Autoantibodies of patients with coeliac disease are insufficient to block tissue transglutaminase activity
Autoantibodies of patients with coeliac disease are insufficient to block tissue transglutaminase activity
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DOI：
10.1136/gut.52.11.1562
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发表时间：
2003-11-01
期刊：
影响因子：
24.5
通讯作者：
Schuppan, D
中科院分区：
文献类型：
--
作者：
Dieterich, W;Trapp, D;Schuppan, D
背景和目的：乳糜泻（CD）的特点是存在针对组织转谷氨酰胺酶（tTG）的自身抗体，即肌内膜自身抗原。本研究旨在确定纯化的自身抗体对tTG酶活性的影响。方法：从未治疗的CD患者和对照组血清中分离总IgA、IgG类抗体和纯化的抗ttg自身抗体。抗体对tTG活性的抑制能力通过基于将单丹基尸胺掺入酪蛋白和通过tTG催化的生物素化尸胺与麦胶蛋白交联的荧光测定来检测。结果：5例CD患者和3例对照者的IgA和IgG富集部位对酶活性的抑制无显著差异。相比之下，与对照免疫球蛋白相比，12例CD患者使用亲和纯化的抗tTG自身抗体导致tTG活性的剂量依赖性降低（n = 6）。然而，剩余的活性足以将尸胺交联到麦胶蛋白，并且tTG酶活性仅被高浓度的单克隆抗体完全阻断，该抗体直接指向tTG的活性中心。结论：尽管从CD患者身上分离的抗ttg自身抗体有部分抑制作用，但残留的酶活性仍然足够高，因此怀疑它们在体内的相关性。
Background and aims: Coeliac disease (CD) is characterised by the presence of autoantibodies against tissue transglutaminase (tTG), the endomysial autoantigen. This study was performed to determine the effect of purified autoantibodies on the enzymatic activity of tTG.Methods: Total IgA and IgG class antibodies and purified anti-tTG autoantibodies were isolated from sera of untreated patients with CD and controls. The inhibitory capacity of the antibodies on tTG activity was checked by a fluorometric assay based on the incorporation of monodansyl cadaverine into casein and by tTG-catalysed cross linking of biotinylated cadaverine to gliadin.Results: The enriched IgA and IgG fractions of five patients with CD and three controls resulted in no significantly different inhibition of enzymatic activity. In contrast, the use of affinity purified anti-tTG autoantibodies of 12 patients with CD led to a dose dependent reduction of tTG activity, compared to control immunoglobulins (n = 6). However, the remaining activity was sufficient for cross linking of cadaverine into gliadin, and enzymatic tTG activity was only blocked completely by high concentrations of a monoclonal antibody, which is directed to the active centre of tTG.Conclusions: Despite a partial inhibitory effect of isolated anti-tTG autoantibodies from patients with CD, residual enzymatic activity remains sufficiently high to cast doubt on their in vivo relevance.