Quantification of human serum procollagen C-proteinase enhancer (hsPCPE) glycopattern

Procollagen C-proteinase enhancer-1 (PCPE-1), a potential biomarker and therapeutic target for fibrosis

The correct balance between collagen synthesis and degradation is essential for almost every aspect of life, from development to healthy aging, reproduction and wound healing. When this balance is compromised by external or internal stress signals, it very often leads to disease as is the case in fibrotic conditions. Fibrosis occurs in the context of defective tissue repair and is characterized by the excessive, aberrant and debilitating deposition of fibril-forming collagens. Therefore, the numerous proteins involved in the biosynthesis of fibrillar collagens represent a potential and still underexploited source of therapeutic targets to prevent fibrosis. One such target is procollagen C-proteinase enhancer-1 (PCPE-1) which has the unique ability to accelerate procollagen maturation by BMP-1/tolloid-like proteinases (BTPs) and contributes to trigger collagen fibrillogenesis, without interfering with other BTP functions or the activities of other extracellular metalloproteinases. This role is achieved through a fine-tuned mechanism of action that is close to being elucidated and offers promising perspectives for drug design. Finally, the in vivo data accumulated in recent years also confirm that PCPE-1 overexpression is a general feature and early marker of fibrosis. In this review, we describe the results which presently support the driving role of PCPE-1 in fibrosis and discuss the questions that remain to be solved to validate its use as a biomarker or therapeutic target.

Procollagen C-Proteinase Enhancer 1 (PCPE-1) in Liver Fibrosis

Fibrosis is characterized by excessive deposition of collagen and additional extracellular matrix (ECM) components in response to chronic injuries. Liver fibrosis often results from chronic hepatitis C virus infection and alcohol abuse that can deteriorate to cirrhosis and liver failure. Current noninvasive diagnostic methods of liver fibrosis are limited in their ability to detect and differentiate between early and intermediate stages of fibrosis. New biomarkers of fibrosis that reflect ECM turnover are therefore badly needed. Procollagen C-proteinase enhancer 1 (PCPE-1), a connective tissue glycoprotein that functions as a positive regulator of C-terminal procollagen processing and subsequent collagen fibril assembly, is a promising candidate. Its tissue distribution and expression profile overlap those of collagen, and its expression in fibrosis is upregulated in parallel to the increase in collagen expression. The potential of PCPE-1 as a biomarker of liver fibrosis was recently established using a CCl₄ mouse model of liver fibrosis by showing that the increase in collagen and PCPE-1 content in the fibrotic mouse liver was reflected by elevated plasma levels of PCPE-1. This was achieved using a newly developed highly sensitive, specific, accurate, and reproducible ELISA for mouse PCPE-1, which is based on commercially available antibodies and is offered as a new research tool in the field. A similar ELISA test was developed for human PCPE-1, and preliminary results with plasma from liver fibrosis patients revealed increased plasma concentrations of PCPE-1 in some patients. The protocols of both ELISA tests are outlined herein in great detail to permit their application by any laboratory with similar interests.

Data comparing the plasma levels of procollagen C-proteinase enhancer 1 (PCPE-1) in healthy individuals and liver fibrosis patients

This article provides a protocol for determination of human procollagen C-proteinase enhancer 1 (PCPE-1) concentrations by ELISA. The inter-assay and intra-assay coefficients of variability are given and so are the average plasma concentrations of PCPE-1 in healthy (control) individuals and liver fibrosis patients.

Procollagen C-Proteinase Enhancer 1 (PCPE-1) as a Plasma Marker of Muscle and Liver Fibrosis in Mice

Current non-invasive diagnostic methods of fibrosis are limited in their ability to identify early and intermediate stages of fibrosis and assess the efficacy of therapy. New biomarkers of fibrosis are therefore constantly sought for, leading us to evaluate procollagen C-proteinase enhancer 1 (PCPE-1), a fibrosis-related extracellular matrix glycoprotein, as a plasma marker of fibrosis. A sandwich ELISA that permitted accurate measurements of PCPE-1 concentrations in mouse plasma was established. Tissue fibrosis was assessed using histochemical, immunofluorescence, and immunoblotting analyses 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 mdx 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.