Pathology Of Idiopathic Pulmonary Fibrosis Research Articles

Proteolysis and Contractility Regulate Tissue Opening and Wound Healing by Lung Fibroblasts in 3D Microenvironments.

Damage and repair are recurring processes in tissues, with fibroblasts playing key roles by remodeling extracellular matrices (ECM) through protein synthesis, proteolysis, and cell contractility. Dysregulation of fibroblasts can lead to fibrosis and tissue damage, as seen in idiopathic pulmonary fibrosis (IPF). In advanced IPF, tissue damage manifests as honeycombing, or voids in the lungs. This study explores how transforming growth factor-beta (TGF-β), a crucial factor in IPF, induces lung fibroblast spheroids to create voids in reconstituted collagen through proteolysis and cell contractility, a process is termed as hole formation. These voids reduce when proteases are blocked. Spheroids mimic fibroblast foci observed in IPF. Results indicate that cell contractility mediates tissue opening by stretching fractures in the collagen meshwork. Matrix metalloproteinases (MMPs), including MMP1 and MT1-MMP, are essential for hole formation, with invadopodia playing a significant role. Blocking MMPs reduces hole size and promotes wound healing. This study shows how TGF-β induces excessive tissue destruction and how blocking proteolysis can reverse damage, offering insights into IPF pathology and potential therapeutic interventions.

DNA methylation modification in Idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and irreversible interstitial lung disease with a prognosis worse than lung cancer. It is a fatal lung disease with largely unknown etiology and pathogenesis, and no effective therapeutic drugs render its treatment largely unsuccessful. With continuous in-depth research efforts, the epigenetic mechanisms in IPF pathogenesis have been further discovered and concerned. As a widely studied mechanism of epigenetic modification, DNA methylation is primarily facilitated by DNA methyltransferases (DNMTs), resulting in the addition of a methyl group to the fifth carbon position of the cytosine base, leading to the formation of 5-methylcytosine (5-mC). Dysregulation of DNA methylation is intricately associated with the advancement of respiratory disorders. Recently, the role of DNA methylation in IPF pathogenesis has also received considerable attention. DNA methylation patterns include methylation modification and demethylation modification and regulate a range of essential biological functions through gene expression regulation. The Ten-Eleven-Translocation (TET) family of DNA dioxygenases is crucial in facilitating active DNA demethylation through the enzymatic conversion of the modified genomic base 5-mC to 5-hydroxymethylcytosine (5-hmC). TET2, a member of TET proteins, is involved in lung inflammation, and its protein expression is downregulated in the lungs and alveolar epithelial type II cells of IPF patients. This review summarizes the current knowledge of pathologic features and DNA methylation mechanisms of pulmonary fibrosis, focusing on the critical roles of abnormal DNA methylation patterns, DNMTs, and TET proteins in impacting IPF pathogenesis. Researching DNA methylation will enchance comprehension of the fundamental mechanisms involved in IPF pathology and provide novel diagnostic biomarkers and therapeutic targets for pulmonary fibrosis based on the studies involving epigenetic mechanisms.

Unraveling FOXO3a and USP18 Functions in Idiopathic Pulmonary Fibrosis through Single-Cell RNA Sequencing of Mouse and Human Lungs.

Background Idiopathic pulmonary fibrosis (IPF) is identified as a chronic, progressive lung disease, predominantly marked by enhanced fibroblast proliferation and excessive deposition of extracellular matrix. The intricate interactions between diverse molecular pathways in fibroblasts play a crucial role in driving the pathogenesis of IPF. Methods This research is focused on elucidating the roles of FOXO3a, a transcription factor, and USP18, a ubiquitin-specific protease, in modulating fibroblast functionality in the context of IPF. FOXO3a is well-known for its regulatory effects on cellular responses, including apoptosis and oxidative stress, while USP18 is generally associated with protein deubiquitination. Results Our findings highlight that FOXO3a acts as a critical regulator in controlling fibroblast activation and differentiation, illustrating its vital role in the pathology of IPF. Conversely, USP18 seems to promote fibroblast proliferation and imparts resistance to apoptosis, thereby contributing to the exacerbation of fibrotic processes. The synergistic dysregulation of both FOXO3a and USP18 in fibroblasts was found to significantly contribute to the fibrotic alterations characteristic of IPF. Conclusion Deciphering the complex molecular interactions between FOXO3a and USP18 in fibroblasts provides a deeper understanding of IPF pathogenesis and unveils novel therapeutic avenues, offering a promising potential for not just halting but potentially reversing the progression of this debilitating disease.

Adoptive Transfer of IL-33-Stimulated Macrophages into Bleomycin-Induced Mouse Models to Study Their Effect on Idiopathic Pulmonary Fibrosis In Vivo.

The inflammatory response caused by early lung injury is one of the important causes of the development of idiopathic pulmonary fibrosis (IPF), which is accompanied by the activation of inflammatory cells such as macrophages and neutrophils, as well as the release of inflammatory factors including TNF-α, IL-1β, and IL-6. Early inflammation caused by activated pulmonary interstitial macrophages (IMs) in response to IL-33 stimulation is known to play a vital role in the pathological process of IPF. This protocol describes the adoptive transfer of IMs stimulated by IL-33 into the lungs of mice to study IPF development. It involves the isolation and culture of primary IMs from host mouse lungs, followed by the adoptive transfer of stimulated IMs into the alveoli of bleomycin (BLM)-induced IPF recipient mice (which have been previously depleted of alveolar macrophages by treatment with clodronate liposomes), and the pathological evaluation of those mice. The representative results show that the adoptive transfer of IL-33-stimulated macrophages aggravates pulmonary fibrosis in mice, suggesting that the establishment of the macrophage adoptive transfer experiment is a good technical means to study IPF pathology.

Differences in Treatment Response in Bronchial Epithelial Cells from Idiopathic Pulmonary Fibrosis (IPF) Patients: A First Step towards Personalized Medicine?

Idiopathic pulmonary fibrosis (IPF) has a detrimental prognosis despite antifibrotic therapies to which individual responses vary. IPF pathology is associated with oxidative stress, inflammation and increased activation of SRC family kinases (SFK). This pilot study evaluates individual responses to pirfenidone, nintedanib and SFK inhibitor saracatinib, markers of redox homeostasis, fibrosis and inflammation, in IPF-derived human bronchial epithelial (HBE) cells. Differentiated HBE cells from patients with and without IPF were analyzed for potential alterations in redox and profibrotic genes and pro-inflammatory cytokine secretion. Additionally, the effects of pirfenidone, nintedanib and saracatinib on these markers were determined. HBE cells were differentiated into a bronchial epithelium containing ciliated epithelial, basal, goblet and club cells. NOX4 expression was increased in IPF-derived HBE cells but differed on an individual level. In patients with higher NOX4 expression, pirfenidone induced antioxidant gene expression. All drugs significantly decreased NOX4 expression. IL-6 (p = 0.09) and IL-8 secretion (p = 0.014) were increased in IPF-derived HBE cells and significantly reduced by saracatinib. Finally, saracatinib significantly decreased TGF-β gene expression. Our results indicate that treatment responsiveness varies between IPF patients in relation to their oxidative and inflammatory status. Interestingly, saracatinib tends to be more effective in IPF than standard antifibrotic drugs.

USP13 Deficiency Impairs Autophagy and Facilitates Age-related Lung Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is an age-related disease. Failure of the proteostasis network with age, including insufficient autophagy, contributes to the pathology of IPF. Mechanisms underlying autophagy disruption in IPF are unclear and may involve regulation of USP (ubiquitin-specific protease) by post-translational modifications. To expand our previous observation of low USP13 expression in IPF, this study evaluated the role of USP13 in age-related lung fibrosis. Here, we demonstrated that Usp13-deficient aged mice exhibited impaired autophagic activity and increased vulnerability to bleomycin-induced fibrosis. Mechanistically, USP13 interacted with and deubiquitinated Beclin 1, and Beclin 1 overexpression abolished the effects of USP13 disruption. In addition, Beclin 1 inhibition resulted in insufficient autophagy and more severe lung fibrosis after bleomycin injury, consistent with the phenotype of aged Usp13-deficient mice. Collectively, we show a protective role of USP13 in age-related pulmonary fibrosis. Aging-mediated USP13 loss impairs autophagic activity and facilitates lung fibrosis through Beclin 1 deubiquitination. Our findings support the notion that age-dependent dysregulation of autophagic regulators enhances vulnerability to lung fibrosis.

Integrated analysis reveals the protective mechanism and therapeutic potential of hyperbaric oxygen against pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a dreadful, chronic, and irreversibly progressive disease leading to death with a few effective treatments. Our previous study suggested that repetitive hyperbaric oxygen (HBO) treatment alleviates bleomycin-induced pulmonary fibrosis in mice. Here, we investigated the protective mechanism of HBO treatment against pulmonary fibrosis using an integrated approach. Analyzing publicly available expression data from the mouse model of bleomycin-induced pulmonary fibrosis as well as IPF patients, several potential mechanisms of relevance to IPF pathology were identified, including increased epithelial-to-mesenchymal transition (EMT) and glycolysis. High EMT or glycolysis scores in bronchoalveolar lavage were strong independent predictors of mortality in multivariate analysis. These processes were potentially driven by hypoxia and blocked by HBO treatment. Together, these data support HBO treatment as a viable strategy against pulmonary fibrosis.

Lysophosphatidic acid, ceramide 1-phosphate and sphingosine 1-phosphate in peripheral blood of patients with idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonias. Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are signaling lipids that evoke growth factor-like responses to many cells. Recent studies revealed the involvement of LPA and S1P in the pathology of IPF. In this study, we determined LPA, S1P and ceramide 1-phosphate (C1P) in peripheral blood plasma of IPF patients, and examined correlation to the vital capacity of lung (VC), an indicator of development of fibrosis. Blood plasma samples were taken from eleven patients with IPF and seven healthy volunteers. The lipids of the sample were extracted and subjected to liquid chromatography-tandem mass spectrometry for analysis. Results showed that there is a significant negative correlation between VC and plasma LPA levels, indicating that IPF patients with advanced fibrosis had higher concentration of LPA in their plasma. Average of S1P levels were significantly higher in IPF patients than those in healthy subjects. Although it is not statistically significant, a similar correlation trend that observed in LPA levels also found between VC and S1P levels. These results indicated that plasma LPA and S1P may be associated with deterioration of pulmonary function of IPF patients. J. Med. Invest. 69 : 196-203, August, 2022.

Inhibition of PDIA3 in club cells attenuates osteopontin production and lung fibrosis

BackgroundThe role of club cells in the pathology of idiopathic pulmonary fibrosis (IPF) is not well understood. Protein disulfide isomerase A3 (PDIA3), an endoplasmic reticulum-based redox chaperone required for the...

The transition from normal lung anatomy to minimal and established fibrosis in idiopathic pulmonary fibrosis (IPF)

BackgroundThe transition from normal lung anatomy to minimal and established fibrosis is an important feature of the pathology of idiopathic pulmonary fibrosis (IPF). The purpose of this report is to examine the molecular and cellular mechanisms associated with this transition. MethodsPre-operative thoracic Multidetector Computed Tomography (MDCT) scans of patients with severe IPF (n = 9) were used to identify regions of minimal(n = 27) and established fibrosis(n = 27). MDCT, Micro-CT, quantitative histology, and next-generation sequencing were used to compare 24 samples from donor controls (n = 4) to minimal and established fibrosis samples. FindingsThe present results extended earlier reports about the transition from normal lung anatomy to minimal and established fibrosis by showing that there are activations of TGFBI, T cell co-stimulatory genes, and the down-regulation of inhibitory immune-checkpoint genes compared to controls. The expression patterns of these genes indicated activation of a field immune response, which is further supported by the increased infiltration of inflammatory immune cells dominated by lymphocytes that are capable of forming lymphoid follicles. Moreover, fibrosis pathways, mucin secretion, surfactant, TLRs, and cytokine storm-related genes also participate in the transitions from normal lung anatomy to minimal and established fibrosis. InterpretationThe transition from normal lung anatomy to minimal and established fibrosis is associated with genes that are involved in the tissue repair processes, the activation of immune responses as well as the increased infiltration of CD4, CD8, B cell lymphocytes, and macrophages. These molecular and cellular events correlate with the development of structural abnormality of IPF and probably contribute to its pathogenesis.

Lung organoids and other preclinical models of pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive fatal disease affecting over 100 000 people in Europe with an increasing incidence. Available treatments offer only slowing of disease progression and are poorly tolerated by patients leading to cessation of therapy. Lung transplant remains the only cure. Therefore, alternative treatments are urgently required. The pathology of IPF is complex and poorly understood and thus creates a major obstacle to the discovery of novel treatments. Additionally, preclinical assessment of new treatments currently relies upon animal models where disparities with human lung biology often hamper drug development. At a cellular level, IPF is characterized by persistent and abnormal deposition of extracellular matrix by fibroblasts and alveolar epithelial cell injury which is seen as a key event in initiation of disease progression. In-depth investigation of the role of alveolar epithelial cells in health and disease has been impeded due to difficulties in primary cell isolation and culture ex vivo. Novel strategies employing patient-derived induced pluripotent stem cells engineered to produce type 2 alveolar epithelial cells (iAEC2) cultured as three-dimensional organoids have the potential to overcome these hurdles and inform new effective precision treatments for IPF leading to improved survival and quality of life for patients worldwide.

Pathology of Idiopathic Pulmonary Fibrosis Assessed by a Combination of Microcomputed Tomography, Histology, and Immunohistochemistry

Idiopathic pulmonary fibrosis (IPF) is a fibrotic disease with the histology of usual interstitial pneumonia (UIP). Although the pathologist's visual inspection is central in histologic assessments, three-dimensional microcomputed tomography (microCT) assessment may complement the pathologist's scoring. We examined associations between the histopathologic features of UIP and IPF in explanted lungs and quantitative microCT measurements, including alveolar surface density, total lung volume taken up by tissue (%), and terminal bronchiolar number. Sixty frozen samples from 10 air-inflated explanted lungs with severe IPF and 36 samples from 6 donor control lungs were scanned with microCT and processed for histologic analysis. An experienced pathologist scored three major UIP criteria (patchy fibrosis, honeycomb, and fibroblastic foci), five additional pathologic changes, and immunohistochemical staining for CD68-, CD4-, CD8-, and CD79a-positive cells, graded on a 0 to 3+ scale. The alveolar surface density and terminal bronchiolar number decreased and the tissue percentage increased in lungs with IPF compared with controls. In lungs with IPF, lower alveolar surface density and higher tissue percentage were correlated with greater scores of patchy fibrosis, fibroblastic foci, honeycomb, CD79a-positive cells, and lymphoid follicles. A decreased number of terminal bronchioles was correlated with honeycomb score but not with the other scores. The three-dimensional microCT measurements reflect the pathological UIP and IPF criteria and suggest that the reduction in the terminal bronchioles may be associated with honeycomb cyst formation.

Klotho antagonizes pulmonary fibrosis through suppressing pulmonary fibroblasts activation, migration, and extracellular matrix production: a therapeutic implication for idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) has been widely accepted as an aging-related fatal lung disease with a therapeutic impasse, largely a consequence of the complex and polygenic gene architecture underlying the molecular pathology of IPF. Here, by conducting an integrative network analysis on the largest IPF case-control RNA-seq dataset to date, we attributed the systems-level alteration in IPF to disruptions in a handful of biological processes including cell migration, transforming growth factor-β (TGF-β) signaling and extracellular matrix (ECM), and identified klotho (KL), a typical anti-aging molecule, as a potential master regulator of those disease-relevant processes. Following experiments showed reduced Kl in isolated pulmonary fibroblasts from bleomycin-exposed mice, and demonstrated that recombinant KL effectively mitigated pulmonary fibrosis in an ex vivo model and alleviated TGF-β-induced pulmonary fibroblasts activation, migration, and ECM production in vitro, which was partially ascribed to FOXF1 and CAV1, two highly co-expressed genes of KL in the IPF. Overall, KL appears to be a vital regulator during pulmonary fibrosis. Given that administration of exogenous KL is a feasible treatment strategy, our work highlighted a promising target gene that could be easily manipulated, leaving the field well placed to further explore the therapeutic potential of KL for IPF.

Ferric chloride induces irreversible pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is a fatal respiratory disease with an unknown cause and poor prognosis. To precisely know the pathophysiology of lung fibrotic disease, the appropriate animal model correlating to the pathology of IPF is required. Its establishment may contribute to develop a new strategy for the treatment of patients with IPF. From the transcriptome analysis using lung myofibroblasts derived from the patient with IPF, we found the possible correlation between ferroptosis and lung fibrosis. Then, to investigate whether the intracellular overload of ferrous ion in the lung parenchyma induces fibrotic formation, we subpleurally injected ferric chloride solution into the central part of left upper lobe. Within 1 h post-injection, the intracellular elevation of ferrous ion and ROS was detected by berlin blue and dihydrorhodamine, respectively. At 10 days post-injury, diffuse and severe fibrosis occurred in the whole lung lobe, which was well associated with an excessive collagen deposition, an increase in expression of myofibroblast markers and a decrease in static lung compliance. Likewise, the DNA array/gene set enrichment analysis clearly showed the accumulation of extracellular matrix including collagen in the ferric chloride-injured lung. In our model, it is noteworthy that a prominent hyperplasia of type2 alveolar epithelial cells was observed around the fibrotic lesion and that progressive and irreversible fibrogenesis was verified by a follow-up survey at least for 6 weeks. These features correlate to the pathology of IPF but are not observed in other existing mouse models. In conclusion, we established a new reliable lung fibrosis model.

Discovery of 4-Methylquinazoline Based PI3K Inhibitors for the Potential Treatment of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease, and its molecular pathogenesis remains poorly understood. Recently, emerging evidence demonstrates that the PI3K signaling transduction pathway is linked to the pathology of IPF. In this work, we rationally designed a new series of 4-methylquinazoline derivatives as highly potent PI3K inhibitors that significantly suppress the phosphorylation of the main PI3K downstream effectors and displays marked antiproliferative activity in mouse MLg2908 lung fibroblasts. In a bleomycin-induced mouse pulmonary fibrosis model, 5d from the series improved mouse lung function and slowed the progression of pulmonary fibrosis. Overall, this work promises a therapeutic potential for PI3K inhibitors to treat IPF.

Intrapulmonary Autoantibodies to HSP72 Are Associated with Improved Outcomes in IPF.

Rationale Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic interstitial lung disease, with high mortality. Currently, the aetiology and the pathology of IPF are poorly understood, with both innate and adaptive responses previously being implicated in the disease pathogenesis. Heat shock proteins (Hsp) and antibodies to Hsp in patients with IPF have been suggested as therapeutic targets and prognostic biomarkers, respectively. We aimed to study the relationship between the expression of Hsp72 and anti-Hsp72 antibodies in the BAL fluid and serum Aw disease progression in patients with IPF. Methods A novel indirect ELISA to measure anti-Hsp72 IgG was developed and together with commercially available ELISAs used to detect Hsp72 IgG, Hsp72 IgGAM, and Hsp72 antigen, in the serum and BALf of a cohort of IPF (n = 107) and other interstitial lung disease (ILD) patients (n = 66). Immunohistochemistry was used to detect Hsp72 in lung tissue. The cytokine expression from monocyte-derived macrophages was measured by ELISA. Results Anti-Hsp72 IgG was detectable in the serum and BALf of IPF (n = 107) and other ILDs (n = 66). Total immunoglobulin concentrations in the BALf showed an excessive adaptive response in IPF compared to other ILDs and healthy controls (p = 0.026). Immunohistochemistry detection of C4d and Hsp72 showed that these antibodies may be targeting high expressing Hsp72 type II alveolar epithelial cells. However, detection of anti-Hsp72 antibodies in the BALf revealed that increasing concentrations were associated with improved patient survival (adjusted HR 0.62, 95% CI 0.45-0.85; p = 0.003). In vitro experiments demonstrate that anti-Hsp72 complexes stimulate macrophages to secrete CXCL8 and CCL18. Conclusion Our results indicate that intrapulmonary anti-Hsp72 antibodies are associated with improved outcomes in IPF. These may represent natural autoantibodies, and anti-Hsp72 IgM and IgA may provide a beneficial role in disease pathogenesis, though the mechanism of action for this has yet to be determined.

Redox Imbalance in Idiopathic Pulmonary Fibrosis: A Role for Oxidant Cross-Talk Between NADPH Oxidase Enzymes and Mitochondria.

Significance: Idiopathic pulmonary fibrosis (IPF) is a progressive age-related lung disease with a median survival of only 3 years after diagnosis. The pathogenic mechanisms behind IPF are not clearly understood, and current therapeutic approaches have not been successful in improving disease outcomes. Recent Advances: IPF is characterized by increased production of reactive oxygen species (ROS), primarily by NADPH oxidases (NOXes) and mitochondria, as well as altered antioxidant defenses. Recent studies have identified the NOX isoform NOX4 as a key player in various important aspects of IPF pathology. In addition, mitochondrial dysfunction is thought to enhance pathological features of IPF, in part by increasing mitochondrial ROS (mtROS) production and altering cellular metabolism. Recent findings indicate reciprocal interactions between NOX enzymes and mitochondria, which affect regulation of NOX activity as well as mitochondrial function and mtROS production, and collectively promote epithelial injury and profibrotic signaling. Critical Issues and Future Directions: The precise molecular mechanisms by which ROS from NOX or mitochondria contribute to IPF pathology are not known. This review summarizes the current knowledge with respect to the various aspects of ROS imbalance in the context of IPF and its proposed roles in disease development, with specific emphasis on the importance of inappropriate NOX activation, mitochondrial dysfunction, and the emerging evidence of NOX-mitochondria cross-talk as important drivers in IPF pathobiology.

Impact of ergothioneine on idiopathic pulmonary fibrosis markers in human lung epithelial cells in vitro

The pathology of idiopathic pulmonary fibrosis (IPF) remains unknown. Tobacco smoking is a risk factor for IPF and tobacco smoke‐induced oxidative stress can initiate/worsen epithelial‐mesenchymal transition (EMT) in pulmonary epithelial cells, leading to IPF. Ergothioneine (ET) is an antioxidant amino acid available exclusively from the diet. ET requires its physiological transporter OCTN1 (SLC22A4) for cellular uptake and accumulation. Genetic variants of SLC22A4 have been associated with inflammatory bowel diseases and COPD, diseases with fibrotic phenotype. In this study, we tested the hypothesis that ET protects lung epithelial cells in vitro from factors implicated with EMT.NCl‐H441 and A549 cells were cultured in RPMI‐1640 medium supplemented with 5% FBS and 1% sodium pyruvate, at 37°C and in 5% CO2 atmosphere. In some experiments, the medium was supplemented with 250 or 500 μM ET. To assess the impact of tobacco smoke, cells were cultured in the presence of 5 or 10% cigarette smoke extract (CSE) for 24h. CSE was generated by bubbling one Kentucky 3R4F research cigarette through 10ml of medium. The CSE was filtered and diluted before use. To initiate EMT, cells were exposed to 5ng/mL TGF‐β1 in serum‐free medium for 3 days in the respective experiments.Cell proliferation was determined by CyQUANT® NF assay. Cell shape investigation was performed by phase‐contrast microscopy and ImageJ software. A scratch wound assay was carried out to measure wound closure. Before the assay, cells were subjected to serum‐deprivation for 24h. Monolayers were wounded with a pipette tip, followed by 1‐day of serum‐free culture. The wound area was measured by phase‐contrast microscopy using the Cell^A software.The cell proliferation assay showed that CSE‐attenuated cell proliferation rate was significantly reduced by ET in NCl‐H441 cells. However, in A549 cells, their rapid proliferation rate might have compromised the sensitivity of the assay. In A549 cells, decreased circularity and increased aspect ratio were measured after TGF‐β1 treatment. These effects were significantly reduced when cultured in the presence of ET. In the scratch assay, increased cell migration was observed in CSE‐treated NCl‐H441 cells, but the effect was diminished after ET treatment. These data suggest that ET not only protects lung epithelial cells from CSE‐induced cell death, but also prevent CSE‐induced cell migration, thereby ameliorating EMT. Of note, in NCl‐H441 cells, TGF‐β1 failed to establish signs of EMT.Future research will investigate the effect of ET on molecular markers of EMT such as α‐SMA, vimentin and collagen.Support or Funding InformationThis work has been financially supported by a Clinical Investigator Award from the Flight Attendant Medical Research Institute (FAMRI CIA 130016). M.A.S. is the recipient of a PhD bursary from the Iraqi Ministry of Higher Education and Scientific Research (MOHESR). A.K. is the recipient of a Laidlaw Undergraduate Research and Leadership Programme.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Interleukin-18 promotes fibroblast senescence in pulmonary fibrosis through down-regulating Klotho expression

Idiopathic pulmonary fibrosis (IPF) is a lethal disease of unknown aetiology that largely presents in the elderly. The mechanisms related to aging such as fibroblast senescence have been strongly implicated in pathology of IPF. We have previously demonstrated the protective effects of IL-18 binding protein (IL-18BP) against bleomycin (BLM)-induced pulmonary fibrosis (PF) via inhibition of epithelial-to-mesenchymal transition. However, the role of IL-18 in fibroblast senescence in PF is still unknown. The aim of this study was to investigate the effects of IL-18 on fibroblast senescence in the development of PF. We found that SA-β-gal positive cells, the proportion of cells in G1 phase, and expressions of p21 and p53 were increased in primary lung fibroblasts isolated from BLM-challenged mice, while the fibroblasts from IL-18BP-treated mice showed decreased senescence propensity. We further demonstrated that IL-18 was sufficient to trigger senescence of primary lung fibroblasts. The senescence-associated secretory phenotype (SASP) of fibroblasts treated with IL-18 robustly stimulated a fibrotic phenotype in pulmonary fibroblasts. Moreover, the expression of Klotho, an anti-senescence protein, was down-regulated after IL-18 treatment in primary lung fibroblasts. Overexpression of Klotho reversed the senescence and SASP induced by IL-18 in lung fibroblasts. In summary, we reported for the first time that IL-18 promoted the lung fibroblast senescence and SASP in PF through blocking Klotho pathway. Neutralize IL-18 by IL-18BP exhibited antifibrotic effects partly by suppressing lung fibroblast senescence in PF. It contributes to the growing evidence that IL-18 could be a therapeutic target for PF.

Fibroblast senescence in the pathology of idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing interstitial pneumonia of unknown cause with a median survival of only three years. Little is known about the mechanisms that precede the excessive collagen deposition seen in IPF, but cellular senescence has been strongly implicated in disease pathology. Senescence is a state of irreversible cell-cycle arrest accompanied by an abnormal secretory profile and is thought to play a critical role in both development and wound repair. Normally, once a senescent cell has contributed to wound repair, it is promptly removed from the environment via infiltrating immune cells. However, if immune clearance fails, the persistence of senescent cells is thought to drive disease pathology through their altered secretory profile. One of the major cell types involved in wound healing is fibroblasts, and senescent fibroblasts have been identified in the lungs of patients with IPF and in fibroblast cultures from IPF lungs. The question of what is driving abnormally high numbers of fibroblasts into senescence remains unanswered. The transcription factor signal transducer and activator of transcription 3 (STAT3) plays a role in a myriad of processes, including cell-cycle progression, gene transcription, as well as mitochondrial respiration, all of which are dysregulated during senescence. Activation of STAT3 has previously been shown to correlate with IPF progression and therefore is a potential molecular target to modify early-stage senescence and restore normal fibroblast function. This review summarizes what is presently known about fibroblast senescence in IPF and how STAT3 may contribute to this phenotype.