Single‐cell RNA‐seq reveals altered NK cell subsets and reduced levels of cytotoxic molecules in patients with ankylosing spondylitis

Abstract

Ankylosing spondylitis (AS) is an autoimmune disease with unknown aetiology. To unravel the mechanisms mediating AS pathogenesis, we profiled peripheral blood mononuclear cells (PBMCs) from AS patients and healthy subjects using 10X single‐cell RNA sequencing. The frequencies of immune cell subsets were evaluated by flow cytometry. NK cells were purified from PBMCs using isolation kit and were examined for gene expression by RT‐qPCR. Plasma levels of cytolytic molecules were examined by enzyme‐linked immunosorbent assay. Compared to healthy controls, AS patients showed a significant decrease in total NK cells as well as CD56dim NK subset, whereas CD56bright NK cells were increased. Additionally, impaired expression of cytotoxic genes in NK cells of AS patients was observed by bioinformatics algorithm and verified by RT‐qPCR and flow cytometry. Consistent with changes in transcriptomics, we found decreased plasma levels of granzymes, but not granulysin, in AS patients. Furthermore, Pearson correlation analysis revealed a negative correlation between plasma GZMB levels and disease activity (r = −0.5275, p = 0.0358). No correlation was observed between plasma cytolytic molecules and biochemical indexes (ESR and CRP). Our findings uncover altered NK cell subsets and cytotoxic profiles in peripheral circulation of AS patients at single‐cell resolution.

Mucosal-associated invariant T cells in patients with axial spondyloarthritis

“…In line with our data, Gracey and co-workers have previously demonstrated a down-regulation of cytotoxic cell-related genes in whole blood from AS patients (50). Consistent with these findings, Ren et al have shown that Granzyme A level was significantly decreased in serum of AS-patients (18). They hypothesized that reduction in circulating cytotoxic cells in AS-patients is caused by recruitment of these cytotoxic cells to the inflamed joint and implicated in tissue injury.…”

“…Data by Gracey and co-workers suggested that CD8 T cells with a cytotoxic phenotype are recruited to the joints and may play an overlooked role in the pathogenesis of AS (16,17). In addition, recent study by Ren et al uncovered remarkable differences in NK cell subsets and cytotoxic profile between AS patients and healthy individuals (18). Importantly, they have shown that plasma levels of Granzyme A (GrzA) and Granzyme B (GrzB) in AS patients were significantly reduced and negatively correlated with patientreported disease activity.…”

Identification of three autophagy-related genes as diagnostic biomarkers and analysis of immune cell infiltration in ankylosing spondylitis patients

“…Previous report indicated that CD8 + T cell frequency was decreased in blood of AS patients, and CD8 + T cell plays a central role in AS development (33). Single-cell RNA sequencing revealed altered NK cells subsets in peripheral circulation of AS patients (34). Increased of neutrophils may be a primary factor in the AS progression (35).…”

Single-cell profiling identifies a CD8brightCD244brightNatural Killer cell subset that reflects disease activity in HLA-A29-positivebirdshot chorioretinopathy

“…Transcriptomically distinct NK cell subsets are considered to exhibit differential effector functions mediated by an ensemble of surface immunoregulatory molecules 23 , in particular Killer cell immunoglobulin-like receptors (KIR), IgG Fc receptors (e.g., CD16), and integrins (e.g., CD47) 24, 25, 26 . Perturbations in the composition of the NK cells have been reported in other MHC-I associated conditions, such as HLA-B27-positive ankylosing spondylitis 27 and were shown to be predictive for clinical outcome in autoimmune diseases, such as Multiple Sclerosis 28 . Collectively, these observations suggest that deep phenotyping of the blood NK cell compartment could provide better understanding of disease biology and may hold clinically relevant information to the clinical course of BCR-UV.…”