Idiopathic pulmonary fibrosis is a serious and progressive chronic lung disease that is characterised by altered cellular composition and homoeostasis in the peripheral lung, leading to excessive ...accumulation of extracellular matrix and, ultimately, loss of lung function. It is the interstitial pneumonia with the worst prognosis—mortality 3–5 years after diagnosis is 50%. During the past decade, researchers have described several novel cellular and molecular mechanisms and signalling pathways implicated in the pathogenesis of idiopathic pulmonary fibrosis, resulting in the identification of new therapeutic targets. These advances will hopefully result in increased survival rates and improved quality of life for patients with this disorder in future.
Immune Mechanisms in Pulmonary Fibrosis Kolahian, Saeed; Fernandez, Isis E; Eickelberg, Oliver ...
American journal of respiratory cell and molecular biology,
09/2016, Letnik:
55, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Pulmonary fibrosis, particularly idiopathic pulmonary fibrosis, represents a chronic and progressive disease with high mortality and limited therapeutic options. Excessive deposition of extracellular ...matrix proteins results in fibrotic remodeling, alveolar destruction, and irreversible loss of lung function. Both innate and adaptive immune mechanisms contribute to fibrogenesis at several cellular and noncellular levels. Here, we summarize and discuss the role of immune cells (T cells, neutrophils, macrophages, and fibrocytes) and soluble mediators (cytokines and chemokines) involved in pulmonary fibrosis, pointing toward novel immune-based therapeutic strategies in the field.
Aging promotes lung function decline and susceptibility to chronic lung diseases, which are the third leading cause of death worldwide. Here, we use single cell transcriptomics and mass ...spectrometry-based proteomics to quantify changes in cellular activity states across 30 cell types and chart the lung proteome of young and old mice. We show that aging leads to increased transcriptional noise, indicating deregulated epigenetic control. We observe cell type-specific effects of aging, uncovering increased cholesterol biosynthesis in type-2 pneumocytes and lipofibroblasts and altered relative frequency of airway epithelial cells as hallmarks of lung aging. Proteomic profiling reveals extracellular matrix remodeling in old mice, including increased collagen IV and XVI and decreased Fraser syndrome complex proteins and collagen XIV. Computational integration of the aging proteome with the single cell transcriptomes predicts the cellular source of regulated proteins and creates an unbiased reference map of the aging lung.
The extracellular matrix (ECM) is a key regulator of tissue morphogenesis and repair. However, its composition and architecture are not well characterized. Here, we monitor remodeling of the ...extracellular niche in tissue repair in the bleomycin‐induced lung injury mouse model. Mass spectrometry quantified 8,366 proteins from total tissue and bronchoalveolar lavage fluid (BALF) over the course of 8 weeks, surveying tissue composition from the onset of inflammation and fibrosis to its full recovery. Combined analysis of proteome, secretome, and transcriptome highlighted post‐transcriptional events during tissue fibrogenesis and defined the composition of airway epithelial lining fluid. To comprehensively characterize the ECM, we developed a quantitative detergent solubility profiling (QDSP) method, which identified Emilin‐2 and collagen‐XXVIII as novel constituents of the provisional repair matrix. QDSP revealed which secreted proteins interact with the ECM, and showed drastically altered association of morphogens to the insoluble matrix upon injury. Thus, our proteomic systems biology study assigns proteins to tissue compartments and uncovers their dynamic regulation upon lung injury and repair, potentially contributing to the development of anti‐fibrotic strategies.
Synopsis
A proteome‐wide view of lung injury and repair was elucidated by mass spectrometry analysis of the dynamic composition of lung tissue compartments. In particular, the extracellular matrix proteome uncovers potential factors in stem cell mobilization and fibrosis resolution.
Proteomic analysis discovers signatures of consecutive phases of lung injury, fibrosis, and repair.
Combined proteomics and transcriptomics define the prevalence of post‐transcriptional events.
Compartment proteomics uncovers extracellular matrix and epithelial lining fluid composition.
In vivo solubility profiling reveals extracellular matrix interactions with secreted proteins.
A proteome‐wide view of lung injury and repair was elucidated by mass spectrometry analysis of the dynamic composition of lung tissue compartments. In particular, the extracellular matrix proteome uncovers potential factors in stem cell mobilization and fibrosis resolution.
Circulating immune cell populations have been shown to contribute to interstitial lung disease (ILD). In this study, we analysed circulating and lung resident monocyte populations, and assessed their ...phenotype and recruitment from the blood to the lung in ILD. Flow cytometry analysis of blood samples for quantifying circulating monocytes was performed in 105 subjects: 83 with ILD (n=36, n=28 and n=19 for nonspecific interstitial pneumonia, hypersensitivity pneumonitis and connective-tissue disease-associated ILD, respectively), as well as 22 controls. Monocyte localisation and abundance were assessed using immunofluorescence and flow cytometry of lung tissue. Monocyte populations were cultured either alone or with endothelial cells to assess fractalkine-dependent transmigration pattern. We show that circulating classical monocytes (CM) were increased in ILD compared with controls, while nonclassical monocytes (NCM) were decreased. CM abundance correlated inversely with lung function, while NCM abundance correlated positively. Both CCL2 and CX3CL1 concentrations were increased in plasma and lungs of ILD patients. Fractalkine co-localised with ciliated bronchial epithelial cells, thereby creating a chemoattractant gradient towards the lung. Fractalkine enhanced endothelial transmigration of NCM in ILD samples only. Immunofluorescence, as well as flow cytometry, showed an increased presence of NCM in fibrotic niches in ILD lungs. Moreover, NCM in the ILD lungs expressed increased CX3CR1, M2-like and phagocytic markers. Taken together, our data support that in ILD, fractalkine drives the migration of CX3CR1
NCM to the lungs, thereby perpetuating the local fibrotic process.
The immunoproteasome is a specialized type of proteasome involved in MHC class I antigen presentation, antiviral adaptive immunity, autoimmunity, and is also part of a broader response to stress. ...Whether the immunoproteasome is regulated by DNA stress, however, is not known. We here demonstrate that mitochondrial DNA stress upregulates the immunoproteasome and MHC class I antigen presentation pathway via cGAS/STING/type I interferon signaling resulting in cell autonomous activation of CD8+ T cells. The cGAS/STING‐induced adaptive immune response is also observed in response to genomic DNA and is conserved in epithelial and mesenchymal cells of mice and men. In patients with idiopathic pulmonary fibrosis, chronic activation of the cGAS/STING‐induced adaptive immune response in aberrant lung epithelial cells concurs with CD8+ T‐cell activation in diseased lungs. Genetic depletion of the immunoproteasome and specific immunoproteasome inhibitors counteract DNA stress induced cytotoxic CD8+ T‐cell activation. Our data thus unravel cytoplasmic DNA sensing via the cGAS/STING pathway as an activator of the immunoproteasome and CD8+ T cells. This represents a novel potential pathomechanism for pulmonary fibrosis that opens new therapeutic perspectives.
Synopsis
Immunoproteasomes are activated by interferons and involved in MHC class I‐mediated CD8+ T‐cell activation as part of antiviral immune responses. This study demonstrates that cytoplasmic DNA sensing by the cGAS/STING pathway induces immunoproteasome‐mediated activation of CD8+ T cells that may be involved in idiopathic pulmonary fibrosis.
Sensing of intracellular mitochondrial and genomic DNA via the cGAS/STING pathway activates the immunoproteasome and MHC class I antigen presentation in human and murine epithelial cells and fibroblasts.
cGAS/STING activation induces CD8+ T cell adaptive immune responses in a cell‐autonomous manner.
Immunoproteasomes and CD8+ T cells are activated in lungs of patients with idiopathic pulmonary fibrosis.
The DNA‐sensing cGAS/STING pathway regulates immunoproteasome function and MHC class I antigen presentation to promote T‐cell activation that may underlie pathology of idiopathic pulmonary fibrosis.
The ubiquitin-proteasome system is critical for maintenance of protein homeostasis by degrading polyubiquitinated proteins in a spatially and temporally controlled manner. Cell and protein ...homeostasis are altered upon pathological tissue remodeling. Dysregulation of the proteasome has been reported for several chronic diseases of the heart, brain, and lung. We hypothesized that proteasome function is altered upon fibrotic lung remodeling, thereby contributing to the pathogenesis of idiopathic pulmonary fibrosis (IPF).
To investigate proteasome function during myofibroblast differentiation.
We treated lung fibroblasts with transforming growth factor (TGF)-β and examined proteasome composition and activity. For in vivo analysis, we used mouse models of lung fibrosis and fibrotic human lung tissue.
We demonstrate that induction of myofibroblast differentiation by TGF-β involves activation of the 26S proteasome, which is critically dependent on the regulatory subunit Rpn6. Silencing of Rpn6 in primary human lung fibroblasts counteracted TGF-β-induced myofibroblast differentiation. Activation of the 26S proteasome and increased expression of Rpn6 were detected during bleomycin-induced lung remodeling and fibrosis. Importantly, Rpn6 is overexpressed in myofibroblasts and basal cells of the bronchiolar epithelium in lungs of patients with IPF, which is accompanied by enhanced protein polyubiquitination.
We identified Rpn6-dependent 26S proteasome activation as an essential feature of myofibroblast differentiation in vitro and in vivo, and our results suggest it has an important role in IPF pathogenesis.
Given the importance of pirfenidone as the first worldwide-approved drug for idiopathic pulmonary fibrosis treatment, its pharmacodynamic properties and the metabolic response to pirfenidone ...treatment have not been fully elucidated. The aim of the present study was to get molecular insights of pirfenidone-related pharmacometabolomic response using MALDI-FTICR-MSI. Quantitative MALDI-FTICR-MSI was carried out for determining the pharmacokinetic properties of pirfenidone and its related metabolites 5-hydroxymethyl pirfenidone and 5-carboxy pirfenidone in lung, liver and kidney. To monitor the effect of pirfenidone administration on endogenous cell metabolism, additional in situ endogenous metabolite imaging was performed in lung tissue sections. While pirfenidone is highly abundant and delocalized across the whole micro-regions of lung, kidney and liver, 5-hydroxymethyl pirfenidone and 5-carboxy pirfenidone demonstrate heterogeneous distribution patterns in lung and kidney. In situ endogenous metabolite imaging study of lung tissue indicates no significant effects of pirfenidone on metabolic pathways. Remarkably, we found 129 discriminative
m/z
values which represent clear differences between control and treated lungs, the majority of which are currently unknown. PCA analysis and heatmap view can accurately distinguish control and treated groups. This is the first pharmacokinetic study to investigate the tissue distribution of orally administered pirfenidone and its related metabolites simultaneously in organs without labeling. The combination of pharmametabolome with histological features provides detailed mapping of drug effects on metabolism as response of heathy lung tissue to pirfenidone treatment.
Cigarette smoking is associated with emphysema and radiographic interstitial lung abnormalities. The degree to which interstitial lung abnormalities are associated with reduced total lung capacity ...and the extent of emphysema is not known.
We looked for interstitial lung abnormalities in 2416 (96%) of 2508 high-resolution computed tomographic (HRCT) scans of the lung obtained from a cohort of smokers. We used linear and logistic regression to evaluate the associations between interstitial lung abnormalities and HRCT measurements of total lung capacity and emphysema.
Interstitial lung abnormalities were present in 194 (8%) of the 2416 HRCT scans evaluated. In statistical models adjusting for relevant covariates, interstitial lung abnormalities were associated with reduced total lung capacity (-0.444 liters; 95% confidence interval CI, -0.596 to -0.292; P<0.001) and a lower percentage of emphysema defined by lung-attenuation thresholds of -950 Hounsfield units (-3%; 95% CI, -4 to -2; P<0.001) and -910 Hounsfield units (-10%; 95% CI, -12 to -8; P<0.001). As compared with participants without interstitial lung abnormalities, those with abnormalities were more likely to have a restrictive lung deficit (total lung capacity <80% of the predicted value; odds ratio, 2.3; 95% CI, 1.4 to 3.7; P<0.001) and were less likely to meet the diagnostic criteria for chronic obstructive pulmonary disease (COPD) (odds ratio, 0.53; 95% CI, 0.37 to 0.76; P<0.001). The effect of interstitial lung abnormalities on total lung capacity and emphysema was dependent on COPD status (P<0.02 for the interactions). Interstitial lung abnormalities were positively associated with both greater exposure to tobacco smoke and current smoking.
In smokers, interstitial lung abnormalities--which were present on about 1 of every 12 HRCT scans--were associated with reduced total lung capacity and a lesser amount of emphysema. (Funded by the National Institutes of Health and the Parker B. Francis Foundation; ClinicalTrials.gov number, NCT00608764.).
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