Plasma concentrations of extracellular matrix protein fibulin-1 are related to cardiovascular risk markers in chronic kidney disease and diabetes

Identification of extracellular matrix proteins in plasma as a potential biomarker for intervertebral disc degeneration

PURPOSE

Recently, there has been significant focus on extracellular matrix proteolysis due to its importance in the pathological progression of intervertebral disc degeneration (IVDD). The present study investigates the circulating levels of extracellular matrix proteins in the plasma of IVDD and determines their potential relevance as biomarkers in disc degeneration.

METHODS

Global proteomic analysis was performed in the plasma samples of 10 healthy volunteers (HV) and 10 diseased subjects (DS) after depletion of highly abundant proteins such as albumin and IgG.

RESULTS

We identified 144 and 135 matrix-associated proteins in plasma samples from healthy volunteers (HV) and patients with disc degeneration (DS), respectively. Among these, 49 of the matrix-associated proteins were identical to the proteins found in intervertebral disc (IVD) tissues retrieved from the in-house library. Applying stringent parameters, we selected 28 proteins, with 26 present in DS and 21 in HV. 19 proteins were found common between the groups, two of which-aggrecan (ACAN) and fibulin 1 (FBLN1) - showed statistically significant differences. Specifically, ACAN was up-regulated and FBLN1 was down-regulated in the DS-plasma. In particular, DS-plasma exhibited specific expression of collagen type 2a1 (COL2A1), native to the nucleus pulposus.

CONCLUSION

The distinct presence of collagen type 2a1 and the elevated expression of aggrecan in IVDD plasma may serve as the basis for the development of a potential biomarker for monitoring the progression of disc degeneration.

Recent advances in proteomic analysis to study carotid artery plaques

Objective

We sought to identify differentially expressed proteins in serum, plasma, and plaque samples of patients with carotid atherosclerotic lesions.

Methods

We performed a systematic review of the proteomic profile of serum, plasma, and plaque samples of patients with carotid artery disease. We included full-length peer-reviewed studies of adult humans and reported them using PRISMA guidelines. The quality of the design and content of the articles included in the review was assessed using the Newcastle-Ottawa scale.

Results

We included six peer-reviewed articles reporting protein expression in serum, plasma, or plaque samples from patients with carotid atherosclerosis. Three were single-center cross-sectional studies, two were single-center case-control studies, and one was a single-center cohort study. Thirty-six proteins were found to be expressed differentially when comparing samples from healthy subjects and individuals with diseased carotid vessels and between patients with symptomatic and asymptomatic carotid artery atherosclerotic lesions. Some of these were shown to be related to inflammatory or anti-inflammatory pathways in atherogenesis. CD5L and S100A12 were both found to be upregulated in patients with unstable plaque, the former owing to its anti-inflammatory properties and the latter for its pro-oxidant effects in atherosclerosis. ACTB is involved in cellular structure and integrity and was found to be downregulated in patients with ruptured carotid plaques.

Conclusions

Atherosclerotic carotid disease places the patient at increased risk of ischemic neurological events. Proteomics may help to understand their pathophysiological processes and can identify differential protein expression in blood samples from healthy subjects and patients with carotid artery plaques. This patient-centered approach will allow for the timely identification of individuals at higher risk of experiencing stroke.

Identification of potential shared gene signatures between gastric cancer and type 2 diabetes: a data-driven analysis

Background

Gastric cancer (GC) and type 2 diabetes (T2D) contribute to each other, but the interaction mechanisms remain undiscovered. The goal of this research was to explore shared genes as well as crosstalk mechanisms between GC and T2D.

Methods

The Gene Expression Omnibus (GEO) database served as the source of the GC and T2D datasets. The differentially expressed genes (DEGs) and weighted gene co-expression network analysis (WGCNA) were utilized to identify representative genes. In addition, overlapping genes between the representative genes of the two diseases were used for functional enrichment analysis and protein-protein interaction (PPI) network. Next, hub genes were filtered through two machine learning algorithms. Finally, external validation was undertaken with data from the Cancer Genome Atlas (TCGA) database.

Results

A total of 292 and 541 DEGs were obtained from the GC (GSE29272) and T2D (GSE164416) datasets, respectively. In addition, 2,704 and 336 module genes were identified in GC and T2D. Following their intersection, 104 crosstalk genes were identified. Enrichment analysis indicated that "ECM-receptor interaction," "AGE-RAGE signaling pathway in diabetic complications," "aging," and "cellular response to copper ion" were mutual pathways. Through the PPI network, 10 genes were identified as candidate hub genes. Machine learning further selected BGN, VCAN, FN1, FBLN1, COL4A5, COL1A1, and COL6A3 as hub genes.

Conclusion

"ECM-receptor interaction," "AGE-RAGE signaling pathway in diabetic complications," "aging," and "cellular response to copper ion" were revealed as possible crosstalk mechanisms. BGN, VCAN, FN1, FBLN1, COL4A5, COL1A1, and COL6A3 were identified as shared genes and potential therapeutic targets for people suffering from GC and T2D.

Investigating HMGB1 as a potential serum biomarker for early diabetic nephropathy monitoring by quantitative proteomics

Current diagnostic methods for diabetic nephropathy (DN) lack precision, especially in early stages and monitoring progression. This study aims to find potential biomarkers for DN progression and evaluate their accuracy. Using serum samples from healthy controls (NC), diabetic patients (DM), early-medium stage DN (DN-EM), and late-stage DN (DN-L), researchers employed quantitative proteomics and Mfuzz clustering analysis revealed 15 proteins showing increased expression during DN progression, hinting at their biomarker potential. Combining Mfuzz clustering with weighted gene co-expression network analysis (WGCNA) highlighted five candidates (HMGB1, CD44, FBLN1, PTPRG, and ADAMTSL4). HMGB1 emerged as a promising biomarker, closely correlated with renal function changes. Experimental validation supported HMGB1's upregulation under high glucose conditions, reinforcing its potential as an early detection biomarker for DN. This research advances DN understanding and identifies five potential biomarkers, notably HMGB1, as a promising early monitoring target. These findings set the stage for future clinical diagnostic applications in DN.

Age prediction from human blood plasma using proteomic and small RNA data: a comparative analysis

Aging clocks, built from comprehensive molecular data, have emerged as promising tools in medicine, forensics, and ecological research. However, few studies have compared the suitability of different molecular data types to predict age in the same cohort and whether combining them would improve predictions. Here, we explored this at the level of proteins and small RNAs in 103 human blood plasma samples. First, we used a two-step mass spectrometry approach measuring 612 proteins to select and quantify 21 proteins that changed in abundance with age. Notably, proteins increasing with age were enriched for components of the complement system. Next, we used small RNA sequencing to select and quantify a set of 315 small RNAs that changed in abundance with age. Most of these were microRNAs (miRNAs), downregulated with age, and predicted to target genes related to growth, cancer, and senescence. Finally, we used the collected data to build age-predictive models. Among the different types of molecules, proteins yielded the most accurate model (R² = 0.59 ± 0.02), followed by miRNAs as the best-performing class of small RNAs (R² = 0.54 ± 0.02). Interestingly, the use of protein and miRNA data together improved predictions (R2 = 0.70 ± 0.01). Future work using larger sample sizes and a validation dataset will be necessary to confirm these results. Nevertheless, our study suggests that combining proteomic and miRNA data yields superior age predictions, possibly by capturing a broader range of age-related physiological changes. It will be interesting to determine if combining different molecular data types works as a general strategy to improve future aging clocks.

Fibulin7 aggravates calcium oxalate-induced acute kidney injury by binding to calcium oxalate crystals

Fibulin7 (Fbln7) is a matricellular protein that is structurally similar to short fibulins but does not possess elastogenic abilities. Fbln7 is localized on the cell surface of the renal tubular epithelium in the adult kidney. We previously reported that Fbln7 binds artificial calcium phosphate particles in vitro, and that heparin counteracts this binding by releasing Fbln7 from the cell surface. Fbln7 gene (Fbln7) deletion in vivo decreased interstitial fibrosis and improved renal function in a high phosphate diet-induced chronic kidney disease mouse model. However, the contribution of Fbln7 during acute injury response remains largely unknown. We hypothesized that Fbln7 serves as an exacerbating factor in acute kidney injury (AKI). We employed three AKI models in vivo and in vitro, including unilateral ureteral obstruction (UUO), cisplatin-induced AKI, and calcium oxalate (CaOx)-induced AKI. Here, we report that Fbln7KO mice were protected from kidney damage in a CaOx-induced AKI model. Using HEK293T cells, we found that Fbln7 overexpression enhanced the CaOx-induced upregulation of EGR1 and LAMB3, and that heparin treatment canceled this effect. Interestingly, the protective function observed in Fbln7KO kidneys was limited to the CaOx-induced AKI model, while Fbln7KO mice were not protected against UUO-induced renal fibrosis or cisplatin-induced renal tubular damage. Taken together, our study indicates that Fbln7 mediates the local deposition of CaOx and damages the renal tubular epithelium. Releasing Fbln7 from the cell surface via heparin/heparin derivatives or Fbln7 inhibitory antibodies may provide a general strategy to mitigate calcium crystal-induced kidney injuries.

Blood plasma proteome alteration after local tissue damage induced by Bothrops erythromelas snake venom in mice

Snakes of the genus Bothrops are responsible the most snakebites in the Brazil, causing a diverse and complex pathophysiological condition. Bothrops erythromelas is the main specie of medical relevance found in the Caatinga from the Brazilian Northeast region. The pathophysiological effects involving B. erythromelas snakebite as well as the organism reaction in response to this envenomation are not so explored. Thus, edema was induced in mice paws using 2.5 μg or 5.0 μg of B. erythromelas venom, and the percentage of edema was measured. Plasma was collected 30  minutes after the envenomation-induced in mice and analyzed by mass spectrometry. It was identified a total of 112 common plasma proteins differentially abundant among experimental groups, which are involved with the complement system and coagulation cascades, oxidative stress, neutrophil degranulation, platelets degranulation and inflammatory response. Apolipoprotein A1 (Apoa), serum amyloid protein A-4 (Saa4), adiponectin (Adipoq) showed up-regulated in mice plasma after injection of venom, while fibulin (Fbln1), factor XII (F12) and vitamin K-dependent protein Z (Proz) showed down-regulated. The results indicate a protein pattern of thrombo-inflammation to the B. erythromelas snakebite, evidencing potential biomarkers for monitoring this snakebite, new therapeutic targets and its correlations with the degree of envenomation once showed modulations in the abundance among the different groups according to the amount of venom injected into the mice.

Extracellular Matrix Stiffness in Lung Health and Disease

The extracellular matrix (ECM) provides structural support and imparts a wide variety of environmental cues to cells. In the past decade, a growing body of work revealed that the mechanical properties of the ECM, commonly known as matrix stiffness, regulate the fundamental cellular processes of the lung. There is growing appreciation that mechanical interplays between cells and associated ECM are essential to maintain lung homeostasis. Dysregulation of ECM-derived mechanical signaling via altered mechanosensing and mechanotransduction pathways is associated with many common lung diseases. Matrix stiffening is a hallmark of lung fibrosis. The stiffened ECM is not merely a sequelae of lung fibrosis but can actively drive the progression of fibrotic lung disease. In this article, we provide a comprehensive view on the role of matrix stiffness in lung health and disease. We begin by summarizing the effects of matrix stiffness on the function and behavior of various lung cell types and on regulation of biomolecule activity and key physiological processes, including host immune response and cellular metabolism. We discuss the potential mechanisms by which cells probe matrix stiffness and convert mechanical signals to regulate gene expression. We highlight the factors that govern matrix stiffness and outline the role of matrix stiffness in lung development and the pathogenesis of pulmonary fibrosis, pulmonary hypertension, asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. We envision targeting of deleterious matrix mechanical cues for treatment of fibrotic lung disease. Advances in technologies for matrix stiffness measurements and design of stiffness-tunable matrix substrates are also explored. © 2022 American Physiological Society. Compr Physiol 12:3523-3558, 2022.

Dynamic molecular choreography induced by traffic exposure: A randomized, crossover trial using multi-omics profiling

The biological mechanism of adverse health outcomes related to exposure to traffic-related air pollution (TRAP) needs elucidation. We conducted a randomized, crossover trial among healthy young students in Shanghai, China. Participants wore earplugs and were randomly assigned to a 4-hour walking treatment either along a traffic-polluted road or through a traffic-free park. We conducted untargeted analyses of plasma exosome transcriptomics, serum mass spectrometry-based proteomics, and serum metabolomics to evaluate changes in genome-wide transcription, protein, and metabolite profiles in 35 randomly selected participants. Mean personal exposure levels of ultrafine particles, black carbon, nitrogen dioxide, and carbon monoxide in the road were 2-3 times higher than that in the park. We observed 3449 exosome mRNAs, 58 serum proteins, and 128 serum metabolites that were significantly associated with TRAP. The multi-omics analysis showed dozens of regulatory pathways altered in response to TRAP, such as inflammation, oxidative stress, coagulation, endothelin-1 signaling, and renin-angiotensin signaling. We found that several novel pathways activated in response to TRAP exposure: growth hormone signaling, adrenomedullin signaling, and arachidonic acid metabolism. Our study served as a demonstration and proof of concept on the evidence that associated TRAP exposure with global molecular changes based on the multi-omics level.

Autocrine Exosomal Fibulin-1 as a Target of MiR-1269b Induces Epithelial–Mesenchymal Transition in Proximal Tubule in Diabetic Nephropathy

Background: Diabetic nephropathy (DN) is an increasing threat to human health and is regarded to be the leading cause of end-stage renal disease worldwide. Exosomes deliver biomolecule massages and may play a key role in cell communication and the progression of DN.

Methods: A cross-disciplinary study, including in vivo, in vitro, and human studies, was conducted to explore the cross-talk within proximal tubular epithelial cells (PTECs) in DN. Exosomal protein from PTECs treated with high glucose (HG) was purified and examined using liquid chromatography–tandem mass spectrometry (LC-MS/MS). Next-generation sequencing (NGS) was utilized to analyze RNAs extracted from PTECs from a type 2 diabetic patient and a normal individual. HK-2 cells were used to assess exosomal protein and its modulation and biofunction in DN. Normal individuals and type 2 diabetic patients were enrolled, and nondiabetic db/m mice and diabetic db/db mice were used to validate the molecular mechanism of exosomes in DN.

Results: HG stimulated PTECs to increase Fibulin-1 (FBLN1) expression, and PTECs secreted FBLN1 through exosome delivery, thereby inducing epithelial–mesenchymal transition (EMT) in PTECs. Transcriptome analysis found that FBLN1 expression was modulated by miR-1269b, which was downregulated by HG in HK-2 cells. While transfection of miR-1269b reversed FBLN1-mediated EMT in PTECs, miR-1269b inhibitor modulated the phenotype of PTECs toward mesenchymal type under normal glucose (NG) condition. Most importantly, urinary FBLN1 and exosomal miR-1269b levels were correlated with the severity of kidney injury in type 2 diabetic patients.

Conclusion: This study demonstrated the communication within PTECs through exosome transmission in an autocrine pattern. MiR-1269b–FBLN1 epigenetic regulatory network could be a potential therapeutic strategy to prevent the progression of DN.

Plasma fibulin-1 levels during pregnancy and delivery: a longitudinal observational study

Background

Fibulin-1 is an extracellular matrix protein expressed at high levels in the placenta. Elevated circulating fibulin-1 have been observed in women with severe pre-eclampsia, whereas low levels have been found in the fetal membranes, prior to membrane rupture. The aim of the study was primarily to evaluate plasma fibulin-1 during expected normal pregnancy and delivery, and secondarily to explore fibulin-1 levels in women developing pre-eclampsia or preterm premature rupture of fetal membranes (PPROM).

Methods

From the historical longitudinal cohort originally consisting of 801 healthy Danish women with a singleton pregnancy, 128 women (632 samples) were selected. Of these, 107 women had normal pregnancies, nine experienced PPROM, and 12 pre-eclampsia. All samples were analyzed for fibulin-1, and levels were compared with blood donors. Differences in mean fibulin-1 between groups were estimated using a linear mixed model.

Results

The mean concentration of fibulin-1 in 120 blood donors was 15.7 µg/mL, (25th-75th-percentiles, 12.3–18.2), with no significant difference in groups stratified by gender or age. Compared to baseline levels in week 12–20, fibulin-1 levels increased significantly from week 29–34 (estimated difference, 5.6 µg/mL; standard error, 1.7; p < 0.001) and 35–42 (12.5 µg/mL; 1.6; p < 0.001) and normalized after birth. The decrease at delivery tended to be more pronounced after elective (-7.0 µg/mL; 2.3; p = 0.002) and emergency (-5.6 µg/mL; 2.9; p = 0.05) cesarean section than after vaginal delivery (reference group). Women who developed PPROM had lower fibulin-1 levels throughout their pregnancies (-11.6 µg/mL; 4.2; p = 0.006). We did not observe a correlate between late pre-eclampsia and fibulin-1 (-0.2 µg/mL; 3.0; p = 0.9).

Conclusions

Fibulin-1 was above non-pregnant levels at week 12 and increased significantly throughout pregnancy. We observed an association between low levels of fibulin-1 and PPROM. Further studies are needed to examine if fibulin-1 could serve as biomarker for the risk of PPROM. However, its role in late preeclampsia is doubtful.

Trial registration

The study was conducted in accordance with the Declaration of Helsinki. The participants provided written informed consent, including storage for future use. The study was approved on July 18, 2005 by The Danish National Committee on Bioethics (No. KA 05065 and S-20,090,061) and the Danish Data Protection Agency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04110-y.

Analysis of genes associated with proinflammatory and profibrotic pathways upregulated in ischemia-induced chronic kidney disease in cats

OBJECTIVE

To use RNA sequencing (RNAseq) to characterize renal transcriptional activities of genes associated with proinflammatory and profibrotic pathways in ischemia-induced chronic kidney disease (CKD) in cats.

SAMPLES

Banked renal tissues from 6 cats with experimentally induced CKD (renal ischemia [RI] group) and 9 healthy cats (control group).

PROCEDURES

Transcriptome analysis with RNAseq, followed by gene ontology and cluster analyses, were performed on banked tissue samples of the right kidneys (control kidneys) from cats in the control group and of both kidneys from cats in the RI group, in which unilateral (right) RI had been induced 6 months before the cats were euthanized and the ischemic kidneys (IKs) and contralateral nonischemic kidneys (CNIKs) were harvested. Results for the IKs, CNIKs, and control kidneys were compared to identify potential differentially expressed genes and overrepresented proinflammatory and profibrotic pathways.

RESULTS

Genes from the gene ontology pathways of collagen binding (eg, transforming growth factor-β1), metalloendopeptidase activity (eg, metalloproteinase [MMP]-7, MMP-9, MMP-11, MMP-13, MMP-16, MMP-23B, and MMP-28), chemokine activity, and T-cell migration were overrepresented as upregulated in tissue samples of the IKs versus control kidneys. Genes associated with the extracellular matrix (eg, TIMP-1, fibulin-1, secreted phosphoprotein-1, matrix Gla protein, and connective tissue growth factor) were upregulated in tissue samples from both the IKs and CNIKs, compared with tissues from the control kidneys.

CONCLUSIONS AND CLINICAL RELEVANCE

Unilateral ischemic injury differentially altered gene expression in both kidneys, compared with control kidneys. Fibulin-1, secreted phosphoprotein-1, and matrix Gla protein may be candidate biomarkers of active kidney injury in cats.

Identification of Lumican and Fibromodulin as Hub Genes Associated with Accumulation of Extracellular Matrix in Diabetic Nephropathy

INTRODUCTION

Diabetic nephropathy (DN) remains a major cause of end-stage renal disease. The development of novel biomarkers and early diagnosis of DN are of great clinical importance. The goal of this study was to identify hub genes with diagnostic potential for DN by weighted gene co-expression network analysis (WGCNA).

METHODS

Gene Expression Omnibus database was searched for microarray data including distinct types of CKD. Gene co-expression network was constructed, and modules specific for DN were identified by WGCNA. Gene ontology (GO) analysis was performed, and the hub genes were screened out within the selected gene modules. In addition, cross-validation was performed in an independent dataset and in samples of renal biopsies with DN and other types of glomerular diseases.

RESULTS

Dataset GSE99339 was selected, and a total of 179 microdissected glomeruli samples were analyzed, including DN, normal control, and 7 groups of other glomerular diseases. Twenty-three modules of the total 10,947 genes were grouped by WGCNA, and a module was specifically correlated with DN (r = 0.54, p = 9e-15). GO analysis showed that module genes were mainly enriched in the accumulation of extracellular matrix (ECM). LUM, ELN, FBLN1, MMP2, FBLN5, and FMOD were identified as hub genes. Cross verification showed LUM and FMOD were higher in the DN group and were negatively correlated with estimated glomerular filtration rate (eGFR). In renal biopsies, expression levels of LUM and FMOD were higher in DN than IgA nephropathy, membranous nephropathy, and normal controls.

CONCLUSION

By using WGCNA approach, we identified LUM and FMOD related to ECM accumulation and were specific for DN. These 2 genes may represent potential candidate diagnostic biomarkers of DN.

Relationship between the Plasma Fibulin-1 Levels, Pulse Wave Velocity, and Vascular Age in Asymptomatic Hyperuricemia

Fibulin-1 (FBLN-1), an elastin-associated extracellular matrix protein, has been found in blood and may play a role in the pathophysiological processes leading to cardiovascular disease (CVD). We aimed to investigate the relationship between fibulin-1 levels and the risk of CVD by evaluating vascular age derived from the Framingham Heart Study and brachial-ankle Pulse Wave Velocity (baPWV) in patients with asymptomatic hyperuricemia (AHU). In total, 66 patients with AHU and 66 gender- and age-matched healthy individuals were enrolled. The plasma fibulin-1 levels were measured by immunochemistry. Patients with AHU presented significantly higher vascular age [median (interquartile range): 54 (22) vs. 48 (14) years, P=0.01] and baPWV [mean±SD: 1373±223 vs. 1291±177 cm/s, P=0.02] than the healthy subjects; however, no significant difference was observed in the plasma fibulin-1 level between the patients with AHU and healthy subjects [median (interquartile range): 4018 (3838) vs. 3099 (3405) ng/mL, P=0.31]. A correlation between fibulin-1 levels and baPWV was observed only in patients with AHU (r=0.29, P=0.02); and there was also a suggestively statistically significant correlation between fibulin-1 levels and vascular age (r=0.22, P=0.08). However, these associations were rendered insignificant after adjustments for potential confounders. In healthy subjects, no correlation was observed between fibulin-1 levels and CVD risk. This study reveals that plasma fibulin-1 levels may reflect the CVD risk in patients with AHU, but the relationship is not robust.

Regulation of cellular senescence by extracellular matrix during chronic fibrotic diseases

The extracellular matrix (ECM) is a complex network of macromolecules surrounding cells providing structural support and stability to tissues. The understanding of the ECM and the diverse roles it plays in development, homoeostasis and injury have greatly advanced in the last three decades. The ECM is crucial for maintaining tissue homoeostasis but also many pathological conditions arise from aberrant matrix remodelling during ageing. Ageing is characterised as functional decline of tissue over time ultimately leading to tissue dysfunction, and is a risk factor in many diseases including cardiovascular disease, diabetes, cancer, dementia, glaucoma, chronic obstructive pulmonary disease (COPD) and fibrosis. ECM changes are recognised as a major driver of aberrant cell responses. Mesenchymal cells in aged tissue show signs of growth arrest and resistance to apoptosis, which are indicative of cellular senescence. It was recently postulated that cellular senescence contributes to the pathogenesis of chronic fibrotic diseases in the heart, kidney, liver and lung. Senescent cells negatively impact tissue regeneration while creating a pro-inflammatory environment as part of the senescence-associated secretory phenotype (SASP) favouring disease progression. In this review, we explore and summarise the current knowledge around how aberrant ECM potentially influences the senescent phenotype in chronic fibrotic diseases. Lastly, we will explore the possibility for interventions in the ECM-senescence regulatory pathways for therapeutic potential in chronic fibrotic diseases.

Changes in the plasma microvesicle proteome during the ovarian hyperstimulation phase of assisted reproductive technology

The incidence of pulmonary and venous thromboembolism is increased during the first trimester of pregnancies after assisted reproductive technology (ART) compared to spontaneous conception. We previously found that haemostatic plasma variables changed but within normal limits during controlled ovarian hyperstimulation (COH) concomitant with a major increase in plasma microvesicles (MVs) and markers indicating cell activation. We now explored the proteome of these MVs. Thirty-one women undergoing ART were blood sampled at down-regulation (DR) of oestrogen and at high level stimulation (HLS) with its 10–100-fold increased oestrogen level. Samples were analysed by liquid chromatography and tandem mass spectrometry to identify and quantify the proteome. We identified 306 proteins in the MVs and 72 had changed significantly at HLS compared to DR and more than 20% of them were associated with haemostasis. Thus, proteins related to both haemostasis and complement activation altered in plasma MVs in parallel with MV activation during COH. This needs to be further explored in the clinical context.

Association of Proteins Modulating Immune Response and Insulin Clearance During Gestation with Antenatal Complications in Patients with Gestational or Type 2 Diabetes Mellitus

Background: The purpose of the study is to establish and quantitatively assess protein markers and their combination in association with insulin uptake that may be have value for early prospective recognition of diabetic fetopathy (DF) as a complication in patients with diabetes mellitus during gestation. Methods: Proteomic surveying and accurate quantitative measurement of selected proteins from plasma samples collected from the patients with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) who gave birth of either healthy or affected by maternal diabetes newborns was performed using mass spectrometry. Results: We determined and quantitatively measured several proteins, including CRP, CEACAM1, CNDP1 and Ig-family that were significantly differed in patients that gave birth of newborns with signs of DF. We found that patients with newborns associated with DF are characterized by significantly decreased CEACAM1 (113.18 ± 16.23 ng/mL and 81.09 ± 10.54 ng/mL in GDM and T2DM, p < 0.005) in contrast to control group (515.6 ± 72.14 ng/mL, p < 0.005). On the contrary, the concentration of CNDP1 was increased in DF-associated groups and attained 49.3 ± 5.18 ng/mL and 37.7 ± 3.34 ng/mL (p < 0.005) in GDM and T2DM groups, respectively. Among other proteins, dramatically decreased concentration of IgG4 and IgA2 subclasses of immunoglobulins were noticed. Conclusion: The combination of the measured markers may assist (AUC = 0.893 (CI 95%, 0.785–0.980) in establishing the clinical finding of the developing DF especially in patients with GDM who are at the highest risk of chronic insulin resistance.

A novel single amino acid deletion impairs fibronectin function and causes familial glomerulopathy with fibronectin deposits: case report of a family

Background

Glomerulopathy with fibronectin deposits is an autosomal dominant disease associated with proteinuria, hematuria, hypertension and renal function decline. Forty percent of the cases are caused by mutations in FN1, the gene that encodes fibronectin.

Case presentation

This report describes two cases of Glomerulopathy with fibronectin deposits, involving a 47-year-old father and a 14-year-old son. The renal biopsies showed glomeruli with endocapillary hypercellularity and large amounts of mesangial and subendothelial eosinophilic deposits. Immunohistochemistry for fibronectin was markedly positive. Whole exome sequencing identified a novel FN1 mutation that leads to an amino-acid deletion in both patients (Ile1988del), a variant that required primary amino-acid sequence analysis for assessment of pathogenicity. Our primary sequence analyses revealed that Ile1988 is very highly conserved among relative sequences and is positioned in a C-terminal FN3 domain containing heparin- and fibulin-1-binding sites. This mutation was predicted as deleterious and molecular mechanics simulations support that it can change the tertiary structure and affect the complex folding and its molecular functionality.

Conclusion

The current report not only documents the occurrence of two GFND cases in an affected family and deeply characterizes its anatomopathological features but also identifies a novel pathogenic mutation in FN1, analyzes its structural and functional implications, and supports its pathogenicity.

Nanodiamond for Sample Preparation in Proteomics

Protein analysis of potential disease markers in blood is complicated by the fact that proteins in plasma show very different abundances. As a result, high-abundance proteins dominate the analysis, which often render the analysis of low-abundance proteins impossible. Depleting high-abundance proteins is one strategy to solve this problem. Here, we present, for the first time, a very simple approach based on selective binding of serum proteins to the surface of nanodiamonds. In our first proof-of-principle experiments, we were able to detect, on average, eight proteins that are present at a concentration of 1 ng/mL (instead of 0.5 ng/mL in the control without sample preparation). Remarkably, we detect proteins down to a concentration of 400 pg/mL after only one simple depletion step. Among the proteins we could analyze are also numerous disease biomarkers, including markers for multiple cancer forms, cardiovascular diseases, or Alzheimer's disease. Remarkably, many of the biomarkers we find also could not be detected with a state-of-the-art ultrahigh-performance liquid chromatography column (which depletes the 64 most-abundant serum proteins).

Increased fibulin-1 plasma levels in polycystic ovary syndrome (PCOS) patients: possible contribution to the link between PCOS and cardiovascular risk

PURPOSE

To investigate a possible relation between fibulin-1 plasma levels and PCOS.

DESIGN

ELISA quantitative determination of human fibulin-1.

METHODS

50 women with PCOS and 40 control patients who attended the Unit of Human Reproductive Pathophysiology, Università Cattolica del Sacro Cuore, Rome, were enrolled. Ultrasonographic pelvic examinations, hormonal profile assays, oral tolerance test OGTT, lipid profile and ELISA quantitative determination of human fibulin-1 were performed.

RESULTS

Fibulin-1 levels were found to be statistically significantly higher in PCOS patients than in matched control women. No statistically significant positive correlation was found between fibulin-1 and AUCi, HOMA-IR, total cholesterol, LDL, AMH, androstenedione and FAI, whereas a statistically significant positive correlation was found between fibulin-1 and 17OHP (p = 0.016) in the PCOS group. However, multivariable linear regression analysis showed that 17 OH P did not independently predict fibulin-1 levels (p = 0.089).

CONCLUSIONS

Our data could contribute to explain the hypothesized increased cardiovascular risk and vascular damage in patients with PCOS. A better understanding of the cellular and molecular mechanisms involved in cardiometabolic disorders associated with PCOS is mandatory to identify new therapeutic strategies to eventually prevent the progression of cardiovascular diseases in these patients.

The matrix proteins aggrecan and fibulin-1 play a key role in determining aortic stiffness

Stiffening of the aorta is an important independent risk factor for myocardial infarction and stroke. Yet its genetics is complex and little is known about its molecular drivers. We have identified for the first time, tagSNPs in the genes for extracellular matrix proteins, aggrecan and fibulin-1, that modulate stiffness in young healthy adults. We confirmed SNP associations with ex vivo stiffness measurements and expression studies in human donor aortic tissues. Both aggrecan and fibulin-1 were found in the aortic wall, but with marked differences in the distribution and glycosylation of aggrecan reflecting loss of chondroitin-sulphate binding domains. These differences were age-dependent but the striking finding was the acceleration of this process in stiff versus elastic young aortas. These findings suggest that aggrecan and fibulin-1 have critical roles in determining the biomechanics of the aorta and their modification with age could underpin age-related aortic stiffening.

Is cardiovascular disease in patients with diabetes associated with serum levels of MMP-2, LOX, and the elastin degradation products ELM and ELM-2?

BACKGROUND

Diabetes mellitus type 2 (T2DM) is a significant risk factor for the development of cardiovascular diseases (CVDs). In a previous microarray study of internal mammary arteries from patients with and without T2DM, we observed several elastin-related genes with altered mRNA-expression in diabetic patients, namely matrix metalloproteinase 2 (MMP-2), lysyl oxidase (LOX) and elastin itself. In this study we investigate whether the serum concentrations of elastin-related proteins correlate to signs of CVD in patients with T2DM.

METHODS

Blood samples from 302 type 2 diabetic patients were analysed for MMP-2, LOX, and the elastin degradation products ELM and ELM2. The results were investigated for correlations to signs of CVD in different vascular territories, as determined by myocardial perfusion scintigraphy, carotid artery thickness and ankle-brachial blood pressure index.

RESULTS

T2DM patients with peripheral arterial disease (low ankle-brachial index) (PAD) display higher levels of MMP-2 and ELM compared to patients without PAD. However, none of the proteins or degradation products correlated with myocardial ischemia or a combined measure of CVD-signs, including myocardial ischemia, increased carotid thickness and decreased ankle-brachial blood pressure.

CONCLUSIONS

Our results suggest that the diabetic environment affects the circulating amounts of MMP-2 and ELM in patients with PAD. However, the same connection could not be seen in diabetic patients with CVD broadly identified in three vascular territories. LOX and ELM-2 did not correlate to any type of CVD. Overall, serum levels of elastin-related molecules are only remotely related to CVD in type 2 diabetes.

The serum protein responses to treatment with Xiaoke Pill and Glibenclamide in type 2 diabetes patients

AIM

The Xiaoke Pill containing Chinese herb extracts and Glibenclamide, is used in therapy for type 2 diabetes mellitus (T2DM), and is effective in reducing the risk of hypoglycemia and improving diabetes symptoms compared with Glibenclamide. We describe a quantitative proteomics project to measure the T2DM serum proteome response to the Xiaoke Pill and Glibenclamide.

METHODS

Based on a recently conducted 48-week clinical trial comparing the safety and efficacy of Glibenclamide (n = 400) and Xiaoke Pill (n = 400), after matching for age, sex, BMI, drug dose and whether hypoglycemia occurred, 32 patients were selected for the serum based proteomic analysis and divided into four groups (with/without hypoglycemia treated with Xiaoke Pill or Glibenclamide, n = 8 for each group). We screened the differential serum proteins related to treatments and the onset of hypoglycemia using the iTRAQ labeling quantitative proteomics technique. Baseline and follow-up samples were used.

RESULTS

The quantitative proteomics experiments demonstrated that 25 and 21 proteins differed upon treatment with the Xiaoke Pill in patients without and with hypoglycemia, respectively, while 24 and 25 proteins differed upon treatment with Glibenclamide in patients without and with hypoglycemia, respectively. The overlap of different proteins between the patients with and without hypoglycemia given the same drug treatment was much greater than between the patients given different drug treatments.

CONCLUSIONS

We conclude that the serum proteins response to the two different anti-diabetic drug treatments may serve as a sensitive biomarker for evaluation of the therapeutic effects and continue investigations into the mechanism.

Galectin-3 and fibulin-1 in systolic heart failure - relation to glucose metabolism and left ventricular contractile reserve

Background

Heart failure (HF) patients with diabetes (DM) have an adverse prognosis and reduced functional capacity, which could be associated with cardiac fibrosis, increased chamber stiffness and reduced left ventricular (LV) contractile reserve. Galectin-3 (Gal-3) and fibulin-1 are circulating biomarkers potentially reflecting cardiac fibrosis. We hypothesize that plasma levels of Gal-3 and fibulin-1 are elevated in HF patients with DM and are associated with reduced LV contractile reserve in these patients.

Methods

A total of 155 patients with HF with reduced ejection fraction underwent a low-dose dobutamine echocardiography and blood sampling for biomarker measurements. Patients were classified according to history of DM and an oral glucose tolerance test (OGTT) as: normal glucose tolerance (NGT) (n = 70), impaired glucose tolerance (IGT) (n = 25) and DM (n = 60).

Results

Galectin-3 levels were elevated in DM patients as compared to non-diabetic patients (P = 0.02), while higher fibulin-1 levels were observed in HF patients with IGF and DM (P = 0.07). Reduced LV contractile reserve was associated with increasing Gal-3 levels (β = −0.19, P = 0.03) although, this association was attenuated after adjustment for estimated glomerular filtration rate (P = 0.66). Fibulin-1 was not associated with LV contractile reserve (P = 0.71).

Conclusions

Galectin-3 and fibulin-1 levels were elevated in HF patients with impaired glucose metabolism. However, reduced LV contractile reserve among HF patients with DM does not to have an independent impact on plasma Gal-3 and fibulin-1 levels.

Serum and vitreous fibulin-1 concentrations in patients with diabetic retinopathy

Fibulin-1, an extracellular matrix glycoprotein, is closely correlated with angiogenesis. The purpose of this investigation is to determine serum and vitreous fibulin-1 concentrations in diabetic retinopathy (DR). This cross-sectional investigation was carried out in a population of 154 diabetic patients (54 without DR, 42 with non-proliferative diabetic retinopathy (NPDR) and 58 with proliferative diabetic retinopathy (PDR)) and 49 control subjects. The diabetic group showed higher serum and vitreous fibulin-1 concentrations than the controls. Serum and vitreous fibulin-1 concentrations in PDR patients were significantly elevated compared with those in the other 3 groups. NPDR patients showed elevated levels of serum and vitreous fibulin-1 concentrations compared with patients without DR. Logistic regression analysis revealed that serum and vitreous fibulin-1 were risk factors for developing DR. Pearson correlation analysis showed that serum fibulin-1 was correlated with systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting plasma glucose and vitreous fibulin-1. Furthermore, Pearson correlation analysis showed that vitreous fibulin-1 was correlated with SBP, DBP, high-density lipoprotein cholesterol and serum fibulin-1. Serum and vitreous fibulin-1 concentrations are elevated under DR condition.

Association Between Fibulin-1 and Aortic Augmentation Index in Male Patients with Peripheral Arterial Disease

BACKGROUND

Fibulin-1 (FBLN-1), a newly identified biomarker for vascular stiffness in type 2 diabetes, may participate in the pathophysiological processes leading to progression of arterial stiffness in atherosclerosis. In the present study, the relationship between FBLN-1 and arterial stiffness was examined in patients with atherosclerosis and in healthy subjects.

METHODS

Thirty-eight patients with peripheral arterial disease (PAD) (age 62.4 ± 9.0 years), 38 patients with coronary artery disease (CAD) (age 64.0 ± 9.5 years), and 30 apparently healthy controls (age 61.1 ± 6.4 years) were studied. Serum FBLN-1, oxidized low density lipoprotein (oxLDL), resistin and plasminogen activator inhibitor-1 (PAI-1) levels were measured using the enzyme linked immunosorbent assay method. The technique of applanation tonometry was used for non-invasive pulse wave analysis and pulse wave velocity assessments.

RESULTS

The levels of FBLN-1 (PAD = 9.4 [4.9-17.8] vs. CAD = 7.1 [4.8-11.8] vs. controls = 5.6 [4.1-8.4] μg/mL; p = .005), carotid-femoral pulse wave velocity (cf-PWV) (9.8 ± 2.2 vs. 9.5 ± 2.2 vs. 8.3 ± 2.2 m/s; p = .023) and the heart rate corrected augmentation index (AIx@75) (29.4 ± 7.2 vs. 19.2 ± 7.2 vs. 15.4 ± 7.1%; p < .001), differed among the three groups. A correlation between FBLN-1 and AIx@75 was observed only in patients with PAD (rho = 0.37, p = .021). The relationship retained statistical significance in a multiple regression model after adjustment for potential confounders.

CONCLUSIONS

An independent association was demonstrated between serum FBLN-1 and AIx@75 in the PAD group. Thus, the findings suggest that FBLN-1 may play a role in arterial stiffening in patients with atherosclerosis.

Simvastatin Increases Fibulin-2 Expression in Human Coronary Artery Smooth Muscle Cells via RhoA/Rho-Kinase Signaling Pathway Inhibition

The composition and structure of the extracellular matrix (ECM) in the vascular wall and in the atherosclerotic plaque are important factors that determine plaque stability. Statins can stabilize atherosclerotic plaques by modulating ECM protein expression. Fibulins are important components of the ECM. We evaluated the in vitro effect of simvastatin on the expression of fibulin-1, -2, -4 and -5 in human coronary artery smooth muscle cells (SMCs) and the mechanisms involved. Cells were incubated with simvastatin (0.05–1 μM), mevalonate (100 and 200 μM), geranylgeranyl pyrophosphate (GGPP) (15 μM), farnesyl pyrophosphate (FPP) (15 μM), the Rho kinase (ROCK) inhibitor Y-27632 (15 and 20 μM), the Rac-1 inhibitor (another member of Rho family) NSC23766 (100 μM), arachidonic acid (a RhoA/ROCK activator, 25–100 μM) and other fatty acids that are not activators of RhoA/ROCK (25–100 μM). Gene expression was analyzed by quantitative real-time PCR, and fibulin protein levels were analyzed by western blotting and ELISA. Simvastatin induced a significant increase in mRNA and protein levels of fibulin-2 at 24 hours of incubation (p<0.05), but it did not affect fibulin-1, -4, and -5 expression. Mevalonate and GGPP were able to reverse simvastatin’s effect, while FPP did not. In addition, Y-27632, but not NSC23766, significantly increased fibulin-2 expression. Furthermore, activation of the RhoA/ROCK pathway with arachidonic acid decreased fibulin-2 mRNA. Simvastatin increased mRNA levels and protein expression of the ECM protein fibulin-2 through a RhoA and Rho-Kinase-mediated pathway. This increase could affect the composition and structure of the ECM.

Calumenin and fibulin-1 on tumor metastasis: Implications for pharmacology

Tumor metastasis is a key cause of cancer mortality, and inhibiting migration of cancer cells is one of the major directions of anti-metastatic drug development. Calumenin and fibulin-1 are two extracellular proteins that synergistically inhibit cell migration and tumor metastasis, and could potentially be served as targets for pharmacological research of anti-metastatic drugs. This review briefly introduces the multi-function of these two proteins, and discusses the mechanism of how they regulate cell migration and tumor metastasis.

Fibulin1C peptide induces cell attachment and extracellular matrix deposition in lung fibroblasts

Fibulin-1 is an extracellular matrix (ECM) protein, levels of which are elevated in serum and lung tissue from patients with idiopathic pulmonary fibrosis compared to healthy volunteers. Inhibition of fibulin-1C, one of four fibulin-1 isoforms, reduced proliferation and wound healing in human airway smooth muscle (ASM) cells. This study identified the bioactive region/s of fibulin-1C which promotes fibrosis. Seven fibulin-1C peptides were synthesized and used to pre-coat tissue culture plates before lung derived ASM cells and fibroblasts from patients with pulmonary fibrosis (PF), chronic obstructive pulmonary disease (COPD) or neither disease (Control) were plated. Peptide effects on in vitro measures of fibrosis: cell attachment, proliferation and viability, and ECM deposition, were examined. Among these peptides, peptide 1C1 (FBLN1C1) enhanced ASM cell and fibroblast attachment. FBLN1C1 increased mitochondrial activity and proliferation in fibroblasts. In addition, FBLN1C1 stimulated fibulin1 deposition in PF and COPD fibroblasts, and augmented fibronectin and perlecan deposition in all three groups. Peptides FBLN1C2 to FBLN1C7 had no activity. The active fibulin-1C peptide identified in this study describes a useful tool for future studies. Ongoing investigation of the role of fibulin-1 may reveal the mechanisms underlying the pathphysiology of chronic lung diseases.

Associations between plasma fibulin-1, pulse wave velocity and diabetes in patients with coronary heart disease

BACKGROUND

Diabetes is related to increased risk of cardiovascular disease, and arterial stiffness and its consequences may be the factor connecting the two. Arterial stiffness is often measured by carotid-femoral pulse wave velocity (cf-PWV), but no plasma biomarker reflecting arterial stiffness is available. Fibulin-1 is an extracellular matrix protein, up-regulated in arterial tissue and in plasma in patients with type 2 diabetes. We aimed to evaluate the association between plasma fibulin-1 and arterial stiffness measured by cf PWV in a group of patients with diabetes, and one without, all undergoing coronary artery bypass grafting.

METHODS

Pulse wave velocity (PWV) and pulse wave analysis including augmentation index (Aix75) was measured in 273 patients, who subsequently underwent a coronary by-pass operation. Plasma samples were drawn and information was gathered on diabetes status, HbA1c, lipids, medication, body mass index, co-morbidities and smoking status. Carotid artery intima-media thickness, as well as estimation of carotid artery plaque burden, and distal blood pressure was also obtained.

RESULTS

Sixty three patients had diabetes, and this group had significantly higher levels of plasma fibulin-1, PWV and Aix75, compared to the 210 patients who did not have diabetes. In univariate analysis fibulin-1 and pulse wave velocity were not correlated in either group whereas fibulin-1 in patients without diabetes was correlated to Aix75.

CONCLUSION

Fibulin-1 and arterial stiffness indices are not directly related in patients with cardiac disease, despite the fact that both measures are increased among patients with diabetes.

Total and isoform-specific quantitative assessment of circulating fibulin-1 using selected reaction monitoring MS and time-resolved immunofluorometry

PURPOSE

Targeted proteomics using SRM-MS combined with stable-isotope dilution has emerged as a promising quantitative technique for the study of circulating protein biomarkers. The purpose of this study was to develop and characterize robust quantitative assays for the emerging cardiovascular biomarker fibulin-1 and its circulating isoforms in human plasma.

EXPERIMENTAL DESIGN

We used bioinformatics analysis to predict total and isoform-specific tryptic peptides for absolute quantitation using SRM-MS. Fibulin-1 was quantitated in plasma by nanoflow-LC-SRM-MS in undepleted plasma and time-resolved immunofluorometric assay (TRIFMA). Both methods were validated and compared to a commercial ELISA (CircuLex). Molecular size determination was performed under native conditions by SEC analysis coupled to SRM-MS and TRIFMA.

RESULTS

Absolute quantitation of total fibulin-1, isoforms -1C, and -1D was performed by SRM-MS. Fibulin-1C was the most abundant isoform in plasma. Circulating fibulin-1 isoforms were homo -or hetero multimeric complexes (range 318-364 kDa). Good correlation was obtained between SRM-MS and TRIFMA but not CircuLex.

CONCLUSIONS AND CLINICAL RELEVANCE

For biomarker studies using smaller cohorts, SRM-MS provides an alternative measure of total and specific fibulin-1 isoforms in undepleted plasma. For larger cohorts TRIFMA provides a faster platform for fibulin-1 quantitation in plasma. While the correlation between these methods was acceptable, low correlation was obtained between the commercial CircuLex assay and SRM-MS or TRIFMA.

Fibulins and their role in cardiovascular biology and disease

Fibulins are a group of extracellular matrix proteins of which many are present in high amounts in the cardiovascular system. They share common biochemical properties and are often found in relation to basement membranes or elastic fibers. Observations in humans with specific mutations in fibulin genes, together with results from genetically engineered mice and data from human cardiovascular tissue suggest that the fibulin family of proteins play important functional roles in the cardiovascular system. Moreover, fibulin-1 circulates in high concentrations in plasma and may function as a cardiovascular disease marker.

Extracellular matrix biomarker, fibulin-1, is closely related to NT-proBNP and soluble urokinase plasminogen activator receptor in patients with aortic valve stenosis (the SEAS study)

Background

Fibulin-1, a circulating extracellular matrix glycoprotein, has been associated with arterial disease and elevated N-terminal prohormone B-type natriuretic peptide (NT-proBNP) in diabetes. Soluble urokinase plasminogen activator receptor (suPAR), a marker of inflammation, has been associated with subclinical atherosclerosis. Therefore, we aimed to explore the interplay between these biomarkers and mild to moderate aortic valve stenosis (AS).

Methods

In 374 patients with mild to moderate AS, we investigated the relationship of fibulin-1 with NT-proBNP, levels of suPAR and the degree of AS at baseline and after one and four years of treatment with Simvastatin 40 mg and Ezetimibe 10 mg or placebo.

Results

During treatment, fibulin-1 became more closely associated with NT-proBNP (β_year0 = 0.10, p = 0.08, β_year1 = 0.16, p = 0.005, β_year4 = 0.22, p<0.001) and suPAR (β_year0 = 0.05, p = 0.34, β_year1 = 0.16, p = 0.006, β_year4 = 0.13, p = 0.03) at the expense of the association to aortic valve area index (AVAI) (β_year0 = −0.14, p = 0.005, β_year1 = −0.08, p = 0.11, β_year4 = −0.06, p = 0.22) independently of age, gender, creatinine, and serum aspartate aminotransferase (Adj.R_year0² = 0.19, Adj.R_year1² = 0.22, Adj.R_year4² = 0.27). Fibulin-1 was unrelated to aortic regurgitation, left ventricular mass, and ejection fraction. In patients with baseline AVAI<0.58 cm²/m² (median value), fibulin-1 was more closely associated to NT-proBNP (β_year0 = 0.25, β_year1 = 0.21, β_year4 = 0.22, all p<0.01), and suPAR (β_year0 = 0.09, p = 0.26, β_year1 = 0.23, β_year4 = 0.21, both p<0.01) independently of age, gender, AST and treatment allocation.

Conclusions

Increased levels of fibulin-1 were independently associated with higher levels of suPAR and NT-proBNP especially in patients with lower AVAI, suggesting that fibulin-1 may be an early marker of AS as well as cardiac fibrosis secondarily to elevated left ventricular hemodynamic load.

Expression of fibulin-6 in failing hearts and its role for cardiac fibroblast migration

AIMS

The cardiac extracellular matrix (ECM) undergoes a dynamic transition following myocardial infarction. Fibulin-6 is expressed in cell junctions particularly in tissues subjected to significant mechanical stress. Fibulin-6 deficiency results in defective cell migration in nematodes and early embryonic lethality in mice. The role of fibulin-6 in healthy and failing myocardium is unknown. We have examined the expression and distribution pattern of fibulin-6 during myocardial remodelling (MR) and detailed its effect on the migratory function of cardiac fibroblasts (CFs) in response to TGF-β1.

METHODS AND RESULTS

In healthy murine myocardium, fibulin-6 expression is largely confined to larger coronary arteries. It is induced during the early and the late phase of remodelling after infarction in murine hearts predominantly in the scar-muscle junction. Similar results are obtained in human ischaemic cardiomyopathy. Fibulin-6 is mostly expressed in close vicinity to vimentin-positive cells and is also abundantly expressed in vitro in cultured neonatal CF. TGF-β1 does not induce smooth muscle actin in fibroblasts deficient of fibulin-6, which also compromised their migration. Cells that had migrated expressed more fibulin-6 compared with stationary cells. Plated on fibulin-6-depleted matrix, stress fibre induction in fibroblast in response to TGF-β1 was impaired. In ex vivo explant cultures from post-infarct myocardium, the number of emigrating fibroblasts was also significantly reduced by fibulin-6 siRNA knockdown.

CONCLUSION

Fibulin-6, a fibroblast-released ECM protein, may play an important role during MR by imparting an effect on CF migration in close and complementary interplay with TGF-β1 signalling.

Low-dose spironolactone reduces plasma fibulin-1 levels in patients with type 2 diabetes and resistant hypertension

Diabetic patients with hypertension are at particularly high risk of vascular damage and consequently cardiovascular and renal disease. Fibulin-1, an extracellular matrix glycoprotein, is increased in arterial tissue and plasma from individuals with type 2 diabetes. This study aimed to evaluate whether antihypertensive treatment with spironolactone changes plasma fibulin-1 levels. In a multicenter, double-blind, randomized, placebo-controlled study, 119 patients with type 2 diabetes and resistant hypertension were included. A dose of spironolactone 25 mg or matching placebo was added to previous treatment at randomization. Blood pressure (BP) and plasma fibulin-1 were measured at baseline and at 16 weeks follow-up. Overall, 112 patients completed the study. All measures of BP were reduced in the spironolactone group at follow-up. Plasma fibulin-1 was significantly reduced after spironolactone treatment (P=0.009), but increased after placebo (P=0.017). Baseline plasma fibulin-1 correlated with BP and estimated glomerular filtration rate. Increased levels of plasma fibulin-1 (P=0.004) were observed in diabetic participants reporting erectile dysfunction as compared with participants who did not. Treatment with low-dose spironolactone reduced plasma fibulin-1 levels in patients with type 2 diabetes and resistant hypertension. This supports the hypothesis that the antihypertensive effect of the mineralocorticoid receptor blocker in part may be due to regression of vascular remodeling.

Metformin, but not rosiglitazone, attenuates the increasing plasma levels of a new cardiovascular marker, fibulin-1, in patients with type 2 diabetes

OBJECTIVE The extracellular matrix protein fibulin-1 is upregulated in the arterial wall in type 2 diabetes (T2D) and circulates in increased concentrations in diabetes. Metformin is an antidiabetic drug with beneficial cardiovascular disease effects in diabetes. We hypothesized that metformin would influence the increased level of plasma fibulin-1 in diabetes. RESEARCH DESIGN AND METHODS After a 4-week run-in period, 371 eligible patients with T2D were randomized to treatment groups in a factorial design including insulin alone (control), +metformin, +rosiglitazone, or +both metformin and rosiglitazone. Plasma fibulin-1 was analyzed at the beginning of the study and after 18 and 24 months. RESULTS Plasma fibulin-1 increased in all groups throughout the 2-year period; however, the increase was strongly attenuated among patients treated with metformin. A highly significant difference was observed when the mean change in plasma fibulin-1 was compared between metformin- and non-metformin-treated individuals both at 18 and 24 months of treatment, but rosiglitazone had no effect. Metformin and rosiglitazone alone reduced the HbA1c levels to comparable levels and in combination even further. CONCLUSIONS Metformin attenuates the increase in plasma fibulin-1 concentrations in T2D, independently of glycemic effects. Changes in fibulin-1 may reflect an important element in diabetic arteriopathy that can be influenced by metformin.

Changes in matrix metalloproteinase-9 levels during progression of atrial fibrillation

OBJECTIVES

To observe levels of matrix metalloproteinase (MMP)-9 and evaluate their significance in various stages of idiopathic atrial fibrillation (AF).

METHODS

Patients with idiopathic AF were recruited into this prospective study and classified into one of three groups according to stage of disease progression: paroxysmal AF; persistent AF; permanent AF. Healthy individuals were enrolled as control subjects. Serum levels of MMP-9 in all four groups were determined using a double-antibody sandwich enzyme-linked immunosorbent assay.

RESULTS

Each AF group included 25 patients; 40 healthy individuals were included as controls. MMP-9 levels in the three AF groups were significantly higher than in the control group: 168.72 ± 25.970, 201.36 ± 31.26 and 253.20 ± 22.99 ng/ml for the paroxysmal, persistent and permanent AF groups respectively, versus 76.80 ± 14.90 ng/ml for the control group. MMP-9 levels increased with idiopathic AF disease progression (P < 0.05).

CONCLUSIONS

An elevated MMP-9 level appears to be associated with a diagnosis of AF. MMP-9 levels appear to increase in relation to the stage of idiopathic AF progression.

Dialysis-related transcriptomic profiling: the pivotal role of heparanase

Peritoneal (PD) and hemodialysis (HD) represent the leading renal replacement therapies in advanced chronic kidney disease (CKD). Although absolutely necessary to ensure patient survival, these treatments are responsible for considerable biological alterations primarily due to the un-physiological contact of blood and tissues with bioincompatible devices or plastificants. Although extensively described, this complex dialysis-related deregulated bio-molecular machinery is still not completely known. Therefore, to select a set of genes deregulated in patients on dialysis treatment and to assess the possible differences between dialysis modalities, we measured the expression level of 132 genes involved in proteoglycans (PGs) biosynthesis/metabolism by microarray in peripheral blood mononuclear cells (PBMCs), biological elements involved in the inflammatory/immune response, from 5 healthy subjects (HS), 9 CKD, 10 PD, and 17 HD patients. We focused on PGs biosynthesis/metabolism pathways because of their involvement in the onset and development of several CKD-related clinical complications. Statistical analysis/bioinformatics identified 70 genes discriminating HD/PD patients from HS/CKD subjects (P < 0.009, FDR < 5%). Twenty-five genes were up-regulated (e.g. HPSE, VCAN, and VEGFA) and 45 down-regulated (e.g. IDS and HEXA) in PD/HD compared to HS/CKD. Gene expression and plasma activity of Heparanase (HPSE), one of the top selected up-regulated genes in PD/HD, validated microarray results. In addition, for the second part of the study, HPSE plasmatic activities were first assessed in an independent testing-group (7 HS, 10 CKD, 17 PD, and 11 HD), and then correlated with high-sensitive C reactive protein (HS-CRP) measurements. HPSE activity was higher in PD and HD versus CKD/HS and it correlated with HS-CRP levels (R (2 )= 0.37, P = 0.007). Lipopolysaccharide (LPS)-stimulated PBMCs showed a significant up-regulation of HPSE mRNA level (P = 0.04). Our results revealed that dialysis treatments induce change in the transcriptomic pattern of biosynthetic proteoglycans in PBMCs with an up-regulation of HPSE. Our selected genes could be useful in the future as potential biomarkers and new therapeutic targets.

Plasma levels of the arterial wall protein fibulin-1 are associated with carotid-femoral pulse wave velocity: a cross-sectional study

BACKGROUND

The arterial system in diabetic patients is characterized by generalized non-atherosclerotic alterations in the vascular extracellular matrix causing increased arterial stiffness compared with subjects without diabetes. The underlying pathophysiology remains elusive. The elastin-associated extracellular matrix protein, fibulin-1, was recently found in higher concentrations in the arterial wall and in plasma in patients with long duration type 2 diabetes. Furthermore, plasma fibulin-1 independently predicted total mortality and was associated with pulse pressure, an indirect measure of arterial stiffness. Whether plasma fibulin-1 is associated with arterial stiffness at earlier phases of type 2 diabetes has not been determined.

METHODS

In this cross-sectional study, we examined 90 patients with recently diagnosed type 2 diabetes (< 5 years) and 90 gender- and age-matched controls. Plasma fibulin-1 was measured immunochemically. Arterial stiffness was assessed by carotid-femoral Pulse Wave Velocity (PWV). Differences in means were assessed by t-tests. Associations were assessed by multivariate regression analyses.

RESULTS

Plasma fibulin-1 levels were lower in the diabetic group compared with the control group, 93 ± 28 vs 106 ± 30 μg/mL, p = 0.005. In unadjusted analysis of the total study sample, plasma fibulin-1 was not associated with PWV, p = 0.46. However, with adjustment for the confounders age, gender, mean blood pressure, heart rate, body mass index, diabetes and glomerular filtration rate, a 10 μg/mL increase in plasma fibulin was associated with 0.09 ± 0.04 m/s increase in PWV, p < 0.05. In subgroup analysis, plasma fibulin-1 was associated with PWV in the diabetes group, (0.16 ± 0.07 m/s increase in PWV per 10 μg/mL increase in plasma fibulin-1, p<0.05), but not controls, β = 0.021 ± 0.057 m/s per 10 μg/mL, p = 0.70. The association remained significant in the diabetes group after adjustment for covariates, p < 0.05.

CONCLUSIONS

Plasma fibulin-1 is independently associated with PWV. Yet, as the plasma level of fibulin-1 was lower in patients with recently diagnosed type 2 diabetes than in healthy controls, plasma fibulin-1 levels are not a simple marker of the degree of arterial stiffening. Further studies are needed to determine the exact role of fibulin-1 in arterial stiffness and cardiovascular risk in patients with type 2 diabetes.