Immunological detection of the type V collagen propeptide fragment, PVCP-1230, in connective tissue remodeling associated with liver fibrosis

Dysregulation of circulating collagen turnover markers in very early systemic sclerosis

OBJECTIVE

Clinical observation suggests that vascular activation and autoimmunity precede remodelling of the extracellular matrix (ECM) in systemic sclerosis (SSc). We challenge this paradigm by hypothesising that ECM biomarkers are already disturbed in patients with very early SSc (veSSc) when fibrosis is not yet clinically detectable.

METHODS

42 patients with veSSc, defined as the presence of Raynaud's phenomenon and at least one of puffy fingers, positive antinuclear antibodies or pathological nailfold capillaroscopy, not meeting the 2013 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for SSc, were compared with healthy controls (HCs, n=29). ECM degradation (BGM, C3M, C4M and C6M) and ECM formation biomarkers (PRO-C3, PRO-C4 and PRO-C5) were measured in serum using ELISAs. A cross-sectional analysis at baseline and a longitudinal analysis was performed.

RESULTS

Compared with HC, veSSc patients showed a strongly dysregulated turnover of type III and IV collagens (higher C3M, C4M, both p<0.0001 and PRO-C3, p=0.004, lower turnover ratios PRO-C3/C3M and PRO-C4/C4M, both p<0.0001). The biglycan degradation biomarker BGM was higher in veSSc than in HC (p=0.006), whereas the degradation biomarker for type VI collagen, C6M, was lower (p=0.002). In an ROC analysis, biomarkers of type III and IV collagen excellently distinguished between veSSc and HC: C3M, AUC=0.95, p<0.0001; C4M, AUC=0.97, p<0.0001; turnover ratios PRO-C3/C3M, AUC=0.80, p<0.0001; PRO-C4/C4M, AUC=0.97; p<0.0001.

CONCLUSION

These findings indicate ECM remodelling as a very early phenomenon of SSc occurring in parallel with microvascular and autoimmune changes. Biomarkers of type III and IV collagens distinguished between veSSc patients and HC, indicating them as potential biomarkers for the detection of veSSc.

Extracellular matrix remodeling proteins as biomarkers for clinical assessment and treatment outcomes in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic progressive inflammatory disease of the esophagus, characterized by extracellular matrix remodeling and fibrotic stricture formation. Disease monitoring requires multiple re-endoscopies with esophageal biopsies. Hence non-invasive methods for determining tissue fibrosis and treatment efficacy are warranted.

AIMS

To investigate the ability of extracellular matrix proteins in serum as potential biomarkers of tissue remodeling and clinical, endoscopic, and histological disease outcomes in adult EoE patients.

METHODS

Protein-fingerprint assays were used to measure neo-epitope specific fragments of collagen remodeling, human-neutrophil elastase degraded calprotectin, and citrullinated or non-citrullinated vimentin in the serum of an adult EoE-cohort. Biomarker analysis, symptoms, endoscopic features and histological disease activity (eosinophils(eos) per high-power-field(hpf)) were evaluated at baseline and after six weeks of dietary intervention.

RESULTS

Patients with a baseline (Endoscopic Reference score) EREFS fibrosis subscore ≥ 2 presented with increased fibrolysis of cross-linked type III collagen (CTX-III) (p < 0.01), whereas low CTX-III levels were observed in patients achieving histological remission (< 15 eos/hpf) (vs. no histological remission (p < 0.05). Progression of endoscopic fibrosis after intervention was associated with increased levels of type-III (PRO-C3) and -VI collagen (PRO-C6) formation (all; p < 0.05). A baseline EREFS inflammatory subscore ≥ 2 correlated with higher neutrophilic activity (Cpa9-HNE) at week 6 (p < 0.05). Moreover, increased degradation of type-III (C3M) and -IV (C4M/PRO-C4) collagens were associated with remission of food impaction after intervention (all; p < 0.05).

CONCLUSION

Serum extracellular matrix remodeling proteins demonstrated potential as surrogate biomarkers for assessing histological disease remission, endoscopic fibrosis, and remission of symptoms of food impaction after diet intervention in adult EoE patients.

Skin Extracellular Matrix Breakdown Following Paclitaxel Therapy in Patients with Chemotherapy-Induced Peripheral Neuropathy

The chemotherapeutic agent paclitaxel causes peripheral neuropathy, a dose-limiting side effect, in up to 68% of cancer patients. In this study, we investigated the impact of paclitaxel therapy on the skin of breast cancer patients with chemotherapy-induced peripheral neuropathy (CIPN), building upon previous findings in zebrafish and rodents. Comprehensive assessments, including neurological examinations and quality of life questionnaires, were conducted, followed by intraepidermal nerve fiber (IENF) density evaluations using skin punch biopsies. Additionally, RNA sequencing, immunostaining for Matrix-Metalloproteinase 13 (MMP-13), and transmission electron microscopy provided insights into molecular and ultrastructural changes in this skin. The results showed no significant difference in IENF density between the control and CIPN patients despite the presence of patient-reported CIPN symptoms. Nevertheless, the RNA sequencing and immunostaining on the skin revealed significantly upregulated MMP-13, which is known to play a key role in CIPN caused by paclitaxel therapy. Additionally, various genes involved in the regulation of the extracellular matrix, microtubules, cell cycle, and nervous system were significantly and differentially expressed. An ultrastructural examination of the skin showed changes in collagen and basement membrane structures. These findings highlight the presence of CIPN in the absence of IENF density changes and support the role of skin remodeling as a major contributor to CIPN.

High serum levels of the C-propetide of type V collagen (PRO-C5) are prognostic for short overall survival in patients with pancreatic ductal adenocarcinoma

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a pronounced fibrotic tumor microenvironment, which impairs treatment response. Type I and V collagens are responsible for the densely packed fibrils in the tumor fibrosis environment. While the role of the major type I collagen in cancer is well described, less is known about the minor type V collagen. Quantifying collagen propeptides in serum has been shown to have prognostic and predictive value. In this study, we evaluated the clinical utility of measuring the propeptide of type V collagen (PRO-C5) in serum from a discovery cohort and a validation cohort of patients with PDAC as well as in non-pancreatic solid tumor types to explore the relevance of the PRO-C5 biomarker in cancer.

Methods: Serum PRO-C5 was measured in three cohorts: a discovery cohort (19 healthy controls, 12 patients with chronic pancreatitis and 33 patients with PDAC (stage I-IV)), a validation cohort (800 patients with PDAC (stage I-IV)), and a non-pancreatic solid tumor type cohort of 33 healthy controls and 200 patients with 10 different non-pancreatic solid tumor types. The levels of serum PRO-C5 in patients with cancer were compared to levels in healthy controls. The association between PRO-C5 levels and overall survival (OS) was evaluated in patients with PDAC after adjusting for established prognostic factors.

Results: PRO-C5 was significantly increased in serum from patients with PDAC compared to healthy controls (p &lt; 0.001). High PRO-C5 levels were significantly associated with short OS in both the discovery- and the validation cohort, especially in early stages of PDAC (validation cohort stage II, HR = 2.0, 95%CI1.2-3.4). The association was independent of other prognostic parameters including stage, performance status and CA19-9. Furthermore, serum levels of PRO-C5 were significantly increased in serum from patients with other non-pancreatic solid tumor types compared to healthy controls.

Conclusion: High levels of serum PRO-C5 is prognostic for short OS in patients with PDAC and may provide clinical value in many other tumor types beyond PDAC. This underlines the importance of type V collagen in tumor fibrosis. PRO-C5 could have the potential to be used in several aspects within drug discovery, patient stratification and drug efficacy.

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.

Circulating collagen neo-epitopes and their role in the prediction of fibrosis in patients with systemic sclerosis: a multicentre cohort study

BACKGROUND

Extracellular matrix remodelling is a hallmark of systemic sclerosis. We evaluated extracellular matrix neo-epitopes as potential serum biomarkers for progression of fibrosis in systemic sclerosis.

METHODS

We included patients meeting the 2013 American College of Rheumatology and European League Against Rheumatism criteria and healthy controls from a derivation and validation cohort. The primary outcome was progression of fibrosis at follow-up, defined as decline in percentage of predicted forced vital capacity of 10% or more in patients with interstitial lung disease or increase in modified Rodnan skin score of 25% or more and more than 5 points at a 1-year follow-up visit. Longitudinal assessment and biobanking followed European Scleroderma Trials and Research standards. Extracellular matrix-degradation (BGM, C3M, C4M, and C6M) and extracellular matrix-formation neo-epitopes (PRO-C1, PRO-C3, PRO-C4, PRO-C5, and PRO-C6) were measured in serum using validated ELISAs.

FINDINGS

Between Aug 18, 2011, and Jan 19, 2015, 149 patients with systemic sclerosis (27 [18%] progressors and 122 [82%] non-progressors) and 29 healthy controls were included in the derivation cohort. Concentrations of type III and IV collagen neo-epitopes were higher in patients with systemic sclerosis compared with healthy controls and were significantly associated with systemic sclerosis in univariable logistic regression. Concentrations of degradation neo-epitopes of type III and IV collagens and their turnover ratios distinguished between progressors and non-progressors (C3M area under the curve 0·77 [95% CI 0·67-0·86], p<0·0001; PRO-C3:C3M 0·70 [0·59-0·80], p=0·0013; C4M 0·73 [0·63-0·82], p<0·0001; PRO-C4:C4M 0·75 [0·64-0·86], p<0·0001). 384 patients with systemic sclerosis (73 [19%] progressors) and 60 healthy controls were included in the multicentre validation cohort between April 17, 2003, and Jan 24, 2017. Analysis of the validation cohort confirmed that neo-epitopes of type III and IV collagens are changed in progressors. In a pooled analysis of both cohorts, the serum concentrations of formation neo-epitopes PRO-C3 and PRO-C4 and the turnover ratio of type IV collagen (PRO-C4:C4M) were higher in skin progressors. The turnover ratio of type IV collagen and PRO-C3 significantly predicted skin progression in a multivariable model adjusted for modified Rodnan skin score, sex, and age.

INTERPRETATION

These data suggest that neo-epitopes of type III and IV collagens are promising biomarkers for the assessment and prediction of extracellular matrix remodelling in systemic sclerosis. They could be used in clinical practice to risk stratify patients at risk of progression of fibrosis.

FUNDING

None.

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.

Dermal fibroblasts have different extracellular matrix profiles induced by TGF-β, PDGF and IL-6 in a model for skin fibrosis

Different stimulants might induce different extracellular matrix profiles. It is essential to gain an understanding and quantification of these changes to allow for focused anti-fibrotic drug development. This study investigated the expression of extracellular matrix by dermal fibroblast mimicking fibrotic skin diseases as SSc using clinically validated biomarkers. Primary healthy human dermal fibroblasts were grown in media containing FICOLL. The cells were stimulated with PDGF-AB, TGF-β1, or IL-6. Anti-fibrotic compounds (iALK-5, Nintedanib) were added together with growth factors. Biomarkers of collagen formation and degradation together with fibronectin were evaluated by ELISAs in the collected supernatant. Immunohistochemical staining was performed to visualize fibroblasts and proteins, while selected gene expression levels were examined through qPCR. TGF-β and PDGF, and to a lesser extent IL-6, increased the metabolic activity of the fibroblasts. TGF-β primarily increased type I collagen and fibronectin protein and gene expression together with αSMA. PDGF stimulation resulted in increased type III and VI collagen formation and gene expression. IL-6 decreased fibronectin levels. iALK5 could inhibit TGF-β induced fibrosis while nintedanib could halt fibrosis induced by TGF-β or PDGF. Tocilizumab could not inhibit fibrosis induced in this model. The extent and nature of fibrosis are dependent on the stimulant. The model has potential as a pre-clinical model as the fibroblasts fibrotic phenotype could be reversed by an ALK5 inhibitor and Nintedanib.

Prolonged Scar-in-a-Jar: an in vitro screening tool for anti-fibrotic therapies using biomarkers of extracellular matrix synthesis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a rapidly progressing disease with challenging management. To find novel effective therapies, better preclinical models are needed for the screening of anti-fibrotic compounds. Activated fibroblasts drive fibrogenesis and are the main cells responsible for the accumulation of extracellular matrix (ECM). Here, a prolonged Scar-in-a-Jar assay was combined with clinically validated biochemical markers of ECM synthesis to evaluate ECM synthesis over time. To validate the model as a drug screening tool for novel anti-fibrotic compounds, two approved compounds for IPF, nintedanib and pirfenidone, and a compound in development, omipalisib, were tested.

METHODS

Primary human lung fibroblasts from healthy donors were cultured for 12 days in the presence of ficoll and were stimulated with TGF-β1 with or without treatment with an ALK5/TGF-β1 receptor kinase inhibitor (ALK5i), nintedanib, pirfenidone or the mTOR/PI3K inhibitor omipalisib (GSK2126458). Biomarkers of ECM synthesis were evaluated over time in cell supernatants using ELISAs to assess type I, III, IV, V and VI collagen formation (PRO-C1, PRO-C3, PRO-C4, PRO-C5, PRO-C6), fibronectin (FBN-C) deposition and α-smooth muscle actin (α-SMA) expression.

RESULTS

TGF-β1 induced synthesis of PRO-C1, PRO-C6 and FBN-C as compared with unstimulated fibroblasts at all timepoints, while PRO-C3 and α-SMA levels were not elevated until day 8. Elevated biomarkers were reduced by suppressing TGF-β1 signalling with ALK5i. Nintedanib and omipalisib were able to reduce all biomarkers induced by TGF-β1 in a concentration dependent manner, while pirfenidone had no effect on α-SMA.

CONCLUSIONS

TGF-β1 stimulated synthesis of type I, III and VI collagen, fibronectin and α-SMA but not type IV or V collagen. Synthesis was increased over time, although temporal profiles differed, and was modulated pharmacologically by ALK5i, nintedanib, pirfenidone and omipalisib. This prolonged 12-day Scar-in-a-Jar assay utilising biochemical markers of ECM synthesis provides a useful screening tool for novel anti-fibrotic compounds.

Resolution of NASH and hepatic fibrosis by the GLP-1R/GcgR dual-agonist Cotadutide via modulating mitochondrial function and lipogenesis

Non-alcoholic fatty liver disease and steatohepatitis are highly associated with obesity and type 2 diabetes mellitus. Cotadutide, a GLP-1R/GcgR agonist, was shown to reduce blood glycemia, body weight and hepatic steatosis in patients with T2DM. Here, we demonstrate that the effects of Cotadutide to reduce body weight, food intake and improve glucose control are predominantly mediated through the GLP-1 signaling, while, its action on the liver to reduce lipid content, drive glycogen flux and improve mitochondrial turnover and function are directly mediated through Gcg signaling. This was confirmed by the identification of phosphorylation sites on key lipogenic and glucose metabolism enzymes in liver of mice treated with Cotadutide. Complementary metabolomic and transcriptomic analyses implicated lipogenic, fibrotic and inflammatory pathways, which are consistent with a unique therapeutic contribution of GcgR agonism by Cotadutide in vivo. Significantly, Cotadutide also alleviated fibrosis to a greater extent than Liraglutide or Obeticholic acid (OCA), despite adjusting dose to achieve similar weight loss in 2 preclinical mouse models of NASH. Thus Cotadutide, via direct hepatic (GcgR) and extra-hepatic (GLP-1R) effects, exerts multi-factorial improvement in liver function and is a promising therapeutic option for the treatment of steatohepatitis.

Use of Plasma Fragments of Propeptides of Type III, V, and VI Procollagen for the Detection of Liver Fibrosis in Type 2 Diabetes

OBJECTIVE

This study assessed the utility of plasma fragments of propeptides of type III (PRO-C3), V (PRO-C5), and VI (PRO-C6) procollagen for the detection of liver fibrosis in patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

Patients with T2DM (n = 191) underwent an oral glucose tolerance test, a liver ¹H-MRS, and a liver biopsy when indicated. PRO-C3, PRO-C5, and PRO-C6 were blindly assessed.

RESULTS

PRO-C3 performed well for the diagnosis of moderate-to-advanced (area under the receiver operating characteristic curve [AUROC] 0.81 [95% CI 0.74-0.88]) and advanced (AUROC 0.88 [0.80-0.95]) fibrosis in T2DM patients. Its performance was similar to that of AST to platelet ratio index (APRI) (AUROC 0.83 and 0.87, respectively) and Fibrosis-4 (FIB-4) (AUROCs 0.83 and 0.86, respectively) scores. Use of PRO-C5 and PRO-C6 did not improve the accuracy to detect liver fibrosis. After 18 months, PRO-C3 changes were associated with changes in fibrosis stages.

CONCLUSIONS

PRO-C3 performed well for the detection of fibrosis in T2DM patients and showed promising results for prediction of histological changes in fibrosis stage with treatment.

Alterations in non-type I collagen biomarkers in osteogenesis imperfecta

Osteogenesis imperfecta [1] is a rare disorder of connective tissue caused by abnormalities in the synthesis or processing of type I collagen. Type I collagen is the most abundant type of collagen and is expressed in almost all connective tissues. Given that type I collagen interacts with other collagens based in the extracellular matrix (ECM), we hypothesized changes in type I collagen in OI would result in perturbations in the homeostasis of other collagen types. We measured serum biomarkers of several non-type I collagens in patients with mild (type I) and moderate-to-severe (type III/IV) OI. Compared to controls, those with moderate-to severe OI had a higher mean level of the synthesis markers of collagen III (ProC3) (P = 0.02), and levels of collagen V (ProC5) (P = 0.07) were slightly, but not significantly, higher. Degradation markers of collage type IV (C4M2) (P = 0.04) and type VI (C6M) (P = 0.003) were also higher. In each case, a test for trend suggested levels were higher in moderate-to-severe OI, intermediate in mild OI, and lowest in controls (P = 0.06-0.002). These changes supports the hypothesis that mutations in type I collagen induce a widespread alteration in the ECM, and that the diverse clinical manifestations of OI reflect an extensive disruption in ECM biology.

Serum biomarkers of collagen turnover as potential diagnostic tools in diffuse systemic sclerosis: A cross-sectional study

BACKGROUND

Systemic sclerosis (SSc) is characterized by excessive fibrosis throughout the body. This leads to the release of extracellular matrix (ECM) fragments into circulation, where they may be quantified as biomarkers. The objectives were to investigate levels of ECM turnover biomarkers and the diagnostic power of these.

METHODS

Diffuse SSc patients (n = 40) fulfilling the ACR/EULAR 2013 classification criteria and asymptomatic controls were included. Patients were divided into early (<2 years of symptoms; n = 20) and late (>10 years of symptoms; n = 20) diffuse SSc. Biomarkers of type I (C1M), III (C3A, C3M), IV (C4M), V (C5M) and VI (C6M) collagen degradation and type I (PRO-C1), II (PRO-C2), III (PRO-C3), IV (PRO-C4), V (PRO-C5) and VI (PRO-C6) collagen formation were measured in serum. Repeated measures ANOVA was used to test for differences in biomarker levels and the area under the receiver operating characteristic curve (AUC) was used to investigate the ability of the biomarkers to separate groups.

RESULTS

In early diffuse SSc, formation biomarkers of type III, IV, V and VI collagen were significantly increased compared to asymptomatic controls (p<0.0001). Moreover, in early diffuse SSc formation biomarkers of type III, V and VI collagen were significantly increased compared to late diffuse SSc (p = 0.0006, 0.003 and 0.004, respectively). Type I (p<0.0001), III (C3M: p = 0.001, and C3A: p = 0.02), IV (p<0.0001) and VI (p<0.0001) collagen degradation biomarkers significantly increased in early diffuse SSc compared to controls. C4M, C6M, PRO-C4, PRO-C5 and PRO-C6 had an AUC of >0.85 when assessing asymptomatic controls vs. diffuse SSc. Biomarkers of type VI collagen (PRO-C6 and C6M) turnover had the best separation with an AUC's of >0.90.

CONCLUSION

Formation biomarkers of ECM turnover were shown to be significantly different between asymptomatic controls and diffuse SSc. This pilot study suggest that serological biomarkers of the ECM turnover is potentially applicable in SSc.

Type V Collagen is Persistently Altered After Inguinal Hernia Repair

BACKGROUND AND AIMS

Hernia formation is associated with alterations of collagen metabolism. Collagen synthesis and degradation cause a systemic release of products, which are measurable in serum. Recently, we reported changes in type V and IV collagen metabolisms in patients with inguinal and incisional hernia. The aim of this study was to determine if the altered collagen metabolism was persistent after hernia repair.

MATERIAL AND METHODS

Patients who had undergone repairs for inguinal hernia (n = 11) or for incisional hernia (n = 17) were included in this study. Patients who had undergone elective cholecystectomy served as controls (n = 10). Whole venous blood was collected 35-55 months after operation. Biomarkers for type V collagen synthesis (Pro-C5) and degradation (C5M) and those for type IV collagen synthesis (P4NP) and degradation (C4M2) were measured by a solid-phase competitive assay.

RESULTS

The turnover of type V collagen (Pro-C5/C5M) was slightly higher postoperatively when compared to preoperatively in the inguinal hernia group (P = 0.034). In addition, the results revealed a postoperatively lower type V collagen turnover level in the inguinal hernia group compared to controls (P = 0.012). In the incisional hernia group, the type V collagen turnover was higher after hernia repair (P = 0.004) and the postoperative turnover level was not different from the control group (P = 0.973).

CONCLUSION

Patients with an inguinal hernia demonstrated a systemic and persistent type V collagen turnover alteration. This imbalance of the collagen metabolism may be involved in the development of inguinal hernias.

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.

Misbalance in type III collagen formation/degradation as a novel serological biomarker for penetrating (Montreal B3) Crohn's disease

BACKGROUND

Misbalances in extracellular matrix turnover are key factors in the development of stricturing (Montreal B2) and penetrating (Montreal B3) Crohn's disease.

AIM

To determine whether serological markers for collagen formation and degradation could serve as biomarkers for complications of Crohn's disease.

METHODS

Serum biomarkers for type I, III, V and VI collagen formation (P1NP, Pro-C3, Pro-C5, Pro-C6) and matrix metalloproteinase mediated degradation (C1M, C3M, C5M and C6M) were measured in a retrospective, single centre cohort of 112 patients with Crohn's disease in the terminal ileum (nonstricturing/nonpenetrating: n=40, stricturing: n=55, penetrating: n=17) and 24 healthy controls. Active inflammation was defined as CRP >5 mg/L.

RESULTS

C3M and Pro-C5 levels were higher in penetrating vs nonpenetrating/nonstricturing and stricturing disease (33.6±5 vs 25.8±2.2 [P=.004] and 27.2±2.3 [P=.018] nmol/L C3M, 1262.7±259.4 vs 902.9±109.9 [P=.005] and 953.0±106.4 [P=.015] nmol/L Pro-C5). C1M (71.2±26.1 vs 46.2±6.2 nmol/L [P<.001]), C3M (31.6±3.9 vs 26.1±1.6 nmol/L [P=.002] and Pro-C5 levels (1171.7±171.5 vs 909.6±80.4 nmol/L [P=.002]) were higher in patients with active inflammation vs without active inflammation. Pro-C3/C3M-ratios were best to differentiate between penetrating vs nonstricturing/nonpenetrating and stricturing disease with area under the curves of 0.815±0.109 (P<.001) and 0.746±0.114 (P=.002) respectively.

CONCLUSIONS

Serological biomarkers show that penetrating Crohn's disease is characterised by increased matrix metalloproteinase-9 degraded type III collagen and formation of type V collagen. Active inflammation in Crohn's disease is characterised by increased formation of type V collagen and increased matrix metalloproteinase mediated breakdown of type I, III collagen. Pro-C3/C3M ratios are superior in differentiating between penetrating Crohn's disease vs inflammatory and stricturing Crohn's 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.

Abdominal wall hernias-A local manifestation of systemically impaired quality of the extracellular matrix

BACKGROUND

Throughout life, inguinal hernia develops in approximately every fourth man, some of whom develop multiple hernias. If patients at risk of developing multiple hernias could be identified by a serologic biomarker, treatment might be able to be tailored and improved. Evidence suggests that abdominal wall hernia formation is associated with altered collagen metabolism. The aim of this study was to evaluate biomarkers for type IV and V collagen turnover in patients with multiple hernias and control subjects without hernia.

METHODS

Venous blood was collected from 88 men (mean age, 62 years) with a history of more than 3 hernia repairs and 86, age-matched men without hernias. Biomarkers for synthesis of collagen type IV (P4NP) and type V (P5CP) as well as breakdown (C4M and C5M) were measured in serum by validated, solid-phase, competitive assays. Collagen turnover was indicated by the ratio between the biomarker for synthesis and breakdown.

RESULTS

Type IV collagen turnover was 1.4-fold increased in patients with multiple hernias compared to control subjects (P < .001), whereas type V collagen turnover was 1.7-fold decreased (P < .001). Diagnostic power of P5CP was 0.83 (95%C.I.:0.77-0.89), P < .001.

CONCLUSION

Patients with multiple hernias exhibit increased turnover of type IV collagen and a decreased turnover of type V collagen, demonstrating systemically altered collagen turnover. Biomarkers for type V collagen turnover may be used to identify patients at risk for or with multiple hernias.

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.

Pro-C5, a marker of true type V collagen formation and fibrillation, correlates with portal hypertension in patients with alcoholic cirrhosis

BACKGROUND AND AIMS

The hepatic venous pressure gradient (HVPG) is an important but invasive diagnostic and prognostic marker in cirrhotic patients. The aim of the study was to evaluate a novel biochemical plasma marker of true type V collagen formation (Pro-C5) for describing HVPG.

METHODS

Ninety-four patients mainly with alcoholic cirrhosis and fourteen liver-healthy controls were included in a retrospective study. Relevant clinical and routine laboratory data and hemodynamics were determined. Plasma Pro-C5 was correlated to HVPG and liver function parameters. Furthermore, Pro-C5 was combined in a linear regression model.

RESULTS

Plasma Pro-C5 correlated to HVPG, indocyanine green clearance, sustained vascular resistance and mean arterial pressure (r = -0.68-0.33, p < 0.0001). A multiple regression analysis including Pro-C5, alanine aminotransferase, bilirubin and model for end-stage liver disease (MELD) improved the correlation to HVPG (r = 0.74, p < 0.0001). Plasma Pro-C5 was positively or negatively correlated to a number of routine liver function markers and MELD score (r = 0.27-0.68; p < 0.05-0.0001). Furthermore, plasma Pro-C5 could clearly separate patients with a HVPG <10 mmHg or HVPG ≥10 mmHg (p < 0.001, area under the curve (AUC) = 0.73), HVPG 10-<16 mmHg or HVPG ≥16 mmHg (p < 0.001, AUC = 0.68) and controls from diseased patients (p < 0.0001, AUC = 0.88). Finally, there was a clear relation to increasing Child score A-C and plasma Pro-C5 (ANOVA p < 0.001).

CONCLUSION

Plasma Pro-C5 reflects liver hemodynamics, liver function, disease stage and clinically significant portal hypertension (PH). A multimarker model in combination with clinical scores predicted HVPG and separated clinical relevant HVPG thresholds. Plasma Pro-C5 may be suitable for the noninvasive evaluation of PH in patients with cirrhosis.

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

BACKGROUND

Nearly 45% of all deaths are associated with chronic fibroproliferative diseases, of which the primary characteristic is altered remodelling of the extracellular matrix. A major difficulty in developing anti-fibrotic therapies is the lack of accurate and established techniques to estimate dynamics of fibrosis, regression or progression, in response to therapy.

AIM

One of the most pressing needs in modern clinical chemistry for fibroproliferative disorders is the development of biomarkers for early diagnosis, prognosis, and early efficacy for the benefit of patients and to facilitate improved drug development. The aim of this article was to review the serological biomarkers that may assist in early diagnosis of patients, separate fast from slow- or nonprogressors, and possibly assist in drug development for fibroproliferative diseases, exemplified by liver fibrosis. The lack of success of biochemical markers and the possible reasons for this is discussed in the context of other fields with biomarker success.

METHOD

This is a personal opinion review article.

RESULTS

Biochemical markers, originating from the fibrotic structure, may have increased specificity and sensitivity for disease. Assessment of the tissue turnover balance by measurement of tissue formation and tissue degradation separately by novel technologies may provide value.

CONCLUSIONS

Novel technologies focused on the protein fingerprint in addition to biomarker classification, may increase the quality of biomarker development and provide the much needed biomarkers to further the fibroproliferative field. This is in direct alignment with the Food and Drug Administration and European Medicinal Agencies initiatives of personal health care.

Involvement of mast cells in adipose tissue fibrosis

Recently, fibrosis is observed in obese adipose tissue; however, the pathogenesis remains to be clarified. Obese adipose tissue is characterized by chronic inflammation with massive accumulation of immune cells including mast cells. The objective of the present study was to clarify the relationship between fibrosis and mast cells in obese adipose tissue, as well as to determine the origin of infiltrating mast cells. We observed the enhancement of mast cell accumulation and fibrosis in adipose tissue of severely obese diabetic db/db mice. Furthermore, adipose tissue-conditioned medium (ATCM) from severely obese diabetic db/db mice significantly enhanced collagen 5 mRNA expression in NIH-3T3 fibroblasts, and this enhancement was suppressed by the addition of an anti-mast cell protease 6 (MCP-6) antibody. An in vitro study showed that only collagen V among various types of collagen inhibited preadipocyte differentiation. Moreover, we found that ATCM from the nonobese but not obese stages of db/db mice significantly enhanced the migration of bone marrow-derived mast cells (BMMCs). These findings suggest that immature mast cells that infiltrate into adipose tissue at the nonobese stage gradually mature with the progression of obesity and diabetes and that MCP-6 secreted from mature mast cells induces collagen V expression in obese adipose tissue, which may contribute to the process of adipose tissue fibrosis. Induction of collagen V by MCP-6 might accelerate insulin resistance via the suppression of preadipocyte differentiation.

Novel serological neo-epitope markers of extracellular matrix proteins for the detection of portal hypertension

BACKGROUND

The hepatic venous pressure gradient (HVPG) is an invasive, but important diagnostic and prognostic marker in cirrhosis with portal hypertension (PHT). During cirrhosis, remodelling of fibrotic tissue by matrix metalloproteinases (MMPs) is a permanent process generating small fragments of degraded extracellular matrix (ECM) proteins known as neoepitopes, which are then released into the circulation.

AIM

To investigate their potential as plasma markers for detection of PHT.

METHODS

Ninety-four patients with alcoholic cirrhosis and 20 liver-healthy controls were included. Clinical and laboratory data of the patients were collected. All patients received HVPG measurement with blood sampling. In these samples, the following degradation or formation markers were measured: C1M (type I-collagen), C3M and PRO-C3 (type III collagen), C4M and P4NP 7S (type IV collagen), C5M (type V collagen), C6M (type VI collagen), BGM (biglycan), ELM (elastin), CRPM (CRP).

RESULTS

All ECM markers except for CRPM correlated significantly with HVPG. Interestingly, C4M, C5M and ELM levels were significantly higher in patients with HVPG >10 mmHg. Multiple regression analysis identified PRO-C3, C6M and ELM as significant determinants, while the models A and B including PRO-C3, ELM, C6M and model for end-stage liver disease (MELD) provided better description of PHT (r = 0.75, P < 0.0001). The models provided odds ratios of >100 for having clinical significant PHT.

CONCLUSIONS

These novel non-invasive extracellular matrix markers reflect the degree of liver dysfunction. The different degrees of portal hypertension correlated with these circulating neoepitopes. Using a single blood sample, these neoepitopes in combination with MELD detect the level of portal hypertension.

Cellular re- and de-programming by microenvironmental memory: why short TGF-β1 pulses can have long effects

Background

Fibrosis poses a substantial setback in regenerative medicine. Histopathologically, fibrosis is an excessive accumulation of collagen affected by myofibroblasts and this can occur in any tissue that is exposed to chronic injury or insult. Transforming growth factor (TGF)-β1, a crucial mediator of fibrosis, drives differentiation of fibroblasts into myofibroblasts. These cells exhibit α-smooth muscle actin (α-SMA) and synthesize high amounts of collagen I, the major extracellular matrix (ECM) component of fibrosis. While hormones stimulate cells in a pulsatile manner, little is known about cellular response kinetics upon growth factor impact. We therefore studied the effects of short TGF-β1 pulses in terms of the induction and maintenance of the myofibroblast phenotype.

Results

Twenty-four hours after a single 30 min TGF-β1 pulse, transcription of fibrogenic genes was upregulated, but subsided 7 days later. In parallel, collagen I secretion rate and α-SMA presence were elevated for 7 days. A second pulse 24 h later extended the duration of effects to 14 days. We could not establish epigenetic changes on fibrogenic target genes to explain the long-lasting effects. However, ECM deposited under singly pulsed TGF-β1 was able to induce myofibroblast features in previously untreated fibroblasts. Dependent on the age of the ECM (1 day versus 7 days’ formation time), this property was diminished. Vice versa, myofibroblasts were cultured on fibroblast ECM and cells observed to express reduced (in comparison with myofibroblasts) levels of collagen I.

Conclusions

We demonstrated that short TGF-β1 pulses can exert long-lasting effects on fibroblasts by changing their microenvironment, thus leaving an imprint and creating a reciprocal feed-back loop. Therefore, the ECM might act as mid-term memory for pathobiochemical events. We would expect this microenvironmental memory to be dependent on matrix turnover and, as such, to be erasable. Our findings contribute to the current understanding of fibroblast induction and maintenance, and have bearing on the development of antifibrotic drugs.

Bringing cancer serological diagnosis to a new level: focusing on HER2, protein ectodomain shedding and neoepitope technology

Cancer is a heterogeneous disease and consequently an exact diagnosis is as important as the actual therapy. Therefore, identification of novel diagnostic biomarker targets is urgently needed. Physiological and pathological changes are reflected by post-translational modifications of proteins. Each post-translational modification (e.g., proteolytic cleavage) is the result of a specific local process and may produce disease-specific neoepitopes. Neoepitopes have been successfully used as biomarkers in many diseases, and may also serve as promising tools in the development of future diagnostic assays within oncology. By specifically targeting neoepitopes, more information regarding disease-type and -state may be obtained and future research into neoepitopes will provide important and novel means for the diagnosis, prognosis and treatment efficacy in cancer. In this paper, we focus on protein ectodomain shedding and the generation of neoepitopes as future noninvasive (serological) cancer biomarkers. We use the protein ectodomain shedding of the human epidermal growth factor receptor 2, which is associated with breast cancer, as an example. We assess the current status of measuring human epidermal growth factor receptor 2 and discuss how this potentially could be improved. Furthermore, we expand the discussion to include examples of other cancer associated proteins.

Protein fingerprinting of the extracellular matrix remodelling in a rat model of liver fibrosis--a serological evaluation

BACKGROUND/AIM

We investigated nine novel biomarkers of extracellular matrix (ECM) remodelling in a rat model of liver fibrosis.

METHODS

Liver fibrosis was induced in 52 male Wistar rats by inhalation of carbon tetrachloride and the level of hepatic fibrosis was assessed by Sirius red staining compared with controls. The novel serum biochemical markers assessed in the model were type I-(C1M), type III-(C3M), type IV-(C4M) and type VI-(C6M) collagen, citrullinated vimentin (VICM) and biglycan (BGM) all protein fragments generated by matrix metalloproteinases; and formation markers of type III-(P3NP), type VI (P4NP 7S) and type V (P5CP) collagen; hepatic mRNA type I collagen alpha-1 chain levels, serum potassium, sodium, osmolarity, alanine aminotransferase, lactate dehydrogenase, albumin and creatinine.

RESULTS

Stratification of the CCl(4) -treated rats according to total hepatic collagen showed that the degradation markers were significantly elevated in mild to severe fibrosis except for C6M which was also elevated in early fibrosis (P < 0.05). The highest Z-scores in early and moderate fibrosis were provided by P4NP 7S and alanine aminotransferase. All nine markers of ECM remodelling were highly related to the extent of liver fibrosis induced by CCl(4) . The novel collagen formation marker, P4NP 7S, was reliable for the detection of early fibrosis, while the combination of the two markers, C6M and P5CP provided the best correlation with hepatic fibrosis in all fibrosis levels.

CONCLUSION

As the markers can be used for translational science, these markers may provide valuable information for the evaluation of liver fibrosis in clinical settings.

Circulating protein fragments of cartilage and connective tissue degradation are diagnostic and prognostic markers of rheumatoid arthritis and ankylosing spondylitis

Inflammation driven connective tissue turnover is key in rheumatic diseases, such as ankylosing spondylitis (AS). Few biomarkers are available for measuring disease prognosis or the efficacy of interventions applied in these tissue-related conditions. Type II collagen is the primary structural protein of cartilage and type III collagen of connective tissues, and obvious targets for the collagenalytic, which increase during tissue inflammation. The objective of the study was to investigate the diagnostic and prognostic utility of cartilage, C2M, and synovial, C3M, turnover biomarkers in AS. Serum samples were retrieved from patients suffering from AS (n = 103), RA (n = 47) and healthy controls (n = 56). AS progressors were defined as having new vertebral syndesmophytes or more that 3 unit change in mSASSS over a two-year period. Type II collagen degradation markers in serum were measured by the C2M ELISA, and type III collagen degradation by the C3M ELISA. Logistic regression and dichotomized decision tree were used to analyze the prognostic value of the markers individually or in combination. Both C2M and C3M levels were significantly higher in RA patients than in healthy controls (p<0.0001). Diagnostic utility was analyzed by ROC and areas under the curve (AUCs) were 72% and 89% for C2M and C3M, respectively. Both C2M and C3M, were significantly higher in serum samples from AS patient than from healthy controls (p<0.0001). The AUCs of C2M and C3M, respectively, were 70% and 81% for AS. A combination of C2M and C3M, dichotomized according to best cut-offs for individual markers, could correctly identify 80% of the progressors and 61% of the non-progressors. The present study is the first to show that specific biomarkers of cartilage and connective tissue degradation facilitate both diagnosis and prediction of progression of RA and AS.

Circulating levels of a collagen type v propeptide fragment in a carbon tetrachloride reversible model of liver fibrosis

Aim:

To measure levels of the collagen V formation marker CO5-1230 during liver fibrosis progression and regression.

Methods:

Monoclonal antibodies were raised against the sequence TAALGDIMGH located at the start of the C-terminal propeptide between amino acid position 1230′ and 1239′ (CO5-1230). An assay developed using the biotin-streptavidin system was evaluated in a rat reversible model of fibrosis. Animals were treated for duration of 4, 6 and 8 weeks. Animals that were treated for 8 weeks were left to regress for a period of 14, 20 and 26 weeks.

Results:

Mean CO5-1230 level for control animals was found to be 8.7 ng/mL. CO5-1230 marker levels, at termination points, for CCl₄ treated animals was be 8.7 ng/mL at 4 weeks (P < 0.05, ROC: 0.83), 11.4 ng/mL at 6 weeks (P < 0.001, ROC: 0.93) and 10.8 ng/mL at 8 weeks (P < 0.05, ROC: 0.82). During regression phase, marker levels were statistically significantly decreased when compared with the marker levels at 8 weeks of treatment. Marker levels were found to be 5.9 ng/mL (P < 0.001, ROC: 0.8) after 14 weeks of regression, 3.9 ng/mL (P < 0.001, ROC: 0.95) after 20 weeks and 4.5 ng/mL (P < 0.001, ROC: 0.97) after 26 weeks of regression.

Conclusions:

The data indicates that CO5-1230 levels are statistically significantly increased when CCl₄ intoxication stimulus is applied in all treatment time points. CO5-1230 levels return back to control levels when the stimulus is removed. The above finding adds to our previous evaluation of the marker and suggests that CO5-1230 may be a promising potential marker for liver fibrosis staging and monitoring in both disease progression and regression.

Future detection and monitoring of diabetes may entail analysis of both β-cell function and volume: how markers of β-cell loss may assist

Disease heterogeneity is as major issue in Type II Diabetes Mellitus (T2DM), and this patient inter-variability might not be sufficiently reflected by measurements of glycated haemoglobin (HbA1c).Β-cell dysfunction and β-cell death are initiating factors in development of T2DM. In fact, β-cells are known vanish prior to the development of T2DM, and autopsy of overt T2DM patients have shown a 60% reduction in β-cell mass.As the decline in β-cell function and mass have been proven to be pathological traits in T2DM, methods for evaluating β-cell loss is becoming of more interest. However, evaluation of β-cell death or loss is currently invasive and unattainable for the vast majority of diabetes patients. Serological markers, reflecting β-cell loss would be advantageous to detect and monitor progression of T2DM. Biomarkers with such capacities could be neo-epitopes of proteins with high β-cell specificity containing post translational modifications. Such tools may segregate T2DM patients into more appropriate treatment groups, based on their β-cell status, which is currently not possible. Presently individuals presenting with adequately elevated levels of both insulin and glucose are classified as T2DM patients, while an important subdivision of those is pending, namely those patients with sufficient β-cell capacity and those without. This may warrant two very different treatment options and patient care paths.Serological biomarkers reflecting β-cell health status may also assist development of new drugs for T2DM and aid physicians in better characterization of individual patients and tailor individual treatments and patient care protocols.

Extracellular matrix remodeling: the common denominator in connective tissue diseases. Possibilities for evaluation and current understanding of the matrix as more than a passive architecture, but a key player in tissue failure

Increased attention is paid to the structural components of tissues. These components are mostly collagens and various proteoglycans. Emerging evidence suggests that altered components and noncoded modifications of the matrix may be both initiators and drivers of disease, exemplified by excessive tissue remodeling leading to tissue stiffness, as well as by changes in the signaling potential of both intact matrix and fragments thereof. Although tissue structure until recently was viewed as a simple architecture anchoring cells and proteins, this complex grid may contain essential information enabling the maintenance of the structure and normal functioning of tissue. The aims of this review are to (1) discuss the structural components of the matrix and the relevance of their mutations to the pathology of diseases such as fibrosis and cancer, (2) introduce the possibility that post-translational modifications (PTMs), such as protease cleavage, citrullination, cross-linking, nitrosylation, glycosylation, and isomerization, generated during pathology, may be unique, disease-specific biochemical markers, (3) list and review the range of simple enzyme-linked immunosorbent assays (ELISAs) that have been developed for assessing the extracellular matrix (ECM) and detecting abnormal ECM remodeling, and (4) discuss whether some PTMs are the cause or consequence of disease. New evidence clearly suggests that the ECM at some point in the pathogenesis becomes a driver of disease. These pathological modified ECM proteins may allow insights into complicated pathologies in which the end stage is excessive tissue remodeling, and provide unique and more pathology-specific biochemical markers.

Molecular serum markers of liver fibrosis

Fibrosis is a hallmark histologic event of chronic liver diseases and is characterized by the excessive accumulation and reorganization of the extracellular matrix (ECM). The gold standard for assessment of fibrosis is liver biopsy. As this procedure has various limitations, including risk of patient injury and sampling error, a non-invasive serum marker for liver fibrosis is desirable. The increasing understanding of the pathogenesis of hepatic fibrosis has suggested several markers which could be useful indicators of hepatic fibrogenesis and fibrosis. These markers include serum markers of liver function, ECM synthesis, fibrolytic processes, ECM degradation and fibrogenesis related cytokines. Recently, neo-epitopes, which are post-translational modifications of proteins, have been successfully used in bone and cartilage diseases which are characterized by extensive ECM remodeling. Increasing numbers of studies are being undertaken to identify neo-epitopes generated during liver fibrosis, and which ultimately might be useful for diagnosing and monitoring fibrogenesis. To date, the metalloproteinases generated fragment of collagen I, III, IV and VI have been proven to be elevated in two rat models of fibrosis. This review summarizes the recent efforts that have been made to identify potentially reliable non-invasive serum markers. We used the recently proposed BIPED (Burden of disease, Investigative, Prognostic, Efficacy and Diagnostic) system to characterize potential serum markers and neo-epitope markers that have been identified to date.

Clinical evaluation of a matrix metalloproteinase-12 cleaved fragment of titin as a cardiovascular serological biomarker

BACKGROUND

Titin is a muscle-specific protein found in cardiac and skeletal muscles which is responsible for restoring passive tension. Levels and functioning of titin have been shown to be affected by cardiac damage. Due to the inherent difficulty of measuring titin levels in vivo in a clinical setting, we aimed to develop an assay that could reliably measure fragments of degraded titin in serum and potentially be used in the assessment of cardiac muscle damage.

METHODS

A competitive ELISA was developed to specifically measure levels of the titin sequence 12670' NVTVEARLIK 12679', derived by the degradation of titin by matrix metalloproteinase (MMP)-12. Serum samples from 90 individuals were divided into 3 equally sized groups. One group had been diagnosed with acute myocardial infarction (AMI) while the remaining two were asymptomatic individuals either with CT-scan signs of coronary calcium (CT-plusCa) or without coronary calcium (CT-noCa).

RESULTS

Mean geometric levels of the titin fragment in the CT-noCa group were 506.5 ng/ml (± 43.88). The CT-plusCa group showed 50.6% higher levels of the marker [763 ng/ml (± 90.14)] (P < 0.05). AMI patients showed 56.3% higher levels [792 ng/ml (± 149)] (P < 0.05).

CONCLUSIONS

The titin-12670 fragment is present in both individuals with undiagnosed and diagnosed CVD. The statistically significant increase in level of the marker in the AMI group is indicative that this neoepitope biomarker may be a useful serological marker in AMI.

Novel cardiac-specific biomarkers and the cardiovascular continuum

The concept of the cardiovascular continuum, introduced during the early 1990s, created a holistic view of the chain of events connecting cardiovascular-related risk factors with the progressive development of pathological-related tissue remodelling and ultimately, heart failure and death. Understanding of the tissue-specific changes, and new technologies developed over the last 25-30 years, enabled tissue remodelling events to be monitored in vivo and cardiovascular disease to be diagnosed more reliably than before. The tangible product of this evolution was the introduction of a number of biochemical markers such as troponin I and T, which are now commonly used in clinics to measure myocardial damage. However, biomarkers that can detect specific earlier stages of the cardiovascular continuum have yet to be generated and utilised. The majority of the existing markers are useful only in the end stages of the disease where few successful intervention options exist. Since a large number of patients experience a transient underlying developing pathology long before the signs or symptoms of cardiovascular disease become apparent, the requirement for new markers that can describe the early tissue-specific, matrix remodelling process which ultimately leads to disease is evident. This review highlights the importance of relating cardiac biochemical markers with specific time points along the cardiovascular continuum, especially during the early transient phase of pathology progression where none of the existing markers aid diagnosis.

Enzyme-linked immunosorbent serum assay specific for the 7S domain of Collagen Type IV (P4NP 7S): A marker related to the extracellular matrix remodeling during liver fibrogenesis

AIM

  The present study describes the ability of a newly developed N-terminal pro-peptides of type IV collagen 7S domain (P4NP 7S) competitive enzyme-linked immunosorbent assay (ELISA) for describing liver fibrosis. The assay applies a monoclonal antibody specific for a PIVNP 7S epitope 100% homologous in the human, rat, and mouse species.

METHODS

  Monoclonal antibodies were raised against selected P4NP 7S specific sequences. Antibodies were screened and a competitive ELISA assay was developed using a selected antibody. The assay was evaluated in relation to technical performance, and in two preclinical liver fibrosis models; the bile duct ligation model (BDL) and the carbon tetrachloride model (CCL4) both performed in rats.

RESULTS

  A technically robust P4NP 7S ELISA assay using a monoclonal antibody was produced. In the BDL and CCL4 liver fibrosis models it was observed that the P4NP 7S levels were significantly elevated in rat with liver fibrosis as seen by histology (CCL4: 283% elevated in the highest quartile of total hepatic collagen compared with controls, P = 0.001; BDL: 183% elevated at week 4 compared with sham, P < 0.001) and correlated to the amount of hepatic type IV collagen expression in BDL rats (r = 0.49, P < 0.05) in contrast to sham (r = -0.12). P4NP 7S also correlated to total collagen in CCL4 treated livers (P < 0.001, r = 0.67), however, not in controls (r = 0.04).

CONCLUSIONS

  This newly developed serum assay specific for P4NP 7S was highly related to liver fibrosis and correlated to extent of hepatic fibrosis. This assay may improve fibrosis quantification.

MMP mediated type V collagen degradation (C5M) is elevated in ankylosing spondylitis

OBJECTIVES

Type V collagen has been demonstrated to control fibril formation. The aim of this study was to develop an ELISA capable of detecting a fragment of type V collagen generated by MMP-2/9 and to evaluate the assay as biomarker for ankylosing spondylitis (AS).

DESIGN AND METHODS

A fragment unique to type V collagen and generated by both MMP-2/9 cleaved at the amino acid position 1317 (C5M) was selected for ELISA development. 40 AS patients and 40 age-matched controls were evaluated.

RESULTS

An ELISA detecting C5M with inter- and intra-assay variations of 9.1% and 4.4% was developed. C5M levels were significantly higher in AS patients compared to controls, 229% (p<0.0001). The diagnostic AUC was 83%.

CONCLUSIONS

This ELISA is the first for detecting type V collagen degradation. AS patients had highly elevated levels of MMP mediated type V collagen degradation. The prognostic and diagnostic values need to be further investigated in additional clinical settings.

Assessment of proteolytic degradation of the basement membrane: a fragment of type IV collagen as a biochemical marker for liver fibrosis

BACKGROUND

Collagen deposition and an altered matrix metalloproteinase (MMP) expression profile are hallmarks of fibrosis. Type IV collagen is the most abundant structural basement membrane component of tissue, which increases 14-fold during fibrogenesis in the liver. Proteolytic degradation of collagens by proteases produces small fragments, so-called neoepitopes, which are released systemically. Technologies investigating MMP-generated fragments of collagens may provide more useful information than traditional serological assays that crudely measure total protein. In the present study, we developed an ELISA for the quantification of a neoepitope generated by MMP degradation of type IV collagen and evaluated the association of this neoepitope with liver fibrosis in two animal models.

METHODS

Type IV collagen was degraded in vitro by a variety of proteases. Mass spectrometric analysis revealed more than 200 different degradation fragments. A specific peptide sequence, 1438'GTPSVDHGFL'1447 (CO4-MMP), in the α1 chain of type IV collagen generated by MMP-9 was selected for ELISA development. ELISA was used to determine serum levels of the CO4-MMP neoepitope in two rat models of liver fibrosis: inhalation of carbon tetrachloride (CCl4) and bile duct ligation (BDL). The levels were correlated to histological findings using Sirius red staining.

RESULTS

A technically robust assay was produced that is specific to the type IV degradation fragment, GTPSVDHGFL. CO4-MMP serum levels increased significantly in all BDL groups compared to baseline, with a maximum increase of 248% seen two weeks after BDL. There were no changes in CO4-MMP levels in sham-operated rats. In the CCl4 model, levels of CO4-MMP were significantly elevated at weeks 12, 16 and 20 compared to baseline levels, with a maximum increase of 88% after 20 weeks. CO4-MMP levels correlated to Sirius red staining results.

CONCLUSION

This ELISA is the first assay developed for assessment of proteolytic degraded type IV collagen, which, by enabling quantification of basement membrane degradation, could be relevant in investigating various fibrogenic pathologies. The CO4-MMP degradation fragment was highly associated with liver fibrosis in the two animal models studied.