Mechanisms and therapeutic research progress in intestinal fibrosis

Intestinal fibrosis is a common complication of chronic intestinal diseases with the characteristics of fibroblast proliferation and extracellular matrix deposition after chronic inflammation, leading to lumen narrowing, structural and functional damage to the intestines, and life inconvenience for the patients. However, anti-inflammatory drugs are currently generally not effective in overcoming intestinal fibrosis making surgery the main treatment method. The development of intestinal fibrosis is a slow process and its onset may be the result of the combined action of inflammatory cells, local cytokines, and intestinal stromal cells. The aim of this study is to elucidate the pathogenesis [e.g., extracellular matrix (ECM), cytokines and chemokines, epithelial-mesenchymal transition (EMT), differentiation of fibroblast to myofibroblast and intestinal microbiota] underlying the development of intestinal fibrosis and to explore therapeutic advances (such as regulating ECM, cytokines, chemokines, EMT, differentiation of fibroblast to myofibroblast and targeting TGF-β) based on the pathogenesis in order to gain new insights into the prevention and treatment of intestinal fibrosis.

Recent advances in intestinal fibrosis

Despite many progresses have been made in the treatment of inflammatory bowel disease, especially due to the increasing number of effective therapies, the development of tissue fibrosis is a very common occurrence along the natural history of this condition. To a certain extent, fibrogenesis is a physiological and necessary process in all those conditions characterised by chronic inflammation. However, the excessive deposition of extracellular matrix within the bowel wall will end up in the formation of strictures, with the consequent need for surgery. A number of mechanisms have been described in this process, but some of them are not yet clear. For sure, the main trigger is the presence of a persistent inflammatory status within the mucosa, which in turn favours the occurrence of a pro-fibrogenic environment. Among the main key players, myofibroblasts, fibroblasts, immune cells, growth factors and cytokines must be mentioned. Although there are no available therapies able to target fibrosis, the only way to prevent it is by controlling inflammation. In this review, we summarize the state of art of the mechanisms involved in gut fibrogenesis, how to diagnose it, and which potential targets could be druggable to tackle fibrosis.

How to Evaluate Fibrosis in IBD?

In this review, we will describe the importance of fibrosis in inflammatory bowel disease (IBD) by discussing its distinct impact on Crohn's disease (CD) and ulcerative colitis (UC) through their translation to histopathology. We will address the existing knowledge on the correlation between inflammation and fibrosis and the still not fully explained inflammation-independent fibrogenesis. Finally, we will compile and discuss the recent advances in the noninvasive assessment of intestinal fibrosis, including imaging and biomarkers. Based on the available data, none of the available cross-sectional imaging (CSI) techniques has proved to be capable of measuring CD fibrosis accurately, with MRE showing the most promising performance along with elastography. Very recent research with radiomics showed encouraging results, but further validation with reliable radiomic biomarkers is warranted. Despite the interesting results with micro-RNAs, further advances on the topic of fibrosis biomarkers depend on the development of robust clinical trials based on solid and validated endpoints. We conclude that it seems very likely that radiomics and AI will participate in the future non-invasive fibrosis assessment by CSI techniques in IBD. However, as of today, surgical pathology remains the gold standard for the diagnosis and quantification of intestinal fibrosis in IBD.

Anti-fibrotic effects of statin drugs: a review of evidence and mechanisms

Fibrosis is a pathological repair process common among organs, that responds to damage by replacement of tissue with non-functional connective tissue. Despite the widespread prevalence of tissue fibrosis, manifesting in numerous disease states across myriad organs, therapeutic modalities to prevent or alleviate fibrosis are severely lacking in quantity and efficacy. Alongside development of new drugs, repurposing of existing drugs may be a complementary strategy to elect anti-fibrotic compounds for pharmacologic treatment of tissue fibrosis. Drug repurposing can provide key advantages to de novo drug discovery, harnessing the benefits of previously elucidated mechanisms of action and already existing pharmacokinetic profiles. One class of drugs a wealth of clinical data and extensively studied safety profiles is the statins, a class of antilipidemic drugs widely prescribed for hypercholesterolemia. In addition to these widely utilized lipid-lowering effects, increasing data from cellular, pre-clinical mammalian, and clinical human studies have also demonstrated that statins are able to alleviate tissue fibrosis originating from a variety of pathological insults via lesser-studied, pleiotropic effects of these drugs. Here we review literature demonstrating evidence for direct effects of statins antagonistic to fibrosis, as well as much of the available mechanistic data underlying these effects. A more complete understanding of the anti-fibrotic effects of statins may enable a clearer picture of their anti-fibrotic potential for various clinical indications. Additionally, more lucid comprehension of the mechanisms by which statins exert anti-fibrotic effects may aid in development of novel therapeutic agents that target similar pathways but with greater specificity or efficacy.

ZNF281 Promotes Colon Fibroblast Activation in TGFβ1-Induced Gut Fibrosis

Crohn’s disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders of the gastrointestinal tract. Chronic inflammation is the main factor leading to intestinal fibrosis, resulting in recurrent stenosis, especially in CD patients. Currently, the underlying molecular mechanisms of fibrosis are still unclear. ZNF281 is a zinc-finger transcriptional regulator that has been characterized as an epithelial-to-mesenchymal transition (EMT)-inducing transcription factor, suggesting its involvement in the regulation of pluripotency, stemness, and cancer. The aim of this study is to investigate in vivo and in vitro the role of ZNF281 in intestinal fibrogenesis. Intestinal fibrosis was studied in vivo in C57BL/6J mice with chronic colitis induced by two or three cycles of administration of dextran sulfate sodium (DSS). The contribution of ZNF281 to gut fibrosis was studied in vitro in the human colon fibroblast cell line CCD-18Co, activated by the pro-fibrotic cytokine TGFβ1. ZNF281 was downregulated by siRNA transfection, and RNA-sequencing was performed to identify genes regulated by TGFβ1 in activated colon fibroblasts via ZNF281. Results showed a marked increase of ZNF281 in in vivo murine fibrotic colon as well as in in vitro human colon fibroblasts activated by TGFβ1. Moreover, abrogation of ZNF281 in TGFβ1-treated fibroblasts affected the expression of genes belonging to specific pathways linked to fibroblast activation and differentiation into myofibroblasts. We demonstrated that ZNF281 is a key regulator of colon fibroblast activation and myofibroblast differentiation upon fibrotic stimuli by transcriptionally controlling extracellular matrix (ECM) composition, remodeling, and cell contraction, highlighting a new role in the onset and progression of gut fibrosis.

"Two-birds-one-stone" colon-targeted nanomedicine treats ulcerative colitis via remodeling immune microenvironment and anti-fibrosis

Dysregulated mucosal immune responses and colonic fibrosis impose two formidable challenges for ulcerative colitis treatment. It indicates that monotherapy could not sufficiently deal with this complicated disease and combination therapy may provide a potential solution. A chitosan-modified poly(lactic-co-glycolic acid) nanoparticle (CS-PLGA NP) system was developed for co-delivering patchouli alcohol and simvastatin to the inflamed colonic epithelium to alleviate the symptoms of ulcerative colitis via remodeling immune microenvironment and anti-fibrosis, a so-called “two-birds-one-stone” nanotherapeutic strategy. The bioadhesive nanomedicine enhanced the intestinal epithelial cell uptake efficiency and improved the drug stability in the gastrointestinal tract. The nanomedicine effectively regulated the Akt/MAPK/NF-κB pathway and reshaped the immune microenvironment through repolarizing M2Φ, promoting regulatory T cells and G-MDSC, suppressing neutrophil and inflammatory monocyte infiltration, as well as inhibiting dendritic cell maturation. Additionally, the nanomedicine alleviated colonic fibrosis. Our work elucidates that the colon-targeted codelivery for combination therapy is promising for ulcerative colitis treatment and to address the unmet medical need.

Atorvastatin attenuates pulmonary fibrosis in mice and human lung fibroblasts, by the regulation of myofibroblast differentiation and apoptosis

Statins have anti-inflammatory and antifibrotic effects in addition to cholesterol-lowering effect. We aimed to investigate the effect of atorvastatin (ATR) in fibrotic mouse lung and human lung fibroblasts (MRC5s). Pulmonary fibrosis was induced by a single dose of bleomycin by intratracheal instillation in adult mice. ATR was administered (20 mg/kg ip) to mice with healthy and pulmonary fibrosis for 10 days from Day 7 of the experiment. Mice were dissected on the 21st day. The levels of alpha-smooth muscle actin (α-SMA), pSMAD2/3, LOXL2, and p-Src were determined by Western blot analysis in the lungs. Furthermore, a group of MRC5 was differentiated into myofibroblasts by transforming growth factor-beta (TGF-β). Another group of MRC5s was treated with 10 µM ATR at 24 h after TGF-β stimulation. Cells were collected at 0, 24, 48, and 72 h. The effects of ATR on myofibroblast differentiation, apoptosis, and TGF-β and Wnt/β-catenin signaling activations were examined by Western blot analysis and flow cytometry in MRC5s. ATR attenuated pulmonary fibrosis by regulating myofibroblast differentiation and interstitial accumulation of collagen, by acting on LOXL2, p-Src, and pSMAD2/3 in mice lungs. Additionally, it blocked myofibroblast differentiation via reduced TGF-β and Wnt/β-catenin signaling and decreased α-SMA in MRC5s stimulated with TGF-β. Moreover, ATR caused myofibroblast apoptosis via caspase-3 activation. ATR treatment attenuates pulmonary fibrosis in mice treated with bleomycin. It also inhibits fibroblast/myofibroblast activation, by both reducing myofibroblasts differentiation and inducing myofibroblast apoptosis.

Revisiting fibrosis in inflammatory bowel disease: the gut thickens

Intestinal fibrosis, which is usually the consequence of chronic inflammation, is a common complication of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis. In the past few years, substantial advances have been made in the areas of pathogenesis, diagnosis and management of intestinal fibrosis. Of particular interest have been inflammation-independent mechanisms behind the gut fibrotic process, genetic and environmental risk factors (such as the role of the microbiota), and the generation of new in vitro and in vivo systems to study fibrogenesis in the gut. A huge amount of work has also been done in the area of biomarkers to predict or detect intestinal fibrosis, including novel cross-sectional imaging techniques. In parallel, researchers are embarking on developing and validating clinical trial end points and protocols to test novel antifibrotic agents, although no antifibrotic therapies are currently available. This Review presents the state of the art on the most recently identified pathogenic mechanisms of this serious IBD-related complication, focusing on possible targets of antifibrotic therapies, management strategies, and factors that might predict fibrosis progression or response to treatment.

The effect of statin therapy on disease-related outcomes in idiopathic pulmonary fibrosis: A systematic review and meta-analysis

BACKGROUND

Idiopathic pulmonary fibrosis is a progressive disease and antifibrotic therapies do not reverse existing fibrosis. There has been emerging evidence of potential role for statins in idiopathic pulmonary fibrosis. The aim of this review is to synthesise the evidence on the efficacy of statins in idiopathic pulmonary fibrosis, focusing on associations with all-cause mortality, disease-specific mortality and change in pulmonary function.

METHODS

Medline and Embase were reviewed to identify relevant publications. Studies were selected if they examined disease-related outcomes including mortality, pulmonary function and adverse events in people with idiopathic pulmonary fibrosis receiving statin therapy.

RESULTS

Five studies with a total of 3407 people with IPF were selected and analysed. The overall risk of bias of five included studies was moderate to serious. In the fixed effect meta-analysis, statin use was associated with a reduction in mortality (RR 0.8; 95% CI 0.72-0.99). However, in the random effects model, there was no longer any significant association between statin use and all-cause mortality (RR 0.87; 95% CI 0.68-1.12). There was no statistically significant association between statin use and decline in FVC % predicted.

CONCLUSION

There is currently insufficient evidence to conclude the effect of statin therapy on disease-related outcomes in idiopathic pulmonary fibrosis. Considering the limitations of available literature, we would recommend a prospective cohort study with capture of dosage and preparation of statin, statin adherence and use of concurrent antifibrotic treatment.

PROSPERO REGISTRATION NUMBER

CRD42019122745.

Association Between Statin Use at the Time of Intra-abdominal Surgery and Postoperative Adhesion-Related Complications and Small-Bowel Obstruction

IMPORTANCE

Adhesion-related complications (ARCs), including small-bowel obstruction, are common complications of intra-abdominal surgery. Statins, which have antifibrotic pleiotropic effects, inhibit adhesion formation in murine models but have not been assessed in humans.

OBJECTIVE

To assess whether statin use at the time of intra-abdominal surgery is associated with a reduction in ARCs.

DESIGN, SETTING, AND PARTICIPANTS

These 2 separate retrospective cohort studies (The Health Improvement Network [THIN] and Optum's Clinformatics Data Mart [Optum]) compared adults receiving statins with those not receiving statins at the time of intra-abdominal surgery. Individuals undergoing intra-abdominal surgery from January 1, 1996, to December 31, 2013, in the United Kingdom and from January 1, 2000, to December 31, 2016, in the US were included in the study. Those with obstructive events before surgery or a history of inflammatory bowel disease were excluded. Data analysis was performed from September 1, 2012, to November 24, 2020.

EXPOSURE

The primary exposure was statin use at the time of surgery.

MAIN OUTCOMES AND MEASURES

The primary outcome was ARCs, defined as small-bowel obstruction or need for adhesiolysis, occurring after surgery. Sensitivity analyses included statin use preceding but not concurrent with surgery, fibrate use, and angiotensin-converting enzyme inhibitor use. All analyses were adjusted for age, sex, and conditions associated with microvascular disease, such as hypertension, hyperlipidemia, obesity, and tobacco use; surgical approach and site; and diagnosis of a malignant tumor.

RESULTS

A total of 148 601 individuals met the inclusion criteria for THIN (mean [SD] age, 49.6 [17.7] years; 70.1% female) and 1 188 217 for Optum (mean [SD] age, 48.2 [16.4] years; 72.6% female). A total of 2060 participants (1.4%) experienced an ARC in THIN and 54 136 (4.6%) in Optum. Statin use at the time of surgery was associated with decreased risk of ARCs (THIN: adjusted hazard ratio [HR], 0.81; 95% CI, 0.71-0.92; Optum: adjusted HR, 0.92; 95% CI, 0.90-0.95). Similar associations were appreciated between statins and small-bowel obstruction (THIN: adjusted HR, 0.80; 95% CI, 0.70-0.92; Optum: adjusted HR, 0.88; 95% CI, 0.85-0.91).

CONCLUSIONS AND RELEVANCE

This study's findings suggest that, among individuals in 2 separate cohorts undergoing intra-abdominal surgery, statin use may be associated with a reduced risk of postoperative ARCs. Statins may represent an inexpensive, well-tolerated pharmacologic option for preventing ARCs.

Simvastatin and ROCK Inhibitor Y-27632 Inhibit Myofibroblast Differentiation of Graves' Ophthalmopathy-Derived Orbital Fibroblasts via RhoA-Mediated ERK and p38 Signaling Pathways

Transforming growth factor-β (TGF-β)-induced differentiation of orbital fibroblasts into myofibroblasts is an important pathogenesis of Graves' ophthalmopathy (GO) and leads to orbital tissue fibrosis. In the present study, we explored the antifibrotic effects of simvastatin and ROCK inhibitor Y-27632 in primary cultured GO orbital fibroblasts and tried to explain the molecular mechanisms behind these effects. Both simvastatin and Y-27632 inhibited TGF-β-induced α-smooth muscle actin (α-SMA) expression, which serves as a marker of fibrosis. The inhibitory effect of simvastatin on TGF-β-induced RhoA, ROCK1, and α-SMA expression could be reversed by geranylgeranyl pyrophosphate, an intermediate in the biosynthesis of cholesterol. This suggested that the mechanism of simvastatin-mediated antifibrotic effects may involve RhoA/ROCK signaling. Furthermore, simvastatin and Y-27632 suppressed TGF-β-induced phosphorylation of ERK and p38. The TGF-β-mediated α-SMA expression was suppressed by pharmacological inhibitors of p38 and ERK. These results suggested that simvastatin inhibits TGF-β-induced myofibroblast differentiation via suppression of the RhoA/ROCK/ERK and p38 MAPK signaling pathways. Thus, our study provides evidence that simvastatin and ROCK inhibitors may be potential therapeutic drugs for the prevention and treatment of orbital fibrosis in GO.

Statins affect human glioblastoma and other cancers through TGF-β inhibition

The cholesterol-lowering statins have known anti-cancer effects, but the mechanisms and how to utilize statins in oncology have been unclear. We noted in the CellMiner database that statin activity against cancer lines correlated with higher expression of TGF-β target genes such as SERPINE1 and ZYX. This prompted us to assess whether statins affected TGF-β activity in glioblastoma (GBM), a cancer strongly influenced by TGF-β and in dire need of new therapeutic approaches. We noted that statins reduced TGF-β activity, cell viability and invasiveness, Rho/ROCK activity, phosphorylation and activity of the TGF-β mediator Smad3, and expression of TGF-β targets ZYX and SERPINE1 in GBM and GBM-initiating cell (GIC) lines. Statins were most potent against GBM, GIC, and other cancer cells with high TGF-β activity, and exogenous TGF-β further sensitized mesenchymal GICs to statins. Statin toxicity was rescued by addition of exogenous mevalonolactone or geranylgeranyl pyrophosphate, indicating that the observed effects reflected inhibition of HMG CoA-reductase by the statins. Simvastatin significantly inhibited the growth of subcutaneous GIC grafts and prolonged survival in GIC intracranially grafted mice. These results indicate where the statins might best be applied as adjunct therapies in oncology, against GBM and other cancers with high TGF-β activity, and have implications for other statin roles outside of oncology.

The effects of platelet-rich plasma on hypertrophic scars fibroblasts

We hypothesised that a feedback mechanism of the transforming growth factor (TGF)-β1 signalling pathway, triggered by high-level TGF-β1, activates platelet-rich plasma (PRP) release to reduce connective tissue growth factor (CTGF) production and expression of CTGF mRNA in hypertrophic scar dermal fibroblasts. Primary dermal fibroblasts were isolated from cultures of hypertrophic scars. Cells were cultured after addition of serum-free Dulbecco's modified Eagle's medium supplemented with 5% (wt/vol) PRP or platelet-poor plasma (PPP). At 1, 4, 6, 8, 11, and 13 days after addition of PRP or PPP, the TGF-β1 and CTGF levels in supernatants were determined using solid-phase enzyme-linked immunosorbent assays. Quantitative reverse transcription polymerase chain reactions were performed to quantify TGF-β1 and CTGF mRNA expression levels. TGF-β1 mRNA expression in the PRP groups was lower than in the PPP groups from 4 to 13 days of culture, and there was statistically significant difference (P < .01). CTGF level and mRNA expression in the PRP groups was lower than in the PPP groups, and there were statistically significant differences (P < .01). Although further experiments will focus on clarifying the second messenger of the TGF-β1 negative feedback mechanism, the in vitro data presented show that PRP can potentially reduce CTGF and CTGF gene transcription by triggering the TGF-β1 signalling negative feedback mechanism.

Synergistic effects of simvastatin and bone marrow-derived mesenchymal stem cells on hepatic fibrosis

The beneficial effects of simvastatin on fibrosis in various organs have been reported. In addition, bone marrow (BM)-derived mesenchymal stem cells (MSCs) have been suggested as an effective therapy for hepatic fibrosis and cirrhosis. Recent evidence suggests that pharmacological treatment devoted to regulating stem cell function is a potential new therapeutic strategy that is drawing nearer to clinical practice. The aim of this study was to determine whether the combination treatment of simvastatin plus MSCs (Sim-MSCs) could have a synergistic effect on hepatic fibrosis in a thioacetamide (TAA)-induced cirrhotic rat model and hepatic stellate cells (HSCs). Cirrhotic livers from rats treated with Sim-MSCs exhibited histological improvement compared to those treated with simvastatin alone. Sim-MSCs combination treatment decreased hepatic collagen distribution, lowered the hydroxyproline content, and rescued liver function impairment in rats with TAA-induced cirrhosis. These protective effects were more potent with Sim-MSCs than with simvastatin alone. The upregulation of collagen-1, α-smooth muscle actin (α-SMA), transforming growth factor (TGF)-β1, and phospho-Smad3 in cirrhotic livers was prevented by the administration of Sim-MSCs. Intriguingly, Sim-MSCs inhibited both TGF-β/Smad3 signaling and α-SMA in HSCs. The Sim-MSCs combination treatment exerted strong protective effects against hepatic fibrosis by suppressing TGF-β/Smad signaling. Simvastatin could act synergistically with MSCs as an efficient therapeutic approach for intractable cirrhosis.

Cytokine and anti-cytokine therapies in prevention or treatment of fibrosis in IBD

The frequency of fibrosing Crohn's disease (CD) is significant, with approximately 40% of CD patients with ileal disease developing clinically apparent strictures throughout their lifetime. Although strictures may be subdivided into fibrotic, inflammatory, or mixed forms, despite immunosuppressive therapy in CD patients in the form of steroids or immunomodulators, the frequency of fibrostenosing complications has still remained significant. A vast number of genetic and epigenetic variables are thought to contribute to fibrostenosing disease, including those that affect cytokine biology, and therefore highlight the complexity of disease, but also shed light on targetable pathways. Exclusively targeting fibrosis may be difficult, however, because of the relatively slow evolution of fibrosis in CD, and the potential adverse effects of inhibiting pathways involved in tissue repair and mucosal healing. Acknowledging these caveats, cytokine-targeted therapy has become the mainstay of treatment for many inflammatory conditions and is being evaluated for fibrotic disorders. The question of whether anti-cytokine therapy will prove useful for intestinal fibrosis is, therefore, acutely relevant. This review will highlight some of the current therapeutics targeting cytokines involved in fibrosis.

Simvastatin blocks TGF-β1-induced epithelial-mesenchymal transition in human prostate cancer cells

In recent years, the use of statins has been reported to be associated with a reduced risk of prostate cancer (PCa), particularly metastatic PCa. The mechanisms underlying these epidemiological observations are poorly understood. Epithelial-mesenchymal transition (EMT) is a critical initial step and a hallmark for cancer metastasis. In the present study, the relationship between simvastatin and EMT in PCa and the mechanism involved was investigated. It was demonstrated that simvastatin inhibited the EMT as assessed by reduced expression of N-cadherin and vimentin, and increased E-cadherin in TGF-β1 treated DU145 PCa cells. Furthermore, simvastatin inhibited TGF-β1-induced migration and invasion of DU145 cells. The TGF-β1/Smad pathway and non-Smad pathway were investigated in simvastatin-treated DU145 cells. Simvastatin had no effect on TGF-β1-induced phosphorylation of Smad2 and Smad3. In the non-Smad pathway, simvastatin reduced TGF-β1-induced p38 MAPK phosphorylation, but had no effect on TGF-β1-induced Erk1/2 phosphorylation. Simvastatin attenuated TGF-β1-induced EMT, cell migration and invasion in DU145 cells. These effects may have been mediated by the inhibition of p38 MAPK phosphorylation, not through the canonical Smad pathway. Therefore simvastatin may be a promising therapeutic agent for treating PCa.

Simvastatin downregulates expression of TGF-βRII and inhibits proliferation of A549 cells via ERK

Lung cancer is the leading cause of cancer-related death worldwide. Transforming growth factor-β receptor II (TGF-βRII) plays an important role in the regulation of proliferation and progression in cancer. Statins have been documented to exhibit anticancer and cancer chemopreventive properties. However, the effects and mechanisms of simvastatin on the development of lung cancer are still unclear. In the present study, quiescent A549 cells were treated in vitro with fetal bovine serum (FBS) in the presence or absence of simvastatin. MTT, Western blot, and real-time qPCR were used to detect cell viability, activation of ERK, and expression of TGF-βRII at the protein and RNA level. Our results demonstrated that simvastatin inhibited activation of ERK, downregulated expression of TGF-βRII, and suppressed A549 cell proliferation. Furthermore, the effects of simvastatin can be reversed by farnesyl pyrophosphate (FPP). Therefore, these results suggest that simvastatin may inhibit A549 cell proliferation and downregulate TGF-βRII expression by inhibiting activation of ERK. Our findings may advance the current understanding of the effects of simvastatin on cancer progression and contribute to the study of cancer treatment.

Medical therapy of stricturing Crohn's disease: what the gut can learn from other organs - a systematic review

Crohn’s disease (CD) is a chronic remitting and relapsing disease. Fibrostenosing complications such as intestinal strictures, stenosis and ultimately obstruction are some of its most common long-term complications. Despite recent advances in the pathophysiological understanding of CD and a significant improvement of anti-inflammatory therapeutics, medical therapy for stricturing CD is still inadequate. No specific anti-fibrotic therapy exists and the incidence rate of strictures has essentially remained unchanged. Therefore, the current therapy of established fibrotic strictures comprises mainly endoscopic dilation as well as surgical approaches. However, these treatment options are associated with major complications as well as high recurrence rates. Thus, a specific anti-fibrotic therapy for CD is urgently needed. Importantly, there is now a growing body of evidence for prevention as well as effective medical treatment of fibrotic diseases of other organs such as the skin, lung, kidney and liver. In face of the similarity of molecular mechanisms of fibrogenesis across these organs, translation of therapeutic approaches from other fibrotic diseases to the intestine appears to be a promising treatment strategy. In particular transforming growth factor beta (TGF-β) neutralization, selective tyrosine kinase inhibitors, blockade of components of the renin-angiotensin system, IL-13 inhibitors and mammalian target of rapamycin (mTOR) inhibitors have emerged as potential drug candidates for anti-fibrotic therapy and may retard progression or even reverse established intestinal fibrosis. However, major challenges have to be overcome in the translation of novel anti-fibrotics into intestinal fibrosis therapy, such as the development of appropriate biomarkers that predict the development and accurately monitor therapeutic responses. Future clinical studies are a prerequisite to evaluate the optimal timing for anti-fibrotic treatment approaches, to elucidate the best routes of application, and to evaluate the potential of drug candidates to reach the ultimate goal: the prevention or reversal of established fibrosis and strictures in CD patients.

Simvastatin inhibits transforming growth factor-β1-induced expression of type I collagen, CTGF, and α-SMA in keloid fibroblasts

Simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitor, is used to reduce cholesterol levels. Accumulating evidence has revealed the immunomodulatory and anti-inflammatory effects of simvastatin that prevent cardiovascular diseases. In addition, the beneficial effects of statins on fibrosis of various organs have been reported. However, the functional effect of statins on dermal fibrosis of keloids has not yet been explored. The objective of this study was to determine whether simvastatin could affect dermal fibrosis associated with keloids. We examined the effect of simvastatin on transforming growth factor (TGF)-β1-induced production of type I collagen, connective tissue growth factor (CTGF or CCN2), and α-smooth muscle actin (α-SMA). Keloid fibroblasts were cultured and exposed to different concentrations of simvastatin in the presence of TGF-β1, and the effects of simvastatin on TGF-β1-induced collagen and CTGF production in keloid fibroblasts were determined. The type I collagen, CTGF, and α-SMA expression levels and the Smad2 and Smad3 phosphorylation levels were assessed by Western blotting. The effect of simvastatin on cell viability was evaluated by assessing the colorimetric conversion of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. Simvastatin suppressed TGF-β1-induced type I collagen, CTGF, and α-SMA production in a concentration-dependent manner. The TGF-β1-induced Smad2 and Smad3 phosphorylation levels were abrogated by simvastatin pretreatment. The inhibition of type I collagen, CTGF, and α-SMA expression by simvastatin was reversed by geranylgeranyl pyrophosphate, suggesting that the simvastatin-induced cellular responses were due to inhibition of small GTPase Rho involvement. A RhoA activation assay showed that preincubation with simvastatin significantly blocked TGF-β1-induced RhoA activation. The Rho-associated coiled kinase inhibitor Y27632 abrogated TGF-β1-induced production of type I collagen, CTGF, and α-SMA. However, Y27632 had no significant effect on TGF-β1-induced phosphorylation of Smad2 and Smad3. In conclusion, the present study suggests that simvastatin is an effective inhibitor of TGF-β1-induced type I collagen, CTGF, and α-SMA production in keloid fibroblasts.

The influence of CTGF single-nucleotide polymorphisms on outcomes in Crohn's disease

OBJECTIVE

To examine the association between single-nucleotide polymorphisms (SNPs) in CTGF (connective tissue growth factor) and patient outcomes after terminal ileal resection for Crohn's disease.

BACKGROUND

The primary indication for intestinal resection in Crohn's disease is fibrostenotic terminal ileal disease. CTGF is a cytokine overexpressed in the intestine of patients with Crohn's disease that influences outcomes in other disease processes.

METHODS

DNA was extracted from formalin-fixed, paraffin-embedded tissue from 147 patients with Crohn's disease who had undergone terminal ileal resection between 1981 and 2009. Genotyping was performed for 4 CTGF SNPs (rs9402373, rs12526196, rs6918698, and rs9399005), which modulate nuclear factor binding and CTGF production, and a smad3 SNP (rs17293632) involved in the CTGF pathway. Patients were phenotyped using the Montreal Disease Classification.

RESULTS

Sixty-seven of 147 patients (45.6%) were male; the mean age at diagnosis was 30.3 ± 12.6 years and the mean follow-up duration was 8.3 ± 7.1 years. Genotype-phenotype analysis demonstrated that the rs6918698GG genotype was associated with an older age of disease onset [>40 years; 30.6% vs 13.2%; odds ratio (OR): 2.891; 95% confidence interval (CI): 1.170-7.147). The rs9402373CC genotype was positively associated with type B1 disease (50.7% vs 26.3%; OR: 2.876; 95% CI: 1.226-6.743) and negatively associated with B2 disease (37.0% vs 65.0%; OR: 0.317; 95% CI: 0.144-0.699). None of the 5 SNPs assessed influenced clinical or surgical recurrence of Crohn's disease after intestinal resection. On multivariate analysis, male sex odds ratio (OR): 0.235; 95% CI: 0.073-0.755; P = 0.015] and never having smoked tobacco (OR: 0.249; 95% CI: 0.070-0.894; P = 0.033) reduced the risk, whereas having a prior appendectomy increased the risk (OR: 5.048; 95% CI: 1.632-15.617; P = 0.005) of surgical recurrence.

CONCLUSIONS

These data implicate the rs6918698GG genotype with an age of disease onset of greater than 40 years in Crohn's disease whereas the rs9402373CC genotype is associated with a nonstricturing, nonpenetrating disease phenotype. CTGF SNPs do not influence the rate of recurrence after terminal ileal resection for Crohn's disease.

Inhibitory effects of pitavastatin on fibrogenic mediator production by human lung fibroblasts

AIMS

Idiopathic pulmonary fibrosis continues to be a devastating clinical disorder for which there are few therapeutic options, and the pathogenesis of this disease remains largely unknown. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in cholesterol biosynthesis, and they have been reported to exert pleiotropic effects on the cellular signaling involved in tissue inflammation and in organ fibrosis/remodeling. We examined the preventive effects of statins on fibrogenic mediator expression and production in normal human lung fibroblasts (NHLF).

MAIN METHODS

NHLF were pretreated with 100nM pitavastatin or medium alone (control), and were then stimulated with transforming growth factor-β1 (TGF-β1). mRNA expression and protein secretion of several mediators from cells were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay or multiplex assay.

KEY FINDINGS

TGF-β1-induced expression or production of mediators, such as collagen-1, vascular endothelial growth factor and chemokine C-X-C motif ligand 8, in NHLF pretreated with pitavastatin was significantly suppressed with inhibition of Smad-3 phosphorylation, as compared to untreated controls. In addition, the inhibitory effects of pitavastatin were negated by addition of mevalonate.

SIGNIFICANCE

Pitavastatin appeared to inhibit TGF-β1-induced fibrogenic mediator production from lung fibroblasts via the mevalonic cascade. Although further evaluation of the signaling pathways for these phenomena is necessary, our results suggest the potential benefits of pitavastatin.

Circulating fibrocytes and Crohn's disease

Background

Despite advances in medical therapy, there remains no effective preventive or non-surgical therapeutic option for fibrostenotic Crohn's disease (CD). Symptomatic recurrences are common, necessitating reintervention. Intestinal fibroblasts mediate stricture formation, but their exact source is unclear. Recent evidence indicates that circulating fibrocytes drive fibrosis through differentiation into fibroblasts and the production of extracellular matrix proteins. The aim of this review is to describe current understanding of the pathophysiology underlying fibrosis in CD, the cellular and molecular biology of fibrocytes and their role in CD.

Methods

The electronic literature (January 1972 to December 2012) on ‘circulating fibrocytes’ and ‘Crohn's fibrosis’ was reviewed.

Results

Circulating fibrocytes appear universally involved in organ fibrosis. A complex array of cytokines, chemokines and growth factors regulate fibrocyte biology, and these are associated with fibrogenesis in CD. The cytokines transforming growth factor β1, connective tissue growth factor and interleukin 13, overexpressed in the strictured Crohn's intestine, promote fibrocyte generation and/or differentiation.

Conclusion

Levels of circulating fibrocytes are raised in conditions marked by exaggerated fibrosis. These and other observations prompt a characterization of fibrocyte activity in CD with a view to investigating a pathogenic role.

Fluvastatin influences hair color in C57BL/6 mice

Our recent in vitro experiments suggest that fluvastatin may influence tyrosinase (key enzyme of melanogenesis) synthesis. The aim of the present study was to verify those findings in experiments, in vitro, in melanoma cell line, and in vivo, in mice. The expression of tyrosinase in B16F10 melanoma cell line, after induction of melanogenesis by UVB irradiation, was examined by Western blot analysis. Afterwards, the effect of fluvastatin on melanin synthesis in hair follicles of C57Bl/6 mice was investigated. The expression of tyrosinase was reduced in the presence of fluvastatin. In mice after anagen induction over the dorsal skin, gel containing fluvastatin in various concentrations was injected subcutaneously, while in part of control groups of mice, gel with placebo was injected. In addition, gel with fluvastatin was injected to four week-old mice (mice in first postnatal anagen) without anagen induction. In extension, injections of gel with fluvastatin or placebo were performed in mice without anagen induction (but after first postnatal anagen). In part of study group of mice (mice after anagen induction and injection of fluvastatin) regrowth of depigmented hair was observed, while in all control groups (mice after injection of placebo), such hair depigmentation over the skin area was not found. In conclusion, this study, for the first time, shows that fluvastatin might affect melanin synthesis in vivo.

Lovastatin-induced decrease of intracellular cholesterol level attenuates fibroblast-to-myofibroblast transition in bronchial fibroblasts derived from asthmatic patients

Chronic inflammation of the airways and structural changes in the bronchial wall are basic hallmarks of asthma. Human bronchial fibroblasts derived from patients with diagnosed asthma display in vitro predestination towards TGF-β-induced fibroblast-to-myofibroblast transition (FMT), a key event in the bronchial wall remodelling. Statins inhibit 3-hydroxymethyl-3-glutaryl coenzyme A reductase, a key enzyme in the cholesterol synthesis pathway and are widely used as antilipidemic drugs. The pleiotropic anti-inflammatory effects of statins, independent of their cholesterol-lowering capacity, are also well established. Since commonly used anti-asthmatic drugs do not reverse the structural remodelling of the airways and statins have tentative anti-asthmatic activity, we have studied the effect of lovastatin on FMT in populations of human bronchial fibroblasts derived from asthmatic patients. We demonstrate that the intensity of FMT induced by TGF-β1 was strongly and dose-dependently attenuated by lovastatin. Furthermore, we show that neither the suppression of prenylation of signalling proteins nor the effect on reactive oxygen species formation are important for lovastatin-induced inhibition of myofibroblast differentiation. On the other hand, we show that a squalene synthase inhibitor, zaragozic acid A, reduced the TGF-β1-induced FMT to an extent comparable to lovastatin effect. Additionally we demonstrate that in bronchial fibroblast populations, both inhibitors (lovastatin and zaragozic acid A) attenuate the TGF-β1-induced Smad2 nuclear translocation in a manner dependent on intracellular cholesterol level. Our data suggest that statins can directly, by decrease of intracellular cholesterol level, affect basic cell signalling events crucial for asthmatic processes and potentially prevent perilous bronchial wall remodelling associated with intensive myofibroblast formation.

Effects of glycated low-density lipoprotein on cell viability, proliferation, and growth factors of mouse embryo fibroblasts

The predominant cause of death in diabetic patients is atherosclerotic coronary artery disease (CAD). Major gross cellular changes in the vascular wall of persons with CAD include endothelial injury and foam cell formation, as well as smooth muscle cell and fibroblast proliferation. This study examined the effects of glycated low density lipoprotein (glyLDL), a biochemical marker of diabetes, on cell viability, proliferation, and the expression of multiple growth factors in mouse embryo fibroblasts (MEF). The results demonstrated that exposure to ≥150 μg/mL of glyLDL for 24 h or 100 μg/mL of glyLDL for ≥48 h either significantly reduced cell viability or increased DNA fragmentation in MEF. GlyLDL treatment (25-100 μg/mL for up to 12 h) significantly increased the abundance of proliferating cell nuclear antigen (PCNA) and achieved a peak after 4 h exposure to glyLDL. Abundances of fibroblast growth factor-basic (FGF), transforming growth factor-β (TGF), and platelet-derived growth factor-A (PDGF) in MEF reached maximal levels after 2 h exposure to 50 μg/mL of glyLDL. The maximal increase of vascular endothelial growth factor (VEGF) was detected in MEF after 4 h of exposure to 50 μg/mL of glyLDL. Inhibitors for FGF (AZD4547), VEGF, or PDGF receptors (Axitinib), but not that for TGF receptor (LY364947), significantly decreased the abundance of (PCNA) in endothelial cells. The findings suggest that early exposure to a low dosage of glyLDL transiently increases the proliferation of MEF through the upregulation of FGF, VEGF, and (or) PDGF, and prolonged exposure to high concentrations of glyLDL reduced cell viability, which possibly accelerates atherogenesis under diabetic condition.

Rosuvastatin ameliorates high-fat and high-cholesterol diet-induced nonalcoholic steatohepatitis in rats

BACKGROUND/AIMS

Statins, which are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase and inhibit endogenous cholesterol synthesis, possess pleiotropic activities, such as anti-inflammatory, anti-oxidative and antifibrotic effects. Here, we investigated whether statins ameliorate steatohepatitis using a high-fat and high-cholesterol (HFHC) diet-induced rat model.

METHODS

Eight-week-old male Sprague-Dawley rats were fed control chow or HFHC diet. Half of the HFHC diet-fed rats were orally administered 2 mg/kg/day rosuvastatin for 12 weeks. Hepatic injury, steatosis, fibrosis and markers of lipid peroxidation/oxidant stress were evaluated.

RESULTS

As previously reported, HFHC diet induced steatohepatitis in rat livers with hypercholesterolaemia. Rosuvastatin decreased Oil Red O stained-positive areas, liver/body weight ratio, serum total cholesterol levels and hepatic free fatty acid contents in HFHC diet-fed rats. Further study revealed that rosuvastatin significantly decreased hepatic mRNA expression of tumour necrosis factor-α and interleukin-6, serum alanine aminotransferase levels and hepatic lobular inflammation grade. Hepatic fibrosis was also ameliorated by rosuvastatin with decreases in hepatic mRNA expression of transforming growth factor-β, connective tissue growth factor and type-1 procollagen. Similarly, hepatic Sirius red stained or α-smooth muscle actin stained-positive areas and expression of markers of lipid peroxidation/oxidant stress [hepatic 8-hydroxy-oxyguanosine and hepatic 4-hydroxy-2-nonenal] were decreased. Interestingly, whereas the expression of carnitine palmitoyltransferase-1 and long-chain acyl-CoA dehydrogenase was not affected, that of catalase and acyl-coA oxidase was restored.

CONCLUSIONS

These data suggest that rosuvastatin improved not only hepatic steatosis but also hepatic injury and fibrosis via improved peroxisomal β-oxidation in this rat HFHC model.

Local inhibition of angiogenesis by halofuginone coated silicone materials

Anti-angiogenic therapy is a promising approach for the treatment of increased angiogenesis in certain diseases. We aimed to investigate the local anti-angiogenic effect of silicone implants coated with Halofuginone, an angiogenesis inhibitor that inhibits synthesis of collagen-type-I and matrix metalloproteinases. The degree of angiogenesis was observed after implantation of surface modified Halofuginone eluting silicone implants into a submuscular pocket in rats over a period of 3 months. Subsequently, key mediators of angiogenesis (TGF-beta-1, bFGF, COL1A1, MMP-2, MMP-9, VEGF and PDGF) were established by immunohistological staining and RT-PCR and statistically evaluated. In comparison to uncoated silicone implants, Halofuginone eluting silicone implants lead to a significant local decrease of angiogenesis. Halofuginone eluting hybrid surface silicone implants have a significant local anti-angiogenic effect by down-regulating the expression activity of key mediators of angiogenesis.

Effect of Simvastatin on Transforming Growth Factor Beta-1–Induced Myofibroblast Differentiation and Collagen Production in Nasal Polyp-Derived Fibroblasts

Background

Statins are the most commonly prescribed drugs for the treatment of hypercholesterolemia. Statins exert not only lipid-lowering but also other cellular effects, including antifibrotic properties. The purpose of this study was to determine the effect of simvastatin on transforming growth factor (TGF)-beta-1–induced myofibroblast differentiation and collagen production in nasal polyp-derived fibroblasts (NPDFs) and to verify the mechanism of the effect of simvastatin in TGF-beta-1–induced myofibroblast differentiation in NPDFs.

Methods

NPDFs were pretreated with simvastatin with or without mevalonate or Y-27643 for 2 hours before induction by TGF-beta-1. The expression of alpha-smooth muscle actin (SMA) and collagen type IV mRNA was determined by a reverse transcription-polymerase chain reaction, and the expression of alpha-SMA protein was determined by immunofluorescent cytochemical staining. Total soluble collagen production was analyzed by the SirCol collagen dye-binding assay (Biocolor, Belfast, U.K.). Phosphorylation of Smad 2/3 was evaluated by Western blot analysis.

Results

In TGF-beta-1–induced NPDFs, simvastatin significantly inhibited the expressions of α-SMA and collagen type IV mRNA and reduced alpha-SMA and collagen protein levels. Pretreatment with mevalonate reversed the effect of simvastatin. The expression of alpha-SMA mRNA and protein was significantly decreased by pretreatment with Y-27632. The TGF-beta-1–induced expression of pSmad 2/3 protein was notably decreased by pretreatment with simvastatin.

Conclusion

We showed that simvastatin inhibits TGF-beta-1–induced myofibroblast differentiation (expression of alpha-SMA) and collagen production in NPDFs and Rho/Rock and TGF-β/Smad signaling is involved as an underlying mechanism. The results of our study suggest that simvastatin is a possible candidate for the suppression of nasal polyp formation.

N-cadherin is overexpressed in Crohn's stricture fibroblasts and promotes intestinal fibroblast migration

BACKGROUND

Intestinal fibroblasts mediate stricture formation in Crohn's disease (CD). Transforming growth factor-β₁ (TGF-β₁) is important in fibroblast activation, while cell attachment and migration is regulated by the adhesion molecule N-cadherin. The aim of this study was to investigate the expression and function of N-cadherin in intestinal fibroblasts in patients with fibrostenosing CD.

METHODS

Intestinal fibroblasts were cultured from seromuscular biopsies from patients undergoing resection for terminal ileal fibrostenosing CD (n = 14) or controls patients (n = 8). N-cadherin expression was assessed using Western blot and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Fibroblasts were stimulated with TGF-β₁ and selective pathway inhibitors Y27632, PD98050, and LY294002 were used to examine the Rho/ROCK, ERK-1/2, and Akt signaling pathways, respectively. Cell migration was assessed using a scratch wound assay. N-cadherin was selectively overexpressed using a plasmid.

RESULTS

Fibroblasts from fibrostenosing CD express increased constitutive N-cadherin mRNA and protein and exhibit enhanced basal cell migration relative to those from directly adjacent normal bowel. Control fibroblasts treated with TGF-β₁ induced N-cadherin in a dose-dependent manner which was inhibited by Rho/ROCK and Akt pathway modulation. Control fibroblasts exhibited enhanced cell migration in response to treatment with TGF-β₁ or transfection with an N-cadherin plasmid.

CONCLUSIONS

Fibroblasts from strictures in CD express increased constitutive N-cadherin and exhibit enhanced basal cell migration. TGF-β₁ is a potent inducer of N-cadherin in intestinal fibroblasts resulting in enhanced cell migration. The TGF-β₁-mediated induction of N-cadherin may potentiate Crohn's stricture formation.

Role of heat shock protein 47 in intestinal fibrosis of experimental colitis

BACKGROUND AND AIMS

Intestinal fibrosis is a clinically important issue of inflammatory bowel disease (IBD). It is unclear whether or not heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, plays a critical role in intestinal fibrosis. The aim of this study is to investigate the role of HSP47 in intestinal fibrosis of murine colitis.

METHODS

HSP47 expression and localization were evaluated in interleukin-10 knockout (IL-10KO) and wild-type (WT, C57BL/6) mice by immunohistochemistry. Expression of HSP47 and transforming growth factor-β1 (TGF-β1) in colonic tissue was measured. In vitro studies were conducted in NIH/3T3 cells and primary culture of myofibroblasts separated from colonic tissue of IL-10KO (PMF KO) and WT mice (PMF WT) with stimulation of several cytokines. We evaluated the inhibitory effect of administration of small interfering RNA (siRNA) targeting HSP47 on intestinal fibrosis in IL-10KO mice in vivo.

RESULTS

Immunohistochemistry revealed HSP47 positive cells were observed in the mesenchymal and submucosal area of both WT and IL-10 KO mice. Gene expressions of HSP47 and TGF-β1 were significantly higher in IL-10KO mice than in WT mice and correlated with the severity of inflammation. In vitro experiments with NIH3T3 cells, TGF-β1 only induced HSP47 gene expression. There was a significant difference of HSP47 gene expression between PMF KO and PMF WT. Administration of siRNA targeting HSP47 remarkably reduced collagen deposition in colonic tissue of IL-10KO mice.

CONCLUSIONS

Our results indicate that HSP47 plays an essential role in intestinal fibrosis of IL-10KO mice, and may be a potential target for intestinal fibrosis associated with IBD.

Statins inhibit angiotensin II/Smad pathway and related vascular fibrosis, by a TGF-β-independent process

We have recently described that in an experimental model of atherosclerosis and in vascular smooth muscle cells (VSMCs) statins increased the activation of the Smad pathway by transforming growth factor-β (TGF-β), leading to an increase in TGF-β-dependent matrix accumulation and plaque stabilization. Angiotensin II (AngII) activates the Smad pathway and contributes to vascular fibrosis, although the in vivo contribution of TGF-β has not been completely elucidated. Our aim was to further investigate the mechanisms involved in AngII-induced Smad activation in the vasculature, and to clarify the beneficial effects of statins on AngII-induced vascular fibrosis. Infusion of AngII into rats for 3 days activates the Smad pathway and increases fibrotic-related factors, independently of TGF-β, in rat aorta. Treatment with atorvastatin or simvastatin inhibited AngII-induced Smad activation and related-fibrosis. In cultured rat VSMCs, direct AngII/Smad pathway activation was mediated by p38 MAPK and ROCK activation. Preincubation of VSMCs with statins inhibited AngII-induced Smad activation at all time points studied (from 20 minutes to 24 hours). All these data show that statins inhibited several AngII-activated intracellular signaling systems, including p38-MAPK and ROCK, which regulates the AngII/Smad pathway and related profibrotic factors and matrix proteins, independently of TGF-β responses. The inhibitory effect of statins on the AngII/Smad pathway could explain, at least in part, their beneficial effects on hypertension-induced vascular damage.

Bacterial lipopolysaccharide promotes profibrotic activation of intestinal fibroblasts

BACKGROUND

Fibroblasts play a critical role in intestinal wound healing. Lipopolysaccharide (LPS) is a cell wall component of commensal gut bacteria. The effects of LPS on intestinal fibroblast activation were characterized.

METHODS

Expression of the LPS receptor, toll-like receptor (TLR) 4, was assessed in cultured primary human intestinal fibroblasts using flow cytometry and confocal microscopy. Fibroblasts were treated with LPS and/or transforming growth factor (TGF) beta1. Nuclear factor kappaB (NFkappaB) pathway activation was assessed by inhibitory kappaBalpha (IkappaBalpha) degradation and NFkappaB promoter activity. Fibroblast contractility was measured using a fibroblast-populated collagen lattice. Smad-7, a negative regulator of TGF-beta1 signalling, and connective tissue growth factor (CTGF) expression were assessed using reverse transcriptase-polymerase chain reaction and western blot. The NFkappaB pathway was inhibited by IkappaBalpha transfection.

RESULTS

TLR-4 was present on the surface of intestinal fibroblasts. LPS treatment of fibroblasts induced IkappaBalpha degradation, enhanced NFkappaB promoter activity and increased collagen contraction. Pretreatment with LPS (before TGF-beta1) significantly increased CTGF production relative to treatment with TGF-beta1 alone. LPS reduced whereas TGF-beta1 increased smad-7 expression. Transfection with an IkappaBalpha plasmid enhanced basal smad-7 expression.

CONCLUSION

Intestinal fibroblasts express TLR-4 and respond to LPS by activating NFkappaB and inducing collagen contraction. LPS acts in concert with TGF-beta1 to induce CTGF. LPS reduces the expression of the TGF-beta1 inhibitor, smad-7.

Endoglin negatively regulates transforming growth factor beta1-induced profibrotic responses in intestinal fibroblasts

BACKGROUND

Fibroblasts isolated from strictures in Crohn's disease (CD) exhibit reduced responsiveness to stimulation with transforming growth factor (TGF) beta1. TGF-beta1, acting through the smad pathway, is critical to fibroblast-mediated intestinal fibrosis. The membrane glycoprotein, endoglin, is a negative regulator of TGF-beta1.

METHODS

Intestinal fibroblasts were cultured from seromuscular biopsies of patients undergoing intestinal resection for CD strictures or from control patients. Endoglin expression was assessed using confocal microscopy, flow cytometry and western blot. The effect of small interfering (si) RNA-mediated knockdown and plasmid-mediated overexpression of endoglin on fibroblast responsiveness to TGF-beta1 was assessed by examining smad phosphorylation, smad binding element (SBE) promoter activity, connective tissue growth factor (CTGF) expression and ability to contract collagen.

RESULTS

Crohn's stricture fibroblasts expressed increased constitutive cell-surface and whole-cell endoglin relative to control cells. Endoglin co-localized with filamentous actin. Fibroblasts treated with siRNA directed against endoglin exhibited enhanced TGF-beta1-mediated smad-3 phosphorylation, and collagen contraction. Cells transfected with an endoglin plasmid did not respond to TGF-beta1 by exhibiting SBE promoter activity or producing CTGF.

CONCLUSION

Fibroblasts from strictures in CD express increased constitutive endoglin. Endoglin is a negative regulator of TGF-beta1 signalling in the intestinal fibroblast, modulating smad-3 phosphorylation, SBE promoter activity, CTGF production and collagen contraction.

A chemical biology screen reveals a role for Rab21-mediated control of actomyosin contractility in fibroblast-driven cancer invasion

Background:

Carcinoma-associated fibroblasts (CAFs) can promote the progression of tumours in many ways. They can remodel the extracellular matrix to generate an environment that enables the invasion of cancer cells. We hypothesised that compounds that prevent matrix remodelling by CAFs would block their ability to promote carcinoma cell invasion.

Methods:

We designed a screen for compounds that interfere with CAF-promoted matrix remodelling. Hits from this screen were investigated in organotypic invasion models of squamous cell carcinoma (SCC).

Results:

We find that lovastatin and simvastatin reduce matrix remodelling by fibroblasts and thereby reduce SCC invasion. This class of compounds exert their effects partly through disrupting the function of Rab proteins, and we show a new role for Rab21 in promoting cancer cell invasion promoted by CAFs.

Conclusions:

Rab21 is required for CAFs to promote the invasion of cancer cells. It enables the accumulation of integrin α5 at the plasma membrane and subsequent force-mediated matrix remodelling.