Inhibition of MRTF activation as a clinically achievable anti-fibrotic mechanism for Pirfenidone

Evidence from recent clinical trials in fibrotic interstitial lung diseases

PURPOSE OF REVIEW

Idiopathic pulmonary fibrosis (IPF) is the prototype of fibrosing interstitial lung diseases. It is mirrored by progressive pulmonary fibrosis (PPF), an umbrella term which characterizes disease behavior of various fibrotic interstitial lung diseases with irreversible progression, accounting for loss of lung function, exercise intolerance and respiratory failure leading to early mortality. Pirfenidone and nintedanib halve the decline in lung function but do not halt disease progression.

RECENT FINDINGS

Since the publication in 2014 of pivotal pirfenidone and nintedanib studies, a number of clinical trials were conducted, many of them did not reach their primary endpoints. In IPF, promising phase 2 trials were followed by large phase 3 trials that did not confirm a favorable efficacy to tolerability favorable profile, including those with ziritaxestat, an autotaxin-1 inhibitor, zinpentraxin-alpha (human recombinant pentraxin-2), and the monoclonal antibody pamrevlumab targeting connective tissue growth factor. Nevertheless, newer compounds that hold promise are currently being evaluated in phase 3 or phase 2b randomized controlled trials, including: nerandomilast, a preferential phosphodiesterase 4B inhibitor; admilparant, a lysophosphatidic acid receptor antagonist; inhaled treprostinil, a prostacyclin agonist; and bexotegrast, a dual-selective inhibitor of αvβ6 and αvβ1 integrins. Nerandomilast, admilparant, inhaled treprostinil, and inhaled AP01 (pirfenidone), are currently studied in patients with PPF.

SUMMARY

Despite recent frustrating negative results, there is a growing portfolio of candidate drugs developed in both IPF and PPF.

Treatment of idiopathic pulmonary fibrosis: an update on emerging drugs in phase II & III clinical trials

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a progressive, debilitating lung disease with poor prognosis. Although two antifibrotics have been approved in the past decade there are no curative therapies.

AREAS COVERED

This review highlights the current landscape of IPF research in the development of novel compounds for the treatment of IPF while also evaluating repurposed medications and their role in the management of IPF. The literature search includes studies found on PubMed, conference abstracts, and press releases until March 2024.

EXPERT OPINION

Disease progression in IPF is driven by a dysregulated cycle of microinjury, aberrant wound healing, and propagating fibrosis. Current drug development focuses on attenuating fibrotic responses via multiple pathways. Phosphodiesterase 4 inhibitors (PDE4i), lysophosphatidic acid (LPA) antagonists, dual-selective inhibitor of αvβ6 and αvβ1 integrins, and the prostacyclin agonist Treprostinil have had supportive phase II clinical trial results in slowing decline in forced vital capacity (FVC) in IPF. Barriers to drug development specific to IPF include the lack of a rodent model that mimics IPF pathology, the nascent understanding of the role of genetics affecting development of IPF and response to treatment, and the lack of a validated biomarker to monitor therapeutic response in patients with IPF. Successful treatment of IPF will likely include a multi-targeted approach anchored in precision medicine.

Reusable tutorials for using cloud-based computing environments for the analysis of bacterial gene expression data from bulk RNA sequencing

This manuscript describes the development of a resource module that is part of a learning platform named "NIGMS Sandbox for Cloud-based Learning" https://github.com/NIGMS/NIGMS-Sandbox. The overall genesis of the Sandbox is described in the editorial NIGMS Sandbox at the beginning of this Supplement. This module delivers learning materials on RNA sequencing (RNAseq) data analysis in an interactive format that uses appropriate cloud resources for data access and analyses. Biomedical research is increasingly data-driven, and dependent upon data management and analysis methods that facilitate rigorous, robust, and reproducible research. Cloud-based computing resources provide opportunities to broaden the application of bioinformatics and data science in research. Two obstacles for researchers, particularly those at small institutions, are: (i) access to bioinformatics analysis environments tailored to their research; and (ii) training in how to use Cloud-based computing resources. We developed five reusable tutorials for bulk RNAseq data analysis to address these obstacles. Using Jupyter notebooks run on the Google Cloud Platform, the tutorials guide the user through a workflow featuring an RNAseq dataset from a study of prophage altered drug resistance in Mycobacterium chelonae. The first tutorial uses a subset of the data so users can learn analysis steps rapidly, and the second uses the entire dataset. Next, a tutorial demonstrates how to analyze the read count data to generate lists of differentially expressed genes using R/DESeq2. Additional tutorials generate read counts using the Snakemake workflow manager and Nextflow with Google Batch. All tutorials are open-source and can be used as templates for other analysis.

Investigation of a UPR-Related Gene Signature Identifies the Pro-Fibrotic Effects of Thrombospondin-1 by Activating CD47/ROS/Endoplasmic Reticulum Stress Pathway in Lung Fibroblasts

Unfolded protein response (UPR) signaling and endoplasmic reticulum (ER) stress have been linked to pulmonary fibrosis. However, the relationship between UPR status and pulmonary function and prognosis in idiopathic pulmonary fibrosis (IPF) patients remains largely unknown. Through a series of bioinformatics analyses, we established a correlation between UPR status and pulmonary function in IPF patients. Furthermore, thrombospondin-1 (TSP-1) was identified as a potential biomarker for prognostic evaluation in IPF patients. By utilizing both bulk RNA profiling and single-cell RNA sequencing data, we demonstrated the upregulation of TSP-1 in lung fibroblasts during pulmonary fibrosis. Gene set enrichment analysis (GSEA) results indicated a positive association between TSP-1 expression and gene sets related to the reactive oxygen species (ROS) pathway in lung fibroblasts. TSP-1 overexpression alone induced mild ER stress and pulmonary fibrosis, and it even exacerbated bleomycin-induced ER stress and pulmonary fibrosis. Mechanistically, TSP-1 promoted ER stress and fibroblast activation through CD47-dependent ROS production. Treatment with either TSP-1 inhibitor or CD47 inhibitor significantly attenuated BLM-induced ER stress and pulmonary fibrosis. Collectively, these findings suggest that the elevation of TSP-1 during pulmonary fibrosis is not merely a biomarker but likely plays a pathogenic role in the fibrotic changes in the lung.

Catch your breath: The protective role of the angiotensin AT2 receptor for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease whereby excessive deposition of extracellular matrix proteins (ECM) ultimately leads to respiratory failure. While there have been advances in pharmacotherapies for pulmonary fibrosis, IPF remains an incurable and irreversible disease. There remains an unmet clinical need for treatments that reverse fibrosis, or at the very least have a more tolerable side effect profile than currently available treatments. Transforming growth factor β1(TGFβ1) is considered the main driver of fibrosis in IPF. However, as our understanding of the role of the pulmonary renin-angiotensin system (PRAS) in the pathogenesis of IPF increases, it is becoming clear that targeting angiotensin receptors represents a potential novel treatment strategy for IPF - in particular, via activation of the anti-fibrotic angiotensin type 2 receptor (AT2R). This review describes the current understanding of the pathophysiology of IPF and the mediators implicated in its pathogenesis; focusing on TGFβ1, angiotensin II and related peptides in the PRAS and their contribution to fibrotic processes in the lung. Preclinical and clinical assessment of currently available AT2R agonists and the development of novel, highly selective ligands for this receptor will also be described, with a focus on compound 21, currently in clinical trials for IPF. Collectively, this review provides evidence of the potential of AT2R as a novel therapeutic target for IPF.

Back to the future: targeting the extracellular matrix to treat systemic sclerosis

Fibrosis is the excessive deposition of a stable extracellular matrix (ECM); fibrotic tissue is composed principally of highly crosslinked type I collagen and highly contractile myofibroblasts. Systemic sclerosis (SSc) is a multisystem autoimmune connective tissue disease characterized by skin and organ fibrosis. The fibrotic process has been recognized in SSc for >40 years, but drugs with demonstrable efficacy against SSc fibrosis in ameliorating the lung involvement have only recently been identified. Unfortunately, these treatments are ineffective at improving the skin score in patients with SSc. Previous clinical trials in SSc have largely focused on the cross-purposing of anti-inflammatory drugs and the use of immunosuppressive drugs from the transplantation field, which address inflammatory and/or autoimmune processes. Limited examination has taken place of specific anti-fibrotic agents developed through their ability to directly target the ECM in SSc by, for example, alleviating the persistent matrix stiffness and mechanotransduction that might be required for both the initiation and maintenance of fibrosis, including in SSc. However, because of the importance of the ECM in the SSc phenotype, attempts have now been made to identify drugs that specifically target the ECM, including some drugs that are currently under consideration for the treatment of cancer.

Novel approaches to target fibroblast mechanotransduction in fibroproliferative diseases

The ability of cells to sense and respond to changes in mechanical environment is vital in conditions of organ injury when the architecture of normal tissues is disturbed or lost. Among the various cellular players that respond to injury, fibroblasts take center stage in re-establishing tissue integrity by secreting and organizing extracellular matrix into stabilizing scar tissue. Activation, activity, survival, and death of scar-forming fibroblasts are tightly controlled by mechanical environment and proper mechanotransduction ensures that fibroblast activities cease after completion of the tissue repair process. Conversely, dysregulated mechanotransduction often results in fibroblast over-activation or persistence beyond the state of normal repair. The resulting pathological accumulation of extracellular matrix is called fibrosis, a condition that has been associated with over 40% of all deaths in the industrialized countries. Consequently, elements in fibroblast mechanotransduction are scrutinized for their suitability as anti-fibrotic therapeutic targets. We review the current knowledge on mechanically relevant factors in the fibroblast extracellular environment, cell-matrix and cell-cell adhesion structures, stretch-activated membrane channels, stress-regulated cytoskeletal structures, and co-transcription factors. We critically discuss the targetability of these elements in therapeutic approaches and their progress in pre-clinical and/or clinical trials to treat organ fibrosis.

Innovative Pre-Clinical Data Using Peptides to Intervene in the Evolution of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, relentless, and deadly disease. Little is known about its pathogenetic mechanisms; therefore, developing efficient pharmacological therapies is challenging. This work aimed to apply a therapeutic alternative using immunomodulatory peptides in a chronic pulmonary fibrosis murine model. BALB/c mice were intratracheally instilled with bleomycin (BLM) and followed for 30 days. The mice were treated with the immune modulatory peptides ToAP3 and ToAP4 every three days, starting on the 5th day post-BLM instillation. ELISA, qPCR, morphology, and respiratory function analyses were performed. The treatment with both peptides delayed the inflammatory process observed in the non-treated group, which showed a fibrotic process with alterations in the production of collagen I, III, and IV that were associated with significant alterations in their ventilatory mechanics. The ToAP3 and ToAP4 treatments, by lung gene modulation patterns, indicated that distinct mechanisms determine the action of peptides. Both peptides controlled the experimental IPF, maintaining the tissue characteristics and standard function properties and regulating fibrotic-associated cytokine production. Data obtained in this work show that the immune response regulation by ToAP3 and ToAP4 can control the alterations that cause the fibrotic process after BLM instillation, making both peptides potential therapeutic alternatives and/or adjuvants for IPF.