Petersen Jan, van Bergen Jeroen, Loh Khai Lee, Kooy-Winkelaar Yvonne, Beringer Dennis X, Thompson Allan, Bakker Sjoerd F, Mulder Chris J J, Ladell Kristin, McLaren James E, Price David A, Rossjohn Jamie, Reid Hugh H, Koning Frits
Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia;
Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden 2333 ZA, the Netherlands;
J Immunol. 2015 Jun 15;194(12):6112-22. doi: 10.4049/jimmunol.1500161. Epub 2015 May 6.
In HLA-DQ8-associated celiac disease (CD), the pathogenic T cell response is directed toward an immunodominant α-gliadin-derived peptide (DQ8-glia-α1). However, our knowledge of TCR gene usage within the primary intestinal tissue of HLA-DQ8 (+) CD patients is limited. We identified two populations of HLA-DQ8-glia-α1 tetramer(+) CD4(+) T cells that were essentially undetectable in biopsy samples from patients on a gluten-free diet but expanded rapidly and specifically after antigenic stimulation. Distinguished by expression of TRBV9, both T cell populations displayed biased clonotypic repertoires and reacted similarly against HLA-DQ8-glia-α1. In particular, TRBV9 paired most often with TRAV26-2, whereas the majority of TRBV9(-) TCRs used TRBV6-1 with no clear TRAV gene preference. Strikingly, both tetramer(+)/TRBV9(+) and tetramer(+)/TRBV9(-) T cells possessed a non-germline-encoded arginine residue in their CDR3α and CDR3β loops, respectively. Comparison of the crystal structures of three TRBV9(+) TCRs and a TRBV9(-) TCR revealed that, as a result of distinct TCR docking modes, the HLA-DQ8-glia-α1 contacts mediated by the CDR3-encoded arginine were almost identical between TRBV9(+) and TRBV9(-) TCRs. In all cases, this interaction centered on two hydrogen bonds with a specific serine residue in the bound peptide. Replacement of serine with alanine at this position abrogated TRBV9(+) and TRBV9(-) clonal T cell proliferation in response to HLA-DQ8-glia-α1. Gluten-specific memory CD4(+) T cells with structurally and functionally conserved TCRs therefore predominate in the disease-affected tissue of patients with HLA-DQ8-mediated CD.
在与HLA - DQ8相关的乳糜泻（CD）中，致病性T细胞反应针对一种免疫显性的α - 麦醇溶蛋白衍生肽（DQ8 - 麦醇溶蛋白 - α1）。然而，我们对HLA - DQ8（+）CD患者原发性肠道组织内TCR基因使用情况的了解有限。我们鉴定出两类HLA - DQ8 - 麦醇溶蛋白 - α1四聚体（+）CD4（+）T细胞群体，在无麸质饮食患者的活检样本中基本检测不到，但在抗原刺激后迅速且特异性地扩增。这两类T细胞群体通过TRBV9的表达来区分，它们都表现出偏向性的克隆型库，并且对HLA - DQ8 - 麦醇溶蛋白 - α1的反应相似。特别是，TRBV9最常与TRAV26 - 2配对，而大多数TRBV9（ - ）TCR使用TRBV6 - 1，且对TRAV基因没有明显偏好。引人注目的是，四聚体（+）/TRBV9（+）和四聚体（+）/TRBV9（ - ）T细胞在其CDR3α和CDR3β环中分别具有一个非种系编码的精氨酸残基。对三个TRBV9（+）TCR和一个TRBV9（ - ）TCR晶体结构的比较表明，由于不同的TCR对接模式，由CDR3编码的精氨酸介导的HLA - DQ8 - 麦醇溶蛋白 - α1接触在TRBV9（+）和TRBV9（ - ）TCR之间几乎相同。在所有情况下，这种相互作用集中在与结合肽中特定丝氨酸残基的两个氢键上。将该位置的丝氨酸替换为丙氨酸可消除TRBV9（+）和TRBV9（ - ）克隆性T细胞对HLA - DQ8 - 麦醇溶蛋白 - α1的增殖反应。因此，具有结构和功能保守TCR的麸质特异性记忆CD4（+）T细胞在HLA - DQ8介导的CD患者受疾病影响的组织中占主导地位。
