiles and biochemical characteristics. No or very few MDSCs are observed in steady-state physiological conditions. Therefore, until recently, accumulation of MDSCs was considered a consequence of pathological processes or pregnancy. Here, we report that MDSCs with a potent ability to suppress T cells are present during the first weeks of life in mice and humans. MDSC suppressive activity was triggered by lactoferrin and mediated by nitric oxide, PGE2, and S100A9 and S100A8 proteins. MDSCs from newborns had a transcriptome similar to that of tumor MDSCs, but with strong upregulation of an antimicrobial gene network, and had potent antibacterial activity. MDSCs played a critical role in control of experimental necrotizing enterocolitis (NEC) in newborn mice. MDSCs in infants with very low weight, who are prone to NEC, had lower MDSC levels and suppressive activity than did infants with normal weight. Thus, the transitory presence of MDSCs may be critical for regulation of inflammation in newborns.

中文翻译：

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新生儿中骨髓来源的抑制细胞的短暂存在对于控制炎症至关重要。

髓样来源的抑制细胞（MDSC）是经过病理激活的且相对不成熟的髓样细胞，已参与许多病理状况的免疫调节。在表型和形态上，MDSC与嗜中性粒细胞（PMN-MDSC）和单核细胞（M-MDSC）相似。但是，它们具有强大的抑制活性，并具有独特的基因表达谱和生化特征。在稳态生理条件下没有观察到MDSC，或者只有很少MDSCs。因此，直到最近，MDSC的积累仍被认为是病理过程或妊娠的结果。在这里，我们报告说，在小鼠和人类生命的最初几周内，存在具有抑制T细胞的强大能力的MDSC。MDSC抑制活性由乳铁蛋白触发，并由一氧化氮PGE2介导，以及S100A9和S100A8蛋白。新生儿的MDSC的转录组与肿瘤MDSC的相似，但抗菌基因网络的上调很强，并且具有强大的抗菌活性。MDSC在新生小鼠实验性坏死性小肠结肠炎（NEC）的控制中起着关键作用。与体重正常的婴儿相比，极轻的婴儿容易发生NEC，MDSC的MDSC水平和抑制活性较低。因此，MDSC的短暂存在对于调节新生儿的炎症可能至关重要。与体重正常的婴儿相比，极轻的婴儿容易发生NEC，MDSC的MDSC水平和抑制活性较低。因此，MDSC的短暂存在对于调节新生儿的炎症可能至关重要。与体重正常的婴儿相比，极轻的婴儿容易发生NEC，MDSC的MDSC水平和抑制活性较低。因此，MDSC的短暂存在对于调节新生儿的炎症可能至关重要。