N-Acetylcysteine and Milk Thistle for Treatment of Diabetic Nephropathy

氧化应激和谷胱甘肽（GSH）失衡是糖尿病肾病发病机制的主要因素。循环单核细胞参与这一过程，因为这些细胞携带高氧化负荷，并在糖尿病肾组织中发现。目前治疗糖尿病肾病的氧化应激的选择是有限的，只有部分有效，因此在新的策略的发展兴趣很高。N-乙酰半胱氨酸（NAC）和奶蓟（MTh）植物黄酮木脂素是具有互补抗氧化特性的营养补充剂。这两种补充剂都能够直接中和有毒的自由基，但更重要的是，NAC是细胞内产生GSH的底物，MTh黄酮木脂素是参与GSH代谢的许多细胞酶的诱导剂，包括GSH还原酶（GSH-R），GSH过氧化物酶（GSH-Px），GSH-S-转移酶（GST）和超氧化物歧化酶（SOD）。 我们建议联合口服补充NAC和MTh黄酮木脂素将减少蛋白尿和氧化应激和炎症的泌尿和全身表现，这是2型糖尿病（T2 DM）和相关肾病患者的特征性观察。我们希望这些效果能够以最小或无副作用的方式实现，并且具有良好的患者耐受性。为了检验这一假设，我们提出了一项双盲、随机、安慰剂对照、五组初步研究，其中包括在患有T2 DM和已确诊肾病的患者中进行的剂量范围研究。干预将包括单独和联合口服一种水平的NAC和两种水平的MTh黄酮木脂素或安慰剂三个月。干预组为：（A）安慰剂;（B）NAC 600 mg BID;（C）Siliphos 480 mg BID;（D）NAC 600 mg BID + Siliphos 480 mg BID;和（E）NAC 600 mg BID + Siliphos 960 mg BID。主要的结果指标是尿白蛋白排泄，这是肾小球损伤的标志物。次要结局指标将是α-1微球蛋白（肾小管损伤的标志物）和炎性细胞因子和C-C趋化因子（即肾脏炎症的标志物）的尿排泄。在同一患者的血浆和外周血单核细胞中，我们将分析GSH含量和GSH代谢酶的活性。此外，我们将分析血浆和尿液糖蛋白质组，重点是作为炎症细胞信使和激素的糖蛋白。将监测这些变量与治疗分配以及活性治疗的普遍血液和尿液水平的关系。在整个试验过程中，我们将监测这种联合治疗的安全性和耐受性。

Oxidative stress and glutathione (GSH) imbalance are major contributors to the pathogenesis of diabetic nephropathy. Circulating monocytes participate to this process since these cells carry a high oxidative burden and are found in diabetic renal tissue. Current options for the treatment of oxidative stress in diabetic nephropathy are limited and only partially effective, thus interest in the development of new strategies is high. N-acetylcysteine (NAC) and the milk thistle (MTh) plant flavonolignans are nutritional supplements with complementary antioxidant properties. Both supplements are capable of neutralizing directly toxic free radicals but, more importantly, NAC is substrate for the intracellular generation of GSH and the MTh flavonolignans are inducers of many cellular enzymes participating in GSH metabolism, including GSH-reductase (GSH-R), GSH-peroxidase (GSH-Px), GSH-S-transferases (GST) and superoxide dismutase (SOD). We propose that combined oral supplementation of NAC and MTh flavonolignans will reduce proteinuria and urinary and systemic manifestations of oxidative stress and inflammation, which are characteristically observed in patients with type 2 diabetes mellitus (T2DM) and related nephropathy. We expect these effects to be achieved with minimal or no side effects, and with good patient tolerance. To test this hypothesis, we propose a double-blind randomized, placebo-controlled, five-arm pilot study which includes a dose ranging component in patients with T2DM and established nephropathy. Intervention will consist of the individual and combined oral administration of one level of NAC and two levels of MTh flavonolignans or placebo for three months. The intervention groups are: (A) placebo; (B) NAC 600 mg BID; (C) Siliphos 480 mg BID; (D) NAC 600 mg BID + Siliphos 480 mg BID; and (E) NAC 600 mg BID + Siliphos 960 mg BID. The primary outcome measure will be urinary excretion of albumin, a marker of glomerular injury. Secondary outcome measures will be alpha-1 microglobulin, a marker of tubular injury, and urinary excretion of inflammatory cytokines and C-C chemokines, i.e. markers of renal inflammation. In plasma and in peripheral blood monocytes from the same patients, we will analyze GSH content and activity of GSH metabolizing enzymes. In addition, we will analyze the plasma and urine glycoproteome, with focus on those glycoproteins serving as inflammatory cell messengers and hormones. These variables will be monitored in relation to both treatment allocation and prevalent blood and urine levels of the active treatment. Throughout the trial, we will monitor the safety and tolerability of this combination treatment.