Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 171 77 Stockholm, Sweden.
J Inflamm (Lond). 2011 Oct 8;8:25. doi: 10.1186/1476-9255-8-25.
The kynurenine pathway (KP) is the main route of tryptophan degradation in the human body and generates several neuroactive and immunomodulatory metabolites. Altered levels of KP-metabolites have been observed in neuropsychiatric and neurodegenerative disorders as well as in patients with affective disorders. The purpose of the present study was to investigate if skin derived human fibroblasts are useful for studies of expression of enzymes in the KP.
Fibroblast cultures were established from cutaneous biopsies taken from the arm of consenting volunteers. Such cultures were subsequently treated with interferon (IFN)-γ 200 U/ml and/or tumor necrosis factor (TNF)-α, 100 U/ml for 48 hours in serum-free medium. Levels of transcripts encoding different enzymes were determined by real-time PCR and levels of kynurenic acid (KYNA) were determined by HPLC.
At base-line all cultures harbored detectable levels of transcripts encoding KP enzymes, albeit with considerable variation across individuals. Following cytokine treatment, considerable changes in many of the transcripts investigated were observed. For example, increases in the abundance of transcripts encoding indoleamine 2,3-dioxygenase, kynureninase or 3-hydroxyanthranilic acid oxygenase and decreases in the levels of transcripts encoding tryptophan 2,3-dioxygenase, kynurenine aminotransferases or quinolinic acid phosphoribosyltransferase were observed following IFN-γ and TNF-α treatment. Finally, the fibroblast cultures released detectable levels of KYNA in the cell culture medium at base-line conditions, which were increased after IFN-γ, but not TNF-α, treatments.
All of the investigated genes encoding KP enzymes were expressed in human fibroblasts. Expression of many of these appeared to be regulated in response to cytokine treatment as previously reported for other cell types. Fibroblast cultures, thus, appear to be useful for studies of disease-related abnormalities in the kynurenine pathway of tryptophan degradation.
色氨酸降解的犬尿氨酸途径（KP）是人体内色氨酸降解的主要途径，并产生几种神经活性和免疫调节代谢物。在神经精神疾病和神经退行性疾病以及情感障碍患者中，观察到 KP 代谢物的水平发生了改变。本研究的目的是探讨皮肤来源的人成纤维细胞是否可用于研究 KP 中酶的表达。
从同意志愿者手臂上的皮肤活检中建立成纤维细胞培养物。随后，将这些培养物在无血清培养基中用干扰素（IFN）-γ 200 U/ml 和/或肿瘤坏死因子（TNF）-α 100 U/ml 处理 48 小时。通过实时 PCR 测定编码不同酶的转录本的水平，并通过 HPLC 测定犬尿氨酸（KYNA）的水平。
在基线时，所有培养物均存在可检测到的编码 KP 酶的转录本，但个体之间存在很大差异。在细胞因子处理后，研究的许多转录本发生了明显变化。例如，在 IFN-γ 和 TNF-α 处理后，编码吲哚胺 2,3-双加氧酶、犬尿氨酸酶或 3-羟基犬尿氨酸氧合酶的转录本丰度增加，而编码色氨酸 2,3-双加氧酶、犬尿氨酸氨基转移酶或喹啉酸磷酸核糖基转移酶的转录本水平降低。最后，在基础条件下，成纤维细胞培养物在细胞培养基中释放可检测到的 KYNA 水平，IFN-γ 处理后增加，但 TNF-α 处理后没有增加。
所有研究的编码 KP 酶的基因均在人成纤维细胞中表达。这些基因中的许多基因的表达似乎受到细胞因子处理的调节，如先前报道的其他细胞类型。因此，成纤维细胞培养物似乎可用于研究色氨酸降解的犬尿氨酸途径中与疾病相关的异常。
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