Granzyme B+CD8+T cells with terminal differentiated effector signature determine multiple sclerosis progression

BackgroundMultiple sclerosis (MS) leads to demyelination and neurodegeneration with autoimmune responses in central nervous system. Patients begin with a relapsing-remitting (RR) course, and more than 80% of them may advance to secondary progressive MS (SPMS), which is characteristic for the gradual decline of neurological functions without demonstrated treating method to prevent. This study aims to investigate the contribution of peripheral CD8 + T cells during the conversion from RRMS to SPMS, as well as reveal potential diagnostic signature in distinguishing SPMS.MethodsSingle-cell RNA sequencing was employed to reveal the heterogeneity of CD8 + T cells between SPMS and RRMS. In addition, flow cytometry was used to further characterized CD8 + T cell dynamic changes in patients. T cell receptor sequencing was performed to detect the clonal expansion of MS. Using Tbx21 siRNA, T-bet was confirmed to manipulate GzmB expression. The correlation between GzmB + CD8 + T cell subsets and clinical characteristics of MS and their potential diagnostic value for SPMS were evaluated by generalized linear regression models and receiver operating characteristic (ROC) curve respectively.ResultsOther than diminished naive CD8 + T cell, elevating of activated CD8 + T cell subsets were observed in SPMS patients. Meanwhile, this aberrant amplified peripheral CD8 + T cells not only exhibited terminal differentiated effector (EMRA) phenotype with GzmB expression, but also possessed distinct trajectory from clonal expansion. In addition, T-bet acted as a key transcriptional factor that elicited GzmB expression in CD8 + T-EMRA cells of patients with SPMS. Finally, the expression of GzmB in CD8 + T cells was positively correlated with disability and progression of MS, and could effectively distinguish SPMS from RRMS with a high accuracy.ConclusionsOur study mapped peripheral immune cells of RRMS and SPMS patients and provided an evidence for the involvement of GzmB + CD8 + T-EMRA cells in the progression of MS, which could be used as a diagnostic biomarker for distinguishing SPMS from RRMS.

Automated summary

This study investigated the contribution of peripheral CD8+ T cells during the conversion from RRMS to SPMS and revealed a diagnostic biomarker for distinguishing SPMS from RRMS. Single-cell RNA sequencing and flow cytometry were used to analyze the heterogeneity and dynamic changes of CD8+ T cells. The study found that activated CD8+ T cell subsets were elevated in SPMS patients, and GzmB expression in CD8+ T-EMRA cells played a key role in the progression of MS. The expression of GzmB in CD8+ T cells was correlated with disability and progression of MS, and could effectively distinguish SPMS from RRMS.