Unveiling the Immunological Landscape of Disseminated Tuberculosis: A Single-Cell Transcriptome Perspective

Zhen Gong ^1,2* Hongxiang Xu ¹ Qiao Zhang ¹ Guirong Wang ³ Lin Fan ⁴ Zilu Wang ¹ Lichao Fan ⁵ Yanhong Yu ⁵ Qiang Zhou ² Huasheng Xiao ⁶ 睿 Hou ⁶ Zhou Liu ² Ying Zhao ⁶ Yu Chen ⁵ Jianping Xie ^1* Chang Liu ⁷

• ¹ College of Life Science, Southwest University, Chongqing, China
• ² Department of Clinical Laboratory, Second Hospital of Anhui Medical University, Hefei, Anhui Province, China
• ³ Beijing Chest Hospital, Capital Medical University, Beijing, Beijing Municipality, China
• ⁴ Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, Shanghai, China
• ⁵ Tuberculosis Laboratory, Shenyang Tenth People's Hospital, Shenyang, Liaoning Province, China
• ⁶ Shanghai CASB Biotechnology (China), Shanghai, Shanghai Municipality, China
• ⁷ Shenyang Tenth People's Hospital, Shenyang, Liaoning Province, China

The etiology of hematogenous disseminated tuberculosis (DTB) likely involves multiple factors but is still not fully understood. This study involved single-cell RNA transcriptome and T cell receptor (TCR) sequencing on samples from 7 DTB patients. Additionally, we analyzed integrated data from two published profiles of latent TB infection, three active TB cases, and two healthy controls. Observations revealed a significantly higher proportion of inflammatory immune cells (such as monocytes and macrophages) and a notably lower abundance of various lymphocytes (including T cells, B cells, and plasma cells) in DTB patients. This suggests that lymphopenia could be a prominent feature of the disease. T cell pseudotime analysis indicated a decrease in most hypervariable gene expressions over time in DTB, pointing to T cell functional exhaustion as a potential immunological characteristic in DTB patients. Another significant indicator of T cell exhaustion in DTB is the notable absence of mucosal-associated invariant T (MAIT) cells, a key cytological feature in DTB peripheral blood. In the TCR repertoire of DTB patients, specific polymorphisms such as TRAV9-2, TRAV13-1, TRBV20-1, and TRBV5-1 were identified, along with dominant clones TRAJ49, TRBJ2-7, and TRBJ2-1. Analysis of the complementarity determining region 3 (CDR3) showed that the most frequent combination was TRAV1-2/TRAJ33. Notably, the motif "CAAMD" was significantly reduced in DTB patients, potentially indicating unique disease characteristics. In summary, our study provides new insights into the complex dynamics of TCR clonotypes, CDR3 dominant motifs, and cell types involved in DTB pathogenesis.In this study, we utilized Scs on peripheral blood mononuclear cells (PBMCs) from seven DTB patients to identify distinct cell types and explore their properties. We conducted pseudotime analysis to examine T cell development, subset heterogeneity, and signs of exhaustion. Our focus also extended to the functional enrichment and expression patterns of differential genes in T cell subsets, alongside investigating TCR development across different DTB patients.This study uniquely concentrates on DTB, often overshadowed by classical TB, and aims to identify diagnostic markers that hold immense clinical significance, striving to profile peripheral blood cell subpopulations and potential biomarkers at single-cell resolution to enhance timely clinical diagnosis.