Serum and Tissue Biomarkers Associated With Composite of Relevant Endpoints for Sjögren Syndrome (CRESS) and Sjögren Tool for Assessing Response (STAR) to B Cell-Targeted Therapy in the Trial of Anti-B Cell Therapy in Patients With Primary Sjögren Syndrome (TRACTISS)

OBJECTIVE

This study aimed to identify peripheral and salivary gland (SG) biomarkers of response/resistance to B cell depletion based on the novel concise Composite of Relevant Endpoints for Sjögren Syndrome (cCRESS) and candidate Sjögren Tool for Assessing Response (STAR) composite endpoints.

METHODS

Longitudinal analysis of peripheral blood and SG biopsies was performed pre- and post-treatment from the Trial of Anti-B Cell Therapy in Patients With Primary Sjögren Syndrome (TRACTISS) combining flow cytometry immunophenotyping, serum cytokines, and SG bulk RNA sequencing.

RESULTS

Rituximab treatment prevented the worsening of SG inflammation observed in the placebo arm, by inhibiting the accumulation of class-switched memory B cells within the SG. Furthermore, rituximab significantly down-regulated genes involved in immune-cell recruitment, lymphoid organization alongside antigen presentation, and T cell co-stimulatory pathways. In the peripheral compartment, rituximab down-regulated immunoglobulins  and auto-antibodies together with pro-inflammatory cytokines and chemokines. Interestingly, patients classified as responders  according to STAR displayed significantly higher baseline levels of C-X-C motif chemokine ligand-13 (CXCL13), interleukin (IL)-22, IL-17A, IL-17F, and tumor necrosis factor-α (TNF-α), whereas a longitudinal analysis of serum T cell-related cytokines showed a selective reduction in both STAR and cCRESS responder patients. Conversely, cCRESS response was better associated with biomarkers of SG immunopathology, with cCRESS-responders showing a significant decrease in SG B cell infiltration and reduced expression of transcriptional gene modules related to T cell costimulation, complement activation, and Fcγ-receptor engagement. Finally, cCRESS and STAR response were associated with a significant improvement in SG exocrine function linked to transcriptional evidence of SG epithelial and metabolic restoration.

CONCLUSION

Rituximab modulates both peripheral and SG inflammation, preventing the deterioration of exocrine function with functional and metabolic restoration of the glandular epithelium. Response assessed by newly developed cCRESS and STAR criteria was associated with differential modulation of peripheral and SG biomarkers, emerging as novel tools for patient stratification.

Molecular portrait of chronic joint diseases: Defining endotypes toward personalized medicine

Joint diseases affect hundreds of millions of people worldwide, and their prevalence is constantly increasing. To date, despite recent advances in the development of therapeutic options for most rheumatic conditions, a significant proportion of patients still lack efficient disease management, considerably impacting their quality of life. Through the spectrum of rheumatoid arthritis (RA), psoriatic arthritis (PsA), and osteoarthritis (OA) as quintessential and common rheumatic diseases, this review first provides an overview of their epidemiological and clinical features before exploring how the better definition of clinical phenotypes has helped their clinical management. It then discusses the recent progress in understanding the diversity of endotypes underlying disease phenotypes. Finally, this review highlights the current challenges of implementing molecular endotypes towards the personalized management of RA, PsA and OA patients in the future.

Clinical Phenotypes, Serological Biomarkers, and Synovial Features Defining Seropositive and Seronegative Rheumatoid Arthritis: A Literature Review

Rheumatoid arthritis (RA) is a chronic autoimmune disorder which can lead to long-term joint damage and significantly reduced quality of life if not promptly diagnosed and adequately treated. Despite significant advances in treatment, about 40% of patients with RA do not respond to individual pharmacological agents and up to 20% do not respond to any of the available medications. To address this large unmet clinical need, several recent studies have focussed on an in-depth histological and molecular characterisation of the synovial tissue to drive the application of precision medicine to RA. Currently, RA patients are clinically divided into "seropositive" or "seronegative" RA, depending on the presence of routinely checked antibodies. Recent work has suggested that over the last two decades, long-term outcomes have improved significantly in seropositive RA but not in seronegative RA. Here, we present up-to-date differences in epidemiology, clinical features, and serological biomarkers in seronegative versus seropositive RA and discuss how histological and molecular synovial signatures, revealed by recent large synovial biopsy-based clinical trials, may be exploited to refine the classification of RA patients, especially in the seronegative group.

Axl and MerTK regulate synovial inflammation and are modulated by IL-6 inhibition in rheumatoid arthritis

The TAM tyrosine kinases, Axl and MerTK, play an important role in rheumatoid arthritis (RA). Here, using a unique synovial tissue bioresource of patients with RA matched for disease stage and treatment exposure, we assessed how Axl and MerTK relate to synovial histopathology and disease activity, and their topographical expression and longitudinal modulation by targeted treatments. We show that in treatment-naive patients, high AXL levels are associated with pauci-immune histology and low disease activity and inversely correlate with the expression levels of pro-inflammatory genes. We define the location of Axl/MerTK in rheumatoid synovium using immunohistochemistry/fluorescence and digital spatial profiling and show that Axl is preferentially expressed in the lining layer. Moreover, its ectodomain, released in the synovial fluid, is associated with synovial histopathology. We also show that Toll-like-receptor 4-stimulated synovial fibroblasts from patients with RA modulate MerTK shedding by macrophages. Lastly, Axl/MerTK synovial expression is influenced by disease stage and therapeutic intervention, notably by IL-6 inhibition. These findings suggest that Axl/MerTK are a dynamic axis modulated by synovial cellular features, disease stage and treatment.

Comparative analysis of late-stage rheumatoid arthritis and osteoarthritis reveals shared histopathological features

OBJECTIVES

Osteoarthritis (OA) is a debilitating and heterogeneous condition, characterized by various levels of articular cartilage degradation, osteophytes formation, and synovial inflammation. Multiple evidences suggest that synovitis may appear early in the disease development and correlates with disease severity and pain, therefore representing a relevant therapeutic target. In a typical synovitis-driven joint disease, namely rheumatoid arthritis (RA), several pathotypes have been described by our group and associated with clinical phenotypes, disease progression, and response to therapy. However, whether these pathotypes can be also observed in the OA synovium is currently unknown.

METHODS

Here, using histological approaches combined with semi-quantitative scoring and quantitative digital image analyses, we comparatively characterize the immune cell infiltration in a large cohort of OA and RA synovial tissue samples collected at the time of total joint replacement.

RESULTS

We demonstrate that OA synovium can be categorized also into three pathotypes and characterized by disease- and stage-specific features. Moreover, we revealed that pathotypes specifically reflect distinct levels of peripheral inflammation.

CONCLUSIONS

In this study, we provide a novel and relevant pathological classification of OA synovial inflammation. Further studies investigating synovial molecular pathology in OA may contribute to the development of disease-modifying therapies.

Deconstruction of rheumatoid arthritis synovium defines inflammatory subtypes

Rheumatoid arthritis is a prototypical autoimmune disease that causes joint inflammation and destruction1. There is currently no cure for rheumatoid arthritis, and the effectiveness of treatments varies across patients, suggesting an undefined pathogenic diversity1,2. Here, to deconstruct the cell states and pathways that characterize this pathogenic heterogeneity, we profiled the full spectrum of cells in inflamed synovium from patients with rheumatoid arthritis. We used multi-modal single-cell RNA-sequencing and surface protein data coupled with histology of synovial tissue from 79 donors to build single-cell atlas of rheumatoid arthritis synovial tissue that includes more than 314,000 cells. We stratified tissues into six groups, referred to as cell-type abundance phenotypes (CTAPs), each characterized by selectively enriched cell states. These CTAPs demonstrate the diversity of synovial inflammation in rheumatoid arthritis, ranging from samples enriched for T and B cells to those largely lacking lymphocytes. Disease-relevant cell states, cytokines, risk genes, histology and serology metrics are associated with particular CTAPs. CTAPs are dynamic and can predict treatment response, highlighting the clinical utility of classifying rheumatoid arthritis synovial phenotypes. This comprehensive atlas and molecular, tissue-based stratification of rheumatoid arthritis synovial tissue reveal new insights into rheumatoid arthritis pathology and heterogeneity that could inform novel targeted treatments.

Stratification of biological therapies by pathobiology in biologic-naive patients with rheumatoid arthritis (STRAP and STRAP-EU): two parallel, open-label, biopsy-driven, randomised trials

BACKGROUND

Despite highly effective targeted therapies for rheumatoid arthritis, about 40% of patients respond poorly, and predictive biomarkers for treatment choices are lacking. We did a biopsy-driven trial to compare the response to rituximab, etanercept, and tocilizumab in biologic-naive patients with rheumatoid arthritis stratified for synovial B cell status.

METHODS

STRAP and STRAP-EU were two parallel, open-label, biopsy-driven, stratified, randomised, phase 3 trials done across 26 university centres in the UK and Europe. Biologic-naive patients aged 18 years or older with rheumatoid arthritis based on American College of Rheumatology (ACR)-European League Against Rheumatism classification criteria and an inadequate response to conventional synthetic disease-modifying antirheumatic drugs (DMARDs) were included. Following ultrasound-guided synovial biopsy, patients were classified as B cell poor or B cell rich according to synovial B cell signatures and randomly assigned (1:1:1) to intravenous rituximab (1000 mg at week 0 and week 2), subcutaneous tocilizumab (162 mg per week), or subcutaneous etanercept (50 mg per week). The primary outcome was the 16-week ACR20 response in the B cell-poor, intention-to-treat population (defined as all randomly assigned patients), with data pooled from the two trials, comparing etanercept and tocilizumab (grouped) versus rituximab. Safety was assessed in all patients who received at least one dose of study drug. These trials are registered with the EU Clinical Trials Register, 2014-003529-16 (STRAP) and 2017-004079-30 (STRAP-EU).

FINDINGS

Between June 8, 2015, and July 4, 2019, 226 patients were randomly assigned to etanercept (n=73), tocilizumab (n=74), and rituximab (n=79). Three patients (one in each group) were excluded after randomisation because they received parenteral steroids in the 4 weeks before recruitment. 168 (75%) of 223 patients in the intention-to-treat population were women and 170 (76%) were White. In the B cell-poor population, ACR20 response at 16 weeks (primary endpoint) showed no significant differences between etanercept and tocilizumab grouped together and rituximab (46 [60%] of 77 patients vs 26 [59%] of 44; odds ratio 1·02 [95% CI 0·47-2·17], p=0·97). No differences were observed for adverse events, including serious adverse events, which occurred in six (6%) of 102 patients in the rituximab group, nine (6%) of 108 patients in the etanercept group, and three (4%) of 73 patients in the tocilizumab group (p=0·53).

INTERPRETATION

In this biologic-naive population of patients with rheumatoid arthrtitis, the dichotomic classification into synovial B cell poor versus rich did not predict treatment response to B cell depletion with rituximab compared with alternative treatment strategies. However, the lack of response to rituximab in patients with a pauci-immune pathotype and the higher risk of structural damage progression in B cell-rich patients treated with rituximab warrant further investigations into the ability of synovial tissue analyses to inform disease pathogenesis and treatment response.

FUNDING

UK Medical Research Council and Versus Arthritis.

Synovial Inflammatory Pathways Characterize Anti-TNF-Responsive Rheumatoid Arthritis Patients

OBJECTIVE

This study was undertaken to understand the mechanistic basis of response to anti-tumor necrosis factor (anti-TNF) therapies and to determine whether transcriptomic changes in the synovium are reflected in peripheral protein markers.

METHODS

Synovial tissue from 46 rheumatoid arthritis (RA) patients was profiled with RNA sequencing before and 12 weeks after treatment with anti-TNF therapies. Pathway and gene signature analyses were performed on RNA expression profiles of synovial biopsies to identify mechanisms that could discriminate among patients with a good response, a moderate response, or no response, according to the American College of Rheumatology (ACR)/EULAR response criteria. Serum proteins encoded by synovial genes that were differentially expressed between ACR/EULAR response groups were measured in the same patients.

RESULTS

Gene signatures predicted which patients would have good responses, and pathway analysis identified elevated immune pathways, including chemokine signaling, Th1/Th2 cell differentiation, and Toll-like receptor signaling, uniquely in good responders. These inflammatory pathways were correspondingly down-modulated by anti-TNF therapy only in good responders. Based on cell signature analysis, lymphocyte, myeloid, and fibroblast cell populations were elevated in good responders relative to nonresponders, consistent with the increased inflammatory pathways. Cell signatures that decreased following anti-TNF treatment were predominately associated with lymphocytes, and fewer were associated with myeloid and fibroblast populations. Following anti-TNF treatment, and only in good responders, several peripheral inflammatory proteins decreased in a manner that was consistent with corresponding synovial gene changes.

CONCLUSION

Collectively, these data suggest that RA patients with robust responses to anti-TNF therapies are characterized at baseline by immune pathway activation, which decreases following anti-TNF treatment. Understanding mechanisms that define patient responsiveness to anti-TNF treatment may assist in development of predictive markers of patient response and earlier treatment options.

POS0145 CLINICAL RESPONSE TO RITUXIMAB IS ASSOCIATED WITH PREVENTION OF B-CELL DRIVEN SALIVARY GLAND INFLAMMATION AND EPITHELIAL RESTORATION AS REVEALED BY MOLECULAR PATHOLOGY: RESULTS FROM THE TRACTISS TRIAL IN PRIMARY SJOGREN’S SYNDROME

Background

The TRial for Anti-B-Cell Therapy In patients with pSS (TRACTISS) is the largest multi-centre, placebo-controlled, phase-III trial with the administration of 2 cycles of Rituximab (RTX) or placebo at week 0 and 24, with trial clinical endpoints at week 48. Despite the primary endpoints (30% reduction in fatigue or oral dryness) were not met, RTX treated patients showed an improvement in secondary endpoints, such as unstimulated whole salivary flow (UWSF), and salivary gland (SG) total ultrasound score1,2. Additionally, recent post-hoc analysis of TRACTISS using novel CRESS composite endpoints3, highlighted a significantly increased response rate in the RTX vs placebo arm.

Objectives

To perform the first longitudinal analysis of matched transcriptomic and histological data of SG biopsies of pSS patients treated with RTX vs placebo at 3 time points, over 48 weeks, from the TRACTISS cohort, in order to identify mechanisms of response/resistance to B cell depletion.

Methods

29 pSS patients randomised to RTX or placebo arm consented for labial SG biopsies at week 0, 16 and 48. Patients received two 1000mg cycles of RTX or placebo at week 0 and 24. SG focus score, inflammatory aggregate area fraction, B-cells (CD20+), T-cells (CD3+), follicular dendritic cells (FDCs) (CD21+) and plasma cells (CD138+) density were assessed using quantitative digital image analysis. RNA sequencing with deconvolution and pathway analysis was performed to identify genes signatures and consensus gene modules as biomarkers of disease evolution and response/resistance to therapy.

Results

Placebo-treated SGs showed worsening of SG inflammation highlighted by the increment of aggregate size, B-cell density, development of new FDC networks, and a higher ectopic GC prevalence over 48 weeks, compared to RTX-treated patients. No difference in focus score, total T-cell and plasma cell infiltration was observed. RTX downregulated genes involved in immune cell recruitment and inflammatory aggregate organisation (e.g. CXCL13, CCR7 and PDCD1). Gene signature-based analysis of 35 immune cell types using XCell highlighted how RTX blocked class-switched and memory-B-cells accumulation in SGs over 48 weeks. Pathway analyses confirmed the downregulation of leukocyte migration, MHC-II antigen presentation, and T-cell co-stimulation immunological pathways, such as the CD40 receptor complex pathway. Among RTX-treated patients, only CRESS-responders demonstrated prevention of worsening B cell-driven molecular pathology signatures over time and a significant improvement in UWSF, in parallel with the upregulation of molecular pathways associated to SG restoration of the glandular epithelium. None of the above effects were observed at week 16 after the first RTX cycle.

Conclusion

Two RTX infusions repeated at week 24 exerted beneficial effects on labial SG inflammatory infiltration in pSS by downregulating genes involved in immune cell recruitment, activation and organisation in ectopic GCs. Conversely, all the above parameters showed significant evolution in placebo treated patients over 48 weeks demonstrating progression of SG immunopathology. Clinical responders to RTX based on CRESS response criteria were characterised by preservation of exocrine function which appear driven by SG epithelial restoration.

References

[1]Fisher, B. A. et al. Effect of rituximab on a salivary gland ultrasound score in primary Sjögren’s syndrome: results of the TRACTISS randomised double-blind multicentre substudy. Ann. Rheum. Dis.77, 412–416 (2018).

[2]Bowman, S. J. et al. Randomized Controlled Trial of Rituximab and Cost-Effectiveness Analysis in Treating Fatigue and Oral Dryness in Primary Sjögren’s Syndrome. Arthritis Rheumatol.69, 1440–1450 (2017).

[3]Arends, S. et al. Composite of Relevant Endpoints for Sjögren’s Syndrome (CRESS): development and validation of a novel outcome measure. Lancet Rheumatol.3, e553–e562 (2021).

Disclosure of Interests

None declared

Rituximab versus tocilizumab in rheumatoid arthritis: synovial biopsy-based biomarker analysis of the phase 4 R4RA randomized trial

Patients with rheumatoid arthritis (RA) receive highly targeted biologic therapies without previous knowledge of target expression levels in the diseased tissue. Approximately 40% of patients do not respond to individual biologic therapies and 5-20% are refractory to all. In a biopsy-based, precision-medicine, randomized clinical trial in RA (R4RA; n = 164), patients with low/absent synovial B cell molecular signature had a lower response to rituximab (anti-CD20 monoclonal antibody) compared with that to tocilizumab (anti-IL6R monoclonal antibody) although the exact mechanisms of response/nonresponse remain to be established. Here, in-depth histological/molecular analyses of R4RA synovial biopsies identify humoral immune response gene signatures associated with response to rituximab and tocilizumab, and a stromal/fibroblast signature in patients refractory to all medications. Post-treatment changes in synovial gene expression and cell infiltration highlighted divergent effects of rituximab and tocilizumab relating to differing response/nonresponse mechanisms. Using ten-by-tenfold nested cross-validation, we developed machine learning algorithms predictive of response to rituximab (area under the curve (AUC) = 0.74), tocilizumab (AUC = 0.68) and, notably, multidrug resistance (AUC = 0.69). This study supports the notion that disease endotypes, driven by diverse molecular pathology pathways in the diseased tissue, determine diverse clinical and treatment-response phenotypes. It also highlights the importance of integration of molecular pathology signatures into clinical algorithms to optimize the future use of existing medications and inform the development of new drugs for refractory patients.

OP0085 CELL LINEAGE-SPECIFIC TRANSCRIPT DECONVOLUTION OF SYNOVIAL BIOPSIES FROM THE R4RA TRIAL IDENTIFIES CELL POPULATIONS ASSOCIATED WITH RESPONSE TO RITUXIMAB AND TOCILIZUMAB

Background

The R4RA trial, the first biopsy-based randomised trial in TNF-i inadequate responder patients with Rheumatoid Arthritis, showed that molecular stratification of RA synovial tissue was associated with clinical response, demonstrating that, in patients with low/absent B-cell lineage signature in synovial-tissue, tocilizumab is superior to rituximab1.

Objectives

Here, we aimed to perform cell-transcript deconvolution of pre-and post-treatment synovial biopsies from the R4RA trial.

Methods

A total of 164 patients underwent pre-treatment synovial biopsy (US-guided or arthroscopic) prior to randomization 1:1 to rituximab (83) or tocilizumab (81). 65 patients had a repeat biopsy at 16 weeks when clinical response was assessed using Clinical Disease Activity Index (CDAI) 50% improvement. RNA extracted from a minimum of 6 synovial samples/patient underwent RNA-sequencing and the abundance of tissue-infiltrating immune and stromal cell populations was estimated using the Microenvironment Cell Populations-counter (MCP-counter) method (Figure 1a).

Results

At baseline, while synovial semiquantitative immunohistochemistry scores did not differ between CDAI50% responders and non-responders, both for rituximab and tocilizumab, MCP-counter analysis showed significantly higher CD8 T-cells in responders to rituximab and higher macrophage-monocytes and myeloid dendritic cells (mDC) in responders to tocilizumab (Figure 1b). Moreover, when patients were classified according to MCP-counter scores, B-cell poor patients (MCP-counter B cell score <median value) showed significantly higher response rates to tocilizumab, while no difference was found in B-cell rich patients (Figure 1c). In contrast, macrophage and myeloid dendritic cell (mDC) rich individuals showed higher responses to tocilizumab (Figure 1d). Combined scores for lymphoid and myeloid cells demonstrated that patients poor in B-cells but rich in macrophages/mDC had a significantly higher response to tocilizumab (77% responders to tocilizumab vs 14% responders to rituximab, p=0.017, OR 16.48, 95%CI 1.29-1000.5) (Figure 1e). By analysing disease activity over time from baseline to week 16, we found a statistically significant interaction effect between treatments and time in B-cell poor (p=0.003), T-cell poor (p=0.022), mDC rich (p=0.029) and B-cell poor/Macrophages-mDC rich patients (p=0.006) (Figure 1f-g-h). Finally, by applying MCP-counter on matched pre-and post-treatment biopsies, rituximab-treated patients showed a significant reduction of B-cells, T-cells and monocyte/macrophages, while tocilizumab-treated patients showed a significant reduction of monocyte/macrophages, T-cells, but also neutrophils, myeloid dendritic cells and, interestingly, an increase in fibroblast signature (Figure 1i).

Conclusion

In silico deconvolution of the synovial tissue identify pre-treatment lymphoid cell lineages associated with response to rituximab and myeloid cells for tocilizumab. The longitudinal analysis of matched pre- and post-treatment synovial biopsies indicated that both medications have an effect on synovial immune cells, but tocilizumab can also affect stromal cells.

References

[1]Humby et al. Rituximab versus tocilizumab in anti-TNF inadequate responder patients with rheumatoid arthritis (R4RA): 16-week outcomes of a stratified, biopsy-driven, multicentre, open-label, phase 4 randomised controlled trial Lancet. 2021 Jan 23;397(10271):305-317. doi: 10.1016/S0140-6736(20)32341-2.

Acknowledgements

We would like to thank all patients and the R4RA recruiting centres and principal investigators http://www.r4ra-nihr.whri.qmul.ac.uk/recruiting_centres.php We would also like to acknowledge the UK National Institute of Health Research for funding the R4RA trial (grant reference: 11/100/76) and Versus Arthritis for providing infrastructure support through the Experimental Arthritis Treatment Centre (grant number: 20022).

Disclosure of Interests

None declared.

POS0138 RHEUMATOID SYNOVIAL FIBROBLASTS DISPLAY IMPRINTED MEMORY OF THEIR SYNOVIAL ENDOTYPE WHICH CAN BE PLASTICALLY MODULATED BY B-CELLS CROSSTALK

Background

Despite advances in the treatment of Rheumatoid Arthritis (RA), synthetics and biologicals drugs are ineffective in ~40% of patients. The origin of this refractoriness is unclear, but several clues point at the synovial microenvironment (SE) and the relative cellular heterogeneity between patients. We previously described the existence of different RA endotypes such as the lympho-myeloid, LM, which is B-cell rich and the fibroid-paucimmune, FPI, which is devoid of B-cells. While there is clear evidence that the crosstalk between stromal and immune cells in rheumatoid joints is critical for the perpetuation of chronic inflammation and autoimmunity, it is currently unknown whether transcriptional signatures identified in synovial fibroblasts (SFs) derived from different RA endotypes are driven by “imprinted” properties of the SFs or are shaped by the interaction with infiltrating immune cells in the RA joints.

Objectives

I) to identify “imprinted” vs “inducible” RASFs signatures trough the comparison of freshly isolated SFs and primary established SFs cultures obtained from LM vs FPI RA synovial biopsies and ii) to investigate the identified RASF signature as predictive biomarkers of disease evolution and of response to conventional and biological DMARDs.

Methods

We performed flowcytometry and single cell RNA sequencing (sc-RNAseq) on SFs obtained from LM and FPI biopsies, in isolation or in co-culture with RA B cells. Next, supernatant has been screened trough Multiplex and ELISA. Furthermore, we compared our results to publicly available sc-RNAseq datasets on freshly isolated SFs and to our bulk-RNAseq data from clinical trials patients.

Results

Hierarchical clustering from sc-RNAseq transcriptional profiling of LM vs FPI RASF - after several cell passages - identified profoundly different gene signatures: whereby LM-RASF were characterised by genes involved in inflammation, proteoglycan formation and integrin binding, FPI-RASF were defined by genes related to collagen biosynthesis. Comparing the above signatures with those of freshly isolated RASF we identified both imprinted (i.e. maintained through several in vitro passages) and inducible (i.e. loss after long term culture) gene signatures. Notably, RA B-cells co-cultured with FPI-RASF profoundly altered the FPI-RASF transcriptional profile including the ex-novo expression of gene signatures typical of LM-RASF. Consensus gene modules constructed on LM vs FPI RASF imprinted gene signatures could be tracked in longitudinal whole tissue bulk RNA-seq data obtained from both early arthritis and established RA and were associated with synovial pathotype-specific histological and clinical features. Finally, modulation of FPI-RASF related genes following B-cell depletion identified poor responders to Rituximab in the R4RA randomised clinical trial.

Conclusion

Our work demonstrates that RASFs from different endotypes display imprinted memory of their original synovial tissue when maintained in culture over several months. We also demonstrated that imprinted memory typical of RASF isolated from B-cell rich LM synovial tissues can be dynamically modulated in FPI RASF following crosstalk with RA B cells. Finally, consensus gene modules based on FPI vs LM RASF-gene signatures were able inform on response/resistance to targeted biologic therapies.

References

[1]Lewis, M. J. et al. Molecular Portraits of Early Rheumatoid Arthritis Identify Clinical and Treatment Response Phenotypes. Cell Rep (2019)

[2]Humby, F. et al. Synovial cellular and molecular signatures stratify clinical response to csDMARD therapy and predict radiographic progression in early rheumatoid arthritis patients. Ann Rheum Dis (2019)

[3]Zhang, F. et al. Defining inflammatory cell states in rheumatoid arthritis joint synovial tissues by integrating single-cell transcriptomics and mass cytometry. Nat Immunol (2019)

[4]Humby, F. et al. Rituximab versus tocilizumab in anti-TNF inadequate responder patients with rheumatoid arthritis (R4RA). Lancet (2021)

Disclosure of Interests

None declared

POS0441 IN-DEPTH ANALYSIS OF Axl AND MerTK EXPRESSION PATTERNS AND REGULATION BY BIOLOGIC TREATMENTS IN RHEUMATOID ARTHRITIS

Background

Tyrosine kinases receptors MerTK and Axl have been implicated in the pathogenesis of several autoimmune diseases. Despite sharing significant structural homology and having common ligands, Axl and MerTK have distinct features and biological functions [1]. A growing body of evidence suggests that both Axl and MerTK play a crucial role in Rheumatoid Arthritis (RA) pathogenesis and progression and may be exploited as novel therapeutic targets [2]. However, numerous unanswered questions remain to be addressed.

Objectives:

i.To define common and distinct gene-partners of Axl/MerTK and quantify their expression in RA synovial tissue.

ii.To assess the co-expression of Axl/MerTK by synovial cells.

iii.To outline the longitudinal variation in Axl/MerTK expression upon treatment intervention.

Methods

Synovial tissue samples were collected by US-guided synovial biopsy from: i. Patients with early (<12 months) RA DMARDs/steroid-naïve [n=87]; and ii. RA patients who failed the first-line biologic with TNF-inhibitors (TNFi) before and 16 weeks after receiving either Rituximab (RTX) or Tocilizumab (TOC) [n=164] [3]. Gene expression was obtained by bulk RNAseq performed on an Illumina HiSeq2500 platform. Axl-/MerTK-modules were defined using STRING networks and the module expression determined by the mean z-score of regularized log transformed expression for all genes in the set. Axl, MerTK, CD55, CD90, CD68 protein expression was analysed by multiplex immunofluorescence staining.

Results

Using STRING network analysis, we defined an Axl- and a MerTK-module composed of 31 predicted gene-partners of either Axl or MerTK. Thirteen genes were common to both modules and included the ligands Gas6 and ProteinS, and EGFR. Conversely, eighteen genes were uniquely present in the Axl-module (e.g., PIK3-family, IGF1R, IFNAR1 and STAT3) or the MerTK-module (e.g., Galectin3 and TULP, recently discovered MerTK ligands, FCGR1A/CD64, PTPN1and MEGF10). Axl/MerTK-modules quantified in the early-arthritis treatment-naïve RNAseq dataset showed a significant negative correlation with the synovitis score (Axl r=−0.33, p=0.0032; MerTK r=-0.33, p=0.003). At protein level, CD68+macrophages of the Lining showed notable heterogeneity between patients: they could express either Axl or MerTK alone, or co-express both. Axl was also present in most CD55+ Lining Fibroblast-Like-Cells (FLS) but not by CD90+ Sublining FLS while MerTK, as expected, was restricted to macrophages, including intra-aggregate tingible-body-macrophages.

To define how Axl and MerTK vary depending on disease stage and treatment exposure, we quantified their gene expression in active RA patients inadequately responding to TNFi, prior and 16 weeks after starting second-line biologic (RTX or TOC) [3]. Differently from the early-arthritis cohort, MerTK was significantly up-regulated in synovia characterised by higher degree of tissue inflammation (lympho-myeloid > diffuse-myeloid > pauci-immune, p<0.0001) and significantly positively correlated with several cytokines’ genes such as TNF, IL-6, CCL8 and IL-10. MerTK expression was dependent on clinical response to RTX but not TOC as assessed by EULAR response (DAS28CRP, good vs none/mod, FDRresp 0.048). Conversely, Axl expression significantly increased upon IL-6 blockade by TOC independently of the clinical response (FDRtime 0.016).

Conclusion

Our data further corroborate that Axl and MerTK constitute a dynamic axis influenced by the synovial tissue inflammatory features, the disease stage, the exposure and the response to targeted treatment and the blockade of critical inflammatory pathways over time. A better understanding of the individual features of these tyrosine kinases as well as their interaction would be beneficial to define novel treatment approaches.

References

[1]Zagórska A, et al. Nat Immunol. 2014 Oct;15(10):920-8

[2]Kemble S, Croft AP. Front Immunol. 2021 Sep 3;12:715894

[3]Humby F et al. Lancet. 2021 Jan 23;397(10271):305-317

Acknowledgements

Versus Arthritis.

Disclosure of Interests

None declared.

Circulating and Synovial Pentraxin-3 (PTX3) Expression Levels Correlate With Rheumatoid Arthritis Severity and Tissue Infiltration Independently of Conventional Treatments Response

Aims

To determine the relationship between PTX3 systemic and synovial levels and the clinical features of rheumatoid arthritis (RA) in a cohort of early, treatment naïve patients and to explore the relevance of PTX3 expression in predicting response to conventional-synthetic (cs) Disease-Modifying-Anti-Rheumatic-Drugs (DMARDs) treatment.

Methods

PTX3 expression was analyzed in 119 baseline serum samples from early naïve RA patients, 95 paired samples obtained 6-months following the initiation of cs-DMARDs treatment and 43 healthy donors. RNA-sequencing analysis and immunohistochemistry for PTX3 were performed on a subpopulation of 79 and 58 synovial samples, respectively, to assess PTX3 gene and protein expression. Immunofluorescence staining was performed to characterize PTX3 expressing cells within the synovium.

Results

Circulating levels of PTX3 were significantly higher in early RA compared to healthy donors and correlated with disease activity at baseline and with the degree of structural damages at 12-months. Six-months after commencing cs-DMARDs, a high level of PTX3, proportional to the baseline value, was still detectable in the serum of patients, regardless of their response status. RNA-seq analysis confirmed that synovial transcript levels of PTX3 correlated with disease activity and the presence of mediators of inflammation, tissue remodeling and bone destruction at baseline. PTX3 expression in the synovium was strongly linked to the degree of immune cell infiltration, the presence of ectopic lymphoid structures and seropositivity for autoantibodies. Accordingly, PTX3 was found to be expressed by numerous synovial cell types such as plasma cells, fibroblasts, vascular and lymphatic endothelial cells, macrophages, and neutrophils. The percentage of PTX3-positive synovial cells, although significantly reduced at 6-months post-treatment as a result of global decreased cellularity, was similar in cs-DMARDs responders and non-responders.

Conclusion

This study demonstrates that, early in the disease and prior to treatment modification, the level of circulating PTX3 is a reliable marker of RA activity and predicts a high degree of structural damages at 12-months. In the joint, PTX3 associates with immune cell infiltration and the presence of ectopic lymphoid structures. High synovial and peripheral blood levels of PTX3 are associated with chronic inflammation characteristic of RA. Additional studies to determine the mechanistic link are required.

OP0011 INTEGRATION OF FLOW AND DIGITAL CYTOMETRY IN EARLY TREATMENT-NAÏVE RHEUMATOID ARTHRITIS IDENTIFIES DISTINCT IMMUNOPHENOTYPES IN PERIPHERAL BLOOD AND DISEASE TISSUE

Background:

The study of synovial tissue in patients with Rheumatoid Arthritis (RA) has led to the identification of synovial patterns of immune cell infiltration and specific cellular subsets associated that have been disease activity and clinical outcomes(1–3). However, the relationship of circulating and synovial immune cell sub-sets with histopathological features and clinical outcomes remains to be defined.

Objectives:

To assess the relationship of peripheral blood and synovial immune cells with RA histopathology and clinical outcomes, by performing flow and digital cytometry in matched peripheral blood and synovial samples from patients with early RA.

Methods:

70 patients with early (<12 months) untreated RA (2010 criteria) recruited in the pathobiology of early Arthritis Cohort (PEAC) at the Barts Health NHS Trust were included(1). Peripheral blood mononuclear cells (n=70) were analysed by flow cytometry. Matched synovial tissues (n=70) obtained by minimally invasive ultrasound-guided synovial biopsy underwent semi-quantitative scoring (0-4) of immune cell infiltration and classification into lympho-myeloid (LM), diffuse-myeloid (DM) and pauci-immune (PI) pathotypes, as previously described(1). 49 synovial and 36 matched peripheral blood samples underwent RNA-sequencing and were analysed by digital cytometry (Xcell) (4) and Singular Value Decomposition (SVD).

Results:

Circulating B cells and their subsets showed significant inverse correlations with inflammatory markers (ESR, CRP), disease activity (swollen joints, four components and two components(5) DAS28) and ultrasound scores (Fig 1A). Among T cell subsets, CXCR5-PD1hiICOS+CD4+ T cells (T peripheral helper cells, Tph) had strong positive correlations with inflammatory markers (ESR and CRP), disease activity (DAS28) and ultrasound scores (Fig 1B). Tph in the peripheral blood also correlated with immune cell infiltration in synovia (Fig 1C) and were significantly higher in patients with a LM pathotype (Fig 1D). Accordingly, circulating Tph were associated with synovial LM pathotype independently of clinical features such as DAS28, ACPA positivity, Body Mass Index (BMI) and age (AUC 0.821). By applying digital cytometry in matched synovial and peripheral blood samples, synovial B and T cells were significantly higher in patients with a LM pathotype, in line with the histological definition of the LM pathotype – rich in B and T cells. On the contrary, circulating B cells and total CD4 and CD8 T cells were significantly lower in patients with a synovial LM pathotype (Fig 1E). The Tph signature in synovia derived by Singular Value Decomposition (SVD) correlated with baseline ESR (R 0.38, p<0.0001) and DAS28 (R 0.35, p <0.0001) and with delta-DAS28 after 6 months of treatment with conventional synthetic DMARDs (R 0.27, p 0.026). Finally, the baseline synovial Tph signature was significantly higher in patients who progressed to the use of biologics and was predictive of future biologic DMARDs use, independently of baseline DAS28, ACPA positivity, BMI and age (AUC 0.703).

Conclusion:

By combining conventional flow cytometry in the peripheral blood and digital cytometry on matched synovial and peripheral blood samples, we highlight diverging associations of circulating immune cell subsets with synovial inflammation and pathotypes. Tph cells, in particular, emerge as predictors of lympho-myeloid synovial inflammation and disease progression.

References:

[1]F. Humby et al., Ann. Rheum. Dis. 78, 761–772 (2019), doi:10.1136/annrheumdis-2018-214539. [2]M. J. Lewis et al., Cell Rep. 28, 2455-2470.e5 (2019), doi:10.1016/j.celrep.2019.07.091.[3]D. a Rao et al., Nat. Publ. Gr. 542, 110–114 (2017), doi:10.1038/nature20810.[4]D. Aran et al., Genome Biol. 18, 220 (2017), doi:10.1186/s13059-017-1349-1.[5]E. M. A. Hensor et al., Rheumatology. 58, 1400–1409 (2019), doi:10.1093/rheumatology/kez049.

Figure 1.

Acknowledgements:

The Pathobiology of Early Arthritis Cohort (PEAC) was supported by the MRC (grant 36661). Versus Arthritis provided funding infrastructure support (grant 20022). F. Rivellese is funded by an NIHR Transitional Research Fellowship (TRF-2018-11-ST2-002). We would like to thank the patients and the clinical and laboratory team (core team) at Queen Mary University of London.

Disclosure of Interests:

None declared

IL-23 skin and joint profiling in psoriatic arthritis: novel perspectives in understanding clinical responses to IL-23 inhibitors

OBJECTIVES

To determine the relationship between synovial versus skin transcriptional/histological profiles in patients with active psoriatic arthritis (PsA) and explore mechanistic links between diseased tissue pathology and clinical outcomes.

METHODS

Twenty-seven active PsA patients were enrolled in an observational/open-label study and underwent biopsies of synovium and paired lesional/non-lesional skin before starting anti-tumour necrosis factor (TNF) (if biologic-naïve) or ustekinumab (if anti-TNF inadequate responders). Molecular analysis of 80-inflammation-related genes and protein levels for interleukin (IL)-23p40/IL-23p19/IL-23R were assessed by real-time-PCR and immunohistochemistry, respectively.

RESULTS

At baseline, all patients had persistent active disease as per inclusion criteria. At primary end-point (16-weeks post-treatment), skin responses favoured ustekinumab, while joint responses favoured anti-TNF therapies. Principal component analysis revealed distinct clustering of synovial tissue gene expression away from the matched skin. While IL12B, IL23A and IL23R were homogeneously expressed in lesional skin, their expression was extremely heterogeneous in paired synovial tissues. Here, IL-23 transcriptomic/protein expression was strongly linked to patients with high-grade synovitis who, however, were not distinguishable by conventional clinimetric measures.

CONCLUSIONS

PsA synovial tissue shows a heterogeneous IL-23 axis profile when compared with matched skin. Synovial molecular pathology may help to identify among clinically indistinguishable patients those with a greater probability of responding to IL-23 inhibitors.

Novel insights into macrophage diversity in rheumatoid arthritis synovium

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease affecting joints and causing progressive damage and disability. Macrophages are of critical importance in the initiation and perpetuation of synovitis in RA, they can function as antigen presenting cells leading to T-cell dependent B-cell activation, assume a variety of inflammatory cell states with the production of destructive cytokines, but also contribute to tissue homeostasis/repair. The recent development of high-throughput technologies, including bulk and single cells RNA-sequencing, has broadened our understanding of synovial cell diversity, and opened novel perspectives to the discovery of new potential therapeutic targets in RA. In this review, we will focus on the relationship between the synovial macrophage infiltration and clinical disease severity and response to treatment. We will then provide a state-of-the-art picture of the biological roles of synovial macrophages and distinct macrophage subsets described in RA. Finally, we will review the effects of approved conventional and biologic drugs on the synovial macrophage component and highlight the therapeutic potential of future strategies to re-program macrophage phenotypes in RA.

Novel Bispecific Antibody for Synovial-Specific Target Delivery of Anti-TNF Therapy in Rheumatoid Arthritis

Biologic drugs, especially anti-TNF, are considered as the gold standard therapy in rheumatoid arthritis. However, non-uniform efficacy, incidence of infections, and high costs are major concerns. Novel tissue-specific agents may overcome the current limitations of systemic administration, providing improved potency, and safety. We developed a bispecific antibody (BsAb), combining human arthritic joint targeting, via the synovial-specific single-chain variable fragment (scFv)-A7 antibody, and TNFα neutralization, via the scFv-anti-TNFα of adalimumab, with the binding/blocking capacity comparable to adalimumab -immunoglobulin G (IgG). Tissue-targeting capacity of the BsAb was confirmed on the human arthritic synovium in vitro and in a synovium xenograft Severe combined immune deficient (SCID) mouse model. Peak graft accumulation occurred at 48 h after injection with sustained levels over adalimumab-IgG for 7 days and increased therapeutic effect, efficiently decreasing tissue cellularity, and markers of inflammation with higher potency compared to the standard treatment. This study provides the first description of a BsAb capable of drug delivery, specifically to the disease tissue, and a strong evidence of improved therapeutic effect on the human arthritic synovium, with applications to other existing biologics.

Rituximab versus tocilizumab in anti-TNF inadequate responder patients with rheumatoid arthritis (R4RA): 16-week outcomes of a stratified, biopsy-driven, multicentre, open-label, phase 4 randomised controlled trial

BACKGROUND

Although targeted biological treatments have transformed the outlook for patients with rheumatoid arthritis, 40% of patients show poor clinical response, which is mechanistically still unexplained. Because more than 50% of patients with rheumatoid arthritis have low or absent CD20 B cells-the target for rituximab-in the main disease tissue (joint synovium), we hypothesised that, in these patients, the IL-6 receptor inhibitor tocilizumab would be more effective. The aim of this trial was to compare the effect of tocilizumab with rituximab in patients with rheumatoid arthritis who had an inadequate response to anti-tumour necrosis factor (TNF) stratified for synovial B-cell status.

METHODS

This study was a 48-week, biopsy-driven, multicentre, open-label, phase 4 randomised controlled trial (rituximab vs tocilizumab in anti-TNF inadequate responder patients with rheumatoid arthritis; R4RA) done in 19 centres across five European countries (the UK, Belgium, Italy, Portugal, and Spain). Patients aged 18 years or older who fulfilled the 2010 American College of Rheumatology and European League Against Rheumatism classification criteria for rheumatoid arthritis and were eligible for treatment with rituximab therapy according to UK National Institute for Health and Care Excellence guidelines were eligible for inclusion in the trial. To inform balanced stratification, following a baseline synovial biopsy, patients were classified histologically as B-cell poor or rich. Patients were then randomly assigned (1:1) centrally in block sizes of six and four to receive two 1000 mg rituximab infusions at an interval of 2 weeks (rituximab group) or 8 mg/kg tocilizumab infusions at 4-week intervals (tocilizumab group). To enhance the accuracy of the stratification of B-cell poor and B-cell rich patients, baseline synovial biopsies from all participants were subjected to RNA sequencing and reclassified by B-cell molecular signature. The study was powered to test the superiority of tocilizumab over rituximab in the B-cell poor population at 16 weeks. The primary endpoint was defined as a 50% improvement in Clinical Disease Activity Index (CDAI50%) from baseline. The trial is registered on the ISRCTN database, ISRCTN97443826, and EudraCT, 2012-002535-28.

FINDINGS

Between Feb 28, 2013, and Jan 17, 2019, 164 patients were classified histologically and were randomly assigned to the rituximab group (83 [51%]) or the tocilizumab group (81 [49%]). In patients histologically classified as B-cell poor, there was no statistically significant difference in CDAI50% between the rituximab group (17 [45%] of 38 patients) and the tocilizumab group (23 [56%] of 41 patients; difference 11% [95% CI -11 to 33], p=0·31). However, in the synovial biopsies classified as B-cell poor with RNA sequencing the tocilizumab group had a significantly higher response rate compared with the rituximab group for CDAI50% (rituximab group 12 [36%] of 33 patients vs tocilizumab group 20 [63%] of 32 patients; difference 26% [2 to 50], p=0·035). Occurrence of adverse events (rituximab group 76 [70%] of 108 patients vs tocilizumab group 94 [80%] of 117 patients; difference 10% [-1 to 21) and serious adverse events (rituximab group 8 [7%] of 108 vs tocilizumab group 12 [10%] of 117; difference 3% [-5 to 10]) were not significantly different between treatment groups.

INTERPRETATION

The results suggest that RNA sequencing-based stratification of rheumatoid arthritis synovial tissue showed stronger associations with clinical responses compared with histopathological classification. Additionally, for patients with low or absent B-cell lineage expression signature in synovial tissue tocilizumab is more effective than rituximab. Replication of the results and validation of the RNA sequencing-based classification in independent cohorts is required before making treatment recommendations for clinical practice.

FUNDING

Efficacy and Mechanism Evaluation programme from the UK National Institute for Health Research.

Distinct synovial tissue macrophage subsets regulate inflammation and remission in rheumatoid arthritis

Immune-regulatory mechanisms of drug-free remission in rheumatoid arthritis (RA) are unknown. We hypothesized that synovial tissue macrophages (STM), which persist in remission, contribute to joint homeostasis. We used single-cell transcriptomics to profile 32,000 STMs and identified phenotypic changes in patients with early/active RA, treatment-refractory/active RA and RA in sustained remission. Each clinical state was characterized by different frequencies of nine discrete phenotypic clusters within four distinct STM subpopulations with diverse homeostatic, regulatory and inflammatory functions. This cellular atlas, combined with deep-phenotypic, spatial and functional analyses of synovial biopsy fluorescent activated cell sorted STMs, revealed two STM subpopulations (MerTKposTREM2high and MerTKposLYVE1pos) with unique remission transcriptomic signatures enriched in negative regulators of inflammation. These STMs were potent producers of inflammation-resolving lipid mediators and induced the repair response of synovial fibroblasts in vitro. A low proportion of MerTKpos STMs in remission was associated with increased risk of disease flare after treatment cessation. Therapeutic modulation of MerTKpos STM subpopulations could therefore be a potential treatment strategy for RA.

THU0082 MERTK SYNOVIAL EXPRESSION CORRELATES WITH TREATMENT RESPONSE IN RHEUMATOID ARTHRITIS

Background:

Despite substantial improvements in long-term clinical outcomes, a significant proportion of rheumatoid arthritis (RA) patients still fail to respond to treatment adequately, and early prognostic biomarkers of response are missing. Single-cell transcriptomic studies on RA synovial tissue (ST) have shown that MerTK is highly expressed in “anti-inflammatory” macrophages [1]. It has also been suggested that synovial macrophages isolated from RA patients in remission are characterised by a CD206+/MerTK+ signature [2]. Finally, monocyte-derived macrophages from RA patients treated with TNF-inhibitors (TNF-i) up-regulate MerTK.

Objectives:

To assess i) the modulation of synovial tissue MerTK+ macrophages upon treatment with conventional synthetic (cs) disease-modifying anti-rheumatic drugs (DMARDs) and ii) the relationship between baselineMerTKgene expression and response to TNFi.

Methods:

ST was obtained by US-guided synovial biopsies of an inflamed peripheral joint in patients with early (<12 months) treatment-naïve RA (as per ACR/EULAR 2010 criteria). A second biopsy of the same joint was repeated six months after starting treatment with single or multiple csDMARDs. ST (n=15) was stained for CD68, MerTK and CD206 by immunofluorescence using a tyramide amplification signal system. Quantification of the percentage of single- (MerTK+ or CD206+) and double-positive (CD206+MerTK+) CD68+ macrophages was obtained by digital image analysis (Image J). Gene expression analysis was performed on RNA sequences of 22 baseline ST samples (treatment-naïve).

Results:

Before any treatment intervention, the percentage of MerTK+CD206+ macrophages was significantly higher in RA patients with low (DAS28<3.2) versus high (DAS28>5.1) disease activity (24.5±20.1 versus 4.8±4.8, p<0.05). There were no differences in the relative number of MerTK+ or CD206+ or MerTK+CD206+ macrophages at baseline in relationship with the clinical response to csDMARDs at 6-months. On the other hand, patients (n=5) achieving remission (DAS<2.6) upon receiving csDMARDs significantly increased the number of MerTK+ macrophages from pre- to six-months post-treatment (23.6±23.8 to 55.5±15.4, p<0.05) in comparison with patients (n=5) who were still active after treatment (18±15.6 to 30.4±11.17, p=ns). MerTK synovial gene expression at baseline (i.e., in newly diagnosed treatment-naïve RA patients) was significantly higher in patients subsequently treated with TNFi and achieving a good/moderate EULAR response at 12 months in comparison with those who did not respond (n=14, n=8, p adjusted 0.003).

Conclusion:

Our whole-tissue protein expression data further support the hypothesis that a selective expansion of the MerTK+ macrophage subset characterise patients achieving remission. Moreover, the pre-treatment up-regulation of the MerTK gene in future responders to TNFi suggest that MerTK is implicated in modulating synovial inflammatory responses and may be exploited as a therapeutic target in RA.

References:

[1]F. Zhang et al, Nature Immunology, vol. 20, no. 7, pp. 928–942, 2019.

[2]S. R. Finlay at al, Annals of the Rheumatic Diseases, vol. 77, Supplement 2, pp. 183–183, 2018.

[3]Y. Degboé et al, Frontiers in Immunology, vol. 10, p. 3, 2019.

Acknowledgments:

Versus Arthritis

Disclosure of Interests:

None declared

OP0217 INVOLVEMENT OF LARGE JOINTS AT DISEASE PRESENTATION IS ASSOCIATED WITH DIVERSE HISTOPATHOLOGICAL FEATURES AND CLINICAL OUTCOMES IN EARLY RHEUMATOID ARTHRITIS

Background:

The involvement of large joints at disease presentation in early Rheumatoid Arthritis (RA) has been associated with severe disease activity. At the same time, the clinical heterogeneity of RA is known to be mirrored by heterogeneity of synovial inflammation, with specific histological patterns (pathotypes) associated with treatment response and disease progression. However, it is not known whether joint size is associated with specific pathotypes.

Objectives:

To analyse histopathological features of synovial biopsies from joints of different sizes and establish the relationship with clinical outcomes in patients with early RA.

Methods:

167 patients with early (<1 year) treatment-naïve RA, fulfilling the 2010 RA criteria and recruited at Barts Health NHS Trust, underwent US-guided synovial biopsy of the most inflamed joint, either large (knee), medium (e.g. wrist, ankle, elbow) or small (MCPs, MTPs), before starting treatment with csDMARDS with a treat to target approach. Upon SQ scoring (0-4) of immune cell infiltration, tissues were classified into lympho-myeloid, diffuse-myeloid and pauci-immune pathotypes. Synovial samples from 111 patients underwent RNA-seq.

Results:

The majority of synovial biopsies were performed on medium and small joints (60.6% and 19.4%) as compared to 21.3% in large joints (Table 1). At baseline, patients who underwent large joint biopsy showed significantly higher levels of inflammation (CRP 27.9±32.4 large, 20.7±26.9 medium, 10.4±9.8 small, p=0.007) and higher HAQ (1.8 ± 0.7 large, 1.4 ± 0.8 medium, 1.2 ±0.9 small, p=0.012), with no differences in DAS28. Significantly higher inflammatory scores and higher proportion of lympho-myeloid pathotype were observed in large joints (Table 1 and Figure 1). 6 months after treat-to-target treatment with csDMARDs, large joints patients had significantly higher HAQ and lower response (RR for low disease activity in large vs medium joints 0.5, 95%CI 0.2-0.9, p=0.03). Finally, differentially expressed genes by RNA-seq showed segregation according to joint size (Figure 2), with upregulation of genes of the Homeobox transcription factors family in large joints.

Table 1.

EULAR 2010 RA (n=167)

Large joints#33 (19.4%)Medium joints#100 (60.6%)Small Joints#34 (20%)P*Clinical featuresESR mm/h,mean (SD)48.2 (31.5)39.6 (30.8)29.2 (17.3)nsCRP mg/L,mean (SD)27.9 (32.4)20.7 (26.9)10.4 (9.8)0.007DAS28, mean (SD)6 (1.2)5.7 (1.4)5.7 (1.5)nsHAQ, mean (SD)1.8 (0.7)1.4 (0.8)1.2 (0.9)0.012ACPA-positive, %70.9%77.3%83.9%nsRF-positive,%71.9%74.2%80.6%nsHistologyInflammatory score,median IQR)5 (3)4 (4)2 (2.75)<0.001Pathotype,%Ungraded6.1%7.8%2.9%0.014Fibroid6.1%24.3%32.3%Myeloid30.3%28.1%47.1%Lympho-myeloid57.6%39.8%17.6%Clinical outcomes at 6 monthsDAS28 6m,mean (SD)4.2 (1.8)3.4 (1.9)3.7 (1.5)nsHAQ 6m,mean (SD)1.2 (0.8)0.8 (0.8)0.8 (0.8)0.012DAS28 6m <3.2,%23.3%48.8%37.9%0.04

#Large joints: knees; Medium joints: wrists, ankle, elbows; Small joints: MCPs, MTPs, PIPs; * Chi-squared or Kruskal–Wallis as appropriate;

Conclusion:

Synovial biopsy of large joints as the most inflamed joints at disease presentation identified patients with early RA with specific histopathological features and clinical outcomes. Together with clustering of differentially expressed genes according to joint size, this suggests that the involvement of different joint compartments in early RA contributes to disease heterogeneity with potential physiopathological and clinical implications.

References:

[1]Humby et al Ann Rheum Dis. 2019 Jun;78(6):761-772

[2]Lewis et al Cell Rep. 2019 Aug 27;28(9):2455-2470.e5

[3]Linn-Rasker SP et al Ann Rheum Dis. 2007 May;66(5):646-50

Acknowledgments:

PEAChttp://www.peac-mrc.mds.qmul.ac.ukMRC grant 36661 & ARUK Grant 20022

F. Rivellese NIHR Fellowship TRF-2018-11-ST2-002

Disclosure of Interests:

None declared

A Pauci-Immune Synovial Pathotype Predicts Inadequate Response to TNFα-Blockade in Rheumatoid Arthritis Patients

Objectives: To assess whether the histopathological features of the synovium before starting treatment with the TNFi certolizumab-pegol could predict clinical outcome and examine the modulation of histopathology by treatment. Methods: Thirty-seven RA patients fulfilling UK NICE guidelines for biologic therapy were enrolled at Barts Health NHS trust and underwent synovial sampling of an actively inflamed joint using ultrasound-guided needle biopsy before commencing certolizumab-pegol and after 12-weeks. At 12-weeks, patients were categorized as responders if they had a DAS28 fall >1.2. A minimum of 6 samples was collected for histological analysis. Based on H&E and immunohistochemistry (IHC) staining for CD3 (T cells), CD20 (B cells), CD138 (plasma cells), and CD68 (macrophages) patients were categorized into three distinct synovial pathotypes (lympho-myeloid, diffuse-myeloid, and pauci-immune). Results: At baseline, as per inclusion criteria, DAS28 mean was 6.4 ± 0.9. 94.6% of the synovial tissue was retrieved from the wrist or a metacarpophalangeal joint. Histological pathotypes were distributed as follows: 58% lympho-myeloid, 19.4% diffuse-myeloid, and 22.6% pauci-immune. Patients with a pauci-immune pathotype had lower levels of CRP but higher VAS fatigue compared to lympho- and diffuse-myeloid. Based on DAS28 fall >1.2, 67.6% of patients were deemed as responders and 32.4% as non-responders. However, by categorizing patients according to the baseline synovial pathotype, we demonstrated that a significantly higher number of patients with a lympho-myeloid and diffuse-myeloid pathotype in comparison with pauci-immune pathotype [83.3% (15/18), 83.3 % (5/6) vs. 28.6% (2/7), p = 0.022) achieved clinical response to certolizumab-pegol. Furthermore, we observed a significantly higher level of post-treatment tender joint count and VAS scores for pain, fatigue and global health in pauci-immune in comparison with lympho- and diffuse-myeloid patients but no differences in the number of swollen joints, ESR and CRP. Finally, we confirmed a significant fall in the number of CD68+ sublining macrophages post-treatment in responders and a correlation between the reduction in the CD20+ B-cells score and the improvement in the DAS28 at 12-weeks. Conclusions: The analysis of the synovial histopathology may be a helpful tool to identify among clinically indistinguishable patients those with lower probability of response to TNFα-blockade.

B Cell Synovitis and Clinical Phenotypes in Rheumatoid Arthritis: Relationship to Disease Stages and Drug Exposure

OBJECTIVE

To define the relationship of synovial B cells to clinical phenotypes at different stages of disease evolution and drug exposure in rheumatoid arthritis (RA).

METHODS

Synovial biopsy specimens and demographic and clinical data were collected from 2 RA cohorts (n = 329), one of patients with untreated early RA (n = 165) and one of patients with established RA with an inadequate response to tumor necrosis factor inhibitors (TNFi-IR; n = 164). Synovial tissue was subjected to hematoxylin and eosin and immunohistochemical staining and semiquantitative assessment for the degree of synovitis (on a scale of 0-9) and of CD20+ B cell infiltrate (on a scale of 0-4). B cell scores were validated by digital image analysis and B cell lineage-specific transcript analysis (RNA-Seq) in the early RA (n = 91) and TNFi-IR (n = 127) cohorts. Semiquantitative CD20 scores were used to classify patients as B cell rich (≥2) or B cell poor (<2).

RESULTS

Semiquantitative B cell scores correlated with digital image analysis quantitative measurements and B cell lineage-specific transcripts. B cell-rich synovitis was present in 35% of patients in the early RA cohort and 47.7% of patients in the TNFi-IR cohort (P = 0.025). B cell-rich patients showed higher levels of disease activity and seropositivity for rheumatoid factor and anti-citrullinated protein antibody in early RA but not in established RA, while significantly higher histologic synovitis scores in B cell-rich patients were demonstrated in both cohorts.

CONCLUSION

We describe a robust semiquantitative histologic B cell score that closely replicates the quantification of B cells by digital or molecular analyses. Our findings indicate an ongoing B cell-rich synovitis, which does not seem to be captured by standard clinimetric assessment, in a larger proportion of patients with established RA than early RA.

Interleukin-36 family dysregulation drives joint inflammation and therapy response in psoriatic arthritis

OBJECTIVES

IL-36 agonists are pro-inflammatory cytokines involved in the pathogenesis of psoriasis. However, their role in the pathogenesis of arthritis and treatment response to DMARDs in PsA remains uncertain. Therefore, we investigated the IL-36 axis in the synovium of early, treatment-naïve PsA, and for comparison RA patients, pre- and post-DMARDs therapy.

METHODS

Synovial tissues were collected by US-guided biopsy from patients with early, treatment-naïve PsA and RA at baseline and 6 months after DMARDs therapy. IL-36 family members were investigated in synovium by RNA sequencing and immunohistochemistry, and expression levels correlated with DMARDs treatment response ex vivo. Additionally, DMARDs effects on IL-36 were investigated in vitro in fibroblast-like synoviocytes.

RESULTS

PsA synovium displayed a reduced expression of IL-36 antagonists, while IL-36 agonists were comparable between PsA and RA. Additionally, neutrophil-related molecules, which drive a higher activation of the IL-36 pathway, were upregulated in PsA compared with RA. At baseline, the synovial expression of IL-36α was significantly higher in PsA non-responders to DMARDs treatment, with the differential expression being sustained at 6 months post-treatment. In vitro, primary PsA-derived fibroblasts were more responsive to IL-36 stimulation compared with RA and, importantly, DMARDs treatment increased IL-36 expression in PsA fibroblasts.

CONCLUSION

The impaired balance between IL-36 agonists-antagonists described herein for the first time in PsA synovium and the decreased sensitivity to DMARDs in vitro may explain the apparent lower efficacy of DMARDs in PsA compared with RA. Exogenous replacement of IL-36 antagonists may be a novel promising therapeutic target for PsA patients.

O07 Randomised, open labelled clinical trial to investigate synovial mechanisms determining response: resistance to rituximab versus tocilizumab in RA patients failing TNF inhibitor therapy

Background

Biologic therapies have transformed the outlook for RA but the significant health economic impact of these therapies has highlighted the need to define predictive markers of response. Rituximab (RTX) is licensed for use following failure of csDMARDs and TNF inhibitor (TNFi) therapy. However, in this increasing therapeutically resistant cohort only 30% of patients achieve an ACR50 response. The observation in early RA that 50% of patients show low/absence of synovial B-cells prompted us to test the hypothesis that in these patients a biologic agent targeting alternative pathways maybe more effective. We report results from the first pathobiology-driven randomised controlled trial (RCT) in RA (R4RA) evaluating whether patient stratification according to the synovial B-cell rich/poor status enriches for response/non response to RTX.

Methods

R4RA is a phase IV open-label RCT conducted in 19 European centres recruiting patients failing or intolerant to csDMARD therapy and at least one TNFi. Synovial tissue was obtained at trial entry and used to classify patients as B-cell rich or poor using both histological and RNA-seq classification criteria. Patients were randomised to receive RTX or tocilizumab (TCZ). The study was powered to test in the B cell poor population superiority of TCZ over RTX at 16 weeks. The primary and co-primary end-points were defined respectively as Clinical Disease Activity Index (CDAI) ≥50% improvement from baseline and Major Treatment response (MTR)= CDAI improvement ≥ 50% and CDAI ≤10.1.

Results

The trial recruited to target (n = 164) with a power of 89.5%. In the B cell poor cohort a numerically higher number of patients achieved the primary endpoint and a significantly higher number of patients achieved co-primary endpoint (MTR). Classification of patients as B cell poor/rich according to RNA-seq criteria enhanced the difference between TCZ and RTX, with a significantly higher number of TCZ treated patients reaching both CDAI 50% improvement and CDAI MTR in the B-cell poor group.

Conclusion

In a RA B cell poor population failing csDMARDs and TNFi therapy, TCZ is more effective than RTX. This first biopsy-driven RCT suggests clinical utility for integrating molecular pathology profiling into treatment algorithms to allocate targeted therapies.

Disclosures

F. Humby: Honoraria; Roche, Pfizer. Grants/research support; Pfizer. P. Durez: BMS,Bristol-Myers Squibb, Celltrion, Eli Lilly, Hospira, Mundipharma, Pfizer, Samsung, Sanofi, UCB. M. Buch: Consultancies; Pfizer, Roche, UCB, AbbVie, Eli Lilly, Sandoz, and Sanofi. Grants/research support; Pfizer, Roche, UCB, AbbVie, Eli Lilly, Sandoz, and Sanofi. M. Lewis: None. M. Bombardieri: None. H. Rizvi: None. S. Kelly: None. L. Fossati: None. R. Hands: None. G. Giorli: None. A. Mahto: None. C. Montecucco: None. B. Lauwerys: None. V.C. Romao: None. A.G. Pratt: Member of speakers’ bureau; Eli Lilly and Janssen-Cilag Ltd. Grants/research support; Pfizer. S. Bugatti: None. N. Ng: None. F. Rivellese: None. P. Ho: None. M. Bellan: None. P. Sainaghi: None. P. Verschueren: None. N. Gendi: None. B. Dasgupta: Abbvie, BMS, GSK, Roche, Roche Chugai, Sanofi, Sanofi Aventis, Sanofi-Aventis. A. Cauli: BMS, Celgene, Lilly, Lilly MSD, MSD, Novartis, Pfizer, Sanofi, Sigma Wesseumen, UCB. C. John: None. A. Nerviani: None. G. Thornborn: None. D. Holroyd: None. M. Congia: None. C. Thompson: None. P. Reynolds: None. J. Cañete: None. R. J. Moots: Biogen, Bristol-Myers Squibb, Chugai,

Novartis, Pfizer Inc, Roche, Sandoz, UCB. P.C. Taylor: AbbVie, Biogen, Celgene, Eli Lilly and Company, Fresenius, Fresenius SE & Co, Galapagos, Gilead. GlaxoSmithKline, Janssen, Lilly, Nordic Pharma, Pfizer, Pfizer Inc, Roche, Sanofi, UCB. C. Edwards: Abbvie, Biogen, BMS, Fresenius, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, UCB. J. Isaacs: None. P. Sasieni: None. J. E. Fonesca: None. E. Choy: AbbVie, Abbvie, Roche, Chugai, Amgen, Eli Lilly, Janssen, Novartis, Regeneron, R-Pharm and Sanofi, Amgen, Amgen, Roche, Chugai, Bristol-Myers Squibb, Eli-Lilly Janssen, Pfizer, Regeneron, Sanofi and UCB., AstraZeneca, Bio-Cancer, Bio-Cancer, Biogen, Novartis, Sanofi, Roche, Pfizer and UCB ,Biogen, BMS, Boehringer Ingelheim, Celgene, Chugai Pharma, Eli Lilly, Ferring Pharmaceuticals, GSK, Hospira, Janssen, Jazz Pharmaceuticals, Merck Sharp & Dohme, Merrimack Pharmaceutical, Napp, Novartis, Novimmune, ObsEva, Pfizer, Regeneron, Roche, R-Pharm, Sanofi, SynAct Pharma, Tonix, Union Chimique Belge. C. Pitzalis: None. NIHR have funded the study.

O20 Histological and molecular features of the diseased synovium in early untreated PsA in comparison with RA

Background

Psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are clinically distinct autoimmune joint disorders both marked by the chronic infiltration of the synovial tissue (ST) by inflammatory cells. It has been proposed that a more prominent thickening of the lining layer and a higher number of T/B-cells within the sublining characterised RA-ST. However, in most studies, patients had established disease and were already exposed to treatments. Furthermore, a prevalent number of samples from large joints may have affected these conclusions. Here, we intended to portrait the histological and molecular characteristics of the PsA-ST before any therapeutic modulation and early in the disease in comparison with RA and correlate them with the clinical features.

Methods

183 consecutive patients naïve to DMARDs/steroids with ongoing symptoms for less than 12 months and at least one inflamed joint entered the Pathobiology of Early Arthritis Cohort (PEAC) at the Barts Health NHS Trust and underwent a US-guided synovial biopsy. ST was immuno-stained for CD3-CD20-CD138-CD68 to quantify the cellular infiltrate by T-cells, B-cells, plasma cells and macrophages, respectively. Based on the semi-quantitative score (0-4) of the immune markers, patients were categorised in lympho-myeloid (CD20≥2 or CD138&gt;2), diffuse-myeloid (CD68 sublining≥2, CD20 and CD138&lt;2) and pauci-immune (CD68sublining&lt;2 and/or CD3-CD20-CD138&lt;1). Molecular analysis was performed using RNA-sequencing of 93 RA and 15 PsA-ST. RNA cellular content was quantified using Fantom5-gene-modules.

Results

Of 183 patients, 39 were diagnosed with PsA (32 polyarticular, 7 oligoarticular) and 144 with RA (2010 ACR/EULAR criteria). Age was significantly lower in PsA patients. Small joints were biopsied in 74.4% of PsA and 82% of RA patients. US-synovial thickening score of the biopsied joint was, on average, higher in PsA while the power-doppler signal was similar. The histological comparison proved fewer infiltrating T/B-cells, plasma cells and sublining macrophages in PsA than RA, yet a comparable macrophage composition of the lining. The pathotypes' distribution was different, with prevalent pauci-immune in PsA (43.2%) and lympho-myeloid in RA (43.2%). At baseline, the number of tender/swollen joints was significantly higher in RA, while there were no differences in other clinical parameters such as DAS28. In PsA, synovial pathotypes did not define clinical phenotypes, whereas RA pauci-immune patients had less severe disease activity than lympho-myeloid; this relation was confirmed in an age/gender-matched to PsA subset of 26 RA subjects. The molecular profiling revealed that PsA-ST composition had a greater content of fibroblasts, eosinophils and neutrophils. Moreover, PsA-ST had higher expression of neutrophil recruitment/enrichment, cell migration and cytoskeleton remodelling gene-modules clusters.

Conclusion

Discovering distinct synovial tissue signatures characterising early treatment-naive PsA will provide a better understanding of the disease pathogenesis and suggest innovative therapeutic targets.

Disclosures

A. Nerviani None. G. Lliso-Ribera None. M. Boutet None. K. Goldmann None. F. Rivellese None. S. Kelly None. M. Bombardieri None. M. Lewis None. F. Humby None. C. Pitzalis None.

Synovial tissue signatures enhance clinical classification and prognostic/treatment response algorithms in early inflammatory arthritis and predict requirement for subsequent biological therapy: results from the pathobiology of early arthritis cohort (PEAC)

OBJECTIVE

To establish whether synovial pathobiology improves current clinical classification and prognostic algorithms in early inflammatory arthritis and identify predictors of subsequent biological therapy requirement.

METHODS

200 treatment-naïve patients with early arthritis were classified as fulfilling RA1987 American College of Rheumatology (ACR) criteria (RA1987) or as undifferentiated arthritis (UA) and patients with UA further classified into those fulfilling RA2010 ACR/European League Against Rheumatism (EULAR) criteria. Treatment requirements at 12 months (Conventional Synthetic Disease Modifying Antirheumatic Drugs (csDMARDs) vs biologics vs no-csDMARDs treatment) were determined. Synovial tissue was retrieved by minimally invasive, ultrasound-guided biopsy and underwent processing for immunohistochemical (IHC) and molecular characterisation. Samples were analysed for macrophage, plasma-cell and B-cells and T-cells markers, pathotype classification (lympho-myeloid, diffuse-myeloid or pauci-immune) by IHC and gene expression profiling by Nanostring.

RESULTS

128/200 patients were classified as RA1987, 25 as RA2010 and 47 as UA. Patients classified as RA1987 criteria had significantly higher levels of disease activity, histological synovitis, degree of immune cell infiltration and differential upregulation of genes involved in B and T cell activation/function compared with RA2010 or UA, which shared similar clinical and pathobiological features. At 12-month follow-up, a significantly higher proportion of patients classified as lympho-myeloid pathotype required biological therapy. Performance of a clinical prediction model for biological therapy requirement was improved by the integration of synovial pathobiological markers from 78.8% to 89%-90%.

CONCLUSION

The capacity to refine early clinical classification criteria through synovial pathobiological markers offers the potential to predict disease outcome and stratify therapeutic intervention to patients most in need.

Extracellular traps and PAD4 released by macrophages induce citrullination and auto-antibody production in autoimmune arthritis

The mechanisms underlying the transition of rheumatoid arthritis (RA) systemic autoimmunity to the joints remain largely unknown. Here, we demonstrate that macrophages in the secondary lymphoid organs (SLOs) and synovial ectopic lymphoid-like structures (ELSs) express peptidylarginine deiminase 4 (PAD4) in murine collagen induced arthritis (CIA) and synovial biopsies from RA patients. Moreover, peptidyl citrulline colocalized with macrophages in SLOs and ELSs, and depletion of macrophages in CIA decreased lymphoid tissue citrullination and serum anti-citrullinated protein/peptide antibody (ACPA) levels. Furthermore, PAD was released from activated murine and RA synovial tissue and fluid (SF) macrophages which functionally deiminated extracellular proteins/peptides in vitro. Additionally, activated murine and SF macrophages displayed macrophage extracellular trap formation (METosis) and release of intracellular citrullinated histones. Moreover, presentation of citrullinated proteins induced ACPA production in vitro. Thus, lymphoid tissue macrophages contribute to self-antigen citrullination and ACPA production, indicating that their selective targeting would potentially ameliorate citrullination-dependent autoimmune disorders.

Synovial tissue signatures enhance clinical classification and prognostic/treatment response algorithms in early inflammatory arthritis and predict requirement for subsequent biological therapy: results from the pathobiology of early arthritis cohort (PEAC)

OBJECTIVE

To establish whether synovial pathobiology improves current clinical classification and prognostic algorithms in early inflammatory arthritis and identify predictors of subsequent biological therapy requirement.

METHODS

200 treatment-naïve patients with early arthritis were classified as fulfilling RA1987 American College of Rheumatology (ACR) criteria (RA1987) or as undifferentiated arthritis (UA) and patients with UA further classified into those fulfilling RA2010 ACR/European League Against Rheumatism (EULAR) criteria. Treatment requirements at 12 months (Conventional Synthetic Disease Modifying Antirheumatic Drugs (csDMARDs) vs biologics vs no-csDMARDs treatment) were determined. Synovial tissue was retrieved by minimally invasive, ultrasound-guided biopsy and underwent processing for immunohistochemical (IHC) and molecular characterisation. Samples were analysed for macrophage, plasma-cell and B-cells and T-cells markers, pathotype classification (lympho-myeloid, diffuse-myeloid or pauci-immune) by IHC and gene expression profiling by Nanostring.

RESULTS

128/200 patients were classified as RA1987, 25 as RA2010 and 47 as UA. Patients classified as RA1987 criteria had significantly higher levels of disease activity, histological synovitis, degree of immune cell infiltration and differential upregulation of genes involved in B and T cell activation/function compared with RA2010 or UA, which shared similar clinical and pathobiological features. At 12-month follow-up, a significantly higher proportion of patients classified as lympho-myeloid pathotype required biological therapy. Performance of a clinical prediction model for biological therapy requirement was improved by the integration of synovial pathobiological markers from 78.8% to 89%-90%.

CONCLUSION

The capacity to refine early clinical classification criteria through synovial pathobiological markers offers the potential to predict disease outcome and stratify therapeutic intervention to patients most in need.

Synovial tissue signatures enhance clinical classification and prognostic/treatment response algorithms in early inflammatory arthritis and predict requirement for subsequent biological therapy: results from the pathobiology of early arthritis cohort (PEAC)

OBJECTIVE

To establish whether synovial pathobiology improves current clinical classification and prognostic algorithms in early inflammatory arthritis and identify predictors of subsequent biological therapy requirement.

METHODS

200 treatment-naïve patients with early arthritis were classified as fulfilling RA1987 American College of Rheumatology (ACR) criteria (RA1987) or as undifferentiated arthritis (UA) and patients with UA further classified into those fulfilling RA2010 ACR/European League Against Rheumatism (EULAR) criteria. Treatment requirements at 12 months (Conventional Synthetic Disease Modifying Antirheumatic Drugs (csDMARDs) vs biologics vs no-csDMARDs treatment) were determined. Synovial tissue was retrieved by minimally invasive, ultrasound-guided biopsy and underwent processing for immunohistochemical (IHC) and molecular characterisation. Samples were analysed for macrophage, plasma-cell and B-cells and T-cells markers, pathotype classification (lympho-myeloid, diffuse-myeloid or pauci-immune) by IHC and gene expression profiling by Nanostring.

RESULTS

128/200 patients were classified as RA1987, 25 as RA2010 and 47 as UA. Patients classified as RA1987 criteria had significantly higher levels of disease activity, histological synovitis, degree of immune cell infiltration and differential upregulation of genes involved in B and T cell activation/function compared with RA2010 or UA, which shared similar clinical and pathobiological features. At 12-month follow-up, a significantly higher proportion of patients classified as lympho-myeloid pathotype required biological therapy. Performance of a clinical prediction model for biological therapy requirement was improved by the integration of synovial pathobiological markers from 78.8% to 89%-90%.

CONCLUSION

The capacity to refine early clinical classification criteria through synovial pathobiological markers offers the potential to predict disease outcome and stratify therapeutic intervention to patients most in need.

Inflammatory cytokines shape a changing DNA methylome in monocytes mirroring disease activity in rheumatoid arthritis

Objective

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that mainly targets joints. Monocytes and macrophages are critical in RA pathogenesis and contribute to inflammatory lesions. These extremely plastic cells respond to extracellular signals which cause epigenomic changes that define their pathogenic phenotype. Here, we interrogated how DNA methylation alterations in RA monocytes are determined by extracellular signals.

Methods

High-throughput DNA methylation analyses of patients with RA and controls and in vitro cytokine stimulation were used to investigate the underlying mechanisms behind DNA methylation alterations in RA as well as their relationship with clinical parameters, including RA disease activity.

Results

The DNA methylomes of peripheral blood monocytes displayed significant changes and increased variability in patients with RA with respect to healthy controls. Changes in the monocyte methylome correlate with DAS28, in which high-activity patients are divergent from healthy controls in contrast to remission patients whose methylome is virtually identical to healthy controls. Indeed, the notion of a changing monocyte methylome is supported after comparing the profiles of same individuals at different stages of activity. We show how these changes are mediated by an increase in disease activity-associated cytokines, such as tumour necrosis factor alpha and interferons, as they recapitulate the DNA methylation changes observed in patients in vitro.

Conclusion

We demonstrate a direct link between RA disease activity and the monocyte methylome through the action of inflammation-associated cytokines. Finally, we have obtained a DNA methylation-based mathematical formula that predicts inflammation-mediated disease activity for RA and other chronic immune-mediated inflammatory diseases.

To Supplement or not to Supplement? The Rationale of Vitamin D Supplementation in Systemic Lupus Erythematosus

Background:

Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease characterised by abnormal activation of the immune system, chronic inflammation and organ damage. Lupus patients are more prone to be vitamin D deficient. However, current evidence is not conclusive with regards to the role played by vitamin D in SLE development, progression, and clinical manifestations.

Objective:

Here, we will summarise the current knowledge about vitamin D deficiency prevalence, risk factors, molecular effects, and potential pathogenic role in SLE. We will focus on the link between vitamin D deficiency and lupus clinical manifestations, and on the clinical trials assessing the effects of vitamin D supplementation in SLE.

Method:

A detailed literature search was performed exploiting the available databases, using “vitamin D and lupus/SLE” as keywords. The relevant interventional trials published over the last decade have been considered and the results are reported here.

Conclusion:

Several immune cells express vitamin D receptors. Thus, an immunomodulatory role for vitamin D in lupus is plausible. Numerous observational studies have investigated the relationship between vitamin D levels and clinical/serological manifestations of SLE with contrasting results. Negative correlations between vitamin D levels and disease activity, fatigue, renal and cardiovascular disease, and anti-dsDNA titres have been described but not conclusively accepted. In experimental models of lupus, vitamin D supplementation can improve the disease. Interventional trials have assessed the potential therapeutic value of vitamin D in SLE, but further larger studies are needed.

Redox-Mediated Mechanisms Fuel Monocyte Responses to CXCL12/HMGB1 in Active Rheumatoid Arthritis

Chemokine synergy-inducing molecules are emerging as regulating factors in cell migration. The alarmin HMGB1, in its reduced form, can complex with CXCL12 enhancing its activity on monocytes via the chemokine receptor CXCR4, while the form containing a disulfide bond, by binding to TLR2 or TLR4, initiates a cascade of events leading to production of cytokines and chemokines. So far, the possibility that the CXCL12/HMGB1 heterocomplex could be maintained in chronic inflammation was debated, due to the release of reactive oxygen species. Therefore, we have assessed if the heterocomplex could remain active in Rheumatoid Arthritis (RA) and its relevance in the disease assessment. Monocytes from RA patients with active disease require a low concentration of HMGB1 to enhance CXCL12-induced migration, in comparison to monocytes from patients in clinical remission or healthy donors. The activity of the heterocomplex depends on disease activity, on the COX2 and JAK/STAT pathways, and is determined by the redox potential of the microenvironment. In RA, the presence of an active thioredoxin system correlates with the enhanced cell migration, and with the presence of the heterocomplex in the synovial fluid. The present study highlights how, in an unbalanced microenvironment, the activity of the thioredoxin system plays a crucial role in sustaining inflammation. Prostaglandin E2 stimulation of monocytes from healthy donors is sufficient to recapitulate the response observed in patients with active RA. The activation of mechanisms counteracting the oxidative stress in the extracellular compartment preserves HMGB1 in its reduced form, and contributes to fuel the influx of inflammatory cells. Targeting the heterocomplex formation and its activity could thus be an additional tool for dampening the inflammation sustained by cell recruitment, for those patients with chronic inflammatory conditions who poorly respond to current therapies.

Mast cells in early rheumatoid arthritis associate with disease severity and support B cell autoantibody production

OBJECTIVES

Mast cells (MCs) are involved in the pathogenesis of rheumatoid arthritis (RA). However, their contribution remains controversial. To establish their role in RA, we analysed their presence in the synovium of treatment-naïve patients with early RA and their association and functional relationship with histological features of synovitis.

METHODS

Synovial tissue was obtained by ultrasound-guided biopsy from treatment-naïve patients with early RA (n=99). Immune cells (CD3/CD20/CD138/CD68) and their relationship with CD117⁺MCs in synovial tissue were analysed by immunohistochemistry (IHC) and immunofluorescence (IF). The functional involvement of MCs in ectopic lymphoid structures (ELS) was investigated in vitro, by coculturing MCs with naïve B cells and anticitrullinated protein antibodies (ACPA)-producing B cell clones, and in vivo in interleukin-27 receptor alpha (IL27ra)-deficient and control mice during antigen-induced arthritis (AIA).

RESULTS

High synovial MC counts are associated with local and systemic inflammation, autoantibody positivity and high disease activity. IHC/IF showed that MCs reside at the outer border of lymphoid aggregates. Furthermore, human MCs promote the activation and differentiation of naïve B cells and induce the production of ACPA, mainly via contact-dependent interactions. In AIA, synovial MC numbers increase in IL27ra deficient mice, in association with ELS and worse disease activity.

CONCLUSIONS

Synovial MCs identify early RA patients with a severe clinical form of synovitis characterised by the presence of ELS.

Role of chemokines in ectopic lymphoid structures formation in autoimmunity and cancer

Ectopic (or tertiary) lymphoid structures (ELS) are organized aggregates of lymphocytes resembling secondary lymphoid organs and developing in chronically inflamed nonlymphoid tissues during persistent infections, graft rejection, autoimmune conditions, and cancer. In this review, we will first depict the mechanisms regulating ELS generation, focusing on the role played by lymphoid chemokines. We will then characterize ELS forming in target organs during autoimmune conditions, here exemplified by rheumatoid arthritis, and cancer, highlighting the relevance of the tissue-specific factors. Finally, we will discuss the clinical significance of ELS and the therapeutic potential of their inhibition and/or enhancement depending on the disease considered.

Role of the IL-23/IL-17 Axis in Psoriasis and Psoriatic Arthritis: The Clinical Importance of Its Divergence in Skin and Joints

Psoriasis is a chronic systemic inflammatory disease causing erythematosus and scaly skin plaques; up to 30% of patients with psoriasis develop Psoriatic Arthritis (PsA), which is characterised by inflammation and progressive damage of the peripheral joints and/or the spine and/or the entheses. The pathogenic mechanisms driving the skin disorder in psoriasis and the joint disease in PsA are sustained by the activation of inflammatory pathways that can be overlapping, but also, at least partially, distinct. Cytokines members of the IL-23/IL-17 family, critical in the development of autoimmunity, are abundantly expressed within the cutaneous lesions but also seem to be involved in chronic inflammation and damage of the synovium though, as it will be here discussed, not in all patients. In this review, we will focus on the state of the art of the molecular features of psoriatic skin and joints, focusing on the specific role of the IL-23/IL-17 pathway in each of these anatomical districts. We will then offer an overview of the approved and in-development biologics targeting this axis, emphasising how the availability of the “target” in the diseased tissues could provide a plausible explanation for the heterogeneous clinical efficacy of these drugs, thus opening future perspective of personalised therapies.

Endothelial Dysfunction in Systemic Lupus Erythematosus: Pathogenesis, Assessment and Therapeutic Opportunities

BACKGROUND

Systemic Lupus Erythematosus (SLE) is characterised by increased mortality secondary to Cardiovascular Diseases (CVD). Despite being common in SLE, traditional cardiovascular risk factors cannot entirely justify such increase in CVD-associated mortality. The endothelium is a key regulator of the vascular homeostasis; lupus-associated persistent systemic inflammation may impair endothelium functionality, thus initiating a cascade of events that, in concert with traditional CVD-risk factors, leads to atherosclerosis development and progression. Numerous methods have been used for the in vivo assessment of the endothelial function; among all, Flow- Mediated Dilatation (FMD) has been widely validated in clinical trials. Quantification of the endothelial dysfunction by FMD has been confirmed to be an early predictor of CVD in multiple studies involving both non-CVD and CVD-population and it may therefore represent a likewise efficient biomarker of CVD in SLE.

METHODS

Research and online content related to endothelial function in SLE is reviewed in this article with special attention to the pathophysiology and therapeutic opportunities.

RESULTS

To date, the vast majority of the available data, albeit not all, shows that endotheliumdependent FMD values are lower in SLE patients compared to healthy subjects; further studies, however, will be required in order to confirm the usefulness of the endothelial dysfunction quantification as CVD-predictor in the specific clinical setting of lupus. Notably, FMD variations can also be a sensitive marker for assessing specific therapeutic strategies ability of improving endothelial function in SLE patients.

CONCLUSION

Endothelial function appears to be affected by SLE potentially contributing to the increased cardiovascular risk observed in SLE patients.

Mast cells in rheumatoid arthritis: friends or foes?

Mast cells are tissue-resident cells of the innate immunity, implicated in the pathogenesis of many autoimmune diseases, including rheumatoid arthritis (RA). They are present in synovia and their activation has been linked to the potentiation of inflammation in the course of RA. However, recent investigations questioned the role of mast cells in arthritis. In particular, animal models generated conflicting results, so that many of their pro-inflammatory, i.e. pro-arthritogenic functions, even though supported by robust experimental evidence, have been labelled as redundant. At the same time, a growing body of evidence suggests that mast cells can act as tunable immunomodulatory cells. These characteristics, not yet fully understood in the context of RA, could partially explain the inconsistent results obtained with experimental models, which do not account for the pro- and anti-inflammatory functions exerted in more chronic heterogeneous conditions such as RA. Here we present an overview of the current knowledge on mast cell involvement in RA, including the intriguing hypothesis of mast cells acting as subtle immunomodulatory cells and the emerging concept of synovial mast cells as potential biomarkers for patient stratification.

Ectopic Lymphoid Structures: Powerhouse of Autoimmunity

Ectopic lymphoid structures (ELS) often develop at sites of inflammation in target tissues of autoimmune diseases, such as rheumatoid arthritis, Sjögren’s syndrome, multiple sclerosis, myasthenia gravis, and systemic lupus erythematosus. ELS are characterized by the formation of organized T/B cells aggregates, which can acquire follicular dendritic cells network supporting an ectopic germinal center response. In this review, we shall summarize the mechanisms that regulate the formation of ELS in tertiary lymphoid organs, with particular emphasis on the role of lymphoid chemokines in both formation and maintenance of ELS, the role of emerging positive and negative regulators of ELS development and function, including T follicular helper cells and IL-27, respectively. Finally, we shall discuss the main functions of ELS in supporting the affinity maturation, clonal selection, and differentiation of autoreactive B cells contributing to the maintenance and perpetuation of humoral autoimmunity.

Autophagy generates citrullinated peptides in human synoviocytes: a possible trigger for anti-citrullinated peptide antibodies

OBJECTIVES

Autophagy may represent a functional processing event that creates a substrate for autoreactivity. In particular, autophagy may play a role in the pathogenesis of RA, since autophagy is a key cellular event involved in the generation of citrullinated peptides, with consequent breakage of tolerance. Thus, in RA, autophagy may be the common feature in several situations (including smoking, joint injury and infection) that may drive the adaptive responses to citrullinated self-proteins. The aim of this study was the analysis, in vitro, of the role of autophagy in the generation of citrullinated peptides and, in vivo, of the relationship between autophagy and the production of anti-CCP antibodies (Abs).

METHODS

For autophagy induction, fibroblast-like synoviocytes, primary fibroblasts and monocytes were stimulated with tunicamycin or rapamycin. Peptidyl arginine deiminase activity was tested by enzyme-linked immunosorbent assay, and protein citrullination was evaluated by western blotting. The main citrullinated RA candidate antigens, vimentin, α-enolase and filaggrin, were demonstrated by immunoprecipitation. The relationship between autophagy and anti-CCP Abs was analysed in 30 early-active RA patients.

RESULTS

Our results demonstrated in vitro a role for autophagy in the citrullination process. Cells treated with tunicamycin or rapamycin showed peptidyl arginine deiminase 4 activation, with consequent protein citrullination. Immunoblotting and immunoprecipitation experiments, using specific Abs, identified the main citrullinated proteins: vimentin, α-enolase and filaggrin. In vivo, a significant association between levels of autophagy and anti-CCP Abs was observed in treatment-naïve early-active RA patients.

CONCLUSION

These findings support the view that the processing of proteins in autophagy generates citrullinated peptides recognized by the immune system in RA.