Idiopathic Pulmonary Fibrosis: Diagnosis and Clinical Manifestations

Therapeutic Strategies for Idiopathic Pulmonary Fibrosis - Thriving Present and Promising Tomorrow

Idiopathic pulmonary fibrosis (IPF) is a continuous, progressive, and lethal age-related respiratory disease. It is characterized by condensed and rigid lung tissue, which leads to a decline in the normal functioning of the lungs. The pathophysiology of IPF has still not been completely elucidated, so current strategies are lagging behind with respect to improving the condition of patients with IPF and increasing their survival rate. The desire for a better understanding of the pathobiology of IPF and its early detection has led to the identification of various biomarkers associated with IPF. The use of drugs such as pirfenidone and nintedanib as a safe and effective treatment alternative have marked a new chapter in the treatment of IPF. However, nonpharmacological therapies, involving long-term oxygen therapy, transplantation of the lungs, pulmonary rehabilitation, ventilation, and palliative care for cough and dyspnea, are still considered to be beneficial as supplementary methods for IPF therapy. A major risk factor for IPF is aging, with associated hallmarks such as telomere attrition, senescence, epigenetic drift, stem cell exhaustion, loss of proteostasis, and mitochondrial dysfunction. These are promising earmarks for the development of potential therapy for the disease. In this review, we have discussed current and emerging novel therapeutic strategies for IPF, especially for targets associated with age-related mechanisms.

Current and Novel Treatment Modalities of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) presents a clinical challenge characterized by progressive fibrosis and destruction of lung tissue. Despite recent advancements, including antifibrotic medications like pirfenidone and nintedanib, IPF remains a chronic and often fatal condition with limited treatment options. This article provides an overview of the current treatment modalities for IPF and explores the need for new therapeutic approaches. Antifibrotic medications have shown efficacy in slowing disease progression but are not curative and may not be suitable for all patients. Ongoing research focuses on emerging therapies such as stem cell therapy, immunomodulatory agents, and novel pharmacological targets like phosphodiesterase 4B (PDE4B) inhibitors. While these treatments offer promise, there remains an unmet need for effective therapies capable of halting or reversing fibrotic lung damage.

Circular RNAs and their roles in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease with limited treatment options. Circular RNAs (circRNAs) have emerged as a novel class of non-coding RNAs with diverse functions in cellular processes. This review paper aims to explore the potential involvement of circRNAs in the pathogenesis of IPF and their diagnostic and therapeutic implications. We begin by providing an overview of the epidemiology and risk factors associated with IPF, followed by a discussion of the pathophysiology underlying this complex disease. Subsequently, we delve into the history, types, biogenesis, and functions of circRNAs and then emphasize their regulatory roles in the pathogenesis of IPF. Furthermore, we examine the current methodologies for detecting circRNAs and explore their diagnostic applications in IPF. Finally, we discuss the potential utility of circRNAs in the treatment of IPF. In conclusion, circRNAs hold great promise as novel biomarkers and therapeutic targets in the management of IPF.

Integrated bioinformatics analysis for the identification of idiopathic pulmonary fibrosis-related genes and potential therapeutic drugs

OBJECTIVE

The pathogenesis of idiopathic pulmonary fibrosis (IPF) remains unclear. We sought to identify IPF-related genes that may participate in the pathogenesis and predict potential targeted traditional Chinese medicines (TCMs).

METHODS

Using IPF gene-expression data, Wilcoxon rank-sum tests were performed to identify differentially expressed genes (DEGs). Protein-protein interaction (PPI) networks, hub genes, and competitive endogenous RNA (ceRNA) networks were constructed or identified by Cytoscape. Quantitative polymerase chain reaction (qPCR) experiments in TGF-β1-induced human fetal lung (HFL) fibroblast cells and a pulmonary fibrosis mouse model verified gene reliability. The SymMap database predicted potential TCMs targeting IPF. The reliability of TCMs was verified in TGF-β1-induced MRC-5 cells.

MATERIALS

Multiple gene-expression profile data of normal lung and IPF tissues were downloaded from the Gene Expression Omnibus database. HFL fibroblast cells and MRC-5 cells were purchased from Wuhan Procell Life Science and Technology Co., Ltd. (Wuhan, China). C57BL/12 mice were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. (Beijing, China).

RESULTS

In datasets GSE134692 and GSE15197, DEGs were identified using Wilcoxon rank-sum tests (both p < 0.05). Among them, 1885 DEGs were commonly identified, and 87% (1640 genes) had identical dysregulation directions (binomial test, p < 1.00E-16). A PPI network with 1623 nodes and 8159 edges was constructed, and 18 hub genes were identified using the Analyze Network plugin in Cytoscape. Of 18 genes, CAV1, PECAM1, BMP4, VEGFA, FYN, SPP1, and COL1A1 were further validated in the GeneCards database and independent dataset GSE24206. ceRNA networks of VEGFA, SPP1, and COL1A1 were constructed. The genes were verified by qPCR in samples of TGF-β1-induced HFL fibroblast cells and pulmonary fibrosis mice. Finally, Sea Buckthorn and Gnaphalium Affine were predicted as potential TCMs for IPF. The TCMs were verified by qPCR in TGF-β1-induced MRC-5 cells.

CONCLUSION

This analysis strategy may be useful for elucidating novel mechanisms underlying IPF at the transcriptome level. The identified hub genes may play key roles in IPF pathogenesis and therapy.

The Role of Extracellular Vesicles in Idiopathic Pulmonary Fibrosis Progression: An Approach on Their Therapeutics Potential

Idiopathic pulmonary fibrosis (IPF) is a fibrosing interstitial lung disease of unknown etiology. Different types of cells are involved in fibrogenesis, which is persistently physical and molecular stimulation, either directly or by interacting with bioactive molecules and extracellular vesicles (EVs). Current evidence suggests that EVs play an essential role in IPF development. EVs are released by a variety of cells, including fibroblasts, epithelial cells, and alveolar macrophages. In addition, EVs can transport bioactive molecules, such as lipids, proteins, and nucleic acids, which play a pivotal role in cellular communication. Several proposed mechanisms show that an acceptor cell can capture, absorb, or interact with EVs through direct fusion with the plasma membrane, ligand–receptor interaction, and endocytotic process, modifying the target cell. During fibrogenesis, the release of EVs is deregulated, increases the EVs amount, and the cargo content is modified. This alteration is closely associated with the maintenance of the fibrotic microenvironment. This review summarizes the current data on the participation of EVs secreted by the cells playing a critical role in IPF pathogenesis.

Extracellular matrix remodeling associated with bleomycin-induced lung injury supports pericyte-to-myofibroblast transition

Of the many origins of pulmonary myofibroblasts, microvascular pericytes are a known source. Prior literature has established the ability of pericytes to transition into myofibroblasts, but provide limited insight into molecular cues that drive this process during lung injury repair and fibrosis. Fibronectin and RGD-binding integrins have long been considered pro-fibrotic factors in myofibroblast biology, and here we test the hypothesis that these known myofibroblast cues coordinate pericyte-to-myofibroblast transitions. Specifically, we hypothesized that αvβ3 integrin engagement on fibronectin induces pericyte transition into myofibroblastic phenotypes in the murine bleomycin lung injury model. Myosin Heavy Chain 11 (Myh11)-CreERT2 lineage tracing in transgenic mice allows identification of cells of pericyte origin and provides a robust tool for isolating pericytes from tissues for further evaluation. We used this murine model to track and characterize pericyte behaviors during tissue repair. The majority of Myh11 lineage-positive cells are positive for the pericyte surface markers, PDGFRβ (55%) and CD146 (69%), and display typical pericyte morphology with spatial apposition to microvascular networks. After intratracheal bleomycin treatment of mice, Myh11 lineage-positive cells showed significantly increased contractile and secretory markers, as well as αv integrin expression. According to RNASeq measurements, many disease and tissue-remodeling genesets were upregulated in Myh11 lineage-positive cells in response to bleomycin-induced lung injury. In vitro, blocking αvβ3 binding through cycloRGDfK prevented expression of the myofibroblastic marker αSMA relative to controls. In response to RGD-containing provisional matrix proteins present in lung injury, pericytes may alter their integrin profile.

The ER Stress/UPR Axis in Chronic Obstructive Pulmonary Disease and Idiopathic Pulmonary Fibrosis

Cellular protein homeostasis in the lungs is constantly disrupted by recurrent exposure to various external and internal stressors, which may cause considerable protein secretion pressure on the endoplasmic reticulum (ER), resulting in the survival and differentiation of these cell types to meet the increased functional demands. Cells are able to induce a highly conserved adaptive mechanism, known as the unfolded protein response (UPR), to manage such stresses. UPR dysregulation and ER stress are involved in numerous human illnesses, such as metabolic syndrome, fibrotic diseases, and neurodegeneration, and cancer. Therefore, effective and specific compounds targeting the UPR pathway are being considered as potential therapies. This review focuses on the impact of both external and internal stressors on the ER in idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) and discusses the role of the UPR signaling pathway activation in the control of cellular damage and specifically highlights the potential involvement of non-coding RNAs in COPD. Summaries of pathogenic mechanisms associated with the ER stress/UPR axis contributing to IPF and COPD, and promising pharmacological intervention strategies, are also presented.

Idiopathic Pulmonary Fibrosis Registry China study (PORTRAY): protocol for a prospective, multicentre registry study

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal lung disease characterised by a fibrotic histological pattern found in usual interstitial pneumonia. Its causes, pathogenesis, clinical phenotype and molecular mechanisms are poorly defined. Large-scale, multicentre studies are warranted to better understand IPF as a disease in China, its associated risk factors, clinical characteristics, diagnosis, disease progression and treatment.

METHODS AND ANALYSIS

The Idiopathic Pulmonary Fibrosis Registry China Study (PORTRAY) is a prospective, multicentre registry study of patients with IPF in China. Eight hundred patients will be enrolled over a 36-month period and followed for at least 3 years to generate a comprehensive database on baseline characteristics and various follow-up parameters including patient-reported outcomes. Biological specimens will also be collected from patients to develop a library of blood, bronchoalveolar lavage fluid and lung biopsy samples, to support future research. As of 15 December 2019, 204 patients from 19 large medical centres with relatively high IPF diagnosis and treatment rates had been enrolled. Patient characteristics will be presented using descriptive statistics. The Kaplan-Meier method will be used for survival analyses. Repeated measures will be used to compare longitudinal changes in lung function, imaging and laboratory tests. Results following analysis have been projected to be available by July 2025.

ETHICS AND DISSEMINATION

The study protocol was reviewed and approved by the Institutional Review Board from all the study sites currently recruiting patients. Study results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03666234.

Exercise Improves Lung Inflammation, but Not Lung Remodeling and Mechanics in a Model of Bleomycin-Induced Lung Fibrosis

Introduction

Moderate aerobic exercise training accelerates the resolution of lung fibrosis in a model of bleomycin-induced pulmonary fibrosis. However, whether it can inhibit the development of lung fibrosis is unknown.

Materials and Methods

C57Bl/6 mice were distributed into four groups: Control (Co), Exercise (Exe), Bleomycin (Bleo), and Bleomycin+Exercise (Bleo+Exe). A single bleomycin dose (1.5 UI/kg) was administered orotracheally and treadmill exercise started in the same day, enduring for 4 weeks, 5x/week, 60 minutes/session, at moderate intensity. Lung mechanics, systemic and pulmonary inflammation, and lung remodeling were evaluated. Lung homogenates were used to evaluate the antioxidant status.

Results

Total cells, macrophages, lymphocytes, and neutrophils numbers, in agreement with IL-6 levels, were higher in the BAL and serum of Bleo group, compared to other groups. In addition, lung levels of LTB4 in Bleo were higher than other groups, whereas SOD activity and nitric oxide levels in exercised groups (Exe and Exe+Bleo) compared to the Bleo group. Lung GPX activity was lower in Bleo and Exe+Bleo groups compared to others. Exe and Exe+Bleo groups also showed higher IL-10 expression by lung macrophages than other groups, whereas TGF-β expression was higher in Exe, Bleo, and Exe+Bleo groups compared to control. CCR7 expression was induced only in the Exe group. However, exercise did not improve lung remodeling and mechanics, or serum and pulmonary levels of VEGF, IGF-1, and TGF-β.

Conclusion

Aerobic exercise training initiated concomitantly with induction of pulmonary fibrosis reduces lung and systemic inflammation but fails to inhibit lung fibrosis and mechanics impairment.