Pierre-Simon Bellaye

Inhibition of HSP27 blocks fibrosis development and EMT features by promoting Snail degradation

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by myofibroblast proliferation. Transition of epithelial/mesothelial cells into myofibroblasts [epithelial‐to‐mesenchymal transition (EMT)] occurs under the influence of transforming growth factor (TGF)‐β1, with Snail being a major transcription factor. We study here the role of the heat‐shock protein HSP27 in fibrogenesis and EMT. In vitro, we have up‐ and down‐modulated HSP27 expression in mesothelial and epithelial cell lines and studied the expression of different EMT markers induced by TGF‐β1. In vivo, we inhibited HSP27 with the antisense oligonucleotide OGX‐427 (in phase II clinical trials as anticancer agent) in our rat subpleural/pulmonary fibrosis models. We demonstrate that HSP27 is strongly expressed during the fibrotic process in patients with IPF and in different in vivo models. We showed that HSP27 binds to and stabilizes Snail and consequently induces EMT. Conversely, HSP27 knockdown leads to Snail proteasomal degradation, thus inhibiting TGF‐β1‐induced EMT. Inhibition of HSP27 with OGX‐427 efficiently blocks EMT and fibrosis development. Controls in vivo were an empty adenovirus that did not induce fibrosis and a control antisense oligonucleotide. The present work opens the possibility of a new therapeutic use for HSP27 inhibitors against IPF, for which there is no conclusively effective treatment.—Wettstein, G., Bellaye, P.‐S., Kolb, M., Hammann, A., Crestani, B., Soler, P., Marchal‐Somme, J., Hazoume, A., Gauldie, J., Gunther, A., Micheau, O., Gleave, M., Camus, P., Garrido, C., Bonniaud, P. Inhibition of HSP27 blocks fibrosis development and EMT features by promoting Snail degradation. FASEB J. 27, 1549–1560 (2013). www.fasebj.org

Stretch-induced Activation of Transforming Growth Factor-β1 in Pulmonary Fibrosis.

RATIONALE Recent findings suggesting transforming growth factor (TGF)-β1 activation by mechanical stimuli in vitro raised the question of whether this phenomenon was relevant in vivo in the context of pulmonary fibrosis. OBJECTIVES To explore the effect of mechanical stress on TGF-β1 activation and its signaling pathway in rat and human fibrotic lung tissue using a novel ex vivo model. METHODS Rat lung fibrosis was induced using transient gene expression of active TGF-β1. Lungs were harvested at Day 14 or 21 and submitted to various stimuli in a tissue bath equipped with a force transducer and servo-controlled arm. MEASUREMENTS AND MAIN RESULTS Fibrotic lung strips responded to tensile force by releasing active TGF-β1 from latent stores with subsequent increase in tissue phospho-Smad2/3. In contrast, measurable active TGF-β1 and phospho-Smad2/3 were not induced by mechanical stress in nonfibrotic lungs. Protease inhibition did not affect the release of active TGF-β1. A TGF-β1 receptor inhibitor, Rho-associated protein kinase inhibitor, and αv integrin inhibitor all attenuated mechanical stretch-induced phospho-Smad2/3 in fibrotic lung strips. Furthermore, the induction of phospho-Smad2/3 was enhanced in whole fibrotic rat lungs undergoing ventilation pressure challenge compared with control lungs. Last, tissue slices from human lung with usual interstitial pneumonia submitted to mechanical force showed an increase in TGF-β1 activation and induction of phospho-Smad2/3 in contrast with human nonfibrotic lungs. CONCLUSIONS Mechanical tissue stretch contributes to the development of pulmonary fibrosis via mechanotransduced activation of TGF-β1 in rodent and human pulmonary fibrosis.

Heat shock proteins in fibrosis and wound healing: Good or evil?

Heat shock proteins (HSPs) are key regulators of cell homeostasis, and their cytoprotective role has been largely investigated in the last few decades. However, an increasing amount of evidence highlights their deleterious effects on several human pathologies, including cancer, in which they promote tumor cell survival, proliferation and drug resistance. Therefore, HSPs have recently been suggested as therapeutic targets for improving human disease outcomes. Fibrotic diseases and cancer share several properties; both pathologies are characterized by genetic alterations, uncontrolled cell proliferation, altered cell interactions and communication and tissue invasion. The discovery of new HSP inhibitors that have been shown to be efficacious against certain types of cancers has given rise to a new field of research that investigates the activity of these compounds in other incurable human diseases such as fibrotic disorders. The aim of this review is to discuss new findings regarding the involvement of HSPs in the pathogenesis of organ fibrosis and to note recent discoveries that indicate that HSPs could be important therapeutic targets to improve the current dismal outcome of fibrotic diseases.

The small heat-shock protein αB-crystallin is essential for the nuclear localization of Smad4: impact on pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by the proliferation of myofibroblasts and the accumulation of extracellular matrix (ECM) in the lungs. TGF‐β1 is the major profibrotic cytokine involved in IPF and is responsible for myofibroblast proliferation and differentiation and ECM synthesis. αB‐crystallin is constitutively expressed in the lungs and is inducible by stress, acts as a chaperone and is known to play a role in cell cytoskeleton architecture homeostasis. The role of αB‐crystallin in fibrogenesis remains unknown. The principal signalling pathway involved in this process is the Smad‐dependent pathway. We demonstrate here that αB‐crystallin is strongly expressed in fibrotic lung tissue from IPF patients and in vivo rodent models of pulmonary fibrosis. We also show that αB‐crystallin‐deficient mice are protected from bleomycin‐induced fibrosis. Similar protection from fibrosis was observed in αB‐crystallin KO mice after transient adenoviral‐mediated over‐expression of IL‐1β or TGF‐β1. We show in vitro in primary epithelial cells and fibroblasts that αB‐crystallin increases the nuclear localization of Smad4, thereby enhancing the TGF‐β1–Smad pathway and the consequent activation of TGF‐β1 downstream genes. αB‐crystallin over‐expression disrupts Smad4 mono‐ubiquitination by interacting with its E3–ubiquitin ligase, TIF1γ, thus limiting its nuclear export. Conversely, in the absence of αB‐crystallin, TIF1γ can freely interact with Smad4. Consequently, Smad4 mono‐ubiquitination and nuclear export are favoured and thus TGF‐β1–Smad4 pro‐fibrotic activity is inhibited. This study demonstrates that αB‐crystallin may be a key target for the development of specific drugs in the treatment of IPF or other fibrotic diseases. Copyright

Antifibrotic role of αB-crystallin inhibition in pleural and subpleural fibrosis.

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

Pleural inhibition of the caspase-1/IL-1β pathway diminishes profibrotic lung toxicity of bleomycin

BackgroundIdiopathic and toxic pulmonary fibrosis are severe diseases starting classically in the subpleural area of the lung. It has recently been suggested that pleural mesothelial cells acquire a myofibroblast phenotype under fibrotic conditions induced by TGF-β1 or bleomycin. The importance and role of inflammation in fibrogenesis are still controversial. In this work, we explored the role of IL-1β/caspase-1 signaling in bleomycin lung toxicity and in pleural mesothelial cell transformation.MethodsC57BL/6 mice were intravenously injected with either bleomycin or nigericin or NaCl as control. In vitro, the Met5A cell line was used as a model of human pleural mesothelial cells.ResultsIntravenous injections of bleomycin induced lung fibrosis with histologically-proven peripheral distribution, collagen accumulation in the pleural and subpleural area, and overexpression of markers of myofibroblast transformation of pleural cells which migrated into the lung. These events were associated with an inflammatory process with an increase in neutrophil recruitment in pleural lavage fluid and increased caspase-1 activity. TGF-β1 was also overexpressed in pleural lavage fluid and was produced by pleural cells following intravenous bleomycin. In this model, local pleural inhibition of IL-1β with the IL-1β inhibitor anakinra diminished TGF-β1 and collagen accumulation. In vitro, caspase-1 inhibition interfered with Met5A cell transformation into the myofibroblast-like phenotype induced by bleomycin or TGF-β1. Moreover, nigericin, a caspase-1 activator, triggered transformation of Met5A cells and its intra-pleural delivery induced fibrogenesis in mice.ConclusionsWe demonstrated, after intravenous bleomycin injection in mice, the role of the pleura and highlighted the key role of IL-1β/caspase-1 axis in this fibrogenesis process.

Optimising experimental research in respiratory diseases: an ERS statement

Experimental models are critical for the understanding of lung health and disease and are indispensable for drug development. However, the pathogenetic and clinical relevance of the models is often unclear. Further, the use of animals in biomedical research is controversial from an ethical perspective. The objective of this task force was to issue a statement with research recommendations about lung disease models by facilitating in-depth discussions between respiratory scientists, and to provide an overview of the literature on the available models. Focus was put on their specific benefits and limitations. This will result in more efficient use of resources and greater reduction in the numbers of animals employed, thereby enhancing the ethical standards and translational capacity of experimental research. The task force statement addresses general issues of experimental research (ethics, species, sex, age, ex vivo and in vitro models, gene editing). The statement also includes research recommendations on modelling asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, lung infections, acute lung injury and pulmonary hypertension. The task force stressed the importance of using multiple models to strengthen validity of results, the need to increase the availability of human tissues and the importance of standard operating procedures and data quality. This document summarises the benefits and limitations of current lung disease models and how they can be improved http://ow.ly/SLFT30jEoCf

Small Heat Shock Proteins and Fibrosis

Small heat shock proteins (sHSP) are involved in many essential cellular mechanisms both in physiologic and pathologic conditions. HSP27 (HSPB1), αB-crystallin (HSPB5) and HSP20 (HSPB6), the most studied members, are stress-inducible chaperones with an anti-aggregation function. They have been shown to inhibit apoptosis by interacting with proteins involved in programmed cell death such as cytochrome c or caspases, to have anti-oxidant properties and/or to modulate protein homeostasis by participating in the proteasomal degradation of specific proteins under stress conditions. Heat shock proteins accumulate in cancer cells and this overexpression is needed for the cancer cells’ survival. Accordingly, the inhibition of heat shock proteins such as HSP27 is an emerging strategy in cancer therapy (already is in phase II clinical trials). Fibrogenesis and cancer share several properties as both pathologies are characterized by genetic alterations, uncontrolled cell proliferation, altered cell interaction and communication and tissue invasion.