Inhibition of MicroRNA-21 induces apoptosis in dermal fibroblasts of patients with systemic sclerosis

miR-143-3p boosts extracellular vesicles to improve the dermal fibrosis of localized scleroderma

Localized scleroderma (LoSc) is an autoimmune disease that features extensive fibrosis of the skin. Due to its severity and limited understanding, no effective treatments have been developed to date. Bone marrow mesenchymal stem cells (BMSCs) derived extracellular vesicles (EVs) have been demonstrated promising therapeutic effects on the LoSc mouse model in our previous study. However, identifying the targets and underlying mechanisms of EVs remains a significant challenge for therapeutic applications. miR-143-3p, a critical and abundant factor in BMSC-EVs identified through miRNA sequencing, mediates antifibrotic effects in a LoSc mouse model and is significantly lacking in the dermis of LoSc patients. This microRNA inhibits myofibroblast formation and collagen synthesis, contributing to the therapeutic effects of BMSC-EVs in the LoSc mouse model. Moreover, miR-143-3p-reinforced BMSC-EVs demonstrated enhanced therapeutic efficacy compared to normal BMSC-EVs, reducing dermal thickening, collagen deposition, fibroblast differentiation into myofibroblasts, and promoting skin tissue remodeling. IGF1R, highly expressed in the skin of LoSc, was identified as a potential target of miR-143-3p and was inhibited by miR-143-3p-reinforced EVs, thereby modulating the IGF1/IGF1R-AKT/MAPK pathway. In conclusion, miR-143-3p-enriched EVs could be a more efficient candidate for treating dermal fibrosis in LoSc.

Differential modulations of miRNAs in patients with systemic sclerosis-associated skeletal muscle loss

BACKGROUND

Systemic sclerosis (SSc) is an autoimmune disease characterized by sustained vascular inflammation and progressive skin and internal organs fibrosis. Up to 22 % of SSc patients may manifest skeletal muscle impairment, which predicts worse clinical outcomes, including increased mortality, however, pathogenesis is still largely unclear and could be associated with modulation of circulating microRNAs (miRNAs). Aims of the present study were to evaluate differentially modulated miRNAs in SSc patients and to evaluate their association with changes in body composition(s) and with the clinical course and type of the disease.

METHODS

Circulating levels of miRNAs were detected by RT-qPCR. ELISA assay was performed to measure the TGF-β1 protein. Muscularity (FFMI kg/m2) and phase angle (PhA, °) were estimated by Bioelectrical Impedance Analysis.

RESULTS

We enrolled 47 SSc patients and 21 controls (C). We observed downregulation of miR-15b (p = 0.024), -21 (p < 0.001), -29a (p < 0.001), -29b (p = 0.007) and -133a (p < 0.001), whereas miR-206 (p < 0.001) and -486 (p < 0.001) were upregulated in SSc vs C. In SSc, miR-29b negatively correlates with TGF-β1 (r = -0.303, p = 0.046). MiR-206 was downregulated vs high FFMI (p = 0.040) in SSc with low FFMI, and miR-15b positively correlates with PhA (r = 0.356, p = 0.014). MiR-15b and -486 were modulated in early vs late nailfold capillaroscopy stage (p = 0.028 and p = 0.045, respectively). MiR-133a was higher in SSc with Scl70 v ACA subset of autoantibodies (p = 0.002).

CONCLUSIONS

In SSc patients, differential modulations of miRNAs involved in muscularity occur. The data obtained suggest that mechanisms other than disease-related malnutrition might be responsible for SSc-associated skeletal muscle loss.

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

BACKGROUND

MicroRNA (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.

METHODS

A 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.

RESULTS

MiRNA-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.

CONCLUSION

MiRNA-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.

Fibroblast Activation Protein Alpha (FAPα) in Fibrosis: Beyond a Perspective Marker for Activated Stromal Cells?

The development of tissue fibrosis is a complex process involving the interaction of multiple cell types, which makes the search for antifibrotic agents rather challenging. So far, myofibroblasts have been considered the key cell type that mediated the development of fibrosis and thus was the main target for therapy. However, current strategies aimed at inhibiting myofibroblast function or eliminating them fail to demonstrate sufficient effectiveness in clinical practice. Therefore, today, there is an unmet need to search for more reliable cellular targets to contribute to fibrosis resolution or the inhibition of its progression. Activated stromal cells, capable of active proliferation and invasive growth into healthy tissue, appear to be such a target population due to their more accessible localization in the tissue and their high susceptibility to various regulatory signals. This subpopulation is marked by fibroblast activation protein alpha (FAPα). For a long time, FAPα was considered exclusively a marker of cancer-associated fibroblasts. However, accumulating data are emerging on the diverse functions of FAPα, which suggests that this protein is not only a marker but also plays an important role in fibrosis development and progression. This review aims to summarize the current data on the expression, regulation, and function of FAPα regarding fibrosis development and identify promising advances in the area.

The Roles of Noncoding RNAs in Systemic Sclerosis

Noncoding RNAs (ncRNAs) constitute more than 90% of the RNAs in the human genome. In the past decades, studies have changed our perception of ncRNAs from “junk” transcriptional products to functional regulatory molecules that mediate critical processes, including chromosomal modifications, mRNA splicing and stability, and translation, as well as key signaling pathways. Emerging evidence suggests that ncRNAs are abnormally expressed in not only cancer but also autoimmune diseases, such as systemic sclerosis (SSc), and may serve as novel biomarkers and therapeutic targets for the diagnosis and treatment of SSc. However, the functions and underlying mechanisms of ncRNAs in SSc remain incompletely understood. In this review, we discuss the current findings on the biogenetic processes and functions of ncRNAs, including microRNAs and long noncoding RNAs, as well as explore emerging ncRNA-based diagnostics and therapies for SSc.

Pathophysiology of systemic sclerosis (scleroderma)

Systemic sclerosis (scleroderma) is an autoimmune-triggered chronic fibrosing disease that affects the skin and many other organs. Its pathophysiology is complex and involves an early endothelial damage, an inflammatory infiltrate and a resulting fibrotic reaction. Based on a predisposing genetic background, an altered balance of the acquired and the innate immune system leads to the release of many cytokines and chemokines as well as autoantibodies, which induce the activation of fibroblasts with the formation of myofibroblasts and the deposition of a stiff and rigid connective tissue. A curative treatment is still not available but remarkable progress has been made in the management of organ complications. In addition, several breakthroughs in the pathophysiology have led to new therapeutic concepts. Based on these, many new compounds have been developed during the last years, which target these different pathways and offer specific therapeutic approaches.

Epigenetic Modifications in the Pathogenesis of Systemic Sclerosis

Systemic sclerosis is a rare chronic autoimmune disease, which mainly manifests as immune disorders, vascular damage, and progressive fibrosis. The etiology of SSc is complex and involves multiple factors. Both genetic and environmental factors are involved in its pathogenesis. As one of the molecular mechanisms of environmental factors, epigenetic regulation plays an important role in the occurrence and development of systemic sclerosis, which involves DNA methylation, histone modification and non-coding RNA regulation. This review summarizes research advances in epigenetics, including exosomes, lncRNA, and mentions possible biomarkers and therapeutic targets among them.

Novel Concepts in Systemic Sclerosis Pathogenesis: Role for miRNAs

Systemic sclerosis (SSc) is a rare connective tissue disease with heterogeneous clinical phenotypes. It is characterized by the pathogenic triad: microangiopathy, immune dysfunction, and fibrosis. Epigenetic mechanisms modulate gene expression without interfering with the DNA sequence. Epigenetic marks may be reversible and their differential response to external stimuli could explain the protean clinical manifestations of SSc while offering the opportunity of targeted drug development. Small, non-coding RNA sequences (miRNAs) have demonstrated complex interactions between vasculature, immune activation, and extracellular matrices. Distinct miRNA profiles were identified in SSc skin specimens and blood samples containing a wide variety of dysregulated miRNAs. Their target genes are mainly involved in profibrotic pathways, but new lines of evidence also confirm their participation in impaired angiogenesis and aberrant immune responses. Research approaches focusing on earlier stages of the disease and on differential miRNA expression in various tissues could bring novel insights into SSc pathogenesis and validate the clinical utility of miRNAs as biomarkers and therapeutic targets.

The Role of Pro-fibrotic Myofibroblasts in Systemic Sclerosis: from Origin to Therapeutic Targeting

Systemic sclerosis (SSc, scleroderma) is a complex connective tissue disorder characterized by multisystem clinical manifestations resulting from immune dysregulation/autoimmunity, vasculopathy and, most notably, progressive fibrosis of the skin and internal organs. In recent years, it has emerged that the main drivers of SSc-related tissue fibrosis are myofibroblasts, a type of mesenchymal cells with both the extracellular matrix-synthesizing features of fibroblasts and the cytoskeletal characteristics of contractile smooth muscle cells. The accumulation and persistent activation of pro-fibrotic myofibroblasts during SSc development and progression result into elevated mechanical stress and reduced matrix plasticity within the affected tissues and may be ascribed to a reduced susceptibility of these cells to pro-apoptotic stimuli, as well as their increased formation from tissue-resident fibroblasts or transition from different cell types. Given the crucial role of myofibroblasts in SSc pathogenesis, finding the way to inhibit myofibroblast differentiation and accumulation by targeting their formation, function and survival may represent an effective approach to hamper the fibrotic process or even halt or reverse established fibrosis. In this review, we discuss the role of myofibroblasts in SSc-related fibrosis, with a special focus on their cellular origin and the signaling pathways implicated in their formation and persistent activation. Furthermore, we provide an overview of potential therapeutic strategies targeting myofibroblasts that may be able to counteract fibrosis in this pathological condition.

MicroRNA-31 Can Positively Regulate the Proliferation, Differentiation and Migration of Keratinocytes

In the past decades, the key roles of most microRNA in dermatosis and skin development have been explored one after another. Among them, microRNA-31 (miR-31) has a prominent role in the regulation of keratinocytes. Numerous studies show that miR-31 can positively regulate the proliferation, differentiation and cell activity of keratinocytes via regulating the NF-κB, RAS/MAPK, Notch signaling pathways, and some cytokines. At present, the interaction between miR-31 and the NF-κB signaling pathway in keratinocytes is a hot research topic. The positive feedback loop formed by miR-31 and NF-κB signaling may bring new ideas for the prevention of psoriasis. The abnormal state of keratinocytes is usually the pathological basis of many skin and immune system diseases. Therefore, strengthening the ability to regulate keratinocytes may be a breakthrough for a variety of diseases. At the same time, miR-31's capacity to accelerate wound healing via positively regulating keratinocytes should be further investigated in the treatment of chronic ulcers and trauma.

Circulating miRNA-181b-5p, miRNA-223-3p, miRNA-210-3p, let 7i-5p, miRNA-21-5p and miRNA-29a-3p in patients with localized scleroderma as potential biomarkers

Localized scleroderma (LoSc) is a rare disease manifested by an inflammation and sclerosis of the skin. The latest studies focused on glycoprotein Krebs von den Lungen-6, surfactant protein-D, chemokine ligand 18 and dipeptidylpeptidase 4 as potential biomarkers of skin fibrosis in systemic scleroderma. Our study aimed to identify 6 miRNAs with elevated or decreased levels in 38 LoSc patients (31 females, 7 males) compared to healthy volunteers (HVs) and to correlate the selected miRNAs' serum levels with the severity and the clinical symptoms of LoSc and some laboratory parameters with the selected miRNAs' serum levels. The serum levels of miRNAs, i.e. miRNA-181b-5p, miRNA-223-3p, miRNA-21-5p, let 7i-5p, miRNA-29a-3p and miRNA-210-3p were significantly increased in the LoSc patients compared to the HVs. The level of let-7i increase in the female LoSc patients correlated negatively with BSA (r =  - 0.355, p = 0.049) and mLoSSI (r =  - 0.432, p = 0.015). Moreover, the female patients with inactive LoSc had significantly higher level of let-7i (2.68-fold on average) in comparison to those with active disease (p = 0.045). The exact role of those molecules has not been revealed in LoSc and a long-term longitudinal research is pivotal to confirm their prognostic value.

Ligamentum flavum fibrosis and hypertrophy: Molecular pathways, cellular mechanisms, and future directions

Hypertrophy of ligamentum flavum (LF), along with disk protrusion and facet joints degeneration, is associated with the development of lumbar spinal canal stenosis (LSCS). Of note, LF hypertrophy is deemed as an important cause of LSCS. Histologically, fibrosis is proved to be the main pathology of LF hypertrophy. Despite the numerous studies explored the mechanisms of LF fibrosis at the molecular and cellular levels, the exact mechanism remains unknown. It is suggested that pathophysiologic stimuli such as mechanical stress, aging, obesity, and some diseases are the causative factors. Then, many cytokines and growth factors secreted by LF cells and its surrounding tissues play different roles in activating the fibrotic response. Here, we summarize the current status of detailed knowledge available regarding the causative factors, pathology, molecular and cellular mechanisms implicated in LF fibrosis and hypertrophy, also focusing on the possible avenues for anti-fibrotic strategies.

The contribution of epigenetics to the pathogenesis and gender dimorphism of systemic sclerosis: a comprehensive overview

Systemic sclerosis (SSc) is a life-threatening connective tissue disorder of unknown etiology characterized by widespread vascular injury and dysfunction, impaired angiogenesis, immune dysregulation and progressive fibrosis of the skin and internal organs. Over the past few years, a new trend of investigations is increasingly reporting aberrant epigenetic modifications in genes related to the pathogenesis of SSc, suggesting that, besides genetics, epigenetics may play a pivotal role in disease development and clinical manifestations. Like many other autoimmune diseases, SSc presents a striking female predominance, and even if the reason for this gender imbalance has yet to be completely understood, it appears that the X chromosome, which contains many gender and immune-related genes, could play a role in such gender-biased prevalence. Besides a short summary of the genetic background of SSc, in this review we provide a comprehensive overview of the most recent insights into the epigenetic modifications which underlie the pathophysiology of SSc. A particular focus is given to genetic variations in genes located on the X chromosome as well as to the main X-linked epigenetic modifications that can influence SSc susceptibility and clinical phenotype. On the basis of the most recent advances, there is realistic hope that integrating epigenetic data with genomic, transcriptomic, proteomic and metabolomic analyses may provide in the future a better picture of their functional implications in SSc, paving the right way for a better understanding of disease pathogenesis and the development of innovative therapeutic approaches.

Epigenetic Control of Scleroderma: Current Knowledge and Future Perspectives

PURPOSE OF REVIEW

Epigenetics has been implicated in the pathogenesis of systemic sclerosis (SSc). In this review, the involvement of the three epigenetic mechanisms in SSc development and progression-DNA methylation, histone modifications, and non-coding RNAs-will be discussed.

RECENT FINDINGS

Alteration in epigenetics was observed in immune cells, dermal fibroblasts, and endothelial cells derived from SSc patients. Genes that are affected include those involved in immune cell function and differentiation, TGFβ and Wnt pathways, extracellular matrix accumulation, transcription factors, and angiogenesis. All the studies remain in the pre-clinical stage. Extensive research provides evidence that epigenetic alterations are critical for SSc pathogenesis. Future epigenomic studies will undoubtedly continue to broaden our understanding of disease pathogenesis and clinical heterogeneity. They will also provide the scientific basis for repurposing epigenetic-modifying agents for SSc patients.

New insights into the genetics and epigenetics of systemic sclerosis

Systemic sclerosis (SSc) is a severe autoimmune disease that is characterized by vascular abnormalities, immunological alterations and fibrosis of the skin and internal organs. The results of genetic studies in patients with SSc have revealed statistically significant genetic associations with disease manifestations and progression. Nevertheless, genetic susceptibility to SSc is moderate, and the functional consequences of genetic associations remain only partially characterized. A current hypothesis is that, in genetically susceptible individuals, epigenetic modifications constitute the driving force for disease initiation. As epigenetic alterations can occur years before fibrosis appears, these changes could represent a potential link between inflammation and tissue fibrosis. Epigenetics is a fast-growing discipline, and a considerable number of important epigenetic studies in SSc have been published in the past few years that span histone post-translational modifications, DNA methylation, microRNAs and long non-coding RNAs. This Review describes the latest insights into genetic and epigenetic contributions to the pathogenesis of SSc and aims to provide an improved understanding of the molecular pathways that link inflammation and fibrosis. This knowledge will be of paramount importance for the development of medicines that are effective in treating or even reversing tissue fibrosis.

In Silico Detection and Characterization of microRNAs and Their Target Genes in microRNA Microarray Datasets from Patients with Systemic Sclerosis-Interstitial Lung Disease

Interstitial lung disease (ILD) is the main reason of death in patients with systemic sclerosis (SSc). The potential microRNA (miRNA)-messenger RNA (mRNA) interaction networks of SSc-ILD from a systematic biological perspective are unclear. To characterize differentially expressed miRNAs (DE-miRNAs) and differentially expressed genes (DEGs) likely related to SSc-ILD, we downloaded the miRNA microarray dataset (GSE81923) and mRNA datasets (GSE76808 and GSE81292) from the Gene Expression Omnibus database. Comprehensive bioinformatic analyses were conducted to predict target genes for DE-miRNAs and generate an miRNA-hub gene network with SSc-ILD. In total, 26 DE-miRNAs were detected in SSc-ILD, among which 2 were upregulated and 24 were downregulated. Additionally, 178 common DEGs (55 upregulated and 123 downregulated) were identified. miRNAs were primarily enriched in pathways involving inflammation and regulation of fibroblasts. The hub genes identified were MMP7, IER2, HBEGF, CCL4, NFKBIA, JUNB, LIF, SERPINE1, FOSL1, and NAMPT. We discovered the miRNA-mediated regulatory network in SSc-ILD using an integrated bioinformatic analysis. The findings provide novel insight and expand our comprehension of the molecular mechanisms participating in the pathogenesis of SSc-ILD, along with identification of new potential diagnostic biomarkers.

Pathogenesis and treatment of autoimmune rheumatic diseases

PURPOSE OF REVIEW

Autoimmune diseases are of unknown origin, and they represent significant causes of morbidity and mortality. Here, we review new developments in the understanding of their pathogenesis that have led to development of well tolerated and effective treatments.

RECENT FINDINGS

In addition to the long-recognized genetic impact of the HLA locus, interferon regulatory factors, PTPN22, STAT4, and NOX have been implicated in pathogenesis of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Smoking, ultraviolet light, diet, and microbiota exert strong environmental influence on development of RA and SLE. Metabolism has been recognized as a critical integrator of genetic and environmental factors, and it controls immune cell differentiation both under physiological and pathological conditions.

SUMMARY

With the advent of high-throughput genetic, proteomic, and metabolomic technologies, the field of medicine has been shifting towards systems-based and personalized approaches to diagnose and treat common conditions, including rheumatic diseases. Regulatory checkpoints of metabolism and signal transduction, such as glucose utilization, mitochondrial electron transport, JAK, mTOR, and AMPK pathway activation, and production of pro-inflammatory cytokines IL-1, IL-6, and IL-17 have presented new targets for therapeutic intervention. This review amalgamates recent discoveries in genetics and metabolomics with immunological pathways of pathogenesis in rheumatic diseases.

The Role of Epigenetic Modifications in Systemic Sclerosis: A Druggable Target

Systemic sclerosis (SSc) is a rare autoimmune disorder characterised by skin fibrosis that often also affects internal organs, eventually resulting in mortality. Although management of the symptoms has extended lifespan, patients still suffer from poor quality of life, hence the need for improved therapies. Development of efficacious treatments has been stymied by the unknown aetiology, although recent advancements suggest a potentially key role for epigenetics - the regulation of gene expression by noncoding RNAs and chemical modifications to DNA or DNA-associated proteins. Herein, the evidence implicating epigenetics in the pathogenesis of SSc is discussed with an emphasis on the therapeutic potential this introduces to the field - particularly the repurposing of epigenetic targeting cancer therapeutics and newly emerging miRNA-based strategies.

Overexpression of apoptosis-related protein, survivin, in fibroblasts from patients with systemic sclerosis

BACKGROUND/OBJECTIVES

Recent studies suggest that, in addition to activation and hypersecretion of matrix components, fibroblasts from patients with systemic sclerosis (SSc) are resistant to apoptosis. Previous studies have shown that survivin, a member of inhibition of apoptosis (IAP) family, plays an important role in apoptosis resistance. Accordingly, we decided to study the expression of the most important members of IAP family in SSc fibroblasts, which can block apoptosis either by binding and inhibiting caspases or through caspase-independent mechanisms.

METHOD

Skin biopsy samples were obtained from 19 patients with diffuse cutaneous SSc (DcSSc) and 16 healthy controls. Dermal fibroblasts were cultured and the total RNA was isolated from cells followed by cDNA synthesis. Real-time PCR was performed using SYBR Green PCR master mix and specific primers for cIAP1, cIAP2, XIAP, and Survivin mRNA quantification.

RESULTS

A significantly increased expression level of Survivin was observed in fibroblasts from SSc patients compared to controls (2.26-fold, P = 0.04). However, mRNA expression of cIAP1, cIAP2, and XIAP did not change significantly between cases and controls.

CONCLUSIONS

Our results showed that survivin is upregulated in SSc skin fibroblast which may lead to resistance to apoptosis. Further studies should be performed to reveal the role of survivin in apoptosis pathway of SSc fibroblasts.

Unraveling SSc Pathophysiology; The Myofibroblast

Systemic sclerosis (SSc) is a severe auto-immune disease, characterized by vasculopathy and fibrosis of connective tissues. SSc has a high morbidity and mortality and unfortunately no disease modifying therapy is currently available. A key cell in the pathophysiology of SSc is the myofibroblast. Myofibroblasts are fibroblasts with contractile properties that produce a large amount of pro-fibrotic extracellular matrix molecules such as collagen type I. In this narrative review we will discuss the presence, formation, and role of myofibroblasts in SSc, and how these processes are stimulated and mediated by cells of the (innate) immune system such as mast cells and T helper 2 lymphocytes. Furthermore, current novel therapeutic approaches to target myofibroblasts will be highlighted for future perspective.

MiR-3606-3p inhibits systemic sclerosis through targeting TGF-β type II receptor

Systemic sclerosis (SSc) is a multisystemic fibrotic disease characterized by excessive collagen deposition and extracellular matrix synthesis. Though transforming growth factor-β (TGF-β) plays a fundamental role in the pathogenesis of SSc, the mechanism by which TGF-β signaling acts in SSc remains largely unclear. Here, we showed that TGF-β type II receptor (TGFBR2) was significantly upregulated in both human SSc dermal tissues and primary fibroblasts. In fibroblasts, siRNA-induced knockdown of TGFBR2 resulted in a reduction of p-SMAD2/3 levels and reduced production of type I collagen. Additionally, functional experiments revealed that downregulation of TGFBR2 yielded an anti-growth effect on fibroblasts through inhibiting cell cycle progression. Further studies showed that miR-3606-3p could directly target the 3'-UTR of TGFBR2 and significantly decrease the levels of both TGFBR2 mRNA and protein. Furthermore, SSc dermal tissues and primary fibroblasts contain significantly reduced amounts of miR-3606-3p, and the overexpression of miR-3606-3p in fibroblasts replicates the phenotype of TGFBR2 downregulation. Collectively, our findings demonstrated that increased TGFBR2 could be responsible for the hyperactive TGF-β signaling observed in SSc. Moreover, we identified a pivotal role for miR-3606-3p in SSc, which acts, at least partly, through the attenuation of TGF-β signaling via TGFBR2 repression, suggesting that the regulation of miR-3606-3p/TGFBR2 could be a promising therapeutic target that could improve the treatment strategy for fibrosis.

Expressions of p53 and PUMA in fibroblasts of systemic sclerosis patients are normal at transcription level

BACKGROUND

Systemic sclerosis (SSc) fibroblasts show resistance apoptosis mechanisms, which enhances the fibrosis stage of the disease. Impaired function of p53 upregulated modulator of apoptosis (PUMA) has been related to deficits in p53-dependant apoptosis pathway. This study aimed to evaluate the transcriptional levels of p53 and PUMA mRNAs in fibroblasts from SSc patients and compare it with healthy individuals.

METHODS

In this case-control study, skin biopsy samples were obtained from 19 patients with diffuse cutaneous SSc (DcSSc) and 16 healthy controls. Afterward, dermal fibroblasts were isolated and cultured. After extraction of total RNA from cultured fibroblasts, complementary DNA (cDNA) was synthesized. mRNA quantification was carried out using real-time PCR, SYBR Green PCR master mix, and specific primers for p53 and PUMA.

RESULTS

No significant alteration was observed in mRNA expression levels of p53 and PUMA (P = .99 and .23, respectively) in fibroblasts from SSc patients compared with controls.

CONCLUSIONS

Apoptosis pathways are impaired in fibroblasts from patients with SSc, leading to chronic fibrosis. Nonetheless, PUMA/p53 pathway may not be involved in dysfunction of apoptosis mechanisms in fibroblasts of patients with SSc.

Dysregulation of microRNAs in autoimmune diseases: Pathogenesis, biomarkers and potential therapeutic targets

MicroRNAs (miRNAs) are small, single-stranded, endogenous non-coding RNAs that repress the expression of target genes via post-transcriptional mechanisms. Due to their broad regulatory effects, the precisely regulated, spatial-specific and temporal-specific expression of miRNAs is fundamentally important to various biological processes including the immune homeostasis and normal function of both innate and adaptive immune response. Aberrance of miRNAs is implicated in the development of various human diseases, especially cancers. Increasing evidence has revealed a dysregulated expression pattern of miRNAs in autoimmune diseases, among which many play key roles in the pathogenesis. In this review we summarize these findings on miRNA dysregulation implicated in autoimmune diseases, focusing on four representative systemic autoimmune diseases, i.e. systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis and dermatomyositis. The causes of the dysregulation of miRNA expression in autoimmune diseases may include genetic and epigenetic variants, and various environmental factors. Further understanding of miRNA dysregulation and its mechanisms during the development of different autoimmune diseases holds enormous potential to bring about novel therapeutic targets or strategies for these complex human disorders, as well as novel circulating or exosomal miRNA biomarkers.

Evaluation of ITGB2 (CD18) and SELL (CD62L) genes expression and methylation of ITGB2 promoter region in patients with systemic sclerosis

Systemic sclerosis (SSc), an autoimmune disease of connective tissue, is characterized by inflammation, fibrosis, and vessel endothelial damage. Products of Integrin subunit beta 2 (ITGB2) and selectin L (SELL) genes participate in several functional pathways of immune system. The aim of this investigation was to survey the transcript level of ITGB2 and SELL genes as well as methylation status of CpG sites in promoter region of differently expressed gene in PBMCs of SSc patients. PBMCs were isolated from whole blood of 50 SSc patients and 30 healthy controls. Total RNA and DNA contents of PBMCs were extracted. Gene expression was analyzed by real-time PCR using the SYBR Green PCR Master Mix. To investigate the methylation status of CpG sites, DNA samples were treated by bisulfite, amplified through nested PCR, and sequenced through Sanger difficult sequencing method. ITGB2 gene in PBMCs of SSc patients was overexpressed significantly in comparison to healthy controls. However, no altered SELL expression was observed. Three CpG sites of 12, 13 and 14 were significantly hypomethylated in patients group, despite overall methylation status of ITGB2 gene promoter revealed no significant difference between study groups. There was no statistically significant correlation between methylation status of ITGB2 promoter and the gene expression in patients. Regarding to lack of correlation of increased expression of ITGB2 with its promoter hypomethylation in SSc patients, our study suggests that upregulation of ITGB2 in PBMCs from SSc patients is probably due to another mechanism other than methylation alteration.

Epigenetics and pathogenesis of systemic sclerosis; the ins and outs

The pathogenesis of many diseases is influenced by environmental factors which can affect human genome and be inherited from generation to generation. Adverse environmental stimuli are recognized through the epigenetic regulatory complex, leading to gene expression alteration, which in turn culminates in disease outcomes. Three epigenetic regulatory mechanisms modulate the manifestation of a gene, namely DNA methylation, histone changes, and microRNAs. Both epigenetics and genetics have been implicated in the pathogenesis of systemic sclerosis (SSc) disease. Genetic inheritance rate of SSc is low and the concordance rate in both monozygotic (MZ) and dizygotic (DZ) twins is little, implying other possible pathways in SSc pathogenesis scenario. Here, we provide an extensive overview of the studies regarding different epigenetic events which may offer insights into the pathology of SSc. Furthermore, epigenetic-based interventions to treat SSc patients were discussed.

Mir-21 Mediates the Inhibitory Effect of Ang (1-7) on AngII-induced NLRP3 Inflammasome Activation by Targeting Spry1 in lung fibroblasts

MicroRNA-21 (mir-21) induced by angiotensin II (AngII) plays a vital role in the development of pulmonary fibrosis, and the NLRP3 inflammasome is known to be involved in fibrogenesis. However, whether there is a link between mir-21 and the NLRP3 inflammasome in pulmonary fibrosis is unknown. Angiotensin-converting enzyme 2/angiotensin(1-7) [ACE2/Ang(1-7)] has been shown to attenuate AngII-induced pulmonary fibrosis, but it is not clear whether ACE2/Ang(1-7) protects against pulmonary fibrosis by inhibiting AngII-induced mir-21 expression. This study's aim was to investigate whether mir-21 activates the NLRP3 inflammasome and mediates the different effects of AngII and ACE2/Ang(1-7) on lung fibroblast apoptosis and collagen synthesis. In vivo, AngII exacerbated bleomycin (BLM)-induced lung fibrosis in rats, and elevated mir-21 and the NLRP3 inflammasome. In contrast, ACE2/Ang(1-7) attenuated BLM-induced lung fibrosis, and decreased mir-21 and the NLRP3 inflammasome. In vitro, AngII activated the NLRP3 inflammasome by up-regulating mir-21, and ACE2/Ang(1-7) inhibited NLRP3 inflammasome activation by down-regulating AngII-induced mir-21. Over-expression of mir-21 activated the NLRP3 inflammasome via the ERK/NF-κB pathway by targeting Spry1, resulting in apoptosis resistance and collagen synthesis in lung fibroblasts. These results indicate that mir-21 mediates the inhibitory effect of ACE2/Ang(1-7) on AngII-induced activation of the NLRP3 inflammasome by targeting Spry1 in lung fibroblasts.

MiR-21 promotes fibrosis and hypertrophy of ligamentum flavum in lumbar spinal canal stenosis by activating IL-6 expression

The molecular mechanism underlying the fibrosis of ligamentum flavum(LF) in patients with lumbar spinal canal stenosis(LSCS) remains unknown. MicroRNAs are reported to play important roles in regulating fibrosis in different organs. The present study aimed to identify fibrosis related miR-21 expression profile and investigate the pathological process of miR-21 in the fibrosis of LF hypertrophy and associated regulatory mechanisms. 15 patients with LSCS underwent surgical treatment were enrolled in this study. For the control group, 11 patients with lumbar disc herniation(LDH) was included. The LF thickness was measured on MRI. LF samples were obtained during the surgery. Fibrosis score was assessed by Masson's trichrome staining. The expression of miR-21 in LF tissues were determined by RT-PCR. Correlation among LF thickness, fibrosis score, and miR-21 expression was analyzed. In addition, Lentiviral vectors for miR-21 mimic were constructed and transfected into LF cells to examine the role of miR-21 in LF fibrosis. Types I and III collagen were used as indicators of fibrosis. IL-6 expression in LF cells after transfection was investigated by RT-PCR and ELISA. Patients in two groups showed similar outcomes regarding age, gender, level of LF tissue. The thickness and fibrosis score of LF in the LSCS group were significantly greater than those in LDH group (all P < 0.05). Similarly, the expression of miR-21 in LSCS group was substantially higher than that in LDH group(P < 0.05). Furthermore, the miR-21 expression exhibited positive correlations with the LF thickness (r = 0.595, P < 0.05) and fibrosis score (r = 0.608, P < 0.05). Of note, miR-21 over-expression increased the expression levels of collagen I and III (P < 0.05). Also, IL-6 expression and secretion in LF cells was elevated after transfection of miR-21 mimic. MiR-21 is a fibrosis-associated miRNA and promotes inflammation in LF tissue by activating IL-6 expression, leading to LF fibrosis and hypertrophy.