Hepatoprotective Effect of MMP-19 Deficiency in a Mouse Model of Chronic Liver Fibrosis Marketa Jirouskova1., Olga Zbodakova1., Martin Gregor1, Karel Chalupsky1, Lenka Sarnova1, Marian Hajduch2, Jiri Ehrmann2,3, Marie Jirkovska4, Radislav Sedlacek1* 1 Institute of Molecular Genetics of the ASCR, Prague, Czech Republic, 2 Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University and University Hospital in Olomouc, Olomouc, Czech Republic, 3 Department of Clinical and Molecular Pathology, Faculty of Medicine and Dentistry, Palacky University and University Hospital in Olomouc, Olomouc, Czech Republic, 4 Institute of Histology and Embryology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic Abstract Liver fibrosis is characterized by the deposition and increased turnover of extracellular matrix. This process is controlled by matrix metalloproteinases (MMPs), whose expression and activity dynamically change during injury progression. MMP-19, one of the most widely expressed MMPs, is highly expressed in liver; however, its contribution to liver pathology is unknown. The aim of this study was to elucidate the role of MMP-19 during the development and resolution of fibrosis by comparing the response of MMP-19-deficient (MMP19KO) and wild-type mice upon chronic liver CCl4-intoxication. We show that loss of MMP-19 was beneficial during liver injury, as plasma ALT and AST levels, deposition of fibrillar collagen, and phosphorylation of SMAD3, a TGF-ß1 signaling molecule, were all significantly lower in MMP19KO mice. The ameliorated course of the disease in MMP19KO mice likely results from a slower rate of basement membrane destruction and ECM remodeling as the knockout mice maintained significantly higher levels of type IV collagen and lower expression and activation of MMP-2 after 4 weeks of CCl4-intoxication. Hastened liver regeneration in MMP19KO mice was associated with slightly higher IGF-1 mRNA expression, slightly increased phosphorylation of Akt kinase, decreased TGF-ß1 mRNA levels and significantly reduced SMAD3 phosphorylation. In addition, primary hepatocytes isolated from MMP19KO mice showed impaired responsiveness towards TGF-ß1 stimulation, resulting in lower expression of Snail1 and vimentin mRNA. Thus, MMP-19-deficiency improves the development of hepatic fibrosis through the diminished replacement of physiological extracellular matrix with fibrotic deposits in the beginning of the injury, leading to subsequent changes in TGF-ß and IGF-1 signaling pathways. Citation: Jirouskova M, Zbodakova O, Gregor M, Chalupsky K, Sarnova L, et al. (2012) Hepatoprotective Effect of MMP-19 Deficiency in a Mouse Model of Chronic Liver Fibrosis. PLoS ONE 7(10): e46271. doi:10.1371/journal.pone.0046271 Editor: Bernhard Ryffel, French National Centre for Scientific Research, France Received May 19, 2012; Accepted August 28, 2012; Published October 9, 2012 Copyright: 2012 Jirouskova et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: Financial support was given to RS by GAAV (The Grant Agency of the Academy of Sciences of the Czech Republic) (IAA500520812; http://www.gaav.cz), GACR (Grantova Agentura Ceske Pepubliky) (P303/10/2044; http://www.gacr.cz/), Academy of Sciences of the Czech Republic (RVO 68378050; http://www.cas.cz/), and by Ministry of School and Education, Czech Republic (Operational Program Research and Development for Innovations) to RS (CZ.1.05/1.1.00/02.0109) and MH (CZ.1.05/2.1.00/01.0030; http://www.msmt.cz/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: radislav.sedlacek@img.cas.cz . These authors contributed equally to this work. Introduction Liver fibrosis and its possible progression toward cirrhosis is a result of a wound healing process by which the liver responds to continuous chronic injury. This pathological process engages many cell types and mediators and results in the excess deposition of extracellular matrix (ECM) proteins, causing a distortion of the normal liver architecture and function that potentially lead to liver failure [1]. During hepatic fibrogenesis, the physiologic ECM that is rich in basement membrane components, predominantly type IV collagen (collagen IV), is degraded and replaced by interstitial matrix fibers, i.e. predominantly collagens I and III [2]. Remodeling of ECM is controlled by matrix metalloproteinases (MMPs) whose expression and activity dynamically change during liver injury and recovery [3]. MMPs and their inhibitors, TIMPs, are thought to regulate matrix turnover, and their imbalance determines the processes of fibrogenesis and fibrolysis [4]. It was shown that toxic liver injury is associated with increased levels of most MMPs while TIMPs were downregulated [3]. In contrast, chronic liver injury is characterized by lower matrix degradation correlating with lower MMP expression while TIMP production is augmented [3]. Although it has been shown that general inhibitors of MMPs, for instance, attenuate hepatic fibrosis [5] or are useful to inhibit acute, and chronic inflammatory or vascular diseases as reviewed in [6], we have an incomplete understanding of the roles the individual MMPs may play during liver injury. MMP-2 was shown to be increased in fibrotic liver [7,8], and its expression was thought to be pro-fibrotic by its ability to degrade collagen IV [9]. However, recent studies have reported that MMP-2-deficient animals show increased liver fibrosis, due to increased collagen I synthesis [10] and suppressed TIMP-1 upregulation [2,11]. MMP- 13, a collagen I degrading MMP, which is highly increased at the beginning of liver injury and during the recovery period, was PLOS ONE | www.plosone.org 1 October 2012 | Volume 7 | Issue 10 | e46271