Tranilast Inhibits Pulmonary Fibrosis by Suppressing TGFβ/SMAD2 Pathway

Purpose

Idiopathic pulmonary fibrosis (IPF) is characterized by the accumulation of extracellular matrix (ECM) protein in the lungs. Transforming growth factor (TGF) β-induced ECM protein synthesis contributes to the development of IPF. Tranilast, an anti-allergy drug, suppresses TGFβ expression and inhibits interstitial renal fibrosis in animal models. However, the beneficial effects of tranilast or its mechanism as a therapy for pulmonary fibrosis have not been clarified.

Methods

We investigated the in vitro effect of tranilast on ECM production and TGFβ/SMAD2 pathway in TGFβ2-stimulated A549 human alveolar epithelial cells, using quantitative polymerase chain reaction, Western blotting, and immunofluorescence. In vitro observations were validated in the lungs of a murine pulmonary fibrosis model, which we developed by intravenous injection of bleomycin.

Results

Treatment with tranilast suppressed the expression of ECM proteins, such as fibronectin and type IV collagen, and attenuated SMAD2 phosphorylation in TGFβ2-stimulated A549 cells. In addition, based on a wound healing assay in these cells, tranilast significantly inhibited cell motility, with foci formation that comprised of ECM proteins. Histological analyses revealed that the administration of tranilast significantly attenuated lung fibrosis in mice. Furthermore, tranilast treatment significantly reduced levels of TGFβ, collagen, fibronectin, and phosphorylated SMAD2 in pulmonary fibrotic tissues in mice.

Conclusion

These findings suggest that tranilast inhibits pulmonary fibrosis by suppressing TGFβ/SMAD2-mediated ECM protein production, presenting tranilast as a promising and novel anti-fibrotic agent for the treatment of IPF.

p19Arf Exacerbates Cigarette Smoke-Induced Pulmonary Dysfunction

Senescent cells accumulate in tissues during aging or pathological settings. The semi-genetic or pharmacological targeting of senescent cells revealed that cellular senescence underlies many aspects of the aging-associated phenotype and diseases. We previously reported that cellular senescence contributes to aging- and disease-associated pulmonary dysfunction. We herein report that the elimination of Arf-expressing cells ameliorates cigarette smoke-induced lung pathologies in mice. Cigarette smoke induced the expression of Ink4a and Arf in lung tissue with concomitant increases in lung tissue compliance and alveolar airspace. The elimination of Arf-expressing cells prior to cigarette smoke exposure protected against these changes. Furthermore, the administration of cigarette smoke extract lead to pulmonary dysfunction, which was ameliorated by subsequent senescent cell elimination. Collectively, these results suggest that senescent cells are a potential therapeutic target for cigarette smoking-associated lung disease.

Lung Fixation under Constant Pressure for Evaluation of Emphysema in Mice

Emphysema is a significant feature of chronic obstructive pulmonary disease (COPD). Studies involving an emphysematous mouse model require optimal lung fixation to produce reliable histological specimens of the lung. Due to the nature of the lung's structural composition, which consists largely of air and tissue, there is a risk that it collapses or deflates during the fixation process. Various lung fixation methods exist, each of which has its own advantages and disadvantages. The lung fixation method presented here utilizes constant pressure to enable optimal tissue evaluation for studies using an emphysematous mouse lung model. The main advantage is that it can fix many lungs with the same condition at one time. Lung specimens are obtained from chronic cigarette smoke-exposed mice. Lung fixation is performed using specialized equipment that enables the production of constant pressure. This constant pressure maintains the lung in a reasonably inflated state. Thus, this method generates a histological specimen of the lung that is suitable to evaluate cigarette smoke-induced mild emphysema.

Elimination of p19ARF -expressing cells protects against pulmonary emphysema in mice

Senescent cells accumulate in tissues during aging and are considered to underlie several aging‐associated phenotypes and diseases. We recently reported that the elimination of p19^ARF‐expressing senescent cells from lung tissue restored tissue function and gene expression in middle‐aged (12‐month‐old) mice. The aging of lung tissue increases the risk of pulmonary diseases such as emphysema, and cellular senescence is accelerated in emphysema patients. However, there is currently no direct evidence to show that cellular senescence promotes the pathology of emphysema, and the involvement of senescence in the development of this disease has yet to be clarified. We herein demonstrated that p19^ARF facilitated the development of pulmonary emphysema in mice. The elimination of p19^ARF‐expressing cells prevented lung tissue from elastase‐induced lung dysfunction. These effects appeared to depend on reduced pulmonary inflammation, which is enhanced after elastase stimulation. Furthermore, the administration of a senolytic drug that selectively kills senescent cells attenuated emphysema‐associated pathologies. These results strongly suggest the potential of senescent cells as therapeutic/preventive targets for pulmonary emphysema.

CD44 silencing decreases the expression of stem cell-related factors induced by transforming growth factor β1 and tumor necrosis factor α in lung cancer: Preliminary findings

The mechanism underlying increased concentrations of cancer stem cell (CSC)-associated factors in non-small cell lung cancer (NSCLC) cells treated with transforming growth factor β1 (TGFβ1) and tumor necrosis factor α (TNFα), is still not clear. The purpose of this study was to investigate the possible role of CD44 in the regulation of CSC-associated genes, by analyzing the effect of CD44 knockdown on their expression. A549, a NSCLC cell line that expresses CD44 antigen, was treated with TGFβ1 and TNFα. Small-interfering ribonucleic acid (siRNA) that specifically targets the CD44 gene was used to knockdown the expression of CD44 in A549. The gene expressions of CD44, CXCR4, POU5F1 (octamer-binding transcription factor 4 [Oct4]), PROM1, NANOG, c-Myc, KLF4, and SOX2, as well as of CDH1 (E-cadherin), CDH2 (N-cadherin), VIM (vimentin), and FN1 (fibronectin) were analyzed in A549 cells by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Cell morphology was observed using light microscopy. After TGFβ1/TNFα treatment, increased expressions of CXCR4 and POU5F1 were detected. Silencing of CD44 gene expression was confirmed by RT-qPCR. The knockdown of CD44 decreased the CXCR4 and POU5F1 gene expressions in TGFβ1/TNFα-treated A549 cells. However, the silencing of CD44 did not affect the morphology of TGFβ1/TNFα-treated A549 cells nor it reversed epithelial-mesenchymal transition (EMT) gene signature induced by TGFβ1/TNFα in A549 cells. Our preliminary findings suggest that the CD44 gene may have a role in regulating CXCR4 and POU5F1 gene expressions, independently of the EMT signaling pathway.

Birt–Hogg–Dubé syndrome in an Indonesian patient with folliculin gene mutation

Birt–Hogg–Dubé (BHD) syndrome is a rare autosomal dominant disorder that affects the skin, kidney, and lungs. Affected individuals have an increased risk of developing multiple cysts in the lungs and a spontaneous pneumothorax. Germline mutations in the folliculin (FLCN) gene have been confirmed as the aetiology of BHD syndrome. A 51‐year‐old Indonesian female presented with recurrent spontaneous pneumothorax, multiple cysts in both lungs, and a renal cyst on magnetic resonance imaging (MRI). Blood sampling was performed to extract genomic DNA from peripheral blood leucocytes. We identified an aberrant band in the DNA fragment derived from FLCN exon 6. Moreover, direct sequencing of FLCN exon 6 by denaturing high‐performance liquid chromatography (DHPLC) showed a pathogenic mutation, which caused premature termination of folliculin protein translation. This is the first reported case of BHD syndrome in an Indonesian patient confirmed by detection of a FLCN exon 6 mutation.

MicroRNAs as Therapeutic Targets in Lung Disease: Prospects and Challenges

MicroRNAs (miRNAs) are small non-coding RNAs that regulate multiple target genes providing fine-tuned coordinated expression. Growing evidence suggests that miRNAs play important roles in lung development and the pathogenesis of lung disease and that they have great potential as novel therapeutic targets for the treatment of diseases such as lung cancer, asthma, pulmonary fibrosis, and chronic obstructive pulmonary disease (COPD). We have previously shown that miR-146a is a promising therapeutic target for controlling abnormal inflammatory response in COPD through a series of in vitro experiments in lung fibroblasts. However, further investigations in in vivo experimental models are needed to explore the role of miR-146a in the pathogenesis and therapy of COPD. Recently, miRNAs encapsulated in extracellular vesicles (EVs) have been recognized as modulators of intercellular communication. EVs, therefore, may also have therapeutic potential and show promise for use as biomarkers for various lung diseases. In addition to miRNAs, we briefly discuss a specific long non-coding RNA (lncRNA) that may contribute to the pathogenesis of COPD. The application of miRNA-based therapeutics faces several challenges related to mode of delivery, stability, and tissue specificity. However, recent advances in nanotechnology are expected to prove valuable for the development of miRNA-based therapeutics to treat lung disease.

Strategies for an effective tobacco harm reduction policy in Indonesia

Tobacco consumption is a major causative agent for various deadly diseases such as coronary artery disease and cancer. It is the largest avoidable health risk in the world, causing more problems than alcohol, drug use, high blood pressure, excess body weight or high cholesterol. As countries like Indonesia prepare to develop national policy guidelines for tobacco harm reduction, the scientific community can help by providing continuous ideas and a forum for sharing and distributing information, drafting guidelines, reviewing best practices, raising funds, and establishing partnerships. We propose several strategies for reducing tobacco consumption, including advertisement interference, cigarette pricing policy, adolescent smoking prevention policy, support for smoking cessation therapy, special informed consent for smokers, smoking prohibition in public spaces, career incentives, economic incentives, and advertisement incentives. We hope that these strategies would assist people to avoid starting smoking or in smoking cessation.

Treatment with insulin-like growth factor 1 receptor inhibitor reverses hypoxia-induced epithelial-mesenchymal transition in non-small cell lung cancer

Insulin-like growth factor 1 receptor (IGF1R) is expressed in many types of solid tumors including non-small cell lung cancer (NSCLC), and enhanced activation of IGF1R is thought to reflect cancer progression. Epithelial-mesenchymal transition (EMT) has been established as one of the mechanisms responsible for cancer progression and metastasis, and microenvironment conditions, such as hypoxia, have been shown to induce EMT. The purposes of this study were to address the role of IGF1R activation in hypoxia-induced EMT in NSCLC and to determine whether inhibition of IGF1R might reverse hypoxia-induced EMT. Human NSCLC cell lines A549 and HCC2935 were exposed to hypoxia to investigate the expression of EMT-related genes and phenotypes. Gene expression analysis was performed by quantitative real-time PCR and cell phenotypes were studied by morphology assessment, scratch wound assay, and immunofluorescence. Hypoxia-exposed cells exhibited a spindle-shaped morphology with increased cell motility reminiscent of EMT, and demonstrated the loss of E-cadherin and increased expression of fibronectin and vimentin. Hypoxia also led to increased expression of IGF1, IGF binding protein-3 (IGFBP3), and IGF1R, but not transforming growth factor β1 (TGFβ1). Inhibition of hypoxia-inducible factor 1α (HIF1α) with YC-1 abrogated activation of IGF1R, and reduced IGF1 and IGFBP3 expression in hypoxic cells. Furthermore, inhibition of IGF1R using AEW541 in hypoxic condition restored E-cadherin expression, and reduced expression of fibronectin and vimentin. Finally, IGF1 stimulation of normoxic cells induced EMT. Our findings indicated that hypoxia induced EMT in NSCLC cells through activation of IGF1R, and that IGF1R inhibition reversed these phenomena. These results suggest a potential role for targeting IGF1R in the prevention of hypoxia-induced cancer progression and metastasis mediated by EMT.