Basement Membrane Remodeling Research Articles

Reducing INS-IGF1 signaling protects against non-cell autonomous vesicle rupture caused by SNCA spreading

ABSTRACTAging is associated with a gradual decline of cellular proteostasis, giving rise to devastating protein misfolding diseases, such as Alzheimer disease (AD) or Parkinson disease (PD). These diseases often exhibit a complex pathology involving non-cell autonomous proteotoxic effects, which are still poorly understood. Using Caenorhabditis elegans we investigated how local protein misfolding is affecting neighboring cells and tissues showing that misfolded PD-associated SNCA/α-synuclein is accumulating in highly dynamic endo-lysosomal vesicles. Irrespective of whether being expressed in muscle cells or dopaminergic neurons, accumulated proteins were transmitted into the hypodermis with increasing age, indicating that epithelial cells might play a role in remote degradation when the local endo-lysosomal degradation capacity is overloaded. Cell biological and genetic approaches revealed that inter-tissue dissemination of SNCA was regulated by endo- and exocytosis (neuron/muscle to hypodermis) and basement membrane remodeling (muscle to hypodermis). Transferred SNCA conformers were, however, inefficiently cleared and induced endo-lysosomal membrane permeabilization. Remarkably, reducing INS (insulin)-IGF1 (insulin-like growth factor 1) signaling provided protection by maintaining endo-lysosomal integrity. This study suggests that the degradation of lysosomal substrates is coordinated across different tissues in metazoan organisms. Because the chronic dissemination of poorly degradable disease proteins into neighboring tissues exerts a non-cell autonomous toxicity, this implies that restoring endo-lysosomal function not only in cells with pathological inclusions, but also in apparently unaffected cell types might help to halt disease progression.Abbreviations: AD: Alzheimer disease; BM: basement membrane; BWM: body wall muscle; CEP: cephalic sensilla; CLEM: correlative light and electron microscopy; CTNS-1: cystinosin (lysosomal protein) homolog; DA: dopaminergic; DAF-2: abnormal dauer formation; ECM: extracellular matrix; FLIM: fluorescence lifetime imaging microscopy; fps: frames per second; GFP: green fluorescent protein; HPF: high pressure freezing; IGF1: insulin-like growth factor 1; INS: insulin; KD: knockdown; LMP: lysosomal membrane permeabilization; MVB: multivesicular body; NOC: nocodazole; PD: Parkinson disease; RFP: red fluorescent protein; RNAi: RNA interference; sfGFP: superfolder GFP; SNCA: synuclein alpha; TEM: transmission electron microscopy; TNTs: tunneling nanotubes; TCSPC: time correlated single photon counting; YFP: yellow fluorescent protein.

Temporal characterization of optic fissure basement membrane composition suggests nidogen may be an initial target of remodeling

Fusion of the optic fissure is necessary to complete retinal morphogenesis and ensure proper function of the optic stalk. Failure of this event leads to congenital coloboma, one of the leading causes of pediatric blindness. Mechanistically it is widely accepted that the basement membrane (BM) surrounding the maturing retina needs to be remodeled within the fissure in order to facilitate subsequent epithelial sheet fusion. However, the mechanism driving BM remodeling has yet to be elucidated. As a first step to understanding this critical molecular event we comprehensively characterized the core composition of optic fissure BMs in the zebrafish embryos. Zebrafish optic fissure BMs were found to express laminin a1, a4, b1a, c1 and c3, nidogen 1a, 1b and 2a, collagen IV a1 and a2 as well as perlecan. Furthermore, we observed that laminin, perlecan and collagen IV expression persists in the fissure during fusion, up to 56 hpf, while nidogen expression is downregulated upon initiation of fusion, at 36 hpf. Using immunohistochemistry we also show that nidogen is removed from the BM prior to that of laminin, indicating that remodeling of the BM is an ordered event. Lastly, we characterized retinal morphogenesis in the absence of nidogen function and documented retinal malformation similar to what is observed in laminin mutants. Taken together, we propose a model of BM remodeling where nidogen acts as a linchpin during initiation of optic fissure fusion.

THU-088-Serum markers of interstitial matrix formation (PRO-C3) and basement membrane remodeling (PRO-C4 and C4M) predict recurrence of fibrosis and survival in post-liver transplanted patients

THU-088-Serum markers of interstitial matrix formation (PRO-C3) and basement membrane remodeling (PRO-C4 and C4M) predict recurrence of fibrosis and survival in post-liver transplanted patients

SAT-415-High levels of basement membrane remodelling (C4M) and low activity of wound healing (FPA) reflect fibrosis in alcoholic liver disease

SAT-415-High levels of basement membrane remodelling (C4M) and low activity of wound healing (FPA) reflect fibrosis in alcoholic liver disease

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

BackgroundIdentifying subjects with chronic obstructive pulmonary disease (COPD) at high risk of exacerbation and mortality is key to aid individual management of COPD. The only FDA approved blood-based drug development biomarker for patients at high risk of mortality, is plasma fibrinogen. In this study, we benchmarked two biomarkers of basement membrane remodeling, a characteristic of COPD, against plasma fibrinogen alone and as a combination. The biomarkers of basement membrane remodeling are two neoepitopes from of the alpha 3 chain of type IV collagen (COL4A3).Materials and methodsCOL4A3 degradation was assessed by the biomarkers C4Ma3 and tumstatin (TUM) in year 1 plasma samples in 984 COPD subjects, 95 non-smoking controls and 95 smoking controls from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE) cohort. They were measured by competitive ELISA using monoclonal antibodies recognizing two specific MMP-generated cleavage site within COL4A3. The level of fibrinogen was previously assessed in year 1 plasma.ResultsIn COPD subjects, plasma C4Ma3 levels were significantly correlated with plasma fibrinogen levels (0.389 (P < 0.0001)). Cox proportional-hazards regression adjusted for relevant confounders showed that high levels of plasma C4Ma3, but not TUM, were related to a higher risk of mortality (hazard ratio 5.12 (95% CI 2.28–11.50), P < 0.0001). High levels of plasma fibrinogen were not associated with all-cause mortality in this subpopulation, contradictory to published results. Whereas plasma C4Ma3 multiplied by fibrinogen showed to be related to a higher risk of mortality (hazard ratio 5.74 (95% CI 2.65–12.41), P < 0.0001). Plasma C4Ma3 levels were related to the number of hospitalizations due to COPD exacerbations in the year before study start (P = 0.0375). Fibrinogen levels were related to hospitalized exacerbations prior to study start (P = 0.0058) and were also related to future exacerbations (P < 0.0001).ConclusionWe compared herein fibrinogen, C4Ma3 and TUM as biomarkers for COPD prognosis. Fibrinogen was related to future exacerbation, whereas C4Ma3 and the combination of C4Ma3 with fibrinogen were superior to fibrinogen alone in predicting mortality. This pilot study suggests that the assessment of plasma C4Ma3 could be important for identifying COPD patients with a poor prognosis.Trial registrationNCT00292552, GSK Study No. SCO104960.

Choroid plexus transcriptome and ultrastructure analysis reveals a TLR2-specific chemotaxis signature and cytoskeleton remodeling in leukocyte trafficking

Perinatal infection and inflammation are major risk factors for injury in the developing brain, however, underlying mechanisms are not fully understood. Leukocyte migration to the cerebrospinal fluid (CSF) and brain is a hallmark of many pathologies of the central nervous system including those in neonates. We previously reported that systemic activation of Toll-like receptor (TLR) 2, a major receptor for gram-positive bacteria, by agonist Pam3CSK4 (P3C) resulted in dramatic neutrophil and monocyte infiltration to the CSF and periventricular brain of neonatal mice, an effect that was absent by the TLR4 agonist, LPS. Here we first report that choroid plexus is a route of TLR2-mediated leukocyte infiltration to the CSF by performing flow cytometry and transmission electron microscopy (TEM) of the choroid plexus. Next, we exploited the striking discrepancy between P3C and LPS effects on cell migration to determine the pathways regulating leukocyte trafficking through the choroid plexus. We performed RNA sequencing on the choroid plexus after administration of P3C and LPS to postnatal day 8 mice. A cluster gene analysis revealed a TLR2-specific signature of chemotaxis represented by 80-fold increased expression of the gene Ccl3 and 1000-fold increased expression of the gene Cxcl2. Ingenuity pathway analysis (IPA) revealed TLR2-specific molecular signaling related to cytoskeleton organization (e.g. actin signaling) as well as inositol phospholipids biosynthesis and degradation. This included upregulation of genes such as Rac2 and Micall2. In support of IPA results, ultrastructural analysis by TEM revealed clefting and perforations in the basement membrane of the choroid plexus epithelial cells in P3C-treated mice. In summary, we show that the choroid plexus is a route of TLR2-mediated transmigration of neutrophils and monocytes to the developing brain, and reveal previously unrecognized mechanisms that includes a specific chemotaxis profile as well as pathways regulating cytoskeleton and basement membrane remodeling.

Draxin alters laminin organization during basement membrane remodeling to control cranial neural crest EMT

Premigratory neural crest cells arise within the dorsal neural tube and subsequently undergo an epithelial-to-mesenchymal transition (EMT) to leave the neuroepithelium and initiate migration. Draxin is a Wnt modulator that has been shown to control the timing of cranial neural crest EMT. Here we show that this process is accompanied by three stages of remodeling of the basement membrane protein laminin, from regression to expansion and channel formation. Loss of Draxin results in blocking laminin remodeling at the regression stage, whereas ectopic maintenance of Draxin blocks remodeling at the expansion stage. The latter effect is rescued by addition of Snail2, previously shown to be downstream of Draxin. Our results demonstrate an essential function for the Wnt modulator Draxin in regulating basement membrane remodeling during cranial neural crest EMT.

MiR-203a is differentially expressed during branching morphogenesis and EMT in breast progenitor cells and is a repressor of peroxidasin

MicroRNAs regulate developmental events such as branching morphogenesis, epithelial to mesenchymal transition (EMT) and its reverse process mesenchymal to epithelial transition (MET). In this study, we performed small RNA sequencing of a breast epithelial progenitor cell line (D492), and its mesenchymal derivative (D492M) cultured in three-dimensional microenvironment. Among the most downregulated miRNAs in D492M was miR-203a, a miRNA that plays an important role in epithelial differentiation. Increased expression of miR-203a was seen in D492, concomitant with increased complexity of branching. When miR-203a was overexpressed in D492M, a partial reversion towards epithelial phenotype was seen. Gene expression analysis of D492M and D492MmiR-203a revealed peroxidasin, a collagen IV cross-linker, as the most significantly downregulated gene in D492MmiR-203a. Collectively, we demonstrate that miR-203a expression temporally correlates with branching morphogenesis and is suppressed in D492M. Overexpression of miR-203a in D492M induces a partial MET and reduces the expression of peroxidasin. Furthermore, we demonstrate that miR-203a is a novel repressor of peroxidasin. MiR-203-peroxidasin axis may be an important regulator in branching morphogenesis, EMT/MET and basement membrane remodeling.

Endothelial FN (Fibronectin) Deposition by α5β1 Integrins Drives Atherogenic Inflammation.

Objective- Alterations in extracellular matrix quantity and composition contribute to atherosclerosis, with remodeling of the subendothelial basement membrane to an FN (fibronectin)-rich matrix preceding lesion development. Endothelial cell interactions with FN prime inflammatory responses to a variety of atherogenic stimuli; however, the mechanisms regulating early atherogenic FN accumulation remain unknown. We previously demonstrated that oxLDL (oxidized low-density lipoprotein) promotes endothelial proinflammatory gene expression by activating the integrin α5β1, a classic mediator of FN fibrillogenesis. Approach and Results- We now show that oxLDL drives robust endothelial FN deposition and inhibiting α5β1 (blocking antibodies, α5 knockout cells) completely inhibits oxLDL-induced FN deposition. Consistent with this, inducible endothelial-specific α5 integrin deletion in ApoE knockout mice significantly reduces atherosclerotic plaque formation, associated with reduced early atherogenic inflammation. Unlike TGFβ (transforming growth factor β)-induced FN deposition, oxLDL does not induce FN expression (mRNA, protein) or the endothelial-to-mesenchymal transition phenotype. In addition, we show that cell-derived and plasma-derived FN differentially affect endothelial function, with only cell-derived FN capable of supporting oxLDL-induced VCAM-1 (vascular cell adhesion molecule 1) expression, despite plasma FN deposition by oxLDL. The inclusion of alternative exon EIIIA (EDA) of FN (EIIIA) and alternative exon EIIIB (EDB) of FN (EIIIB) domains in cell-derived FN mediates this effect, as EIIIA/EIIIB knockout endothelial cells show diminished oxLDL-induced inflammation. Furthermore, our data suggest that EIIIA/EIIIB-positive cellular FN is required for maximal α5β1 recruitment to focal adhesions and FN fibrillogenesis. Conclusions- Taken together, our data demonstrate that endothelial α5 integrins drive oxLDL-induced FN deposition and early atherogenic inflammation. Additionally, we show that α5β1-dependent endothelial FN deposition mediates oxLDL-dependent endothelial inflammation and FN fibrillogenesis.

Markers of Basement Membrane Remodeling Are Associated With Higher Mortality in Patients With Known Atherosclerosis.

BackgroundPatients with atherosclerosis have a high risk of cardiovascular events and death. Atherosclerosis is characterized by accumulation of lipids, cells and extracellular matrix proteins in the intima. We hypothesized that dysregulated remodeling of the basement membrane proteins may be associated with clinical outcomes in patients with atherosclerosis.Methods and ResultsNeoepitope fragments of collagen type IV (C4M) and laminin (LG1M) were assessed by ELISAs in serum from 787 endarterectomy patients. Matrix metalloproteinases were measured using proximity extension assay and correlated to C4M and LG1M levels using Spearman correlations. A total of 473 patients were followed up for 6 years using national registers, medical charts, and telephone interviews. The incidence of cardiovascular events, cardiovascular mortality, and all‐cause mortality were associated to levels of C4M and LG1M using Kaplan–Meier curves and Cox regression analyses. A total of 101 patients had cardiovascular events, 39 died of cardiovascular mortality, and 64 patients died from all‐cause mortality. C4M levels were increased in patients with symptomatic carotid atherosclerotic disease before surgery (P=0.048). High C4M and LG1M levels were associated with increased risk of all‐cause mortality (P=0.020 and 0.031, respectively) and predicted all‐cause death together with glomerular filtration rate and diabetes mellitus.ConclusionsHigh LG1M and C4M levels were associated with all‐cause mortality, together with glomerular filtration rate and diabetes mellitus. These novel biomarkers need further evaluation but might be tools to identify high‐risk patients.

A novel biomarker of laminin turnover is associated with disease progression and mortality in chronic kidney disease.

BackgroundPatients with chronic kidney disease (CKD) have increased risk of development of end-stage renal disease (ESRD) and early mortality. Fibrosis is the central pathogenic process in CKD and is caused by dysregulated extracellular matrix (ECM) remodeling. The laminin γ1 chain (LAMC1) is a core structural protein present in the basement membrane of several organs, including the kidneys. We hypothesized that dysregulation of LAMC1 remodeling could be associated with a higher risk of adverse clinical outcomes in patients with CKD.MethodsA novel immunoassay targeting LG1M, a specific MMP-9-generated neo-epitope fragment of LAMC1, was developed and used to measure the levels of the fragment in urine and serum from 492 patients from the Renal Impairment in Secondary Care (RIISC) study, a prospective cohort of patients with high-risk CKD. Patients were monitored for a median follow-up time of 3.5 years. Associations between serum and urine LG1M levels and progression of CKD at 12 months were assessed by a multivariable logistic regression model. The association with ESRD or mortality was assessed by Kaplan-Meier survival curves and Cox proportional hazards regression.ResultsForty-six (11%) of the 416 patients who reached 12-month follow-up had progression of CKD; during the study follow-up, 125 patients (25.4%) developed ESRD and 71 patients (14.4%) died. Serum and urine levels of LG1M correlated with baseline eGFR (r = -0.43, p<0.0001 and r = -0.17, p = 0.0002, respectively). Serum levels of LG1M were higher in patients with one-year progression of CKD compared to those who did not progress (p<0.01). Baseline serum levels of LG1M were associated with development of ESRD (HR 3.2, 95% CI 1.99–5.2 for patients in the highest LG1M tertile compared to patient in the lowest tertile). Baseline urinary levels of LG1M (uLG1M) were significantly associated with mortality (HR 5.0, 95% CI 2.8–8.9, p<0.0001 for patients in the highest LG1M tertile compared to patients in the lowest tertile). Urine LG1M was retained in the model for prediction of mortality (HR per standard deviation of uLG1M: 1.01, 95% CI 1.00–1.02, p = 0.001).ConclusionsLG1M, a marker of basement membrane remodeling, is increased in serum and urine of patients with CKD and levels are associated with one-year disease progression, development of ESRD, and mortality.

Ultrastructural Remodeling of the Neurovascular Unit in the Female Diabetic db/db Model—Part I: Astrocyte

Obesity, insulin resistance, and type 2 diabetes mellitus are associated with cognitive impairment, known as diabetic cognopathy. In this study, we tested the hypothesis that neurovascular unit(s) (NVU) within cerebral cortical gray matter regions display abnormal cellular remodeling. The monogenic (Leprdb) female diabetic db/db (BKS.CgDock7m +/+Leprdb/J; DBC) mouse model was utilized for this ultrastructural study. Upon sacrifice (at 20 weeks of age), left-brain hemispheres of the DBC and age-matched non-diabetic wild-type control C57BL/KsJ (CKC) mice were immediately immersion-fixed. We found attenuation/loss of endothelial blood–brain barrier tight/adherens junctions and pericytes, thickening of the basement membrane, aberrant mitochondria, and pathological remodeling of protoplasmic astrocytes. Additionally, there were adherent red blood cells and NVU microbleeds (cortical layer III) in DBC mice, which were not observed in CKC animals. While this study represents only a “snapshot in time”, it does allow for cellular remodeling comparisons between DBC and CKC. In this paper, the first of a three-part series, we report the observational ultrastructural remodeling changes of the NVU and its protoplasmic astrocytes in relation to the surrounding neuropil. Having identified multiple abnormal cellular remodeling changes in the DBC as compared to CKC models, we will design future experiments to evaluate various treatment modalities in DBC mice.

4982Markers of basement membrane remodelling are associated with higher mortality in patients with advanced carotid atherosclerosis

4982Markers of basement membrane remodelling are associated with higher mortality in patients with advanced carotid atherosclerosis

Abstract 1610: Expression of genes of the uPA system from LCM-procured breast carcinoma cells and their relationships with clinical outcomes

Abstract Introduction: The urokinase plasminogen activator (uPA), its receptor uPAR and serine protease inhibitors PAI-1 or PAI-2 play a key role in tissue membrane remodeling and invasion of basement membranes by induction of a fibrinolytic pathway. Earlier studies reported that uPA and PAI-1 protein levels assist in prediction of breast cancer response to chemotherapy. Our goal is to develop molecular signatures of candidate genes and identify novel relationships with these four protein biomarkers that demonstrate clinical utility for assessment of breast carcinoma outcomes. Methods: The retrospective study used de-identified tissue biopsies from primary breast cancers on which biomarker and clinical outcomes were stored in an IRB-approved Database. ELISA analyses of uPA, uPAR and PAI-1 performed using IMUBIND kits (American Diagnostica Inc.) used cutoff values previously reported. Estrogen (ER) and progestin receptor (PR) assays were performed either by EIA (Abbott Labs) or by radioligand binding (NEN/DuPont). Relative expression levels of 22,000 genes were determined by microarray using RNA extracted and amplified from Laser-Capture Microdissection (LCM) procured breast carcinoma cells. Univariable and multivariable Cox regression analyses, Kaplan-Meier plots, Violin and scatter grams were performed by R Studio version 3.4.1. External validation of gene subsets derived were performed with SurvExpress. Results: uPA and PAI-1 protein content of a carcinoma were predictive of overall survival (OS). Examination of biomarker gene expression by Violin plots revealed that either ER- or PR- breast cancers expressed elevated levels of UPA, UPAR and PAI2 compared to that of ER+ or PR+ carcinoma cells. Scatter grams suggested an inverse relationship between ER/PR protein levels and expression of UPA, UPAR and PAI2. Univariable Cox regression analyses indicated that PAI2 expression was associated with progression-free survival (PFS) and OS while UPA and PAI1 expression was only associated with OS with a p value &amp;lt; 0.3 (selected as the discovery limit). When carcinomas were sorted by biomarker levels, qPCR expression of RERG and NQO-1 were elevated in uPA- lesions while CD34 and EDG-1 were elevated in uPAR- cancers. However, ERBB4 expression was elevated in PAI-1+ carcinomas. Multivariate Cox regression, performed with backward conditional selection using microarray data with ER or PR status revealed clinically relevant genes for PFS and OS. SurvExpress, an online tool, validated gene subsets externally. Conclusions: Use of LCM-procured breast carcinoma cells in a nondestructive manner uncovered relationships between gene expression and either uPA, uPAR, PAI-1 or PAI-2 protein content of a lesion to reveal candidates for predicting clinical outcomes. Certain of these gene subsets appear related to patient prognosis when considered with ER/PR status of the carcinomas. Citation Format: Seth B. Sereff, Michael W. Daniels, James L. Wittliff. Expression of genes of the uPA system from LCM-procured breast carcinoma cells and their relationships with clinical outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1610.

Serological markers of extracellular matrix remodeling predict transplant-free survival in primary sclerosing cholangitis.

Primary sclerosing cholangitis is a progressive liver disease with a remarkably variable course. Biomarkers of disease activity or prognostic models predicting outcome at an individual level are currently not established. To evaluate the prognostic utility of four biomarkers of basement membrane and interstitial extracellular matrix remodeling in patients with primary sclerosing cholangitis. Serum samples were available from 138 large-duct primary sclerosing cholangitis patients (of which 102 [74%] with IBD) recruited 2008-2012 and 52 ulcerative colitis patients (controls). The median follow-up time was 2.2 (range 0-4.3) years. Specific biomarkers of type III and V collagen formation (PRO-C3 and PRO-C5, respectively) and type III and IV collagen degradation (C3M and C4M, respectively) were assessed. The Enhanced Liver Fibrosis test, including procollagen type III N-terminal peptide, tissue inhibitor of metalloproteinase-1 and hyaluronic acid was assessed for comparison. All markers were elevated in primary sclerosing cholangitis compared to ulcerative colitis patients (P<0.001). PRO-C3 showed the largest difference between the two groups with a threefold increase in primary sclerosing cholangitis compared to ulcerative colitis patients. Patients with high baseline serum levels of all markers, except C3M, had shorter survival compared to patients with low baseline serum levels (P<0.001). Combining PRO-C3 and PRO-C5 the odds ratio for predicting transplant-free survival was 47 compared to the Enhanced Liver Fibrosis test's odds ratio of 11. Extracellular matrix remodeling is elevated in primary sclerosing cholangitis patients compared to ulcerative colitis patients. Furthermore, the interstitial matrix marker PRO-C3 was identified as a potent prognostic marker and an independent predictor of transplant-free survival in primary sclerosing cholangitis.

P125 Basement membrane remodelling as a biomarker for monitoring disease activity in Crohn’s disease patients: the role of laminin

P125 Basement membrane remodelling as a biomarker for monitoring disease activity in Crohn’s disease patients: the role of laminin

MicroRNA-mediated MMP Regulation: Current Diagnostic and Therapeutic Strategies for Metabolic Syndrome.

Metabolic Syndrome (MS) is a global socioeconomic problem rapidly progressing in accordance with increasing Body Mass Index (BMI) and age. It is a consortium of risk factors, such as dyslipidaemia, insulin resistance, leptin resistance, reduced adiponectin, glucose intolerance, hyperglycemia, and hypertension. Collectively, these factors accelerate the onset of type 2 diabetes mellitus, cardiovascular disease, stroke, and certain cancers such as breast, liver pancreatic, and colon cancer. Extracellular Matrix (ECM) and basement membrane remodeling play a central role during pathogenesis of MS as they regulate diverse cell functions including proliferation, differentiation, and migration. Therefore, regulation of proteins that remodel the ECM offers promising therapeutic opportunities for most of the MS. Matrix Metalloproteinases (MMPs), a family of zinc dependent endopeptidases, are the main enzymes involved in ECM remodeling. Emerging studies have reported altered levels of MMPs and the Tissue Inhibitors of Metalloproteinases (TIMPs) during MS. A number of pharmaceutical MMP inhibitors are being developed, but they have yet to be recognized for clinical applications. Recently, microRNAs (~21-23-nucleotide, small non-coding, endogenous, single-stranded RNAs) have emerged as a class of promising entities for therapeutic intervention due to their ability to manipulate gene expression. The combined strategy of targeting ECM remodeling through regulation of MMPs by small non-coding RNA has produced encouraging results in pre-clinical studies for cancer and cardiovascular diseases. This review serves to provide insight into the role of microRNAs as modulators of MS and their potential as therapeutics tool through direct and indirect interactions with the MMPs.

Tumor Necrosis Factor-α and IL-17A Activation Induces Pericyte-Mediated Basement Membrane Remodeling in Human Neutrophilic Dermatoses

Sweet syndrome (SS) is a prototypical neutrophilic dermatosis, a class of inflammatory diseases marked by elevated levels of tumor necrosis factor (TNF)-α and IL-17A, pathologic neutrophil recruitment, and microvascular remodeling. Histologic analyses of four matrix proteins-collagen I and IV, laminin, and fibronectin-in skin biopsies of patients with SS reveal that the basement membrane of dermal postcapillary venules undergoes changes in structure and composition. Increased neutrophil recruitment invivo was associated with increases in collagen IV, decreases in laminin, and varied changes in fibronectin. Invitro studies using TNF-α and IL-17A were conducted to dissect basement membrane remodeling. Prolonged dual activation of cultured human pericytes with TNF-α and IL-17A augmented collagen IV production, similar to invivo remodeling. Co-activation of pericytes with TNF-α and IL-17A also elevated fibronectin levels with little direct effect on laminin. However, the expression of fibronectin- and laminin-specific matrix metalloproteinases (MMPs), particularly MMP-3, was significantly up-regulated. Interactions between pericytes and neutrophils in culture yielded even higher levels of active MMPs, facilitating fibronectin and laminin degradation, and likely contributing to the varied levels of detectable fibronectin and the decreases in laminin observed invivo. These data indicate that pericyte-neutrophil interactions play a role in mediating microvascular changes in SS and suggest that targeting MMP-3 may be effective in protecting vascular wall integrity.

Abstract 600: Deposition of Endothelial Cell-derived Fibronectin by Alpha5beta1 Integrins Mediates Oxidized LDL-induced Proinflammatory Gene Expression and Early Atherosclerosis

Subendothelial basement membrane remodeling to a fibronectin-rich matrix precedes lesion development, and endothelial cell interactions with fibronectin prime inflammatory responses to a variety of atherogenic stimuli. However, the mechanisms regulating early atherogenic fibronectin accumulation remain unknown. We now show that treating endothelial cells with oxidized LDL (oxLDL) potently induces endothelial fibronectin deposition through activation of the fibronectin-binding integrin α5β1, as inhibiting α5β1 (blocking antibodies, α5 knockout cells) completely abrogates oxLDL-induced fibronectin deposition in vitro . Inducible endothelial-specific deletion of α5 integrins significantly blunts endothelial proinflammatory gene expression at atheroprone sites and diminishes atherosclerotic plaque formation in ApoE knockout mice, suggesting an important role for this integrin in early endothelial activation. However, endothelial α5 deletion surprisingly enhances fibronectin staining in the endothelial layer, potentially due to leak of plasma-derived fibronectin. Plasma fibronectin differs from cell-derived fibronectin due to the lack of two alternatively spliced domains, termed extradomain A (EIIIA) and extradomain B (EIIIB). Interestingly, loss of endothelial cell-derived fibronectin (fibronectin siRNA) completely inhibits oxLDL-induced VCAM-1 expression, and only rescue with cell-derived fibronectin, but not plasma fibronectin, reverses this inhibitory effect. This effect appears to be due to the presence of EIIIA and EIIIB domains, as endothelial cells isolated from EIIIA/EIIIB knockout mice also show reduced oxLDL-induced proinflammatory responses. However, it is unclear whether this response is due to specific EIIIA/EIIIB receptors or due to altered integrin signaling, as limiting the presence of cell-derived fibronectin prevents integrin α5 localization to focal adhesions and reduces fibronectin fibril length. Taken together, our data demonstrate that oxLDL stimulates α5 integrin-dependent deposition of endothelial-derived fibronectin into the subendothelial matrix and suggest that the source of fibronectin regulates the subsequent endothelial cell proinflammatory responses.

Sterile Inflammation Enhances ECM Degradation in Integrin β1 KO Embryonic Skin

Epidermal knockout of integrin β1 results in complete disorganization of the basement membrane (BM), resulting in neonatal lethality. Here, we report that this disorganization is exacerbated by an earlyembryonic inflammatory response involving the recruitment of tissue-resident and monocyte-derived macrophages to the dermal-epidermal junction, associated with increased matrix metalloproteinase activity. Remarkably, the skin barrier in the integrin β1 knockout animals is intact, suggesting that this inflammatory response is initiated in a sterile environment. We demonstrate that the molecular mechanism involves de novo expression of integrin αvβ6 in the basal epidermal cells, which activates a TGF-β1 driven inflammatory cascade resulting in upregulation of dermal NF-κB in a Tenascin C-dependent manner. Importantly, treatment of β1 KO embryos in utero with small molecule inhibitors of TGF-βR1 and NF-κB results in marked rescue of the BM defects and amelioration of immune response, revealing an unconventional immuno-protective role for integrin β1 during BM remodeling.