Molecular Characterization of Human Lymph Node Stromal Cells During the Earliest Phases of Rheumatoid Arthritis.

Emmanuel Karouzakis,Paul P Tak,Cristoforo Grasso,Steffen Gay,Lisa G M Van Baarsen,Caroline Ospelt,Johanna F Semmelink,Janine Hähnlein,Danielle M Gerlag

doi:10.3389/fimmu.2019.01863

Abstract

Rheumatoid arthritis (RA) is a progressive, destructive autoimmune arthritis. Break of tolerance and formation of autoantibodies occur years before arthritis. Adaptive immunity is initiated in lymphoid tissue where lymph node stromal cells (LNSCs) play a crucial role in shaping the immune response and maintaining peripheral tolerance. Here we performed the first epigenomic characterization of LNSCs during health and early RA, by analyzing their transcriptome and DNA methylome in LNSCs isolated from lymph node needle biopsies obtained from healthy controls (HC), autoantibody positive RA-risk individuals and patients with established RA. Of interest, LNSCs from RA-risk individuals and RA patients revealed a common significantly differential expressed gene signature compared with HC LNSCs. Pathway analysis of this common signature showed, among others, significant enrichment of pathways affecting the extracellular matrix (ECM), cholesterol biosynthesis and immune system. In a gel contraction assay LNSCs from RA-risk individuals and RA patients showed impaired collagen contraction compared to healthy LNSCs. In RA LNSCs a significant enrichment was observed for genes involved in cytokine signaling, hemostasis and packaging of telomere ends. In contrast, in RA-risk LNSCs pathways in cancer (cell cycle related genes) were differentially expressed compared with HC, which could be validated in vitro using a proliferation assay, which indicated a slower proliferation rate. DNA methylation analyses revealed common and specific differentially methylated CpG sites (DMS) in LNSC from RA patients and RA-risk individuals compared with HC. Intriguingly, shared DMS were all associated with antigen processing and presentation. This data point toward alterations in cytoskeleton and antigen-processing and presentation in LNSC from RA-risk individuals and RA patients. Further studies are required to investigate the consequence of this LNSC abnormality on LNSC-mediated immunomodulation.

Highlights

Rheumatoid arthritis (RA) is a progressive, destructive autoimmune disease of which the etiology is only partly understood
In an earlier study we showed that expanded human lymph node stromal cells (LNSCs) are capable of producing these key chemokines upon stimulation, with lower induction observed in RA LNSCs [16]
We demonstrate that cultured human LNSCs show a comparable expression profile to mouse LNSCs, suggesting that the reported functional role of mouse LNSCs is potentially operational in humans

Summary

Introduction

Rheumatoid arthritis (RA) is a progressive, destructive autoimmune disease of which the etiology is only partly understood. Studies in mice revealed that lymph node stromal cells (LNSCs) are crucial regulators of adaptive immunity and highlighted their various abilities to shape T and B cell responses [9, 10]. They orchestrate trafficking of immune cells within the LN [11, 12], control lymphocyte activation, differentiation and survival [9], but can inhibit T cell proliferation [13, 14] and maintain peripheral tolerance [13, 15]. This group of LNSCs contains follicular dendritic cells (FDCs) and other, less well described LNSC subtypes

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Results

Conclusion