Usual interstitial pneumonia end-stage features from explants with radiologic and pathological correlations

Correlation of FAPI PET Uptake with Immunohistochemistry in Explanted Lungs from Patients with Advanced Interstitial Lung Disease

Recent studies have demonstrated promising results of fibroblast activation protein (FAP) inhibitor (FAPI) PET in prognosticating and monitoring interstitial lung diseases (ILDs). As a first step toward successful translation, our primary aim was to validate the FAPI PET uptake through immunohistochemistry in patients with advanced ILD who underwent lung transplantation after a FAPI PET scan. Methods: This is a preliminary analysis of a single-center, open-label, single-arm, prospective exploratory biodistribution study of 68Ga-FAPI-46 PET imaging in patients with ILD (NCT05365802). Patients with ILD confirmed by high-resolution CT and scheduled for lung transplant were included. Tissue samples of explanted lungs were obtained from both the central and peripheral lung parenchyma of each lobe. Additional samples were obtained from areas of the lung corresponding to regions of FAPI PET activity. Immunohistochemical staining was performed with an anti-FAP antibody. Percentages of FAP immunohistochemistry-positive area were measured semiautomatically using QuPath software. SUVs in the areas of pathologic samples were measured on FAPI PET/CT by referencing the gross photomap of the explanted lung. A Spearman correlation coefficient test was used to assess the relationship between FAPI PET uptake and FAP immunohistochemical expression in each specimen. Results: Four patients with advanced ILD who underwent FAPI PET/CT before lung transplantation were included. The types of ILD were idiopathic pulmonary fibrosis (n = 2), rheumatoid arthritis-associated ILD (n = 1), and nonspecific interstitial pneumonia (n = 1). FAPI uptake was visualized mainly in the fibrotic area on CT. Twenty-nine surgical pathology samples from 3 patients were analyzed. FAP staining was predominantly positive in fibroblastic foci. FAPI PET SUVmax and SUVmean showed a positive correlation with the immunohistochemical FAP expression score (SUVmax: r = 0.57, P = 0.001; SUVmean: r = 0.54, P = 0.002). Conclusion: In this analysis conducted in patients who underwent lung transplantation after a FAPI PET scan, FAPI PET uptake was positively correlated with FAP immunohistochemistry. These findings provide a rationale for further investigation of FAPI PET as a potential imaging biomarker for ILD.

Advanced Delivery Strategies of Nintedanib for Lung Disorders and Beyond: A Comprehensive Review

Nintedanib, a primary treatment for lung fibrosis, has gathered substantial attention due to its multifaceted potential. A tyrosine kinase inhibitor, nintedanib, inhibits multiple signalling receptors, including endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR) and ultimately inhibits fibroblast proliferation and differentiation. Therefore, nintedanib has been studied widely for other ailments like cancers and hepatic fibrosis, apart from lung disorders. Commercially, nintedanib is available as soft gelatin capsules for treatment against idiopathic pulmonary fibrosis. Since it has very low oral bioavailability (4.7%), high doses of a drug, such as 100-150 mg, are administered, which can cause problems of gastrointestinal irritation and hepatotoxicity. The article begins with exploring the mechanism of action of nintedanib, elucidating its complex interactions within cellular pathways that govern fibrotic processes. It also emphasizes the pharmacokinetics of nintedanib, clinical trial insights, and the limitations of conventional formulations. The article mainly focuses on the emerging landscape of nanoparticle-based carriers such as hybrid liposome-exosome, nano liquid crystals, discoidal polymeric, and magnetic systems, offering promising avenues to optimize drug targeting, address its efficacy issues and minimise adverse effects. However, none of these delivery systems are commercialised, and further research is required to ensure safety and effectiveness in clinical settings. Yet, as research progresses, these advanced delivery systems promise to revolutionise the treatment landscape for various fibrotic disorders and cancers, potentially improving patient outcomes and quality of life.

Multidisciplinary Approach to the Diagnosis of Idiopathic Interstitial Pneumonias: Focus on the Pathologist's Key Role

Idiopathic Interstitial Pneumonias (IIPs) are a heterogeneous group of the broader category of Interstitial Lung Diseases (ILDs), pathologically characterized by the distortion of lung parenchyma by interstitial inflammation and/or fibrosis. The American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary consensus classification of the IIPs was published in 2002 and then updated in 2013, with the authors emphasizing the need for a multidisciplinary approach to the diagnosis of IIPs. The histological evaluation of IIPs is challenging, and different types of IIPs are classically associated with specific histopathological patterns. However, morphological overlaps can be observed, and the same histopathological features can be seen in totally different clinical settings. Therefore, the pathologist's aim is to recognize the pathologic-morphologic pattern of disease in this clinical setting, and only after multi-disciplinary evaluation, if there is concordance between clinical and radiological findings, a definitive diagnosis of specific IIP can be established, allowing the optimal clinical-therapeutic management of the patient.

The compound artemisinin-hydroxychloroquine ameliorates bleomycin-induced pulmonary fibrosis in rats by inhibiting TGF-β1/Smad2/3 signaling pathway

Pulmonary fibrosis (PF) is a lethal disease characterized by a progressive decline in lung function. Currently, lung transplantation remains the only available treatment for PF. However, both artemisinin (ART) and hydroxychloroquine (HCQ) possess potential antifibrotic properties. This study aimed to investigate the effects and mechanisms of a compound known as Artemisinin-Hydroxychloroquine (AH) in treating PF, specifically by targeting the TGF-β1/Smad2/3 pathway. To do this, we utilized an animal model of PF induced by a single tracheal drip of bleomycin (BLM) in Sprague-Dawley (SD) rats. The PF animal models were administered various doses of AH, and the efficacy and safety of AH were evaluated through pulmonary function testing, blood routine tests, serum biochemistry tests, organ index measurements, and pathological examinations. Additionally, Elisa, western blotting, and qPCR techniques were employed to explore the potential molecular mechanisms of AH in treating PF. Our findings reveal that AH effectively and safely alleviate PF by inhibiting BLM-induced specific inflammation, reducing extracellular matrix (ECM) deposition, and interfering with the TGF-β1/Smad2/3 signaling pathway. Notably, the windfall for this study is that the inhibition of ECM may initiate self-healing in the BLM-induced PF animal model. In conclusion, AH shows promise as a potential therapeutic drug for PF, as it inhibits disease progression through the TGF-β1/Smad2/3 signaling pathway.

99mTc-Labeled FAPI SPECT Imaging in Idiopathic Pulmonary Fibrosis: Preliminary Results

AIM

Idiopathic pulmonary fibrosis (IPF) is associated with a poor prognosis, presenting the most aggressive form of interstitial lung diseases (ILDs). Activated fibroblasts are crucial for pathological processes. Fibroblast activation protein (FAP) inhibitor (FAPI) tracers would be promising imaging agents for these diseases. The purpose of this study was to evaluate a 99mTc-labeled FAPI tracer, 99mTc-HFAPI imaging in IPF patients.

METHODS

Eleven IPF patients (nine males and two females; age range 55-75 year) were included in this pilot study. 99mTc-HFAPI serial whole-body scintigraphy at 5 min, 20 min, 40 min, 1 h, 2 h, 3 h, 4 h, and 6 h was acquired for dynamic biodistribution and dosimetry estimation in seven representative patients. SPECT/CT tomography fusion imaging of the chest region was performed in all patients at 4 h post-injection, which was considered as the optimal acquisition time. Dosimetry was calculated using OLINDA/EXM software (version 2.0; HERMES Medical Solutions). The quantified or semi-quantified standardized uptake values (SUVs) and lesion-to-background ratios (LBRs) of affected lung parenchyma were also calculated. The high-resolution CT (HRCT) stage was determined with visual evaluation, and the total HRCT score of each patient was measured using a weighting factor formula. Pulmonary function tests (PFTs) were recorded as well. Then, the relationships between the 99mTc-HFAPI results, disease extent on HRCT, and PFT results were investigated.

RESULTS

Normal physiological uptake of 99mTc-HFAPI was observed mainly in the liver, intestinal tract, pancreas, gallbladder, and to a lesser extent in the spleen, kidneys, and thyroid, with no apparent retention in the blood circulation at the late time point. The mean injected activity of 99mTc-HFAPI was 813.4 MBq (range 695.6-888.0 MBq). No subjective side effects were noticed. The average whole-body effective dose was 0.0041 mSv/MBq per patient. IPF patients exhibited elevated pulmonary 99mTc-HFAPI uptake in abnormal lung regions, which was correlated with fibrotic regions on HRCT. Among different HRCT stage groups, both SUVmax and LBR showed significant differences (p < 0.001). The higher HRCT stage demonstrated significantly higher SUVmax and LBR. A linear correlation between 99mTc-HFAPI uptake and total HRCT score was observed for SUVmax (r = 0.7839, F = 54.41, p = 0.0094) and LBR (r = 0.7402, F = 56.33, p = 0.0092). 99mTc-HFAPI uptake also had moderate correlations with PFT results.

CONCLUSIONS

Our preliminary data show that the 99mTc-HFAPI SPECT imaging is a promising new imaging modality in IPF patients. Investigations of its clinical value in monitoring disease progression and treatment response are needed in the future.

Modeling fibrotic alveolar transitional cells with pluripotent stem cell-derived alveolar organoids

Repeated injury of the lung epithelium is proposed to be the main driver of idiopathic pulmonary fibrosis (IPF). However, available therapies do not specifically target the epithelium and human models of fibrotic epithelial damage with suitability for drug discovery are lacking. We developed a model of the aberrant epithelial reprogramming observed in IPF using alveolar organoids derived from human-induced pluripotent stem cells stimulated with a cocktail of pro-fibrotic and inflammatory cytokines. Deconvolution of RNA-seq data of alveolar organoids indicated that the fibrosis cocktail rapidly increased the proportion of transitional cell types including the KRT5 - /KRT17 + aberrant basaloid phenotype recently identified in the lungs of IPF patients. We found that epithelial reprogramming and extracellular matrix (ECM) production persisted after removal of the fibrosis cocktail. We evaluated the effect of the two clinically approved compounds for IPF, nintedanib and pirfenidone, and found that they reduced the expression of ECM and pro-fibrotic mediators but did not completely reverse epithelial reprogramming. Thus, our system recapitulates key aspects of IPF and is a promising system for drug discovery.

Rituximab for steroid-resistant organising pneumonia in a woman with rheumatoid arthritis

Organising pneumonia (OP) is a form of interstitial pneumonia characterised by inflammation and scarring leading to obstruction within the small airways and alveoli. Practice guidelines recommend treatment of moderate to severe OP with glucocorticoids; however, there have been cases of steroid-resistant OP successfully treated with rituximab. We describe a case of a woman in her 20s with rheumatoid arthritis who presented with pleuritic chest pain, haemoptysis and dyspnoea on exertion and was diagnosed with OP after multiple radiographic images and biopsies. The patient failed numerous treatment regimens, including corticosteroids, antibiotics and mycophenolate, but was successfully treated with rituximab. This case highlights the importance of identifying new therapeutic agents that will minimise the use of glucocorticoids in the treatment of OP.

Syndrome of Combined Pulmonary Fibrosis and Emphysema: An Official ATS/ERS/JRS/ALAT Research Statement

Background: The presence of emphysema is relatively common in patients with fibrotic interstitial lung disease. This has been designated combined pulmonary fibrosis and emphysema (CPFE). The lack of consensus over definitions and diagnostic criteria has limited CPFE research. Goals: The objectives of this task force were to review the terminology, definition, characteristics, pathophysiology, and research priorities of CPFE and to explore whether CPFE is a syndrome. Methods: This research statement was developed by a committee including 19 pulmonologists, 5 radiologists, 3 pathologists, 2 methodologists, and 2 patient representatives. The final document was supported by a focused systematic review that identified and summarized all recent publications related to CPFE. Results: This task force identified that patients with CPFE are predominantly male, with a history of smoking, severe dyspnea, relatively preserved airflow rates and lung volumes on spirometry, severely impaired DlCO, exertional hypoxemia, frequent pulmonary hypertension, and a dismal prognosis. The committee proposes to identify CPFE as a syndrome, given the clustering of pulmonary fibrosis and emphysema, shared pathogenetic pathways, unique considerations related to disease progression, increased risk of complications (pulmonary hypertension, lung cancer, and/or mortality), and implications for clinical trial design. There are varying features of interstitial lung disease and emphysema in CPFE. The committee offers a research definition and classification criteria and proposes that studies on CPFE include a comprehensive description of radiologic and, when available, pathological patterns, including some recently described patterns such as smoking-related interstitial fibrosis. Conclusions: This statement delineates the syndrome of CPFE and highlights research priorities.

Connective Tissue Growth Factor in Idiopathic Pulmonary Fibrosis: Breaking the Bridge

CTGF is upregulated in patients with idiopathic pulmonary fibrosis (IPF), characterized by the deposition of a pathological extracellular matrix (ECM). Additionally, many omics studies confirmed that aberrant cellular senescence-associated mitochondria dysfunction and metabolic reprogramming had been identified in different IPF lung cells (alveolar epithelial cells, alveolar endothelial cells, fibroblasts, and macrophages). Here, we reviewed the role of the CTGF in IPF lung cells to mediate anomalous senescence-related metabolic mechanisms that support the fibrotic environment in IPF.

Cigarette Smoke Particle-Induced Lung Injury and Iron Homeostasis

It is proposed that the mechanistic basis for non-neoplastic lung injury with cigarette smoking is a disruption of iron homeostasis in cells after exposure to cigarette smoke particle (CSP). Following the complexation and sequestration of intracellular iron by CSP, the host response (eg, inflammation, mucus production, and fibrosis) attempts to reverse a functional metal deficiency. Clinical manifestations of this response can present as respiratory bronchiolitis, desquamative interstitial pneumonitis, pulmonary Langerhans’ cell histiocytosis, asthma, pulmonary hypertension, chronic bronchitis, and pulmonary fibrosis. If the response is unsuccessful, the functional deficiency of iron progresses to irreversible cell death evident in emphysema and bronchiectasis. The subsequent clinical and pathological presentation is a continuum of lung injuries, which overlap and coexist with one another. Designating these non-neoplastic lung injuries after smoking as distinct disease processes fails to recognize shared relationships to each other and ultimately to CSP, as well as the common mechanistic pathway (ie, disruption of iron homeostasis).

The Hedgehog Signaling Pathway in Idiopathic Pulmonary Fibrosis: Resurrection Time

The hedgehog (Hh) pathway is a sophisticated conserved cell signaling pathway that plays an essential role in controlling cell specification and proliferation, survival factors, and tissue patterning formation during embryonic development. Hh signal activity does not entirely disappear after development and may be reactivated in adulthood within tissue-injury-associated diseases, including idiopathic pulmonary fibrosis (IPF). The dysregulation of Hh-associated activating transcription factors, genomic abnormalities, and microenvironments is a co-factor that induces the initiation and progression of IPF.

Ageing mechanisms that contribute to tissue remodeling in lung disease

Age is a major risk factor for chronic respiratory diseases such as idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and certain phenotypes of asthma. The recent COVID-19 pandemic also highlights the increased susceptibility of the elderly to acute respiratory distress syndrome (ARDS), a diffuse inflammatory lung injury with often long-term effects (ie parenchymal fibrosis). Collectively, these lung conditions are characterized by a pathogenic reparative process that, rather than restoring organ function, contributes to structural and functional tissue decline. In the ageing lung, the homeostatic control of wound healing following challenge or injury has an increased likelihood of being perturbed, increasing susceptibility to disease. This loss of fidelity is a consequence of a diverse range of underlying ageing mechanisms including senescence, mitochondrial dysfunction, proteostatic stress and diminished autophagy that occur within the lung, as well as in other tissues, organs and systems of the body. These ageing pathways are highly interconnected, involving localized and systemic increases in inflammatory mediators and damage associated molecular patterns (DAMPs); along with corresponding changes in immune cell function, metabolism and composition of the pulmonary and gut microbiomes. Here we comprehensively review the roles of ageing mechanisms in the tissue remodeling of lung disease.

Cellular Senescence: Pathogenic Mechanisms in Lung Fibrosis

Pulmonary fibrosis is a chronic and fatal lung disease that significantly impacts the aging population globally. To date, anti-fibrotic, immunosuppressive, and other adjunct therapy demonstrate limited efficacies. Advancing our understanding of the pathogenic mechanisms of lung fibrosis will provide a future path for the cure. Cellular senescence has gained substantial interest in recent decades due to the increased incidence of fibroproliferative lung diseases in the older age group. Furthermore, the pathologic state of cellular senescence that includes maladaptive tissue repair, decreased regeneration, and chronic inflammation resembles key features of progressive lung fibrosis. This review describes regulatory pathways of cellular senescence and discusses the current knowledge on the senescence of critical cellular players of lung fibrosis, including epithelial cells (alveolar type 2 cells, basal cells, etc.), fibroblasts, and immune cells, their phenotypic changes, and the cellular and molecular mechanisms by which these cells contribute to the pathogenesis of pulmonary fibrosis. A few challenges in the field include establishing appropriate in vivo experimental models and identifying senescence-targeted signaling molecules and specific therapies to target senescent cells, known collectively as "senolytic" or "senotherapeutic" agents.

Regulatory Effect of PD1/PD-Ligand 1 (PD-L1) on Treg Cells in Patients with Idiopathic Pulmonary Fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is a serious irreversible lung disease. The mechanism of immune checkpoint in idiopathic pulmonary fibrosis is still unknown.

Material/Methods

First, the expression levels of PD-1/PD-L1 on the surface of CD4+ T cells and the proportion of Treg cells in IPF or controls were detected by flow cytometry. Then, expression of TGF-β in blood samples was detected with ELISA. Moreover, a co-culture system was composed of fibroblasts stimulated by TGF-β and CD4+ T cells from healthy people. The proportions of Treg cells and PD-1 in the co-culture system were detected. In addition, we detected the proportion of Treg cells and the level of collagen-1 after adding PD-1 or PD-L1 protein antibody blocker to the co-culture system.

Results

Flow cytometry revealed the upregulated expression of PD-1/PD-L1 in CD4+ T cells of IPF patients. PD-1 appears to inhibit the differentiation of CD4+ T cells into Treg cells. Co-culture of myofibroblasts and CD4+ T cells induced the generation of collagen-1 and reduced the proliferation of CD4+ T cells. When PD-1 was blocked, the inhibition of Treg cell differentiation was reversed, accompanied by decreased collagen-1 production.

Conclusions

This work identified the molecular mechanism of PD-1 in patients with IPF. It may provide a new perspective on the therapeutic effect of PD-1.

Fibroblasts and their responses to chronic injury in pulmonary fibrosis

The field of pulmonary fibrosis is rapidly expanding as new insights highlight novel mechanisms that influence fibroblast biology and likely promote aberrant and chronic activation of the tissue repair response. Current paradigms suggest repeated epithelial microinjury as a driver for pathology; however, the rapid expansion of pulmonary fibrosis research calls for an overview on how fibroblasts respond to both neighbouring cells and the injury microenvironment. This review seeks to highlight recent discoveries and identify areas that require further research regarding fibroblasts, and their role in pulmonary fibrosis.

Artificial intelligence identifies inflammation and confirms fibroblast foci as prognostic tissue biomarkers in idiopathic pulmonary fibrosis

A large number of fibroblast foci (FF) predict mortality in idiopathic pulmonary fibrosis (IPF). Other prognostic histological markers have not been identified. Artificial intelligence (AI) offers a possibility to quantitate possible prognostic histological features in IPF. We aimed to test the use of AI in IPF lung tissue samples by quantitating FF, interstitial mononuclear inflammation, and intra-alveolar macrophages with a deep convolutional neural network (CNN). Lung tissue samples of 71 patients with IPF from the FinnishIPF registry were analyzed by an AI model developed in the Aiforia® platform. The model was trained to detect tissue, air spaces, FF, interstitial mononuclear inflammation, and intra-alveolar macrophages with 20 samples. For survival analysis, cut-point values for high and low values of histological parameters were determined with maximally selected rank statistics. Survival was analyzed using the Kaplan-Meier method. A large area of FF predicted poor prognosis in IPF (p = 0.01). High numbers of interstitial mononuclear inflammatory cells and intra-alveolar macrophages were associated with prolonged survival (p = 0.01 and p = 0.01, respectively). Of lung function values, low diffusing capacity for carbon monoxide was connected to a high density of FF (p = 0.03) and a high forced vital capacity of predicted was associated with a high intra-alveolar macrophage density (p = 0.03). The deep CNN detected histological features that are difficult to quantitate manually. Interstitial mononuclear inflammation and intra-alveolar macrophages were novel prognostic histological biomarkers in IPF. Evaluating histological features with AI provides novel information on the prognostic estimation of IPF.

Clinical predictors and explant lung pathology of acute exacerbation of idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is characterised by constant threat of acute exacerbation of IPF (AE-IPF). It would be significant to identify risk factors of AE-IPF. We sought to determine the prognostic value of lung transplantation candidacy testing for AE-IPF and describe explant pathology of recipients with and without AE-IPF before lung transplantation.

Methods

Retrospective cohort study of 89 IPF patients listed for lung transplantation. Data included pulmonary function testing, echocardiography, right heart catheterisation, imaging, oesophageal pH/manometry and blood tests. Explanted tissue was evaluated by pulmonary pathologists and correlated to computed tomography (CT) findings.

Results

Out of 89 patients with IPF, 52 were transplanted during stable IPF and 37 had AE-IPF before transplantation (n=28) or death (n=9). There were no substantial differences in candidacy testing with and without AE-IPF. AE-IPF had higher rate of decline of forced vital capacity (FVC) (21±22% versus 4.8±14%, p=0.00019). FVC decline of >15% had a hazard ratio of 7.2 for developing AE-IPF compared to FVC decline of <5% (p=0.004). AE-IPF had more secondary diverse histopathology (82% versus 29%, p<0.0001) beyond diffuse alveolar damage. There was no correlation between ground-glass opacities (GGO) on chest CT at any point to development of AE-IPF (p=0.077), but GGO during AE-IPF predicted secondary pathological process beyond diffuse alveolar damage.

Conclusions

Lung transplantation candidacy testing including reflux studies did not predict AE-IPF besides FVC absolute decline. CT did not predict clinical or pathological AE-IPF. Secondary diverse lung pathology beyond diffuse alveolar damage was present in most AE-IPF, but not in stable IPF.

Transplant candidacy testing fails to predict acute exacerbation of IPF besides FVC absolute decline. Patients transplanted during acute exacerbation of IPF reveal multiple secondary lung histopathological processes beyond the expected DAD.https://bit.ly/3e1CPjO

Idiopathic pulmonary fibrosis: Molecular mechanisms and potential treatment approaches

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive disease with high mortality that commonly occurs in middle-aged and older adults. IPF, characterized by a decline in lung function, often manifests as exertional dyspnea and cough. Symptoms result from a fibrotic process driven by alveolar epithelial cells that leads to increased migration, proliferation, and differentiation of lung fibroblasts. Ultimately, the differentiation of fibroblasts into myofibroblasts, which synthesize excessive amounts of extracellular matrix proteins, destroys the lung architecture. However, the factors that induce the fibrotic process are unclear. Diagnosis can be a difficult process; the gold standard for diagnosis is the multidisciplinary conference. Practical biomarkers are needed to improve diagnostic and prognostic accuracy. High-resolution computed tomography typically shows interstitial pneumonia with basal and peripheral honeycombing. Gas exchange and diffusion capacity are impaired. Treatments are limited, although the anti-fibrotic drugs pirfenidone and nintedanib can slow the progression of the disease. Lung transplantation is often contraindicated because of age and comorbidities, but it improves survival when successful. The incidence and prevalence of IPF has been increasing and there is an urgent need for improved therapies. This review covers the detailed cellular and molecular mechanisms underlying IPF progression as well as current treatments and cutting-edge research into new therapeutic targets.

Pathology and natural history of organ fibrosis

Histopathological assessment of fibrosis focusing on morphological patterns provides important information for the management of patients with chronic diseases of the kidney, liver and the lung. This review summarizes key histopathological features of pulmonary, renal and hepatic fibrosis and discusses advances in the understanding of the pathogenesis of pulmonary fibrosis and pathogenetic insights with translational implications for renal fibrosis. The review also tackles new staging approaches based on liver fibrosis dynamics and evaluation of fibrosis regression, digital pathology and second harmonic generation microscopy methods for hepatic fibrosis assessment and critical appraisal of non-invasive tests for liver and renal fibrosis evaluation.

High Diagnostic Accuracy of Transbronchial Cryobiopsy in Fibrotic Interstitial Lung Diseases Compared to Final Explant Diagnosis

BACKGROUND

A diagnostic lung biopsy may be required in some cases of fibrotic interstitial lung diseases (ILD). Transbronchial cryobiopsy has been suggested as a possible alternative to surgical lung biopsy. However, previous estimates of its diagnostic yield were not validated compared to the definitive diagnosis in explanted lungs.

OBJECTIVES

We aimed to assess the diagnostic accuracy of cryobiopsy in fibrotic ILD patients who subsequently had lung transplantation.

METHODS

All 197 patients who underwent lung transplantation at our Center due to fibrotic ILD from January 2010 to May 2018, were screened for the presence of a pre-transplant cryobiopsy. Fourteen patients who underwent cryobiopsy before transplantation were identified. Two expert lung pathologists blindedto the explant diagnoses, independently examined these cryobiopsy specimens to decide if they match guideline criteria for usual interstitial pneumonia (UIP) pattern or an alternative diagnosis. The primary measure was the diagnostic accuracy of cryobiopsy to detect or refute a UIP pattern, as compared to the final explant diagnosis.

RESULTS

Median time between cryobiopsy and transplantation was 1.4 years. All 14 cryobiopsy samples contained adequate alveolar tissue. The explant diagnosis of 13/14 patients was UIP. The two pathologists correctly diagnosed or refuted UIP in the cryobiopsy specimen in 12/14 cases (85.7%) and 11/14 cases (78.6%), respectively. The level of diagnostic agreement between pathologists was good (kappa 0.59, p = 0.016).

CONCLUSIONS

Compared to the final explant diagnosis, transbronchial cryobiopsy had high diagnostic accuracy and good inter-observer agreement for UIP pattern. These findings support a potential diagnostic role for cryobiopsy in experienced centers.

A single-institution study of concordance of pathological diagnoses for interstitial lung diseases between pre-transplantation surgical lung biopsies and lung explants

BACKGROUND

By comparing diagnoses made by pre-transplant surgical lung biopsy (SLB) and the final pathologic diagnosis of the explanted pathology (EP), we aimed to study the factors that could impact pathologic diagnoses in patients with interstitial lung disease (ILD).

METHODS

We retrospectively reviewed the lung transplant database at Cleveland Clinic [01/01/2006-12/31/2013] to include all lung transplant recipients with a prior diagnosis of ILD. Two pulmonary pathologists independently reviewed each SLB and lung explant. The diagnoses were labeled as concordant (same diagnosis on SLB and explant) or discordant (diagnosis on SLB and explant were different) by consensus.

RESULTS

Of 389 patients transplanted for ILD, 217 had an SLB before transplant. Pathological diagnoses were concordant in 190 patients (87.6%) [165 UIP (86.8%), 13 NSIP (6.8%), 8 CHP (4.2%) and 4 other diagnoses (2.1%). In 27 cases (12.4%), the diagnosis on SLB differed from EP. 8/27 were diagnosed with UIP on SLB and of these, 5 were re-classified as NSIP. 14/19 (73.7%) patients with a SLB diagnosis "other than UIP" were re-categorized as UIP based on explant. Discordant cases had a greater time between SLB and EP than concordant cases (1553 days vs 1248 days).

CONCLUSIONS

The pathologic diagnosis of ILD by SLB prior to lung transplant is accurate in most patients, but may be misleading in a small subset of patients. The majority of discordant cases that were reclassified as UIP could be due to a sampling error, or perhaps, an increased time from the date of the SLB to transplant. Future studies examining how multidisciplinary consensus diagnosis affects this discordance are necessary.

Bronchoscopic lung cryobiopsy: An Indian association for bronchology position statement

BACKGROUND

Bronchoscopic lung cryobiopsy (BLC) is a novel technique for obtaining lung tissue for the diagnosis of diffuse parenchymal lung diseases. The procedure is performed using several different variations of technique, resulting in an inconsistent diagnostic yield and a variable risk of complications. There is an unmet need for standardization of the technical aspects of BLC.

METHODOLOGY

This is a position statement framed by a group comprising experts from the fields of pulmonary medicine, thoracic surgery, pathology, and radiology under the aegis of the Indian Association for Bronchology. Sixteen questions on various technical aspects of BLC were framed. A literature search was conducted using PubMed and EMBASE databases. The expert group discussed the available evidence relevant to each question through e-mail and a face-to-face meeting, and arrived at a consensus.

RESULTS

The experts agreed that patients should be carefully selected for BLC after weighing the risks and benefits of the procedure. Where appropriate, consideration should be given to perform alternate procedures such as conventional transbronchial biopsy or subject the patient directly to a surgical lung biopsy. The procedure is best performed after placement of an artificial airway under sedation/general anesthesia. Fluoroscopic guidance and occlusion balloon should be utilized for positioning the cryoprobe to reduce the risk of pneumothorax and bleeding, respectively. At least four tissue specimens (with at least two of adequate size, i.e., ≥5 mm) should be obtained during the procedure from different lobes or different segments of a lobe. The histopathological findings of BLC should be interpreted by an experienced pulmonary pathologist. The final diagnosis should be made after a multidisciplinary discussion. Finally, there is a need for structured training for performing BLC.

CONCLUSION

This position statement is an attempt to provide practical recommendations for the performance of BLC in DPLDs.

Low-dose administration of bleomycin leads to early alterations in lung mechanics

NEW FINDINGS

What is the central question of this study? When do alterations in pulmonary mechanics occur following chronic low-dose administration of bleomycin? What is the main finding and its importance? Remarkably, we report changes in lung mechanics as early as day 7 that corresponded to parameters determined from single-frequency forced oscillation manoeuvres and pressure-volume loops. These changes preceded substantial histological changes or changes in gene expression levels. These findings are significant to refine drug discovery in idiopathic pulmonary fibrosis, where preclinical studies using lung function parameters would enhance the translational potential of drug candidates where lung function readouts are routinely performed in the clinic.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is the most widespread form of interstitial lung disease and, currently, there are only limited treatment options available. In preclinical animal models of lung fibrosis, the effectiveness of experimental therapeutics is often deemed successful via reductions in collagen deposition and expression of profibrotic genes in the lung. However, in clinical studies, improvements in lung function are primarily used to gauge the success of therapeutics directed towards IPF. Therefore, we examined whether changes in respiratory system mechanics in the early stages of an experimental model of lung fibrosis can be used to refine drug discovery approaches for IPF. C57BL/6J mice were administered bleomycin (BLM) or a vehicle control i.p. twice a week for 4 weeks. At 7, 14, 21, 28 and 33 days into the BLM treatment regimen, indices of respiratory system mechanics and pressure-volume relationships were measured. Concomitant with these measurements, histological and gene analyses relevant to lung fibrosis were performed. Alterations in respiratory system mechanics and pressure-volume relationships were observed as early as 7 days after the start of BLM administration. Changes in respiratory system mechanics preceded the appearance of histological and molecular indices of lung fibrosis. Administration of BLM leads to early changes in respiratory system mechanics that coincide with the appearance of representative histological and molecular indices of lung fibrosis. Consequently, these data suggest that dampening the early changes in respiratory system mechanics might be used to assess the effectiveness of experimental therapeutics in preclinical animal models of lung fibrosis.

Idiopathic Pulmonary Fibrosis (IPF): An Overview

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterised by chronic, progressive scarring of the lungs and the pathological hallmark of usual interstitial pneumonia. Current paradigms suggest alveolar epithelial cell damage is a key initiating factor. Globally, incidence of the disease is rising, with associated high morbidity, mortality, and economic healthcare burden. Diagnosis relies on a multidisciplinary team approach with exclusion of other causes of interstitial lung disease. Over recent years, two novel antifibrotic therapies, pirfenidone and nintedanib, have been developed, providing treatment options for many patients with IPF, with several other agents in early clinical trials. Current efforts are directed at identifying key biomarkers that may direct more customized patient-centred healthcare to improve outcomes for these patients in the future.

The fibrogenic actions of the coagulant and plasminogen activation systems in pulmonary fibrosis

Fibrosis causes irreversible damage to lung structure and function in restrictive lung diseases such as idiopathic pulmonary fibrosis (IPF). Extravascular coagulation involving fibrin formation in the intra-alveolar compartment is postulated to have a pivotal role in the development of pulmonary fibrosis, serving as a provisional matrix for migrating fibroblasts. Furthermore, proteases of the coagulation and plasminogen activation (plasminergic) systems that form and breakdown fibrin respectively directly contribute to pulmonary fibrosis. The coagulants, thrombin and factor Xa (FXa) evoke fibrogenic effects via cleavage of the N-terminus of protease-activated receptors (PARs). Whilst the formation and activity of plasmin, the principle plasminergic mediator is suppressed in the airspaces of patients with IPF, localized increases are likely to occur in the lung interstitium. Plasmin-evoked proteolytic activation of factor XII (FXII), matrix metalloproteases (MMPs) and latent, matrix-bound growth factors such as epidermal growth factor (EGF) indirectly implicate plasmin in pulmonary fibrosis. Another plasminergic protease, urokinase plasminogen activator (uPA) is associated with regions of fibrosis in the remodelled lung of IPF patients and elicits fibrogenic activity via binding its receptor (uPAR). Plasminogen activator inhibitor-1 (PAI-1) formed in the injured alveolar epithelium also contributes to pulmonary fibrosis in a manner that involves vitronectin binding. This review describes the mechanisms by which components of the two systems primarily involved in fibrin homeostasis contribute to interstitial fibrosis, with a particular focus on IPF. Selectively targeting the receptor-mediated mechanisms of coagulant and plasminergic proteases may limit pulmonary fibrosis, without the bleeding complications associated with conventional anti-coagulant and thrombolytic therapies.

The Processes and Mechanisms of Cardiac and Pulmonary Fibrosis

Fibrosis is the formation of fibrous connective tissue in response to injury. It is characterized by the accumulation of extracellular matrix components, particularly collagen, at the site of injury. Fibrosis is an adaptive response that is a vital component of wound healing and tissue repair. However, its continued activation is highly detrimental and a common final pathway of numerous disease states including cardiovascular and respiratory disease. Worldwide, fibrotic diseases cause over 800,000 deaths per year, accounting for ~45% of total deaths. With an aging population, the incidence of fibrotic disease and subsequently the number of fibrosis-related deaths will rise further. Although, fibrosis is a well-recognized cause of morbidity and mortality in a range of disease states, there are currently no viable therapies to reverse the effects of chronic fibrosis. Numerous predisposing factors contribute to the development of fibrosis. Biological aging in particular, interferes with repair of damaged tissue, accelerating the transition to pathological remodeling, rather than a process of resolution and regeneration. When fibrosis progresses in an uncontrolled manner, it results in the irreversible stiffening of the affected tissue, which can lead to organ malfunction and death. Further investigation into the mechanisms of fibrosis is necessary to elucidate novel, much needed, therapeutic targets. Fibrosis of the heart and lung make up a significant proportion of fibrosis-related deaths. It has long been established that the heart and lung are functionally and geographically linked when it comes to health and disease, and thus exploring the processes and mechanisms that contribute to fibrosis of each organ, the focus of this review, may help to highlight potential avenues of therapeutic investigation.

An Official American Thoracic Society Workshop Report: Use of Animal Models for the Preclinical Assessment of Potential Therapies for Pulmonary Fibrosis

Numerous compounds have shown efficacy in limiting development of pulmonary fibrosis using animal models, yet few of these compounds have replicated these beneficial effects in clinical trials. Given the challenges associated with performing clinical trials in patients with idiopathic pulmonary fibrosis (IPF), it is imperative that preclinical data packages be robust in their analyses and interpretations to have the best chance of selecting promising drug candidates to advance to clinical trials. The American Thoracic Society has convened a group of experts in lung fibrosis to discuss and formalize recommendations for preclinical assessment of antifibrotic compounds. The panel considered three major themes (choice of animal, practical considerations of fibrosis modeling, and fibrotic endpoints for evaluation). Recognizing the need for practical considerations, we have taken a pragmatic approach. The consensus view is that use of the murine intratracheal bleomycin model in animals of both genders, using hydroxyproline measurements for collagen accumulation along with histologic assessments, is the best-characterized animal model available for preclinical testing. Testing of antifibrotic compounds in this model is recommended to occur after the acute inflammatory phase has subsided (generally after Day 7). Robust analyses may also include confirmatory studies in human IPF specimens and validation of results in a second system using in vivo or in vitro approaches. The panel also strongly encourages the publication of negative results to inform the lung fibrosis community. These recommendations are for preclinical therapeutic evaluation only and are not intended to dissuade development of emerging technologies to better understand IPF pathogenesis.

Interstitial Pneumonia With Autoimmune Features: Value of Histopathology

CONTEXT

- Patients with idiopathic interstitial pneumonia may display evidence of autoimmunity without meeting criteria for a defined connective tissue disease. A recent European Respiratory Society/American Thoracic Society statement proposed research criteria for interstitial pneumonia with autoimmune features (IPAF), which includes findings from the clinical, serologic, and morphologic domains.

OBJECTIVES

- To investigate the importance of histopathologic criteria within the morphologic domain and to report our methodology for identifying these features.

DESIGN

- Patients with idiopathic interstitial pneumonia at the University of Chicago who underwent surgical lung biopsy or lung transplantation were assessed for IPAF histopathologic features, using the initial pathology interpretation in the electronic records. A focused rereview of available slides by a pulmonary pathologist was then performed for patients who failed to meet IPAF criteria on initial pathology assessment.

RESULTS

- Of 422 patients with idiopathic interstitial pneumonia, 176 (41.7%) underwent surgical lung biopsy or lung transplant. Forty-six of those 176 patients (26.1%) met IPAF criteria by initial pathology interpretation and a positive clinical or serologic feature. Of the remaining 130 patients, 73 (56.2%) met either the clinical or serologic domains without meeting the morphologic domain, whereas 36 (27.7%) had slides available for pathology rereview. This rereview demonstrated nonspecific interstitial pneumonia in 8 of 36 patients (22.2%) and lymphoplasmacytic infiltrates in 6 of 36 patients (16.7%), resulting in an additional 7 of 36 patients (19.4%) with idiopathic interstitial pneumonia that met the IPAF criteria. In IPAF, pulmonary vasculopathy was the most prevalent finding (45 of 84; 53.6%) and predicted increased mortality (hazard ratio, 2.5; P = .04).

CONCLUSIONS

- Using a methodological approach to identifying IPAF pathology, we demonstrate a significant increase in the number of patients meeting IPAF criteria because of focused pathologic review and highlight the prognostic value of the IPAF pathologic findings.

Transbronchial Cryobiopsy in Diffuse Lung Disease: Update for the Pathologist

CONTEXT

- Transbronchial cryobiopsy has recently been proposed as an alternative to surgical biopsy in the diagnosis of diffuse lung disease.

OBJECTIVE

- To familiarize pathologists with transbronchial cryobiopsy, including what it is, how it is performed, how it compares to other techniques of lung biopsy in diffuse lung disease, what are the technical issues relating to it, what the complications are, how cryobiopsies should be interpreted, and the clinical usefulness of cryobiopsy.

DATA SOURCES

- All the available literature on cryobiopsy in diffuse lung disease through May 2016, primarily in the last 5 years, was reviewed, and some unpublished data known to the authors were included.

CONCLUSIONS

- Cryobiopsies are considerably larger than forceps biopsies and allow pattern recognition approaching that of a surgical lung biopsy in many cases. Artifacts associated with cryobiopsy are minimal. In comparison with surgical lung biopsies, the diagnosis rate with cryobiopsies is lower, in the neighborhood of 80%, versus higher than 90% for surgical lung biopsies. Cryobiopsy is proposed as an alternative to surgical lung biopsy and a technique that may appreciably decrease the number of patients who require surgical lung biopsy for diagnosis. This is important because the mortality from cryobiopsy is very small (0.1% to date) compared with surgical lung biopsy (1.7% for elective procedures and considerably higher for nonelective procedures).