Including Idiopathic Pulmonary Fibrosis Research Articles

Epigenetic regulation of IPF fibroblast phenotype by glutaminolysis

ObjectiveExcessive extra-cellular-matrix production and uncontrolled proliferation of the fibroblasts are characteristics of many fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). The fibroblasts have enhanced glutaminolysis with up-regulated glutaminase, GLS1, which converts glutamine to glutamate. Here, we investigated the role of glutaminolysis and glutaminolysis-derived metabolite α-ketoglutarate (α-KG) on IPF fibroblast phenotype and gene expression. MethodsReduced glutamine conditions were carried out either using glutamine-free culture medium or silencing the expression of GLS1 with siRNA, with or without α-KG compensation. Cell phenotype has been characterized under these different conditions, and gene expression profile was examined by RNA-Seq. Specific profibrotic genes (Col3A1 and PLK1) expression were examined by real-time PCR and western blots. The levels of repressive histone H3K27me3, which demethylase activity is affected by glutaminolysis, were examined and H3K27me3 association with promoter region of Col3A1 and PLK1 were checked by ChIP assays. Effects of reduced glutaminolysis on fibrosis markers were checked in an animal model of lung fibrosis. ResultsThe lack of glutamine in the culture medium alters the profibrotic phenotype of activated fibroblasts. The addition of exogenous and glutaminolysis-derived metabolite α-KG to glutamine-free media barely restores the pro-fibrotic phenotype of activated fibroblasts. Many genes are down-regulated in glutamine-free medium, α-KG supplementation only rescues a limited number of genes. As α-KG is a cofactor for histone demethylases of H3K27me3, the reduced glutaminolysis alters H3K27me3 levels, and enriches H3K27me3 association with Col3A1 and PLK1 promoter region. Adding α-KG in glutamine-free medium depleted H3K27me3 association with Col3A1 promoter region but not that of PLK1. In a murine model of lung fibrosis, mice with reduced glutaminolysis showed markedly reduced fibrotic markers. ConclusionsThis study indicates that glutamine is critical for supporting pro-fibrotic fibroblast phenotype in lung fibrosis, partially through α-KG-dependent and –independent mechanisms, and supports targeting fibroblast metabolism as a therapeutic method for fibrotic diseases.

S-Glutathionylation-Controlled Apoptosis of Lung Epithelial Cells; Potential Implications for Lung Fibrosis.

Glutathione (GSH), a major antioxidant in mammalian cells, regulates several vital cellular processes, such as nutrient metabolism, protein synthesis, and immune responses. In addition to its role in antioxidant defense, GSH controls biological processes through its conjugation to reactive protein cysteines in a post-translational modification known as protein S-glutathionylation (PSSG). PSSG has recently been implicated in the pathogenesis of multiple diseases including idiopathic pulmonary fibrosis (IPF). Hallmarks of IPF include repeated injury to the alveolar epithelium with aberrant tissue repair, epithelial cell apoptosis and fibroblast resistance to apoptosis, and the accumulation of extracellular matrix and distortion of normal lung architecture. Several studies have linked oxidative stress and PSSG to the development and progression of IPF. Additionally, it has been suggested that the loss of epithelial cell homeostasis and increased apoptosis, accompanied by the release of various metabolites, creates a vicious cycle that aggravates disease progression. In this short review, we highlight some recent studies that link PSSG to epithelial cell apoptosis and highlight the potential implication of metabolites secreted by apoptotic cells.

The Association between Idiopathic Pulmonary Fibrosis and Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis.

The prevalence of obstructive sleep apnea (OSA) has greatly increased in recent years. Recent data suggest that severe and moderate forms of OSA affect between 6 and 17% of adults in the general population. Many papers are reporting the significantly increased prevalence of OSA in patients suffering from fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). Therefore, we performed a systematic review and meta-analysis regarding the dependency between IPF and OSA. Due to the lack of papers focusing on IPF among OSA patients, we focused on the prevalence of OSA among IPF patients. In the search strategy, a total of 684 abstracts were identified, 496 after the removal of duplicates. After the screening of titles and abstracts, 31 studies were qualified for further full-text analysis for eligibility criteria. The final analysis was performed on 614 IPF patients from 18 studies, which met inclusion criteria. There were 469 (76.38%) IPF patients with OSA and 145 (23.62%) without. The mean age varied from 60.9 ± 8.1 up to 70.3 ± 7.9. The obtained prevalence was 76.4 (95% CI: 72.9–79.7) and 75.7 (95% CI: 70.1–80.9) for fixed and random effects, respectively. The median prevalence of OSA among non-IPF patients for all the ethnics groups included in this study was 16,4% (IQR: 3.4%–26.8%). The study provides strong evidence for the increased prevalence of OSA in IPF patients when comparing with the general OSA prevalence.

HER2 drives lung fibrosis by activating a metastatic cancer signature in invasive lung fibroblasts.

Progressive tissue fibrosis, including idiopathic pulmonary fibrosis (IPF), is characterized by excessive recruitment of fibroblasts to sites of tissue injury and unremitting extracellular matrix deposition associated with severe morbidity and mortality. However, the molecular mechanisms that control progressive IPF have yet to be fully determined. Previous studies suggested that invasive fibroblasts drive disease progression in IPF. Here, we report profiling of invasive and noninvasive fibroblasts from IPF patients and healthy donors. Pathway analysis revealed that the activated signatures of the invasive fibroblasts, the top of which was ERBB2 (HER2), showed great similarities to those of metastatic lung adenocarcinoma cancer cells. Activation of HER2 in normal lung fibroblasts led to a more invasive genetic program and worsened fibroblast invasion and lung fibrosis, while antagonizing HER2 signaling blunted fibroblast invasion and ameliorated lung fibrosis. These findings suggest that HER2 signaling may be a key driver of fibroblast invasion and serve as an attractive target for therapeutic intervention in IPF.

Mitochondrial uncoupling protein-2 reprograms metabolism to induce oxidative stress and myofibroblast senescence in age-associated lung fibrosis.

Mitochondrial dysfunction has been associated with age‐related diseases, including idiopathic pulmonary fibrosis (IPF). We provide evidence that implicates chronic elevation of the mitochondrial anion carrier protein, uncoupling protein‐2 (UCP2), in increased generation of reactive oxygen species, altered redox state and cellular bioenergetics, impaired fatty acid oxidation, and induction of myofibroblast senescence. This pro‐oxidant senescence reprogramming occurs in concert with conventional actions of UCP2 as an uncoupler of oxidative phosphorylation with dissipation of the mitochondrial membrane potential. UCP2 is highly expressed in human IPF lung myofibroblasts and in aged fibroblasts. In an aging murine model of lung fibrosis, the in vivo silencing of UCP2 induces fibrosis regression. These studies indicate a pro‐fibrotic function of UCP2 in chronic lung disease and support its therapeutic targeting in age‐related diseases associated with impaired tissue regeneration and organ fibrosis.

Association of the RAGE/RAGE-ligand axis with interstitial lung disease and its acute exacerbation.

The receptor for advanced glycation end product (RAGE) is a transmembrane receptor highly expressed in type 1 pneumocytes of healthy lungs. RAGE is considered to play a homeostatic role in the lung, as RAGE knockout mice develop lung fibrosis as they age. In contrast, RAGE can bind numerous ligands, including high-mobility group box 1 (HMGB1). These interactions initiate pro-inflammatory signaling associated with the pathogenesis of lung injury and interstitial lung disease (ILD), including idiopathic pulmonary fibrosis (IPF). ILD is a broad category of diffuse parenchymal lung disease characterized by various extents of lung fibrosis and inflammation, and IPF is a common and progressive ILD of unknown cause. The prognosis of patients with IPF is poor, and acute exacerbation of IPF (AE-IPF) is one of the main causes of death. Recent reports indicate that acute exacerbations can occur in other ILDs (AE-ILD). Notably, ILD is frequently observed in patients with lung cancer, and AE-ILD after surgical procedures or the initiation of chemotherapy for concomitant lung cancer are clinically important due to their association with increased mortality. In this review, we summarize the associations of RAGE/soluble RAGE (sRAGE)/RAGE ligands with the pathogenesis and clinical course of ILD, including IPF and AE-IPF. Additionally, the potential use of sRAGE and RAGE ligands as predictive markers of AE-IPF and cancer treatment-triggered AE-ILD is also discussed.

Cellular Senescence as Fibrogenic Mechanism in Smoking Lung

Age is a risk factor for many diseases including idiopathic pulmonary fibrosis (IPF) by affecting wound healing through abnormal fibrogenesis. Common cellular and molecular traits associated with aging can be found in senescent cells, which may occur throughout the lifespan playing physiological roles during normal development or limiting the proliferation of damaged and aged cells. In this study we investigated in smoking mice whether the senescence of lung cells, triggered by the oxidative stress response, is associated with molecular pathways that can influence lung fibrogenesis and contribute to the remodeling of the fibrotic tissue characterizing some phenotypes of COPD in humans. Among the complex mixture of hundreds senescence secreted factors that include proinflammatory cytokines, chemokines, growth factors, and proteases, we selected important factors involved in differentiation of myofibroblasts, their dedifferentiation and apoptosis, as well as in their metabolic function.The expression of these factors and the amount of matrix deposition was analyzed after chronic cigarette smoke (CS) exposure of C57 Bl/6 and DBA/2 mice sensitive to oxidative, in different lung compartmentscharacterized by a fibrotic remodeling using histochemistry or immunohistochemistry.Unlike C57 Bl/6, DBA/2 mice at 4 months of exposure show marked positivity for 8‐OHdG, a marker of oxidative damage, in subpleural areas, in central parts of the lung parenchyma, on airways and on cells of the fibro‐muscular layer.In these areas, a marked positivity is observed for fibrogenic cytokines such as TGF‐β, PDGF‐b and CTGF, and for other factors such as the p16ink4A senescence marker, and proliferation markers PCNA and Ki67. In DBA/2 mice, these compartments are characterized by a progressive fibrous remodeling at various experimental time points from 5 months of CS exposure onwards as demonstrated by Masson’s trichrome staining.Fibroproliferative foci are present in sub‐pleural areas, in peripheral areas of airways, and in central parts of the lung parenchyma. They are characterized by increasing number of α‐SMA positive myofibroblasts, which express the senescence marker p16ink4A and the transcription factor MyoD that plays a crucial role in myoblast proliferation and differentiation. MyoD induces cell cycle arrest, promotes cellular terminal differentiation of fibroblasts into myofibroblasts, and in senescent myofibroblasts it has been reported to determine resistance to apoptosis and opposes their dedifferentiation.All these factors contribute to the development in smoking DBA/2 mice of lung lesions, which are like those seen in patients with “Combined Fibrosis/Emphysema Syndrome.”Despite consistent levels of TGF‐β, PDGF‐b and CTGF, C57 Bl/6 mice develop after chronic CS exposure fibrotic remodeling at lower extent. Of interest, a very low expression of factors indicative of senescence (p16ink4A and MyoD) and cell proliferation (PCNA and Ki67) is observed.Our results suggest that apoptosis, senescence, and proliferation induced at different rate by fibrotic cytokines and senescence associated secretory factors play important role in early or late appearance of fibrotic remodeling of lung and airways exposed to CS.

115: THE PULMONARY SEQUELAE OF GASTRO-OESOPHAGEAL REFLUX DISEASE

Abstract Background and aim Gastro-oesophageal reflux disease (GORD) and a spectrum of pulmonary diseases, including idiopathic pulmonary fibrosis (IPF) and bronchiectasis have a complex but poorly understood relationship. IPF is characterised by chronic progressive interstitial pneumonia due to the deposition of fibrous tissue in the pulmonary interstitium. It has a median survival time from diagnosis of 2 to 5 years. Bronchiectasis is defined as irreversible dilatation of the bronchial tree, leading to severe pulmonary infections and gradual deterioration in lung function. Chronic micro aspiration of acid and non-acid refluxate leading to airway irritation, repeated lung injury and respiratory tree remodelling has been implicated in the pathophysiology and progression of both diseases. Current studies have shown that patients with severe GORD will demonstrate pulmonary aspiration of refluxate on scintigraphic scanning. We aim to demonstrate the presence of pulmonary aspiration of refluxate on oesophageal scintigraphy and correlate this with changes of fibrosis, scarring, bronchiectatic and ground glass changes on high resolution computed tomography (HRCT) chest imaging. Methods Retrospective data was obtained from 114 patients who underwent oesophageal scintigraphy reflux studies at a single nuclear medicine imaging facility to evaluate for significant GORD or extra-oesophageal symptoms. Scintigraphy results were then compared with HRCT chest studies of the respective patients. Lobar locations of parenchymal changes on CT were correlated with location of isotope in lungs seen during aspiration on scintigraphy. Results 114 of patients demonstrated evidence of pulmonary aspiration on scintigraphy in the delayed study. All patients had intermittent or continuous full column gastro-oesophageal reflux with evidence of tracer in both lungs or the right lung. Of these patients, 35 underwent HRCT chest studies. 23 of the 35 patients had evidence of pulmonary disease on HRCT, demonstrated by fibrosis, scarring, bronchiectatic changes or ground glass opacities. 11 patients showed evidence of pulmonary fibrosis or scarring, and 10 of these demonstrated co-location of pulmonary aspiration on scintigraphy. 10 of 11 patients with bronchiectactic change were co-located with pulmonary aspiration. Conclusion These results demonstrate a likely relationship between GORD, IPF and bronchiectasis, indicating that the current clinical paradigm of GORD and respiratory disease being two separate entities must be re-evaluated.

Identification of a distal RXFP1 gene enhancer with differential activity in fibrotic lung fibroblasts involving AP-1

Relaxin/insulin-like family peptide receptor 1 (RXFP1) mediates relaxin’s antifibrotic effects and has reduced expression in the lung and skin of patients with fibrotic interstitial lung disease (fILD) including idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc). This may explain the failure of relaxin-based anti-fibrotic treatments in SSc, but the regulatory mechanisms controlling RXFP1 expression remain largely unknown. This study aimed to identify regulatory elements of RXFP1 that may function differentially in fibrotic fibroblasts. We identified and evaluated a distal regulatory region of RXFP1 in lung fibroblasts using a luciferase reporter system. Using serial deletions, an enhancer upregulating pGL3-promoter activity was localized to the distal region between -584 to -242bp from the distal transcription start site (TSS). This enhancer exhibited reduced activity in IPF and SSc lung fibroblasts. Bioinformatic analysis identified two clusters of activator protein 1 (AP-1) transcription factor binding sites within the enhancer. Site-directed mutagenesis of the binding sites confirmed that only one cluster reduced activity (-358 to -353 relative to distal TSS). Co-expression of FOS in lung fibroblasts further increased enhancer activity. In vitro complex formation with a labeled probe spanning the functional AP-1 site using nuclear proteins isolated from lung fibroblasts confirmed a specific DNA/protein complex formation. Application of antibodies against JUN and FOS resulted in the complex alteration, while antibodies to JUNB and FOSL1 did not. Analysis of AP-1 binding in 5 pairs of control and IPF lung fibroblasts detected positive binding more frequently in control fibroblasts. Expression of JUN and FOS was reduced and correlated positively with RXFP1 expression in IPF lungs. In conclusion, we identified a distal enhancer of RXFP1 with differential activity in fibrotic lung fibroblasts involving AP-1 transcription factors. Our study provides insight into RXFP1 downregulation in fILD and may support efforts to reevaluate relaxin-based therapeutics alongside upregulation of RXFP1 transcription.

The Hedgehog Signaling Pathway in Idiopathic Pulmonary Fibrosis: Resurrection Time.

The hedgehog (Hh) pathway is a sophisticated conserved cell signaling pathway that plays an essential role in controlling cell specification and proliferation, survival factors, and tissue patterning formation during embryonic development. Hh signal activity does not entirely disappear after development and may be reactivated in adulthood within tissue-injury-associated diseases, including idiopathic pulmonary fibrosis (IPF). The dysregulation of Hh-associated activating transcription factors, genomic abnormalities, and microenvironments is a co-factor that induces the initiation and progression of IPF.

Nutritional assessment in idiopathic pulmonary fibrosis: a prospective multicentre study.

BackgroundNutritional status impacts quality of life and prognosis of patients with respiratory diseases, including idiopathic pulmonary fibrosis (IPF). However, there is a lack of studies performing an extensive nutritional assessment of IPF patients. This study aimed to investigate the nutritional status and to identify nutritional phenotypes in a cohort of IPF patients at diagnosis.MethodsPatients underwent a thorough pulmonary and nutritional evaluation including questionnaires on nutritional status, and physical activity, anthropometry, body impedance, dynamometry, 4-m gait speed and blood tests.Results90 IPF patients (78.9% males, mean age 72.7 years) were enrolled. The majority of patients were classified as Gender-Age-Physiology Index stage 2 (47, 52.2%) with an inactive lifestyle according to International Physical Activity Questionnaire score (39, 43.3%), and had mean forced vital capacity and diffusing capacity for carbon monoxide 86.5% and 54.2%, respectively. In regards to nutritional phenotypes, the majority of patients were normally nourished (67.8%, 95% CI 58.6–77.7%), followed by non-sarcopenic obese (25.3%, 95% CI 16.1–35.2%), sarcopenic (4.6%, 95% CI 0.0–14.5%) and sarcopenic obese (2.3%, 95% CI 0.0–12.2%). Among the normally nourished, 49.2% showed early signs of nutritional and physical performance alterations, including body mass index ≥30 kg·m−2 in 4.3%, history of weight loss ≥5% in 11.9%, and reduction of gait speed and hand grip strength in 11.9% and 35.6%, respectively. Low vitamin D values were observed in 56.3% of cases.ConclusionsIPF patients at diagnosis are mainly normally nourished and obese, but early signs of nutritional and physical performance impairment can already be identified at this stage.

Fibrotic Idiopathic Interstitial Lung Disease: The Molecular and Cellular Key Players.

Interstitial lung diseases (ILDs) that are known as diffuse parenchymal lung diseases (DPLDs) lead to the damage of alveolar epithelium and lung parenchyma, culminating in inflammation and widespread fibrosis. ILDs that account for more than 200 different pathologies can be divided into two groups: ILDs that have a known cause and those where the cause is unknown, classified as idiopathic interstitial pneumonia (IIP). IIPs include idiopathic pulmonary fibrosis (IPF), non-specific interstitial pneumonia (NSIP), cryptogenic organizing pneumonia (COP) known also as bronchiolitis obliterans organizing pneumonia (BOOP), acute interstitial pneumonia (AIP), desquamative interstitial pneumonia (DIP), respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), and lymphocytic interstitial pneumonia (LIP). In this review, our aim is to describe the pathogenic mechanisms that lead to the onset and progression of the different IIPs, starting from IPF as the most studied, in order to find both the common and standalone molecular and cellular key players among them. Finally, a deeper molecular and cellular characterization of different interstitial lung diseases without a known cause would contribute to giving a more accurate diagnosis to the patients, which would translate to a more effective treatment decision.

Patient-specific iPSCs carrying an SFTPC mutation reveal the intrinsic alveolar epithelial dysfunction at the inception of interstitial lung disease.

SUMMARYAlveolar epithelial type 2 cell (AEC2) dysfunction is implicated in the pathogenesis of adult and pediatric interstitial lung disease (ILD), including idiopathic pulmonary fibrosis (IPF); however, identification of disease-initiating mechanisms has been impeded by inability to access primary AEC2s early on. Here, we present a human in vitro model permitting investigation of epithelial-intrinsic events culminating in AEC2 dysfunction, using patient-specific induced pluripotent stem cells (iPSCs) carrying an AEC2-exclusive disease-associated variant (SFTPCI73T). Comparing syngeneic mutant versus gene-corrected iPSCs after differentiation into AEC2s (iAEC2s), we find that mutant iAEC2s accumulate large amounts of misprocessed and mistrafficked pro-SFTPC protein, similar to in vivo changes, resulting in diminished AEC2 progenitor capacity, perturbed proteostasis, altered bioenergetic programs, time-dependent metabolic reprogramming, and nuclear factor κB (NF-κB) pathway activation. Treatment of SFTPCI73T-expressing iAEC2s with hydroxychloroquine, a medication used in pediatric ILD, aggravates the observed perturbations. Thus, iAEC2s provide a patient-specific preclinical platform for modeling the epithelial-intrinsic dysfunction at ILD inception.

Interstitial pneumonia with autoimmune features: from research classification to diagnosis

The term interstitial pneumonia with autoimmune features (IPAF) was first proposed by an international task force in 2015 as a research classification to standardise nomenclature regarding patients with idiopathic interstitial pneumonia and features of connective tissue disease. However, how the use of this term and its proposed definition translates to clinical practice remains uncertain. This review will provide a comprehensive overview of studies of IPAF cohorts to date, discuss the consideration of IPAF as a distinct diagnostic entity and outline a suggested approach to patient management. Considerable heterogeneity exists between published IPAF cohorts, with some cohorts exhibiting similarities to those with connective tissue disease-associated interstitial lung disease (CTD-ILD), and others more similar to idiopathic interstitial pneumonias including idiopathic pulmonary fibrosis (IPF). Little data exist to inform the management of patients who fulfil the IPAF criteria. Preliminary data supports pragmatic management of these patients as having a working clinical diagnosis of either idiopathic interstitial pneumonia or CTD-ILD. Future research studies into this approach are required. The term IPAF, and its definition, have been of fundamental benefit to facilitating research in this diverse patient group. However, to date, there remain many unanswered questions regarding their natural histories and response to treatment.

TGFβ1 induces resistance of human lung myofibroblasts to cell death via down-regulation of TRPA1 channels.

TGFβ1-mediated myofibroblast activation contributes to pathological fibrosis in many diseases including idiopathic pulmonary fibrosis (IPF), where myofibroblast resistance to oxidant-mediated apoptosis is also evident. We therefore investigated the involvement of redox-sensitive TRPA1 ion channels on human lung myofibroblasts (HLMFs) cell death and TGFβ1-mediated pro-fibrotic responses. The effects of TGFβ1 stimulation on TRPA1 expression and cell viability was studied in HLMFs derived from IPF patients and non-fibrotic patients. We also examined a model of TGFβ1-dependent fibrogenesis in human lung. We used qRT-PCR, immunofluorescent assays, overexpression with lentiviral vectors and electrophysiological methods. TRPA1 mRNA, protein and ion currents were expressed in HLMFs derived from both non-fibrotic patient controls and IPF patients, and expression was reduced by TGFβ1. TRPA1 mRNA was also down-regulated by TGFβ1 in a model of lung fibrogenesis in human lung. TRPA1 over-expression or activation induced HLMF apoptosis, and activation of TRPA1 channel activation by H2 O2 induced necrosis. TRPA1 inhibition following TGFβ1 down-regulation or pharmacological inhibition, protected HLMFs from both apoptosis and necrosis. Lentiviral vector mediated TRPA1 expression was also found to induce sensitivity to H2 O2 induced cell death in a TRPA1-negative HEK293T cell line. TGFβ1 induces resistance of HLMFs to TRPA1 agonist- and H2 O2 -mediated cell death via down-regulation of TRPA1 channels. Our data suggest that therapeutic strategies which prevent TGFβ1-dependent down-regulation of TRPA1 may reduce myofibroblast survival in IPF and therefore improve clinical outcomes.

Serum Concentrations of KL-6 in Patients with IPF and Lung Cancer and Serial Measurements of KL-6 in IPF Patients Treated with Antifibrotic Therapy.

Simple SummaryEvaluation of the prognostic significance of serial measurements of serum concentrations of Krebs von den Lungen-6 (KL-6) showed that an annual increment in KL-6 exceeding a threshold amount was an independent risk factor for progressive disease and poor prognosis. No literature data are available on long-term KL-6 measurements in the follow-up of IPF patients treated with Nintedanib. The aim of this study is to serially analyze KL-6 in idiopathic pulmonary fibrosis (IPF) patients after 24 months of Nintedanib and to investigate its biomarker potential in patients with IPF and lung cancer with respect to fibrotic hypersensitivity pneumonitis patients, pulmonary fibrosis associated with autoimmune diseases group and healthy controls.Background: Krebs von den Lungen-6 (KL-6) was suggested as ILD biomarker including idiopathic pulmonary fibrosis (IPF). Lung cancer is one of the most severe comorbidity of IPF patients. This study aims to serially analyze KL-6 in IPF patients after 24 months of Nintedanib and to first investigate the biomarker behavior in IPF associated with adenocarcinoma. Materials and methods: One hundred and forty-two ILD patients (median (IQR), 69 (63–75) years; 86 males) were retrospectively enrolled. Serial serum samples were collected from IPF patients before starting antifibrotic therapy and after 12 months. Serum KL-6 levels were measured by KL-6 reagent assay (Fujirebio Europe, UK). Results: Increased KL-6 concentrations were identified in IPF-LC patients than IPF, fibrotic hypersensitivity pneumonitis, and pulmonary fibrosis associated with autoimmune disease groups. A cut-off value was calculated to distinguish IPF and IPF-LC patients. IPF patients monitored for 24 months with Nintedanib showed persisted increased levels of KL-6 with a progressive decline of FVC percentages. Conclusion: This preliminary study offers a first demonstration that very high serum concentrations of KL-6 in IPF-LC patients are associated with poor prognosis. Moreover, serial evaluation of serum KL-6 in IPF patients over 24 months of Nintedanib treatment revealed that most patients experienced a stabilization of lung function parameters and of serum concentrations of KL-6.

Transcriptional and Proteomic Characterization of Telomere-Induced Senescence in a Human Alveolar Epithelial Cell Line.

Cellular senescence due to telomere dysfunction has been hypothesized to play a role in age-associated diseases including idiopathic pulmonary fibrosis (IPF). It has been postulated that paracrine mediators originating from senescent alveolar epithelia signal to surrounding mesenchymal cells and contribute to disease pathogenesis. However, murine models of telomere-induced alveolar epithelial senescence fail to display the canonical senescence-associated secretory phenotype (SASP) that is observed in senescent human cells. In an effort to understand human-specific responses to telomere dysfunction, we modeled telomere dysfunction-induced senescence in a human alveolar epithelial cell line. We hypothesized that this system would enable us to probe for differences in transcriptional and proteomic senescence pathways in vitro and to identify novel secreted protein (secretome) changes that potentially contribute to the pathogenesis of IPF. Following induction of telomere dysfunction, a robust senescence phenotype was observed. RNA-seq analysis of the senescent cells revealed the SASP and comparisons to previous murine data highlighted differences in response to telomere dysfunction. We conducted a proteomic analysis of the senescent cells using a novel biotin ligase capable of labeling secreted proteins. Candidate biomarkers selected from our transcriptional and secretome data were then evaluated in IPF and control patient plasma. Four novel proteins were found to be differentially expressed between the patient groups: stanniocalcin-1, contactin-1, tenascin C, and total inhibin. Our data show that human telomere-induced, alveolar epithelial senescence results in a transcriptional SASP that is distinct from that seen in analogous murine cells. Our findings suggest that studies in animal models should be carefully validated given the possibility of species-specific responses to telomere dysfunction. We also describe a pragmatic approach for the study of the consequences of telomere-induced alveolar epithelial cell senescence in humans.

Crucial Biomarkers for Pulmonary Arterial Hypertension (PAH) by Transcriptome Comparison with Idiopathic Pulmonary Fibrosis with and without PH and Identification of Essential Signaling Pathways- A Meta Analysis and Bioinformatics Study

The development of pulmonary arterial hypertension (group I PH) complicates many interstitial lung diseases, including idiopathic pulmonary fibrosis (IPF) mostly present with underlined pulmonary hypertension, is suspected to be an independent risk factor for mortality in chronic lung diseases. This meta-analysis of transcriptomics study of pulmonary arterial hypertension and pulmonary fibrosis associated with and without pulmonary hypertension aims to utilize current evidences to extract novel genetic identifiers specifically for PAH in order to identify it among all 5 groups of pulmonary hypertension in IPF patients using pre existing vast number of observational experimental databases freely accessible publicly to facilitate early diagnosis of PAH and thereby improving its therapeutics. This meta-analysis framework extracts expression intensity features from each study, corresponding to genes that are consistently among the highly significant differentially expressed genes (DEGs) in PAH and IPF (with and without PH).

Targeting FSTL1 for Multiple Fibrotic and Systemic Autoimmune Diseases

Follistatin-like 1 (FSTL1) is a matricellular protein that is upregulated during development and disease, including idiopathic pulmonary fibrosis (IPF), keloid, and arthritis. The profibrotic and pro-inflammatory roles of FSTL1 have been intensively studied during the last several years, as well as in this report. We screened and identified epitope-specific monoclonal neutralizing antibodies (nAbs) to functionally block FSTL1. FSTL1 nAbs attenuated bleomycin-induced pulmonary and dermal fibrosis invivo and transforming growth factor (TGF)-β1-induced dermal fibrosis exvivo in human skin. In addition, FSTL1 nAbs significantly reduced existing lung fibrosis and skin fibrosis in experimental models. FSTL1 nAbs exerted their potent antifibrotic effects via reduced TGF-β1 responsiveness and subsequent myofibroblast activation and extracellular matrix production. We also observed that FSTL1 nAbs attenuated the severity of collagen-induced arthritis in mice, which was accompanied by reduced inflammatory responses invitro. Our findings suggest that FSTL1 nAbs are a promising new therapeutic strategy for the treatment of multiple organ fibrosis and systemic autoimmune diseases.

Contributions of alveolar epithelial cell quality control to pulmonary fibrosis.

Epithelial cell dysfunction has emerged as a central component of the pathophysiology of diffuse parenchymal diseases including idiopathic pulmonary fibrosis (IPF). Alveolar type 2 (AT2) cells represent a metabolically active lung cell population important for surfactant biosynthesis and alveolar homeostasis. AT2 cells and other distal lung epithelia, like all eukaryotic cells, contain an elegant quality control network to respond to intrinsic metabolic and biosynthetic challenges imparted by mutant protein conformers, dysfunctional subcellular organelles, and dysregulated telomeres. Failed AT2 quality control components (the ubiquitin-proteasome system, unfolded protein response, macroautophagy, mitophagy, and telomere maintenance) result in diverse cellular endophenotypes and molecular signatures including ER stress, defective autophagy, mitochondrial dysfunction, apoptosis, inflammatory cell recruitment, profibrotic signaling, and altered progenitor function that ultimately converge to drive downstream fibrotic remodeling in the IPF lung. As this complex network becomes increasingly better understood, opportunities will emerge to identify targets and therapeutic strategies for IPF.