Novel Mechanisms for the Antifibrotic Action of Nintedanib

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)-b1-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-b signaling, specifically tyrosine phosphorylation of the type II TGF-b 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-b signaling. These mechanisms appear to be uncoupled and function independently to mediate its putative antifibrotic effects.

3D pulmospheres serve as a personalized and predictive multicellular model for assessment of antifibrotic drugs

“…The mechanism of action of pirfenidone is thought to be through inhibition of TGF-β1 (34), with subsequent downregulation of inflammatory cytokines and oxidative stress (1). Nintedanib is thought to inhibit tyrosine kinases and has been more recently recognized to induce noncanonical autophagy in fibroblasts, while also inhibiting TGF-β1 signaling (35,36). There are at least 10 ongoing clinical trials targeting various mediators with calls for using a multitargeted approach during the course of the disease (36).…”

“…Nintedanib is thought to inhibit tyrosine kinases and has been more recently recognized to induce noncanonical autophagy in fibroblasts, while also inhibiting TGF-β1 signaling (35,36). There are at least 10 ongoing clinical trials targeting various mediators with calls for using a multitargeted approach during the course of the disease (36).…”

Pirfenidone may revert the epithelial-to-mesenchymal transition in human lung adenocarcinoma

“…The same authors also reported that the promotion of E-cadherin expression in A-549 cells occurred through ZEB1 downregulation (22). Furthermore, nintedanib was demonstrated to inhibit TGF-β-induced myofibroblast differentiation through the inhibition of early events in TGF-β signaling and the activation of SMAD family member 3 (Smad3) in lung fibroblast cells (18). Therefore, the present study has provided novel evidence that pirfenidone possesses a similar ability to revert the EMT in human lung adenocarcinoma cells.…”

“…The expression levels of the receptor tyrosine kinases of PDGF, FGF and vascular endothelial growth factor were observed to be inhibited following treatment with nintedanib (17). Recently, nintedanib was demonstrated to inhibit the early signaling of TGF-β by suppressing the phosphorylation of the TGF-β type II receptor (18 Numerous studies have reported that the relative risk of lung cancer among patients with IPF is 7-14 times higher compared with that in patients without IPF (19)(20)(21). Under such circumstances, these agents may soon be widely used for the treatment of patients with lung cancer accompanied by IPF.…”

Getting to the core of fibrosis: targeting redox imbalance in aging

“…Interestingly, the precise mechanisms of action of these drugs are not known (3). Importantly, although both drugs have been shown to slow the progression of disease, neither has been shown to definitively improve quality of life or survival.…”