The study was approved by the Tel Aviv University Institutional animal care and use committee and performed in compliance with their guidelines. Proteins and antibodies Mouse PCPE-1 (mPCPE-1) was purified from culture media of 3T6 mouse fibroblasts by ammonium sulfate fractionation, gel-filtration, lysyl-Sepharose chromatography and affinity chromatography on Sepharose coupled to the C-propeptide of type I procollagen as described . for type I collagen and PCPE-1. The normal plasma concentration of PCPE-1 in 6 weeks to 4 months old mice was ~200 ng/ml (189.5 11.3 to 206.8 13.8 ng/ml). PCPE-1 plasma concentrations in four and 8.5 months old mice displaying fibrotic diaphragms increased 27 and 40% respectively relatively to age-matched control mice, an increase comparable to that of the N-propeptide of procollagen type III (PIIINP), a known blood marker of fibrosis. PCPE-1 plasma levels in mice with CCl4-induced liver fibrosis increased 34 to 50% relatively to respective controls and reflected the severity of the disease, namely increased gradually during the progression of fibrosis and went down to basal levels during recovery, in parallel to changes in the liver content of collagen I and PCPE-1. The results favor PCPE-1 as a potential new clinically valuable fibrosis biomarker. Introduction Fibrosis is a non-physiological scarring process associated with excessive deposition of extracellular matrix (ECM), leading to impairment of organ function . It can affect many organs and tissues, including liver, kidney, heart, lung, skin (hypertrophic scars, keloids) and skeletal muscles [1C3]. Various triggers can contribute to the development of fibrotic diseases, including inherited disorders, persistent infections, recurrent exposure to toxins, irritants or smoke, chronic autoimmune inflammation, myocardial infarction and hypertension [1C4]. A feature common to all fibrotic diseases is abnormal accumulation of collagen and other ECM components in the extracellular space that are produced by Glycopyrrolate activated fibroblasts (myofibroblasts). This is evident Glycopyrrolate for instance in left ventricular hypertrophy that results from chronic hypertension and may lead to heart failure  and liver fibrosis that is often caused by chronic hepatitis C virus infection or chronic alcohol abuse and may lead to cirrhosis and hepatocellular dysfunction . Procollagen C-proteinase enhancer 1 (PCPE-1) is a connective tissue glycoprotein that increases the rate of release of the carboxyl-propeptide from fibrillar procollagens by procollagen C-proteinases (PCPs) [7C9], a reaction critical for the assembly of collagen fibrils. PCPE-1 (50/55 kDa for human and rodent PCPE-1, respectively) consists of two CUB (Complement-Uegf-Bone morphogenetic protein 1) domains that bind to the C-propeptide of types I and III procollagen and are required for enhancing activity, and a netrin-like (NTR) domain that mediates binding to heparin, heparan sulfate proteoglycans (e.g., syndecans) and fibronectin [10C12]. The enhancing activity of PCPE-1 appears to be restricted to fibrillar procollagens because it does not affect processing of any other PCPs substrate tested to date [13,14]. The tissue distribution of Gja5 PCPE-1 overlaps that of collagen type I. It is abundant in tissues rich in collagen I such as tendon, bone, skin and cornea, expressed to a lower extent in tissues containing lower amounts of collagen I such as skeletal muscles, heart, and kidney, and is practically undetectable in organs producing no (or negligible amounts of) type I collagen such as brain and liver [8,10]. The expression of PCPE-1, like that Glycopyrrolate of collagen type I, is up-regulated in organs undergoing fibrosis including liver [15,16], heart [17,18], skin (hypertrophic/keloid scars)  and cornea . PCPE-1 expression in cultured fibroblasts is also coordinated with that of collagen I [15,16,18,20]. PCPE-1 is therefore recognized as an important regulator of collagen deposition and potential target for intervention with fibrosis [17,21]. Worth noting in this context, PCPE-1 is found in human sera Glycopyrrolate Glycopyrrolate [22C24], plasma  and cerebrospinal fluid [26,27] as well as rat plasma . None-invasive diagnosis of fibrosis relies on imaging techniques and immunoassays of blood biomarkers [6, 28C30]. Blood markers used to evaluate liver fibrosis are classified as direct when they measure extracellular matrix components or indirect when they measure.
The study was approved by the Tel Aviv University Institutional animal care and use committee and performed in compliance with their guidelines