Lutz Wollin

Antifibrotic and Anti-inflammatory Activity of the Tyrosine Kinase Inhibitor Nintedanib in Experimental Models of Lung Fibrosis

The tyrosine kinase inhibitor nintedanib (BIBF 1120) is in clinical development for the treatment of idiopathic pulmonary fibrosis. To explore its mode of action, nintedanib was tested in human lung fibroblasts and mouse models of lung fibrosis. Human lung fibroblasts expressing platelet-derived growth factor (PDGF) receptor-α and -β were stimulated with platelet-derived growth factor BB (homodimer) (PDGF-BB). Receptor activation was assessed by autophosphorylation and cell proliferation by bromodeoxyuridine incorporation. Transforming growth factor β (TGFβ)-induced fibroblast to myofibroblast transformation was determined by α-smooth muscle actin (αSMA) mRNA analysis. Lung fibrosis was induced in mice by intratracheal bleomycin or silica particle administration. Nintedanib was administered every day by gavage at 30, 60, or 100 mg/kg. Preventive nintedanib treatment regimen started on the day that bleomycin was administered. Therapeutic treatment regimen started at various times after the induction of lung fibrosis. Bleomycin caused increased macrophages and lymphocytes in the bronchoalveolar lavage (BAL) and elevated interleukin-1β (IL-1β), tissue inhibitor of metalloproteinase-1 (TIMP-1), and collagen in lung tissue. Histology revealed chronic inflammation and fibrosis. Silica-induced lung pathology additionally showed elevated BAL neutrophils, keratinocyte chemoattractant (KC) levels, and granuloma formation. Nintedanib inhibited PDGF receptor activation, fibroblast proliferation, and fibroblast to myofibroblast transformation. Nintedanib significantly reduced BAL lymphocytes and neutrophils but not macrophages. Furthermore, interleukin-1β, KC, TIMP-1, and lung collagen were significantly reduced. Histologic analysis showed significantly diminished lung inflammation, granuloma formation, and fibrosis. The therapeutic effect was dependent on treatment start and duration. Nintedanib inhibited receptor tyrosine kinase activation and the proliferation and transformation of human lung fibroblasts and showed antifibrotic and anti-inflammatory activity in two animal models of pulmonary fibrosis. These results suggest that nintedanib may impact the progressive course of fibrotic lung diseases such as idiopathic pulmonary fibrosis.

Mode of action of nintedanib in the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal disease characterised by fibrosis of the lung parenchyma and loss of lung function. Although the pathogenic pathways involved in IPF have not been fully elucidated, IPF is believed to be caused by repetitive alveolar epithelial cell injury and dysregulated repair, in which there is uncontrolled proliferation of lung fibroblasts and differentiation of fibroblasts into myofibroblasts, which excessively deposit extracellular matrix (ECM) proteins in the interstitial space. A number of profibrotic mediators including platelet-derived growth factor (PDGF), fibroblast growth factor (FGF) and transforming growth factor-β are believed to play important roles in the pathogenesis of IPF. Nintedanib is a potent small molecule inhibitor of the receptor tyrosine kinases PDGF receptor, FGF receptor and vascular endothelial growth factor receptor. Data from in vitro studies have shown that nintedanib interferes with processes active in fibrosis such as fibroblast proliferation, migration and differentiation, and the secretion of ECM. In addition, nintedanib has shown consistent anti-fibrotic and anti-inflammatory activity in animal models of lung fibrosis. These data provide a strong rationale for the clinical efficacy of nintedanib in patients with IPF, which has recently been demonstrated in phase III clinical trials. Nintedanib interferes with processes active in fibrosis, e.g. fibroblast proliferation, migration and differentiation http://ow.ly/Iae9z

Nintedanib inhibits fibroblast activation and ameliorates fibrosis in preclinical models of systemic sclerosis

Background Nintedanib is a tyrosine kinase inhibitor that has recently been shown to slow disease progression in idiopathic pulmonary fibrosis in two replicate phase III clinical trials. The aim of this study was to analyse the antifibrotic effects of nintedanib in preclinical models of systemic sclerosis (SSc) and to provide a scientific background for clinical trials in SSc. Methods The effects of nintedanib on migration, proliferation, myofibroblast differentiation and release of extracellular matrix of dermal fibroblasts were analysed by microtitre tetrazolium and scratch assays, stress fibre staining, qPCR and SirCol assays. The antifibrotic effects of nintedanib were evaluated in bleomycin-induced skin fibrosis, in a murine sclerodermatous chronic graft-versus-host disease model and in tight-skin-1 mice. Results Nintedanib dose-dependently reduced platelet-derived growth factor-induced and transforming growth factor-β-induced proliferation and migration as well as myofibroblast differentiation and collagen release of dermal fibroblasts from patients with and healthy individuals. Nintedanib also inhibited the endogenous activation of SSc fibroblasts. Nintedanib prevented bleomycin-induced skin fibrosis in a dose-dependent manner and was also effective in the treatment of established fibrosis. Moreover, treatment with nintedanib ameliorated fibrosis in the chronic graft-versus-host disease model and in tight-skin-1 mice in well-tolerated doses. Conclusions We demonstrate that nintedanib effectively inhibits the endogenous as well as cytokine-induced activation of SSc fibroblasts and exerts potent antifibrotic effects in different complementary mouse models of SSc. These data have direct translational implications for clinical trials with nintedanib in SSc.

Induced Syk deletion leads to suppressed allergic responses but has no effect on neutrophil or monocyte migration in vivo.

The spleen tyrosine kinase (Syk) is a key mediator of immunoreceptor signaling in immune cells. Thus, interfering with the function of Syk by genetic deletion or pharmacological inhibition might influence a variety of allergic and autoimmune processes. Since conventional Syk knockout mice are not viable, studies addressing the effect of Syk deletion in adult animals have been limited. To further explore functions of Syk in animal models of allergy and to shed light on the role of Syk in the in vivo migration of neutrophils and monocytes, we generated inducible Syk knockout mice. These mice harbor a floxed Syk gene and a tamoxifen‐inducible Cre recombinase under the control of the ubiquitously active Rosa26‐promoter. Thus, treatment of mice with tamoxifen leads to the deletion of Syk in all organs. Syk‐deleted mice were analyzed in mast cell‐dependent models and in models focusing on neutrophil and monocyte migration. We show that Syk deletion in adult mice reduces inflammatory responses in mast cell‐driven animal models of allergy and asthma but has no effect on the migration of neutrophils and monocytes. Therefore, the inducible Syk knockout mice presented here provide a valuable tool to further explore the role of Syk in disease‐related animal models.

Idiopathic pulmonary fibrosis: current treatment options and critical appraisal of nintedanib.

Idiopathic pulmonary fibrosis (IPF) is the most common type of idiopathic interstitial pneumonia and is characterized by a poor prognosis, with an estimated 5-year survival of approximately 20%. Progressive and irreversible lung functional impairment leads to chronic respiratory insufficiency with a severely impaired quality of life. In the last 2 decades, novel treatments for IPF have been developed as a consequence of an increasing understanding of disease pathogenesis and pathobiology. In IPF, injured dysfunctional alveolar epithelial cells promote fibroblast recruitment and proliferation, resulting in scarring of the lung tissue. Recently, pirfenidone and nintedanib have been approved for the treatment of IPF, having shown efficacy to slow functional decline and disease progression. This article focuses on the pharmacologic characteristics and clinical evidence supporting the use of nintedanib, a potent small-molecule tyrosine kinase inhibitor, as therapy for IPF. After introducing the mechanism of action and pharmacokinetics, an overview of the safety and efficacy results from the most recent clinical trials of nintedanib in IPF is presented.

Nintedanib inhibits macrophage activation and ameliorates vascular and fibrotic manifestations in the Fra2 mouse model of systemic sclerosis

Background Nintedanib is an inhibitor targeting platelet-derived growth factor receptor, fibroblast growth factor receptor and vascular endothelial growth factor receptor tyrosine kinases that has recently been approved for the treatment of idiopathic pulmonary fibrosis. The aim of this study was to analyse the effects of nintedanib in the fos-related antigen-2 (Fra2) mouse model of systemic sclerosis (SSc). Methods The effects of nintedanib on pulmonary arterial hypertension with proliferation of pulmonary vascular smooth muscle cells (PVSMCs) and luminal occlusion, on microvascular disease with apoptosis of microvascular endothelial cells (MVECs) and on fibroblast activation with myofibroblast differentiation and accumulation of extracellular matrix were analysed. We also studied the effects of nintedanib on the levels of key mediators involved in the pathogenesis of SSc and on macrophage polarisation. Results Nintedanib inhibited proliferation of PVSMCs and prevented thickening of the vessel walls and luminal occlusion of pulmonary arteries. Treatment with nintedanib also inhibited apoptosis of MVECs and blunted the capillary rarefaction in Fra2-transgenic mice. These effects were associated with a normalisation of the serum levels of vascular endothelial growth factor in Fra2 mice on treatment with nintedanib. Nintedanib also effectively blocked myofibroblast differentiation and reduced pulmonary, dermal and myocardial fibrosis in Fra2-transgenic mice. The antifibrotic effects of nintedanib were associated with impaired M2 polarisation of monocytes and reduced numbers of M2 macrophages. Conclusion Nintedanib targets core features of SSc in Fra2-transgenic mice and ameliorates histological features of pulmonary arterial hypertension, destructive microangiopathy and pulmonary and dermal fibrosis. These data might have direct implications for the ongoing phase III clinical trial with nintedanib in SSc-associated interstitial lung disease.

The long‐acting β2‐adrenoceptor agonist olodaterol attenuates pulmonary inflammation

β2‐adrenoceptor agonists are widely used in the management of obstructive airway diseases. Besides their bronchodilatory effect, several studies suggest inhibitory effects on various aspects of inflammation. The aim of our study was to determine the efficacy of the long‐acting β2‐adrenoceptor agonist olodaterol to inhibit pulmonary inflammation and to elucidate mechanism(s) underlying its anti‐inflammatory actions.

Quantification of Pulmonary Fibrosis in a Bleomycin Mouse Model Using Automated Histological Image Analysis.

Current literature on pulmonary fibrosis induced in animal models highlights the need of an accurate, reliable and reproducible histological quantitative analysis. One of the major limits of histological scoring concerns the fact that it is observer-dependent and consequently subject to variability, which may preclude comparative studies between different laboratories. To achieve a reliable and observer-independent quantification of lung fibrosis we developed an automated software histological image analysis performed from digital image of entire lung sections. This automated analysis was compared to standard evaluation methods with regard to its validation as an end-point measure of fibrosis. Lung fibrosis was induced in mice by intratracheal administration of bleomycin (BLM) at 0.25, 0.5, 0.75 and 1 mg/kg. A detailed characterization of BLM-induced fibrosis was performed 14 days after BLM administration using lung function testing, micro-computed tomography and Ashcroft scoring analysis. Quantification of fibrosis by automated analysis was assessed based on pulmonary tissue density measured from thousands of micro-tiles processed from digital images of entire lung sections. Prior to analysis, large bronchi and vessels were manually excluded from the original images. Measurement of fibrosis has been expressed by two indexes: the mean pulmonary tissue density and the high pulmonary tissue density frequency. We showed that tissue density indexes gave access to a very accurate and reliable quantification of morphological changes induced by BLM even for the lowest concentration used (0.25 mg/kg). A reconstructed 2D-image of the entire lung section at high resolution (3.6 μm/pixel) has been performed from tissue density values allowing the visualization of their distribution throughout fibrotic and non-fibrotic regions. A significant correlation (p<0.0001) was found between automated analysis and the above standard evaluation methods. This correlation establishes automated analysis as a novel end-point measure of BLM-induced lung fibrosis in mice, which will be very valuable for future preclinical drug explorations.

Tyrosine Kinase Inhibitor BIBF1000 does not hamper right ventricular pressure adaptation in rats

BIBF1000 is a small molecule tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), and platelet-derived growth factor receptor (PDGFR) and is a powerful inhibitor of fibrogenesis. BIBF1000 is very similar to BIBF1120 (nintedanib), a drug recently approved for the treatment of idiopathic pulmonary fibrosis (IPF). A safety concern pertaining to VEGFR, FGFR, and PDGFR inhibition is the possible interference with right ventricular (RV) responses to an increased afterload, which could adversely affect clinical outcome in patients with IPF who developed pulmonary hypertension. We tested the effect of BIBF1000 on the adaptation of the RV in rats subjected to mechanical pressure overload. BIBF1000 was administered for 35 days in pulmonary artery-banded (PAB) rats. RV adaptation was assessed by echocardiography, pressure volume loop analysis, histology, and determination of atrial natriuretic peptide (ANP) expression. BIBF1000 treatment resulted in growth attenuation but had no effects on RV function after PAB, given absence of changes in cardiac index, end-systolic elastance, connective tissue disposition, and capillary density. We conclude that, in this experimental model of increased afterload, combined VEGFR, FGFR, and PDGFR inhibition does not hamper RV adaptation to pressure overload.

Olodaterol shows anti‐fibrotic efficacy in in vitro and in vivo models of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal respiratory disease characterized by excessive fibroblast activation ultimately leading to scarring of the lungs. Although, the activation of β2‐adrenoceptors (β2‐AR) has been shown to inhibit pro‐fibrotic events primarily in cell lines, the role of β2‐adrenoceptor agonists has not yet been fully characterized. The aim of our study was to explore the anti‐fibrotic activity of the long‐acting β2‐adrenoceptor agonist olodaterol in primary human lung fibroblasts (HLF) and in murine models of pulmonary fibrosis.