Hintze Jonathan P, Tomatsu Shunji, Fujii Tadashi, Montaño Adriana M, Yamaguchi Seiji, Suzuki Yasuyuki, Fukushi Masaru, Ishimaru Takeshi, Orii Tadao
Department of Pediatrics, School of Medicine, Saint Louis University, St. Louis, MO, USA.
Biomark Insights. 2011;6:69-78. doi: 10.4137/BMI.S7451. Epub 2011 Jun 27.
Mucopolysaccharidosis IVA (MPS IVA) leads to skeletal dysplasia through excessive storage of chondroitin-6-sulfate and keratan sulfate (KS). KS is synthesized mainly in cartilage and released into circulation, making it a critical biomarker for MPS IVA to evaluate clinical course and effectiveness of therapies. Therefore, an accurate and sensitive method is required to measure KS levels.
Using sandwich ELISA and liquid chromatography tandem mass spectrometry (LC/MS/MS) assays, we measured KS levels in blood and urine from MPS IVA patients and healthy controls to evaluate comparability of results. Blood (patients, n = 110; controls, n = 364) and urine (patients, n = 103; controls, n = 326) specimens were obtained.
Plasma and urine KS measurements in patients were age-dependent and higher than age-matched controls. We observed a moderate correlation (r = 0.666; P < 0.001) between urine KS measurements and a weak correlation (r = 0.333; P = 0.002) between plasma KS measurements by ELISA and LC/MS/MS methods in patients. No correlation was found between plasma KS measurements in controls. The difference between KS measurements assayed by LC/MS/MS and ELISA was greater in controls than in patients. A moderate correlation between blood and urine KS measurements in the same individual was observed.
These findings indicate that both methods to measure blood and urine KS are suitable for diagnosis, monitoring therapies, and longitudinal assessment of the disease course in MPS IVA, but the LC/MS/MS method measures over 10 times more KS present in body fluids.
IVA型黏多糖贮积症（MPS IVA）通过硫酸软骨素-6-硫酸盐和硫酸角质素（KS）的过度蓄积导致骨骼发育异常。KS主要在软骨中合成并释放到循环系统中，使其成为评估MPS IVA临床病程和治疗效果的关键生物标志物。因此，需要一种准确且灵敏的方法来测量KS水平。
我们使用夹心酶联免疫吸附测定法（ELISA）和液相色谱串联质谱法（LC/MS/MS），测量了MPS IVA患者和健康对照者血液和尿液中的KS水平，以评估结果的可比性。采集了血液（患者110例；对照364例）和尿液（患者103例；对照326例）样本。
患者血浆和尿液中的KS测量值与年龄相关，且高于年龄匹配的对照者。我们观察到患者尿液KS测量值之间存在中度相关性（r = 0.666；P < 0.001），而ELISA法和LC/MS/MS法测量患者血浆KS值之间存在弱相关性（r = 0.333；P = 0.002）。对照者血浆KS测量值之间未发现相关性。LC/MS/MS法和ELISA法测量对照者KS值的差异大于患者。在同一个体中观察到血液和尿液KS测量值之间存在中度相关性。
这些发现表明，测量血液和尿液KS的两种方法均适用于MPS IVA的诊断、治疗监测和疾病病程的纵向评估，但LC/MS/MS法测量的体液中KS含量是另一种方法的10倍以上。
