Abstract
Idiopathic pulmonary fibrosis (IPF) is a disease with relentless course and limited therapeutic options. Nintedanib (BIBF-1120) is a multiple tyrosine kinase inhibitor recently approved by the U.S. Food and Drug Administration for the treatment of IPF. The precise antifibrotic mechanism(s) of action of nintedanib, however, is not known. Therefore, we studied the effects of nintedanib on fibroblasts isolated from the lungs of patients with IPF. Protein and gene expression of profibrotic markers were assessed by Western immunoblotting and real-time PCR. Autophagy markers and signaling events were monitored by biochemical assays, Western immunoblotting, microscopy, and immunofluorescence staining. Silencing of autophagy effector proteins was achieved with small interfering RNAs. Nintedanib down-regulated protein and mRNA expression of extracellular matrix (ECM) proteins, fibronectin, and collagen 1a1 while inhibiting transforming growth factor (TGF)-β1-induced myofibroblast differentiation. Nintedanib also induced beclin-1-dependent, ATG7-independent autophagy. Nintedanib's ECM-suppressive actions were not mediated by canonical autophagy. Nintedanib inhibited early events in TGF-β signaling, specifically tyrosine phosphorylation of the type II TGF-β receptor, activation of SMAD3, and p38 mitogen-activated protein kinase. Nintedanib down-regulates ECM production and induces noncanonical autophagy in IPF fibroblasts while inhibiting TGF-β signaling. These mechanisms appear to be uncoupled and function independently to mediate its putative antifibrotic effects.
Keywords:
autophagy; fibroblasts; fibrosis; nintedanib; transforming growth factor-β.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Apoptosis Regulatory Proteins / genetics
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Apoptosis Regulatory Proteins / metabolism
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Autophagy-Related Protein 7
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Beclin-1
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Cells, Cultured
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Collagen Type I / genetics
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Collagen Type I / metabolism
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Collagen Type I, alpha 1 Chain
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Dose-Response Relationship, Drug
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Fibronectins / genetics
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Fibronectins / metabolism
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Humans
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Idiopathic Pulmonary Fibrosis / genetics
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Idiopathic Pulmonary Fibrosis / metabolism
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Idiopathic Pulmonary Fibrosis / pathology
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Idiopathic Pulmonary Fibrosis / prevention & control*
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Indoles / pharmacology*
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Lung / drug effects*
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Lung / metabolism
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Lung / pathology
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Phosphorylation
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Protein Serine-Threonine Kinases / metabolism
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RNA Interference
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RNA, Messenger / metabolism
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Receptor, Transforming Growth Factor-beta Type II
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Receptors, Transforming Growth Factor beta / metabolism
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Signal Transduction / drug effects
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Smad3 Protein / metabolism
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Time Factors
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Transfection
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Transforming Growth Factor beta1 / metabolism
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Ubiquitin-Activating Enzymes / genetics
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Ubiquitin-Activating Enzymes / metabolism
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p38 Mitogen-Activated Protein Kinases / metabolism
Substances
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Apoptosis Regulatory Proteins
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BECN1 protein, human
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Beclin-1
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Collagen Type I
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Collagen Type I, alpha 1 Chain
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Fibronectins
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Indoles
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Membrane Proteins
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RNA, Messenger
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Receptors, Transforming Growth Factor beta
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SMAD3 protein, human
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Smad3 Protein
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Transforming Growth Factor beta1
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Protein Serine-Threonine Kinases
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p38 Mitogen-Activated Protein Kinases
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Receptor, Transforming Growth Factor-beta Type II
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ATG7 protein, human
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Autophagy-Related Protein 7
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Ubiquitin-Activating Enzymes
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nintedanib