Progress in Understanding and Treating Idiopathic Pulmonary Fibrosis

Nebulized milk exosomes loaded with siTGF-β1 ameliorate pulmonary fibrosis by inhibiting EMT pathway and enhancing collagen permeability

Pulmonary Fibrosis (PF) is a fatal disease in the interstitial lung associated with high mortality, morbidity, and poor prognosis. Transforming growth factor-β1 (TGF-β1) is a fibroblast-activating protein that promotes fibrous diseases. Herein, an inhalable system was first developed using milk exosomes (M-Exos) encapsulating siRNA against TGF-β1 (MsiTGF-β1), and their therapeutic potential for bleomycin (BLM)-induced PF was investigated. M-siTGF-β1 was introduced into the lungs of mice with PF through nebulization. The collagen penetration effect and lysosomal escape ability were verified in vitro. Inhaled MsiTGF-β1 notably alleviated inflammatory infiltration, attenuated extracellular matrix (ECM) deposition, and increased the survival rate of PF mice by 4.7-fold. M-siTGF-β1 protected lung tissue from BLM toxicity by efficiently delivering specific siRNA to the lungs, leading to TGF-β1 mRNA silencing and epithelial mesenchymal transition pathway inhibition. Therefore, M-siTGF-β1 offers a promising avenue for therapeutic intervention in fibrosis-related disorders.

Realveolarization with inhalable mucus-penetrating lipid nanoparticles for the treatment of pulmonary fibrosis in mice

The stemness loss-associated dysregeneration of impaired alveolar type 2 epithelial (AT2) cells abolishes the reversible therapy of idiopathic pulmonary fibrosis (IPF). We here report an inhalable mucus-penetrating lipid nanoparticle (LNP) for codelivering dual mRNAs, promoting realveolarization via restoring AT2 stemness for IPF treatment. Inhalable LNPs were first formulated with dipalmitoylphosphatidylcholine and our in-house-made ionizable lipids for high-efficiency pulmonary mucus penetration and codelivery of dual messenger RNAs (mRNAs), encoding cytochrome b5 reductase 3 and bone morphogenetic protein 4, respectively. After being inhaled in a bleomycin model, LNPs reverses the mitochondrial dysfunction through ameliorating nicotinamide adenine dinucleotide biosynthesis, which inhibits the accelerated senescence of AT2 cells. Concurrently, pathological epithelial remodeling and fibroblast activation induced by impaired AT2 cells are terminated, ultimately prompting alveolar regeneration. Our data demonstrated that the mRNA-LNP system exhibited high protein expression in lung epithelial cells, which markedly extricated the alveolar collapse and prolonged the survival of fibrosis mice, providing a clinically viable strategy against IPF.

Pharmacological treatment in Idiopathic Pulmonary Fibrosis: current issues and future perspectives

Idiopathic pulmonary fibrosis (IPF) represents a fibrotic interstitial lung disease characterized by uncertain etiology and poor prognosis. Over the years, the path to effective treatments has been marked by a series of advances and setbacks. The introduction of approved antifibrotic drugs, pirfenidone and nintedanib, marked a pivotal moment in the management of IPF. However, despite these advances, these drugs are not curative, although they can slow the natural progression of the disease. The history of drug therapy for IPF goes together with the increased understanding of the pathogenic mechanisms underlying the disease. Based on that, current research efforts continue to explore new therapies, possible personalized treatment strategies, drug combinations, and potential biomarkers for diagnosis and prognosis. In this review, we outline the route that led to the discover of the first effective therapies, ongoing clinical trials, and future directions in the search for more effective treatments.

Association between mosaic loss of chromosome Y and pulmonary fibrosis susceptibility and severity

Background Pulmonary fibrosis (PF) is a rare lung disease with diverse pathogenesis and multiple interconnected underlying biological mechanisms. Mosaic loss of chromosome Y (mLOY) is one of the most common forms of acquired chromosome abnormality in men, which has been reported to be associated with increased risk of various chronic progressive diseases including fibrotic diseases. However, the exact role of mLOY in the development of PF remains elusive and to be elucidated.

Methods

We adopted three complementary approaches to explore the role of mLOY in the pathogenesis of PF. We used copy number on chromosome Y to estimate mLOY comparing patients in PROFILE and gnomAD cohorts and between cases and control patients from the GE100KGP cohort. Correlation of mLOY with demographic and clinical variables was tested using patients from PROFILE cohort. Lung single-cell transcriptomic data were analysed to assess the cell types implicated in mLOY. We performed Mendelian randomisation to examine the causal relationship between mLOY, IPF, and telomere length.

Results

The genetic analysis suggests that mLOY is found in PF from both case cohorts but when compared with an age matched population the effect is minimal (P = 0.0032). mLOY is related to age (P = 0.00021) and shorter telomere length (P = 0.0081) rather than PF severity or progression. Single-cell analysis indicates that mLOY appears to be found primarily in immune cells and appears to be related to presence and severity of fibrosis. Mendelian randomisation demonstrates that mLOY is not on the causal pathway for IPF, but partial evidence supports that telomere shortening is on the causal pathway for mLOY.

Conclusion

Our study confirms the existence of mLOY in PF patients and suggests that mLOY is not a major driver of IPF. The combined evidence suggests a triangulation model where telomere shortening leads to both IPF and mLOY.

Airway basal cell‑derived exosomes suppress epithelial‑mesenchymal transition of lung cells by inhibiting the expression of ANO1

Disruption of the epithelial-mesenchymal transition (EMT) of activated lung cells is an important strategy to inhibit the progression of idiopathic pulmonary fibrosis (IPF). The present study investigated the role of exosomes derived from airway basal cells on EMT of lung cells and elucidate the underlying mechanism. Exosomes were characterized by nanoparticle tracking analysis, transmission electron microscopy imaging and markers detection. The role of exosome on the EMT of lung epithelial cells and lung fibroblasts induced by TGF-β1 was detected. RNA sequencing screened dysregulated genes in exosome-treated group, followed by the bioinformatical analysis. One of the candidates, anoctamin-1 (ANO1), was selected for further gain-and-loss phenotype assays. A bleomycin-induced pulmonary fibrosis model was used to evaluate the treatment effect of exosomes. Exosomes were round-like and positively expressed CD63 and tumor susceptibility gene 101 protein. Treatment with exosomes inhibited the EMT of lung cells activated by TGF-β1. 4158 dysregulated genes were identified in exosome-treated group under the threshold of |log2 fold-change| value >1 and they were involved in the metabolism of various molecules, as well as motility-related biological processes. A key gene, ANO1, was verified by reverse transcription-quantitative PCR, whose overexpression induced the EMT of lung cells. By contrast, ANO1 knockdown reversed the EMT induced by TGF-β1. In vivo assay indicated that exosome treatment ameliorated pulmonary fibrosis and inhibited the upregulation of ANO1 induced by bleomycin. In conclusion, airway basal cell-derived exosomes suppressed the EMT of lung cells via the downregulation of ANO1. These exosomes represent a potential therapeutic option for patients with IPF.

Platelet Activating Factor Receptor and Intercellular Adhesion Molecule-1 Expression Increases in the Small Airway Epithelium and Parenchyma of Patients with Idiopathic Pulmonary Fibrosis: Implications for Microbial Pathogenesis

Background: Idiopathic pulmonary fibrosis (IPF) is an irreversible lung fibrotic disorder of unknown cause. It has been reported that bacterial and viral co-infections exacerbate disease pathogenesis. These pathogens use adhesion molecules such as platelet activating factor receptor (PAFR) and intercellular adhesion molecule-1 (ICAM-1) to gain cellular entry, causing infections. Methods: Immunohistochemical staining was carried out for lung resections from IPF patients (n = 11) and normal controls (n = 12). The quantification of PAFR and ICAM-1 expression is presented as a percentage in the small airway epithelium. Also, type 2 pneumocytes and alveolar macrophages were counted as cells per mm2 of the parenchymal area and presented as a percentage. All image analysis was done using Image Pro Plus 7.0 software. Results: PAFR expression significantly increased in the small airway epithelium (p < 0.0001), type 2 pneumocytes (p < 0.0001) and alveolar macrophages (p < 0.0001) compared to normal controls. Similar trend was observed for ICAM-1 expression in the small airway epithelium (p < 0.0001), type 2 pneumocytes (p < 0.0001) and alveolar macrophages (p < 0.0001) compared to normal controls. Furthermore, the proportion of positively expressed type 2 pneumocytes and alveolar macrophages was higher in IPF than in normal control. Conclusions: This is the first study to show PAFR and ICAM-1 expression in small airway epithelium, type 2 pneumocytes and alveolar macrophages in IPF. These findings could help intervene microbial impact and facilitate management of disease pathogenesis.

Molecular Regulation of Transforming Growth Factor-β1-induced Thioredoxin-interacting Protein Ubiquitination and Proteasomal Degradation in Lung Fibroblasts: Implication in Pulmonary Fibrosis

Thioredoxin-interacting protein (TXNIP) plays a critical role in regulation of cellular redox reactions and inflammatory responses by interacting with thioredoxin (TRX) or the inflammasome. The role of TXNIP in lung fibrosis and molecular regulation of its stability have not been well studied. Therefore, here we investigated the molecular regulation of TXNIP stability and its role in TGF-β1-mediated signaling in lung fibroblasts. TXNIP protein levels were significantly decreased in lung tissues from bleomycin-challenged mice. Overexpression of TXNIP attenuated transforming growth factor-β1 (TGF-β1)-induced phosphorylation of Smad2/3 and fibronectin expression in lung fibroblasts, suggesting that decrease in TXNIP may contribute to the pathogenesis of lung fibrosis. Further, we observed that TGF-β1 lowered TXNIP protein levels, while TXNIP mRNA levels were unaltered by TGF-β1 exposure. TGF-β1 induced TXNIP degradation via the ubiquitin-proteasome system. A serine residue mutant (TNXIP-S308A) was resistant to TGF-β1-induced degradation. Furthermore, downregulationof ubiquitin-specific protease-13 (USP13) promoted the TGF-β1-induced TXNIP ubiquitination and degradation. Mechanistic studies revealed that USP13 targeted and deubiquitinated TXNIP. The results of this study revealed that the decrease of TXNIP in lungs apparently contributes to the pathogenesis of pulmonary fibrosis and that USP13 can target TXNP for deubiquitination and regulate its stability.

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.

Inhaled nanoparticles for treating idiopathic pulmonary fibrosis by inhibiting honeycomb cyst and alveoli interstitium remodeling

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with high mortality. The Food and Drug Administration-approved drugs, nintedanib and pirfenidone, could delay progressive fibrosis by inhibiting the overactivation of fibroblast, however, there was no significant improvement in patient survival due to low levels of drug accumulation and remodeling of honeycomb cyst and interstitium surrounding the alveoli. Herein, we constructed a dual drug (verteporfin and pirfenidone)-loaded nanoparticle (Lip@VP) with the function of inhibiting airway epithelium fluidization and fibroblast overactivation to prevent honeycomb cyst and interstitium remodeling. Specifically, Lip@VP extensively accumulated in lung tissues via atomized inhalation. Released verteporfin inhibited the fluidization of airway epithelium and the formation of honeycomb cyst, and pirfenidone inhibited fibroblast overactivation and reduced cytokine secretion that promoted the fluidization of airway epithelium. Our results indicated that Lip@VP successfully rescued lung function through inhibiting honeycomb cyst and interstitium remodeling. This study provided a promising strategy to improve the therapeutic efficacy for IPF.

Olfactory mucosa mesenchymal stem cells alleviate pulmonary fibrosis via the immunomodulation and reduction of inflammation

BACKGROUND

Pulmonary fibrosis (PF) is a progressive fibrosing interstitial pneumonia that leads to respiratory failure and other complications, which is ultimately fatal. Mesenchymal stem cells (MSCs) transplant is a promising strategy to solve this problem, while the procurement of MSCs from the patient for autotransplant remains a challenge.

METHODS

Here, we presented olfactory mucosa mesenchymal stem cells (OM-MSCs) from mouse turbinate and determined the preventing efficacy of allotransplant for PF. We demonstrated the antiinflammation and immunomodulatory effects of OM-MSCs. Flow cytometric analysis was used to verify the effect of OM-MSCs on monocyte-derived macrophage populations in the lung.

RESULTS

Administration of OM-MSCs reduces inflammation, attenuates the matrix metallopeptidase 13 (MMP13) expression level and restores the bleomycin (BLM)-induced pulmonary fibrosis by assessing the architecture of lung, collagen type I; (COL1A1), actin alpha 2, smooth muscle, aorta (ACTA2/α-SMA) and hydroxyproline. This therapeutic effect of OM-MSCs was related to the increase in the ratio of nonclassical monocytes to proinflammatory monocytes in the lung.

CONCLUSIONS

This study suggests that transplant of OM-MSCs represents an effective and safe treatment for PF.

Homeostatic chemokines as putative therapeutic targets in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal chronic interstitial lung disease (ILD) that affects lung mechanical functions and gas exchange. IPF is caused by increased fibroblast activity and collagen deposition that compromise the alveolar-capillary barrier. Identifying an effective therapy for IPF remains a clinical challenge. Chemokines are key proteins in cell communication that have functions in immunity as well as in tissue homeostasis, damage, and repair. Chemokine receptor signaling induces the activation and proliferation of lung-resident cells, including alveolar macrophages (AMs) and fibroblasts. AMs are an important source of chemokines and cytokines during IPF. We highlight the complexity of this system and, based on insights from genetic and transcriptomic studies, propose a new role for homeostatic chemokine imbalance in IPF, with implications for putative therapeutic targets.

Current and Future Treatment Landscape for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) remains a disease with poor survival. The pathogenesis is complex and encompasses multiple molecular pathways. The first-generation antifibrotics pirfenidone and nintedanib, approved more than 10 years ago, have been shown to reduce the rate of progression, increase the length of life for patients with IPF, and work for other fibrotic lung diseases. In the last two decades, most clinical trials on IPF have failed to meet the primary endpoint and an urgent unmet need remains to identify agents or treatment strategies that can stop disease progression. The pharmacotherapeutic landscape for IPF is moving forward with a number of new drugs currently in clinical development, mostly in phase I and II trials, while only a few phase III trials are running. Since our understanding of IPF pathogenesis is still limited, we should keep focusing our efforts to deeper understand the mechanisms underlying this complex disease and their reflection on clinical phenotypes. This review discusses the key pathogenetic concepts for the development of new antifibrotic agents, presents the newest data on approved therapies, and summarizes new compounds currently in clinical development. Finally, future directions in antifibrotics development are discussed.

Fraxetin alleviates BLM-induced idiopathic pulmonary fibrosis by inhibiting NCOA4-mediated epithelial cell ferroptosis

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a debilitating lung condition with few available treatments. The early driver of wound repair that contributes to IPF has been extensively identified as repetitive alveolar epithelial damage. According to recent reports, IPF is linked to ferroptosis, a unique type of cell death characterized by a fatal buildup of iron and lipid peroxidation.

OBJECTIVE AND METHOD

There is little information on epithelial cells that induce pulmonary fibrosis by going through ferroptosis. In this study, we used bleomycin (BLM) to examine the impact of ferroptosis on IPF in mouse lung epithelial cells (MLE-12).

RESULTS

We discovered that BLM increases ferroptosis in MLE-12. Additionally, we found that NCOA4 is overexpressed and plays a key role in the ferroptosis of epithelial cells throughout the IPF process. Using Molecular docking, we found that Fraxetin, a natural component extracted from Fraxinus rhynchophylla, formed a stable binding to NCOA4. In vitro investigations showed that Fraxetin administration greatly decreased ferroptosis and NCOA4 expression, which in turn lowered the release of inflammatory cytokines.

CONCLUSION

Fraxetin treatment significantly alleviated BLM-induced lung inflammation and fibrosis. Our findings imply that fraxetin possesses inhibitory roles in ferroptosis and can be a potential drug against IPF.

Mapping Genetic Susceptibility to Stenosis in the Proximal Airway

OBJECTIVES

Recent translational scientific efforts in subglottic stenosis (SGS) support a disease model where epithelial alterations facilitate microbiome displacement, dysregulated immune activation, and localized fibrosis. Yet despite recent advances, the genetic basis of SGS remains poorly understood. We sought to identify candidate risk genes associated with an SGS phenotype, investigate their biological function, and identify the cell types enriched for their expression.

METHODS

The Online Mendelian Inheritance in Man (OMIM) database was queried for single gene variants associated with an SGS phenotype. The functional intersections and molecular roles of the identified genes were explored using pathway enrichment analysis (PEA) computational methods. Cellular localization of the candidate risk genes was measured via transcriptional quantification in an established single cell RNA sequencing (scRNA-seq) atlas of the proximal airway.

RESULTS

Twenty genes associated with SGS phenotype were identified. PEA resulted in 24 significantly enriched terms including "cellular response to TGF-β," "epithelial-to-mesenchymal transition," and "adherens junctions." Mapping the 20 candidate risk genes to the scRNA-seq atlas found 3 (15%) genes were enriched in epithelial cells, 3 (15%) in fibroblasts, and 3 (15%) in endothelial cells. 11 (55%) genes were expressed ubiquitously among tissue types. Interestingly, immune cells were not significantly enriched for candidate risk genes.

CONCLUSION

We identify and provide biologic context for 20 genes associated with fibrotic disease of the proximal airway and form the foundation for future detailed genetic study.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:3049-3056, 2023.

Senescence of alveolar epithelial progenitor cells: a critical driver of lung fibrosis

Pulmonary fibrosis comprises a range of chronic interstitial lung diseases (ILDs) that impose a significant burden on patients and public health. Among these, idiopathic pulmonary fibrosis (IPF), a disease of aging, is the most common and most severe form of ILD and is treated largely by lung transplantation. The lack of effective treatments to stop or reverse lung fibrosis-in fact, fibrosis in most organs-has sparked the need to understand causative mechanisms with the goal of identifying critical points for potential therapeutic intervention. Findings from many groups have indicated that repeated injury to the alveolar epithelium-where gas exchange occurs-leads to stem cell exhaustion and impaired alveolar repair that, in turn, triggers the onset and progression of fibrosis. Cellular senescence of alveolar epithelial progenitors is a critical cause of stemness failure. Hence, senescence impairs repair and thus contributes significantly to fibrosis. In this review, we discuss recent evidence indicating that senescence of epithelial progenitor cells impairs alveolar homeostasis and repair creating a profibrotic environment. Moreover, we discuss the impact of senescent alveolar epithelial progenitors, alveolar type 2 (AT2) cells, and AT2-derived transitional epithelial cells in fibrosis. Emerging evidence indicates that transitional epithelial cells are prone to senescence and, hence, are a new player involved in senescence-associated lung fibrosis. Understanding the complex interplay of cell types and cellular regulatory factors contributing to alveolar epithelial progenitor senescence will be crucial to developing targeted therapies to mitigate their downstream profibrotic sequelae and to promote normal alveolar repair.NEW & NOTEWORTHY With an aging population, lung fibrotic diseases are becoming a global health burden. Dysfunctional repair of the alveolar epithelium is a key causative process that initiates lung fibrosis. Normal alveolar regeneration relies on functional progenitor cells; however, the senescence of these cells, which increases with age, hinders their ability to contribute to repair. Here, we discuss studies on the control and consequence of progenitor cell senescence in fibrosis and opportunities for research.

Nanoengineered mesenchymal stem cell therapy for pulmonary fibrosis in young and aged mice

Pulmonary fibrosis (PF) is an age-related interstitial lung disease that results in notable morbidity and mortality. The Food and Drug Administration-approved drugs can decelerate the progression of PF; however, curing aged patients with severe fibrosis is ineffective because of insufficient accumulation of these drugs and wide necrocytosis of type II alveolar epithelial cells (AEC IIs). Here, we constructed a mesenchymal stem cell (MSC)-based nanoengineered platform via the bioconjugation of MSCs and type I collagenase-modified liposomes loaded with nintedanib (MSCs-Lip@NCAF) for treating severe fibrosis. Specifically, MSCs-Lip@NCAF migrated to fibrotic lungs because of the homing characteristic of MSCs and then Lip@NCAF was sensitively released. Subsequently, Lip@NCAF ablated collagen fibers, delivered nintedanib into fibroblasts, and inhibited fibroblast overactivation. MSCs differentiated into AEC IIs to repair alveolar structure and ultimately promote the regeneration of damaged lungs in aged mice. Our findings indicated that MSCs-Lip@NCAF could be used as a promising therapeutic candidate for PF therapy, especially in aged patients.

Oxymatrine inhibits TGF‑β1‑mediated mitochondrial apoptotic signaling in alveolar epithelial cells via activation of PI3K/AKT signaling

Although pulmonary fibrosis (PF) causes respiratory failure and death, effective therapies for PF have not been developed. Oxymatrine (OMT), an active ingredient in the Chinese herb Sophora flavescens, exerts antifibrotic effects; however, its effect on PF remains unclear. The present study aimed to determine whether OMT decreases transforming growth factor-β1 (TGF-β1)-induced PF in human lung cancer A549 cells by inhibiting apoptosis and targeting the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway. To construct a PF cell model, A549 cells were stimulated with TGF-β1. The experimental groups were as follows: control (untreated cells grown in complete medium), TGF-β1 (cells treated with 5 ng/ml TGF-β1), OMT (cells treated with 5 ng/ml TGF-β1 and 0.25, 0.50, or 1.00 mg/ml OMT), and OMT + LY294002 (cells treated with 5 ng/ml TGF-β1, 1.0 mg/ml OMT. and 25 µmol/l LY294002). The effects of OMT on cell morphology (via electron microscopy), apoptosis (via Annexin V-PI staining), mitochondrial apoptosis signaling [using JC-1 method to analyze mitochondrial membrane potential (MMP)], and Bcl-2, as well as Bax expression (via western blotting and reverse transcription-quantitative polymerase chain reaction), were analyzed. OMT significantly protected cells against TGF-β1-induced PF by inhibiting apoptosis. The specific manifestations were cell injury, as evidenced by morphological changes and decreased MMP. Following OMT treatment, the expression of the pro-apoptotic protein Bax increased, whereas that of the anti-apoptotic protein Bcl-2 decreased. The PI3K/AKT-specific inhibitor LY294002 significantly inhibited the ameliorative effects of OMT on TGF-β1-induced apoptosis. Collectively, OMT attenuated TGF-β1-mediated mitochondrial apoptosis of alveolar epithelial cells by activating the PI3K/AKT signaling pathway. Therefore, OMT may be a promising drug for PF treatment.

Lung shrinking assessment on HRCT with elastic registration technique for monitoring idiopathic pulmonary fibrosis

OBJECTIVES

Evaluation and follow-up of idiopathic pulmonary fibrosis (IPF) mainly rely on high-resolution computed tomography (HRCT) and pulmonary function tests (PFTs). The elastic registration technique can quantitatively assess lung shrinkage. We aimed to investigate the correlation between lung shrinkage and morphological and functional deterioration in IPF.

METHODS

Patients with IPF who underwent at least two HRCT scans and PFTs were retrospectively included. Elastic registration was performed on the baseline and follow-up HRCTs to obtain deformation maps of the whole lung. Jacobian determinants were calculated from the deformation fields and after logarithm transformation, log_jac values were represented on color maps to describe morphological deterioration, and to assess the correlation between log_jac values and PFTs.

RESULTS

A total of 69 patients with IPF (male 66) were included. Jacobian maps demonstrated constriction of the lung parenchyma marked at the lung base in patients who were deteriorated on visual and PFT assessment. The log_jac values were significantly reduced in the deteriorated patients compared to the stable patients. Mean log_jac values showed positive correlation with baseline percentage of predicted vital capacity (VC%) (r = 0.394, p < 0.05) and percentage of predicted forced vital capacity (FVC%) (r = 0.395, p < 0.05). Additionally, the mean log_jac values were positively correlated with pulmonary vascular volume (r = 0.438, p < 0.01) and the number of pulmonary vascular branches (r = 0.326, p < 0.01).

CONCLUSIONS

Elastic registration between baseline and follow-up HRCT was helpful to quantitatively assess the morphological deterioration of lung shrinkage in IPF, and the quantitative indicator log_jac values were significantly correlated with PFTs.

KEY POINTS

• The elastic registration on HRCT was helpful to quantitatively assess the deterioration of IPF. • Jacobian logarithm was significantly reduced in deteriorated patients and mean log_jac values were correlated with PFTs. • The mean log_jac values were related to the changes of pulmonary vascular volume and the number of vascular branches.

Arctiin-encapsulated DSPE-PEG bubble-like nanoparticles inhibit alveolar epithelial type 2 cell senescence to alleviate pulmonary fibrosis via the p38/p53/p21 pathway

Background: Idiopathic pulmonary fibrosis is a severe and deadly form of diffuse parenchymal lung disease and treatment options are few. Alveolar epithelial type 2 (AEC2) cell senescence is implicated in the pathogenies of IPF. A major bioactive compound from the traditional Chinese medicine Fructus arctii, arctiin (ARC) has robust anti-inflammatory, anti-senescence, and anti-fibrosis functions. However, the potential therapeutic effects of ARC on IPF and the underlying mechanisms involved are still unknown.

Methods: First of all, ARC was identified as an active ingredient by network pharmacology analysis and enrichment analysis of F. arctii in treating IPF. We developed ARC-encapsulated DSPE-PEG bubble-like nanoparticles (ARC@DPBNPs) to increase ARC hydrophilicity and achieve high pulmonary delivery efficiency. C57BL/6 mice were used to establish a bleomycin (BLM)-induced pulmonary fibrosis model for assessing the treatment effect of ARC@DPBNPs on lung fibrosis and the anti-senescence properties of AEC2. Meanwhile, p38/p53 signaling in AEC2 was detected in IPF lungs, BLM-induced mice, and an A549 senescence model. The effects of ARC@DPBNPs on p38/p53/p21 were assessed in vivo and in vitro.

Results: Pulmonary route of administration of ARC@DPBNPs protected mice against BLM-induced pulmonary fibrosis without causing significant damage to the heart, liver, spleen, or kidney. ARC@DPBNPs blocked BLM-induced AEC2 senescence in vivo and in vitro. The p38/p53/p21 signaling axis was significantly activated in the lung tissues of patients with IPF, senescent AEC2, and BLM-induced lung fibrosis. ARC@DPBNPs attenuated AEC2 senescence and pulmonary fibrosis by inhibiting the p38/p53/p21 pathway.

Conclusion: Our data suggest that the p38/p53/p21 signaling axis plays a pivotal role in AEC2 senescence in pulmonary fibrosis. The p38/p53/p21 signaling axis inhibition by ARC@DPBNPs provides an innovative approach to treating pulmonary fibrosis in clinical settings.

Cellular and Molecular Mechanisms in Idiopathic Pulmonary Fibrosis

The respiratory system is a well-organized multicellular organ, and disruption of cellular homeostasis or abnormal tissue repair caused by genetic deficiency and exposure to risk factors lead to life-threatening pulmonary disease including idiopathic pulmonary fibrosis (IPF). Although there is no clear etiology as the name reflected, its pathological progress is closely related to uncoordinated cellular and molecular signals. Here, we review the advances in our understanding of the role of lung tissue cells in IPF pathology including epithelial cells, mesenchymal stem cells, fibroblasts, immune cells, and endothelial cells. These advances summarize the role of various cell components and signaling pathways in the pathogenesis of idiopathic pulmonary fibrosis, which is helpful to further study the pathological mechanism of the disease, provide new opportunities for disease prevention and treatment, and is expected to improve the survival rate and quality of life of patients.

Therapeutic Effects of Omentin-1 on Pulmonary Fibrosis by Attenuating Fibroblast Activation via AMP-Activated Protein Kinase Pathway

Idiopathic pulmonary fibrosis (IPF) is a fatal age-related chronic lung disease, characterized by progressive scarring of the lungs by activated fibroblasts. The effect of omentin-1 against pulmonary fibrosis and fibroblast activation has not been investigated. The purpose of this experiment is to investigate the role of omentin-1 in bleomycin (BLM)-induced lung fibrosis and its mechanism. Our results showed that the loss of omentin-1 exaggerated lung fibrosis induced by BLM. On the contrary, adenoviral-overexpression of omentin-1 significantly alleviated BLM-induced lung fibrosis both in preventive and therapeutic regimens. Moreover, omentin-1 prevented fibroblast activation determined by a decreased number of S100A4+ (fibroblasts marker) α-SMA+ cells in vivo, and a decreased level of α-SMA expression both in mice primary fibroblasts and human primary fibroblasts induced by TGF-β in vitro. Furthermore, the phosphorylation of AMP-activated protein kinase (p-AMPK) was significantly lower in the fibrotic foci induced by BLM, and the adenoviral-overexpression of omentin-1 significantly increased the p-AMPK level in vivo. Importantly, Compound C, the inhibitor of AMPK, significantly attenuated the protective effect of omentin-1 on BLM-induced lung fibrosis and reversed the effect of omentin-1 on fibroblast activation by TGF-β. Omentin-1 can be a promising therapeutic agent for the prevention and treatment of lung fibrosis.

The potential benefit of endothelin receptor antagonists' therapy in idiopathic pulmonary fibrosis: A meta-analysis of results from randomized controlled trials

BACKGROUND

Fibrotic diseases take a very heavy toll in terms of morbidity and mortality equal to or even greater than that caused by metastatic cancer. This meta-analysis aimed to evaluate the effect of endothelin receptor antagonists on idiopathic pulmonary fibrosis.

METHOD

A systematic search of the clinical trials from the Medline, Google Scholar, Cochrane Library, and PubMed electronic databases was performed. Stata version 12.0 statistical software (Stata Crop LP, College Station, TX) was adopted as statistical software.

RESULT

A total of 5 studies, which included 1500 participants. Our analysis found there is no significant difference between using the endothelin receptor antagonists' group and placebo groups regarding the lung function via estimating both the change of forced vital capacity from baseline and DLco index. Exercise capacity and serious adverse effects are taken into consideration as well; however, there is still no significant change between the 2 groups.

CONCLUSION

This meta-analysis provides insufficient evidence to support that endothelin receptor antagonists' administration provides a benefit among included participants who encounter idiopathic pulmonary fibrosis.

Biology of lung macrophages in health and disease

Tissue-resident alveolar and interstitial macrophages and recruited macrophages are critical players in innate immunity and maintenance of lung homeostasis. Until recently, assessing the differential functional contributions of tissue-resident versus recruited macrophages has been challenging because they share overlapping cell surface markers, making it difficult to separate them using conventional methods. This review describes how scRNA-seq and spatial transcriptomics can separate these subpopulations and help unravel the complexity of macrophage biology in homeostasis and disease. First, we provide a guide to identifying and distinguishing lung macrophages from other mononuclear phagocytes in humans and mice. Second, we outline emerging concepts related to the development and function of the various lung macrophages in the alveolar, perivascular, and interstitial niches. Finally, we describe how different tissue states profoundly alter their functions, including acute and chronic lung disease, cancer, and aging.

Inhaled siRNA nanoparticles targeting IL11 inhibit lung fibrosis and improve pulmonary function post-bleomycin challenge

Interleukin-11 (IL-11) is a profibrotic cytokine essential for the differentiation of fibroblasts into collagen-secreting, actin alpha 2, smooth muscle-positive (ACTA2⁺) myofibroblasts, driving processes underlying the pathogenesis of idiopathic pulmonary fibrosis (IPF). Here, we developed an inhalable and mucus-penetrative nanoparticle (NP) system incorporating siRNA against IL11 (siIL11@PPGC NPs) and investigated therapeutic potential for the treatment of IPF. NPs are formulated through self-assembly of a biodegradable PLGA-PEG diblock copolymer and a self-created cationic lipid-like molecule G0-C14 to enable efficient transmucosal delivery of siIL11. Noninvasive aerosol inhalation hindered fibroblast differentiation and reduced ECM deposition via inhibition of ERK and SMAD2. Furthermore, siIL11@PPGC NPs significantly diminished fibrosis development and improved pulmonary function in a mouse model of bleomycin-induced pulmonary fibrosis without inducing systemic toxicity. This work presents a versatile NP platform for the locally inhaled delivery of siRNA therapeutics and exhibits promising clinical potential in the treatment of numerous respiratory diseases, including IPF.

Role of Ferroptosis in Fibrotic Diseases

Ferroptosis is a unique and pervasive form of regulated cell death driven by iron-dependent phospholipid peroxidation. It results from disturbed cellular metabolism and imbalanced redox homeostasis and is regulated by various cellular metabolic pathways. Recent preclinical studies have revealed that ferroptosis may be an attractive therapeutic target in fibrotic diseases, such as liver fibrosis, pulmonary fibrosis, kidney fibrosis, and myocardial fibrosis. This review summarizes the latest knowledge on the regulatory mechanism of ferroptosis and its roles in fibrotic diseases. These updates may provide a novel perspective for the treatment of fibrotic diseases as well as future research.

Prognostic Role of NLR, PLR and MHR in Patients With Idiopathic Pulmonary Fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease with low survival time. Since the pathophysiological progression of IPF is closely associated with immunological and inflammatory responses, immune biomarkers, including neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), and monocyte-high density lipoprotein ratio (MHR), have the potential to predict overall survival in IPF patients.

Methods

A total of 278 patients with IPF were finally enrolled. The demographic and clinical characteristics of the patients at baseline were recorded. Multivariable Cox regression analysis was used to evaluate the association between the three biomarkers and overall survival in both the total cohort and acute exacerbation subgroup.

Results

The median follow-up was 5.84 months. After adjusting for confounders, we found that only elevated NLR was associated with worse overall survival (OR = 1.019, 95% CI 1.001-1.037, P =0.041) by using multivariable Cox regression analysis. In 116 acute exacerbation IPF patients, the results of the Cox multiple regression model also indicated that the NLR was a significant prognostic factor (OR= 1.022, 95% CI 1.001-1.044, P =0.036). The NLR before death was also significantly higher than that at admission in nonsurvival acute exacerbation IPF patients (P=0.014). No significant differences were found in PLR (P=0.739) or MHR changes (P=0.478).

Conclusions

Our results indicated that elevated NLR expression is associated with shorter overall survival in IPF patients, which is independent of other prognostic factors. The NLR may be regarded as a reliable prognostic biomarker for IPF patients.

Gefitinib and fostamatinib target EGFR and SYK to attenuate silicosis: a multi-omics study with drug exploration

Silicosis is the most prevalent and fatal occupational disease with no effective therapeutics, and currently used drugs cannot reverse the disease progress. Worse still, there are still challenges to be addressed to fully decipher the intricated pathogenesis. Thus, specifying the essential mechanisms and targets in silicosis progression then exploring anti-silicosis pharmacuticals are desperately needed. In this work, multi-omics atlas was constructed to depict the pivotal abnormalities of silicosis and develop targeted agents. By utilizing an unbiased and time-resolved analysis of the transcriptome, proteome and phosphoproteome of a silicosis mouse model, we have verified the significant differences in transcript, protein, kinase activity and signaling pathway level during silicosis progression, in which the importance of essential biological processes such as macrophage activation, chemotaxis, immune cell recruitment and chronic inflammation were emphasized. Notably, the phosphorylation of EGFR (p-EGFR) and SYK (p-SYK) were identified as potential therapeutic targets in the progression of silicosis. To inhibit and validate these targets, we tested fostamatinib (targeting SYK) and Gefitinib (targeting EGFR), and both drugs effectively ameliorated pulmonary dysfunction and inhibited the progression of inflammation and fibrosis. Overall, our drug discovery with multi-omics approach provides novel and viable therapeutic strategies for the treatment of silicosis.

ASK1 Regulates Bleomycin-induced Pulmonary Fibrosis

Pulmonary fibrosis (PF) is an abnormal remodeling of cellular composition and extracellular matrix that results in histological and functional alterations in the lungs. Apoptosis signal-regulating kinase-1 (ASK1) is a member of the mitogen-activated protein (MAP) kinase family that is activated by oxidative stress and promotes inflammation and apoptosis. Here we show that bleomycin-induced PF is reduced in Ask1 knockout mice (Ask1^-/-) compared with wild-type (WT) mice, with improved survival and histological and functional parameters restored to basal levels. In WT mice, bleomycin caused activation of ASK1, p38, and extracellular signal-regulated kinase 1/2 (ERK1/2) in lung tissue, as well as changes in redox indicators (thioredoxin and heme-oxygenase-1), collagen content, and epithelial-mesenchymal transition markers (EMTs). These changes were largely restored toward untreated WT control levels in bleomycin-treated Ask1^-/- mice. We further investigated whether treatment of WT mice with an ASK1 inhibitor, selonsertib (GS-4997), during the fibrotic phase would attenuate the development of PF. We found that pharmacological inhibition of ASK1 reduced activation of ASK1, p38, and ERK1/2 and promoted the restoration of redox and EMT indicators, as well as improvements in histological parameters. Our results suggest that ASK1 plays a central role in the development of bleomycin-induced PF in mice via p38 and ERK1/2 signaling. Together, these data indicate a possible therapeutic target for PF that involves an ASK1/p38/ERK1/2 axis.

Lung Injury Induces Alveolar Type 2 Cell Hypertrophy and Polyploidy with Implications for Repair and Regeneration

Epithelial polyploidization after injury is a conserved phenomenon recently shown to improve barrier restoration during wound healing. Whether lung injury can induce alveolar epithelial polyploidy is not known. We show that bleomycin injury induces alveolar type 2 cell (AT2) hypertrophy and polyploidy. AT2 polyploidization is also seen in short term ex vivo cultures, where AT2-to-AT1 transdifferentiation is associated with substantial binucleation due to failed cytokinesis. Both hypertrophic and polyploid features of AT2 cells can be attenuated by inhibiting the integrated stress response using the small molecule ISRIB. These data suggest that AT2 hypertrophic growth and polyploidization may be a feature of alveolar epithelial injury. Because AT2 cells serve as facultative progenitors for the distal lung epithelium, a propensity for injury-induced binucleation has implications for AT2 self-renewal and regenerative potential upon reinjury, which may benefit from targeting the integrated stress response.

Multi-Omics Integrative Approach of Extracellular Vesicles: A Future Challenging Milestone

In the era of multi-omic sciences, dogma on singular cause-effect in physio-pathological processes is overcome and system biology approaches have been providing new perspectives to see through. In this context, extracellular vesicles (EVs) are offering a new level of complexity, given their role in cellular communication and their activity as mediators of specific signals to target cells or tissues. Indeed, their heterogeneity in terms of content, function, origin and potentiality contribute to the cross-interaction of almost every molecular process occurring in a complex system. Such features make EVs proper biological systems being, therefore, optimal targets of omic sciences. Currently, most studies focus on dissecting EVs content in order to either characterize it or to explore its role in various pathogenic processes at transcriptomic, proteomic, metabolomic, lipidomic and genomic levels. Despite valuable results being provided by individual omic studies, the categorization of EVs biological data might represent a limit to be overcome. For this reason, a multi-omic integrative approach might contribute to explore EVs function, their tissue-specific origin and their potentiality. This review summarizes the state-of-the-art of EVs omic studies, addressing recent research on the integration of EVs multi-level biological data and challenging developments in EVs origin.

LncRNA DACH1 protects against pulmonary fibrosis by binding to SRSF1 to suppress CTNNB1 accumulation

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with unknown etiology and limited therapeutic options. Activation of fibroblasts is a prominent feature of pulmonary fibrosis. Here we report that lncRNA DACH1 (dachshund homolog 1) is downregulated in the lungs of IPF patients and in an experimental mouse model of lung fibrosis. LncDACH1 knockout mice develop spontaneous pulmonary fibrosis, whereas overexpression of LncDACH1 attenuated TGF-β1-induced aberrant activation, collagen deposition and differentiation of mouse lung fibroblasts. Similarly, forced expression of LncDACH1 not only prevented bleomycin (BLM)-induced lung fibrosis, but also reversed established lung fibrosis in a BLM model. Mechanistically, LncDACH1 binding to the serine/arginine-rich splicing factor 1 (SRSF1) protein decreases its activity and inhibits the accumulation of Ctnnb1. Enhanced expression of SRSF1 blocked the anti-fibrotic effect of LncDACH1 in lung fibroblasts. Furthermore, loss of LncDACH1 promoted proliferation, differentiation, and extracellular matrix (ECM) deposition in mouse lung fibroblasts, whereas such effects were abolished by silencing of Ctnnb1. In addition, a conserved fragment of LncDACH1 alleviated hyperproliferation, ECM deposition and differentiation of MRC-5 cells driven by TGF-β1. Collectively, LncDACH1 inhibits lung fibrosis by interacting with SRSF1 to suppress CTNNB1 accumulation, suggesting that LncDACH1 might be a potential therapeutic target for pulmonary fibrosis.

Anti-PD-L1 antibody alleviates pulmonary fibrosis by inducing autophagy via inhibition of the PI3K/Akt/mTOR pathway

Pulmonary fibrosis is a fatal lung disease for which no effective treatment is available. Previous studies have shown that the expression of programmed cell death-Ligand (PD-L1) is significantly increased in pulmonary fibrosis, and that this is related to the occurrence of this disease. However, the underlying mechanism is not clear. To clarify the efficacy and mechanism of an anti-PD-L1 monoclonal antibody (anti-PD-L1 mAb) as a treatment for pulmonary fibrosis, we conducted histopathological, molecular, and functional analyses in a mouse model of bleomycin-induced pulmonary fibrosis and a cell model of fibrosis induced by transforming growth factor-beta 1 (TGF-β1). Our results indicate that PD-L1 is highly expressed in the lung fibrosis model. The anti-PD-L1 mAb significantly alleviated bleomycin-induced lung structural disorders and collagen deposition in mice and inhibited the proliferation, migration, activation and extracellular matrix deposition of TGF-β1-induced lung fibroblasts. Interestingly, the anti-PD-L1 mAb could also alleviate the autophagy impairment observed in pulmonary fibrosis. The potential mechanism is through the downregulation of the PI3K/Akt/mTOR signaling pathway. Our study provides evidence of the crucial ability of anti-PD-L1 mAbs to activate autophagy in the context of pulmonary fibrosis, providing a new strategy for the treatment of this disease.

Protective Effects of the Wenfei Buqi Tongluo Formula on the Inflammation in Idiopathic Pulmonary Fibrosis through Inhibiting the TLR4/MyD88/NF-κB Pathway

Background. Idiopathic pulmonary fibrosis (IPF) is a progressive disease with high mortality and poor prognosis. The prognostic signatures related to conventional therapy response remain limited. The Wenfei Buqi Tongluo (WBT) formula, a traditional Chinese medicine (TCM) formula, has been widely utilized to treat respiratory diseases in China, which is particularly effective in promoting inflammatory absorption. In this study, we aim to explore the mechanism of the WBT formula in the inhibition of inflammatory response during IPF, based on network pharmacology and in vivo experiments. Methods. Network pharmacology was applied to predict the changes of biological processes and potential pathways for the WBT formula against IPF. Histopathological changes, inflammatory factors (IL-6, IL-1β, and TNF-α), and the proteins of the TLR4/MyD88/NF-κB pathway in bleomycin- (BLM-) induced mice model were examined by hematoxylin-eosin (H&E), Masson or immunohistochemistry staining, Western blot, and enzyme-linked immunosorbent assay analysis. Results. A total of 163 possible components and 167 potential targets between the WBT formula and IPF were obtained. The enrichments of network pharmacology showed that inflammation response, TNF, and NF-κB pathways were involved in the treatment of WBT against IPF. The in vivo experiments indicated that the WBT formula could ameliorate inflammatory exudation and collagen deposition at a histopathology level in the BLM-induced mice model. The levels of IL-6, IL-1β, and TNF-α were reduced after the WBT formula treatment. Moreover, the expressions of phosphorylated-NF-κB p65, TLR4, and MyD88 were significantly downregulated by the WBT formula, compared with the BLM-induced group. Conclusion. These results indicated that the WBT formula can suppress BLM-induced IPF in a mouse model by inhibiting the inflammation via the TLR4/MyD88/NF-κB pathway. This study provides a new insight into the molecular mechanisms of the WBT formula in the application at the clinic.

Distinct roles of KLF4 in mesenchymal cell subtypes during lung fibrogenesis

During lung fibrosis, the epithelium induces signaling to underlying mesenchyme to generate excess myofibroblasts and extracellular matrix; herein, we focus on signaling in the mesenchyme. Our studies indicate that platelet-derived growth factor receptor (PDGFR)-β⁺ cells are the predominant source of myofibroblasts and Kruppel-like factor (KLF) 4 is upregulated in PDGFR-β⁺ cells, inducing TGFβ pathway signaling and fibrosis. In fibrotic lung patches, KLF4 is down-regulated, suggesting KLF4 levels decrease as PDGFR-β⁺ cells transition into myofibroblasts. In contrast to PDGFR-β⁺ cells, KLF4 reduction in α-smooth muscle actin (SMA)⁺ cells non-cell autonomously exacerbates lung fibrosis by inducing macrophage accumulation and pro-fibrotic effects of PDGFR-β⁺ cells via a Forkhead box M1 to C-C chemokine ligand 2-receptor 2 pathway. Taken together, in the context of lung fibrosis, our results indicate that KLF4 plays opposing roles in PDGFR-β⁺ cells and SMA⁺ cells and highlight the importance of further studies of interactions between distinct mesenchymal cell types.

Genetics and animal models of familial pulmonary fibrosis

Pulmonary fibrosis is caused by the interplay between genetic and environmental factors. Recent studies have revealed various genes associated with idiopathic pulmonary fibrosis, as well as the causative genes for familial pulmonary fibrosis. Although increased death or dysfunction of type 2 alveolar epithelial (AT2) cells has been detected in lung specimens from pulmonary fibrosis patients, it remains unclear whether and how AT2 cell death or dysfunction is responsible for the progression of pulmonary fibrosis. A recent study showed that increased AT2 cell necroptosis is the initial event in pulmonary fibrosis by analyzing patients with familial pulmonary fibrosis and an animal model that harbors the same mutation as patients. The contribution of AT2 cell necroptosis to the pathogenesis of pulmonary fibrosis has not been identified in animal model studies, which validates the effectiveness of genetic analysis of familial diseases to uncover unknown pathogeneses. Thus, further extensive genetic studies of pulmonary fibrosis along with functional studies based on genetic analysis will be crucial not only in elucidating the precise disease process but also, ultimately, in identifying novel treatment strategies for both familial and non-familial pulmonary fibrosis.

The Role of Hippo/YAP Signaling in Alveolar Repair and Pulmonary Fibrosis

Pulmonary fibrosis is characterized by loss of normal alveoli, accumulation of pathologic activated fibroblasts, and exuberant extracellular matrix deposition that over time can lead to progressive loss of respiratory function and death. This loss of respiratory function is associated with the loss of alveolar type 1 cells (AT1) that play a crucial role in gas exchange and the depletion of the alveolar type 2 cells (AT2) that act as progenitor cells to regenerate the AT1 and AT2 cell populations during repair. Understanding the mechanisms that regulate normal alveolar repair and those associated with pathologic repair is essential to identify potential therapeutic targets to treat or delay progression of fibrotic diseases. The Hippo/YAP developmental signaling pathway has been implicated as a regulator of normal alveolar development and repair. In idiopathic pulmonary fibrosis, aberrant activation of YAP/TAZ has been demonstrated in both the alveolar epithelium and activated fibroblasts associated with increased fibrotic remodeling, and there is emerging interest in this pathway as a target for antifibrotic therapies. In this review, we summarize current evidence as to the role of the Hippo-YAP/TAZ pathway in alveolar development, homeostasis, and repair, and highlight key questions that must be resolved to determine effective strategies to modulate YAP/TAZ signaling to prevent progressive pulmonary fibrosis and enhance adaptive alveolar repair.

A phycocyanin derived eicosapeptide attenuates lung fibrosis development

Pulmonary fibrosis (PF) is a progressive respiratory disease. Phycocyanin derived eicosapeptide (PP20) is a novel peptide derived from active protein C-phycocyanin in Cyanobacteria. The aim of our study was to explore the anti-fibrotic activity of the PP20 and its underlying mechanism. Characteristic features of pulmonary fibrosis in oleic acid (OA)-induced mice and epithelial-mesenchymal transition (EMT) in TGF-β1-exposed A549 and HFL-1 cells with or without PP20 and the change of TGF-β/Smad and MAPK signaling pathways were examined. Smad and MAPK agonists were used to explore the role of TGF-β/Smad and MAPK signaling in TGF-β1- induced collagen I expression in A549 cells and α-SMA expression in HFL-1 cells when treated with PP20. Our results showed that PP20 significantly alleviated the inflammatory response and tissue destruction, inhibited EMT, restored the imbalance of TIMP-1/MMP-9 and reduced collagen fiber deposition. Moreover, PP20 inhibited TGF-β1-induced EMT and collagen I expression in A549 cells. PP20 could also inhibit the proliferation, and decrease TGF-β1-induced the expression of collagen I and transformation of fibroblasts into myofibroblasts in HFL-1 cells. Additionally, animal experiments and cell experiments combined with pathway agonists have shown that PP20 can negatively regulate TGF-β/Smad and MAPK pathways and show anti-fibrotic properties. PP20 may be a promising drug candidate for protection against pulmonary fibrosis.

Ion therapy of pulmonary fibrosis by inhalation of ionic solution derived from silicate bioceramics

Pulmonary fibrosis (PF) is a chronic and progressively fatal disease, but clinically available therapeutic drugs are limited due to efficacy and side effects. The possible mechanism of pulmonary fibrosis includes the damage of alveolar epithelial cells II (AEC2), and activation of immune cells such as macrophages. The ions released from bioceramics have shown the activity in stimulating soft tissue derived cells such as fibroblasts, endothelia cells and epithelia cells, and regulating macrophage polarization. Therefore, this study proposes an "ion therapy" approach based on the active ions of bioceramic materials, and investigates the therapeutic effect of bioactive ions derived from calcium silicate (CS) bioceramics on mouse models of pulmonary fibrosis. We demonstrate that silicate ions significantly reduce pulmonary fibrosis by simultaneously regulating the functions of AEC2 and macrophages. This result suggests potential clinical applications of ion therapy for lung fibrosis.

Mangostanin Derivatives as Novel and Orally Active Phosphodiesterase 4 Inhibitors for the Treatment of Idiopathic Pulmonary Fibrosis with Improved Safety

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease, and its incidence rate is rapidly rising. However, effective therapies for the treatment of IPF are still lacking. Phosphodiesterase 4 (PDE4) inhibitors were reported to be potential anti-fibrotic agents, but their clinical use was hampered by side effects like emesis and nausea. Herein, structure-based hit-to-lead optimizations of natural mangostanin resulted in the novel and orally active PDE4 inhibitor 18a with potent inhibitory affinity (IC50 = 4.2 nM), favorable physico-chemical properties, and a different binding pattern from roflumilast. Emetic activity tests on dogs demonstrated that 18a cannot cause emesis even at an oral dose of 10 mg/kg, whereas rolipram had severe emetic effects at an oral dose of 1 mg/kg. Finally, the oral administration of 18a (10 mg/kg) exhibited comparable anti-pulmonary fibrosis effects with pirfenidone (150 mg/kg) in a bleomycin-induced IPF rat model, indicating its potential as a novel anti-IPF agent with improved safety.

PTX3 Regulation of Inflammation, Hemostatic Response, Tissue Repair, and Resolution of Fibrosis Favors a Role in Limiting Idiopathic Pulmonary Fibrosis

PTX3 is a soluble pattern recognition molecule (PRM) belonging to the humoral innate immune system, rapidly produced at inflammatory sites by phagocytes and stromal cells in response to infection or tissue injury. PTX3 interacts with microbial moieties and selected pathogens, with molecules of the complement and hemostatic systems, and with extracellular matrix (ECM) components. In wound sites, PTX3 interacts with fibrin and plasminogen and favors a timely removal of fibrin-rich ECM for an efficient tissue repair. Idiopathic Pulmonary Fibrosis (IPF) is a chronic and progressive interstitial lung disease of unknown origin, associated with excessive ECM deposition affecting tissue architecture, with irreversible loss of lung function and impact on the patient’s life quality. Maccarinelli et al. recently demonstrated a protective role of PTX3 using the bleomycin (BLM)-induced experimental model of lung fibrosis, in line with the reported role of PTX3 in tissue repair. However, the mechanisms and therapeutic potential of PTX3 in IPF remained to be investigated. Herein, we provide new insights on the possible role of PTX3 in the development of IPF and BLM-induced lung fibrosis. In mice, PTX3-deficiency was associated with worsening of the disease and with impaired fibrin removal and subsequently increased collagen deposition. In IPF patients, microarray data indicated a down-regulation of PTX3 expression, thus suggesting a potential rational underlying the development of disease. Therefore, we provide new insights for considering PTX3 as a possible target molecule underlying therapeutic intervention in IPF.

Active Components from Traditional Herbal Medicine for the Potential Therapeutics of Idiopathic Pulmonary Fibrosis: A Systemic Review

Idiopathic pulmonary fibrosis (IPF), a tumor-like disease, is a serious and fatal pulmonary inflammatory condition usually characterized by irreversible destruction of the lung parenchyma, excessive matrix accumulation, and decline in lung function. IPF still remains a great burden to the universe. At the moment, the available therapeutic regimens utilized for IPF such as non-pharmacological therapies (lung transplantation) and pharmacological therapies (drugs, nintedanib, pirfenidone, etc.) are normally accompanied by significant limitations, such as adverse reactions, low bioavailability, poor selectivity, low-tissue distribution, in vivo instability, systemic toxicity, inconveniency and unsafe usage. There is a need for the exploration and discovery of new novel remedies by researchers and scientists globally. Recent numerous preliminary studies have laid significant emphasis and demonstrated the antifibrotic importance, good curative actions (little or no adverse reactions), and multiple target sites of the active components from traditional herbal medicine (THM) against IPF, which could serve as a modern, alternative and potential therapeutics or drug candidates in treating IPF. This paper extensively summarizes the pharmacological actions and signaling pathways or mechanisms of active components obtained from THM for treating IPF. Moreover, the sources and modernization, markets, relevant FDA and CFDA studies (the USA and China), preclinical analysis, and various compositions of THM currently under clinical trials are also highlighted. Additionally, this present analytical data would be instrumental towards further drug progression or advancement of active components from THM for the potential therapeutics of IPF in the future.

Resetting proteostasis with ISRIB promotes epithelial differentiation to attenuate pulmonary fibrosis

Pulmonary fibrosis is a relentlessly progressive and often fatal disease with a paucity of available therapies. Genetic evidence implicates disordered epithelial repair, which is normally achieved by the differentiation of small cuboidal alveolar type 2 (AT2) cells into large, flattened alveolar type 1 (AT1) cells as an initiating event in pulmonary fibrosis pathogenesis. Using models of pulmonary fibrosis in young adult and old mice and a model of adult alveologenesis after pneumonectomy, we show that administration of ISRIB, a small molecule that restores protein translation by EIF2B during activation of the integrated stress response (ISR), accelerated the differentiation of AT2 into AT1 cells. Accelerated epithelial repair reduced the recruitment of profibrotic monocyte-derived alveolar macrophages and ameliorated lung fibrosis. These findings suggest a dysfunctional role for the ISR in regeneration of the alveolar epithelium after injury with implications for therapy.

Pretreatment of aged mice with retinoic acid supports alveolar regeneration via upregulation of reciprocal PDGFA signalling

OBJECTIVES

Idiopathic pulmonary fibrosis (IPF) primarily affects the aged population and is characterised by failure of alveolar regeneration, leading to loss of alveolar type 1 (AT1) cells. Aged mouse models of lung repair have demonstrated that regeneration fails with increased age. Mouse and rat lung repair models have shown retinoic acid (RA) treatment can restore alveolar regeneration. Herein, we seek to determine the signalling mechanisms that become activated on RA treatment prior to injury, which support alveolar differentiation.

DESIGN

Partial pneumonectomy lung injury model and next-generation sequencing of sorted cell populations were used to uncover molecular targets regulating alveolar repair. In vitro organoids generated from epithelial cells of mouse or patient with IPF co-cultured with young, aged or RA-pretreated murine fibroblasts were used to test potential targets.

MAIN OUTCOME MEASUREMENTS

Known alveolar epithelial cell differentiation markers, including HOPX and AGER for AT1 cells, were used to assess outcome of treatments.

RESULTS

Gene expression analysis of sorted fibroblasts and epithelial cells isolated from lungs of young, aged and RA-pretreated aged mice predicted increased platelet-derived growth factor subunit A (PDGFA) signalling that coincided with regeneration and alveolar epithelial differentiation. Addition of PDGFA induced AT1 and AT2 differentiation in both mouse and human IPF lung organoids generated with aged fibroblasts, and PDGFA monoclonal antibody blocked AT1 cell differentiation in organoids generated with young murine fibroblasts.

CONCLUSIONS

Our data support the concept that RA indirectly induces reciprocal PDGFA signalling, which activates regenerative fibroblasts that support alveolar epithelial cell differentiation and repair, providing a potential therapeutic strategy to influence the pathogenesis of IPF.

Dopamine receptor agonists ameliorate bleomycin-induced pulmonary fibrosis by repressing fibroblast differentiation and proliferation

Idiopathic pulmonary fibrosis (IPF) is the most common fatal interstitial lung disease, with limited therapeutic options. The abnormal and uncontrolled differentiation and proliferation of fibroblasts have been confirmed to play a crucial role in driving the pathogenesis of IPF. Therefore, effective and well-tolerated antifibrotic agents that interfere with fibroblasts would be an ideal treatment, but no such treatments are available. Remarkably, we found that dopamine (DA) receptor D1 (D1R) and DA receptor D2 (D2R) were both upregulated in myofibroblasts in lungs of IPF patients and a bleomycin (BLM)-induced mouse model. Then, we explored the safety and efficacy of DA, fenoldopam (FNP, a selective D1R agonist) and sumanirole (SMR, a selective D2R agonist) in reversing BLM-induced pulmonary fibrosis. Further data showed that DA receptor agonists exerted potent antifibrotic effects in BLM-induced pulmonary fibrosis by attenuating the differentiation and proliferation of fibroblasts. Detailed pathway analysis revealed that DA receptor agonists decreased the phosphorylation of Smad2 induced by TGF-β1 in primary human lung fibroblasts (PHLFs) and IMR-90 cells. Overall, DA receptor agonists protected mice from BLM-induced pulmonary fibrosis and may be therapeutically beneficial for IPF patients in a clinical setting.

Integrative analysis of cell state changes in lung fibrosis with peripheral protein biomarkers

The correspondence of cell state changes in diseased organs to peripheral protein signatures is currently unknown. Here, we generated and integrated single-cell transcriptomic and proteomic data from multiple large pulmonary fibrosis patient cohorts. Integration of 233,638 single-cell transcriptomes (n = 61) across three independent cohorts enabled us to derive shifts in cell type proportions and a robust core set of genes altered in lung fibrosis for 45 cell types. Mass spectrometry analysis of lung lavage fluid (n = 124) and plasma (n = 141) proteomes identified distinct protein signatures correlated with diagnosis, lung function, and injury status. A novel SSTR2+ pericyte state correlated with disease severity and was reflected in lavage fluid by increased levels of the complement regulatory factor CFHR1. We further discovered CRTAC1 as a biomarker of alveolar type-2 epithelial cell health status in lavage fluid and plasma. Using cross-modal analysis and machine learning, we identified the cellular source of biomarkers and demonstrated that information transfer between modalities correctly predicts disease status, suggesting feasibility of clinical cell state monitoring through longitudinal sampling of body fluid proteomes.

Effect of Fluorofenidone Against Paraquat-Induced Pulmonary Fibrosis Based on Metabolomics and Network Pharmacology

BACKGROUND Fluorofenidone (AKF-PD) is an anti-fibrotic small-molecule compound. Its mechanism of action on paraquat (PQ)-induced pulmonary fibrosis is still unclear. MATERIAL AND METHODS Forty-eight SD rats were divided into 4 groups: control group, PQ group, PQ+AKF-PD group, and AKF-PD group. The pathological changes of lung tissues were observed by Masson and HE staining. The UPLC-QTOF-MS analysis was performed to detect the differences in metabolites among groups, then the possible mechanisms of the anti-pulmonary fibrosis effects of fluorofenidone were further revealed by network pharmacology analysis. Biological methods were used to verify the results of the network pharmacology analysis. RESULTS The results showed that fluorofenidone treatment significantly alleviated paraquat-induced pulmonary fibrosis. Metabolomics analysis showed that 18 metabolites were disordered in the serum of paraquat-poisoned rats, of which 13 were restored following fluorofenidone treatment. Network pharmacology analysis showed that the drug screened a total of 12 targets and mainly involved multiple signaling pathways and metabolic pathways to jointly exert anti-pulmonary fibrosis effects. Autophagy is the main pathway of fluorofenidone in treatment pulmonary fibrosis. The western blot results showed that fluorofenidone upregulated the expression of LC3-II/I and E-cadherin, and downregulated the expression of p62, alpha-SMA, and TGF-ß1, which validated that fluorofenidone could inhibit the development of paraquat-induced pulmonary fibrosis by increasing autophagy. CONCLUSIONS In conclusion, metabolomics combined with network pharmacology research strategy revealed that fluorofenidone has a multi-target and multi-path mechanism of action in the treatment of pulmonary fibrosis.

Identification of a missense variant in SPDL1 associated with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disorder characterised by progressive, destructive lung scarring. Despite substantial progress, the genetic determinants of this disease remain incompletely defined. Using whole genome and whole exome sequencing data from 752 individuals with sporadic IPF and 119,055 UK Biobank controls, we performed a variant-level exome-wide association study (ExWAS) and gene-level collapsing analyses. Our variant-level analysis revealed a novel association between a rare missense variant in SPDL1 and IPF (NM_017785.5:g.169588475 G > A p.Arg20Gln; p = 2.4 × 10-7, odds ratio = 2.87, 95% confidence interval: 2.03-4.07). This signal was independently replicated in the FinnGen cohort, which contains 1028 cases and 196,986 controls (combined p = 2.2 × 10-20), firmly associating this variant as an IPF risk allele. SPDL1 encodes Spindly, a protein involved in mitotic checkpoint signalling during cell division that has not been previously described in fibrosis. To the best of our knowledge, these results highlight a novel mechanism underlying IPF, providing the potential for new therapeutic discoveries in a disease of great unmet need.