目的: 探讨脓毒症小鼠髓源性抑制细胞(myeloid-derived suppressor cells, MDSCs)氨基酸代谢组学特点。方法: 采用盲肠结扎穿孔术(cecal ligation and puncture, CLP)制备脓毒症小鼠模型，将小鼠随机分为假手术组(sham组, n = 10)和CLP组(n = 10)。术后第7天在各组存活小鼠中随机选取5只，分离小鼠骨髓MDSCs，采用安捷伦Seahorse XF技术测量MDSCs细胞的氧气消耗速率(oxygen consumption rate, OCR)，采用超高效液相色谱-串联质谱联用技术靶向检测细胞内氨基酸及寡肽含量。通过单维和多维检验分析差异代谢物和潜在生物标志物，并对潜在生物标志物进行通路富集分析。结果: CLP组小鼠骨髓中MDSCs比例(75.53% ± 6.02%)显著大于sham组的MDSCs比例(43.15% ± 7.42%, t = 7.582, P < 0.001)，且CLP组小鼠骨髓中MDSCs的基础呼吸速率[(50.03±1.20) pmol/min]、最大呼吸速率[(78.07±2.57) pmol/min]和腺嘌呤核苷三磷酸(adenosine triphosphate, ATP)产生[(25.30±1.21) pmol/min]均显著大于sham组的基础呼吸速率[(34.53±0.96) pmol/min, (t = 17.41, P < 0.001)]、最大呼吸速率[(42.57±1.87) pmol/min, (t = 19.33, P < 0.001)]和ATP产生[(12.63±0.96) pmol/min, (t = 14.18, P < 0.001)]。亮氨酸、苏氨酸、甘氨酸等17种氨基酸含量显著增加(均P < 0.05)，是脓毒症MDSCs的潜在生物标志物。增加的氨基酸主要富集在苹果酸-天冬氨酸穿梭、氨回收、丙氨酸代谢、谷胱甘肽代谢、苯丙氨酸和酪氨酸代谢、尿素循环、甘氨酸和丝氨酸代谢、β-丙氨酸代谢、谷氨酸代谢、精氨酸和脯氨酸代谢等代谢途径。结论: CLP组小鼠MDSCs中线粒体氧化磷酸化增强，苹果酸-天冬氨酸穿梭和丙氨酸代谢增强，可能为线粒体有氧呼吸提供大量原料，从而促进MDSCs发挥免疫抑制功能，阻断上述代谢途径或将有助于调节MDSCs功能，为改善脓毒症预后提供新思路。

Objective: To explore the amino acid metabolomics characteristics of myeloid-derived suppressor cells (MDSCs) in mice with sepsis induced by the cecal ligation and puncture (CLP). Methods: The sepsis mouse model was prepared by CLP, and the mice were randomly divided into a sham operation group (sham group, n = 10) and a CLP model group (n = 10). On the 7th day after the operation, 5 mice were randomly selected from the surviving mice in each group, and the bone marrow MDSCs of the mice were isolated. Bone marrow MDSCs were separated to measure the oxygen consumption rate (OCR) by using Agilent Seahorse XF technology and to detect the contents of intracellular amino acids and oligopeptides through ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) technology. Different metabolites and potential biomarkers were analyzed by univariate statistical analysis and multivariate statistical analysis. The major metabolic pathways were enriched using the small molecular pathway database (SMPDB). Results: The proportion of MDSCs in the bone marrow of CLP group mice (75.53% ± 6.02%) was significantly greater than that of the sham group (43.15%± 7.42%, t = 7.582, P < 0.001), and the basal respiratory rate [(50.03±1.20) pmol/min], maximum respiration rate [(78.07±2.57) pmol/min] and adenosine triphosphate (ATP) production [(25.30±1.21) pmol/min] of MDSCs in the bone marrow of CLP group mice were significantly greater than the basal respiration rate [(34.53±0.96) pmol/min, (t = 17.41, P < 0.001)], maximum respiration rate [(42.57±1.87) pmol/min, (t = 19.33, P < 0.001)], and ATP production [(12.63±0.96) pmol/min, (t = 14.18, P < 0.001)] of sham group. Leucine, threonine, glycine, etc. were potential biomarkers of septic MDSCs (all P < 0.05). The increased amino acids were mainly enriched in metabolic pathways, such as malate-aspartate shuttle, ammonia recovery, alanine metabolism, glutathione metabolism, phenylalanine and tyrosine metabolism, urea cycle, glycine and serine metabolism, β-alanine metabolism, glutamate metabolism, arginine and proline metabolism. Conclusion: The enhanced mitochondrial oxidative phosphorylation, malate-aspartate shuttle and alanine metabolism in MDSCs of CLP mice may provide raw materials for mitochondrial aerobic respiration, thereby promoting the immunosuppressive function of MDSCs. Blocking the above metabolic pathways may reduce the risk of secondary infection in sepsis and improve the prognosis.