Characterization of T-Cell Receptor Repertoire in Patients with Rheumatoid Arthritis Receiving Biologic Therapies

Abstract

Rheumatoid arthritis (RA) is a systematic autoimmune disease, predominantly causing chronic polyarticular inflammation and joint injury of patients. For the treatment of RA, biologic disease-modifying antirheumatic drugs (bDMARDs) have been used to reduce inflammation and to interfere with disease progression through targeting and mediating the immune system. Although the therapeutic effects of bDMARDs in RA patients have been widely reported, whether these drugs also play important roles in T-cell repertoire status is still unclear. We therefore designed the study to identify the role of T-cell repertoire profiles in RA patients with different types of bDMARD treatments. A high-throughput sequencing approach was applied to profile the T-cell receptor beta chain (TCRB) repertoire of circulating T lymphocytes in eight patients given adalimumab (anti-TNF-α) with/without the following use of either rituximab (anti-CD20) or tocilizumab (anti-IL6R). We subsequently analyzed discrepancies in the clonal diversity and CDR3 length distribution as well as usages of the V and J genes of TCRB repertoire and interrogated the association between repertoire diversity and disease activities followed by the treatment of bDMARDs in these RA patients. All groups of patients showed well-controlled DAS28 scores (<2.6) after different treatment regimens of drugs and displayed no significant statistical differences in repertoire diversity, distribution of CDR3 lengths, and usage of V and J genes of TCRB. Nonetheless, a trend between overall TCRB repertoire diversity and disease activity scores in all bDMARD-treated RA patients was observed. Additionally, age was found to be associated with repertoire diversity in RA patients treated with bDMARDs. Through the profiling of the TCR repertoire in RA patients receiving different biologic medications, our study indicated an inverse tendency between TCR repertoire diversity and disease activity after biologic treatment in RA patients.

Figure 1

A schematic diagram illustrating sample collection from bDMARD-treated RA patients.

Figure 2

The TCRB repertoire diversity in bDMARD-treated RA patients. (a) TCRB clonotypes of RA patients receiving adalimumab only (A1 and A2), adalimumab followed by rituximab (R1, R2, and R3), and adalimumab followed by tocilizumab (T1, T2, and T3) are represented as dots and ranked according to clonal frequency from high to low. The diversity index of the TCRB repertoire for each patient was calculated as the inverse Simpson diversity index (1/D). (b) The boxplot shows the comparison of TCRB repertoire diversity between RA patients receiving different courses of bDMARD treatment. The upper, middle, and lower lines of the box corresponds to the third quartile, median, and first quartile of the diversity index of patients in each stratified group, respectively.

Figure 3

The CDR3 length of the TCRB repertoire in bDMARD-treated RA patients. (a) The distributions of the CDR3 amino acid lengths of the TCRB clonotypes in RA patients receiving adalimumab only (A1 and A2), adalimumab followed by rituximab (R1, R2, and R3), and adalimumab followed by tocilizumab (T1, T2, and T3) are illustrated. (b) The intragroup repertoire dissimilarity index (RDI) values of TCRB CDR3 lengths between each pair of RA patients are represented.

Figure 4

Usages of the TRBV and TRBJ genes of the TCRB repertoire in bDMARD-treated RA patients. The heatmaps illustrate fractions of (a) TRBV and (b) TRBJ genes of RA patients receiving different courses of bDMARD treatment in a color spectrum between white (low) and red (high). The intragroup repertoire dissimilarity index (RDI) values of (c) TRBV, (d) TRBJ, and (e) V-J combinations between each pair of RA patients are illustrated.

Figure 5

Correlation between TCRB repertoire diversity and disease activity in bDMARD-treated RA patients. The TCRB repertoire diversity showed a negative trend toward DAS28, CDAI, and SDAI scores (a) in all bDMARD-treated RA patients, (b) in patients receiving adalimumab followed by rituximab, and (c) in patients receiving adalimumab followed by tocilizumab. The statistical analysis was performed using the Pearson correlation.