Long non-coding RNA H19X as a regulator of mononuclear cell adhesion to the endothelium in systemic sclerosis

OBJECTIVE

To define the functional relevance of H19 X-linked co-expressed lncRNA (H19X) in endothelial cell (EC) activation as a key process in systemic sclerosis (SSc) vasculopathy.

METHODS

H19X expression in SSc skin biopsies was analyzed from single cell RNA sequencing (scRNA-seq) data. Differential expression and pathway enrichment analysis between cells expressing (H19Xpos) and non expressing H19X (H19Xneg) cells was performed. H19X function was investigated in human dermal microvascular EC (HDMECs) by silencing. H19X and EC adhesion molecules levels were analyzed by RT-qPCR and Western Blot after stimulation with proinflammatory cytokines. Cytoskeletal rearrangements were analyzed by fluorescent staining. Endothelial adhesion was evaluated by co-culture of HDMECs and fluorescent labelled peripheral blood mononuclear cells (PBMCs). Shedding VCAM1 was evaluated by ELISA on HDMEC supernatant.

RESULTS

scRNA-seq showed significant upregulation of H19X in SSc compared with healthy EC. In HDMEC, H19X was consistently induced by type I and II interferons. H19X knockdown lead to a significant decrease of the mRNA of several adhesion molecules. Particularly, vascular cell adhesion protein 1 (VCAM1) was significantly reduced at protein and mRNA levels. Co-expression analysis of the scRNA-seq data confirmed a higher expression of VCAM1 in (H19Xpos) EC. EC were also strongly associated with the 'cell adhesion molecule' pathway. Moreover, VCAM1 downstream pathway displayed less activation following H19X knockdown. Contractility of HDMEC, PBMC adhesion to HDMEC and VCAM1 shedding were also reduced following H19X knockdown.

CONCLUSIONS

lncRNA H19X may contribute to EC activation in SSc vasculopathy, acting as a regulator of expression of adhesion molecules in EC.

Vaccination-based immunotherapy to target profibrotic cells in liver and lung

Fibrosis is the final path of nearly every form of chronic disease, regardless of the pathogenesis. Upon chronic injury, activated, fibrogenic fibroblasts deposit excess extracellular matrix, and severe tissue fibrosis can occur in virtually any organ. However, antifibrotic therapies that target fibrogenic cells, while sparing homeostatic fibroblasts in healthy tissues, are limited. We tested whether specific immunization against endogenous proteins, strongly expressed in fibrogenic cells but highly restricted in quiescent fibroblasts, can elicit an antigen-specific cytotoxic T cell response to ameliorate organ fibrosis. In silico epitope prediction revealed that activation of the genes Adam12 and Gli1 in profibrotic cells and the resulting "self-peptides" can be exploited for T cell vaccines to ablate fibrogenic cells. We demonstrate the efficacy of a vaccination approach to mount CD8⁺ T cell responses that reduce fibroblasts and fibrosis in the liver and lungs in mice. These results provide proof of principle for vaccination-based immunotherapies to treat fibrosis.

POS0482 LONG NON-CODING RNA H19X IS A MEDIATOR OF ENDOTHELIAL CELL ACTIVATION IN SYSTEMIC SCLEROSIS

Background

In one of our previous studies, we demonstrated that long non-coding RNA (lncRNA) H19X plays a crucial role in the development of TGFβ driven fibrosis in systemic sclerosis (SSc) and other fibrotic diseases1.

Objectives

To define the functional relevance of H19X in endothelial cell (EC) activation as a decisive process in SSc vasculopathy.

Methods

Correlation of H19X expression and microvascular gene signature was computed on bulk RNA-Seq data derived from SSc skin biopsies of patients enrolled in the multicentre Prospective Registry of Early Systemic Sclerosis cohort (PRESS, n=48 SSc vs. n=33 healthy controls, HCs). Single cell RNA sequencing (scRNA-seq) data were collected from 27 diffuse cutaneous SSc (dcSSc) and 10 HC skin biopsies. Single cells were barcoded and encapsulated in droplets using a 10X Genomics system. After cDNA synthesis, the libraries were prepared and sequenced using Illumina NovaSeq-500 platform. Seurat package in R (v.3.0) was used to perform data analysis. EC were identified by enrichment of EC markers CLDN5, VWF and PECAM1. One thousand five hundred eighty-three and 3398 EC were identified from HC and SSc patients, respectively. Cells were analysed for the expression of H19X and EC activation markers. Additionally, differential expression and pathway enrichment analysis between H19X expressing cells and H19X negative cells was carried out. The function of H19X was investigated in human dermal microvascular EC (HDMEC) by silencing, using locked nucleic acid antisense oligonucleotides (LNA GapmeRs). Gene expression was measured by qPCR. Protein levels of endothelial adhesion molecules were analysed by Western Blot. Endothelial adhesion was evaluated by co-culture of HDMEC and fluorescently labelled peripheral blood mononuclear cells (PBMCs).

Results

H19X expression was found significantly upregulated in SSc skin biopsies of the PRESS cohort (p<0.0001). The expression of H19X positively correlated with the microvascular endothelial cell gene signature in all subjects (SSc and HC, R=0.43, p<0.0001), confirming that H19X is expressed in this cell type. To determine if H19X might be an important factor in SSc EC dysfunction scRNAseq was performed. This analysis revealed a significant upregulation of H19X in SSc EC as compared to HC EC (p=0.0095). H19X was found to be upregulated in several EC subclusters including arterial (SEMA3G, HEY1), capillary (CA4, RGCC), venous (ACKR1, VCAM1) and lymphatic (PROX1, LYVE1). H19X displayed highest expression in injured SSc EC and capillary SSc EC. Co-expression analysis of the scRNA-seq data revealed higher expression of several adhesion molecules in EC expressing H19X, including VCAM1, ICAM and JAM3. KEGG pathway analysis revealed that differentially expressed genes in H19X expressing cells were highly associated with the ‘Cell adhesion molecule’ pathway (p=2.209e-7). H19X silencing lead to a significant downregulation of mRNA levels of genes encoding adhesion molecules VCAM1 (n=7, p<0.05) and E-selectin (n=7, p<0.01) at 48h after transfection. VCAM1, but not E-Selectin, was also reduced at protein level as revealed by Western Blot (n=3). The functional relevance of H19X on endothelial adhesion was confirmed by PBMCs with H19X silenced HDMEC where we were able to demonstrate a significant decrease in leucocyte-to-endothelial cell adhesion (n=5, p<0.05).

Conclusion

Our results show that lncRNA H19X could contribute to EC activation in SSc vasculopathy, acting as a regulator of expression of adhesion molecules in EC.

References

[1]Pachera E, et al. Long noncoding RNA H19X is a key mediator of TGF-β-driven fibrosis. J Clin Invest. 2020 Sep 1;130(9):4888-4905.

Disclosure of Interests

Francesca Tirelli: None declared, Elena Pachera: None declared, Robert Lafyatis Consultant of: Pfizer, Bristol Myers Squibb, Boehringer-Ingleheim, Formation, Sanofi, Boehringer-Mannheim, Merck and Genentech/Roche, Grant/research support from: Corbus, Formation, Moderna, Regeneron, Pfizer and Kiniksa, Menqi Huang: None declared, Shervin Assassi: None declared, Eva Camarillo: None declared, Francesco Zulian: None declared, Gabriela Kania: 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.

POS0479 STAT3 DEGRADERS PROTECT FROM IMMUNOFIBROTIC CHANGES IN PRECLINICAL MODELS

Background

The ubiquitin-proteasome system (UPS) is the endogenous intracellular mechanism for maintaining protein homeostasis through protein degradation and turnover. Heterobifunctional small molecules are a new class of compounds that form a ternary complex with an E3 ligase and protein of interest leading to ubiquitination and subsequent degradation of the protein of interest in a process known as Targeted Protein Degradation. This new therapeutic modality enables targeting of “undruggable” proteins such as STAT3, a transcription factor activated in immunofibrotic diseases.

Objectives

Kymera has developed heterobifunctional molecules that potently and selectively target STAT3 for degradation and elimination by the ubiquitin-proteasome pathway. The aim of these studies was to evaluate the therapeutic potential of pharmacologically removing STAT3 by targeted protein degradation in various human cell types in vitro, and to prevent the development of skin and lung fibrosis in vivo.

Methods

Dermal fibroblasts obtained from healthy and systemic sclerosis patients activated with TGF-β were analyzed for development of α-smooth muscle actin (α-SMA)-positive stress fibers and for contractility using collagen gel contraction assay. Contraction assay was also performed using human dermal smooth muscle cells. Human aortic endothelial cells (HAECs) were activated with LPS, and their adhesive properties were assessed in the microcapillary system by the ability to bind peripheral blood mononuclear cells (PBMCs) under shear stress. HAECs proliferation was induced with VEGF. THP-1 cells and CD14+ monocytes were activated with IL-6 or LPS, and secreted cytokines were assessed by CBA. PBMCs activated with LPS, IL-6, IL-21, or IL-23 alone (pSTAT3 induction), or with a combination of anti-CD3/CD38 beads and a pro-Th17 cocktail comprised of cytokines and antibodies to evaluate the development of a Th17 and Treg phenotype by flow cytometry. Cytokines were analyzed by ELISA. All cell types were pre-treated with STAT3 degraders 20h prior to experiment start. Intratracheal instillation of bleomycin was used to induce pulmonary fibrosis. Transgenic Tsk-1 mice were used as a model of spontaneous skin fibrosis.

Results

STAT3 degraders completely ablated STAT3 in all analyzed cell types with DC50 ranging from 0.25-0.8 nM. STAT3 degradation prevented TGF-β-induced formation of α-SMA-positive stress fibers in dermal fibroblasts (IC50 = 0.35nM) and 2 and 10nM degrader completely abrogated their contractility. Similarly, STAT3 degradation reduced the constitutive contractility of dermal smooth muscle cells of 13% (p<0.05, n=6). Treatment of HAECs with STAT3 degraders resulted in anti-adhesive 178±21 for LPS and 93±12 for LPS +degrader, p<0.05, n=6) and anti-proliferative 1.2±0.1 for VEGF and 0.95±0.1 for VEGF +degrader, p<0.05, n=10-11) effects. In monocyte-focused assays (CD14+ monocytes and THP-1 cells), STAT3 degradation potently and dose-dependently inhibited IL-6 and LPS-induced pSTAT3 levels and the ensuing release of MCP-1/CCL2 (24.3±3.7 for LPS and 20.2±3.2 for LPS +degrader, p<0.05, n=6). In CD4+ T lymphocytes, STAT3 degradation promoted a Treg phenotype and suppressed the development of Th17 cells. Systemic treatment in vivo showed that prophylactic STAT3 degradation (7 mg/kg twice a week, i.p.) reduced disease severity in the bleomycin-induced pulmonary fibrosis model (Ashcroft‘s score, 4.7±1.9 vs. 3.1±1.6, p<0.05, n=11). In Tsk-1 mice that show co-occurrence of spontaneous skin thickening and robust STAT3 activation, STAT3 degrader treatment (2 or 7 mg/kg twice a week, i.p.) for 7 weeks significantly reduced thickness of the skin (701±238 vs. 480±205 vs. 365±107, p<0.05, n=6-8).

Conclusion

STAT3 degraders that selectively and potently eliminate STAT3 show robust anti-inflammatory and anti-fibrotic potential in vitro and in vivo. Our results suggest that targeted protein degradation is a promising approach to modulate the STAT3 pathway, making it a novel therapeutic opportunity to treating multiple immunofibrotic diseases.

Disclosure of Interests

Przemyslaw Blyszczuk Grant/research support from: Kymera, Gabriela Kania: None declared, Elena Pachera: None declared, Filip Rolski: None declared, Amela Hukara: None declared, Vanessa Tela: None declared, Michele Mayo Employee of: Kymera, Vaishali Dixit Employee of: Kymera, Bin Yang Employee of: Kymera, Jared Gollob Employee of: Kymera, Nello Mainolfi Employee of: Kymera, Anthony Slavin Employee of: Kymera, Cedric Hubeau Employee of: Kymera, 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.

POS0486 IDENTIFICATION OF NEW CANDIDATE TARGETS INVOLVED IN ACTIVATION OF CARDIAC FIBROBLASTS UNDER IMMUNOFIBROTIC CONDITIONS

Background

Inflammatory dilated cardiomyopathy (iDCM) often leads to heart failure (HF), which is the main cause of mortality in patients with systemic diseases. Fibroblast activation, driven by the activator protein 1 family member Fos-related antigen 2 (FOSL2), represents a critical step in cardiac fibrogenesis. The existing antifibrotic therapies, based on known fibrotic markers, failed to demonstrate efficacy against myocardial fibrosis.

Objectives

To identify new candidate targets implicated in cardiac fibrogenesis under immunofibrotic conditions.

Methods

Cardiac fibroblasts were isolated from the left atria of patients (n=5) undergoing heart transplantation due to HF associated with iDCM and from unaffected hearts of brain-dead donors (UDs, n=5). Protein identification and quantification was performed using liquid chromatography tandem-mass spectrometry (LC–MS/MS). The data were analysed with MaxQuant v1.6.2.3 software. Bulk RNA sequencing (RNA-seq) was conducted using the Illumina HiSeq platform. Differentially expressed genes were identified using DESeq2. Additionally, we analysed publicly available single-cell (sc) RNA sequencing datasets (GSE109816, GSE121893) [1] on adult hearts from HF patients (n=6) and UDs (n=14) using Seurat package (V.2.3.4). Specific gene knockdown was achieved by siRNA transfection of human foetal cardiac fibroblasts (HCFs, Sigma), untreated or stimulated with TGF-β for 48-72h. The profibrotic marker expression was assessed using RT-qPCR and Western Blot. Cell viability was measured using PrestoBlue HS reagent (Invitrogen), and ATP production was quantified with CellTiter-Glo assay (Promega) in untreated and TGF-β-stimulated HCFs 48h after transfection.

Results

The LC–MS/MS analysis revealed 14 differentially expressed proteins (absolute log2FC>1, adj. p<0.05) in the HF group compared to UDs. The most upregulated protein in HF fibroblasts was dysferlin (DYSF, log2FC=5.78, adj. p<0.004), which is known to play a role in the sarcolemma repair of both skeletal muscle fibres and cardiomyocytes. Bulk RNA-seq analysis identified a total of 67 significantly differentially expressed genes (absolute log2FC>1, adj. p<0.05). The comparative analysis of bulk RNA-seq results and publicly available scRNA-seq datasets revealed two commonly upregulated genes in HF fibroblasts or their subclusters, encoding transcription factor FOXF1 (log2FC=3.51, adj.p<0.05) and matrix remodelling-associated protein MXRA5 (log2FC=2.91, adj. p<0.05).

Further in vitro studies on HCFs (n=4) showed that TGF-β upregulated DYSF (p<0.001) and MXRA5 (p<0.01) but downregulated FOXF1 (p<0.05). DYSF silencing in HCFs (n=4) upregulated MXRA5 after 48h of TGF-β stimulation (p<0.05), downregulated ACTA2 (48h and 72h of TGF-β stimulation, p<0.05), and upregulated FOSL2 protein levels in untreated HCFs and 72h after TGF-β stimulation (n=3, p<0.05). MXRA5 knockdown (n=8) resulted in the upregulation of DYSF (p<0.05), ACTA2 (p<0.05) and COL1A1 (p<0.001) in untreated HCFs, and also upregulated DYSF (p<0.01) and COL1A1 (p<0.05) after 48h of TGF-β stimulation. FOXF1 silencing in HCFs (n=8) followed by 48h of TGF-β stimulation downregulated MXRA5 (p<0.01) and ACTA2 (p=0.06), and upregulated DYSF (p<0.001) and COL1A1 (p=0.05). Candidate targets knockdown reduced cell viability in untreated (n=4, DYSF: p<0.01, MXRA5: p<0.001, FOXF1: p<0.01) and TGF-β stimulated (n=4, DYSF: p<0.05, MXRA5: p<0.05, FOXF1: p<0.01) HCFs. ATP levels were decreased in TGF-β-stimulated HCFs after DYSF silencing (n=6, p=0.05).

Conclusion

Based on transcriptomics, proteomics and in vitro analysis of human cardiac fibroblasts, we identified DYSF, MXRA5 and FOXF1 as candidate targets implicated in profibrotic phenotype development, including profibrotic transcription factor FOSL2 regulation. These newly proposed candidates may serve as potential therapeutic targets for the treatment of cardiac fibrosis.

References

[1]Wang, L. et al. Nat. Cell Biol. 2020.

Disclosure of Interests

Ievgeniia Kocherova: None declared, Elena Pachera: None declared, Daria Nurzynska: None declared, Franca Di Meglio: 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, Przemyslaw Blyszczuk: None declared, Gabriela Kania: 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.

POS0332 ENDOTHELIAL ACTIVATION IN SYSTEMIC SCLEROSIS VASCULOPATHY: ROLE OF LONG NON-CODING RNA H19X

Background:

Long non-coding RNAs (lncRNA) are a class of non-coding transcripts which modulate many biological processes. Our previous studies showed that lncRNA H19X is pivotal in the regulation of TGFβ driven fibrosis in systemic sclerosis (SSc)1.

Objectives:

We aimed to investigate whether H19X plays a functional role in the regulation of endothelial cell (EC) activation, which is crucial in SSc vasculopathy2.

Methods:

Single-cell RNA sequencing (scRNA-seq) data from 27 dcSSc and 10 healthy control (HC) skin biopsies, following 10X Genomics partitioning and cDNA preparation, were analyzed for H19X expression in skin ECs, using Seurat package in R. A total of 4,981 ECs, of which 1,583 cells originated from HC and 3,398 cells originated from SSc patients, ranging from 59 to 342 ECs per subject, characterized by enrichment of EC markers of CLDN5, VWF and PECAM1.

Expression of H19X in Human Dermal Microvascular ECs (HDMEC) was analyzed by qPCR. HDMEC were stimulated with different proinflammatory cytokines including IFNα, IFNβ, IFNγ, TGFβ, TNFα, IL-6, IL-1β and IL-4 at biologically relevant concentrations. In order to ascertain its effect in ECs, H19X was silenced in HDMECs using locked nucleic acid antisense oligonucleotides (LNA GapmeRs). qPCR and Western Blot (WB) were used to analyze the effects of H19X downregulation on EC activation biomarkers.

Results:

scRNA-seq data showed that H19X was significantly upregulated in SSc compared to healthy ECs (p=0.0095). Based on the differentially expressed gene profiles among subclusters, EC were further annotated as arterial (SEMA3G, HEY1), capillary (CA4, RGCC), venous (ACKR1, VCAM1), lymphatic (PROX1, LYVE1) ECs, as well as two aberrant clusters, proliferating (TOP2A, MKI67) and injured (HSGP2, APLNR) ECs, which were dominated by the SSc ECs. Specifically, the highest expression of H19X was found in injured SSc ECs and capillary SSc ECs. Overall, 1.5% SSc EC, about 51 cells, expressed detectable levels of H19X.

In HDMEC (n=3), H19X was consistently induced by IFNα, IFNβ and IFNγ. Time curve analysis demonstrated that the strongest induction was observed at 48H (1.5±0.2, 1.6±0.4 and 2.1±0.3 – fold increase respectively). The combination of different IFNs determined stronger H19X induction after 48H stimulation, with a 2.4±0.1 increase with the combination of all IFNs and a 2.4±0.1 increase after the combination of IFNα+γ.

Importantly, H19X knockdown lead to consistent and significant decrease of mRNAs of several adhesion molecules, including VCAM1, E- Selectin and P-Selectin, both in untreated HDMEC and after IFN stimulation. A decrease of VCAM and P-Selectin could be also demonstrated with WB analysis. No change was seen in other EC activation markers, including endothelin-1 and angiogenesis markers including VEGF, VEGFRA, Tie2 and thrombospondin.

Conclusion:

This is the first report analyzing a potential role of lncRNA H19X in SSc vasculopathy. Our results suggest that lncRNA H19X could act as a regulator of adhesion molecules expression in EC, possibly mediated by IFNs, and be therefore involved in EC activation.

References:

[1]Pachera E, et al. Long noncoding RNA H19X is a key mediator of TGF-β-driven fibrosis. J Clin Invest. 2020 Sep 1;130(9):4888-4905.

[2]Mostmans Y, et al. The role of endothelial cells in the vasculopathy of systemic sclerosis: A systematic review. Autoimmun Rev. 2017 Aug;16(8):774-786.

Acknowledgements:

I have no acknowledgements to declare

Disclosure of Interests:

Francesca Tirelli: None declared, Elena Pachera: None declared, Robert Lafyatis Consultant of: RL served as a consultant with Bristol Meyers Squibb, Formation, Sanofi, Boehringer-Ingelheim, Merck, and Genentech/Roche, Acceleron, Grant/research support from: RL received grants form Bristol Meyer Squib, Corbus, Formation, Moderna, Regeneron, Pfizer, and Kiniksa, Menqi Huang: None declared, Francesco Zulian: None declared, Gabriela Kania: None declared, Oliver Distler Speakers bureau: Speaker fee on Scleroderma and related complications and on other rheumatology topics: Actelion, Bayer, Boehringer Ingelheim, Medscape, Novartis, Roche, Menarini, Mepha, MSD, iQone, Pfizer, Consultant of: Has consultancy relationship in the area of potential treatments for systemic sclerosis and its complications (last three years):Abbvie, Actelion, Acceleron Pharma, Amgen, AnaMar, Arxx Therapeutics, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, ChemomAb, Corpuspharma, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, -Kymera, Medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi, UCB, Lilly, Target BioScience, Pfizer. Consultancy relationship for rheumatology topic other than Scleroderma: Abbvie, Amgen, Lilly, Target BioScience, Pfizer. In addition, he holds a patent issued “mir-29 for the treatment of systemic sclerosis” (US8247389, EP2331143)., Grant/research support from: Has received grants/research support in the are of potential treatments for systemic sclerosis from Actelion, Bayer, Boehringer Ingelheim, Kymera Therapeutics, Mitsubishi Tanabe Pharma

OP0248 DEVELOPMENT OF A 3D SKIN MICROTISSUE MODEL FOR FIBROTIC DISEASES

Background:

Traditional preclinical approaches, such as two-dimensional cell culture and animal models, are often inadequate to mimic the pathophysiological features of complex diseases such as systemic sclerosis (SSc). Human specific targets, such as the recently described pro-fibrotic long non coding RNA (lncRNA) H19X1, are becoming increasingly relevant in preclinical research, creating the need of new strategies and tools in translational medicine. The employment of novel three-dimensional (3D) culture systems, where multiple cell types are included, is filling an important gap left by the traditional preclinical methods.

Objectives:

To develop an easy to produce 3D fibrotic skin microtissues model for translational proof of concept studies.

Methods:

Two thousand five hundred dermal fibroblasts isolated from skin of SSc patients were seeded in ultra-low attachment 96-well plates. Fibroblast were let to aggregate into spheres for 48h. Two thousand five hundred primary normal human keratinocytes were added to the culture and let to layer onto the fibroblast spheres for 72h. H19X silencing experiments were used as proof of concept studies. H19X silencing with antisense oligonucleotides or transfections with a scrambled control were performed in fibroblasts prior to the sphere formation for 24h. TGFβ (10 ng/ml) was added to microtissue to exacerbate the fibrotic phenotype. Haematoxylin eosin staining as well as immunohistochemistry staining for vimentin and cytokeratin 10 was performed. Skin microtissues were processed for RNA and protein isolation. Pro-collagen Iα1 and fibronectin were quantified in the supernatants with ELISA.

Results:

The microtissues presented a core of SSc fibroblast as revealed by vimentin staining and an external layer of keratinocytes as revealed by cytokeratin 10 staining, mimicking the human skin architecture. Gene expression analysis following TGFβ stimulation displayed induced expression of extracellular matrix gene COL1A1 (p=0.044) and the myofibroblast marker ACTA2 (p=0.018), indicating that the microtissues were able to develop a fibrotic response. Microtissues, where H19X was silenced, displayed reduced gene expression of COL1A1 and ACTA2 after TGFβ stimulation (COL1A1 p=0.007, ACTA2 p=0.045). Additionally, H19X silencing led to lower levels of αSMA protein expression (p=0.009) and pro-collagen1α1 secretion (p=0.039) in the supernatant of the microtissue cultures as revealed by Western Blot and ELISA, respectively. FN1 expression and fibronectin protein levels were not significantly reduced in the microtissues after H19X silencing.

Conclusion:

We were able to produce a 3D microtissue resembling skin architecture that can respond to fibrotic stimuli. Knockdown experiments of pro-fibrotic lncRNA H19X confirmed the potential of the model as screening platform for novel pro-fibrotic effectors. A future aim will be to optimize the model for high-throughput automated screening platforms.

References:

[1]Pachera, E., et al. (2020). “Long noncoding RNA H19X is a key mediator of TGF-β–driven fibrosis.” The Journal of Clinical Investigation 130(9): 4888-4905.

Disclosure of Interests:

Elena Pachera: None declared, Gabriela Kania: None declared, Astrid Juengel: None declared, Maurizio Calcagni Speakers bureau: Arthrex, Consultant of: Medartis, Arthrex, SilkBiomaterials, Grant/research support from: Medartis, Oliver Distler Speakers bureau: Actelion, Bayer, Boehringer Ingelheim, Medscape, Novartis, Roche, Consultant of: Abbvie, Actelion, Acceleron Pharma, Amgen, AnaMar, Arxx Therapeutics, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, ChemomAb, Corpuspharma, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, -Kymera, Medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi, UCB, Grant/research support from: Abbvie, Actelion, Bayer, Boehringer Ingelheim, Kymera Therapeutics, Mitsubishi Tanabe

Long noncoding RNA H19X is a key mediator of TGF-β-driven fibrosis

TGF-β is a master regulator of fibrosis, driving the differentiation of fibroblasts into apoptosis-resistant myofibroblasts and sustaining the production of extracellular matrix (ECM) components. Here, we identified the nuclear long noncoding RNA (lncRNA) H19X as a master regulator of TGF-β-driven tissue fibrosis. H19X was consistently upregulated in a wide variety of human fibrotic tissues and diseases and was strongly induced by TGF-β, particularly in fibroblasts and fibroblast-related cells. Functional experiments following H19X silencing revealed that H19X was an obligatory factor for TGF-β-induced ECM synthesis as well as differentiation and survival of ECM-producing myofibroblasts. We showed that H19X regulates DDIT4L gene expression, specifically interacting with a region upstream of the DDIT4L gene and changing the chromatin accessibility of a DDIT4L enhancer. These events resulted in transcriptional repression of DDIT4L and, in turn, in increased collagen expression and fibrosis. Our results shed light on key effectors of TGF-β-induced ECM remodeling and fibrosis.

Regulation of Fibroblast Apoptosis and Proliferation by MicroRNA-125b in Systemic Sclerosis

OBJECTIVE

To analyze the expression, regulation, and role of microRNA-125b (miR-125b) in systemic sclerosis (SSc).

METHODS

MiR-125b expression was assessed by quantitative polymerase chain reaction (qPCR) of RNA from dermal fibroblasts and whole skin biopsy specimens from healthy controls and SSc patients. To identify downstream effectors, RNA from healthy control fibroblasts was sequenced after miR-125b knockdown and further validated using qPCR and Western blotting. Fibrosis, apoptosis, and proliferation were assessed by Caspase-Glo 3/7 assay, Western blotting, immunofluorescence staining for cleaved caspase 3, and annexin V real-time assay in dermal fibroblasts.

RESULTS

Expression of miR-125b was significantly down-regulated in SSc skin biopsy specimens by 53% (median fold change 0.47 [interquartile range 0.35-0.69]; P < 0.001) and in SSc dermal fibroblasts by 47% (median fold change 0.53 [interquartile range 0.36-0.58]; P < 0.001) compared to healthy control skin biopsy specimens and fibroblasts, respectively (n = 10 samples per group). Treatment with the histone deacetylase inhibitors trichostatin A and tubastatin A significantly decreased the expression of miR-125b in dermal fibroblasts. MiR-125b knockdown significantly reduced cell proliferation and α-smooth muscle actin (α-SMA) expression at the messenger RNA (mRNA) and protein levels. RNA-Seq identified BAK1, BMF, and BBC3 as potential targets of miR-125b. Quantitative PCR confirmed that knockdown of miR-125b up-regulated these genes (P < 0.01; n = 12). Bcl-2 homologous antagonist killer 1 showed the strongest induction confirmed at the protein level (P < 0.01; n = 10). Consequently, miR-125b knockdown increased apoptosis compared to scrambled control. Accordingly, miR-125b overexpression decreased apoptosis.

CONCLUSION

Our findings indicate that miR-125b is down-regulated in SSc skin and primary dermal fibroblasts. MiR-125b down-regulation increases apoptosis and decreases proliferation and α-SMA expression in dermal fibroblasts, indicating that its compensatory, antifibrotic mechanism may be a potential novel therapeutic option.

OTUD6B-AS1 Might Be a Novel Regulator of Apoptosis in Systemic Sclerosis

Antisense long non-coding RNAs (AS lncRNAs) have increasingly been recognized as important regulators of gene expression and they have been found to play key roles in several diseases. However, very little is known about the role of AS lncRNAs in fibrotic diseases such as systemic sclerosis (SSc). Our recent screening experiments by RNA sequencing showed that ovarian tumor domain containing 6B antisense RNA1 (OTUD6B-AS1) and its sense gene OTUD6B were significantly downregulated in SSc skin biopsies. Therefore, we aimed to identify key regulators of OTUD6B-AS1 and to analyze the functional relevance of OTUD6B-AS1 in SSc. OTUD6B-AS1 and OTUD6B expression in SSc and healthy control (HC) dermal fibroblasts (Fb) after stimulation with transforming growth factor-β (TGFβ), Interleukin (IL)-4, IL-13, and platelet-derived growth factor (PDGF) was analyzed by qPCR. To identify the functional role of OTUD6B-AS1, dermal Fb or human pulmonary artery smooth muscle cells (HPASMC) were transfected with a locked nucleic acid antisense oligonucleotide (ASO) targeting OTUD6B-AS1. Proliferation was measured by BrdU and real-time proliferation assay. Apoptosis was measured by Caspase 3/7 assay and Western blot for cleaved caspase 3. While no difference was recorded at the basal level between HC and SSc dermal Fb, the expression of OTUD6B-AS1 and OTUD6B was significantly downregulated in both SSc and HC dermal Fb after PDGF stimulation in a time-dependent manner. Only mild and inconsistent effects were observed with TGFβ, IL-4, and IL-13. OTUD6B-AS1 knockdown in Fb and HPASMC did not affect extracellular matrix or pro-fibrotic/proinflammatory cytokine production. However, OTUD6B-AS1 knockdown significantly increased Cyclin D1 expression at the mRNA and protein level. Moreover, silencing of OTUD6B-AS1 significantly reduced proliferation and suppressed apoptosis in both dermal Fb and HPASMC. OTUD6B-AS1 knockdown did not affect OTUD6B expression at the mRNA level and protein level. Our data suggest that OTUD6B-AS1 regulates proliferation and apoptosis via cyclin D1 expression in a sense gene independent manner. This is the first report investigating the function of OTUD6B-AS1. Our data shed light on a novel apoptosis resistance mechanism in Fb and vascular smooth muscle cells that might be relevant for pathogenesis of SSc.

PU.1 controls fibroblast polarization and tissue fibrosis

Fibroblasts are polymorphic cells with pleiotropic roles in organ morphogenesis, tissue homeostasis and immune responses. In fibrotic diseases, fibroblasts synthesize abundant amounts of extracellular matrix which lead to scaring and organ failure. In contrast, the hallmark feature of fibroblasts in arthritis is matrix degradation by the release of metalloproteinases and degrading enzymes, and subsequent tissue destruction. The mechanisms driving these functionally opposing pro-fibrotic and pro-inflammatory phenotypes of fibroblasts are enigmatic. We identified the transcription factor PU.1 as an essential orchestrator of the pro-fibrotic gene expression program. The interplay between transcriptional and post-transcriptional mechanisms which normally control PU.1 expression is perturbed in various fibrotic diseases, resulting in upregulation of PU.1, induction of fibrosis-associated gene sets, and a phenotypic switch in matrix-producing pro-fibrotic fibroblasts. In contrast, pharmacological and genetic inactivation of PU.1 disrupts the fibrotic network and enables re-programming of fibrotic fibroblasts into resting fibroblasts with regression of fibrosis in different organs.

Downregulation of miR-193b in systemic sclerosis regulates the proliferative vasculopathy by urokinase-type plasminogen activator expression

OBJECTIVES

To investigate the role of microRNA-193b-3p (miR-193b) in the vascular pathophysiology of systemic sclerosis (SSc).

METHODS

Expression of miR-193b in skin biopsies and fibroblasts from patients with SSc and normal healthy (NH) controls were determined by real-time PCR. Transfection with miR-193b precursor and inhibitor were used to confirm targets of miR-193b. Proliferative effects of urokinase-type plasminogen activator (uPA) were determined by water-soluble tetrazolium salt-1 assay and by analysis of proliferating cell nuclear antigen expression. Fluorescence activated cell sorting analysis was performed to investigate the effect of uPA on apoptosis. For inhibition of the uPA-cellular receptor for uPA (uPAR) pathway, uPAR neutralising antibodies and low molecular weight uPA were used.

RESULTS

We found that miR-193b was downregulated in SSc fibroblasts and skin sections as compared with NH controls. The expression of miR-193b was not affected by major profibrotic cytokines and hypoxia. Induction of miR-193b in SSc fibroblasts suppressed, and accordingly, knockdown of miR-193b increased the levels of messenger RNA and protein for uPA. uPA was found to be upregulated in SSc as compared with NH controls in a transforming growth factor-β dependent manner, and uPA was strongly expressed in vascular smooth muscle cells in SSc skin section. Interestingly, uPA induced cell proliferation and inhibited apoptosis of human pulmonary artery smooth muscle cells, and these effects were independent of uPAR signalling.

CONCLUSIONS

In SSc, the downregulation of miR-193b induces the expression of uPA, which increases the number of vascular smooth muscle cells in an uPAR-independent manner and thereby contributes to the proliferative vasculopathy with intimal hyperplasia characteristic for SSc.