miR-29 inhibits bleomycin-induced pulmonary fibrosis in mice

MicroRNA-29b inhibits supernatants from silica-treated macrophages from inducing extracellular matrix synthesis in lung fibroblasts

Silicosis is pathologically characterized by diffused pulmonary fibrosis and abundant deposition of extracellular matrix (ECM) components. The ECM is mainly secreted by myofibroblasts which are the activated state of fibroblasts. MicroRNA-29b (miR-29b) is one of the well-known microRNAs involved in fibrosis, but its roles in silicosis have not been specified. In this study, we hypothesized that miR-29b might play a protective role in the progression of silicosis. MTT assay, qRT-PCR, immunofluorescence and western blotting were applied. The results demonstrated that the supernatants from silica-treated macrophages not only caused the proliferation of fibroblasts (NIH-3T3 and MRC-5) but were also involved in the down-regulation of miR-29b. Meanwhile they could induce fibroblast activation, increasing the expression of ECM components such as collagen1 and collagen3, in a silica dose-dependent manner. Furthermore, overexpression of miR-29b by transfecting mimics markedly reduced the expression of ECM components and inhibited ECM synthesis. These findings indicate that miR-29b inhibits the supernatants from silica-treated macrophages from inducing extracellular matrix synthesis, thus miR-29b might have a strong anti-fibrotic capacity in silicosis and serve as a potential therapeutic agent for the treatment.

Gene Therapy with the Sleeping Beauty Transposon System

The widespread clinical implementation of gene therapy requires the ability to stably integrate genetic information through gene transfer vectors in a safe, effective, and economical manner. The latest generation of Sleeping Beauty (SB) transposon vectors fulfills these requirements, and may overcome limitations associated with viral gene transfer vectors and transient nonviral gene delivery approaches that are prevalent in ongoing clinical trials. The SB system enables high-level stable gene transfer and sustained transgene expression in multiple primary human somatic cell types, thereby representing a highly attractive gene transfer strategy for clinical use. Here, we review the most important aspects of using SB for gene therapy, including vectorization as well as genomic integration features. We also illustrate the path to successful clinical implementation by highlighting the application of chimeric antigen receptor (CAR)-modified T cells in cancer immunotherapy.

miR-29b supplementation decreases expression of matrix proteins and improves alveolarization in mice exposed to maternal inflammation and neonatal hyperoxia

Even with advances in the care of preterm infants, chronic lung disease or bronchopulmonary dysplasia (BPD) continues to be a significant pulmonary complication. Among those diagnosed with BPD, a subset of infants develop severe BPD with disproportionate pulmonary morbidities. In addition to decreased alveolarization, these infants develop obstructive and/or restrictive lung function due to increases in or dysregulation of extracellular matrix proteins. Analyses of plasma obtained from preterm infants during the first week of life indicate that circulating miR-29b is suppressed in infants that subsequently develop BPD and that decreased circulating miR-29b is inversely correlated with BPD severity. Our mouse model mimics the pathophysiology observed in infants with severe BPD, and we have previously reported decreased pulmonary miR-29b expression in this model. The current studies tested the hypothesis that adeno-associated 9 (AAV9)-mediated restoration of miR-29b in the developing lung will improve lung alveolarization and minimize the deleterious changes in matrix deposition. Pregnant C3H/HeN mice received an intraperitoneal LPS injection on embryonic day 16 and newborn pups were exposed to 85% oxygen from birth to 14 days of life. On postnatal day 3, AAV9-miR-29b or AAV9-control was administered intranasally. Mouse lung tissues were then analyzed for changes in miR-29 expression, alveolarization, and matrix protein levels and localization. Although only modest improvements in alveolarization were detected in the AAV9-miR29b-treated mice at postnatal day 28, treatment completely attenuated defects in matrix protein expression and localization. Our data suggest that miR-29b restoration may be one component of a novel therapeutic strategy to treat or prevent severe BPD in prematurely born infants.

Elevated plasma levels of miR-29a are associated with hemolysis in patients with hypertrophic cardiomyopathy

BACKGROUND

miR-29a is a small non-coding RNA that is known to repress collagen synthesis. Interestingly, elevated plasma miR-29a was reported to correlate with pronounced myocardial fibrosis in patients with hypertrophic cardiomyopathy. The objective of this study was to elucidate the origin of plasma miR-29a, and evaluate its significance as a biomarker.

METHODS

miR-29a expression was evaluated in plasma (n=50) and myocardial samples (n=4) from patients with hypertrophic cardiomyopathy using RT-qPCR.

RESULTS

Although miR-29a was highly expressed in the myocardium, miR-29a plasma levels did not show any correlation with serum troponin I levels (r_s=-0.12, p=0.43), and the heart does not release significant amounts of miR-29a into the circulation via exosome secretion. Conversely, miR-29a was present in red blood cells, and plasma levels correlated significantly with markers of hemolysis: lactic dehydrogenase (r_s=0.36, p=0.01) and the absorbance of oxyhemoglobin at 414nm (r_s=0.39, p=0.006). Furthermore, the association between serum haptoglobin and the maximal blood flow velocity in the left ventricle outflow tract (r_s=-0.42, p=0.008) indicated that intravascular hemolysis is a manifestation of the disease.

CONCLUSIONS

miR-29a is highly expressed in myocardial tissue from patients with hypertrophic cardiomyopathy. In contrast, plasma miR-29a is primarily of nonmyocardial origin and is correlated significantly with the extent of hemolysis observed in these patients.

Dnmt3a-mediated inhibition of Wnt in cardiac progenitor cells improves differentiation and remote remodeling after infarction

Adult cardiac progenitor cells (CPCs) display a low capacity to differentiate into cardiomyocytes in injured hearts, strongly limiting the regenerative capacity of the mammalian myocardium. To identify new mechanisms regulating CPC differentiation, we used primary and clonally expanded Sca-1+ CPCs from murine adult hearts in homotypic culture or coculture with cardiomyocytes. Expression kinetics analysis during homotypic culture differentiation showed downregulation of Wnt target genes concomitant with increased expression of the Wnt antagonist, Wnt inhibitory factor 1 (Wif1), which is necessary to stimulate CPC differentiation. We show that the expression of the Wif1 gene is repressed by DNA methylation and regulated by the de novo DNA methyltransferase Dnmt3a. In addition, miR-29a is upregulated early during CPC differentiation and downregulates Dnmt3a expression, thereby decreasing Wif1 gene methylation and increasing the efficiency of differentiation of Sca-1+ CPCs in vitro. Extending these findings in vivo, transient silencing of Dnmt3a in CPCs subsequently injected in the border zone of infarcted mouse hearts improved CPC differentiation in situ and remote cardiac remodeling. In conclusion, miR-29a and Dnmt3a epigenetically regulate CPC differentiation through Wnt inhibition. Remote effects on cardiac remodeling support paracrine signaling beyond the local injection site, with potential therapeutic interest for cardiac repair.

Plasminogen Activator Inhibitor Type-1 as a Regulator of Fibrosis

Fibrosis is known as a frequent and irreversible pathological condition which is associated with organ failure. Tissue fibrosis is a central process in a variety of chronic progressive diseases such as diabetes, hypertension, and persistent inflammation. This state could contribute to chronic injury and the initiation of tissue repair. Fibrotic disorders represent abnormal wound healing with defective matrix turnover and clearance that lead to excessive accumulation of extracellular matrix components. A variety of identified growth factors, cytokines, and persistently activated myofibroblasts have critical roles in the pathogenesis of fibrosis. Irrespective of etiology, the transforming growth factor-β pathway is the major driver of fibrotic response. Plasminogen activator inhibitor-1 (PAI-1) is a crucial downstream target of this pathway. Transforming growth factor-β positively regulates PAI-1 gene expression via two main pathways including Smad-mediated canonical and non-canonical pathways. Overexpression of PAI-1 reduces extracellular matrix degradation via perturbing the plasminogen activation system. Indeed, elevated PAI-1 levels inhibit proteolytic activity of tissue plasminogen activator and urokinase plasminogen activator which could contribute to a variety of inflammatory elements in the injury site and to excessive matrix deposition. This review summarizes the current knowledge of critical pathways that regulate PAI-1 gene expression and suggests effective approaches for the treatment of fibrotic disease. J. Cell. Biochem. 119: 17-27, 2018. © 2017 Wiley Periodicals, Inc.

Exogenous miR-29B Delivery Through a Hyaluronan-Based Injectable System Yields Functional Maintenance of the Infarcted Myocardium

Myocardial infarction (MI) results in debilitating remodeling of the myocardial extracellular matrix (ECM). In this proof-of-principle study it was sought to modulate this aggressive remodeling by injecting a hyaluronic acid-based reservoir delivering exogenous microRNA-29B (miR-29B). This proof-of-principal study was executed whereby myocardial ischemia/reperfusion was performed on C57BL/6 mice for 45 min after which five 10 μL boluses of a hydrogel composed of thiolated hyaluronic acid cross-linked with poly (ethylene glycol) diacrylate, containing exogenous miR-29B as an active therapy, were injected into the border zone of the infarcted myocardium. Following surgery, the myocardial function of the animals was monitored up to 5 weeks. Delivering miR-29B locally using an injectable hyaluronan-based hydrogel resulted in the maintenance of myocardial function at 2 and 5 weeks following MI in this proof-of-principle study. In addition, while animals treated with the control of a nontargeting miR delivered using the hyaluronan-based hydrogel had a significant deterioration of myocardial function, those treated with miR-29B did not. Histological analysis revealed a significantly decreased presence of elastin and significantly less immature/newly deposited collagen fibers at the border zone of the infarct. Increased vascularity of the myocardial scar was also detected and Raman microspectroscopy discovered significantly altered ECM-specific biochemical signals at the border zone of the infarct. This preclinical proof-of-principle study demonstrates that an injectable hyaluronic acid hydrogel system could be capable of delivering miR-29B toward maintaining cardiac function following MI. In addition, Raman microspectroscopy revealed subtle, yet significant changes in ECM organization and maturity. These findings have great potential with regard to using injectable biomaterials as a local treatment for ischemic tissue and exogenous miRs to modulate tissue remodeling.

A systematic review of overlapping microRNA patterns in systemic sclerosis and idiopathic pulmonary fibrosis

Lung fibrosis can be observed in systemic sclerosis and in idiopathic pulmonary fibrosis, two disorders where lung involvement carries a poor prognosis. Although much has been learned about the pathogenesis of these conditions, interventions capable of reversing or, at the very least, halting disease progression are not available. Recent studies point to the potential role of micro messenger RNAs (microRNAs) in cancer and tissue fibrogenesis. MicroRNAs are short non-coding RNA sequences (20–23 nucleotides) that are endogenous, evolutionarily conserved and encoded in the genome. By acting on several genes, microRNAs control protein expression. Considering the above, we engaged in a systematic review of the literature in search of overlapping observations implicating microRNAs in the pathogenesis of both idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc). Our objective was to uncover top microRNA candidates for further investigation based on their mechanisms of action and their potential for serving as targets for intervention against lung fibrosis. Our review points to microRNAs of the -29 family, -21-5p and -92a-3p, -26a-5p and let-7d-5p as having distinct and counter-balancing actions related to lung fibrosis. Based on this, we speculate that readjusting the disrupted balance between these microRNAs in lung fibrosis related to SSc and IPF may have therapeutic potential.

miR-21-5p and the miR-29 family group cluster in systemic sclerosis and idiopathic pulmonary fibrosishttp://ow.ly/D6B030bg2vn

Detecting the Molecular System Signatures of Idiopathic Pulmonary Fibrosis through Integrated Genomic Analysis

Idiopathic Pulmonary Fibrosis (IPF) is an incurable progressive fibrotic disease of the lungs. We currently lack a systematic understanding of IPF biology and a systems approach may offer new therapeutic insights. Here, for the first time, a large volume of high throughput genomics data has been unified to derive the most common molecular signatures of IPF. A set of 39 differentially expressed genes (DEGs) was found critical to distinguish IPF. Using high confidence evidences and experimental data, system level networks for IPF were reconstructed, involving 737 DEGs found common across at least two independent studies. This all provided one of the most comprehensive molecular system views for IPF underlining the regulatory and molecular consequences associated. 56 pathways crosstalks were identified which included critical pathways with specified directionality. The associated steps gained and lost due to crosstalk during IPF were also identified. A serially connected system of five crucial genes was found, potentially controlled by nine miRNAs and eight transcription factors exclusively in IPF when compared to NSIP and Sarcoidosis. Findings from this study have been implemented into a comprehensive molecular and systems database on IPF to facilitate devising diagnostic and therapeutic solutions for this deadly disease.

MicroRNA-29 overexpression by adeno-associated virus suppresses fibrosis and restores muscle function in combination with micro-dystrophin

Duchenne muscular dystrophy (DMD) is caused by dystrophin deficiency resulting in progressive muscle weakness and fibrotic scarring. Muscle fibrosis impairs blood flow, hampering muscle repair and regeneration. Irrespective of the success of gene restoration, functional improvement is limited without reducing fibrosis. The levels of miR-29c, a known regulator of collagen, are reduced in DMD. Our goal is to develop translational, antifibrotic therapy by overexpressing miR-29c. We injected the gastrocnemius muscle with either self-complementary AAV.CMV.miR-29c or single-stranded AAV.MCK.micro-dystrophin alone or in combination in the mdx/utrn+/- mouse, a DMD mouse model. Treatment of 3-month-old mdx/utrn+/- mice with AAV.miR-29c showed a reduction in collagen and increased absolute and specific force compared with untreated animals, but neither parameter reached WT levels. Combinatorial gene delivery in 3-month-old mdx/utrn+/- mice further decreased fibrosis, and showed a reduction of transcript levels for Col1A, Col3A, fibronectin, and Tgfb1. In addition, absolute and specific force was normalized and equivalent to WT. However, protection against eccentric contraction fell short of WT levels at this time point. When this same mouse model was treated with miR-29c/micro-dystrophin combinatorial therapy at 1 month of age, there was complete normalization of specific and absolute force and protection against eccentric contraction-induced injury was comparable to WT. These findings highlight the potential for miR-29c as an important addition to the armamentarium for translational gene therapy, especially when used in combination with micro-dystrophin in DMD.

Role of the microRNA-29 family in fibrotic skin diseases

Fibrotic skin diseases are characterized by the accumulation of collagen. The hallmarks of fibrotic skin diseases are unbalanced fibroblast proliferation and differentiation, extracellular matrix production and transforming growth factor-β signalling. Numerous studies have investigated the possibility that microRNAs (miRNAs or miRs) are involved in the pathogenesis of certain fibrotic diseases, including skin, heart, lung and liver diseases. miRNAs are a class of small non-coding RNAs, which modify gene expression by binding to target messenger RNA (mRNA) and blocking the translation or inducing the degradation of target mRNA. The biological relevance of miRNAs has been investigated in physiological and pathological conditions, and there is increasing evidence that the miR-29 family is associated with fibrotic diseases. The aim of the present review is to provide an up-to-date summary of current knowledge on the latest developments associated with the miR-29 family and fibrotic skin diseases.

Going non-viral: the Sleeping Beauty transposon system breaks on through to the clinical side

Molecular medicine has entered a high-tech age that provides curative treatments of complex genetic diseases through genetically engineered cellular medicinal products. Their clinical implementation requires the ability to stably integrate genetic information through gene transfer vectors in a safe, effective and economically viable manner. The latest generation of Sleeping Beauty (SB) transposon vectors fulfills these requirements, and may overcome limitations associated with viral gene transfer vectors and transient non-viral gene delivery approaches that are prevalent in ongoing pre-clinical and translational research. The SB system enables high-level stable gene transfer and sustained transgene expression in multiple primary human somatic cell types, thereby representing a highly attractive gene transfer strategy for clinical use. Here we review several recent refinements of the system, including the development of optimized transposons and hyperactive SB variants, the vectorization of transposase and transposon as mRNA and DNA minicircles (MCs) to enhance performance and facilitate vector production, as well as a detailed understanding of SB's genomic integration and biosafety features. This review also provides a perspective on the regulatory framework for clinical trials of gene delivery with SB, and illustrates the path to successful clinical implementation by using, as examples, gene therapy for age-related macular degeneration (AMD) and the engineering of chimeric antigen receptor (CAR)-modified T cells in cancer immunotherapy.

miR-29b promotes skin wound healing and reduces excessive scar formation by inhibition of the TGF-β1/Smad/CTGF signaling pathway

The hypertrophic scar is a medical difficulty of humans, which has caused great pain to patients. Here, we investigated the inhibitory effect of miR-29b on scar formation. The scalded model was established in mice and miR-29b mimics or a negative control was subcutaneously injected into the injury skin. Then various molecular biological experiments were performed to assess the effect of miR-29b on scar formation. According to our present study, first, the results demonstrated that miR-29b was down-regulated in thermal injury tissue and miR-29b treatment could promote wound healing, inhibit scar formation, and alleviate histopathological morphologic alteration in scald tissues. Additionally, miR-29b treatment suppressed collagen deposition and fibrotic gene expression in scar tissues. Finally, we found that miR-29b treatment inhibited the TGF-β1/Smad/CTGF signaling pathway. Taken together, our data suggest that miR-29b treatment has an inhibitory effect against scar formation via inhibition of the TGF-β1/Smad/CTGF signaling pathway and may provide a potential molecular basis for future treatments for hypertrophic scars.

Lung cancer in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrotic lung disease of unknown etiology. With a gradually increasing worldwide prevalence and a mortality rate exceeding that of many cancers, IPF diagnosis and management are critically important and require a comprehensive multidisciplinary approach. This approach also involves assessment of comorbid conditions, such as lung cancer, that exerts a dramatic impact on disease survival. Emerging evidence suggests that progressive lung scarring in the context of IPF represents a risk factor for lung carcinogenesis. Both disease entities present with major similarities in terms of pathogenetic pathways, as well as potential causative factors, such as smoking and viral infections. Besides disease pathogenesis, anti-cancer agents, including nintedanib, have been successfully applied in the treatment of patients with IPF while an oncologic approach with a cocktail of several pleiotropic anti-fibrotic agents is currently in the therapeutic pipeline of IPF. Nevertheless, epidemiologic association between IPF and lung cancer does not prove causality. Currently there is significant lack of knowledge supporting a direct association between lung fibrosis and cancer reflecting to disappointing therapeutic algorithms. An optimal therapeutic strategy for patients with both IPF and lung cancer represents an amenable need. This review article synthesizes the current state of knowledge regarding pathogenetic commonalities between IPF and lung cancer and focuses on clinical and therapeutic data that involve both disease entities.

Extracellular matrix remodeling in idiopathic pulmonary fibrosis. It is the 'bed' that counts and not 'the sleepers'

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease characterized by irreversible fibrosis. Current disease pathogenesis assumes an aberrant wound healing process in response to repetitive injurious stimuli leading to apoptosis of epithelial cells, activation of fibroblasts and accumulation of extracellular matrix (ECM). Particularly, lung ECM is a highly dynamic structure that lies at the core of several physiological and developmental pathways. The scope of this review article is to summarize current knowledge on the role of ECM in the pathogenesis of IPF, unravel novel mechanistic data and identify future more effective therapeutic targets. Areas covered: The exact mechanisms through which lung microenvironment activates fibroblasts and inflammatory cells, regulates profibrotic signaling cascades through growth factors, integrins and degradation enzymes ultimately leading to excessive matrix deposition are discussed. Furthermore, the potential therapeutic usefulness of specific inhibitors of matrix deposition or activators of matrix degradation pathways are also presented. Expert commentary: With a gradually increasing worldwide incidence IPF still present a major challenge in clinical research due to its unknown etiopathogenesis and current ineffective treatment approaches. Today, there is an amenable need for more effective therapeutic targets and ECM components may represent one.

Novel form of miR-29b suppresses bleomycin-induced pulmonary fibrosis

MicroRNA 29b (miR-29b) replacement therapy is effective for suppressing fibrosis in a mouse model. However, to develop clinical applications for miRNA mimics, the side effects of nucleic acid drugs have to be addressed. In this study, we focused on miRNA mimics in order to develop therapies for idiopathic pulmonary fibrosis. We developed a single-stranded RNA, termed “miR-29b Psh-match,” that has a unique structure to avoid problems associated with the therapeutic uses of miRNAs. A comparison of miR-29b Psh-match and double-stranded one, termed “miR-29b mimic” indicated that the single-stranded form was significantly effective towards fibrosis according to both in vivo and in vitro experiments. This novel form of miR-29b may become the foundation for developing an effective therapeutic drug for pulmonary fibrosis.

MCL-1 is modulated in Crohn's disease fibrosis by miR-29b via IL-6 and IL-8

The miR-29 family is involved in fibrosis in multiple organs, including the intestine where miR-29b facilitates TGF-β-mediated up-regulation of collagen in mucosal fibroblasts from Crohn’s disease (CD) patients. Myeloid cell leukemia-1 (MCL-1), a member of the B-cell CLL/Lymphoma 2 (BCL-2) apoptosis family, is involved in liver fibrosis and is targeted by miR-29b via its 3’-UTR in cultured cell lines. We investigate the role of MCL-1 and miR-29b in primary intestinal fibroblasts and tissue from stricturing CD patients. Transfection of CD intestinal fibroblasts with pre-miR-29b resulted in a significant increase in the mRNA expression of MCL-1 isoforms [MCL-1Long (L)/Extra Short (ES) and MCL-1Short (S)], although MCL-1S was expressed at significantly lower levels. Western blotting predominantly detected the anti-apoptotic MCL-1L isoform, and immunofluorescence showed that staining was localised in discrete nuclear foci. Transfection with pre-miR-29b or anti-miR-29b resulted in a significant increase or decrease, respectively, in MCL-1L foci. CD fibroblasts treated with IL-6 and IL-8, inflammatory cytokines upstream of MCL-1, increased the total mass of MCL-1L-positive foci. Furthermore, transfection of intestinal fibroblasts with pre-miR-29b resulted in an increase in mRNA and protein levels of IL-6 and IL-8. Finally, immunohistochemistry showed reduced MCL-1 protein expression in fibrotic CD samples compared to non-stricturing controls. Together, our findings suggest that induction of MCL-1 by IL-6/IL-8 may surmount any direct down-regulation by miR-29b via its 3’-UTR. We propose that an anti-fibrotic miR-29b/IL-6 IL-8/MCL-1L axis may influence intestinal fibrosis in CD. In the future, therapeutic modulation of this pathway might contribute to the management of fibrosis in CD.

Sex and age differences in the expression of liver microRNAs during the life span of F344 rats

Background

Physiological factors such as age and sex have been shown to be risk factors for adverse effects in the liver, including liver diseases and drug-induced liver injury. Previously, we have reported age- and sex-related significant differences in hepatic basal gene expression in rats during the life span that may be related to susceptibility to such adverse effects. However, the underlying mechanisms of the gene expression changes were not fully understood. In recent years, increasing evidence for epigenetic mechanisms of gene regulation has fueled interest in the role of microRNAs (miRNAs) in toxicogenomics and biomarker discovery. We therefore proposed that significant age and sex differences exist in baseline liver miRNA expression, and that comprehensive profiling of miRNAs will provide insights into the epigenetic regulation of gene expression in rat liver.

Methods

To address this, liver tissues from male and female F344 rats were examined at 2, 5, 6, 8, 15, 21, 52, 78, and 104 weeks of age for the expression of 677 unique miRNAs. Following data processing, predictive pathway analysis was performed on selected miRNAs that exhibited prominent age and/or sex differences in expression.

Results

Of the 314 miRNAs found to be expressed, 214 were differentially expressed; 65 and 212 miRNAs showed significant (false discovery rate (FDR) <5% and ≥1.5-fold change) sex- and age-related differences in expression, respectively. Thirty-eight miRNAs showed 2-week-specific expression, of which 31 miRNAs were found to be encoded within the Dlk1-Dio3 cluster located on chromosome 6. This cluster has been associated with tissue proliferation and differentiation, and liver energy homeostasis in postnatal development. Predictive pathway analysis linked sex-biased miRNA expression with sexually dimorphic molecular functions and toxicological functions that may reflect sex differences in hepatic physiology and disease. The expression of miRNAs (miR-18a, miR-99a, and miR-203, miR-451) was also found to associate with specific sexually dimorphic hepatic histopathology. The expression of miRNAs involved in regulating cell death, cell proliferation, and cell cycle was found to change as the rats matured from adult to old age.

Conclusions

Overall, significant age- and sex-related differences in liver miRNA expression were identified and linked to histopathological findings and predicted functional pathways that may underlie susceptibilities to liver toxicity and disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13293-017-0127-9) contains supplementary material, which is available to authorized users.

miR-18a-5p Inhibits Sub-pleural Pulmonary Fibrosis by Targeting TGF-β Receptor II

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease that typically leads to respiratory failure and death within 3-5 years of diagnosis. Sub-pleural pulmonary fibrosis is a pathological hallmark of IPF. Bleomycin treatment of mice is a an established pulmonary fibrosis model. We recently showed that bleomycin-induced epithelial-mesenchymal transition (EMT) contributes to pleural mesothelial cell (PMC) migration and sub-pleural pulmonary fibrosis. MicroRNA (miRNA) expression has recently been implicated in the pathogenesis of IPF. However, changes in miRNA expression in PMCs and sub-pleural fibrosis have not been reported. Using cultured PMCs and a pulmonary fibrosis animal model, we found that miR-18a-5p was reduced in PMCs treated with bleomycin and that downregulation of miR-18a-5p contributed to EMT of PMCs. Furthermore, we determined that miR-18a-5p binds to the 3' UTR region of transforming growth factor β receptor II (TGF-βRII) mRNA, and this is associated with reduced TGF-βRII expression and suppression of TGF-β-Smad2/3 signaling. Overexpression of miR-18a-5p prevented bleomycin-induced EMT of PMC and inhibited bleomycin-induced sub-pleural fibrosis in mice. Taken together, our data indicate that downregulated miR-18a-5p mediates sub-pleural pulmonary fibrosis through upregulation of its target, TGF-βRII, and that overexpression of miR-18a-5p might therefore provide a novel approach to the treatment of IPF.

The role of miR-497-5p in myofibroblast differentiation of LR-MSCs and pulmonary fibrogenesis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and fatal fibrotic lung disease characterized by profound changes in stem cell differentiation, epithelial cell phenotypes and fibroblast proliferation. In our study, we found that miR-497-5p was significantly upregulated both during myofibroblast differentiation of lung resident mesenchymal stem cells (LR-MSCs) and in the lung tissues of a pulmonary fibrosis model. In addition, as determined by luciferase assays and Western blot analysis, reversion-inducing cysteine-rich protein with kazal motifs (Reck) was identified to be one of the target genes of miR-497-5p, and Reck could suppress the expression of matrix metalloproteinase-2 (Mmp2) and Mmp9, which could activate latent transforming growth factor-β1 (TGF-β1). To test the potential therapeutic significance of this miRNA, we modulated the expression of miR-497-5p in LR-MSCs and relevant animal models. The results demonstrated that upregulation of miR-497-5p could induce LR-MSCs to differentiate into myofibroblasts and promote pulmonary fibrogenesis, while inhibition of its expression could effectively retard these processes. In conclusion, our work supports that controlling pulmonary fibrogenesis via inhibition of miR-497-5p expression may provide a potential therapeutic strategy for IPF.

Mesenchymal stem cells as novel micro-ribonucleic acid delivery vehicles in kidney disease

MicroRNAs (miRNAs) are short single strands of RNA responsible for post-transcriptional regulation of gene expression and have been implicated in the pathogenesis of chronic kidney disease (CKD). Emerging evidence reports that miRNAs can reduce kidney fibrosis through regulation of targets associated with collagen and extracellular matrix accumulation. However, the development of miRNA therapies has been hampered by the lack of targeted and sustainable methods of systemic miRNA delivery. Mesenchymal stem cells (MSCs) provide a promising miRNA delivery platform to overcome toxicity, the potential for insertional mutations and the low efficiency of previous methods. MSCs are endogenously immunoprivileged and home to sites of inflammation. They also release trophic growth factors to modulate the immune system, alter the polarization of macrophages and provide renal protection and repair. The potential to engineer MSCs to express or overexpress miRNAs, released by exosomes, may enhance their natural functions. Clinical studies are already being conducted individually for the use of miRNAs in cancer and MSCs in diseases associated with CKD. Hence, the combination of miRNAs and MSCs may provide an unparalleled cell-based therapy for treating CKD.

miR-27b inhibits fibroblast activation via targeting TGFβ signaling pathway

Background

MicroRNAs are a group of small RNAs that regulate gene expression at the posttranscriptional level. They regulate almost every aspect of cellular processes. In this study, we investigated whether miR-27b regulates pulmonary fibroblast activation.

Results

We found that miR-27b was down-regulated in fibrotic lungs and fibroblasts from an experimental mouse model of pulmonary fibrosis. The overexpression of miR-27b with a lentiviral vector inhibited TGFβ1-stimulated mRNA expression of collagens (COL1A1, COL3A1, and COL4A1) and alpha-smooth muscle actin, and protein expression of Col3A1 and alpha-smooth muscle actin in LL29 human pulmonary fibroblasts. miR-27b also reduced contractile activity of LL29. TGFβ receptor 1 and SMAD2 were identified as the targets of miR-27b by 3’-untranslated region luciferase reporter and western blotting assays.

Conclusions

Our results suggest that miR-27b is an anti-fibrotic microRNA that inhibits fibroblast activation by targeting TGFβ receptor 1 and SMAD2. This discovery may provide new targets for therapeutic interventions of idiopathic pulmonary fibrosis.

TGF-β/Smad3 signalling regulates the transition of bone marrow-derived macrophages into myofibroblasts during tissue fibrosis

Myofibroblasts are a main cell-type of collagen-producing cells during tissue fibrosis, but their origins remains controversial. While bone marrow-derived myofibroblasts in renal fibrosis has been reported, the cell origin and mechanisms regulating their transition into myofibroblasts remain undefined. In the present study, cell lineage tracing studies by adoptive transfer of GFP+ or dye-labelled macrophages identified that monocyte/macrophages from bone marrow can give rise to myofibroblasts via the process of macrophage-myofibroblast transition (MMT) in a mouse model of unilateral ureteric obstruction. The MMT cells were a major source of collagen-producing fibroblasts in the fibrosing kidney, accounting for more than 60% of α-SMA+ myofibroblasts. The MMT process occurred predominantly within M2-type macrophages and was regulated by TGF-β/Smad3 signalling as deletion of Smad3 in the bone marrow compartment of GFP+ chimeric mice prevented the M2 macrophage transition into the MMT cells and progressive renal fibrosis. In vitro studies in Smad3 null bone marrow macrophages also showed that Smad3 was required for TGF-β1-induced MMT and collagen production. In conclusion, we have demonstrated that bone marrow-derived fibroblasts originate from the monocyte/macrophage population via a process of MMT. This process contributes to progressive renal tissue fibrosis and is regulated by TGF-β/Smad3 signalling.

Overexpression of miR-29b reduces collagen biosynthesis by inhibiting heat shock protein 47 during skin wound healing

Skin scar formation is characterized by excessive synthesis and aberrant deposition of collagens during wound healing. MicroRNAs are endogenous gene regulators critically involved in diverse biological events including skin scar formation and hold considerable promise as therapeutic targets. However, the detailed molecular mechanisms responsible for collagen production during skin wound repair and scar formation remain incompletely known. Here our data revealed that significant downregulation of miR-29b and upregulation of heat shock protein 47 (HSP47) were observed during wound healing in both excisional and burn wound models and also detected in facial skin scar as compared to adjacent healthy skin. HSP47, a specific chaperon for collagen production and secretion, was identified as a novel and direct post-transcriptional target of miR-29b in skin fibroblasts via bioinformatics prediction and experimental validation. Moreover, the regulatory functions of miR-29b in collagen biosynthesis are partially achieved through modulating HSP47 expression in skin fibroblasts. Furthermore, the profibrotic growth factor TGF-β1 inhibited miR-29b transcription by activating TGF-β/Smads signaling and in turn depressed HSP47 and enhanced collagen 1 production. In contrast, the proinflammatory cytokines IL-1β and TNF-α significantly induced miR-29b transcription via activating NF-κB signaling but had no significant effect on HSP47 and collagen production in skin fibroblasts. Importantly, local delivery of miR-29b lentiviral particles inhibited HSP47 expression and collagen biosynthesis as well as suppressed angiogenesis, thus reducing scar formation in an excisional wound splinting model. Collectively, our data reveal that miR-29b can reduce collagen biosynthesis during skin wound healing likely via post-transcriptional inhibition of HSP47 expression. These findings also suggest that therapeutic targeting of miR-29b/HSP47 might be a viable alternative strategy to prevent or reduce scar formation.

Inflammatory macrophages can transdifferentiate into myofibroblasts during renal fibrosis

Myofibroblasts play a central role in renal fibrosis although the origin of these cells remains controversial. We recently reported that bone marrow-derived macrophages can give rise to myofibroblasts through macrophage to myofibroblast transition (MMT). However, several important issues remain to be addressed, including whether MMT occurs in human kidney disease and verification of the MMT process through lineage tracing. Biopsies from a cohort of 58 patients with various forms of kidney disease were examined for MMT cells that co-express macrophage (CD68) and myofibroblast (α-smooth muscle actin, α-SMA) markers. MMT cells were evident in active fibrotic lesions, but were largely absent in acute inflammatory or sclerotic lesions, suggesting that MMT cells contribute to progressive renal fibrosis. Fate-mapping studies in LysM^CreTomato mice identified substantial numbers of Tomato⁺ myeloid cells with F4/80⁺ macrophage phenotype expressing α-SMA and collagen I in the unilateral ureteral obstructive model of renal fibrosis, providing direct evidence for the MMT process during the development of renal fibrosis. In addition, MMT cells had a predominant M2 phenotype in both human and mouse renal fibrosis. Finally, selective depletion of myeloid cells via diphtheria toxin in LysM^CreiDTR mice largely abolished macrophage infiltration and MMT cells in the obstructed kidney and substantially reduced accumulation of α-SMA⁺ myofibroblasts and collagen deposition, revealing a pathogenic role for inflammatory macrophages in MMT and tissue fibrosis. In conclusion, these findings provide substantial new data to support the postulate that macrophages can directly transdifferentiate into collagen-producing myofibroblasts in human and experimental kidney disease.

Emerging drugs and therapeutics for systemic sclerosis

INTRODUCTION

Treatment of systemic sclerosis (SSc) is challenging despite advances in medical therapeutics for other rheumatologic diseases. Significant disease modifying therapy is lacking for most patients with SSc, due to the heterogeneous multisystem nature of SSc and its complex pathophysiology. The emergence of organ based management strategies has provided guidance in patient care as well as research and drug development. Areas covered: Design and development of new compounds focused on the underlying fibrotic disease processes have been sparse. Therefore, organ based strategies with targeted approaches have been directed towards the most devastating and life threatening features of systemic sclerosis. These include pulmonary arterial hypertension, interstitial lung disease, peripheral vasculopathy and skin thickening. In this context, new treatment regimens using older drugs as well as discovery of novel compounds based on recent insights of the disease pathophysiology are discussed. Expert opinion: Systemic sclerosis is a heterogeneous rare disease that carries a high burden of morbidity and mortality. Organ based management strategies have improved the natural history of systemic sclerosis using targeted interventions or strategies, particularly vascular features. However, more research is required to better understand disease mechanisms, including an ultimate unifying pathway that explains the multisystem nature of systemic sclerosis.

MicroRNAs in idiopathic pulmonary fibrosis: involvement in pathogenesis and potential use in diagnosis and therapeutics

MicroRNAs (miRNAs) are a class of phylogenetically conserved, non-coding short RNAs, 19-22 nt in length which suppress protein expression through base-pairing with the 3'-untranslated region of target mRNAs. miRNAs have been found to participate in cell proliferation, differentiation and apoptosis. Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and high lethality fibrotic lung disease for which currently there is no effective treatment. Some miRNAs have been reported to be involved in the pathogenesis of pulmonary fibrosis. In this review, we discuss the role of miRNAs in the pathogenesis, diagnosis and treatment of IPF.

MicroRNA-29c regulates apoptosis sensitivity via modulation of the cell-surface death receptor, Fas, in lung fibroblasts

MicroRNAs play an important role in the development and progression of various diseases, such as idiopathic pulmonary fibrosis (IPF). Although the accumulation of aberrant fibroblasts resistant to apoptosis is a hallmark in IPF lungs, the mechanism regulating apoptosis susceptibility is not fully understood. Here, we investigated the role of miR-29, which is the most downregulated microRNA in IPF lungs and is also known as a regulator of extracellular matrix (ECM), in the mechanism of apoptosis resistance. We found that functional inhibition of miR-29c caused resistance to Fas-mediated apoptosis in lung fibroblasts. Furthermore, experiments using miR-29c inhibitor and miR-29c mimic revealed that miR-29c regulated expression of the death receptor, Fas, and formation of death-inducing signaling complex leading to extrinsic apoptosis. The representative profibrotic transforming growth factor (TGF)-β downregulated the expression of miR-29c as well as Fas receptor and conferred resistance to apoptosis. We also found that introduction of miR-29c mimic abrogated these TGF-β-induced phenotypes of Fas repression and apoptosis resistance. The results presented here suggest that downregulation of miR-29 observed in IPF lungs may be associated with the apoptosis-resistant phenotype of IPF lung fibroblasts via downregulation of Fas receptor. Therefore, restoration of miR-29 expression in IPF lungs could not only inhibit the accumulation of ECM but also normalize the sensitivity to apoptosis in lung fibroblasts, which may be an effective strategy for treatment of IPF.

Sleeping Beauty transposition: from biology to applications

Sleeping Beauty (SB) is the first synthetic DNA transposon that was shown to be active in a wide variety of species. Here, we review studies from the last two decades addressing both basic biology and applications of this transposon. We discuss how host-transposon interaction modulates transposition at different steps of the transposition reaction. We also discuss how the transposon was translated for gene delivery and gene discovery purposes. We critically review the system in clinical, pre-clinical and non-clinical settings as a non-viral gene delivery tool in comparison with viral technologies. We also discuss emerging SB-based hybrid vectors aimed at combining the attractive safety features of the transposon with effective viral delivery. The success of the SB-based technology can be fundamentally attributed to being able to insert fairly randomly into genomic regions that allow stable long-term expression of the delivered transgene cassette. SB has emerged as an efficient and economical toolkit for safe and efficient gene delivery for medical applications.

Role of noncoding RNA in vascular remodelling

PURPOSE OF REVIEW

Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are becoming fundamentally important in the pathophysiology relating to injury-induced vascular remodelling. We highlight recent studies that demonstrate the involvement of ncRNAs in vein graft disease, in in-stent restenosis and in pulmonary arterial hypertension, with a particular focus on endothelial cell and vascular smooth muscle cell function. We also briefly discuss the emerging role of exosomal-derived ncRNAs and how this mechanism impacts on vascular function.

RECENT FINDINGS

ncRNAs have been described as novel regulators in the pathophysiology of vascular injury, inflammation, and vessel wall remodelling. In particular, several studies have demonstrated that manipulation of miRNAs can reduce the burden of pathological vascular remodelling. Such studies have also shown that exosomal miRNA-mediated, cell-to-cell communication between endothelial cells and vascular smooth muscle cells is critical in the disease process. In addition to miRNAs, lncRNAs are emerging as regulators of vascular function in health and disease. Although lncRNAs are complex in both their sheer numbers and mechanisms of action, identifying their contribution to vascular disease is essential.

SUMMARY

Given the important roles of ncRNAs in vascular injury and remodelling together will their capacity for cell-to-cell communication, manipulating ncRNA might provide novel therapeutic interventions.

PGMA-Based Star-Like Polycations with Plentiful Hydroxyl Groups Act as Highly Efficient miRNA Delivery Nanovectors for Effective Applications in Heart Diseases

Poly(glycidyl methacrylate)-based star-like polycations with rich hydrophilic hydroxyl groups can efficiently transfer miRNA into primary cardiac fibroblasts for effective applications in cardiac diseases, such as inhibition of cardiac fibrosis and hypertrophy.

Genome-wide analysis of aberrantly expressed microRNAs in bronchoalveolar lavage fluid from patients with silicosis

Background To identify differentially expressed miRNAs profiles in bronchoalveolar lavage fluid (BALF) from patients with silicosis and consider the potential contribution of miRNAs to silicosis.Methods miRNAs expression profiling were performed in the cell fraction of BALF samples obtained from 9 subjects (3 silicosis observation subjects, 3 stage I and stage II silicosis patients, respectively). The differential expression of two selected miRNAs hsa-miR-181c-5p and hsa-miR-29a-3p were confirmed by RT-qPCR. Furthermore, miRNAs Gene Ontology Enrichment categories and target mRNAs were determined based on miRWalk.Results We found 110 dysregulated miRNAs in silicosis samples, most of which showed a down-regulation trend. Microarray results were confirmed by RT-qPCR. With the observation group samples set as standards, stage I samples showed 123 differentially expressed miRNAs, and stage II 46. 23 miRNAs were dysregulated in both stages. Finally, functional enrichment analysis indicated that these miRNAs played an important role in various biological processes, including ECM-receptor interaction and endocytosis.Conclusions This is the first time to acquire the BALF-derived microRNAs expression profiling targeting to human silicosis. These results contribute to unravelling miRNAs involved in the pathogenesis of silicosis, and provide new tools of potential use of as biomarkers for diagnosis and/or therapeutic purposes.

The MicroRNA 29 Family Promotes Type II Cell Differentiation in Developing Lung

Lung alveolar type II cells uniquely synthesize surfactant, a developmentally regulated lipoprotein that is essential for breathing. Expression of the gene (SFTPA) encoding the major surfactant protein, SP-A, in midgestation human fetal lung (HFL) is dramatically induced by cyclic AMP (cAMP). cAMP induction of SP-A expression is repressed by transforming growth factor β (TGF-β) and by hypoxia. In this study, we found that expression of the microRNA 29 (miR-29) family was significantly upregulated in epithelial cells isolated from mouse fetal lung during late gestation and in epithelial cells isolated from HFL explants during type II cell differentiation in culture. miR-29 expression in cultured HFL epithelial cells was increased by cAMP and inhibited by hypoxia, whereas the miR-29 target, TGF-β2, was coordinately decreased. Knockdown of the miR-29 family in cultured HFL type II cells blocked cAMP-induced SP-A expression and accumulation of surfactant-containing lamellar bodies, suggesting their physiological relevance. This occurred through derepression of TGF-β signaling. Notably, cAMP increased binding of endogenous thyroid transcription factor 1 (TTF-1/Nkx2.1) to the miR-29ab1 promoter in HFL type II cells, and TTF-1 increased miR-29ab1 promoter-driven luciferase activity in cotransfection assays. Together, these findings identify miR-29 family members as TTF-1-driven mediators of SP-A expression and type II cell differentiation through repression of TGF-β signaling.

Age-driven developmental drift in the pathogenesis of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and usually lethal disease of unknown aetiology. A growing body of evidence supports that IPF represents an epithelial-driven process characterised by aberrant epithelial cell behaviour, fibroblast/myofibroblast activation and excessive accumulation of extracellular matrix with the subsequent destruction of the lung architecture. The mechanisms involved in the abnormal hyper-activation of the epithelium are unclear, but we propose that recapitulation of pathways and processes critical to embryological development associated with a tissue specific age-related stochastic epigenetic drift may be implicated. These pathways may also contribute to the distinctive behaviour of IPF fibroblasts. Genomic and epigenomic studies have revealed that wingless/Int, sonic hedgehog and other developmental signalling pathways are reactivated and deregulated in IPF. Moreover, some of these pathways cross-talk with transforming growth factor-β activating a profibrotic feedback loop. The expression pattern of microRNAs is also dysregulated in IPF and exhibits a similar expression profile to embryonic lungs. In addition, senescence, a process usually associated with ageing, which occurs early in alveolar epithelial cells of IPF lungs, likely represents a conserved programmed developmental mechanism. Here, we review the major developmental pathways that get twisted in IPF, and discuss the connection with ageing and potential therapeutic approaches.

The critical role of epigenetics in systemic lupus erythematosus and autoimmunity

One of the major disappointments in human autoimmunity has been the relative failure on genome-wide association studies to provide "smoking genetic guns" that would explain the critical role of genetic susceptibility to loss of tolerance. It is well known that autoimmunity refers to the abnormal state that the dysregulated immune system attacks the healthy cells and tissues due to the loss of immunological tolerance to self-antigens. Its clinical outcomes are generally characterized by the presence of autoreactive immune cells and (or) the development of autoantibodies, leading to various types of autoimmune disorders. The etiology and pathogenesis of autoimmune diseases are highly complex. Both genetic predisposition and environmental factors such as nutrition, infection, and chemicals are implicated in the pathogenic process of autoimmunity, however, how much and by what mechanisms each of these factors contribute to the development of autoimmunity remain unclear. Epigenetics, which refers to potentially heritable changes in gene expression and function that do not involve alterations of the DNA sequence, has provided us with a brand new key to answer these questions. In the recent decades, increasing evidence have demonstrated the roles of epigenetic dysregulation, including DNA methylation, histone modification, and noncoding RNA, in the pathogenesis of autoimmune diseases, especially systemic lupus erythematosus (SLE), which have shed light on a new era for autoimmunity research. Notably, DNA hypomethylation and reactivation of the inactive X chromosome are two epigenetic hallmarks of SLE. We will herein discuss briefly how genetic studies fail to completely elucidate the pathogenesis of autoimmune diseases and present a comprehensive review on landmark epigenetic findings in autoimmune diseases, taking SLE as an extensively studied example. The epigenetics of other autoimmune diseases such as rheumatic arthritis, systemic sclerosis and primary biliary cirrhosis will also be summarized. Importantly we emphasize that the stochastic processes that lead to DNA modification may be the lynch pins that drive the initial break in tolerance.

The correlation between miR-200c and the severity of interstitial lung disease associated with different connective tissue diseases

OBJECTIVES

To explore the correlation between microRNA (miR)-200c and the severity of interstitial lung disease (ILD) associated with connective tissue diseases (CTDs).

METHOD

We recruited 218 patients with CTDs who were evaluated with high-resolution computed tomography (HRCT) and the pulmonary function test (PFT). Peripheral blood mononuclear cells (PBMCs) were acquired from 23 patients with systemic sclerosis (SSc), 29 with dermatomyositis/polymyositis (DM/PM), 30 with primary Sjögren's syndrome (pSS), 47 with rheumatoid arthritis (RA), and 23 normal controls to detect the expression level of miR-200c by quantitative reverse transcription polymerase chain reaction (QRT-PCR). miR-200c levels were compared among the different disease groups, between the group with ILD (CTD+ILD) and the group without ILD (CTD-ILD), and between mild and severe ILD groups. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were compared among the different CTD groups and the different CTD+ILD groups.

RESULTS

The miR-200c level in the SSc group was significantly higher than in the DM/PM, pSS, and RA groups, and the levels in the DM/PM and pSS groups were significantly higher than in the RA group. The level of miR-200c in the CTD+ILD group was significantly higher than in the CTD-ILD group, and the level in the severe ILD group was significantly higher than in the mild ILD group. FVC and FEV1 were significantly different among the different CTD groups, and among the different CTD+ILD groups. There was a negative correlation between the level of miR-200c and FVC and FEV1.

CONCLUSIONS

The level of miR-200c was positively correlated with the severity of ILD, and miR-200c in PBMCs could be a biomarker of the severity of ILD in CTDs.

microRNAs in Diabetic Kidney Disease

Diabetes and diabetic kidney diseases have continually exerted a great burden on our society. Although the recent advances in medical research have led to a much better understanding of diabetic kidney diseases, there is still no successful strategy for effective treatments for diabetic kidney diseases. Recently, treatment of diabetic kidney diseases relies either on drugs that reduce the progression of renal injury or on renal replacement therapies, such as dialysis and kidney transplantation. On the other hand, searching for biomarkers for early diagnosis and effective therapy is also urgent. Discovery of microRNAs has opened to a novel field for posttranscriptional regulation of gene expression. Results from cell culture experiments, experimental animal models, and patients under diabetic conditions reveal the critical role of microRNAs during the progression of diabetic kidney diseases. Functional studies demonstrate not only the capability of microRNAs to regulate expression of target genes, but also their therapeutic potential to diabetic kidney diseases. The existence of microRNAs in plasma, serum, and urine suggests their possibility to be biomarkers in diabetic kidney diseases. Thus, identification of the functional role of microRNAs provides an essentially clinical impact in terms of prevention and treatment of progression in diabetic kidney diseases as it enables us to develop novel, specific therapies and diagnostic tools for diabetic kidney diseases.

Circulating miR-29a and miR-150 correlate with delivered dose during thoracic radiation therapy for non-small cell lung cancer

BACKGROUND

Risk of normal tissue toxicity limits the amount of thoracic radiation therapy (RT) that can be routinely prescribed to treat non-small cell lung cancer (NSCLC). An early biomarker of response to thoracic RT may provide a way to predict eventual toxicities-such as radiation pneumonitis-during treatment, thereby enabling dose adjustment before the symptomatic onset of late effects. MicroRNAs (miRNAs) were studied as potential serological biomarkers for thoracic RT. As a first step, we sought to identify miRNAs that correlate with delivered dose and standard dosimetric factors.

METHODS

We performed miRNA profiling of plasma samples obtained from five patients with Stage IIIA NSCLC at five dose-points each during radical thoracic RT. Candidate miRNAs were then assessed in samples from a separate cohort of 21 NSCLC patients receiving radical thoracic RT. To identify a cellular source of circulating miRNAs, we quantified in vitro miRNA expression intracellularly and within secreted exosomes in five NSCLC and stromal cell lines.

RESULTS

miRNA profiling of the discovery cohort identified ten circulating miRNAs that correlated with delivered RT dose as well as other dosimetric parameters such as lung V20. In the validation cohort, miR-29a-3p and miR-150-5p were reproducibly shown to decrease with increasing radiation dose. Expression of miR-29a-3p and miR-150-5p in secreted exosomes decreased with radiation. This was concomitant with an increase in intracellular levels, suggesting that exosomal export of these miRNAs may be downregulated in both NSCLC and stromal cells in response to radiation.

CONCLUSIONS

miR-29a-3p and miR-150-5p were identified as circulating biomarkers that correlated with delivered RT dose. miR-150 has been reported to decrease in the circulation of mammals exposed to radiation while miR-29a has been associated with fibrosis in the human heart, lungs, and kidneys. One may therefore hypothesize that outlier levels of circulating miR-29a-3p and miR-150-5p may eventually help predict unexpected responses to radiation therapy, such as toxicity.

Role of microRNAs in gastrointestinal smooth muscle fibrosis and dysfunction: novel molecular perspectives on the pathophysiology and therapeutic targeting

MicroRNAs (miRNAs) belong to a group of short noncoding RNA molecules with important roles in cellular biology. miRNAs regulate gene expression by repressing translation or degrading the target mRNA. Recently, a growing body of evidence suggests that miRNAs are implicated in many diseases and could be potential biomarkers. Fibrosis and/smooth muscle (SM) dysfunction contributes to the morbidity and mortality associated with several diseases of the gastrointestinal tract (GIT). Currently available therapeutic modalities are unsuccessful in efficiently blocking or reversing fibrosis and/or SM dysfunction. Recent understanding of the role of miRNAs in signaling pathway of fibrogenesis and SM phenotype switch has provided a new insight into translational research. However, much is still unknown about the molecular targets and therapeutic potential of miRNAs in the GIT. This review discusses miRNA biology, pathophysiology of fibrosis, and aging- associated SM dysfunction in relation to the deregulation of miRNAs in the GIT. We also highlight the role of selected miRNAs associated with fibrosis and SM dysfunction-related diseases of the GIT.

MicroRNA-29b inhibits TGF-β1-induced fibrosis via regulation of the TGF-β1/Smad pathway in primary human endometrial stromal cells

Transforming growth factor (TGF)-β1 has a key role in the regulation of fibrosis and organ dysfunction. During the pathogenesis and progression of vital organ fibrosis, the microRNA (miR)-29 family is irregularly downregulated and exogenous supplementation of miR-29b has a strong anti-fibrotic capacity. However, whether TGF-β1 is able to provoke endometrial fibrosis, and the role of miR-29 in endometrial fibrosis remain unclear. In the present study, RT-qPCR, immunocytochemistry, western blot analysis, scanning electron microscopy, immunofluorescence staining, cell proliferation assay and flow cytometric analysis were employed. The results demonstrated that the expression levels of collagen, type 1, alpha 1 (COL1A1), α-smooth muscle actin (α-SMA) and phosphorylated (p)-Smad2/3 were increased, whereas miR-29b and maternally expressed gene 3 (MEG3) were decreased in primary endometrial stromal cells (ESCs) in response to TGF-β1 stimulation, in a time and dose-dependent manner. Furthermore, overexpression of miR-29b markedly reduced the expression levels of COL1A1 and α-SMA, and decreased the expression and nuclear accumulation of p-Smad2/3. In addition, ectopic overexpression of miR-29b increased the expression levels of MEG3, inhibited myofibroblast-like cell proliferation and induced apoptosis. These findings indicated that miR-29b may have a significant anti-fibrotic role, and may attenuate TGF-β1-induced fibrosis in ESCs. Therefore, exogenous miR-29b may serve as a potential therapeutic agent for the treatment of endometrial fibrosis.

Microarray Study of Pathway Analysis Expression Profile Associated with MicroRNA-29a with Regard to Murine Cholestatic Liver Injuries

Accumulating evidence demonstrates that microRNA-29 (miR-29) expression is prominently decreased in patients with hepatic fibrosis, which consequently stimulates hepatic stellate cells' (HSCs) activation. We used a cDNA microarray study to gain a more comprehensive understanding of genome-wide gene expressions by adjusting miR-29a expression in a bile duct-ligation (BDL) animal model.

METHODS

Using miR-29a transgenic mice and wild-type littermates and applying the BDL mouse model, we characterized the function of miR-29a with regard to cholestatic liver fibrosis. Pathway enrichment analysis and/or specific validation were performed for differentially expressed genes found within the comparisons.

RESULTS

Analysis of the microarray data identified a number of differentially expressed genes due to the miR-29a transgene, BDL, or both. Additional pathway enrichment analysis revealed that TGF-β signaling had a significantly differential activated pathway depending on the occurrence of miR-29a overexpression or the lack thereof. Furthermore, overexpression was found to elicit changes in Wnt/β-catenin after BDL.

CONCLUSION

This study verified that an elevated miR-29a level could alleviate liver fibrosis caused by cholestasis. Furthermore, the protective effects of miR-29a correlate with the downregulation of TGF-β and associated with Wnt/β-catenin signal pathway following BDL.

MicroRNA-29b Inhibits Endometrial Fibrosis by Regulating the Sp1-TGF-β1/Smad-CTGF Axis in a Rat Model

Intrauterine adhesions (IUAs), which are characterized by endometrial fibrosis, increase the risk of secondary infertility and recurrent miscarriage. MicroRNA-29 (miR-29) is a potent inhibitor of TGF-β1/Smad signaling. In this study, we investigated the therapeutic potential of agomir-29b, an miR-29b mimic, in endometrial fibrosis induced by dual injury (uterine curettage and lipopolysaccharide treatment) in a rat model of IUA and explored the underlying mechanism. We found that injured rats developed endometrial fibrosis characterized by increased COL1A1 and α-smooth muscle actin expression and decreased E-cadherin expression, associated with a loss of miR-29b. Overexpression of miR-29b before injury prevented endometrial fibrosis including collagen accumulation and epithelial-mesenchymal transition. Delay of agomir-29b treatment until endometrial fibrosis was established on day 4 also halted the progression of disease. Further experiments indicated that miR-29b inhibited endometrial fibrosis via blockade of the Sp1-TGF-β1/Smad-CTGF pathway. In conclusion, agomir-29b may act as a novel and effective therapeutic agent against IUAs.

miR-26a suppresses EMT by disrupting the Lin28B/let-7d axis: potential cross-talks among miRNAs in IPF

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and highly lethal fibrotic lung disease with unknown cause or cure. Although some microRNAs (miRNAs), such as miR-26a and let-7d, have been confirmed, the contribution to the pathophysiological processes of IPF, the roles of miRNAs and intrinsic links between them in fibrotic lung diseases are not yet well understood. In this study, we found that Lin28B could induce the process of epithelial-mesenchymal transition (EMT) by inhibiting let-7d, whereas inhibition of Lin28B mitigated TGF-β1-induced fibrogenesis and attenuated EMT in both cultured A549 cells and MLE-12 cells. More importantly, over-expression of miR-26a could simultaneously enhance the expression of let-7d in A549 cells, and further study confirmed that Lin28B was one of the direct targets of miR-26a, which mediates, at least in part, the regulatory effects of miR-26a on the biogenesis of let-7d. Finally, we constructed a regulatory network among miRNAs involved in the progression of IPF. Taken together, our study deciphered the essential role of Lin28B in the pathogenesis of EMT, and unraveled a novel mechanism that miR-26a is a modulator of let-7d. This study also defines the miRNAs network involved in IPF, which may have implications for developing new strategies for pulmonary fibrosis.

KEY MESSAGE

Upregulation of Lin28B contributes to idiopathic pulmonary fibrosis. Lin28B causes epithelial-mesenchymal transition (EMT) by inhibition of let-7d. Lin28B is one of the targets of microRNA-26a. miR-26a enhances the expression of let-7d via targeting regulation of Lin28B. A regulatory network among miRNAs involved in the progression of IPF.

microRNA-29b prevents liver fibrosis by attenuating hepatic stellate cell activation and inducing apoptosis through targeting PI3K/AKT pathway

microRNA-29b (miR-29b) is known to be associated with TGF-β-mediated fibrosis, but the mechanistic action of miR-29b in liver fibrosis remains unclear and is warranted for investigation. We found that miR-29b was significantly downregulated in human and mice fibrotic liver tissues and in primary activated HSCs. miR-29b downregulation was directly mediated by Smad3 through binding to the promoter of miR-29b in hepatic stellate cell (HSC) line LX1, whilst miR-29b could in turn suppress Smad3 expression. miR-29b transduction in the liver of mice prevented CCl₄ induced-fibrogenesis, concomitant with decreased expression of α-SMA, collagen I and TIMP-1. Ectopic expression of miR-29b in activated HSCs (LX-1, HSC-T6) inhibited cell viability and colony formation, and caused cell cycle arrest in G1 phase by downregulating cyclin D1 and p21^cip1. Further, miR-29b induced apoptosis in HSCs mediated by caspase-9 and PARP. miR-29b inhibited its downstream effectors of PIK3R1 and AKT3 through direct targeting their 3′UTR regions. Moreover, knockdown of PIK3R1 or AKT3 suppressed α-SMA and collagen I and induced apoptosis in both HSCs and in mice. In conclusion, miR-29b prevents liver fibrogenesis by inhibiting HSC activation and inducing HSC apoptosis through inhibiting PI3K/AKT pathway. These results provide novel mechanistic insights for the anti-fibrotic effect of miR-29b.

MicroRNAs in fibrosis: opportunities and challenges

MicroRNAs (miRNAs) are small, non-coding RNAs that mediate mRNA cleavage, translational repression or mRNA destabilisation and are around 22–25 nucleotides in length via partial complementary binding to the 3′ untranslated region in target transcripts. They are master regulators of gene expression. Fibrosis is an important cause of morbidity and mortality in the world, and there are currently no accepted treatments for fibrosis. Many novel miRNAs are now associated with fibrosis, both organ-specific and systemic, as in the prototypical fibrotic disease systemic sclerosis. Recently, the targets of these altered miRNAs have been validated and defined new biochemical pathways. Dysregulated miRNAs are amenable to therapeutic modulation. This review will examine the role of miRNAs in fibrosis and the opportunities and challenges of targeting them.