Biology subjects

Distler, O.

Publications and source records attributed to Distler, O..

15 recordsLinked to original sources

bioRxiv2026

Pulmonary pressure load shapes right ventricular molecular remodelling in dilated cardiomyopathy

Right ventricular (RV) adaptation to pulmonary hypertension determines outcome in dilated cardiomyopathy (DCM), but the molecular mechanisms of the transition to decompensation remain unclear. We analysed RV tissue from explanted hearts of patients with end-stage DCM using single-nucleus RNA sequencing (n=21), mass spectrometry and Olink Reveal proteomics (both n=44), and integrated these molecular profiles with echocardiographic and right-heart catheterisation measures to identify molecular correlates of RV dysfunction. Mean pulmonary arterial pressure was the dominant correlate of RV transcriptional remodelling, particularly in cardiomyocytes, where higher pressure was associated with contractile remodelling, autophagy, vesicle trafficking and glucose metabolism. In contrast, RV decompensation was characterised by immune activation and reduced oxidative phosphorylation exclusively at the proteomic level. Integrative multi-omics factor analysis (MOFA) further identified fibrosis as the dominant molecular program shared across transcriptomic and proteomic layers. Together, these findings indicate molecular adaptation to pressure load and tissue fibrosis during progression towards RV failure.

physiology↗

bioRxiv2026

Lanifibranor (IVA-337) - a pan-PPAR agonist suppresses TGF-β1-induced cardiac fibrosis and rescues cardiomyocyte function

Background: Cardiac fibrosis is a hallmark of many cardiovascular diseases, driven by sustained fibroblast activation and excessive extracellular matrix deposition, leading to myocardial stiffening and impaired contractility. Current therapies inadequately address this process. This study evaluated the antifibrotic potential of lanifibranor, a balanced pan-peroxisome proliferator-activated receptors (PPARs) agonist, in TGF-beta1-induced cardiac fibrosis. Methods: Human cardiac microtissues, along with 2D and 3D cardiac fibroblast and cardiomyocyte cultures, were used to assess cell viability, structure, metabolism, contractility, and gene expression. Results: Lanifibranor reduced TGF-beta1-induced fibrosis by limiting fibroblast activation and matrix deposition without affecting viability. In fibroblasts, these effects were associated with partial restoration of mitochondrial respiration and reduced focal adhesion maturation. In cardiac microtissues, lanifibranor improved contraction kinetics, decreased profibrotic transcriptional activity, and preserved bioenergetic homeostasis despite altered nucleotide balance. In cardiomyocytes, treatment normalized contractility and calcium handling while maintaining metabolic stability. Conclusions: Lanifibranor attenuates TGF-beta1-driven cardiac fibrosis by combining antifibrotic effects with metabolic and functional improvements in human models.

pharmacology and toxicology↗

bioRxiv2026

The dual PPAR-α/δ agonist elafibranor attenuates TGF-β1-induced cardiac fibrosis through redox-metabolic and bioenergetic reprogramming in human cardiac models

BackgroundCardiac fibrosis drives adverse myocardial remodelling through persistent fibroblast activation, ECM deposition, and impaired cardiac function. Current therapies offer limited protection against cardiac fibrosis progression. Elafibranor is a dual PPAR-/{delta} agonist approved for the treatment of liver disease. However, its effects in human models of cardiac fibrosis remain insufficiently explored. MethodsElafibranor was evaluated in complementary human in vitro TGF-{beta}1-induced cardiac fibrosis models: 2D primary fibroblasts, 3D fibroblast spheroids, spontaneously contracting 3D cardiac microtissues, and hiPSC-derived cardiomyocytes. Viability, apoptosis, fibroblast activation, ECM remodelling, mitochondrial respiration, nucleotide and NAD pools, calcium handling, contractility, and transcriptomic profiles were assessed. ResultsAt non-cytotoxic concentrations, elafibranor attenuated TGF-{beta}1-driven cardiac fibrosis responses. In 2D cardiac fibroblasts, it reduced myofibroblast differentiation, procollagen 11 secretion, and partially restored mitochondrial respiratory capacity. In 3D spheroids, it preserved viability, attenuated caspase-3/7 activation, and suppressed procollagen 11 release. In cardiac microtissues, elafibranor reduced ECM accumulation, shifted transcriptomic profiles toward redox-metabolic/cytoprotective pathways, altered adenine nucleotide and NAD pools, and partially recovered contraction parameters. In hiPSC-derived cardiomyocytes, elafibranor modulated calcium handling, contractility, and mitochondrial respiration. ConclusionsElafibranor mitigates TGF-{beta}1-driven cardiac fibrosis by suppressing fibroblast activation and ECM remodelling while promoting adaptive metabolic, redox, and bioenergetic responses, supporting balanced PPAR-/{delta} activation as a potential therapeutic strategy for cardiac fibrosis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/745425v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@2de670org.highwire.dtl.DTLVardef@173fea6org.highwire.dtl.DTLVardef@537e7aorg.highwire.dtl.DTLVardef@194b846_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2026

Dysferlin is a novel regulator of COMP-positive matrifibrocytes in heart failure

Background and AimsCardiac fibrosis is a major contributor to heart failure (HF), yet mechanisms limiting pathological fibroblast activation remain incompletely understood. We identified dysferlin (DYSF), a membrane repair protein, as highly induced in HF fibroblasts and investigated its role in regulating profibrotic responses. MethodsCardiac fibroblasts from patients with end-stage HF and unaffected donor hearts were analysed by liquid chromatography-tandem mass spectrometry and bulk RNA sequencing. Dysferlin expression was validated in independent cohorts. Selected gene/protein expression was validated using single-cell/single-nucleus RNA sequencing and multiplex immunofluorescence of human myocardium from dilated cardiomyopathy (DCM), ischaemic cardiomyopathy (ICM), acute myocardial infarction (AMI), and unaffected hearts. Functional studies were performed in human and mouse cardiac fibroblasts using siRNA-mediated silencing and TGF-{beta} stimulation, and in engineered human 3D cardiac microtissues. Fibrotic remodelling, autophagy, apoptosis, and contractile function were assessed by molecular, histological, biochemical and functional analyses. ResultsDysferlin abundance was markedly increased in HF fibroblasts. Across HF myocardium, DYSF was enriched in activated fibroblasts but largely excluded from COMP-enriched fibrotic regions, consistent with a role in restraining fibroblast state transitions. Although induced by TGF-{beta}, DYSF silencing enhanced extracellular matrix production, increased FOSL2 expression, and promoted differentiation into COMP-positive matrifibrocytes. In engineered human cardiac microtissues, DYSF silencing exacerbated fibrosis, increased apoptosis, and impaired contractility. Mechanistically, dysferlin restrained the TGF-{beta}-FOSL2-autophagy signalling axis, whereas FOSL2 suppressed DYSF expression, defining a reciprocal regulatory circuit. Silencing FOSL2 or MXRA5 increased dysferlin levels, while mRNA-protein discordance implicated S-acylation as a potential regulator of dysferlin protein abundance. ConclusionsDysferlin is a stress-inducible antifibrotic regulator that limits maladaptive fibroblast differentiation and myocardial fibrosis, thereby representing a potential therapeutic target to attenuate adverse cardiac remodelling in HF. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/745492v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@46ae02org.highwire.dtl.DTLVardef@4a0b99org.highwire.dtl.DTLVardef@13fa574org.highwire.dtl.DTLVardef@18777d4_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2026

Comparison of Culture Systems for Mouse Living Myocardial Slices in Cardiac Fibrosis Research

Living myocardial slices (LMS) are a highly relevant ex vivo model for investigating cardiac physiology and disease, as they preserve the native three-dimensional architecture, cellular diversity, and extracellular matrix of the heart. In addition, LMS enable longitudinal functional and molecular analyses. In this study, we established and compared two LMS culture approaches: an air-liquid interface system and a biomimetic culture system. We further examined how different slicing techniques affect tissue quality and longevity within the biomimetic setup. To develop a fibrosis model, LMS were stimulated with transforming growth factor-beta1 (TGF-beta1) and/or exposed to increased mechanical load. Tissue viability was assessed using LIVE/DEAD staining and the MTT assay, while cytotoxicity was evaluated with the LDH-Glo-TM Cytotoxicity assay. Contractile function was measured, and fibrotic remodelling was analysed using RT-qPCR, ELISA, and immunohistochemistry. Our results demonstrate that LMS cultured in the biomimetic system exhibit superior viability, structural integrity, and functional performance compared with those maintained at the air-liquid interface. Mouse LMS could be stably cultured for up to one week in the biomimetic system. Importantly, sample preparation, particularly the slicing method, had a significant impact on tissue quality and culture duration. While TGF-beta1 stimulation alone did not consistently induce fibrosis, combining TGF-beta1 treatment with increased mechanical load led to more pronounced fibrotic remodelling in LMS. These findings highlight the importance of biomechanical cues in modelling cardiac fibrosis ex vivo and support the biomimetic system as a robust platform for functional and disease-relevant studies.

cell biology↗

bioRxiv2026

Compartmental Profiling of PDE4B in Systemic Sclerosis

ObjectivesThe preferential phosphodiesterase 4B (PDE4B) inhibitor nerandomilast was recently approved for treatment of idiopathic pulmonary fibrosis (IPF) and progressive pulmonary fibrosis. Its proposed immunomodulatory, anti-fibrotic, and endothelial-stabilising actions target all three cardinal features of SSc, yet PDE4B expression has not been systematically characterised in SSc tissue. We aimed to define PDE4B expression across fibrotic organs and cellular compartments in SSc. MethodsPDE4B expression was profiled in SSc lung, peripheral blood mononuclear cells (PBMCs) and skin on the transcript level using single-cell RNA sequencing data and on the protein level using immunohistochemistry, immunofluorescence and multiplexed immunofluorescent stainings. ResultsPDE4B was consistently dysregulated in immune cells across SSc tissue and PBMCs, with compartment-specific direction and distribution. In SSc-ILD lung, expression was increased in CD8 and CD4 memory T-cells. In PBMCs, expression was increased in B cells, monocytes, and CD8 T-cells, and stratified patients into three endotypes (PDE4B//hi) not distinguishable by clinical variables. In skin, bulk RNA-seq showed a significant global increase, which localized to myeloid cells in scRNA-seq data. Approximately 90% of FAP activated fibroblasts co-expressed PDE4B at the protein level in SSc skin, identifying the activated fibroblast compartment as a candidate target for PDE4B inhibition. No PDE4B dysregulation was detected in vascular cell types. ConclusionsThis first cell-type-resolved characterisation of PDE4B in SSc demonstrates consistent immune-cell dysregulation across tissues and protein-level enrichment in activated fibroblasts. This provides a human-tissue rationale for the immunomodulatory and anti-fibrotic effects of PDE4B inhibition and supporting PDE4B as a disease-relevant therapeutic target in SSc. Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSO_LINerandomilast (BI 1015550), a PDE4B-preferential inhibitor, was approved for idiopathic pulmonary fibrosis and progressive pulmonary fibrosis. C_LIO_LIPre-clinical studies indicate that PDE4B inhibition may act on all cardinal features of SSc. C_LI What this study addsO_LIFirst cell-type-resolved characterization of PDE4B expression across SSc-affected lung, PBMCs, and skin. C_LIO_LIPBMC PDE4B expression is heterogeneous, stratifying patients into PDE4B// endotypes independent of standard clinical variables. C_LIO_LIscRNA-seq shows increased myeloid PDE4B expression in SSc skin, while [~]90% of FAP activated fibroblasts in SSc skin express PDE4B protein. C_LI How this study might affect research, practice or policyO_LIThe study strengthens the human-level evidence underpinning the target rationale for PDE4B inhibition in SSc. C_LI

molecular biology↗

bioRxiv2026

Synovitis in systemic sclerosis is an interferon-driven stromal condition distinct from rheumatoid arthritis

Joint involvement is a major driver of disability in systemic sclerosis (SSc), yet its pathophysiology remains poorly understood. In the absence of specific evidence, SSc synovitis is treated by analogy with rheumatoid arthritis (RA). Here, we present the first comprehensive molecular characterization of SSc synovitis, integrating histology, single-cell RNA sequencing, and spatial multi-omics of synovial biopsies from SSc patients, RA patients, and non-inflammatory controls with in vitro validation. We show that SSc synovitis is characterized by distinct pathomechanisms from RA. Histologically, most SSc biopsies displayed a pauci-immune pathotype with sparse immune infiltrates and predominant stromal cells. At molecular level, synovial fibroblasts in SSc were characterized by a disease-specific type I interferon (IFN) response program, in contrast to the TNF-dominant profile of RA, accompanied by dysregulation of the complement cascade. This IFN program extended across multiple synovial cell types, including monocyte-derived macrophages and endothelial cells, and was spatially organized into focal myeloid niches and a diffuse stromal program. Systemically, elevated serum IFN-2a levels were associated with the presence of clinical synovitis in an independent cohort of SSc patients. We furthermore show that similar IFN-driven programs are shared between skin and synovium in SSc. Genes downregulated by IFNAR1 blockade in SSc skin were enriched in SSc synovium, supporting IFN receptor blockade as a multi-organ target therapeutic strategy. These findings reframe SSc synovitis as a less destructive, IFN-driven stromal condition distinct from RA and provide a mechanistic basis for dedicated clinical trials for joint inflammation in SSc. One Sentence SummarySSc synovitis is a pauci-immune, IFN-driven stromal condition distinct from RA, supporting IFNAR1 blockade as a therapeutic strategy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/733140v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@d85bb5org.highwire.dtl.DTLVardef@6cffe6org.highwire.dtl.DTLVardef@148eb4org.highwire.dtl.DTLVardef@1a4cd83_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2026

Metabolic-secretory decoupling defines a disease-intrinsic state in rheumatoid arthritis monocytes

ObjectivesCirculating monocytes from rheumatoid arthritis (RA) patients are pre-primed for inflammatory activation, but their disease-intrinsic features have not been systematically characterized. Given the important role of metabolism in shaping immune cell function, we aimed to determine how this pre-primed state is underpinned metabolically and whether these changes persist across different activation states, using an unbiased multi-omics approach. MethodsPeripheral blood CD14 monocytes from RA patients and matched healthy donors were analyzed in an undifferentiated state (M0) and after differentiation into classically activated M(IFN{gamma}+LPS) and alternatively activated M(IL-4) macrophages, followed by acute lipopolysaccharide (LPS) stimulation. Metabolomic (untargeted LC-MS/MS), transcriptomic (RNA-seq), and proteomic (label-free mass LC-MS/MS) profiling were performed. Data was comprehensively analyzed by weighted gene correlation network analysis, differential analysis, gene set enrichment analysis, multi-omics factor analysis and metabolic flux modeling. ResultsRA monocytes exhibited a stable disease-driven signature across activation states. Integration of metabolomic, transcriptomic and proteomic data revealed an unexpected convergence on metabolic-secretory coupling, with depletion of nucleotide and redox metabolites, downregulation of mitochondrial and translational pathways, and remodeling of the secretory apparatus, including loss of cis-Golgi components. Consistently, metabolic modeling predicted reduced glycosylation fluxes, connecting metabolic changes to altered secretory capacity. ConclusionsRA monocytes adopt a stable, disease-intrinsic state that persists across activation conditions. Multi-omics data identify a linked metabolic and secretory defect, with reduced glycosylation capacity as a potential functional consequence. This metabolic-secretory coupling represents a defining feature of RA monocyte dysfunction and a potential therapeutic target.

immunology↗

bioRxiv2026

Synovial fibroblast niche shapes the efficacy - safety dynamics of JAK inhibition in rheumatoid arthritis

Synovial fibroblasts (SF) drive joint pathology in rheumatoid arthritis (RA). Difficult-to-treat RA frequently exhibits a fibroblast-rich synovial pathotype, enriched in DKK3{square} and CD34{square} SF, highlighting a critical therapeutic gap. Through multicohort transcriptomic analysis of synovial tissues and mechanistic in vitro studies, we identified SF as principal targets of Janus kinase (JAK) inhibition in RA. We demonstrated that JAK inhibitors (JAKi) can target multiple core aspects of fibroblast pathobiology - therapeutic refractoriness, cartilage destruction, and inflammation - offering a mechanistic rationale for JAKi superiority in difficult-to-treat RA. JAK1 was the dominantly expressed JAK across synovial pathotypes and SF subsets, including DKK3{square} and CD34{square} populations. A STAT1-interferon type I gene program was enriched in matrix-destructive PRG4{square} SF, consistent with JAKi efficacy in erosive RA. In contrast, canonical IL-6 signaling predominated in IL6-expressing inflammatory CXCL12high and HLA-DR+ SF, and was reproduced in cytokine-stimulated cultured SF, underscoring the autocrine nature of synovial IL-6 signaling. These data inferred a heightened JAKi sensitivity of PRG4{square}, CXCL12high, and HLA-DR+ SF subsets, informing precision therapeutic strategies. We uncovered a strong synergy between TNF and IL-6 trans-signaling, profoundly amplifying fibroblast inflammation. In high and synergistic cytokine milieu, STAT1/3 phosphorylation and IL-6 secretion persisted in SF despite tofacitinib treatment, revealing tofacitinibs functional ceiling. This could explain reduced tofacitinib efficacy and adherence in patients with high baseline arthritis activity. Finally, inflamed SF partially uncoupled STAT3 activation from sustained JAK1 phosphorylation, limiting inflammatory output. Similar uncoupling in tofacitinib-treated SF, likely drove rapid STAT1/3 reactivation following tofacitinib washout. These data aligned with JAKi withdrawal complications and clinical recommendations for gradual JAKi tapering. Collectively, our study identifies SF as key cellular targets of JAK inhibition and delineates cytokine- and drug-driven mechanisms that may constrain the efficacy and safety profiles of JAKi in RA.

molecular biology↗

bioRxiv2025

Distinct myeloid precursors and their interaction with mesenchymal cells orchestrate the spreading of psoriatic disease from the skin to the joints

Psoriatic disease initially affects the skin, but later extends to the joints. Herein, we describe a two-step process that orchestrates spreading of inflammation from the skin to the joints. Induction of psoriatic skin disease in photoconvertible mice, followed by sequencing and computational characterization of skin-derived cells in the joints, identified a unique population of CD2+ MHC-II+ CCR2+ myeloid precursors that built up a skin-derived myeloid cell compartment in the joints. Single-cell cross-species reference mapping and mitochondrial variant tracing showed an orthologue human cell population. Interactome analyses in the joints showed that in a second step, resident regulatory CD200+ fibroblasts critically regulate the priming of the CD2+ MHC-II+ CCR2+ myeloid precursors, which subsequently regulate the IL-17 expression in T cells. Hence, spreading of inflammation requires a distinct migratory myeloid precursor population and a permissive local tissue environment, similar to tumour metastasis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=121 SRC="FIGDIR/small/665302v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@38c440org.highwire.dtl.DTLVardef@dc574dorg.highwire.dtl.DTLVardef@1e79f72org.highwire.dtl.DTLVardef@19508cf_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

5' HOXD Genes Differentially Regulate Gene Expression of Synovial Fibroblasts in Hand Joints

We previously demonstrated that Homeobox (HOX) transcription factors are differentially expressed between joint locations and can accurately assign synovial fibroblasts (SFs) to their correct joint location. We show here that the expression of the 5HOXD transcription factors HOXD10, HOXD11, and HOXD13 in SFs strikingly overlaps with predilection sites for the development of rheumatoid arthritis (RA). Changes in SFs gene expression after silencing 5HOXDs aligned with joint-specific differences of RA SFs. In particular, we identify HOXD13 as regulator or primary cilia function in SFs modulating cell cycle, DNA damage and proteasome activity. Accordingly, we show joint specific differences in primary cilia morphology, DNA damage repair and proteasome activity. We thus propose that HOXD13 and primary cilia play a role in shaping joint-specific SFs functions that might underlie the pathognomic pattern of joint involvement in RA.

cell biology↗

bioRxiv2024

Radioproteomics stratifies molecular response to antifibrotic treatment in pulmonary fibrosis

Antifibrotic therapy with nintedanib is the clinical mainstay in the treatment of progressive fibrosing interstitial lung disease (ILD). High-dimensional medical image analysis, known as radiomics, provides quantitative insights into organ-scale pathophysiology, generating digital disease fingerprints. Here, we used an integrative analysis of radiomic and proteomic profiles (radioproteomics) to assess whether changes in radiomic signatures can stratify the degree of antifibrotic response to nintedanib in (experimental) fibrosing ILD. Unsupervised clustering of delta radiomic profiles revealed two distinct imaging phenotypes in mice treated with nintedanib, contrary to conventional densitometry readouts, which showed a more uniform response. Integrative analysis of delta radiomics and proteomics demonstrated that these phenotypes reflected different treatment response states, as further evidenced on transcriptional and cellular levels. Importantly, radioproteomics signatures paralleled disease- and drug related biological pathway activity with high specificity, including extracellular matrix (ECM) remodeling, cell cycle activity, wound healing, and metabolic activity. Evaluation of the preclinical molecular response-defining features, particularly those linked to ECM remodeling, in a cohort of nintedanib-treated fibrosing ILD patients, accurately stratified patients based on their extent of lung function decline. In conclusion, delta radiomics has great potential to serve as a non-invasive and readily accessible surrogate of molecular response phenotypes in fibrosing ILD. This could pave the way for personalized treatment strategies and improved patient outcomes.

molecular biology↗

bioRxiv2023

Liposomal aggregates sustain the release of rapamycin and protect cartilage from friction

Fibrosis, low-grade inflammation, and increased friction are together with degradation of cartilage key culprits for debilitating pain in osteoarthritis (OA), which is one of the most common chronic diseases of todays aging population. Intraarticular administration of bio-lubricants loaded with a pharmaceutically active component recently showed promise to improve therapy. Liposomes have emerged as exceptional lubricant biomaterial, but their small size leads to rapid clearance from the synovium, causing a need for more frequent administration. We recently developed a liposomal drug delivery system based on aggregation of negatively charged liposomes with physiologically present divalent cations. Here, we expanded our platform by replacing calcium with zinc, reported to exert anti-inflammatory action. The liposomal aggregates extend the release of rapamycin (RAPA) beyond the free liposomes and have a diameter of nearly 100 m, which was previously established to improve retention in synovial joints. Electron microscopy showed that RAPA alters the irregular morphology of liposomal clusters, which are irreversible upon dilution. RAPA recently showed great promise both in vitro and in vivo at protecting the joints from inflammation and cartilage from further degradation. Our study adds to this by showing that RAPA is also able to dampen the fibrotic response in human OA synovial fibroblasts. Finally, the tribological properties were assessed on nano- and macro-scales on silicon surface and ex vivo porcine cartilage, which showed an excellent protective ability of the system against friction on both scales. Taken together, our study shows that liposomal aggregates have the potential of improving local OA therapy.

pharmacology and toxicology↗

bioRxiv2022

A comprehensive single-cell atlas of freshly dissociated human synovium in inflammatory arthritis with an optimized dissociation protocol for prospective fresh synovial biopsy collection

Single-cell RNA-sequencing is advancing our understanding of synovial pathobiology in inflammatory arthritis. Here, we optimized the protocol for the dissociation of fresh synovial biopsies and created a reference single-cell map of fresh human synovium in inflammatory arthritis. We utilized the published method for dissociating cryopreserved synovium and optimized it for dissociating small fresh synovial biopsies. The optimized protocol enabled the isolation of a good yield of consistently highly viable cells, minimizing the dropout rate of prospectively collected biopsies. Our reference synovium map comprised over 100000 unsorted single-cell profiles from 25 synovial tissues of patients with inflammatory arthritis. Synovial cells formed 11 lymphoid, 15 myeloid and 16 stromal cell clusters, including IFITM2+ synovial neutrophils. Using this reference map, we successfully annotated published synovial scRNA-seq datasets. Our dataset uncovered endothelial cell diversity and identified SOD2highSAA1+SAA2+ and SERPINE1+COL5A3+ fibroblast clusters, expressing genes linked to cartilage breakdown (SDC4) and extracellular matrix remodelling (LOXL2, TGFBI, TGFB1), respectively. We broadened the characterization of tissue resident FOLR2+COLEC12high and LYVE1+SLC40A1+ macrophages, inferring their extracellular matrix sensing and iron recycling activities. Our research brings an efficient synovium dissociation protocol and a reference annotation resource of fresh human synovium, while expanding the knowledge about synovial cell diversity in inflammatory arthritis.

genomics↗

bioRxiv2021

Sustained mechanical tension governs fibrogenic activation of tendon stromal cells in systemic sclerosis

Fibrosis is a pathological outcome of aberrant repair responses in systemic sclerosis and affects many tissues, including tendons. Progressive matrix stiffening is a key feature of this pathological remodeling. How dysregulated tissue mechanics contribute to the persistence of the fibrotic phenotype has been obscured by limited availability of experimental tissue models that are both controllable and capture essential aspects of the tendon biophysical niche. Here, we developed a modular, cantilever-based platform that allows culture of 3D tendon-like constructs under easily variable static tension, emulating this central tendon-specific structure function relationship. The system reveals that elevated matrix tension instigates fibroblast-to-myofibroblast activation eliciting scar-like phenotypes in vitro. By using this mechano-culture system and preclinical and clinical models of systemic sclerosis, we further show that 3D matrix stiffness is inversely correlated with the transcription of major pro-fibrotic collagens, but positively correlate with the expression of markers of stromal-immune interactions. Co-culture of tendon stromal fibroblasts and bone marrow-derived macrophages override stiffness-mediated downregulation of matrix transcription, suggesting that normal tension mediated checkpoints are superseded by the local tissue immune state. Our study highlights the power of 3D reductionist approaches in dissecting the contribution of the elevated matrix tension to the positive feedforward loops between activated fibroblasts and progressive ECM stiffening in systemic sclerosis.

cell biology↗