Abstract:
The protease fibroblast activation protein (FAP) is a specific marker of activated mesenchymal cells in tumour stroma and fibrotic liver. A specific, reliable FAP enzyme assay has been lacking. FAP\'s unique and restricted cleavage of the post proline bond was exploited to generate a new specific substrate to quantify FAP enzyme activity. This sensitive assay detected no FAP activity in any tissue or fluid of FAP gene knockout mice, thus confirming assay specificity. Circulating FAP activity was ∼20- and 1.3-fold less in baboon than in mouse and human plasma, respectively. Serum and plasma contained comparable FAP activity. In mice, the highest levels of FAP activity were in uterus, pancreas, submaxillary gland and skin, whereas the lowest levels were in brain, prostate, leukocytes and testis. Baboon organs high in FAP activity included skin, epididymis, bladder, colon, adipose tissue, nerve and tongue. FAP activity was greatly elevated in tumours and associated lymph nodes and in fungal-infected skin of unhealthy baboons. FAP activity was 14- to 18-fold greater in cirrhotic than in non-diseased human liver, and circulating FAP activity was almost doubled in alcoholic cirrhosis. Parallel DPP4 measurements concorded with the literature, except for the novel finding of high DPP4 activity in bile. The new FAP enzyme assay is the first to be thoroughly characterised and shows that FAP activity is measurable in most organs and at high levels in some. This new assay is a robust tool for specific quantitation of FAP enzyme activity in both preclinical and clinical samples, particularly liver fibrosis.
摘要:
蛋白酶成纤维细胞活化蛋白(FAP)是肿瘤间质和纤维化肝脏中活化的间充质细胞的特异性标志物。一个具体的,一直缺乏可靠的FAP酶检测方法。利用FAP对脯氨酸后键的独特和限制性切割来产生新的特异性底物以定量FAP酶活性。该敏感试验在FAP基因敲除小鼠的任何组织或液体中均未检测到FAP活性,从而证实了测定的特异性。狒狒的循环FAP活性比小鼠和人血浆低20倍和1.3倍,分别。血清和血浆含有相当的FAP活性。在老鼠身上,FAP活性最高的是子宫,胰腺,颌下腺和皮肤,而最低水平在大脑中,前列腺,白细胞和睾丸。FAP活性高的狒狒器官包括皮肤,附睾,膀胱,结肠,脂肪组织,神经和舌头在肿瘤和相关淋巴结以及不健康的狒狒的真菌感染皮肤中,FAP活性大大提高。肝硬化患者的FAP活性比无疾病的人肝脏高14至18倍,在酒精性肝硬化中,循环FAP活性几乎翻了一番。并行DPP4测量与文献一致,除了胆汁中DPP4活性高的新发现。新的FAP酶测定法是第一个被彻底表征的测定法,并且显示FAP活性在大多数器官中是可测量的,并且在一些器官中是高水平的。这种新的检测方法是对临床前和临床样品中FAP酶活性进行特异性定量的强大工具。特别是肝纤维化。