http://www.fibrogenesis.com The latest research articles published by Fibrogenesis & Tissue Repair 2010-02-17T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ Background: Expression of insulin-like growth factor binding protein 5 (IGFBP5) is strongly induced upon activation of hepatic stellate cells and their transdifferentiation into myofibroblasts in vitro. This was confirmed in vivo in an animal model of liver fibrosis. Since IGFBP5 has been shown to promote fibrosis in other tissues, the aim of this study was to investigate its role in the progression of liver fibrosis. Methods: The effect of IGFBP5 was studied in LX2 cells, a model for partially activated hepatic stellate cells, and in human primary liver myofibroblasts. IGFBP5 signalling was modulated by the addition of recombinant protein, by lentiviral overexpression, and by siRNA mediated silencing. Furthermore, the addition of IGF1 and silencing of the IGF1R was used to investigate the role of the IGF-axis in IGFBP5 mediated effects. Results: IGFBP5 enhanced the survival of LX2 cells and myofibroblasts via a >50% suppression of apoptosis. This effect of IGFBP5 was not modulated by the addition of IGF1, nor by silencing of the IGF1R. Additionally, IGFBP5 was able to enhance the expression of established pro-fibrotic markers, such as collagen Iα1, TIMP1 and MMP1. Conclusion: IGFBP5 enhances the survival of (partially) activated hepatic stellate cells and myofibroblasts by lowering apoptosis via an IGF1-independent mechanism, and enhances the expression of profibrotic genes. Its lowered expression may, therefore, reduce the progression of liver fibrosis. http://www.fibrogenesis.com/content/3/1/3 Aleksandar Sokolovic Milka Sokolovic Willem Boers Ronald Oude Elferink Piter Bosma Fibrogenesis & Tissue Repair 2010, 3:3 2010-02-17T00:00:00Z doi:10.1186/1755-1536-3-3 Fibrogenesis & Tissue Repair 1755-1536 3 3 2010-02-17T00:00:00Z XML Background: Defective epithelial repair, excess fibroblasts and myofibroblasts, collagen overproduction and fibrosis occur in a number of respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. Pathological conversion of epithelial cells into fibroblasts (epithelial-mesenchymal transition, EMT) has been proposed as a mechanism for the increased fibroblast numbers and has been demonstrated to occur in lung alveolar epithelial cells. Whether other airway cell types also have the capability to undergo EMT has been less explored so far. A better understanding of the full extent of EMT in airways, and the underlying mechanisms, can provide important insights into airway disease pathology and enable the development of new therapies. The main aim of this study was to test whether primary human bronchial epithelial cells are able to undergo EMT in vitro and to investigate the effect of various profibrotic factors in the process. Results: Our data demonstrate that primary human bronchial epithelial cells (HBECs) are able to undergo EMT in response to transforming growth factor-beta 1 (TGF-β1), as revealed by typical morphological alterations and EMT marker progression at the RNA level by real-time quantitative polymerase chain reaction and, at the protein level, by western blot. By using pharmacological inhibitors we show that this is a Smad-dependent mechanism and is independent of extracellular signal-related kinase pathway activation. Additional cytokines and growth factors such as tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL1β) and connective tissue growth factor (CTGF) were also tested, alone or in combination with TGF-β1. TNF-α markedly enhances the effect of TGF-β1 on EMT, whereas IL1β shows only a very weak effect and CTGF has no significant effect. We have also found that cell-matrix contact, in particular to fibronectin, an ECM component upregulated in fibrotic lesions, potentiates EMT in both human alveolar epithelial cells and HBECs. Furthermore, we also show that the collagen discoidin domain receptor 1 (DDR1), generally expressed in epithelial cells, is downregulated during the EMT of bronchial epithelium whereas DDR2 is unaffected. Our results also suggest that bone morphogenetic protein-4 is likely to have a context dependent effect during the EMT of HBECs, being able to induce the expression of EMT markers and, at the same time, to inhibit TGF-β induced epithelial transdifferentiation. Conclusions: The results presented in this study provide additional insights into EMT, a potentially very important mechanism in fibrogenesis. We show that, in addition to alveolar epithelial type II cells, primary HBECs are also able to undergo EMT in vitro upon TGF-β1 stimulation via a primarily Smad 2/3 dependent mechanism. The effect of TGF-β1 is potentiated on fibronectin matrix and in the presence of TNF-α, representing a millieu reminiscent of fibrotic lesions. Our results can contribute to a better understanding of lung fibrosis and to the development of new therapeutic approaches. http://www.fibrogenesis.com/content/3/1/2 Joana Camara Gabor Jarai Fibrogenesis & Tissue Repair 2010, 3:2 2010-01-05T00:00:00Z doi:10.1186/1755-1536-3-2 Fibrogenesis & Tissue Repair 1755-1536 3 2 2010-01-05T00:00:00Z XML Background: Pin 1 is a peptidyl-prolyl isomerase inhibitor related to cyclophilin A and FK506 binding protein (FKBP). Juglone (5-hydroxy-1,4-naphthoquinone) is a natural inhibitor of Pin 1 with anti-inflammatory and antifibrotic properties. We evaluated the role of Pin 1 in renal fibrogenesis by evaluating the effects of juglone on epithelial to mesenchymal transition (EMT) and fibrogenesis in the rat unilateral ureteral obstruction (UUO) model and normal rat tubular epithelial cells (NRK52E). Results: After 2 weeks of UUO, immunoblot analyses demonstrated that juglone (0.25 and 1 mg/kg/24 h) inhibited the deposition of matrix (α-smooth muscle actin (SMA), collagen type III and vimentin) and the activation of signaling pathways involved in fibrogenesis (phospho-smad2) and stress response (phospho-heat shock protein (HSP)27). Juglone also reduced EMT (α-SMA and E-cadherin dual staining) and oxidative stress (Mn superoxide dismutase (SOD) and NAPDH oxidase 2 (Nox-2) dual staining) in the obstructed kidney. There was no difference in Pin 1 levels between treatment and control groups. Pin 1 activity was significantly decreased in obstructed kidneys regardless of treatment status. In vitro, juglone (1 μM) significantly decreased α-SMA and p-smad levels compared to vehicle. Conclusions: Juglone attenuates fibrogenesis via Pin 1-independent mechanisms in the UUO model. The antifibrotic effects of juglone may result from the inhibition of smad2 and oxidative stress. http://www.fibrogenesis.com/content/3/1/1 Shannon Reese Aparna Vidyasagar Lynn Jacobson Zeki Acun Stephane Esnault Debra Hullett James Malter Arjang Djamali Fibrogenesis & Tissue Repair 2010, 3:1 2010-01-04T00:00:00Z doi:10.1186/1755-1536-3-1 Fibrogenesis & Tissue Repair 1755-1536 3 1 2010-01-04T00:00:00Z XML Fibrosis represents a major global disease burden, yet a potent antifibrotic compound is still not in sight. Part of the explanation for this situation is the difficulties that both academic laboratories and research and development departments in the pharmaceutical industry have been facing in re-enacting the fibrotic process in vitro for screening procedures prior to animal testing. Effective in vitro characterization of antifibrotic compounds has been hampered by cell culture settings that are lacking crucial cofactors or are not holistic representations of the biosynthetic and depositional pathway leading to the formation of an insoluble pericellular collagen matrix. In order to appreciate the task which in vitro screening of antifibrotics is up against, we will first review the fibrotic process by categorizing it into events that are upstream of collagen biosynthesis and the actual biosynthetic and depositional cascade of collagen I. We point out oversights such as the omission of vitamin C, a vital cofactor for the production of stable procollagen molecules, as well as the little known in vitro tardy procollagen processing by collagen C-proteinase/BMP-1, another reason for minimal collagen deposition in cell culture. We review current methods of cell culture and collagen quantitation vis-à-vis the high content options and requirements for normalization against cell number for meaningful data retrieval. Only when collagen has formed a fibrillar matrix that becomes cross-linked, invested with ligands, and can be remodelled and resorbed, the complete picture of fibrogenesis can be reflected in vitro. We show here how this can be achieved. A well thought-out in vitro fibrogenesis system represents the missing link between brute force chemical library screens and rational animal experimentation, thus providing both cost-effectiveness and streamlined procedures towards the development of better antifibrotic drugs. http://www.fibrogenesis.com/content/2/1/7 Clarice Chen Michael Raghunath Fibrogenesis & Tissue Repair 2009, 2:7 2009-12-15T00:00:00Z doi:10.1186/1755-1536-2-7 Fibrogenesis & Tissue Repair 1755-1536 2 7 2009-12-15T00:00:00Z XML Fibrosis can occur in tissues in response to a variety of stimuli. Following tissue injury, cells undergo transformation or activation from a quiescent to an activated state resulting in tissue remodelling. The fibrogenic process creates a tissue environment that allows inflammatory and matrix-producing cells to invade and proliferate. While this process is important for normal wound healing, chronicity can lead to impaired tissue structure and function.This review examines the major factors involved in transforming or activating tissues towards fibrosis. The role of genetic variation within individuals affected by fibrosis has not been well described and it is in this context that we have examined the mediators of remodelling, including transforming growth factor-beta, T helper 2 cytokines and matrix metalloproteinases.Finally we examine the role of Toll-like receptors in fibrosis. The inflammatory phenotype that precedes fibrosis has been associated with Toll-like receptor activation. This is particularly important when considering gastrointestinal and hepatic disease, where inappropriate Toll-like receptor signalling, in response to the local microbe-rich environment, is thought to play an important role. http://www.fibrogenesis.com/content/2/1/6 Georgina Hold Paraskevi Untiveros Karin Saunders Emad El-Omar Fibrogenesis & Tissue Repair 2009, 2:6 2009-12-04T00:00:00Z doi:10.1186/1755-1536-2-6 Fibrogenesis & Tissue Repair 1755-1536 2 6 2009-12-04T00:00:00Z XML Background: Arthrofibrosis, occurring in 3%-4% of patients following total knee arthroplasty (TKA), is a challenging condition for which there is no defined cause. The hypothesis for this study was that disregulated production of reactive oxygen species (ROS) and nitrogen species (RNS) mediates matrix protein and DNA modifications, which result in excessive fibroblastic proliferation. Results: We found increased numbers of macrophages and lymphocytes, along with elevated amounts of myeloperoxidase (MPO) in arthrofibrotic tissues when compared to control tissues. MPO expression, an enzyme that generates ROS/RNS, is usually limited to neutrophils and some macrophages, but was found by immunohistochemistry to be expressed in both macrophages and fibroblasts in arthrofibrotic tissue. As direct measurement of ROS/RNS is not feasible, products including DNA hydroxylation (8-OHdG), and protein nitrosylation (nitrotyrosine) were measured by immunohistochemistry. Quantification of the staining showed that 8-OHdg was significantly increased in arthrofibrotic tissue. There was also a direct correlation between the intensity of inflammation and ROS/RNS to the amount of heterotopic ossification (HO). In order to investigate the aberrant expression of MPO, a real-time oxidative stress polymerase chain reaction array was performed on fibroblasts isolated from arthrofibrotic and control tissues. The results of this array confirmed the upregulation of MPO expression in arthrofibrotic fibroblasts and highlighted the downregulated expression of the antioxidants, superoxide dismutase1 and microsomal glutathione S-transferase 3, as well as the significant increase in thioredoxin reductase, a known promoter of cell proliferation, and polynucleotide kinase 3'-phosphatase, a key enzyme in the base excision repair pathway for oxidative DNA damage. Conclusion: Based on our current findings, we suggest that ROS/RNS initiate and sustain the arthrofibrotic response driving aggressive fibroblast proliferation and subsequent HO. http://www.fibrogenesis.com/content/2/1/5 Theresa Freeman Javad Parvizi Craig Della Valle Marla Steinbeck Fibrogenesis & Tissue Repair 2009, 2:5 2009-11-13T00:00:00Z doi:10.1186/1755-1536-2-5 Fibrogenesis & Tissue Repair 1755-1536 2 5 2009-11-13T00:00:00Z XML Background: Human chronic liver diseases (CLDs) with different aetiologies rely on chronic activation of wound healing that represents the driving force for fibrogenesis progression (throughout defined patterns of fibrosis) to the end stage of cirrhosis and liver failure.IssuesFibrogenesis progression has a major worldwide clinical impact due to the high number of patients affected by CLDs, increasing mortality rate, incidence of hepatocellular carcinoma and shortage of organ donors for liver transplantation.Basic science advancesLiver fibrogenesis is sustained by a heterogeneous population of profibrogenic hepatic myofibroblasts (MFs), the majority being positive for α smooth muscle actin (αSMA), that may originate from hepatic stellate cells and portal fibroblasts following a process of activation or from bone marrow-derived cells recruited to damaged liver and, in a method still disputed, by a process of epithelial to mesenchymal transition (EMT) involving cholangiocytes and hepatocytes. Recent experimental and clinical data have identified, at tissue, cellular and molecular level major profibrogenic mechanisms: (a) chronic activation of the wound-healing reaction, (b) oxidative stress and related reactive intermediates, and (c) derangement of epithelial-mesenchymal interactions.Clinical care relevanceLiver fibrosis may regress following specific therapeutic interventions able to downstage or, at least, stabilise fibrosis. In cirrhotic patients, this would lead to a reduction of portal hypertension and of the consequent clinical complications and to an overall improvement of liver function, thus extending the complication-free patient survival time and reducing the need for liver transplantation. Conclusion: Emerging mechanisms and concepts related to liver fibrogenesis may significantly contribute to clinical management of patients affected by CLDs. http://www.fibrogenesis.com/content/2/1/4 Maurizio Parola Massimo Pinzani Fibrogenesis & Tissue Repair 2009, 2:4 2009-09-25T00:00:00Z doi:10.1186/1755-1536-2-4 Fibrogenesis & Tissue Repair 1755-1536 2 4 2009-09-25T00:00:00Z XML In most adult epithelia the process of replacing damaged or dead cells is maintained through the presence of stem/progenitor cells, which allow epithelial tissues to be repaired following injury. Existing evidence strongly supports the presence of stem cells in the adult kidney. Indeed, recent findings provide evidence in favour of a role for intrinsic renal cells and against a physiological role for bone marrow-derived stem cells in the regeneration of renal epithelial cells. In addition, recent studies have identified a subset of CD24+CD133+ renal progenitors within the Bowman's capsule of adult human kidney, which provides regenerative potential for injured renal epithelial cells. Intriguingly, CD24+CD133+ renal progenitors also represent common progenitors of tubular cells and podocytes during renal development. Chronic injury causes dysfunction of the tubular epithelial cells, which triggers the release of fibrogenic cytokines and recruitment of inflammatory cells to injured kidneys. The rapid interposition of scar tissue probably confers a survival advantage by preventing infectious microorganisms from invading the wound, but prevents subsequent tissue regeneration. However, the existence of renal epithelial progenitors in the kidney suggests a possible explanation for the regression of renal lesions which has been observed in experimental animals and even in humans. Thus, manipulation of the wound repair process in order to shift it towards regeneration will probably require the ability to slow the rapid fibrotic response so that renal progenitor cells can allow tissue regeneration rather than scar formation. http://www.fibrogenesis.com/content/2/1/3 Paola Romagnani Raghu Kalluri Fibrogenesis & Tissue Repair 2009, 2:3 2009-06-26T00:00:00Z doi:10.1186/1755-1536-2-3 Fibrogenesis & Tissue Repair 1755-1536 2 3 2009-06-26T00:00:00Z XML Background: Regression of hepatic fibrosis in patients with autoimmune hepatitis (AIH) has been described in response to immunosuppressive therapy. These studies, however, besides being few in number, were conducted on adult populations. Our aim was to assess the regression of hepatic fibrosis, using morphometric assessment of fibrosis versus semi-quantitative methods, in children with AIH who achieved clinical and biochemical remission. Thirteen patients who achieved clinical and biochemical remission were included in the study, out of 62 children with AIH. Repeat biopsy was performed after 6 to 12 months of clinical and biochemical remission. Morphometric assessment of fibrosis was performed and correlated with METAVIR and Ishak semi-quantitative scores. Results: The study group included eight male and five female patients. The median age at presentation was 4 years (range 2 to 12 years). The mean duration of treatment was 22 ± 7.3 months, and the mean interval between biopsies was 26.2 ± 6.5 months. Following therapy, there was significant reduction in aspartate aminotransferase, ALT and IgG levels as well as improvement of necroinflammation. The mean fibrosis scores were significantly decreased from 4.5 ± 1.19 and 2.9 ± 0.7 before therapy to 2.7 ± 1.16 and 2 ± 0.8 after treatment as assessed by Ishak and METAVIR scores, respectively (P = 0.001 and 0.004). The mean morphometric assessment of fibrosis before treatment was 20% ± 9.7 and following therapy it decreased to 5.6% ± 3.9 (P = 0.000). Conclusion: Significant regression of fibrosis in paediatric AIH could occur with current therapeutic regimens. Morphometric assessment of fibrosis is more sensitive than semi-quantitative methods to identify changes in fibrosis. http://www.fibrogenesis.com/content/2/1/2 Ahmed Abdalla Khaled Zalata Abeer Ismail Gamal Shiha Mohamed Attiya Ahmed Abo-Alyazeed Fibrogenesis & Tissue Repair 2009, 2:2 2009-04-02T00:00:00Z doi:10.1186/1755-1536-2-2 Fibrogenesis & Tissue Repair 1755-1536 2 2 2009-04-02T00:00:00Z XML Background: Human hepatic stellate cells have been shown to be resistant to apoptotic stimuli. This is likely dependent on the activation of anti-apoptotic pathways upon transition of these cells to myofibroblast-like cells. In particular, previous studies have demonstrated an increased expression of the anti-apoptotic protein Bcl-2 and a decreased expression of the pro-apoptotic protein Bax during the transition of the hepatic stellate cell phenotype from quiescent to myofibroblast-like cells. However, the role and expression of other key anti-apoptotic and survival pathways elicited by polypeptide growth factors involved in the chronic wound healing process remain to be elucidated. In particular, insulin growth factor-I promotes chemotactic and mitogenic effects in activated human hepatic stellate cells and these effects are mediated by the activation of PI 3-K. The role of insulin growth factor-I as a survival factor in human hepatic stellate cells needs to be substantiated. The aim of this study was to evaluate the involvement of other key anti-apoptotic pathways such as PI-3K/Akt/p-Bad in response to insulin growth factor-I. Results: Insulin growth factor-I induced activation of Akt followed by Bad phosphorylation after 15 minutes of incubation. These effects were PI-3k dependent since selective inhibitors of this molecule, wortmannin and LY294002, inhibited both Akt and Bad phosphorylation. The effect of insulin growth factor-I on the activation of two downstream targets of Akt activation, that is, GSK3 and FHKR, both implicated in the promotion of cell survival was also investigated. Both targets became phosphorylated after 15 minutes of incubation, and these effects were also PI-3K-dependent. Despite the activation of this survival pathway insulin growth factor-I did not have a remarkable biological effect, probably because other insulin growth factor-I-independent survival pathways were already maximally activated in the process of hepatic stellate cell activation. However, after incubation of the cells with a strong apoptotic stimuli such as Fas ligand+cycloheximide, a small percentage of hepatic stellate cells underwent programmed cell death that was partially rescued by insulin growth factor-I. Conclusion: In addition to Bcl-2, several other anti-apoptotic pathways are responsible for human hepatic stellate cell resistance to apoptosis. These features are relevant for the progression and limited reversibility of liver fibrosis in humans. http://www.fibrogenesis.com/content/2/1/1 Alessandra Gentilini Benedetta Lottini Marco Brogi Alessandra Caligiuri Lorenzo Cosmi Fabio Marra Massimo Pinzani Fibrogenesis & Tissue Repair 2009, 2:1 2009-01-30T00:00:00Z doi:10.1186/1755-1536-2-1 Fibrogenesis & Tissue Repair 1755-1536 2 1 2009-01-30T00:00:00Z XML