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摘要：
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摘要：目的 揭示原发性胆汁性胆管炎（primary biliary cholangitis，PBC）患者T细
胞受体（T cell receptor，TCR）图谱特征，并揭示大肠埃希菌（Escherichia coli，
E.coli）的丙酮酸脱氢酶复合体E2亚基（pyruvate dehydrogenase complex E2，
PDC-E2）抗原在PBC疾病的分子模拟机制。方法 采用多重聚合酶链反应和免疫组
库测序技术分析PBC患者和健康对照者的CD4+
和CD8+
记忆性TCR β链互补决定区3
（complementarity determining region 3， CDR3）序列的多样性、氨基酸组成及疏水
性、共有CDR3序列。体外诱导和扩增人PDC-E2163-176（人PDC-E2）抗原相关T细胞和
E.coli PDC-E231-44/134-147/235-248（E.coli PDC-E2）抗原相关T细胞，通过免疫组库测序技术
鉴定人（和E.coli）PDC-E2抗原相关TCR β CDR3图谱，并分析其丰度变化。结果 PBC
患者组和健康对照组间的CD4+
记忆性T细胞、CD8+
记忆性T细胞TCRβ CDR3免疫图谱
多样性相似，D50指数 [CD4+
记忆性T细胞：0.028 ± 0.019比0.034 ± 0.015；CD8+
记忆性
T细胞：（1.86 ± 2.70）× 10-3比（4.62 ± 3.89）× 10-4]、Shannon指数（CD4+
记忆性T细
胞：9.473 ± 1.346比9.734 ± 0.933；CD8+
记忆性T细胞：6.197 ± 1.519比5.436 ± 1.629）、
Gini指数（CD4+
记忆性T细胞：0.786 ± 0.048比0.760 ± 0.036；CD8+
记忆性T细胞：
0.920 ± 0.047比0.939 ± 0.025）等差异均无统计学意义（P均＞ 0.05）。PBC组和健康
对照组CD4+
记忆性T细胞和CD8+
记忆性T细胞间共有CDR3序列百分比差异无统计学意
义 [（6.47 ± 1.43）%比（6.21 ± 3.18）%；t = -0.21，P = 0.84]。健康对照组和PBC组中
序列长度为13、14、15的CDR3分子第6位和第7位氨基酸的组成频率中部分存在显著差
异，疏水氨基酸组成频率近似。通过细胞培养和免疫组库测序鉴定了一系列人PDC-E2
和E.coli PDC-E2抗原刺激后丰度显著上升的TCR序列。结论 该研究鉴定出PBC疾病的
TCR图谱特征，从TCR这个新视角阐述了E.coli在PBC疾病中的分子模拟机制。
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Abstract: Objective To reveal the characteristics of T cell receptor (TCR) profiles in patients with
primary biliary cholangitis (PBC) and to reveal the molecular mimicry mechanism of pyruvate
dehydrogenase complex E2 (PDC-E2) antigen of Escherichia coli (E.coli) in PBC disease.
Methods The sequence diversity, amino acid composition and hydrophobicity, and common
sequences of memory TCR β chain complementarity determining region 3s (CDR3s) of PBC
patients and healthy volunteers were analyzed by multiplex polymerase chain reaction and immune
repertoire sequencing. Human PDC-E2163-176 (PDC-E2) antigen-associated T cells and E.coli
PDC-E231-44/134-147/235-248 (E.coli PDC-E2) antigen-associated T cells were induced and amplified
in vitro, and human (E. coli) PDC-E2 antigen-related TCRβ CDR3 repertoire were identified by
immune repertoire sequencing. Results TCRβ CDR3 repertoire diversity of CD4+
memory T cells
and CD8+ memory T cells between PBC patients and healthy controls was similar, there were no
statistically significant differences in D50 index [CD4+
memory T cells: 0.028 ± 0.019 vs. 0.034 ±
0.015; CD8+
memory T cells: (1.86 ± 2.70) × 10-3 vs. (4.62 ± 3.89) × 10-4], Shannon index (CD4+
memory T cells: 9.473 ± 1.346 vs. 9.734 ± 0.933; CD8+
memory T cells: 6.197 ± 1.519 vs. 5.436 ±
1.629), Gini index（CD4+
memory T cells: 0.786 ± 0.048 vs. 0.760 ± 0.036；CD8+
memory T
cells: 0.920 ± 0.047 vs. 0.939 ± 0.025), etc. There was no significant difference in the percentage of
common CDR3 sequence between CD4+ memory T cells and CD8+ memory T cells of PBC patients
and healthy controls [(6.47 ± 1.43)% vs. (6.21 ± 3.18)%; t = -0.21, P = 0.84]. The percentage of
some amino acids at positions 6 and 7 (P6 and P7) of TCRβ CDR3 13～15 amino acids in length
in healthy control group and PBC group were significantly different, while the percentage of
hydrophobic amino acids were similar. It is noteworthy that a series of human PDC-E2 and E.coli
PDC-E2 antigen-related TCR sequences through cell culture and immune repertoire sequencing,
which may play an important role in the pathogenesis of PBC were identified . Conclusions This
study identified the TCR profile features of PBC disease and elucidated the molecular mimicry
mechanism of E.coli in PBC disease from the perspective of TCR.
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