Single-cell profiling reveals pathogenic role and differentiation trajectory of granzyme K+CD8+ T cells in primary Sjögren’s syndrome

Abstract

Primary Sjogren's syndrome (pSS) is a systemic autoimmune inflammatory disease mainly defined by T cell-dominated destruction of exocrine glands. Currently, CD8 + T cells were closely related to the pathogenesis of pSS. However, the single-cell immune profiling of pSS and molecular signatures of pathogenic CD8 + T cells have not been well elucidated.Our multiomics investigation identified that both T cell and B cell, especially CD8 + T cells, were undergoing significant clonal expansion in pSS patients. TCR clonality analysis revealed that peripheral granzyme (GZM) K + CXCR6 + CD8 + T cells had higher proportion of shared clones with CD69 + CD103 -CD8 + tissue resident memory T (TRM) cells in labial glands in pSS. CD69 + CD103 -CD8 + TRM cells featured by high expression of GZMK were more active and cytotoxic in pSS compared with their CD103 + counterparts. Peripheral GZMK + CXCR6 + CD8 + T cells with higher CD122 expression were increased and harbored a gene signature similar to TRM cells in pSS. Consistently, IL-15 was significantly elevated in pSS plasma and showed the capacity to promote differentiation of CD8 + T cells into GZMK + CXCR6 + CD8 + T cells in a STAT5 dependent manner. Taken together, we depicted the immune profile of pSS and further conducted comprehensive bioinformatics analysis and in vitro experimental investigation to characterize the pathogenic role and differentiation trajectory of CD8 + TRM cells in pSS.

PD-1 Mediated Regulation of Unique Activated CD8+T Cells by NK Cells in the Submandibular Gland

“…To determine the clinical relevance of these highly activated CD8 + T cells, we compared them to CD8 + T cells associated with Sjogren’s Syndrome in human patients 31,32 . In Sjogren’s Syndrome patients, pathogenic resident GzmK + CD8 + T cells expand and correlate with disease severity 32 . Importantly, of 50 genes differentially upregulated in those cytotoxic T cells, 17 are also upregulated in the murine CD8 Activated 3 cluster of interest ( Supplemental Figure 5 ).…”

“…Importantly, the CD8 + T cells of interest express high levels of GzmK , consistent with highly activated CD8 + T cell populations. A recent study from primary Sjögren’s Syndrome patients found a population of CD8 + T cells with high expression of GzmK that are highly active and cytotoxic 32 . Notably, in this data set, upregulated expression of GzmK correlated with disease severity.…”

“…To determine the clinical relevance of these highly activated CD8 + T cells, we compared them to CD8 + T cells associated with Sjogren's Syndrome in human patients 31,32 . In Sjogren's Syndrome patients, pathogenic resident GzmK + CD8 + T cells expand and correlate with disease severity 32 .…”

Multimodal Single‐Cell Sequencing of B Cells in Primary Sjögren's Syndrome

“…Previous studies using scRNA-seq and analyzing PBMCs in a handful of patients with pSS have primarily reported differences in the T cell compartment, whereas the B cells were only briefly considered. 13,[24][25][26] Here, we assigned the individual B cells into 16 cellular states, all present in both patients and controls, but with a shift in the composition of B cell subtypes. The largest difference compared with controls was seen in the SSA/SSB+ patient group.…”

“…This is the first large‐scale study in which B cell composition and BCR gene usage have been investigated at the single‐cell level in patients with pSS stratified for SSA/SSB antibodies. Previous studies using scRNA‐seq and analyzing PBMCs in a handful of patients with pSS have primarily reported differences in the T cell compartment, whereas the B cells were only briefly considered 13,24–26 . Here, we assigned the individual B cells into 16 cellular states, all present in both patients and controls, but with a shift in the composition of B cell subtypes.…”