Composition and diversity analysis of the TCR CDR3 repertoire in patients with idiopathic orbital inflammation using high-throughput sequencing.

Background: Idiopathic orbital inflammation (IOI) is a nonspecific orbital inflammatory disease with the third highest prevalence among orbital diseases, and its pathogenesis is associated with T-cell-mediated immune responses. This study aimed to investigate the differences in T-cell receptor (TCR) expression between IOI patients and healthy subjects by high-throughput sequencing and to characterize TCR expression in patients with IOI and with respect to glucocorticoid response.

Methods: A total of 19 subjects were enrolled in this study and were divided into the idiopathic orbital inflammation group (IOI group, n = 13) and the healthy control group (HC group, n = 6), and within the IOI group were further divided into the glucocorticoid therapy sensitive group (IOI(EF) group, n = 6) and the glucocorticoid therapy ineffective group (IOI(IN) group, n = 7) based on the degree of effectiveness to glucocorticoid therapy. High-throughput TCR sequencing was performed on peripheral blood mononuclear cells of IOI patients and healthy control individuals using 5' RACE technology combined with Unique Identifier (UID) digital tag correction technology. The TCR CDR3 region diversity, sharing patterns, and differential sequences between the IOI and HC groups, and between the IOI(EF) and IOI(IN) groups were analyzed.

Results: It was found that the diversity of TCR CDR3 in the IOI group was significantly lower than that in the HC group, and the frequency of V gene use was significantly different between groups. The diversity of TCR CDR3 in patients in the IOI(EF) group was significantly lower than that in patients in the IOI(IN) group, and the frequency of V and J gene use was significantly different between the IOI(EF) group and the IOI(IN) group. Additionally, we found 133 nucleotide sequences shared in all IOI samples and screened two sequences with higher expression from them.

Conclusions: Our results suggested that abnormal clonal expansion of specific T-cells exists in IOI patients and that TCR diversity may had an impact on the prognosis of glucocorticoid-treated IOI. This study may contribute to a better understanding of the immune status of IOI and provide new insights for T-cell -associated IOI pathogenesis, diagnosis and treatment prediction.