Exploring Anti-Fibrotic Effects of Adipose-Derived Stem Cells: Transcriptome Analysis upon Fibrotic, Inflammatory, and Hypoxic Conditioning.

Autologous fat transfers show promise in treating fibrotic skin diseases, reversing scarring and stiffness, and improving quality of life. Adipose-derived stem cells (ADSCs) within these grafts are believed to be crucial for this effect, particularly their secreted factors, though the specific mechanisms remain unclear. This study investigates transcriptomic changes in ADSCs after in vitro fibrotic, inflammatory, and hypoxic conditioning. High-throughput gene expression assays were conducted on ADSCs exposed to IL1-ß, TGF-ß1, and hypoxia and in media with fetal bovine serum (FBS). Flow cytometry characterized the ADSCs. RNA-Seq analysis revealed distinct gene expression patterns between the conditions. FBS upregulated pathways were related to the cell cycle, replication, wound healing, and ossification. IL1-ß induced immunomodulatory pathways, including granulocyte chemotaxis and cytokine production. TGF-ß1 treatment upregulated wound healing and muscle tissue development pathways. Hypoxia led to the downregulation of mitochondria and cellular activity.

NKX2-5 regulates vessel remodelling in scleroderma-associated pulmonary arterial hypertension.

NKX2-5 is a member of the homeobox-containing transcription factors critical in regulating tissue differentiation in development. Here, we report a role for NKX2-5 in vascular smooth muscle cell phenotypic modulation in vitro and in vascular remodelling in vivo. NKX2-5 is up-regulated in scleroderma (SSc) patients with pulmonary arterial hypertension. Suppression of NKX2-5 expression in smooth muscle cells, halted vascular smooth muscle proliferation and migration, enhanced contractility and blocked the expression of the extracellular matrix genes. Conversely, overexpression of NKX2-5 suppressed the expression of contractile genes (ACTA2, TAGLN, CNN1) and enhanced the expression of matrix genes (COL1) in vascular smooth muscle cells. In vivo, conditional deletion of NKX2-5 attenuated blood vessel remodelling and halted the progression to hypertension in the mouse chronic hypoxia mouse model. This study revealed that signals related to injury such as serum and low confluence, which induce NKX2-5 expression in cultured cells, is potentiated by TGFß and further enhanced by hypoxia. The effect of TGFß was sensitive to ERK5 and PI3K inhibition. Our data suggest a pivotal role for NKX2-5 in the phenotypic modulation of smooth muscle cells during pathological vascular remodelling and provide proof of concept for therapeutic targeting of NKX2-5 in vasculopathies.

Single-Cell Analysis of ADSC Interactions with Fibroblasts and Endothelial Cells in Scleroderma Skin.

Adipose-derived stem cells (ADSCs) as part of autologous fat grafting have anti-fibrotic and anti-inflammatory effects, but the exact mechanisms of action remain unknown. By simulating the interaction of ADSCs with fibroblasts and endothelial cells (EC) from scleroderma (SSc) skin in silico, we aim to unravel these mechanisms. Publicly available single-cell RNA sequencing data from the stromal vascular fraction of 3 lean patients and biopsies from the skin of 10 control and 12 patients with SSc were obtained from the GEO and analysed using R and Seurat. Differentially expressed genes were used to compare the fibroblast and EC transcriptome between controls and SSc. GO and KEGG functional enrichment was performed. Ligand-receptor interactions of ADSCs with fibroblasts and ECs were explored with LIANA. Pro-inflammatory and extracellular matrix (ECM) interacting fibroblasts were identified in SSc. Arterial, capillary, venous and lymphatic ECs showed a pro-fibrotic and pro-inflammatory transcriptome. Most interactions with both cell types were based on ECM proteins. Differential interactions identified included NTN1, VEGFD, MMP2, FGF2, and FNDC5. The ADSC secretome may disrupt vascular and perivascular inflammation hubs in scleroderma by promoting angiogenesis and especially lymphangiogenesis. Key phenomena observed after fat grafting remain unexplained, including modulation of fibroblast behaviour.

Unravelling morphoea aetiopathogenesis by next-generation sequencing of paired skin biopsies.

BACKGROUND: Morphoea can have a significant disease burden. Aetiopathogenesis remains poorly understood, with very limited existing genetic studies. Linear morphoea (LM) may follow Blascho's lines of epidermal development, providing potential pathogenic clues. OBJECTIVE: The first objective of this study was to identify the presence of primary somatic epidermal mosaicism in LM. The second objective was tTo explore differential gene expression in morphoea epidermis and dermis to identify potential pathogenic molecular pathways and tissue layer cross-talk. METHODOLOGY: Skin biopsies from paired affected and contralateral unaffected skin were taken from 16 patients with LM. Epidermis and dermis were isolated using a 2-step chemical-physical separation protocol. Whole Genome Sequencing (WGS; n = 4 epidermal) and RNA-seq (n = 5-epidermal, n = 5-dermal) with gene expression analysis via GSEA-MSigDBv6.3 and PANTHER-v14.1 pathway analyses, were performed. RTqPCR and immunohistochemistry were used to replicate key results. RESULTS: Sixteen participants (93.8% female, mean age 27.7 yrs disease-onset) were included. Epidermal WGS identified no single affected gene or SNV. However, many potential disease-relevant pathogenic variants were present, including ADAMTSL1 and ADAMTS16. A highly proliferative, inflammatory and profibrotic epidermis was seen, with significantly-overexpressed TNFα-via-NFkB, TGFß, IL6/JAKSTAT and IFN-signaling, apoptosis, p53 and KRAS-responses. Upregulated IFI27 and downregulated LAMA4 potentially represent initiating epidermal 'damage' signals and enhanced epidermal-dermal communication. Morphoea dermis exhibited significant profibrotic, B-cell and IFN-signatures, and upregulated morphogenic patterning pathways such as Wnt. CONCLUSION: This study supports the absence of somatic epidermal mosaicism in LM, and identifies potential disease-driving epidermal mechanisms, epidermal-dermal interactions and disease-specific dermal differential-gene-expression in morphoea. We propose a potential molecular narrative for morphoea aetiopathogenesis which could help guide future targeted studies and therapies.

Dysregulated B cell function and disease pathogenesis in systemic sclerosis.

Systemic sclerosis (SSc) is a complex, immune-mediated rheumatic disease characterised by excessive extracellular matrix deposition in the skin and internal organs. B cell infiltration into lesional sites such as the alveolar interstitium and small blood vessels, alongside the production of defined clinically relevant autoantibodies indicates that B cells play a fundamental role in the pathogenesis and development of SSc. This is supported by B cell and fibroblast coculture experiments revealing that B cells directly enhance collagen and extracellular matrix synthesis in fibroblasts. In addition, B cells from SSc patients produce large amounts of profibrotic cytokines such as IL-6 and TGF-ß, which interact with other immune and endothelial cells, promoting the profibrotic loop. Furthermore, total B cell counts are increased in SSc patients compared with healthy donors and specific differences can be found in the content of naïve, memory, transitional and regulatory B cell compartments. B cells from SSc patients also show differential expression of activation markers such as CD19 which may shape interactions with other immune mediators such as T follicular helper cells and dendritic cells. The key role of B cells in SSc is further supported by the therapeutic benefit of B cell depletion with rituximab in some patients. It is notable also that B cell signaling is impaired in SSc patients, and this could underpin the failure to induce tolerance in B cells as has been shown in murine models of scleroderma.

The pan-PPAR agonist lanifibranor reduces development of lung fibrosis and attenuates cardiorespiratory manifestations in a transgenic mouse model of systemic sclerosis.

BACKGROUND: The TßRII∆k-fib transgenic (TG) mouse model of scleroderma replicates key fibrotic and vasculopathic complications of systemic sclerosis through fibroblast-directed upregulation of TGFß signalling. We have examined peroxisome proliferator-activated receptor (PPAR) pathway perturbation in this model and explored the impact of the pan-PPAR agonist lanifibranor on the cardiorespiratory phenotype. METHODS: PPAR pathway gene and protein expression differences from TG and WT sex-matched littermate mice were determined at baseline and following administration of one of two doses of lanifibranor (30 mg/kg or 100 mg/kg) or vehicle administered by daily oral gavage up to 4 weeks. The prevention of bleomycin-induced lung fibrosis and SU5416-induced pulmonary hypertension by lanifibranor was explored. RESULTS: Gene expression data were consistent with the downregulation of the PPAR pathway in the TßRII∆k-fib mouse model. TG mice treated with high-dose lanifibranor demonstrated significant protection from lung fibrosis after bleomycin and from right ventricular hypertrophy following induction of pulmonary hypertension by SU5416, despite no significant change in right ventricular systolic pressure. CONCLUSIONS: In the TßRII∆k-fib mouse strain, treatment with 100 mg/kg lanifibranor reduces the development of lung fibrosis and right ventricular hypertrophy induced by bleomycin or SU5416, respectively. Reduced PPAR activity may contribute to the exaggerated fibroproliferative response to tissue injury in this transgenic model of scleroderma and its pulmonary complications.

Selective deletion of connective tissue growth factor attenuates experimentally-induced pulmonary fibrosis and pulmonary arterial hypertension.

Connective tissue growth factor (CTGF, CCN2) is a matricellular protein which plays key roles in normal mammalian development and in tissue homeostasis and repair. In pathological conditions, dysregulated CCN2 has been associated with cancer, cardiovascular disease, and tissue fibrosis. In this study, genetic manipulation of the CCN2 gene was employed to investigate the role of CCN2 expression in vitro and in experimentally-induced models of pulmonary fibrosis and pulmonary arterial hypertension (PAH). Knocking down CCN2 using siRNA reduced expression of pro-fibrotic markers (fibronectin p < 0.01, collagen type I p < 0.05, α-SMA p < 0.0001, TIMP-1 p < 0.05 and IL-6 p < 0.05) in TGF-ß-treated lung fibroblasts derived from systemic sclerosis patients. In vivo studies were performed in mice using a conditional gene deletion strategy targeting CCN2 in a fibroblast-specific and time-dependent manner in two models of lung disease. CCN2 deletion significantly reduced pulmonary interstitial scarring and fibrosis following bleomycin-instillation, as assessed by fibrotic scores (wildtype bleomycin 3.733 ± 0.2667 vs CCN2 knockout (KO) bleomycin 4.917 ± 0.3436, p < 0.05) and micro-CT. In the well-established chronic hypoxia/Sugen model of pulmonary hypertension, CCN2 gene deletion resulted in a significant decrease in pulmonary vessel remodelling, less right ventricular hypertrophy and a reduction in the haemodynamic measurements characteristic of PAH (RVSP and RV/LV + S were significantly reduced (p < 0.05) in CCN2 KO compared to WT mice in hypoxic/SU5416 conditions). These results support a prominent role for CCN2 in pulmonary fibrosis and in vessel remodelling associated with PAH. Therefore, therapeutics aimed at blocking CCN2 function are likely to benefit several forms of severe lung disease.

Serum markers of pulmonary epithelial damage in systemic sclerosis-associated interstitial lung disease and disease progression.

BACKGROUND AND OBJECTIVE: The course of systemic sclerosis-associated interstitial lung disease (SSc-ILD) is highly variable, and accurate prognostic markers are needed. KL-6 is a mucin-like glycoprotein (MUC1) expressed by type II pneumocytes, while CYFRA 21-1 is expressed by alveolar and bronchiolar epithelial cells. Both are released into the blood from cell injury. METHODS: Serum KL-6 and CYFRA 21-1 levels were measured in a retrospective (n = 189) and a prospective (n = 118) cohort of SSc patients. Genotyping of MUC1 rs4072037 was performed. Linear mixed-effect models were used to evaluate the relationship with change in lung function parameters over time, while association with survival was evaluated with Cox proportional hazard analysis. RESULTS: In both cohorts, KL-6 and CYFRA 21-1 were highest in patients with lung involvement, and in patients with extensive rather than limited ILD. KL-6 was higher in patients carrying the MUC1 rs4072037 G allele in both cohorts. In patients with SSc-ILD, serum KL-6, but not CYFRA 21-1, was significantly associated with DLCO decline in both cohorts (P = 0.001 and P = 0.004, respectively), and with FVC decline in the retrospective cohort (P = 0.005), but not the prospective cohort. When combining the cohorts and subgrouping by severity (median CPI = 45.97), KL-6 remained predictive of decline in DLCO in both milder (P = 0.007) and more severe disease (P = 0.02) on multivariable analysis correcting for age, gender, ethnicity, smoking history and MUC1 allele carriage. CONCLUSION: Our results suggest serum KL-6 predicts decline in lung function in SSc, suggesting its clinical utility in risk stratification for progressive SSc-ILD.

Defining genetic risk factors for scleroderma-associated interstitial lung disease : IRF5 and STAT4 gene variants are associated with scleroderma while STAT4 is protective against scleroderma-associated interstitial lung disease.

Although several genetic associations with scleroderma (SSc) are defined, very little is known on genetic susceptibility to SSc-associated interstitial lung disease (SSc-ILD). A number of common polymorphisms have been associated with SSc-ILD, but most have not been replicated in separate populations. Four SNPs in IRF5, and one in each of STAT4, CD226 and IRAK1, selected as having been previously the most consistently associated with SSc-ILD, were genotyped in 612 SSc patients, of European descent, of whom 394 had ILD. The control population (n = 503) comprised individuals of European descent from the 1000 Genomes Project. After Bonferroni correction, two of the IRF5 SNPs, rs2004640 (OR (95% CI)1.30 (1.10-1.54), pcorr = 0.015) and rs10488631 (OR 1.48 (1.14-1.92), pcorr = 0.022), and the STAT4 SNP rs7574865 (OR 1.43 (1.18-1.73), pcorr = 0.0015) were significantly associated with SSc compared with controls. However, none of the SNPs were significantly different between patients with SSc-ILD and controls. Two SNPs in IRF5, rs10488631 (OR 1.72 (1.24-2.39), pcorr = 0.0098), and rs2004640 (OR 1.39 (1.11-1.75), pcorr = 0.03), showed a significant difference in allele frequency between controls and patients without ILD, as did STAT4 rs7574865 (OR 1.86 (1.45-2.38), pcorr = 6.6 × 10-6). A significant difference between SSc with and without ILD was only observed for STAT4 rs7574865, being less frequent in patients with ILD (OR 0.66 (0.51-0.85), pcorr = 0.0084). In conclusion, IRF5 rs2004640 and rs10488631, and STAT4 rs7574865 were significantly associated with SSc as a whole. Only STAT4 rs7574865 showed a significant difference in allele frequency in SSc-ILD, with the T allele being protective against ILD.Key points• We confirm the associations of the IRF5 SNPs rs2004640 and rs10488631, and the STAT4 SNP rs7574865, with SSc as a whole.• None of the tested SNPs were risk factors for SSc-ILD specifically.• The STAT4 rs7574865 T allele was protective against the development of lung fibrosis in SSc patients.• Further work is required to understand the genetic basis of lung fibrosis in association with scleroderma.

Stem cell enriched lipotransfer reverses the effects of fibrosis in systemic sclerosis.

Oro-facial fibrosis in systemic sclerosis (Scleroderma;SSc) has a major impact on mouth function, facial appearance, and patient quality of life. Lipotransfer is a method of reconstruction that can be used in the treatment of oro-facial fibrosis. The effect of this treatment not only restores oro-facial volume but has also been found to reverse the effects of oro-facial fibrosis. Adipose derived stem cells (ADSCs) within the engrafted adipose tissue have been shown to be anti-fibrotic in SSc and are proposed as the mechanism of the anti-fibrotic effect of lipotransfer. A cohort of 62 SSc patients with oro-facial fibrosis were assessed before and after stem cell enriched lipotransfer treatment. Clinical evaluation included assessment of mouth function using a validated assessment tool (Mouth Handicap in Systemic Sclerosis Scale-MHISS), validated psychological measurements and pre and post-operative volumetric assessment. In addition, to understand the mechanism by which the anti-fibrotic effect of ADSCs occur, SSc derived fibroblasts and ADSCs from this cohort of patients were co-cultured in direct and indirect culture systems and compared to monoculture controls. Cell viability, DNA content, protein secretion of known fibrotic mediators including growth factor- ß1 (TGF ß-1) and connective tissue growth factor (CTGF) using ELISA analysis and fibrosis gene expression using a fibrosis pathway specific qPCR array were evaluated. Mouth function (MHISS) was significantly improved (6.85±5.07) (p<0.0001) after treatment. All psychological measures were significantly improved: DAS 24 (12.1±9.5) (p<0.0001); HADS-anxiety (2.8±3.2) (p<0.0001), HADS-depression (2.0±3.1) (p<0.0001); BFNE (2.9 ± 4.3) (p<0.0001); VAS (3.56±4.1) (p<0.0001). Multiple treatments further improved mouth function (p<0.05), DAS (p<0.0001) and VAS (p = 0.01) scores. SSc fibroblast viability and proliferation was significantly reduced in co-culture compared to monoculture via a paracrine effect over 14 days (p < 0.0001). Protein secretion of transforming growth factor (TGF-ß1) and connective tissue growth factor (CTGF) was significantly reduced in co-culture compared to monoculture (p < 0.0001). Multiple fibrosis associated genes were down regulated in SSc co-culture compared to monoculture after 14 days including Matrix metalloproteinase-8 (MMMP-8), Platelet derived growth factor-ß (PDGF-ß) and Integrin Subunit Beta 6 (ITG-ß6). Autologous stem cell enriched lipotransfer significantly improved the effects of oro-facial fibrosis in SSc in this open cohort study. Lipotransfer may reduce dermal fibrosis through the suppression of fibroblast proliferation and key regulators of fibrogenesis including TG-ß1 and CTGF. Our findings warrant further investigation in a randomised controlled trial.

Functional and phenotypic heterogeneity of Th17 cells in health and disease.

BACKGROUND: Th17 cells have nonredundant roles in maintaining immunity, particularly at mucosal surfaces. These roles are achieved principally through the production of cytokines and the recruitment of other immune cells to maintain the integrity of mucosal barriers and prevent the dissemination of microorganisms. Th17 cells are heterogeneous and exhibit a considerable degree of plasticity. This allows these cells to respond to changing environmental challenges. However, Th17 cells also play pro-inflammatory roles in chronic autoimmune diseases. The trigger(s) that initiate these Th17 responses in chronic autoimmune diseases remain unclear. DESIGN: In this report, we provide an overview of studies involving animal models, patient data, genome wide association studies and clinical trials targeting IL-17 for treatment of patients to gain a better understanding of the pathogenic roles of Th17 cells play in a range of autoimmune diseases. RESULTS: The report sheds light on likely triggers that initiate or perpetuate Th17 responses that promote chronic inflammation and autoimmunity. The divergent effects of tumour necrosis factor alpha blockade on Th17 cells in patients, is explored. Furthermore, we highlight the role of Th17 cells in inducing autoreactive B cells, leading to autoantibody production. Pathogenic bacterial species can change Th17 cell phenotype and responses. These findings provide insights into how Th17 cells could be induced to promoting autoimmune disease pathogenesis. CONCLUSION: This article provides an overview of the distinct roles Th17 cells play in maintaining immunity at mucosal surfaces and in skin mucosa and how their functional flexibility could be linked with chronic inflammation in autoimmune rheumatic diseases.

Hydrogel and membrane scaffold formulations of Frutalin (breadfruit lectin) within a polysaccharide galactomannan matrix have potential for wound healing.

Plant lectins are carbohydrate-binding proteins, which can interact with cell surfaces to initiate anti-inflammatory pathways, as well as immunomodulatory functions. Here, we have extracted, purified and part-characterized the bioactivity of Jacalin, Frutalin, DAL and PNA, before evaluating their potential for wound healing in cultured human skin fibroblasts. Only Frutalin stimulated fibroblast migration in vitro, prompting further studies which established its low cytotoxicity and interaction with TLR4 receptors. Frutalin also increased p-ERK expression and stimulated IL-6 secretion. The in vivo potential of Frutalin for wound healing was then assessed in hybrid combination with the polysaccharide galactomannan, purified from Caesalpinia pulcherrima seeds, using both hydrogel and membrane scaffolds formulations. Physical-chemical characterization of the hybrid showed that lectin-galactomannan interactions increased the pseudoplastic behaviour of solutions, reducing viscosity and increasing Frutalin's concentration. Furthermore, infrared spectroscopy revealed -OH band displacement, likely caused by interaction of Frutalin with galactose residues present on galactomannan chains, while average membrane porosity was 100 µm, sufficient to ensure water vapor permeability. Accelerated angiogenesis and increased fibroblast and keratinocyte proliferation were observed with the optimal hybrid recovering the lesioned area after 11 days. Our findings indicate Frutalin as a biomolecule with potential for tissue repair, regeneration and chronic wound healing.

Endothelial C-Type Natriuretic Peptide Is a Critical Regulator of Angiogenesis and Vascular Remodeling.

BACKGROUND: Angiogenesis and vascular remodeling are complementary, innate responses to ischemic cardiovascular events, including peripheral artery disease and myocardial infarction, which restore tissue blood supply and oxygenation; the endothelium plays a critical function in these intrinsic protective processes. C-type natriuretic peptide (CNP) is a fundamental endothelial signaling species that coordinates vascular homeostasis. Herein, we sought to delineate a central role for CNP in angiogenesis and vascular remodeling in response to ischemia. METHODS: The in vitro angiogenic capacity of CNP was examined in pulmonary microvascular endothelial cells and aortic rings isolated from wild-type, endothelium-specific CNP-/-, global natriuretic peptide receptor (NPR)-B-/- and NPR-C-/- animals, and human umbilical vein endothelial cells. These studies were complemented by in vivo investigation of neovascularization and vascular remodeling after ischemia or vessel injury, and CNP/NPR-C expression and localization in tissue from patients with peripheral artery disease. RESULTS: Clinical vascular ischemia is associated with reduced levels of CNP and its cognate NPR-C. Moreover, genetic or pharmacological inhibition of CNP and NPR-C, but not NPR-B, reduces the angiogenic potential of pulmonary microvascular endothelial cells, human umbilical vein endothelial cells, and isolated vessels ex vivo. Angiogenesis and remodeling are impaired in vivo in endothelium-specific CNP-/- and NPR-C-/-, but not NPR-B-/-, mice; the detrimental phenotype caused by genetic deletion of endothelial CNP, but not NPR-C, can be rescued by pharmacological administration of CNP. The proangiogenic effect of CNP/NPR-C is dependent on activation of Gi, ERK1/2, and phosphoinositide 3-kinase γ/Akt at a molecular level. CONCLUSIONS: These data define a central (patho)physiological role for CNP in angiogenesis and vascular remodeling in response to ischemia and provide the rationale for pharmacological activation of NPR-C as an innovative approach to treating peripheral artery disease and ischemic cardiovascular disorders.

Insights into myofibroblasts and their activation in scleroderma: opportunities for therapy?

PURPOSE OF REVIEW: The persistence of myofibroblasts is a key feature of fibrosis and in fibrotic diseases including scleroderma. This review evaluates the emerging concepts of the origins and cell populations that contribute to myofibroblasts and the molecular mechanisms that govern phenotypic conversion and that highlight opportunities for new interventional treatments in scleroderma. RECENT FINDINGS: Studies have defined heterogeneity in fibroblast-like cells that can develop into myofibroblast in normal wound healing, scarring and fibrosis. Characterizing these distinct cell populations and their behaviour has been a key focus. In addition, the overarching impact of epigenetic regulation of genes associated with inflammatory responses, cell signalling and cell communication and the extracellular matrix (ECM) has provided important insights into the formation of myofibroblast and their function. Important new studies include investigations into the relationship between inflammation and myofibroblast production and further evidence has been gathered that reveal the importance of ECM microenvironment, biomechanical sensing and mechanotransduction. SUMMARY: This review highlights our current understanding and outlines the increasing complexity of the biological processes that leads to the appearance of the myofibroblast in normal functions and in diseased tissues. We also focus on areas of special interest in particular, studies that have therapeutic potential in fibrosis and scleroderma.

Changes in macrophage transcriptome associate with systemic sclerosis and mediate GSDMA contribution to disease risk.

OBJECTIVES: Several common and rare risk variants have been reported for systemic sclerosis (SSc), but the effector cell(s) mediating the function of these genetic variants remains to be elucidated. While innate immune cells have been proposed as the critical targets to interfere with the disease process underlying SSc, no studies have comprehensively established their effector role. Here we investigated the contribution of monocyte-derived macrophages (MDMs) in mediating genetic susceptibility to SSc. METHODS: We carried out RNA sequencing and genome-wide genotyping in MDMs from 57 patients with SSc and 15 controls. Our differential expression and expression quantitative trait locus (eQTL) analysis in SSc was further integrated with epigenetic, expression and eQTL data from skin, monocytes, neutrophils and lymphocytes. RESULTS: We identified 602 genes upregulated and downregulated in SSc macrophages that were significantly enriched for genes previously implicated in SSc susceptibility (P=5×10-4), and 270 cis-regulated genes in MDMs. Among these, GSDMA was reported to carry an SSc risk variant (rs3894194) regulating expression of neighbouring genes in blood. We show that GSDMA is upregulated in SSc MDMs (P=8.4×10-4) but not in the skin, and is a significant eQTL in SSc macrophages and lipopolysaccharide/interferon gamma (IFNγ)-stimulated monocytes. Furthermore, we identify an SSc macrophage transcriptome signature characterised by upregulation of glycolysis, hypoxia and mTOR signalling and a downregulation of IFNγ response pathways. CONCLUSIONS: Our data further establish the link between macrophages and SSc, and suggest that the contribution of the rs3894194 risk variant to SSc susceptibility can be mediated by GSDMA expression in macrophages.

Molecular Basis for Dysregulated Activation of NKX2-5 in the Vascular Remodeling of Systemic Sclerosis.

OBJECTIVE: NKX2-5 is a homeobox transcription factor that is required for the formation of the heart and vessels during development, with significant postnatal down-regulation and reactivation in disease states, characterized by vascular remodeling. The purpose of this study was to investigate mechanisms that activate NKX2-5 expression in diseased vessels, such as systemic sclerosis (scleroderma; SSc)-associated pulmonary hypertension (PH), and to identify genetic variability that potentially underlies susceptibility to specific vascular complications. METHODS: We explored NKX2-5 expression in biopsy samples from patients with SSc-associated PH and in pulmonary artery smooth muscle cells (PASMCs) from patients with scleroderma. Disease-associated putative functional single-nucleotide polymorphisms (SNPs) at the NKX2-5 locus were cloned and studied in reporter gene assays. SNP function was further examined through protein-DNA binding assays, chromatin immunoprecipitation assays, and RNA silencing analyses. RESULTS: Increased NKX2-5 expression in biopsy samples from patients with SSc-associated PH was localized to remodeled vessels and PASMCs. Meta-analysis of 2 independent scleroderma cohorts revealed an association of rs3131917 with scleroderma (P = 0.029). We demonstrated that disease-associated SNPs are located in a novel functional enhancer, which increases NKX2-5 transcriptional activity through the binding of GATA-6, c-Jun, and myocyte-specific enhancer factor 2C. We also characterized an activator/coactivator transcription-enhancer factor domain 1 (TEAD1)/Yes-associated protein 1 (YAP1) complex, which was bound at rs3095870, another functional SNP, with TEAD1 binding the risk allele and activating the transcription of NKX2-5. CONCLUSION: NKX2-5 is genetically associated with scleroderma, pulmonary hypertension, and fibrosis. Functional evidence revealed a regulatory mechanism that results in NKX2-5 transcriptional activation in PASMCs through the interaction of an upstream promoter and a novel downstream enhancer. This mechanism can act as a model for NKX2-5 activation in cardiovascular disease characterized by vascular remodeling.

STAT3 controls COL1A2 enhancer activation cooperatively with JunB, regulates type I collagen synthesis posttranscriptionally, and is essential for lung myofibroblast differentiation.

Fibroblast differentiation is a key cellular process that underlies the process of fibrosis, a deadly complication of fibrotic diseases like scleroderma (SSc). This transition coincides with the overproduction of collagen type I (COL1) and other extracellular matrix proteins. High-level expression of the collagen type 1α2 subunit (COL1A2), requires the engagement of a far-upstream enhancer, whose activation is strongly dependent on the AP1 factor JunB. We now report that STAT3 also binds the COL1A2 enhancer and is essential for RNA polymerase recruitment, without affecting JunB binding. STAT3 is required for the increased COL1A2 expression observed in myofibroblasts. We also report that TGFß partially activates STAT3 and show that inhibiting STAT3 potently blocks TGFß signaling, matrix remodeling, and TGFß-induced myofibroblast differentiation. Activation of STAT3 with IL6 transsignaling alone, however, only increased COL1A2 protein expression, leaving COL1A2 mRNA levels unchanged. Our results suggest that activated STAT3 is not the limiting factor for collagen enhancer activation in human lung fibroblasts. Yet, a certain threshold level of STAT3 activity is essential to support activation of the COL1A2 enhancer and TGFß signaling in fibroblasts. We propose that STAT3 operates at the posttranscriptional as well as the transcriptional level.

Association of Defective Regulation of Autoreactive Interleukin-6-Producing Transitional B Lymphocytes With Disease in Patients With Systemic Sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) has the highest case-specific mortality of any rheumatic disease, and no effective therapy is available. A clear manifestation of SSc is the presence of autoantibodies. However, the origin of autoantibody-producing B lymphocytes, their mechanisms of activation and autoantibody production, and their role remain unclear. This study was undertaken to identify mechanisms that contribute to pathogenic B cell generation and involvement in SSc and to assess the altered distribution and function of B cells in SSc patients. METHODS: Multicolor flow cytometry was performed to determine B cell subset distribution, cytokine production, and tolerance induction in SSc patients and healthy controls. Cytokine production following stimulation of the cells ex vivo was determined by multiplex assay. RESULTS: A range of defects in B lymphocyte tolerance and cytokine production in SSc were noted. There was evidence of altered distribution of transitional B cell subsets, increased production of interleukin-6 (IL-6) and IL-8, and defective tolerance induction in SSc B cells. In addition, B cells from SSc patients had a reduced ability to produce IL-10 when stimulated through innate immune pathways. In contrast to healthy individuals, tolerance checkpoints in SSc patients failed to suppress the emergence of B cells that produce autoantibodies with specificity to the Scl-70 antigen, which is strongly associated with SSc. These defects were paralleled by altered intracellular signaling and apoptosis following B cell receptor engagement. CONCLUSION: Our findings provide new insights into mechanisms underlying defective B lymphocyte responses in patients with SSc and their contribution to disease.

Searching Novel Therapeutic Targets for Scleroderma: P2X7-Receptor Is Up-regulated and Promotes a Fibrogenic Phenotype in Systemic Sclerosis Fibroblasts.

Objectives: Systemic sclerosis (SSc) is a connective tissue disorder presenting fibrosis of the skin and internal organs, for which no effective treatments are currently available. Increasing evidence indicates that the P2X7 receptor (P2X7R), a nucleotide-gated ionotropic channel primarily involved in the inflammatory response, may also have a key role in the development of tissue fibrosis in different body districts. This study was aimed at investigating P2X7R expression and function in promoting a fibrogenic phenotype in dermal fibroblasts from SSc patients, also analyzing putative underlying mechanistic pathways. Methods: Fibroblasts were isolated by skin biopsy from 9 SSc patients and 8 healthy controls. P2X7R expression, and function (cytosolic free Ca2+ fluxes, α-smooth muscle actin [α-SMA] expression, cell migration, and collagen release) were studied. Moreover, the role of cytokine (interleukin-1ß, interleukin-6) and connective tissue growth factor (CTGF) production, and extracellular signal-regulated kinases (ERK) activation in mediating P2X7R-dependent pro-fibrotic effects in SSc fibroblasts was evaluated. Results: P2X7R expression and Ca2+ permeability induced by the selective P2X7R agonist 2'-3'-O-(4-benzoylbenzoyl)ATP (BzATP) were markedly higher in SSc than control fibroblasts. Moreover, increased αSMA expression, cell migration, CTGF, and collagen release were observed in lipopolysaccharides-primed SSc fibroblasts after BzATP stimulation. While P2X7-induced cytokine changes did not affect collagen production, it was completely abrogated by inhibition of the ERK pathway. Conclusion: In SSc fibroblasts, P2X7R is overexpressed and its stimulation induces Ca2+-signaling activation and a fibrogenic phenotype characterized by increased migration and collagen production. These data point to the P2X7R as a potential, novel therapeutic target for controlling exaggerated collagen deposition and tissue fibrosis in patients with SSc.

Limited cutaneous systemic sclerosis skin demonstrates distinct molecular subsets separated by a cardiovascular development gene expression signature.

BACKGROUND: Systemic sclerosis (SSc; scleroderma) is an uncommon autoimmune rheumatic disease characterised by autoimmunity, vasculopathy and fibrosis. Gene expression profiling distinguishes scleroderma from normal skin, and can detect different subsets of disease, with potential to identify prognostic biomarkers of organ involvement or response to therapy. We have performed gene expression profiling in skin samples from patients with limited cutaneous SSc (lcSSc). METHODS: Total RNA was extracted from clinically uninvolved skin biopsies of 15 patients with lcSSc and 8 healthy controls (HC). Gene expression profiling was performed on a DNA oligonucleotide microarray chip. Differentially expressed genes (DEG) were identified using significance analysis of microarrays (SAM). Functional enrichment analysis of gene signatures was done via g:Profiler. RESULTS: There were 218 DEG between lcSSc and HC samples (false discovery rate <10%): 181/218 DEG were upregulated in lcSSc samples. Hierarchical clustering of DEG suggested the presence of two separate groups of lcSSc samples: "limited 1" and "limited 2". The limited-1 group (13 samples, 10 unique patients) showed upregulation of genes involved in cell adhesion, cardiovascular system (CVS) development, extracellular matrix and immune and inflammatory response. The CVS development signature was of particular interest as its genes showed very strong enrichment in response to wounding, response to transforming growth factor (TGF)-ß and kinase cascade. Neither limited-2 samples (six samples, five unique patients) nor HC samples showed functional enrichment. There were no significant differences in demographic or clinical parameters between these two groups. These results were confirmed using a second independent cohort. CONCLUSIONS: Our study suggests the presence of molecular subsets in lcSSc based on gene expression profiling of biopsies from uninvolved skin. This may reflect important differences in pathogenesis within these patient groups. We identify differential expression of a subset of genes that relate to CVS and are enriched in fibrotic signalling. This may shed light on mechanisms of vascular disease in SSc. The enrichment in profibrotic profile suggests that dysregulated gene expression may contribute to vasculopathy and fibrosis in different disease subsets.