Age-dependent dysregulation of redox genes may contribute to fibrotic pulmonary disease susceptibility.
ABSTRACT: Aging is associated with enhanced oxidative stress and increased susceptibility to numerous diseases. This relationship is particularly striking with respect to the incidence of fibrotic lung disease. To identify potential mechanisms underlying the association between aging and susceptibility to fibrotic lung disease we analyzed transcriptome data from 342 disease-free human lung samples as a function of donor age. Our analysis reveals that aging in lung is accompanied by modest yet progressive changes in genes modulating redox homeostasis, the TGF-beta 1 signaling axis, and the extracellular matrix (ECM), pointing to an aging lung functional network (ALFN). Further, the transcriptional changes we document are tissue-specific, with age-dependent gene expression patterns differing across organ systems. Our findings suggest that the age-associated increased incidence of fibrotic pulmonary disease occurs in the context of tissue-specific, age-dependent transcriptional changes. Understanding the relationship between age-associated gene expression and susceptibility to fibrotic pulmonary disease may allow for more accurate risk stratification and effective therapeutic interventions within this challenging clinical space.
Project description:Pulmonary fibrosis develops as a consequence of environmentally induced lung injury and/or an inherent disease susceptibility causing fibroblast activation, proliferation and extracellular matrix deposition. The study was undertaken to characterise global gene expression in pulmonary fibroblasts to better understand the mechanisms underlying the fibrotic fibroblast phenotype. Gene expression was evaluated in lung fibroblasts derived from ten controls (normal periphery of resected tumor), open lung biopsies from eight patients with interstitial lung disease associated with systemic sclerosis (fibrotic non specific interstitial pneumonia pattern on biopsy), and from three patients with usual interstitial pneumonia. Lung fibroblasts were grown to confluence in DMEM with 10% fetal calf serum. At confluence, lung fibroblasts were serum-deprived for 44 hours in the presence of fibroblast growth medium with the addition of 0.1% bovine serum albumin (Sigma).
Project description:Collagen-producing myofibroblast transdifferentiation is considered a crucial determinant in the formation of scar tissue in the lungs of patients with idiopathic pulmonary fibrosis. Multiple resident pulmonary cell types and bone marrow-derived fibrocytes have been implicated as contributors to fibrotic lesions because of the transdifferentiation potential of these cells into myofibroblasts. In this study, we assessed the expression of Wilms tumor 1 (WT1), a known marker of mesothelial cells, in various cell types in normal and fibrotic lungs. We demonstrate that WT1 is expressed by both mesothelial and mesenchymal cells in idiopathic pulmonary fibrosis lungs but has limited or no expression in normal human lungs. We also demonstrate that WT1(+) cells accumulate in fibrotic lung lesions, using two different mouse models of pulmonary fibrosis and WT1 promoter-driven fluorescent reporter mice. Reconstitution of bone marrow cells into a TGF-? transgenic mouse model demonstrated that fibrocytes do not transform into WT1(+) mesenchymal cells, but they do augment accumulation of WT1(+) cells in severe fibrotic lung disease. Importantly, the number of WT1(+) cells in fibrotic lesions was correlated with severity of lung disease as assessed by changes in lung function, histology, and hydroxyproline levels in mice. Finally, inhibition of WT1 expression was sufficient to attenuate collagen and other extracellular matrix gene production by mesenchymal cells from both murine and human fibrotic lungs. Thus, the results of this study demonstrate a novel association between fibrocyte-driven WT1(+) cell accumulation and severe fibrotic lung disease.
Project description:The aging of the human population has resulted in an unprecedented increase in the incidence and prevalence of age-related diseases, including those of the lung. Idiopathic pulmonary fibrosis is a disease of aging, and is characterized by a progressive decline in lung function and high mortality. Recent studies suggest that mitochondrial dysfunction, which can accompany aging phenotypes, may contribute to the pathogenesis of idiopathic pulmonary fibrosis. In this review, we explore current evidence for mitochondrial dysfunction in alveolar epithelial cells, fibroblasts, and immune cells that participate in the fibrotic process. Further, the fates of these cell populations and the potential to target mitochondrial dysfunction as a therapeutic strategy are discussed.
Project description:Fibrotic interstitial lung diseases (ILDs) have a high mortality rate with an unpredictable disease course and clinical features that frequently overlap. Recent data indicate important roles for genomics in the mechanisms underlying susceptibility and progression of pulmonary fibrosis. The impact of these genomic markers on pharmacotherapy and their contribution to outcomes is increasingly recognized. Interstitial lung abnormalities, frequently considered representative of early ILD, have been consistently associated with the MUC5B promoter polymorphism, a common gene variant. Other rare gene variant mutations, including TERT, TERC, SFTPC, and DKC1, may be present in patients with familial interstitial pneumonia and are frequently associated with a usual interstitial pneumonia pattern of fibrosis. The minor allele of the MUC5B rs35705950 genotype is prevalent in several sporadic forms of ILD, including idiopathic pulmonary fibrosis and chronic hypersensitivity pneumonitis. Gene mutations that characterize familial pulmonary fibrosis may be present in patients with connective tissue disease-related ILD, such as rheumatoid arthritis-ILD. Additionally, shorter telomere lengths and mutations in telomere biology-related genes have been demonstrated in both familial and sporadic ILD, with significant implications for disease progression, lung function, and survival. An improved understanding of the impact of genetic and genomic risk factors on disease progression would better guide personalized therapeutic choices in persons with fibrotic ILD.
Project description:The pathogenesis of idiopathic pulmonary fibrosis (IPF), an intractable interstitial lung disease, is unclear. Recessive mutations in some genes implicated in Hermansky-Pudlak syndrome (HPS) cause HPS-associated interstitial pneumonia (HPSIP), a clinical entity that is similar to IPF. We previously reported that HPS1-/- embryonic stem cell-derived 3D lung organoids showed fibrotic changes. Here, we show that the introduction of all HPS mutations associated with HPSIP promotes fibrotic changes in lung organoids, while the deletion of HPS8, which is not associated with HPSIP, does not. Genome-wide expression analysis revealed the upregulation of interleukin-11 (IL-11) in epithelial cells from HPS mutant fibrotic organoids. IL-11 was detected predominantly in type 2 alveolar epithelial cells in end-stage IPF, but was expressed more broadly in HPSIP. Finally, IL-11 induced fibrosis in WT organoids, while its deletion prevented fibrosis in HPS4-/- organoids, suggesting IL-11 as a therapeutic target. hPSC-derived 3D lung organoids are, therefore, a valuable resource to model fibrotic lung disease.
Project description:Idiopathic pulmonary fibrosis (IPF) is an incurable disease with poor prognosis and unknown etiology. The poor clinical outcome is associated with enhanced microbial burden in bronchoalveolar lavage fluid from IPF patients. However, whether microbes from the respiratory tract fluid cause the disease remains uncertain. Tissue-associated microbes can influence host physiology in health and disease development. The aim of this study was to evaluate the existence of microbes in lung fibrotic tissues. We evaluated the microbial community in lung tissues from IPF and from human transforming growth factor-?1 (TGF-?1) transgenic mice with lung fibrosis by oligotyping. We also evaluated the microbial population in non-tumor-bearing tissues from surgical specimens of lung cancer patients. The phyla Firmicutes and the genus Clostridium tended to be predominant in the lung tissue from IPF and lung cancer patients. Oligotyping analysis revealed a predominance of bacteria belonging to the genera Halomonas, Shewanella, Christensenella, and Clostridium in lung tissue from IPF and lung cancer. Evaluation of the microbial community in the lung tissue from mice revealed abundance of Proteobacteria in both wild-type (WT) littermates and transgenic mice. However, the genus Halomonas tended to be more abundant in TGF-?1 transgenic mice compared to WT mice. In conclusion, this study describes tissue-associated microbes in lung fibrotic tissues from IPF patients and from aging TGF-?1 transgenic mice.
Project description:Idiopathic pulmonary fibrosis (IPF) is a chronic fibrotic lung disease that is prevalent in individuals >50 years of age, with a median survival of 3-5 years and limited therapeutic options. The disease is characterized by collagen deposition and remodeling of the lung parenchyma in a process that is thought to be driven by collagen-expressing immune and structural cells. The G-protein coupled C-X-C chemokine receptor 4, CXCR4, is a candidate therapeutic target for IPF owing to its role in the recruitment of CXCR4+ fibrocytes from the bone marrow to fibrotic lung tissue and its increased expression levels by structural cells in fibrotic lung tissue. We have engineered a novel fully human single domain antibody "i-body" called AD-114 that binds with high affinity to human CXCR4. We demonstrate here that AD-114 inhibits invasive wound healing and collagen 1 secretion by human IPF fibroblasts but not non-diseased control lung fibroblasts. Furthermore, in a murine bleomycin model of pulmonary fibrosis, AD-114 reduced the accumulation of fibrocytes (CXCR4+/Col1+/CD45+) in fibrotic murine lungs and ameliorated the degree of lung injury. Collectively, these studies demonstrate that AD-114 holds promise as a new biological therapeutic for the treatment of IPF.
Project description:Idiopathic pulmonary fibrosis (IPF) is a fatal chronic lung disease characterized by progressive scarring of the lung tissue, leading to respiratory failure. There is no cure for IPF, and current anti-fibrotic treatments modestly arrest its further progression. IPF prevalence and incidence increase with age, which is a recognized risk factor. Intense clinical and basic research over the last fifteen years has shown that hallmarks of accelerated aging are present in the lungs of patients with IPF. Different cell types in IPF lungs exhibit premature hallmarks of aging, including telomere attrition and cellular senescence. In this Review, we discuss recent insights into the mechanisms behind these age-related alterations and their contribution to the development of lung fibrosis. We focus on the genetic and molecular basis of telomere attrition in alveolar type II epithelial cells, which promote cellular senescence and lung fibrosis. Mechanistically, senescent cells secrete pro-fibrotic factors that activate scar-forming myofibroblasts. Ultimately, senescent alveolar epithelial cells lose their regenerative capacity, impeding fibrosis resolution. In addition, mitochondrial dysfunction is strongly associated with the appearance of senescent epithelial cells and senescent myofibroblasts in IPF, which persist in the fibrotic tissue by adapting their metabolic pathways and becoming resistant to apoptosis. We discuss emerging novel therapeutic strategies to treat IPF by targeting cellular senescence with the so-called senotherapeutics.
Project description:<b>Background: </b>Comorbidities are frequent and have been associated with poor quality of life, increased hospitalizations, and mortality in patients with interstitial lung disease (ILD). However, it is unclear how comorbidities lead to these negative outcomes and whether they could influence ILD disease progression. The goal of this study was to identify clusters of patients based on similar comorbidity profiles and to determine whether these clusters were associated with rate of lung function decline and/or mortality.<br><br><b>Methods: </b>Patients with a major fibrotic ILD (idiopathic pulmonary fibrosis (IPF), fibrotic hypersensitivity pneumonitis, connective tissue disease-associated ILD, and unclassifiable ILD) from the CAnadian REgistry for Pulmonary Fibrosis (CARE-PF) were included. Hierarchical agglomerative clustering of comorbidities, age, sex, and smoking pack-years was conducted for each ILD subtype to identify combinations of these features that frequently occurred together in patients. The association between clusters and change in lung function over time was determined using linear mixed effects modeling, with adjustment for age, sex, and smoking pack-years. Kaplan Meier curves were used to assess differences in survival between the clusters.<br><br><b>Results: </b>Discrete clusters were identified within each fibrotic ILD. In IPF, males with obstructive sleep apnea (OSA) had more rapid decline in FVC %-predicted (- 11.9% per year [95% CI - 15.3, - 8.5]) compared to females without any comorbidities (- 8.1% per year [95% CI - 13.6, - 2.7]; p?=?0.03). Females without comorbidities also had significantly longer survival compared to all other IPF clusters. There were no significant differences in rate of lung function decline or survival between clusters in the other fibrotic ILD subtypes.<br><br><b>Conclusions: </b>The combination of male sex and OSA may portend worse outcomes in IPF. Further research is required to elucidate the interplay between sex and comorbidities in ILD, as well as the role of OSA in ILD disease progression.
Project description:Idiopathic pulmonary fibrosis (IPF) is a fatal disease characterized by interstitial remodelling, leading to compromised lung function. Cellular senescence markers are detectable within IPF lung tissue and senescent cell deletion rejuvenates pulmonary health in aged mice. Whether and how senescent cells regulate IPF or if their removal may be an efficacious intervention strategy is unknown. Here we demonstrate elevated abundance of senescence biomarkers in IPF lung, with p16 expression increasing with disease severity. We show that the secretome of senescent fibroblasts, which are selectively killed by a senolytic cocktail, dasatinib plus quercetin (DQ), is fibrogenic. Leveraging the bleomycin-injury IPF model, we demonstrate that early-intervention suicide-gene-mediated senescent cell ablation improves pulmonary function and physical health, although lung fibrosis is visibly unaltered. DQ treatment replicates benefits of transgenic clearance. Thus, our findings establish that fibrotic lung disease is mediated, in part, by senescent cells, which can be targeted to improve health and function.