Kubaski Francyne, Suzuki Yasuyuki, Orii Kenji, Giugliani Roberto, Church Heather J, Mason Robert W, Dũng Vũ Chí, Ngoc Can Thi Bich, Yamaguchi Seiji, Kobayashi Hironori, Girisha Katta M, Fukao Toshiyuki, Orii Tadao, Tomatsu Shunji
Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, United States; Department of Biological Sciences, University of Delaware, Newark, DE, United States; INAGEMP, Porto Alegre, Brazil.
Medical Education Development Center, Gifu University, Japan.
Mol Genet Metab. 2017 Mar;120(3):247-254. doi: 10.1016/j.ymgme.2016.12.010. Epub 2016 Dec 22.
Mucopolysaccharidoses (MPSs) and mucolipidoses (ML) are groups of lysosomal storage disorders in which lysosomal hydrolases are deficient leading to accumulation of undegraded glycosaminoglycans (GAGs), throughout the body, subsequently resulting in progressive damage to multiple tissues and organs. Assays using tandem mass spectrometry (MS/MS) have been established to measure GAGs in serum or plasma from MPS and ML patients, but few studies were performed to determine whether these assays are sufficiently robust to measure GAG levels in dried blood spots (DBS) of patients with MPS and ML.
In this study, we evaluated GAG levels in DBS samples from 124 MPS and ML patients (MPS I=16; MPS II=21; MPS III=40; MPS IV=32; MPS VI=10; MPS VII=1; ML=4), and compared them with 115 age-matched controls. Disaccharides were produced from polymer GAGs by digestion with chondroitinase B, heparitinase, and keratanase II. Subsequently, dermatan sulfate (DS), heparan sulfate (HS-0S, HS-NS), and keratan sulfate (mono-sulfated KS, di-sulfated KS, and ratio of di-sulfated KS in total KS) were measured by MS/MS.
Untreated patients with MPS I, II, VI, and ML had higher levels of DS compared to control samples. Untreated patients with MPS I, II, III, VI, and ML had higher levels of HS-0S; and untreated patients with MPS II, III and VI and ML had higher levels of HS-NS. Levels of KS were age dependent, so although levels of both mono-sulfated KS and di-sulfated KS were generally higher in patients, particularly for MPS II and MPS IV, age group numbers were not sufficient to determine significance of such changes. However, the ratio of di-sulfated KS in total KS was significantly higher in all MPS patients younger than 5years old, compared to age-matched controls. MPS I and VI patients treated with HSCT had normal levels of DS, and MPS I, VI, and VII treated with ERT or HSCT had normal levels of HS-0S and HS-NS, indicating that both treatments are effective in decreasing blood GAG levels.
Measurement of GAG levels in DBS is useful for diagnosis and potentially for monitoring the therapeutic efficacy in MPS.
黏多糖贮积症（MPS）和黏脂贮积症（ML）是一组溶酶体贮积病，其中溶酶体水解酶缺乏导致未降解的糖胺聚糖（GAG）在全身蓄积，随后导致多个组织和器官的进行性损伤。已建立使用串联质谱（MS/MS）的检测方法来测量MPS和ML患者血清或血浆中的GAG，但很少有研究确定这些检测方法是否足够稳健以测量MPS和ML患者干血斑（DBS）中的GAG水平。
在本研究中，我们评估了124例MPS和ML患者（MPS I = 16例；MPS II = 21例；MPS III = 40例；MPS IV = 32例；MPS VI = 10例；MPS VII = 1例；ML = 4例）DBS样本中的GAG水平，并将其与115例年龄匹配的对照进行比较。通过用软骨素酶B、乙酰肝素酶和角蛋白酶II消化，从聚合物GAG中产生二糖。随后，通过MS/MS测量硫酸皮肤素（DS）、硫酸乙酰肝素（HS-0S、HS-NS）和硫酸角质素（单硫酸化KS、双硫酸化KS以及双硫酸化KS在总KS中的比例）。
未经治疗的MPS I、II、VI和ML患者的DS水平高于对照样本。未经治疗的MPS I、II、III、VI和ML患者的HS-0S水平较高；未经治疗的MPS II、III、VI和ML患者的HS-NS水平较高。KS水平与年龄有关，因此尽管患者中尤其是MPS II和MPS IV患者的单硫酸化KS和双硫酸化KS水平通常较高，但年龄组数量不足以确定此类变化的显著性。然而，与年龄匹配的对照相比，所有5岁以下的MPS患者中双硫酸化KS在总KS中的比例显著更高。接受造血干细胞移植（HSCT）治疗的MPS I和VI患者的DS水平正常，接受酶替代疗法（ERT）或HSCT治疗的MPS I、VI和VII患者的HS-0S和HS-NS水平正常，表明这两种治疗方法在降低血液GAG水平方面均有效。
测量DBS中的GAG水平有助于MPS的诊断，并可能用于监测治疗效果。
