Division of Rheumatology, Toronto Western Hospital, University of Toronto, Ontario, Canada.
Ann Rheum Dis. 2012 Apr;71(4):589-95. doi: 10.1136/annrheumdis-2011-200347. Epub 2012 Feb 21.
The functional interaction of endoplasmic reticulum aminopeptidase 1 (ERAP1) with human leucocyte antigen (HLA)-B27 could be important in the pathogenesis of ankylosing spondylitis (AS). AS is associated with B27:04 and B27:05, but not with B27:06 and B27:09. The authors studied the surface expression of peptide-HLA(pHLA)-B27 complexes and HLA class-I free heavy chains (FHCs) on peripheral blood mononuclear cells of patients with AS with different ERAP1 single nucleotide polymorphisms. The effects of ERAP1 suppression on HLA-B27 subtypes were tested.
Peripheral blood mononuclear cells were collected from Caucasian patients with AS for flow cytometry and were stained for pHLA and FHCs. Genotyping was performed for two ERAP1 single nucleotide polymorphisms (rs27044(C/G) and rs30187(C/T)). C1R cells transfected with different HLA-B27 subtypes (B27:04, B27:05, B27:06 and B27:09) were subjected to ERAP1 suppression by small interfering RNA and stained using the monoclonal antibody (mAb) MARB4 as well as antibodies for pHLA, FHC, intracellular FHC (IC-FHC). MARB4 has been reported to bind to HLA-B27 with extended peptides.
The authors found variations in FHC expression on the monocytes of patients with AS, depending on different ERAP1 variants. Subsequently, using Hmy2.C1R cells in vitro, the authors show that ERAP1 suppression leads to increased IC-FHC and surface pHLA that react with the monoclonal antibody MARB4. The functional interaction between ERAP1 and HLA-B27 molecules appears to be subtype-specific, since ERAP1 suppression leads to changes only in cells expressing B27:04 or B27:05, but not B27:06 or B27:09.
Direct or indirect alterations in the ERAP1-HLA-B27 interaction could be crucial by causing changes in peptide presentation or FHC formation by HLA-B27 molecules, as well as by contributing to differential subtype association in spondyloarthropathies.
内质网氨肽酶 1（ERAP1）与人类白细胞抗原（HLA）-B27 的功能相互作用可能在强直性脊柱炎（AS）的发病机制中起重要作用。AS 与 B27：04 和 B27：05 相关，但与 B27：06 和 B27：09 不相关。作者研究了不同 ERAP1 单核苷酸多态性的 AS 患者外周血单个核细胞表面表达的肽-HLA（pHLA）-B27 复合物和 HLA Ⅰ类游离重链（FHC）。测试了 ERAP1 抑制对 HLA-B27 亚型的影响。
收集白人 AS 患者的外周血单个核细胞进行流式细胞术，并对 pHLA 和 FHCs 进行染色。对 ERAP1 的两个单核苷酸多态性（rs27044（C/G）和 rs30187（C/T））进行基因分型。用不同的 HLA-B27 亚型（B27：04、B27：05、B27：06 和 B27：09）转染 C1R 细胞，并通过小干扰 RNA 抑制 ERAP1，然后用单克隆抗体（mAb）MARB4 以及 pHLA、FHC、细胞内 FHC（IC-FHC）抗体进行染色。MARB4 已被报道可与具有扩展肽的 HLA-B27 结合。
作者发现 AS 患者单核细胞上的 FHC 表达存在差异，这取决于不同的 ERAP1 变体。随后，作者在体外使用 Hmy2.C1R 细胞表明，ERAP1 抑制导致 IC-FHC 和与单克隆抗体 MARB4 反应的表面 pHLA 增加。ERAP1 与 HLA-B27 分子之间的功能相互作用似乎具有亚型特异性，因为 ERAP1 抑制仅导致表达 B27：04 或 B27：05 的细胞发生变化，而不影响 B27：06 或 B27：09。
ERAP1-HLA-B27 相互作用的直接或间接改变可能通过改变 HLA-B27 分子的肽呈递或 FHC 形成，以及通过导致脊柱关节病的不同亚型相关性而变得至关重要。
