Enzyme-linked immunosorbent serum assays (ELISAs) for rat and human N-terminal pro-peptide of collagen type I (PINP) — Assessment of corresponding epitopes

Circulating collagen type I fragments as specific biomarkers of cardiovascular outcome risk: Where are the opportunities?

Collagen type I (COL1) is the most abundant protein in the human body and is a main component in the extracellular matrix. The COL1 structure vastly influences normal tissue homeostasis, and changes in the matrix drive progression in multiple diseases. Cardiovascular diseases (CVD) are the leading cause of mortality and morbidity in many Western countries; alterations in the extracellular matrix turnover processes, including COL1, are known to influence the pathophysiological processes leading to CVD outcome. Peptides reflecting COL1 formation and degradation have been established and explored for over two decades in CVD. This review aims to combine and assess the evidence for using COL1-derived circulating peptides as biomarkers in CVD. Secondly, the review identifies existing pitfalls, and evaluates future opportunities for improving the technical characteristics and performance of the biomarkers for implementation in the clinical setting.

Serum extracellular matrix biomarkers in rheumatoid arthritis, psoriatic arthritis and psoriasis and their association with hand function

Inflammatory arthritis, including rheumatoid arthritis and psoriatic arthritis, is characterized by physical function impairment. This becomes apparent even before arthritis onset, as in psoriasis (PsO). Chronic inflammation triggers an accelerated remodeling of the extracellular matrix (ECM), resulting in released ECM fragments detectable in blood. We aimed to investigate levels of blood-based ECM biomarkers in patients with RA, PsA, PsO, and healthy controls and to explore the association of ECM biomarkers with hand function impairments. Patients with RA (n = 85), PsA (n = 115), PsO (n = 102) and controls (n = 110) were included in this cross-sectional study. ECM catabolic (C1M, C2M, C3M, C4M, PRO-C4, C6M, ARG), formation (PRO-C1, PRO-C3, PRO-C6) and inflammation biomarkers (VICM) were measured in serum from all patients. Objective hand function (fine motor skills (Moberg-Picking-Up Test), isometric grip strength (dynamometer) and patient-perceived hand function (Michigan Hand Questionnaire (MHQ)) were assessed. Patients with RA and PsA received treatment with disease-modifying anti-rheumatic drugs. VICM levels were higher in RA, PsA, and PsO than in controls (p < 0.0001). PsA and PsO showed higher C4M levels compared to controls (p < 0.0001, p < 0.0001), while C6M was lower in patients with RA, PsA and PsO than in controls (p < 0.0001, p < 0.001, p < 0.01). PsO presented with higher levels of C1M compared to controls and to RA (p < 0.001 and p < 0.0001). PRO-C6 correlated negatively with MHQ (ρ = -0.39, p < 0.01) and grip strength (ρ = -0.31, p < 0.05) in PsO, while only weak correlations were observed between biomarkers and hand function scores for RA and PsA patients (all ρ <  ± 0.2-0.3). Patients with RA, PsA, and PsO showed significant alterations in ECM remodeling biomarkers. Especially PsA and PsO had higher levels of inflammatory biomarkers compared to RA and controls, likely due to modulation by treatment. Predominantly in PsO, ECM formation biomarkers were associated with hand function impairments.

Regulation of fibronectin and collagens type I, III and VI by TNF-α, TGF-β, IL-13, and tofacitinib

Understanding how inflammatory cytokines influence profibrogenic wound healing responses in fibroblasts is important for understanding the pathogenesis of fibrosis. TNF-α and IL-13 are key cytokines in Th1 and Th2 immune responses, respectively, while TGF-β1 is the principal pro-fibrotic mediator. We show that 12-day fibroblast culture with TNF-α or IL-13 induces fibrogenesis, marked by progressively increasing type III and VI collagen formation, and that TGF-β1 co-stimulation amplifies these effects. Tofacitinib substantially reduced the formation of ECM proteins in response to IL-13, while fibrogenesis in response to TNF-α or TGF-β1 was marginally inhibited. The in vitro findings were supported by clinical observations in patients with active rheumatoid arthritis, which had elevated serum type III collagen formation, indicating ongoing fibrogenesis during inflammation. After 48-60 weeks of tofacitinib treatment, type III collagen degradation, aswell as formation, were significantly decreased compared to baseline, highlighting dual anti-inflammatory and anti-fibrogenic effects of tofacitinib. In contrast, other anti-inflammatory treatments including methotrexate, adalimumab and tocilizumab demonstrated anti-inflammatory effects only. Our results highlight fibro-inflammatory profiles associated with TNF-α or IL-13 stimulation, both alone and in combination with TGF-β1, and support the use of tofacitinib as an anti-fibrogenic treatment in chronic inflammatory conditions.

Longitudinal stability of molecular endotypes of knee osteoarthritis patients

OBJECTIVE

To assess the longitudinal stability of biomarker-based molecular endotypes of knee osteoarthritis (KOA) participants from APPROACH and to evaluate the consistency of findings in an independent KOA population.

METHODS

Nineteen biomarkers were measured longitudinally in 295 KOA participants from the APPROACH cohort. K-means clustering was used to identify the structural damage, inflammation, and low tissue turnover endotypes at the six-, 12-, and 24-month follow-ups. Endotype stability was defined as having the same independent endotype assignment longitudinally for patients with complete data (n = 226). Clinical and biochemical characteristics were compared between participants with longitudinally stable and unstable endotypes. The presence and longitudinal stability of the endotypes were evaluated in a different KOA population from the placebo arm of the oral salmon calcitonin trials.

RESULTS

An average overall longitudinal endotype stability of 55% (Fleiss' Kappa of 0.53; 95% confidence interval [CI]: 0.46, 0.60) was demonstrated. An average stability of 59% (range: 54-59%) was observed for the structural damage endotype (Fleiss' Kappa 0.52; 95% CI: 0.45, 0.60), 54% (52-56%) for the inflammatory (Fleiss' Kappa 0.61; 95% CI: 0.53, 0.68), and 50% (49-52%) for the low tissue turnover endotype (Fleiss' Kappa 0.46; 95% CI: 0.39, 0.54). Participants with longitudinally unstable endotypes exhibited molecular properties of more than one endotype, which were detectable already at the first visit.

CONCLUSIONS

Our study showed for the first time that more than half of KOA participants exhibited a longitudinally stable endotype, highlighting the applicability of biomarker-based endotyping in a clinical trial setting.

Fibrogenesis in Human Mucosa and Muscularis Precision-Cut Intestinal Slices

In Crohn's Disease (CD), intestinal fibrosis is a prevalent yet unresolved complication arising from chronic and transmural inflammation. The histological assessment of CD intestines shows changes in tissue morphology in all the layers, including the mucosa and muscularis. This study aimed to determine the differences in fibrogenesis between mucosa and muscularis. Human precision-cut intestinal slices (hPCIS) were prepared from human intestine mucosa and muscularis and treated with TGF-β1 and/or PDGF-BB for 72 h. Gene and protein expression and matrix metalloproteinase (MMP) activity were determined. The basal gene expression of various fibrosis markers was higher in muscularis compared to mucosa hPCIS. During incubation, Pro-Collagen-1A1 secretion increased in muscularis but not in mucosa hPCIS. MMP gene expression increased during incubation in mucosa and muscularis hPCIS, except for MMP9, MMP12, and MMP13 in muscularis hPCIS. Incubation with TGF-β1 caused increased COL1A1 expression in the mucosa but not in muscularis hPCIS. In muscularis hPCIS, TGF-β1 treatment caused a decrease in MMP1 and CTSK expression, while MMP13 was increased. In the presence of TGF-β1, protease inhibitor expression was stable, except for SERPINE1, which was increased in muscularis hPCIS. We conclude that fibrogenesis is more pronounced in muscularis hPCIS compared to mucosa hPCIS, especially when stimulated with TGF-β1.

The collagen landscape in cancer: profiling collagens in tumors and in circulation reveals novel markers of cancer-associated fibroblast subtypes

Cancer-associated fibroblasts (CAFs) deposit and remodel collagens in the tumor stroma, impacting cancer progression and efficacy of interventions. CAFs are the focus of new therapeutics with the aim of normalizing the tumor microenvironment. To do this, a better understanding of CAF heterogeneity and collagen composition in cancer is needed. In this study, we sought to profile the expression of collagens at multiple levels with the goal of identifying cancer biomarkers. We investigated the collagen expression pattern in various cell types and CAF subtypes in a publicly available single-cell RNA sequencing (RNA-seq) dataset of pancreatic ductal adenocarcinoma. Next, we investigated the collagen expression profile in tumor samples across cancer types from The Cancer Genome Atlas (TCGA) database and evaluated if specific patterns of collagen expression were associated with prognosis. Finally, we profiled circulating collagen peptides using a panel of immunoassays to measure collagen fragments in the serum of cancer patients. We found that pancreatic stellate cells and fibroblasts were the primary producers of collagens in the pancreas. COL1A1, COL3A1, COL5A1, COL6A1 were expressed in all CAF subtypes, whereas COL8A1, COL10A1, COL11A1, COL12A1 were specific to myofibroblast CAFs (myCAF) and COL14A1 specific to inflammatory CAFs (iCAF). In TCGA database, myCAF collagens COL10A1 and COL11A1 were elevated across solid tumor types, and multiple associations between high expression and worse survival were found. Finally, circulating collagen biomarkers were elevated in the serum of patients with cancer relative to healthy controls with COL11A1 (myCAF) having the best diagnostic accuracy of the markers measured. In conclusion, CAFs express a noncanonical collagen profile with specific collagen subtypes associated with iCAFs and myCAFs in PDAC. These collagens are deregulated at the cellular, tumor, and systemic levels across different solid tumors and associate with survival. These findings could lead to new discoveries such as novel biomarkers and therapeutic targets. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Preliminary investigation of elevated collagen and blood-clotting markers as potential noninvasive biomarkers for small cell lung cancer

BACKGROUND

Small cell lung cancer (SCLC) is highly aggressive with limited therapeutic options and a poor prognosis. Moreover, noninvasive biomarker tools for detecting disease and monitoring treatment response are lacking. To address this, we evaluated serum biomarkers of extracellular matrix proteins not previously explored in SCLC.

METHODS

We measured biomarkers in the serum of 16 patients with SCLC before and after chemotherapy as well as in the serum of 11 healthy individuals.

RESULTS

Our findings demonstrated that SCLC serum had higher levels of collagen type I degradation, collagen type III formation, and collagen type XI formation than healthy controls. In addition, we observed higher levels of type XIX and XXII collagens, fibrinogen, and von Willebrand factor A formation in SCLC serum. The formation of type I collagen did not exhibit any discernible variation. However, we observed a decrease in the degradation of type I collagen following chemotherapy.

CONCLUSION

Overall, our findings revealed elevated levels of collagen and blood-clotting markers in the serum of SCLC patients, indicating the potential of ECM proteins as noninvasive biomarkers for SCLC.

Plasma type I collagen α1 chain in relation to coronary artery disease: findings from a prospective population-based cohort and an acute myocardial infarction prospective cohort in Sweden

OBJECTIVES

To investigate the association between type I collagen α1 chain (COL1α1) levels and coronary artery disease (CAD) by using absolute quantification in plasma. Also, to investigate the correlates of COL1α1 to clinical characteristics and circulating markers of collagen metabolism.

DESIGN

Life conditions, Stress and Health (LSH) study: prospective cohort study, here with a nested case-control design.Assessing Platelet Activity in Coronary Heart Disease (APACHE) study: prospective cohort study.

SETTING

LSH: primary care setting, southeast Sweden.APACHE: cardiology department, university hospital, southeast Sweden.

PARTICIPANTS

LSH: 1007 randomly recruited individuals aged 45-69 (50% women). Exclusion criteria was serious disease. After 13 years of follow-up, 86 cases with primary endpoint were identified and sex-matched/age-matched to 184 controls.

APACHE

125 patients with myocardial infarction (MI), 73 with ST-elevation MI and 52 with non-ST-elevation MI.

EXCLUSION CRITERIA

Intervention study participation, warfarin treatment and short life expectancy.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome was the association between baseline COL1α1 and first-time major event of CAD, defined as fatal/non-fatal MI or coronary revascularisation after 13 years. Secondary outcomes were the association between the collagen biomarkers PRO-C1 (N-terminal pro-peptide of type I collagen)/C1M (matrix metalloproteinase-mediated degradation of type I collagen) and CAD; temporal change of COL1α1 after acute MI up to 6 months and lastly, correlates between COL1α1 and patient characteristics along with circulating markers of collagen metabolism.

RESULTS

COL1α1 levels were associated with CAD, both unadjusted (HR=0.69, 95% CI=0.56 to 0.87) and adjusted (HR=0.55, 95% CI=0.41 to 0.75). PRO-C1 was associated with CAD, unadjusted (HR=0.62, 95% CI=0.47 to 0.82) and adjusted (HR=0.61, 95% CI=0.43 to 0.86), while C1M was not. In patients with MI, COL1α1 remained unchanged up to 6 months. COL1α1 was correlated to PRO-C1, but not to C1M.

CONCLUSIONS

Plasma COL1α1 was independently and inversely associated with CAD. Furthermore, COL1α1 appeared to reflect collagen synthesis but not degradation. Future studies are needed to confirm whether COL1α1 is a clinically useful biomarker of CAD.

Fibroblasts are not just fibroblasts: clear differences between dermal and pulmonary fibroblasts' response to fibrotic growth factors

Systemic Sclerosis (SSc) hallmark is skin fibrosis, but up to 80% of the patients have fibrotic involvement in the pulmonary system. Antifibrotic drugs which have failed in a general SSc population have now been approved in patients with SSc-associated interstitial lung disease (ILD). This indicates that the fibrotic progression and regulation of fibroblasts likely depend on local factors specific to the tissue type. This study investigated the difference between dermal and pulmonary fibroblasts in a fibrotic setting, mimicking the extracellular matrix. Primary healthy fibroblasts were grown in a crowded environment and stimulated with TGF-β1 and PDGF-AB. The viability, morphology, migration capacity, extracellular matrix formation, and gene expression were assessed: TGF-β1 only increased the viability in the dermal fibroblasts. PDGF-AB increased the migration capacity of dermal fibroblasts while the pulmonary fibroblasts fully migrated. The morphology of the fibroblasts was different without stimulation. TGF-β1 increased the formation of type III collagen in pulmonary fibroblasts, while PDGF-AB increased it in dermal fibroblasts. The gene expression trend of type VI collagen was the opposite after PDGF-AB stimulation. The fibroblasts exhibit different response profiles to TGF-β1 and PDGF-AB; this suggests that drivers of fibrosis are tissue-dependent, which needs to be considered in drug development.

Levels of extracellular matrix metabolites are associated with changes in Ankylosing Spondylitis Disease Activity Score and MRI inflammation scores in patients with axial spondyloarthritis during TNF inhibitor therapy

BACKGROUND/PURPOSE

In axial spondyloarthritis (axSpA) inflammation of the sacroiliac joints and spine is associated with local extracellular matrix (ECM) remodeling of affected tissues. We aimed to investigate the association of ECM metabolites with treatment response in axSpA patients treated with TNF-α inhibitory therapy for 46 weeks.

METHODS

In a prospective clinical study of axSpA patients (n=55) initiating a TNF inhibitor (infliximab, etanercept, or adalimumab), serum concentrations of formation of type I (PRO-C1), type III (PRO-C3), and type VI (PRO-C6) collagen; turnover of type IV collagen (PRO-C4), and matrix-metalloproteinase (MMP)-degraded type III (C3M) collagen, MMP-degraded type IV (C4M), type VI (C6M), and type VII (C7M) collagen, and cathepsin-degraded type X collagen (C10C), MMP-mediated metabolite of C-reactive protein (CRPM), citrullinated vimentin (VICM), and neutrophil elastase-degraded elastin (EL-NE) were measured at baseline, week 2, week 22, and week 46.

RESULTS

Patients were mostly males (82%), HLA-B27 positive (84%), with a median age of 40 years (IQR: 32-48), disease duration of 5.5 years (IQR: 2-10), and a baseline Ankylosing Spondylitis Disease Activity Score (ASDAS) of 3.9 (IQR: 3.0-4.5). Compared to baseline, PRO-C1 levels were significantly increased after two weeks of treatment, C6M levels were significantly decreased after two and 22 weeks (repeated measures ANOVA, p=0.0014 and p=0.0015, respectively), EL-NE levels were significantly decreased after 2 weeks (p=0.0008), VICM levels were significantly decreased after two and 22 weeks (p=0.0163 and p=0.0374, respectively), and CRP were significantly decreased after two and 22 weeks (both p=0.0001). Baseline levels of PRO-C1, PRO-C3, C6M, VICM, and CRP were all associated with ASDAS clinically important and major improvement after 22 weeks (ΔASDAS ≥1.1) (Mann-Whitney test, p=0.006, p=0.008, p<0.001, <0.001, <0.001, respectively), while C6M, VICM and CRP levels were associated with ASDAS clinically important and major improvement after 46 weeks (ΔASDAS ≥2.0) (p=0.002, p=0.044, and p<0.001, respectively). PRO-C1 and C6M levels were associated with a Bath AS Disease Activity Score (BASDAI) response to TNF-inhibitory therapy after 22 weeks (Mann-Whitney test, p=0.020 and p=0.049, respectively). Baseline levels of PRO-C4 and C6M were correlated with the total SPARCC MRI Spine and Sacroiliac Joint Inflammation score (Spearman's Rho ρ=0.279, p=0.043 and ρ=0.496, p=0.0002, respectively).

CONCLUSIONS

Extracellular matrix metabolites were associated with ASDAS response, MRI inflammation, and clinical treatment response during TNF-inhibitory treatment in patients with axSpA.

Type XXII Collagen Complements Fibrillar Collagens in the Serological Assessment of Tumor Fibrosis and the Outcome in Pancreatic Cancer

Circulating fragments of type III collagen, measured by PRO-C3, has shown promising results as a tumor fibrosis biomarker. However, the fibrotic tumor microenvironment consists of many other collagens with diverse functions and unexplored biomarker potential. One example hereof is type XXII collagen (COL22). In this study, we investigated the biomarker potential of COL22 by measuring this in serum. An ELISA, named PRO-C22, was developed and measured in two serum cohorts consisting of patients with various solid tumors (n = 220) and healthy subjects (n = 33) (Cohort 1), and patients with pancreatic ductal adenocarcinoma (PDAC) (n = 34), and healthy subjects (n = 20) (Cohort 2). In Cohort 1, PRO-C22 was elevated in the serum from patients with solid tumors, compared to healthy subjects (p < 0.01 to p < 0.0001), and the diagnostic accuracy (AUROC) ranged from 0.87 to 0.98, p < 0.0001. In Cohort 2, the high levels of PRO-C22, in patients with PDAC, were predictive of a worse overall survival (HR = 4.52, 95% CI 1.90−10.7, p = 0.0006) and this remained significant after adjusting for PRO-C3 (HR = 4.27, 95% CI 1.24−10.4, p = 0.0013). In conclusion, PRO-C22 has diagnostic biomarker potential in various solid tumor types and prognostic biomarker potential in PDAC. Furthermore, PRO-C22 complemented PRO-C3 in predicting mortality, suggesting an additive prognostic value when quantifying different collagens.

Nintedanib modulates type III collagen turnover in viable precision-cut lung slices from bleomycin-treated rats and patients with pulmonary fibrosis

BACKGROUND

Aberrant extracellular matrix (ECM) deposition and remodelling is important in the disease pathogenesis of pulmonary fibrosis (PF). We characterised neoepitope biomarkers released by ECM turnover in lung tissue from bleomycin-treated rats and patients with PF and analysed the effects of two antifibrotic drugs: nintedanib and pirfenidone.

METHODS

Precision-cut lung slices (PCLS) were prepared from bleomycin-treated rats or patients with PF. PCLS were incubated with nintedanib or pirfenidone for 48 h, and levels of neoepitope biomarkers of type I, III and VI collagen formation or degradation (PRO-C1, PRO-C3, PRO-C6 and C3M) as well as fibronectin (FBN-C) were assessed in the culture supernatants.

RESULTS

In rat PCLS, incubation with nintedanib led to a reduction in C3M, reflecting type III collagen degradation. In patient PCLS, incubation with nintedanib reduced the levels of PRO-C3 and C3M, thus showing effects on both formation and degradation of type III collagen. Incubation with pirfenidone had a marginal effect on PRO-C3. There were no other notable effects of either nintedanib or pirfenidone on the other neoepitope biomarkers studied.

CONCLUSIONS

This study demonstrated that nintedanib modulates neoepitope biomarkers of type III collagen turnover and indicated that C3M is a promising translational neoepitope biomarker of PF in terms of therapy assessment.

Effects of Calcium Lactate-Enriched Pumpkin on Calcium Status in Ovariectomized Rats

This study aimed to evaluate the effects of enriched pumpkin on calcium status in ovariectomized rats. The study was conducted in sixty female Wistar rats, which were divided into six groups: a group fed a standard diet (C) and five ovariectomized groups fed a standard diet (OVX_C) or a diet with calcium lactate (CaL), with calcium lactate-enriched pumpkin (P_CaL), with calcium lactate and alendronate (CaL_B), or with calcium lactate-enriched pumpkin with alendronate (P_CaL_B). After 12 weeks of the intervention, the rats were sacrificed, and their blood and tissues were collected. The calcium concentrations in serum and in tissues were measured using flame atomic absorption spectrometry (AAS). Serum concentrations of procollagen type-1 amino-terminal propeptide (PINP), parathyroid hormone PTH, estrogen (ES), and osteocalcin (OC) were determined with enzyme-linked immunosorbent assay (ELISA). It was found that enriched pumpkin increased the calcium level in the kidneys (194.13 ± 41.01 mg) compared to the C (87.88 ± 12.42 mg) and OVX_C (79.29 ± 7.66 mg) groups. The addition of alendronate increased the calcium level in the femurs (267.63 ± 23.63 mg) and more than six times in the kidneys (541.33 ± 62.91 mg) compared to the OVX_C group (234.53 ± 21.67 mg and 87.88 ± 12.42 mg, respectively). We found that the CaL, P_CaL, and CaL_B groups had significantly lower PINP serum concentrations (4.45 ± 0.82 ng/mL, 4.14 ± 0.69 ng/mL, and 3.77 ± 0.33 ng/mL) and higher PTH serum levels (3.39 ± 0.54 ng/dL, 3.38 ± 0.57 ng/dL, and 3.47 ± 0.28 ng/dL) than the OVX_C group (4.69 ± 0.82 ng/mL and 2.59 ± 0.45 ng/dL, respectively). In conclusion, pumpkin enriched with calcium lactate affects calcium status and normalizes PINP and PTH serum levels in ovariectomized rats. Diet with enriched pumpkin and alendronate increase calcium concentration in the femur. Enriched pumpkin causes calcium to accumulate in the kidneys of ovariectomized rats; alendronate significantly exacerbates this effect.

Extracellular matrix protein turnover markers are associated with axial spondyloarthritis-a comparison with postpartum women and other non-axial spondyloarthritis controls with or without back pain

Background

Axial spondyloarthritis (axSpA) is a common chronic inflammatory disease, associated with extracellular matrix (ECM) remodeling of the cartilage, bone, and connective tissues. The primary symptom of axSpA is back pain, caused by inflammation. However, there is a medical need to truly identify patients with axSpA from other subjects with buttock or low back pain attributable to other reasons. We aimed to investigate circulating biomarkers of ECM/inflammation (MMP-degraded type I (C1M), II (C2M, T2CM), III (C3M), IV (C4M), VI (C6M), and X (C10C, COL10NC) collagens, CRPM, PROM and VICM) and ECM formation of type II (PRO-C2), III (PRO-C3), IV (PRO-C4), and VI (PRO-C6) collagens as potential biomarkers to identify patients with axSpA.

Methods

We measured biomarkers from a cross-sectional study with 204 participants by enzyme-linked immunosorbent assay (ELISA). The study included axSpA patients (N = 41), women with postpartum buttock/pelvic pain (N = 46), disc herniation (N = 25), and a group of healthy subjects (including women without postpartum pelvic pain (N = 14), subjects with various types of physical strain (cleaning staff (N = 26) long-distance runners (N = 23)), and healthy men (N = 29)). Differences between the groups were calculated by ANCOVA and AUC, while Spearman’s correlations were performed with ECM biomarkers and clinical scores.

Results

Patients with axSpA expressed significantly higher levels of C1M, C4M, and VICM (p < 0.05-p < 0.0001) compared to all the non-axSpA control groups. Further, C6M and PRO-C4 were significantly higher in patients with axSpA (both p < 0.0001) compared to women with postpartum pelvic pain and healthy subjects, whereas PRO-C3 was significantly lower compared to healthy subjects (p = 0.01). The best ECM common biomarker to differentiate between axSpA and the non-axSpA control groups was PRO-C4 (AUC ≥ 0.75; specificity ≥ 0.79, sensitivity = 0.65). Mild correlations were observed between collagen turnover and inflammation biomarkers and CRP and MRI (ρ ≥ 0.3; p < 0.05-p < 0.001).

Conclusions

Biomarkers of type I, IV, and VI collagen and biomarkers of inflammation showed an altered turnover in patients with axSpA compared with the non-axSpA control groups. Such biomarkers may be useful in combination with MRI or independently to separate patients with axSpA from other back pain conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02839-1.

Adipose-derived stromal cells increase the formation of collagens through paracrine and juxtacrine mechanisms in a fibroblast co-culture model utilizing macromolecular crowding

Background

Adipose-derived stromal cells (ASCs) possess a multitude of regenerative capabilities, which include immunomodulation, angiogenesis, and stimulation of extracellular matrix (ECM) remodeling. However, the underlying mechanisms leading to ECM remodeling remain largely elusive and highlight the need for functional in vitro models for mode of action studies. Therefore, the purpose of this study was to develop an in vitro co-culture model to investigate the capabilities of ASCs to modulate fibroblasts and ECM.

Methods

An ECM in vitro model with ASCs and normal human dermal fibroblasts (NHDFs) was established utilizing macromolecular crowding, ascorbic acid, and TGF-β stimulation. Paracrine and juxtacrine co-cultures were created using transwell inserts and cell cultures with direct cell–cell contacts. The cultures were screened using RT² PCR Profiler Arrays; the protein levels of myofibroblast differentiation marker alpha smooth muscle actin (αSMA) and ECM remodeling enzymes were analyzed using western blot on cell lysates; the formation of collagen type I, III, VI, and fibronectin was investigated using ELISA on culture supernatants; and the deposition of collagens was analyzed using immunocytochemistry.

Results

TGF-β stimulation of NHDF monocultures increased the expression of 18 transcripts relevant for ECM formation and remodeling, the protein levels of αSMA and matrix metalloproteinase-2 (MMP-2), the formation of collagen type I, III, VI, and fibronectin, and the deposition of collagen type I and VI and decreased the protein levels of MMP-14. Inclusion of ASCs in the ECM co-culture model increased the formation of collagen type I and III through paracrine mechanisms and the formation of collagen type VI through juxtacrine mechanisms.

Conclusions

The co-culture model provides effective stimulation of NHDF monocultures by TGF-β for enhanced formation and deposition of ECM. In the model, ASCs induce changes in ECM by increasing formation of collagen type I, III and VI. The obtained results could guide further investigations of ASCs’ capabilities and underlying mechanisms related to ECM formation and remodeling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02923-y.

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.

LPA1 antagonist BMS-986020 changes collagen dynamics and exerts antifibrotic effects in vitro and in patients with idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a debilitating lung disease with limited treatment options. A phase 2 trial (NCT01766817) showed that twice-daily treatment with BMS-986020, a lysophosphatidic acid receptor 1 (LPA₁) antagonist, significantly decreased the slope of forced vital capacity (FVC) decline over 26 weeks compared with placebo in patients with IPF. This analysis aimed to better understand the impact of LPA₁ antagonism on extracellular matrix (ECM)-neoepitope biomarkers and lung function through a post hoc analysis of the phase 2 study, along with an in vitro fibrogenesis model.

METHODS

Serum levels of nine ECM-neoepitope biomarkers were measured in patients with IPF. The association of biomarkers with baseline and change from baseline FVC and quantitative lung fibrosis as measured with high-resolution computed tomography, and differences between treatment arms using linear mixed models, were assessed. The Scar-in-a-Jar in vitro fibrogenesis model was used to further elucidate the antifibrotic mechanism of BMS-986020.

RESULTS

In 140 patients with IPF, baseline ECM-neoepitope biomarker levels did not predict FVC progression but was significantly correlated with baseline FVC and lung fibrosis measurements. Most serum ECM-neoepitope biomarker levels were significantly reduced following BMS-986020 treatment compared with placebo, and several of the reductions correlated with FVC and/or lung fibrosis improvement. In the Scar-in-a-Jar in vitro model, BMS-986020 potently inhibited LPA₁-induced fibrogenesis.

CONCLUSIONS

BMS-986020 reduced serum ECM-neoepitope biomarkers, which were previously associated with IPF prognosis. In vitro, LPA promoted fibrogenesis, which was LPA₁ dependent and inhibited by BMS-986020. Together these data elucidate a novel antifibrotic mechanism of action for pharmacological LPA₁ blockade. Trial registration ClinicalTrials.gov identifier: NCT01766817; First posted: January 11, 2013; https://clinicaltrials.gov/ct2/show/NCT01766817 .

An integrated multiomic and quantitative label-free microscopy-based approach to study pro-fibrotic signalling in ex vivo human precision-cut lung slices

Fibrosis can affect any organ, resulting in the loss of tissue architecture and function with often life-threatening consequences. Pathologically, fibrosis is characterised by the expansion of connective tissue due to excessive deposition of extracellular matrix (ECM) proteins, including the fibrillar forms of collagen. A significant limitation for discovering cures for fibrosis is the availability of suitable human models and techniques to quantify mature fibrillar collagen deposition as close as possible to human physiological conditions.Here we have extensively characterised an ex vivo cultured human lung tissue-derived, precision-cut lung slices (hPCLS) model using label-free second harmonic generation (SHG) light microscopy to quantify fibrillar collagen deposition and mass spectrometry-based techniques to obtain a proteomic and metabolomic fingerprint of hPCLS in ex vivo culture.We demonstrate that hPCLS are viable and metabolically active, with mesenchymal, epithelial, endothelial and immune cell types surviving for at least 2 weeks in ex vivo culture. Analysis of hPCLS-conditioned supernatants showed a strong induction of pulmonary fibrosis-related ECM proteins upon transforming growth factor-β1 (TGF-β1) stimulation. This upregulation of ECM proteins was not translated into an increased deposition of fibrillar collagen. In support of this observation, we revealed the presence of a pro-ECM degradation activity in our ex vivo cultures of hPCLS, inhibition of which by a metalloproteinase inhibitor resulted in increased collagen deposition in response to TGF-β1 stimulation.Together the data show that an integrated approach of measuring soluble pro-fibrotic markers alongside quantitative SHG-based analysis of fibrillar collagen is a valuable tool for studying pro-fibrotic signalling and testing anti-fibrotic agents.

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.

A Human Cellular Model for Colorectal Anastomotic Repair: The Effect of Localization and Transforming Growth Factor-β1 Treatment on Collagen Deposition and Biomarkers

Anastomotic leakage (AL) is a devastating complication after colorectal surgery, possibly due to the loss of stabilizing collagen fibers in the submucosa. Our aim was to assess the formation of collagen in the colon versus the rectum with or without transforming growth factor (TGF)-β1 exposure in a human cellular model of colorectal repair. Primary fibroblasts were isolated by an explant procedure from clinically resected tissue rings during anastomosis construction in 19 consecutive colorectal patients who underwent laparoscopy. The cells, identified as fibroblasts by morphologic characteristics and flow cytometry analysis (CD90⁺), were cultured for 8 days and in 12 patients in the presence of 1 ng/mL TGF-β1. Total collagen deposition was measured colorimetrically after Sirius red staining of fixed cell layers, and type I, III, and VI collagen biosynthesis and degradation were specifically determined by the biomarkers PINP, PRO-C3, PRO-C6, and C3M in conditioned media by competitive enzyme-linked immunosorbent assays. Total collagen deposition by fibroblasts from the colon and rectum did not significantly differ. TGF-β1 treatment increased PINP, PRO-C6, and total collagen deposition. Mechanistically, TGF-β1 treatment increased COL1A1 and ACTA2 (encoding α-smooth muscle actin), and decreased COL6A1 and MMP2 mRNA levels in colorectal fibroblasts. In conclusion, we found no effect of anatomic localization on collagen production by fibroblasts derived from the large intestine. TGF-β1 represents a potential therapeutic agent for the prevention of AL by increasing type I collagen synthesis and collagen deposition.

Ginsenoside Rg3 Attenuates Aluminum-Induced Osteoporosis Through Regulation of Oxidative Stress and Bone Metabolism in Rats

Aluminum (Al)-induced bone metabolism disorder is a primary cause of osteoporosis. Ginsenoside Rg3 (Rg3) has demonstrated therapeutic properties in the treatment of osteoporosis. The present study aimed to identify potential bone protection mechanisms of Rg3 against Al-induced osteoporosis in rats. In this study, forty healthy male Sprague-Dawley rats were randomly allocated into groups in which they were treated with AlCl₃ (64 mg/kg/day) and/or Rg3 (20 mg/kg/day). AlCl₃ was given orally to rats for 120 days, and from the 91st day, treated orally with Rg3 for 30 days. Rg3 attenuated AlCl₃-induced accumulation of Al by decreasing the bone mineral density in the lumbar spines, femoral metaphysis, and tibia, and inhibited AlCl₃-induced oxidative stress in rat bone by decreasing the levels of reactive oxygen species and malondialdehyde, while increasing glutathione peroxidase and superoxide dismutase activity. Rg3 facilitated bone formation by increasing the concentration of calcium, phosphorus, amino-terminal propeptide of type I procollagen, and carboxyl-terminal propeptide of type I procollagen, bone alkaline phosphatase activity in serum, and type I collagen, osteocalcin, and osteopontin protein expressions. Rg3 inhibited bone resorption by decreasing the content of N-terminal cross-linking telopeptide of type I collagen, C-terminal cross-linking telopeptide of type I collagen, and tartrate-resistant acid phosphatase 5b activity in serum. Rg3 promoted the mRNA expression of growth regulation factors by increasing transforming growth factor-β1, bone morphogenetic protein-2, insulin-like growth factor I, and core-binding factor α1. The results demonstrate that Rg3 can significantly attenuate Al accumulation, facilitate bone formation, inhibit bone resorption, resist oxidative stress, and promote the expression of factors that regulate growth. The results indicate that Rg3 is effective in alleviating AlCl₃-induced osteoporosis.

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.

Advances in the clinical use of collagen as biomarker of liver fibrosis

INTRODUCTION

Hepatic fibrosis is the excessive synthesis and deposition of extracellular matrix including collagen in the tissue. Chronic liver insult leads to progressive parenchymal damage, portal hypertension, and cirrhosis. Determination of hepatic collagen by invasive liver biopsy is the gold standard to estimate severity and stage of fibrosis. However, this procedure is associated with pain, carries the risk of infection and bleeding, and is afflicted with a high degree of sampling error. Therefore, there is urgent need for serological collagen-derived markers to assess collagen synthesis/turnover.

AREAS COVERED

Biochemical properties of collagens, cellular sources of hepatic collagen synthesis, and regulatory aspects in collagen expression. Markers are discussed suitable to estimate hepatic collagen synthesis and/or turnover. Discussed studies were identified through a PubMed search done in May 2020 and the authors' topic knowledge.

EXPERT OPINION

Hepatic fibrosis is mainly characterized by accumulation of collagen-rich scar tissue. Although traditionally performed liver biopsy is still standard in estimating hepatic fibrosis, there is evidence that noninvasive diagnostic scores and collagen-derived neo-epitopes provide clinical useful information. These noninvasive tests are less expensive than liver biopsy, better tolerated, safer, and more acceptable to patients. Therefore, these tests will lead to dramatic changes in diagnosis.

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.

Collagen biology and non-invasive biomarkers of liver fibrosis

There is an unmet need for high-quality liquid biomarkers that can safely and reproducibly predict the stage of fibrosis and the outcomes of chronic liver disease (CLD). The requirement for such markers has intensified because of the high global prevalence of diseases such as non-alcoholic fatty liver disease (NAFLD). In particular, there is a need for diagnostic and prognostic tools, as well as predictive biomarkers that reflect the efficacy of interventions, as described by the BEST criteria (Biomarkers, EndpointS, and other Tools Resource). This review covers the various liver collagens, their functional role in tissue homeostasis and delineates the common nomenclature for biomarkers based on BEST criteria. It addresses the common confounders affecting serological biomarkers, and describes defined collagen epitope biomarkers that originate from the dynamic processes of extracellular matrix (ECM) remodelling during liver injury.

Collagen turnover profiles in chronic kidney disease

Renal fibrosis is a hallmark of chronic kidney disease (CKD) caused by an imbalance between formation and degradation of extracellular matrix proteins. We investigated the collagen turnover profile of 81 non-dialysis CKD stage 2-5 patients by measuring peptides reflecting formation and degradation of collagen type (COL) I, III, IV, and VI. Based on the collagen turnover profile, we identified four clusters of patients. Cluster 1 contained one patient with prostate cancer, who had a distinct collagen turnover. The other clusters generally had severe (Cluster 2), moderate (Cluster 4), or mild CKD (Cluster 3). Cluster 4 patients were characterized by higher levels of COL III, COL IV, and COL VI (all p < 0.001) degradation fragments in plasma, while patients in Clusters 2 and 4 had higher levels of COL VI formation (p < 0.05). COL IV fragments in plasma were lower in Cluster 2 (p < 0.01). Urinary COL III fragments decreased from Cluster 3 to 4, and from Cluster 4 to 2 (both p < 0.001). We show that patients with similar kidney function have a different collagen remodeling profile, suggesting that different phenotypes exist with different disease activity and potentially disease progression. Biomarkers of collagen remodeling could provide additional information to traditional markers of renal function.

Identification of pathological RA endotypes using blood-based biomarkers reflecting tissue metabolism. A retrospective and explorative analysis of two phase III RA studies

There is an increasing demand for accurate endotyping of patients according to their pathogenesis to allow more targeted treatment. We explore a combination of blood-based joint tissue metabolites (neoepitopes) to enable patient clustering through distinct disease profiles. We analysed data from two RA studies (LITHE (N = 574, follow-up 24 and 52 weeks), OSKIRA-1 (N = 131, follow-up 24 weeks)). Two osteoarthritis (OA) studies (SMC01 (N = 447), SMC02 (N = 81)) were included as non-RA comparators. Specific tissue-derived neoepitopes measured at baseline, included: C2M (cartilage degradation); CTX-I and PINP (bone turnover); C1M and C3M (interstitial matrix degradation); CRPM (CRP metabolite) and VICM (macrophage activity). Clustering was performed to identify putative endotypes. We identified five clusters (A-E). Clusters A and B were characterized by generally higher levels of biomarkers than other clusters, except VICM which was significantly higher in cluster B than in cluster A (p<0.001). Biomarker levels in Cluster C were all close to the median, whilst Cluster D was characterised by low levels of all biomarkers. Cluster E also had low levels of most biomarkers, but with significantly higher levels of CTX-I compared to cluster D. There was a significant difference in ΔSHP score observed at 52 weeks (p<0.05). We describe putative RA endotypes based on biomarkers reflecting joint tissue metabolism. These endotypes differ in their underlining pathogenesis, and may in the future have utility for patient treatment selection.

Biomarkers of collagen synthesis predict progression in the PROFILE idiopathic pulmonary fibrosis cohort

Idiopathic pulmonary fibrosis (IPF) is characterised by excessive extracellular matrix (ECM) deposition and remodelling. Measuring this activity provides an opportunity to develop tools capable of identifying individuals at-risk of progression. Longitudinal change in markers of ECM synthesis was assessed in 145 newly-diagnosed individuals with IPF.Serum levels of collagen synthesis neoepitopes, PRO-C3 and PRO-C6 (collagen type 3 and 6), were elevated in IPF compared with controls at baseline, and progressive disease versus stable disease during follow up, (PRO-C3 p < 0.001; PRO-C6 p = 0.029). Assessment of rate of change in neoepitope levels from baseline to 3 months (defined as 'slope to month 3': HIGH slope, slope > 0 vs. LOW slope, slope < =0) demonstrated no relationship with mortality for these markers (PRO-C3 (HR 1.62, p = 0.080); PINP (HR 0.76, p = 0.309); PRO-C6 (HR 1.14, p = 0.628)). As previously reported, rising concentrations of collagen degradation markers C1M, C3M, C6M and CRPM were associated with an increased risk of overall mortality (HR = 1.84, CI 1.03-3.27, p = 0.038, HR = 2.44, CI 1.39-4.31, p = 0.002; HR = 2.19, CI 1.25-3.82, p = 0.006; HR = 2.13 CI 1.21-3.75, p = 0.009 respectively).Elevated levels of PRO-C3 and PRO-C6 associate with IPF disease progression. Collagen synthesis and degradation biomarkers have the potential to enhance clinical trials in IPF and may inform prognostic assessment and therapeutic decision making in the clinic.

The mTORC1/4E-BP1 axis represents a critical signaling node during fibrogenesis

Myofibroblasts are the key effector cells responsible for excessive extracellular matrix deposition in multiple fibrotic conditions, including idiopathic pulmonary fibrosis (IPF). The PI3K/Akt/mTOR axis has been implicated in fibrosis, with pan-PI3K/mTOR inhibition currently under clinical evaluation in IPF. Here we demonstrate that rapamycin-insensitive mTORC1 signaling via 4E-BP1 is a critical pathway for TGF-β1 stimulated collagen synthesis in human lung fibroblasts, whereas canonical PI3K/Akt signaling is not required. The importance of mTORC1 signaling was confirmed by CRISPR-Cas9 gene editing in normal and IPF fibroblasts, as well as in lung cancer-associated fibroblasts, dermal fibroblasts and hepatic stellate cells. The inhibitory effect of ATP-competitive mTOR inhibition extended to other matrisome proteins implicated in the development of fibrosis and human disease relevance was demonstrated in live precision-cut IPF lung slices. Our data demonstrate that the mTORC1/4E-BP1 axis represents a critical signaling node during fibrogenesis with potential implications for the development of novel anti-fibrotic strategies.

Age-related collagen turnover of the interstitial matrix and basement membrane: Implications of age- and sex-dependent remodeling of the extracellular matrix

The extracellular matrix (ECM) plays a vital role in maintaining normal tissue function. Collagens are major components of the ECM and there is a tight equilibrium between degradation and formation of these proteins ensuring tissue health and homeostasis. As a consequence of tissue turnover, small collagen fragments are released into the circulation, which act as important biomarkers in the study of certain tissue-related remodeling factors in health and disease. The aim of this study was to establish an age-related collagen turnover profile of the main collagens of the interstitial matrix (type I and III collagen) and basement membrane (type IV collagen) in healthy men and women. By using well-characterized competitive ELISA-assays, we assessed specific fragments of degraded (C1M, C3M, C4M) and formed (PINP, Pro-C3, P4NP7S) type I, III and IV collagen in serum from 617 healthy men and women ranging in ages from 22 to 86. Subjects were divided into 5-year age groups according to their sex and age. Groups were compared using Kruskal-Wallis adjusted for Dunn's multiple comparisons test and Mann-Whitney t-test. Age-specific changes in collagen turnover was most profound for type I collagen. PINP levels decreased in men with advancing age, whereas in women, the level decreased in early adulthood followed by an increase around the age of menopause (age 40-60). Sex-specific changes in type I, III and IV collagen turnover was present at the age around menopause (age 40-60) with women having an increased turnover. In summary, collagen turnover is affected by age and sex with the interstitial matrix and the basement membrane being differently regulated. The observed changes needs to be accounted for when measuring ECM related biomarkers in clinical studies.

Matrix Metalloproteinase Mediated Type I Collagen Degradation is an Independent Predictor of Increased Risk of Acute Myocardial Infarction in Postmenopausal Women

Acute myocardial infarction (AMI) is often underdiagnosed in women. It is therefore of interest to identify biomarkers that indicate increased risk of AMI and thereby help clinicians to have additional focus on the difficult AMI diagnosis. Type I Collagen, a component of the cardiac extracellular matrix, is cleaved by matrix metalloproteinases (MMPs) generating the neo-epitope C1M. We investigated the association between serum-C1M and AMI and evaluated whether C1M is a prognostic marker for outcome following AMI. This study is based on The Prospective Epidemiological Risk Factor (PERF) Study including postmenopausal women. 316 out of 5,450 women developed AMI within the follow-up period (14 years, median). A multivariate Cox analysis assessed association between serum-C1M and AMI, and re-infaction or death subsequent to AMI. The risk of AMI increased by 18% (p = 0.03) when serum-C1M was doubled and women in the highest quartile had a 33% increased risk compared to those in the low quartiles (p = 0.025). Serum-C1M was, however not related to reinfarction or death subsequent to AMI. In this study C1M was be an independent risk factor for AMI. Measuring MMP degraded type I collagen could be useful for prediction of increased risk of AMI if replicated in other cohorts.

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.

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.

Tissue turnover of collagen type I, III and elastin is elevated in the PCLS model of IPF and can be restored back to vehicle levels using a phosphodiesterase inhibitor

BACKGROUND

The aim of this study was to develop and validate a model for pulmonary fibrosis, using ex vivo tissue cultures of lungs from bleomycin treated animals, enabling the investigation of fibrosis remodeling using novel biomarkers for the detection of ECM protein fragments. The combination of in vivo and ex vivo models together with ECM remodeling markers may provide a translational tool for screening of potential treatments for IPF.

METHODS

Twenty female Sprague-Dawley rats, twelve weeks of age, were administrated either two doses of bleomycin (BLM) (n = 14) or saline (n = 6) I.T., two days apart. Ten rats were euthanized at day seven and the remaining ten rats at day fourteen, after the last dose. Precision-cut lung slices (PCLS) were made and cultured for 48 h. Ten female Sprague-Dawley rats, twelve weeks of age, were administrated either two doses of BLM (n = 7) or saline (n = 3) I.T., two days apart. The rats were euthanized fourteen days after the last dose. PCLS were made and cultured for 48 h in: medium, medium + 100 μM IBMX (PDE inhibitor), or medium + 10 μM GM6001 (MMP inhibitor). Turnover of type I collagen (P1NP, C1M), type III collagen (iP3NP, C3M) and elastin degradation (ELM7) was measured in the supernatant of the cultured PCLS.

RESULTS

P1NP, C1M, iP3NP, C3M and ELM7 were significantly increased in supernatants from BLM animals (P ≤ 0.05 - P ≤ 0.0001) when compared to controls. P1NP, C1M, iP3NP, C3M and ELM7 were significantly increased in supernatants from day seven BLM animals compared to day fourteen BLM animals (P ≤ 0.05 - P ≤ 0.0001). P1NP, C1M, iP3NP, C3M and ELM7 were significantly decreased when adding IBMX to the culture medium of fibrotic lung tissue (P ≤ 0.05 - P ≤ 0.0001). C1M, C3M and ELM7 were significantly decreased when adding GM6001 to the culture medium (P ≤ 0.05 - P ≤ 0.0001). Sirius Red and Orcein staining confirmed the presence of collagen and elastin deposition in the lungs of the animals receiving BLM.

CONCLUSIONS

The protein fingerprint technology allows the assessment of ECM remodeling markers in the BLM PCLS model. By combining in vivo, ex vivo models and the protein fingerprint technology in the fibrotic phase of the model, we believe the chance of translation from animal model to human is markedly increased.

Precision-Cut Kidney Slices as a Tool to Understand the Dynamics of Extracellular Matrix Remodeling in Renal Fibrosis

The aim of this study was to set up an ex vivo model for renal interstitial fibrosis in order to investigate the extracellular matrix (ECM) turnover profile in the fibrotic kidney. We induced kidney fibrosis in fourteen 12-week-old male Sprague Dawley rats by unilateral ureteral obstruction (UUO) surgery of the right ureter. The left kidney (contralateral) was used as internal control. Six rats were sham operated and used as the control group. Rats were terminated two weeks after the surgery; the kidneys were excised and precision-cut kidney slices (PCKSs) were cultured for five days in serum-free medium. Markers of collagen type I formation (P1NP), collagen type I and III degradation (C1M and C3M), and α-smooth muscle actin (αSMA) were measured in the PCKS supernatants by enzyme-linked immunosorbent assay. P1NP, C1M, C3M, and α-SMA were increased up to 2- to 13-fold in supernatants of tissue slices from the UUO-ligated kidneys compared with the contralateral kidneys (P < 0.001) and with the kidneys of sham-operated animals (P < 0.0001). The markers could also reflect the level of fibrosis in different animals. The UUO PCKS ex vivo model provides a valuable translational tool for investigating the extracellular matrix remodeling associated with renal interstitial fibrosis.

Exploration of a potent PI3 kinase/mTOR inhibitor as a novel anti-fibrotic agent in IPF

Rationale

Idiopathic pulmonary fibrosis (IPF) is the most rapidly progressive and fatal of all fibrotic conditions with no curative therapies. Common pathomechanisms between IPF and cancer are increasingly recognised, including dysfunctional pan-PI3 kinase (PI3K) signalling as a driver of aberrant proliferative responses. GSK2126458 is a novel, potent, PI3K/mammalian target of rapamycin (mTOR) inhibitor which has recently completed phase I trials in the oncology setting. Our aim was to establish a scientific and dosing framework for PI3K inhibition with this agent in IPF at a clinically developable dose.

Methods

We explored evidence for pathway signalling in IPF lung tissue and examined the potency of GSK2126458 in fibroblast functional assays and precision-cut IPF lung tissue. We further explored the potential of IPF patient-derived bronchoalveolar lavage (BAL) cells to serve as pharmacodynamic biosensors to monitor GSK2126458 target engagement within the lung.

Results

We provide evidence for PI3K pathway activation in fibrotic foci, the cardinal lesions in IPF. GSK2126458 inhibited PI3K signalling and functional responses in IPF-derived lung fibroblasts, inhibiting Akt phosphorylation in IPF lung tissue and BAL derived cells with comparable potency. Integration of these data with GSK2126458 pharmacokinetic data from clinical trials in cancer enabled modelling of an optimal dosing regimen for patients with IPF.

Conclusions

Our data define PI3K as a promising therapeutic target in IPF and provide a scientific and dosing framework for progressing GSK2126458 to clinical testing in this disease setting. A proof-of-mechanism trial of this agent is currently underway.

Trial registration number

NCT01725139, pre-clinical.

New frontiers in fibrotic disease therapies: The focus of the Joan and Joel Rosenbloom Center for Fibrotic Diseases at Thomas Jefferson University

Fibrotic diseases constitute a world-wide major health problem, but research support remains inadequate in comparison to the need. Although considerable understanding of the pathogenesis of fibrotic reactions has been attained, no completely effective therapies exist. Although fibrotic disorders are diverse, it is universally appreciated that a particular cell type with unique characteristics, the myofibroblast, is responsible for replacement of functioning tissue with non-functional scar tissue. Understanding the cellular and molecular mechanisms responsible for the creation of myofibroblasts and their activities is central to the development of therapies. Critical signaling cascades, initiated primarily by TGF-β, but also involving other cytokines which stimulate pro-fibrotic reactions in the myofibroblast, offer potential therapeutic targets. However, because of the multiplicity and complex interactions of these signaling pathways, it is very unlikely that any single drug will be successful in modifying a major fibrotic disease. Therefore, we have chosen to examine the effectiveness of administration of several drug combinations in a mouse pneumoconiosis model. Such treatment proved to be effective. Because fibrotic diseases that tend to be chronic, are difficult to monitor, and are patient variable, implementation of clinical trials is difficult and expensive. Therefore, we have made efforts to identify and validate non-invasive biomarkers found in urine and blood. We describe the potential utility of five such markers: (i) the EDA form of fibronectin (Fn(EDA)), (ii) lysyl oxidase (LOX), (iii) lysyl oxidase-like protein 2 (LoxL2), (iv) connective tissue growth factor (CTGF, CCNII), and (v) the N-terminal propeptide of type III procollagen (PIIINP).

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.

Fragments of Citrullinated and MMP-degraded Vimentin and MMP-degraded Type III Collagen Are Novel Serological Biomarkers to Differentiate Crohn's Disease from Ulcerative Colitis

BACKGROUND AND AIMS

A hallmark of inflammatory bowel disease [IBD] is chronic inflammation, which leads to excessive extracellular matrix [ECM] remodelling and release of specific protein fragments, called neoepitopes. We speculated that the biomarker profile panel for ulcerative colitis [UC] and Crohn's disease [CD] represent a heterogeneous expression pattern, and may be applied as a tool to aid in the differentiation between UC and CD.

METHODS

Serum biomarkers of degraded collagens I, III-IV [C1M, C3M, and C4M], collagen type 1 and IV formation [P1NP, P4NP], and citrullinated and MMP-degraded vimentin [VICM] were studied with a competitive ELISA assay system in a cohort including 164 subjects [CD n = 72, UC n = 60, and non-IBD controls n = 32] and a validation cohort of 61 subjects [CD n = 46, and UC n = 15]. Receiver operating characteristic curve analysis and logistic regression modelling were carried out to evaluate the discriminative power of the biomarkers.

RESULTS

All biomarkers were corrected for confounding factors. VICM and C3M demonstrated the highest diagnostic power, alone, to differentiate CD from UC with an area under the curve [AUC] of 0.77 and 0.69, respectively. Furthermore, the biomarkers C1M [AUC = 0.81], C3M [AUC = 0.83], VICM [AUC = 0.83], and P1NP [AUC = 0.77] were best to differentiate UC from non-IBD. The best combinations of biomarkers to differentiate CD from UC and UC from non-IBD were VICM, C3M, C4M [AUC = 0.90] and VICM, C3M [AUC = 0.98] respectively.

CONCLUSIONS

Specific extracellular matrix degradation markers are elevated in IBD and can discriminate CD from UC and UC from non-IBD controls with a high diagnostic accuracy.

Investigating the Robustness and Diagnostic Potential of Extracellular Matrix Remodelling Biomarkers in Alkaptonuria

BACKGROUND AND AIM

Alkaptonuria (AKU) clinical manifestations resemble severe arthritis. The Suitability of Nitisinone in Alkaptonuria 1 (SONIA 1) study is a dose-finding trial for nitisinone treatment of AKU patients. We tested a panel of serum and urinary biomarkers reflecting extracellular matrix remodelling (ECMR) of cartilage, bone and connective tissue in SONIA 1 patients to identify non-invasive and diagnostic biomarkers of tissue turnover in AKU.

METHODS

Fasted serum and urine were retrieved from 40 SONIA 1 patients and 44 healthy controls. Established biomarkers of bone remodelling (CTX-I, P1NP, OC), cartilage remodelling (CTX-II, C2M, AGNx1) and inflammation (CRPM) as well as exploratory biomarkers of ECMR (C6M, VCANM, MIM, TIM) were measured at baseline in serum and urine by means of enzyme-linked immunosorbent assays (ELISAs) or automated systems (Elecsys 2010).

RESULTS

The levels of bone resorption (CTX-I) and cartilage degradation (C2M) were elevated in AKU patients as compared to controls (p > 0.0001 and p = 0.03, respectively). Also tissue inflammation (CRPM) was elevated in AKU patients (p = 0.01). In addition all four exploratory biomarkers of ECMR (C6M, VCANM, MIM, TIM) were elevated in AKU patients compared to healthy controls. CTX-II was the only biomarker to be reduced in AKU patients. TIM was the only marker that showed a higher concentration than the normal assay range in AKU patients.

CONCLUSIONS

We have identified new potential biomarkers for assessment of cartilage, bone and cardiovascular remodelling in AKU and demonstrated the robustness of the assays used to measure the biomarker concentration in biological fluids.

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.

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

OBJECTIVES

Fibrosis is characterized by excessive tissue remodeling resulting from altered expression of various growth factors, cytokines and proteases. We hypothesized that matrix metalloproteinase (MMP) mediated degradation of type IV collagen, a main component of the basement membrane, will release peptide fragments (neo-epitopes) into the circulation. Here we present the development of two competitive enzyme-linked immunosorbent assays (ELISAs) for assessing the levels of specific fragments of type IV collagen α1 (C4M12a1) and α3 (C4M12a3) chains in serum as indicators of fibrosis.

METHODS

Fragments of type IV collagen cleaved in vitro by MMP-12 were identified by mass spectrometry, and two were chosen for ELISA development due to their unique sequences. The assays were evaluated using samples from a carbon tetrachloride (CCl₄) rat model of liver fibrosis and from patients with idiopathic pulmonary fibrosis (IPF) or chronic obstructive pulmonary disease (COPD).

RESULTS

Two technically robust ELISAs were produced using neo-epitope specific monoclonal antibodies. Mean serum C4M12a1 levels were significantly elevated in CCl₄-treated rats compared with controls in weeks 12, 16, and 20, with a maximum increase of 102% at week 16 (p < 0.0001). Further, C4M12a1 levels correlated with the total collagen content of the liver in CCl₄-treated rats (r = 0.43, p = 0.003). Mean serum C4M12a3 levels were significantly elevated in patients with mild, moderate, and severe IPF, and COPD relative to healthy controls, with a maximum increase of 321% in COPD (p < 0.0001).

CONCLUSIONS

Two assays measuring C4M12a1 and C4M12a3 enabled quantification of MMP mediated degradation of type IV collagen in serum. C4M12a1 was elevated in a pre-clinical model of liver fibrosis, and C4M12a3 was elevated in IPF and COPD patients. This suggests the use of these assays to investigate pathological remodeling of the basement membrane in different organs. However, validations in larger clinical settings are needed.

Targeted disruption of leucine-rich repeat kinase 1 but not leucine-rich repeat kinase 2 in mice causes severe osteopetrosis

To assess the roles of Lrrk1 and Lrrk2, we examined skeletal phenotypes in Lrrk1 and Lrrk2 knockout (KO) mice. Lrrk1 KO mice exhibit severe osteopetrosis caused by dysfunction of multinucleated osteoclasts, reduced bone resorption in endocortical and trabecular regions, and increased bone mineralization. Lrrk1 KO mice have lifelong accumulation of bone and respond normally to the anabolic actions of teriparatide treatment, but are resistant to ovariectomy-induced bone boss. Precursors derived from Lrrk1 KO mice differentiate into multinucleated cells in response to macrophage colony-stimulating factor (M-CSF)/receptor activator of NF-κB ligand (RANKL) treatment, but these cells fail to form peripheral sealing zones and ruffled borders, and fail to resorb bone. The phosphorylation of cellular Rous sarcoma oncogene (c-Src) at Tyr-527 is significantly elevated whereas at Tyr-416 is decreased in Lrrk1-deficient osteoclasts. The defective osteoclast function is partially rescued by overexpression of the constitutively active form of Y527F c-Src. Immunoprecipitation assays in osteoclasts detected a physical interaction of Lrrk1 with C-terminal Src kinase (Csk). Lrrk2 KO mice do not show obvious bone phenotypes. Precursors derived from Lrrk2 KO mice differentiate into functional multinucleated osteoclasts. Our finding of osteopetrosis in Lrrk1 KO mice provides convincing evidence that Lrrk1 plays a critical role in negative regulation of bone mass in part through modulating the c-Src signaling pathway in mice.

Acute Myocardial Infarction and Pulmonary Diseases Result in Two Different Degradation Profiles of Elastin as Quantified by Two Novel ELISAs

BACKGROUND

Elastin is a signature protein of the arteries and lungs, thus it was hypothesized that elastin is subject to enzymatic degradation during cardiovascular and pulmonary diseases. The aim was to investigate if different fragments of the same protein entail different information associated to two different diseases and if these fragments have the potential of being diagnostic biomarkers.

METHODS

Monoclonal antibodies were raised against an identified fragment (the ELM-2 neoepitope) generated at the amino acid position '552 in elastin by matrix metalloproteinase (MMP) -9/-12. A newly identified ELM neoepitope was generated by the same proteases but at amino acid position '441. The distribution of ELM-2 and ELM, in human arterial plaques and fibrotic lung tissues were investigated by immunohistochemistry. A competitive ELISA for ELM-2 was developed. The clinical relevance of the ELM and ELM-2 ELISAs was evaluated in patients with acute myocardial infarction (AMI), no AMI, high coronary calcium, or low coronary calcium. The serological release of ELM-2 in patients with chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibrosis (IPF) was compared to controls.

RESULTS

ELM and ELM-2 neoepitopes were both localized in diseased carotid arteries and fibrotic lungs. In the cardiovascular cohort, ELM-2 levels were 66% higher in serum from AMI patients compared to patients with no AMI (p<0.01). Levels of ELM were not significantly increased in these patients and no correlation was observed between ELM-2 and ELM. ELM-2 was not elevated in the COPD and IPF patients and was not correlated to ELM. ELM was shown to be correlated with smoking habits (p<0.01).

CONCLUSIONS

The ELM-2 neoepitope was related to AMI whereas the ELM neoepitope was related to pulmonary diseases. These results indicate that elastin neoepitopes generated by the same proteases but at different amino acid sites provide different tissue-related information depending on the disease in question.

Phosphodiesterase inhibition mediates matrix metalloproteinase activity and the level of collagen degradation fragments in a liver fibrosis ex vivo rat model

Background

Accumulation of extracellular matrix (ECM) and increased matrix metalloproteinase (MMP) activity are hallmarks of liver fibrosis. The aim of the present study was to develop a model of liver fibrosis combining ex vivo tissue culture of livers from CCl₄ treated animals with an ELISA detecting a fragment of type III collagen generated in vitro by MMP-9 (C3M), known to be associated with liver fibrosis and to investigate cAMP modulation of MMP activity and liver tissue turnover in this model.

Findings

In vivo: Rats were treated for 8 weeks with CCl₄/Intralipid. Liver slices were cultured for 48 hours. Levels of C3M were determined in the supernatants of slices cultured without treatment, treated with GM6001 (positive control) or treated with IBMX (phosphodiesterase inhibitor). Enzymatic activity of MMP-2 and MMP-9 were studied by gelatin zymography. Ex vivo: The levels of serum C3M increased 77% in the CCl₄-treated rats at week 8 (p < 0.01); Levels of C3M increased significantly by 100% in fibrotic liver slices compared to controls after 48 hrs (p < 0.01). By adding GM6001 or IBMX to the media, C3M was restored to control levels. Gelatin zymography demonstrated CCl₄-treated animals had highly increased MMP-9, but not MMP-2 activity, compared to slices derived from control animals.

Conclusions

We have combined an ex vivo model of liver fibrosis with measurement of a biochemical marker of collagen degradation in the condition medium. This technology may be used to evaluate the molecular process leading to structural fibrotic changes, as collagen species are the predominant structural part of fibrosis. These data suggest that modulation of cAMP may play a role in regulation of collagen degradation associated with liver fibrosis.