miR-200b is involved in intestinal fibrosis of Crohn's disease

Potential application of miRNAs as diagnostic and therapeutic tools in chronic pancreatitis

Chronic pancreatitis (CP) is a progressive inflammatory disease typified by end-stage fibrosis. This disease can also increase the risk of pancreatic cancer. The associated diagnosis, pain and other complications further add to the burden of disease management. In recent years, significant progress has been achieved in identifying miRNAs and their physiological functions, including mRNA repression and protein expression control. Given the extensive effort made on miRNA research, a close correlation has been discovered between certain types of miRNAs and disease progression, particularly for tissue fibrosis. Designing miRNA-related tools for disease diagnosis and therapeutic treatments presents a novel and potential research frontier. In the current review, we discuss various miRNAs closely interacting with CP, as well as the possible development of targeted miRNA therapies in managing this disease.

Stromal miR-200s contribute to breast cancer cell invasion through CAF activation and ECM remodeling

The activation of cancer-associated fibroblasts (CAFs) is a key event in tumor progression, and alternative extracellular matrix (ECM) proteins derived from CAFs induce ECM remodeling and cancer cell invasion. Here we found that miR-200 s, which are generally downregulated in activated CAFs in breast cancer tissues and in normal fibroblasts (NFs) activated by breast cancer cells, are direct mediators of NF reprogramming into CAFs and of ECM remodeling. NFs with downregulated miR-200 s displayed the traits of activated CAFs, including accelerated migration and invasion. Ectopic expression of miR-200 s in CAFs at least partially restored the phenotypes of NFs. CAF activation may be governed by the targets of miR-200 s, Fli-1 and TCF12, which are responsible for cell development and differentiation; Fli-1 and TCF12 were obviously elevated in CAFs. Furthermore, miR-200 s and their targets influenced collagen contraction by CAFs. The upregulation of fibronectin and lysyl oxidase directly by miR-200 or indirectly through Fli-1 or TCF12 contributed to ECM remodeling, triggering the invasion and metastasis of breast cancer cells both in vitro and vivo. Thus, these data provide important and novel insights into breast CAF activation and ECM remodeling, which trigger tumor cell invasion.

Intestinal fibrosis in Crohn's disease: role of microRNAs as fibrogenic modulators, serum biomarkers, and therapeutic targets

Inflammation often precedes fibrosis and stricture formation in patients with Crohn's disease. Established medical therapies reduce inflammation, but there are currently no specific therapies to prevent fibrosis or treat established fibrosis. Our understanding of the pathogenic processes underpinning fibrogenesis is limited compared with our knowledge of the events initiating and propagating inflammation. There are several biomarkers for intestinal inflammation, but there are none that reflect the development of fibrosis. MicroRNAs (miRNAs) are regulators of cellular activities including inflammation and fibrosis and may serve as biomarkers of disease processes. Differential serum and mucosal miRNA expression profiles have been identified between patients with inflammatory bowel disease with active and inactive inflammatory disease. In contrast, studies in patients with fibrotic phenotypes are comparatively few, although specific miRNAs have defined roles in the development of fibrosis in other organ systems. Here, we discuss the most recent research on miRNA and fibrogenesis with a particular emphasis on Crohn's disease. We also anticipate the potential of miRNAs in fulfilling current unmet translational needs in this patient group by focusing on the role of miRNAs as modulators of fibrogenesis and on their potential value as serum biomarkers and therapeutic targets in the management of fibrosis.

A microrna screen to identify regulators of peritoneal fibrosis in a rat model of peritoneal dialysis

Background

Peritoneal fibrosis is a common complication in patients treated with long-term peritoneal dialysis. The aim of this study was to identify the microRNAs (miRNAs) involved in regulation of peritoneal fibrosis in a rat model of peritoneal dialysis.

Methods

Twenty-four Sprague–Dawley (SD) rats were randomly allocated into three groups: (i) Control group (Cg, n = 8); (ii) Saline group (Sg, n = 8): daily intraperitoneal injection with 0.9% normal saline; (iii) Hypertonic dialysate group (HDg, n = 8): daily intraperitoneal injection with 4.25% peritoneal dialysis solution. Rats were sacrificed after four weeks for histological evaluation of peritoneal membrane and the expression of α-SMA and COL-1. A miRNA screen was performed using microarray analysis to identify differentially expressed miRNAs, which were then validated by real-time PCR.

Results

Compared with the control and the saline groups, hypertonic dialysate group showed impaired peritoneal function accompanied by a spectrum of morphological changes including thicker peritoneal membrane, higher collagen deposition, infiltration of mononuclear cells and neovascularization in the peritoneum. Increased mRNA and protein levels of α-SMA and COL-1 were observed in hypertonic dialysate group, indicating the progression of peritoneal fibrosis. The miRNA screen identified 8 significantly down-regulated miRNAs (miR-31, miR-93, miR-100, miR-152, miR-497, miR-192, miR-194 and miR-200b) and one highly up-regulated miRNA (miR-122) in the hypertonic dialysate group. The results were confirmed by real-time PCR.

Conclusions

Altered miRNA expression in peritoneum was found in the rat model of peritoneal fibrosis, indicating that these miRNAs may be associated with pathogenesis of peritoneal fibrosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0039-z) contains supplementary material, which is available to authorized users.

Hallmarks of epithelial to mesenchymal transition are detectable in Crohn's disease associated intestinal fibrosis

BACKGROUND

Intestinal fibrosis and subsequent stricture formation represent frequent complications of Crohn's disease (CD). In many organs, fibrosis develops as a result of epithelial to mesenchymal transition (EMT). Recent studies suggested that EMT could be involved in intestinal fibrosis as a result of chronic inflammation. Here, we investigated whether EMT might be involved in stricture formation in CD patients.

METHODS

Human colonic tissue specimens from fibrotic areas of 18 CD and 10 non-IBD control patients were studied. Immunohistochemical staining of CD68 (marker for monocytes/macrophages), transforming growth factor-β1 (TGFβ1), β-catenin, SLUG, E-.cadherin, α-smooth muscle actin and fibroblast activation protein (FAP) were performed using standard techniques.

RESULTS

In fibrotic areas in the intestine of CD patients, a large number of CD68-positive mononuclear cells was detectable suggesting an inflammatory character of the fibrosis. We found stronger expression of TGFβ1, the most powerful driving force for EMT, in and around the fibrotic lesions of CD patients than in non-IBD control patients. In CD patients membrane staining of β-catenin was generally weaker than in control patients and more cells featured nuclear staining indicating transcriptionally active β-catenin, in fibrotic areas. In these regions we also detected nuclear localisation of the transcription factor, SLUG, which has also been implicated in EMT pathogenesis. Adjacent to the fibrotic tissue regions, we observed high levels of FAP, a marker of reactive fibroblasts.

CONCLUSIONS

We demonstrate the presence of EMT-associated molecules in fibrotic lesions of CD patients. These findings support the hypothesis that EMT might play a role for the development of CD-associated intestinal fibrosis.

Homocysteine promotes intestinal fibrosis in rats with trinitrobenzene sulfonic acid-induced colitis

BACKGROUND AND AIM

Previous studies have revealed significantly increased levels of plasma and mucosal homocysteine (Hcy) in patients with Crohn's disease (CD); however, whether Hcy is involved in intestinal fibrosis of CD remains unclear. This study aimed to investigate the effects of Hcy on intestinal fibrosis in TNBS/ethanol-induced colitis and to elucidate its potential mechanisms.

METHODS

Sprague-Dawley rats were divided into 4 groups: normal control, normal + Hcy injection, TNBS model and TNBS model + Hcy injection. Hyperhomocysteinemia was induced by subcutaneous injection of Hcy. DAI, CMDI and HI were calculated to evaluate the severity of colitis. Masson trichrome staining was performed to assess the severity of fibrosis. The plasma and mucosal levels of Hcy were measured by HPLC-FD. The levels of IL-1β, IL-6, TNF-α, TGF-β1, CTGF, MMP-2,9 and collagen I, III in the colon were determined by ELISA, and the mRNA expressions of TGF-β1, MMP-2,9 and TIMP-1 were detected by RT-PCR.

RESULTS

Hcy was found to increase the scores of DAI, CMDI and HI; levels of IL-1β, Il-6, TNF-α, TGF-β1, CTGF, MMP-2,9 and collagen I, III; and mRNA expressions of TGF-β1, MMP-2,9 and TIMP-1 in colonic tissue of rats with TNBS/ethanol-induced colitis.

CONCLUSIONS

Hcy promotes intestinal fibrosis in rats with TNBS/ethanol-induced colitis, the underlying mechanisms of which may be attributed to its effects of increasing inflammatory damage, promoting the expression of profibrogenic cytokines and influencing MMPs/TIMPs balance.

Combined silencing of TGF-β2 and Snail genes inhibit epithelial-mesenchymal transition of retinal pigment epithelial cells under hypoxia

BACKGROUND

The formation of scar-like fibrous tissue in age-related macular degeneration (AMD) is associated with hypoxia. Under hypoxia, retinal pigment epithelial (RPE) cells can secret more transforming growth factor-β2 (TGF-β2), which is determined to induce epithelial-mesenchymal transition (EMT) at certain concentrations. Whether hypoxia can induce EMT by stimulating RPE cell line secrets TGF-β2 or not remains unknown. To gain a better understanding of the signaling mechanisms of fibrosis in AMD under hypoxic conditions, we investigated EMT in retinal pigment epithelial (RPE) cells and the effect of TGF-β2 and Snail in this process.

METHODS

Human RPE cell line (ARPE-19) was incubated with 5 % O2 for different periods of time. The expression of N-cadherin, α-smooth muscle actin (α-SMA), TGF-β2 , and Snail were determined by Western blot and real-time PCR. Cell proliferation was assessed by CCK8 kit. RNA interference was used for multi-gene silencing of TGF-β2 and Snail genes.

RESULTS

N-cadherin was decreased and mesenchymal cell marker α-SMA was increased after the ARPE-19 cell line was incubated with 5 % O2. Meanwhile, the proliferation capability of the cell line was increased. TGF-β2 and Snail expression were increased in a time-dependent manner under hypoxia. After multi-silencing TGF-β2 and Snail genes, N-cadherin was increased and α-SMA was reduced. Meanwhile, the proliferation of the cell line was suppressed.

CONCLUSIONS

Under hypoxic conditions, RPE cells undergo EMT. Endogenic TGF-β2 and Snail are involved in this process. Furthermore, knockdown of both TGF-β2 and Snail inhibited EMT to a greater extent than knockdown of either gene individually.

Mechanisms of initiation and progression of intestinal fibrosis in IBD

Intestinal fibrosis is a common complication of the inflammatory bowel diseases (IBDs). It becomes clinically apparent in >30% of patients with Crohn's disease (CD) and in about 5% with ulcerative colitis (UC). Fibrosis is a consequence of local chronic inflammation and is characterized by excessive extracellular matrix (ECM) protein deposition. ECM is produced by activated myofibroblasts, which are modulated by both, profibrotic and antifibrotic factors. Fibrosis depends on the balance between the production and degradation of ECM proteins. This equilibrium can be impacted by a complex and dynamic interaction between profibrotic and antifibrotic mediators. Despite the major therapeutic advances in the treatment of active inflammation in IBD over the past two decades, the incidence of intestinal strictures in CD has not significantly changed as the current anti-inflammatory therapies neither prevent nor reverse the established fibrosis and strictures. This implies that control of intestinal inflammation does not necessarily affect the associated fibrotic process. The conventional view that intestinal fibrosis is an inevitable and irreversible process in patients with IBD is also gradually changing in light of an improved understanding of the cellular and molecular mechanisms that underline the pathogenesis of fibrosis. Comprehension of the mechanisms of intestinal fibrosis is thus vital and may pave the way for the developments of antifibrotic agents and new therapeutic approaches in IBD.

Integrated miRNA and mRNA expression profiling in inflamed colon of patients with ulcerative colitis

Background

Ulcerative colitis (UC) is associated with differential colonic expression of genes involved in immune response (e.g. IL8) and barrier integrity (e.g. cadherins). MicroRNAs (miRNAs) are regulators of gene expression and are involved in various immune-related diseases. In this study, we investigated (1) if miRNA expression in UC mucosa is altered and (2) if any of these changes correlate with mucosal mRNA expression. Integration of mRNA and miRNA expression profiling may allow the identification of functional links between dysregulated miRNAs and their target mRNA.

Methodology

Colonic mucosal biopsies were obtained from 17 UC (10 active and 7 inactive) patients and 10 normal controls. Total RNA was used to analyze miRNA and mRNA expression via Affymetrix miRNA 2.0 and Affymetrix Human Gene 1.0ST arrays, respectively. Both miRNA and gene expression profiles were integrated by correlation analysis to identify dysregulated miRNAs with their corresponding predicted target mRNA. Microarray data were validated with qRT-PCR. Regulation of IL8 and CDH11 expression by hsa-miR-200c-3p was determined by luciferase reporter assays.

Results

When comparing active UC patients vs. controls, 51 miRNAs and 1543 gene probe sets gave significantly different signals. In contrast, in inactive UC vs. controls, no significant miRNA expression differences were found while 155 gene probe sets had significantly different signals. We then identified potential target genes of the significantly dysregulated miRNAs and genes in active UC vs. controls and found a highly significant inverse correlation between hsa-miR-200c-3p and IL8, an inflammatory marker, and between hsa-miR-200c-3p and CDH11, a gene related to intestinal epithelial barrier function. We could demonstrate that hsa-miR-200c-3p directly regulates IL8 and CDH11 expression.

Conclusion

Differential expression of immune- and barrier-related genes in inflamed UC mucosa may be influenced by altered expression of miRNAs. Integrated analysis of miRNA and mRNA expression profiles revealed hsa-miR-200c-3p for use of miRNA mimics as therapeutics.

Results of the 4th scientific workshop of the ECCO (I): pathophysiology of intestinal fibrosis in IBD

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal fibrosis in the disease course of inflammatory bowel disease (IBD). The objective was to better understand the pathophysiological mechanisms of intestinal fibrosis, to identify useful markers and imaging modalities of fibrosis in order to assess its presence and progression, and, finally, to point out possible approaches for the prevention and the treatment of fibrosis. The results of this workshop are presented in three separate manuscripts. This first section describes the most important mechanisms that contribute to the initiation and progression of intestinal fibrosis in IBD including the cellular and molecular mediators, the extracellular matrix molecules and matrix metalloproteinases/tissue inhibitors of metalloproteinases-system, the microbiota products, the role of fat, genetic and epigenetic factors, as well as the currently available experimental models. Furthermore, it identifies unanswered questions in the field of intestinal fibrosis and provides a framework for future research.

Results of the 4th scientific workshop of the ECCO (Group II): markers of intestinal fibrosis in inflammatory bowel disease

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on intestinal fibrosis in inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms and markers of intestinal fibrosis as well as to suggest new therapeutic targets to prevent or treat fibrosis. The results of this workshop are presented in three separate manuscripts. This section describes markers of fibrosis in IBD, identifies unanswered questions in the field and provides a framework for future studies addressing the unmet needs in the field of intestinal fibrosis.

The possible role of extravillous trophoblast-derived exosomes on the uterine spiral arterial remodeling under both normal and pathological conditions

A tenet of contemporary obstetrics is that events that compromise placentation increase the risk of complications of pregnancy and contribute to poor pregnancy outcome. In particular, conditions that affect the invasion of placental cells and remodeling of uterine spiral arteries compromise placental function and the subsequent development of the fetus. Extravillous trophoblast cells (EVTs) proliferate and migrate from the cytotrophoblast in the anchoring villi of the placenta and invade the maternal decidua and myometrium. These cells are localised with uterine uterine spiral arteries and are thought to induce vascular remodeling. A newly identified pathway by which EVTs may regulate vascular remodeling within the uterus is via the release of exosomes. Trophoblast cells release exosomes that mediate aspects of cell-to-cell communication. The aim of this brief commentary is to review the putative role of exosomes released from extravillous trophoblast cells in uterine spiral artery remodeling and, in particular, their role in the aetiology of preeclampsia. Placental exosomes may engage in local cell-to-cell communication between the cell constituents of the placenta and contiguous maternal tissues and/or distal interactions, involving the release of placental exosomes into biological fluids and their transport to a remote site of action.

The emerging role of circulating microRNAs as biomarkers in autoimmune diseases

The highly conserved RNAs known as microRNAs (miRNAs) are a class of small, single-stranded, non-coding RNAs that play a critical role in the regulation of host genome expression at the posttranscriptional level. MiRNA-mediated gene regulation is vital for normal cellular functions, such as the cell differentiation, proliferation and apoptosis, and nearly one-third of human messenger RNAs might be miRNA targets. Increasing evidence has suggested that miRNAs play a critical role in the regulating the immune system and preventing autoimmune disorders. Circulating miRNAs, which can be easily detected by a non-invasive methods, have been proven to be able to distinguish diseased individuals from healthy subjects. In addition, these circulating miRNAs have relatively high sensitivity and specificity and thus have been developed as biomarkers for the diagnosis and monitoring of human diseases. To date, nearly 100 circulating miRNAs have been proven to be biomarkers for various diseases, and this number continues to rise. This review aims to summarize the most promising identified circulating miRNAs as potential biomarkers in autoimmune diseases and to discuss current challenges and future directions in the field.

A gestational profile of placental exosomes in maternal plasma and their effects on endothelial cell migration

Studies completed to date provide persuasive evidence that placental cell-derived exosomes play a significant role in intercellular communication pathways that potentially contribute to placentation and development of materno-fetal vascular circulation. The aim of this study was to establish the gestational-age release profile and bioactivity of placental cell-derived exosome in maternal plasma. Plasma samples (n = 20 per pregnant group) were obtained from non-pregnant and pregnant women in the first (FT, 6–12 weeks), second (ST, 22–24 weeks) and third (TT, 32–38 weeks) trimester. The number of exosomes and placental exosome contribution were determined by quantifying immunoreactive exosomal CD63 and placenta-specific marker (PLAP), respectively. The effect of exosomes isolated from FT, ST and TT on endothelial cell migration were established using a real-time, live-cell imaging system (Incucyte). Exosome plasma concentration was more than 50-fold greater in pregnant women than in non-pregnant women (p<0.001). During normal healthy pregnancy, the number of exosomes present in maternal plasma increased significantly with gestational age by more that two-fold (p<0.001). Exosomes isolated from FT, ST and TT increased endothelial cell migration by 1.9±0.1, 1.6±0.2 and 1.3±0.1-fold, respectively compared to the control. Pregnancy is associated with a dramatic increase in the number of exosomes present in plasma and maternal plasma exosomes are bioactive. While the role of placental cell-derived exosome in regulating maternal and/or fetal vascular responses remains to be elucidated, changes in exosome profile may be of clinical utility in the diagnosis of placental dysfunction.

Serum microRNA levels in patients with Crohn's disease during induction therapy by infliximab

BACKGROUND AND AIM

microRNAs (miRNAs) have been suggested to be candidates for biomarkers in various diseases including Crohn's disease (CD). To identify possible biomarkers predictive of the therapeutic effect of infliximab in CD, we investigated serum miRNA levels during the induction therapy by the medication.

METHODS

Nineteen CD patients who were applied to the induction therapy by infliximab were enrolled. Serum samples for miRNA analyses were obtained at weeks 0 and 6, and the therapeutic efficacy by infliximab was assessed according to the Crohn's disease activity index value at week 14. Exploratory miRNA profiling by low-density array was initially performed in three patients. The levels of candidate miRNA were subsequently determined by real-time polymerase chain reaction (PCR) assays in the remaining 16 patients. The miRNA levels during the induction therapy were compared between the two groups classified by the clinical response to infliximab at week 14.

RESULTS

Low-density array analysis identified 14 miRNAs that showed twofold or more altered expression during the induction therapy by infliximab. Subsequent analysis by real-time PCR demonstrated significantly increased levels of five miRNAs (let-7d, let-7e, miR-28-5p, miR-221, and miR-224) at week 6 when compared with those at week 0 (P < 0.05 each). In addition, miRNA levels of let-7d and let-7e were significantly increased in the group of patients who achieved clinical remission by infliximab (P = 0.001 and P = 0.002, respectively).

CONCLUSION

let-7d and let-7e might be possible therapeutic biomarkers in patients with CD, who are treated by infliximab.

Implication of miRNAs for inflammatory bowel disease treatment: Systematic review

Inflammatory bowel disease (IBD) is believed to develop via a complex interaction between genetic, environmental factors and the mucosal immune system. Crohn’s disease and ulcerative colitis are two major clinical forms of IBD. MicroRNAs (miRNAs) are a class of small, endogenous, noncoding RNA molecules, and evolutionary conserved in animals and plants. It controls protein production at the post-transcriptional level by targeting mRNAs for translational repression or degradation. MiRNAs are important in many biological processes, such as signal transduction, cellular proliferation, differentiation and apoptosis. Considerable attention has been paid on the key role of miRNAs in autoimmune and inflammatory disease, especially IBD. Recent studies have identified altered miRNA profiles in ulcerative colitis, Crohn’s disease and inflammatory bowel disease-associated colorectal cancer. In addition, emerging data have implicated that special miRNAs which suppress functional targets play a critical role in regulating key pathogenic mechanism in IBD. MiRNAs were found involving in regulation of nuclear transcription factor kappa B pathway (e.g., miR-146a, miR-146b, miR-122, miR-132, miR-126), intestinal epithelial barrier function (e.g., miR-21, miR-150, miR-200b) and the autophagic activity (e.g., miR-30c, miR-130a, miR-106b, miR-93, miR-196). This review aims at discussing recent advances in our understanding of miRNAs in IBD pathogenesis, their role as disease biomarkers, and perspective for future investigation and clinical application.

Predicted overlapping microRNA regulators of acetylcholine packaging and degradation in neuroinflammation-related disorders

MicroRNAs (miRNAs) can notably control many targets each and regulate entire cellular pathways, but whether miRNAs can regulate complete neurotransmission processes is largely unknown. Here, we report that miRNAs with complementary sequence motifs to the key genes involved in acetylcholine (ACh) synthesis and/or packaging show massive overlap with those regulating ACh degradation. To address this topic, we first searched for miRNAs that could target the 3′-untranslated regions of the choline acetyltransferase (ChAT) gene that controls ACh synthesis; the vesicular ACh transporter (VAChT), encoded from an intron in the ChAT gene and the ACh hydrolyzing genes acetyl- and/or butyrylcholinesterase (AChE, BChE). Intriguingly, we found that many of the miRNAs targeting these genes are primate-specific, and that changes in their levels associate with inflammation, anxiety, brain damage, cardiac, neurodegenerative, or pain-related syndromes. To validate the in vivo relevance of this dual interaction, we selected the evolutionarily conserved miR-186, which targets both the stress-inducible soluble “readthrough” variant AChE-R and the major peripheral cholinesterase BChE. We exposed mice to predator scent stress and searched for potential associations between consequent changes in their miR-186, AChE-R, and BChE levels. Both intestinal miR-186 as well as BChE and AChE-R activities were conspicuously elevated 1 week post-exposure, highlighting the previously unknown involvement of miR-186 and BChE in psychological stress responses. Overlapping miRNA regulation emerges from our findings as a recently evolved surveillance mechanism over cholinergic neurotransmission in health and disease; and the corresponding miRNA details and disease relevance may serve as a useful resource for studying the molecular mechanisms underlying this surveillance.

Up-regulation of miR-200b in biliary atresia patients accelerates proliferation and migration of hepatic stallate cells by activating PI3K/Akt signaling

An increasing body of evidence suggests that miRNAs are involved in fibrotic process of several organs including heart, lung and kidney. It has been observed recently that aberrant expression of miR-200s are associated with hepatic fibrosis. However, the role and underlying mechanism of miR-200s in hepatic fibrogenesis remains unknown. Here, we investigate the role of miR-200b in the activation of immortalized human hepatic stallate cells (HSCs), LX-2 cells. We firstly found that miR-200b significantly enhanced proliferation and migration of LX-2 cells. Secondly, our findings showed that miR-200b enhanced the phosphorylation of Akt, a downstream effector of phosphatidyl-inositol 3-Kinase (PI3K). FOG2, as the targets of fly miR-8 and human miR-200s, directly binds to p85α and inhibits the activation of the PI3K/Akt pathway. Here, we showed that FOG2 protein levels in LX-2 cells were suppressed significantly by miR-200b mimics. FOG2 knockdown by siRNAs activated the PI3K/Akt signaling, which increased cell growth and migration that mimicked the effect of miR-200b. Conversely, LY294002, a highly selective inhibitor of PI3K, could block phosphorylation of Akt and effect of miR-200b. In addition, we showed that miR-200b enhanced the expression of matrix metalloproteinase-2 (MMP-2), which may increase the migration of LX-2 cells. Finally, our results indicated that the expression of miR-200b was unregulated in the biliary atresia (BA) and associated with liver fibrotic progression. These data suggest a potential mechanism for Akt activation through FOG2 down-regulation by miR-200b that can lead to HSC growth and migration. In view of the putative pathogenic role of miR-200b in HSCs, miR-200b may constitute a potential marker for HSC activation and liver fibrosis progression.

Epigenetics: the fine-tuner in inflammatory bowel disease?

PURPOSE OF REVIEW

Epigenetic studies are transforming our understanding of a variety of complex pathological conditions including cancer, autoimmune, and inflammatory diseases. A selection of the major recent advances in this area will be reviewed, focusing on the important emerging themes that are relevant to these diseases including inflammatory bowel disease (IBD).

RECENT FINDINGS

The main current themes that will be addressed on the role of epigenetics in disease pathogenesis include current understanding of the nature and function of histone modifications and DNA methylation; the connection between epigenetics and metabolic pathways; new studies on the mechanism of heritability of epigenetic changes; the role of stochastic noise and the expanding research on chromatin readers and their potential as selective therapeutic targets. The recent contribution of epigenetic modifications in defining the molecular basis of IBD and how such changes may act as fine-tuners of gene expression in these intestinal disorders are also discussed.

SUMMARY

Published evidence over the last 12-18 months indicates that targeting epigenetic factors can be efficacious in cancer and inflammatory disease. All the indications are that future research will continue to reveal new epigenetic targets and mechanisms that will advance the prospects for selective epigenetic therapy for IBD and other complex diseases.

The role of microRNAs in the pathogenesis of MMPi-induced skin fibrodysplasia

Background

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes involved in extracellular matrix (ECM) homeostasis. MMPs have been an attractive pharmacological target for a number of indications. However, development has been hampered by the propensity of compounds targeting these enzymes to cause connective-tissue pathologies. The broad-spectrum MMP-inhibitor (MMPi) AZM551248 has been shown to induce such effects in the dog. Histopathological changes were consistent with fibrodysplasia (FD), characterised by fibroblast proliferation and the deposition of collagen in the subcutaneous tissues. We conducted a time-course study administering 20mg/kg/day AZM551248 between 4 and 17 days. Cervical subcutaneous tissue and plasma were sampled during the time-course. miRNA expression profiles in subcutaneous skin specimens following the administration of AZM551248 were determined by high-throughput-sequencing.

Results

An increasing number of miRNAs were differentially expressed compared with vehicle treated control animals as the study progressed. Several of these were members of the miR-200 family and were significantly attenuated in response to MMPi. As the severity of FD increased at the later time-points, other miRNAs associated with TGFβ synthesis and regulation of the acute inflammatory response were modulated. Evidence indicative of epithelial to mesenchymal transition was present at all study time points. Receiver operator curve (ROC) analysis revealed that miR-21 expression in the cervical subcutaneous tissue was a sensitive and specific biomarker of FD incidence.

Conclusions

Our data reveal significant perturbations in canine skin miRNA expression in response to MMPi administration. Furthermore, we have identified dysregulated miRNAs that are associated with processes relevant to the key histopathological events of MMPi-induced FD.

miR-200b inhibits TGF-β1-induced epithelial-mesenchymal transition and promotes growth of intestinal epithelial cells

Inflammatory bowel disease (IBD), which consists of Crohn's disease (CD) and ulcerative colitis (UC), is a chronic, inflammatory disorder of the gastro-intestinal tract with unknown etiology. Current evidence suggests that intestinal epithelial cells (IECs) is prominently linked to the pathogenesis of IBD. Therefore, maintaining the intact of epithelium has potential roles in improving pathophysiology and clinical outcomes of IBD. MicroRNAs (miRNAs) act as post-transcriptional gene regulators and regulate many biological processes, including embryonal development, cell differentiation, apoptosis and proliferation. In this study, we found that miR-200b decreased significantly in inflamed mucosa of IBD, especially for UC, when compared with their adjacent normal tissue. Simultaneously, we also found that the genes of E-cadherin and cyclin D1 were reduced significantly and correlated positively to the miR-200b. In addition, the upregulation of transforming growth factor-beta 1 (TGF-β1) was inversely correlated to the miR-200b in IBD. To investigate the possible roles of miR-200b in IECs maintaining, we used TGF-β1 to induce epithelial-mesenchymal transition (EMT) in IEC-6 initially. After sustained over-expressing miR-200b in IEC-6, the EMT was inhibited significantly that was characterized by downregulation of vimentin and upregulation of E-cadherin. Furthermore, we found that miR-200b enhanced E-cadherin expression through targeting of ZEB1, which encode transcriptional repressors of E-cadherin. SMAD2 was found to act as a target of miR-200b with direct evidence that miR-200b binding to the 3′ UTR of SAMD2 and the ability of miR-200b to repress SMAD2 protein expression. With SMAD2 depletion, the expression of vimentin decreased correspondingly, which suggested miR-200b might reduce vimentin through regulating the SMAD2. With endogenous over-expression of miR-200b, the proliferation of IEC-6 cells increased significantly by increasing S-phase entry and promoting expression of the protein cyclin D1. Summarily, our study suggested a potential role for mir-200b in maintaining intact of intestinal epithelium through inhibiting EMT and promoting proliferation of IECs.

Epigenetics and the developmental origins of inflammatory bowel diseases

The gut microbiota, the intestinal mucosa and the host immune system are among the large biological networks involved in the development of inflammatory bowel disease (IBD), which includes Crohn disease (CD) and ulcerative colitis (UC). Host genetics and environmental factors can significantly modulate the interactive relationships among these biological systems and influence predilection toward IBD. High monozygotic twin discordance rates and the rapid rise in the prevalence of IBD indicate that environmental influences may be as important or even more important in their pathogenesis than genetic susceptibility. However, the nature and timing of environmental factors critical for inducing IBD remain largely unknown. The molecular mechanisms and the key biological component(s) that may be affected by such factors are also in question. Epigenetic changes, such as DNA methylation (the methylation of cytosines followed by a guanine in CpG dinucleotides) can be modified by environmental influences during finite developmental periods and have been implicated in the pathogenesis of IBD. Mucosal DNA methylation can also react to changes in the commensal microbiota, underscoring the intercalating relationships among the large biological systems involved in gastrointestinal disorders. Therefore, transient environmental influences during specific periods of development may induce critical change(s) in an isolated or concomitant fashion within the intestinal biomic networks and lead to increased susceptibility to IBD. The present review focuses on the emerging paradigm shift considering IBD to originate from critical environmental effects during pre- and postnatal development.

miR-200c is aberrantly expressed in leiomyomas in an ethnic-dependent manner and targets ZEBs, VEGFA, TIMP2, and FBLN5

MicroRNA-200c (miR-200c) through repression of specific target genes has been associated with cellular transition, tumorigenesis, and tissue fibrosis. We explored the expression and functional aspects of miR-200c in genesis of leiomyomas (LYO), benign uterine tumors with fibrotic characteristic. Using LYO and matched myometrium (MYO; n=76) from untreated and from patients exposed to hormonal therapies (GNRH agonist (GNRHa), Depo-Provera, and oral contraceptives), we found that miR-200c was expressed at significantly lower levels (P<0.05) in LYO as compared with MYO. These levels were lower in LYO from African Americans as compared with Caucasians, patients experiencing abnormal uterine bleeding and those exposed to GNRHa therapy. Gain-of-function of miR-200c in isolated leiomyoma smooth muscle cells (LSMCs), myometrial smooth muscle cells (MSMCs), and leiomyosarcoma cell line (SKLM-S1) repressed ZEB1/ZEB2 mRNAs and proteins, with concurrent increase in E-cadherin (CDH1) and reduction in vimentin expression, phenotypic alteration, and inhibition of MSMC and LSMC proliferations. We further validated TIMP2, FBLN5, and VEGFA as direct targets of miR-200c through interaction with their respective 3' UTRs, and other genes as determined by microarray analysis. At tissue levels, LYO expressed lower levels of TIMP2 and FBLN5 mRNAs but increased protein expressions, which to some extent altered due to hormonal exposure. Given the regulatory functions of ZEBs, VEGFA, FBLN5, and TIMP2 on cellular activities that promote cellular transition, angiogenesis, and matrix remodeling, we concluded that altered expression of miR-200c may have a significant impact on the outcome of LYO growth, maintenance of their mesenchymal and fibrotic characteristics, and possibly their associated symptoms.