Induction of EMT-like phenotypes by an active metabolite of leflunomide and its contribution to pulmonary fibrosis. Cell Death Differ. 2010;17:1882-1895. [PMID: 20489727 DOI: 10.1038/cdd.2010.64]

Methotrexate, leflunomide and tacrolimus use and the progression of rheumatoid arthritis-associated interstitial lung disease

OBJECTIVE

To examine the association between MTX, LEF and tacrolimus use and the progression of RA-associated interstitial lung disease (ILD).

METHODS

The Korean RA-ILD cohort prospectively enrolled patients with RA-associated ILD at multiple centres from 2015 to 2018 and followed up with them for 3 years. ILD progression was defined by any of the followings: a decrease of ≥10% in forced vital capacity, a decrease of ≥15% in the diffusing capacity of the lung for carbon monoxide, or death from respiratory failure.

RESULTS

Of 143 patients, 64 patients experienced ILD progression during a median follow-up period of 33 months. The use of MTX [adjusted hazard ratio (aHR), 1.06; 95% CI, 0.59, 1.89], LEF (aHR, 1.75; 95% CI, 0.88, 3.46) and tacrolimus (aHR, 0.94; 95% CI, 0.52, 1.72) did not increase the risk of ILD progression. However, the association between LEF use and the risk of ILD progression was significant in subgroups with poor lung function (aHR, 8.42; 95% CI, 2.61, 27.15). Older age, male sex, a shorter RA duration, higher RA disease activity and extensive disease at baseline were independently associated with ILD progression.

CONCLUSION

None of the three treatments increased the risk of RA-associated ILD progression, except for LEF, which increased the risk of ILD progression in patients with severe ILD. The appropriate use of conventional synthetic disease-modifying antirheumatic drugs considering RA disease activity and ILD severity would be important for the management of RA-associated ILD.

Better Safe than Sorry: Rheumatoid Arthritis, Interstitial Lung Disease, and Medication-A Narrative Review

It is well known that rheumatoid arthritis (RA) patients are at an increased risk of developing non-infectious pulmonary complications, especially interstitial lung disease (ILD); however, the clinician must keep in mind that lung disease could not only be a manifestation of the underlying condition, but also a consequence of using disease-modifying therapies. New-onset ILD or ILD worsening has also been reported as a possible consequence of both conventional disease-modifying antirheumatic drugs (DMARDs) and biologic agents. This study is a narrative review of the current literature regarding the potential risk of developing interstitial lung disease along with the administration of specific drugs used in controlling rheumatoid arthritis. Its purpose is to fill knowledge gaps related to this challenging patient cohort by addressing various aspects of the disease, including prevalence, disease features, treatment strategies, and patient outcomes.

Molecular Mechanisms of Alveolar Epithelial Stem Cell Senescence and Senescence-Associated Differentiation Disorders in Pulmonary Fibrosis

Pulmonary senescence is accelerated by unresolved DNA damage response, underpinning susceptibility to pulmonary fibrosis. Recently it was reported that the SARS-Cov-2 viral infection induces acute pulmonary epithelial senescence followed by fibrosis, although the mechanism remains unclear. Here, we examine roles of alveolar epithelial stem cell senescence and senescence-associated differentiation disorders in pulmonary fibrosis, exploring the mechanisms mediating and preventing pulmonary fibrogenic crisis. Notably, the TGF-β signalling pathway mediates alveolar epithelial stem cell senescence by mechanisms involving suppression of the telomerase reverse transcriptase gene in pulmonary fibrosis. Alternatively, telomere uncapping caused by stress-induced telomeric shelterin protein TPP1 degradation mediates DNA damage response, pulmonary senescence and fibrosis. However, targeted intervention of cellular senescence disrupts pulmonary remodelling and fibrosis by clearing senescent cells using senolytics or preventing senescence using telomere dysfunction inhibitor (TELODIN). Studies indicate that the development of senescence-associated differentiation disorders is reprogrammable and reversible by inhibiting stem cell replicative senescence in pulmonary fibrosis, providing a framework for targeted intervention of the molecular mechanisms of alveolar stem cell senescence and pulmonary fibrosis. Abbreviations: DPS, developmental programmed senescence; IPF, idiopathic pulmonary fibrosis; OIS, oncogene-induced replicative senescence; SADD, senescence-associated differentiation disorder; SALI, senescence-associated low-grade inflammation; SIPS, stress-induced premature senescence; TERC, telomerase RNA component; TERT, telomerase reverse transcriptase; TIFs, telomere dysfunction-induced foci; TIS, therapy-induced senescence; VIS, virus-induced senescence.

NLRP3 inflammasome activation in alveolar epithelial cells promotes myofibroblast differentiation of lung-resident mesenchymal stem cells during pulmonary fibrogenesis

Idiopathic pulmonary fibrosis (IPF) is a lethal and agnogenic interstitial lung disease, which has limited therapeutic options. Recently, the NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome has been demonstrated as an important contributor to various fibrotic diseases following its persistent activation. However, the role of NLRP3 inflammasome in pulmonary fibrogenesis still needs to be further clarified. Here, we found that the activation of the NLRP3 inflammasome was raised in fibrotic lungs. In addition, the NLRP3 inflammasome was found to be activated in alveolar epithelial cells (AECs) in the lung tissue of both IPF patients and pulmonary fibrosis mouse models. Further research revealed that epithelial cells, following activation of the NLRP3 inflammasome, could induce the myofibroblast differentiation of lung-resident mesenchymal stem cells (LR-MSCs). In addition, inhibiting the activation of the NLRP3 inflammasome in epithelial cells promoted the expression of dickkopf-1 (DKK1), a secreted Wnt antagonist. DKK1 was capable of suppressing the profibrogenic differentiation of LR-MSCs and bleomycin-induced pulmonary fibrosis. In conclusion, this study not only provides a further in-depth understanding of the pathogenesis of pulmonary fibrosis, but also reveals a potential therapeutic strategy for disorders associated with pulmonary fibrosis.

Genome-Wide Association Study: Functional Variant rs2076295 Regulates Desmoplakin Expression in Airway Epithelial Cells

Rationale: Genetic association studies have identified rs2076295 in association with idiopathic pulmonary fibrosis (IPF). We hypothesized that rs2076295 is the functional variant regulating DSP (desmoplakin) expression in human bronchial epithelial cells, and DSP regulates extracellular matrix-related gene expression and cell migration, which is relevant to IPF development.Objectives: To determine whether rs2076295 regulates DSP expression and the function of DSP in airway epithelial cells.Methods: Using CRISPR (clustered regularly interspaced short palindromic repeat)/Cas9 editing (including regional deletion, indel, CRISPR interference, and single-base editing), we modified rs2076295 and measured DSP expression in edited 16HBE14o- and primary airway epithelial cells. Cellular integrity, migration, and genome-wide gene expression changes were examined in 16HBE14o- single colonies with DSP knockout. The expression of DSP and its relevant matrix genes was measured by quantitative PCR and also analyzed in single-cell RNA-sequencing data from control and IPF lungs.Measurements and Main Results:DSP is expressed predominantly in bronchial and alveolar epithelial cells, with reduced expression in alveolar epithelial cells in IPF lungs. The deletion of the DNA region-spanning rs2076295 led to reduced expression of DSP, and the edited rs2076295GG 16HBE14o- line has lower expression of DSP than the rs2076295TT lines. Knockout of DSP in 16HBE14o- cells decreased transepithelial resistance but increased cell migration, with increased expression of extracellular matrix-related genes, including MMP7 and MMP9. Silencing of MMP7 and MMP9 abolished increased migration in DSP-knockout cells.Conclusions: rs2076295 regulates DSP expression in human airway epithelial cells. The loss of DSP enhances extracellular matrix-related gene expression and promotes cell migration, which may contribute to the pathogenesis of IPF.

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.

The role of Chinese herbal medicine in the management of adverse drug reactions of leflunomide in treating rheumatoid arthritis

BACKGROUND

The high discontinuation rate in RA patients who use LEF might be attributed to their intolerance rather than irresponsibility. The concomitant administration of Leflunomide (LEF) with Chinese herbal medicine (CHM) provides a potential solution to preventing the adverse drug reactions (ADRs) induced by LEF during the treatment of rheumatoid arthritis (RA).

PURPOSE

To investigate whether co-administration of LEF with CHM could bring in both increased therapeutic outcomes and reduced ADRs due to the framework of treatment at the level of entire body.

STUDY DESIGN

The mechanism of LEF in RA treatment and the ADRs it induced was introduced based on recent papers. Reported clinical examples of CHM concurrent use with LEF was revealed to provide more evidence. The management of the ADRs caused by LEF was suggested by current researches on the concomitant therapy of CHM with LEF.

RESULTS

The active ingredients, compounds and medicinal herbs all demonstrated properties in relieving toxicities and reducing ADRs when used with LEF and reported in several clinical cases. The wide application of concurrent use of CHM with LEF is however hindered by the complex pathogenesis of RA which requires further scientific grounds for diagnosis and treatment.

CONCLUSION

This review introduced that the adoption of CHM is emerging as a novel strategy for the management of ADRs caused by LEF.

2',3'-Cyclic-nucleotide 3'-phosphodiesterase contributes to epithelial-mesenchymal transition of lens epithelial cells through the notch signalling pathway

Objectives

Fibrosis is a complex process involved in multiple diseases that result in organ injury and failure. Cataract, one common form of ocular fibrosis, is a main cause of blindness worldwide, and surgery may be the only cure. In this regard, epithelial‐mesenchymal transition (EMT) of lens epithelial cells (LECs) is the primary cause of anterior subcapsular cataract (ASC). This study aimed to investigate the mechanism by which 2',3'‐cyclic‐nucleotide 3'‐phosphodiesterase (CNPase) regulates the function of EMT in LECs.

Materials and Methods

A mouse model of ASC was used to observe the expression of CNPase in the lens and correlate its expression changes with lens EMT. Furthermore, the effects of CNPase on cell migration and cell proliferation were evaluated by transwell migration, wound healing and EdU staining assays. Finally, Western blotting and immunofluorescence were used to assess the mechanical properties potentially involved in the regulation of EMT by CNPase.

Results

The expression of CNPase was upregulated in LECs during the EMT process in mice with ASC. Notably, CNPase significantly promoted the proliferation, migration and EMT of LECs in vitro. Interestingly, the EMT‐promoting mechanism of CNPase may be achieved by targeting the Notch signalling pathway.

Conclusions

Considering the involvement of EMT in ASC, both CNPase and the Notch signalling pathway may be therapeutic targets for the treatment of cataracts.

Cancer driver mutations in endometriosis: Variations on the major theme of fibrogenesis

BACKGROUND

One recent study reports cancer driver mutations in deep endometriosis, but its biological/clinical significance remains unclear. Since the natural history of endometriosis is essentially gradual progression toward fibrosis, it is thus hypothesized that the six driver genes reported to be mutated in endometriosis (the RP set) may play important roles in fibrogenesis but not necessarily malignant transformation.

METHODS

Extensive PubMed search to see whether RP and another set of driver genes not yet reported (NR) to be mutated in endometriosis have any roles in fibrogenesis. All studies reporting on the role of fibrogenesis of the genes in both RP and NR sets were retrieved and evaluated in this review.

RESULTS

All six RP genes were involved in various aspects of fibrogenesis as compared with only three NR genes. These nine genes can be anchored in networks linking with their upstream and downstream genes that are known to be aberrantly expressed in endometriosis, piecing together seemingly unrelated findings.

CONCLUSIONS

Given that somatic driver mutations can and do occur frequently in physiologically normal tissues, it is argued that these mutations in endometriosis are not necessarily synonymous with malignancy or premalignancy, but the result of enormous pressure for fibrogenesis.

Ethyl Pyruvate Improves Pulmonary Function in Mice with Bleomycin-induced Lung Injury as Monitored with Hyperpolarized 129Xe MR Imaging

Purpose:

High Mobility Group Box1 (HMGB1), which is one of the damage-associated molecular pattern molecules relating to various inflammatory diseases, has gained interest as a therapeutic target because of its involvement in wound healing processes. In the present study, we investigated HMGB1 as a potential therapeutic target in a model of lung fibrosis using a preclinical hyperpolarized ¹²⁹Xe (HPXe) MRI system.

Methods:

Lung injury was induced by intra-peritoneal injection of bleomycin (BLM) in 19 mice. Three weeks post-injection (when fibrosis was confirmed histologically), administration of ethyl pyruvate (EP) and alogliptin (ALG), which are down- and up-regulators of HMGB1, respectively, was commenced in six and seven of the 19 mice, respectively, and continued for a further 3 weeks. A separate sham-instilled group was formed of five mice, which were administered with saline for 6 weeks. Over the second 3-week period, the effects of disease progression and pharmacological therapy in the four groups of mice were monitored by HPXe MRI metrics of fractional ventilation and gas-exchange function.

Results:

Gas-exchange function in BLM mice was significantly reduced after 3 weeks of BLM challenge compared to sham-instilled mice (P < 0.05). Ethyl pyruvate was found to improve HPXe MRI metrics of both ventilation and gas exchange, and repair tissue damage (assessed histologically), to a similar level as sham-instilled mice (P < 0.05), whilst ALG treatment caused no significant improvement of pulmonary function.

Conclusion:

This study demonstrates the down-regulator of HMGB1, EP, as a potential therapeutic agent for pulmonary fibrosis, as assessed by a non-invasive HPXe MRI protocol.

Folic acid prevents methotrexate-induced epithelial-mesenchymal transition via suppression of secreted factors from the human alveolar epithelial cell line A549

Methotrexate (MTX) often induces serious lung diseases such as pulmonary fibrosis. Although MTX is known to be a folic acid (FA) antagonist, the effect of FA on MTX-induced lung injury remains unclear. Recent studies indicate that epithelial-mesenchymal transition (EMT) is involved in pulmonary fibrosis. Here, we aimed to clarify the effect of FA on MTX-induced EMT in human alveolar epithelial cell line A549 using conditioned medium (CM). CM was prepared from the supernatants of A549 cells treated with MTX in the absence (CMM) or presence (CMMF) of FA. FA suppressed EMT-like morphological changes and elevated mRNA/protein expression levels of α-smooth muscle actin induced by MTX in A549 cells. In addition, CMM induced EMT-like phenotypical changes, whereas CMMF had no effect on the phenotype of A549 cells, indicating that FA may suppress MTX-induced EMT via inhibiting the secretion of certain factors into the supernatant of the cells. Furthermore, FA also prevented CMM-induced EMT-like phenotypical changes in A549 cells. These findings indicate that FA may be a useful pharmaceutical for MTX-induced lung injury.

Triptolide suppresses paraquat induced idiopathic pulmonary fibrosis by inhibiting TGFB1-dependent epithelial mesenchymal transition

Idiopathic pulmonary fibrosis (IPF) and tumor are highly similar to abnormal cell proliferation that damages the body. This malignant cell evolution in a stressful environment closely resembles that of epithelial-mesenchymal transition (EMT). As a popular EMT-inducing factor, TGFβ plays an important role in the progression of multiple diseases. However, the drugs that target TGFB1 are limited. In this study, we found that triptolide (TPL), a Chinese medicine extract, exerts an anti-lung fibrosis effect by inhibiting the EMT of lung epithelial cells. In addition, triptolide directly binds to TGFβ and subsequently increase E-cadherin expression and decrease vimentin expression. In in vivo studies, TPL improves the survival state and inhibits lung fibrosis in mice. In summary, this study revealed the potential therapeutic effect of paraquat induced TPL in lung fibrosis by regulating TGFβ-dependent EMT progression.

Therapeutic pro-fibrogenic signaling pathways in fibroblasts

Myofibroblasts (MFs) play a critical role in the progression of chronic inflammatory and fibroproliferative diseases in different tissues/organs, whatever the etiology. Fibrosis is preceded and sustained by persistent injury and inflammatory response in a profibrogenic scenario involving mutual interactions, operated by several mediators and pathways, of MFs and related precursor cells with innate immunity cells and virtually any cell type in a defined tissue. These interactions, mediators and related signaling pathways are critical in initiating and perpetuating the differentiation of precursor cells into MFs that in different tissues share peculiar traits and phenotypic responses, including the ability to proliferate, produce ECM components, migrate and contribute to the modulation of inflammatory response and tissue angiogenesis. Literature studies related to liver, lung and kidney fibrosis have outlined a number of MF-related core regulatory fibrogenic signaling pathways conserved across these different organs and potentially targetable in order to develop effective antifibrotic therapeutic strategies.

Advanced Oxidation Protein Products Induce Epithelial-Mesenchymal Transition of Intestinal Epithelial Cells via a PKC δ-Mediated, Redox-Dependent Signaling Pathway

AIMS

Epithelial-mesenchymal transition (EMT) has been considered a fundamental mechanism in complications of Crohn's disease (CD), especially intestinal fibrosis. However, the mechanism underlying EMT regulation in intestinal fibrosis remains unclear. This study aimed to investigate the role of advanced oxidation protein products (AOPPs) in the occurrence of intestinal EMT.

RESULTS

AOPPs accumulated in CD tissues and were associated with EMT marker expression in fibrotic lesions from CD patients. Challenge with AOPPs induced intestinal epithelial cell (IEC) phenotype transdifferentiation, fibroblast-like phenotype acquisition, and production of extracellular matrix, both in vitro and in vivo. The effect of AOPPs was mainly mediated by a protein kinase C (PKC) δ-mediated redox-dependent pathway, including phosphorylation of PKC δ, recruitment of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, production of reactive oxygen species, and NF-κB p65 activation. Inhibition of AOPP-redox signaling activation effectively blocked AOPP-induced EMT in vitro. Studies performed in normal rats showed that chronic administration of AOPPs triggered the occurrence of EMT in rat intestinal epithelia, accompanied by disruption of intestinal integrity, and by promotion of collagen deposition. These effects could be reversed by inhibition of NADPH oxidase. Innovation and Conclusion: This is the first study to demonstrate that AOPPs triggered the occurrence of EMT in IECs in vitro and in vivo through PKC δ-mediated redox-dependent signaling. Our study identifies the role of AOPPs and, in turn, EMT in intestinal fibrosis and provides novel potential targets for the treatment of intestinal fibrotic diseases. Antioxid. Redox Signal. 27, 37-56.

Cu,Zn-Superoxide Dismutase-Mediated Redox Regulation of Jumonji Domain Containing 3 Modulates Macrophage Polarization and Pulmonary Fibrosis

M2 macrophages are implicated in the development of pulmonary fibrosis as they generate profibrotic signals. The polarization process, at least in part, is regulated by epigenetic modulation. Because Cu,Zn-superoxide dismutase-induced H2O2 can polarize macrophages to a profibrotic M2 phenotype, we hypothesized that modulation of the redox state of the cell is involved in the epigenetic modulation of the macrophage phenotype. In this study, we show that signal transducer and activator of transcription 6 (STAT6) regulates Jumonji domain containing (Jmjd) 3, a histone H3 lysine 27 demethylase, and mutation of a redox-sensitive cysteine in STAT6 attenuates jmjd3 expression. Moreover, Jmjd3 deficiency abrogates profibrotic M2 gene expression. Treatment with leflunomide, which reduces mitochondrial reactive oxygen species production and tyrosine phosphorylation, inhibits jmjd3 expression and M2 polarization, as well as development of a fibrotic phenotype. Taken together, these observations provide evidence that the redox regulation of Jmjd3 is a unique regulatory mechanism for Cu,Zn-superoxide dismutase-mediated profibrotic M2 polarization. Furthermore, leflunomide, which reduces reactive oxygen species production and tyrosine phosphorylation, may prove to be therapeutic in the treatment of asbestos-induced pulmonary fibrosis.

Melatonin attenuates TGFβ1-induced epithelial-mesenchymal transition in lung alveolar epithelial cells

Idiopathic pulmonary fibrosis (IPF) is the most common interstitial lung disease. However, the pathogenesis remains to be fully elucidated. Melatonin is secreted by the pineal gland, it has a strong antioxidant effect, and exerts an anti-fibrosis effect. Whether melatonin attenuates pulm -onary fibrosis by inhibiting epithelial‑mesenchymal transition (EMT) requires further research. The present study aimed to investigate whether melatonin prevents transforming growth factor‑β1 (TGF‑β1)‑induced EMT and underlying signaling pathways using reverse transcription‑quantitative polymerase chain reaction, western blot analysis and immunofluorescence. The results demonstrated that melatonin inhibits EMT in A549 cells, and the Wnt/β‑catenin and Smad2/3 signaling pathways are involved in the EMT of the A549 cell line as they were suppressed by melatonin. The present study indicates that melatonin inhibited TGFβ1‑induced epithelial‑mesenchymal transition in the A549 cell line and may potentially be useful in the treatment of IPF.

Lung involvement in inflammatory rheumatic diseases

This chapter describes the involvement of the lung in systemic inflammatory joint disease (IJD) with a particular focus on rheumatoid arthritis, although the topics of pulmonary involvement in ankylosing spondylitis and psoriatic arthritis are also addressed. Interstitial lung disease is the most lethal pulmonary complication of IJD and the chapter describes recent advances in both our understanding of this complication and the therapeutic options that offer real hope for improved outcomes. Although less well recognised, airways disease is just as common and its association with IJD is described in some detail, with a section devoted to the recent surge in interest in bronchiectasis. Acute pulmonary infection is common in IJD and its management is reviewed in some detail. Although pleural disease is less common than it once was, its treatment is explored. We conclude by reviewing the relationship between the drug therapies employed in IJD and their effects on the lung.

Bleomycin (BLM) Induces Epithelial-to-Mesenchymal Transition in Cultured A549 Cells via the TGF-β/Smad Signaling Pathway

The epithelial-to-mesenchymal transition (EMT) is a crucial cellular event in wound healing, tissue repair, and cancer progression in adult tissues, with the interactions with numerous signals. In this study, we aimed to determine whether bleomycin (BLM), an agent that causes pulmonary fibrosis, induces the EMT of the alveolar epithelial cell line A549 and investigated the possible mechanisms. We examined the EMT involved changes in cell morphology, isoform switching of the fibroblast growth factor receptor 2 (FGFR2) by alternative splicing, and expression of the phenotypic markers including E-cadherin, vimentin, and α-SMA using RT-PCR, Western blotting, and immunofluorescence assays. A TGF-β/Smad inhibitor was used to determine whether coculture with BLM would inhibit the EMT of A549 cells. The results showed that BLM induced the EMT of A549 cells possibly via the TGF-β/Smad signaling pathway, evident from the decrease in the expression of E-cadherin and increase in the expression on vimentin.

Notch signaling in lung diseases: focus on Notch1 and Notch3

Notch signaling is an evolutionarily conserved cell–cell communication mechanism that plays a key role in lung homeostasis, injury and repair. The loss of regulation of Notch signaling, especially Notch1 and Notch3, has recently been linked to the pathogenesis of important lung diseases, in particular, chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis, pulmonary arterial hypertension (PAH), lung cancer and lung lesions in some congenital diseases. This review focuses on recent advances related to the mechanisms and the consequences of aberrant or absent Notch1/3 activity in the initiation and progression of lung diseases. Our increasing understanding of this signaling pathway offers great hope that manipulating Notch signaling may represent a promising alternative complementary therapeutic strategy in the future.

Diffuse alveolar damage in a patient with rheumatoid arthritis under prolonged leflunomide treatment: A Case Report and Literature Review

Patients with rheumatoid arthritis (RA) often have pulmonary involvement, and interstitial lung disease (ILD) is the primary manifestation, in which diffuse alveolar damage (DAD) is a rare histopathologic pattern. Leflunomide (LEF) is a frequently prescribed disease-modifying antirheumatic drug for treating RA. LEF-related ILD in the form of DAD has been reported in patients with RA, with the duration of LEF treatment before symptom onset ranging from 6 to 1204 days.We present a case of elderly woman with RA under prolonged LEF treatment for >9 years (3291 days), who had acute respiratory failure with the initial presentation of exertional dyspnea, fever, chills, and productive cough for 2 days. The histopathologic result of surgical lung biopsy was compatible with DAD. She was diagnosed as having LEF-related ILD, based on correlated clinical history, compatible histopathologic examination and excluding possible infection after extensive survey.Although the causative role of LEF cannot be confirmed, this case still hints that LEF-related DAD may occur even if LEF has been prescribed for a prolonged period.

Notch in fibrosis and as a target of anti-fibrotic therapy

The Notch pathway represents a highly conserved signaling network with essential roles in regulation of key cellular processes and functions, many of which are critical for development. Accumulating evidence indicates that it is also essential for fibrosis and thus the pathogenesis of chronic fibroproliferative diseases in diverse organs and tissues. Different effects of Notch activation are observed depending on cellular and tissue context as well as in both physiologic and pathologic states. Close interactions of Notch signaling pathway with other signaling pathways have been identified. In this review, current knowledge on the role of the Notch signaling with special focus on fibrosis and its potential as a therapeutic target is summarized.

Rheumatoid arthritis-associated lung disease

Comprehensive, up-to-date review of RA-associated lung diseases including pathogenesis and managementhttp://ow.ly/FBaNZ

Interstitial lung disease in rheumatoid arthritis: Current concepts in pathogenesis, diagnosis and therapeutics

Rheumatoid arthritis (RA) is the most common chronic autoimmune inflammatory joint disease. RA-associated interstitial lung disease (RA-ILD) is a major extra-articular complication and causes symptoms that lead to a deterioration in the quality of life, high utilization of health resources, and an increased risk of earlier mortality. Early in the course of RA-ILD, symptoms are highly variable, making the diagnosis difficult. Therefore, a rational diagnostic strategy that combines an adequate clinical assessment with the appropriate use of clinical tests, including pulmonary function tests and high-resolution computed tomography, should be used. In special cases, lung biopsy or bronchioalveolar lavage should be performed to achieve an early diagnosis. Several distinct histopathological subtypes of RA-ILD are currently recognized. These subtypes also have different clinical presentations, which vary in therapeutic response and prognosis. This article reviews current evidence about the epidemiology of RA-ILD and discusses the varying prevalence rates observed in different studies. Additionally, aspects of RA-ILD pathogenesis, including the role of cytokines and other molecules such as autoantibodies, as well as the evidence linking several drugs used to treat RA with lung damage will be discussed. Some aspects of the clinical characteristics of RA-ILD are noted, and diagnostic strategies are reviewed. Finally, this article analyzes current treatments for RA-ILD, including immunosuppressive therapies and biologic agents, as well as other therapeutic modalities. The prognosis of this severe complication of RA is discussed. Additionally, this paper examines updated evidence from studies identifying an association between drugs used for the treatment of RA and the development of ILD.

Involvement of epithelial-mesenchymal transition in methotrexate-induced pulmonary fibrosis

Epithelial-mesenchymal transition (EMT) plays a pivotal event in the development of pulmonary fibrosis. We have previously reported that methotrexate (MTX)-induced alveolar epithelial cell injury followed by pulmonary fibrosis as a result of the recruitment and proliferation of myofibroblasts. However, there is no data concerning whether EMT occurs in MTX-induced pulmonary fibrosis. In the present study, therefore, we investigated the expression of EMT markers such as E-cadherin, α-SMA, and vimentin by immunofluorescence analysis in mouse lung tissues after administration of MTX. We found that vimentin and α-SMA-positive cells of the MTX-induced pulmonary fibrosis were increased; on the other hand, E-cadherin was decreased, indicating that epithelial cells act as the main source of mesenchymal expansion. These results exhibited the down-regulation of E-cadherin expression and the up-regulation of α-smooth muscle actin (α-SMA) in primary mouse alveolar epithelial cells (MAECs) and A549 cell lines. Additionally, MTX-induced A549 cells exhibited an EMT-like phenotype accompanied by the elevation of the expression of interleukin-6 (IL-6) and transforming growth factor (TGF)-β1, as well as an enhancement of migration. All of these findings suggest that MTX-induced pulmonary fibrosis occurs via EMT.

Comparative analysis of ER stress response into HIV protease inhibitors: lopinavir but not darunavir induces potent ER stress response via ROS/JNK pathway

HIV protease inhibitor (PI)-induced ER stress has been associated with adverse effects. Although it is a serious clinical problem for HIV/AIDS patients, comparative analyses of ER stress induction by clinically used PIs have rarely been done. Especially, there is no report on the differential ER stress response between lopinavir (LPV) and darunavir (DRV), although these PIs are the most clinically used PIs. We show here that LPV induces the most potent CHOP expression, ER stress marker, among the 9 Food and Drug Administration (FDA)-approved PIs in human peripheral blood mononuclear cells, several human epithelial cells, and mouse embryonic fibroblasts. LPV induced the most potent ROS production and JNK activation in 9 PIs. A comparison among the most clinically used PIs, ritonavir (RTV), LPV, and DRV, revealed that LPV potently and RTV moderately but not DRV induced ER stress via ROS-dependent JNK activation rather than proteasome inhibition. Finally, we analyzed ER stress induction in tissues of mice intraperitoneally injected with RTV, LPV, and DRV. RTV and LPV but not DRV showed ER stress induction in several mice tissues. In conclusion, we first identify LPV as the most potent ER stress inducing PI among 9 FDA-approved PIs in human cells, and although clinical verification is necessary, we show here that DRV has the advantage of less ROS and ER stress induction potential compared with LPV in vitro and in vivo.

The multifaceted aspects of interstitial lung disease in rheumatoid arthritis

Interstitial lung disease (ILD) is a relevant extra-articular manifestation of rheumatoid arthritis (RA) that may occur either in early stages or as a complication of long-standing disease. RA related ILD (RA-ILD) significantly influences the quoad vitam prognosis of these patients. Several histopathological patterns of RA-ILD have been described: usual interstitial pneumonia (UIP) is the most frequent one, followed by nonspecific interstitial pneumonia (NSIP); other patterns are less commonly observed. Several factors have been associated with an increased risk of developing RA-ILD. The genetic background plays a fundamental but not sufficient role; smoking is an independent predictor of ILD, and a correlation with the presence of rheumatoid factor and anti-cyclic citrullinated peptide antibodies has also been reported. Moreover, both exnovo occurrence and progression of ILD have been related to drug therapies that are commonly prescribed in RA, such as methotrexate, leflunomide, anti-TNF alpha agents, and rituximab. A greater understanding of the disease process is necessary in order to improve the therapeutic approach to ILD and RA itself and to reduce the burden of this severe extra-articular manifestation.

Esophageal epithelial and mesenchymal cross-talk leads to features of epithelial to mesenchymal transition in vitro

BACKGROUND

Esophageal fibrosis is a complication of eosinophilic esophagitis (EoE) which has been attributed to both subepithelial fibrosis and to epithelial to mesenchymal transition (EMT), a process by which epithelial cells acquire mesenchymal features. Common to both causes of EoE-fibrosis is the notion that granulocyte-derived TGF-β, induces myofibroblast differentiation of the target cell. To date, the role of esophageal epithelial cells as effector cells in esophageal fibrosis has never been explored. Herein, we investigated consequences of cross-talk between esophageal epithelial cells and fibroblasts, and identified profibrotic cytokines which influence the development of EMT in vitro.

METHODS AND RESULTS

Stimulation of primary fetal esophageal fibroblasts (FEF3) with conditioned media (CEM) from esophageal epithelial cells (EPC2-hTERT), primed FEF3 cells to secrete IL-1β and TNFα, but not TGFβ. To determine whether these cytokines signaled in a paracrine fashion to esophageal epithelial cells, FEF3 cells were stimulated with CEM, followed by transfer of this fibroblast conditioned media (FCM) to EPC2-hTERT cells. Epithelial FCM stimulation increased expression of mesenchymal markers and reduced E-cadherin expression, features of EMT which were TNFα and IL-1β-dependent. Using organotypic culture models, primary EoE epithelial cells exhibited features of EMT compared to non-EoE cells, corresponding to patterns of EMT in native biopsies.

CONCLUSIONS

Esophageal epithelial cell and fibroblast cross-talk contributes to esophageal fibrosis. Our results suggest that features of EMT can develop independent of TGF-β and granulocytes, which may have important implications in treatment of EoE.

Suppression of expression of heat shock protein 70 by gefitinib and its contribution to pulmonary fibrosis

Drug-induced interstitial lung disease (ILD), particularly pulmonary fibrosis, is of serious clinical concern. Gefitinib, a tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR), is beneficial as a drug for treating non-small cell lung cancer; however, this drug induces ILD and the molecular mechanisms underpinning this condition remain unclear. We recently reported that expression of heat shock protein 70 (HSP70) protects against bleomycin-induced pulmonary fibrosis, an animal model of pulmonary fibrosis. In this study, we have examined the effects of drugs known to induce ILD clinically on the expression of HSP70 in cultured lung epithelial cells and have found that gefitinib has a suppressive effect. Results of a luciferase reporter assay, pulse-labelling analysis of protein and experiments using an inhibitor of translation or transcription suggest that gefitinib suppresses the expression of HSP70 at the level of translation. Furthermore, the results of experiments with siRNA for Dicer1, an enzyme responsible for synthesis of microRNA, and real-time RT-PCR analysis suggest that some microRNAs are involved in the gefitinib-induced translational inhibition of HSP70. Mutations in the EGFR affect the concentration of gefitinib required for suppressing the expression of HSP70. These results suggest that gefitinib suppresses the translation of HSP70 through an EGFR- and microRNA-mediated mechanism. In vivo, while oral administration of gefitinib suppressed the pulmonary expression of HSP70 and exacerbated bleomycin-induced pulmonary fibrosis in wild-type mice, these effects were not as distinct in transgenic mice expressing HSP70. Furthermore, oral co-administration of geranylgeranylacetone (GGA), an inducer of HSP70, suppressed gefitinib-induced exacerbation of bleomycin-induced pulmonary fibrosis. Taken together, these findings suggest that gefitinib-induced exacerbation of bleomycin-induced pulmonary fibrosis is mediated by suppression of pulmonary expression of HSP70 and that an inducer of HSP70 expression, such as GGA, may be therapeutically beneficial for the treatment of gefitinib-induced pulmonary fibrosis.

Notch signaling may negatively regulate neonatal rat cardiac fibroblast-myofibroblast transformation

Cardiac fibroblast-myofibroblast transformation (CMT) is a critical event in the initiation of myocardial fibrosis. Notch signaling has been shown to regulate myofibroblast transformation from other kinds of cells. However, whether Notch signaling is also involved in CMT remains unclear. In the present study, expressions of Notch receptors in cardiac fibroblasts (CFs) were examined, effects of Notch signaling inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) and transforming growth factor-beta1 (TGF-beta1) on CMT were determined by increasing alpha-smooth muscle actin (alpha-SMA) expression and collagen synthesis, and Notch signaling was examined by analyzing expressions of Notch receptors. The results showed that: (1) Notch receptor 1, 2, 3 and 4 were all expressed in CFs; (2) DAPT promoted CMT in a time-dependent manner; (3) During the period of CMT induced by TGF-beta1, expressions of Notch receptor 1, 3 and 4 in CFs were down-regulated, whereas there was no change for Notch receptor 2. Moreover, the downtrends of Notch 1, 3 and 4 were corresponding to the trend growth of alpha-SMA expression and collagen synthesis. These results suggested that inhibiting of Notch signaling might promote CMT. The down-regulations of Notch receptor 1, 3 and 4 induced by TGF-beta1 may facilitate CMT. In conclusion, inhibition of Notch signaling might be a novel mechanism of CMT in myocardial fibrosis.

Human glycolipid transfer protein (GLTP) expression modulates cell shape

Glycolipid transfer protein (GLTP) accelerates glycosphingolipid (GSL) intermembrane transfer via a unique lipid transfer/binding fold (GLTP-fold) that defines the GLTP superfamily and is the prototype for GLTP-like domains in larger proteins, i.e. phosphoinositol 4-phosphate adaptor protein-2 (FAPP2). Although GLTP-folds are known to play roles in the nonvesicular intracellular trafficking of glycolipids, their ability to alter cell phenotype remains unexplored. In the present study, overexpression of human glycolipid transfer protein (GLTP) was found to dramatically alter cell phenotype, with cells becoming round between 24 and 48 h after transfection. By 48 h post transfection, ∼70% conversion to the markedly round shape was evident in HeLa and HEK-293 cells, but not in A549 cells. In contrast, overexpression of W96A-GLTP, a liganding-site point mutant with abrogated ability to transfer glycolipid, did not alter cell shape. The round adherent cells exhibited diminished motility in wound healing assays and an inability to endocytose cholera toxin but remained viable and showed little increase in apoptosis as assessed by poly(ADP-ribose) polymerase cleavage. A round cell phenotype also was induced by overexpression of FAPP2, which binds/transfers glycolipid via its C-terminal GLTP-like fold, but not by a plant GLTP ortholog (ACD11), which is incapable of glycolipid binding/transfer. Screening for human protein partners of GLTP by yeast two hybrid screening and by immuno-pulldown analyses revealed regulation of the GLTP-induced cell rounding response by interaction with δ-catenin. Remarkably, while δ-catenin overexpression alone induced dendritic outgrowths, coexpression of GLTP along with δ-catenin accelerated transition to the rounded phenotype. The findings represent the first known phenotypic changes triggered by GLTP overexpression and regulated by direct interaction with a p120-catenin protein family member.