Deregulation in adult IgA vasculitis skin as the basis for the discovery of novel serum biomarkers

INTRODUCTION

Immunoglobulin A vasculitis (IgAV) in adults has a variable disease course, with patients often developing gastrointestinal and renal involvement and thus contributing to higher mortality. Due to understudied molecular mechanisms in IgAV currently used biomarkers for IgAV visceral involvement are largely lacking. Our aim was to search for potential serum biomarkers based on the skin transcriptomic signature.

METHODS

RNA sequencing analysis was conducted on skin biopsies collected from 6 treatment-naïve patients (3 skin only and 3 renal involvement) and 3 healthy controls (HC) to get insight into deregulated processes at the transcriptomic level. 15 analytes were selected and measured based on the transcriptome analysis (adiponectin, lipopolysaccharide binding protein (LBP), matrix metalloproteinase-1 (MMP1), C-C motif chemokine ligand (CCL) 19, kallikrein-5, CCL3, leptin, C-X-C motif chemokine ligand (CXCL) 5, osteopontin, interleukin (IL)-15, CXCL10, angiopoietin-like 4 (ANGPTL4), SERPIN A12/vaspin, IL-18 and fatty acid-binding protein 4 (FABP4)) in sera of 59 IgAV and 22 HC. Machine learning was used to assess the ability of the analytes to predict IgAV and its organ involvement.

RESULTS

Based on the gene expression levels in the skin, we were able to differentiate between IgAV patients and HC using principal component analysis (PCA) and a sample-to-sample distance matrix. Differential expression analysis revealed 49 differentially expressed genes (DEGs) in all IgAV patient's vs. HC. Patients with renal involvement had more DEGs than patients with skin involvement only (507 vs. 46 DEGs) as compared to HC, suggesting different skin signatures. Major dysregulated processes in patients with renal involvement were lipid metabolism, acute inflammatory response, and extracellular matrix (ECM)-related processes. 11 of 15 analytes selected based on affected processes in IgAV skin (osteopontin, LBP, ANGPTL4, IL-15, FABP4, CCL19, kallikrein-5, CCL3, leptin, IL-18 and MMP1) were significantly higher (p-adj < 0.05) in IgAV serum as compared to HC. Prediction models utilizing measured analytes showed high potential for predicting adult IgAV.

CONCLUSION

Skin transcriptomic data revealed deregulations in lipid metabolism and acute inflammatory response, reflected also in serum analyte measurements. LBP, among others, could serve as a potential biomarker of renal complications, while adiponectin and CXCL10 could indicate gastrointestinal involvement.

Disturbed Antioxidant Capacity in Patients with Systemic Sclerosis Associates with Lung and Gastrointestinal Symptoms

The correct balance between reactive oxygen species and antioxidant defense in an organism is disturbed in oxidative stress. To assess oxidative balance in 36 SSc patients and 26 healthy controls (HCs), we measured reactive oxidative metabolites (ROMs), total antioxidant capacity (TAC), lipid peroxidation (measuring 4-HNE), and DNA oxidative damage (measuring 8-OHdG) in serum. Furthermore, DNA breaks in leukocytes of 35 SSc patients and 32 HCs were evaluated using COMET. While we report high ROMs for both SSc patients and age/sex matched HC samples, there was a significant increase in TAC in SSc patients as compared to HCs, and thus also a significantly higher oxidative stress index in SSc patients. TAC was significantly higher in SSc patients with ILD and gastrointestinal involvement, as well as in patients with anti-topoisomerase antibodies. We observe no difference in serum lipid peroxidation status or oxidative DNA damage. However, SSc patients had significantly more leukocyte DNA breaks than HCs; the most damage was observed in patients treated with immunosuppressives. Thus, our study confirms presence of oxidative stress and increased DNA damage in leukocytes of SSc patients; however, it points toward increased antioxidant capacity, which needs to be further studied.

Correlation of the High-Resolution Computed Tomography Patterns of Intrathoracic Sarcoidosis with Serum Levels of SAA, CA 15.3, SP-D, and Other Biomarkers of Interstitial Lung Disease

Studies on the serum biomarkers of granulomatous inflammation and pulmonary interstitial disease in intrathoracic sarcoidosis have shown conflicting results. We postulated that differences in the concentrations of serum biomarkers can be explained by the heterogenous patterns of sarcoidosis seen on thoracic HRCT. Serum biomarker levels in 79 consecutive patients, newly diagnosed with intrathoracic sarcoidosis, were compared to our control group of 56 healthy blood donors. An analysis was performed with respect to HRCT characteristics (the presence of lymph node enlargement, perilymphatic or peribronchovascular infiltrates, ground-glass lesions, or fibrosis), CXR, and disease extent. Serum levels of CXCL9, CXCL10, CTO, and CCL18 were statistically significantly increased in all patients compared to controls. Serum levels of CA15.3 were statistically significantly increased in all patients with parenchymal involvement. SAA was increased in patients with ground-glass lesions while SP-D levels were statistically significantly increased in patients with lung fibrosis. Only SP-D and CA15.3 showed a significant correlation to interstitial disease extent. In conclusion, we found that sarcoidosis patients with different HRCT patterns of intrathoracic sarcoidosis have underlying biochemical differences in their serum biomarkers transcending Scadding stages. The stratification of patients based on both radiologic and biochemical characteristics could enable more homogenous patient selection for further prognostic studies.

Molecular and Cellular Markers in Chlorhexidine-Induced Peritoneal Fibrosis in Mice

Understanding the tissue changes and molecular mechanisms of preclinical models is essential for creating an optimal experimental design for credible translation into clinics. In our study, a chlorhexidine (CHX)-induced mouse model of peritoneal fibrosis was used to analyze histological and molecular/cellular alterations induced by 1 and 3 weeks of intraperitoneal CHX application. CHX treatment for 1 week already caused injury, degradation, and loss of mesothelial cells, resulting in local inflammation, with the most severe structural changes occurring in the peritoneum around the ventral parts of the abdominal wall. The local inflammatory response in the abdominal wall showed no prominent differences between 1 and 3 weeks. We observed an increase in polymorphonuclear cells in the blood but no evidence of systemic inflammation as measured by serum levels of serum amyloid A and interleukin-6. CHX-induced fibrosis in the abdominal wall was more pronounced after 3 weeks, but the gene expression of fibrotic markers did not change over time. Complement system molecules were strongly expressed in the abdominal wall of CHX-treated mice. To conclude, both histological and molecular changes were already present in week 1, allowing examination at the onset of fibrosis. This is crucial information for refining further experiments and limiting the amount of unnecessary animal suffering.

AB0149 RNA SEQUENCING OF SKIN BIOPSY SAMPLES REVEALS UNIQUE BIOLOGICAL PROCESSES AMONG SPECIFIC GROUPS OF ADULT PATIENTS WITH IgA VASCULITIS

Background

Immunoglobulin A vasculitis (IgAV) is a small vessel leukocytoclastic vasculitis, characterized by vascular IgA deposits, and clinically by skin, join, kidney and bowel involvement. Renal involvement, present in up to 84% of adult patients, is associated with an increased risk of progression to chronic kidney failure. A skin or renal biopsy is still the golden standard for diagnosis. Omics data from NCBI-GEO and Array Express databanks are lacking from IgAV samples of adult patients.

Objectives

Our aim was to perform RNA sequencing and to identify differentially expressed genes and dysregulated molecular pathways in the affected skin of adult IgAV patients with renal involvement, patients with skin-limited IgAV and healthy controls (HC).

Methods

Skin biopsy samples were collected from treatment-naive adult IgAV patients at time of diagnostic procedure: 1) skin-limited disease (n=3), 2), IgAV with renal involvement (n=3), and age-/sex-matched HC (n=3). RNA was isolated and 100 bp paired-end sequenced using the Illumina HiSeq 4000 platform (25.9 to 30.8 million reads were obtained per sample). Reads were mapped with Salmon tool against the human transcriptome (Ensemble Release 104). Differentially expressed genes (log2 fold change ≥ │1│, padj < 0.05) were computed using the R package DESeq2. Data were clustered using principal component analysis (PCA), and KEGG pathway over-representation analysis (ORA) was performed with R package clusterProfiler.

Results

We identified 72 differentially expressed genes (34 up- and 38 down-regulated) between skin-limited IgAV and HC, while 686 genes were differentially expressed (421 up- and 265 down-regulated) in the affected skin between adult IgAV patients with renal involvement and healthy controls (HC). PCA distinguished between IgAV (renal and skin-limited) and healthy controls, suggesting specific transcriptome signatures in IgAV. 21 overlapping genes were differentially expressed in both groups of patients in comparison to HC. 196 genes were differentially expressed between IgAV patients with renal involvement compared to skin-limited IgAV.

Genes, differentially expressed in patients with skin-limited disease were enriched in the oxidative phosphorylation (padj = 3.08 x 10-5) and cell adhesion molecules (padj = 6.32 x 10-4) KEGG Pathways. Differentially expressed genes in patients with renal involvement exhibited enriched KEGG Pathways involved in the ribosome (padj = 0 x 10-7), the regulation of lipolysis in adipocytes (padj 9,066 x 10-4), cell adhesion molecules (padj = 8.0008 x 10-3), renin secretion (padj = 4.2882 x 10-3), complement and coagulation cascades (padj = 3.58547 x 10-2), vascular smooth muscle contraction (padj = 3.76132 x 10-2) and aldosterone synthesis and secretion (padj = 3.76132 x 10-2).

Conclusion

Deregulated genes in skin of adult IgAV patients with renal manifestation could serve as biomarkers for organ-specific involvement. Further studies are needed that would support deciphering the involvement of perturbed molecular pathways and the contribution of individual cell types to skin manifestations of adult IgAV patients.

Acknowledgements

The authors also wish to thank all the patients who volunteered to participate into this study and the funding.

Disclosure of Interests

None declared

OP0095 SINGLE-CELL RNA SEQUENCING REVEALS POTENT ANTI-INFLAMMATORY AND ANTIFIBROTIC ACTIVITIES OF DIMETHYL-ALPHA-KETOGLUTARATE ON EXPLANTED SKIN FROM PATIENTS WITH SYSTEMIC SCLEROSIS

Background

Activated fibroblasts are the main drivers of skin fibrosis in SSc. We have recently identified dimethyl alpha-ketoglutarate (dm-aKG) as a potential repressor of myofibroblast differentiation and profibrotic activity in cultured skin fibroblasts.

Objectives

To further analyse the clinical translation of our findings by investigating the antifibrotic capacity of dm-aKG on explanted skin biopsies from SSc patients.

Methods

We cultured forearm punch skin biopsies from SSc patients (n=10) for 24h ex vivo in the presence/absence of 6 mM dm-aKG. Thereafter, skin biopsies (n=4) were dissociated into single cells using a combined mechanical-enzymatic dissociation protocol, followed by single cell (sc)RNA-seq library preparation (10x Genomics) and sequencing (Illumina, NovaSeq6000, 50,000 reads/cell). We mapped the scRNA-seq reads to the reference genome GRCh38.p13 and analysed the data with R/Bioconductor tools. We deconvoluted cell types in bulk skin transcriptomes from SSc cohorts (GSE: 45485, 59785, 9285, 32413) using human skin scRNA-seq data1. The secretion of IL-6, procollagen-1, PRO-C1 (N-terminal type I collagen pro-peptide), C1M (MMP-degradation fragment of type I collagen), and fibronectin (FBN-C) from cultured skin (n=10) was measured in supernatants by ELISA. We analysed gene and protein expression in TGFβ-activated healthy and SSc dermal fibroblasts (DF, n=10) treated or not with dm-aKG using qPCR, Western blot and ELISA. Contractile properties of DF were assessed by gel contraction assay. Traction forces generated by DF were determined by reference-free traction force microscopy.

Results

Dissociated cultured SSc skin exhibited comparable cell yield and viability in the presence (20,203; 89%) and absence (25,280; 93%) of dm-aKG, respectively. scRNA-seq skin analysis included 20,869 high quality single cell profiles segregating into 10 distinct skin cell populations (Figure 1A). This analysis demonstrated decreased proportion of fibroblasts and increased proportion of keratinocytes in dm-aKG treated skin (p<0.05; Figure 1B). Among skin cell types, skin fibroblasts exhibited the largest amount of differentially expressed genes upon dm-aKG treatment (44%, n=779, x-fold>0.5, FDR<0.05), suggesting that these cells are key targets of dm-aKG therapy in SSc skin. We identified inflammatory/cytokine signalling (hub genes IL6, STAT1) and extracellular matrix (ECM) organization (hub genes MMP1, ITGB3) as top downregulated biological processes in fibroblasts in dm-aKG treated SSc skin (Figure 1C), coinciding with a decreased abundance of proinflammatory skin fibroblast subpopulation. Specifically, these cells were identified as the main source of IL6 (Figure 1D) and were enriched in SSc skin as revealed by deconvolution analysis of skin transcriptomes. Furthermore, dm-aKG reduced the secretion of IL-6, procollagen-1 and C1M, but not pro-C1 and FBN-C, from cultured skin explants. In cultured DF, dm-aKG blocked the inflammatory (IL-6, pSTAT3), profibrotic (aSMA, Fibronectin, Procollagen-1, Pro-C1) and contractile activities, and significantly diminished traction forces exerted by DF on the matrix substrate.

Figure 1.

scRNA-seq – comparison of untreated and dm-aKG treated paired skin biopsies. (A) UMAP plot with annotated skin cells, (B) differential abundance of main skin cell types, (C) volcano plot of DE genes with top downregulated gene ontology (GO) pathways in dm-aKG treated skin fibroblasts, (D) IL6 expression in untreated (blue) and treated (pink) skin fibroblasts.

Conclusion

Dm-aKG broadly interferes with inflammatory and ECM organizational activities of skin fibroblasts in culture and in explanted skin from SSc patients. These results confirm that dm-aKG might represent a potential new therapeutic approach for efficient targeting of skin inflammation and fibrosis in SSc.

References

[1]He H et al. J Allergy Clin Immunol 2020

Acknowledgements

This work was supported by a research grant from FOREUM Foundation for Research in Rheumatology and University Medical Centre Ljubljana.

Disclosure of Interests

Blaž Burja: None declared, Dominique Paul: None declared, Reto Gerber: None declared, Sam G. Edalat: None declared, Muriel Elhai Speakers bureau: BMS, Elena Pachera: None declared, Rahel S. Zingg: None declared, Francesca Michela Pramotton: None declared, Sofie Falkenløve Madsen: None declared, Kristina Buerki: None declared, Giampietro Costanza: None declared, Michael Whitfield: None declared, Anne-Christine Bay-Jensen: None declared, Snežna Sodin-Šemrl: None declared, Matija Tomsic: None declared, Gabriela Kania: None declared, Hubert Rehrauer: None declared, Oliver Distler Speakers bureau: Bayer, Boehringer Ingelheim, Janssen, Medscape, Consultant of: Abbvie, Acceleron, Alcimed, Amgen, AnaMar, Arxx, AstraZeneca, Baecon, Blade, Bayer, Boehringer Ingelheim, Corbus, CSL Behring, 4P Science, Galapagos, Glenmark, Horizon, Inventiva, Kymera, Lupin, Miltenyi Biotec, Mitsubishi Tanabe, MSD, Novartis, Prometheus, Roivant, Sanofi and Topadur, Grant/research support from: Kymera, Mitsubishi Tanabe, Boehringer Ingelheim, Ziga Rotar: None declared, Mark Robinson: None declared, Katja Lakota: None declared, Mojca Frank Bertoncelj: None declared.

From Active to Non-active Giant Cell Arteritis: Longitudinal Monitoring of Patients on Glucocorticoid Therapy in Combination With Leflunomide

In the present study, we longitudinally monitored leukocyte subsets, expression of neutrophil surface adhesion molecules (CD62L and CD11b) and serum analytes in therapy-naïve patients with active giant cell arteritis (GCA). We collected blood samples at the baseline, and at weeks 1, 4, 12, 24, and 48 of follow-up, and evaluated short- and long-term effects of glucocorticoids (GC) vs. GC and leflunomide. Our aim was to identify candidate biomarkers that could be used to monitor disease activity and predict an increased risk of a relapse. Following high doses of GC, the numbers of CD4+ T-lymphocytes and B-lymphocytes transiently increased and then subsided when GC dose tapering started at week 4. In contrast, the numbers of neutrophils significantly increased during the follow-up time of 12 weeks compared to pre-treatment time. Neutrophil CD62L rapidly diminished after initiation of GC therapy, however its expression remained low at week 48, only in patients under combinatorial therapy with leflunomide. Levels of acute phase reactant SAA and IL-6 decreased significantly after treatment with GC and leflunomide, while levels of IL-8, IL-18, and CHI3L1 did not change significantly during the follow-up period. CHI3L1 was associated with signs of transmural inflammation and vessel occlusion and might therefore serve as a marker of fully developed active GCA, and a promising therapeutic target. Patients with relapses had higher levels of IL-23 at presentation than patients without relapses (p = 0.021). Additionally, the levels of IL-23 were higher at the time of relapse compared to the last follow-up point before relapse. IL-23 might present a promising biomarker of uncontrolled and active disease and could give early indication of upcoming relapses.

Single Cell RNA Sequencing in Autoimmune Inflammatory Rheumatic Diseases: Current Applications, Challenges and a Step Toward Precision Medicine

Single cell RNA sequencing (scRNA-seq) represents a new large scale and high throughput technique allowing analysis of the whole transcriptome at the resolution of an individual cell. It has emerged as an imperative method in life science research, uncovering complex cellular networks and providing indices that will eventually lead to the development of more targeted and personalized therapies. The importance of scRNA-seq has been particularly highlighted through the analysis of complex biological systems, in which cellular heterogeneity is a key aspect, such as the immune system. Autoimmune inflammatory rheumatic diseases represent a group of disorders, associated with a dysregulated immune system and high patient heterogeneity in both pathophysiological and clinical aspects. This complicates the complete understanding of underlying pathological mechanisms, associated with limited therapeutic options available and their long-term inefficiency and even toxicity. There is an unmet need to investigate, in depth, the cellular and molecular mechanisms driving the pathogenesis of rheumatic diseases and drug resistance, identify novel therapeutic targets, as well as make a step forward in using stratified and informed therapeutic decisions, which could now be achieved with the use of single cell approaches. This review summarizes the current use of scRNA-seq in studying different rheumatic diseases, based on recent findings from published in vitro, in vivo, and clinical studies, as well as discusses the potential implementation of scRNA-seq in the development of precision medicine in rheumatology.

AB0080 ALTERED CONCENTRATIONS OF DIFFERENT SMALL EXTRACELLULAR VESICLE POPULATIONS IN PLASMA OF PATIENTS WITH ANTIPHOSPHOLIPID SYNDROME

Background:

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by thrombosis, obstetric complications, and the presence of antiphospholipid antibodies (aPL) that cause endothelial injury and thrombophilia [1]. Extracellular vesicles (EVs) are involved in various thrombotic disorders [2], including APS [3, 4], and therefore may influence the prothrombotic status of APS patients. One of the hallmarks of activated endothelium is the expression of adhesion molecules, such as ICAM-1 (CD54) and E-selectin (CD62E), that play a key function in the interactions with leukocytes and platelets.

Objectives:

To determine the level of total tetraspanin (CD81/CD63/CD9)-positive vesicles and specific EV populations (CD54- and CD62E-positive EVs) in plasma from APS patients.

Methods:

Whole blood was collected from 4 APS patients and 3 healthy blood donors (HBDs) and processed to obtain platelet-depleted plasma. The size and concentration of EVs were determined using ExoView platform (NanoView Biosciences, MA, USA). In brief, EVs were captured and immobilized on ExoView Tetraspanin chips using the capture antibodies CD81, CD63, and CD9. Size was determined using SP-IRIS technology. Concentration measurements were performed with fluorescently labeled detection antibodies, specifically tetraspanins (CD81/CD63/CD9) for total EVs and CD54 and CD62E for specific EV populations.

Results:

Analysis of EVs size confirmed the presence of small EVs (sEVs, < 70 nm) in both study groups. The size of EVs did not vary significantly between study groups (mean size ± SD in APS vs. HBD; CD81 (63.1 ± 1.5 nm vs. 66.6 ± 10.6 nm), CD63 (63.3 ± 1.64 nm vs. 69.2 ± 13.2 nm), and CD9 capture spot (61.8 ± 1.18 nm vs. 64.1 ± 7.64 nm)). The levels of total EVs (tetraspanin-positive) were increased 1.7-fold, 1.4-fold, and 2.2-fold for CD81, CD63, and CD9 capture spots, respectively, in APS patients compared to HBDs (Figure 1A). In addition, CD54- and CD62E-positive EVs represented a small population (< 2 %) of the total EVs (Figure 1B). The levels of CD54 were increased 2.9-fold, 3.0-fold, and 2.5-fold on CD81, CD63, and CD9 capture spots, respectively, and similarly, the levels of CD62E were increased 2.2-fold, 2.7-fold, and 2.0-fold on CD81, CD63, and CD9 capture spots, respectively, in APS patients compared to HBDs (Figure 1A).

Figure 1.

Concentration of tetraspanin- (CD81/CD63/CD9), CD54- and CD62- positive sEVs in APS patients and HBDs.

Conclusion:

Higher levels of sEVs and increased percentage of CD54- and CD62E-positive sEVs in plasma of APS patients could indicate an altered and activated endothelium in those patients.

References:

[1]Miyakis S. Journal of thrombosis and haemostasis. 2006.

[2]Zara M. Int J Mol Sci. 2019.

[3]Chaturvedi S. Semin Thromb Hemost. 2018.

[4]Stok U. Cells. 2020.

[5]Oggero S. Front Pharmacol. 2019.

Disclosure of Interests:

Ula Stok: None declared, Alex Shephard Employee of: NanoView Biosciences., Sasa Cucnik: None declared, Snežna Sodin-Šemrl: None declared, Polona Zigon: None declared

THU0013 INTEGRATED ANALYSIS OF SYNOVIAL SINGLE CELL RNA SEQUENCING DATA DEEPENS THE CURRENT KNOWLEDGE OF SYNOVIAL PATHOLOGY IN ARTHRITIS

Background:

The heterogeneity of synovial tissues from patients with arthritis could contribute to the interpatient variability in disease course, prognosis and treatment response. Single-cell RNA sequencing (scRNA-seq) permits in-depth analysis of tissue heterogeneity, which could facilitate drug discovery and patient stratification for precision medicine.

Objectives:

To construct a comprehensive landscape of synovial cell types and molecular pathways in arthritis by integrating our and published scRNA-seq data, generated across different scRNA-seq technologies [Smart-seq2, Drop-seq], cell preparation protocols [dissociated unsorted, sorted cells] and types of arthritis [undifferentiated (UA), rheumatoid arthritis, osteoarthritis].

Methods:

Synovial tissues were obtained by ultrasound-guided biopsy from patients with UA [not fulfilling the classification criteria for a specific arthritis, n=3]. Biopsies were disintegrated [enzymatic and mechanical disruption] and cell viability assessed with trypan blue. ScRNA-seq libraries [2 per patient] were prepared with 10X Genomics Drop-Seq and sequenced on NovaSeq6000. Bioinformatics analysis of our and published [n=35] datasets1-3was performed using Seurat protocol4with correction for batch effects and filtering low-quality cells. Functional enrichment analysis of marker genes in clusters was done with STRING Protein-Protein networks. Synovitis was assessed with ultrasound and histology.

Results:

Our tissue disintegration protocol resulted in good cell yield and viability (92%, 72%, 100%). The synovial cellular heterogeneity detected by scRNA-seq reflected the histological findings [Krenn score, pathotype]. These were supported with the ultrasound and clinically assessed disease activity. The integrated analysis of 41 datasets from 38 donors yielded 41845 scRNA-seq cell profiles, 50% contributed by our dataset. An independent analysis of our data and their integration with published data showed that different scRNA-seq methods and protocols can identify all the major synovial cell types and their activation states (Figure 1) with large heterogeneity between donors. We identified a previously undescribed synovial cell population, which was located near the fibroblast cluster, was negative for canonical cell markers, but highly enriched in cell division genes (80% of marker genes). These cells comprised a mixed population of CD34-, podoplanin (PDPN)highor PDPNlowcells that were mostly negative for the sub-lining fibroblast marker THY. Furthermore, they appeared to be highly secretory (extracellular matrix components) and their gene expression profile was inclined towards cell migration, vascular development and insulin growth factor-dependent processes.

Figure 1.

Heatmap with top 20 cluster gene markers, gene enrichment analysis and UMAP plot of synovial cell clusters.

Conclusion:

By integrating synovial scRNA-seq data from 41845 cells, we identified a previously undescribed, highly proliferative and secretory synovial cell population in arthritis. We increased the number of known scRNA-seq synovial cell profiles in arthritis by two-fold and demonstrated the robustness of synovial scRNA-seq data outputs across different technologies and protocols. This broadens the current knowledge of synovial tissue heterogeneity and pathology in arthritis.

References:

[1]Stephenson W. et al. Nat Commun 2017.

[2]Mizoguchi F. et al. Nat Commun 2017.

[3]Zhang F. et al. Nat Immunol 2018.

[4]Stuart T et al. Cell 2019

Acknowledgments:

This work is supported by Vontobel Foundation and medAlumni University of Zurich

Disclosure of Interests:

Sam G. Edalat: None declared, Raphael Micheroli: None declared, Tadeja Kuret: None declared, Kristina Buerki: None declared, Chantal Pauli: None declared, Snežna Sodin-Šemrl: None declared, Adrian Ciurea Consultant of: Consulting and/or speaking fees from AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Merck Sharp & Dohme, Novartis and Pfizer., Oliver Distler Grant/research support from: Grants/Research support from Actelion, Bayer, Boehringer Ingelheim, Competitive Drug Development International Ltd. and Mitsubishi Tanabe; he also holds the issued Patent on mir-29 for the treatment of systemic sclerosis (US8247389, EP2331143)., Consultant of: Consultancy fees from Actelion, Acceleron Pharma, AnaMar, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, Catenion, ChemomAb, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi and UCB, Speakers bureau: Speaker fees from Actelion, Bayer, Boehringer Ingelheim, Medscape, Pfizer and Roche, Caroline Ospelt Consultant of: Consultancy fees from Gilead Sciences., Gregor Rot: None declared, Mojca Frank-Bertoncelj: None declared

SAT0292 INTEGRATIVE TRANSCRIPTOMIC AND FUNCTIONAL ANALYSIS REVEALS A ROLE OF DIMETHYL-Α-KETOGLUTARATE IN TGFΒ-DRIVEN CYTOSKELETON REGULATION AND MYOFIBROBLAST DIFFERENTIATION

Background:

Myofibroblasts are the orchestrators of aberrant extracellular matrix (ECM) remodelling in fibrosis. Actin cytoskeleton is a central hub that integrates mechanical signals to promote myofibroblast differentiation and ECM remodelling. Targeting these pathways could represent a novel antifibrotic strategy. We have recently shown that metabolic intermediate dimethyl-α-ketoglutarate (dm-αKG) blocks TGFβ-driven myofibroblast differentiation in dermal fibroblasts (DF).

Objectives:

To investigate the mechanisms by which dm-αKG regulates TGFβ-driven myofibroblast differentiation and inflammatory responses in DF.

Methods:

DF from healthy controls and patients with systemic sclerosis (SSc) were treated with TGFβ (10 ng/ml) and/or dm-αKG (6 mM) for 24h, 48h and 72h. RNA sequencing (Ilumina 2000, n=3 per experimental group) was followed by the analysis of differentially expressed genes (DeSEQ2, log2 fold ≥ |0.5|, padj< 0.01), pathway enrichment analysis (GO terms) and supervised PCA analysis (ClustVis). Protein amounts (fibronectin, αSMA, IL-6), cell contraction and apoptosis were measured with Western blot (n=6), ELISA (n=4), collagen gel contraction assay (n=4) and real time Annexin V assay (n=6). Significance (p<0.05) was determined by one-sample t-test or ANOVA with Tukey’s correction for multiple comparisons.

Results:

TGFβ (24h) altered the expression of 4076 genes in DF as determined by RNA-seq, among which 1864 genes were upregulated. The upregulated genes were enriched in GO biological processes/molecular functions/cellular compartments related to ECM organization (p=1e-07), Wnt signalling (p=5e-06), actin binding (p=3e-07), focal adhesion (p=1e-10), stress fibers (p=3e-07) and actin cytoskeleton (p= 3e-06). Dm-αKG altered the expression of 589 genes in TGFβ-treated DF compared to TGFβ only. The most downregulated pathways in DF treated with dm-αKG + TGFβ compared to TGFβ only included actin binding (p=5e-05), muscle contraction (p=0.001), ECM organization (p=0.008), focal adhesion (p=0.01), Z disk (p=0.01) and stress fibers (p=0.03). Specifically, dm-aKG significantly (p<0.01, log2>-0.5) decreased the expression of many TGFβ-induced genes involved in actin organization and focal adhesion (NEXN, FRMD5, ANTXR1, ACTC1, LIMCH1, SORBS2, TGM2, CSRP2, CAP2, LMO7, FZD2), muscle contraction (SNTB1, LMOD1, ANKRD1, SULF1, JPH2, CAVIN4, OXTR, DYSF, FBXO32) and ECM organization (COL10A1, COL11A1, HAPLN1, MMP14, MMP3, SPINT2, GREM1, MATN3, ADAMTS4). The PCA analysis revealed that the experimental treatment (PC1, Fig 1A) accounted for 61% variability in the expression of these genes, while 19% was attributed to interdonor variability (PC2). Dm-αKG diminished TGFβ-induced production of αSMA protein (72h, p=0.02, mean O.D. ± SD in TGFβ + dm-αKG vs. TGFβ: 0.34 ± 0.38 vs. 3.1 ± 2.3) and repressed TGFβ-driven secretion of fibronectin protein (72h, p=0.047, 0.5 ± 0.1 vs. 1.2 ± 0.6). Dm-αKG reduced the contractile capacity of TGFβ-stimulated DF in collagen gel contraction assay (p=0.003, 0 vs. 67.1 ± 5.4%). Additionally, dm-αKG decreased TGFβ-driven production of IL-6 transcripts (24h, p=0.05, 2.9 ± 0.6 vs 1.9 ± 0.3) and protein (24h, p=0.0005, 5.9 ± 1.2 vs 3 ± 0.7, Fig 1B), but did not increase the apoptosis of DF (24h, 48h, 72h).

Fig 1.

A Supervised PCA analysis of RNA-seq data. B. IL-6 secretion (ELISA).

Conclusion:

Dm-αKG counteracted TGFβ-induced myofibroblast differentiation by regulating the cytoskeleton organization and ECM dynamics in DF and blocked the TGFβ-induced IL-6 production. This closely links metabolism to inflammatory and pro-fibrotic responses in DF. Therefore, regulating intracellular αKG might offer a novel strategy in combating the inflammatory and fibrotic stages of skin fibrosis in SSc.

Acknowledgments:

This work was supported by a research grant from FOREUM Foundation for Research in Rheumatology.

Disclosure of Interests:

Blaž Burja: None declared, Gabriela Kania: None declared, Matija Tomsic: None declared, Snežna Sodin-Šemrl: None declared, Oliver Distler Grant/research support from: Grants/Research support from Actelion, Bayer, Boehringer Ingelheim, Competitive Drug Development International Ltd. and Mitsubishi Tanabe; he also holds the issued Patent on mir-29 for the treatment of systemic sclerosis (US8247389, EP2331143)., Consultant of: Consultancy fees from Actelion, Acceleron Pharma, AnaMar, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, Catenion, ChemomAb, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi and UCB, Speakers bureau: Speaker fees from Actelion, Bayer, Boehringer Ingelheim, Medscape, Pfizer and Roche, Katja Lakota: None declared, Mojca Frank-Bertoncelj: None declared

Characterization of Plasma-Derived Small Extracellular Vesicles Indicates Ongoing Endothelial and Platelet Activation in Patients with Thrombotic Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disease, characterized by thrombosis, obstetric complications and the presence of antiphospholipid antibodies (aPL), which drive endothelial injury and thrombophilia. Extracellular vesicles (EVs) have been implicated in endothelial and thrombotic pathologies. Here, we characterized the quantity, cellular origin and the surface expression of biologically active molecules in small EVs (sEVs) isolated from the plasma of thrombotic APS patients (n = 14), aPL-negative patients with idiopathic thrombosis (aPL-neg IT, n = 5) and healthy blood donors (HBD, n = 7). Nanoparticle tracking analysis showed similar sEV sizes (110–170 nm) between the groups, with an increased quantity of sEVs in patients with APS and aPL-neg IT compared to HBD. MACSPlex analysis of 37 different sEV surface markers showed endothelial (CD31), platelet (CD41b and CD42a), leukocyte (CD45), CD8 lymphocyte and APC (HLA-ABC) cell-derived sEVs. Except for CD8, these molecules were comparably expressed in all study groups. sEVs from APS patients were specifically enriched in surface expression of CD62P, suggesting endothelial and platelet activation in APS. Additionally, APS patients exhibited increased CD133/1 expression compared to aPL-neg IT, suggesting endothelial damage in APS patients. These findings demonstrate enhanced shedding, and distinct biological properties of sEVs in thrombotic APS.

Titanium Dioxide Nanotube Arrays for Cardiovascular Stent Applications

Efficient stent implantation among others depends on avoiding the aggregation of platelets in the blood vessels and appropriate proliferation of endothelial cells and controlled proliferation of smooth muscle cells, which reduces the development of pathology, such as neointimal hyperplasia, thrombosis, and restenosis. The current article provides an elegant solution for prevention of platelet and smooth muscle cell adhesion and activation on stent surfaces while obtaining surface conditions to support the growth of human coronary artery endothelial cells. This was achieved by surface nanostructuring and chemical activation of the surface. Specific nanotopographies of titanium were obtained by electrochemical anodization, while appropriate chemical properties were attained by treatment of titanium oxide nanotubes by highly reactive oxygen plasma. Surface properties were studied by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Wettability was evaluated by measuring the water contact angle. The influence of nanostructured morphology and plasma modification on in vitro biological response with human coronary artery endothelia and smooth muscle cells as well as whole blood was studied. Our results show that a combination of nanostructuring and plasma modification of the surfaces is an effective way to achieve desired biological responses necessary for implantable materials such as stents.

Interleukin-1β Induces Intracellular Serum Amyloid A1 Expression in Human Coronary Artery Endothelial Cells and Promotes its Intercellular Exchange

Serum amyloid A (SAA) is an acute-phase protein with important, pathogenic role in the development of atherosclerosis. Since dysfunctional endothelium represents a key early step in atherogenesis, we aimed to determine whether induced human coronary artery endothelial cells (HCAEC) modulate SAA1/2/4 expression and influence intracellular location and intercellular transport of SAA1. HCAEC were stimulated with 1 ng/ml IL-1β, 10 ng/ml IL-6, and/or 1 μM dexamethasone for 24 h. QPCR, Western blots, ELISA, and immunofluorescent labeling were performed for detection of SAA1/2/4 mRNA and protein levels, respectively. In SAA1 transport experiments, FITC- or Cy3-labeled SAA1 were added to HCAEC separately, for 24 h, followed by a combined incubation of SAA1-FITC and SAA1-Cy3 positive cells, with IL-1β and analysis by flow cytometry. IL-1β upregulated SAA1 (119.9-fold, p < 0.01) and SAA2 (9.3-fold; p < 0.05) mRNA expression levels, while mRNA expression of SAA4 was not affected. Intracellular SAA1 was found mainly as a monomer, while SAA2 and SAA4 formed octamers as analyzed by Western blots. Within HCAEC, SAA1/2/4 located mostly to the perinuclear area and tunneling membrane nanotubes. Co-culturing of SAA1-FITC and SAA1-Cy3 positive cells for 48 h showed a significantly higher percentage of double positive cells in IL-1β-stimulated (mean ± SD; 60 ± 4%) vs. non-stimulated cells (48 ± 2%; p < 0.05). IL-1β induces SAA1 expression in HCAEC and promotes its intercellular exchange, suggesting that direct communication between cells in inflammatory conditions could ultimately lead to faster development of atherosclerosis in coronary arteries.

The immunogenicity of seasonal and pandemic influenza vaccination in autoimmune inflammatory rheumatic patients-a 6-month follow-up prospective study

INTRODUCTION

Influenza may cause severe complications in patients with autoimmune inflammatory rheumatic disease (AIRD), to whom vaccinations are especially recommended. However, AIRD patients require cautious scrutiny of immunogenicity as they might exhibit poor antibody response to vaccination, especially when taking immunomodulatory medications.

AIM

The aim was to determine immunogenicity of seasonal and pandemic influenza vaccine in AIRD patients, its timeline/persistence, and influence of medications on immune response.

METHODS

One hundred and thirty-seven AIRD and 54 healthy controls were vaccinated with trivalent seasonal influenza. After 3-5 weeks, 15 healthy controls and 93 AIRD were vaccinated with pandemic influenza vaccine, and 63 of patients were vaccinated a second time after 3-5 weeks. Sera were collected before vaccination, 18-90 days after each vaccination, and more than 180 days after the last vaccination. The immune response was measured using hemagglutination inhibition (HI) assay and IgG/IgA antibodies against influenza A/B with ELISA.

RESULTS

Our findings indicate that following vaccination with seasonal influenza vaccine, seroprotection, seroresponse, and change in geometric mean titers (GMT) in AIRD patients was not compromised compared to healthy. Similarly, we report for pandemic influenza vaccination little added benefit of the second dose. We confirm lowest increase in HI titer in rituximab-treated AIRD compared to other medications. Vaccination largely tilts the balance from negative ELISA A IgG and IgA titers to positive titers in seasonal H1N1 seroresponsive AIRD patients and controls. A significant decrease in HI GMT and seroprotection was observed only in AIRD at > 180 days after vaccination highlighting an absent persistence of immunogenic response in AIRD patients. Due to high initial HI titers for influenza vaccine, we foresee their benefit in personalized medicine in the future.

CONCLUSION

Influenza vaccination is immunologically active for AIRD, with little value of the second dose of the pandemic vaccine and further scrutiny on persistence of immune response to vaccine in AIRD is needed.

MicroRNA expression in the affected skin of adult patients with IgA vasculitis

IgA vasculitis (IgAV) represents a common systemic vasculitis in pediatric and adult population. Our current knowledge of disease pathogenesis is still very limited, without information on miRNAs in IgAV. The aim of our study was to determine the expression of five pre-selected miRNAs (miRNA-146a-5p, miRNA-148-3p, miRNA-155-5p, miRNA-223-3p, and let-7b) in the affected skin of adult IgAV patients. The study included 65 skin samples from consecutive, untreated IgAV patients (61.5% male, median age 67.6 years, range 29-91), diagnosed between October 2014 and September 2016, and 20 samples of normal skin from healthy volunteers. Total RNA was isolated from tissue sections of formalin-fixed, paraffin-embedded samples. Expression of miRNAs was measured using qRT-PCR. To present relative miRNA expression, the ΔΔCT method was used. Skin miRNA expression was correlated to clinical characteristics of adult IgAV patients. We found significantly higher levels of miRNA-155-5p, miRNA-223-3p, and let-7b in the affected skin compared to controls (18.6-fold, 6.4-fold, and 7.9-fold higher respectively). Contrary, the miRNA 148-3p expression was significantly lower (2.2-fold). The expression of the miRNA-146-5p showed near normal levels. Patients with necrotic skin lesions had significantly higher miRNA-223 tissue expression than those with non-necrotic purpura (p = 0.029). Gastrointestinal tract involvement inversely correlated with the expression of miRNA-155-5p and/or miRNA-146a-5p in affected skin. Altered expression of miRNA-148b-3p, miRNA-155-5p, miRNA-223-3p, and let-7b was found in vasculitic skin lesions in IgAV. Additionally, we found a positive association between the severity of purpura and skin miRNA-223-3p expression. Aberrantly expressed miRNAs could represent a biomarker in adult IgAV.

Correlation Between Mitochondrial DNA Content Measured in Myocardium and Peripheral Blood of Patients with Non-Ischemic Heart Failure

BACKGROUND/OBJECTIVES

Heart failure (HF) is associated with disturbances in mitochondrial energy production. This mitochondrial dysfunction is reflected by depletion of mitochondrial DNA (mtDNA) in different tissues. Our aims were to determine if there was a correlation between mtDNA content measured in myocardial tissue and the easily accessible peripheral blood cells of patients with non-ischemic HF; and to determine if there was a correlation between myocardial mtDNA and left ventricular (LV) ejection fraction.

METHODS

We prospectively collected paired myocardial tissue and peripheral blood samples from 13 consecutive end-stage non-ischemic HF patients undergoing cardiac transplantation. mtDNA content was assessed with real-time quantitative PCR by calculating the relative ratio of two specific mitochondrial sequences and one nuclear control gene sequence.

RESULTS

HF patients with lower myocardial mtDNA content had a significantly lower LV ejection fraction (r = 0.65, p = 0.016). Peripheral blood mtDNA content correlated positively with right ventricular myocardial mtDNA content (r = 0.63, p = 0.021). We also observed that averaged myocardial DNA content tended to correlate with peripheral blood mtDNA content (r = 0.53, p = 0.061).

CONCLUSIONS

In non-ischemic HF patients, myocardial mtDNA content is positively correlated with peripheral blood mtDNA content and LV function as assessed by echocardiography.

Methotrexate reduces HbA1c concentration but does not produce chronic accumulation of ZMP in patients with rheumatoid or psoriatic arthritis

OBJECTIVES

The mechanism by which methotrexate (MTX) improves glucose homeostasis in patients with rheumatoid (RA) and psoriatic arthritis (PsA) remains undetermined. Animal studies indicate a role for intracellular accumulation of 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5'-monophosphate (ZMP) but this has not been directly demonstrated in humans. We explored whether accumulation of ZMP is associated with improvements in glucose homeostasis during MTX therapy.

METHOD

MTX-naïve, non-diabetic RA (n = 16) and PsA (n = 10) patients received uninterrupted MTX treatment for 6 months. To evaluate whether ZMP accumulated during MTX therapy, we measured the concentration of ZMP in erythrocytes and the concentration of its dephosphorylated derivative 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) in urine using liquid chromatography mass spectrometry (LC-MS/MS). To assess glucose homeostasis, we determined the concentration of glycated haemoglobin (HbA1c) and homeostasis model assessment of insulin resistance [HOMA-IR: fasting glucose (mmol/L) × fasting insulin (μU/mL)/22.5].

RESULTS

Erythrocyte ZMP and urinary AICAR concentrations did not increase during 6 months of MTX therapy. HbA1c concentration was reduced from 5.80 ± 0.29% at baseline to 5.51 ± 0.32% at 6 months (p < 0.001), while HOMA-IR remained unaltered. Reduction in HbA1c concentration was not associated with increased ZMP or AICAR concentrations.

CONCLUSIONS

MTX therapy probably does not produce a chronic increase in erythrocyte ZMP or urinary AICAR concentrations. Collectively, our data do not support the hypothesis that MTX improves glucose homeostasis through chronic accumulation of ZMP.