Syndecan-2 is a novel target of insulin-like growth factor binding protein-3 and is over-expressed in fibrosis

The Relationship between Time, Race, and Estrogen Receptor Alpha in Estradiol-Induced Dermal Fibrosis

In the skin, estradiol (E2) promotes profibrotic and proinflammatory cytokines, contributing to extracellular matrix (ECM) deposition. However, the magnitude of the response differs. Using the human skin organ culture model, we evaluated donor characteristics and correlations that contribute to E2-induced interleukin-6 (IL-6), transforming growth factor beta 1 and 2 (TGFB1 and TGFB2), collagen IA2 (Col IA2), collagen IIIA1 (Col IIIA1), and fibronectin (FN) expressions. In vehicle- and E2-treated dermal skin tissue transcripts, we confirm differences in the magnitude; however, there were positive correlations between profibrotic mediators and ECM components 48 h after E2 treatment. Also, positive correlations exist between baseline and E2-induced TGFB1, IL-6, Col IIIA1, and FN transcripts. Since estrogen receptor alpha (ERA) can propagate E2's signal, we measured and detected differences in its baseline and fold change transcript levels, with a significant decline in baseline levels 48 h after incubation and an increase 48 h after E2 treatment. There was a trend to higher transcript levels in African American donors 24 h earlier. Finally, E2-induced ERA transcript levels negatively correlated with its own baseline levels and positively correlated with FN, TGFB1, and Col IA2 transcript levels. Therefore, our data suggest ERA, E2 exposure time, and race/ethnicity contribute to E2-induced dermal fibrosis.

Evaluating the clinical performance of SDC2/NDRG4 methylation for colorectal cancer detection

Purpose: The performance and clinical accuracy of combined SDC2/NDRG4 methylation were evaluated in diagnosing colorectal cancer (CRC) and advanced adenoma. Methods: A total of 2333 participants were enrolled to assess the sensitivity and specificity of biomarkers in diagnosing CRC in a multicenter clinical trial through feces DNA methylation tests. Results: SDC2/NDRG4 methylation showed excellent performance for CRC detection in biomarker research and the real world. Its sensitivity for detecting CRC, early CRC and advanced adenoma were 92.06%, 91.45% and 62.61%, respectively. Its specificity was 94.29%, with a total coincidence rate of 88.28%. When interference samples were included, the specificity was still good (82.61%). Therefore, the SDC2/NDRG4 methylation test showed excellent performance in detecting CRC and advanced adenoma under clinical application.

Integrated Bioinformatic Analysis of Differentially Expressed Genes Associated with Wound Healing

OBJECTIVE

Wound healing is a complex process involving the coordinated interaction of various genes and molecular
pathways. The study aimed to uncover novel therapeutic targets, biomarkers and candidate genes for drug development
to improve successful wound repair interventions.
Materials and Methods: This study is a network-meta analysis study. Nine wound healing microarray datasets obtained
from the Gene Expression Omnibus (GEO) database were used for this study. Differentially expressed genes (DEGs)
were described using the Limma package and shared genes were used as input for weighted gene co-expression
network analysis. The Gene Ontology analysis was performed using the EnrichR web server, and construction of a
protein-protein interaction (PPI) network was achieved by the STRING and Cytoscape.
Results: A total of 424 DEGs were determined. A co-expression network was constructed using 7692 shared genes
between nine data sets, resulting in the identification of seven modules. Among these modules, those with the top 20
genes of up and down-regulation were selected. The top down-regulated genes, including TJP1, SEC61A1, PLEK,
ATP5B, PDIA6, PIK3R1, SRGN, SDC2, and RBBP7, and the top up-regulated genes including RPS27A, EEF1A1,
HNRNPA1, CTNNB1, POLR2A, CFL1, CSNk1E, HSPD1, FN1, and AURKB, which can potentially serve as therapeutic
targets were identified. The KEGG pathway analysis found that the majority of the genes are enriched in the "Wnt
signaling pathway".
Conclusion: In our study of nine wound healing microarray datasets, we identified DEGs and co-expressed modules
using WGCNA. These genes are involved in important cellular processes such as transcription, translation, and posttranslational
modifications. We found nine down-regulated genes and ten up-regulated genes, which could serve as
potential therapeutic targets for further experimental validation. Targeting pathways related to protein synthesis and cell
adhesion and migration may enhance wound healing, but additional experimental validation is needed to confirm the
effectiveness and safety of targeted interventions.

Integrative single-cell transcriptome analysis provides new insights into post-COVID-19 pulmonary fibrosis and potential therapeutic targets

The global COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 virus has resulted in a significant number of patients experiencing persistent symptoms, including post-COVID pulmonary fibrosis (PCPF). This study aimed to identify novel therapeutic targets for PCPF using single-cell RNA-sequencing data from lung tissues of COVID-19 patients, idiopathic pulmonary fibrosis (IPF) patients, and a rat transforming growth factor beta-1-induced fibrosis model treated with antifibrotic drugs. Patients with COVID-19 had lower alveolar macrophage counts than healthy controls, whereas patients with COVID-19 and IPF presented with elevated monocyte-derived macrophage counts. A comparative transcriptome analysis showed that macrophages play a crucial role in IPF and COVID-19 development and progression, and fibrosis- and inflammation-associated genes were upregulated in both conditions. Functional enrichment analysis revealed the upregulation of inflammation and proteolysis and the downregulation of ribosome biogenesis. Cholesterol efflux and glycolysis were augmented in both macrophage types. The study suggests that antifibrotic drugs may reverse critical lung fibrosis mediators in COVID-19. The results help clarify the molecular mechanisms underlying pulmonary fibrosis in patients with severe COVID-19 and IPF and highlight the potential efficacy of antifibrotic drugs in COVID-19 therapy. Collectively, all these findings may have significant implications for the development of new treatment strategies for PCPF.

Potential biomarkers for diagnosis and disease evaluation of idiopathic pulmonary fibrosis

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease characterized by progressive lung fibrogenesis and histological features of usual interstitial pneumonia. IPF has a poor prognosis and presents a spectrum of disease courses ranging from slow evolving disease to rapid deterioration; thus, a differential diagnosis remains challenging. Several biomarkers have been identified to achieve a differential diagnosis; however, comprehensive reviews are lacking. This review summarizes over 100 biomarkers which can be divided into six categories according to their functions: differentially expressed biomarkers in the IPF compared to healthy controls; biomarkers distinguishing IPF from other types of interstitial lung disease; biomarkers differentiating acute exacerbation of IPF from stable disease; biomarkers predicting disease progression; biomarkers related to disease severity; and biomarkers related to treatment. Specimen used for the diagnosis of IPF included serum, bronchoalveolar lavage fluid, lung tissue, and sputum. IPF-specific biomarkers are of great clinical value for the differential diagnosis of IPF. Currently, the physiological measurements used to evaluate the occurrence of acute exacerbation, disease progression, and disease severity have limitations. Combining physiological measurements with biomarkers may increase the accuracy and sensitivity of diagnosis and disease evaluation of IPF. Most biomarkers described in this review are not routinely used in clinical practice. Future large-scale multicenter studies are required to design and validate suitable biomarker panels that have diagnostic utility for IPF.

Heparan sulfate proteoglycans (HSPGs) of the ocular lens

Heparan sulfate proteoglycans (HSPGs) reside in most cells; on their surface, in the pericellular milieu and/or extracellular matrix. In the eye, HSPGs can orchestrate the activity of key signalling molecules found in the ocular environment that promote its development and homeostasis. To date, our understanding of the specific roles played by individual HSPG family members, and the heterogeneity of their associated sulfated HS chains, is in its infancy. The crystalline lens is a relatively simple and well characterised ocular tissue that provides an ideal stage to showcase and model the expression and unique roles of individual HSPGs. Individual HSPG core proteins are differentially localised to eye tissues in a temporal and spatial developmental- and cell-type specific manner, and their loss or functional disruption results in unique phenotypic outcomes for the lens, and other ocular tissues. More recent work has found that different HS sulfation enzymes are also presented in a cell- and tissue-specific manner, and that disruption of these different sulfation patterns affects specific HS-protein interactions. Not surprisingly, these sulfated HS chains have also been reported to be required for lens and eye development, with dysregulation of HS chain structure and function leading to pathogenesis and eye-related phenotypes. In the lens, HSPGs undergo significant and specific changes in expression and function that can drive pathology, or in some cases, promote tissue repair. As master signalling regulators, HSPGs may one day serve as valuable biomarkers, and even as putative targets for the development of novel therapeutics, not only for the eye but for many other systemic pathologies.

The Molecular Mechanisms of Systemic Sclerosis-Associated Lung Fibrosis

Systemic sclerosis (SSc), also known as scleroderma, is an autoimmune disorder that affects the connective tissues and has the highest mortality rate among the rheumatic diseases. One of the hallmarks of SSc is fibrosis, which may develop systemically, affecting the skin and virtually any visceral organ in the body. Fibrosis of the lungs leads to interstitial lung disease (ILD), which is currently the leading cause of death in SSc. The identification of effective treatments to stop or reverse lung fibrosis has been the main challenge in reducing SSc mortality and improving patient outcomes and quality of life. Thus, understanding the molecular mechanisms, altered pathways, and their potential interactions in SSc lung fibrosis is key to developing potential therapies. In this review, we discuss the diverse molecular mechanisms involved in SSc-related lung fibrosis to provide insights into the altered homeostasis state inherent to this fatal disease complication.

In Vitro, Ex Vivo, and In Vivo Approaches for Investigation of Skin Scarring: Human and Animal Models

Significance: The cutaneous repair process naturally results in different types of scarring that are classified as normal or pathological. Affected individuals are often affected from an esthetic, physical (functional), and psychosocial perspective. The distinct nature of scarring in humans, particularly the formation of pathological scars, makes the study of skin scarring a challenge for researchers in this area. Several established experimental models exist for studying scar formation. However, the increasing development and validation of newly emerging models have made it possible to carry out studies focused on different variables that influence this unique process. Recent Advances: Experimental models such as in vitro, ex vivo, and in vivo models have obtained different degrees of success in the reproduction of the scar formation in its native milieu and true environment. These models also differ in their ability to elucidate the molecular, cellular, and structural mechanisms involved in scarring, as well as for testing new agents and approaches for therapies. The models reviewed here, including cells derived from human skin and in vivo animal models, have contributed to the advancement of skin scarring research. Critical Issues and Future Directions: The absence of experimental models that faithfully reproduce the typical characteristics of the different types of human skin scars makes the improvement of validated models and the establishment of new ones a critical unmet need. The fields of wound healing research combined with tissue engineering have offered newer alternatives for experimental studies with the potential to provide clinically useful knowledge about scar formation.

Syndecan-2 selectively regulates VEGF-induced vascular permeability

Vascular endothelial growth factor (VEGF)- driven increase in vascular permeability is a key feature of many disease states associated with inflammation and ischemic injury, contributing significantly to morbidity and mortality in these settings. Despite its importance, no specific regulators that preferentially control VEGF-dependent increase in permeability versus its other biological activities, have been identified. Here we report that a proteoglycan Syndecan-2 (Sdc2) regulates the interaction between a transmembrane phosphatase DEP1 and VEGFR2 by controlling cell surface levels of DEP1. In the absence of Sdc2 or the presence of an antibody that blocks Sdc2-DEP1 interaction, increased plasma membrane DEP1 levels promote selective dephosphorylation of the VEGFR2 Y951 site that is involved in permeability control. Either an endothelial-specific Sdc2 deletion or a treatment with an anti-Sdc2 antibody result in a highly significant reduction in stroke size due to a decrease in intracerebral edema.

Syndecan receptors: pericellular regulators in development and inflammatory disease

The syndecans are the major family of transmembrane proteoglycans, usually bearing multiple heparan sulfate chains. They are present on virtually all nucleated cells of vertebrates and are also present in invertebrates, indicative of a long evolutionary history. Genetic models in both vertebrates and invertebrates have shown that syndecans link to the actin cytoskeleton and can fine-tune cell adhesion, migration, junction formation, polarity and differentiation. Although often associated as co-receptors with other classes of receptors (e.g. integrins, growth factor and morphogen receptors), syndecans can nonetheless signal to the cytoplasm in discrete ways. Syndecan expression levels are upregulated in development, tissue repair and an array of human diseases, which has led to the increased appreciation that they may be important in pathogenesis not only as diagnostic or prognostic agents, but also as potential targets. Here, their functions in development and inflammatory diseases are summarized, including their potential roles as conduits for viral pathogen entry into cells.

Cell-surface heparan sulfate proteoglycans as multifunctional integrators of signaling in cancer

Proteoglycans (PGs) represent a large proportion of the components that constitute the extracellular matrix (ECM). They are a diverse group of glycoproteins characterized by a covalent link to a specific glycosaminoglycan type. As part of the ECM, heparan sulfate (HS)PGs participate in both physiological and pathological processes including cell recruitment during inflammation and the promotion of cell proliferation, adhesion and motility during development, angiogenesis, wound repair and tumor progression. A key function of HSPGs is their ability to modulate the expression and function of cytokines, chemokines, growth factors, morphogens, and adhesion molecules. This is due to their capacity to act as ligands or co-receptors for various signal-transducing receptors, affecting pathways such as FGF, VEGF, chemokines, integrins, Wnt, notch, IL-6/JAK-STAT3, and NF-κB. The activation of those pathways has been implicated in the induction, progression, and malignancy of a tumor. For many years, the study of signaling has allowed for designing specific drugs targeting these pathways for cancer treatment, with very positive results. Likewise, HSPGs have become the subject of cancer research and are increasingly recognized as important therapeutic targets. Although they have been studied in a variety of preclinical and experimental models, their mechanism of action in malignancy still needs to be more clearly defined. In this review, we discuss the role of cell-surface HSPGs as pleiotropic modulators of signaling in cancer and identify them as promising markers and targets for cancer treatment.

The Cardiac Syndecan-2 Interactome

The extracellular matrix (ECM) is important in cardiac remodeling and syndecans have gained increased interest in this process due to their ability to convert changes in the ECM to cell signaling. In particular, syndecan-4 has been shown to be important for cardiac remodeling, whereas the role of its close relative syndecan-2 is largely unknown in the heart. To get more insight into the role of syndecan-2, we here sought to identify interaction partners of syndecan-2 in rat left ventricle. By using three different affinity purification methods combined with mass spectrometry (MS) analysis, we identified 30 novel partners and 9 partners previously described in the literature, which together make up the first cardiac syndecan-2 interactome. Eleven of the novel partners were also verified in HEK293 cells (i.e., AP2A2, CAVIN2, DDX19A, EIF4E, JPH2, MYL12A, NSF, PFDN2, PSMC5, PSMD11, and RRAD). The cardiac syndecan-2 interactome partners formed connections to each other and grouped into clusters mainly involved in cytoskeletal remodeling and protein metabolism, but also into a cluster consisting of a family of novel syndecan-2 interaction partners, the CAVINs. MS analyses revealed that although syndecan-2 was significantly enriched in fibroblast fractions, most of its partners were present in both cardiomyocytes and fibroblasts. Finally, a comparison of the cardiac syndecan-2 and -4 interactomes revealed surprisingly few protein partners in common.

Interplay between Cell-Surface Receptors and Extracellular Matrix in Skin

Skin consists of the epidermis and dermis, which are connected by a specialized basement membrane-the epidermal basement membrane. Both the epidermal basement membrane and the underlying interstitial extracellular matrix (ECM) created by dermal fibroblasts contain distinct network-forming macromolecules. These matrices play various roles in order to maintain skin homeostasis and integrity. Within this complex interplay of cells and matrices, cell surface receptors play essential roles not only for inside-out and outside-in signaling, but also for establishing mechanical and biochemical properties of skin. Already minor modulations of this multifactorial cross-talk can lead to severe and systemic diseases. In this review, major epidermal and dermal cell surface receptors will be addressed with respect to their interactions with matrix components as well as their roles in fibrotic, inflammatory or tumorigenic skin diseases.

Pulmonary involvement in systemic sclerosis: exploring cellular, genetic and epigenetic mechanisms

Systemic sclerosis (SSc) is a chronic progressive autoimmune disease characterized by immune inflammation, vasculopathy, and fibrosis. There are still numerous uncertainties in the understanding of disease initiation and progression. Pulmonary involvement in SSc, and particularly pulmonary fibrosis, is critical for all organ systems affections in this disease. This review is aimed to describe and analyze new findings in the pathophysiology of SSc-associated pulmonary involvement and to explore perspective diagnostic and therapeutic strategies. A myriad of cellular interactions is explored in the dynamics of progressive interstitial lung disease (ILD) and pulmonary hypertension (PH) in SSc. The role of exosomes, microvesicles, and apoptotic bodies is examined and the impact of micro and long non-coding RNAs, DNA methylation, and histone modification in SSc is discussed.

GIPC-Regulated IGFBP-3 Promotes HSC Migration In Vitro and Portal Hypertension In Vivo Through a β1-Integrin Pathway

BACKGROUND & AIMS

Transforming growth factor (TGF-β)-induced activation of quiescent hepatic stellate cells (HSCs) and their transformation to myofibroblasts is a key event in liver fibrosis and portal hypertension. GIPC (also referred to as synectin) is a downstream signal activation molecule of TGF-β and other receptors. In this study, we sought to identify novel genes targeted by TGF-β and GIPC and elucidate if and how they may contribute to liver fibrosis.

METHODS

We performed sequential messenger RNA sequencing analysis on TGF-β-stimulated HSCs and then on TGF-β-stimulated HSCs in the presence and absence of GIPC also referred to as synectin (GIPC) knockdown. Insulin-like growth factor binding protein-3 (IGFBP-3) transport protein emerged as a top activation target of both TGF-β and GIPC. Quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, targeted chromatin immunoprecipitation, and Western blot analysis were done for further confirmation.

RESULTS

IGFBP-3, an insulin growth factor transport protein, emerged as a top activation target of both TGF-β and GIPC, which was confirmed by quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blot analysis. Targeted chromatin immunoprecipitation showed that GIPC increases the histone 3 lysine 27 (H3K27) acetylation activating mark and concurrently decreases the H3K27 inhibitory trimethylation (H3K27m3) mark, providing an epigenetic correlate to the gene regulation changes. In vivo, global knockout of IGFBP-3 mice resulted in attenuation of HSC activation markers and attenuation of portal pressure in response to chronic liver injury models. Analysis of serum levels from cirrhotic patients also showed an IGFBP-3 increase of more than 2-fold compared with healthy controls. Finally, in vitro mechanism studies showed that IGFBP-3 promotes HSC migration through integrin-dependent phosphorylation of protein kinase B.

CONCLUSIONS

TGF-β up-regulates IGFBP-3 through GIPC, leading to increased HSC migration in vitro and promotes portal hypertension in vivo. These studies support the role of IGFBP-3 as a potential pathophysiologic target or biomarker in chronic liver disease.

Molecular insights and immune responses of big belly seahorse syndecan-2 (CD362): Involvement of ectodomain in regulating cell survival, proliferation, and wound healing

Syndecan-2, also known as CD362, is a transmembrane heparan sulfate proteoglycan which regulates cell growth, proliferation, cell adhesion, wound healing, and recruits immune cells. In the present study, we performed bioinformatics, spatial and temporal expression analyses of Hippocampus abdominalis syndecan-2 (HaSDC-2). Additionally, functional assays were conducted. HaSDC-2 has five major domains; an extracellular heparan sulfate attachment domain, a co-receptor binding domain, a transmembrane domain, two conserved domains (C1 domain, C2 domain), and a variable (V) domain. The ectodomain contained a signal peptide and GAG attachment sites. In-silico analysis revealed that HaSDC-2 contained a 798 bp long ORF and protein sequence of 265 amino acid residues. Further analysis of the amino acid sequence predicted a 28.9 kDa molecular weight and a 4.13 theoretical isoelectric point. The spatial expression of HaSDC-2 was ubiquitous in all tested tissues. HaSDC-2 expression in the liver was upregulated 24 h post-injection in response to all stimuli. Further, HaSDC-2 expression in blood cells was upregulated at 12 and 72 h post-injection in response to all the stimuli. HaSDC-2 + pcDNA™3.1(+) transfected cells exhibited significant survival in response to cell stressors such as H₂O₂ and HED. The ectodomain of recombinant HaSDC-2 treated cells showed significant cell proliferation in a concentration-dependent manner. The scratch wound healing assay showed significant Δ gap closures with increasing concentrations of HaSDC-2. Collectively, these results indicated that syndecan-2 was involved in regulating immune responses and cell stress conditions.

Cross-Talk between Transforming Growth Factor-β and Periostin Can Be Targeted for Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized as progressive and irreversible fibrosis in the interstitium of lung tissues. There is still an unmet need to develop a novel therapeutic drug for IPF. We have previously demonstrated that periostin, a matricellular protein, plays an important role in the pathogenesis of pulmonary fibrosis. However, the underlying mechanism of how periostin causes pulmonary fibrosis remains unclear. In this study, we sought to learn whether the cross-talk between TGF-β (transforming growth factor-β), a central mediator in pulmonary fibrosis, and periostin in lung fibroblasts leads to generation of pulmonary fibrosis and whether inhibitors for integrin αVβ3, a periostin receptor, can block pulmonary fibrosis in model mice and the TGF-β signals in fibroblasts from patients with IPF. We found that cross-talk exists between TGF-β and periostin signals via αVβ3/β5 converging into Smad3. This cross-talk is necessary for the expression of TGF-β downstream effector molecules important for pulmonary fibrosis. Moreover, we identified several potent integrin low-molecular-weight inhibitors capable of blocking cross-talk with TGF-β signaling. One of the compounds, CP4715, attenuated bleomycin-induced pulmonary fibrosis in vivo in mice and the TGF-β signals in vitro in fibroblasts from patients with IPF. These results suggest that the cross-talk between TGF-β and periostin can be targeted for pulmonary fibrosis and that CP4715 can be a potential therapeutic agent to block this cross-talk.

Syndecan-4 Inhibits the Development of Pulmonary Fibrosis by Attenuating TGF-β Signaling

Syndecan-4 is a transmembrane heparan sulfate proteoglycan expressed in a variety of cells, and its heparan sulfate glycosaminoglycan side chains bind to several proteins exhibiting various biological roles. The authors have previously demonstrated syndecan-4′s critical roles in pulmonary inflammation. In the current study, however, its role in pulmonary fibrosis was evaluated. Wild-type and syndecan-4-deficient mice were injected with bleomycin, and several parameters of inflammation and fibrosis were analyzed. The mRNA expression of collagen and α-smooth muscle action (α-SMA) in lung tissues, as well as the histopathological lung fibrosis score and collagen content in lung tissues, were significantly higher in the syndecan-4-deficient mice. However, the total cell count and cell differentiation in bronchoalveolar lavage fluid were equivalent between the wild-type and syndecan-4-deficient mice. Although there was no difference in the TGF-β expression in lung tissues between the wild-type and syndecan-4-deficient mice, significantly more activation of Smad3 in lung tissues was observed in the syndecan-4-deficient mice compared to the wild-type mice. Furthermore, in the in vitro experiments using lung fibroblasts, the co-incubation of syndecan-4 significantly inhibited TGF-β-induced Smad3 activation, collagen and α-SMA upregulation. Moreover, syndecan-4 knock-down by siRNA increased TGF-β-induced Smad3 activation and upregulated collagen and α-SMA expression. These findings showed that syndecan-4 inhibits the development of pulmonary fibrosis, at least in part, through attenuating TGF-β signaling.

Interferon-γ enhances the antifibrotic effects of pirfenidone by attenuating IPF lung fibroblast activation and differentiation

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) pathogenesis involves multiple pathways, and combined antifibrotic therapy is needed for future IPF therapy. Inhaled interferon-γ (IFN-γ) was recently shown to be safe and without systemic effects in patients with IPF.

AIM

To examine the in vitro effects of individual and combined treatment with IFN-γ and pirfenidone (PFD) on normal and IPF fibroblast activation and extracellular matrix remodeling after TGF-β1 and PDGF-BB stimulation.

METHODS

IPF and normal human lung fibroblasts (NHLF) were treated with IFN-γ, PFD or a combination of both drugs in the presence of either TGF-β1 or PDGF-BB. The effects of TGF-β1 and PDGF-BB treatment on cell viability, proliferation, differentiation and migration were examined. The expression of collagen 1, matrix metalloproteinases (MMPs) and tissue inhibitors of MMP (TIMPs) was analyzed using qPCR, Western blotting and gelatin zymography. Total collagen content in conditioned media was also measured using a Sircol assay.

RESULTS

Compared to that of PFD, the effect of IFN-γ in downregulating normal and IPF lung fibroblast differentiation to myofibroblasts in response to TGF-β1 was more potent. Importantly, the combination of IFN-γ and PFD had a possibly synergistic/additive effect in inhibiting the TGF-β1- and PDGF-BB-induced proliferation, migration and differentiation of normal and IPF lung fibroblasts. Furthermore, both drugs reversed TGF-β1-induced effects on MMP-1, - 2, - 3, - 7, and - 9, while only PFD promoted TIMP-1 and-2 expression and release.

CONCLUSIONS

Our findings demonstrate that the antifibrotic effects of IFN-γ and PFD on normal and IPF lung fibroblasts are different and complementary. Combination therapy with inhaled IFN-γ and PFD in IPF is promising and should be further explored in IPF clinical trials.

Use of cholesterol and soluble tumour markers CEA and syndecan-2 in pleural effusions in cases of inconclusive cytology

Aims

In order to improve diagnostics in pleural effusions, additional value of effusion cholesterol, carcinoembryonic antigen (CEA) and syndecan-2 assays to cytology was studied.

Methods

Biomarkers were measured in effusion supernatants from 247 patients, of whom 126 had malignant pleural involvement, and their additional diagnostic efficacy to cytology was assessed.

Results

Syndecan-2 measurement, although gave detectable concentrations in all effusions with highest median value in mesotheliomas, was non-discriminative between different pathological conditions. CEA concentrations exceeding 5 ng/mL cut-off point indicated carcinomas, regardless of pleural involvement, which gave a sensitivity of 62% and specificity of 100% for carcinoma. Cholesterol concentration over 1.21 mmol/L cut-off value indicated neoplastic pleural involvement with 99% sensitivity and ‘merely’ 69% specificity, the latter mainly due to raised levels being associated also with benign inflammatory effusions. Combined CEA and cholesterol determinations increased the sensitivity for diagnosing carcinomatosis from 70% with cytology alone to 84% and established the correct diagnosis in 16 of 31 carcinomatosis cases with inconclusive cytology. Cholesterol measurement alone, with elevated level, in combination with absence of substantial number of inflammatory cells in effusion sediment proved to be a magnificent marker for neoplastic pleural involvement with 99% efficacy, and recognised all 36 such cases with inconclusive cytology.

Conclusions

Simultaneous measurement of CEA and cholesterol concentrations in effusion, or at least cholesterol alone, in combination with non-inflammatory fluid cytology, provides additional specific information about neoplastic pleural involvement, and can therefore be used as an adjunct to cytology, above all, in inconclusive cases.

Proteomic profile of TGF-β1 treated lung fibroblasts identifies novel markers of activated fibroblasts in the silica exposed rat lung

We performed liquid chromatography-tandem mass spectrometry (LC-MS/MS) on control and TGF-β1-exposed rat lung fibroblasts to identify proteins differentially expressed between cell populations. A total of 196 proteins were found to be differentially expressed in response to TGF-β1 treatment. Guided by these results, we next determined whether similar changes in protein expression were detectable in the rat lung after chronic exposure to silica dust. Of the five proteins selected for further analysis, we found that levels of all proteins were markedly increased in the silica-exposed rat lung, including the proteins for the very low density lipoprotein receptor (VLDLR) and the transmembrane (type I) heparin sulfate proteoglycan called syndecan 2 (SDC2). Because VLDLR and SDC2 have not, to our knowledge, been previously linked to the pathobiology of silicosis, we next examined whether knockdown of either gene altered responses to TGF-β1 in MRC-5 lung fibroblasts. Interestingly, we found knockdown of either VLDLR or SDC2 dramatically reduced collagen production to TGF-β1, suggesting that both proteins might play a novel role in myofibroblast biology and pathogenesis of silica-induced pulmonary fibrosis. In summary, our findings suggest that performing LC-MS/MS on TGF-β1 stimulated lung fibroblasts can uncover novel molecular targets of activated myofibroblasts in silica-exposed lung.

Spotlight on the Transglutaminase 2-Heparan Sulfate Interaction

Heparan sulfate proteoglycans (HSPGs), syndecan-4 (Sdc4) especially, have been suggested as potential partners of transglutaminase-2 (TG2) in kidney and cardiac fibrosis, metastatic cancer, neurodegeneration and coeliac disease. The proposed role for HSPGs in the trafficking of TG2 at the cell surface and in the extracellular matrix (ECM) has been linked to the fibrogenic action of TG2 in experimental models of kidney fibrosis. As the TG2-HSPG interaction is largely mediated by the heparan sulfate (HS) chains of proteoglycans, in the past few years a number of studies have investigated the affinity of TG2 for HS, and the TG2 heparin binding site has been mapped with alternative outlooks. In this review, we aim to provide a compendium of the main literature available on the interaction of TG2 with HS, with reference to the pathological processes in which extracellular TG2 plays a role.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

The apparent competitive action of ECM proteases and cross-linking enzymes during fibrosis: Applications to drug discovery

Progressive loss of organ function in most organs is associated with fibrosis, a tissue state associated with abnormal matrix buildup. If highly progressive, the fibrotic process eventually leads to organ failure and death. Fibrosis is a basic connective tissue lesion defined by the increase in the amount of fibrillar extracellular matrix (ECM) components in a tissue or organ. In addition, intrinsic changes in important structural cells can induce the fibrotic response by regulating the differentiation, recruitment, proliferation and activation of extracellular matrix-producing myofibroblasts. ECM enzymes belonging to the family of matrix metalloproteinases (MMPs) and lysyl oxidases (LOXs) play a crucial role in ECM remodeling and regeneration. MMPs have a catalytic role in degradation of ECM, whereas LOX/LOXLs mediate ECM, especially collagen, cross-linking and stiffening. Importantly, enzymes from both families are elevated during the fibrotic response to tissue injury and its resolution. Yet, the apparent molecular competition or antagonistic activities of these enzyme families during the various stages of fibrosis is often overlooked. In this review, we discuss the diverse roles of MMPs and LOX/LOXL2 in chronic organ fibrosis. Finally, we review contemporary therapeutic strategies for fibrosis treatment, based on neutralization of MMP and LOX activity, as well as the development of novel drug delivery approaches.

Extracellular matrix remodeling in idiopathic pulmonary fibrosis. It is the 'bed' that counts and not 'the sleepers'

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease characterized by irreversible fibrosis. Current disease pathogenesis assumes an aberrant wound healing process in response to repetitive injurious stimuli leading to apoptosis of epithelial cells, activation of fibroblasts and accumulation of extracellular matrix (ECM). Particularly, lung ECM is a highly dynamic structure that lies at the core of several physiological and developmental pathways. The scope of this review article is to summarize current knowledge on the role of ECM in the pathogenesis of IPF, unravel novel mechanistic data and identify future more effective therapeutic targets. Areas covered: The exact mechanisms through which lung microenvironment activates fibroblasts and inflammatory cells, regulates profibrotic signaling cascades through growth factors, integrins and degradation enzymes ultimately leading to excessive matrix deposition are discussed. Furthermore, the potential therapeutic usefulness of specific inhibitors of matrix deposition or activators of matrix degradation pathways are also presented. Expert commentary: With a gradually increasing worldwide incidence IPF still present a major challenge in clinical research due to its unknown etiopathogenesis and current ineffective treatment approaches. Today, there is an amenable need for more effective therapeutic targets and ECM components may represent one.

Increased deposition of glycosaminoglycans and altered structure of heparan sulfate in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant deposition of extracellular matrix (ECM) constituents, including glycosaminoglycans (GAGs), that may play a role in remodelling processes by influencing critical mediators such as growth factors. We hypothesize that GAGs may be altered in IPF and that this contribute to create a pro-fibrotic environment. The aim of this study was therefore to examine the fine structure of heparan sulfate (HS), chondroitin/dermatan sulfate (CS/DS) and hyaluronan (HA) in lung samples from IPF patients and from control subjects. GAGs in lung samples from severe IPF patients and donor lungs were analyzed with HPLC. HS was assessed by immunohistochemistry and collagen was quantified as hydroxyproline content. The total amount of HS, CS/DS and HA was increased in IPF lungs but there was no significant difference in the total collagen content. We found a relative increase in total sulfation of HS due to increment of 2-O, 6-O and N-sulfation and a higher proportion of sulfation in CS/DS. Highly sulfated HS was located in the border zone between denser areas and more normal looking alveolar parenchyma in basement membranes of blood vessels and airways, that were immuno-positive for perlecan, as well as on the cell surface of spindle-shaped cells in the alveolar interstitium. These findings show for the first time that both the amount and structure of glycosaminoglycans are altered in IPF. These changes may contribute to the tissue remodelling in IPF by altering growth factor retention and activity, creating a pro-fibrotic ECM landscape.

Matrix metalloproteinases as therapeutic targets for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a restrictive lung disease that is associated with high morbidity and mortality. Current medical therapies are not fully effective at limiting mortality in patients with IPF, and new therapies are urgently needed. Matrix metalloproteinases (MMPs) are proteinases that, together, can degrade all components of the extracellular matrix and numerous nonmatrix proteins. MMPs and their inhibitors, tissue inhibitors of MMPs (TIMPs), have been implicated in the pathogenesis of IPF based upon the results of clinical studies reporting elevated levels of MMPs (including MMP-1, MMP-7, MMP-8, and MMP-9) in IPF blood and/or lung samples. Surprisingly, studies of gene-targeted mice in murine models of pulmonary fibrosis (PF) have demonstrated that most MMPs promote (rather than inhibit) the development of PF and have identified diverse mechanisms involved. These mechanisms include MMPs: (1) promoting epithelial-to-mesenchymal transition (MMP-3 and MMP-7); (2) increasing lung levels or activity of profibrotic mediators or reducing lung levels of antifibrotic mediators (MMP-3, MMP-7, and MMP-8); (3) promoting abnormal epithelial cell migration and other aberrant repair processes (MMP-3 and MMP-9); (4) inducing the switching of lung macrophage phenotypes from M1 to M2 types (MMP-10 and MMP-28); and (5) promoting fibrocyte migration (MMP-8). Two MMPs, MMP-13 and MMP-19, have antifibrotic activities in murine models of PF, and two MMPs, MMP-1 and MMP-10, have the potential to limit fibrotic responses to injury. Herein, we review what is known about the contributions of MMPs and TIMPs to the pathogenesis of IPF and discuss their potential as therapeutic targets for IPF.

Similarities in Gene Expression Profiles during In Vitro Aging of Primary Human Embryonic Lung and Foreskin Fibroblasts

Replicative senescence is of fundamental importance for the process of cellular aging, since it is a property of most of our somatic cells. Here, we elucidated this process by comparing gene expression changes, measured by RNA-seq, in fibroblasts originating from two different tissues, embryonic lung (MRC-5) and foreskin (HFF), at five different time points during their transition into senescence. Although the expression patterns of both fibroblast cell lines can be clearly distinguished, the similar differential expression of an ensemble of genes was found to correlate well with their transition into senescence, with only a minority of genes being cell line specific. Clustering-based approaches further revealed common signatures between the cell lines. Investigation of the mRNA expression levels at various time points during the lifespan of either of the fibroblasts resulted in a number of monotonically up- and downregulated genes which clearly showed a novel strong link to aging and senescence related processes which might be functional. In terms of expression profiles of differentially expressed genes with age, common genes identified here have the potential to rule the transition into senescence of embryonic lung and foreskin fibroblasts irrespective of their different cellular origin.

Syndecan-1 and Its Expanding List of Contacts

Significance: The binding of cytokines and growth factors to heparan sulfate (HS) chains on proteoglycans generates gradients that control development and regulate wound healing. Syndecan-1 (sdc1) is an integral membrane HS proteoglycan. Its structure allows it to bind with cytosolic, transmembrane, and extracellular matrix (ECM) proteins. It plays important roles in mediating key events during wound healing because it regulates a number of important processes, including cell adhesion, cell migration, endocytosis, exosome formation, and fibrosis. Recent Advances: Recent studies reveal that sdc1 regulates wound healing by altering integrin activation. Differences in integrin activation lead to cell-type-specific changes in the rate of cell migration and ECM assembly. Sdc1 also regulates endocytosis and the formation and release of exosomes. Critical Issues: Understanding how sdc1 facilitates wound healing and resolution will improve treatment options for elderly and diabetic patients with delayed wound healing. Studies showing that sdc1 function is altered in cancer are relevant to those interested in controlling fibrosis and scarring. Future Directions: The key to understanding the various functions ascribed to sdc1 is resolving how it interacts with its numerous binding partners. The role played by chondroitin sulfate glycosaminoglycan (GAG) chains on the ability of sdc1 to associate with its ligands needs further investigation. At wound sites heparanase can cleave the HS GAG chains of sdc1, alter its ability to bind cytokines, and induce shedding of the ectodomain. This review will discuss how the unique structure of sdc1 allows it to play key roles in cell signaling, ECM assembly, and wound healing.

Cellular interactions in the pathogenesis of interstitial lung diseases

Interstitial lung disease (ILD) encompasses a large and diverse group of pathological conditions that share similar clinical, radiological and pathological manifestations, despite potentially having quite different aetiologies and comorbidities. Idiopathic pulmonary fibrosis (IPF) represents probably the most aggressive form of ILD and systemic sclerosis is a multiorgan fibrotic disease frequently associated with ILD. Although the aetiology of these disorders remains unknown, in this review we analyse the pathogenic mechanisms by cell of interest (fibroblast, fibrocyte, myofibroblast, endothelial and alveolar epithelial cells and immune competent cells). New insights into the complex cellular contributions and interactions will be provided, comparing the role of cell subsets in the pathogenesis of IPF and systemic sclerosis.

Distinct cell populations contribute to the complex pathogenesis of IPF and systemic sclerosis-associated ILDhttp://ow.ly/AjFaz

Fibroblasts in fibrosis: novel roles and mediators

Fibroblasts are the most common cell type of the connective tissues found throughout the body and the principal source of the extensive extracellular matrix (ECM) characteristic of these tissues. They are also the central mediators of the pathological fibrotic accumulation of ECM and the cellular proliferation and differentiation that occurs in response to prolonged tissue injury and chronic inflammation. The transformation of the fibroblast cell lineage involves classical developmental signaling programs and includes a surprisingly diverse range of precursor cell types—most notably, myofibroblasts that are the apex of the fibrotic phenotype. Myofibroblasts display exaggerated ECM production; constitutively secrete and are hypersensitive to chemical signals such as cytokines, chemokines, and growth factors; and are endowed with a contractile apparatus allowing them to manipulate the ECM fibers physically to close open wounds. In addition to ECM production, fibroblasts have multiple concomitant biological roles, such as in wound healing, inflammation, and angiogenesis, which are each interwoven with the process of fibrosis. We now recognize many common fibroblast-related features across various physiological and pathological protracted processes. Indeed, a new appreciation has emerged for the role of non-cancerous fibroblast interactions with tumors in cancer progression. Although the predominant current clinical treatments of fibrosis involve non-specific immunosuppressive and anti-proliferative drugs, a variety of potential therapies under investigation specifically target fibroblast biology.

Up-regulation of heparan sulfate 6-O-sulfation in idiopathic pulmonary fibrosis

Heparan sulfate proteoglycans (HSPGs) are integral components of the lung. Changes in HSPGs have been documented in idiopathic pulmonary fibrosis (IPF). Many of the biological functions of HSPGs are mediated by heparan sulfate (HS) side chains, and little is understood about these side chains in the pathogenesis of IPF. The aims of this study were to compare HS structure between normal and IPF lungs and to examine how changes in HS regulate the fibrotic process. HS disaccharide analysis revealed that HS 6-O-sulfation was significantly increased in IPF lungs compared with normal lungs, concomitant with overexpression of HS 6-O-sulfotransferases 1 and 2 (HS6ST1/2) mRNA. Immunohistochemistry revealed that HS6ST2 was specifically expressed in bronchial epithelial cells, including those lining the honeycomb cysts in IPF lungs, whereas HS6ST1 had a broad expression pattern. Lung fibroblasts in the fibroblastic foci of IPF lungs expressed HS6ST1, and overexpression of HS6ST1 mRNA was observed in primary lung fibroblasts isolated from IPF lungs compared with those from normal lungs. In vitro, small interference RNA-mediated silencing of HS6ST1 in primary normal lung fibroblasts resulted in reduced Smad2 expression and activation and in reduced expression of collagen I and α-smooth muscle actin after TGF-β1 stimulation. Similar results were obtained in primary IPF lung fibroblasts. Furthermore, silencing of HS6ST1 in normal and IPF lung fibroblasts resulted in significant down-regulation of TβRIII (betaglycan). In summary, HS 6-O-sulfation is up-regulated in IPF with overexpression of HS6ST1 and HS6ST2, and overexpression of HS6ST1 in lung fibroblasts may regulate their fibrotic responses to TGF-β1.

Syndecan-2 exerts antifibrotic effects by promoting caveolin-1-mediated transforming growth factor-β receptor I internalization and inhibiting transforming growth factor-β1 signaling

RATIONALE

Alveolar transforming growth factor (TGF)-β1 signaling and expression of TGF-β1 target genes are increased in patients with idiopathic pulmonary fibrosis (IPF) and in animal models of pulmonary fibrosis. Internalization and degradation of TGF-β receptor TβRI inhibits TGF-β signaling and could attenuate development of experimental lung fibrosis.

OBJECTIVES

To demonstrate that after experimental lung injury, human syndecan-2 confers antifibrotic effects by inhibiting TGF-β1 signaling in alveolar epithelial cells.

METHODS

Microarray assays were performed to identify genes differentially expressed in alveolar macrophages of patients with IPF versus control subjects. Transgenic mice that constitutively overexpress human syndecan-2 in macrophages were developed to test the antifibrotic properties of syndecan-2. In vitro assays were performed to determine syndecan-2-dependent changes in epithelial cell TGF-β1 signaling, TGF-β1, and TβRI internalization and apoptosis. Wild-type mice were treated with recombinant human syndecan-2 during the fibrotic phase of bleomycin-induced lung injury.

MEASUREMENTS AND MAIN RESULTS

We observed significant increases in alveolar macrophage syndecan-2 levels in patients with IPF. Macrophage-specific overexpression of human syndecan-2 in transgenic mice conferred antifibrotic effects after lung injury by inhibiting TGF-β1 signaling and downstream expression of TGF-β1 target genes, reducing extracellular matrix production and alveolar epithelial cell apoptosis. In vitro, syndecan-2 promoted caveolin-1-dependent internalization of TGF-β1 and TβRI in alveolar epithelial cells, which inhibited TGF-β1 signaling and epithelial cell apoptosis. Therapeutic administration of human syndecan-2 abrogated lung fibrosis in mice.

CONCLUSIONS

Alveolar macrophage syndecan-2 exerts antifibrotic effects by promoting caveolin-1-dependent TGF-β1 and TβRI internalization and inhibiting TGF-β1 signaling in alveolar epithelial cells. Hence, molecules that facilitate TβRI degradation via endocytosis represent potential therapies for pulmonary fibrosis.