Subpleural Fibrosis Research Articles

The importance of subpleural fibrosis in the prognosis of patients with idiopathic interstitial pneumonias

PurposeTo compare computer-aided diagnostic results with histological findings obtained by surgical biopsy and evaluate whether subpleural lesion volumes can aid identification of idiopathic pulmonary fibrosis (IPF).Materials and MethodsWe retrospectively analyzed computed tomography (CT) images of 79 patients (43 with fibrosing nonspecific interstitial pneumonia (fNSIP) and 36 with IPF) using the Gaussian Histogram Normalized Correlation (GHNC) system. We determined the H-pattern based on honeycomb and/or fibrosis with traction bronchiectasis on CT, and measured the H-pattern volume ratio at the biopsy sites and in the subpleural area. The biopsy site CT data were compared with biopsy specimens using Spearman’s correlation. H-pattern volumes in the subpleural area within 2mm under the pleura (H2) were analyzed to predict IPF diagnosis and patients prognosis. ResultsThe H-pattern volume ratio at the biopsy sites showed significant correlation with histological honeycomb (r=0.355, p<0.001), subpleural collapse (r=0.410, p<0.001), and heterogeneity (r=0.484, p<0.001). Multivariate regression analysis, adjusting for age, sex, and CT results, revealed that the H2 was a significant independent predictor of IPF diagnosis (odds ratio: 1.073; p=0.048). H2 correlated with patients’ survival after adjusting for age (p=0.003). ConclusionThe computer-aided H-pattern volume ratio of the subpleural area indicates subpleural abnormalities quantitatively and may help diagnose IPF.

Lung remodeling in aging surfactant protein D deficient mice

Pulmonary surfactant, a mixture of lipids and proteins at the air–liquid interface of alveoli, prevents the lungs from collapsing due to surface tension. One constituent is surfactant-associated protein-D (SP-D), a protein involved in surfactant homeostasis and innate immunity. Mice deficient in SP-D (SP-D (−/−)) has been described as developing a characteristic phenotype which affects the surfactant system (including changes in the intra-cellular and intra-alveolar surfactant pool, alveolar epithelial type II cells and alveolar macrophages), lung architecture and its inflammatory state (development of an emphysema-like pathology, inflammatory cell infiltration). Furthermore, it has been described that these mice develop sub-pleural fibrosis and a thickening of alveolar septal walls. The aim of the present study was to systematically investigate the long term progression of this phenotype with special focus on parenchymal remodeling, whether there are progressive emphysematous changes and whether there is progressive septal wall thickening which might indicate the development of pulmonary fibrosis. By means of design-based stereology and light microscopy, lungs of wild type (wt) and SP-D (−/−) mice of four age groups (3, 6, 12 and ∼18 months) were investigated. The data do not suggest a relevant spontaneous pro-fibrotic remodeling or a destructive process in the aging SP-D (−/−) mice. We demonstrated neither a significant destructive emphysema nor significant thickening of alveolar septal walls, but the data suggest an increase in the number weighted mean alveolar volume in aging SP-D (−/−) mice without loss of alveoli or alveolar epithelial surface area per lung. This increase may reflect over-distension due to altered mechanical properties of alveoli. In the light of our findings and data from the literature, the question arises as to whether a lack of SP-D promotes structural changes in the lung which have been described as being associated with aging lungs. Furthermore, data from wt mice point to an ongoing alveolarization during adult life in C57Bl/6NCrl mice. Our data may promote further studies on the morphological development of the aging lung and the role of SP-D in this process.

MiR-18a-5p Inhibits Sub-pleural Pulmonary Fibrosis by Targeting TGF-β Receptor II

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease that typically leads to respiratory failure and death within 3-5 years of diagnosis. Sub-pleural pulmonary fibrosis is a pathological hallmark of IPF. Bleomycin treatment of mice is a an established pulmonary fibrosis model. We recently showed that bleomycin-induced epithelial-mesenchymal transition (EMT) contributes to pleural mesothelial cell (PMC) migration and sub-pleural pulmonary fibrosis. MicroRNA (miRNA) expression has recently been implicated in the pathogenesis of IPF. However, changes in miRNA expression in PMCs and sub-pleural fibrosis have not been reported. Using cultured PMCs and a pulmonary fibrosis animal model, we found that miR-18a-5p was reduced in PMCs treated with bleomycin and that downregulation of miR-18a-5p contributed to EMT of PMCs. Furthermore, we determined that miR-18a-5p binds to the 3' UTR region of transforming growth factor β receptor II (TGF-βRII) mRNA, and this is associated with reduced TGF-βRII expression and suppression of TGF-β-Smad2/3 signaling. Overexpression of miR-18a-5p prevented bleomycin-induced EMT of PMC and inhibited bleomycin-induced sub-pleural fibrosis in mice. Taken together, our data indicate that downregulated miR-18a-5p mediates sub-pleural pulmonary fibrosis through upregulation of its target, TGF-βRII, and that overexpression of miR-18a-5p might therefore provide a novel approach to the treatment of IPF.

Spontaneous and Dosing Route-related Lung Lesions in Beagle Dogs from Oral Gavage and Inhalation Toxicity Studies: Differentiation from Compound-induced Lesions.

This study was conducted to characterize lung microscopic lesions in control beagle dogs from inhalation and oral gavage toxicity studies, to determine differences associated with the route of administration, and to discuss distinguishing features from compound-induced lung lesions. Samples from 138 control dogs from oral gavage studies and 124 control dogs from inhalation (vehicle control) studies were evaluated microscopically. There was no significant sex-related difference in the incidence of all lesions. Perivascular mononuclear cell infiltration, centriacinar mixed cell infiltration, bronchopneumonia, subpleural septal fibrosis, and alveolar macrophage accumulation were the most common lesions. Aspiration pneumonia was more common in dogs from gavage studies, suggesting reflux after gavage dosing or accidental administration of test formulation as possible causes. Centriacinar mixed cell infiltration was more common in dogs from inhalation studies, suggesting mild irritation by the vehicles used. Vascular lesions, which included pulmonary arteriopathy and smooth muscle mineralization, were observed in a few animals. Some of the spontaneous lesions are similar to lesions induced by test compounds. Compared to spontaneous lesions, compound-induced lesions tend to be multifocal or diffuse, follow a pattern of distribution (e.g., centriacinar, perivascular, and interstitial), show a dose response in the incidence and severity, and may show cell-specific toxicity.

Fibroélastose pleuro-parenchymateuse

Idiopathic pleuroparechymal fibroelastosis appears in the litlerature under that name in 2004.The diagnosis is usually suspected on the basis of a patient with dyspnea and a compatible radiographic pattern with a pleural thickening as well as a subpleural fibrosis in the uppers lobes and a decreasing pulmonary volume, an ascension of the pulmonary hiliums and a shrinking of the apex.The definitive diagnosis requires anatomopathological analysis with specific colouring of Elastin fibres.Differential diagnosis are tuberculosis consequences, connective tissue disease, polyarteritis, the lung asbestosis, and the apical cap.The disease can appear at any age, dyspnea is still present, caughs, weight loss and chest pain are common. Platythorax is typical. Lung fonction is altered with a restrictive spirometry pattern. Spontaneous pneumothorax is a common complication. The disease progresses toward a restrictive and an hypercanic respiratory insufficiency.Etiologies are idiopathic and commonly iatrogenic (lung transplantation, chemotherapy, bone marrow transplantation). There also are familial forms with genetics abnormalities.The prognosis is poor with a fast vital capacity decreasing.The corticosteroids are useless. At the moment there is no effective treatment other than lung transplantation.

Truncated Plasminogen Activator Inhibitor-1 Protein Protects From Pulmonary Fibrosis Mediated by Irradiation in a Murine Model

To determine whether the delivery of recombinant truncated plasminogen activator inhibitor-1 (PAI-1) protein (rPAI-1(23)) would protect from the development of radiation-induced lung injury. C57Bl/6 mice received intraperitoneal injections of rPAI-1(23) (5.4 μg/kg/d) or vehicle for 18 weeks, beginning 2 days before irradiation (IR) (5 daily fractions of 6 Gy). Cohorts of mice were followed for survival (n=8 per treatment) and tissue collection (n=3 per treatment and time point). Fibrosis in lung was assessed with Masson-Trichrome staining and measurement of hydroxyproline content. Senescence was assessed with staining for β-galactosidase activity in lung and primary pneumocytes. Hydroxyproline content in irradiated lung was significantly reduced in mice that received rPAI-1(23) compared with mice that received vehicle (IR+vehicle: 84.97 μg/lung; IR+rPAI-1(23): 56.2 μg/lung, P=.001). C57Bl/6 mice exposed to IR+vehicle had dense foci of subpleural fibrosis at 19 weeks, whereas the lungs of mice exposed to IR+rPAI-1(23) were largely devoid of fibrotic foci. Cellular senescence was significantly decreased by rPAI-1(23) treatment in primary pneumocyte cultures and in lung at multiple time points after IR. These studies identify that rPAI-1(23) is capable of preventing radiation-induced fibrosis in murine lungs. These antifibrotic effects are associated with increased fibrin metabolism, enhanced matrix metalloproteinase-3 expression, and reduced senescence in type 2 pneumocytes. Thus, rPAI-1(23) is a novel therapeutic option for radiation-induced fibrosis.

Rare idiopathic interstitial pneumonias: LIP and PPFE and rare histologic patterns of interstitial pneumonias: AFOP and BPIP.

In the 2013 reclassification of the idiopathic interstitial pneumonias (IIPs), two rare IIPs (idiopathic lymphoid interstitial pneumonia (LIP), idiopathic pleuroparenchymal fibroelastosis (IPPFE)) and two rare histologic patterns (acute fibrinous and organizing pneumonia (AFOP), bronchiolocentric pattern of interstitial pneumonia (BPIP)) are described. All these entities are rare with small series published to date, mostly containing primary and secondary forms of disease. LIP is histologically characterized by diffuse polyclonal lymphoid cell infiltrate surrounding the airways and expanding the interstitium. Thin-walled cysts and diffuse ground glass are considered the typical radiologic features. The clinical course is highly variable with corticosteroid responsiveness evident in approximately half of cases. IPPFE is defined histologically by coexisting upper lobe pleural and intra-alveolar fibrosis with elastosis. Dense subpleural irregular fibrosis and consolidation are the cardinal radiologic features. A history of recurrent lower respiratory tract infection is frequent. Responses to immunomodulation have not been reported and the rate of progression appears to be highly variable. AFOP is a rare histologic pattern lying within the spectrum of acute/subacute lung injury, characterized by organizing pneumonia and intra-alveolar fibrin deposition without hyaline membranes. BPIP is characterized histologically by fibrosis and/or inflammation confined to the alveolar interstitium around bronchovascular bundles, overlapping with peribronchial metaplasia and fibrosis in some series. Currently, AFOP and BPIP are both best viewed as histological entities rather than true clinical disorders, in the absence of characteristic associated imaging patterns and clinical features.

P70 ribosomal S6 kinase regulates subpleural fibrosis following transforming growth factor-α expression in the lung.

The p70 ribosomal S6 kinase (S6K) is a downstream substrate that is phosphorylated and activated by the mammalian target of rapamycin complex and regulates multiple cellular processes associated with fibrogenesis. Recent studies demonstrate that aberrant mTORC1-S6K signaling contributes to various pathological conditions, but a direct role in pulmonary fibroproliferation has not been established. Increased phosphorylation of the S6K pathway is detected immediately following transforming growth factor-α (TGF-α) expression in a transgenic model of progressive lung fibrosis. To test the hypothesis that the S6K directly regulates pulmonary fibroproliferative disease we determined the cellular sites of S6K phosphorylation during the induction of fibrosis in the TGF-α model and tested the efficacy of specific pharmacological inhibition of the S6K pathway to prevent and reverse fibrotic disease. Following TGF-α expression increased phosphorylation of the S6K was detected in the airway and alveolar epithelium and the mesenchyme of advanced subpleural fibrotic regions. Specific inhibition of the S6K with the small molecule inhibitor LY-2584702 decreased TGF-α and platelet-derived growth factor-β-induced proliferation of lung fibroblasts in vitro. Administration of S6K inhibitors to TGF-α mice prevented the development of extensive subpleural fibrosis and alterations in lung mechanics, and attenuated the increase in total lung hydroxyproline. S6K inhibition after fibrosis was established attenuated the progression of subpleural fibrosis. Together these studies demonstrate targeting the S6K pathway selectively modifies the progression of pulmonary fibrosis in the subpleural compartment of the lung.

MTOR Inhibition With Rapamycin Mitigates Radiation-Induced Pulmonary Fibrosis in a Murine Model

Fibrosis is a late toxicity of radiation in lung. Radiation-induced pulmonary fibrosis (RIPF) is characterized by parenchymal cell depletion, inflammation, fibroblast proliferation, and collagen deposition. mTOR signaling has been implicated in inflammatory cytokine production, fibroblast proliferation, and epithelial stem cell senescence. We sought to determine if mTOR inhibition with rapamycin would mitigate RIPF. C57Bl/6 mice received a diet with rapamycin (14 mg/kg food; 0.056 mg/mouse/day) or control diet beginning one day prior to radiation and continuing until tissue collection or death. Cohorts of mice treated with rapamycin or control diet were exposed to thoracic irradiation in 5 daily fractions of 6 Gy (RT), and followed for survival (n=8 per group) and tissue collection (n=3 per time point). Histologic changes were evaluated by Masson-Trichrome staining at 16 weeks after RT. Inflammatory cytokine expression was evaluated by quantitative real time PCR. Senescence was assessed by staining for beta-galactosidase activity. To define the role of rapamycin in the fibroproliferative response, cell proliferation (MTT assay) and collagen deposition (Hydroxyproline assay) were examined in a mouse fibroblast cell line. Administration of rapamycin increased the median survival of irradiated mice from 116 days to 156 days (log rank p=0.006). At 16 weeks after irradiation, treatment with rapamycin reduced hydroxyproline content compared to vehicle treated irradiated controls (RT+vehicle: 45.9±11.8, RT+rapamycin: 21.4±6.0, or unirradiated+control chow: 25.7±5.0 μg/lung respectively, p=0.001). Mice exposed to RT+vehicle had dense foci of subpleural fibrosis at 16 weeks, a finding largely absent in RT+rapamycin treated mice. Rapamycin treatment attenuated IL-1β and TGF-β induction in lung in response to RT at multiple time points. Cellular senescence was significantly decreased by rapamycin treatment in primary type 2 pneumocytes (4-fold reduction at 5 days after RT, p=0.012) and in lung tissue at 16 weeks after RT (3-fold decrease, p<0.001). Treatment of NIH3T3 fibroblasts with rapamycin (50 ng/ml) resulted in decreased collagen production (1.3-fold decrease at 3 days after RT, p=0.013) and decreased proliferation (1.2-fold decrease, p=0.019). Rapamycin protected against RIPF in murine lungs through a reduction in inflammatory cytokine expression, extra cellular matrix production, and senescence in type2 pneumocytes. Rapamycin has the potential to be an effective therapy option for pulmonary fibrosis following thoracic radiation.

Pleuroparenchymal Fibroelastosis: Is it also an Idiopathic Entity?

Pleuroparenchymal fibroelastosis (PPFE) is a rare disease that has been recently included in the updated consensus on idiopathic interstitial pneumonias. It shares some clinical features with other chronic interstitial pneumonias (dyspnea, dry cough), and is radiologically characterized by pleural and subpleural parenchymal fibrosis and elastosis, mainly in the upper lobes. The main histological findings include pleural fibrosis and prominent subpleural and parenchymal fibroelastosis. Its characterization is based on the increasing number of cases reported in the literature, so several aspects of the etiology, pathogenesis and natural history are still unknown. Although some cases have been described as idiopathic, PPFE has been reported as a complication after bone marrow transplantation, lung transplantation and chemotherapy, especially with alkylating agents.Spontaneous or iatrogenic pneumothorax is a frequently reported complication of invasive diagnostic tests for identifying PPFE. The disease course is variable, ranging from slow progression to rapid clinical deterioration. No treatment has shown evidence of efficacy, and lung transplantation remains the only option for patients who fulfill the diagnostic criteria for this option. Recognizing and disseminating the specific features of PPFE are essential to raise the level of clinical suspicion for this entity, and to implement appropiate diagnostic and management by the multidisciplinary team.

Fibroelastosis pleuropulmonar: ¿es también una entidad idiopática?

Pleuroparenchymal fibroelastosis (PPFE) is a rare disease that has been recently included in the updated consensus on idiopathic interstitial pneumonias. It shares some clinical features with other chronic interstitial pneumonias (dyspnea, dry cough), and is radiologically characterized by pleural and subpleural parenchymal fibrosis and elastosis, mainly in the upper lobes. The main histological findings include pleural fibrosis and prominent subpleural and parenchymal fibroelastosis. Its characterization is based on the increasing number of cases reported in the literature, so several aspects of the etiology, pathogenesis and natural history are still unknown. Although some cases have been described as idiopathic, PPFE has been reported as a complication after bone marrow transplantation, lung transplantation and chemotherapy, especially with alkylating agents.Spontaneous or iatrogenic pneumothorax is a frequently reported complication of invasive diagnostic tests for identifying PPFE. The disease course is variable, ranging from slow progression to rapid clinical deterioration. No treatment has shown evidence of efficacy, and lung transplantation remains the only option for patients who fulfill the diagnostic criteria for this option. Recognizing and disseminating the specific features of PPFE is essential to raise the level of clinical suspicion for this entity, and to implement appropriate multidisciplinary diagnostic management.

Pleuroparenchymal fibroelastosis: Distinct pulmonary physiological features in nine patients.

Pleuroparenchymal fibroelastosis (PPFE) is a rare idiopathic interstitial pneumonia defined by pleural and subpleural parenchymal fibrosis predominantly in the upper lobes. Although the radiological and pathological characteristics of PPFE have become increasingly recognized, its pulmonary physiological features are not well understood. We reviewed nine patients with radiologically and histologically proven PPFE, and evaluated pulmonary physiological data. Of the nine patients, six were male and three were female. The median age at presentation was 61 years. Common symptoms were dyspnea on exertion, weight loss, and nonproductive cough. Recurrent pneumothorax was found in eight patients and pneumonia in four. Median pulmonary function test results were as follows: forced vital capacity, 55.4% predicted; total lung capacity (TLC), 67.1% predicted; residual volume (RV), 102.3% predicted; and RV/TLC, 143.6% predicted. RV/TLC was increased without evidence of small airway disease according to clinico-radiologic-pathologic evaluation. The median partial pressure of oxygen in arterial blood and the alveolar-arterial gradient of oxygen were within normal limits, although there was a slightly elevated partial pressure of carbon dioxide in arterial blood (PaCO2). PPFE progressed in all patients despite treatment with pirfenidone, corticosteroids, and immunosuppressive agents. Seven patients died during the follow-up, five because of hypercapnic respiratory failure. PPFE is characterized by severe mechanical restriction with high RV/TLC, causing increased PaCO2 and eventual hypercapnic respiratory failure. These physiological findings may be useful as an adjunct in the diagnosis of PPFE.

A modified murine model of systemic sclerosis: bleomycin given by pump infusion induced skin and pulmonary inflammation and fibrosis

Daily subcutaneous (sc) injection of bleomycin (BLM) causes dermal fibrosis but rarely causes lung changes in mice. There are also significant disadvantages to this traditional model for systemic sclerosis, including a variable distribution of lesions and a requirement for repetitive procedures. The present study was undertaken to develop a convenient method of BLM administration that yields stable dermal inflammation and fibrosis with extensive and reproducible interstitial lung disease (ILD) in mice. Osmotic minipumps containing BLM (150 mg/kg) or saline were implanted sc in C57BL/6 mice and the drug was delivered as a continuous infusion over 1∼4 weeks. The time course of morphological features, collagen content, and pro-inflammatory cytokine expression in the skin and the lungs were analyzed. Pathological examination demonstrated dominant inflammatory infiltrates at week 1 and significant fibrosis at week 4. Decreased microvessel density and increased myofibroblast counts were observed in the skin of BLM-treated mice at week 4. In addition, there were obvious increases in dermal infiltration of CD45+ leukocytes, including F4/80+ macrophages, Gr-1+ neutrophils, and CD3+ T lymphocytes in BLM-treated mice. IL-1β, IL-4, and CXCL2 transcripts were continually upregulated by BLM in the skin and lung tissues. In addition, lungs from BLM-treated mice showed significant inflammatory infiltrates and confluent subpleural fibrosis at week 4. In conclusion, this modified murine model for drug-induced systemic inflammation and fibrosis uses a single procedure and provides reproducible skin and lung lesions, mimicking human systemic sclerosis (SSc) with ILD-like manifestation.

Antifibrotic Role of αB-Crystallin Inhibition in Pleural and Subpleural Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by myofibroblast proliferation and extracellular-matrix accumulation. IPF typically starts in subpleural lung regions, and recent studies suggest that pleural mesothelial cells play a role in the onset of the disease. The transition of mesothelial cells into myofibroblasts (mesothelio-mesenchymal transition) is induced by the profibrotic cytokine, transforming growth factor (TGF)-β1, and is thought to play a role in the development and progression of IPF. The Mothers Against Decapentaplegic homolog (Smad)-dependent pathway is the main TGF-β1 pathway involved in fibrosis. αB-crystallin is constitutively expressed in the lungs, and is inducible by stress, acts as a chaperon, and is known to play a role in cell cytoskeleton architecture. We recently showed that the lack of αB-crystallin hampered TGF-β1 signaling by favoring Smad4 monoubiquitination and nuclear export. We demonstrate here, for the first time, that αB-crystallin is strongly overexpressed in the pleura of fibrotic lungs from patients with IPF and in rodent models of pleural/subpleural fibrosis. αB-crystallin-deficient mice are protected from pleural/subpleural fibrosis induced by the transient adenoviral-mediated overexpression of TGF-β1 or the intrapleural injection of bleomycin combined with carbon particles. We show that αB-crystallin inhibition hampers Smad4 nuclear localization in pleural mesothelial cells and the consequent characteristics of mesothelio-mesenchymal transition. αB-crystallin-deficient mesothelial cells fail to acquire the properties of myofibroblasts, thus limiting their migration in vivo and the progression of fibrosis in the lung parenchyma. In conclusion, our work demonstrates that αB-crystallin may be a key target for the development of specific drugs in the treatment of IPF.

Bleomycin induced epithelial–mesenchymal transition (EMT) in pleural mesothelial cells

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease characterized by the development of subpleural foci of myofibroblasts that contribute to the exuberant fibrosis. Recent studies revealed that pleural mesothelial cells (PMCs) undergo epithelial–mesenchymal transition (EMT) and play a pivotal role in IPF. In animal model, bleomycin induces pulmonary fibrosis exhibiting subpleural fibrosis similar to what is seen in human IPF. It is not known yet whether bleomycin induces EMT in PMCs. In the present study, PMCs were cultured and treated with bleomycin. The protein levels of collagen-I, mesenchymal phenotypic markers (vimentin and α-smooth muscle actin), and epithelial phenotypic markers (cytokeratin-8 and E-cadherin) were measured by Western blot. PMC migration was evaluated using wound-healing assay of culture PMCs in vitro, and in vivo by monitoring the localization of PMC marker, calretinin, in the lung sections of bleomycin-induced lung fibrosis. The results showed that bleomycin induced increases in collagen-I synthesis in PMC. Bleomycin induced significant increases in mesenchymal phenotypic markers and decreases in epithelial phenotypic markers in PMC, and promoted PMC migration in vitro and in vivo. Moreover, TGF-β1-Smad2/3 signaling pathway involved in the EMT of PMC was demonstrated. Taken together, our results indicate that bleomycin induces characteristic changes of EMT in PMC and the latter contributes to subpleural fibrosis.

Transforming growth factor alpha is a critical mediator of radiation lung injury.

Radiation fibrosis of the lung is a late toxicity of thoracic irradiation. Epidermal growth factor (EGF) signaling has previously been implicated in radiation lung injury. We hypothesized that TGF-α, an EGF receptor ligand, plays a key role in radiation-induced fibrosis in lung. Mice deficient in transforming growth factor (TGF-α(-/-)) and control C57Bl/6J (C57-WT) mice were exposed to thoracic irradiation in 5 daily fractions of 6 Gy. Cohorts of mice were followed for survival (n ≥ 5 per group) and tissue collection (n = 3 per strain and time point). Collagen accumulation in irradiated lungs was assessed by Masson's trichrome staining and analysis of hydroxyproline content. Cytokine levels in lung tissue were assessed with ELISA. The effects of TGF-α on pneumocyte and fibroblast proliferation and collagen production were analyzed in vitro. Lysyl oxidase (LOX) expression and activity were measured in vitro and in vivo. Irradiated C57-WT mice had a median survival of 24.4 weeks compared to 48.2 weeks for irradiated TGF-α(-/-) mice (P = 0.001). At 20 weeks after irradiation, hydroxyproline content was markedly increased in C57-WT mice exposed to radiation compared to TGF-α(-/-) mice exposed to radiation or unirradiated C57-WT mice (63.0, 30.5 and 37.6 μg/lung, respectively, P = 0.01). C57-WT mice exposed to radiation had dense foci of subpleural fibrosis at 20 weeks after exposure, whereas the lungs of irradiated TGF-α (-/-) mice were largely devoid of fibrotic foci. Lung tissue concentrations of IL-1β, IL-4, TNF-α, TGF-β and EGF at multiple time points after irradiation were similar in C57-WT and TGF-α(-/-) mice. TGF-α in lung tissue of C57-WT mice rose rapidly after irradiation and remained elevated through 20 weeks. TGF-α(-/-) mice had lower basal LOX expression than C57-WT mice. Both LOX expression and LOX activity were increased after irradiation in all mice but to a lesser degree in TGF-α(-/-) mice. Treatment of NIH-3T3 fibroblasts with TGF-α resulted in increases in proliferation, collagen production and LOX activity. These studies identify TGF-α as a critical mediator of radiation-induced lung injury and a novel therapeutic target in this setting. Further, these data implicate TGF-α as a mediator of collagen maturation through a TGF-β independent activation of lysyl oxidase.

Chronic Pleuropulmonary Fibrosis and Elastosis of Aged Donkeys: Similarities to Human Pleuroparenchymal Fibroelastosis

Donkey pulmonary fibrosis (DPF) is a spontaneous syndrome of aged donkeys with a high prevalence (35%). No previous detailed characterization of DPF has been performed. We sought to determine the similarities between DPF and recognized patterns of human pulmonary fibrosis. Whole lungs were collected from 32 aged donkeys at routine necropsy. Gross examination revealed pulmonary fibrosis in 19 donkeys (DPF cases), whereas 13 (control cases) had grossly normal lungs. Eighteen whole inflated ex vivo lungs (11 DPF cases, seven control cases) were imaged with high-resolution CT (HRCT) scan, whereas the remainder were sectioned and photographed. Tissue samples were collected from all lungs for histopathologic evaluation using a standardized protocol. HRCT images and histology sections underwent independent blinded review. Lung tissue was analyzed for herpes virus, fungal hyphae, mycobacteria, and dust content. Ten of 19 DPF lungs were categorized as being consistent with pleuroparenchymal fibroelastosis (PPFE) according to previously defined histologic and imaging criteria. All 10 PPFE-like lungs had marked pleural and subpleural fibrosis, predominantly within the upper lung zone, with accompanying intraalveolar fibrosis and elastosis. Asinine herpesvirus was ubiquitously expressed within control and DPF lung tissue. No other etiologic agents were identified. Many cases of DPF share key pathologic and imaging features with human PPFE, a rare interstitial pneumonia. Consequently, further study of DPF may help to elucidate the etiopathogenesis of human PPFE.

An observational study of giant cell interstitial pneumonia and lung fibrosis in hard metal lung disease

BackgroundHard metal lung disease has various pathological patterns including giant cell interstitial pneumonia (GIP) and usual interstitial pneumonia (UIP). Although the UIP pattern is considered the prominent feature in advanced...

A Case of IgG4-Related Lung Disease Presenting as Interstitial Lung Disease.

Intrathoracic involvement of immunoglobulin G4 (IgG4)-related disease has recently been reported. However, a subset of the disease presenting as interstitial lung disease is rare. Here, we report a case of a 35-year-old man with IgG4-related lung disease with manifestations similar to those of interstitial lung disease. Chest computed tomography showed diffuse ground glass opacities and rapidly progressive pleural and subpleural fibrosis in both upper lobes. Histological findings showed diffuse interstitial lymphoplasmacytic infiltration with an increased number of IgG4-positive plasma cells. Serum levels of IgG and IgG4 were also increased. The patient was diagnosed with IgG4-related lung disease, treated with anti-inflammatory agents, and showed improvement. Lung involvement of IgG4-related disease can present as interstitial lung disease and, therefore, should be differentiated when evaluating interstitial lung disease.

Two Cases of Pulmonary Sarcoidosis Presenting with Subpleural Reticular Shadows in the Lower Lobes

We herein report two unusual cases of sarcoidosis presenting with similar subpleural reticular shadows predominantly in the lower lobes with quite different pathological findings. In one patient, the lower lobe specimen contained typical epithelioid cell granulomas with subpleural and paraseptal fibrosis. However, the other patient exhibited usual interstitial pneumonia (UIP) in the lower lobe and sarcoidosis lesions in the upper lobe. Therefore, the latter patient was diagnosed with sarcoidosis complicated with UIP. Our results indicate that performing a surgical lung biopsy is necessary in order to provide appropriate management when lower lobe subpleural reticular shadows are present, even in patients with suspected sarcoidosis.