Petronijevic Sanja, Stig Solveig, Halstensen Trond S
Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
Eur J Oral Sci. 2020 Feb;128(1):27-36. doi: 10.1111/eos.12672. Epub 2020 Feb 21.
Previously we detected increased levels of IgA to the enamel matrix protein amelogenin in children with untreated coeliac disease (CeD). The biological impact of autoantibodies to amelogenin may depend on which part of the amelogenin (epitopes) they bind. Sera or blood samples from 146 untreated children with CeD from two different cohorts and 25 non-CeD control children were tested for IgA anti-amelogenin (Emdogain) reactivity. The 32 CeD children and six controls with the highest reactivity were selected for detailed IgA anti-amelogenin (AMELX) epitope mapping using 31 overlapping, 10-22mer peptides in ELISA. The dominating reactivity were to six peptides in a 75-amino-acid (aa)-long central segment (aa 75-150) containing enzymatic cleavage sites for matrix metalloproteinase 20 (MMP-20) and kallikrein-related peptidase 4 (KLK-4) and to two N-terminal peptides (aa 13-41) included in the tyrosine-rich amelogenin peptide fragment, which is important for self-assembly. Only two of the six control children reacted to single, but different peptides. Solid-phase extraction with gliadin- and Emdogain-coated Sepharose revealed a gliadin cross-reactive central region and a putative conformation-dependent, apparently non-cross-reactive N-terminal region. High IgA anti-amelogenin reactivity may interfere with normal amelogenesis by inhibiting amelogenin self-assembly, amelogenin-hydroxyapatite interaction, and/or enzymatic degradation.
此前我们检测到，未经治疗的乳糜泻（CeD）患儿体内针对釉质基质蛋白釉原蛋白的IgA水平升高。针对釉原蛋白的自身抗体的生物学影响可能取决于它们所结合的釉原蛋白的哪一部分（表位）。对来自两个不同队列的146名未经治疗的CeD患儿以及25名非CeD对照儿童的血清或血样进行了IgA抗釉原蛋白（Emdogain）反应性检测。选取了反应性最高的32名CeD患儿和6名对照，使用31种重叠的10 - 22肽段通过酶联免疫吸附测定法（ELISA）进行详细的IgA抗釉原蛋白（AMELX）表位图谱分析。主要反应针对的是一个75个氨基酸（aa）长的中央片段（aa 75 - 150）中的6个肽段，该片段包含基质金属蛋白酶20（MMP - 20）和激肽释放酶相关肽酶4（KLK - 4）的酶切位点，以及富含酪氨酸的釉原蛋白肽片段中包含的两个N端肽段（aa 13 - 41），这对于自组装很重要。6名对照儿童中只有2名对单个但不同的肽段有反应。用麦醇溶蛋白和Emdogain包被的琼脂糖进行固相萃取，揭示了一个麦醇溶蛋白交叉反应性中央区域和一个假定的构象依赖性、明显非交叉反应性的N端区域。高IgA抗釉原蛋白反应性可能通过抑制釉原蛋白自组装、釉原蛋白 - 羟基磷灰石相互作用和/或酶促降解来干扰正常的釉质形成。
