Perl Andras, Hanczko Robert, Lai Zhi-Wei, Oaks Zachary, Kelly Ryan, Borsuk Rebecca, Asara John M, Phillips Paul E
Division of Rheumatology, Department of Medicine, College of Medicine, Upstate Medical University, State University of New York, Syracuse, NY 13210 USA ; Department of Microbiology and Immunology, College of Medicine, Upstate Medical University, State University of New York, 750 East Adams Street, Syracuse, NY 13210 USA ; Department of Biochemistry and Molecular Biology, College of Medicine, Upstate Medical University, State University of New York, Syracuse, NY 13210 USA.
Division of Rheumatology, Department of Medicine, College of Medicine, Upstate Medical University, State University of New York, Syracuse, NY 13210 USA.
Metabolomics. 2015;11(5):1157-1174. doi: 10.1007/s11306-015-0772-0. Epub 2015 Jan 20.
Systemic lupus erythematosus (SLE) patients exhibit depletion of the intracellular antioxidant glutathione and downstream activation of the metabolic sensor, mechanistic target of rapamycin (mTOR). Since reversal of glutathione depletion by the amino acid precursor, -acetylcysteine (NAC), is therapeutic in SLE, its mechanism of impact on the metabolome was examined within the context of a double-blind placebo-controlled trial. Quantitative metabolome profiling of peripheral blood lymphocytes (PBL) was performed in 36 SLE patients and 42 healthy controls matched for age, gender, and ethnicity of patients using mass spectrometry that covers all major metabolic pathways. mTOR activity was assessed by western blot and flow cytometry. Metabolome changes in lupus PBL affected 27 of 80 KEGG pathways at FDR p < 0.05 with most prominent impact on the pentose phosphate pathway (PPP). While cysteine was depleted, cystine, kynurenine, cytosine, and dCTP were the most increased metabolites. Area under the receiver operating characteristic curve (AUC) logistic regression approach identified kynurenine (AUC = 0.859), dCTP (AUC = 0.762), and methionine sulfoxide (AUC = 0.708), as top predictors of SLE. Kynurenine was the top predictor of NAC effect in SLE (AUC = 0.851). NAC treatment significantly reduced kynurenine levels relative to placebo in vivo (raw p = 2.8 × 10, FDR corrected p = 6.6 × 10). Kynurenine stimulated mTOR activity in healthy control PBL in vitro. Metabolome changes in lupus PBL reveal a dominant impact on the PPP that reflect greater demand for nucleotides and oxidative stress. The PPP-connected and NAC-responsive accumulation of kynurenine and its stimulation of mTOR are identified as novel metabolic checkpoints in lupus pathogenesis.
系统性红斑狼疮（SLE）患者表现出细胞内抗氧化剂谷胱甘肽耗竭以及代谢传感器雷帕霉素作用靶点（mTOR）的下游激活。由于氨基酸前体N - 乙酰半胱氨酸（NAC）逆转谷胱甘肽耗竭对SLE具有治疗作用，因此在双盲安慰剂对照试验的背景下研究了其对代谢组的影响机制。使用涵盖所有主要代谢途径的质谱法，对36例SLE患者以及42例在年龄、性别和种族上与患者匹配的健康对照者的外周血淋巴细胞（PBL）进行了定量代谢组分析。通过蛋白质免疫印迹法和流式细胞术评估mTOR活性。狼疮PBL中的代谢组变化在FDR p < 0.05时影响了80条KEGG通路中的27条，对磷酸戊糖途径（PPP）影响最为显著。虽然半胱氨酸减少，但胱氨酸、犬尿氨酸、胞嘧啶和脱氧胞苷三磷酸（dCTP）是增加最多的代谢物。受试者工作特征曲线（AUC）逻辑回归方法确定犬尿氨酸（AUC = 0.859）、dCTP（AUC = 0.762）和甲硫氨酸亚砜（AUC = 0.708）是SLE的顶级预测指标。犬尿氨酸是SLE中NAC效应的顶级预测指标（AUC = 0.851）。在体内，相对于安慰剂，NAC治疗显著降低了犬尿氨酸水平（原始p = 2.8×10，FDR校正p = 6.6×10）。犬尿氨酸在体外刺激健康对照PBL中的mTOR活性。狼疮PBL中的代谢组变化揭示了对PPP的主要影响，这反映了对核苷酸的更大需求和氧化应激。犬尿氨酸与PPP相关且对NAC有反应的积累及其对mTOR的刺激被确定为狼疮发病机制中的新型代谢检查点。
