Idiopathic pulmonary fibrosis: Diagnosis, epidemiology and natural history

Phenotypic drug screening in a human fibrosis model identified a novel class of antifibrotic therapeutics

Fibrogenic processes instigate fatal chronic diseases leading to organ failure and death. Underlying biological processes involve induced massive deposition of extracellular matrix (ECM) by aberrant fibroblasts. We subjected diseased primary human lung fibroblasts to an advanced three-dimensional phenotypic high-content assay and screened a repurposing drug library of small molecules for inhibiting ECM deposition. Fibrotic Pattern Detection by Artificial Intelligence identified tranilast as an effective inhibitor. Structure-activity relationship studies confirmed N-(2-butoxyphenyl)-3-(phenyl)acrylamides (N23Ps) as a novel and highly potent compound class. N23Ps suppressed myofibroblast transdifferentiation, ECM deposition, cellular contractility, and altered cell shapes, thus advocating a unique mode of action. Mechanistically, transcriptomics identified SMURF2 as a potential therapeutic target network. Antifibrotic activity of N23Ps was verified by proteomics in a human ex vivo tissue fibrosis disease model, suppressing profibrotic markers SERPINE1 and CXCL8. Conclusively, N23Ps are a novel class of highly potent compounds inhibiting organ fibrosis in patients.

Coagulation Factor-XII induces interleukin-6 by primary lung fibroblasts: A role in idiopathic pulmonary fibrosis?

Background The mechanisms driving idiopathic pulmonary fibrosis (IPF) remain undefined, however it is postulated that coagulation imbalances may play a role. The impact of blood-derived clotting factors, including factor XII (FXII) has not been investigated in the context of IPF. Methods Plasma levels of FXII were measured by ELISA in patients with IPF and age-matched healthy donors. Expression of FXII in human lung tissue was quantified using multiplex immunohistochemistry and western blotting. Mechanistic investigation of FXII activity was assessed in vitro on primary lung fibroblasts using qPCR and specific receptor/FXII inhibition. The functional outcome of FXII on fibroblast migration was examined by high-content image analysis. Findings Compared to 35 healthy donors, plasma levels of FXII were not higher in IPF (n=27, p>0·05). Tissue FXII was elevated in IPF (n=11) and increased numbers of FXII+ cells were found in IPF (n=8) lung tissue compared to non-diseased controls (n=6, p<0·0001). Activated FXII induced IL6 mRNA and IL-6 protein in fibroblasts that was blocked by anti-FXII antibody, CSL312. FXII-induced IL-6 production via PAR-1 and NF-kB. FXII induced migration of fibroblasts in a concentration-dependent manner. Interpretation FXII is normally confined to the circulation but leaks from damaged vessels into the lung interstitium in IPF where it 1) induces IL-6 production and 2) enhances migration of resident fibroblasts, critical events that drive chronic inflammation and therefore, contribute to fibrotic disease progression. Targeting FXII-induced fibroblastic processes in IPF may ameliorate pulmonary fibrosis. Funding National Health and Medical Research Council CRE in Lung Fibrosis and CSL Ltd.

Molecular Mechanisms and Cellular Contribution from Lung Fibrosis to Lung Cancer Development

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial lung disease (ILD) of unknown aetiology, with a median survival of 2-4 years from the time of diagnosis. Although IPF has unknown aetiology by definition, there have been identified several risks factors increasing the probability of the onset and progression of the disease in IPF patients such as cigarette smoking and environmental risk factors associated with domestic and occupational exposure. Among them, cigarette smoking together with concomitant emphysema might predispose IPF patients to lung cancer (LC), mostly to non-small cell lung cancer (NSCLC), increasing the risk of lung cancer development. To this purpose, IPF and LC share several cellular and molecular processes driving the progression of both pathologies such as fibroblast transition proliferation and activation, endoplasmic reticulum stress, oxidative stress, and many genetic and epigenetic markers that predispose IPF patients to LC development. Nintedanib, a tyrosine-kinase inhibitor, was firstly developed as an anticancer drug and then recognized as an anti-fibrotic agent based on the common target molecular pathway. In this review our aim is to describe the updated studies on common cellular and molecular mechanisms between IPF and lung cancer, knowledge of which might help to find novel therapeutic targets for this disease combination.

TRPV4 Mechanotransduction in Fibrosis

Fibrosis is an irreversible, debilitating condition marked by the excessive production of extracellular matrix and tissue scarring that eventually results in organ failure and disease. Differentiation of fibroblasts to hypersecretory myofibroblasts is the key event in fibrosis. Although both soluble and mechanical factors are implicated in fibroblast differentiation, much of the focus is on TGF-β signaling, but to date, there are no specific drugs available for the treatment of fibrosis. In this review, we describe the role for TRPV4 mechanotransduction in cardiac and lung fibrosis, and we propose TRPV4 as an alternative therapeutic target for fibrosis.

Between-population differences in constitutive and infection-induced gene expression in threespine stickleback

Vertebrate immunity is a complex system consisting of a mix of constitutive and inducible defences. Furthermore, host immunity is subject to selective pressure from a range of parasites and pathogens which can produce variation in these defences across populations. As populations evolve immune responses to parasites, they may adapt via a combination of (1) constitutive differences, (2) shared inducible responses, or (3) divergent inducible responses. Here, we leverage a powerful natural host‐parasite model system (Gasterosteus aculeatus and Schistochephalus solidus) to tease apart the relative contributions of these three types of adaptations to among‐population divergence in response to parasites. Gene expression analyses revealed limited evidence of significant divergence in constitutive expression of immune defence, and strong signatures of conserved inducible responses to the parasite. Furthermore, our results highlight a handful of immune‐related genes which show divergent inducible responses which may contribute disproportionately to functional differences in infection success or failure. In addition to investigating variation in evolutionary adaptation to parasite selection, we also leverage this unique data set to improve understanding of cellular mechanisms underlying a putative resistance phenotype (fibrosis). Combined, our results provide a case study in evolutionary immunology showing that a very small number of genes may contribute to genotype differences in infection response.

Evaluation of Regional Lung Function in Pulmonary Fibrosis with Xenon-129 MRI

Idiopathic pulmonary fibrosis, a pattern of interstitial lung disease, is often clinically unpredictable in its progression. This paper presents hyperpolarized Xenon-129 chemical shift imaging as a noninvasive, nonradioactive method of probing lung physiology as well as anatomy to monitor subtle changes in subjects with IPF. Twenty subjects, nine healthy and eleven IPF, underwent HP Xe-129 ventilation MRI and 3D-SBCSI. Spirometry was performed on all subjects before imaging, and DLCO and hematocrit were measured in IPF subjects after imaging. Images were post-processed in MATLAB and segmented using ANTs. IPF subjects exhibited, on average, higher Tissue/Gas ratios and lower RBC/Gas ratios compared with healthy subjects, and quantitative maps were more heterogeneous in IPF subjects. The higher ratios are likely due to fibrosis and thickening of the pulmonary interstitium. T2* relaxation was longer in IPF subjects and corresponded with hematocrit scores, although the mechanism is not well understood. A lower chemical shift in the red blood cell spectroscopic peak correlated well with a higher Tissue/RBC ratio and may be explained by reduced blood oxygenation. Tissue/RBC also correlated well, spatially, with areas of fibrosis in HRCT images. These results may help us understand the underlying mechanism behind gas exchange impairment and disease progression.

Proteomic Analysis Reveals Key Proteins in Extracellular Vesicles Cargo Associated with Idiopathic Pulmonary Fibrosis In Vitro

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible, and highly fatal disease. It is characterized by the increased activation of both fibroblast and myofibroblast that results in excessive extracellular matrix (ECM) deposition. Extracellular vesicles (EVs) have been described as key mediators of intercellular communication in various pathologies. However, the role of EVs in the development of IPF remains poorly understood. This study aimed to characterize the differentially expressed proteins contained within EVs cargo derived from the fibroblast cell lines LL97A (IPF-1) and LL29 (IPF-2) isolated from lungs bearing IPF as compared to those derived from the fibroblast cell lines CCD8Lu (NL-1) and CCD19Lu (NL-2) isolated from healthy donors. Isolated EVs were subjected to label-free quantitative proteomic analysis by LC-MS/MS, and as a result, 331 proteins were identified. Differentially expressed proteins were obtained after the pairwise comparison, including all experimental groups. A total of 86 differentially expressed proteins were identified in either one or more comparison groups. Of note, proteins involved in fibrogenic processes, such as tenascin-c (TNC), insulin-like-growth-factor-binding protein 7 (IGFBP7), fibrillin-1 (FBN1), alpha-2 collagen chain (I) (COL1A2), alpha-1 collagen chain (I) (COL1A1), and lysyl oxidase homolog 1 (LOXL1), were identified in EVs cargo isolated from IPF cell lines. Additionally, KEGG pathway enrichment analysis revealed that differentially expressed proteins participate in focal adhesion, PI3K-Akt, and ECM–receptor interaction signaling pathways. In conclusion, our findings reveal that proteins contained within EVs cargo might play key roles during IPF pathogenesis.

Pharmaceutical targeting of succinate dehydrogenase in fibroblasts controls bleomycin-induced lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by excessive deposition of extracellular matrix in the lung with fibroblast-to-myofibroblast transition, leading to chronically compromising lung function and death. However, very little is known about the metabolic alterations of fibroblasts in IPF, and there is still a lack of pharmaceutical agents to target the metabolic dysregulation. Here we show a glycolysis upregulation and fatty acid oxidation (FAO) downregulation in fibroblasts from fibrotic lung, and perturbation of glycolysis and FAO affects fibroblasts transdifferentiation. In addition, there is a significant accumulation of succinate both in fibrotic lung tissues and myofibroblasts, where succinate dehydrogenase (SDH) operates in reverse by reducing fumarate to succinate. Then succinate contributes to glycolysis upregulation and FAO downregulation by stabilizing HIF-1α, which promotes the development of lung fibrosis. In addition, we identify a near-infrared small molecule dye, IR-780, as a targeting agent which stimulates mild inhibition of succinate dehydrogenase subunit A (SDHA) in fibroblasts, and which inhibits TGF-β1 induced SDH and succinate elevation, then to prevent fibrosis formation and respiratory dysfunction. Further, enhanced cell retention of IR-780 is shown to promote severe inhibition of SDHA in myofibroblasts, which may contribute to excessive ROS generation and selectively induces myofibroblasts to apoptosis, and then therapeutically improves established lung fibrosis in vivo. These findings indicate that targeting metabolic dysregulation has significant implications for therapies aimed at lung fibrosis and succinate dehydrogenase is an exciting new therapeutic target to treat IPF.

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Glycolysis upregulation and fatty acid oxidation (FAO) downregulation in fibroblasts lead to lung fibrosis.

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Succinate contributes to metabolic dysregulation of fibroblasts by stabilizing HIF-1α.

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Succinate dehydrogenase is an exciting new therapeutic target to treat IPF.

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IR-780 can be a promising agent to control lung fibrosis by targeting succinate dehydrogenase.

Acute motor neuropathy with quadriparesis following treatment with triple tyrosine kinase inhibitor, nintedanib

Idiopathic pulmonary fibrosis (IPF) is a rare progressive interstitial lung disease characterized by declining lung function, worsening dyspnea and poor prognosis with median survival of 3–5 years. IPF predominantly affects people over 60 years, it however has worse prognosis in younger patients with genetic predisposition like short telomere syndrome. Nintedanib, one of two anti-fibrotic therapies approved for IPF treatment has occasional neurological side effects like fatigue, dizziness and headaches. Significant polyneuropathy or motor dysfunction is rarely seen. This case report illustrates a patient who developed quadriparesis following initiation of Nintedanib.

Identification and Validation of Potential Biomarkers and Pathways for Idiopathic Pulmonary Fibrosis by Comprehensive Bioinformatics Analysis

Objective

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible, high-mortality lung disease, but its pathogenesis is still unclear. Our purpose was to explore potential genes and molecular mechanisms underlying IPF.

Methods

IPF-related data were obtained from the GSE99621 dataset. Differentially expressed genes (DEGs) were identified between IPF and controls. Their biological functions were analyzed. The relationships between DEGs and microRNAs (miRNAs) were predicted. DEGs and pathways were validated in a microarray dataset. A protein-protein interaction (PPI) network was constructed based on these common DEGs. Western blot was used to validate hub genes in IPF cell models by western blot.

Results

DEGs were identified for IPF than controls in the RNA-seq dataset. Functional enrichment analysis showed that these DEGs were mainly enriched in immune and inflammatory response, chemokine-mediated signaling pathway, cell adhesion, and other biological processes. In the miRNA-target network based on RNA-seq dataset, we found several miRNA targets among all DEGs, like RAB11FIP1, TGFBR3, and SPP1. We identified 304 upregulated genes and 282 downregulated genes in IPF compared to controls both in the microarray and RNA-seq datasets. These common DEGs were mainly involved in cell adhesion, extracellular matrix organization, oxidation-reduction process, and lung vasculature development. In the PPI network, 3 upregulated and 4 downregulated genes could be considered hub genes, which were confirmed in the IPF cell models.

Conclusion

Our study identified several IPF-related DEGs that could become potential biomarkers for IPF. Large-scale multicentric studies are eagerly needed to confirm the utility of these biomarkers.

Occupational exposures and idiopathic pulmonary fibrosis

PURPOSE OF REVIEW

A recent meta-analysis of data from international case-control studies reports a population attributable fraction of 16% for occupational factors in the cause of idiopathic pulmonary fibrosis (IPF). Smoking, genetic factors and other prevalent diseases only partly explain IPF, and so this review aims to summarize recent progress in establishing which occupational exposures are important in cause.

RECENT FINDINGS

IPF is a rare disease, although it is the commonest idiopathic interstitial pneumonia. Epidemiological study suggests that incidence of IPF is increasing, particularly in older men. There are significant associations with IPF and occupational exposures to organic dust, including livestock, birds and animal feed, metal dust, wood dust and silica/minerals. Estimates of effect vary between studies, and are influenced by the distribution of employment, study design and case definition. Inhalation of asbestos fibres is a known cause of usual interstitial pneumonia (as seen histologically in IPF), though there are significant linear relationships between asbestos consumption, and mortality from both IPF and mesothelioma, leading to the hypothesis that low-level asbestos exposure may cause IPF.

SUMMARY

Research must focus on exposure-response relationships between asbestos and other occupational inhaled hazards, and IPF. Funding bodies and policy makers should acknowledge the significant occupational burden on IPF.

Emerging drugs for the treatment of idiopathic pulmonary fibrosis: 2020 phase II clinical trials

INTRODUCTION

The enthusiasm generated by the approval of pirfenidone and nintedanib as the first effective therapies for IPF led the IPF scientific community to investigate an increasing number of novel agents in well-designed randomized controlled trials, in the hope to find a cure for these patients.

AREAS COVERED

This reviews the evidence from IPF phase II trials that were completed or started in 2020. Literature search was performed using Medline and Clinicaltrials.org databases.

EXPERT OPINION

Randomized clinical trials revolutionized the management of IPF, leading to the discovery of the first therapies capable of slowing down functional deterioration in these patients. The recently published findings of the first successful phase II trials since pirfenidone and nintedanib will hopefully inaugurate a new era in the therapeutic scenario of IPF, where consolidated treatments of proven efficacy and novel targeted agents contribute together to reach the final goal of halting the fibrotic process of this dreadful disease.

Baseline plasma KL-6 level predicts adverse outcomes in patients with idiopathic pulmonary fibrosis receiving nintedanib: a retrospective real-world cohort study

BACKGROUND

Nintedanib is effective for treating idiopathic pulmonary fibrosis (IPF), but some patients may exhibit a suboptimal response and develop on-treatment acute exacerbation (AE-IPF), hepatic injury, or mortality. It remains unclear which patients are at risk for these adverse outcomes.

METHODS

We analysed the demographic and clinical data, baseline plasma levels of Krebs von den Lungen-6 (KL-6) and surfactant protein A (SPA), and longitudinal clinical courses of a real-world cohort of IPF patients who received nintedanib ≥ 14 days between March 2017 and December 2020. Cox proportional-hazards regression, subdistribution hazards regression, and sensitivity analyses were performed to investigate the association between baseline predictors and AE-IPF, mortality, and nintedanib-related hepatic injury. The relationship between baseline predictors and pulmonary function decline was determined.

RESULTS

Fifty-seven patients were included, of whom 24 (42%) developed hepatic injury, 20 (35%) had AE-IPF, and 16 (28%) died on-treatment. A baseline plasma KL-6 level ≥ 2.5 ng/mL, and diffusion capacity for carbon monoxide (DLCO) < 55% predicted, were associated with increased risk of hepatic injury (adjusted hazard ratio [aHR] was 3.46; 95% CI 1.13-10.60; p = 0.029 for KL-6, and 6.05; 95% CI 1.89-19.32; p = 0.002 for DLCO). Both factors also predicted severe and recurrent hepatic injury. Patients with baseline KL-6 ≥ 2.5 ng/mL also had a higher risk of AE-IPF (aHR 4.52; 95% CI 1.63-12.55; p = 0.004). For on-treatment mortality, baseline KL-6 ≥ 3.5 ng/mL and SPA ≥ 600 pg/mL were significant predictors (aHR 5.39; 95% CI 1.16-24.97; p = 0.031 for KL-6, and aHR 12.28; 95% CI 2.06-73.05; p = 0.006 for SPA). Results from subdistribution hazard regression and sensitivity analyses supported these findings. Patients with elevated baseline plasma KL-6 levels also exhibited a trend towards faster pulmonary function decline.

CONCLUSIONS

For patients with IPF who are receiving nintedanib, we have identified baseline predictors, in particular plasma KL-6 levels, for the risk of adverse outcomes. Patients with these predictors may require close monitoring for unfavourable responses during treatment. Our findings also support the prognostic role of molecular markers like KL-6 and may contribute to future formulation of more individualized therapeutic strategies for IPF.

Venous Thromboembolic Disease in Chronic Inflammatory Lung Diseases: Knowns and Unknowns

Persistent inflammation within the respiratory tract underlies the pathogenesis of numerous chronic pulmonary diseases. There is evidence supporting that chronic lung diseases are associated with a higher risk of venous thromboembolism (VTE). However, the relationship between lung diseases and/or lung function with VTE is unclear. Understanding the role of chronic lung inflammation as a predisposing factor for VTE may help determine the optimal management and aid in the development of future preventative strategies. We aimed to provide an overview of the relationship between the most common chronic inflammatory lung diseases and VTE. Asthma, chronic obstructive pulmonary disease, interstitial lung diseases, or tuberculosis increase the VTE risk, especially pulmonary embolism (PE), compared to the general population. However, high suspicion is needed to diagnose a thrombotic event early as the clinical presentation inevitably overlaps with respiratory disorders. PE risk increases with disease severity and exacerbations. Hence, hospitalized patients should be considered for thromboprophylaxis administration. Conversely, all VTE patients should be asked for lung comorbidities before determining anticoagulant therapy duration, as those patients are at increased risk of recurrent PE episodes rather than DVT. Further research is needed to understand the underlying pathophysiology of in-situ thrombosis in those patients.

Deglycosylated Azithromycin Attenuates Bleomycin-Induced Pulmonary Fibrosis via the TGF-β1 Signaling Pathway

Idiopathic pulmonary fibrosis (IPF) is a progressive, life-threatening lung disease characterized by the proliferation of myofibroblasts and deposition of extracellular matrix that results in irreversible distortion of the lung structure and the formation of focal fibrosis. The molecular mechanism of IPF is not fully understood, and there is no satisfactory treatment. However, most studies suggest that abnormal activation of transforming growth factor-β1 (TGF-β1) can promote fibroblast activation and epithelial to mesenchymal transition (EMT) to induce pulmonary fibrosis. Deglycosylated azithromycin (Deg-AZM) is a compound we previously obtained by removing glycosyls from azithromycin; it was demonstrated to exert little or no antibacterial effects. Here, we discovered a new function of Deg-AZM in pulmonary fibrosis. In vivo experiments showed that Deg-AZM could significantly reduce bleomycin-induced pulmonary fibrosis and restore respiratory function. Further study revealed the anti-inflammatory and antioxidant effects of Deg-AZM in vivo. In vitro experiments showed that Deg-AZM inhibited TGF-β1 signaling, weakened the activation and differentiation of lung fibroblasts, and inhibited TGF-β1-induced EMT in alveolar epithelial cells. In conclusion, our findings show that Deg-AZM exerts antifibrotic effects by inhibiting TGF-β1-induced myofibroblast activation and EMT.

MiRNA, a New Treatment Strategy for Pulmonary Fibrosis

Pulmonary fibrosis (PF) is the most common chronic, progressive interstitial lung disease, mainly occurring in the elderly, with a median survival of 2-4 years after diagnosis. Its high mortality rate attributes to the delay in diagnosis due to its generic symptoms, and more importantly, to the lack of effective treatments. MicroRNAs (miRNAs) are a class of small non-coding RNAs that are involved in many essential cellular processes, including extracellular matrix remodeling, alveolar epithelial cell apoptosis, epithelial-mesenchymal transition, etc. We summarized the dysregulated miRNAs in TGF-β signaling pathway-mediated PF in recent years with dual effects, such as anti-fibrotic let-7 family and pro-fibrotic miR-21 members. Therefore, this review will set out the latest application of miRNAs to provide a new direction for PF treatment.

Current and future treatment for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fibrosing interstitial lung disease, which is associated with a short survival rate. The decline in forced vital capacity in patients with IPF appears to be almost the same rate regardless of baseline lung function status. This suggests that early treatment would be necessary to prevent further deterioration even lung function is maintained within normal limits. Both pirfenidone and nintedanib significantly slow the decline in lung function, reduce the risk of acute exacerbation, and improve survival rate. However, many individuals with IPF remain untreated. Most IPF patients can tolerate antifibrotic drug therapy, and the dose adjustment has been shown to effectively reduce side effects without modifying efficacy. Although the recent introduction of pirfenidone and nintedanib has led to the slowing of lung function decline, there is no evidence of fibrosis reversal. In the near future, several new drugs are expected to be prescribed to patients with IPF. We are anticipating that some drugs may reverse fibrosis. Fibrosis inhibiting drugs have different pharmacological actions and there are various mechanisms causing fibrosis in the lesion. Therefore, it is imperative to launch efforts to optimize antifibrotic effects through a combination therapy of several drugs. These efforts will hold out hope for patients with IPF.

Gene therapy strategies for idiopathic pulmonary fibrosis: recent advances, current challenges, and future directions

Idiopathic pulmonary fibrosis (IPF) is a chronic disease in which the lungs become irreversibly scarred, leading to declining lung function. As currently available drugs do not cure IPF, there remains a great medical need for more effective treatments. Perhaps this need could be addressed by gene therapies, which offer powerful and versatile ways to attenuate a wide range of processes involved in fibrosis. Despite the potential benefits of gene therapy, no one has reviewed the current state of knowledge regarding its application for treating IPF. We therefore analyzed publications that reported the use of gene therapies to treat pulmonary fibrosis in animals, as clinical studies have not been published yet. In this review, we first provide an introduction on the pathophysiology of IPF and the most well-established gene therapy approaches. We then present a comprehensive evaluation of published animal studies, after which we provide recommendations for future research to address challenges with respect to the selection and use of animal models as well as the development of delivery vectors and dosage forms. Addressing these considerations will bring gene therapies one step closer to clinical testing and thus closer to patients.

Regorafenib-Attenuated, Bleomycin-Induced Pulmonary Fibrosis by Inhibiting the TGF-β1 Signaling Pathway

Idiopathic pulmonary fibrosis (IPF) is a fatal and age-related pulmonary disease. Nintedanib is a receptor tyrosine kinase inhibitor, and one of the only two listed drugs against IPF. Regorafenib is a novel, orally active, multi-kinase inhibitor that has similar targets to nintedanib and is applied to treat colorectal cancer and gastrointestinal stromal tumors in patients. In this study, we first identified that regorafenib could alleviate bleomycin-induced pulmonary fibrosis in mice. The in vivo experiments indicated that regorafenib suppresses collagen accumulation and myofibroblast activation. Further in vitro mechanism studies showed that regorafenib inhibits the activation and migration of myofibroblasts and extracellular matrix production, mainly through suppressing the transforming growth factor (TGF)-β1/Smad and non-Smad signaling pathways. In vitro studies have also indicated that regorafenib could augment autophagy in myofibroblasts by suppressing TGF-β1/mTOR (mechanistic target of rapamycin) signaling, and could promote apoptosis in myofibroblasts. In conclusion, regorafenib attenuates bleomycin-induced pulmonary fibrosis by suppressing the TGF-β1 signaling pathway.

LncRNA SNHG16 promotes pulmonary fibrosis by targeting miR-455-3p to regulate the Notch2 pathway

Background

Idiopathic pulmonary fibrosis (IPF) is the most common interstitial lung diseases with a poor prognosis. Long non-coding RNAs (lncRNAs) have been reported to be involved in IPF in several studies. However, the role of lncRNA SNHG16 in IPF is largely unknown.

Methods

Firstly, experimental pulmonary fibrosis model was established by using bleomycin (BML). Histology and Western blotting assays were used to determine the different stages of fibrosis and expression of several fibrosis biomarkers. The expression of SNHG16 was detected by quantitative real-time polymerase chain reaction (qRT‐PCR). EdU staining and wound-healing assay were utilized to analyze proliferation and migration of lung fibroblast cells. Molecular mechanism of SNHG16 was explored by bioinformatics, dual-luciferase reporter assay, RNA immunoprecipitation assay (RIP), and qRT-PCR.

Results

The expression of SNHG16 was significantly up-regulated in bleomycin-(BLM) induced lung fibrosis and transforming growth factor-β (TGF-β)-induced fibroblast. Knockdown of SNHG16 could attenuate fibrogenesis. Mechanistically, SNHG16 was able to bind and regulate the expression of miR-455-3p. Moreover, SNHG16 also regulated the expression of Notch2 by targeting miR-455-3p. Finally, SNHG16 could promote fibrogenesis by regulating the expression of Notch2.

Conclusion

Taken together, our study demonstrated that SNHG16 promoted pulmonary fibrosis by targeting miR-455-3p to regulate the Notch2 pathway. These findings might provide a novel insight into pathologic process of lung fibrosis and may provide prevention strategies in the future.

Role of Farnesoid X Receptor in the Pathogenesis of Respiratory Diseases

Farnesoid X receptor (FXR) is a bile acid receptor encoded by the Nr1h4 gene. FXR plays an important role in maintaining the stability of the internal environment and the integrity of many organs, including the liver and intestines. The expression of FXR in nondigestible tissues other than in the liver and small intestine is known as the expression of “nonclassical” bile acid target organs, such as blood vessels and lungs. In recent years, several studies have shown that FXR is widely involved in the pathogenesis of various respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, and idiopathic pulmonary fibrosis. Moreover, a number of works have confirmed that FXR can regulate the bile acid metabolism in the body and exert its anti-inflammatory and antifibrotic effects in the airways and lungs. In addition, FXR may be used as a potential therapeutic target for some respiratory diseases. For example, FXR can regulate the tumor microenvironment by regulating the balance of inflammatory and immune responses in the body to promote the occurrence and development of non-small-cell lung cancer (NSCLC), thereby being considered a potential target for immunotherapy of NSCLC. In this article, we provide an overview of the internal relationship between FXR and respiratory diseases to track the progress that has been achieved thus far in this direction and suggest potential therapeutic prospects of FXR in respiratory diseases.

In-hospital mortality trends among patients with idiopathic pulmonary fibrosis in the United States between 2013-2017: a comparison of academic and non-academic programs

Background

Idiopathic pulmonary fibrosis (IPF) is a devastating condition characterized by progressive lung function decline and early mortality. While early accurate diagnosis is essential for IPF treatment, data evaluating the impact of hospital academic status on IPF-related mortality remains limited. Here we examined in-hospital mortality trends for patients with IPF from 2013 to 2017. We hypothesized that in-hospital IPF mortality would be influenced by hospital academic setting.

Methods

Hospitalization data was extracted from the National Inpatient Sample (NIS) for subjects with an international classification of disease code for IPF. In-hospital mortality stratified by hospital setting (academic versus non-academic) was the primary outcome of interest, with secondary analyses performed for subgroups with and without respiratory failure and requiring mechanical ventilation. Predictors of mortality were then assessed.

Results

Among 93,680 patients with IPF requiring hospitalization, 58,450 (62.4%) were admitted to academic institutions. In-hospital mortality decreased significantly in those admitted to an academic hospital (p < 0.001) but remained unchanged in patients admitted to a non-academic hospital. A plateau in-hospital mortality was observed among all hospitalized patients (p = 0.12), with a significant decrease observed for patients with admitted respiratory failure (p < 0.001) and those placed on mechanic ventilation (p < 0.001).

Conclusion

In-hospital mortality decreased significantly for patients with IPF admitted to an academic hospital, suggesting that management strategies may differ by hospital setting. Mortality among those with respiratory failure and those requiring mechanical ventilation has dropped significantly. Our findings may underscore the importance of promoting early referral to an academic institution and adherence to international treatment guidelines.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-020-01328-y.

Extracellular adenosine 5'-triphosphate in pulmonary disorders

Adenosine 5'-triphosphate (ATP) is found in every cell of the human body where it plays a critical role in cellular energetics and metabolism. ATP is released from cells under physiologic and pathophysiologic condition; extracellular ATP is rapidly degraded to adenosine 5'-diphosphate (ADP) and adenosine by ecto-enzymes (mainly, CD39 and CD73). Before its degradation, ATP acts as an autocrine and paracrine agent exerting its effects on targeted cells by activating cell surface receptors named P2 Purinergic receptors. The latter are expressed by different cell types in the lungs, the activation of which is involved in multiple pulmonary disorders. This succinct review summarizes the role of ATP in inflammation processes associated with these disorders including bronchoconstriction, cough, mechanical ventilation-induced lung injury and idiopathic pulmonary fibrosis. All of these disorders still constitute unmet clinical needs. Therefore, the various ATP-signaling pathways in pulmonary inflammation constitute attractive targets for novel drug-candidates that would improve the management of patients with multiple pulmonary diseases.

Human Fibrosis: Is There Evidence for a Genetic Predisposition in Musculoskeletal Tissues?

BACKGROUND

Pathologic fibrosis is characterized by dysregulation of gene expression with excessive extracellular matrix production. The genetic basis for solid organ fibrosis is well described in the literature. However, there is a paucity of evidence for similar processes in the musculoskeletal (MSK) system. The purpose of this review is to provide an overview of existing evidence of genetic predisposition to pathologic fibrosis in the cardiac, pulmonary, and MSK systems, and to describe common genetic variants associated with these processes.

METHODS

A comprehensive search of several databases from 2000 to 2019 was conducted using relevant keywords in the English language. Genes reported as involved in idiopathic fibrotic processes in the heart, lung, hand, shoulder, and knee were recorded by 2 independent authors.

RESULTS

Among 2373 eligible studies, 52 studies investigated genetic predisposition in terms of variant analysis with the following organ system distribution: 36 pulmonary studies (69%), 15 hand studies (29%), and 1 knee study (2%). Twenty-two percent of gene variants identified were associated with both pulmonary and MSK fibrosis (ie, ADAM, HLA, CARD, EIF, TGF, WNT, and ZNF genes). Genetic variants known to be involved in the MSK tissue development or contractility properties in muscle were identified in the pulmonary fibrosis.

CONCLUSION

Despite shared genetic variations in both the lung and hand, there remains limited information about genetic variants associated with fibrosis in other MSK regions. This finding establishes the necessity of further studies to elucidate the genetic determinants involved in the knee, shoulder, and other joint fibrotic pathways.

LEVEL OF EVIDENCE

Level III.

Alveolar cells under mechanical stressed niche: critical contributors to pulmonary fibrosis

Pulmonary fibrosis arises from the repeated epithelial mild injuries and insufficient repair lead to over activation of fibroblasts and excessive deposition of extracellular matrix, which result in a mechanical stretched niche. However, increasing mechanical stress likely exists before the establishment of fibrosis since early micro injuries increase local vascular permeability and prompt cytoskeletal remodeling which alter cellular mechanical forces. It is noteworthy that COVID-19 patients with severe hypoxemia will receive mechanical ventilation as supportive treatment and subsequent pathology studies indicate lung fibrosis pattern. At advanced stages, mechanical stress originates mainly from the stiff matrix since boundaries between stiff and compliant parts of the tissue could generate mechanical stress. Therefore, mechanical stress has a significant role in the whole development process of pulmonary fibrosis. The alveoli are covered by abundant capillaries and function as the main gas exchange unit. Constantly subject to variety of damages, the alveolar epithelium injuries were recently recognized to play a vital role in the onset and development of idiopathic pulmonary fibrosis. In this review, we summarize the literature regarding the effects of mechanical stress on the fundamental cells constituting the alveoli in the process of pulmonary fibrosis, particularly on epithelial cells, capillary endothelial cells, fibroblasts, mast cells, macrophages and stem cells. Finally, we briefly review this issue from a more comprehensive perspective: the metabolic and epigenetic regulation.

Pleuroparenchymal fibroelastosis in patients with idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

PPFE is characterized by fibrosis in the pleura and subpleural lung parenchyma in the upper lobes, while other types of ILD, mainly UIP, can be observed in about half of the patients in their lower lobes. The aim of this study was to evaluate the clinical significance of the radiologically defined PPFE in patients with IPF.

METHODS

Clinical data and chest CT images were retrospectively analysed in 445 patients with IPF (biopsy-proven cases, n = 165). The radiological criteria of PPFE were defined as follows: (i) bilateral subpleural dense fibrosis with or without pleural thickening in the upper lobes, (ii) evidence of disease progression and (iii) no clinical evidence of identifiable aetiologies.

RESULTS

The median follow-up period was 43.0 months. The mean age of the patients was 66.4 years and 76.4% were male. PPFE was identified in 28 patients (6.3%). The PPFE group showed lower BMI and lung function (FVC and TLC) at baseline, more frequent pneumothorax and pneumomediastinum, higher decline rates in lung function and poorer prognosis during follow-up than the no-PPFE group. PPFE was an independent risk factor (HR = 2.953, 95% CI: 1.350-6.460, P = 0.007) for pneumothorax or pneumomediastinum, but not for mortality in patients with IPF.

CONCLUSION

Among patients with IPF, the PPFE group, when compared to the no-PPFE group, showed lower BMI and lung function and showed more frequent complications and poorer survival during follow-up.

Cor pulmonale: the role of traditional and advanced echocardiography in the acute and chronic settings

Cor pulmonale is the condition in which the right ventricle undergoes morphological and/or functional changes due to diseases that affect the lungs, the pulmonary circulation, or the breathing process. Depending on the speed of onset of the pathological condition and subsequent effects on the right ventricle, it is possible to distinguish the acute cor pulmonale from the chronic type of disease. Echocardiography plays a central role in the diagnostic and therapeutic work-up of these patients, because of its non-invasive nature and wide accessibility, providing its greatest usefulness in the acute setting. It also represents a valuable tool for tracking right ventricular function in patients with cor pulmonale, assessing its stability, deterioration, or improvement during follow-up. In fact, not only it provides parameters with prognostic value, but also it can be used to assess the efficacy of treatment. This review attempts to provide the current standards of an echocardiographic evaluation in both acute and chronic cor pulmonale, focusing also on the findings present in the most common pathologies causing this condition.

Use of systemic lidocaine for postoperative acute pain management in single-lung transplantation: Case report

Introduction: Lung transplantation is associated with severe pain, which can delay recovery. Systemic lidocaine has useful analgesic properties for managing acute pain, however little is known on its use after lung transplantation. Due to pharmacological alterations during the postoperative period, the use of analgesics implies a demanding process to avoid toxicity, so lidocaine may play a role in this scenario. In this sense, the purpose of this case report is to present the use of systemic lidocaine as an option for the management of acute pain when other analgesics have failed to do so.Case presentation: The case of a male patient with acute pain in the postoperative period of single-lung transplantation is presented. Opioids and non-opioid analgesics showed limited efficacy, so the systematic administration of lidocaine was decided. Systemic lidocaine was effective for pain control, functional recovery and opioid decrease during the postoperative period.Conclusions: Systemic lidocaine was a useful drug for postoperative pain management in lung transplantation, since it allowed adequate analgesia and lung function recovery with decreased use of opioids. This drug may be a component of multimodal analgesia in selected patients when other options have failed; however its routine use is not recommended.

Fluorescence imaging of hypochlorous acid and peroxynitritein vitroandin vivowith emission wavelength beyond 750 nm

Hydro-Si-oxazines were exploited as NIR fluorescent probes to monitor HClO/ONOO⁻produced by phagocytes in inflammation-related diseases.

Retrospective cohort study of patients qualified for lung transplantation due to idiopathic pulmonary fibrosis - single-centre experience

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive disease. Pharmacological treatment can only slow its progression. However, lung transplantation (LTx) is the only treatment for patients with its end-stage form. This study analysed the long-term results of the qualification process of patients with IPF recruited for LTx in a single centre.

MATERIAL AND METHODS

Retrospective analysis of 84 patients (56 patients who died while on the waiting list and 28 patients who underwent LTx) with end-stage IPF who were qualified for LTx between 2006 and 2017 at the Silesian Centre for Heart Diseases (Zabrze, Poland).

RESULTS

Cox proportional hazard analysis showed that the only parameter was 6-minute walk test (6MWT) distance, which statistically significantly impacted the probability of receiving a graft (parameter assessment, 0.00523; p = 0.006; 95% confidence interval (CI): 0.0015-0.009; hazard ratio (HR) = 1.005) as well as that of death while on the waiting list (parameter assessment, -0.0054; p = 0.003; 95% CI: -0.009- (-0.0017); HR = 0.995). Patients with a 253-350-m 6MWT distance had 3 times greater risk of dying while on the waiting list than those who walked more than 350 m. Other factors, such as height, sex, and blood group, also influenced the outcome.

CONCLUSIONS

The 6-minute walk test distance is an independent predictor of mortality on the lung transplant waiting list. Blood type and height also play a significant role in becoming a lung recipient.

Traditional Chinese medicine in the treatment of idiopathic pulmonary fibrosis based on syndrome differentiation: Study protocol of an exploratory trial

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) has a poor prognosis and is often a kind of heavy financial burden to patients. Currently, few treatments are available for IPF. Clinical practice of traditional Chinese medicine (TCM), using a syndrome differentiation approach, offers some treatment success in IPF. However, there is no sufficient evidence-based study of the role of TCM in IPF management to make strong conclusions. This study evaluates the efficacy and safety of TCM in the treatment of IPF.

METHODS AND DESIGN

A multicenter, exploratory, randomized, double-blind and placebo-controlled trial is planned. A total of 80 patients will be enrolled in the study, which will include 26 weeks of treatment. Participants will be randomly assigned into TCM group or control group in a 1:1 ratio. The TCM group will be given TCM granules based on syndrome differentiation. Formulae include Bao-fei Hua-xian granule for lung qi deficiency, Jin-shui Huan-xian granule for lung-kidney qi deficiency and Yang-qing Kang-xian granule for yin deficiency and inner heat. The control group will be given a corresponding TCM granule placebo. The efficacy and safety of interventions will be evaluated by the outcome variables, including frequencies of acute exacerbations, pulmonary function, clinical symptoms, dyspnea, health-related quality of life (HRQoL), 6-minute walk distance and safety indicators.

DISCUSSION

It is hypothesized that TCM will decrease the frequency of adverse events, improve pulmonary function and HRQoL, based on our clinical experience. This trial is the first study of TCM treatment in IPF that is based on syndrome differentiation and will evaluate the efficacy and safety of TCM in IPF.

TRIAL REGISTRATION

This study was registered on www.Chictr.org.cn: ChiCTR-IIR-17013532. Register date: November 24, 2017.

Forced Vital Capacity (FVC) decline, mortality and healthcare resource utilization in idiopathic pulmonary fibrosis

Aim of the study: Potential care implications of antifibrotic reimbursement restrictions were studied by forced vital capacity (FVC) decline, mortality and specialty care related healthcare resource utilization in patients with idiopathic pulmonary fibrosis (IPF).

Material and methods: IPF patients were identified from the electronic medical records of the Hospital District of Southwest Finland between 2005 and 2017. Text-mining was used for patient identification to exclude other interstitial lung diseases (ILD) from the cohort. FVC reimbursement restriction (FVC 50-90%) was used for stratification.

Results: Out of all patients with ILD, 27% (N = 266) were identified to have IPF. At baseline, 24% presented with FVC>90% and 63% with FVC 50-90% predicted. FVC at diagnosis did not improve during the study period. Median survival decreased by severity from 6.7 years in FVC>90% at baseline to 0.7 years in patient with FVC<50% predicted. In the FVC>90% group, 14% died before a change in FVC category could be noted. Overall, 4.7 million euro worth of specialty care resources were spent on IPF patients. The highest cost driver was inpatient days.

Conclusions: IPF is associated with a high burden of disease, and reimbursement restrictions are in conflict with early care. As there are antifibrotic treatment options for IPF patients, early diagnosis is important.

Effect of the alteration of Tribbles homologue 3 expression on epithelial‑mesenchymal transition of transforming growth factor β1‑induced mouse alveolar epithelial cells through the Wnt/β‑catenin signaling pathway

The aims of the present study were to elucidate the regulatory effect of exogenous Tribbles homologue 3 (TRB3) expression on the Wnt/β-catenin signaling pathway and epithelial-mesenchymal transition (EMT) in transforming growth factor-β1 (TGF-β1)-induced mouse alveolar epithelial cells (MLE-12) and investigate the underlying regulatory mechanisms. TRB3 expression was upregulated and downregulated using gene overexpression and RNA interference techniques, respectively. TGF-β1-stimulated MLE-12 cells were examined for EMT and activation condition of the Wnt/β-catenin signaling pathway using Cell Counting Kit-8, flow cytometry, western blotting, reverse transcription-quantitative PCR, ELISA and immunofluorescence techniques. During TGF-β1-induced EMT, TRB3 expression was found to be significantly upregulated (P<0.05). In the TRB3 overexpression group, upregulated expression of β-catenin and EMT-related genes and proteins was observed (P<0.05), and an increase in fibrosis-related factors in the cell culture supernatant was detected (P<0.05); however, the results were the opposite in the TRB3 downregulated group (P<0.05). TRB3 may be involved in the regulation of EMT in TGF-β1-induced MLE-12 cells through the Wnt/β-catenin signaling pathway.

Pirfenidone activates cannabinoid receptor 2 in a mouse model of bleomycin-induced pulmonary fibrosis

Inflammation serves an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Cannabinoid receptor 2 (CB2R) is a receptor predominantly expressed in the immune system. CB2R agonists can be used to treat a wide range of inflammation-related diseases. Pirfenidone has been demonstrated to be effective for IPF treatment. The aim of present study was to investigate whether CB2R activation mediates the antifibrotic effect of pirfenidone. For that purpose, mice were intravenously injected with bleomycin (BLM; 5 mg/kg/day). pirfenidone (300 mg/kg/day) was then orally administered for 15 days. Lung pathological alterations in the mice were evaluated by Masson's trichrome staining. The mRNA and protein levels of CB2R in lung tissues were measured by reverse transcription-quantitative PCR and western blotting. The levels of inflammatory factors were determined by ELISA. The effect of pirfenidone on WI38 cell viability was evaluated by MTT assay. The results demonstrated that CB2R protein and mRNA levels increased with increasing fibrosis in mice with BLM-induced IPF. Pirfenidone administration significantly ameliorated IPF and reduced the serum levels of inflammatory factors induced by BLM. Pirfenidone also inhibited fibroblast cell proliferation and decreased the levels of inflammatory factors in vitro, which could be reversed by the CB2R antagonist SR144528, suggesting that CB2R was activated by pirfenidone. In conclusion, pirfenidone attenuated and activated CB2R in BLM-treated mice. In addition, pirfenidone inhibited fibroblast cell proliferation in vitro. These effects could be reversed by the CB2R antagonist SR144528. Thus, activation of CB2R may be considered a mechanism of the antifibrotic effects of pirfenidone.

tPA promotes the proliferation of lung fibroblasts and activates the Wnt/β-catenin signaling pathway in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible and the most common fatal interstitial lung disease, which is characterized by damaged alveolar structure, the massive proliferation of fibroblasts and deposition of extracellular matrix (ECM). While the pathogenesis of IPF remains unclear, it has been clearly established that the excessive proliferation of lung fibroblasts is the most direct cause of fibrogenesis. Numerous proliferating fibroblasts form fibrous foci and secrete a large amount of ECM to aggravate the process of pulmonary fibrosis. Tissue plasminogen activator (tPA) is a kind of serine protease, its main function is to activate zymogens into active enzymes involved in fibrinolysis. Our study found tPA functioned as a cytokine to promote the proliferation of lung fibroblasts through intracellular signaling events involving Erk1/2, p90RSK, GSK-3β phosphorylation, and cyclinD1 induction. We also uncovered that tPA indirectly activated the Wnt/β-catenin signaling pathway by regulating the GSK-3β phosphorylation level. It's well-known that Wnt/β-catenin signaling pathway plays an important role in the pathogenesis of pulmonary fibrosis, in which the accumulation of β-catenin in the cytoplasm is an important signal of the activation of Wnt/β-catenin signaling pathway. Our study unveiled that tPA can serve as a cytokine involved in Wnt/β-catenin signaling pathway and be implicated in pulmonary fibrosis.

Antifibrotic Mechanism of Cinobufagin in Bleomycin-Induced Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is a progressive and usually fatal lung disease that is characterized by fibroblast proliferation and extracellular matrix remodeling, which result in irreversible distortion of the lung's architecture and the formation of focal fibrous hyperplasia. The molecular mechanism by which pulmonary fibrosis develops is not fully understood, and no satisfactory treatment currently exists. However, many studies consider that aberrant activation of TGF-β1 frequently promotes epithelial-mesenchymal transition (EMT) and fibroblast activation in pulmonary fibrosis. Cinobufagin (CBG), a traditional Chinese medicine, has been widely used for long-term pain relief, cardiac stimulation, and anti-inflammatory and local anesthetic treatments. However, its role in pulmonary fibrosis has not yet been established. We investigated the hypothesis that cinobufagin plays an inhibitory role on TGF-β1 signaling using a luciferase-reporter assay. We further explored the effect of cinobufagin on pulmonary fibrosis both in vitro and in vivo. The in vitro experiments showed that cinobufagin suppresses TGF-β1/Smad3 signaling in a dose-dependent manner, attenuates the activation and differentiation of lung fibroblasts and inhibits EMT induced by TGF-β1 in alveolar epithelial cells. The in vivo experiments indicated that cinobufagin significantly alleviates bleomycin-induced collagen deposition and improves pulmonary function. Further study showed that cinobufagin could attenuate bleomycin-induced inflammation and inhibit fibroblast activation and the EMT process in vivo. In summary, cinobufagin attenuates bleomycin-induced pulmonary fibrosis in mice via suppressing inflammation, fibroblast activation and epithelial-mesenchymal transition.

Metformin induces lipogenic differentiation in myofibroblasts to reverse lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease in which the intricate alveolar network of the lung is progressively replaced by fibrotic scars. Myofibroblasts are the effector cells that excessively deposit extracellular matrix proteins thus compromising lung structure and function. Emerging literature suggests a correlation between fibrosis and metabolic alterations in IPF. In this study, we show that the first-line antidiabetic drug metformin exerts potent antifibrotic effects in the lung by modulating metabolic pathways, inhibiting TGFβ1 action, suppressing collagen formation, activating PPARγ signaling and inducing lipogenic differentiation in lung fibroblasts derived from IPF patients. Using genetic lineage tracing in a murine model of lung fibrosis, we show that metformin alters the fate of myofibroblasts and accelerates fibrosis resolution by inducing myofibroblast-to-lipofibroblast transdifferentiation. Detailed pathway analysis revealed a two-arm mechanism by which metformin accelerates fibrosis resolution. Our data report an antifibrotic role for metformin in the lung, thus warranting further therapeutic evaluation.

Idiopathic pulmonary fibrosis is associated with myofibroblast activation in the lungs and metabolic alterations. Here, the authors show that the antidiabetic drug metformin has antifibrotic effects in human-derived samples and mouse models, by modulating a number of metabolic pathways to induce lipogenic transdifferentiation of myofibroblasts.

A pathologic two-way street: how innate immunity impacts lung fibrosis and fibrosis impacts lung immunity

Lung fibrosis is characterised by the accumulation of extracellular matrix within the lung and is secondary to both known and unknown aetiologies. This accumulation of scar tissue limits gas exchange causing respiratory insufficiency. The pathogenesis of lung fibrosis is poorly understood, but immunologic‐based treatments have been largely ineffective. Despite this, accumulating evidence suggests that innate immune cells and receptors play important modulatory roles in the initiation and propagation of the disease. Paradoxically, while innate immune signalling may be important for the pathogenesis of fibrosis, there is also evidence to suggest that innate immune function against pathogens may be impaired, leading to dysregulated and/or impaired host defence. This review summarises the evidence for this pathologic two‐way street, highlights new concepts of pathogenesis and recommends future directions for research emphasis.

Serious adverse events in patients with idiopathic pulmonary fibrosis in the placebo arms of 6 clinical trials

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by irreversible loss of lung function and an unpredictable course of disease progression.

METHODS

The safety data for patients with IPF who received placebo in 6 clinical trials were pooled to examine the categories and frequencies of serious adverse events (SAEs) in this population.

RESULTS

In 1082 patients with IPF who received placebo, 673 SAEs were reported. Of these, 93 SAEs resulted in death (8.6% of patients). Respiratory-related conditions were the most frequently reported SAE (225 events, 16.33 per 100 patient-exposure years [PEY]), followed by infections and infestations (136 events, 9.87 per 100 PEY) and cardiac disorders (79 events, 5.73 per 100 PEY); these categories also had the most fatal outcomes (60, 10, and 10 deaths, respectively). The most frequently reported fatal respiratory-related SAEs were IPF and respiratory failure (38 and 11 patients, respectively), and the most frequently reported fatal infections and infestations and cardiac disorders were pneumonia (5 patients) and myocardial infarction (3 patients), respectively.

CONCLUSIONS

This pooled analysis has value as a comparator for safety in future studies of IPF and provides insights in the natural evolution of both IPF and common comorbidities.

Therapeutic effects of obeticholic acid (OCA) treatment in a bleomycin-induced pulmonary fibrosis rat model

PURPOSE

We recently demonstrated a protective effect of the farnesoid X receptor agonist obeticholic acid (OCA) in rat models of bleomycin-induced pulmonary fibrosis (PF). Aim of the present study was to investigate whether the positive effects of OCA treatment are apparent also on ongoing bleomycin-induced PF, i.e., after 2 weeks of bleomycin administration.

METHODS

Bleomycin-induced PF rats were treated 2 weeks after bleomycin administration with OCA or pirfenidone for two additional weeks. Pulmonary function test was performed at 2 and 4 weeks in all experimental groups. At the same time points, lung morphological features and mRNA expression profile of genes related to fibrosis, inflammation and epithelial-mesenchymal transition were also assessed.

RESULTS

After 2 weeks, bleomycin significantly increased the pressure at the airway opening (PAO), a functional parameter related to fibrosis-induced lung stiffness, and induced diffuse lung interstitium fibrosis, with upregulation of inflammation (IL1β, MCP1) and tissue remodeling (COL1A1, COL3A1, ET1, MMP7, PDGFa, αSMA, SNAI1) markers. At week four, a further increase of lung fibrosis and PAO was observed, accompanied by upregulation of extracellular matrix-related mRNA expression. OCA administration, even after the establishment of PF, significantly improved pulmonary function, normalizing PAO, and reverted the bleomycin-induced lung alterations, with significant reduction of markers of inflammation (CD206, COX2, HIF1, IL1β, MCP1), epithelial proliferation (CTGF, PDGFa) and fibrosis (COL1A1, COL3A1, ET1, FN1, MMPs, αSMA, SNAIs, TGFβ1, TIMPs). Results with OCA were similar or superior to those obtained with pirfenidone.

CONCLUSIONS

In conclusion, our results demonstrate a significant therapeutic effect of OCA in already established PF.

Interstitial Lung Diseases in Developing Countries

More than 100 different conditions are grouped under the term interstitial lung disease (ILD). A diagnosis of an ILD primarily relies on a combination of clinical, radiological, and pathological criteria, which should be evaluated by a multidisciplinary team of specialists. Multiple factors, such as environmental and occupational exposures, infections, drugs, radiation, and genetic predisposition have been implicated in the pathogenesis of these conditions. Asbestosis and other pneumoconiosis, hypersensitivity pneumonitis (HP), chronic beryllium disease, and smoking-related ILD are specifically linked to inhalational exposure of environmental agents. The recent Global Burden of Disease Study reported that ILD rank 40th in relation to global years of life lost in 2013, which represents an increase of 86% compared to 1990. Idiopathic pulmonary fibrosis (IPF) is the prototype of fibrotic ILD. A recent study from the United States reported that the incidence and prevalence of IPF are 14.6 per 100,000 person-years and 58.7 per 100,000 persons, respectively. These data suggests that, in large populated areas such as Brazil, Russia, India, and China (the BRIC region), there may be approximately 2 million people living with IPF. However, studies from South America found much lower rates (0.4–1.2 cases per 100,000 per year). Limited access to high-resolution computed tomography and spirometry or to multidisciplinary teams for accurate diagnosis and optimal treatment are common challenges to the management of ILD in developing countries.

Diagnosis and management of idiopathic pulmonary fibrosis: Thoracic Society of Australia and New Zealand and Lung Foundation Australia position statements summary

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a fibrosing interstitial lung disease associated with debilitating symptoms of dyspnoea and cough, resulting in respiratory failure, impaired quality of life and ultimately death. Diagnosing IPF can be challenging, as it often shares many features with other interstitial lung diseases. In this article, we summarise recent joint position statements on the diagnosis and management of IPF from the Thoracic Society of Australia and New Zealand and Lung Foundation Australia, specifically tailored for physicians across Australia and New Zealand. Main suggestions: A comprehensive multidisciplinary team meeting is suggested to establish a prompt and precise IPF diagnosis. Antifibrotic therapies should be considered to slow disease progression. However, enthusiasm should be tempered by the lack of evidence in many IPF subgroups, particularly the broader disease severity spectrum. Non-pharmacological interventions including pulmonary rehabilitation, supplemental oxygen, appropriate treatment of comorbidities and disease-related symptoms remain crucial to optimal management. Despite recent advances, IPF remains a fatal disease and suitable patients should be referred for lung transplantation assessment.

Right Ventricular Functional Reserve in Early-Stage Idiopathic Pulmonary Fibrosis: An Exercise Two-Dimensional Speckle Tracking Doppler Echocardiography Study

BACKGROUND

The most important determinant of long-term survival in patients with idiopathic pulmonary fibrosis is the right ventricular (RV) adaptation to the increased pulmonary vascular resistance. Our aim was to explore RV contractile reserve during stress echocardiography in early-stage IPF.

METHODS

Fifty early-stage patients with IPF and 50 healthy control patients underwent rest and stress echocardiography, including RV two-dimensional speckle tracking echocardiography. At peak exertion, blood gas analysis and spirometry were also assessed.

RESULTS

At rest, RV diameters were mildly increased in IPF; however, although RV conventional systolic function indexes were similar between the IPF and control groups, RV global longitudinal strain and RV lateral wall longitudinal strain (LWLS) were significantly reduced in the IPF cohort. During physical exercise, patients with IPF showed a reduced exercise tolerance with lower maximal workload (P < .01), level of oxygen saturation (P < .001), and peak heart rate (P < .01). Systolic and diastolic BP values were similar in both groups. Systolic pulmonary artery pressure (PAPs) increase (ΔPAPs) during exertion was higher in IPF vs healthy subjects (P < .0001); RV LWLS increase (ΔRV LWLS) during exercise was lower in patients with IPF vs control patients (P < .00001). By multivariable analysis, RV LWLS at rest and ΔRV LWLS were directly related to peak exertion capacity, PAPs, and blood oxygen saturation level (Spo₂; P < .0001). Δ RV LWLS was directly related to diffusion lung carbon monoxide (P < .0001).

CONCLUSIONS

RV myocardial dysfunction is already present at rest in early-stage IPF and worsens during exertion as detected by two-dimensional speckle-tracking echocardiography. The RV altered contractile reserve appears to be related to reduced exercise tolerability and impaired pulmonary hemodynamic.

The Role of Occupational and Environmental Exposures in the Pathogenesis of Idiopathic Pulmonary Fibrosis: A Narrative Literature Review

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease characterised by a progressive and irreversible decline in lung function, which is associated with poor long-term survival. The pathogenesis of IPF is incompletely understood. An accumulating body of evidence, obtained over the past three decades, suggests that occupational and environmental exposures may play a role in the development of IPF. This narrative literature review aims to summarise current understanding and the areas of ongoing research into the role of occupational and environmental exposures in the pathogenesis of IPF.

Neutralization of IL-18 by IL-18 binding protein ameliorates bleomycin-induced pulmonary fibrosis via inhibition of epithelial-mesenchymal transition

Idiopathic pulmonary fibrosis (IPF) is a fatal parenchymal lung disease with limited effective therapies. Interleukin (IL)-18 belongs to a rather large IL-1 gene family and is a proinflammatory cytokine, which acts in both acquired and innate immunity. We have previously reported that IL-18 play an important role in lipopolysaccharide-induced acute lung injury in mice. Persistent inflammation often drives fibrotic progression in the bleomycin (BLM) injury model. However, the role of IL-18 in pulmonary fibrosis (PF) is still unknown. IL-18 binding protein (IL-18BP) is able to neutralize IL-18 biological activity and has a protective effect against renal fibrosis. The aim of this study was to investigate the effects of IL-18BP on BLM-induced PF. In the present study, we found that IL-18 was upregulated in lungs of BLM-injured mice. Neutralization of IL-18 by IL-18BP improved the survival rate and ameliorated BLM-induced PF in mice, which was associated with attenuated pathological changes, reduced collagen deposition, and decreased content of transforming growth factor-β1 (TGF-β1). We further demonstrated that IL-18BP treatment suppressed the BLM-induced epithelial mesenchymal transition (EMT), characterized by decreased α-smooth muscle actin (α-SMA) and increased E-cadherin (E-cad) in vivo. In addition, we provided in vitro evidence demonstrating that IL-18 promoted EMT through upregulation of Snail-1 in A549 cells. In conclusion, our findings raise the possibility that the increase of IL-18 is involved in the development of BLM-induced PF through modulating EMT in a Snail-1-dependent manner. IL-18BP may be a worthwhile candidate option for PF therapy.

Thyroid hormone: a resurgent treatment for an emergent concern

The story of thyroid hormone in human physiology is one of mixed emotions. Studying past literature on its use leads one to believe that it serves only a few functions in a handful of diseases. In reality, the pathophysiological role of thyroid hormone is an uncharted expanse. Over the past few decades, research on thyroid hormone has been understandably monopolized by studies of hypo- and hyperthyroidism and cancers. However, in our focused pursuit, we have neglected to observe its role in systems that are not so easily relatable. Recent evidence in lung disease suggests that the thyroid hormone is capable of preserving mitochondria in an indirect manner. This is an exciting revelation given the profound implications of mitochondrial dysfunction in several lung diseases. When paired with known links between thyroid hormone and fibrotic pathways, thyroid hormone-based therapies become more enticing for research. In this article, we inspect the sudden awareness surrounding thyroid hormone and discuss why it is of paramount importance that further studies scrutinize the potential of thyroid hormone, and/or thyromimetics, as therapies for lung diseases.