The Latent Form of TGFβ1is Induced by TNFα Through an ERK Specific Pathway and is Activated by Asbestos-Derived Reactive Oxygen SpeciesIn VitroandIn Vivo

Transforming growth factor-β receptors: versatile mechanisms of ligand activation

Transforming growth factor-β (TGF-β) signaling is initiated by activation of transmembrane TGF-β receptors (TGFBR), which deploys Smad2/3 transcription factors to control cellular responses. Failure or dysregulation in the TGF-β signaling pathways leads to pathological conditions. TGF-β signaling is regulated at different levels along the pathways and begins with the liberation of TGF-β ligand from its latent form. The mechanisms of TGFBR activation display selectivity to cell types, agonists, and TGF-β isoforms, enabling precise control of TGF-β signals. In addition, the cell surface compartments used to release active TGF-β are surprisingly vibrant, using thrombospondins, integrins, matrix metalloproteinases and reactive oxygen species. The scope of TGFBR activation is further unfolded with the discovery of TGFBR activation initiated by other signaling pathways. The unique combination of mechanisms works in series to trigger TGFBR activation, which can be explored as therapeutic targets. This comprehensive review provides valuable insights into the diverse mechanisms underpinning TGFBR activation, shedding light on potential avenues for therapeutic exploration.

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

Redox Biology and Liver Fibrosis

Hepatic fibrosis is a complex process that develops in chronic liver diseases. Even though the initiation and progression of fibrosis rely on the underlying etiology, mutual mechanisms can be recognized and targeted for therapeutic purposes. Irrespective of the primary cause of liver disease, persistent damage to parenchymal cells triggers the overproduction of reactive species, with the consequent disruption of redox balance. Reactive species are important mediators for the homeostasis of both hepatocytes and non-parenchymal liver cells. Indeed, other than acting as cytotoxic agents, reactive species are able to modulate specific signaling pathways that may be relevant to hepatic fibrogenesis. After a brief introduction to redox biology and the mechanisms of fibrogenesis, this review aims to summarize the current evidence of the involvement of redox-dependent pathways in liver fibrosis and focuses on possible therapeutic targets.

Oxidative Stress and Lung Fibrosis: Towards an Adverse Outcome Pathway

Lung fibrosis is a progressive fatal disease in which deregulated wound healing of lung epithelial cells drives progressive fibrotic changes. Persistent lung injury due to oxidative stress and chronic inflammation are central features of lung fibrosis. Chronic cigarette smoking causes oxidative stress and is a major risk factor for lung fibrosis. The objective of this manuscript is to develop an adverse outcome pathway (AOP) that serves as a framework for investigation of the mechanisms of lung fibrosis due to lung injury caused by inhaled toxicants, including cigarette smoke. Based on the weight of evidence, oxidative stress is proposed as a molecular initiating event (MIE) which leads to increased secretion of proinflammatory and profibrotic mediators (key event 1 (KE1)). At the cellular level, these proinflammatory signals induce the recruitment of inflammatory cells (KE2), which in turn, increase fibroblast proliferation and myofibroblast differentiation (KE3). At the tissue level, an increase in extracellular matrix deposition (KE4) subsequently culminates in lung fibrosis, the adverse outcome. We have also defined a new KE relationship between the MIE and KE3. This AOP provides a mechanistic platform to understand and evaluate how persistent oxidative stress from lung injury may develop into lung fibrosis.

LncRNAs and related molecular basis in malignant pleural mesothelioma: challenges and potential

Malignant pleural mesothelioma (MPM) is a rare but invasive cancer, which mainly arises from mesothelial tissues of pleura, peritoneum and pericardium. Despite significant advances in treatments, the prognosis of MPM patients remains poor, and the 5-year survival rate is less than 10%. Therefore, it is urgent to explore novel therapeutic targets for the treatment of MPM. Growing evidence has indicated that long non-coding RNAs (lncRNAs) potentially could be promising therapeutic targets for numerous cancers. In this regard, lncRNAs might also potentially therapeutic targets for MPM. Recent advances have been made to investigate the molecular basis of MPM. This review first provides a comprehensive overview of roles of lncRNAs in MPM and then discusses the relationship between molecular basis of MPM and MPM-related lncRNAs to implement them as promising therapeutic targets for MPM.

Transforming Growth Factor-β1 Regulates Peroxisomal Genes/Proteins via Smad Signaling in Idiopathic Pulmonary Fibrosis Fibroblasts and Transgenic Mouse Models

Idiopathic pulmonary fibrosis (IPF) is a chronic human disease with persistent destruction of lung parenchyma. Transforming growth factor-β1 (TGF-β1) signaling plays a pivotal role in the initiation and pathogenesis of IPF. As shown herein, TGF-β1 signaling down-regulated not only peroxisome biogenesis but also the metabolism of these organelles in human IPF fibroblasts. In vitro cell culture observations in human fibroblasts and human lung tissue indicated that peroxisomal biogenesis and metabolic proteins were significantly down-regulated in the lung of 1-month-old transgenic mice expressing a constitutively active TGF-β type I receptor kinase (ALK5). The peroxisome biogenesis protein peroxisomal membrane protein Pex13p (PEX13p) as well as the peroxisomal lipid metabolic enzyme peroxisomal acyl-coenzyme A oxidase 1 (ACOX1) and antioxidative enzyme catalase were highly up-regulated in TGF-β type II receptor and Smad3 knockout mice. This study reports a novel mechanism of peroxisome biogenesis and metabolic regulation via TGF-β1-Smad signaling: interaction of the Smad3 transcription factor with the PEX13 gene in chromatin immunoprecipitation-on-chip assay as well as in a bleomycin-induced pulmonary fibrosis model applied to TGF-β type II receptor knockout mice. Taken together, data from this study suggest that TGF-β1 participates in regulation of peroxisomal biogenesis and metabolism via Smad-dependent signaling, opening up novel strategies for the development of therapeutic approaches to inhibit progression of pulmonary fibrosis patients with IPF.

Effect of high glucose supplementation on pulmonary fibrosis involving reactive oxygen species and TGF-β

This study explored the profibrotic impact of high glucose in the lung and potential mechanisms using latent TGF-β1-induced human epithelial cell pulmonary fibrosis and bleomycin (BLM)-induced pulmonary fibrosis models. Results demonstrated that high glucose administration induced epithelial–mesenchymal transition (EMT) in human epithelial cells in a dose-dependent manner via activating latent TGF-β1, followed by increased expression of mesenchymal-related proteins and decreased expression of epithelial marker protein E-cadherin. Further mechanism analysis showed that administration of high glucose dose-dependently promoted total and mitochondrial reactive oxygen species (ROS) accumulation in human epithelial cells, which promoted latent TGF-β1 activation. However, N-acetyl-L-cysteine, a ROS eliminator, inhibited such effects. An in vivo feed study found that mice given a high-glucose diet had more seriously pathological characteristics of pulmonary fibrosis in BLM-treated mice, including increasing infiltrated inflammatory cells, collagen I deposition, and the expression of mesenchymal-related proteins while decreasing the expression of the epithelial marker E-cadherin. In addition, high glucose intake further increased TGF-β1 concentration and upregulated p-Smad2/3 and snail in lung tissues from BLM-treated mice when compared to BLM-treated mice. Finally, supplementation with high glucose further increased the production of lipid peroxidation metabolite malondialdehyde and decreased superoxide dismutase activity in BLM-treated mice. Collectively, these findings illustrate that high glucose supplementation activates a form of latent TGF-β1 by promoting ROS accumulation and ultimately exacerbates the development of pulmonary fibrosis.

Fructose Induces Pulmonary Fibrotic Phenotype Through Promoting Epithelial-Mesenchymal Transition Mediated by ROS-Activated Latent TGF-β1

Fructose is a commonly used food additive and has many adverse effects on human health, but it is unclear whether fructose impacts pulmonary fibrosis. TGF-β1, a potent fibrotic inducer, is produced as latent complexes by various cells, including alveolar epithelial cells, macrophages, and fibroblasts, and must be activated by many factors such as reactive oxygen species (ROS). This study explored the impact of fructose on pulmonary fibrotic phenotype and epithelial-mesenchymal transition (EMT) using lung epithelial cells (A549 or BEAS-2B) and the underlying mechanisms. Fructose promoted the cell viability of lung epithelial cells, while N-Acetyl-l-cysteine (NAC) inhibited such. Co-treatment of fructose and latent TGF-β1 could induce the fibrosis phenotype and the epithelial-mesenchymal transition (EMT)-related protein expression, increasing lung epithelial cell migration and invasion. Mechanism analysis shows that fructose dose-dependently promoted the production of total and mitochondrial ROS in A549 cells, while NAC eliminated this promotion. Notably, post-administration with NAC or SB431542 (a potent TGF-β type I receptor inhibitor) inhibited fibrosis phenotype and EMT process of lung epithelial cells co-treated with fructose and latent TGF-β1. Finally, the fibrosis phenotype and EMT-related protein expression of lung epithelial cells were mediated by the ROS-activated latent TGF-β1/Smad3 signal. This study revealed that high fructose promoted the fibrotic phenotype of human lung epithelial cells by up-regulating oxidative stress, which enabled the latent form of TGF-β1 into activated TGF-β1, which provides help and reference for the diet adjustment of healthy people and patients with fibrosis.

Sequential grade evaluation method exploration of Exocarpium Citri Grandis (Huajuhong) decoction pieces based on "network prediction → grading quantization → efficacy validation"

ETHNOPHARMACOLOGICAL RELEVANCE

Exocarpium Citri Grandis (Huajuhong) is an authentic Chinese materia medica with excellent curative effects on relieving cough and reducing phlegm, which has been reputed as "Southern Ginseng" in China for a long history.

AIM OF THE STUDY

To establish a sequential grade evaluation method with strong operability and controllable quality for Huajuhong decoction pieces.

MATERIALS AND METHODS

(1) Indicators of ingredients and bio-effects were predicted by network pharmacology, and the potential pharmacodynamic ingredients and key targets were analyzed integrating screening results and literatures. (2) 45 batches of Huajuhong decoction pieces from different producing areas were collected and graded by original plant, planting place, and harvesting time. The chemical indicators determination of Huajuhong decoction pieces was conducted by Ultra Performance Liquid Chromatography (UPLC). (3) 112 rats with idiopathic pulmonary fibrosis (IPF) model were used to evaluated the efficacy within graded groups.

RESULTS

(1) There are 22 key targets corresponding to 20 potential ingredients related to immunity and inflammation pathways for Huajuhong. Naringin and rhoifolin were chosen as the chemical indicators, and IL-6, IL-8, MCP-1, MIP-1α, TNF-α, TGF-β1 were selected as bio-indicators for different grades of Huajuhong decoction pieces. (2) The contents of the naringin and rhoifolin can reflect the quality of different grades of Huajuhong decoction pieces. (3) The efficacy of different grades of Huajuhong decoction pieces can delay the progression of IPF in varying degrees via the selected bio-indicators' pathways.

CONCLUSIONS

This sequential grading evaluation method is an attempt to apply systems pharmacology which integrates network pharmacology, quantitative chemical and experiments on animals to the classification of TCM decoction pieces. Combining the concepts of traditional theory and modern technology to explain the complex grading mechanism of TCM decoction pieces is worth popularizing and applying.

Sustained Club Cell Injury in Mice Induces Histopathologic Features of Deployment-Related Constrictive Bronchiolitis

Histopathologic evidence of deployment-related constrictive bronchiolitis (DRCB) has been identified in soldiers deployed to Southwest Asia. While inhalational injury to the airway epithelium is suspected, relatively little is known about the pathogenesis underlying this disabling disorder. Club cells are local progenitors critical for repairing the airway epithelium after exposure to various airborne toxins, and a prior study using an inducible transgenic murine model reported that 10 days of sustained targeted club cell injury causes constrictive bronchiolitis. To further understand the mechanisms leading to small airway fibrosis, a murine model was employed to show that sustained club cell injury elicited acute weight loss, caused increased local production of proinflammatory cytokines, and promoted accumulation of numerous myeloid cell subsets in the lung. Transition to a chronic phase was characterized by up-regulated expression of oxidative stress-associated genes, increased activation of transforming growth factor-β, accumulation of alternatively activated macrophages, and enhanced peribronchiolar collagen deposition. Comparative histopathologic analysis demonstrated that sustained club cell injury was sufficient to induce epithelial metaplasia, airway wall thickening, peribronchiolar infiltrates, and clusters of intraluminal airway macrophages that recapitulated key abnormalities observed in DRCB. Depletion of alveolar macrophages in mice decreased activation of transforming growth factor-β and ameliorated constrictive bronchiolitis. Collectively, these findings implicate sustained club cell injury in the development of DRCB and delineate pathways that may yield biomarkers and treatment targets for this disorder.

p62-Nrf2 Regulatory Loop Mediates the Anti-Pulmonary Fibrosis Effect of Bergenin

Idiopathic pulmonary fibrosis (IPF) can severely disrupt lung function, leading to fatal consequences, and there is currently a lack of specific therapeutic drugs. Bergenin is an isocoumarin compound with lots of biological functions including antioxidant activity. This study evaluated the potential beneficial effects of bergenin on pulmonary fibrosis and investigated the possible mechanisms. We found that bergenin alleviated bleomycin-induced pulmonary fibrosis by relieving oxidative stress, reducing the deposition of the extracellular matrix (ECM) and inhibiting the formation of myofibroblasts. Furthermore, we showed that bergenin could induce phosphorylation and expression of p62 and activation of Nrf2, Nrf2 was required for bergenin-induced p62 upregulation, and p62 knockdown reduced bergenin-induced Nrf2 activity. More importantly, knockdown of Nrf2 or p62 could abrogate the antioxidant activity of bergenin and the inhibition effect of bergenin on TGF-β-induced ECM deposition and myofibroblast differentiation. Thereby, a regulatory loop is formed between p62 and Nrf2, which is an important target for bergenin aimed at treating pulmonary fibrosis.

Esomeprazole attenuates inflammatory and fibrotic response in lung cells through the MAPK/Nrf2/HO1 pathway

Introduction

Idiopathic pulmonary fibrosis (IPF) is an orphan disease characterized by progressive loss of lung function resulting in shortness of breath and often death within 3–4 years of diagnosis. Repetitive lung injury in susceptible individuals is believed to promote chronic oxidative stress, inflammation, and uncontrolled collagen deposition. Several preclinical and retrospective clinical studies in IPF have reported beneficial outcomes associated with the use of proton pump inhibitors (PPIs) such as esomeprazole. Accordingly, we sought to investigate molecular mechanism(s) by which PPIs favorably regulate the disease process.

Methods

We stimulated oxidative stress, pro-inflammatory and profibrotic phenotypes in primary human lung epithelial cells and fibroblasts upon treatment with bleomycin or transforming growth factor β (TGFβ) and assessed the effect of a prototype PPI, esomeprazole, in regulating these processes.

Results

Our study shows that esomeprazole controls pro-inflammatory and profibrotic molecules through nuclear translocation of the transcription factor nuclear factor-like 2 (Nrf2) and induction of the cytoprotective molecule heme oxygenase 1 (HO1). Genetic deletion of Nrf2 or pharmacological inhibition of HO1 impaired esomeprazole-mediated regulation of proinflammatory and profibrotic molecules. Additional studies indicate that activation of Mitogen Activated Protein Kinase (MAPK) pathway is involved in the process. Our experimental data was corroborated by bioinformatics studies of an NIH chemical library which hosts gene expression profiles of IPF lung fibroblasts treated with over 20,000 compounds including esomeprazole. Intriguingly, we found 45 genes that are upregulated in IPF but downregulated by esomeprazole. Pathway analysis showed that these genes are enriched for profibrotic processes. Unbiased high throughput RNA-seq study supported antifibrotic effect of esomeprazole and revealed several novel targets.

Conclusions

Taken together, PPIs may play antifibrotic role in IPF through direct regulation of the MAPK/Nrf2/HO1 pathway to favorably influence the disease process in IPF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12950-021-00284-6.

HIP/PAP protects against bleomycin-induced lung injury and inflammation and subsequent fibrosis in mice

Hepatocarcinoma‐intestine‐pancreas/pancreatitis‐associated protein (HIP/PAP), a C‐type lectin, exerts anti‐oxidative, anti‐inflammatory, bactericidal, anti‐apoptotic, and mitogenic functions in several cell types and tissues. In this study, we explored the role of HIP/PAP in pulmonary fibrosis (PF). Expression of HIP/PAP and its murine counterpart, Reg3B, was markedly increased in fibrotic human and mouse lung tissues. Adenovirus‐mediated HIP/PAP expression markedly alleviated bleomycin (BLM)‐induced lung injury, inflammation, and fibrosis in mice. Adenovirus‐mediated HIP/PAP expression alleviated oxidative injury and lessened the decrease in pulmonary superoxide dismutase (SOD) activity in BLM‐treated mice, increased pulmonary SOD expression in normal mice, and HIP/PAP upregulated SOD expression in cultured human alveolar epithelial cells (A549) and human lung fibroblasts (HLF‐1). Moreover, in vitro experiments showed that HIP/PAP suppressed the growth of HLF‐1 and ameliorated the H₂O₂‐induced apoptosis of human alveolar epithelial cells (A549 and HPAEpiC) and human pulmonary microvascular endothelial cells (HPMVEC). In HLF‐1, A549, HPAEpiC, and HPMVEC cells, HIP/PAP did not affect the basal levels, but alleviated the TGF‐β1‐induced down‐regulation of the epithelial/endothelial markers E‐cadherin and vE‐cadherin and the over‐expression of mesenchymal markers, such as α‐SMA and vimentin. In conclusion, HIP/PAP was found to serve as a potent protective factor in lung injury, inflammation, and fibrosis by attenuating oxidative injury, promoting the regeneration of alveolar epithelial cells, and antagonizing the pro‐fibrotic actions of the TGF‐β1/Smad signaling pathway.

New therapeutic strategies for IPF: Based on the "phagocytosis-secretion-immunization" network regulation mechanism of pulmonary macrophages

Pulmonary fibrosis is a chronic and progressive interstitial lung disease of known and unknown etiology. Over the past decades, macrophages have been recognized to play a significant role in IPF pathogenesis. According to their anatomical loci, macrophages can be divided to alveolar macrophages (AMs) subtypes and interstitial macrophages subtypes (IMs) with different responsibility in the damage defense response. Depending on diverse chemokines and cytokines in local microenvironments, macrophages can be induced and polarized to either classically activated (M1) or alternatively activated (M2) phenotypes in different stages of immunity. Therefore, we hypothesize that there is a "phagocytosis-secretion-immunization" network regulation of pulmonary macrophages related to a number of chemokines and cytokines. In this paper, we summarize and discuss the role of chemokines and cytokines involved in the "phagocytosis-secretion-immunization" network regulation mechanism of pulmonary macrophages, pointing toward novel therapeutic approaches based on the network target regulation in the field. Therapeutic strategies focused on modifying the chemokines, cytokines and the network are promising for the pharmacotherapy of IPF. Some Traditional Chinese medicines may have more superiorities in delaying the progression of pulmonary fibrosis for their multi-target activities of this network regulation.

Epithelial to Mesenchymal Transition in Human Mesothelial Cells Exposed to Asbestos Fibers: Role of TGF-β as Mediator of Malignant Mesothelioma Development or Metastasis via EMT Event

Asbestos exposure increases the risk of asbestosis and malignant mesothelioma (MM). Both fibrosis and cancer have been correlated with the Epithelial to Mesenchymal Transition (EMT)-an event involved in fibrotic development and cancer progression. During EMT, epithelial cells acquire a mesenchymal phenotype by modulating some proteins. Different factors can induce EMT, but Transforming Growth Factor β (TGF-β) plays a crucial role in promoting EMT. In this work, we verified if EMT could be associated with MM development. We explored EMT in human mesothelial cells (MeT-5A) exposed to chrysotile asbestos: we demonstrated that asbestos induces EMT in MeT-5A cells by downregulating epithelial markers E-cadherin, β-catenin, and occludin, and contemporarily, by upregulating mesenchymal markers fibronectin, α-SMA, and vimentin, thus promoting EMT. In these cells, this mechanism is mediated by increased TGF-β secretion, which in turn downregulates E-cadherin and increases fibronectin. These events are reverted in the presence of TGF-β antibody, via a Small Mother Against Decapentaplegic (SMAD)-dependent pathway and its downstream effectors, such as Zinc finger protein SNAI1 (SNAIL-1), Twist-related protein (Twist), and Zinc Finger E-Box Binding Homeobox 1 (ZEB-1), which downregulate the E-cadherin gene. Since SNAIL-1, Twist, and ZEB-1 have been shown to be overexpressed in MM, these genes could be considered possible predictive or diagnostic markers of MM development.

Ventricular pro-arrhythmic phenotype, arrhythmic substrate, ageing and mitochondrial dysfunction in peroxisome proliferator activated receptor-γ coactivator-1β deficient (Pgc-1β-/-) murine hearts

INTRODUCTION

Ageing and age-related bioenergetic conditions including obesity, diabetes mellitus and heart failure constitute clinical ventricular arrhythmic risk factors.

MATERIALS AND METHODS

Pro-arrhythmic properties in electrocardiographic and intracellular recordings were compared in young and aged, peroxisome proliferator-activated receptor-γ coactivator-1β knockout (Pgc-1β-/-) and wild type (WT), Langendorff-perfused murine hearts, during regular and programmed stimulation (PES), comparing results by two-way ANOVA.

RESULTS AND DISCUSSION

Young and aged Pgc-1β-/- showed higher frequencies and durations of arrhythmic episodes through wider PES coupling-interval ranges than WT. Both young and old, regularly-paced, Pgc-1β-/- hearts showed slowed maximum action potential (AP) upstrokes, (dV/dt)max (∼157 vs. 120-130 V s-1), prolonged AP latencies (by ∼20%) and shortened refractory periods (∼58 vs. 51 ms) but similar AP durations (∼50 ms at 90% recovery) compared to WT. However, Pgc-1β-/- genotype and age each influenced extrasystolic AP latencies during PES. Young and aged WT ventricles displayed distinct, but Pgc-1β-/- ventricles displayed similar dependences of AP latency upon (dV/dt)max resembling aged WT. They also independently increased myocardial fibrosis. AP wavelengths combining activation and recovery terms paralleled contrasting arrhythmic incidences in Pgc-1β-/- and WT hearts. Mitochondrial dysfunction thus causes pro-arrhythmic Pgc-1β-/- phenotypes by altering AP conduction through reducing (dV/dt)max and causing age-dependent fibrotic change.

Age-dependent electrocardiographic changes in Pgc-1β deficient murine hearts

Increasing evidence implicates chronic energetic dysfunction in human cardiac arrhythmias. Mitochondrial impairment through Pgc-1β knockout is known to produce a murine arrhythmic phenotype. However, the cumulative effect of this with advancing age and its electrocardiographic basis have not been previously studied. Young (12-16 weeks) and aged (>52 weeks), wild type (WT) (n = 5 and 8) and Pgc-1β^-/- (n = 9 and 6), mice were anaesthetised and used for electrocardiographic (ECG) recordings. Time intervals separating successive ECG deflections were analysed for differences between groups before and after β1-adrenergic (intraperitoneal dobutamine 3 mg/kg) challenge. Heart rates before dobutamine challenge were indistinguishable between groups. The Pgc-1β^-/- genotype however displayed compromised nodal function in response to adrenergic challenge. This manifested as an impaired heart rate response suggesting a functional defect at the level of the sino-atrial node, and a negative dromotropic response suggesting an atrioventricular conduction defect. Incidences of the latter were most pronounced in the aged Pgc-1β^-/- mice. Moreover, Pgc-1β^-/- mice displayed electrocardiographic features consistent with the existence of a pro-arrhythmic substrate. Firstly, ventricular activation was prolonged in these mice consistent with slowed action potential conduction and is reported here for the first time. Additionally, Pgc-1β^-/- mice had shorter repolarisation intervals. These were likely attributable to altered K⁺ conductance properties, ultimately resulting in a shortened QT_c interval, which is also known to be associated with increased arrhythmic risk. ECG analysis thus yielded electrophysiological findings bearing on potential arrhythmogenicity in intact Pgc-1β^-/- systems in widespread cardiac regions.

MiR-21-Mediated Suppression of Smad7 Induces TGFβ1 and Can Be Inhibited by Activation of Nrf2 in Alcohol-Treated Lung Fibroblasts

BACKGROUND

We previously demonstrated that chronic alcohol ingestion augments TGFβ1 expression in the lung fibroblast and increases the risk of fibroproliferative disrepair in a mouse model of acute lung injury. The effect of alcohol on TGFβ1 is mitigated by treatment with sulforaphane (SFP), which can activate nuclear factor (erythroid-derived 2)-like 2 (Nrf2). However, the mechanisms by which alcohol amplifies, or SFP attenuates, TGFβ1 expression in the fibroblast are not known. MicroRNA (miR)-21 has been shown to inhibit Smad7, a TGFβ1 signaling inhibitor. In this study, we hypothesized that alcohol augments TGFβ1 expression through up-regulation of miR-21, which subsequently inhibits Smad7.

METHODS

Primary mouse lung fibroblasts were cultured ± alcohol ± SFP and assessed for gene expression of miR-21, and gene and/or protein expression of Nrf2, Nrf2-regulated antioxidant enzymes, Smad7, STAT3, and TGFβ1. NIH 3T3 fibroblasts were transfected with a miR-21 inhibitor and cultured ± alcohol. α-SMA, Smad7, and TGFβ1 protein expression were then assessed. In parallel, NIH 3T3 lung fibroblasts were transfected with Nrf2 silencing RNA (siRNA) and cultured ± alcohol ± SFP. Gene expression of miR-21, Nrf2, Smad7, and TGFβ1 was assessed.

RESULTS

MiR-21 gene expression was increased by 12-fold at 48 hours, and Smad7 gene expression and protein expression were reduced by ~30% in alcohol-treated fibroblasts. In parallel, inhibition of miR-21 attenuated alcohol-mediated decrease in Smad7 and increase in TGFβ1 and α-SMA protein expression. Treatment with SFP mitigated the effect of alcohol on miR-21, Smad7 and total and phosphorylated STAT3, and restored Nrf2-regulated antioxidant gene expression. Silencing of Nrf2 prevented the effect of SFP on miR-21, Smad7, and TGFβ1 gene expression in alcohol-treated NIH 3T3 fibroblasts.

CONCLUSIONS

Alcohol treatment increases TGFβ1 in fibroblasts, at least in part, through augmentation of miR-21, which then inhibits Smad7 expression. These effects can be attenuated by activation of Nrf2 with SFP.

Age-dependent atrial arrhythmic phenotype secondary to mitochondrial dysfunction in Pgc-1β deficient murine hearts

INTRODUCTION

Ageing and several age-related chronic conditions including obesity, insulin resistance and hypertension are associated with mitochondrial dysfunction and represent independent risk factors for atrial fibrillation (AF).

MATERIALS AND METHODS

Atrial arrhythmogenesis was investigated in Langendorff-perfused young (3-4 month) and aged (>12 month), wild type (WT) and peroxisome proliferator activated receptor-γ coactivator-1β deficient (Pgc-1β-/-) murine hearts modeling age-dependent chronic mitochondrial dysfunction during regular pacing and programmed electrical stimulation (PES).

RESULTS AND DISCUSSION

The Pgc-1β-/- genotype was associated with a pro-arrhythmic phenotype progressing with age. Young and aged Pgc-1β-/- hearts showed compromised maximum action potential (AP) depolarization rates, (dV/dt)max, prolonged AP latencies reflecting slowed action potential (AP) conduction, similar effective refractory periods and baseline action potential durations (APD90) but shortened APD90 in APs in response to extrasystolic stimuli at short stimulation intervals. Electrical properties of APs triggering arrhythmia were similar in WT and Pgc-1β-/- hearts. Pgc-1β-/- hearts showed accelerated age-dependent fibrotic change relative to WT, with young Pgc-1β-/- hearts displaying similar fibrotic change as aged WT, and aged Pgc-1β-/- hearts the greatest fibrotic change. Mitochondrial deficits thus result in an arrhythmic substrate, through slowed AP conduction and altered repolarisation characteristics, arising from alterations in electrophysiological properties and accelerated structural change.

A novel compressive stress-based osteoarthritis-like chondrocyte system

Mechanical stress damage and insufficient self-repair can contribute to osteoarthritis (OA) in the affected joint. As the effects of stress on chondrocyte metabolism can regulate cartilage homeostasis, the specific stress-response condition is therefore a key to the generation of an OA disease model. We aimed to produce a specific stress- and cell-based OA model after evaluating the metabolic responses of chondrocytes in response to a series of static and cyclic compression stressors. A static load exceeding 40 psi initiated extracellular matrix (ECM) degradation through a decrease in the sulphated-glycosaminoglycan (GAG) content, upregulation of catabolic matrix metalloproteinase (MMP)-13 encoding gene expression, and downregulation of the ECM-related aggrecan and type II collagen encoding genes within 24 h. Indicators of pro-inflammatory events and oxidative stress were found to correlate with increased IL-6 expression and reactive oxygen species (ROS) production, respectively. However, chondrocytes stimulated by moderate cyclic loading (30-40 psi) exhibited increased ECM-related gene expression without significant changes in catabolic and pro-inflammatory gene expression. BMP-7 expression increased at cyclic loading levels above 30-60 psi. These results demonstrated that static compression exceeding 60 psi is sufficient to produce OA-like chondrocytes that exhibit signs of ECM degradation and inflammation. These OA-like chondrocytes could therefore be used as a novel cell-based drug screening system. Impact statement The lack of an effective treatment for osteoarthritis (OA) reflects the great need for alternative therapies and drug discovery. Disease models can be used for early-stage compound screening and disease studies. Chondrocytes are solely responsible for the maintenance of the articular cartilage extracellular matrix. Our strategy involved the generation of a cell-based model of OA, a more readily studied disease. Instead of using animal cartilage explants, we incorporated isolated porcine chondrocytes with hydrogel to form three-dimensional assemblies. We could identify the specific magnitude-dependent metabolic responses of chondrocytes by applying a series of static and cyclic compression, and therefore successfully generated a novel OA-like cell-based model for drug screening.

Mitochondrial catalase overexpressed transgenic mice are protected against lung fibrosis in part via preventing alveolar epithelial cell mitochondrial DNA damage

RATIONALE

Alveolar epithelial cell (AEC) injury and mitochondrial dysfunction are important in the development of lung fibrosis. Our group has shown that in the asbestos exposed lung, the generation of mitochondrial reactive oxygen species (ROS) in AEC mediate mitochondrial DNA (mtDNA) damage and apoptosis which are necessary for lung fibrosis. These data suggest that mitochondrial-targeted antioxidants should ameliorate asbestos-induced lung.

OBJECTIVE

To determine whether transgenic mice that express mitochondrial-targeted catalase (MCAT) have reduced lung fibrosis following exposure to asbestos or bleomycin and, if so, whether this occurs in association with reduced AEC mtDNA damage and apoptosis.

METHODS

Crocidolite asbestos (100µg/50µL), TiO2 (negative control), bleomycin (0.025 units/50µL), or PBS was instilled intratracheally in 8-10 week-old wild-type (WT - C57Bl/6J) or MCAT mice. The lungs were harvested at 21d. Lung fibrosis was quantified by collagen levels (Sircol) and lung fibrosis scores. AEC apoptosis was assessed by cleaved caspase-3 (CC-3)/Surfactant protein C (SFTPC) immunohistochemistry (IHC) and semi-quantitative analysis. AEC (primary AT2 cells from WT and MCAT mice and MLE-12 cells) mtDNA damage was assessed by a quantitative PCR-based assay, apoptosis was assessed by DNA fragmentation, and ROS production was assessed by a Mito-Sox assay.

RESULTS

Compared to WT, crocidolite-exposed MCAT mice exhibit reduced pulmonary fibrosis as measured by lung collagen levels and lung fibrosis score. The protective effects in MCAT mice were accompanied by reduced AEC mtDNA damage and apoptosis. Similar findings were noted following bleomycin exposure. Euk-134, a mitochondrial SOD/catalase mimetic, attenuated MLE-12 cell DNA damage and apoptosis. Finally, compared to WT, asbestos-induced MCAT AT2 cell ROS production was reduced.

CONCLUSIONS

Our finding that MCAT mice have reduced pulmonary fibrosis, AEC mtDNA damage and apoptosis following exposure to asbestos or bleomycin suggests an important role for AEC mitochondrial H2O2-induced mtDNA damage in promoting lung fibrosis. We reason that strategies aimed at limiting AEC mtDNA damage arising from excess mitochondrial H2O2 production may be a novel therapeutic target for mitigating pulmonary fibrosis.

Effects of Chrysotile Exposure in Human Bronchial Epithelial Cells: Insights into the Pathogenic Mechanisms of Asbestos-Related Diseases

BACKGROUND

Chrysotile asbestos accounts for > 90% of the asbestos used worldwide, and exposure is associated with asbestosis (asbestos-related fibrosis) and other malignancies; however, the molecular mechanisms involved are not fully understood. A common pathogenic mechanism for these malignancies is represented by epithelial-mesenchymal transition (EMT), through which epithelial cells undergo a morphological transformation to assume a mesenchymal phenotype. In the present work, we propose that chrysotile asbestos induces EMT through a mechanism involving a signaling pathway mediated by tranforming growth factor beta (TGF-β).

OBJECTIVES

We investigated the role of chrysotile asbestos in inducing EMT in order to elucidate the molecular mechanisms involved in this event.

METHODS

Human bronchial epithelial cells (BEAS-2B) were incubated with 1 μg/cm2 chrysotile asbestos for ≤ 72 hr, and several markers of EMT were investigated. Experiments with specific inhibitors for TGF-β, glycogen synthase kinase-3β (GSK-3β), and Akt were performed to confirm their involvement in asbestos-induced EMT. Real-time polymerase chain reaction (PCR), Western blotting, and gelatin zymography were performed to detect mRNA and protein level changes for these markers.

RESULTS

Chrysotile asbestos activated a TGF-β-mediated signaling pathway, implicating the contributions of Akt, GSK-3β, and SNAIL-1. The activation of this pathway in BEAS-2B cells was associated with a decrease in epithelial markers (E-cadherin and β-catenin) and an increase in mesenchymal markers (α-smooth muscle actin, vimentin, metalloproteinases, and fibronectin).

CONCLUSIONS

Our findings suggest that chrysotile asbestos induces EMT, a common event in asbestos-related diseases, at least in part by eliciting the TGF-β-mediated Akt/GSK-3β/SNAIL-1 pathway.

CITATION

Gulino GR, Polimeni M, Prato M, Gazzano E, Kopecka J, Colombatto S, Ghigo D, Aldieri E. 2016. Effects of chrysotile exposure in human bronchial epithelial cells: insights into the pathogenic mechanisms of asbestos-related diseases. Environ Health Perspect 124:776-784; http://dx.doi.org/10.1289/ehp.1409627.

Persistent effects of Libby amphibole and amosite asbestos following subchronic inhalation in rats

Background

Human exposure to Libby amphibole (LA) asbestos increases risk of lung cancer, mesothelioma, and non-malignant respiratory disease. This study evaluated potency and time-course effects of LA and positive control amosite (AM) asbestos fibers in male F344 rats following nose-only inhalation exposure.

Methods

Rats were exposed to air, LA (0.5, 3.5, or 25.0 mg/m³ targets), or AM (3.5 mg/m³ target) for 10 days and assessed for markers of lung inflammation, injury, and cell proliferation. Short-term results guided concentration levels for a stop-exposure study in which rats were exposed to air, LA (1.0, 3.3, or 10.0 mg/m³), or AM (3.3 mg/m³) 6 h/day, 5 days/week for 13 weeks, and assessed 1 day, 1, 3, and 18 months post-exposure. Fibers were relatively short; for 10 mg/m³ LA, mean length of all structures was 3.7 μm and 1 % were longer than 20 μm.

Results

Ten days exposure to 25.0 mg/m³ LA resulted in significantly increased lung inflammation, fibrosis, bronchiolar epithelial cell proliferation and hyperplasia, and inflammatory cytokine gene expression compared to air. Exposure to 3.5 mg/m³ LA resulted in modestly higher markers of acute lung injury and inflammation compared to AM. Following 13 weeks exposure, lung fiber burdens correlated with exposure mass concentrations, declining gradually over 18 months. LA (3.3 and 10.0 mg/m³) and AM produced significantly higher bronchoalveolar lavage markers of inflammation and lung tissue cytokines, Akt, and MAPK/ERK pathway components compared to air control from 1 day to 3 months post-exposure. Histopathology showed alveolar inflammation and interstitial fibrosis in all fiber-exposed groups up to 18 months post-exposure. Positive dose trends for incidence of alveolar epithelial hyperplasia and bronchiolar/alveolar adenoma or carcinoma were observed among LA groups.

Conclusions

Inhalation of relatively short LA fibers produced inflammatory, fibrogenic, and tumorigenic effects in rats which replicate essential attributes of asbestos-related disease in exposed humans. Fiber burden, inflammation, and activation of growth factor pathways may persist and contribute to lung tumorigenesis long after initial LA exposure. Fiber burden data are being used to develop a dosimetry model for LA fibers, which may provide insights on mode of action for hazard assessment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-016-0130-z) contains supplementary material, which is available to authorized users.

Reciprocal regulation of TGF-β and reactive oxygen species: A perverse cycle for fibrosis

Transforming growth factor beta (TGF-β) is the most potent pro-fibrogenic cytokine and its expression is increased in almost all of fibrotic diseases. Although signaling through Smad pathway is believed to play a central role in TGF-β's fibrogenesis, emerging evidence indicates that reactive oxygen species (ROS) modulate TGF-β's signaling through different pathways including Smad pathway. TGF-β1 increases ROS production and suppresses antioxidant enzymes, leading to a redox imbalance. ROS, in turn, induce/activate TGF-β1 and mediate many of TGF-β's fibrogenic effects, forming a vicious cycle (see graphic flow chart on the right). Here, we review the current knowledge on the feed-forward mechanisms between TGF-β1 and ROS in the development of fibrosis. Therapeutics targeting TGF-β-induced and ROS-dependent cellular signaling represents a novel approach in the treatment of fibrotic disorders.

•

TGF-β1 is the most potent ubiquitous profibrogenic cytokine.

•

TGF- β 1 induces redox imbalance by ↑ ROS production and ↓ anti-oxidant defense system

•

Redox imbalance, in turn, activates latent TGF-β1 and induces TGF-β1 expression.

•

Redox imbalance also mediates many of TGF-β1’s profibrogenic effects

Pleiotropic effect of the proton pump inhibitor esomeprazole leading to suppression of lung inflammation and fibrosis

Background

The beneficial outcome associated with the use of proton pump inhibitors (PPIs) in idiopathic pulmonary fibrosis (IPF) has been reported in retrospective studies. To date, no prospective study has been conducted to confirm these outcomes. In addition, the potential mechanism by which PPIs improve measures of lung function and/or transplant-free survival in IPF has not been elucidated.

Methods

Here, we used biochemical, cell biological and preclinical studies to evaluate regulation of markers associated with inflammation and fibrosis. In our in vitro studies, we exposed primary lung fibroblasts, epithelial and endothelial cells to ionizing radiation or bleomycin; stimuli typically used to induce inflammation and fibrosis. In addition, we cultured lung fibroblasts from IPF patients and studied the effect of esomeprazole on collagen release. Our preclinical study tested efficacy of esomeprazole in a rat model of bleomycin-induced lung injury. Furthermore, we performed retrospective analysis of interstitial lung disease (ILD) databases to examine the effect of PPIs on transplant-free survival.

Results

The cell culture studies revealed that esomeprazole controls inflammation by suppressing the expression of pro-inflammatory molecules including vascular cell adhesion molecule-1, inducible nitric oxide synthase, tumor necrosis factor-alpha (TNF-α) and interleukins (IL-1β and IL-6). The antioxidant effect is associated with strong induction of the stress-inducible cytoprotective protein heme oxygenase-1 (HO1) and the antifibrotic effect is associated with potent inhibition of fibroblast proliferation as well as downregulation of profibrotic proteins including receptors for transforming growth factor β (TGFβ), fibronectin and matrix metalloproteinases (MMPs). Furthermore, esomeprazole showed robust effect in mitigating the inflammatory and fibrotic responses in a murine model of acute lung injury. Finally, retrospective analysis of two ILD databases was performed to assess the effect of PPIs on transplant-free survival in IPF patients. Intriguingly, this data demonstrated that IPF patients on PPIs had prolonged survival over controls (median survival of 3.4 vs 2 years).

Conclusions

Overall, these data indicate the possibility that PPIs may have protective function in IPF by directly modulating the disease process and suggest that they may have other clinical utility in the treatment of extra-intestinal diseases characterized by inflammatory and/or fibrotic phases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0614-x) contains supplementary material, which is available to authorized users.

Amphibole, but not chrysotile, asbestos induces anti-nuclear autoantibodies and IL-17 in C57BL/6 mice

Abstract Exposure to amphibole asbestos has been associated with production of autoantibodies in mice and humans, and increases the risk of systemic autoimmune disease. However, epidemiological studies of chrysotile exposure have not indicated a similar induction of autoimmune responses. To demonstrate this difference in controlled exposures in mice, and to explore possible mechanistic explanations for the difference, C57BL/6 mice were exposed intratracheally to amphibole or chrysotile asbestos, or to saline only. Serum antinuclear antibodies (ANA), antibodies to extractable nuclear antigens (ENA), serum cytokines, and immunoglobulin isotypes were evaluated 8 months after the final treatment. The percentages of lymphocyte sub-sets were determined in the spleen and lungs. The results show that amphibole, but not chrysotile, asbestos increases the frequency of ANA/ENA in mice. Amphibole and chrysotile both increased multiple serum cytokines, but only amphibole increased IL-17. Both fibers decreased IgG1, without significant changes in other immunoglobulin isotypes. Although there were no gross changes in overall percentages of T- and B-cells in the spleen or lung, there was a significant increase in the normally rare populations of suppressor B-cells (CD19(+), CD5(+), CD1d(+)) in both the spleen and lungs of chrysotile-exposed mice. Overall, the results suggest that, while there may be an inflammatory response to both forms of asbestos, there is an autoimmune response in only the amphibole-exposed, but not the chrysotile-exposed mice. These data have critical implications in terms of screening and health outcomes of asbestos-exposed populations.

Tumor necrosis factor-α modulates epithelial mesenchymal transition mediators ZEB2 and S100A4 to promote cholangiocarcinoma progression

BACKGROUND

The epithelial-mesenchymal transition (EMT) process strongly contributes to cancer metastasis. This study was to investigate the alteration of EMT-related proteins (ZEB1, ZEB2 and S100A4) in cholangiocarcinoma (CCA) tissues. The effect of tumor necrosis factor-α (TNF-α) on the expression of those molecules in CCA cells was investigated.

METHODS

The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay was used to quantify ZEB1, ZEB2 and S100A4 mRNA levels in 50 CCA tissues and related its expression to clinicopathological data. ZEB2 protein immunostaining was investigated in 165 CCA tissues. The effect of TNF-α on EMT-related CCA cell migration was evaluated using qRT-PCR, immunofluorescence and transwell migration assays.

RESULTS

ZEB2 and S100A4 mRNA levels were found to be higher in CCA tissues. High levels of S100A4 mRNA and ZEB2 protein were significantly associated with CCA metastasis (P = 0.04 and P = 0.03). Moreover, a trend toward statistical association was found with high levels of both ZEB2 mRNA and protein with shorter survival time (P = 0.10 and P = 0.19). In addition, TNF-α induced CCA cell migration by the induction of transforming growth factor-β (TGF-β) resulting in ZEB2 and S100A4 mRNA and protein activation.

CONCLUSIONS

These studies demonstrate that TNF-α plays crucial role in the progression of CCA by activating TGF-β signaling and the induction of ZEB2 and S100A4, EMT-related proteins expression.

Topical infliximab for the suppression of wound healing following experimental glaucoma filtration surgery

Background

The purpose of this work was to look into the effects of infliximab on wound healing in experimental glaucoma filtration surgery and to compare the antifibrotic effects of this agent to that of mitomycin-C (MMC).

Methods

Twenty-eight male New Zealand White rabbits were randomly assigned to four groups, each including seven rabbits: control group, sham group, MMC group, and infliximab group. The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the MMC treatment group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL MMC was applied intraoperatively to the scleral surgical site for three minutes. The rabbits in the infliximab treatment group underwent trabeculectomy and one drop of 10 mg/mL infliximab was instilled four times a day for 14 days after surgery. On day 14 of the experiment, the operated and control eyes were enucleated and histologically and immunohistochemically analyzed.

Results

The mean fibroblast and mononuclear cell (MNC) numbers and the mean immunostaining intensities of transforming growth factor-β (TGF-β), fibroblast growth factor-β (FGF-β), and platelet-derived growth factor (PDGF) in the sham group were higher than those of the control group (P<0.01). The mean fibroblast and MNC numbers and the mean immunostaining intensities of TGF-β, FGF-β, and PDGF in the MMC and infliximab groups were statistically significantly lower than those of the sham group (P<0.01). The mean fibroblast and MNC numbers and the mean TGF-β, FGF-β, and PDGF immunostaining intensities of the MMC and infliximab groups were similar (P>0.05).

Conclusion

Our study suggests that topical infliximab effectively suppresses the subconjunctival wound healing response after experimental glaucoma filtration surgery, reducing the MNC and fibroblast numbers and immunostaining intensities of TGF-β, FGF-β, and PDGF.

Asbestos modulates thioredoxin-thioredoxin interacting protein interaction to regulate inflammasome activation

BACKGROUND

Asbestos exposure is related to various diseases including asbestosis and malignant mesothelioma (MM). Among the pathogenic mechanisms proposed by which asbestos can cause diseases involving epithelial and mesothelial cells, the most widely accepted one is the generation of reactive oxygen species and/or depletion of antioxidants like glutathione. It has also been demonstrated that asbestos can induce inflammation, perhaps due to activation of inflammasomes.

METHODS

The oxidation state of thioredoxin was analyzed by redox Western blot analysis and ROS generation was assessed spectrophotometrically as a read-out of solubilized formazan produced by the reduction of nitrotetrazolium blue (NTB) by superoxide. Quantitative real time PCR was used to assess changes in gene transcription.

RESULTS

Here we demonstrate that crocidolite asbestos fibers oxidize the pool of the antioxidant, Thioredoxin-1 (Trx1), which results in release of Thioredoxin Interacting Protein (TXNIP) and subsequent activation of inflammasomes in human mesothelial cells. Exposure to crocidolite asbestos resulted in the depletion of reduced Trx1 in human peritoneal mesothelial (LP9/hTERT) cells. Pretreatment with the antioxidant dehydroascorbic acid (a reactive oxygen species (ROS) scavenger) reduced the level of crocidolite asbestos-induced Trx1 oxidation as well as the depletion of reduced Trx1. Increasing Trx1 expression levels using a Trx1 over-expression vector, reduced the extent of Trx1 oxidation and generation of ROS by crocidolite asbestos, and increased cell survival. In addition, knockdown of TXNIP expression by siRNA attenuated crocidolite asbestos-induced activation of the inflammasome.

CONCLUSION

Our novel findings suggest that extensive Trx1 oxidation and TXNIP dissociation may be one of the mechanisms by which crocidolite asbestos activates the inflammasome and helps in development of MM.

The epithelium in idiopathic pulmonary fibrosis: breaking the barrier

Idiopathic pulmonary fibrosis is a progressive disease of unknown etiology characterized by a dysregulated wound healing response that leads to fatal accumulation of fibroblasts and extracellular matrix (ECM) in the lung, which compromises tissue architecture and lung function capacity. Injury to type II alveolar epithelial cells is thought to be the key event for the initiation of the disease, and so far both genetic factors, such as mutations in telomerase and MUC5B genes as well as environmental components, like cigarette smoking, exposure to asbestos and viral infections have been implicated as potential initiating triggers. The injured epithelium then enters a state of senescence-associated secretory phenotype whereby it produces both pro-inflammatory and pro-fibrotic factors that contribute to the wound healing process in the lung. Immune cells, like macrophages and neutrophils as well as activated myofibroblasts then perpetuate this cascade of epithelial cell apoptosis and proliferation by release of pro-fibrotic transforming growth factor beta and continuous deposition of ECM stiffens the basement membrane, altogether having a deleterious impact on epithelial cell function. In this review, we describe the role of the epithelium as both a physical and immunological barrier between environment and self in the homeostatic versus diseased lung and explore the potential mechanisms of epithelial cell injury and the impact of loss of epithelial cell permeability and function on cytokine production, inflammation, and myofibroblast activation in the fibrotic lung.

Role of IL-10 in the progression of kidney disease

Interleukin-10 (IL-10), a cytokine with anti-inflammatory and immunomodulatory functions, regulates the biology of B and T cells. The present review describes the role of IL-10 in normal renal physiology, during acute kidney injury and in the development of chronic renal failure. We further discuss IL-10-induced cellular and molecular pathways and their link to the progression of kidney injury.

Genes involved in innate immunity associated with asbestos-related fibrotic changes

Objectives

To determine whether genetic polymorphisms in several candidate genes related to innate immunity and protease–antiprotease balance modify individual susceptibility to develop asbestos-related fibrotic pleuropulmonary changes.

Methods

Sixteen polymorphisms from nine genes (NLRP3, CARD8, TNF, TGFB1, GC, MMP1, MMP9, MMP12 and TIMP2) were genotyped from 951 Finnish asbestos-exposed workers. The genotype/haplotype data were compared to signs of fibrosis and pleural thickenings using linear and logistic regression analysis adjusted for potential confounders.

Results

A functional polymorphism (Q705K; rs35829419) in the NLRP3 gene was associated with interstitial lung fibrosis (p=0.013), and the TGFB1 rs2241718 SNP with visceral pleural fibrosis (VPF) (p=0.044). In stratified analysis, the carriage of at least one NLRP3 variant allele conferred a 2.5-fold increased risk for pathological interstitial lung fibrosis (OR 2.44, 95% CI 0.97 to 6.14). Conversely, the carriage of at least one TGFB1 rs2241718 variant allele protected against VPF (OR 0.62, 95% CI 0.39 to 0.98). The TIMP2 rs2277698 SNP and a haplotype consisting of the TGFB1 rs1800469 and rs1800470 SNPs were associated with the degree of pleural thickening calcification (p=0.037 and p=0.035), and the CARD8 rs2043211 SNP with the greatest thickness of pleural plaques (p=0.015).

Conclusions

Our results support the hypothesis that the NLRP3 inflammasome is important in the development of fibrotic lung disease by associating the NLRP3 rs35829419 variant allele with increased risk of asbestos-related interstitial lung fibrosis, and the TGFB1 rs2241718 variant allele with decreased risk of asbestos-related VPF. Polymorphisms in CARD8 and TIMP2 are proposed to modify the development and/or calcification of pleural thickenings.

TGF-β activation and lung fibrosis

Lung fibrosis can affect the parenchyma and the airways, classically giving rise to idiopathic pulmonary fibrosis (IPF) in the parenchyma or airway remodeling in asthma and chronic obstructive pulmonary disease. TGF-β activation has been implicated in the fibrosis of both IPF and airway remodeling. However, the mechanisms of TGF-β activation appear to differ depending on the cellular and anatomical compartments, with implications on disease pathogenesis. Although it appears that epithelial cell activation of TGF-β by the αvβ6 integrin is central in IPF, mesenchymal activation of TGF-β by the αvβ5 and αvβ8 integrins appears to predominate in airway remodeling. Interestingly, the mechanism of TGF-β by the integrins αvβ6 and αvβ5 is shared, relying on cytoskeletal changes, whereas activation of TGF-β by the αvβ8 integrin is distinct, relying on proteolytic cleavage of the latency-associated peptide of TGF-β by matrix metalloproteinase 14. This article describes the mechanisms through which epithelial cells activate TGF-β by the αvβ6 integrin and mesenchymal cells activate TGF-β by the αvβ5 integrin, and highlights their roles in lung fibrosis.

Proinflammatory cytokines induced altered expression of cyclooxygenase-2 gene results in unreceptive endometrium in women with idiopathic recurrent spontaneous miscarriage

OBJECTIVE

To investigate the expression pattern of proinflammatory, anti-inflammatory, and angiogenic cytokines and their effect on various mediators of endometrial receptivity in women with idiopathic recurrent spontaneous miscarriage (IRSM).

DESIGN

A prospective study.

SETTING

Tertiary care hospital and reproductive health research unit.

PATIENT(S)

Thirty-six women with IRSM (<35 years) and 30 fertile women as controls matched by age and body mass index undergoing sterilization.

INTERVENTION(S)

Endometrial biopsies in all women corresponding to the window of implantation.

MAIN OUTCOME MEASURE(S)

Assessment of endometrial expression of proinflammatory, anti-inflammatory, and angiogenic cytokines, mediators of matrix turnover and angiogenesis, markers of receptivity.

RESULT(S)

A statistical significantly higher level of proinflammatory cytokines, mediators of matrix turnover and angiogenesis, and a reduced expression of anti-inflammatory and angiogenic cytokines were observed in women with IRSM. Additionally, the markers of endometrial receptivity were poorly expressed in women with IRSM.

CONCLUSION(S)

Aberrant expression of proinflammatory, anti-inflammatory, and angiogenic cytokines during implantation window in women with IRSM is one of the key factors that adversely affect endometrial development, as evidenced by the inadequate expression of various endometrial receptivity markers.

Antifibrotic and antioxidant effects of N-acetylcysteine in an experimental cholestatic model

OBJECTIVES

Several studies have suggested that oxidative stress may play an important role in the pathogenesis of hepatic injury during cholestasis in rats and humans. The aim of this study was to evaluate the ability of N-acetylcysteine (NAC) to prevent the damage induced by bile duct ligation (BDL) for 28 days in male Wistar rats.

METHODS

NAC was administered daily (300 mg/kg, orally) for 28 days. Alanine aminotransferase was quantified in the serum; lipid peroxidation, glutathione, and catalase activity were measured in the liver. Fibrosis was assessed by measuring the liver hydroxyproline content; transforming growth factor-β (TGF-β), interleukin (IL)-6, and IL-10 were determined in the liver by a western blot and quantified densitometrically.

RESULTS

The induction of cholestatic damage by BDL was associated with an increase in alanine aminotransferase. Oxidative stress was also evaluated; lipid peroxidation increased, whereas the liver glutathione content and catalase activity decreased by BDL. NAC treatment prevented these alterations. Hydroxyproline was increased by chronic BDL, but NAC preserved the normal hydroxyproline levels. Cytokines TGF-β, IL-6, and IL-10 increased after 28 days of BDL. NAC was effectively significant in preventing TGF-β and IL-6 expression and further augmented the IL-10 expression.

CONCLUSION

Our data indicate that in the development to cholestatic liver damage, oxidative stress plays an important role and this in turn leads to fibrosis. This study shows that the beneficial effects of NAC are because of its antioxidant and immunomodulatory properties.

Peroxidase-like activity of ferruginous bodies isolated by exploiting their magnetic property

Ferruginous bodies (FB) are polymorphic structures whose formation is macrophage dependent, and are composed of a core, which may consist of an asbestos fiber coated with proteins, among which ferritin is the main component. Within ferritin, the ferric and ferrous ions are coordinated as ferrihydrite, which is the main iron (Fe) storage compound. However, when ferritin accumulates in some tissues following Fe overload it also contains magnetite along with ferrihydrite, which endows it with magnetic properties. Recently studies showed that magnetite exerts peroxidase-like activity, and since ferruginous bodies display magnetic properties, it was postulated that these particular structures may also contain magnetite within the ferritin coating, and thus may also exert peroxidase-like activity. Histochemical analysis for peroxidase of isolated FB smears demonstrated positive staining. Samples isolated from 4 different autopsy lung fragments were also able to oxidize 3,3',5,5'-tetramethyl-benzidine to a blue colored compound that absorbs at 655 nm. This activity was (1) azide and heat insensitive with optimal pH from 5 to 6, and (2) highly variable, changing more than 25-fold from one sample to another. These findings, together with evidence that the peroxidase-like activity of ferruginous bodies has a hydrogen peroxide and substrate requirement different from that of human myeloperoxidase, can exclude that this enzyme gives a significant contribution to the formation of FB. Standard Fe-rich asbestos fibers also express a peroxidase-like activity, but this appears negligible compared to that of ferruginous bodies. Strong acidification of standard Fe-containing asbestos fibers or magnetically isolated ferruginous bodies liberates a high amount of peroxidase-like activity, which is probably accounted for by the release of Fe ions. Further, FB also damage mesothelial cells in vitro. Data suggest that FB exert peroxidase-like activity and cytotoxic activity against mesothelial cells, and hence may be an important factor in pathogenesis of asbestos-related diseases.

TNF-α mRNA expression correlates with TGF-β mRNA expression in vivo

TNF-α is postulated to play a significant role in regulating TGF-β(1) expression. In lung fibroblasts, for example, TNF-α is supposed to induce TGF-β(1) via AP-1 activation. TNF-α receptor, knock-out mice are resistant to induced fibrosis and over-expression of TNF-α causes increased TGF-β(1) production in mice. Therefore, we investigated whether TNF-α mRNA levels are associated with the TGF-β(1) mRNA levels of blood leucocytes in humans. Quantitative real-time PCR of TNF-α and TGF-β(1) was performed in 118 Germans. Calculations of expression were made with the 2(-ΔΔCT) method. When the investigated population was divided in two groups (TNF-α low and TNF-α high) by the median of the determined TNF-α expression, highly significant (p < 0.0001) differences of TGF-β1 mRNA expression were revealed. Additionally, dividing the investigated population into quartiles of the determined TNF-α expression showed significantly different TGF-β1 mRNA expressions. Comparing the determined CT-values of TNF-α in context with these of TGF-β1, a coefficient of determination R(2) = 0.4635 was calculated. In this study we demonstrated in vivo a significant association of the relative TNF-α/B2M mRNA expression and the relative TGF-β(1)/B2M mRNA expression in 118 Germans.

Increased transforming growth factor beta 1 expression mediates ozone-induced airway fibrosis in mice

Ozone (O₃), a commonly encountered environmental pollutant, has been shown to induce pulmonary fibrosis in different animal models; the underlying mechanism, however, remains elusive. To investigate the molecular mechanism underlying O₃-induced pulmonary fibrosis, 6- to 8-week-old C57BL/6 male mice were exposed to a cyclic O₃ exposure protocol consisting of 2 days of filtered air and 5 days of O₃ exposure (0.5 ppm, 8 h/day) for 5 and 10 cycles with or without intraperitoneal injection of IN-1233, a specific inhibitor of the type 1 receptor of transforming growth factor beta (TGF-β), the most potent profibrogenic cytokine. The results showed that O₃ exposure for 5 or 10 cycles increased the TGF-β protein level in the epithelial lining fluid (ELF), associated with an increase in the expression of plasminogen activator inhibitor 1 (PAI-1), a TGF-β-responsive gene that plays a critical role in the development of fibrosis under various pathological conditions. Cyclic O₃ exposure also increased the deposition of collagens and alpha smooth muscle actin (α-SMA) in airway walls. However, these fibrotic changes were not overt until after 10 cycles of O₃ exposure. Importantly, blockage of the TGF-β signaling pathway with IN-1233 suppressed O₃-induced Smad2/3 phosphorylation, PAI-1 expression, as well as collagens and α-SMA deposition in the lung. Our data demonstrate for the first time that O₃ exposure increases TGF-β expression and activates TGF-β signaling pathways, which mediates O₃-induced lung fibrotic responses in vivo.

Thermosensitive chitosan-gelatin-glycerol phosphate hydrogel as a controlled release system of ferulic acid for nucleus pulposus regeneration

In the degenerative disc, overproduction of reactive oxygen species (ROS) involves in apoptosis and senescence of nucleus pulposus (NP) cells that could accelerate the degenerative process. Ferulic acid (FA) has been reported to have an excellent antioxidant property. In the study, injectable thermosensitive chitosan/gelatin/glycerol phosphate (C/G/GP) hydrogel was applied as a controlled release system for FA delivery. The study was aimed to evaluate possible therapeutic effects of FA-incorporated C/G/GP hydrogel on hydrogen peroxide (H(2)O(2))-induced oxidative stress NP cells. The results showed that the release of FA from C/G/GP hydrogel could decrease the H(2)O(2)-induced oxidative stress. Post-treatment of FA-incorporated C/G/GP hydrogel on H(2)O(2)-induced oxidative stress NP cells showed up-regulation of Aggrecan and type II collagen and down-regulation of MMP-3 in mRNA level. The results of sulfated-glycosaminoglycans (GAGs) to DNA ratio and alcian blue staining revealed that the GAGs production of H(2)O(2)-induced oxidative stress NP cells could reach to normal level. The results of caspase-3 activity and TUNEL staining indicated that FA-incorporated C/G/GP hydrogel decreased the apoptosis of H(2)O(2)-induced oxidative stress NP cells. The results suggested that the C/G/GP hydrogel was very suitable for sustained delivery of FA. The FA-incorporated C/G/GP hydrogel would be used to treat the degenerative disc in the early stage before it developed into the latter irreversible stages.

Pulmonary endpoints (lung carcinomas and asbestosis) following inhalation exposure to asbestos

Lung carcinomas and pulmonary fibrosis (asbestosis) occur in asbestos workers. Understanding the pathogenesis of these diseases is complicated because of potential confounding factors, such as smoking, which is not a risk factor in mesothelioma. The modes of action (MOA) of various types of asbestos in the development of lung cancers, asbestosis, and mesotheliomas appear to be different. Moreover, asbestos fibers may act differentially at various stages of these diseases, and have different potencies as compared to other naturally occurring and synthetic fibers. This literature review describes patterns of deposition and retention of various types of asbestos and other fibers after inhalation, methods of translocation within the lung, and dissolution of various fiber types in lung compartments and cells in vitro. Comprehensive dose-response studies at fiber concentrations inhaled by humans as well as bivariate size distributions (lengths and widths), types, and sources of fibers are rarely defined in published studies and are needed. Species-specific responses may occur. Mechanistic studies have some of these limitations, but have suggested that changes in gene expression (either fiber-catalyzed directly or by cell elaboration of oxidants), epigenetic changes, and receptor-mediated or other intracellular signaling cascades may play roles in various stages of the development of lung cancers or asbestosis.

Tumour necrosis factor-alpha gene polymorphisms in asbestos-induced diseases

BACKGROUND

Tumour necrosis factor (TNF)-alpha influences the pathogenesis of lung fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene have been suggested to be associated with susceptibility to lung diseases.

METHODS

Association studies were performed in German subjects, using control subjects (n = 177), pulmonary fibrosis patients (n = 612) and bronchial carcinoma patients (n = 374).

RESULTS

Compared with a healthy (control) group, a significant result could be obtained for the asbestosis (patient) group (crude odds ratio (OR(crude)) = 1.57; 95% confidence interval (CI) 1.05-2.36; p = 0.03), especially with severe lung asbestosis (OR(crude) = 4.15; 95% CI 1.06-16.16; p = 0.04). A significant association was revealed when comparing asbestosis patients (OR(crude) = 4.08; 95% CI 1.53-10.54; p = 0.004 and OR(adjusted) = 3.89; 95% CI 1.49-10.17; p = 0.006) with asbestos-induced lung cancer patients.

CONCLUSION

The results confirm the hypothesis that TNF-alpha polymorphisms are associated with asbestos-induced fibrotic or malignant lung diseases in Germans.

TNF-alpha induces TGF-beta1 expression in lung fibroblasts at the transcriptional level via AP-1 activation

Tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta(1) (TGF-beta(1)) are peptides with multiple biological activities that influence neoplastic, immunologic and fibroproliferative diseases. There are clear interrelationships and overlap between the actions of TNF-alpha and TGF-beta(1) in lung fibrosis; therefore, we postulated that TNF-alpha may play a significant role in regulating TGF-beta(1) expression in lungs. We recently reported that TNF-alpha activates the extracellular regulated kinase (ERK)-specific pathway in fibroblasts resulting in stabilization of TGF-beta(1) mRNA and increased expression of TGF-beta(1). In the current study, we further investigated the molecular mechanisms involved in TNF-alpha regulation of TGF-beta(1) expression. Nuclear run-on assays showed that treatment of Swiss 3T3 fibroblasts with TNF-alpha increased transcription of the TGF-beta(1) gene in an ERK independent manner. Pre-treatment with the activator protein-1 (AP-1) inhibitor curcumin attenuated TNF-alpha induced transcription of the TGF-beta(1) gene. TNF-alpha induced increased levels of c-Jun and C-Fos in the nucleus accompanied by phosphorylation of c-Jun. In electrophoretic mobility shift assays, AP-1 binding to an AP-1 binding site found within the TGF-beta(1) promoter was increased in nuclear extracts from Swiss 3T3 fibroblasts treated with TNF-alpha. Together, these results suggest that TNF-alpha induces expression and DNA binding of AP-1 resulting in increased transcription of the TGF-beta(1) gene. It is essential to know which transcription pathways are activated because of the wide distribution of TNF-alpha and TGF-beta(1), the general lack of effective treatments for fibroproliferative disease and the possibility that targeting the correct transcription factors could be palliative.

TNF-alpha induces TGF-beta1 expression in lung fibroblasts at the transcriptional level via AP-1 activation

Tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta(1) (TGF-beta(1)) are peptides with multiple biological activities that influence neoplastic, immunologic and fibroproliferative diseases. There are clear interrelationships and overlap between the actions of TNF-alpha and TGF-beta(1) in lung fibrosis; therefore, we postulated that TNF-alpha may play a significant role in regulating TGF-beta(1) expression in lungs. We recently reported that TNF-alpha activates the extracellular regulated kinase (ERK)-specific pathway in fibroblasts resulting in stabilization of TGF-beta(1) mRNA and increased expression of TGF-beta(1). In the current study, we further investigated the molecular mechanisms involved in TNF-alpha regulation of TGF-beta(1) expression. Nuclear run-on assays showed that treatment of Swiss 3T3 fibroblasts with TNF-alpha increased transcription of the TGF-beta(1) gene in an ERK independent manner. Pre-treatment with the activator protein-1 (AP-1) inhibitor curcumin attenuated TNF-alpha induced transcription of the TGF-beta(1) gene. TNF-alpha induced increased levels of c-Jun and C-Fos in the nucleus accompanied by phosphorylation of c-Jun. In electrophoretic mobility shift assays, AP-1 binding to an AP-1 binding site found within the TGF-beta(1) promoter was increased in nuclear extracts from Swiss 3T3 fibroblasts treated with TNF-alpha. Together, these results suggest that TNF-alpha induces expression and DNA binding of AP-1 resulting in increased transcription of the TGF-beta(1) gene. It is essential to know which transcription pathways are activated because of the wide distribution of TNF-alpha and TGF-beta(1), the general lack of effective treatments for fibroproliferative disease and the possibility that targeting the correct transcription factors could be palliative.

Heat shock protein 70 protects against bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) involves infiltration of leucocytes, pulmonary injury, fibrosis and resulting pulmonary dysfunction. Myofibroblasts and transforming growth factor (TGF)-beta1 have been suggested to play a major role in the pathology and the myofibroblasts are derived from both lung epithelial cells through epithelial-mesenchymal transition (EMT) and activation of lung fibroblasts. Heat shock protein 70 (HSP70) confers protection against various stressors and has the anti-inflammatory activity. In this study, we examined the effect of expression of HSP70 on bleomycin-induced pulmonary fibrosis in mice, a tentative animal model of IPF. Bleomycin-induced pulmonary injury and inflammatory response were ameliorated in transgenic mice overexpressing HSP70 compared to wild-type mice, even though bleomycin-induced pulmonary fibrosis and dysfunction were also suppressed in the transgenic mice. The production of TGF-beta1 and expression of pro-inflammatory cytokines was lower in cells from the transgenic mice than wild-type mice after the administration of bleomycin. In vitro, the suppression of HSP70 expression stimulated TGF-beta1-induced EMT-like phenotypes of epithelial cells but did not affect the TGF-beta1-dependent activation of fibroblasts. Orally administered geranylgeranylacetone (GGA), a clinically used drug with HSP-inducing activity, conferred protection against bleomycin-induced pulmonary injury, as well as against the inflammatory response, fibrosis and dysfunction. These results suggest that HSP70 plays a protective role against bleomycin-induced pulmonary injury, inflammation, fibrosis and dysfunction through cytoprotective effects and by inhibiting the production of TGF-beta1, TGF-beta1-dependent EMT of epithelial cells and expression of pro-inflammatory cytokines. Results also suggest that HSP70-inducing drugs, such as GGA, could be beneficial in the prophylaxis of IPF.