Background: Multiple 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. Methods: Single-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. Results: Other than diminished naïve 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. Conclusions: Our 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.

Spontaneous autoimmune peripheral neuropathy including Guillain-Barré Syndrome (GBS) represents as one of the serious emergencies in neurology. Although pathological changes have been well documented, molecular and cellular mechanisms of GBS are still under-explored, partially due to short of appropriate animal models. The field lacks of spontaneous and translatable models for mechanistic investigations. As GBS is preceded often by viral or bacterial infection, a condition can enhance co-stimulatory activity; we sought to investigate the critical role of T cell co-stimulation in this autoimmune disease.

Background: Intracranial non-branching site blood blister-like aneurysms (BBA) are extremely rare and vicious. Their etiology remains elusive, and no molecular study has been carried out to reveal its pathogenic relevance to intracranial atherosclerosis. To investigate its transcriptomic landscape and underlying potential pathogenesis, we performed single-cell RNA sequencing with extensive pathological validation.Methods: In total, 12,245 cells were recovered for single-cell RNA sequencing analysis from 1 BBA and 2 saccular intracranial aneurysms (IAs). Unbiased clustering using Seurat-based pipeline was used for cellular landscape profiling. Cellchat was used to understand intracellular communications. Furthermore, 10 BBAs and 30 IAs were retrospectively collected for pathological validations like scanning electron microscopy, H&E stain, Masson stain, Verhoeff Van Gielson stain, and immunofluorescence.Results: Single-cell transcriptome profiled 14 total subclusters in 6 major groups, namely, 6 monocyte/macrophage clusters, 2 T&NK clusters, 3 vascular smooth muscle cell (VSMC) clusters, 1 dendritic cell, 1 B cell, and 1 endothelial cell cluster. The only mural cell identified in BBAs was VSMC-2 cluster, while mural cells in IAs comprise most clusters of VSMCs and endothelial cells. Upregulated genes in BBA-derived VSMCs are related to arterial mineralization and atherosclerosis, such as PTX3, SPP1, LOX, etc., whereas vasodilation and physiological regulatory genes such as MGP, ACTA2, and MYL9 were conversely enriched in conventional IA-derived VSMCs. Immune cells in the BBA were predominantly macrophages, with a low fraction of T&NK cells, while conventional IAs had a higher percentage of T&NK. Gene enrichment analysis suggested that macrophages in BBA were highly enriched in lipid metabolism as well as atherosclerosis. Ligand–receptor interaction suggested that secretory phosphoprotein 1 (also known as osteopontin) played a major role in mediating the intracellular communication between VSMC and macrophages, especially in BBA. Pathological experiments corroborate with the bioinformatic findings and further characterized BBAs as a thin-walled thrombotic aneurysm with severe atherosclerotic lesions, where ApoE+ macrophages and OPN+ mural cells are intimately involved in the inflammation process.Conclusions: The preexisting intracranial atherosclerosis might predispose the parent artery to the pathogenic occurrence of BBAs. These data shed light on the pathophysiology of intracranial aneurysms and might assist in the further resolution of the complexity in aneurysm pathogenesis.

Objective: Our study aimed to investigate circulating CD8⁺ T cell subpopulations and pro‐inflammatory cytokines in the neuromyelitis optica spectrum disorder (NMOSD).Methods: A total of 121 peripheral blood samples were obtained from 57 patients with NMOSD, 34 patients with multiple sclerosis (MS), and 30 sex‐ and age‐matched healthy controls (HCs) for detection of CD8⁺ T cell subpopulations, including phenotypes of naïve (T_N, CD62L^hiCD45RO^‐), effector/memory (T_E/M, CD62L^loCD45RO⁺), memory precursor (T_MP, CD127^hiKLRG1^lo), and short lived effector (T_SLEC, CD127^loKLRG1^hi). In addition, 36 samples from 18 NMOSD, 12 MS, and 6 sex‐ and age‐matched HCs for detecting pro‐inflammatory cytokines (IFNγ and TNFα) using flow cytometry.Results: Compared with HCs, we found significantly reduced CD8⁺ T_N and increased CD8⁺ T_E/M in both NMOSD and MS，while decreased CD8⁺ T_MP was only observed in NMOSD. Patients treated with immunotherapy were associated with increased CD8⁺ T_N and decreased CD8⁺ T_E/M in NMOSD. Moreover NMOSD cohort showed significant higher proportions of IFNγ⁺CD8⁺ T cells and proportions of TNFα⁺CD8⁺ T cells than HC and MS cohorts. On the contrary, obviously decreased IFNγ and TNFα were found in NMOSD patients treated with immunotherapy. Furthermore, Multivariate linear regression analyses revealed that age was negatively correlated with CD8⁺ T_N and T_MP, and positively associated with T_SLEC; however, sex, EDSS scores and disease phase were not significantly associated with CD8⁺ T subpopulations.Interpretation: This current study provides an evidence that circulating CD8⁺ T cell with abnormal subpopulations and increased pro‐inflammatory were associated with pathogenesis of autoimmune demyelinating disease of CNS, especially in NMOSD.