Evaluation of collagen turnover biomarkers as an objective measure for efficacy of treatment with rurioctocog alfa pegol in patients with hemophilia A: a secondary analysis of a randomized controlled trial

BACKGROUND

Patients with hemophilia who have recurrent hemarthroses develop hemophilic arthropathy (HA). Regular prophylaxis with factor (F) VIII (FVIII) can reduce HA, but there is a need for objective outcome measures to evaluate treatment efficacy.

OBJECTIVES

Evaluate and assess collagen turnover biomarkers in patients with hemophilia A to determine the efficacy of rurioctocog alfa pegol treatment and understand their potential as tools for guiding treatment decisions and monitoring outcomes.

METHODS

Joint remodeling was assessed by analyzing serum levels of collagen remodeling products at baseline and months 3, 6, 9, and 12 in a 98 patient subset receiving pharmacokinetics-guided prophylaxis with rurioctocog alfa pegol, targeting FVIII trough levels of 1 to 3 International Units (IU)/dL or 8 to 12 IU/dL (PROPEL study, NCT0285960).

RESULTS

Basement membrane metabolism-related type 4 collagen remodeling products (C4M and PRO-C4) decreased after 3 months at all time points by up to 25% at 1 to 3 IU/dL (P = .049, P < .0001) and 8 to 12 IU/dL FVIII trough levels (P = .0002, P < .0001). Interstitial tissue metabolism-related type 3 (C3M) and 5 (PRO-C5) collagen remodeling products decreased after 3 months, by up to 19% at 1 to 3 IU/dL FVIII trough level (P = .0001, P = .009) and 23% at 8 to 12 IU/dL FVIII trough level (P = .0002, P = .001). An increase of up to 12% was seen for cartilage metabolism-related type 2 collagen product (PRO-C2, not C2M) after 6 months at both trough levels (P = .01, P = .005). When stratified by prior treatment, changes in C3M (P = .03) and C4M (P = .02) levels were observed between trough levels for prior on-demand treatment but not for prophylaxis prior to study entry.

CONCLUSION

Joint improvement measured by collagen remodeling biomarkers specific to the basement membrane, interstitial matrix, and cartilage was seen with pharmacokinetics-guided prophylaxis. These collagen remodeling biomarkers warrant further exploration as biomarkers to guide treatment toward improvement in HA.

A serologically assessed neo-epitope biomarker of cellular fibronectin degradation is related to pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is characterized by excessive extracellular matrix (ECM) remodeling, herein ECM degradation. Fibronectin (FN) is an important component of the ECM that is produced by multiple cell types, including fibroblasts. Extra domain B (EDB) is specific for a cellular FN isoform which is found in the ECM. We sought to develop a non-invasive test to investigate whether matrix metalloproteinase 8 (MMP-8) degradation of EDB in cellular FN results in a specific protein fragment that can be assessed serologically and if levels relate to pulmonary fibrosis.

METHOD

Cellular FN was cleaved in vitro by MMP-8 and a protein fragment was identified by mass spectrometry. A monoclonal antibody (mAb) was generated, targeting a neo-epitope originating from EDB in cellular FN. Utilizing this mAb, a neo-epitope specific enzyme-linked immunosorbent assay (FN-EDB) was developed and technically validated. Serum FN-EDB was assessed in an IPF cohort (n=98), registered at clinicaltrials.gov (NCT02818712), and in healthy controls (n=35).

RESULTS

The FN-EDB assay had high specificity for the MMP-8 degraded neo-epitope and was technically robust. FN-EDB serum levels were not influenced by age, sex, ethnicity, or BMI. Moreover, FN-EDB serum levels were significantly higher in IPF patients (median 31.38 [IQR 25.79-46.84] ng/mL) as compared to healthy controls (median 28.05 [IQR 21.58-33.88] ng/mL, p=0.023).

CONCLUSION

We developed the neo-epitope specific FN-EDB assay, a competitive ELISA, as a tool for serological assessment of MMP-8 mediated degradation of EDB in cellular FN. This study indicates that degradation of EDB in cellular FN is elevated in IPF and warrants further investigation.

Inflammatory Biomarkers of Extracellular Matrix Remodeling and Disease Activity in Crohn’s Disease and Ulcerative Colitis

Extracellular matrix (ECM) homeostasis is highly affected in active inflammatory bowel disease (IBD). The aim of the study was to investigate serological biomarkers of type III, IV, and V collagen degradation and formation, and their association with disease activity in IBD. ECM remodeling serum biomarkers were measured in 162 IBD patients, 110 with Crohn’s disease (CD) and 52 with ulcerative colitis (UC), and in 29 healthy donors. Biomarkers of type III collagen degradation (C3M) and formation (PRO-C3), type IV collagen degradation (C4M) and formation (PRO-C4), and type V collagen formation (PRO-C5) were measured using ELISA. Inflammatory activity was assessed using endoscopic, clinical, and biochemical activity indices. The highest diagnostic value was identified in discriminating endoscopically moderate to severe disease in CD (PRO-C3, C3M/PRO-C3, and C4M with AUC of 0.70, 0.73, and 0.69, respectively) and UC (C3M, C3M/PRO-C3, and C4M with AUC of 0.86, 0.80, and 0.76, respectively). C4M and C3M/PRO-C3 in combination yielded AUC of 0.93 (0.66–0.90) in CD and 0.94 (0.65–0.99) in UC. This study confirmed that ECM remodeling reflected disease activity in CD and UC. A combination of C4M, C3M, and PRO-C3 biomarkers may potentially be considered as a biomarker differentiating moderate to severe endoscopic disease.

Plasma Kallikrein-Activated TGF-β Is Prognostic for Poor Overall Survival in Patients with Pancreatic Ductal Adenocarcinoma and Associates with Increased Fibrogenesis

Pancreatic ductal adenocarcinoma (PDAC) is a hard-to-treat cancer due to the collagen-rich (fibrotic) and immune-suppressed microenvironment. A major driver of this phenomenon is transforming growth factor beta (TGF-β). TGF-β is produced in an inactive complex with a latency-associated protein (LAP) that can be cleaved by plasma kallikrein (PLK), hereby releasing active TGF-β. The aim of this study was to evaluate LAP cleaved by PLK as a non-invasive biomarker for PDAC and tumor fibrosis. An ELISA was developed for the quantification of PLK-cleaved LAP-TGF-β in the serum of 34 patients with PDAC (stage 1−4) and 20 healthy individuals. Biomarker levels were correlated with overall survival (OS) and compared to serum type III collagen (PRO-C3) and type VI collagen (PRO-C6) pro-peptides. PLK-cleaved LAP-TGF-β was higher in patients with PDAC compared to healthy individuals (p < 0.0001). High levels (>median) of PLK-cleaved LAP-TGF-β were associated with poor OS in patients with PDAC independent of age and stage (HR 2.57, 95% CI: 1.22−5.44, p = 0.0135). High levels of PLK-cleaved LAP-TGF-β were associated with high PRO-C3 and PRO-C6, indicating a relationship between the PLK-cleaved LAP-TGF-β fragment, TGF-β activity, and tumor fibrosis. If these preliminary results are validated, circulating PLK-cleaved LAP-TGF-β may be a biomarker for future clinical trials.

A Serological Biomarker of Laminin Gamma 1 Chain Degradation Reflects Altered Basement Membrane Remodeling in Crohn's Disease and DSS Colitis

BACKGROUND

The laminin gamma 1 chain (LMγ1) is abundant along the crypt-villus axis in the intestinal basement membrane.

AIMS

We investigated whether a serological biomarker of laminin degradation was associated with disease activity in patients with Crohn's disease (CD) and in rats with dextran sulfate sodium (DSS)-induced colitis.

METHODS

Serum samples from CD patients (n = 43), healthy subjects (n = 19), and Sprague Dawley rats receiving 5-6% DSS water for five days and regular drinking water for 11 days were included in this study. The LG1M biomarker, a neo-epitope degradation fragment of the LMγ1 chain generated by matrix metalloproteinases-9 (MMP-9), was measured in serum to estimate the level of laminin degradation.

RESULTS

Serum LG1M was elevated in CD patients with active and inactive disease compared to healthy subjects (p < 0.0001). LG1M distinguished CD patients from healthy subjects, with an area under the curve (AUC) of 0.81 (p < 0.0001). Serum LG1M was decreased in DSS rats compared to controls 2 days after DSS withdrawal, and increased upon reversal of the disease.

CONCLUSIONS

Increased serum LG1M in active and inactive CD patients supports the evidence of altered LM expression in both inflamed and non-inflamed tissue. Moreover, lower LG1M levels in the early healing phase of DSS-induced colitis may reflect ongoing mucosal repair.

Abstract 523: Type XX collagen is elevated in circulation of patients with solid tumors and high levels are associated with higher overall mortality in pancreatic cancer

Introduction: The tumor microenvironment has proven to be intricately involved in many aspects of cancer and is a promising place to look for non-invasive biomarkers. The extracellular matrix (ECM) has also been recognized as an important driver for cancer development. The most dominant ECM proteins are the collagens, which are important for tumor stiffness, tumor immunity and cancer metastasis. However, most of the cancer research of collagens has focused on the abundant and already well-described collagens, such as type I, III or IV collagens, whereas many of the more poorly described collagens remain unexplored. Type XX collagen is one such collagen. In this study, we developed an enzyme-linked immunosorbent assay (ELISA) quantifying type XX collagen, named PRO-C20, using a monoclonal antibody raised against its natural C-terminus and quantified circulating type XX collagen in patients with cancer.

Methods: Optimizations to the PRO-C20 protocol included finding the time and temperature of incubation as well as the assay buffer and concentration of assay components that gave the best sensitivity in serum. PRO-C20 was measured in serum of 219 patients with a range of solid cancer types and compared to serum levels in 33 healthy controls. The patients with cancer included 20 patients each of pancreatic-, colorectal-, kidney-, stomach-, breast-, bladder-, lung-, melanoma-, head and neck- and prostate-cancer as well as 19 with ovarian cancer. PRO-C20 was also subsequently measured in a separate cohort comprising 36 patients with pancreatic ductal adenocarcinoma (PDAC) and compared to 20 healthy controls. The biomarker performance of PRO-C20 was evaluated by ANOVA, ROC-curve analysis and cox proportional hazards models.

Results: The PRO-C20 ELISA was optimized and validated to be specific, precise and robust. PRO-C20 was significantly elevated in all cancers tested (p&lt;0.01 - p&lt;0.0001). PRO-C20 could discriminate between cancer and healthy controls with area under the receiver operating characteristic values ranging from 0.76 to 0.92. Elevated levels of PRO-C20 were confirmed in a separate cohort of patients with PDAC when compared to healthy controls (p&lt;0.0001). In addition, high PRO-C20 levels were associated with higher overall mortality (HR: 4.25, 95%CI: 1.52-11.9, p-value: 0.006) after adjusting for age, sex and the presence of metastasis.

Conclusion: An ELISA optimized to measure circulating type XX collagen in serum (PRO-C20) was successfully developed. Type XX collagen was elevated in serum of patients with cancer and high levels were associated with higher overall mortality in PDAC suggesting PRO-C20 has diagnostic and prognostic biomarker potential.

Citation Format: Jeppe Thorlacius-Ussing, Christina Jensen, Emilie A. Madsen, Neel I. Nissen, Astrid Z. Johansen, Inna M. Chen, Tina Manon-Jensen, Julia S. Johansen, Hadi M. Diab, Lars N. Jørgensen, Morten Karsdal, Nicholas Willumsen. Type XX collagen is elevated in circulation of patients with solid tumors and high levels are associated with higher overall mortality in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 523.

Abstract 3840: Novel aspects of tumor fibrosis: Non-invasively assessed type XXII collagen, and not type I collagen, depicts highy elevated levels in patients with various solid tumor types

Background: The major constituents of the tumor microenvironment (TME), are besides the tumor cells themselves, cancer associated fibroblasts (CAFs), stromal cells and the extracellular matrix (ECM). CAFs synthesize excess amounts of collagens leading to a fibrotic TME with poor response to anti-cancer treatment. Traditionally, tumor fibrosis is defined by quantification of fibrillar collagens such as type I collagen (COL1). So-called Fibril-Associated Collagen with Interrupted Triple helices (FACITs) are less studied in this context. Type XXII collagen (COL22) is a minor FACIT located at the basement membrane. COL22 may therefore provide a different value compared to standard COL1 assessment traditionally associated with tumor fibrosis.

Methods: Levels of COL1 (PRO-C1) and COL22 (PRO-C22) was measured non-invasively using competitive enzyme-linked immunosorbent assays in serum from patients diagnosed with bladder-, breast-, colorectal-, head and neck-, kidney-, lung-, melanoma-, pancreatic-, prostate-, and stomach cancer (n=220) and compared to healthy controls (n=33) (Cohort 1). Based on results from Cohort 1, PRO-C22 was evaluated in an independent cohort (Cohort 2) comprising patients with pancreatic ductal adenocarcinoma (PDAC) (n=39) and healthy controls (n=20). Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic performance of PRO-C22. Kaplan-Meier curves and Cox proportional hazard models were used to assess the association between PRO-C22 and overall survival (OS) after dichotomizing PRO-C22 at the median cutpoint.

Results: In Cohort 1, PRO-C22 was significantly higher in patients with all individual cancer types compared to healthy controls (p&lt;0.01 to p&lt;0.0001). In support, the area under the ROC (AUROC) for separation of patients with cancer from healthy controls using PRO-C22 ranged from 0.89 to 0.98 (p&lt;0.0001). As comparison PRO-C1 assesment showed no significant difference. PRO-C22 was also significantly higher in patients with PDAC (Cohort 2) when compared to healthy (p&lt;0.0001) with an AUROC of 0.87 (p&lt;0.0001). Furthermore, high PRO-C22 levels were associated with shorter OS (median OS days 162 and 1363 for ‘high’ and ‘low’ PRO-C22 subgroups, respectively, p=0.0011). Likewise, high PRO-C22 levels at baseline predicted increased risk of mortality (HR=3.53, 95% CI 1.59-7.86, p=0.0020).

Conclusion: These proof-of-concept data indicate that PRO-C22 may exhibit potential as a novel diagnostic and prognostic tumor fibrosis biomarker in cancer. PRO-C22 may be superior to type PRO-C1. Larger comprehensive clinical cohorts are needed to fully understand the biology associated with COL22 in cancer as well as the biomarker potential of PRO-C22 in various cancer types.

Citation Format: Emilie Albrecht Madsen, Jeppe Thorlacius-Ussing, Christina Jensen, Neel I. Nissen, Astrid Z. Johansen, Inna M. Chen, Julia S. Johansen, Tina Manon-Jensen, Hadi M. Diab, Lars N. Jørgensen, Morten Karsdal, Nicholas Willumsen. Novel aspects of tumor fibrosis: Non-invasively assessed type XXII collagen, and not type I collagen, depicts highy elevated levels in patients with various solid tumor types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3840.

Type XX Collagen Is Elevated in Circulation of Patients with Solid Tumors

In the tumor microenvironment, the extracellular matrix (ECM) has been recognized as an important part of cancer development. The dominant ECM proteins are the 28 types of collagens, each with a unique function in tissue architecture. Type XX collagen, however, is poorly characterized, and little is known about its involvement in cancer. We developed an ELISA quantifying type XX collagen, named PRO-C20, using a monoclonal antibody raised against the C-terminus. PRO-C20 and PRO-C1, an ELISA targeting the N-terminal pro-peptide of type I collagen, was measured in sera of 219 patients with various solid cancer types and compared to sera levels of 33 healthy controls. PRO-C20 was subsequently measured in a separate cohort comprising 36 patients with pancreatic ductal adenocarcinoma (PDAC) and compared to 20 healthy controls and 11 patients with chronic pancreatitis. PRO-C20 was significantly elevated in all cancers tested: bladder, breast, colorectal, head and neck, kidney, lung, melanoma, ovarian, pancreatic, prostate, and stomach cancer (p < 0.01−p < 0.0001). PRO-C1 was only elevated in patients with ovarian cancer. PRO-C20 could discriminate between patients and healthy controls with AUROC values ranging from 0.76 to 0.92. Elevated levels were confirmed in a separate cohort of patients with PDAC (p < 0.0001). High PRO-C20 levels (above 2.57 nM) were predictive of poor survival after adjusting for the presence of metastasis, age, and sex (HR: 4.25, 95% CI: 1.52−11.9, p-value: 0.006). Circulating type XX collagen is elevated in sera of patients with various types of cancer and has prognostic value in PDAC. If validated, PRO-C20 may be a novel biomarker for patients with solid tumors and can help understand the ECM biology of cancer.

A Specific Calprotectin Neo-epitope [CPa9-HNE] in Serum from Inflammatory Bowel Disease Patients Is Associated with Neutrophil Activity and Endoscopic Severity

BACKGROUND AND AIMS

Endoscopy and the use of faecal calprotectin [faecal CP] are among the least-favoured methods for assessing disease activity by inflammatory bowel disease [IBD] patients; the handling/processing of faecal samples is also impractical. Therefore, we sought to develop a novel neo-epitope serum calprotectin enzyme-linked immunosorbent assay [ELISA], CPa9-HNE, with the aim of quantifying neutrophil activity and neutrophil extracellular trap [NET]-osis and proposing a non-invasive method for monitoring disease activity in IBD patients.

METHODS

In vitro cleavage was performed by mixing calprotectin [S100A9/S100A8] with human neutrophil elastase [HNE], and a novel HNE-derived calprotectin neo-epitope [CPa9-HNE] was identified by mass spectrometry for ELISA development. The CPa9-HNE ELISA was quantified in supernatants from ex vivo activated neutrophils and serum samples from patients with ulcerative colitis [UC, n = 43], Crohn's disease [CD, n = 93], and healthy subjects [HS, n = 23]. For comparison, faecal CP and MRP8/14 biomarkers were also measured.

RESULTS

CPa9-HNE was specific for activated neutrophils ex vivo. Serum CPa9-HNE levels were 4-fold higher in CD [p <0.0001] and UC [p <0.0001] patients than in HS. CPa9-HNE correlated well with the Simple Endoscopic Score [SES]-CD score [r = 0.61, p <0.0001], MES [r = 0.46, p = 0.0141], and the full Mayo score [r = 0.52, p = 0.0013]. CPa9-HNE was able to differentiate between CD and UC patients in endoscopic remission and moderate/severe disease activity (CD: area under the curve [AUC] = 0.82 [p = 0.0003], UC: AUC = 0.87 [p = 0.0004]). The performance of CPa9-HNE was equipotent or slightly better than that of faecal CP.

CONCLUSIONS

Serum CPa9-HNE levels were highly associated with CD and UC patients. CPa9-HNE correlated with the SES-CD score and the full Mayo score, indicating a strong association with disease activity.

The activation fragment of PAR2 is elevated in serum from patients with rheumatoid arthritis and reduced in response to anti-IL6R treatment

Osteoarthritis (OA) and rheumatoid arthritis (RA) are serious and painful diseases. Protease-activated receptor 2 (PAR2) is involved in the pathology of both OA and RA including roles in synovial hyperplasia, cartilage destruction, osteophyogenesis and pain. PAR2 is activated via cleavage of its N-terminus by serine proteases. In this study a competitive ELISA assay was developed targeting the 36-amino acid peptide that is cleaved and released after PAR2 activation (PRO-PAR2). Technical assay parameters including antibody specificity, intra- and inter-assay variation (CV%), linearity, accuracy, analyte stability and interference were evaluated. PRO-PAR2 release was confirmed after in vitro cleavage of PAR2 recombinant protein and treatment of human synovial explants with matriptase. Serum levels of 22 healthy individuals, 23 OA patients and 15 RA patients as well as a subset of RA patients treated with tocilizumab were evaluated. The PRO-PAR2 antibody was specific for the neo-epitope and intra-inter assay CV% were 6.4% and 5.8% respectively. In vitro cleavage and matriptase treated explants showed increased PRO-PAR2 levels compared to controls. In serum, PRO-PAR2 levels were increased in RA patients and decreased in RA patients treated with tocilizumab. In conclusion, PRO-PAR2 may be a potential biomarker for monitoring RA disease and pharmacodynamics of treatment.

Considerations for understanding protein measurements: Identification of formation, degradation and more pathological relevant epitopes

OBJECTIVES

There is a need for precision medicine and an unspoken promise of an optimal approach for identification of the right patients for value-based medicine based on big data. However, there may be a misconception that measurement of proteins is more valuable than measurement of fewer selected biomarkers. In population-based research, variation may be somewhat eliminated by quantity. However, this fascination of numbers may limit the attention to and understanding of the single. This review highlights that protein measurements (with collagens as examples) may mean different things depending on the targeted epitope - formation or degradation of tissues, and even signaling potential of proteins.

DESIGN AND METHODS

PubMed was searched for collagen, neo-epitope, biomarkers.

RESULTS

Ample examples of assays with specific epitopes, either pathological such as HbA1c, or domain specific such as pro-peptides, which total protein arrays would not have identified were evident.

CONCLUSIONS

We suggest that big data may be considered as the funnel of data points, in which most important parameters will be selected. If the technical precision is low or the biological accuracy is limited, and we include suboptimal quality of biomarkers, disguised as big data, we may not be able to fulfill the promise of helping patients searching for the optimal treatment. Alternatively, if the technical precision of the total protein quantification is high, but we miss the functional domains with the most considerable biological meaning, we miss the most important and valuable information of a given protein. This review highlights that measurements of the same protein in different ways may provide completely different meanings. We need to understand the pathological importance of each epitope quantified to maximize protein measurements.

Enzymatic cross-linking of collagens in organ fibrosis - resolution and assessment

Introduction: Enzymatic cross-linking of the collagens within the extracellular matrix (ECM) catalyzed by enzymes such as lysyl oxidase (LOX) and lysyl oxidase like-enzymes 1-4 (LOXL), transglutaminase 2 (TG2), and peroxidasin (PXDN) contribute to fibrosis progression through extensive collagen cross-linking. Studies in recent years have begun elucidating the important role of collagen cross-linking in perpetuating progression of organ fibrosis independently of inflammation through an increasingly stiff and noncompliant ECM. Therefore, collagen cross-linking and the cross-linking enzymes have become new targets in anti-fibrotic therapy as well as targets of novel biomarkers to properly assess resolution of the fibrotic ECM.Areas covered: The enzymatic actions of enzymes catalyzing collagen cross-linking and their relevance in organ fibrosis. Potential biomarkers specifically quantifying proteolytic fragments of collagen cross-linking is discussed based on Pubmed search done in November 2020 as well as the authors knowledge.Expert opinion: Current methods for the assessment of fibrosis involve the use of invasive and/or cumbersome and expensive methods such as tissue biopsies. Thus, an unmet need exists for the development and validation of minimally invasive biomarkers of proteolytic fragments of cross-linked collagens. These biomarkers may aid in the development and proper assessment of fibrosis resolution in coming years.

Endotrophin and C6Ma3, serological biomarkers of type VI collagen remodelling, reflect endoscopic and clinical disease activity in IBD

In inflammatory bowel disease (IBD), the chronic inflammation deeply affects the intestinal extracellular matrix. The aim of this study was to investigate if remodeling of the intestinal basement membrane type VI collagen was associated with pathophysiological changes in Crohn’s disease (CD) and ulcerative colitis (UC). Serum from IBD patients (CD: n = 65; UC: n = 107; irritable bowel syndrome: n = 18; healthy subjects: n = 20) was investigated in this study. The serological biomarkers C6Ma3 (a matrix metalloproteinase (MMP) generated fragment of the type VI collagen α3 chain) and PRO-C6, also called endotrophin (the C-terminus of the released C5 domain of the type VI collagen α3 chain) were measured by ELISAs. Serum C6Ma3 was increased in CD patients with moderate to severe and mild endoscopically active disease compared to endoscopic remission (p = 0.002, p = 0.0048), respectively, and could distinguish endoscopically active disease from remission with an AUC of 1.0 (sensitivity: 100%, specificity: 100%) (p < 0.0001), which was superior to CRP. C6Ma3 was increased in CD patients with moderate to severe clinical disease compared to mild and remission (p = 0.04; p = 0.009). Serum PRO-C6, endotrophin, was increased in CD patients in clinically remission compared to mild disease (p = 0.04) and moderate to severe disease (p = 0.065). In UC, fecal calprotectin was the only marker that alone could distinguish both clinical and endoscopic active and inactive disease. Type VI collagen degradation of the α3 chain mediated by MMPs was increased in CD patients with endoscopically active disease, measured by the serological biomarker C6Ma3, which was able to distinguish endoscopically active from inactive CD.

Noninvasive prognostic biomarker potential of quantifying the propeptides of Type XI collagen alpha-1 chain (PRO-C11) in patients with pancreatic ductal adenocarcinoma

Type XI collagen has been associated with tumor fibrosis and aggressiveness in patients with pancreatic ductal adenocarcinoma (PDAC). The propeptide on Type XI collagen is released into the circulation after proteolytic processing at either amino acid 253 or 511. This allows for a noninvasive biomarker approach to quantify Type XI collagen production. We developed two ELISA-based biomarkers, targeting the two enzymatic cleavage sites (PRO-C11-253 and PRO-C11-511). In a discovery cohort including serum from patients with PDAC (n = 39, Stages 1-4), chronic pancreatitis (CP, n = 12) and healthy controls (n = 20), PRO-C11-511, but not PRO-C11-253, was significantly upregulated in patients with PDAC and CP compared to healthy controls. Furthermore, PRO-C11-511 levels >75th percentile were associated with poor overall survival (OS) (HR, 95% CI: 3.40, 1.48-7.83). The PRO-C11-511 biomarker potential was validated in serum from 686 patients with PDAC. Again, high levels of PRO-C11-511 (>75th percentile) were associated with poor OS (HR, 95% CI: 1.68, 1.40-2.02). Furthermore, PRO-C11-511 remained significant after adjusting for clinical risk factors (HR, 95% CI: 1.50, 1.22-1.86). In conclusion, quantifying serum levels of Type XI collagen with PRO-C11-511 predicts poor OS in patients with PDAC. This supports that Type XI collagen is important for PDAC biology and that PRO-C11-511 has prognostic noninvasive biomarker potential for patients with PDAC.

Systemic vascular basement membrane markers linked to synovial vascular remodeling are biomarkers of hemarthrosis in patients with hemophilia

INTRODUCTION

Interstitial, cartilage, and bone collagens have been proposed as biomarkers of joint deterioration in hemophilic arthropathy. The role of basement membrane (type IV and VIII) collagens as biomarkers of endothelial turnover in relation to acute joint bleeding is not understood.

METHODS

Thirty-one adult patients with hemophilia were studied prospectively for 3 years with musculoskeletal ultrasound/power Doppler (MSKUS/PD) during pain-free intervals and painful events for joint bleed status, synovial vascular flow, and 10 plasma markers of collagen turnover. Joint health was determined using Hemophilia Joint Health Scores and Pettersson scores. In animal studies, bleeding was induced in factor VIII-/- mice by knee joint injury. Synovial vascular remodeling was assessed using MSKUS/PD and histology. Murine plasma samples were analyzed for type IV collagen turnover markers.

RESULTS

Ninety-one patient visits were compiled. Twenty-five were due to acute painful episodes, with 16 confirmed hemarthroses. Type IV collagen turnover markers (PRO-C4 and C4M), and a type VIII collagen synthesis marker (PRO-C8), were transiently elevated during acute hemarthrosis. Hemarthrosis was accompanied by increased synovial microvascular flow (MSKUS/PD), and levels of type IV collagen markers correlated with PD signals in the joint. In factor VIII-deficient mice, plasma levels of type IV collagen turnover markers correlated negatively with synovial αSMA staining, indicating that reduced type IV collagen turnover was associated with thicker vessels.

CONCLUSIONS

Our findings suggest that basement membrane turnover markers, closely linked to synovial vascular remodeling, may be systemic biomarkers of acute hemarthrosis. Vascular instability during neovascularization may be involved in the dynamics of hemarthrosis.

Collagen remodelling and plasma ascorbic acid levels in patients suspected of inherited bleeding disorders harbouring germline variants in collagen-related genes

Introduction

Variants in collagen‐related genes COL1A1, COL3A1, COL5A1 and COL5A2 are associated with Ehlers‐Danlos syndrome (EDS), a heterogeneous group of connective tissue disorders strongly associated with increased bleeding. Of patients with incompletely explained bleeding diathesis, a relatively high proportion were shown to harbour at least one heterozygous variant of unknown significance (VUS) in one of these genes, the vast majority without meeting the clinical criteria for EDS.

Aim

To investigate the functional consequences of the identified variants by assessing the formation and degradation of types I, III and V collagen, in addition to plasma levels of ascorbic acid (AA).

Methods

A total of 31 patients harbouring at least one heterozygous VUS in COL1A1, COL3A1, COL5A1 or COL5A2 and 20 healthy controls were assessed using monoclonal antibodies targeting neo‐epitopes specific for collagen formation and degradation. Plasma AA levels were measured in patients using high‐performance liquid chromatography.

Results

Serum levels of C5 M (degradation of type V collagen) were decreased in patients compared with healthy controls (p = .033). No significant differences were found in biomarkers for remodelling of types I and III collagen. A significant negative correlation between bleeding (ISTH‐BAT score) and plasma AA levels was shown (r = −.42; r² = .17; p = .020). Suboptimal or marginally deficient AA status was found in 8/31 patients (26%).

Conclusion

Functional investigations of collagen remodelling were not able to identify any clear associations between the identified variants and increased bleeding. The negative correlation between plasma AA levels and ISTH‐BAT score motivates further investigations.

Combining biomarkers of clot resolution and alveolar basement membrane destruction predicts mortality in the ECLIPSE COPD cohort

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by abnormal epithelial repair resulting in a hypercoagulable state with intra-alveolar accumulation of fibrin and alveolar basement membrane destruction. This study aimed to investigate if the combination of two serological biomarkers evaluating these pathological processes could improve the prediction of mortality risk compared to single biomarkers.

METHODS

Matrix metalloproteinase-mediated degradation of the type IV collagen α3 chain (C4Ma3), located in the alveolar basement membrane, and plasmin-mediated degradation of crosslinked fibrin (X-FIB), an end-product of fibrinogen, were assessed serologically in a subset of the ECLIPSE cohort (n = 982). Biomarker data were dichotomized into high versus low at the median. Cox regression and Kaplan-Meier curves were used to analyze the predictive value of having one or two high biomarkers for all-cause mortality over two years.

RESULTS

COPD participants with high levels of two biomarkers were at significantly higher risk of all-cause mortality with a hazard ratio of 7.66 (95% CI 1.75-33.48; p = 0.007) while participants with one high biomarker were not at significantly higher risk (HR 3.79 [95% CI 0.85-16.94]; p = 0.08).

CONCLUSIONS

A combination of serological biomarkers of alveolar basement membrane destruction and clot resolution was predictive of all-cause mortality in COPD. The combination of two different pathological aspects may strengthen prognostic accuracy and could be used in conjunction with clinical assessment to guide treatment decisions.

Comprehensive assessment of ECM turnover using serum biomarkers establishes PBC as a high-turnover autoimmune liver disease

Background & Aims

Primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) are phenotypically distinct autoimmune liver diseases that progress to cirrhosis and liver failure; however, their histological fibrosis distribution differs. We investigated the extracellular matrix (ECM) profiles of patients with PSC, PBC, and AIH to establish whether the diseases display differential patterns of ECM turnover.

Methods

Serum samples were retrospectively collected from the UK (test cohort; PSC n = 78; PBC n = 74; AIH n = 58) and Norway (validation cohort; PSC n = 138; PBC n = 28; AIH n = 27). Patients with ulcerative colitis without liver disease (n = 194) served as controls. We assessed specific serological biomarkers of ECM turnover: type III and V collagen formation (PRO-C3, PRO-C5), degradation of type III and IV collagen (C3M, C4M), biglycan (BGM) and citrullinated vimentin (VICM).

Results

Most of the ECM markers showed elevated serum levels in PBC compared with PSC or AIH (p <0.01). PRO-C3 correlated well with liver stiffness and showed the most striking differences between advanced and non-advanced liver disease; several of the other ECM markers were also associated with stage. PRO-C3 and other ECM markers were inversely associated with ursodeoxycholic acid treatment response in PBC and remission in AIH. All ECM remodelling markers were significantly elevated (p <0.05) in patients with PSC, PBC, or AIH compared with ulcerative colitis.

Conclusions

In this first study comparing ECM turnover in autoimmune liver diseases, we found increased ECM turnover in PBC compared with either PSC or AIH. The study indicates that ECM remodelling is different in PSC, PBC, and AIH, suggesting differing opportunities for therapeutic intervention.

Lay summary

The level of scarring is linked to prognosis in autoimmune liver diseases such as primary sclerosing cholangitis, primary biliary cholangitis, and autoimmune hepatitis; hence, the scarring process is a possible target for novel therapy. Investigating the scarring process using highly specific technology, we show that the scarring process is different between the 3 autoimmune liver diseases, and this may have important implications for the development of medical treatment.

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Serological biomarkers specifically targeting extracellular matrix remodelling enable evaluation of the dynamics of fibrosis evolution.

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ECM turnover was increased in PBC compared with PSC and AIH.

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ECM markers, particularly PRO-C3, were associated with disease stage in the autoimmune liver diseases and with clinical outcome in PSC.

Endotrophin, an extracellular hormone, in combination with neoepitope markers of von Willebrand factor improves prediction of mortality in the ECLIPSE COPD cohort

BACKGROUND

Lung epithelial damage, activation of the wound healing cascade, and remodeling of the extracellular matrix (ECM) play a major role in chronic obstructive pulmonary disease (COPD). The pro-peptide of type VI collagen has been identified as the hormone endotrophin. Endotrophin has been shown to promote fibrosis and inflammation, whereas von Willebrand factor (VWF) is a crucial part of wound healing initiation. Here, we assessed the released and activated form of VWF and endotrophin, the pro-peptide of type VI collagen, serologically to investigate their association with mortality in COPD subjects alone or in combination.

METHODS

One thousand COPD patients with 3 years of clinical follow-up from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) cohort were included. Serum and heparin plasma were collected at 6 months and 1 year, respectively. Competitive ELISA utilizing specific monoclonal antibodies assessed endotrophin/type VI collagen formation (PRO-C6), VWF release (VWF-N), and activated VWF (VWF-A). Biomarker levels were dichotomized into high and low as defined by receiver operating characteristic (ROC) curves based on mortality data. Kaplan-Meier analysis was used to determine hazard ratios for all-cause mortality for biomarkers alone or in combination.

RESULTS

High levels of PRO-C6, VWF-A, and VWF-N have previously been shown to be individually associated with a higher risk of mortality with hazard ratios of 5.6 (95% CI 2.4-13.1), 3.7 (1.8-7.6), and 4.6 (2.2-9.6), respectively. The hazard ratios increased when combining the biomarkers: PRO-C6*VWFA 8.8 (2.8-27.7) and PRO-C6*VWFN 13.3 (5.6-32.0). Notably, PRO-C6*VWF-N increased more than 2-fold.

CONCLUSION

We demonstrated that by combining two pathological relevant aspects of COPD, tissue remodeling, and wound healing, the predictive value of biomarkers for mortality increased notably.

Increased von Willebrand Factor Processing in COPD, Reflecting Lung Epithelium Damage, Is Associated with Emphysema, Exacerbations and Elevated Mortality Risk

Background

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and lung tissue deterioration. Given the high vascularity of the lung, von Willebrand factor (VWF), a central component of wound healing initiation, has previously been assessed in COPD. VWF processing, which is crucial for regulating the primary response of wound healing, has not been assessed directly. Therefore, this study aimed to characterize wound healing initiation in COPD using dynamic VWF-processing biomarkers and to evaluate how these relate to disease severity and mortality.

Methods

A cross-sectional analysis of plasma samples from the ECLIPSE study collected at year 1 from moderate to very severe COPD subjects (GOLD 2-4, n=984) was performed. We applied competitive neo-epitope ELISAs specifically targeting the formation of and ADAMTS13-processed form of VWF, VWF-N and VWF-A, respectively.

Results

VWF-A and VWF-N were significantly increased (VWF-N, p=0.01; VWF-A, p=0.0001) in plasma of symptomatic (mMRC score ≥2) compared to asymptomatic/mild symptomatic COPD subjects. Increased VWF-N and VWF-A levels were specifically associated with emphysema (VWF-N, p<0.0001) or prior exacerbations (VWF-A, p=0.01). When dichotomized, high levels of both biomarkers were associated with increased risk of all-cause mortality (VWF-N, HR 3.5; VWF-A, HR 2.64).

Conclusion

We demonstrate that changes in VWF processing were related to different pathophysiological aspects of COPD. VWF-N relates to the chronic condition of emphysema, while VWF-A was associated with the more acute events of exacerbations. This study indicates that VWF-A and VWF-N may be relevant markers for characterization of disease phenotype and are associated with mortality in COPD.

Study Identifier

NCT00292552; GSK study code SCO104960.

Mechanisms of vascular permeability and remodeling associated with hemarthrosis in factor VIII-deficient mice

BACKGROUND

Vascular remodeling associated with hemophilic arthropathy (HA) may contribute to bleed propagation, but the mechanisms remain poorly understood.

OBJECTIVES

To explore molecular mechanisms of HA and the effects of hemostasis correction on synovial vascular remodeling after joint injury in hypocoagulable mice.

METHODS

Factor VIII (FVIII)-deficient mice +/- FVIII treatment and hypocoagulable wild-type mice (Hypo BALB/c) were subjected to subpatellar puncture. Hypo BALB/c mice were treated with warfarin and anti-FVIII before injury, after which warfarin was continued for 2 weeks or reversed +/- continuous anti-FVIII until harvest. Synovial vascularity was analyzed at baseline and 2 to 4 weeks post injury by histology, musculoskeletal ultrasound with power Doppler (microvascular flow), and Evans blue extravasation (vascular permeability). Synovial gene expression and systemic markers of vascular collagen turnover were studied in FVIII-deficient mice by RNA sequencing and enzyme-linked immunosorbent assay.

RESULTS

Vascular changes occurred in FVIII-deficient and Hypo BALB/c mice after injury with minimal effect of hemostasis correction. Increased vascular permeability was only significant in FVIII-deficient mice, who exhibited more pronounced vascular remodeling than Hypo BALB/c mice despite similar bleed volumes. FVIII-deficient mice exhibited a strong transcriptional response in synovium that was only partially affected by FVIII treatment and involved genes relating to angiogenesis and extracellular matrix remodeling, with vascular collagen turnover markers detected systemically.

CONCLUSIONS

Intact hemostasis at the time of hemarthrosis and during healing are both critical to prevent vascular remodeling, which appears worse with severe and prolonged FVIII deficiency. Unbiased RNA sequencing revealed potential targets for intervention and biomarker development to improve management of HA.

The intestinal tissue homeostasis - the role of extracellular matrix remodeling in inflammatory bowel disease

Introduction: Extracellular matrix (ECM) remodeling of the intestinal tissue is important in inflammatory bowel disease (IBD) due to the extensive mucosal remodeling. There are still gaps in our knowledge as to how ECM remodeling is related to intestinal epithelium homeostasis and healing of the intestinal mucosa.Areas covered: The aim of this review is to highlight the importance of the ECM in relation to the pathogenesis of IBD, while addressing basement membrane and interstitial matrix remodeling, and the processes of wound healing of the intestinal tissue in IBD.Expert opinion: In IBD, basement membrane remodeling may reflect the integrity of the intestinal epithelial-cell homeostasis. The interstitial matrix remodeling is associated with deep inflammation such as the transmural inflammation as seen in fistulas and intestinal fibrosis leading to fibrostenotic strictures, in patients with CD. The interplay between wound healing processes and ECM remodeling also affects the tissue homeostasis in IBD. The interstitial matrix, produced by fibroblasts, holds a very different biology as compared to the epithelial basement membrane in IBD. In combination with integration of wound healing, quantifying the interplay between damage and repair to these sub compartments may provide essential information in IBD patient profiling, mucosal healing and disease management.

Serological Assessment of the Quality of Wound Healing Processes in Crohn's Disease

BACKGROUND AND AIMS

Crohn's disease (CD) is a chronic inflammatory condition characterized by continuous mucosal damage and ongoing wound healing of the intestines. The fibrinolytic system is involved in early parts of the wound healing process. Fibrin is a key mediator of primary blood clot formation and is formed by cross-linking of fibrinogen. To gain insights into the dynamics of wound healing in CD patients we investigated the conversion of fibrinogen into fibrin by the pro-peptide FPA, the amount of factor XIII cross-linked fibrin and total fibrin clot.

METHODS

Serum samples of 35 CD patients, 15 non-inflammatory bowel disease (non-IBD) patients and 39 age-matched healthy controls were analyzed for three novel neo-epitope markers: D-fragment and D-dimer, reflecting the degradation of total fibrin clot and factor XIII cross-linked fibrin, as well as FPA, reflecting synthesis of fibrin.

RESULTS

Crohn's disease patients had a significantly lower D-dimer level (p=0.0001) compared to healthy controls. Crohn's disease and non-IBD patients had a significantly higher level of FPA (p<0.0001) and D-fragment/D-dimer ratio (p<0.0001 and p=0.02). FPA, D-dimer and D-fragment/D-dimer ratio could distinguish CD patients from healthy controls with area under the curve of 0.92 (95% CI 0.83-0.97), 0.78 (95% CI 0.67-0.87) and 0.85 (95% CI 0.75-0.93), respectively.

CONCLUSION

Wound healing parameters were clearly changed in CD patients. FPA levels were higher in CD patients as compared to healthy controls, indicating more ongoing wound healing. D-dimer levels were lower in CD patients than in healthy controls, indicating impaired wound healing due to poor quality of factor XIII cross-linked fibrin and clot resolution.

Potential diagnostic value of a type X collagen neo-epitope biomarker for knee osteoarthritis

OBJECTIVE

Phenotypic changes of chondrocytes toward hypertrophy might be fundamental in the pathogenesis of osteoarthritis (OA), of which type X collagen (Col10) is a well-known marker. The purpose was to develop a specific immunoassay for blood quantification of a newly identified neo-epitope of type Col10 to assess its diagnostic value for radiographic knee OA.

METHODS

A neo-epitope of Col10 was identified in urine samples from OA patients. A monoclonal antibody against the neo-epitope was produced in Balb/C mice. The enzyme responsible for the cleavage was identified. Immunohistochemical detection of this neo-epitope was performed on human OA cartilage. An immunoassay (Col10neo) was developed and quantified in two clinical studies: the C4Pain-003 and the NYU OA progression study. Receiver operating characteristic curve (ROC) curve analysis was carried out to evaluate the discriminative power of Col10neo between OA and rheumatoid arthritis (RA).

RESULTS

A neo-epitope specific mAb was produced. The Cathepsin K-generated neo-epitope was localized to the pericellular matrix of chondrocytes, while its presence was extended and more prominent in superficial fibrillation in the cartilage with advanced degradation. In the C4Pain study, a higher level of Col10neo was seen in subjects with greater KL grade. The group of the highest tertile of Col10neo included more subjects with KL3-4. In the NYU study, Col10neo was statistically higher in OA than control or RA. ROC curve analysis revealed area under the curve was 0.88 (95% CI 0.81-0.94).

CONCLUSION

Our findings indicate that Col10neo linked to hypertrophic chondrocytes could be used as a diagnostic biochemical marker for knee OA.

Type IV collagen turnover is predictive of mortality in COPD: a comparison to fibrinogen in a prospective analysis of the ECLIPSE cohort

BACKGROUND

Identifying subjects with chronic obstructive pulmonary disease (COPD) at high risk of exacerbation and mortality is key to aid individual management of COPD. The only FDA approved blood-based drug development biomarker for patients at high risk of mortality, is plasma fibrinogen. In this study, we benchmarked two biomarkers of basement membrane remodeling, a characteristic of COPD, against plasma fibrinogen alone and as a combination. The biomarkers of basement membrane remodeling are two neoepitopes from of the alpha 3 chain of type IV collagen (COL4A3).

MATERIALS AND METHODS

COL4A3 degradation was assessed by the biomarkers C4Ma3 and tumstatin (TUM) in year 1 plasma samples in 984 COPD subjects, 95 non-smoking controls and 95 smoking controls from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE) cohort. They were measured by competitive ELISA using monoclonal antibodies recognizing two specific MMP-generated cleavage site within COL4A3. The level of fibrinogen was previously assessed in year 1 plasma.

RESULTS

In COPD subjects, plasma C4Ma3 levels were significantly correlated with plasma fibrinogen levels (0.389 (P < 0.0001)). Cox proportional-hazards regression adjusted for relevant confounders showed that high levels of plasma C4Ma3, but not TUM, were related to a higher risk of mortality (hazard ratio 5.12 (95% CI 2.28-11.50), P < 0.0001). High levels of plasma fibrinogen were not associated with all-cause mortality in this subpopulation, contradictory to published results. Whereas plasma C4Ma3 multiplied by fibrinogen showed to be related to a higher risk of mortality (hazard ratio 5.74 (95% CI 2.65-12.41), P < 0.0001). Plasma C4Ma3 levels were related to the number of hospitalizations due to COPD exacerbations in the year before study start (P = 0.0375). Fibrinogen levels were related to hospitalized exacerbations prior to study start (P = 0.0058) and were also related to future exacerbations (P < 0.0001).

CONCLUSION

We compared herein fibrinogen, C4Ma3 and TUM as biomarkers for COPD prognosis. Fibrinogen was related to future exacerbation, whereas C4Ma3 and the combination of C4Ma3 with fibrinogen were superior to fibrinogen alone in predicting mortality. This pilot study suggests that the assessment of plasma C4Ma3 could be important for identifying COPD patients with a poor prognosis.

TRIAL REGISTRATION

NCT00292552 , GSK Study No. SCO104960.

Specific elastin degradation products are associated with poor outcome in the ECLIPSE COPD cohort

Chronic obstructive pulmonary disease (COPD) is characterized by a slow heterogeneous progression. Therefore, improved biomarkers that can accurately identify patients with the highest likelihood of progression and therefore the ability to benefit from a given treatment, are needed. Elastin is an essential structural protein of the lungs. In this study, we investigated whether elastin degradation products generated by the enzymes proteinase 3, cathepsin G, neutrophil elastase, MMP7 or MMP9/12 were prognostic biomarkers for COPD-related outcomes. The elastin degradome was assessed in a subpopulation (n = 1307) of the Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE) cohort with 3 years of clinical follow-up. Elastin degraded by proteinase 3 could distinguish between COPD participants and non-smoking controls (p = 0.0006). A total of 30 participants (3%) died over the 3 years of observation. After adjusting for confounders, plasma levels of elastin degraded by proteinase 3 and cathepsin G were independently associated with mortality outcome with a hazard ratio per 1 SD of 1.49 (95%CI 1.24-1.80, p < 0.0001) and 1.31 (95%CI 1.10-1.57, p = 0.0029), respectively. Assessing the elastin degradome demonstrated that specific elastin degradation fragments have potential utility as biomarkers identifying subtypes of COPD patients at risk of poor prognosis and supports further exploration in confirmatory studies.

GPDPLQ1237-A Type II Collagen Neo-Epitope Biomarker of Osteoclast- and Inflammation-Derived Cartilage Degradation in vitro

C-telopeptide of type II collagen (CTX-II) has been shown to be a highly relevant biomarker of cartilage degradation in human rheumatic diseases, if measured in synovial fluid or urine. However, serum or plasma CTX-II have not been demonstrated to have any clinical utility to date. Here, we describe the GPDPLQ₁₂₃₇ ELISA which targets the EKGPDPLQ↓ neo-epitope, an elongated version of the CTX-II neo-epitope (EKGPDP↓), speculated to be a blood-precursor of CTX-II generated by the cysteine protease cathepsin K. Human osteoclast cartilage resorption cultures as well as oncostatin M and tumour necrosis factor α-stimulated bovine cartilage explant cultures were used to validate GPDPLQ₁₂₃₇ biologically by treating the cultures with the cysteine protease inhibitor E-64 and/or the matrix metalloproteinase (MMP) inhibitor GM6001 to assess the potential contributions of these two protease classes to GPDPLQ₁₂₃₇ release. Cartilage resorption-derived GPDPLQ₁₂₃₇ release was inhibited by E-64 (72.1% inhibition), GM6001 (75.5%), and E-64/GM6001 (91.5%), whereas CTX-II release was inhibited by GM6001 (87.0%) but not by E-64 (5.5%). Cartilage explant GPDPLQ₁₂₃₇ and CTX-II release were both fully inhibited by GM6001 but were not inhibited by E-64. No clinically relevant GPDPLQ₁₂₃₇ reactivity was identified in human serum, plasma, or urine from healthy donors or arthritis patients. In conclusion, the GPDPLQ₁₂₃₇ biomarker is released during osteoclast-derived cysteine protease- and MMP-mediated cartilage degradation in vitro, whereas CTX-II release is mediated by MMPs and not by cysteine proteases, as well as from MMP-mediated cartilage degradation under a pro-inflammatory stimulus. These findings suggest that GPDPLQ₁₂₃₇ may be relevant in diseases with pathological osteoclast activity and cartilage degradation. Further studies are required to validate the neo-epitope in human samples.

A fragment of SPARC reflecting increased collagen affinity shows pathological relevance in lung cancer - implications of a new collagen chaperone function of SPARC

The matricellular protein SPARC (secreted proteome acidic and rich in cysteine) is known to bind collagens and regulate fibrillogenesis. Cleavage of SPARC at a single peptide bond, increases the affinity for collagens up to 20-fold. To investigate if this specific cleavage has pathological relevance in fibrotic disorders, we developed a competitive ELISA targeting the generated neo-epitope on the released fragment and quantified it in serum from patients with lung cancer, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and healthy subjects. Furthermore, the ability of SPARC to protect fibrillar collagens from proteolytic degradation was investigated in vitro, potentially adding a new collagen chaperone function to SPARC. The fragment was significantly elevated in lung cancer patients when compared to healthy subjects measured in a discovery cohort (p = 0.0005) and a validation cohort (p < 0.0001). No significant difference was observed for IPF and COPD patients compared to healthy subjects. When recombinant SPARC was incubated with type I or type III collagen and matrix metalloproteinase-9, collagen degradation was completely inhibited. Together, these data suggest that cleavage of SPARC at a specific site, which modulates collagen binding, is a physiological mechanism increased during pathogenesis of lung cancer. Furthermore, inhibition of fibrillar collagen degradation by SPARC adds a new chaperone function to SPARC which may play additional roles in the contribution to increased collagen deposition leading to a pro-fibrotic and tumorigenic environment.

Lung tissue destruction by proteinase 3 and cathepsin G mediated elastin degradation is elevated in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by high levels of protease activity leading to degradation of elastin followed by loss of elasticity of the lung and the development of emphysema. Elastin is an essential structural component of the lung parenchyma to support the expansion and recoil of the alveoli during breathing. The lung extracellular matrix is vulnerable to pathological structural changes upon upregulation of serine proteases, including cathepsin G (CG) and proteinase 3 (PR3). In this study, we explored the diagnostic features of elastin neo-epitopes generated by CG and PR3. Two novel competitive enzyme-linked immunosorbent assays (ELISA) measuring CG and PR3 generated elastin fragments (EL-CG and ELP-3 respectively) were developed for assessment in serum. Both assays were technically robust and biologically validated in serum from patients with COPD. Serological levels of both elastin fragments were significantly elevated in patients with COPD compared to healthy controls. These data suggest that EL-CG and ELP-3 may serve as plausible biologic markers of destructive changes in COPD.

The endothelial specific isoform of type XVIII collagen correlates to annual bleeding rate in haemophilia patients

Introduction

The medical need in the haemophilic (HF) field to reduce bleeding incidents requires measurement of the annual bleeding rate (ABR) in haemophiliacs. Vascular rupture is associated with damage to the vascular endothelium causing exposure of the basement membrane. Endothelial cells and matrix impairment may be associated with joint bleeds and later development of HF arthropathy. Imbalanced extracellular matrix turnover is a central pathological feature in many diseases consequent to epithelial or endothelial cell damage. Type XVIII collagen is an essential basement membrane component, with an endothelial specific isoform.

Aim

To quantify the basement membrane specifically for the endothelial cells, as that may have particular relevance to endothelial cell stability and rupture in haemophiliacs. A newly developed ELISA assay detecting endothelial type XVIII collagen (COL-18N) was used to assess the clinical relevance of endothelial basement membrane turnover in patients diagnosed with HF arthropathy and correlation to ABR.

Methods

We developed an ELISA assay for quantification of COL-18N. Serum from 35 male HF patients was investigated using the COL-18N ELISA.

Results

COL-18N correlated to the ABR of haemophiliacs, r = 0.45, P<0.006.

Conclusion

Vascular rupture and consequent bleeding are associated with joint damage and deterioration of life quality in haemophiliacs. Quantification of ABR is an important part in efficacy assessment of different interventions, and the benchmark of these. Objective biomarkers reflecting endothelial dysfunction, vascular leaks and rupture, like the COL-18N biomarker that associate with ABR, may assist in identifying the most optimal treatment and monitoring of HF patients.

The good and the bad collagens of fibrosis - Their role in signaling and organ function

Usually the dense extracellular structure in fibrotic tissues is described as extracellular matrix (ECM) or simply as collagen. However, fibrosis is not just fibrosis, which is already exemplified by the variant morphological characteristics of fibrosis due to viral versus cholestatic, autoimmune or toxic liver injury, with reticular, chicken wire and bridging fibrosis. Importantly, the overall composition of the ECM, especially the relative amounts of the many types of collagens, which represent the most abundant ECM molecules and which centrally modulate cellular functions and physiological processes, changes dramatically during fibrosis progression. We hypothesize that there are good and bad collagens in fibrosis and that a change of location alone may change the function from good to bad. Whereas basement membrane collagen type IV anchors epithelial and other cells in a polarized manner, the interstitial fibroblast collagens type I and III do not provide directional information. In addition, feedback loops from biologically active degradation products of some collagens are examples of the importance of having the right collagen at the right place and at the right time controlling cell function, proliferation, matrix production and fate. Examples are the interstitial collagen type VI and basement membrane collagen type XVIII. Their carboxyterminal propeptides serve as an adipose tissue hormone, endotrophin, and as a regulator of angiogenesis, endostatin, respectively. We provide an overview of the 28 known collagen types and propose that the molecular composition of the ECM in fibrosis needs careful attention to assess its impact on organ function and its potential to progress or reverse. Consequently, to adequately assess fibrosis and to design optimal antifibrotic therapies, we need to dissect the molecular entity of fibrosis for the molecular composition and spatial distribution of collagens and the associated ECM.

Ulcerative colitis, Crohn's disease, and irritable bowel syndrome have different profiles of extracellular matrix turnover, which also reflects disease activity in Crohn's disease

Background

Increased protease activity is a key pathological feature of inflammatory bowel disease (IBD). However, the differences in extracellular matrix remodelling (ECM) in Crohn’s disease (CD) and ulcerative colitis (UC) are not well described. An increased understanding of the inflammatory processes may provide optimized disease monitoring and diagnostics. We investigated the tissue remodelling in IBD and IBS patients by using novel blood-based biomarkers reflecting ECM remodelling.

Methods

Five ECM biomarkers (VICM, BGM, EL-NE, C5M, Pro-C5) were measured by competitive ELISAs in serum from 72 CD patients, 60 UC patients, 22 patients with irritable bowel syndrome (IBS), and 24 healthy donors. One-way analysis of variance, Mann-Whitney U-test, logistic regression models, and receiver operator characteristics (ROC) curve analysis was carried out to evaluate the diagnostic accuracy of the biomarkers.

Results

The ECM remodelling was significantly different in UC compared to CD. The best biomarker combination to differentiate UC from CD and colonic CD was BGM and VICM (AUC = 0.98, P<0.001; AUC = 0.97, P<0.001), and the best biomarker combination to differentiate IBD from IBS patients were BGM, EL-NE, and Pro-C5 (AUC = 0.8, P<0.001). When correcting for the use of immunosuppressant and elevated CRP levels (CRP>5mg/mL), correlation of Pro-C5 (r = 0.36) with CDAI was slightly improved compared to CRP (r = 0.27) corrected for the use of immunosuppressant. Furthermore, BGM and EL-NE biomarkers were highly associated with colon inflammation in CD patients.

Conclusion

ECM fragments of tissue remodelling in IBD affect UC and CD differently, and may aid in differentiating IBD from IBS (EL-NE, BGM, Pro-C5), and UC from CD patients (BGM, VICM). Formation of type V collagen is related to the level of inflammation in CD and may reflect disease activity in CD.

Serological biomarkers detect active joint destruction and inflammation in patients with haemophilic arthropathy

INTRODUCTION

Progressive arthropathy caused by recurrent joint bleeds is a severe complication in haemophilia.

AIM

We investigated whether biomarkers of cartilage and bone degradation, and inflammation were altered in haemophilia patients and whether these biomarkers could identify haemophilia patients with arthropathy.

METHODS

Serum from 35 haemophilia patients with varying degrees of arthropathy and 43 age- and gender-matched control subjects were analysed. Biomarkers of cartilage degradation (C2M, COMP, CTX-II, ADAMTS5), cartilage formation (PRO-C2), bone formation (PINP), bone resorption (CTX-I) and inflammation (hsCRP, CRPM) were measured by ELISA. Arthropathy was assessed by radiological evaluation (Pettersson score) and physical examination (Gilbert score).

RESULTS

In patients with haemophilia, cartilage degradation, measured by C2M, CTX-II and COMP, was increased by 25% (P < 0.05) compared with control subjects. Levels of the cartilage degradation enzyme, ADAMTS5, were 10% lower in haemophilia patients (P < 0.05). Bone formation (PINP) was reduced by 25% (P < 0.05) in haemophilia patients, whereas bone resorption (CTX-I) was increased by 30% (P < 0.001). Acute inflammation (hsCRP) was increased by 50% (P < 0.01), whereas chronic inflammation (CRPM) was decreased by 25% (P < 0.0001). The hsCRP/CRPM ratio was 60% higher (P < 0.001) in haemophilia patients relative to control subjects. A biomarker panel combining C2M, CRPM, and ADAMTS5 could distinguish haemophilia patients from control subjects with 85.3% accuracy (P < 0.0001). We found no strong correlation between biomarkers and radiological and physical examination of the joint.

CONCLUSION

Biomarkers detect increased cartilage and bone degradation, and altered inflammatory activity in haemophilia patients with arthropathy. These biomarkers could potentially be used to identify patients with progressing joint disease.

Altered collagen turnover in factor VIII-deficient rats with hemophilic arthropathy identifies potential novel serological biomarkers in hemophilia

Essentials Joint bleeding in hemophilia may induce significant remodeling of the extracellular matrix. Biomarkers of collagen turnover were investigated in a F8-/- rat model of hemophilic arthropathy. Biomarkers of cartilage degradation increased significantly during development of arthropathy. Basement membrane and interstitial matrix turnover changed significantly following hemarthrosis.

SUMMARY

Background Hemophilic arthropathy is a severe complication of hemophilia. It is caused by recurrent bleeding into joint cavities, which leads to synovial inflammation, fibrosis, cartilage degradation and bone remodeling. Extracellular matrix remodeling of affected tissues is a hallmark of these pathological processes. Objectives The aim of this study was to use serological biomarkers of collagen turnover to evaluate extracellular matrix remodeling in a factor VIII-deficient rat model of hemophilic arthropathy. Methods F8-/- rats and wild-type littermate controls were subjected to repeated knee bleeds induced by needle puncture on days 0 and 14. Development of arthropathy was confirmed by histology after termination on day 28. Serum samples were collected at baseline and throughout the study and analyzed for biomarkers of collagen turnover, including collagens of the basement membrane (type IV collagen), the interstitial matrix (collagen types III, V and VI) and cartilage (type II collagen). Results In F8-/- rats, induced knee bleeding and subsequent development of arthropathy caused significant alterations in collagen turnover, measured as changes in serological biomarkers of basement membrane turnover, interstitial matrix turnover and cartilage degradation. Biomarkers of type II collagen degradation correlated significantly with cartilage degradation and degree of arthropathy. Hemophilic rats had a 50% higher turnover of the basement membrane than wild-type littermates at baseline. Conclusions Joint bleeding and hemophilic arthropathy cause changes in turnover of extracellular matrix collagens in hemophilic rats. Biomarkers of collagen turnover may be used to monitor joint bleeding and development of blood-induced joint disease in hemophilia.

Intercritical circulating levels of neo-epitopes reflecting matrixmetalloprotease-driven degradation as markers of gout and frequent gout attacks

OBJECTIVE

Recurrent flares constitute the main clinical burden of gout. Our aim was to assess whether biomarkers measuring MMP tissue degradation could be used as markers of frequent gout flares.

METHODS

Fasting plasma samples from 112 men with gout and 170 controls, along with serum samples from 447 men with gout collected at baseline from an ongoing clinical trial, were analysed by ELISA for neo-epitopes from MMP degradation of collagens type I (C1M) and type III (C3M). The log10 levels of both markers were compared between cases and controls and between gout patients with three or more gout attacks in the past year and those with two or less attacks.

RESULTS

The circulating levels of C1M and C3M correlated with gout status in the case-control study. Levels of both markers were associated with frequent gout flares (⩾3 attacks in the past year) in both cohorts (odds ratio, OR = 3.1; 95% CI: 1.4, 6.8; P = 0.0056 for log10C1M, and OR = 6.7; 95% CI: 2.3, 19.3; P = 0.0005 for log10C3M). The area under the curve in a receiver operating characteristic analysis of frequent flares increased from 0.68 to 0.74 in one cohort and from 0.60 to 0.66 in the other when log10C1M and log10C3M were added to clinical variables of the model.

CONCLUSION

C1M and C3M, reflective of interstitial matrix destruction, are associated with gout status and with frequent gout flares in men, suggesting that increased MMP activity may contribute to gout flares. Further research is needed to find out whether this is independent of dietary and lifestyle risk factors for acute gout.

Collagen-mediated hemostasis

Collagens mediate essential hemostasis by maintaining the integrity and stability of the vascular wall. Imbalanced turnover of collagens by uncontrolled formation and/or degradation may result in pathologic conditions such as fibrosis. Thickening of the vessel wall because of accumulation of collagens may lead to arterial occlusion or thrombosis. Thinning of the wall because of collagen degradation or deficiency may lead to rupture of the vessel wall or aneurysm. Preventing excessive hemorrhage or thrombosis relies on collagen-mediated actions. Von Willebrand factor, integrins and glycoprotein VI, as well as clotting factors, can bind collagen to restore normal hemostasis after trauma. This review outlines the essential roles of collagens in mediating hemostasis, with a focus on collagens types I, III, IV, VI, XV, and XVIII.

Collagen and tissue turnover as a function of age: Implications for fibrosis

BACKGROUND & AIMS

The extracellular matrix (ECM) is the backbone of all tissues. It is a complex grid consisting of multiple structural proteins which each play a vital role for the function and maintenance of normal tissue function. In development and growth, tissue is being formed and elaborated (tissue modeling), while in adult life, tissues are being maintained and remodeled. These processes involve likely different mechanisms. During tissue modeling and remodeling, small fragments of proteins are released into the circulation, where they may be used as biomarkers for tissue turnover. The aim of the study was to investigate ECM turnover in rodents as a function of age.

METHODS

Serum of rats of 1, 2, 3, 4, 5, 6, 10 and 12months of age was profiled for 15 markers of ECM turnover, including: fragments of type I, II, III, IV, V and VI collagen formation (P1NP, P4NP-7S, Pro-C5, Pro-C6) and degradation (C1M, C2M, C2M-beta, C3M, C4M, C5M, C6M); biglycan (BGM) and elastin (ELM7) degradation; and the type I and II collagen telopeptides CTX-I and CTX-II.

RESULTS

Type I and II collagen turnover was up to 93% and 97% downregulated in old (one year) compared to young (one month) old animals (p<0.0001), while type IV and V collagen and biglycan turnover was upregulated 2.5-, 2- and 2-fold, respectively (p<0.0001). Type III and VI collagen and elastin turnover was not influenced significantly by age.

CONCLUSIONS

ECM turnover rates were consistently different in young vs. old animals, up to 30 fold. This appears to be due to body growth, a different ECM composition and a higher regenerative capability of connective tissues in young vs. old animals. These changes have to be accounted for in translational science. Both in measuring serum levels of ECM biomarkers and in the development of therapies to speed up wound healing or inhibit fibrogenesis.

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.

Mapping of matrix metalloproteinase cleavage sites on syndecan-1 and syndecan-4 ectodomains

Syndecans are transmembrane heparan sulfate proteoglycans with roles in cell proliferation, differentiation, adhesion, and migration. They have been associated with multiple functions in tumour progression, through their ability to interact with a wide range of ligands as well as other receptors, which makes them key effectors in the pericellular microenvironment. Extracellular shedding of syndecans by tumour-associated matrix metalloproteinases (MMPs) may have an important role in tumour progression. Such ectodomain shedding generates soluble ectodomains that may function as paracrine or autocrine effectors, or as competitive inhibitors of the intact proteoglycan. Tumour-associated MMPs are shown here to cleave the ectodomains of human syndecan-1 and syndecan-4. Two membrane proximal regions of both syndecan-1 and syndecan-4 are favoured MMP cleavage sites, six and 15 residues from the transmembrane domain. Other sites are 35-40 residues C-terminal from the heparan sulfate chain substitution sites in both syndecans. The MT1-MMP cleavage sites in syndecan-1 and syndecan-4 were confirmed by site-directed mutagenesis. These findings provide insights into the characteristics of syndecan shedding.

Biological interplay between proteoglycans and their innate immune receptors in inflammation

An emerging body of evidence indicates that secreted proteoglycans act as signaling molecules, in addition to their canonical function in maintaining and regulating the architecture of various extracellular matrices. Proteoglycans interact with a number of receptors that regulate growth, motility and immune response. In part, as a consequence of their complex structure, proteoglycans can induce crosstalk among various families of receptors and can also interact with natural receptor ligands, often blocking and sequestering their bioactivity. In their soluble form, originating from either partial proteolytic processing or through de novo synthesis by activated cells, some proteoglycans can become potent danger signals, denoting tissue stress and injury. Recently, it has been shown that proteoglycans, especially those belonging to the small leucine-rich and hyaluronan-binding gene families as well as the glycosaminoglycan hyaluronan, act as endogenous ligands of the toll-like receptors, a group of central receptors regulating innate immunity. Furthermore, proteoglycans can activate intracellular inflammasomes and trigger sterile inflammation. In this review, we critically assess the signaling events induced by the proteoglycans biglycan, decorin, lumican and versican as well as hyaluronan during inflammation. We discuss the intriguing emerging notion that, in spite of structural diversity of biglycan, decorin, versican and hyaluronan, all of them signal through the same toll-like receptors, albeit triggering differential responses and biological outcomes. Finally, we review the modes of action of these endogenous ligands of toll-like receptors and their ability to specifically modify the final signaling events and the inflammatory response.

Syndecan-1 and syndecan-4 are independent indicators in breast carcinoma

Syndecan proteoglycans may be key regulators of tumor invasion and metastasis because this four-member family of transmembrane receptors regulates cell adhesion, proliferation, and differentiation. Their expression can also serve as prognostic markers. In breast carcinomas, syndecan-1 overexpression correlates with poor prognosis and aggressive phenotype. Syndecan-4 is expressed in most breast carcinoma cell lines, but its role in malignancy is unclear. A possible relationship between syndecan-1 and syndecan-4 expression and established prognostic factors in breast carcinomas was examined. Duplicate samples of 114 benign and malignant breast disease cases were stained for the two syndecans. Clinicopathological information was available for all cases. Syndecan-1 was detected in 72.8% of cases, with significant association between its expression and histological tumor type (p<0.05) and high grade tumors (p<0.05). Syndecan-4 was expressed in 66.7% of cases; expression correlated significantly with positive estrogen (p<0.01) and progesterone (p<0.01) receptor status. Independent expression of the two syndecans was noted from an analysis of single and double positive cases. There was a statistical relationship between syndecan-1 presence in high-grade tumors and absence of syndecan-4, whereas syndecan-4 presence in cases positive for estrogen and progesterone receptor associated with syndecan-1 absence. These syndecans may, therefore, have distinct roles in regulating breast carcinoma cell behavior.

Syndecan proteoglycan contributions to cytoskeletal organization and contractility

Cells exert tension on the extracellular matrix through specific receptors that link to the actin cytoskeleton. The best characterized are the integrins, which, when activated and clustered, can link to the extracellular matrix at specialized adhesion zones, known as focal contacts or focal adhesions. However, other transmembrane receptors can also localize there, including one transmembrane proteoglycan, syndecan-4. This heparan sulfate proteoglycan can also link directly to the cytoskeleton through alpha-actinin, and can signal through protein kinase C. In turn, the pathway leads to RhoA and Rho kinases that control actomyosin contractility. Syndecan-4 may, therefore, be a sensor of tension exerted on the matrix. These processes are described here, their significance being potential roles in wound contraction, tumor-stroma interactions, fibrosis and the regulation of motility.