Fibrosis In Systemic Sclerosis Research Articles

Silica's silent threat: Contributing to skin fibrosis in systemic sclerosis by targeting the HDAC4/Smad2/3 pathway

Nowadays, silica products are widely used in daily life, especially in skin applications, which inevitably increases the risk of silica exposure in general population. However, inadequate awareness of silica's potential hazards and lack of self-protection are of concern. Systemic sclerosis (SSc) is characterized by progressive tissue fibrosis under environmental and genetic interactions. Silica exposure is considered an important causative factor for SSc, but its pathogenesis remains unclear. Within this study, we showed that lower doses of silica significantly promoted the proliferation, migration, and activation of human skin fibroblasts (HSFs) within 24 h. Silica injected subcutaneously into mice induced and exacerbated skin fibrosis. Notably, silica increased histone deacetylase-4 (HDAC4) expression by inducing its DNA hypomethylation in normal HSFs. The elevated HDAC4 expression was also confirmed in SSc HSFs. Furthermore, HDAC4 was positively correlated with Smad2/3 phosphorylation and COL1, α-SMA, and CTGF expression. The HDAC4 inhibitor LMK235 mitigated silica-induced upregulation of these factors and alleviated skin fibrosis in SSc mice. Taken together, silica induces and exacerbates skin fibrosis in SSc patients by targeting the HDAC4/Smad2/3 pathway. Our findings provide new insights for evaluating the health hazards of silica exposure and identify HDAC4 as a potential interventional target for silica-induced SSc skin fibrosis.

P27 Chloride intracellular channel 4 is a global regulator of type 1 interferon signalling in systemic sclerosis skin

Abstract Introduction and aims Systemic sclerosis (SSc) is an autoimmune disease in which an immune-related injury induces fibrosis of the skin and can progress to affect the internal organs in the most serve cases. Aberrant type 1 interferon (IFN) signalling in the keratinocytes plays a major role in SSc disease progression. We have previously shown the chloride intracellular channel 4 (CLIC)4 is upregulated in SSc skin fibroblasts and plays an important role in SSc fibrosis by enhancing transforming growth factor-β signalling. In this study, we investigated the role of CLIC4 in SSc keratinocyte biology. Methods Skin biopsies from patients with SSc (N = 6) and healthy controls (HCs) (N = 6) were analysed by immunohistochemistry for the expression of CLIC4 and phosphorylated signal transducer and activator of transcription (STAT)1. The skin keratinocyte cell line HaCaTs was stimulated with a range of type 1 IFN signalling agonists including POLY I:C, POLY dA:dT, ODN 2216 and IFN-α. CLIC4 was inhibited with the chloride channel inhibitors NPPB and IAA-94 or small interfering RNA specific to CLIC4. Conditioned media from HC or SSc dermal fibroblasts was employed for indirect coculture of HaCaTs. Results Skin biopsies from SSc showed high levels of CLIC4 in SSc skin fibroblasts, keratinocytes and endothelial cells compared with HC. Indirect coculture of HaCaTs with SSc fibroblast media induced CLIC4 expression in the HaCaTs. The increased CLIC4 expression played an important role in type 1 IFN signalling in keratinocytes as inhibition of CLIC4 blocked Toll-like receptor (TLR)3, TLR9 and cGAS-mediated activation of the type 1 IFN signalling pathway transcription factor STAT1. Additionally, inhibition of CLIC4 prevented SSc fibroblast media from inducing a type 1 IFN response in keratinocytes. Conclusions The data presented in this study suggests that CLIC4 is a global regulator of the type 1 IFN signalling cascade in SSc epithelial cells.

EphB2 Receptor Promotes Dermal Fibrosis in Systemic Sclerosis.

Erythropoietin-producing hepatocellular (Eph)/Ephrin cell-cell signaling is emerging as a key player in tissue fibrogenesis. The aim of this study was to test the hypothesis that the receptor tyrosine kinase EphB2 mediates dermal fibrosis in systemic sclerosis (SSc). We assessed normal and SSc human skin biopsies for EphB2 expression. The in vivo role of EphB2 in skin fibrosis was investigated by subjecting EphB2-knockout mice to both bleomycin-induced and tight skin (Tsk1/+) genetic mouse models of skin fibrosis. EphB2 kinase-dead and overactive point mutant mice were used to evaluate the role of EphB2 forward signaling in bleomycin-induced dermal fibrosis. In vitro studies were performed on dermal fibroblasts from patients with SSc and healthy controls, which was followed by in vivo analysis of fibroblast-specific Ephb2-deficient mice. Expression of EphB2 is up-regulated in SSc skin tissue and explanted SSc dermal fibroblasts compared with healthy controls. EphB2 expression is elevated in two animal models of dermal fibrosis. In mice, EphB2 drives dermal fibrosis in both the bleomycin and the Tsk1/+ models of skin fibrosis. EphB2 forward signaling is a critical mediator of dermal fibrosis. Transforming growth factor-β (TGF-β) cytokines up-regulate EphB2 in dermal fibroblasts via noncanonical TGF-β/mother against decapentaplegic signaling, and silencing EPHB2 in human dermal fibroblasts is sufficient to dampen TGF-β-induced fibroblast-to-myofibroblast differentiation. Moreover, mice with fibroblast-specific deletion of EphB2 showed impaired fibroblast-to-myofibroblast differentiation and reduced skin fibrosis upon bleomycin challenge. Our data implicate TGF-β regulation of EphB2 overexpression and kinase-mediated forward signaling in the development of dermal fibrosis in SSc. EphB2 thus represents a potential new therapeutic target for SSc.

Impaired LAIR-1-mediated immune control due to collagen degradation in fibrosis

Tissue repair is disturbed in fibrotic diseases like systemic sclerosis (SSc), where the deposition of large amounts of extracellular matrix components such as collagen interferes with organ function. LAIR-1 is an inhibitory collagen receptor highly expressed on tissue immune cells. We questioned whether in SSc, impaired LAIR-1-collagen interaction is contributing to the ongoing inflammation and fibrosis.We found that SSc patients do not have an intrinsic defect in LAIR-1 expression or function. Instead, fibroblasts from healthy controls and SSc patients stimulated by soluble factors that drive inflammation and fibrosis in SSc deposit disorganized collagen products in vitro, which are dysfunctional LAIR-1 ligands. This is dependent of matrix metalloproteinases and platelet-derived growth factor receptor signaling.In support of a non-redundant role of LAIR-1 in the control of fibrosis, we found that LAIR-1-deficient mice have increased skin fibrosis in response to repeated injury and in the bleomycin mouse model for SSc. Thus, LAIR-1 represents an essential control mechanism for tissue repair. In fibrotic disease, excessive collagen degradation may lead to a disturbed feedback loop. The presence of functional LAIR-1 in patients provides a therapeutic opportunity to reactivate this intrinsic negative feedback mechanism in fibrotic diseases.

Application of blinatumomab, a bispecific anti-CD3/CD19 T-cell engager, in treating severe systemic sclerosis: A case study

Systemic sclerosis, a severe inflammatory autoimmune disease, shares a common thread with cancer through the underlying mechanism of inflammation. This inflammatory milieu not only drives the immune dysregulation characteristic of autoimmune diseases but also plays a pivotal role in the pathogenesis of cancer. Among the cellular components involved, B cells have emerged as key players in hematologic tumor and autoimmune disease, contributing to immune dysregulation and persistent tissue fibrosis in systemic sclerosis, as well as tumor progression and immune evasion in cancer. Consequently, novel therapeutic strategies targeting B cells hold promise in both conditions. Recent exploration of CD19 CAR T cells in severe systemic sclerosis patients has shown great potential, but also introduced possible risks and drawbacks associated with viral vectors, prolonged CAR T cell persistence, lengthy production timelines, high costs, and the necessity of conditioning patients with organotoxic and fertility-damaging chemotherapy. Given these challenges, alternative CD19-depleting approaches are of high interest for managing severe systemic autoimmune diseases. Here, we present the pioneering use of blinatumomab, a bispecific anti-CD3/anti-CD19 T cell engager in a patient with progressive, severe systemic sclerosis, offering a promising alternative for such challenging cases.

MicroRNA-21a-5p inhibition alleviates systemic sclerosis by targeting STAT3 signaling

BackgroundMicroRNA (miRNA)-21-5p participates in various biological processes, including cancer and autoimmune diseases. However, its role in the development of fibrosis in the in vivo model of systemic sclerosis (SSc) has not been reported. This study investigated the effects of miRNA-21a-5p overexpression and inhibition on SSc fibrosis using a bleomycin-induced SSc mouse model.MethodsA murine SSc model was induced by subcutaneously injecting 100 μg bleomycin dissolved in 0.9% NaCl into C57BL/6 mice daily for 5 weeks. On days 14, 21, and 28 from the start of bleomycin injection, 100 μg pre-miRNA-21a-5p or anti-miRNA-21a-5p in 1 mL saline was hydrodynamically injected into the mice. Fibrosis analysis was conducted in lung and skin tissues of SSc mice using hematoxylin and eosin as well as Masson’s trichrome staining. Immunohistochemistry was used to examine the expression of inflammatory cytokines, phosphorylated signal transducer and activator of transcription-3 (STAT3) at Y705 or S727, and phosphatase and tensin homologue deleted on chromosome-10 (PTEN) in skin tissues of SSc mice.ResultsMiRNA-21a-5p overexpression promoted lung fibrosis in bleomycin-induced SSc mice, inducing infiltration of cells expressing TNF-α, IL-1β, IL-6, or IL-17, along with STAT3 phosphorylated cells in the lesional skin. Conversely, anti-miRNA-21a-5p injection improved fibrosis in the lung and skin tissues of SSc mice, reducing the infiltration of cells secreting inflammatory cytokines in the skin tissue. In particular, it decreased STAT3-phosphorylated cell infiltration at Y705 and increased the infiltration of PTEN-expressing cells in the skin tissue of SSc mice.ConclusionMiRNA-21a-5p promotes fibrosis in an in vivo murine SSc model, suggesting that its inhibition may be a therapeutic strategy for improving fibrosis in SSc.

Attenuation of fibroblast activation and fibrosis by adropin in systemic sclerosis.

Fibrotic diseases impose a major socioeconomic challenge on modern societies and have limited treatment options. Adropin, a peptide hormone encoded by the energy homeostasis-associated (ENHO) gene, is implicated in metabolism and vascular homeostasis, but its role in the pathogenesis of fibrosis remains enigmatic. Here, we used machine learning approaches in combination with functional in vitro and in vivo experiments to characterize adropin as a potential regulator involved in fibroblast activation and tissue fibrosis in systemic sclerosis (SSc). We demonstrated consistent down-regulation of adropin/ENHO in skin across multiple cohorts of patients with SSc. The prototypical profibrotic cytokine TGFβ reduced adropin/ENHO expression in a JNK-dependent manner. Restoration of adropin signaling by therapeutic application of bioactive adropin34-76 peptides in turn inhibited TGFβ-induced fibroblast activation and fibrotic tissue remodeling in primary human dermal fibroblasts, three-dimensional full-thickness skin equivalents, mouse models of bleomycin-induced pulmonary fibrosis and sclerodermatous chronic graft-versus-host-disease (sclGvHD), and precision-cut human skin slices. Knockdown of GPR19, an adropin receptor, abrogated the antifibrotic effects of adropin in fibroblasts. RNA-seq demonstrated that the antifibrotic effects of adropin34-76 were functionally linked to deactivation of GLI1-dependent profibrotic transcriptional networks, which was experimentally confirmed in vitro, in vivo, and ex vivo using cultured human dermal fibroblasts, a sclGvHD mouse model, and precision-cut human skin slices. ChIP-seq confirmed adropin34-76-induced changes in TGFβ/GLI1 signaling. Our study characterizes the TGFβ-induced down-regulation of adropin/ENHO expression as a potential pathomechanism of SSc as a prototypical systemic fibrotic disease that unleashes uncontrolled activation of profibrotic GLI1 signaling.

Characterization of Vascular Niche in Systemic Sclerosis by Spatial Proteomics.

Systemic sclerosis (SSc) is a connective tissue disease that can serve as a model to study vascular changes in response to inflammation, autoimmunity, and fibrotic remodeling. Although microvascular changes are the earliest histopathologic manifestation of SSc, the vascular pathophysiology remains poorly understood. We applied spatial proteomic approaches to deconvolute the heterogeneity of vascular cells at the single-cell level in situ and characterize cellular alterations of the vascular niches of patients with SSc. Skin biopsies of patients with SSc and control individuals were analyzed by imaging mass cytometry, yielding a total of 90 755 cells including 2987 endothelial cells and 4096 immune cells. We identified 7 different subpopulations of blood vascular endothelial cells (VECs), 2 subpopulations of lymphatic endothelial cells, and 3 subpopulations of pericytes. A novel population of CD34+;αSMA+ (α-smooth muscle actin);CD31+ VECs was more common in SSc, whereas endothelial precursor cells were decreased. Co-detection by indexing and tyramide signal amplification confirmed these findings. The microenvironment of CD34+;αSMA+;CD31+ VECs was enriched for immune cells and myofibroblasts, and CD34+;αSMA+;CD31+ VECs expressed markers of endothelial-to-mesenchymal transition. The density of CD34+;αSMA+;CD31+ VECs was associated with clinical progression of fibrosis in SSc. Using spatial proteomics, we unraveled the heterogeneity of vascular cells in control individuals and patients with SSc. We identified CD34+;αSMA+;CD31+ VECs as a novel endothelial cell population that is increased in patients with SSc, expresses markers for endothelial-to-mesenchymal transition, and is located in close proximity to immune cells and myofibroblasts. CD34+;αSMA+;CD31+ VEC counts were associated with clinical outcomes of progressive fibrotic remodeling, thus providing a novel cellular correlate for the crosstalk of vasculopathy and fibrosis.

SLC39A7 upregulation links to skin fibrosis in systemic sclerosis via TGF-β/SMAD pathway.

Systemic sclerosis (SSc) is a multisystem connective tissue disease. Skin fibrosis, the hallmark of this disease, is defined as the excess deposition and accumulation of extracellular matrix, mainly type 1 collagen, in the dermis. SLC39A7 is an intracellular zinc transporter that plays a unique role in connective tissue formation. Therefore, we investigated the expression and role of SLC39A7 in SSc. Using immunohistochemical staining we demonstrated the overexpression of SLC39A7 in the skin of SSc patients. Quantitative real-time PCR and western blot data analysis showed that both SLC39A7 mRNA and protein levels were significantly upregulated in dermal fibroblasts from SSc patients compared to healthy controls. We used the shRNA lentiviral particle transduction system to stably knockdown the expression of SLC39A7 in SSc fibroblasts. The results showed that knockdown of SLC39A7 suppressed the production of type 1 collagen. These findings provide evidence that SLC39A7 is involved in the pathogenesis of SSc and that SLC39A7 plays a positive role in its progression.

Immunogenomic Exploration of Cutaneous Manifestations and Therapeutic Targets in Systemic SclerosisVivian Li DO,*

This analysis of current literature explores specific immunogenomic signatures underlying cutaneous manifestations in systemic sclerosis (SSc), a complex autoimmune disorder characterized by fibrosis, vasculopathy, and immune dysregulation. By employing integrated transcriptomic and epigenomic analyses of skin biopsies obtained from SSc patients presenting varying degrees of cutaneous involvement, researchers aim to discern dysregulated immune pathways, gene expression signatures, and epigenetic modifications correlated with disease progression and severity. Additionally, investigating the therapeutic potential of immune-modulating agents, including JAK inhibitors and immune checkpoint inhibitors, in mitigating skin fibrosis and inflammation in SSc may unlock novel avenues for personalized treatment strategies tailored to the immunogenomic profile of individual patients. Future research should focus on validating identified biomarkers, exploring the mechanistic basis of immunogenomic alterations, and translating these findings into clinical practice to optimize therapeutic outcomes and enhance the management of cutaneous manifestations in SSc.

Characteristics and disease course of untreated patients with interstitial lung disease associated with systemic sclerosis in a real-life two-centre cohort

BackgroundInterstitial lung disease (ILD) is the leading cause of death in systemic sclerosis (SSc). According to expert statements, not all SSc-ILD patients require pharmacological therapy.ObjectivesTo describe disease characteristics and disease...

Imbalance of TH17/TREG cells in Tunisian patients with systemic sclerosis

Fibrosis is a pathological manifestation in which connective tissue replaces normal one. It can affect many tissues from the skin to internal organs such as the lungs. Manifestations of pulmonary involvement can be pulmonary arterial hypertension or pulmonary fibrosis. The latter one is currently the leading cause of death in various autoimmune diseases, including systemic sclerosis.Our study group consists of 50 patients with systemic sclerosis: 24 with limited cutaneous form and 26 with diffuse cutaneous form. This cohort was compared to 50 healthy controls (age and sex matched); our aim is to explore the distribution of TH17 cells (TH17) as well as regulatory T cells (TREG) and study their correlation with the disease's progress. Our results show an increase for IL17A in patients compared to controls and that this increase is correlated with a specific clinical involvement: Pulmonary fibrosis. This correlation suggests a crucial role of IL17A in fibrosis especially in systemic sclerosis. In addition, we have shown that the percentages of TH17 cells are higher in patients; however, the percentages of TREG cells are similar between patients and controls. A study of TREG cell activity showed that TREG lost suppressive activity by inactivating the FOXP3 transcription factor. This proves that despite their presence, TREG does not adequately carry out their regulatory activity. Finally, we analyzed the correlation between TH17/TREG and clinical damage; the results show a positive correlation with pulmonary involvement proving the role of TH17/TREG balance in induced fibrosis in systemic sclerosis. No significative difference was observed, for all the parameters, between the two different forms of the disease.In conclusion, the results associated with the TH17/TREG scale and their correlations with fibrosis in systemic sclerosis open a way for new tools to manage this autoimmune disease, which up to today has neither treatment nor accurate diagnosis.

Digital Ulcers and Ventricular Arrhythmias as Red Flags to Predict Replacement Myocardial Fibrosis in Systemic Sclerosis.

Cardiac involvement in systemic sclerosis (SSc) affects the prognosis of the disease. Echocardiography is the first line imaging tool to detect cardiac involvement, but it is not able to routinely detect myocardial fibrosis. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) is the gold standard for replacement myocardial fibrosis assessment, but its availability is currently limited. We aimed to assess the clinical and instrumental parameters that would be useful for predicting the presence of LGE-CMR, to achieve a better selection of patients with SSc that could benefit from third-level CMR imaging. 344 SSc patients underwent a comprehensive echocardiogram and LGE-CMR on the same day; for 189 patients, a 24 h ECG Holter monitoring was available. CMR showed non-junctional replacement myocardial fibrosis via LGE in 25.1% patients. A history of digital ulcers (OR 2.188; 95% C.I. 1.069-4.481) and ventricular arrhythmias at ECG Holter monitoring (OR 3.086; 95% C.I. 1.191-7.998) were independent predictors of replacement myocardial fibrosis. CMR can detect patterns of clinical and subclinical cardiac involvement, which are frequent in SSc. A history of digital ulcers and evidence of ventricular arrhythmias at ECG Holter monitoring are red flags for the presence of replacement myocardial fibrosis in CMR. The association between digital ulcers and myocardial fibrosis suggests that a similar pathological substrate of abnormal vascular function may underlie peripheral vascular and cardiac complications.

Heavy-chain antibody targeting of CD38 NAD+ hydrolase ectoenzyme to prevent fibrosis in multiple organs

The functionally pleiotropic ectoenzyme CD38 is a glycohydrolase widely expressed on immune and non-hematopoietic cells. By converting NAD+ to ADP-ribose and nicotinamide, CD38 governs organismal NAD+ homeostasis and the activity of NAD+-dependent cellular enzymes. CD38 has emerged as a major driver of age-related NAD+ decline underlying adverse metabolic states, frailty and reduced health span. CD38 is upregulated in systemic sclerosis (SSc), a chronic disease characterized by fibrosis in multiple organs. We sought to test the hypothesis that inhibition of the CD38 ecto-enzymatic activity using a heavy-chain monoclonal antibody Ab68 will, via augmenting organismal NAD+, prevent fibrosis in a mouse model of SSc characterized by NAD+ depletion. Here we show that treatment of mice with a non-cytotoxic heavy-chain antibody that selectively inhibits CD38 ectoenzyme resulted in NAD+ boosting that was associated with significant protection from fibrosis in multiple organs. These findings suggest that targeted inhibition of CD38 ecto-enzymatic activity could be a potential pharmacological approach for SSc fibrosis treatment.

Xanthohumol attenuates collagen synthesis in scleroderma skin fibroblasts by ROS/Nrf2/TGFβ1/Smad3 pathway

Skin fibrosis, the most obvious clinical manifestation of systemic sclerosis (SSc), has a high unmet need for treatment. Xanthohumol (Xn) has been shown to have beneficial effects on fibrotic diseases, but its efficacy in SSc remains unreported. This study aims to elucidate the effects and mechanisms of Xn on collagen synthesis in SSc skin fibroblasts (SScF). We found increased collagen production in SScF cultured in vitro, accompanied by dysregulated levels of oxidative stress. Cell experiments showed that Xn inhibited cell proliferation and promoted apoptosis. In addition, Xn was shown for the first time to upregulate reactive oxygen species (ROS) and nuclear factor erythroid 2-related factor 2 (Nrf2)levels in SScF, and when combined with the ROS scavenger N-acetylcysteine (NAC), Nrf2 expression was decreased. Importantly, we demonstrated that Xn significantly attenuated collagen synthesis by blocking the fibrotic classical transforming growth factor beta 1 (TGFβ1)/Smad3 pathway, which interestingly was upregulated when combined with the Nrf2 inhibitor 385. Taken together, Xn suppressed the TGFβ1/Smad3 pathway to ameliorate collagen overproduction by promoting ROS-induced oxidative stress damage and activating Nrf2, suggesting that Xn administration may be an emerging therapeutic strategy for skin fibrosis in SSc.

Tanshinone IIA ameliorates the development of dermal fibrosis in systemic sclerosis.

We previously revealed the role of tanshinone IIA (TAN IIA) on endothelial cells and the impact of TAN IIA on the endothelial-to-mesenchymal transition in systemic sclerosis (SSc). In this study, we sought to further determine whether TAN IIA can directly act on the skin fibroblasts of scleroderma and look into its underlying anti-fibrotic mechanisms. Bleomycin was used to establish the SSc mouse model. After TAN IIA treatment, dermal thickness, type I collagen and hydroxyproline content were measured. Primary fibroblasts were acquired from SSc patients and cultured in vitro, and the effects of TAN IIA on proliferation, apoptosis and the cell cycle of fibroblasts were detected. In a bleomycin-induced SSc model, we discovered that TAN IIA significantly improved skin thickness and collagen deposition, demonstrating a potent anti-fibrotic action. TAN IIA inhibits the proliferation of skin fibroblasts derived from SSc patients by causing G2/M cell cycle arrest and promoting apoptosis. Additionally, TAN IIA downregulated extracellular matrix gene transcription and collagen protein expression in skin fibroblasts in a dose-gradient-dependent manner. Furthermore, we showed how TAN IIA can reduce the activation of the transforming growth factor-β (TGF-β)/Smad and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathways, which are important factors in SSc. In summary, these data suggest that TAN IIA can reduce SSc-related skin fibrosis by modulating the TGF-β/Smad and MAPK/ERK signalling pathways. More importantly, our results imply that TAN IIA can directly act on the skin fibroblasts of SSc, therefore, inhibiting fibrosis.

Antifibrotic effect of apremilast in systemic sclerosis dermal fibroblasts and bleomycin-induced mouse model

Phosphodiesterase (PDE) 4 inhibitors have been reported to suppress the progression of dermal fibrosis in patients with systemic sclerosis (SSc); however, the precise mechanisms remain to be elucidated. Therefore, we conducted experiments focusing on the antifibrotic and anti-inflammatory effects of apremilast using dermal fibroblasts derived from patients with SSc and an SSc mouse model. Dermal fibroblasts derived from healthy controls and patients with SSc were incubated with apremilast in the presence or absence of 10 ng/ml transforming growth factor (TGF)-β1 for the measurement of intracellular cAMP levels and evaluation of mRNA and protein expression. A bleomycin-induced dermal fibrosis mouse model was used to evaluate the inhibitory effects of apremilast on the progression of dermal fibrosis. Intracellular cAMP levels were significantly reduced in dermal fibroblasts derived from patients with SSc compared with those derived from healthy controls. Apremilast reduced the mRNA expression of profibrotic markers and the protein expression of type I collagen and Cellular Communication Network Factor 2 (CCN2) in dermal fibroblasts. Additionally, apremilast inhibited the progression of dermal fibrosis in mice, partly by acting on T cells. These results suggest that apremilast may be a potential candidate for treating dermal fibrosis in SSc.

Back to the future: targeting the extracellular matrix to treat systemic sclerosis.

Fibrosis is the excessive deposition of a stable extracellular matrix (ECM); fibrotic tissue is composed principally of highly crosslinked type I collagen and highly contractile myofibroblasts. Systemic sclerosis (SSc) is a multisystem autoimmune connective tissue disease characterized by skin and organ fibrosis. The fibrotic process has been recognized in SSc for >40 years, but drugs with demonstrable efficacy against SSc fibrosis in ameliorating the lung involvement have only recently been identified. Unfortunately, these treatments are ineffective at improving the skin score in patients with SSc. Previous clinical trials in SSc have largely focused on the cross-purposing of anti-inflammatory drugs and the use of immunosuppressive drugs from the transplantation field, which address inflammatory and/or autoimmune processes. Limited examination has taken place of specific anti-fibrotic agents developed through their ability to directly target the ECM in SSc by, for example, alleviating the persistent matrix stiffness and mechanotransduction that might be required for both the initiation and maintenance of fibrosis, including in SSc. However, because of the importance of the ECM in the SSc phenotype, attempts have now been made to identify drugs that specifically target the ECM, including some drugs that are currently under consideration for the treatment of cancer.

Dangui Huoxue Preparation (DHP) Ameliorates Skin Fibrosis, Inflammation, and Vasculopathy in the Bleomycin-Induced Murine Model of Systemic Sclerosis.

Systemic sclerosis (SSc) is an immune-mediated rheumatic disease that is characterized by fibrosis of the skin and internal organs and vasculopathy with poor prognosis. Dangui Huoxue Preparation (DHP) is a clinically effective traditional Chinese herbal formula for the treatment of SSc in the hospital. This study aims to investigate the therapeutic effects and underlying molecular mechanisms of DHP in the treatment of SSc. SSc mice models are induced by bleomycin (BLM). Tissues of DHP group, normal control group, and positive control drug Sanqi Tongshu Capsule (STC) group are collected for inflammation, fibrosis, and vasculopathy. Also, the human dermal fibroblasts (HDF) stimulated with TGF-β1 are analyzed for in vitro study. The expression levels of MCP-1, IFN-γ, IL-1β, IL-10, Fizz1, iNOS, and IL12p40, and the mRNA levels of Col1a1, Col1a2, Col3a1, and Col5a1 are significantly decreased in all DHP groups and STC group compare with those in the BLM group. The main drug of DHP inhibits the proliferation and migration of HDF, reduces Ctgf, Itgb3, Itgb5 expression, and also inhibits the Smad3 pathway. In conclusion, DHP can ameliorate SSc skin inflammation, fibrosis, and vasculopathy, possibly suppressing the TGF-β1/Smad3 signaling pathway through extracellular and intracellular mechanisms.

Role of Extracellular Vesicles in the Propagation of Lung Fibrosis in Systemic Sclerosis.

Systemic sclerosis (SSc) has the highest mortality rate among the rheumatic diseases, with lung fibrosis leading as the cause of death. A characteristic of severe SSc-related lung fibrosis is its progressive nature. Although most research has focused on the pathology of the fibrosis, the mechanism mediating the fibrotic spread remains unclear. We hypothesized that extracellular vesicle (EV) communication drives the propagation of SSc lung fibrosis. EVs were isolated from normal (NL) or SSc-derived human lungs and primary lung fibroblasts (pLFs). EVs were also isolated from human fibrotic lungs and pLFs induced experimentally with transforming growth factor-β (TGFβ). Fibrotic potency of EVs was assessed using functional assays in vitro and in vivo. Transmission electron microscopy, nanoparticle tracking analysis, real-time quantitative polymerase chain reaction(RT-qPCR), immunoblotting, and immunofluorescence were used to analyze EVs, their cargo, extracellular matrix (ECM) fractions, and conditioned media. SSc lungs and pLFs released significantly more EVs than NL lungs, and their EVs showed increased fibrotic content and activity. TGFβ-stimulated NL lung cores and pLFs increased packaging of fibrotic proteins, including fibronectin, collagens, and TGFβ, into released EVs. The EVs induced a fibrotic phenotype in recipient pLFs and in vivo in mouse lungs. Furthermore, EVs interacted with and contributed to the ECM. Finally, suppressing EV release in vivo reduced severity of murine lung fibrosis. Our findings highlight EV communication as a novel mechanism for propagation of SSc lung fibrosis. Identifying therapies that reduce EV release, activity, and/or fibrotic cargo in SSc patient lungs may be a viable therapeutic strategy to improve fibrosis.