Human Lymph Node Stromal Cells Have the Machinery to Regulate Peripheral Tolerance during Health and Rheumatoid Arthritis.

BACKGROUND: In rheumatoid arthritis (RA) the cause for loss of tolerance and anti-citrullinated protein antibody (ACPA) production remains unidentified. Mouse studies showed that lymph node stromal cells (LNSCs) maintain peripheral tolerance through presentation of peripheral tissue antigens (PTAs). We hypothesize that dysregulation of peripheral tolerance mechanisms in human LNSCs might underlie pathogenesis of RA. METHOD: Lymph node (LN) needle biopsies were obtained from 24 RA patients, 23 individuals positive for RA-associated autoantibodies but without clinical disease (RA-risk individuals), and 14 seronegative healthy individuals. Ex vivo human LNs from non-RA individuals were used to directly analyze stromal cells. Molecules involved in antigen presentation and immune modulation were measured in LNSCs upon interferon γ (IFNγ) stimulation (n = 15). RESULTS: Citrullinated targets of ACPAs were detected in human LN tissue and in cultured LNSCs. Human LNSCs express several PTAs, transcription factors autoimmune regulator (AIRE) and deformed epidermal autoregulatory factor 1 (DEAF1), and molecules involved in citrullination, antigen presentation, and immunomodulation. Overall, no clear differences between donor groups were observed with exception of a slightly lower induction of human leukocyte antigen-DR (HLA-DR) and programmed cell death 1 ligand (PD-L1) molecules in LNSCs from RA patients. CONCLUSION: Human LNSCs have the machinery to regulate peripheral tolerance making them an attractive target to exploit in tolerance induction and maintenance

Pharmacogenomics of Interferon-ß Therapy in Multiple Sclerosis: Baseline IFN Signature Determines Pharmacological Differences between Patients

Multiple sclerosis (MS) is a heterogeneous disease. In order to understand the partial responsiveness to IFNbeta in Relapsing Remitting MS (RRMS) we studied the pharmacological effects of IFNbeta therapy. Large scale gene expression profiling was performed on peripheral blood of 16 RRMS patients at baseline and one month after the start of IFNbeta therapy. Differential gene expression was analyzed by Significance Analysis of Microarrays. Subsequent expression analyses on specific genes were performed after three and six months of treatment. Peripheral blood mononuclear cells (PBMC) were isolated and stimulated in vitro with IFNbeta. Genes of interest were measured and validated by quantitative realtime PCR. An independent group of 30 RRMS patients was used for validation. Pharmacogenomics revealed a marked variation in the pharmacological response to IFNbeta between patients. A total of 126 genes were upregulated in a subset of patients whereas in other patients these genes were downregulated or unchanged after one month of IFNbeta therapy. Most interestingly, we observed that the extent of the pharmacological response correlates negatively with the baseline expression of a specific set of 15 IFN response genes (R = -0.7208; p = 0.0016). The negative correlation was maintained after three (R = -0.7363; p = 0.0027) and six (R = -0.8154; p = 0.0004) months of treatment, as determined by gene expression levels of the most significant correlating gene. Similar results were obtained in an independent group of patients (n = 30; R = -0.4719; p = 0.0085). Moreover, the ex vivo results could be confirmed by in vitro stimulation of purified PBMCs at baseline with IFNbeta indicating that differential responsiveness to IFNbeta is an intrinsic feature of peripheral blood cells at baseline. These data imply that the expression levels of IFN response genes in the peripheral blood of MS patients prior to treatment could serve a role as biomarker for the differential clinical response to IFNbet

EULAR recommendations for terminology and research in individuals at risk of rheumatoid arthritis: report from the Study Group for Risk Factors for Rheumatoid Arthritis

The Study Group for Risk Factors for Rheumatoid Arthritis was established by the EULAR Standing Committee on Investigative Rheumatology to facilitate research into the preclinical and earliest clinically apparent phases of rheumatoid arthritis (RA). This report describes the recommendation for terminology to be used to define specific subgroups during different phases of disease, and defines the priorities for research in this area. Terminology was discussed by way of a three-stage structured process: A provisional list of descriptors for each of the possible phases preceding the diagnosis of RA were circulated to members of the study group for review and feedback. Anonymised comments from the members on this list were fed back to participants before a 2-day meeting. 18 participants met to discuss these data, agree terminologies and prioritise important research questions. The study group recommended that, in prospective studies, individuals without RA are described as having: genetic risk factors for RA; environmental risk factors for RA; systemic autoimmunity associated with RA; symptoms without clinical arthritis; unclassified arthritis; which may be used in a combinatorial manner. It was recommended that the prefix ‘pre-RA with:’ could be used before any/any combination of the five points above but only to describe retrospectively a phase that an individual had progressed through once it was known that they have developed RA. An approach to dating disease onset was recommended. In addition, important areas for research were proposed, including research of other tissues in which an adaptive immune response may be initiated, and the identification of additional risk factors and biomarkers for the development of RA, its progression and the development of extra-articular features. These recommendations provide guidance on approaches to describe phases before the development of RA that will facilitate communication between researchers and comparisons between studies. A number of research questions have been defined, requiring new cohorts to be established and new techniques to be developed to image and collect material from different sites

Tertiary Lymphoid Structures: Diversity in Their Development, Composition, and Role

Lymph node stromal cells coordinate the adaptive immune response in secondary lymphoid organs, providing both a structural matrix and soluble factors that regulate survival and migration of immune cells, ultimately promoting Ag encounter. In several inflamed tissues, resident fibroblasts can acquire lymphoid-stroma properties and drive the formation of ectopic aggregates of immune cells, named tertiary lymphoid structures (TLSs). Mature TLSs are functional sites for the development of adaptive responses and, consequently, when present, can have an impact in both autoimmunity and cancer conditions. In this review, we go over recent findings concerning both lymph node stromal cells and TLSs function and formation and further describe what is currently known about their role in disease, particularly their potential in tolerance

JNK-dependent downregulation of FoxO1 is required to promote the survival of fibroblast-like synoviocytes in rheumatoid arthritis.

Forkhead box O (FoxO) transcription factors integrate environmental signals to modulate cell proliferation and survival, and alterations in FoxO function have been reported in rheumatoid arthritis (RA). To examine the relationship between inflammation and FoxO expression in RA, and to analyse the mechanisms and biological consequences of FoxO regulation in RA fibroblast-like synoviocytes (FLS). RNA was isolated from RA patient and healthy donor (HD) peripheral blood and RA synovial tissue. Expression of FoxO1, FoxO3a and FoxO4 was measured by quantitative PCR. FoxO1 DNA binding, expression and mRNA stability in RA FLS were measured by ELISA-based assays, immunoblotting and quantitative PCR. FLS were transduced with adenovirus encoding constitutively active FoxO1 (FoxO1ADA) or transfected with small interfering RNA targeting FoxO1 to examine the effects on cell viability and gene expression. FoxO1 mRNA levels were reduced in RA patient peripheral blood compared with HD blood, and RA synovial tissue FoxO1 expression correlated negatively with disease activity. RA FLS stimulation with interleukin 1β or tumour necrosis factor caused rapid downregulation of FoxO1. This effect was independent of protein kinase B (PKB), but dependent on c-Jun N-terminal kinase (JNK)-mediated acceleration of FoxO1 mRNA degradation. FoxO1ADA overexpression in RA FLS induced apoptosis associated with altered expression of genes regulating cell cycle and survival, including BIM, p27(Kip1) and Bcl-XL. Our findings identify JNK-dependent modulation of mRNA stability as an important PKB-independent mechanism underlying FoxO1 regulation by cytokines, and suggest that reduced FoxO1 expression is required to promote FLS survival in R

Interleukin 1 receptor antagonist mediates the beneficial effects of systemic interferon beta in mice: implications for rheumatoid arthritis

Objectives Interferon beta (IFN beta) therapy is effective in multiple sclerosis and murine models of arthritis. Surprisingly, systemic IFN beta treatment induces only minimal improvement in rheumatoid arthritis (RA). To explain this paradox, the authors evaluated the mechanism of IFN beta benefit in passive K/BxN arthritis and the effect of IFN beta treatment on RA synovium. Methods Interleukin 10 (IL-10) null, IL-1 receptor antagonist (IL-1Ra) null, IL-1Ra transgenic and wildtype mice were administered K/BxN serum and in some cases treated with IFN beta or normal saline. Clinical response and histological scores were assessed. Gene expression was measured by quantitative PCR. Serum IL-1Ra and IL-6 were measured by ELISA. Paired synovial biopsy specimens from RA patients pre-IFN beta and post-IFN beta treatment (purified natural fibroblast IFN beta (Frone) subcutaneously three times weekly 6 million IU, 12 million IU or 18 million IU) were immunostained for IL-1Ra and IL-10. Results Il1rn transgenic mice had an attenuated course of arthritis, whereas Il1rn(-/-) and Il10(-/-) mice had more severe serum transfer arthritis than wild-type mice. Daily IFN beta treatment significantly decreased arthritis severity in Il10(-/-) but not Il1rn(-/-) mice. IFN beta treatment did not reduce the histological scores in Il1rn(-/-) mice or gene expression of articular cytokines and chemokines. Paired synovial biopsy specimens from RA patients treated with IFN beta demonstrated a trend towards increased IL-1Ra and reduced IL-10 expression on day 85 levels compared with pretreatment specimens. Conclusions The anti-inflammatory effects of IFN beta in passive K/BxN arthritis are dependent on IL-1Ra, but not IL-10. Systemic IFN beta treatment in RA increases synovial IL-1Ra production, but also decreases IL-10 productio

Smoking and overweight determine the likelihood of developing rheumatoid arthritis

Rheumatoid arthritis (RA) is a prototypic chronic inflammatory disease with a debilitating course if untreated. A genetic predisposition for RA is known, and its occurrence is associated with the presence of autoantibodies in the serum and with environmental factors. It is unknown if smoking and overweight are contributory factors for developing RA in individuals with RA-specific autoantibodies in the serum. Fifty-five individuals at risk for developing RA, based on the presence of RA-specific autoantibodies in the serum, who never had any evidence of arthritis upon physical examination, were followed over time. Smoking was assessed as being never or ever smoker and body mass index as <25 (normal) or ≥25 kg/m² (overweight). Clinical endpoint was the occurrence of arthritis. Proportional hazard regression analysis was performed to investigate the potential of (combinations of) variables in predicting the onset of arthritis over time. After a median follow up time of 13 (IQR 6-27) months, 15 individuals (27%) developed arthritis. Smoking was associated with the development of arthritis (HR (95% CI): 9.6 (1.3 to 73.0); p=0.029). Overweight was, independently of smoking, associated with arthritis (HR (95% CI): 5.6 (1.3 to 25.0); p=0.023). The overall arthritis risk of 28% after a median of 27 months follow up increased to 60% in individuals with a smoking history combined with overweight. This is the first prospective study showing that smoking and overweight increase the risk of development of arthritis in a cohort of autoantibody-positive individuals at risk for developing RA. These results show the importance of life style factors in development of RA and should be critically evaluated in future clinical research aimed at disease preventio

Human keratinocytes express functional Toll-like receptor 3, 4, 5, and 9

Keratinocytes are continuously in contact with external stimuli and have the capacity to produce several soluble mediators. Pathogen-associated molecular patterns (PAMPs) are recognized, among others, by Toll-like receptors (TLRs). The functional responses of keratinocytes to different PAMPs have not yet been fully established. Here we show that keratinocytes constitutively express TLR1, 2, 3, 4, 5, 6, 9, and 10 mRNA, but not TLR7 and 8. Stimulation of keratinocytes with TLR3, 4, 5, and 9 ligands resulted in differential immune-associated responses. Tumor necrosis factor-alpha, CXC chemokine ligand 8 (CXCL8), CCL2, and C chemokine ligand 20 (CCL20) release was enhanced in response to all PAMPs tested, in a time- and dose-dependent manner. Only TLR9 ligand CpG-oligodeoxynucleotides (ODNs) and TLR3 ligand poly-I:C could additionally induce type I IFNs. CCL27 production was selectively induced by poly-I:C and flagellin, whereas CXCL9 and CXCL10 were exclusively induced by CpG-ODNs and/or poly-I:C. Upregulation of ICAM-1, HLA-DR, HLA-ABC, FasR, and CD40 was mainly observed in response to poly-I:C, flagellin, and lipopolysaccharide. Furthermore, PAMP triggering resulted in the phosphorylation of phosphorylated-IkappaB alpha and in the nucleus translocation of NF-kappaB p65. Altogether, these findings stress an unexpectedly multifaceted role of keratinocytes in innate immunity as evident by their differential, TLR-mediated responses to PAMPs associated with different classes of pathogen

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

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 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