Strategies for treating idiopathic pulmonary fibrosis

Pulmonary autotaxin expression contributes to the pathogenesis of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic form of diffuse lung disease occurring mainly in older adults. Increased lysophosphatidic acid (LPA) concentrations have been reported in the alveolar space of both idiopathic pulmonary fibrosis patients and a corresponding animal model, whereas the genetic deletion or pharmacological inhibition of LPA receptor 1 attenuated the development of the modeled disease, suggesting a direct involvement of LPA in disease pathogenesis. In this report, increased concentrations of autotaxin (ATX; ENPP2), the enzyme largely responsible for extracellular LPA production, were detected in both murine and human fibrotic lungs. The genetic deletion of ATX from bronchial epithelial cells or macrophages attenuated disease severity, establishing ATX as a novel player in IPF pathogenesis. Furthermore, the pharmacological inhibition of ATX attenuated the development of the modeled disease, suggesting that ATX is a possible therapeutic target in IPF.

Tetraspanin CD151 protects against pulmonary fibrosis by maintaining epithelial integrity

RATIONALE

Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary disorder of unknown etiology with few treatment options. Although tetraspanins are involved in various diseases, their roles in fibrosis have not been determined.

OBJECTIVES

To investigate the role of tetraspanin CD151 in pulmonary fibrosis.

METHODS

CD151 knockout (KO) mice were studied by histological, biochemical, and physiological analyses and compared with wild-type mice and CD9 KO mice. Further mechanistic analyses were performed in vitro, in vivo, and on samples from patients with IPF.

MEASUREMENTS AND MAIN RESULTS

A microarray study identified an enrichment of genes involved in connective tissue disorders in the lungs of CD151 KO mice, but not in CD9 KO mice. Consistent with this, CD151 KO mice spontaneously exhibited age-related pulmonary fibrosis. Deletion of CD151 did not affect pulmonary fibroblast functions but instead degraded epithelial integrity via attenuated adhesion strength on the basement membrane; CD151-deleted alveolar epithelial cells exhibited increased α-SMA expression with activation of p-Smad2, leading to fibrotic changes in the lungs. This loss of epithelial integrity in CD151 KO lungs was further exacerbated by intratracheal bleomycin exposure, resulting in severe fibrosis with increased mortality. We also observed decreased numbers of CD151-positive alveolar epithelial cells in patients with IPF.

CONCLUSIONS

CD151 is essential for normal function of alveolar epithelial cells; loss of CD151 causes pulmonary fibrosis as a result of epithelial disintegrity. Given that CD151 may protect against fibrosis, this protein represents a novel target for the treatment of fibrotic diseases.

Idiopathic pulmonary fibrosis: clinically meaningful primary endpoints in phase 3 clinical trials

Definitive evidence of clinical efficacy in a Phase 3 trial is best shown by a beneficial impact on a clinically meaningful endpoint-that is, an endpoint that directly measures how a patient feels (symptoms), functions (the ability to perform activities in daily life), or survives. In idiopathic pulmonary fibrosis (IPF), we believe the endpoints that best meet these criteria are all-cause mortality and all-cause nonelective hospitalization. There are no validated measures of symptoms or broader constructs such as health status or functional status in IPF. A surrogate endpoint is defined as an indirect measure that is intended to substitute for a clinically meaningful endpoint. Surrogate endpoints can be appropriate outcome measures if validated. However, validation requires substantial evidence that the effect of an intervention on a clinically meaningful endpoint is reliably predicted by the effect of an intervention on the surrogate endpoint. For patients with IPF, there are currently no validated surrogate endpoints.

miR-29 inhibits bleomycin-induced pulmonary fibrosis in mice

Loss of microRNA-29 (miR-29) is known to be a mechanism of transforming growth factor-β (TGF-β)-mediated pulmonary fibrosis, but the therapeutic implication of miR-29 for pulmonary fibrosis remains unexplored. The present study investigated whether miR-29 had therapeutic potential for lung disease induced by bleomycin in mice. In addition, the signaling mechanisms that regulated miR-29 expression were investigated in vivo and in vitro. We found that miR-29 was a downstream target gene of Smad3 and negatively regulated by TGF-β/Smad signaling in fibrosis. This was evidenced by the findings that mice or pulmonary fibroblasts null for Smad3 were protected against bleomycin or TGF-β1-induced loss of miR-29 along with fibrosis in vivo and in vitro. Interestingly, overexpression of miR-29 could in turn negatively regulated TGF-β and connective tissue growth factor (CTGF) expression and Smad3 signaling. Therefore, Sleeping Beauty (SB)-mediated miR-29 gene transfer into normal and diseased lung tissues was capable of preventing and treating pulmonary fibrosis including inflammatory macrophage infiltration induced by bleomycin in mice. In conclusion, miR-29 is negatively regulated by TGF-β/Smad3 and has a therapeutic potential for pulmonary fibrosis. SB-mediated miR-29 gene therapy is a non-invasive therapeutic strategy for lung disease associated with fibrosis.

Pranlukast, a cysteinyl leukotriene type 1 receptor antagonist, attenuates the progression but not the onset of silica-induced pulmonary fibrosis in mice

BACKGROUND

Although cysteinyl leukotrienes (CysLTs) have been implicated in the etiology of acute inflammatory diseases, recent studies have suggested that they also directly stimulate fibroblasts. However, their precise role in the pathogenesis of pulmonary fibrosis is unclear.

METHODS

In this study, we evaluated the effect of both short- and long-term treatment with pranlukast, a CysLT type 1 (CysLT(1)) receptor antagonist, on silica-induced pulmonary fibrosis in mice, which is characterized by persistent progression of fibrosis in the chronic phase. Pranlukast (30 mg/kg/day) was administered orally to mice for 2 or 10 weeks after intratracheal silica instillation.

RESULTS

Pranlukast treatment for 10 weeks significantly attenuated the progression of pulmonary fibrosis, and decreased the content of CysLTs and LTB(4), which were markedly increased in the bronchoalveolar lavage fluid (BALF) and lung tissues of silica-instilled mice in the chronic phase. However, pranlukast treatment for 2 weeks neither affected the acute inflammatory response induced by silica instillation nor inhibited the onset of fibrosis. The expression of TGF-β1 and TNF-α was not affected by pranlukast treatment for either 2 or 10 weeks.

CONCLUSIONS

Pranlukast attenuates the progression of pulmonary fibrosis in the chronic phase but has no effect on the acute inflammatory response or on the onset of pulmonary fibrosis. The antifibrotic effect of pranlukast may be exhibited by antagonizing the direct profibrotic effect of CysLTs, without affecting the expression of other profibrotic cytokines such as TGF-β1 and TNF-α, and also by decreasing the production of CysLTs and LTB(4).

Loss of Shp2 in alveoli epithelia induces deregulated surfactant homeostasis, resulting in spontaneous pulmonary fibrosis

Type II alveolar epithelial (AT-II) cells produce pulmonary surfactant proteins that are essential for alveolar function. AT-II is a major target in lung injury, and ineffective repair of damaged alveolar epithelia has been postulated to cause pulmonary fibrosis. Previous studies have shown that tyrosine phosphatase Shp2 is expressed highly in the embryonic lung epithelial buds, and Shp2 activity is required for FGF-induced lung branching morphogenesis. To investigate in vivo function of pulmonary Shp2, we generated alveoli epithelia-specific Shp2-knockout (Shp2(Δ/Δ)) mice. Shp2(Δ/Δ) mice exhibit marked reduction in surfactant proteins, disorganized lamellar bodies, increased alveolar epithelial apoptosis, and interstitial pulmonary fibrosis without preceding inflammation. Mechanistically, Shp2 acts to mediate expression of thyroid transcription factor 1 (TTF1) and ATP-binding cassette subfamily A member 3 (ABCA3). Shp2 also plays a central role in mediating FGF/GAB/ERK activity, required for epithelial repair program. Together, our results identify a novel role of tyrosine phosphatase Shp2 in surfactant homeostasis, and deregulation of Shp2 triggers spontaneous pulmonary fibrosis with minimal inflammation.

Smoking and idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology with considerable morbidity and mortality. Cigarette smoking is one of the most recognized risk factors for development of IPF. Furthermore, recent work suggests that smoking may have a detrimental effect on survival of patients with IPF. The mechanism by which smoking may contribute to the pathogenesis of IPF is largely unknown. However, accumulating evidence suggests that increased oxidative stress might promote disease progression in IPF patients who are current and former smokers. In this review, potential mechanisms by which cigarette smoking affects IPF, the effects of cigarette smoking on accelerated loss of lung function in patients with IPF, key genetic studies evaluating the potential candidate genes and gene-environment (smoking) interaction, diagnosis, and treatment with emphasis on recently closed and ongoing clinical trials are presented.

Design, synthesis and antifibrotic activities of carbohydrate-modified 1-(substituted aryl)-5-trifluoromethyl-2(1H) pyridones

Pirfenidone, a pyridone compound, is an effective and novel antifibrotic agent. In this article, we describe the design, synthesis and activity evaluation of novel antifibrotic agents, 1-(substituted aryl)-5-trifluoromethyl-2(1H) pyridones modified with carbohydrate. Most of the title compounds exhibited comparable or better inhibitory activity than fluorofenidone. Notably, compound 19a demonstrated the highest cell-based inhibitory activity against NIH 3T3 (IC(50) = 0.17 mM).

Modeling pulmonary fibrosis with bleomycin

PURPOSE OF REVIEW

Idiopathic pulmonary fibrosis is a chronic pulmonary disease of unknown origin ultimately leading to death. No treatment exists yet and animal models have been employed in order to elucidate its etiopathogenesis. Here, we summarize the characteristics of the bleomycin animal model, the most commonly used model of pulmonary fibrosis, highlighting recent advances it has led us to despite its disadvantages.

RECENT FINDINGS

Repetitive intratracheal administration of bleomycin more effectively mimics the chronic aspect of pulmonary fibrosis, as well as other characteristics including the presence of hyperplastic alveolar epithelial cells. Epithelial-to-mesenchymal transition seems to be a major contributor to the lung fibroblast population. There is growing evidence that macrophages, as well as fibrocytes, are largely involved in disease progression by mediating fibroblast and myofibroblast activation. In addition, molecules involved in phospholipid homeostasis are now becoming more appealing as potential therapeutic targets.

SUMMARY

Despite its disadvantages, the bleomycin animal model remains the best available experimental tool for studying disease pathogenesis and testing of novel pharmaceutical compounds. Two such compounds currently showing some promise in clinical trials have emerged through the bleomycin model and preliminary results of basic research using this model have shown that more candidate compounds may follow in the near future.

Discovery of CC-930, an orally active anti-fibrotic JNK inhibitor

In this Letter we describe the discovery of potent, selective, and orally active aminopurine JNK inhibitors. Improving the physico-chemical properties as well as increasing the potency and selectivity of a subseries with rat plasma exposure, led to the identification of four structurally diverse inhibitors. Differentiation based on PK profiles in multiple species as well as activity in a chronic efficacy model led to the identification of 1 (CC-930) as a development candidate, which is currently in Phase II clinical trial for IPF.

Development and preclinical efficacy of novel transforming growth factor-β1 short interfering RNAs for pulmonary fibrosis

Idiopathic pulmonary fibrosis is a chronic devastating disease of unknown etiology. No therapy is currently available. A growing body of evidence supports the role of transforming growth factor (TGF)-β1 as the major player in the pathogenesis of the disease. However, attempts to control its expression and to improve the outcome of pulmonary fibrosis have been disappointing. We tested the hypothesis that TGF-β1 is the dominant factor in the acute and chronic phases of pulmonary fibrosis and developed short interfering (si)RNAs directed toward molecules implicated in the disease. This study developed novel sequences of siRNAs targeting the TGF-β1 gene and evaluated their therapeutic efficacy in two models of pulmonary fibrosis: a model induced by bleomycin and a novel model of the disease developed spontaneously in mice overexpressing the full length of human TGF-β1 in the lungs. Intrapulmonary delivery of aerosolized siRNAs of TGF-β1 with sequences common to humans and rodents significantly inhibited bleomycin-induced pulmonary fibrosis in the acute and chronic phases of the disease and in a dose-dependent manner. Aerosolized human-specific siRNA also efficiently inhibited pulmonary fibrosis, improved lung function, and prolonged survival in human TGF-β1 transgenic mice. Mice showed no off-target effects after intratracheal administration of siRNA. These results suggest the applicability of these novel siRNAs as tools for treating pulmonary fibrosis in humans.

Bayesian probit regression model for the diagnosis of pulmonary fibrosis: proof-of-principle

Background

The accurate diagnosis of idiopathic pulmonary fibrosis (IPF) is a major clinical challenge. We developed a model to diagnose IPF by applying Bayesian probit regression (BPR) modelling to gene expression profiles of whole lung tissue.

Methods

Whole lung tissue was obtained from patients with idiopathic pulmonary fibrosis (IPF) undergoing surgical lung biopsy or lung transplantation. Controls were obtained from normal organ donors. We performed cluster analyses to explore differences in our dataset. No significant difference was found between samples obtained from different lobes of the same patient. A significant difference was found between samples obtained at biopsy versus explant. Following preliminary analysis of the complete dataset, we selected three subsets for the development of diagnostic gene signatures: the first signature was developed from all IPF samples (as compared to controls); the second signature was developed from the subset of IPF samples obtained at biopsy; the third signature was developed from IPF explants. To assess the validity of each signature, we used an independent cohort of IPF and normal samples. Each signature was used to predict phenotype (IPF versus normal) in samples from the validation cohort. We compared the models' predictions to the true phenotype of each validation sample, and then calculated sensitivity, specificity and accuracy.

Results

Surprisingly, we found that all three signatures were reasonably valid predictors of diagnosis, with small differences in test sensitivity, specificity and overall accuracy.

Conclusions

This study represents the first use of BPR on whole lung tissue; previously, BPR was primarily used to develop predictive models for cancer. This also represents the first report of an independently validated IPF gene expression signature. In summary, BPR is a promising tool for the development of gene expression signatures from non-neoplastic lung tissue. In the future, BPR might be used to develop definitive diagnostic gene signatures for IPF, prognostic gene signatures for IPF or gene signatures for other non-neoplastic lung disorders such as bronchiolitis obliterans.

Platelet-derived growth factor-producing CD4+ Foxp3+ regulatory T lymphocytes promote lung fibrosis

RATIONALE

There is evidence that CD4(+) effector T lymphocytes (T eff) participate in the development of lung fibrosis, but the role of their CD4(+) regulatory T-cell (T reg) counterparts remains to be determined.

OBJECTIVES

To elucidate the contribution of T reg cells in a mouse model of lung fibrosis induced by silica (SiO(2)) particles.

METHODS

Lung T reg and T eff cells purified from SiO(2)-treated Foxp3-GFP transgenic mice were cocultured with naive lung fibroblasts or transferred to the lungs of healthy mice. DEREG mice, which express the diphtheria toxin receptor under the control of the foxp3 gene, were used to deplete T reg cells during fibrogenesis.

MEASUREMENTS AND MAIN RESULTS

CD4(+) Foxp3(+) T reg cells were persistently recruited in the lungs in response to SiO(2). T reg accumulation paralleled the establishment of pulmonary immunosuppression and fibrosis. T reg cells highly expressed platelet-derived growth factor (PDGF)-B via a TGF-β autocrine signaling pathway, directly stimulated fibroblast proliferation in vitro, and increased lung collagen deposition upon transfer in the lung of naive mice. The direct profibrotic effects of T reg cells were abolished by the inhibitor of the PDGF-B/TGF-β signaling pathway, imatinib mesylate. Neutralization of T reg-immunosuppressive activity resulted in enhanced accumulation of T eff cells and IL-4-driven pulmonary fibrogenesis, further demonstrating that T reg cells control T eff cell functions during inflammatory fibrosis.

CONCLUSIONS

Our study indicates that T reg cells contribute to lung fibrosis by stimulating fibroblasts through the secretion of PDGF-B in noninflammatory conditions and regulate detrimental T eff cell activities during inflammation-related fibrosis.

Prostaglandin E₂ protects murine lungs from bleomycin-induced pulmonary fibrosis and lung dysfunction

Prostaglandin E(2) (PGE(2)) is a lipid mediator that is produced via the metabolism of arachidonic acid by cyclooxygenase enzymes. In the lung, PGE(2) acts as an anti-inflammatory factor and plays an important role in tissue repair processes. Although several studies have examined the role of PGE(2) in the pathogenesis of pulmonary fibrosis in rodents, results have generally been conflicting, and few studies have examined the therapeutic effects of PGE(2) on the accompanying lung dysfunction. In this study, an established model of pulmonary fibrosis was used in which 10-12-wk-old male C57BL/6 mice were administered a single dose (1.0 mg/kg) of bleomycin via oropharyngeal aspiration. To test the role of prostaglandins in this model, mice were dosed, via surgically implanted minipumps, with either vehicle, PGE(2) (1.32 μg/h), or the prostacyclin analog iloprost (0.33 μg/h) beginning 7 days before or 14 days after bleomycin administration. Endpoints assessed at 7 days after bleomycin administration included proinflammatory cytokine levels and measurement of cellular infiltration into the lung. Endpoints assessed at 21 days after bleomycin administration included lung function assessment via invasive (FlexiVent) analysis, cellular infiltration, lung collagen content, and semiquantitative histological analysis of the degree of lung fibrosis (Ashcroft method). Seven days after bleomycin administration, lymphocyte numbers and chemokine C-C motif ligand 2 expression were significantly lower in PGE(2)- and iloprost-treated animals compared with vehicle-treated controls (P < 0.05). When administered 7 days before bleomycin challenge, PGE(2) also protected against the decline in lung static compliance, lung fibrosis, and collagen production that is associated with 3 wk of bleomycin exposure. However, PGE(2) had no therapeutic effect on these parameters when administered 14 days after bleomycin challenge. In summary, PGE(2) prevented the decline in lung static compliance and protected against lung fibrosis when it was administered before bleomycin challenge but had no therapeutic effect when administered after bleomycin challenge.

Blocking IL-17A promotes the resolution of pulmonary inflammation and fibrosis via TGF-beta1-dependent and -independent mechanisms

Pulmonary fibrosis is the pathologic basis for a variety of incurable human chronic lung diseases. IL-17A, a glycoprotein secreted from IL-17-producing cells, has recently been shown to be a proinflammatory cytokine involved in chronic inflammation and autoimmune disease. In this study, we report that IL-17A increased the synthesis and secretion of collagen and promoted the epithelial-mesenchymal transition in alveolar epithelial cells in a TGF-β1-dependent manner. Using in vivo fibrotic models, we found IL-17A expression to be elevated and IL-17A-associated signaling pathways to be activated in fibrotic lung tissues. Neutralization of IL-17A in vivo promoted the resolution of bleomycin-induced acute inflammation, attenuated pulmonary fibrosis, and increased survival. Additionally, IL-17A antagonism inhibited silica-induced chronic inflammation and pulmonary fibrosis. Targeting IL-17A resulted in a shift of the suppressive immune response in fibrotic lung tissue toward a Th1-type immune response, and it effectively induced autophagy, which promoted the autophagic degradation of collagen and autophagy-associated cell death. Moreover, IL-17A was found to attenuate the starvation-induced autophagy, and autophagy modulators regulated collagen degradation in the alveolar epithelial cells in a TGF-β1-independent manner. Administration of 3-methylamphetamine, an autophagy inhibitor, reversed the therapeutic efficacy of IL-17A antagonism in pulmonary fibrosis. Our studies indicate that IL-17A participates in the development and progression of pulmonary fibrosis in both TGF-β1-dependent and -independent manners and that the components of the IL-17A signaling pathway are potential therapeutic targets for the treatment of fibroproliferative lung diseases.

The clinical significance of 5% change in vital capacity in patients with idiopathic pulmonary fibrosis: extended analysis of the pirfenidone trial

BACKGROUND

Our phase III clinical trial of pirfenidone for patients with idiopathic pulmonary fibrosis (IPF) revealed the efficacy in reducing the decline of vital capacity (VC) and increasing the progression-free survival (PFS) time by pirfenidone. Recently, marginal decline in forced VC (FVC) has been reported to be associated with poor outcome in IPF. We sought to evaluate the efficacy of pirfenidone from the aspects of 5% change in VC.

METHODS

Improvement ratings based on 5% change in absolute VC, i.e., "improved (VC ≥ 5% increase)", "stable (VC < 5% change)", and "worsened (VC ≥ 5% decrease)" at month 3, 6, 9 and 12 were compared between high-dose pirfenidone (1800 mg/day; n = 108) and placebo (n = 104) groups, and (high-dose and low-dose (1200 mg/day; n = 55)) pirfenidone (n = 163) and placebo groups. PFS times with defining the disease progression as death or a ≥ 5% decline in VC were also compared between high-dose pirfenidone and placebo groups, and low-dose pirfenidone and placebo groups. Furthermore, considering "worsened" and "non-worsened (improved and stable)" of the ratings at months 3 and 12 as "positive" and "negative", respectively, and the positive and negative predictive values of the ratings were calculated in each group.

RESULTS

In the comparison of the improvement ratings, the statistically significant differences were clearly revealed at months 3, 6, 9, and 12 between pirfenidone and placebo groups. Risk reductions by pirfenidone to placebo were approximately 35% over the study period. In the comparison of the PFS times, statistically significant difference was also observed between pirfenidone and placebo groups. The positive/negative predictive values in placebo and pirfenidone groups were 86.1%/50.8% and 87.1%/71.7%, respectively. Further, the baseline characteristics of patients worsened at month 3 had generally severe impairment, and their clinical outcomes including mortality were also significantly worsened after 1 year.

CONCLUSIONS

The efficacy of pirfenidone in Japanese phase III trial was supported by the rating of 5% decline in VC, and the VC changes at month 3 may be used as a prognostic factor of IPF.

TRIAL REGISTRATION

This clinical trial was registered with the Japan Pharmaceutical Information Center (JAPIC) on September 13th, 2005 (REGISTRATION NUMBER: JAPICCTI-050121).

Epithelial transglutaminase 2 is needed for T cell interleukin-17 production and subsequent pulmonary inflammation and fibrosis in bleomycin-treated mice

Inhibition of transglutaminase 2 reduces bleomycin-induced epithelial cell release of interleukin 6 in vitro and pulmonary inflammation and fibrosis in vivo.

Pulmonary fibrosis is a potentially life-threatening disease that may be caused by overt or asymptomatic inflammatory responses. However, the precise mechanisms by which tissue injury is translated into inflammation and consequent fibrosis remain to be established. Here, we show that in a lung injury model, bleomycin induced the secretion of IL-6 by epithelial cells in a transglutaminase 2 (TG2)–dependent manner. This response represents a key step in the differentiation of IL-17–producing T cells and subsequent inflammatory amplification in the lung. The essential role of epithelial cells, but not inflammatory cells, TG2 was confirmed in bone marrow chimeras; chimeras made in TG2-deficient recipients showed reduced inflammation and fibrosis, compared with those in wild-type mice, regardless of the bone marrow cell phenotype. Epithelial TG2 thus appears to be a critical inducer of inflammation after noninfectious pulmonary injury. We further demonstrated that fibroblast-derived TG2, acting downstream of transforming growth factor-β, is also important in the effector phase of fibrogenesis. Therefore, TG2 represents an interesting potential target for therapeutic intervention.

Role of von Hippel-Lindau protein in fibroblast proliferation and fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by exaggerated fibroblast proliferation and accumulation of collagens and fibronectin. The extracellular fibronectin and collagen network is regulated by von Hippel-Lindau protein (pVHL). However, it is unknown whether pVHL contributes to pulmonary fibrosis. We found that lungs from patients with IPF expressed increased levels of pVHL in fibroblastic foci. Bleomycin treatment also induced pVHL in lung fibroblasts, but not in alveolar type II cells. Overexpression of pVHL increased lung fibroblast proliferation, protein abundance of fibronectin and collagen, and extracellular fibronectin. In addition, overexpression of pVHL induced expression of the α5 integrin subunit. Overexpression of pVHL did not alter hypoxia-inducible factor luciferase reporter activity and mRNA expression of vascular endothelial growth factor. Fibroblasts overexpressing pVHL were more sensitive to RGD peptide-mediated reduction in proliferation. Activating α5 and β1 integrin increased proliferation of fibroblasts overexpressing pVHL and those cells were more resistant to the inhibition of α5 integrin. Overexpression of pVHL also increased activation of focal adhesion kinase (FAK). Moreover, suppression of pVHL prevented TGF-β1-induced proliferation of mouse embryonic fibroblasts. Taken together, our results indicate that elevated expression of pVHL results in the aberrant fibronectin expression, activation of integrin/FAK signaling, fibroblast proliferation, and fibrosis.

A case of progressive lung fibrosis

Idiopathic pulmonary fibrosis is characterized by progressive fibrosis of the lung and poor prognosis. This is the case report of a patient with idiopathic pulmonary fibrosis that highlights many of the controversies inherent in the diagnosis and treatment of this disease.

Serum and BALF YKL-40 levels are predictors of survival in idiopathic pulmonary fibrosis

BACKGROUND

The chitinase-like protein YKL-40 is a serum biomarker in diseases with fibrosis, inflammation and tissue remodelling. Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease that is hallmarked by these processes. The aim of this study was to investigate the potential of YKL-40 as a prognostic biomarker for survival in IPF patients.

METHODS

Serum and bronchoalveolar lavage fluid (BALF) levels of YKL-40 at the time of diagnosis and a promoter polymorphism in CHI3L1, the gene encoding YKL-40, were determined in 85 IPF patients and 126 controls. The relationship between YKL-40 levels and clinical parameters was evaluated. Kaplan-Meier and Cox regression analyses were used to examine the association between YKL-40 levels and survival.

RESULTS

Serum and BALF YKL-40 levels were significantly higher in patients than in healthy controls (p < 0.001). The - 329 A/G polymorphism had a significant influence on BALF YKL-40 levels and the influence on serum YKL-40 levels showed a trend towards significance in IPF patients. IPF patients with high (> 79 ng/ml) serum or high BALF YKL-40 (> 17 ng/ml) levels had significantly shorter survival than those with low YKL-40 levels in serum or BALF. In patients with both low serum and low BALF YKL-40 levels no IPF related mortality was observed. Cox regression modelling showed that there were no confounding factors.

CONCLUSIONS

The - 329 polymorphism was associated with serum and BALF YKL-40 levels in IPF patients. High serum and BALF YKL-40 levels are associated with poor survival in IPF patients and could be useful prognostic markers for survival in IPF.

Attenuation of transforming growth factor-β-stimulated collagen production in fibroblasts by quercetin-induced heme oxygenase-1

Quercetin is a flavonoid with a wide variety of cytoprotective and modulatory functions. Heme oxygenase-1 (HO-1) is an inducible enzyme. Its reaction product, carbon monoxide (CO), confers cellular protection in a number of conditions and diseases associated with oxidative or inflammatory lung injury. Furthermore, quercetin was reported to be a potent inducer of HO-1 in several cell types. We hypothesized that quercetin suppresses the production of collagen in fibroblasts via the induction of HO-1. Here, we showed that quercetin suppresses transforming growth factor-β (TGF-β)-induced collagen production in NIH3T3 cells and in normal human lung fibroblasts. This suppressive effect of quercetin was mediated by quercetin-induced HO-1. The suppression of collagen production was conferred by the reaction product of HO-1, CO, but not by bilirubin. Furthermore, the translocation of the nuclear factor E2-related factor-2 (Nrf2), an important transcription factor that regulates the expression of HO-1 from the cytoplasm to the nuclei, was demonstrated in NIH3T3 cells by exposure to quercetin. Assessment of the signal transduction pathway involved in TGF-β signaling showed that quercetin stimulated the Smad and mitogen-activated protein kinase pathway to varying degrees. Our results demonstrate that quercetin exerts suppressive effects on the expression of collagen by the induction of HO-1. Idiopathic pulmonary fibrosis is the most lethal diffuse fibrosing lung disease, and is characterized by the deposition of extracellular matrix. Given that HO-1 is one of the important molecules emerging as a central player in diseases, quercetin or its derivatives, which effectively induced HO-1, will lead to new therapeutic strategies for promoting antifibrotic therapy in respiratory diseases.

Clinical review: idiopathic pulmonary fibrosis acute exacerbations--unravelling Ariadne's thread

Idiopathic pulmonary fibrosis (IPF) is a dreadful, chronic, and irreversibly progressive fibrosing disease leading to death in all patients affected, and IPF acute exacerbations constitute the most devastating complication during its clinical course. IPF exacerbations are subacute/acute, clinically significant deteriorations of unidentifiable cause that usually transform the slow and more or less steady disease decline to the unexpected appearance of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) ending in death. The histological picture is that of diffuse alveolar damage (DAD), which is the tissue counterpart of ARDS, upon usual interstitial pneumonia, which is the tissue equivalent of IPF. ALI/ARDS and acute interstitial pneumonia share with IPF exacerbations the tissue damage pattern of DAD. 'Treatment' with high-dose corticosteroids with or without an immunosuppressant proved ineffective and represents the coup de grace for these patients. Provision of excellent supportive care and the search for and treatment of the 'underlying cause' remain the only options. IPF exacerbations require rapid decisions about when and whether to initiate mechanical support. Admission to an intensive care unit (ICU) is a particular clinical and ethical challenge because of the extremely poor outcome. Transplantation in the ICU setting often presents insurmountable difficulties.

Activation of Toll-like receptor 9 attenuates unilateral ureteral obstruction-induced renal fibrosis

AIM

to study whether activation of TLR9 by CpG-ODN would protect against and/or reverse renal fibrosis.

METHODS

animals were treated with CpG-ODN before or after undergoing a unilateral ureteral obstruction (UUO) procedure. The interstitial fibrotic lesions of obstructed kidneys were evaluated using histology and immunohistostaining. The Th2-type cytokine profile and the expression and activity of sma and mad related protein (Smad)3, signal transducers and activators of transcription (Stat)3, extracellular regulated protein kinases (ERK), and p38 kinase were determined using RT-PCR or Western blot.

RESULTS

the obstructed kidneys displayed a significant increase in interstitial fibrosis, an infiltration of macrophages in the interstitium, and an enhanced expression of Th2 cytokines. Prophylactic application of CpG-ODN (40 microg/kg every 3 days from 2 h before UUO until the 14th day after UUO) suppressed the expression of α-smooth muscle actin, collagen deposition, and hydroxyproline in the UUO kidneys of rats. Moreover, CpG-ODN not only decreased the infiltration of macrophages but also inhibited the expression of chemokines CCL2 and CCL5, the Th2 cytokine IL-13, and the profibrogenic cytokines transforming growth factor (TGF)-β1 and plasminogen activator inhibitor (PAI)-1 in UUO kidneys of rats. Importantly, therapeutic administration of CpG-ODN (10 microg/mouse, ip, every 3 days from the 4th day to 21st day after UUO) reversed the established renal fibrosis, which was accompanied by significant reductions in the activity of ERK, Smad3, and Stat3 and an increase in the activity of p38 kinase.

CONCLUSION

the activation of TLR9 by CpG-ODN attenuates UUO-induced renal fibrosis by reversing an immunosuppressive microenvironment in the fibrotic renal tissue, which might be a novel therapeutic strategy against fibrotic renal diseases.

Pirfenidone: antifibrotic agent for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with rare incidence but high mortality, and the pathogenesis of which is still poorly understood. Available treatment options have been empirically applied but evidence-based benefits have not yet been confirmed. Pirfenidone is an antifibrotic agent that is potentially effective for IPF treatment. Preclinical studies have been reported using experimental animal models, which revealed inhibitory effects pn profibrotic and proinflammatory cytokines. Several clinical studies provided promising and reproducible effects for inhibition of IPF disease progression in different nations. The efficacy is demonstrated in patients with mild-to-moderate impairment of pulmonary functions, but not confirmed for patients with severe impairment. Major adverse events are photosensitivity and anorexia, but the treatment was generally safe and well tolerated. In this article, the usefulness and limitations of pirfenidone in IPF treatment are discussed to determine its potential for the management of IPF progression.

Non-steroid agents for idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis is a chronic progressive lung disease with poor outcome and no effective treatment to date. This is an update of a Cochrane Review first published in 2003.

OBJECTIVES

To assess the efficacy of non-steroid agents in adults with idiopathic pulmonary fibrosis.

SEARCH STRATEGY

We searched the Cochrane Airways Group Register (30 March 2010), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1, 2010), Ovid MEDLINE to March week 5, 2010, EMBASE to week 13, 2010 and PubMed to April 2010, with additional handsearching, including abstracts of international conferences. We also contacted pharmaceutical companies and researchers in the field.

SELECTION CRITERIA

Randomised studies comparing non-steroid drugs with placebo or steroids in adults with idiopathic pulmonary fibrosis.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality, extracted data and assessed risk of bias. We contacted pharmaceutical companies to obtain missing information, if any. We combined survival outcomes using Peto odds ratios or hazard ratios (HR).

MAIN RESULTS

Fifteen trials involving 10 different drugs were included. Two trials enrolling 1156 patients compared interferon gamma-1beta with placebo: interferon gamma-1beta did not significantly improve survival (HR 0.88, 95% CI 0.47 to 1.64; P = 0.68). Four trials involving 1155 patients compared pirfenidone with placebo. Three trials, conducted in 1046 patients, provided data on progression-free survival: pirfenidone significantly reduced the risk of disease progression by 30% (HR 0.70, 95% CI 0.56 to 0.88, P = 0.002). Data on the effect of pirfenidone on pulmonary function could only be assessed for two studies analysing 314 patients. Forced vital capacity or vital capacity was significantly improved by pirfenidone (mean difference 0.08 L, 95% CI 0.03 to 0.13, P = 0.0006).

AUTHORS' CONCLUSIONS

Based on available data, partly still unpublished, pirfenidone appears to improve progression-free survival and, to a lesser extent, pulmonary function in patients with idiopathic pulmonary fibrosis. More data are needed on overall survival and quality of life on treatment. From the studies in this review, interferon gamma-1beta has not been shown to affect survival. Other agents evaluated in single studies either failed to provide evidence for a benefit or need to be assessed in larger randomised controlled trials.

Clinical use of biomarkers of survival in pulmonary fibrosis

Background

Biologic predictors or biomarkers of survival in pulmonary fibrosis with a worse prognosis, more specifically in idiopathic pulmonary fibrosis would help the clinician in deciding whether or not to treat since treatment carries a potential risk for adverse events. These decisions are made easier if accurate and objective measurements of the patients' clinical status can predict the risk of progression to death.

Method

A literature review is given on different biomarkers of survival in interstitial lung disease, mainly in IPF, since this disease has the worst prognosis.

Conclusion

Serum biomarkers, and markers measured by medical imaging as HRCT, pertechnegas, DTPA en FDG-PET are not ready for clinical use to predict mortality in different forms of ILD. A baseline FVC, a change of FVC of more than 10%, and change in 6MWD are clinically helpful predictors of survival.

Investigational approaches to therapies for idiopathic pulmonary fibrosis

IMPORTANCE OF THE FIELD

In fibrosing diseases, scar tissue begins to replace normal tissue, causing tissue dysfunction. For instance, in lung fibrosis, foci of what resembles scar tissue form in the lungs, impeding the ability of patients to breathe. These conditions represent a significant source of morbidity and mortality. More than 150,000 people in the USA have some form of fibrotic lung disease, and the 5-year mortality rate for these diseases can be as high as 80%. Despite this large unmet medical need, there are no FDA-approved therapies. Although our understanding of the causes and the biology of fibrosing diseases remains relatively poor, we have made impressive advances in identifying the major cell populations and many biochemical mediators that can drive this process. As a result, novel therapeutics are being developed based upon these discoveries.

AREAS COVERED IN THIS REVIEW

This review examines the experimental therapies currently under investigation as of late 2009 for a major class of lung fibrosis called idiopathic pulmonary fibrosis (IPF).

WHAT THE READER WILL GAIN

The reader will gain an overview of current experimental therapies for IPF.

TAKE HOME MESSAGE

With the recent approval of Pirfenidone in Japan for use in IPF, and a rich pipeline of experimental therapies in various stages of clinical development, the future looks bright for new treatment options.

MicroRNAs and the regulation of fibrosis

MicroRNAs (miRNAs) are small, noncoding RNAs of 18-25 nucleotides that are generally believed to either block the translation or induce the degradation of target mRNA. miRNAs have been shown to play fundamental roles in diverse biological and pathological processes, including cell proliferation, differentiation, apoptosis and carcinogenesis. Fibrosis results from an imbalance in the turnover of extracellular matrix molecules and is a highly debilitating process that can eventually lead to organ dysfunction. A growing body of evidence suggests that miRNAs participate in the fibrotic process in a number of organs including the heart, kidney, liver and lung. In this review, we summarize our current understanding of the role of miRNAs in the development of tissue fibrosis and their potential as novel drug targets.

Advances in the management of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a common form of interstitial lung disease and usually results in progressive respiratory insufficiency and death. Steady progress has been made in understanding the pathogenesis of IPF and multiple clinical trials are ongoing, but effective therapy remains elusive.