Koenig P, Nagl C, Neurauter G, Schennach H, Brandacher G, Fuchs D
Department of Internal Medicine, Innsbruck Medical University, Austria.
Clin Nephrol. 2010 Dec;74(6):465-70. doi: 10.5414/cnp74465.
Hemodialysis patients often present with increased concentrations of tryptophan catabolites perhaps related to an enhanced activity of tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) that is inducible by pro-inflammatory stimuli. The often chronic inflammation and immune activation status in dialysis patients may accelerate tryptophan degradation, which could influence patients' psychological performance.
In this study, plasma concentrations of kynurenine and tryptophan were determined by HPLC in 75 dialysis patients, aged 65.3 ± 15.0 years. Forty patients were female, 35 male; 21 (28%) had diabetes mellitus Type 1 or 2 and 32 (43%) suffered from sleep disturbances and/or depression. Their dialysis vintage was 4.26 ± 4.72 years. HPLC results were compared to concentrations obtained from 40 healthy blood donors, to immune activation marker neopterin, and to psychological test results based on INTERMED scores.
Compared to those in healthy controls, tryptophan concentrations were decreased in patients. Neopterin, kynurenine and the kynurenine to tryptophan ratio (kyn/trp, an index of tryptophan degradation) were increased in patients (all p < 0.01). Kyn/trp correlated with neopterin concentrations (rs = 0.393, p < 0.01). INTERMED scores were 21.0 + 8.4 and slightly higher in females (U = -1.831, p < 0.07); they correlated with tryptophan concentrations (rs = -0.227, p < 0.05) but with no other parameter studied. Data point to a possible relationship between tryptophan metabolic disturbances and psychologic presentation of patients, although only a rather weak relationship was found.
We conclude that tryptophan degradation is increased in dialysis patients. The association with increased neopterin concentrations indicates activated IDO.
血液透析患者常常表现出色氨酸分解代谢产物浓度升高，这可能与色氨酸降解酶吲哚胺2,3-双加氧酶（IDO）活性增强有关，该酶可由促炎刺激诱导产生。透析患者常有的慢性炎症和免疫激活状态可能会加速色氨酸降解，这可能会影响患者的心理表现。
在本研究中，采用高效液相色谱法（HPLC）测定了75名年龄为65.3±15.0岁的透析患者血浆中犬尿氨酸和色氨酸的浓度。其中40名患者为女性，35名患者为男性；21名（28%）患有1型或2型糖尿病，32名（43%）患有睡眠障碍和/或抑郁症。他们的透析龄为4.26±4.72年。将HPLC结果与40名健康献血者的浓度、免疫激活标志物新蝶呤以及基于INTERMED评分的心理测试结果进行比较。
与健康对照组相比，患者的色氨酸浓度降低。患者的新蝶呤、犬尿氨酸以及犬尿氨酸与色氨酸的比值（kyn/trp，色氨酸降解指标）升高（均p<0.01）。Kyn/trp与新蝶呤浓度相关（rs = 0.393，p<0.01）。INTERMED评分为21.0 + 8.4，女性略高（U = -1.831，p<0.07）；它们与色氨酸浓度相关（rs = -0.227，p<0.05），但与其他研究参数无关。数据表明色氨酸代谢紊乱与患者心理表现之间可能存在关联，尽管仅发现了相当微弱的关系。
我们得出结论，透析患者色氨酸降解增加。与新蝶呤浓度升高相关表明IDO被激活。
