Jacob Hull Kristensen

Novel insights into the function and dynamics of extracellular matrix in liver fibrosis

Emerging evidence suggests that altered components and posttranslational modifications of proteins in the extracellular matrix (ECM) may both initiate and drive disease progression. The ECM is a complex grid consisting of multiple proteins, most of which play a vital role in containing the essential information needed for maintenance of a sophisticated structure anchoring the cells and sustaining normal function of tissues. Therefore, the matrix itself may be considered as a paracrine/endocrine entity, with more complex functions than previously appreciated. The aims of this review are to 1) explore key structural and functional components of the ECM as exemplified by monogenetic disorders leading to severe pathologies, 2) discuss selected pathological posttranslational modifications of ECM proteins resulting in altered functional (signaling) properties from the original structural proteins, and 3) discuss how these findings support the novel concept that an increasing number of components of the ECM harbor signaling functions that can modulate fibrotic liver disease. The ECM entails functions in addition to anchoring cells and modulating their migratory behavior. Key ECM components and their posttranslational modifications often harbor multiple domains with different signaling potential, in particular when modified during inflammation or wound healing. This signaling by the ECM should be considered a paracrine/endocrine function, as it affects cell phenotype, function, fate, and finally tissue homeostasis. These properties should be exploited to establish novel biochemical markers and antifibrotic treatment strategies for liver fibrosis as well as other fibrotic diseases.

Accelerated extracellular matrix turnover during exacerbations of COPD

BackgroundExacerbations of chronic obstructive pulmonary disease (COPD) contribute significantly to disease progression. However, the effect on tissue structure and turnover is not well described. There is an urgent clinical need for biomarkers of disease activity associated with disease progression. Extracellular matrix (ECM) turnover reflects activity in tissues and consequently assessment of ECM turnover may serve as biomarkers of disease activity. We hypothesized that the turnover of lung ECM proteins were altered during exacerbations of COPD.Methods69 patients with COPD hospitalised for an exacerbation were recruited at admission and returned for a 4 weeks follow-up. Competitive ELISAs measuring circulating protein fragments in serum or plasma assessed the formation and degradation of collagen types III (Pro-C3 and C3M, respectively), IV (P4NP 7S and C4M, respectively), and VI (Pro-C6 and C6M, respectively), and degradation of elastin (ELM7 and EL-NE) and versican (VCANM).ResultsCirculating levels of C3M, C4M, C6M, ELM7, and EL-NE were elevated during an exacerbation of COPD as compared to follow-up (all P <0.0001), while VCANM levels were decreased (P <0.0001). Pro-C6 levels were decreased and P4NP 7S levels were elevated during exacerbation (P <0.0001). Pro-C3 levels were unchanged. At time of exacerbation, degradation/formation ratios were increased for collagen types III and VI and decreased for collagen type IV.ConclusionsExacerbations of COPD resulted in elevated levels of circulating fragments of structural proteins, which may serve as markers of disease activity. This suggests that patients with COPD have accelerated ECM turnover during exacerbations which may be related to disease progression.

Systemic Biomarkers of Collagen and Elastin Turnover Are Associated With Clinically Relevant Outcomes in COPD

Background Extracellular matrix (ECM) remodeling of the lung tissue releases protein fragments into the blood, where they may be detected as serologic surrogate markers of disease activity in COPD. Our goal was to assess the association of ECM turnover with severity and outcome of COPD. Methods In a prospective, observational, multicenter study including 506 patients with COPD (Global Initiative for Chronic Obstructive Lung Disease grades II to IV), serum samples were analyzed at stable state, exacerbation, and 4 weeks after exacerbation. The analysis comprised a panel of five novel neoepitopes, including fragments of collagen type III (C3M) and collagen type VI (C6M), pro‐forms of collagen type III (Pro‐C3) and type VI (Pro‐C6), and neutrophil elastase‐generated fragments of elastin (EL‐NE) according to enzyme‐linked immunosorbent assay. These neoepitopes were also measured at stable state in a derivation cohort that included 100 patients with COPD. Results Serum levels of C3M, C6M, Pro‐C3, Pro‐C6, and EL‐NE were associated with lung function. Patients with the lowest levels of Pro‐C3 and Pro‐C6 had more severe airflow limitation, hyperinflation, air trapping, and emphysema. C3M and C6M were associated with dyspnea. All ECM biomarkers, except Pro‐C6, were increased at exacerbation compared with stable state but, except EL‐NE, did not differ between stable state and exacerbation follow‐up in the crude and adjusted analyses. In Cox regression adjusted analyses, Pro‐C3 was associated with a shorter time to exacerbation (hazard ratio, 0.72; CI, 0.59‐0.89; P = .002) and Pro‐C6 with survival (hazard ratio, 2.09; CI, 1.18‐3.71; P = .011). Conclusions Serum biomarkers of ECM turnover were significantly associated with disease severity and clinically relevant outcomes in patients with COPD. Trial Registry No.: ISRCTN99586989; URL: www.controlled‐trials.com.

Levels of circulating MMP-7 degraded elastin are elevated in pulmonary disorders.

OBJECTIVES Elastin is a signature protein of the lungs. Matrix metalloproteinase-7 (MMP-7) is important in lung defence mechanisms and degrades elastin. However, MMP-7 activity in regard to elastin degradation has never been quantified serologically in patients with lung diseases. An assay for the quantification of MMP-7 generated elastin fragments (ELM7) was therefore developed to investigate MMP-7 derived elastin degradation in pulmonary disorders such as idiopathic pulmonary fibrosis (IPF) and lung cancer. DESIGN AND METHODS Monoclonal antibodies (mABs) were raised against eight carefully selected MMP-7 cleavage sites on elastin. After characterisation and validation of the mABs, one mAB targeting the ELM7 fragment was chosen. ELM7 fragment levels were assessed in serum samples from patients diagnosed with IPF (n=123, baseline samples, CTgov reg. NCT00786201), and lung cancer (n=40) and compared with age- and sex-matched controls. RESULTS The ELM7 assay was specific towards in vitro MMP-7 degraded elastin and the ELM7 neoepitope but not towards other MMP-7 derived elastin fragments. Serum ELM7 levels were significantly increased in IPF (113%, p<0.0001) and lung cancer (96%, p<0.0001) compared to matched controls. CONCLUSIONS MMP-7-generated elastin fragments can be quantified in serum and may reflect pathological lung tissue turnover in several important lung diseases.

Clinical Drug Development Using Dynamic Biomarkers to Enable Personalized Health Care in COPD.

Despite massive investments in the development of novel treatments for heterogeneous diseases such as COPD, the resources spent have only benefited a fraction of the population treated. Personalized health care to guide selection of a suitable patient population already in the clinical development of new compounds could offer a solution. This review discusses past successes and failures in drug development and biomarker research in COPD, describes research in COPD phenotypes and the required characteristics of a suitable biomarker for identifying patients at higher risk of progression, and examines the role of extracellular matrix proteins found to be upregulated in COPD. Novel biomarkers of connective tissue remodeling that may provide added value for a personalized approach by detecting subgroups of patients with active disease suitable for pharmacologic intervention are discussed.

The Role of Extracellular Matrix Quality in Pulmonary Fibrosis

This review discusses the role of extracellular matrix (ECM) quality in the pathogenesis of pulmonary fibrosis (PF). In PF, the highly ordered structure of collagens and elastin within the ECM of the lung is severely disrupted and lacks its original tissue quality. Discussions about the ECM have focused on the role of protein quantity in relation to the progression of PF, while the importance of lung ECM quality, defined by the levels of ECM protein modifications and by the protein distribution in lung tissue, has not been properly addressed. The quality and function of proteins may be altered by different post-translational modifications (PTMs), such as cross-linking, proteolytic cleavage, citrullination, misfolding and glycosylation. This paper is the first to review key data from the literature related to the lung ECM at the molecular level, relate these to changes observed at a macroscopic level and evaluate which PTMs most likely contribute to PF. This paper also reviews the role of novel neo-epitope-specific biomarkers in the early diagnosis and prognosis of fibrotic disorders. We discuss and argue that the altered quality of the individual ECM proteins contributes to the progression of PF and may also lead to the increased quantity of lung proteins. Thus, both quantity and quality appear to be of utmost importance.

Contents Vol. 88, 2014

I.M. Adcock, London K.E. Bloch, Zürich A. Boehler, Zürich D.E. Bouros, Alexandroupolis A. Chetta, Parma V. Cottin, Lyon C. Dooms, Leuven E. Eber, Graz S. Gasparini, Ancona J. Hammer, Basel J. Johnston, Vancouver, B.C. C.F. Koegelenberg, Cape Town M. Lommatzsch, Rostock M. Miravitlles, Barcelona J. Müller-Quernheim, Freiburg L.P. Nicod, Lausanne D. Olivieri, Parma W. Randerath, Solingen P.L. Shah, London S. Siddiqui, Leicester T. Terashima, Ichikawa O.S. Usmani, London S. van Eeden, Vancouver, B.C. K. Yasufuku, Toronto, Ont.