Abstract

The programmed cell death-1 (PD-1)/PD ligand pathway plays a key role in the maintenance of peripheral tolerance by enhancing the suppressive activity of regulatory T (Treg) cells. The promoter activity of the A allele of PD1 rs36084323 G/A polymorphism is lower than that of the G allele. We examined the association of PD1 gene polymorphisms, PD-1 expression on Treg cells, and thyroid PD-1/PD-1 ligand (PD-L1) expression with the pathogenesis of autoimmune thyroid disease (AITD). We classified patients and genotyped PD-1 polymorphisms by using the PCR-RFLP method in a total of 176 Graves’ disease (GD) patients, 150 Hashimoto’s disease (HD) patients with different disease severities and 99 healthy controls. PD-1 expression on Treg cells was analysed by flow cytometry. Indirect immunofluorescence staining was performed in thyroid tissue to detect PD-1, PD-L1, and PD-L2. The frequencies of the A allele and the AA + AG genotypes of the PD1 rs36084323 polymorphism were lower in HD patients than in GD patients, and the frequencies of the AA genotype of the PD1 rs36084323 and of the TT genotype of the PD1 rs2227982 were lower in mild HD patients than in severe HD patients. In patients with severe HD, the titres of TgAb at the onset were higher in patients with the PD1 rs36084323 AA genotype than in patients with the GG genotype. Peripheral PD1⁺ Treg cells tended to decrease in individuals with the PD1 rs36084323 AA genotype than with the G carrier genotype. Peripheral PD-1⁺ Treg cells were increased in HD, especially in mild HD. PD-1, PD-L1, and PD-L2 were expressed in thyroid-infiltrating mononuclear cells (TIMCs), and PD-L1 and PD-L2 were expressed in thyroid epithelial cells (TECs) in AITD patients but not in normal controls. Expression of PD-L1 in TIMCs and expression of PD-L2 in TECs were predominant in HD and GD patients, respectively. In conclusion, the functional PD1 rs36084323 polymorphism and the thyroid PD-1/ PD-L1s expression which may enhance the suppressive activity of Treg cells differ between GD and HD, and the PD1 rs36084323 and rs2227982 polymorphisms and PD1⁺ Treg cells are related to the severity of HD.

摘要

程序性细胞死亡-1 (PD-1)/PD 配体通路通过增强调节性 T (Treg) 细胞的抑制活性在维持外周耐受中发挥关键作用。PD1 rs36084323 G/A多态性的A等位基因的启动子活性低于G等位基因。我们检查了PD1的关联基因多态性、Treg细胞上PD-1表达、甲状腺PD-1/PD-1配体（PD-L1）表达与自身免疫性甲状腺疾病（AITD）的发病有关。我们使用 PCR-RFLP 方法对 176 名格雷夫斯病 (GD) 患者、150 名不同疾病严重程度的桥本病 (HD) 患者和 99 名健康对照者进行患者分类和基因分型 PD-1 多态性。通过流式细胞术分析Treg细胞上的PD-1表达。在甲状腺组织中进行间接免疫荧光染色以检测 PD-1、PD-L1 和 PD-L2。HD 患者PD1 rs36084323 多态性的 A 等位基因和 AA + AG 基因型的频率低于 GD 患者， PD1 rs36084323 的 AA 基因型和 TT 基因型的频率轻度 HD 患者的PD1 rs2227982 低于重度 HD 患者。在重度 HD 患者中，PD1 rs36084323 AA 基因型患者发病时的 TgAb 滴度高于 GG 基因型患者。与 G 携带者基因型相比，具有PD1 rs36084323 AA 基因型的个体的外周 PD1 ⁺ Treg 细胞倾向于减少。外设 PD-1 ⁺HD中的Treg细胞增加，特别是在轻度HD中。PD-1、PD-L1 和 PD-L2 在甲状腺浸润单核细胞 (TIMCs) 中表达，PD-L1 和 PD-L2 在 AITD 患者的甲状腺上皮细胞 (TECs) 中表达，但在正常对照组中不表达。PD-L1 在 TIMCs 中的表达和 PD-L2 在 TECs 中的表达分别在 HD 和 GD 患者中占主导地位。总之，功能性PD1 rs36084323多态性和可能增强Treg细胞抑制活性的甲状腺PD-1 / PD-L1s表达在GD和HD之间存在差异，PD1 rs36084323和rs2227982多态性和PD1 ⁺ Treg细胞与HD的严重程度。