Inhalation: A means to explore and optimize nintedanib's pharmacokinetic/pharmacodynamic relationship

Prostaglandin E2 (PGE2) and Roflumilast Involvement in IPF Progression

The ECM propagates processes in idiopathic pulmonary fibrosis (IPF), leading to progressive lung scarring. We established an IPF-conditioned matrix (IPF-CM) system as a platform for testing drug candidates. Here, we tested the involvement of a PGE2 and PDE4 inhibitor, Roflumilast, in the IPF-CM system. Primary normal/IPF tissue-derived human lung fibroblasts (N/IPF-HLFs) were cultured on Matrigel and then removed to create the IPF-CM. N-HLFs were exposed to the IPF-CM/N-CM with/without PGE2 (1 nM) and Roflumilast (1 µM) for 24 h. The effect of the IPF-CM on cell phenotype and pro-fibrotic gene expression was tested. In addition, electronic records of 107 patients with up to 15-year follow-up were retrospectively reviewed. Patients were defined as slow/rapid progressors using forced vital capacity (FVC) annual decline. Medication exposure was examined. N-HLFs cultured on IPF-CM were arranged in large aggregates as a result of increased proliferation, migration and differentiation. A PGE2 and Roflumilast combination blocked the large aggregate formation induced by the IPF-CM (p < 0.001) as well as cell migration, proliferation, and pro-fibrotic gene expression. A review of patient records showed that significantly more slow-progressing patients were exposed to NSAIDs (p = 0.003). PGE2/PDE4 signaling may be involved in IPF progression. These findings should be further studied.

Development of nintedanib nanosuspension for inhaled treatment of experimental silicosis

Silicosis is an irreversible and progressive fibrotic lung disease caused by massive inhalation of crystalline silica dust at workplaces, affecting millions of industrial workers worldwide. A tyrosine kinase inhibitor, nintedanib (NTB), has emerged as a potential silicosis treatment due to its inhibitory effects on key signaling pathways that promote silica-induced pulmonary fibrosis. However, chronic and frequent use of the oral NTB formulation clinically approved for treating other fibrotic lung diseases often results in significant side effects. To this end, we engineered a nanocrystal-based suspension formulation of NTB (NTB-NS) possessing specific physicochemical properties to enhance drug retention in the lung for localized treatment of silicosis via inhalation. Our NTB-NS formulation was prepared using a wet-milling procedure in presence of Pluronic F127 to endow the formulation with nonadhesive surface coatings to minimize interactions with therapy-inactivating delivery barriers in the lung. We found that NTB-NS, following intratracheal administration, provided robust anti-fibrotic effects and mechanical lung function recovery in a mouse model of silicosis, whereas a 100-fold greater oral NTB dose given with a triple dosing frequency failed to do so. Importantly, several key pathological phenotypes were fully normalized by NTB-NS without displaying notable local or systemic adverse effects. Overall, NTB-NS may open a new avenue for localized treatment of silicosis and potentially other fibrotic lung diseases.

Mechanisms by Which Liposomes Improve Inhaled Drug Delivery for Alveolar Diseases

Diseases of the pulmonary alveolus, such as pulmonary fibrosis, are leading causes of morbidity and mortality, but exceedingly few drugs are developed for them. A major reason for this gap is that after inhalation, drugs are quickly whisked away from alveoli due to their high perfusion. To solve this problem, the mechanisms by which nano-scale drug carriers dramatically improve lung pharmacokinetics using an inhalable liposome formulation containing nintedanib, an antifibrotic for pulmonary fibrosis, are studied. Direct instillation of liposomes in murine lung increases nintedanib's total lung delivery over time by 8000-fold and lung half life by tenfold, compared to oral nintedanib. Counterintuitively, it is shown that pulmonary surfactant neither lyses nor aggregates the liposomes. Instead, each lung compartment (alveolar fluid, alveolar leukocytes, and parenchyma) elutes liposomes over 24 h, likely serving as "drug depots." After deposition in the surfactant layer, liposomes are transferred over 3-6 h to alveolar leukocytes (which take up a surprisingly minor 1-5% of total lung dose instilled) in a nonsaturable fashion. Further, all cell layers of the lung parenchyma take up liposomes. These and other mechanisms elucidated here should guide engineering of future inhaled nanomedicine for alveolar diseases.

Mouse Models of Lung Fibrosis

The drug discovery pipeline, from discovery of therapeutic targets through preclinical and clinical development phases, to an approved product by health authorities, is a time-consuming and costly process, where a lead candidates' success at reaching the final stage is rare. Although the time from discovery to final approval has been reduced over the last decade, there is still potential to further optimize and streamline the evaluation process of each candidate as it moves through the different development phases. In this book chapter, we describe our preclinical strategies and overall decision-making process designed to evaluate the tolerability and efficacy of therapeutic candidates suitable for patients diagnosed with fibrotic lung disease. We also describe the benefits of conducting preliminary discovery trials, to aid in the selection of suitable primary and secondary outcomes to be further evaluated and assessed in subsequent internal and external validation studies. We outline all relevant research methodologies and protocols routinely performed by our research group and hope that these strategies and protocols will be a useful guide for biomedical and translational researchers aiming to develop safe and beneficial therapies for patients with fibrotic lung disease.

New Insights into Pathomechanisms and Treatment Possibilities for Lung Silicosis

Inhalation of silica particles is an environmental and occupational cause of silicosis, a type of pneumoconiosis. Development of the lung silicosis is a unique process in which the vicious cycle of ingestion of inhaled silica particles by alveolar macrophages and their release triggers inflammation, generation of nodular lesions, and irreversible fibrosis. The pathophysiology of silicosis is complex, and interactions between the pathomechanisms have not been completely understood. However, elucidation of silica-induced inflammation cascades and inflammation-fibrosis relations has uncovered several novel possibilities of therapeutic targeting. This article reviews new information on the pathophysiology of silicosis and points out several promising treatment approaches targeting silicosis-related pathways.

Hypoxia Inducible Factor 1A Supports a Pro-Fibrotic Phenotype Loop in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis. The IPF-conditioned matrix (IPF-CM) system enables the study of matrix–fibroblast interplay. While effective at slowing fibrosis, nintedanib has limitations and the mechanism is not fully elucidated. In the current work, we explored the underlying signaling pathways and characterized nintedanib involvement in the IPF-CM fibrotic process. Results were validated using IPF patient samples and bleomycin-treated animals with/without oral and inhaled nintedanib. IPF-derived primary human lung fibroblasts (HLFs) were cultured on Matrigel and then cleared using NH₄OH, creating the IPF-CM. Normal HLF-CM served as control. RNA-sequencing, PCR and western-blots were performed. HIF1α targets were evaluated by immunohistochemistry in bleomycin-treated rats with/without nintedanib and in patient samples with IPF. HLFs cultured on IPF-CM showed over-expression of ‘HIF1α signaling pathway’ (KEGG, p < 0.0001), with emphasis on SERPINE1 (PAI-1), VEGFA and TIMP1. IPF patient samples showed high HIF1α staining, especially in established fibrous tissue. PAI-1 was overexpressed, mainly in alveolar macrophages. Nintedanib completely reduced HIF1α upregulation in the IPF-CM and rat-bleomycin models. IPF-HLFs alter the extracellular matrix, thus creating a matrix that further propagates an IPF-like phenotype in normal HLFs. This pro-fibrotic loop includes the HIF1α pathway, which can be blocked by nintedanib.

Galectin-3 levels are elevated following nintedanib treatment

Background and Aims:

Idiopathic pulmonary fibrosis (IPF) is a common and severe form of pulmonary fibrosis. Nintedanib, a triple angiokinase inhibitor, is approved for treating IPF. Galectin 3 (Gal-3) activates a variety of profibrotic processes. Currently, the Gal-3 inhibitor TD139 is being tested in phase II clinical trials. Since this treatment is given ‘on top’ of nintedanib, it is important to estimate its effect on Gal-3 levels. Therefore, we evaluated the impact of nintedanib on Gal-3 expression using both in vitro and in vivo models, in addition to serum samples from patients with IPF.

Methods:

Gal-3 levels were evaluated in IPF and control tissue samples, primary human lung fibroblasts (HLFs) following nintedanib treatment (10–100 nM, quantitative polymerase chain reaction), and in a silica-induced fibrosis mouse model with/without nintedanib (0.021–0.21 mg/kg) by immunohistochemistry. In addition, Gal-3 levels were analyzed in serum samples from 41 patients with interstitial lung disease patients with/without nintedanib treatment by ELISA.

Results:

Nintedanib addition to HLFs resulted in significant elevations in Gal-3, phospho-signal transducer and activator of transcription 3 (pSTAT3), as well as IL-8 mRNA levels (p < 0.05). Gal-3 expression was higher in samples from IPF patients compared with non-IPF controls at the protein and mRNA levels (p < 0.05). In the in vivo mouse model, Gal-3 levels were increased following fibrosis induction and even further increased with the addition of nintedanib, mostly in macrophages (p < 0.05). Patients receiving nintedanib presented with higher Gal-3 serum levels compared with those who did not receive nintedanib (p < 0.05).

Conclusion:

Nintedanib elevates Gal-3 levels in both experimental models, along with patient samples. These findings highlight the possibility of using combined inhibition therapy for patients with IPF.