ECM Protein Deposition Research Articles

Biomaterial systems for evaluating the influence of ECM mechanics on anti-fibrotic therapeutic efficacy

Cardiac fibrosis is characterized by excessive accumulation and deposition of ECM proteins. Cardiac fibrosis is commonly implicated in a variety of cardiovascular diseases, including post-myocardial infarction (MI). We have previously developed a dual-delivery nanogel therapeutic to deliver tissue plasminogen activator (tPA) and Y-27632 (a ROCK inhibitor) to address MI-associated coronary artery occlusion and downregulate cell-contractility mediated fibrotic responses. Initial in vitro studies were conducted on glass substrates. The study presented here employs the use of polyacrylamide (PA) gels and microgel thin films to mimic healthy and fibrotic cardiac tissue mechanics. Soft and stiff polyacrylamide substrates or high and low loss tangent microgel thin films were utilized to examine the influence of cell-substrate interactions on dual-loaded nanogel therapeutic efficacy. In the presence of Y-27632 containing nanogels, a reduction of fibrotic marker expression was noted on traditional PA gels mimicking healthy and fibrotic cardiac tissue mechanics. These findings differed on more physiologically relevant microgel thin films, where early treatment with the ROCK inhibitor intensified the fibrotic related responses.

P34 - Topic: AS04-MDS Biology and Pathogenesis/AS04i-Microenvironment and stem cell niche: ABERRANT SMAD2/3 SIGNALING IN MDS BONE MARROW STROMA CONTRIBUTES TO ALTERED ECM PROTEIN DEPOSITION AND CAN BE RESCUED BY LUSPATERCEPT

P34 - Topic: AS04-MDS Biology and Pathogenesis/AS04i-Microenvironment and stem cell niche: ABERRANT SMAD2/3 SIGNALING IN MDS BONE MARROW STROMA CONTRIBUTES TO ALTERED ECM PROTEIN DEPOSITION AND CAN BE RESCUED BY LUSPATERCEPT

Delayed treatment with an autophagy inhibitor 3-MA alleviates the progression of hyperuricemic nephropathy

Autophagy is a cell self-renewal process that relies on the degradation of the cytoplasmic proteins or organelles of lysosomes and is associated with development of numerous diseases. However, the therapeutic effect of autophagy inhibition on hyperuricemic nephropathy (HN) and the underlying mechanisms are still unknown. Here, we investigated the effect of delayed treatment with 3-methyladenine (3-MA), a specific autophagy inhibitor, on the development of HN in a rat model. Administration of 3-MA at 21 days following after uric acid injury protected kidney from hyperuricemic-related injuries, as demonstrated by improving renal dysfunction and architecture damage, blocking Beclin-1 and LC3II/I and decreasing the number of autophagic vacuoles. Late treatment with 3-MA was also effective in attenuating renal fibrosis as evidenced by reducing ECM protein deposition, blocking epithelial-to-mesenchymal transition (EMT) and decreasing the number of renal epithelial cells arrested at the G2/M phase of cell cycle. Injury to the kidney resulted in increased expression of TGFβ receptor I, and phosphorylation of Smad3, 3-MA significantly abrogated all these responses. Moreover, inhibition of autophagy suppressed mitochondrial fission, downregulated the expression of Dynamin-related protein 1 (Drp-1), Cofilin and F-actin, and alleviated cell apoptosis. Finally, 3-MA effectively blocked STAT3 and NF-κB phosphorylation and suppressed infiltration of macrophages and lymphocytes as well as release of multiple profibrogenic cytokines/chemokines in the injured kidney. Taken together, these findings indicate that hyperuricemia-induced autophagy is critically involved in the activation of renal fibroblasts, EMT, mitochondrial fission and apoptosis of tubular epithelial cells and development of renal fibrosis. Thus, this study provides evidence for autophagy inhibitors as the treatment of HN patients.

The effects of platelet lysate patches on the activity of tendon-derived cells

Platelet-derived biomaterials are widely explored as cost-effective sources of therapeutic factors, holding a strong potential for endogenous regenerative medicine. Particularly for tendon repair, treatment approaches that shift the injury environment are explored to accelerate tendon regeneration. Herein, genipin-crosslinked platelet lysate (PL) patches are proposed for the delivery of human-derived therapeutic factors in patch augmentation strategies aiming at tendon repair. Developed PL patches exhibited a controlled release profile of PL proteins, including bFGF and PDGF-BB. Additionally, PL patches exhibited an antibacterial effect by preventing the adhesion, proliferation and biofilm formation by S. aureus, a common pathogen in orthopaedic surgical site infections. Furthermore, these patches supported the activity of human tendon-derived cells (hTDCs). Cells were able to proliferate over time and an up-regulation of tenogenic genes (SCX, COL1A1 and TNC) was observed, suggesting that PL patches may modify the behavior of hTDCs. Accordingly, hTDCs deposited tendon-related extracellular matrix proteins, namely collagen type I and tenascin C.In summary, PL patches can act as a reservoir of biomolecules derived from PL and support the activity of native tendon cells, being proposed as bioinstructive patches for tendon regeneration. Statement of significancePlatelet-derived biomaterials hold great interest for the delivery of therapeutic factors for applications in endogenous regenerative medicine. In the particular case of tendon repair, patch augmentation strategies aiming at shifting the injury environment are explored to improve tendon regeneration. In this study, PL patches were developed with remarkable features, including the controlled release of growth factors and antibacterial efficacy. Remarkably, PL patches supported the activity of native tendon cells by up-regulating tenogenic genes and enabling the deposition of ECM proteins. This patch holds great potential towards simultaneously reducing post-implantation surgical site infections and promoting tendon regeneration for prospective in vivo applications.

2017 AHA Late-Breaking Basic Science Abstracts

### 24036 ### Inhibition Of Prolyl-tRNA Synthetase As A Novel Mediator Of Cardiac Fibrosis Joon Seok Park1, Caroline H Lee1, Sungjin Yoon1, Jong Hyun Kim2, Sunghoon Kim2, Bongyong Lee1; 1Daewoong Pharmaceutical Co., Ltd., Yongin, Korea, Republic of; 2Medicinal Bioconvergence Rsch Center, Seoul National Univ, Suwon, Korea, Republic of Introduction: Prolyl-tRNA synthetase (PRS), a member of aminoacyl tRNA synthetases (ARS), is an enzyme that conjugates amino acid proline to its cognate tRNA to generate prolyl-tRNA to be used in protein synthesis. Since ARS are essential for protein synthesis and viability, dysregulation of ARS has been proposed to many human diseases. Cardiac fibrosis is characterized by excess production and deposition of ECM proteins by activated fibroblast. Although proline is a main component of collagen and ECM proteins, the exact mechanism and involvement of PRS in cardiac fibrosis has not yet been elucidated. Hypothesis: We hypothesized that suppression of PRS would down-regulate collagen synthesis, which could be beneficial in cardiac fibrosis. Results: To validate our hypothesis, we investigated the expression levels of pro-fibrotic markers by overexpression or knockdown of PRS in vitro. We showed that PRS is closely related to the expression of collagen I and α-SMA. Then, we showed that treatment of DWN12088, a novel small molecular selective inhibitor of PRS, reduced expression levels of pro-fibrotic markers in TGFβ-induced fibrotic environments using various cell-lines and primary fibroblasts. Interestingly, we showed that down-regulation of pro-fibrotic markers by DWN12088 is independent of TGFβ signaling pathway, although TGFβ is required for induction of pro-fibrotic markers. In vivo study, we performed transverse aortic constriction in C57BL/6 mice to evaluate the effect of DWN12088 in cardiac fibrosis. TAC results in pressure overload-induced left ventricular hypertrophy and fibrosis, and it is one of the most widely used models to study cardiovascular diseases. 2-week oral treatment of DWN12088 markedly …

Abstract 24036: Inhibition Of Prolyl-tRNA Synthetase As A Novel Mediator Of Cardiac Fibrosis

Introduction: Prolyl-tRNA synthetase (PRS), a member of aminoacyl tRNA synthetases (ARS), is an enzyme that conjugates amino acid proline to its cognate tRNA to generate prolyl-tRNA to be used in protein synthesis. Since ARS are essential for protein synthesis and viability, dysregulation of ARS has been proposed to many human diseases. Cardiac fibrosis is characterized by excess production and deposition of ECM proteins by activated fibroblast. Although proline is a main component of collagen and ECM proteins, the exact mechanism and involvement of PRS in cardiac fibrosis has not yet been elucidated. Hypothesis: We hypothesized that suppression of PRS would down-regulate collagen synthesis, which could be beneficial in cardiac fibrosis. Results: To validate our hypothesis, we investigated the expression levels of pro-fibrotic markers by overexpression or knockdown of PRS in vitro. We showed that PRS is closely related to the expression of collagen I and α-SMA. Then, we showed that treatment of DWN12088, a novel small molecular selective inhibitor of PRS, reduced expression levels of pro-fibrotic markers in TGFβ-induced fibrotic environments using various cell-lines and primary fibroblasts. Interestingly, we showed that down-regulation of pro-fibrotic markers by DWN12088 is independent of TGFβ signaling pathway, although TGFβ is required for induction of pro-fibrotic markers. In vivo study, we performed transverse aortic constriction in C57BL/6 mice to evaluate the effect of DWN12088 in cardiac fibrosis. TAC results in pressure overload-induced left ventricular hypertrophy and fibrosis, and it is one of the most widely used models to study cardiovascular diseases. 2-week oral treatment of DWN12088 markedly reduced cardiac fibrosis with ED 50 of 0.4 mg/kg, based on histological examinations. In addition, we demonstrated that 2-week oral treatment of DWN12088 showed reduction in infiltration of inflammatory cells, left ventricle thickness and accumulation of collagen fiber. Conclusion: These results suggest that inhibition of PRS attenuates pressure-overloaded cardiac fibrosis and a selective inhibitor of PRS, DWN12088, could serve as a potent anti-fibrotic agent without affecting critical cellular signaling cascade.

Pro-fibrotic compounds induce stellate cell activation, ECM-remodelling and Nrf2 activation in a human 3D-multicellular model of liver fibrosis.

Background & AimsCurrently most liver fibrosis research is performed in vivo, since suitable alternative in vitro systems which are able to recapitulate the cellular events leading to liver fibrosis are lacking. Here we aimed at generating a system containing cells representing the three key players of liver fibrosis (hepatocyte, Kupffer cells and stellate cells) and assess their response to pro-fibrotic compounds such as TGF-β1, methotrexate (MTX) and thioacetamide (TAA).MethodsHuman cell lines representing hepatocytes (HepaRG), Kupffer cell (THP-1 macrophages) and stellate cells (hTERT-HSC) were co-cultured using the InSphero hanging drop technology to generate scaffold-free 3D microtissues, that were treated with pro-fibrotic compounds (TGF-β1, MTX, TAA) for up to 14 days. The response of the microtissues was evaluated by determining the expression of cytokines (TNF-α, TGF-β1 and IL6), the deposition and secretion of ECM proteins and induction of gene expression of fibrosis biomarkers (e.g. αSMA). Induction of Nrf2 and Keap1, as key player of defence mechanism, was also evaluated.ResultsWe could demonstrate that the multicellular 3D microtissue cultures could be maintained in a non-activated status, based on the low expression levels of activation markers. Macrophages were activated by stimulation with LPS and hTERT-HSC showed activation by TGF-β1. In addition, MTX and TAA elicited a fibrotic phenotype, as assessed by gene-expression and protein-deposition of ECM proteins such as collagens and fibronectin. An involvement of the antioxidant pathway upon stimulation with pro-fibrotic compounds was also observed.ConclusionHere, for the first time, we demonstrate the in vitro recapitulation of key molecular and cellular events leading to liver fibrosis: hepatocellular injury, antioxidant defence response, activation of Kupffer cells and activation of HSC leading to deposition of ECM.

Differential deposition of fibronectin by asthmatic bronchial epithelial cells

Altered ECM protein deposition is a feature in asthmatic airways. Fibronectin (Fn), an ECM protein produced by human bronchial epithelial cells (HBECs), is increased in asthmatic airways. This study investigated the regulation of Fn production in asthmatic or nonasthmatic HBECs and whether Fn modulated HBEC proliferation and inflammatory mediator secretion. The signaling pathways underlying transforming growth factor (TGF)-β1-regulated Fn production were examined using specific inhibitors for ERK, JNK, p38 MAPK, phosphatidylinositol 3 kinase, and activin-like kinase 5 (ALK5). Asthmatic HBECs deposited higher levels of Fn in the ECM than nonasthmatic cells under basal conditions, whereas cells from the two groups had similar levels of Fn mRNA and soluble Fn. TGF-β1 increased mRNA levels and ECM and soluble forms of Fn but decreased cell proliferation in both cells. The rate of increase in Fn mRNA was higher in nonasthmatic cells. However, the excessive amounts of ECM Fn deposited by asthmatic cells after TGF-β1 stimulation persisted compared with nonasthmatic cells. Inhibition of ALK5 completely prevented TGF-β1-induced Fn deposition. Importantly, ECM Fn increased HBEC proliferation and IL-6 release, decreased PGE2 secretion, but had no effect on VEGF release. Soluble Fn had no effect on cell proliferation and inflammatory mediator release. Asthmatic HBECs are intrinsically primed to produce more ECM Fn, which when deposited into the ECM, is capable of driving remodeling and inflammation. The increased airway Fn may be one of the key driving factors in the persistence of asthma and represents a novel, therapeutic target.

TGF-β1-elevated TRPM7 channel regulates collagen expression in hepatic stellate cells via TGF-β1/Smad pathway

Transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts plays a critical role in the development of liver fibrosis, since myofibroblasts are the key cells responsible for excessive deposition of ECM proteins. Transient receptor potential melastatin 7 (TRPM7), a non-selective cation channel with protein serine/threonine kinase activity, has been demonstrated to function in the proliferation of activated HSCs. Here, we investigated the functional role of TRPM7 in collagen deposition in activated HSC-T6 cells (a rat hepatic stellate cell line). TRPM7 mRNA and protein were measured by Real-time PCR and Western blot in TGF-β1-activated HSC-T6 cells in vitro. Results demonstrated that TRPM7 protein was dramatically increased in fibrotic human livers. Stimulation of HSC-T6 cells with TGF-β1 increased TRPM7 mRNA and protein level in a time-dependent manner. Nevertheless, TGF-β1-elicited upregulation of TRPM7 in HSC-T6 cells was abrogated by SB431542 (TGF-β1 receptor blocker) or SIS3 (inhibitor of Smad3 phosphorylation). Additionally, blockade of TRPM7 channels with non-specific TRPM7 blocker 2-APB or synthetic siRNA targeting TRPM7 attenuated TGF-β1-induced expression of myofibroblast markers, as measured by the induction of α-SMA and Col1α1. Silencing TRPM7 also increased the ratio of MMPs/TIMPs by increasing MMP-13 expression and decreasing TIMP-1 and TIMP-2 levels. Strikingly, phosphorylation of p-Smad2 and p-Smad3, associated with collagen production, was decreased in TRPM7 deficient HSC-T6 cells. These observations suggested that TGF-β1 elevates TRPM7 expression in HSCs via Smad3-dependant mechanisms, which in turn contributes Smad protein phosphorylation, and subsequently increases fibrous collagen expression. Therefore, TRPM7 may constitute a useful target for the treatment of liver fibrosis.

Fibrosis and inflammation are greater in muscles of beta-sarcoglycan-null mouse than mdx mouse.

The Sgcb-null mouse, with knocked-down β-sarcoglycan, develops severe muscular dystrophy as in type 2E human limb girdle muscular dystrophy. The mdx mouse, lacking dystrophin, is the most used model for Duchenne muscular dystrophy (DMD). Unlike DMD, the mdx mouse has mild clinical features and shows little fibrosis in limb muscles. To characterize ECM protein deposition and the progression of muscle fibrosis, we evaluated protein and transcript levels of collagens I, III and VI, decorin, and TGF-β1, in quadriceps and diaphragm, at 2, 4, 8, 12, 26, and 52 weeks in Sgcb-null mice, and protein levels at 12, 26, and 52 weeks in mdx mice. In Sgcb-null mice, severe morphological disruption was present from 4 weeks in both quadriceps and diaphragm, and included conspicuous deposition of extracellular matrix components. Histopathological features of Sgcb-null mouse muscles were similar to those of age-matched mdx muscles at all ages examined, but, in the Sgcb-null mouse, the extent of connective tissue deposition was generally greater than mdx. Furthermore, in the Sgcb-null mouse, the amount of all three collagen isoforms increased steadily, while, in the mdx, they remained stable. We also found that, at 12 weeks, macrophages were significantly more numerous in mildly inflamed areas of Sgcb-null quadriceps compared to mdx quadriceps (but not in highly inflamed regions), while, in the diaphragm, macrophages did not differ significantly between the two models, in either region. Osteopontin mRNA was also significantly greater at 12 weeks in laser-dissected highly inflamed areas of the Sgcb-null quadriceps compared to the mdx quadriceps. TGF-β1 was present in areas of degeneration-regeneration, but levels were highly variable and in general did not differ significantly between the two models and controls. The roles of the various subtypes of macrophages in muscle repair and fibrosis in the two models require further study. The Sgcb-null mouse, which develops early fibrosis in limb muscles, appears more promising than the mdx mouse for probing pathogenetic mechanisms of muscle fibrosis and for developing anti-fibrotic treatments. Highlights • The Sgcb-null mouse develops severe muscular dystrophy, the mdx mouse does not. • Fibrosis developed earlier in Sgcb-null quadriceps and diaphragm than mdx. • Macrophages were commoner in mildly inflamed parts of Sgcb-null quadriceps than mdx. • The Sgcb-null model appears more useful than mdx for studying fibrotic mechanisms. • The Sgcb-null model also appears more useful for developing anti-fibrotic treatments.

Tuning liver stiffness against tumours: An in vitro study using entrapped cells in tumour-like microcapsules

Liver fibrosis is a reversible pathology characterized by the up-regulated secretion and deposition of ECM proteins and inhibitors of metalloproteinases, which increase the stiffness and viscosity of this organ. Since recent studies have shown that fibrosis preceded the generation of hepatocellular carcinomas, we hypothesize that liver fibrosis could play a role as a mechanism for restricting uncontrolled cell proliferation, inducing the mortality of cancer cells and subsequent development of primary tumours.With this purpose, in this work we analysed in vitro how the modulation of stiffness can influence proliferation, viability and aggregation of hepatocarcinoma cells (HepG2) embedded in 3D micromilieus mimicking values of elasticity of fibrotic liver tissues.Experiments were performed by immobilizing up to 10 HepG2 cells within microcapsules made of 0.8%, 1.0% and 1.4% w/v alginate which, besides having values of elasticity from the lower-healthy to the upper-fibrotic range liver tissues, lacked domains for proteases, mimicking the micromilieu existing in hepatic primary tumours.Our results show that entrapped cells exhibited a short duplication phase followed by an irreversible decay stage, in which cell mortality could be mediated by two mechanisms: mechanical stress, in the case of cells entrapped in a stiffer micromilieu; and mass transfer limitations produced by pore coarsening at the interface cell–matrix, in softer micromilieus.According to the authors’ knowledge, this work represents the first attempt to elucidate the role of liver fibrosis during Hepatocarcinoma pathologies, suggesting that the generation of a non-biodegradable and mechanically unfavourable environment surrounding cancer cells could control the proliferation, migration of metastatic cells and the subsequent development of primary tumours.

Hydrodynamic forces regulate ECM protein expression and deposition during cardiac valve development

The primordia of atrioventicular (AV) valves are cushions that attenuate, elongate, and stiffen into fibrous tissues as they mature. It has been postulated that increasing hydrodynamic forces during development contribute to valve morphogenesis. To investigate the molecular mechanisms of flow‐generated force on valve maturation, we have utilized a novel 3D in‐vitro culture system. AV cushion explants were cultured inside a tubular collagen scaffold attached to a pulsatile pump. Estimated in‐vivo flows were applied to developing valve tissues. Data from RT‐PCR, confocal, and Western blot analyses show that flow regulates the expression and localization of ECM proteins in developing AV cushions. Further, the RhoA signaling pathway has been shown to be an important mediator of mechanical signals in endothelial cells. Our data show that RhoA mRNA levels in AV cushion explants are enhanced under flow conditioning. Additionally, compared to controls, cushion explants undergoing flow forces had increased expression of ECM proteins when treated with RhoA activator lysophosphatidic acid, while Y‐27632 Rho‐kinase inhibitor suppresses ECM protein expression. AFM studies confirm that flow and RhoA also regulate the material properties of developing valves. Our data indicate that hydrodynamic forces can drive expression and deposition of fibrous ECM proteins that are critical for proper valve morphogenesis.

Expression and Deposition of Fibrous Extracellular Matrix Proteins in Cardiac Valves during Chick Development

Extracellular matrix (ECM) plays essential signaling and structural roles required for the proper function of cardiac valves. Cardiac valves initially form as jelly-like cushions, which must adapt to withstand the increased circulation hemodynamics associated with fetal development and birth. This increased biomechanical stability of the developing valves is largely imparted by ECM proteins, which form a highly organized fibrous meshwork. Since heart valve defects contribute to most congenital heart diseases, understanding valve development will provide insight into the pathogenesis of various congenital valve anomalies. Thus, the goal of this study is to describe the spatiotemporal deposition of fibrous ECM proteins during cardiac valve development. Chick embryonic and fetal atrioventricular and semilunar valves were examined by light, confocal, and transmission electron microscopy (TEM). Our data demonstrate that fibrous ECM proteins are deposited when the leaflets are adopting an elongated and compacted phenotype. A general pattern of increased fibrotic ECM deposition was detected in valve tissues. Also, each ECM protein examined displayed a unique pattern of organization, suggesting that regulation of fibrous protein deposition is complex and likely involves both genetic and mechanical factors. In addition, the TEM study revealed the presence of membrane protrusions from valvular endocardium, indicating a potential mechanism for mechanical force transduction.

AP-1 overexpression impairs corticosteroid inhibition of collagen production by fibroblasts isolated from asthmatic subjects

Asthma is characterized by airway remodeling associated with an increase in the deposition of ECM proteins such as type I collagen. These components are mainly produced by fibroblasts. Inhaled corticosteroids are considered the cornerstone of asthma therapy. Despite substantial evidence as to the anti-inflammatory action of corticosteroids, their effect on controlling ECM protein deposition in the airways is not completely understood. This study determined the effect of dexamethasone (Dex) on collagen production by bronchial fibroblasts derived from asthmatic and healthy subjects. Expression of procollagen mRNA in fibroblasts from asthmatics and normal controls was determined by quantitative PCR. Regulation of the procollagen-alpha(1)I promoter was evaluated by transient transfections. Transforming growth factor-beta (TGF-beta) protein expression was determined by ELISA. Protein expression of glucocorticoid receptor (GR) and interaction with activator protein-1 (AP-1), a collagen regulatory transcription factor, was assessed by Western blots, coimmunoprecipitations, and EMSA. AP-1 overexpression was performed by transient transfection using c-Fos/c-Jun expression plasmids. Dex significantly downregulated procollagen production and promoter activity in normal fibroblasts but had no effect on asthmatic fibroblasts. AP-1 and GR interaction increased after Dex stimulation in asthmatic fibroblasts. AP-1 overexpression in control fibroblasts abrogated collagen gene response to Dex. These results show that Dex failed to reduce collagen production in fibroblasts from asthmatic subjects. This impaired response may be related to AP-1 overexpression in these cells.

Effect of total saponins of “panax notoginseng root” on aortic intimal hyperplasia and the expressions of cell cycle protein and extracellular matrix in rats

the effect of total saponins of "panax notoginseng root" on aortic intimal hyperplasia and the expressions of cell cycle protein and extracellular matrix in rats Sprague-Dawley rats were randomly divided into sham-operated, control, TSPN and atorvastatin group. Rat aorta intima in all groups were injured by insertion of domestic balloon catheter into the aortae except sham-operated rats. Drugs were administrated orally from the second day after vascular injury and continued for 14 days. The injured segments of aortae were collected on the sixteenth day after operation to observe the morphological changes of vascular structure and to examine the expressions of proliferating cell nuclear antigen(PCNA), cyclinD1, cyclinE, collagen I(Col-I), fibronect(FN), matrix metalloproteinase-9(MMP-9) and tissue inhibitor metalloproteinase-1(TIMP-1). TPNS significantly inhibited the vascular intimal hyperplasia. TPNS significantly lowered the expression of PCNA, cyclinE, cyclinD1, FN and MMP-9. TPNS had no significant impacts on the expression of Col-I and TIMP-1. Our studies indicated that TSPN could inhibit vessel restenosis after vascular intimal injury, and its mechanisms may be related to the blockage of the excessive proliferation of VSMC, the reduction of ECM protein deposition in the endometrium, and the degradation of ECM protein.

Different role of CD30 in the development of acute and chronic airway inflammation in a murine asthma model

CD30 is a costimulatory molecule of the TNF receptor superfamily, expressed on activated T and B cells. Previously, we have shown in a murine asthma model the crucial role of CD30 signaling for the development of this Th2-cell-mediated disease. In the present study, we investigated the role of CD30 in the maintenance of the immune response. In contrast to the acute model, in the chronic model CD30(-/-) mice developed a severe asthma-like phenotype with eosinophilic inflammation and high serum IgE levels. Collagen content, ECM protein deposition and proliferation of smooth muscle cells as signs for airway remodeling were equally increased in both CD30(-/-) and WT mice. Reduced expression of the costimulatory molecule OX40 on CD3(+) T cells in the acute and up-regulation in the chronic model indirectly supported a compensatory role of OX40 for CD30 signaling. In accordance, application of agonistic OX40 antibody restored the asthma phenotype in CD30(-/-) mice in the acute model, whereas chronic airway inflammation was reduced in the presence of an inhibitory anti-OX40 ligand antibody. These data demonstrate that the crucial role of CD30 signaling in the development of acute asthma may be taken over by other costimulatory molecules like OX40 after long-term exposure to the antigen.

Alveolar epithelial cell injury with Epstein-Barr virus upregulates TGFβ1 expression

Idiopathic pulmonary fibrosis (IPF) is a refractory and lethal interstitial lung disease characterized by alveolar epithelial cells apoptosis, fibroblast proliferation, and ECM protein deposition. Epstein-Barr virus (EBV) has previously been localized to alveolar epithelial cells of IPF patients and is associated with a poor prognosis. In this study, we utilized a microarray-based differential gene expression analysis strategy to identify molecular drivers of EBV-associated lung fibrosis. Two cell lines, primary human alveolar epithelial cells type 2 and A549 cells, were infected with EBV. EBV lytic phase induction increased active and total transforming growth factor-beta1 (TGFbeta1) transcript expression in association with reduced cell proliferation and increased caspase 3/7 activity. Exposing EBV-infected cells to ganciclovir resulted in TGFbeta1 deregulation and reduced expression of EBV early response genes, BRLF1 and BZLF1. We targeted the BRLF1 and BZLF1 gene products, Rta and Zta, by silencing RNA, and this resulted in the normalization of TGFbeta1 transcript and cell proliferation levels. Our study using a viral cell line model complements existing human and animal model data and further provides evidence to suggest that viral epithelial cell injury may play a role in IPF.

Urinary proteome and potential biomarkers associated with serial pathogenesis steps of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a chronic nephropathy showing characteristic glomerular sclerosis. So far, the diagnosis and prognosis of FSGS rely mainly on the invasive biopsy. Searching for potential FSGS-associated urinary biomarkers representing pre-sclerotic and serial sclerotic stages of FSGS could be helpful to the non-invasive diagnosis and prognosis of FSGS. In the present study, we used a 2D gel-based proteomic approach to identify urinary proteins at pre-sclerotic and different sclerotic stages of an FSGS mouse model in order to find FSGS-related urinary proteins. The FSGS mouse model was established in Balb/c mice by a single injection of adriamycin, and disease severity was monitored by renal biological parameters and histopathological features. Urine was collected on days 0, 4, 7, 11, 15 and 20, and subjected to two-dimensional electrophoresis (2-DE) analysis. Proteins were identified by matrix-assisted laser desorption ionization/time of flight mass spectrometry (MALDI-TOF MS) and a protein database search. Some of the identified proteins were confirmed by western blot analysis. We identified 37 urinary proteins showing characteristic patterns of dynamic changes along the disease course of FSGS. Early urinary proteins appearing before glomerular sclerosis were noticed. Importantly, 11 urine proteins are novel to FSGS and have known functions highly associated with different pathogenetic steps of the disease, including haemodynamic disturbance, podocyte apoptosis, ECM-protein deposition and glomerular sclerosis. Some urinary proteins appearing earlier than glomerular sclerosis could serve as potential early diagnostic biomarkers. The proteins with the pathogenic roles could serve as potential non-invasive prognostic markers of FSGS, and give an insight into pathogenic mechanisms of this sclerosis disease.

Involvement of PPAR nuclear receptors in tissue injury and wound repair

Tissue damage resulting from chemical, mechanical, and biological injury, or from interrupted blood flow and reperfusion, is often life threatening. The subsequent tissue response involves an intricate series of events including inflammation, oxidative stress, immune cell recruitment, and cell survival, proliferation, migration, and differentiation. In addition, fibrotic repair characterized by myofibroblast transdifferentiation and the deposition of ECM proteins is activated. Failure to initiate, maintain, or stop this repair program has dramatic consequences, such as cell death and associated tissue necrosis or carcinogenesis. In this sense, inflammation and oxidative stress, which are beneficial defense processes, can become harmful if they do not resolve in time. This repair program is largely based on rapid and specific changes in gene expression controlled by transcription factors that sense injury. PPARs are such factors and are activated by lipid mediators produced after wounding. Here we highlight advances in our understanding of PPAR action during tissue repair and discuss the potential for these nuclear receptors as therapeutic targets for tissue injury.

Eosinophils in repair and remodelling

SummarySeveral studies in man suggest a role for the eosinophil in repair in remodelling. Skin biopsies taken at time intervals after allergen injection into human skin indicate that the formation of myofibroblast‐like cells and activation of fibroblasts, as shown by tenascin and procollagen‐1 production, may be partly under the control of infiltrating TGF‐β1+/IL‐13+ eosinophils. Studies involving the infusion of an anti‐IL‐5 monoclonal antibody to atopic subjects indicate that eosinophils are unlikely to be essential for the redness, swelling and induration characteristic of late‐phase allergic response but may play a role in repair/remodelling processes as shown by inhibition of tenascin deposition. Selective reduction of eosinophils by anti‐IL‐5 was also associated with a significant reduction in the up‐regulated expression of ECM proteins in the reticular basement membrane of asthmatics. Furthermore, this reduction in the expression of matrix proteins occurred over a relatively short time period and despite only partial eosinophil depletion. Taken together these data provide direct evidence of a causal association between eosinophils and ECM protein deposition in mild atopic asthma.