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RNA-sequencing in plasmacytoid dendritic cells from patients with primary Sjogren's syndrome (pSS), non-Sjogren's sicca (nSS), and healthy donors (HC)

ABSTRACT: We here provide the first in-depth molecular analysis of pDCs from patients with pSS and nSS in comparison to HC. We isolated circulating pDCs from two independent cohorts of patients and controls (each n=31) and performed RNA-sequencing, after which data-driven networks and modular analysis were used to identify signatures of robustly reproducible transcriptional “signatures” of dysregulated differential and co-expressed genes. Four reproducible gene signatures were identified that indicated pDC activation. Comparison with in vitro activated pDCs showed that pSS pDCs have higher expression of many genes also upregulated upon pDC activation. In all transcriptional analyses, nSS patients formed an intermediate group in which some patients were molecularly similar to pSS patients. Our data provide in-depth characterization of the aberrant regulation of pDCs from patients with nSS and pSS and substantiate their perceived role in the immunopathology of pSS, supporting studies that target pDCs, type-I IFNs, or IFN-signalling in pSS.

ORGANISM(S): Homo sapiens

PROVIDER: GSE135635 | GEO | 2019/09/11

REPOSITORIES: GEO

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Project description:Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease characterized by infiltration of the exocrine glands and prominent B cell hyperactivity. Considering the key role of monocytes in promoting B cell hyperactivity, we performed RNA-sequencing analysis of CD14+ monocytes from patients with pSS, non-Sjögren’s sicca (nSS), and healthy controls (HC). We demonstrated that the transcriptomic profile of pSS patients is enriched in intermediate and non-classical monocyte profiles, and confirmed the increased frequency of non-classical monocytes in pSS patients by flow-cytometry analysis. Weighted gene co-expression network analysis identified four molecular signatures in monocytes from pSS patients, functionally annotated for processes related with translation, IFN-signaling, and toll like receptor signaling. Systemic and local inflammatory features significantly correlated with the expression of these signatures. Furthermore, genes highly associated with clinical features in pSS were identified as hub-genes for each signature. Unsupervised hierarchical cluster analysis of the hub-genes identified four clusters of nSS and pSS patients, each with distinct inflammatory and transcriptomic profiles. One cluster showed a significantly higher percentage of pSS patients with higher prevalence of anti-SSA autoantibodies, interferon score, and erythrocyte sedimentation rate compared to the other clusters. Finally, we showed that the identified transcriptomic differences in pSS monocytes were induced in monocytes of healthy controls by exposure to serum of pSS patients. Representative hub-genes of all four signatures were partially inhibited by interferon-a/b receptor blockade, indicating that the circulating inflammatory mediators, including type I interferons have a significant contribution to the altered transcriptional profile of pSS-monocytes. Our study suggests that targeting key circulating inflammatory mediators, such as type I interferons, could offer new insights into the important pathways and mechanisms driving pSS, and holds promise for halting immunopathology in Sjögren’s Syndrome.

Project description:To identify potential dysregulation of miRNA expression in plasmacytoid dendritic cells from Systemic Sclerosis patients (SSc), miRNA profiling was performed in pDCs from healthy donors or patients with the most severe fibrotic cutaneous form of SSc, namely in dcSSc, with either disease duration shorter (edcSSc) or longer than two years (ldcSSc). Plasmacytoid dendritic cells (pDCs) are a critical source of type I interferons (IFNs) that can contribute to the onset and maintenance of autoimmunity. Molecular mechanisms leading to pDC dysregulation and persistent type I IFN signature are largely unexplored, especially in systemic sclerosis (SSc), a disease in which pDCs infiltrate fibrotic skin lesions and produce higher levels of IFNa as compared to healthy controls. To investigate potential microRNA–mediated epigenetic mechanisms underlying pDC dysregulation and type I IFN production in SSc. microRNA expression profiling and validation was performed in highly purified pDCs obtained from the peripheral blood of 3 independent cohorts of healthy controls and SSc patients. Possible functions of miR-618 on pDC biology were identified by overexpression in healthy pDCs. miR-618 expression was upregulated in pDCs of SSc patients, including those in the early stage of disease onset and not presenting with skin fibrosis. IRF8, a crucial transcription factor for pDC development and activation, was identified as a target of miR-618. miR-618 overexpression reduced the development of pDCs from CD34+ cells in-vitro and enhanced their ability to secrete IFNα, mimicking the pDC phenotype observed in SSc patients. miR-618 upregulation suppresses pDC development and increases their ability to secrete IFNα, potentially contributing to the type I IFN signature observed in SSc patients. Considering the importance of pDCs in the pathogenesis of SSc and other diseases characterized by a type I IFN signature, miR-618 potentially represents an important epigenetic target to regulate immune system homeostasis in these conditions.

Dataset Information

RNA-sequencing in plasmacytoid dendritic cells from patients with primary Sjogren's syndrome (pSS), non-Sjogren's sicca (nSS), and healthy donors (HC)

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