Clinical review: Idiopathic pulmonary fibrosis—Past, present and future

Anti-pulmonary fibrosis activity analysis of methyl rosmarinate obtained from Salvia castanea Diels f. tomentosa Stib. using a scalable process

Pulmonary fibrosis is a progressive, irreversible, chronic interstitial lung disease associated with high morbidity and mortality rates. Current clinical drugs, while effective, do not reverse or cure pulmonary fibrosis and have major side effects, there are urgent needs to develop new anti-pulmonary fibrosis medicine, and corresponding industrially scalable process as well. Salvia castanea Diels f. tomentosa Stib., a unique herb in Nyingchi, Xizang, China, is a variant of S. castanea. and its main active ingredient is rosmarinic acid (RA), which can be used to prepare methyl rosmarinate (MR) with greater drug potential. This study presented an industrially scalable process for the preparation of MR, which includes steps such as polyamide resin chromatography, crystallization and esterification, using S. castanea Diels f. tomentosa Stib. as the starting material and the structure of the product was verified by NMR technology. The anti-pulmonary fibrosis effects of MR were further investigated in vivo and in vitro. Results showed that this process can easily obtain high-purity RA and MR, and MR attenuated bleomycin-induced pulmonary fibrosis in mice. In vitro, MR could effectively inhibit TGF-β1-induced proliferation and migration of mouse fibroblasts L929 cells, promote cell apoptosis, and decrease extracellular matrix accumulation thereby suppressing progressive pulmonary fibrosis. The anti-fibrosis effect of MR was stronger than that of the prodrug RA. Further study confirmed that MR could retard pulmonary fibrosis by down-regulating the phosphorylation of the TGF-β1/Smad and MAPK signaling pathways. These results suggest that MR has potential therapeutic implications for pulmonary fibrosis, and the establishment of this scalable preparation technology ensures the development of MR as a new anti-pulmonary fibrosis medicine.

Chronic pulmonary fibrosis alters the functioning of the respiratory neural network

Some patients with idiopathic pulmonary fibrosis present impaired ventilatory variables characterised by low forced vital capacity values associated with an increase in respiratory rate and a decrease in tidal volume which could be related to the increased pulmonary stiffness. The lung stiffness observed in pulmonary fibrosis may also have an effect on the functioning of the brainstem respiratory neural network, which could ultimately reinforce or accentuate ventilatory alterations. To this end, we sought to uncover the consequences of pulmonary fibrosis on ventilatory variables and how the modification of pulmonary rigidity could influence the functioning of the respiratory neuronal network. In a mouse model of pulmonary fibrosis obtained by 6 repeated intratracheal instillations of bleomycin (BLM), we first observed an increase in minute ventilation characterised by an increase in respiratory rate and tidal volume, a desaturation and a decrease in lung compliance. The changes in these ventilatory variables were correlated with the severity of the lung injury. The impact of lung fibrosis was also evaluated on the functioning of the medullary areas involved in the elaboration of the central respiratory drive. Thus, BLM-induced pulmonary fibrosis led to a change in the long-term activity of the medullary neuronal respiratory network, especially at the level of the nucleus of the solitary tract, the first central relay of the peripheral afferents, and the Pre-Bötzinger complex, the inspiratory rhythm generator. Our results showed that pulmonary fibrosis induced modifications not only of pulmonary architecture but also of central control of the respiratory neural network.

Comparative Study of Ectopic Lymphoid Aggregates in Sheep and Murine Models of Bleomycin-Induced Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease characterized by excessive deposition of extracellular matrix in the interstitial lung parenchyma, often manifested by dyspnea and progressive loss of lung function. The role of inflammation in the pathogenesis of IPF is not well understood. This study evaluated the histopathological and inflammatory components of bleomycin-induced pulmonary fibrosis in mouse and sheep models, in terms of their ability to translate to the human IPF. Merino sheep (n = 8) were bronchoscopically administered with two bleomycin infusions, two weeks apart, into a caudal lung segment, with a saline (control) administered into a caudal segment in the opposite lung. Balb/c mice were twice intranasally instilled, one week apart, with either bleomycin (n = 7); or saline (control, n = 7). Lung samples were taken for the histopathological assessment 28 days in sheep and 21 days in mice after the first bleomycin administration. We observed tertiary lymphoid aggregates, in the fibrotic lung parenchyma of sheep, but not in mouse lung tissues exposed to bleomycin. B-cell and T-cell infiltration significantly increased in sheep lung tissues compared to mouse lung tissues due to bleomycin injury. Statistical analysis showed that the fibrotic score, fibrotic fraction, and tissue fraction significantly increased in sheep lung tissues compared to murine lung tissues. The presence of tertiary lymphoid aggregates in the lung parenchyma and increased infiltration of T-cells and B-cells, in the sheep model, may be useful for the future study of the underlying inflammatory disease mechanisms in the lung parenchyma of IPF patients.

Plumbagin attenuates Bleomycin-induced lung fibrosis in mice

Background

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease with limited treatment options. Plumbagin (PL) is an herbal extract with diverse pharmacological effects that have been recently used to treat various types of cancer. This study aims to explore the anti-fibrotic effect of PL and possible underlying mechanisms in IPF.

Methods

We used a bleomycin-induced experimental mouse model of lung fibrosis to assess the potential anti-fibrotic effect of PL. Histological analysis of lung tissue samples by H&E and Masson’s trichrome staining and hydroxyproline assay was performed to evaluate the fibrotic alterations. ELISA and real-time quantitative PCR were conducted to determine the amount of tumor necrosis factor-alpha (TNFα), tumor growth factor-beta (TGF-β), connective tissue growth factor (CTGF), and endothelin-1 (ET-1).

Results

Bleomycin exposure induced lung fibrosis, which was indicated by inflammation, collagen deposition, and structural damage. PL remarkably prevented bleomycin-induced lung fibrosis. Furthermore, PL significantly inhibited TNF-α and TGF-β production. PL also diminished the upregulated expression of CTGF and ET-1 induced by bleomycin.

Conclusion

Overall, our findings suggest PL as an anti-fibrotic agent acting via down-regulation of TGF-β/CTGF or ET-1 axis, as well as TNF-α, to improve lung fibrosis.

Fine crackles on chest auscultation in the early diagnosis of idiopathic pulmonary fibrosis: a prospective cohort study

Introduction

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease (ILD) with a poor prognosis. Early diagnosis and treatment of IPF may increase lifespan and preserve quality of life. Chest CT is the best test to diagnose IPF, but it is expensive and impractical as a screening test. Fine crackles on chest auscultation may be the only best to screen for IPF.

Methods

We prospectively assessed the presence and type of crackles on chest auscultation in all patients referred to the ILD Clinic at the Kingston Health Sciences Center in Ontario, Canada. Clinicians with varying levels of experience recorded the presence of fine crackles, coarse crackles or both independently and unaware of the final diagnosis. We applied multinomial logistic regression to adjust for ILD severity and factors that could affect the identification of crackles.

Results

We evaluated 290 patients referred to the ILD Clinic. On initial presentation, 93% of patients with IPF and 73% of patients with non-IPF ILD had fine crackles on auscultation. In patients with IPF, fine crackles were more common than cough (86%), dyspnoea (80%), low diffusing capacity (87%), total lung capacity (57%) and forced vital capacity (50%). There was 90% observer agreement in identifying fine crackles at a subsequent visit. In multiple regression analysis, the identification of fine crackles was unaffected by lung function, symptoms, emphysema, chronic obstructive pulmonary disease, obesity or clinician experience (p>0.05).

Conclusions

Fine crackles on chest auscultation are a sensitive and robust screening tool that can lead to early diagnosis and treatment of patients with IPF.

Protein Kinase C δ (PKCδ) Attenuates Bleomycin Induced Pulmonary Fibrosis via Inhibiting NF-κB Signaling Pathway

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and lethal interstitial lung disease characterized by consistent pulmonary inflammation. Although protein kinase C delta (PKCδ) is involved in broad scope cellular response, the role of PKCδ in IPF is complicated and has not been fully defined yet. Here, we reported that PKCδ deficiency (PKCδ^-/-) aggravated bleomycin (BLM)-induced pulmonary fibrosis and inflammation. Upon challenge with BLM, the pulmonary capillary permeability, immune cell infiltration, inflammatory cytokine production, and collagen deposition were enhanced in PKCδ^-/- mice compared to that in PKCδ^+/+ mice. In response to poly(I:C) stimulation, PKCδ deficient macrophages displayed an increased production of IL-1β, IL-6, TNF-α, and IL-33, which were associated with an enhanced NF-κB activation. Furthermore, we found that PKCδ could directly bind to and phosphorylate A20, an inhibitory protein of NF-κB signal. These results suggested that PKCδ may inhibit the NF-κB signaling pathway via enhancing the stability and activity of A20, which in turn attenuates pulmonary fibrosis, suggesting that PKCδ is a promising target for treating pulmonary fibrosis.

BML-111 suppresses TGF-β1-induced lung fibroblast activation in vitro and decreases experimental pulmonary fibrosis in vivo

Pulmonary fibrosis is an aggressive end‑stage disease. Transforming growth factor‑β1 (TGF‑β1) mediates lung fibroblast activation and is essential for the progress of pulmonary fibrosis. BML‑111, a lipoxinA4 (LXA4) receptor (ALX) agonist, has been reported to possess anti‑fibrotic properties. The present study aimed to elucidate whether BML‑111 inhibits TGF‑β1‑induced mouse embryo lung fibroblast (NIH3T3 cell line) activation in vitro and bleomycin (BLM)‑induced pulmonary fibrosis in vivo. In vitro experiments demonstrated that BML‑111 treatment inhibits TGF‑β1‑induced NIH3T3 cell viability and the expression of smooth muscle α actin (α‑SMA), fibronectin and total collagen. Furthermore, this suppressive effect was associated with mothers against decapentaplegic homolog (Smad)2/3, extracellular signal‑regulated kinase (ERK) and Akt phosphorylation interference. In vivo experiments revealed that BML‑111 treatment markedly improved survival rate and ameliorated the destruction of lung tissue structure. It also reduced interleukin‑1β (IL‑1β), tumor necrosis factor‑α (TNF‑α) and TGF‑β1 expression in the BLM intratracheal mouse model. In addition, the expression ofα‑SMA and extracellular matrix (ECM) deposition (total collagen, hydroxyproline and fibronectin) were also suppressed following BML‑111 treatment. However, BOC‑2, an antagonist of ALX, partially weakened the effects of BML‑111. In conclusion, these results indicated that BML‑111 inhibits TGF‑β1‑induced fibroblasts activation and alleviates BLM‑induced pulmonary fibrosis. Therefore, BML‑111 may be used as a potential therapeutic agent for pulmonary fibrosis treatment.

A Chinese Traditional Therapy for Bleomycin-Induced Pulmonary Fibrosis in Mice

Pulmonary fibrosis is a chronic and fatal disease of lung tissue with high incidence and mortality in the world. The exploration of effective treatment for pulmonary fibrosis remains an urgent challenge. In our study, Qingfei Xieding was investigated as a novel Chinese traditional patent medicine against pulmonary fibrosis. A pulmonary fibrosis mouse model was constructed by injecting with bleomycin sulfate. Following Qingfei Xieding administration, lung samples were collected to assess pulmonary phenotype changes by analyzing lung coefficient, wet/dry, and histopathologic section. Levels of nitric oxide (NO), hydroxyproline (HYP), malondialdehyde (MDA), and total antioxidant capacity were measured to evaluate the degree of oxidation. A single-cell gel electrophoresis (SCGE) assay was used to evaluate bleomycin-induced DNA damage. Western blotting and real-time quantitative PCR were performed to determine the abundance of inducible nitric oxide synthase (iNOS), connective tissue growth factor (CTGF), alpha smooth muscle actin (α-SMA), and fibronectin (FN). In the present study, Qingfei Xieding administration significantly attenuated bleomycin-induced pulmonary fibrosis in mice by reducing lung coefficient, wet/dry, NO, HYP, and MDA as well as the expression of iNOS, CTGF, α-SMA, FN, and DNA damage. The results indicated that Qingfei Xieding is effective to resist oxidative damage and histopathologic lesion, serving a protection role on bleomycin-induced pulmonary fibrosis.

Chitosan-alginate nano-carrier for transdermal delivery of pirfenidone in idiopathic pulmonary fibrosis

Pirfenidone (PFD) is one of the pyridine family components with anti-inflammatory, antifibrotic effects and US FDA approved for the treatment of idiopathic pulmonary fibrosis (IPF). Presently, PFD is administered orally and this has setbacks. Hence, it is important to eliminate the pharmacotherapeutic limitations of PFD. This research was carried out to study the possibility of transdermal delivery of PFD using chitosan-sodium alginate nanogel carriers. In order to synthesize chitosan-sodium alginate nanoparticles loaded with PFD, the pre-gelation method was used. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FTIR) analyses were used for the characterization. Drug encapsulation and release manner were studied using UV spectroscopy. Ex vivo permeation examinations were performed using Franz diffusion cell and fluorescence microscopy. The results showed that nanoparticles having spherical morphology and size in the range of 80 nm were obtained. In vitro drug release profile represents sustained release during 24 h, while 50% and 94% are the loading capacity and efficiency, respectively. Also, the skin penetration of PFD loaded in nanoparticles was significantly increased as compared to PFD solution. The obtained results showed that synthesized nanoparticles can be considered as promising carriers for PFD delivery.

The clinical effectiveness and cost-effectiveness of treatments for idiopathic pulmonary fibrosis: a systematic review and economic evaluation

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a life-limiting lung disease that generally affects people over 60 years old. The main symptoms are shortness of breath and cough, and as the disease progresses there is a considerable impact on day-to-day life. Few treatments are currently available.

OBJECTIVES

To conduct a systematic review of clinical effectiveness and an analysis of cost-effectiveness of treatments for IPF based on an economic model informed by systematic reviews of cost-effectiveness and quality of life.

DATA SOURCES

Eleven electronic bibliographic databases, including MEDLINE, EMBASE, Web of Science, and The Cochrane Library and the Centre for Reviews and Dissemination databases, were searched from database inception to July 2013. Reference lists of relevant publications were also checked and experts consulted.

METHODS

Two reviewers independently screened references for the systematic reviews, extracted and checked data from the included studies and appraised their risk of bias. An advisory group was consulted about the choice of interventions until consensus was reached about eligibility. A narrative review with meta-analysis was undertaken, and a network meta-analysis (NMA) was performed. A decision-analytic Markov model was developed to estimate cost-effectiveness of pharmacological treatments for IPF. Parameter values were obtained from NMA and systematic reviews. Univariate and probabilistic sensitivity analyses were undertaken. The model perspective is NHS and Personal Social Services, and discount rate is 3.5% for costs and health benefits.

RESULTS

Fourteen studies were included in the review of clinical effectiveness, of which one evaluated azathioprine, three N-acetylcysteine (NAC) (alone or in combination), four pirfenidone, one BIBF 1120, one sildenafil, one thalidomide, two pulmonary rehabilitation, and one a disease management programme. Study quality was generally good, with a low risk of bias. The current evidence suggests that some treatments appear to be clinically effective. The model base-case results show increased survival for five pharmacological treatments, compared with best supportive care, at increased cost. General recommendations cannot be made of their cost-effectiveness owing to limitations in the evidence base.

LIMITATIONS

Few direct comparisons of treatments were identified. An indirect comparison through a NMA was performed; however, caution is recommended in the interpretation of these results. In relation to the economic model, there is an assumption that pharmacological treatments have a constant effect on the relative rate of per cent predicted forced vital capacity decline.

CONCLUSIONS

Few interventions have any statistically significant effect on IPF and a lack of studies on palliative care approaches was identified. Research is required into the effects of symptom control interventions, in particular pulmonary rehabilitation and thalidomide. Other research priorities include a well-conducted randomised controlled trial on inhaled NAC therapy and an updated evidence synthesis once the results of ongoing studies are reported.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42012002116.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

17(R)-resolvin D1 ameliorates bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is a destructive inflammatory disease with limited therapeutic options. Inflammation plays an integral role in the development of pulmonary fibrosis. Unresolved inflammatory responses can lead to substantial tissue injury, chronic inflammation, and fibrosis. The resolvins are a family of endogenous ω‐3 fatty acid derived‐lipid mediators of inflammation resolution. Resolvin D1 (RvD1) displays potent anti‐inflammatory, pro‐resolving activity, without causing immunosuppression. Its epimer, 17(R)‐resolvin D1 (17(R)‐RvD1), exhibits equivalent functionality to RvD1. In addition, 17(R)‐RvD1 is resistant to rapid inactivation by eicosanoid oxidoreductases. In the present study, we tested the hypothesis that 17(R)‐RvD1 can provide a therapeutic benefit in IPF by reducing inflammation and pulmonary fibrosis, while leaving the normal immune response intact. Mice were exposed to bleomycin (BLM) via micro‐osmotic pump to induce pulmonary fibrosis, and were then treated with 17(R)‐RvD1 or vehicle by intraperitoneal injection. Administration of 17(R)‐RvD1 from the start of BLM treatment attenuated neutrophil alveolar infiltration, lung collagen content, and Interleukin‐1β (IL‐1β), transforming growth factor‐β1 (TGF‐β1), connective tissue growth factor (CTGF), and type I collagen mRNA expression, along with subsequent reduction in histologically detectable fibrosis. The 17(R)‐RvD1‐induced infiltration of inflammatory cells was inhibited by an antagonist of lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2). The administration of 17(R)‐RvD1 at the later fibrotic stage also improved the lung failure. These results suggest that 17(R)‐RvD1 attenuates pulmonary fibrosis by promoting the resolution of neutrophilic inflammation and also provides pulmonary restoration. These data highlight the therapeutic potential of 17(R)‐RvD1 in the management of this intractable disease.

Immunohistochemical and morphometric evaluation of COX 1 and COX-2 in the remodeled lung in idiopathic pulmonary fibrosis and systemic sclerosis

OBJECTIVE:

To study the expression of COX-1 and COX-2 in the remodeled lung in systemic sclerosis (SSc) and idiopathic pulmonary fibrosis (IPF) patients, correlating that expression with patient survival.

METHODS:

We examined open lung biopsy specimens from 24 SSc patients and 30 IPF patients, using normal lung tissue as a control. The histological patterns included fibrotic nonspecific interstitial pneumonia (NSIP) in SSc patients and usual interstitial pneumonia (UIP) in IPF patients. We used immunohistochemistry and histomorphometry to evaluate the expression of COX-1 and COX-2 in alveolar septa, vessels, and bronchioles. We then correlated that expression with pulmonary function test results and evaluated its impact on patient survival.

RESULTS:

The expression of COX-1 and COX-2 in alveolar septa was significantly higher in IPF-UIP and SSc-NSIP lung tissue than in the control tissue. No difference was found between IPF-UIP and SSc-NSIP tissue regarding COX-1 and COX-2 expression. Multivariate analysis based on the Cox regression model showed that the factors associated with a low risk of death were younger age, high DLCO/alveolar volume, IPF, and high COX-1 expression in alveolar septa, whereas those associated with a high risk of death were advanced age, low DLCO/alveolar volume, SSc (with NSIP), and low COX-1 expression in alveolar septa.

CONCLUSIONS:

Our findings suggest that strategies aimed at preventing low COX-1 synthesis will have a greater impact on SSc, whereas those aimed at preventing high COX-2 synthesis will have a greater impact on IPF. However, prospective randomized clinical trials are needed in order to confirm that.

Pulmonary antifibrotic mechanisms aspirin-triggered lipoxin A(4) synthetic analog

No successful therapies are available for pulmonary fibrosis, indicating the need for new treatments. Lipoxins and their 15-epimers, aspirin-triggered lipoxins (ATL), present potent antiinflammatory and proresolution effects (Martins et al., J Immunol 2009;182:5374-5381). We show that ATLa, an ATL synthetic analog, therapeutically reversed a well-established pulmonary fibrotic process induced by bleomycin (BLM) in mice. We investigated the mechanisms involved in its effect and found that systemic treatment with ATLa 1 week after BLM instillation considerably reversed the inflammatory response, total collagen and collagen type 1 deposition, vascular endothelial growth factor, and transforming growth factor (TGF)-β expression in the lung and restored surfactant protein C expression levels. ATLa also inhibited BLM-induced apoptosis and cellular accumulation in bronchoalveolar lavage fluid and in the lung parenchyma as evaluated by light microscopy and flow cytometry (Ly6G(+), F4/80(+), CD11c(+), CD4(+), and B220(+) cells) assays. Moreover, ATLa inhibited the lung production of IL-1β, IL-17, TNF-α, and TGF-β induced by BLM-challenged mice. ATLa restored the balance of inducible nitric oxide synthase-positive and arginase-positive cells in the lungs, suggesting a prevalence of M2 versus M1 macrophages. Together, these effects improved pulmonary mechanics because ATLa treatment brought to normal levels lung resistance and elastance, which were clearly altered at 7 days after BLM challenge. Our findings support ATLa as a promising therapeutic agent to treat lung fibrosis.

Are mast cells instrumental for fibrotic diseases?

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disorder of unknown etiology characterized by accumulation of lung fibroblasts and extracellular matrix deposition, ultimately leading to compromised tissue architecture and lung function capacity. IPF has a heterogeneous clinical course; however the median survival after diagnosis is only 3–5 years. The pharmaceutical and biotechnology industry has made many attempts to find effective treatments for IPF, but the disease has so far defied all attempts at therapeutic intervention. Clinical trial failures may arise for many reasons, including disease heterogeneity, lack of readily measurable clinical end points other than overall survival, and, perhaps most of all, a lack of understanding of the underlying molecular mechanisms of the progression of IPF. The precise link between inflammation and fibrosis remains unclear, but it appears that immune cells can promote fibrosis by releasing fibrogenic factors. So far, however, therapeutic approaches targeting macrophages, neutrophils, or lymphocytes have failed to alter disease pathogenesis. A new cell to garner research interest in fibrosis is the mast cell. Increased numbers of mast cells have long been known to be present in pulmonary fibrosis and clinically correlations between mast cells and fibrosis have been reported. More recent data suggests that mast cells may contribute to the fibrotic process by stimulating fibroblasts resident in the lung, thus driving the pathogenesis of the disease. In this review, we will discuss the mast cell and its physiological role in tissue repair and remodeling, as well as its pathological role in fibrotic diseases such as IPF, where the process of tissue repair and remodeling is thought to be dysregulated.

Mast cells: a pivotal role in pulmonary fibrosis

Pulmonary fibrosis is characterized by an inflammatory response that includes macrophages, neutrophils, lymphocytes, and mast cells. The purpose of this study was to evaluate whether mast cells play a role in initiating pulmonary fibrosis. Pulmonary fibrosis was induced with bleomycin in mast-cell-deficient WBB6F1-W/W(v) (MCD) mice and their congenic controls (WBB6F1-(+)/(+)). Mast cell deficiency protected against bleomycin-induced pulmonary fibrosis, but protection was reversed with the re-introduction of mast cells to the lungs of MCD mice. Two mast cell mediators were identified as fibrogenic: histamine and renin, via angiotensin (ANG II). Both human and rat lung fibroblasts express the histamine H1 and ANG II AT1 receptor subtypes and when activated, they promote proliferation, transforming growth factor β1 secretion, and collagen synthesis. Mast cells appear to be critical to pulmonary fibrosis. Therapeutic blockade of mast cell degranulation and/or histamine and ANG II receptors should attenuate pulmonary fibrosis.

hTERT mutations associated with idiopathic pulmonary fibrosis affect telomerase activity, telomere length, and cell growth by distinct mechanisms

Telomerase is a ribonucleoprotein reverse transcriptase (RT) that synthesizes specific DNA repeats, or telomeric DNA, at the ends of chromosomes. Telomerase is minimally composed of a protein subunit, TERT, and an RNA component, TR. Aberrant telomerase activity has been associated with most human cancers and several premature aging diseases, such as idiopathic pulmonary fibrosis (IPF), a chronic, progressive, and fatal lung disease characterized by alveolar epithelial cell damage and fibrosis. Our study focuses on three hTERT mutations that were identified in a subset of patients with IPF, in which these patients also exhibited shorter telomeres compared with age-matched controls. We characterized how three IPF-associated hTERT mutations, V144M, R865C, and R865H, affected telomerase function both in vitro and in human cells. We demonstrated that the R865 residue is crucial for repeat addition processivity and thus telomere synthesis in telomerase-positive 293 cells and telomerase-negative BJ cells, consistent with its location in the hTERT nucleotide-binding motif. In contrast, while the V144M mutant did not exhibit any biochemical defects, this mutant was unable to elongate telomeres in human cells. As a result, our studies have identified hTERT V144 and R865 as two critical residues required for proper telomerase function in cells. Together, this may explain how inherited hTERT mutations can lead to shortened telomeres in patients with IPF and, thus, provide further insight into the role of naturally occurring telomerase mutations in the pathophysiology of certain age-related disease states.

Novel Positron Emission Tomography/Computed Tomography of Diffuse Parenchymal Lung Disease Combining a Labeled Somatostatin Receptor Analogue and 2-Deoxy-2 [18F] Fluoro-D-Glucose

We prospectively investigated the potential of positron emission tomography (PET) using the somatostatin receptor (SSTR) analogue 68Ga-DOTATATE and 2-deoxy-2[18F]fluoro-D-glucose (18F-FDG) in diffuse parenchymal lung disease (DPLD). Twenty-six patients (mean age 68.9 ± 11.0 years) with DPLD were recruited for 68Ga-DOTATATE and 18F-FDG combined PET/high-resolution computed tomography (HRCT) studies. Ten patients had idiopathic pulmonary fibrosis (IPF), 12 patients had nonspecific interstitial pneumonia (NSIP), and 4 patients had other forms of DPLD. Using PET, the pulmonary tracer uptake (maximum standardized uptake value [SUVmax]) was calculated. The distribution of PET tracer was compared to the distribution of lung parenchymal changes on HRCT. All patients demonstrated increased pulmonary PET signal with 68Ga-DOTATATE and 18F-FDG. The distribution of parenchymal uptake was similar, with both tracers corresponding to the distribution of HRCT changes. The mean SUVmax was 2.2 ± 0.7 for 68Ga-DOTATATE and 2.8 ± 1.0 ( t-test, p = .018) for 18F-FDG. The mean 68Ga-DOTATATE SUVmax in IPF patients was 2.5 ± 0.9, whereas it was 2.0 ± 0.7 ( p = .235) in NSIP patients. The correlation between 68Ga-DOTATATE SUVmax and gas transfer (transfer factor of the lung for carbon monoxide [TLCO]) was r = .34 ( p = .127) and r = .49 ( p = .028) between 18F-FDG SUVmax and TLCO. We provide noninvasive in vivo evidence in humans showing that SSTRs may be detected in the lungs of patients with DPLD in a similar distribution to sites of increased uptake of 18F-FDG on PET.

Minimally invasive imaging method based on second harmonic generation and multiphoton excitation fluorescence in translational respiratory research

For translational respiratory research including in the development of clinical diagnostic tools, a minimally invasive imaging method, which can provide both cellular and extracellular structural details with sufficient specificity, sensitivity and spatial resolution, is particularly useful. Multiphoton microscopy causes excitation of endogenously fluorescent macromolecular systems and induces highly specific second harmonic generation signals from non-centrosymmetric macromolecules such as fibrillar collagens. Both these signals can be captured simultaneously to provide spatially resolved 3D structural organization of extracellular matrix as well as the cellular morphologies in their native states. Besides briefly discussing the fundamentals of multiphoton excitation fluorescence and harmonic generation signals and the instrumentation details, this review focuses on the specific applications of these imaging modalities in lung structural imaging, particularly morphological features of alveolar structures, visualizing and quantifying extracellular matrix remodelling accompanying emphysematous destructions as well as the IPF, detecting lung cancers and the potential use in the tissue engineering applications.

Luteolin ameliorates experimental lung fibrosis both in vivo and in vitro: implications for therapy of lung fibrosis

Lonicera japonica (Caprifoliaceae) has been known as an anti-inflammatory herb in traditional Chinese medicine for thousands of years and is used constantly for upper respiratory tract infections. Luteolin, an active flavonoid compound isolated from Lonicera japonica, has a spectrum of biological activities, especially with antioxidative and anti-inflammatory properties. However, whether luteolin has a direct inhibitory effect on lung fibrosis has not been established. In this study, we examined the effects of luteolin on lung fibrosis both in vivo and in vitro. We found that oral administration of luteolin (10 mg/kg) efficiently suppressed the neutrophil infiltration as well as TNF-α and IL-6 elevation in the bronchoalveolar lavage fluid in bleomycin-instilled C57BL/6J mice. Luteolin also alleviated collagen deposition, TGF-β1 expression, and lung fibrosis upon bleomycin instillation. A similar tendency was observed in both early and delayed luteolin-treated groups. Next, our in vitro studies showed that luteolin inhibited TGF-β1-induced α-SMA, type I collagen, and vimentin expression in primary cultured mouse lung fibroblasts. Moreover, luteolin significantly blocked TGF-β1-mediated epithelial marker (E-cadherin) downregulation and mesenchymal cell markers (fibronectin and vimentin) upregulation, as well as retaining epithelial morphology in human alveolar epithelial-derived A549 cells. Additionally, luteolin could attenuate TGF-β1-induced Smad3 phosphorylation in both lung fibroblasts and A549 cells. These findings suggest that luteolin has a potent antifibrotic activity; this effect was mediated, at least in part, by inhibition of lung inflammation and suppression of myofibroblast differentiation as well as epithelial-to-mesenchymal transition.

NOX4/NADPH oxidase expression is increased in pulmonary fibroblasts from patients with idiopathic pulmonary fibrosis and mediates TGFbeta1-induced fibroblast differentiation into myofibroblasts

BACKGROUND

Persistence of myofibroblasts is believed to contribute to the development of fibrosis in idiopathic pulmonary fibrosis (IPF). Transforming growth factor beta1 (TGFbeta1) irreversibly converts fibroblasts into pathological myofibroblasts, which express smooth muscle alpha-actin (alpha-SMA) and produce extracellular matrix proteins, such as procollagen I (alpha1). Reactive oxygen species produced by NADPH oxidases (NOXs) have been shown to regulate cell differentiation. It was hypothesised that NOX could be expressed in parenchymal pulmonary fibroblasts and could mediate TGFbeta1-stimulated conversion of fibroblasts into myofibroblasts.

METHODS

Fibroblasts were cultured from the lung of nine controls and eight patients with IPF. NOX4, alpha-SMA and procollagen I (alpha1) mRNA and protein expression, reactive oxygen species production and Smad2/3 phosphorylation were quantified, in the absence and in the presence of incubation with TGFbeta1. Migration of platelet-derived growth factor (PDGF)-induced fibroblasts was also assessed.

RESULTS

It was found that (1) NOX4 mRNA and protein expression was upregulated in pulmonary fibroblasts from patients with IPF and correlated with mRNA expression of alpha-SMA and procollagen I (alpha1) mRNA; (2) TGFbeta1 upregulated NOX4, alpha-SMA and procollagen I (alpha1) expression in control and IPF fibroblasts; (3) the change in alpha-SMA and procollagen I (alpha1) expression in response to TGFbeta1 was inhibited by antioxidants and by a NOX4 small interfering RNA (siRNA); (4) NOX4 modulated alpha-SMA and procollagen I (alpha1) expression by controlling activation of Smad2/3; and (5) NOX4 modulated PDGF-induced fibroblast migration.

CONCLUSION

NOX4 is critical for modulation of the pulmonary myofibroblast phenotype in IPF, probably by modulating the response to TGFbeta1 and PDGF.

Genomic phenotype of non-cultured pulmonary fibroblasts in idiopathic pulmonary fibrosis

Activated fibroblasts are the central effector cells of the progressive fibrotic process in idiopathic pulmonary fibrosis (IPF). Characterizing the genomic phenotype of isolated fibroblasts is essential to understanding IPF pathogenesis. Comparing the genomic phenotype of non-cultured pulmonary fibroblasts from advanced IPF patients' and normal lungs revealed novel genes, biological processes and concomitant pathways previously unreported in IPF fibroblasts. We demonstrate altered expression in proteasomal constituents, ubiquitination-mediators, Wnt, apoptosis and vitamin metabolic pathways and cell cycle regulators, suggestive of loss of cellular homeostasis. Specifically, FBXO32, CXCL14, BDKRB1 and NMNAT1 were up-regulated, while RARA and CDKN2D were down-regulated. Paradoxically, pro-apoptotic inducers TNFSF10, BAX and CASP6 were also found to be increased. This comprehensive description of altered gene expression in isolated IPF fibroblasts underscores the complex biological processes characteristic of IPF and may provide a foundation for future research into this devastating disease.

Semiquantitative analysis of surgical biopsies of distinct lung lobes of patients with usual interstitial pneumonia/idiopathic pulmonary fibrosis

OBJECTIVE

To evaluate the differences between surgical biopsies of distinct lung lobes in terms of the histopathological features of usual interstitial pneumonia, using a semiquantitative score.

METHODS

We selected all of the patients diagnosed with idiopathic pulmonary fibrosis and submitted to surgical biopsy in two distinct lobes between 1995 and 2005 at the Hospital São Paulo and other hospitals operated by the Federal University of São Paulo. In the histological evaluation of the specimens, we used a semiquantitative method based on previous studies, assigning a score to each of the biopsied sites.

RESULTS

In this sample of patients, we found no statistically significant differences that would alter the stage of the disease, based on the score used. This finding was independent of the biopsy site (middle lobe or lingular segment).

CONCLUSIONS

No significant histological differences were found between the lung lobes studied. The definitive histological diagnosis of usual interstitial pneumonia did not alter the stage of the disease.

A novel application for Cocoacrisp protein as a biomarker for experimental pulmonary fibrosis

Pulmonary fibrosis is a debilitating disease affecting up to 2 million people worldwide, with a median survival rate of only 3 years after diagnosis. The aim of this study was to evaluate a potential protein biomarker (Cocoacrisp, CC) to identify the onset of pulmonary fibrosis. A model of fibrosis was induced via intratracheal instillation of bleomycin, and samples were collected during the early phase of the disease. Immunohistochemical identification of CC was carried out in lung tissue from the bleomycin model. Quantification by image analysis showed CC levels were doubled (p <0.0003), after a single bleomycin dose, but not after double instillation. Microscopic analysis revealed that CC signal was primarily detected on the alveolar surface. The secretion of the novel protein CC during the early stages of bleomycin-induced injury may have the potential to be utilized as a clinical biomarker for the early stages of fibrosis, particularly as it may be detectable in bronchoalveolar lavage fluid.

ATLa, an aspirin-triggered lipoxin A4 synthetic analog, prevents the inflammatory and fibrotic effects of bleomycin-induced pulmonary fibrosis

Despite an increase in the knowledge of mechanisms and mediators involved in pulmonary fibrosis, there are no successful therapeutics available. Lipoxins (LX) and their 15-epimers, aspirin-triggered LX (ATL), are endogenously produced eicosanoids with potent anti-inflammatory and proresolution effects. To date, few studies have been performed regarding their effect on pulmonary fibrosis. In the present study, using C57BL/6 mice, we report that bleomycin (BLM)-induced lung fibrosis was prevented by the concomitant treatment with an ATL synthetic analog, ATLa, which reduced inflammation and matrix deposition. ATLa inhibited BLM-induced leukocyte accumulation and alveolar collapse as evaluated by histology and morphometrical analysis. Moreover, Sirius red staining and lung hydroxyproline content showed an increased collagen deposition in mice receiving BLM alone that was decreased upon treatment with the analog. These effects resulted in benefits to pulmonary mechanics, as ATLa brought to normal levels both lung resistance and compliance. Furthermore, the analog improved mouse survival, suggesting an important role for the LX pathway in the control of disease establishment and progression. One possible mechanism by which ATLa restrained fibrosis was suggested by the finding that BLM-induced myofibroblast accumulation/differentiation in the lung parenchyma was also reduced by both simultaneous and posttreatment with the analog (alpha-actin immunohistochemistry). Interestingly, ATLa posttreatment (4 days after BLM) showed similar inhibitory effects on inflammation and matrix deposition, besides the TGF-beta level reduction in the lung, reinforcing an antifibrotic effect. In conclusion, our findings show that LX and ATL can be considered as promising therapeutic approaches to lung fibrotic diseases.

Idiopathic pulmonary fibrosis and diffuse parenchymal lung disease: implications from initial experience with 18F-FDG PET/CT

The purpose of this study was to evaluate integrated (18)F-FDG PET/CT in patients with idiopathic pulmonary fibrosis (IPF) and diffuse parenchymal lung disease (DPLD).

METHODS

Thirty-six consecutive patients (31 men and 5 women; mean age +/- SD, 68.7 +/- 9.4 y) with IPF (n = 18) or other forms of DPLD (n = 18) were recruited for PET/CT and high-resolution CT (HRCT), acquired on the same instrument. The maximal pulmonary (18)F-FDG metabolism was measured as a standardized uptake value (SUV(max)). At this site, the predominant lung parenchyma HRCT pattern was defined for each patient: ground-glass or reticulation/honeycombing. Patients underwent a global health assessment and pulmonary function tests.

RESULTS

Raised pulmonary (18)F-FDG metabolism in 36 of 36 patients was observed. The parenchymal pattern on HRCT at the site of maximal (18)F-FDG metabolism was predominantly ground-glass (7/36), reticulation/honeycombing (26/36), and mixed (3/36). The mean SUV(max) in patients with ground-glass and mixed patterns was 2.0 +/- 0.4, and in reticulation/honeycombing it was 3.0 +/- 1.0 (Mann-Whitney U test, P = 0.007). The mean SUV(max) in patients with IPF was 2.9 +/- 1.1, and in other DPLD it was 2.7 +/- 0.9 (Mann-Whitney U test, P = 0.862). The mean mediastinal lymph node SUV(max) (2.7 +/- 1.3) correlated with pulmonary SUV(max) (r = 0.63, P < 0.001). Pulmonary (18)F-FDG uptake correlated with the global health score (r = 0.50, P = 0.004), forced vital capacity (r = 0.41, P = 0.014), and transfer factor (r = 0.37, P = 0.042).

CONCLUSION

Increased pulmonary (18)F-FDG metabolism in all patients with IPF and other forms of DPLD was observed. Pulmonary (18)F-FDG uptake predicts measurements of health and lung physiology in these patients. (18)F-FDG metabolism was higher when the site of maximal uptake corresponded to areas of reticulation/honeycomb on HRCT than to those with ground-glass patterns.

Oxidative stress alters syndecan-1 distribution in lungs with pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterized by severe, progressive fibrosis. Roles for inflammation and oxidative stress have recently been demonstrated, but despite advances in understanding the pathogenesis, there are still no effective therapies for IPF. This study investigates how extracellular superoxide dismutase (EC-SOD), a syndecan-binding antioxidant enzyme, inhibits inflammation and lung fibrosis. We hypothesize that EC-SOD protects the lung from oxidant damage by preventing syndecan fragmentation/shedding. Wild-type or EC-SOD-null mice were exposed to an intratracheal instillation of asbestos or bleomycin. Western blot was used to detect syndecans in the bronchoalveolar lavage fluid and lung. Human lung samples (normal and IPF) were also analyzed. Immunohistochemistry for syndecan-1 and EC-SOD was performed on human and mouse lungs. In vitro, alveolar epithelial cells were exposed to oxidative stress and EC-SOD. Cell supernatants were analyzed for shed syndecan-1 by Western blot. Syndecan-1 ectodomain was assessed in wound healing and neutrophil chemotaxis. Increases in human syndecan-1 are detected in lung homogenates and lavage fluid of IPF lungs. Syndecan-1 is also significantly elevated in the lavage fluid of EC-SOD-null mice after asbestos and bleomycin exposure. On IHC, syndecan-1 staining increases within fibrotic areas of human and mouse lungs. In vitro, EC-SOD inhibits oxidant-induced loss of syndecan-1 from A549 cells. Shed and exogenous syndecan-1 ectodomain induce neutrophil chemotaxis, inhibit alveolar epithelial wound healing, and promote fibrogenesis. Oxidative shedding of syndecan-1 is an underlying cause of neutrophil chemotaxis and aberrant wound healing that may contribute to pulmonary fibrosis.

Therapies for interstitial lung disease: past, present and future

As our understanding of the pathobiology and natural history of the various forms of interstitial lung disease (ILD) has evolved, so have our approaches to treating this heterogeneous group of lung disorders. The earliest pharmacologic agents used to treat various forms of ILD were corticosteroids, and corticosteroids are currently the mainstay of therapy for many forms of ILD. However, it has become clear that corticosteroids and other anti-inflammatory agents lack efficacy for many forms of ILD, such as idiopathic pulmonary fibrosis (IPF), and newer therapies that are in clinical trials target the fibrogenic process and/or secondary pulmonary hypertension (PH) that is present in various forms of fibrotic lung disease. Novel therapies, such as the use of biologic agents (antibodies and cell cycle inhibitors) or stem cell therapies will undoubtedly evolve as new research is performed and clinical trials are undertaken. Lung transplantation remains an option for advanced lung disease that is progressive and unresponsive to non-surgical therapies.

Loosening the bonds of restrictive lung disease

Find out about this common but lesser-known respiratory condition and how to help your patient.

Interstitial Lung Diseases

Several noninfectious nonneoplastic interstitial lung diseases (ILDs) have been recognized in dogs and cats. Overall, these ILDs are poorly characterized in dogs and cats, although awareness of the conditions based on descriptions of clinical case series may be increasing. Lung biopsy remains crucial to the diagnosis, characterization, and classification of ILDs. Histopathologic findings can help to guide clinicians in selecting appropriate therapy and providing an accurate prognosis to pet owners. Only with definitive recognition of these pulmonary conditions can our knowledge of the clinical course and response to therapy be improved.