Pretreatment of aged mice with retinoic acid supports alveolar regeneration via upregulation of reciprocal PDGFA signalling

OBJECTIVES

Idiopathic pulmonary fibrosis (IPF) primarily affects the aged population and is characterised by failure of alveolar regeneration, leading to loss of alveolar type 1 (AT1) cells. Aged mouse models of lung repair have demonstrated that regeneration fails with increased age. Mouse and rat lung repair models have shown retinoic acid (RA) treatment can restore alveolar regeneration. Herein, we seek to determine the signalling mechanisms that become activated on RA treatment prior to injury, which support alveolar differentiation.

DESIGN

Partial pneumonectomy lung injury model and next-generation sequencing of sorted cell populations were used to uncover molecular targets regulating alveolar repair. In vitro organoids generated from epithelial cells of mouse or patient with IPF co-cultured with young, aged or RA-pretreated murine fibroblasts were used to test potential targets.

MAIN OUTCOME MEASUREMENTS

Known alveolar epithelial cell differentiation markers, including HOPX and AGER for AT1 cells, were used to assess outcome of treatments.

RESULTS

Gene expression analysis of sorted fibroblasts and epithelial cells isolated from lungs of young, aged and RA-pretreated aged mice predicted increased platelet-derived growth factor subunit A (PDGFA) signalling that coincided with regeneration and alveolar epithelial differentiation. Addition of PDGFA induced AT1 and AT2 differentiation in both mouse and human IPF lung organoids generated with aged fibroblasts, and PDGFA monoclonal antibody blocked AT1 cell differentiation in organoids generated with young murine fibroblasts.

CONCLUSIONS

Our data support the concept that RA indirectly induces reciprocal PDGFA signalling, which activates regenerative fibroblasts that support alveolar epithelial cell differentiation and repair, providing a potential therapeutic strategy to influence the pathogenesis of IPF.

LEM domain-containing protein 3 antagonizes TGFβ-SMAD2/3 signaling in a stiffness-dependent manner in both the nucleus and cytosol

Transforming growth factor-β (TGFβ) signaling through SMAD2/3 is an important driver of pathological fibrosis in multiple organ systems. TGFβ signaling and extracellular matrix (ECM) stiffness form an unvirtuous pathological circuit in which matrix stiffness drives activation of latent TGFβ, and TGFβ signaling then drives cellular stress and ECM synthesis. Moreover, ECM stiffness also appears to sensitize cells to exogenously activated TGFβ through unknown mechanisms. Here, using human fibroblasts, we explored the effect of ECM stiffness on a putative inner nuclear membrane protein, LEM domain-containing protein 3 (LEMD3), which is physically connected to the cell's actin cytoskeleton and inhibits TGFβ signaling. We showed that LEMD3-SMAD2/3 interactions are inversely correlated with ECM stiffness and TGFβ-driven luciferase activity and that LEMD3 expression is correlated with the mechanical response of the TGFβ-driven luciferase reporter. We found that actin polymerization but not cellular stress or LEMD3-nuclear-cytoplasmic couplings were necessary for LEMD3-SMAD2/3 interactions. Intriguingly, LEMD3 and SMAD2/3 frequently interacted in the cytosol, and we discovered LEMD3 was proteolytically cleaved into protein fragments. We confirmed that a consensus C-terminal LEMD3 fragment binds SMAD2/3 in a stiffness-dependent manner throughout the cell and is sufficient for antagonizing SMAD2/3 signaling. Using human lung biopsies, we observed that these nuclear and cytosolic interactions are also present in tissue and found that fibrotic tissues exhibit locally diminished and cytoplasmically shifted LEMD3-SMAD2/3 interactions, as noted in vitro Our work reveals novel LEMD3 biology and stiffness-dependent regulation of TGFβ by LEMD3, providing a novel target to antagonize pathological TGFβ signaling.

Función pulmonar, capacidad funcional y calidad de vida en pacientes con fibrosis pulmonar idiopática. Revisión de la literatura

Introducción. La fibrosis pulmonar idiopática (FPI) es un tipo de enfermedad intersticial, crónica y progresiva que suele manifestarse con disnea y deterioro progresivo de la tolerancia al ejercicio y a las actividades de la vida diaria, llegando a comprometer el nivel psicológico y la interacción social.Objetivos. Seleccionar y sintetizar información acerca de la respuesta de la capacidad funcional, la función pulmonar y la calidad de vida relacionada con la salud en pacientes con FPI luego de ser sometidos a un programa de rehabilitación pulmonar.Materiales y métodos. Revisión de la literatura desde 2000 a 2016, utilizando las bases de datos PubMed y ScienceDirect.Resultados. Se seleccionaron 10 ensayos clínicos randomizados. Se observó tendencia al aumento significativo en la distancia recorrida en test de marcha de 6 minutos. Respecto a la función pulmonar, los resultados variaron entre las poblaciones estudiadas. En la calidad de vida relacionada con la salud se observó mejora en los pacientes sometidos a rehabilitación, pero los niveles de disnea mostraron resultados discordantes.Conclusión. Se evidenciaron beneficios en términos de capacidad funcional y calidad de vida relacionada con la salud, pero los estudios siguen siendo escasos y con poblaciones pequeñas; los efectos de los programas de rehabilitación no se mantienen a los 6 meses de evaluación post-entrenamiento.

Effectiveness and Safety of Chinese Medicine for Idiopathic Pulmonary Fibrosis: A Systematic Review and Meta-Analysis

OBJECTIVE

To evaluate the effectiveness and safety of Chinese medicine (CM) for Idiopathic pulmonary fibrosis (IPF) patients.

METHODS

To screened relevant articles, PubMed, Cochrane Library, Excerpta Medica Datase (EMBASE), China National Knowledge Infrastructure (CNKI), Chinese VIP Information (VIP), Wanfang Database and Chinese Biomedical Database (CBM) were searched in English or Chinese until December 2015 for randomized controlled trials, which compared CM treatment (CM group) with Western medicine or placebo (control group) on IPF. The outcome measures included acute exacerbation, pulmonary function, the St George's respiratory questionnaire (SGRQ) scores, 6-minute walk test (6MWT) distance, adverse events and mortality.

RESULTS

This meta-analysis included 25 randomized controlled trials involving 1,471 patients. Compared with the control group, CM group was superiori in reducing the risk of exacerbation [relative risk (RR)=0.40, 95% CI 0.22 to 0.72, P<0.05], improving in forced expiratory volume in one second (FEV1) [standard mean difference (SMD)=0.62, 95% CI 0.40 to 0.84, P<0.01] and diffusion capacity for carbon monoxide (DLCO, SMD=0.40, 95% CI 0.22 to 0.58, P<0.01), but there was no significant difference in vital capacity (VC, SMD=0.10, 95% CI-0.12 to 0.31, P>0.05). This meta-analysis also revealed that CM therapy significantly decreased the SGRQ score (SMD=-0.60, 95% CI-1.14 to-0.05, P<0.05) and improved 6MWT distance (SMD=0.59, 95% CI 0.34 to 0.84, P<0.01), compared with the control group. Meanwhile, CM therapy was associated with a low incidence of adverse effects (RR=0.19, 95% CI 0.08 to 0.43, P<0.01). However, there was no significant difference in mortality (RR=0.24, 95% CI 0.05 to 1.10, P>0.05) between CM and control groups.

CONCLUSIONS

The pooled outcomes suggest that CM treatment appears benefit in reducing the risk of exacerbation, improving lung function and decreasing the incidence of adverse effects and enhancing the quality of life. However, the outcomes were limited because of the low quality of the included studies. More rigorous clinic trials need to be carried out to provide sufficient and accurate evidence in the future.

Exploring Animal Models That Resemble Idiopathic Pulmonary Fibrosis

Large multicenter clinical trials have led to two recently approved drugs for patients with idiopathic pulmonary fibrosis (IPF); yet, both of these therapies only slow disease progression and do not provide a definitive cure. Traditionally, preclinical trials have utilized mouse models of bleomycin (BLM)-induced pulmonary fibrosis—though several limitations prevent direct translation to human IPF. Spontaneous pulmonary fibrosis occurs in other animal species, including dogs, horses, donkeys, and cats. While the fibrotic lungs of these animals share many characteristics with lungs of patients with IPF, current veterinary classifications of fibrotic lung disease are not entirely equivalent. Additional studies that profile these examples of spontaneous fibroses in animals for similarities to human IPF should prove useful for both human and animal investigators. In the meantime, studies of BLM-induced fibrosis in aged male mice remain the most clinically relevant model for preclinical study for human IPF. Addressing issues such as time course of treatment, animal size and characteristics, clinically irrelevant treatment endpoints, and reproducibility of therapeutic outcomes will improve the current status of preclinical studies. Elucidating the mechanisms responsible for the development of fibrosis and disrepair associated with aging through a collaborative approach between researchers will promote the development of models that more accurately represent the realm of interstitial lung diseases in humans.

Increased deposition of glycosaminoglycans and altered structure of heparan sulfate in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant deposition of extracellular matrix (ECM) constituents, including glycosaminoglycans (GAGs), that may play a role in remodelling processes by influencing critical mediators such as growth factors. We hypothesize that GAGs may be altered in IPF and that this contribute to create a pro-fibrotic environment. The aim of this study was therefore to examine the fine structure of heparan sulfate (HS), chondroitin/dermatan sulfate (CS/DS) and hyaluronan (HA) in lung samples from IPF patients and from control subjects. GAGs in lung samples from severe IPF patients and donor lungs were analyzed with HPLC. HS was assessed by immunohistochemistry and collagen was quantified as hydroxyproline content. The total amount of HS, CS/DS and HA was increased in IPF lungs but there was no significant difference in the total collagen content. We found a relative increase in total sulfation of HS due to increment of 2-O, 6-O and N-sulfation and a higher proportion of sulfation in CS/DS. Highly sulfated HS was located in the border zone between denser areas and more normal looking alveolar parenchyma in basement membranes of blood vessels and airways, that were immuno-positive for perlecan, as well as on the cell surface of spindle-shaped cells in the alveolar interstitium. These findings show for the first time that both the amount and structure of glycosaminoglycans are altered in IPF. These changes may contribute to the tissue remodelling in IPF by altering growth factor retention and activity, creating a pro-fibrotic ECM landscape.

Interstitial pneumonia induced by bleomycin treatment is exacerbated in Angptl2-deficient mice

Angiopoietin-like protein 2 (ANGPTL2) is a chronic inflammatory mediator that, when deregulated, is associated with various pathologies. However, little is known about its activity in lung. To assess a possible lung function, we generated a rabbit monoclonal antibody that specifically recognizes mouse ANGPTL2 and then evaluated protein expression in mouse lung tissue. We observed abundant ANGPTL2 expression in both alveolar epithelial type I and type II cells and in resident alveolar macrophages under normal conditions. To assess ANGPTL2 function, we compared lung phenotypes in Angptl2 knockout (KO) and wild-type mice but observed no overt changes. We then generated a bleomycin-induced interstitial pneumonia model using wild-type and Angptl2 KO mice. Bleomycin-treated wild-type mice showed specifically upregulated ANGPTL2 expression in areas of severe fibrosing interstitial pneumonia, while Angptl2 KO mice developed more severe lung fibrosis than did comparably treated wild-type mice. Lung fibrosis seen following bone marrow transplant was comparable in wild-type or Angptl2 KO mice treated with bleomycin, suggesting that Angptl2 loss in myeloid cells does not underlie fibrotic phenotypes. We conclude that Angptl2 deficiency in lung epithelial cells and resident alveolar macrophages causes severe lung fibrosis seen following bleomycin treatment, suggesting that ANGPTL2 derived from these cell types plays a protective role against fibrosis in lung.

Usefulness of Cyclophosphamide Pulse Therapy in Interstitial Lung Diseases

BACKGROUND

Interstitial lung diseases (ILDs) are a group of disorders characterised by progressive lung function decline. Stabilisation of lung function under intermittent i.v. cyclophosphamide was shown in patients suffering from systemic sclerosis, yet data in ILD patients are scarce.

OBJECTIVES

To retrospectively evaluate the usefulness of cyclophosphamide pulse therapy in ILD.

METHODS

We retrospectively analysed all patients who received i.v. cyclophosphamide in our centre from 2002 to 2012. Lung function, survival status, and bronchoalveolar lavage cytology were recorded during a follow-up period of 18 months.

RESULTS

Twenty-six patients with idiopathic pulmonary fibrosis, 6 with lymphocytic interstitial pneumonia (LIP), 8 with idiopathic non-specific interstitial pneumonia (NSIP), 7 with rheumatoid arthritis-associated ILD, and 7 with perinuclear anti-neutrophil cytoplasmic antibody-positive ILD (pANCA+ ILD) were included. Patients with LIP and NSIP had the best survival outcome, those with pANCA+ ILD the worst. In the total cohort, we found a significantly higher total lung capacity decline in the year before treatment compared to the year after treatment.

CONCLUSIONS

This retrospective analysis of cyclophosphamide treatment shows a stabilisation of lung function in most patients with fibrotic ILDs, yet prospective studies in clearly defined diagnoses are urgently needed.

Effect of grapefruit juice and food on the pharmacokinetics of pirfenidone in healthy Chinese volunteers: a diet-drug interaction study

1. Ingestion of grapefruit juice and food could be factors affecting the pharmacokinetics of pirfenidone, a promising drug for treatment of idiopathic pulmonary fibrosis. 2. A randomized, open-label, three-period crossover study was carried out in 12 healthy Chinese male volunteers who were randomized to one of the three treatments: pirfenidone tablets (0.4 g) were orally administered to fasted or fed subjects, or with grapefruit juice. The washout period was 7 d. 3. Significantly reduced maximum plasma concentration (Cmax, 5.0 5 ± 1.39 versus 10.9 0 ± 2.94 mg·L(- 1)), modestly affected area-under-the-plasma concentration-time curve (AUC) from time zero to 12 h post dosing (AUC0-12 h, 21.8 9 ± 6.47 versus 26.1 6 ± 7.32 mg·h·L(- 1)) and delayed time to reach Cmax (Tmax) were observed in fed group compared with fasted group. Similar effects on Cmax (5.8 2 ± 1.23 versus 10.9 0 ± 2.94 mg·L(- 1)) and AUC0-12 h (modest but not statistically significant, 24.4 4 ± 7.40 versus 26.1 6 ± 7.32 mg·h·L(- 1)) were observed for grapefruit juice compared to fasted subjects. 4. Co-administration of pirfenidone with grapefruit juice resulted in modestly reduced overall oral absorption and significantly reduced peak concentrations compared to fasting, which was similar to effect of food ingestion. No adverse events were observed in the study, but relatively dramatic reduction of peak concentrations should raise concerns for clinical efficacy and safety.

Increased FGF1-FGFRc expression in idiopathic pulmonary fibrosis

Background

Recent clinical studies show that tyrosine kinase inhibitors slow the rate of lung function decline and decrease the number of acute exacerbations in patients with Idiopathic Pulmonary Fibrosis (IPF). However, in the murine bleomycin model of fibrosis, not all tyrosine kinase signaling is detrimental. Exogenous ligands Fibroblast Growth Factor (FGF) 7 and 10 improve murine lung repair and increase survival after injury via tyrosine kinase FGF receptor 2b-signaling. Therefore, the level and location of FGF/FGFR expression as well as the exogenous effect of the most highly expressed FGFR2b ligand, FGF1, was analyzed on human lung fibroblasts.

Methods

FGF ligand and receptor expression was evaluated in donor and IPF whole lung homogenates using western blotting and qPCR. Immunohistochemistry for FGF1 and FGFR1/2/3/4 were performed on human lung tissue. Lastly, the effects of FGF1, a potent, multi-FGFR ligand, were studied on primary cultures of IPF and non-IPF donor fibroblasts. Western blots for pro-fibrotic markers, proliferation, FACS for apoptosis, transwell assays and MetaMorph analyses on cell cultures were performed.

Results

Whole lung homogenate analyses revealed decreased FGFR b-isoform expression, and an increase in FGFR c-isoform expression. Of the FGFR2b-ligands, FGF1 was the most significantly increased in IPF patients; downstream targets of FGF-signaling, p-ERK1/2 and p-AKT were also increased. Immunohistochemistry revealed FGF1 co-localization within basal cell sheets, myofibroblast foci, and Surfactant protein-C positive alveolar epithelial type-II cells as well as co-localization with FGFR1, FGFR2, FGFR3, FGFR4 and myofibroblasts expressing the migratory marker Fascin. Both alone and in the presence of heparin, FGF1 led to increased MAPK-signaling in primary lung fibroblasts. While smooth muscle actin was unchanged, heparin + FGF1 decreased collagen production in IPF fibroblasts. In addition, FGF1 + heparin increased apoptosis and cell migration. The FGFR inhibitor (PD173074) attenuated these effects.

Conclusions

Strong expression of FGF1/FGFRs in pathogenic regions of IPF suggest that aberrant FGF1-FGFR signaling is increased in IPF patients and may contribute to the pathogenesis of lung fibrosis by supporting fibroblast migration and increased MAPK-signaling.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0242-2) contains supplementary material, which is available to authorized users.

Pharmacological treatment of idiopathic pulmonary fibrosis - preclinical and clinical studies of pirfenidone, nintedanib, and N-acetylcysteine

Three recent clinical trials on the pharmacologic treatment of idiopathic pulmonary fibrosis (IPF) mark a new chapter in the management of patients suffering from this very severe fibrotic lung disease. This review article summarizes the published investigations on the preclinical studies of three novel IPF drugs, namely pirfenidone, nintedanib, and N-acetylcysteine (NAC). In addition, the study protocols, differences, and the main findings in the recent clinical trials of these pharmacological treatments are reviewed. The strategy for drug development and the timeline from the discovery to the clinical use have been very different in these regimens. Pirfenidone was discovered in 1976 but only recently received approval in most countries, and even now its exact mechanism of action is unknown. On the contrary, nintedanib (BIBF1120) was identified in large drug screening tests as a very specific inhibitor of certain tyrosine kinases, but no published data on preclinical tests existed until 2014. NAC, a mucolytic drug with an antioxidant mechanism of action was claimed to possess distinct antifibrotic properties in several experimental models but proved to be ineffective in a recent randomized placebo-controlled trial. At present, no curative treatment is available for IPF. A better understanding of the molecular mechanisms of IPF as well as relevant preclinical tests including animal models and in vitro experiments on human lung cells are needed to promote the development of therapeutic drugs.

Review of the British Thoracic Society Winter Meeting 2013, 4-6 December, London, UK

This article reviews the British Thoracic Society Winter Meeting 2013, the annual scientific meeting attended by over 2000 delegates and representing the depth and breadth of UK respiratory medicine. This year's meeting from 4 to 6 December in London featured cutting-edge research alongside keynote symposia from international experts in respiratory science, epidemiology and clinical trials. This article reviews the key symposia and selected abstract sessions from the 2013 meeting.

Expression and mechanism of BRP-39 in bleomycin-induced pulmonary fibrosis in rat

The purpose of the study was to explore the effects of breast regression protein 39 (BRP-39) in bleomycin-induced pulmonary fibrosis and its mechanism in pulmonary fibrosis by studying change in BRP-39 to provide a novel direction for the treatment of idiopathic pulmonary fibrosis. SPF grade male C57BL/6 rats were randomly divided into three groups, including bleomycin group, bleomycin+ BRP-39 recombinant protein group and control group. HE and Masson staining were applied to test the change in lung tissue after being treated by BRP-39, ELISA was applied to test the expression of TGF-β1 in different groups, and Western blot was used to test the expression of BRP-39 in rat lung tissue. Expression of BRP-39 increased, the fibrosis was obvious, and lung tissue collagen increased in bleomycin-induced pulmonary fibrosis in rat lung tissue. Increasing BRP-39 protein level and intratracheal bleomycin medication to establish pulmonary fibrosis model can aggravate pulmonary fibrosis. Along with the increase in BRP-39 protein level, TGF-β1 expression level also increased in lung tissue. Western blot results showed the expression of BRP-39, and TGF-β1 had the same trend in different groups. BRP-39 has effects in bleomycin-induced rat pulmonary fibrosis. Change in BRP-39 can affect the process of bleomycin-induced pulmonary fibrosis. The mechanism of BRP-3 in pulmonary fibrosis may work by regulating TGF-β1.