Articles
Longitudinal change in collagen degradation biomarkers in idiopathic pulmonary fibrosis: an analysis from the prospective, multicentre PROFILE study

https://doi.org/10.1016/S2213-2600(15)00048-XGet rights and content

Summary

Background

Idiopathic pulmonary fibrosis, a progressive and inevitably fatal disorder, has a highly variable clinical course. Biomarkers that reflect disease activity are urgently needed to inform patient management and for use as biomarkers of therapeutic response (theragnostic biomarkers) in clinical trials. We aimed to determine whether dynamic change in markers of extracellular matrix (ECM) turnover predicts progression of idiopathic pulmonary fibrosis as determined by change in forced vital capacity and death.

Methods

In this ongoing prospective, multicentre, observational cohort study (PROFILE), participants with idiopathic pulmonary fibrosis or idiopathic non-specific interstitial pneumonia diagnosed within the preceding 6 months were recruited from two coordinating centres (Nottingham, UK, and, Royal Brompton Hospital, London, UK). Serum samples were prospectively collected at baseline, 1 month, 3 months, and 6 months and were analysed for a panel of novel matrix metalloprotease (MMP)-degraded ECM proteins, by ELISA-based, neoepitope assay. 11 neoepitopes were tested in a discovery cohort of 55 patients to identify biomarkers of sufficient rigour for more detailed analyses. Eight were then further assessed in a validation cohort of 134 patients with 50 age-matched and sex-matched controls. Changes in biomarker concentrations were related to subsequent progression of idiopathic pulmonary fibrosis (defined as death or decline in forced vital capacity >10% at 12 months after study enrolment) using a repeated measures model. The PROFILE study is registered on ClinicalTrials.gov, numbers NCT01134822 and NCT01110694.

Findings

Of 214 eligible participants recruited between Sept 1, 2010, and March 31, 2012, 189 had a confirmed diagnosis of idiopathic pulmonary fibrosis and were included in subsequent analyses. In the discovery cohort, mean concentrations of seven neoepitopes (BGM, p=0·009; C1M, p=0·009; C3M, p=0·046; C6M, p=0·032; CRPM, p=0·008; ELM2, p=0·02; and VICM, p=0·0007) differed significantly between healthy controls and participants with idiopathic pulmonary fibrosis. Baseline concentrations of six neoepitopes (C1M, p=0·012; C3A, p=0·012; C3M, p=0·0005; C6M, p=0·0003; CRPM, p=0·021; and VICM, p=0·046) were significantly higher in patients with progressive idiopathic pulmonary fibrosis (n=32) than in those with stable disease (n=23). In the validation cohort, mean concentrations of C1M (p=0·001), C3M (p=0·044), C6M (p=0·003), and CRPM (p=0·024) at baseline were higher in patients with idiopathic pulmonary fibrosis than in healthy controls. When assessed longitudinally, concentrations of six neoepitopes (BGM, C1M, C3A, C3M, C6M, and CRPM) were significantly higher in patients with progressive idiopathic pulmonary fibrosis (n=71) than in patients with stable idiopathic pulmonary fibrosis (n=60) by 6 months. Baseline concentrations of two neoepitopes were associated with increased mortality (C1M: HR 1·62 [95% CI 1·14–2·31], p=0·0069; C3A: 1·91 [1·06–3·46], p=0·032). The rate of change between baseline and 3 months of six neoepitopes (BGM: HR 1·084 [95% CI 1·03–1·14], p=0·0019; C1M: 1·01 [1·003–1·017], p=0·0039; C3M: 1·106 [1·045–1·170], p=0·0005; C5M: 1·003 [1·001–1·005], p=0·0011; C6M: 1·042 [1·007–1·078], p=0·017; and CRPM: 1·38 [1·16–1·63], p=0·0002) was strongly predictive of overall survival, and the increased risk was proportional to the magnitude of change in neoepitope concentrations. The strongest association with 3-month rate of biomarker change was recorded for CRPM; greater than 0 ng/mL per month conferred a HR of 2·16 (95% CI 1·15–4·07), whereas a rate greater than 1 ng/mL per month resulted in an HR 4·08 (2·14–7·8), and a rate greater than 1·7 ng/mL per month was associated with an HR 6·61 (2·74–15·94).

Interpretation

Concentrations of protein fragments generated by MMP activity are increased in the serum of individuals with idiopathic pulmonary fibrosis compared with healthy controls. Increased neoepitope concentrations were associated with disease progression, and the rate of this increase predicted survival. Serial measurements of neoepitopes have potential to be used as theragnostic biomarkers in clinical trials and to guide management of idiopathic pulmonary fibrosis.

Funding

GlaxoSmithKline R&D and the Medical Research Council.

Introduction

Idiopathic pulmonary fibrosis is a progressive and inevitably fatal disease with a 5 year survival of only 20%.1 With the advent of specific antifibrotic drugs, there is now hope that disease-modification and improved survival could be realistic therapeutic goals.2, 3 Advances in management of idiopathic pulmonary fibrosis are, however, hampered by heterogeneity of disease progression, absence of validated prognostic measures, and the absence of any markers of treatment response.4 Novel serum biomarkers of fibroproliferation are emerging across a range of non-pulmonary fibrotic diseases, but none have been prospectively validated in carefully phenotyped individuals with idiopathic pulmonary fibrosis.

A cardinal feature of idiopathic pulmonary fibrosis is the accumulation of disordered and architecturally disruptive extracellular matrix (ECM) within the lung tissue. The ECM consists of a dynamic combination of structural proteins, the most abundant of which are collagens. Matrix turnover is determined by several factors including the rate of ECM synthesis by activated myofibroblasts, the extent of collagen cross-linking, and enzymatic matrix degradation.5 Biomarkers that indicate matrix turnover might therefore be indicative of disease activity in fibroproliferative disorders such as idiopathic pulmonary fibrosis.

Most extracellular collagen is degraded by a subset of matrix metalloproteinases (MMPs) including MMP-1, MMP-3, MMP-7, MMP-8, MMP-13, MMP-14, MMP-16, and MMP-18.6 Extracellular collagen fragments generated by these MMPs are then further digested by MMP-2 and MMP-9.6 In idiopathic pulmonary fibrosis, greatly increased rates of ECM protein synthesis are, at least partly, offset by elevated MMP concentrations and activity,7 and MMP-1, MMP-3, and MMP-7 have even been identified as putative prognostic serum biomarkers of the disease.8, 9

During ECM turnover, proteolytically cleaved matrix degradation fragments, or neoepitopes, are released into the systemic circulation.10 Cleavage of each ECM protein by specific MMPs generates a unique neoepitope. These neoepitopes are more accurate diagnostic and prognostic markers for individual fibroproliferative diseases than their protein of origin.10, 11 Previous small point-of-diagnosis studies have suggested that matrix neoepitopes might be elevated in individuals with idiopathic pulmonary fibrosis compared with healthy controls.12, 13, 14

The PROFILE (Prospective Observation of Fibrosis in the Lung Clinical Endpoints) study, the largest prospective study of its type undertaken so far, aimed to determine the prognostic value of longitudinal change in serum concentrations of proteolytically cleaved protein fragments, or neoepitopes. To our knowledge, this study enables, for the first time, sequential temporal assessment of biomarkers in relation to clinical measures of disease activity and progression. Furthermore, the recruitment of incident idiopathic pulmonary fibrosis cases from multiple centres enhances the potential applicability of any findings to real-world clinical practice.

Section snippets

Study design and participants

PROFILE is an ongoing prospective, multicentre, observational cohort study of incident cases (within 6 months of presentation) of idiopathic fibrotic lung disease. Participants with idiopathic pulmonary fibrosis or idiopathic non-specific interstitial pneumonia were identified through two co-ordinating centres: Nottingham, UK, and, Royal Brompton Hospital, London, UK. Only participants with a diagnosis of idiopathic pulmonary fibrosis made in accordance with current internationally accepted

Results

Of 214 eligible participants, recruited between Sept 1, 2010, and March 31, 2012, 189 had a confirmed diagnosis of idiopathic pulmonary fibrosis and were therefore eligible for inclusion in subsequent analyses (figure 1). Participants were predominantly men (79%) with a mean age of 70·1 years (SD 8·3) (table 1). Patients from the Royal Brompton Hospital were significantly younger than patients from Nottingham University Hospitals (p=0·0002), and had slightly, but significantly, worse lung

Discussion

To the best of our knowledge, the PROFILE study is the largest prospective cohort study of incident idiopathic fibrotic lung disease done so far. Patients with incident fibrotic lung disease of all severities were enrolled, through two coordinating centres; because pirfenidone was only approved for reimbursement by the UK National Health Service in August 2013, all participants included in the analysis were naive for antifibrotic therapy. The slightly younger, but more severely affected, cohort

References (33)

  • TJ Richards et al.

    Peripheral blood proteins predict mortality in idiopathic pulmonary fibrosis

    Am J Respir Crit Care Med

    (2012)
  • DJ DePianto et al.

    Heterogeneous gene expression signatures correspond to distinct lung pathologies and biomarkers of disease severity in idiopathic pulmonary fibrosis

    Thorax

    (2015)
  • MA Karsdal et al.

    Review article: the efficacy of biomarkers in chronic fibroproliferative diseases—early diagnosis and prognosis, with liver fibrosis as an exemplar

    Aliment Pharmacol Ther

    (2014)
  • H Skjot-Arkil et al.

    Investigation of two novel biochemical markers of inflammation, matrix metalloproteinase and cathepsin generated fragments of C-reactive protein, in patients with ankylosing spondylitis

    Clin Exp Rheumatol

    (2012)
  • DJ Leeming et al.

    Serological investigation of the collagen degradation profile of patients with chronic obstructive pulmonary disease or idiopathic pulmonary fibrosis

    Biomarker Insights

    (2012)
  • JM Sand et al.

    MMP mediated degradation of type IV collagen alpha 1 and alpha 3 chains reflects basement membrane remodeling in experimental and clinical fibrosis—validation of two novel biomarker assays

    PLoS One

    (2013)
  • Cited by (236)

    • Type I collagen

      2023, Biochemistry of Collagens, Laminins and Elastin: Structure, Function and Biomarkers, Third Edition
    • Type III collagen

      2023, Biochemistry of Collagens, Laminins and Elastin: Structure, Function and Biomarkers, Third Edition
    View all citing articles on Scopus
    View full text