Pulmonary function testing in idiopathic interstitial pneumonias

Follistatin-respiratory connection predicting all-cause mortality among community-dwelling middle-to-old age individuals: Results from the I-Lan Longitudinal Study

OBJECTIVES

The link between aging and pulmonary function decline is well-established, but the underlying mechanisms have yet to be fully revealed. Serum follistatin, a myokine implicated in muscle degeneration, may play a role in age-related pulmonary changes. This study aims to investigate the relationship between serum follistatin levels and pulmonary function decline in community-dwelling older adults, and evaluate their combined association with all-cause mortality.

RESEARCH DESIGN AND METHODS

This longitudinal cohort study utilized data from 751 participants aged ≥50 years in the I-Lan Longitudinal Aging Study between 2018-2019. Serum follistatin levels, spirometry results, demographic and clinical data were retrieved. Participants were stratified based on their follistatin levels. Survival curves and group comparisons based on follistatin levels and decline in peak expiratory flow (PEF) using Kaplan-Meier analysis and log-rank tests. Multivariate Cox proportional hazards models were further used to identify independent predictors of all-cause mortality during the 52-month follow-up.

RESULTS

Elevated follistatin levels significantly correlated with worse pulmonary function, particularly decreased PEF (p = 0.030). Kaplan-Meier analysis revealed the combination of elevated follistatin levels and decreased PEF was associated with increased risk of all-cause mortality (Log-rank p = 0.023). Cox proportional hazards models further identified that concurrent presence of higher follistatin levels and decreased PEF predicted higher risk of all-cause mortality (adjusted HR 3.58, 95% CI: 1.22-10.53, p = 0.020).

CONCLUSION

Higher serum follistatin levels correlate with decreased pulmonary function, specifically PEF decline, in community-dwelling older adults. Furthermore, the coexistence of elevated follistatin levels and decreased PEF was associated with risk of all-cause mortality. Follistatin may serve as a biomarker for pulmonary aging and related adverse outcomes.

A quantitative analysis of progressive fibrosing interstitial lung disease on computed tomography for the assessment of decreased vital capacity

BACKGROUND

The results of a quantitative analysis of computed tomography (CT) of interstitial lung disease (ILD) using a computer-aided detection (CAD) technique were correlated with the results of pulmonary function tests.

PURPOSE

To evaluate the correlation between a quantitative analysis of CT of progressive fibrosing interstitial lung disease (PF-ILD) including idiopathic pulmonary fibrosis (IPF) and non-IPF, which can manifest progressive pulmonary fibrosis and the vital capacity (VC), and to identify indicators for the assessment of a decreased VC.

MATERIAL AND METHODS

A total of 73 patients (46 patients with IPF and 27 patients with non-IPF) were included in this study. Associations between the quantitative analysis of CT and the %VC using a CAD software program were investigated using Spearman's rank correlation and a logistic regression analysis. The appropriate cutoff vale for predicting a decreased VC was determined (%VC <80) and the area under the curve (AUC) was calculated.

RESULTS

A multiple logistic regression analysis showed that the total extent of interstitial pneumonia on CT was a significant indicator of a decreased VC (P = 0.0001; odds ratio [OR]=1.15; 95% confidence interval [CI]=1.06-1.27 in IPF and P = 0.0025; OR=1.16; 95% CI=1.03-1.30 in non-IPF). The cutoff values of the total extent of interstitial pneumonia in IPF and non-IPF for predicting a decreased VC were determined to be 23.3% and 21.5%, and the AUCs were 0.83 and 0.91, respectively.

CONCLUSION

A quantitative analysis of CT of PF-ILD using a CAD software program could be useful for predicting a decreased VC.

Genetic association between smoking and DLCO in idiopathic pulmonary fibrosis patients

BACKGROUND

Observational studies have shown that smoking is related to the diffusing capacity of the lungs for carbon monoxide (DLCO) in individuals with idiopathic pulmonary fibrosis (IPF). Nevertheless, further investigation is needed to determine the causal effect between these two variables. Therefore, we conducted a study to investigate the causal relationship between smoking and DLCO in IPF patients using two-sample Mendelian randomization (MR) analysis.

METHODS

Large-scale genome-wide association study (GWAS) datasets from individuals of European descent were analysed. These datasets included published lifetime smoking index (LSI) data for 462,690 participants and DLCO data for 975 IPF patients. The inverse-variance weighting (IVW) method was the main method used in our analysis. Sensitivity analyses were performed by MR‒Egger regression, Cochran's Q test, the leave-one-out test and the MR-PRESSO global test.

RESULTS

A genetically predicted increase in LSI was associated with a decrease in DLCO in IPF patients [ORIVW = 0.54; 95% CI 0.32-0.93; P = 0.02].

CONCLUSIONS

Our study suggested that smoking is associated with a decrease in DLCO. Patients diagnosed with IPF should adopt an active and healthy lifestyle, especially by quitting smoking, which may be effective at slowing the progression of IPF.

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 impact of respiratory reactance in oscillometry on survival in patients with idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with a poor prognosis. Pulmonary function tests (PFTs) aid in evaluating the disease status of IPF. The clinical significance of oscillometry measurements in interstitial lung diseases has recently been reported. Our previous study showed that respiratory reactance (Xrs) measured by oscillometry reflected disease severity and predicted subsequent lung capacity decline in patients with IPF. However, the direct impact of Xrs on survival needs to be determined, and there are currently no reference values in oscillometry to predict prognosis. Therefore, this study aimed to investigate the association between oscillometry measurements, particularly Xrs, and survival in patients with IPF and to determine the cutoff values of Xrs that predict 3-year survival.

METHODS

We analyzed the relationship between the measured values of PFT and oscillometry derived from 178 patients with IPF. Univariate and multivariate Cox proportional hazards analyses were performed to investigate the relationships between clinical indices at the time of the first oscillometry and survival. We performed the time-dependent receiver operating characteristic (ROC) curve analysis to set the optimized cutoff values of Xrs for 3-year survival prediction. We examined the discriminating power of cutoff values of Xrs on survival using the Kaplan-Meier method and the log-rank test.

RESULTS

Xrs components, especially in the inspiratory phase (In), significantly correlated with the PFT values. In the multivariate analyses, Xrs (all of reactance at 5 Hz [X5], resonant frequency [Fres], and low-frequency reactance area [ALX] in the inspiratory phase) had a significant impact on survival (X5, p = 0.003; Fres, p = 0.016; ALX, p = 0.003) independent of age, sex, and other prognostic factors derived from the univariate analysis. The area under the ROC curve was 0.765, 0.759, and 0.766 for X5 In, Fres In, and ALX In, with cutoff values determined at - 0.98, 10.67, and 5.32, respectively. We found significant differences in survival after dividing patients using each of the cutoff values of Xrs.

CONCLUSIONS

In patients with IPF, Xrs measured by oscillometry significantly impacted survival. We also determined the cutoff values of Xrs to discriminate patients with poor prognoses.

A three-gene random forest model for diagnosing idiopathic pulmonary fibrosis based on circadian rhythm-related genes in lung tissue

BACKGROUND

The disorder of circadian rhythm could be a key factor mediating fibrotic lung disease Therefore, our study aims to determine the diagnostic value of circadian rhythm-related genes (CRRGs) in IPF.

METHODS

We retrieved the data on CRRGs from previous studies and the GSE150910 dataset. The participants from the GSE150910 dataset were divided into training and internal validation sets. Next, we used several various bioinformatics methods and machine learning algorithms to screen genes. Next, we identified SEMA5A, COL7A1, and TUBB3, which were included in the random forest (RF) diagnostic model. Finally, external validation was conducted on data retrieved from the GSE184316 datasets.

RESULTS

The results revealed that the RF diagnostic model could diagnose patients with IPF in the internal validation set with the area under the ROC curve (AUC) value of 0.905 and in the external validation with the AUC value of 0.767. Furthermore, real-time quantitative PCR and western blotting results revealed a significant decrease in SEMA5A (p < 0.05) expression level and an increase in COL7A1 and TUBB3 expression levels in TGF-β1-treated normal human lung fibroblasts.

CONCLUSION

We constructed an RF diagnostic model based on SEMA5A, COL7A1, and TUBB3 expression in lung tissue for diagnosing patients with IPF.

Progressive fibrotic interstitial lung disease

Many interstitial lung diseases (ILDs) share mechanisms that result in a progressive fibrosing phenotype. In Brazil, the most common progressive fibrosing interstitial lung diseases (PF-ILDs) are chronic hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, unclassified ILD, and connective tissue diseases. PF-ILD is seen in approximately 30% of patients with ILD. Because PF-ILD is characterized by disease progression after initiation of appropriate treatment, a diagnosis of the disease resulting in fibrosis is critical. Different criteria have been proposed to define progressive disease, including worsening respiratory symptoms, lung function decline, and radiological evidence of disease progression. Although the time elapsed between diagnosis and progression varies, progression can occur at any time after diagnosis. Several factors indicate an increased risk of progression and death. In the last few years, antifibrotic drugs used in patients with idiopathic pulmonary fibrosis have been tested in patients with PF-ILD. The effects of nintedanib and placebo have been compared in patients with PF-ILD, a mean difference of 107.0 mL/year being observed, favoring nintedanib. The U.S. Food and Drug Administration and the Brazilian Health Regulatory Agency have approved the use of nintedanib in such patients on the basis of this finding. Pirfenidone has been evaluated in patients with unclassified ILD and in patients with other ILDs, the results being similar to those for nintedanib. More studies are needed in order to identify markers of increased risk of progression in patients with ILD and determine the likelihood of response to treatment with standard or new drugs.

Idiopathic Pulmonary Fibrosis and Post-COVID-19 Lung Fibrosis: Links and Risks

Idiopathic pulmonary fibrosis (IPF) is considered the paradigmatic example of chronic progressive fibrosing disease; IPF does not result from a primary immunopathogenic mechanism, but immune cells play a complex role in orchestrating the fibrosing response. These cells are activated by pathogen-associated or danger-associated molecular patterns generating pro-fibrotic pathways or downregulating anti-fibrotic agents. Post-COVID pulmonary fibrosis (PCPF) is an emerging clinical entity, following SARS-CoV-2 infection; it shares many clinical, pathological, and immune features with IPF. Similarities between IPF and PCPF can be found in intra- and extracellular physiopathological pro-fibrotic processes, genetic signatures, as well as in the response to antifibrotic treatments. Moreover, SARS-CoV-2 infection can be a cause of acute exacerbation of IPF (AE-IPF), which can negatively impact on IPF patients’ prognosis. In this narrative review, we explore the pathophysiological aspects of IPF, with particular attention given to the intracellular signaling involved in the generation of fibrosis in IPF and during the SARS-CoV-2 infection, and the similarities between IPF and PCPF. Finally, we focus on COVID-19 and IPF in clinical practice.

Infectious Pneumonia and Lung Ultrasound: A Review

The application of thoracic ultrasound examination has not long been developed because ultrasound's interaction with the lung does not generate an anatomical image but an artifactual one. Subsequently, the evaluation of pulmonary artifacts and their correlation to specific diseases allowed the development of ultrasound semantics. Currently, pneumonia still represents one of the main causes of hospitalization and mortality. Several studies in the literature have demonstrated the ultrasound features of pneumonia. Although ultrasound cannot be considered the diagnostic gold standard for the study of all lung diseases, it has experienced an extraordinary development and growth of interest due to the SARS-CoV-2 pandemic. This review aims to provide essential information on the application of lung ultrasound to the study of infectious pneumonia and to discuss the differential diagnosis.

Interstitial Lung Disease: A Focused Review for the Emergency Clinician

BACKGROUND

Interstitial lung disease (ILD) is a group of restrictive pulmonary diseases associated with diffuse interstitial and parenchymal inflammation. Patients can present to the emergency department with severe exacerbation.

OBJECTIVE

This narrative review provides emergency clinicians with the most recent evidence concerning acute exacerbation of ILD (AE-ILD).

DISCUSSION

AE-ILD can present as acute respiratory distress in a patient with a pre-existing ILD diagnosis or as a de novo presentation of ILD, and is associated with significant morbidity and mortality. A variety of underlying triggers may result in AE-ILD. Emergency clinicians must first assess for extraneous causes of respiratory decompensation prior to diagnosing AE-ILD. For a de novo presentation of ILD, emergency physicians should also assess for possible reversible causes. AE-ILD is managed with systemic steroids, immunosuppressants, intravenous antibiotics, supplemental oxygen, and extracorporeal membrane oxygenation in severe cases. Given the high mortality rates in the absence of lung transplantation, early referral to transplant centers is essential to increase chances of survival.

CONCLUSIONS

Emergency clinician knowledge of AE-ILD can improve the evaluation and management of these patients.

The impact of FVC/DLCO ratio on diagnosis of pulmonary hypertension and disease prognosis in idiopathic pulmonary fibrosis

Introduction: Idiopathic pulmonary fibrosis is a chronic progressive fibrotic lung disease of unknown etiology that occurs most commonly in older adults. The presence of pulmonary hypertension in Idiopathic pulmonary fibrosis is associated with poor prognosis and mortality. Literature suggests that the forced vital capacity to diffusion capacity of the lung for carbon monoxide ratio has a positive predictive value for the diagnosis of pulmonary hypertension. Therefore, this study aimed to investigate the impact of forced vital capacity to diffusion capacity of the lung for carbon monoxide ratio on the diagnosis of pulmonary hypertension and disease prognosis in Idiopathic pulmonary fibrosis patients. MATERIAL AND METHOD: Forty-eight patients diagnosed with Idiopathic pulmonary fibrosis were included in the study. Patient records, echocardiographic and spirometric data were retrospectively reviewed. Results: The average pulmonary arterial pressure was observed to be 32.8 (±9) mmHg, with the second-year follow-up pulmonary arterial pressure at 40.8 (±17.2) mmHg and the fourth-year follow-up pulmonary arterial pressure at 51 (±23.6) mmHg. In those diagnosed as pulmonary hypertension, the forced vital capacity to diffusion capacity of the lung for carbon monoxide ratio was initially 1.54 (±0.72). By the second year, it was 1.61 (±0.45), and by the fourth year, it was 1.87 (±0.8). It was found that the forced vital capacity to diffusion capacity of the lung for carbon monoxide ratio tended to increase when pulmonary artery pressure increased during the follow-up period. Conclusion: We found that low six- minute walking test distance was an important marker for the diagnosis of pulmonary hypertension in patients with idiopathic pulmonary fibrosis and that the presence of desaturation was also significantly associated with survival in pulmonary hypertension. Although we did not find it statistically significant, we found that both pulmonary arterial pressure and the the forced vital capacity to diffusion capacity of the lung for carbon monoxide ratio increased with progressive disease duration after diagnosis in patients with IPF. We believe that the the forced vital capacity to diffusion capacity of the lung for carbon monoxide ratio is an important marker for early detection of pulmonary hypertension and prognosis in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis is defined as a chronic progressive fibrosing interstitial pneumonia of unknown etiology. There are intrinsic and extrinsic risk factors that could favor the development of the disease in individuals with a genetic predisposition. The diagnosis is made by characteristic radiological and/or histological findings on high-resolution computed tomography and lung biopsy, respectively, in the absence of a specific identifiable cause. The median survival of the disease for patients without treatment is 3-5years from the onset of symptoms, although its natural history is variable and unpredictable. Currently, there are two antifibrotic drugs that reduce disease progression. The multidisciplinary approach will consider the nutritional and emotional status, physical conditioning, and treatment of comorbidities, as well as lung transplantation and palliative care in advanced stages. The following article reviews the fundamental aspects for the diagnosis and treatment of idiopathic pulmonary fibrosis.

Aging and Susceptibility to Pulmonary Disease

The lungs are continually subjected to noxious and inert substances, are immunologically active, and are in a constant state of damage and repair. This makes the pulmonary system particularly vulnerable to diseases of aging. Aging can be understood as random molecular damage that is unrepaired and accumulates over time, resulting in cellular defects and tissue dysfunction. The breakdown of cellular mechanisms, including stem cell exhaustion, genomic instability, telomere attrition, epigenetic alteration, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, altered intercellular communication, and changes in the extracellular matrix is thought to advance the aging process itself. Chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and cancers illustrate a pathologic breakdown in these mechanisms beyond normal aging. The immune system becomes less effective with advancing age. There is a low-level state of chronic inflammation termed inflammaging which is thought to be driven by immunosenescence, the changes in the innate and adaptive immune systems with advancing age that lead to dysregulation and decreased effectiveness of the immune system. These processes of aging lead to expected changes in the form and function of the respiratory system, most notably a loss of lung elasticity, decrease in respiratory muscle strength, increase in ventilation-perfusion mismatching, and stiffening of the vasculature. The astute clinician is aware of these expected findings and does not often attribute dyspnea to aging alone. Maintaining a low threshold to investigate for comorbid disease and understanding how pulmonary disease presents differently in the elderly than in younger adults can improve clinical outcomes. © 2022 American Physiological Society. Compr Physiol 12:3509-3522, 2022.

Pulmonary vascular volume is associated with DLCO and fibrotic score in idiopathic pulmonary fibrosis: an observational study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a disease that primarily occurs in elderly individuals. However, it is difficult to diagnose and has a complex disease course. High-resolution computed tomography (HRCT) and lung function testing are crucial for its diagnosis and follow-up. However, the correlation of HRCT findings with lung function test results has not been extensively investigated.

METHODS

This study retrospectively analysed the medical records and images of patients with IPF. Patients with evident emphysema and lung cancer were excluded. The diagnosis of all the included cases was confirmed following a discussion among specialists from multiple disciplines. The correlation of HRCT findings, including fibrotic score, HRCT lung volume, pulmonary artery trunk (PA) diameter and pulmonary vascular volume (PVV), with lung function test parameters, such as forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO), was analysed.

RESULTS

A total of 32 patients were included. Higher fibrotic and PVV scores were significantly correlated with lower DLCO (r =  - 0.59, p = 0.01; r =  - 0.43, p = 0.03, respectively) but not with FVC. Higher PVV score significantly correlated with higher fibrotic score (r = 0.59, p < 0.01) and PA diameter (r = 0.47, p = 0.006).

CONCLUSION

Our study demonstrated the structural and functional correlation of IPF. The extent of lung fibrosis (fibrotic score) and PVV score were associated with DLCO but not with FVC. The PA diameter, which reflects the pulmonary artery pressure, was found to be associated with the PVV score.

Arterial partial pressure of oxygen and diffusion function as prognostic biomarkers for acute pulmonary embolism

BACKGROUND

Risk stratification for acute pulmonary embolism (PE) ignores the roles of respiratory function and gas exchange. We aimed to identify the role of arterial partial pressure of oxygen (PO2) and diffusion function as prognostic biomarkers.

METHODS

We collected the data from hospitalised patients with acute PE. We used Spearman's correlation coefficient and Cox regression analysis to explore the clinical and prognostic values of PO2 and predicted percentage diffusing lung capacity for carbon monoxide (DLCO%pred) to predict the 30-day mortality.

RESULTS

We included 309 patients (mean age: 67.93 ± 13.31 years); 46.6% were men, and 12.62% were haemodynamically unstable. The 30-day all-cause mortality rates in the high-, intermediate high-, intermediate low-, and low-risk groups were 7.7%, 4.7%, 2.9%, and 0.0%, respectively (P < 0.05). PO2 (P = 0.012) and DLCO%pred (P = 0.036) were significantly different between the four risk groups. There were strong correlations between PO2, DLCO%pred, PO2*DLCO%pred, and other markers (P < 0.05), especially troponin I, N-terminal pro-brain natriuretic peptide, and systolic pulmonary artery pressure. PO2 and PO2*DLCO%pred were prognostic factors for death in haemodynamically stable patients (hazard ratio [HR] 0.618, 95% confidence interval [CI] 0.389-0.980, P = 0.041, and HR 0.501, 95% CI 0.26-0.96, P = 0.036, respectively). A lower PO2 (<8 kPa) was associated with a higher risk of mortality in all patients and in haemodynamically stable ones (HR 9.462, 95% CI 2.365-37.860, P = 0.001, and HR 6.597, 95% CI 1.102-39.495, P = 0.039, respectively).

CONCLUSIONS

PO2, PO2*DLCO%pred, and PO2 < 8 kPa were predictors of 30-day all-cause mortality in all patients and haemodynamically stable ones.

TRIAL REGISTRATION

ChiCTR2000030448.

Exploring the 175-year history of spirometry and the vital lessons it can teach us today

175 years have elapsed since John Hutchinson introduced the world to his version of an apparatus that had been in development for nearly two centuries, the spirometer. Though he was not the first to build a device that sought to measure breathing and quantify the impact of disease and occupation on lung function, Hutchison coined the terms spirometer and vital capacity that are still in use today, securing his place in medical history. As Hutchinson envisioned, spirometry would become crucial to our growing knowledge of respiratory pathophysiology, from Tiffeneau and Pinelli's work on forced expiratory volumes, to Fry and Hyatt's description of the flow-volume curve. In the 20th century, standardization of spirometry further broadened its reach and prognostic potential. Today, spirometry is recognized as essential to respiratory disease diagnosis, management and research. However, controversy exists in some of its applications, uptake in primary care remains sub-optimal and there are concerns related to the way in which race is factored into interpretation. Moving forward, these failings must be addressed, and innovations like Internet-enabled portable spirometers may present novel opportunities. We must also consider the physiologic and practical limitations inherent to spirometry and further investigate complementary technologies such as respiratory oscillometry and other emerging technologies that assess lung function. Through an exploration of the storied history of spirometry, we can better contextualize its current landscape and appreciate the trends that have repeatedly arisen over time. This may help to improve our current use of spirometry and may allow us to anticipate the obstacles confronting emerging pulmonary function technologies.

Home monitoring of physiology and symptoms to detect interstitial lung disease exacerbations and progression: a systematic review

Background

Acute exacerbations (AEs) and disease progression in interstitial lung disease (ILD) pose important challenges to clinicians and patients. AEs of ILD are variable in presentation but may result in rapid progression of ILD, respiratory failure and death. However, in many cases AEs of ILD may go unrecognised so that their true impact and response to therapy is unknown. The potential for home monitoring to facilitate early, and accurate, identification of AE and/or ILD progression has gained interest. With increasing evidence available, there is a need for a systematic review on home monitoring of patients with ILD to summarise the existing data. The aim of this review was to systematically evaluate the evidence for use of home monitoring for early detection of exacerbations and/or progression of ILD.

Method

We searched Ovid-EMBASE, MEDLINE and CINAHL using Medical Subject Headings (MeSH) terms in accordance with the PRISMA guidelines (PROSPERO registration number CRD42020215166).

Results

13 studies involving 968 patients have demonstrated that home monitoring is feasible and of potential benefit in patients with ILD. Nine studies reported that mean adherence to home monitoring was >75%, and where spirometry was performed there was a significant correlation (r=0.72–0.98, p<0.001) between home and hospital-based readings. Two studies suggested that home monitoring of forced vital capacity might facilitate detection of progression in idiopathic pulmonary fibrosis.

Conclusion

Despite the fact that individual studies in this systematic review provide supportive evidence suggesting the feasibility and utility of home monitoring in ILD, further studies are necessary to quantify the potential of home monitoring to detect disease progression and/or AEs.

First systematic review that provides supportive evidence for the feasibility and utility of home monitoring in ILD; further studies are necessary to evaluate approaches to detect exacerbation and/or progressionhttps://bit.ly/2Y8OCJL

Radiological pleuroparenchymal fibroelastosis-like lesion in idiopathic interstitial pneumonias

Background

Pleuroparenchymal fibroelastosis (PPFE) is characterised by predominant upper lobe pleural and subpleural lung parenchymal fibrosis. Radiological PPFE-like lesion has been associated with various types of interstitial lung diseases. However, the prevalence and clinical significance of radiological PPFE-like lesion in patients with idiopathic interstitial pneumonias (IIPs) are not fully understood. We aimed to determine the prevalence and clinical impact on survival of radiological PPFE-like lesion in patients with IIPs.

Methods

A post-hoc analysis was conducted using data from the Japanese nationwide cloud-based database of patients with IIPs. All the patients in the database were diagnosed as having IIPs by multidisciplinary discussion. Patients diagnosed with idiopathic PPFE were excluded. Clinical data and chest computed tomography (CT) image of 419 patients with IIPs were analysed. The presence of radiological PPFE-like lesion was independently evaluated by two chest radiologists blind to the clinical data.

Results

Of the 419 patients with IIPs, radiological PPFE-like lesions were detected in 101 (24.1%) patients, mainly in idiopathic pulmonary fibrosis (IPF) and unclassifiable IIPs, but less in idiopathic nonspecific interstitial pneumonia. Prognostic analyses revealed that radiological PPFE-like lesion was significantly associated with poor outcome in patients with IIPs, which was independent of age, IPF diagnosis and %FVC. In survival analyses, the patients with radiological PPFE-like lesions had poor survival compared with those without (log-rank, p < 0.0001). Subgroup analyses demonstrated that radiological PPFE-like lesion was significantly associated with poor survival both in patients with IPF and those with unclassifiable IIPs.

Conclusion

Radiological PPFE-like lesion is a condition that could exist in IIPs, mainly in IPF and unclassifiable IIPs. Importantly, the radiological PPFE-like lesion is a non-invasive marker to predict poor outcome in patients with IIPs, which should be carefully considered in clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01892-9.

Follow-Ups on Persistent Symptoms and Pulmonary Function Among Post-Acute COVID-19 Patients: A Systematic Review and Meta-Analysis

Objective: As the number of recovering COVID-19 patients increases worldwide, the persistence of symptoms and signs through the post-acute phase indicates an urgent need for prolonged follow-up care. To explore existing data about post-acute COVID-19 syndrome, this meta-analysis assesses the prevalence of persistent manifestations in multiple systems and abnormalities in lung function, as well as their related risks in patients with various severities.

Methods: Articles about discharged COVID-19 patients (published from January 1, 2020 to February 23, 2021) were obtained by searching four databases. Cohort studies with follow-up periods >1 month post-discharge or >2 months post-admission were included.

Results: A total of 4,478 COVID-19 patients from 16 cohort studies were included in this meta-analysis. Fatigue or weakness (47%) were the most prevalent physical effects of post-acute COVID-19 syndrome, while psychosocial (28%) symptoms were the most common manifestations among several systems. Abnormalities in lung function of recovering patients, i.e., DLCO <80% (47%, 95% CI: 32–61%) persisted for long periods. Severe patients were more likely to present joint pain (OR 1.84, 95% CI: 1.11–3.04) and decreased lung functions compared with non-severe patients, with pooled ORs for abnormal TLC, FEV1, FVC, and DLCO of 3.05 (95% CI: 1.88–4.96), 2.72 (95% CI: 1.31–5.63), 2.52 (95% CI: 1.28–4.98), and 1.82 (95% CI: 1.32–2.50), respectively.

Conclusions: Our research indicates that patients recovering from COVID-19 manifest long-term, multi-system symptoms, and the adverse effects on psychosocial health and lung functions were the most extensive and persistent. These findings together may facilitate much needed in-depth study of clinical treatments for long-term, post-acute phase symptoms that affect a great number of recovering COVID-19 patients.

Early diagnosis of fibrotic interstitial lung disease: challenges and opportunities

Many patients with interstitial lung disease (ILD) develop pulmonary fibrosis, which can lead to reduced quality of life and early mortality. Patients with fibrotic ILD often have considerable diagnostic delay, and are exposed to unnecessary and costly diagnostic procedures, and ineffective and potentially harmful treatments. Non-specific and insidious presenting symptoms, along with scarce knowledge of fibrotic ILD among primary care physicians and non-ILD experts, are some of the main causes of diagnostic delay. Here, we outline and discuss the challenges facing both patients and physicians in making an early diagnosis of fibrotic ILD, and explore strategies to facilitate early identification of patients with fibrotic ILD, both in the general population and among individuals at highest risk of developing the disease. Finally, we discuss controversies and key uncertainties in screening programmes for fibrotic ILD. Timely identification and accurate diagnosis of patients with fibrotic ILD poses several substantial clinical challenges, but could potentially improve outcomes through early initiation of appropriate management.

Quantifying normal lung in pulmonary fibrosis: CT analysis and correlation with %DLCO

BACKGROUND

Chest CT scans are routinely obtained to monitor disease progression in pulmonary fibrosis. However, radiologists do not employ a standardized system for quantitative description of the severity of the disease. Development and validation of a grading system offers potential for enhancing the information that radiologists provide clinicians.

STUDY DESIGN AND METHODS

Our retrospective review analyzed 100 sequential patients with usual interstitial pneumonitis (UIP) on HRCT scans from 2018 and 2019. A radiologic scoring system evaluated the percent of normal lung on the basis of a 0-5 point scale per lobe (findings for the right middle lobe were included in the right upper lobe score), yielding an overall additive numerical score on a scale of 20 (completely normal lung) to 0 (no normal lung). Two radiologists quantified the percentage of normal lung by consensus agreement. Percent DLCO as well as demographic data were obtained from the medical record. Statistical analysis was performed using Spearman correlation to assess correlation between grade and percent DLCO.

RESULTS

96 patients met the inclusion criteria; average age was 71, 68% were male. Score on CT scan ranged from 18 to 4; average 10.9, SD 3.58. The single-breath diffusing capacity (percent DLCO) ranged from 88% to 17%; mean 44.5%, SD 14.3%. Spearman's correlation for CT score and percent DLCO was 0.622, P < 0.001.

CONCLUSION

This scoring system quantifying the amount of normal lung on chest CT of patients with UIP correlated significantly with percent DLCO (P < 0.001) and appears to offer a promising quantitative measure to assess severity of disease.

COVID-19 and pulmonary fibrosis: A potential role for lung epithelial cells and fibroblasts

The COVID-19 pandemic rapidly spread around the world following the first reports in Wuhan City, China in late 2019. The disease, caused by the novel SARS-CoV-2 virus, is primarily a respiratory condition that can affect numerous other bodily systems including the cardiovascular and gastrointestinal systems. The disease ranges in severity from asymptomatic through to severe acute respiratory distress requiring intensive care treatment and mechanical ventilation, which can lead to respiratory failure and death. It has rapidly become evident that COVID-19 patients can develop features of interstitial pulmonary fibrosis, which in many cases persist for as long as we have thus far been able to follow the patients. Many questions remain about how such fibrotic changes occur within the lung of COVID-19 patients, whether the changes will persist long term or are capable of resolving, and whether post-COVID-19 pulmonary fibrosis has the potential to become progressive, as in other fibrotic lung diseases. This review brings together our existing knowledge on both COVID-19 and pulmonary fibrosis, with a particular focus on lung epithelial cells and fibroblasts, in order to discuss common pathways and processes that may be implicated as we try to answer these important questions in the months and years to come.

Feasibility of cardiopulmonary exercise testing in interstitial lung disease: the PETFIB study

Introduction

Cardiopulmonary exercise testing (CPET) provides a series of biomarkers, such as peak oxygen uptake, which could assess the development of disease status in interstitial lung disease (ILD). However, despite use in research and clinical settings, the feasibility of CPET in this patient group has yet to be established.

Methods

Twenty-six patients with ILD (19 male) were recruited to this study. Following screening for contraindications to maximal exercise, participants underwent an incremental CPET to volitional exhaustion. Feasibility of CPET was assessed by the implementation, practicality, acceptability and demand, thus providing clinical-driven and patient-driven information on this testing procedure.

Results

Of the 26 recruited participants, 24 successfully completed at least one CPET, with 67/78 prospective tests being completed. Contraindications included hypertension, low resting oxygen saturation and recent pulmonary embolism. Of the CPETs undertaken, 63% successfully reached volitional exhaustion, with 31% being terminated early by clinicians due to excessive desaturation. Quantitative and qualitative feedback from participants revealed a positive experience of CPET and desire for it to be included as a future monitoring tool.

Conclusion

CPET is feasible in patients with ILD. Identification of common clinical contraindications, and understanding of patient perspectives will allow for effective design of future studies utilising CPET as a monitoring procedure.

Natural Course of the Diffusing Capacity of the Lungs for Carbon Monoxide in COPD: Importance of Sex

BACKGROUND

The value of the single-breath diffusing capacity of the lungs for carbon monoxide (Dlco) relates to outcomes for patients with COPD. However, little is known about the natural course of Dlco over time, intersubject variability, and factors that may influence Dlco progression.

RESEARCH QUESTION

What is the natural course of Dlco in patients with COPD over time, and which other factors, including sex differences, could influence this progression?

STUDY DESIGN AND METHODS

We phenotyped 602 smokers (women, 33%), of whom 506 (84%) had COPD and 96 (16%) had no airflow limitation. Lung function, including Dlco, was monitored annually over 5 years. A random coefficients model was used to evaluate Dlco changes over time.

RESULTS

The mean (± SE) yearly decline in Dlco % in patients with COPD was 1.34% ± 0.015%/y. This was steeper compared with non-COPD control subjects (0.04% ± 0.032%/y; P = .004). Sixteen percent of the patients with COPD, vs 4.3% of the control subjects, had a statistically significant Dlco % slope annual decline (4.14%/y). At baseline, women with COPD had lower Dlco values (11.37% ± 2.27%; P < .001) in spite of a higher FEV₁ % than men. Compared with men, women with COPD had a steeper Dlco annual decline of 0.89% ± 0.42%/y (P = .039).

INTERPRETATION

Patients with COPD have an accelerated decline in Dlco compared with smokers without the disease. However, the decline is slow, and a testing interval of 3 to 4 years may be clinically informative. The lower and more rapid decline in Dlco values in women, compared with men, suggests a differential impact of sex in gas exchange function.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01122758; URL: www.clinicaltrials.gov.

Respiratory and Psychophysical Sequelae Among Patients With COVID-19 Four Months After Hospital Discharge

IMPORTANCE

Although plenty of data exist regarding clinical manifestations, course, case fatality rate, and risk factors associated with mortality in severe coronavirus disease 2019 (COVID-19), long-term respiratory and functional sequelae in survivors of COVID-19 are unknown.

OBJECTIVE

To evaluate the prevalence of lung function anomalies, exercise function impairment, and psychological sequelae among patients hospitalized for COVID-19, 4 months after discharge.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study at an academic hospital in Northern Italy was conducted among a consecutive series of patients aged 18 years and older (or their caregivers) who had received a confirmed diagnosis of severe acute respiratory coronavirus 2 (SARS-CoV-2) infection severe enough to require hospital admission from March 1 to June 29, 2020. SARS-CoV-2 infection was confirmed via reverse transcription-polymerase chain reaction testing, bronchial swab, serological testing, or suggestive computed tomography results.

EXPOSURE

Severe COVID-19 requiring hospitalization.

MAIN OUTCOMES AND MEASURES

The primary outcome of the study was to describe the proportion of patients with a diffusing lung capacity for carbon monoxide (Dlco) less than 80% of expected value. Secondary outcomes included proportion of patients with severe lung function impairment (defined as Dlco <60% expected value); proportion of patients with posttraumatic stress symptoms (measured using the Impact of Event Scale-Revised total score); proportion of patients with functional impairment (assessed using the Short Physical Performance Battery [SPPB] score and 2-minute walking test); and identification of factors associated with Dlco reduction and psychological or functional sequelae.

RESULTS

Among 767 patients hospitalized for severe COVID-19, 494 (64.4%) refused to participate, and 35 (4.6%) died during follow-up. A total of 238 patients (31.0%) (median [interquartile range] age, 61 [50-71] years; 142 [59.7%] men; median [interquartile range] comorbidities, 2 [1-3]) consented to participate to the study. Of these, 219 patients were able to complete both pulmonary function tests and Dlco measurement. Dlco was reduced to less than 80% of the estimated value in 113 patients (51.6%) and less than 60% in 34 patients (15.5%). The SPPB score was suggested limited mobility (score <11) in 53 patients (22.3%). Patients with SPPB scores within reference range underwent a 2-minute walk test, which was outside reference ranges of expected performance for age and sex in 75 patients (40.5%); thus, a total of 128 patients (53.8%) had functional impairment. Posttraumatic stress symptoms were reported in a total of 41 patients (17.2%).

CONCLUSIONS AND RELEVANCE

These findings suggest that at 4 months after discharge, respiratory, physical, and psychological sequelae were common among patients who had been hospitalized for COVID-19.

A new noninvasive method for measurement of dynamic lung compliance from fluctuations on photoplethysmography in respiration

Lung compliance is important in interstitial lung disease (ILD). However, the measurement requires placement of an esophageal pressure probe and is therefore not done in routine clinic practice. This study was performed to develop and verify a new noninvasive method for estimation of dynamic lung compliance (Cdyn) with a photoplethysmograph (PPG) of pulse wave represented as the changes of absorbance of green LED for hemoglobin and to examine its usefulness. A system for measuring Cdyn in combination with changes in estimated pleural pressure (Ppl) from the fluctuations on PPG with respiration and lung volume measured simultaneously by spirometry was developed and verified to show correspondence with the estimated Ppl and the esophageal pressure (Pes), estimated Cdyn, and Cdyn measured with an esophageal balloon. Furthermore, the estimated percentage of predicted Cdyn (%Cdyn) was compared among healthy subjects (HS) (n = 33) and patients with chronic obstructive pulmonary disease (COPD) (n = 31) and ILD (n = 30). Both estimated Ppl and Cdyn were significantly correlated with Pes (r = 0.89) and measured Cdyn (r = 0.63), respectively. The estimated %Cdyn in ILD showed significantly lower values than those in HS and COPD. The estimated %Cdyn was significantly related to percentage of predicted vital capacity (VC) (r = 0.57, P < 0.01) and percentage of predicted diffusion capacity of carbon monoxide (Dl_CO) (r = 0.50, P < 0.01) in patients with ILD. These findings suggested that the newly developed noninvasive and convenient method for Cdyn estimation using a combination of PPG and spirometry may be useful for the assessment of lung fibrosis in ILD.NEW & NOTEWORTHY Our newly developed method for measuring dynamic lung compliance (Cdyn) in combination with changes in estimated intrathoracic pressure from fluctuations on photoplethysmography with respiration and lung volume measured simultaneously by spirometry showed good linear regression between the estimated Cdyn and the Cdyn measured with an esophageal balloon, and the estimated percentage of predicted Cdyn (%Cdyn) showed significantly lower values in patients with interstitial lung disease (ILD) than in healthy subjects and chronic obstructive pulmonary disease (COPD) patients and significant correlations with vital capacity and lung diffusion capacity.

Addressing Reduced Laboratory-Based Pulmonary Function Testing During a Pandemic

To reduce the spread of the severe acute respiratory syndrome coronavirus 2, many pulmonary function testing (PFT) laboratories have been closed or have significantly reduced their testing capacity. Because these mitigation strategies may be necessary for the next 6 to 18 months to prevent recurrent peaks in disease prevalence, fewer objective measurements of lung function will alter the diagnosis and care of patients with chronic respiratory diseases. PFT, which includes spirometry, lung volume, and diffusion capacity measurement, is essential to the diagnosis and management of patients with asthma, COPD, and other chronic lung conditions. Both traditional and innovative alternatives to conventional testing must now be explored. These may include peak expiratory flow devices, electronic portable spirometers, portable exhaled nitric oxide measurement, airwave oscillometry devices, and novel digital health tools such as smartphone microphone spirometers and mobile health technologies along with integration of machine learning approaches. The adoption of some novel approaches may not merely replace but could improve existing management strategies and alter common diagnostic paradigms. With these options comes important technical, privacy, ethical, financial, and medicolegal barriers that must be addressed. However, the coronavirus disease 19 pandemic also presents a unique opportunity to augment conventional testing by including innovative and emerging approaches to measuring lung function remotely in patients with respiratory disease. The benefits of such an approach have the potential to enhance respiratory care and empower patient self-management well beyond the current global pandemic.

Delayed contrast dynamics as marker of regional impairment in pulmonary fibrosis using 5D MRI - a pilot study

OBJECTIVE

To analyse delayed contrast dynamics of fibrotic lesions in interstitial lung disease (ILD) using five dimensional (5D) MRI and to correlate contrast dynamics with disease severity.

METHODS

20 patients (mean age: 71 years; M:F, 13:7), with chronic fibrosing ILD: n = 12 idiopathic pulmonary fibrosis (IPF) and n = 8 non-IPF, underwent thin-section multislice CT as part of the standard diagnostic workup and additionally MRI of the lung. 2 min after contrast injection, a radial gradient echo sequence with golden-angle spacing was acquired during 5 min of free-breathing, followed by 5D image reconstruction. Disease was categorized as severe or non-severe according to CT morphological regional severity. For each patient, 10 lesions were analysed.

RESULTS

IPF lesions showed later peak enhancement compared to non-IPF (severe: p = 0.01, non-severe: p = 0.003). Severe lesions showed later peak enhancement compared to non-severe lesions, in non-IPF (p = 0.04), but not in IPF (p = 0.35). There was a tendency towards higher accumulation and washout rates in IPF compared to non-IPF in non-severe disease. Severe lesions had lower washout rate than non-severe ones in both IPF (p = 0.003) and non-IPF (p = 0.005). Continuous contrast agent accumulation, without washout, was found only in IPF lesions.

CONCLUSIONS

Contrast agent dynamics are influenced by type and severity of pulmonary fibrosis, which might enable a more thorough characterisation of disease burden. The regional impairment is of particular interest in the context of antifibrotic treatments and was characterised using a non-invasive, non-irradiating, free-breathing method.

ADVANCES IN KNOWLEDGE

Delayed contrast enhancement patterns allow the assessment of regional lung impairment which could represent different disease stages or phenotypes in ILD.

Smoking-associated interstitial lung disease: update and review

INTRODUCTION

Smoking-associated interstitial lung disease manifests as several heterogeneous disorders involving the airways, pleura, and lung parenchyma with various radiological patterns. The clinical history, radiologic, and pathologic findings are important to distinguish these more uncommon diseases. A multidisciplinary approach is recommended for diagnosis and to manage these conditions appropriately.

AREAS COVERED

This review provides an overview of the epidemiology, risk factors, pathogenesis, clinical features, diagnosis, and treatment of acute eosinophilic pneumonia, e-cigarettes, or vaping associated lung injury, respiratory bronchiolitis interstitial lung disease, desquamative interstitial pneumonitis, pulmonary Langerhans cell histiocytosis, idiopathic pulmonary fibrosis, and combined pulmonary fibrosis emphysema.

EXPERT OPINION

Cigarette smoking is associated with a variety of pathologic conditions that affect the airways and lungs. E-cigarette use and vaping present new challenges to the clinician. Consensus between the clinical, radiographic, and pathologic findings is important in identifying and differentiating between the various entities to properly diagnose smoking-related interstitial lung diseases discussed in this review.

Derivation and Validation of a Diagnostic Prediction Tool for Interstitial Lung Disease

BACKGROUND

Interstitial lung disease (ILD) results in high morbidity and health-care utilization. Diagnostic delays remain common and often occur in nonpulmonology settings. Screening for ILD in these settings has the potential to reduce diagnostic delays and improve patient outcomes.

RESEARCH QUESTION

This study sought to determine whether a pulmonary function test (PFT)-derived diagnostic prediction tool (ILD-Screen) could accurately identify incident ILD cases in patients undergoing PFT in nonpulmonology settings.

STUDY DESIGN AND METHODS

Clinical and physiologic PFT variables predictive of ILD were identified by using iterative multivariable logistic regression models. ILD status was determined by using a multi-reader approach. An ILD-Screen score was generated by using final regression model coefficients, with a score ≥ 8 considered positive. ILD-Screen test performance was validated in an independent external cohort and applied prospectively to PFTs over 1 year to identify incident ILD cases at our institution.

RESULTS

Variables comprising the ILD-Screen were age, height, total lung capacity, FEV₁, diffusion capacity, and PFT indication. The ILD-Screen showed consistent test performance across cohorts, with a sensitivity of 0.79 and a specificity of 0.83 when applied prospectively. A positive ILD-Screen strongly predicted ILD (OR, 18.6; 95% CI, 9.4-36.9) and outperformed common ILD clinical features, including cough, dyspnea, lung crackles, and restrictive lung physiology. Prospective ILD-Screen application resulted in a higher proportion of patients undergoing chest CT imaging compared with a historical control cohort (74% vs 56%, respectively; P = .003), with a significantly shorter median time to chest CT imaging (5.6 vs 21.1 months; P < .001).

INTERPRETATION

The ILD-Screen showed good test performance in predicting ILD across diverse geographic settings and when applied prospectively. Systematic ILD-Screen application has the potential to reduce diagnostic delays and facilitate earlier intervention in patients with ILD.

Predictive value of pulmonary function testing in the evaluation of pulmonary hypertension in sarcoidosis

Background: In sarcoidosis patients, pulmonary hypertension (PH) is associated with significant morbidity and mortality. Early identification of sarcoidosis-associated pulmonary hypertension (SAPH) has substantial clinical implications. While a number of pulmonary function testing (PFT) variables have been associated with SAPH, the optimal use of PFT’s in screening for SAPH is unknown. Objectives: To examine the predictive value of PFT’s for echocardiographic PH in a cohort of sarcoidosis patients. Methods: We conducted a retrospective cohort study of patients with sarcoidosis from a single center over a period of five years. All consecutive adult patients with a diagnosis of biopsy-proven sarcoidosis (determined by review of the medical chart) who underwent PFT and echocardiographic testing were included. Echocardiographic risk of PH (either intermediate or high) was determined by the presence of echocardiographic PH signs and tricuspid regurgitant jet velocity. Data analysis was performed using multivariate logistic regression analysis with least absolute shrinkage and selection operator. Results: Of the 156 patients included in the study, 42 (27%) met the criteria for echocardiographic PH. Roughly equal proportions met the criteria for intermediate risk (45%) as did for high risk of PH (55%). The percent predicted of diffusion capacity for carbon monoxide (%DLCO) and forced vital capacity (%FVC) were predictive of echocardiographic PH. No other PFT variables outperformed these two markers, and the incorporation of additional PFT variables failed to significantly enhance the model. Conclusions: The %FVC and %DLCO emerged as being predictive of echocardiographic PH in this cohort of biopsy-proven sarcoidosis patients. Potentially reflecting the multifactorial pathogenesis of PH in sarcoidosis, incorporation of other PFT variables failed to enhance screening for PH in this population. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 308-316)

Exercise Pathophysiology in Interstitial Lung Disease

Interstitial lung disease (ILD) is a heterogeneous group of disorders that primarily affect the lung parenchyma. Patients with ILD have reduced lung volumes, impaired pulmonary gas exchange, and decreased cardiovascular function. These pathologic features of ILD become exacerbated during physical exertion, leading to exercise intolerance and abnormally high levels of exertional dyspnea. In this review, the authors summarize the primary pathophysiologic features of patients with ILD and their effect on the integrative response to exercise.

Assessment of Interstitial Lung Disease Using Lung Ultrasound Surface Wave Elastography: A Novel Technique With Clinicoradiologic Correlates

PURPOSE

Optimal strategies to detect early interstitial lung disease (ILD) are unknown. ILD is frequently subpleural in distribution and affects lung elasticity. Lung ultrasound surface wave elastography (LUSWE) is a noninvasive method of quantifying superficial lung tissue elastic properties. In LUWSE a handheld device applied at the intercostal space vibrates the chest at a set frequency, and the lung surface wave velocity is measured by an ultrasound probe 5 mm away in the same intercostal space. We explored LUWSE's ability to detect ILD and correlated LUSWE velocity with physiological, quantitative, and visual radiologic features of subjects with known ILD and of healthy controls.

MATERIALS AND METHODS

Seventy-seven subjects with ILD, mostly caused by connective tissue disease, and 19 healthy controls were recruited. LUSWE was performed on all subjects in 3 intercostal lung regions bilaterally. Comparison of LUSWE velocities pulmonary function testing, visual assessment, and quantitative analysis of recent computed tomographic imaging with Computer-Aided Lung Informatics for Pathology Evaluation and Rating (CALIPER) software.

RESULTS

Sonographic velocities were higher in all lung regions for cases, with the greatest difference in the lateral lower lung. Median velocity in m/s was 5.84 versus 4.11 and 5.96 versus 4.27 (P<0.00001) for cases versus controls, left and right lateral lower lung zones, respectively. LUSWE velocity correlated negatively with vital capacity and positively with radiologist and CALIPER-detected interstitial abnormalities.

CONCLUSIONS

LUSWE is a safe and noninvasive technique that shows high sensitivity to detect ILD and correlated with clinical, physiological, radiologic, and quantitative assessments of ILD. Prospective study in detecting ILD is indicated.

Surfactant protein A as a biomarker of outcomes of anti-fibrotic drug therapy in patients with idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is a progressive and fibrosing lung disease with poor prognosis. Pirfenidone and nintedanib are anti-fibrotic drugs used for patients with IPF. These drugs reduce the rate of decline in forced vital capacity (FVC). Serum surfactant protein (SP)-A, SP-D, and Krebs von den Lungen-6 (KL-6) are monitoring and prognostic biomarkers in patients with IPF; however, their relationship with the therapeutic outcomes of anti-fibrotic drugs has not been investigated. We aim to clarify whether serum SP-A, SP-D, and KL-6 reflect therapeutic outcomes of pirfenidone and nintedanib administration in patients with IPF.

Methods

We retrospectively investigated patients with IPF who were initiated on pirfenidone or nintedanib administration between January 2014 and June 2018 at our hospital. Changes in clinical parameters and serum SP-A, SP-D, and KL-6 levels were evaluated. Patients with ≥10% decline in FVC or ≥ 15% decline in diffusing capacity of the lung for carbon monoxide (DLco) from baseline to 6 months were classified as progression group, while the other patients were classified as stable group.

Results

Forty-nine patients were included (pirfenidone, 23; nintedanib, 26). Stable group comprised 32 patients, while progression group comprised 17 patients. In the stable group, changes in SP-A and KL-6 from baseline to 3 and 6 months significantly decreased compared with the progression group (SP-A: 3 months − 6.0% vs 16.7%, 6 months − 10.2% vs 20.2%, KL-6: 3 months − 9.2% vs 6.7%, 6 months − 15.0% vs 12.1%, p < 0.05). Changes in SP-A and SP-D levels showed significant negative correlations with the change in %FVC (r = − 0.46 and r = − 0.39, p < 0.01, respectively) and %DLco (r = − 0.67 and r = − 0.54, p < 0.01, respectively). Similar results were also seen in subgroup analysis for both pirfenidone and nintedanib groups. On logistic regression analysis, decrease in SP-A from baseline to 3 months and 6 months was found to predict the outcomes at 6 months (odds ratios: 0.89 and 0.88, respectively).

Conclusions

Changes in serum SP-A reflected the outcomes of anti-fibrotic drug therapy. Serum SP-A has a potential as a biomarker of therapeutic outcomes of anti-fibrotic drugs.

Respiratory reactance in forced oscillation technique reflects disease stage and predicts lung physiology deterioration in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease. Although pulmonary function test (PFT) is useful for evaluating the progression of IPF, obtaining adequate results in advanced cases can be challenging. Conversely, the forced oscillation technique (FOT) can be noninvasively performed, even in patients with severely deteriorated lung function. In this study, the usefulness of FOT for the evaluation of IPF disease status was investigated.

METHODS

We analyzed the PFT and FOT data of 97 patients with IPF.

RESULTS

The respiratory reactance (Xrs) components of FOT, especially in the inspiratory phase, correlated with the PFT values. Patients with advanced disease had significantly lower reactance at 5 Hz (X5), higher resonant frequency (Fres) and low-frequency reactance area (ALX). The longitudinal deterioration of Xrs was also observed. Moreover, X5 in the inspiratory phase predicted subsequent lung capacity deterioration.

CONCLUSION

The Xrs components of FOT, especially in the inspiratory phase, reflected restrictive ventilatory impairment and disease severity in patients with IPF.

From organ to cell: Multi-level telomere length assessment in patients with idiopathic pulmonary fibrosis

Rationale

A subset of patients with idiopathic pulmonary fibrosis (IPF) contains short leukocyte telomeres or telomere related mutations. We previously showed that alveolar type 2 cells have short telomeres in fibrotic lesions. Our objectives were to better understand how telomere shortening associates with fibrosis in IPF lung and identify a subset of patients with telomere-related disease.

Methods

Average telomere length was determined in multiple organs, basal and apical lung, and diagnostic and end-stage fibrotic lung biopsies. Alveolar type 2 cells telomere length was determined in different areas of IPF lungs.

Results

In IPF but not in controls, telomere length in lung was shorter than in other organs, providing rationale to focus on telomere length in lung. Telomere length did not correlate with age and no difference in telomere length was found between diagnostic and explant lung or between basal and apical lung, irrespective of the presence of a radiological apicobasal gradient or fibrosis. Fifteen out of 28 IPF patients had average lung telomere length in the range of patients with a telomerase (TERT) mutation, and formed the IPF_short group. Only in this IPF_short and TERT group telomeres of alveolar type 2 cells were extremely short in fibrotic areas. Additionally, whole exome sequencing of IPF patients revealed two genetic variations in RTEL1 and one in PARN in the IPF_short group.

Conclusions

Average lung tissue telomere shortening does not associated with fibrotic patterns in IPF, however, approximately half of IPF patients show excessive lung telomere shortening that is associated with pulmonary fibrosis driven by telomere attrition.

Lower DLco% identifies exercise pulmonary hypertension in patients with parenchymal lung disease referred for dyspnea

Exercise pulmonary hypertension is an underappreciated form of physical limitation related to early pulmonary vascular disease. A low diffusing capacity of lungs for carbon monoxide (DLco) can be seen in patients with resting pulmonary hypertension as well as parenchymal lung disease. It remains unclear whether low DLco% identifies early pulmonary vascular disease. We hypothesize that a reduced DLco% differentiates the presence of exercise pulmonary hypertension in patients with parenchymal lung disease. Fifty-six patients referred for unexplained exertional dyspnea with pulmonary function tests within six months of hemodynamic testing underwent exercise right heart catheterization. Exclusion criteria included resting pulmonary arterial or venous hypertension. Receiver operator characteristic curve determined the optimal DLco% cutoffs based on the presence or absence of parenchymal lung disease. Twenty-one (37%) patients had parenchymal lung disease, most common manifesting as chronic obstructive lung disease or interstitial lung disease. In patients with parenchymal lung disease, a DLco of 46% demonstrated 100% sensitivity and 73% specificity for detecting exercise pulmonary hypertension. In patients without parenchymal lung disease, a DLco of 73% demonstrated 58% sensitivity and 94% specificity for detecting exercise pulmonary hypertension. In both cohorts, DLco% below the optimum cutoffs were associated with higher peak mean pulmonary arterial pressure and peak total pulmonary resistance consistent with the hemodynamic definition of exercise pulmonary hypertension. Patients with a DLco < 46% were more often treated with pulmonary vasodilators and had a trend to higher mortality and lung transplant. DLco% is a simple non-invasive screening test for the presence of exercise pulmonary hypertension in our mixed referral population with progressive exertional dyspnea. DLco < 46% with parenchymal lung disease and DLco < 73% without parenchymal lung disease may play a role in differentiating the presence of pulmonary vascular disease prior to invasive hemodynamic testing.

Diagnostic test interpretation and referral delay in patients with interstitial lung disease

Background

Diagnostic delays are common in patients with interstitial lung disease (ILD). A substantial percentage of patients experience a diagnostic delay in the primary care setting, but the factors underpinning this observation remain unclear. In this multi-center investigation, we assessed ILD reporting on diagnostic test interpretation and its association with subsequent pulmonology referral by a primary care physician (PCP).

Methods

A retrospective cohort analysis of patients referred to the ILD programs at UC-Davis and University of Chicago by a PCP within each institution was performed. Computed tomography (CT) of the chest and abdomen and pulmonary function test (PFT) were reviewed to identify the date ILD features were first present and determine the time from diagnostic test to pulmonology referral. The association between ILD reporting on diagnostic test interpretation and pulmonology referral was assessed, as was the association between years of diagnostic delay and changes in fibrotic features on longitudinal chest CT.

Results

One hundred and forty-six patients were included in the final analysis. Prior to pulmonology referral, 66% (n = 97) of patients underwent chest CT, 15% (n = 21) underwent PFT and 15% (n = 21) underwent abdominal CT. ILD features were reported on 84, 62 and 33% of chest CT, PFT and abdominal CT interpretations, respectively. ILD reporting was associated with shorter time to pulmonology referral when undergoing chest CT (1.3 vs 15.1 months, respectively; p = 0.02), but not PFT or abdominal CT. ILD reporting was associated with increased likelihood of pulmonology referral within 6 months of diagnostic test when undergoing chest CT (rate ratio 2.17, 95% CI 1.03–4.56; p = 0.04), but not PFT or abdominal CT. Each year of diagnostic delay was associated with a 1.8% increase in percent fibrosis on chest CT. Patients with documented dyspnea had shorter time to chest CT acquisition and pulmonology referral than patients with documented cough and lung crackles.

Conclusions

Determinants of ILD diagnostic delays in the primary care setting include underreporting of ILD features on diagnostic testing and prolonged time to pulmonology referral even when ILD is reported. Interventions to modulate these factors may reduce ILD diagnostic delays in the primary care setting.

Mycophenolate mofetil as an alternative treatment in sarcoidosis

INTRODUCTION

In sarcoidosis although no better drug therapy than corticosteroids (CS) has emerged, alternative immunosuppressive agents are used when indicated. Mycophenolate mofetil (MMF) presents rapid action, a considerable safety profile and absence of lung toxicity. Few data exist so far on its use in patients with sarcoidosis. This is a retrospective study on the effectiveness and safety of MMF in patients with sarcoidosis.

MATERIALS AND METHODS

All patients with biopsy proven sarcoidosis treated for at least 1 year with MMF from 2008 to 2017 in our department are evaluated.

RESULTS

Eight patients with both pulmonary and extrapulmonary disease are included in the analysis. During follow-up, symptoms and chest radiological findings improved in all. A statistically significant improvement of FEV₁ and FVC is reported (p = 0.010 and p = 0.021 respectively). Cardiac and renal disease resolved during treatment while dermal disease significantly improved. MMF permitted CS dose reduction from 15.0 (10.0, 35.0) to 2.5 (0.0, 5.0) mg prednisolone (or equivalent), p = 0.016. All patients but one, tolerated well MMF.

CONCLUSION

MMF as an alternative drug in systemic sarcoidosis, proved safe and effective, permitting the reduction of the dose of oral CS and leading to clinical, functional and radiological improvement.

Assessment of interstitial lung disease among black rheumatoid arthritis patients

BACKGROUND

Conflicting reports exist regarding the racial and the gender distribution of rheumatoid arthritis-related interstitial lung disease (RA-ILD). In a major population study of predominately Whites, RA-ILD was reported mainly among smoker middle-aged men. However, recent data suggest that the disease is that of elderly women. Our study aimed to assess the prevalence and identify the gender differences and clinical characteristics of RA-ILD in a predominantly Black population.

METHODS

Cross-sectional analysis of data obtained from the records of 1142 patients with RA diagnosis by ICD codes of which 503 cases met the inclusion criteria for the study. Eighty-six patients had chronic respiratory symptoms of cough and dyspnea and were further assessed by our multidisciplinary group of investigators. Thirty-two subjects with an established diagnosis of rheumatoid arthritis met the diagnostic criteria for interstitial lung disease.

RESULTS

Of the 32 patients with RA-ILD, mean age was 62.6 ± 2.2 (± SEM), 93.7% were females, and 89% Blacks with a BMI = 29.2 (Kg/m²). Usual interstitial pneumonia (UIP) was found in 24/32 (75%) of the cases. Seventy-two percent of the RA-ILD patient had seropositive RA. Smoking history was reported in 31.3% of the cohort, gastroesophageal reflux disease (GERD) in 32.3%, and cardiovascular disease (CVD) risk factors in 65.6%.

CONCLUSION

Our study indicates RA-ILD among Blacks is predominantly a disease of elderly females with higher rates of GERD and CVD risk factors. Further studies are needed to identify the pathogenetic differences accounting for the gender distribution of RA-ILD among Black and White populations.Key Points• First study to assess ILD among predominantly Black RA patients.• The prevalence of RA-associated ILD was 6.36%, affecting mostly women in their sixth decade with seropositive disease.• COPD was the most common airway disease among non-RA-ILD Black population.• GERD was found in approximately one-third of patients with RA-associated ILD versus one-fifth of those RA patients without any lung disease.

Prognosis of non-small-cell lung cancer in patients with idiopathic pulmonary fibrosis

The risk of lung cancer is higher in idiopathic pulmonary fibrosis (IPF) because both conditions share common risk factors. However, no standard treatment modality for LC in IPF exists due to rare incidence, poor prognosis, and acute exacerbation (AE) of IPF during treatment. We aimed to determine the efficacy of LC treatments and the prognosis in LC patients with IPF according to the LC stage and GAP (gender [G], age [A], and two physiology variables [P]) stage. From 2003 to 2016, 160 retrospectively enrolled patients were classified according to the LC clinical stage and GAP stage. The average (±standard deviation) patient age was 70.1 ± 8.2 years; the cohort predominantly comprised men (94.4%). In GAP stage I, surgery was significantly associated with better survival outcomes in LC. In contrast, no treatment modality yielded significant clinical improvement in GAP stage II/III. The incidences of AE in IPF and its mortality during treatment were 13.8% and 6.3%, respectively. AE occurred commonly in advanced GAP stage. Active treatment should be considered in GAP stage I. The performance status and LC stage should be considered when deciding about the necessity of surgery for patients in advanced GAP stage.

Quantitative Follow-Up Assessment of Patients with Interstitial Lung Disease by 3D-Curved High-Resolution CT Imaging Parallel to the Chest Wall

We evaluated the progression of interstitial lung disease (ILD) by three-dimensional curved high-resolution computed tomography (3D-cHRCT) at a constant depth from the chest wall and compare the results to pulmonary function test (PFT) results on a follow-up assessment. We reviewed the patients with ILD who underwent HRCT and concurrent PFTs at least twice from April 2008 to December 2014. Forty-five patients with ILD were enrolled. 3D-cHRCT images of the lung at various depths from the chest wall were reconstructed, and total area (TA), high-attenuation area (HAA) >-500 HU, and %HAA ([HAA/TA] × 100) were calculated. The TA, HAA, and %HAA ratios (follow-up to baseline) were assessed for use in the diagnosis of physiologically progressive ILD (defined as; forced vital capacity [FVC] ratio <0.9 or %diffusing capacity of the lung for carbon monoxide [%DLCO] ratio <0.85 [follow-up to baseline]). Of all ratios obtained from 3D-cHRCT images at 5-30mm depths, the %HAA ratio at 20-mm had the largest area under the receiver operating characteristic curve (0.815, 95 % confidence interval 0.677-0.953). By univariate logistic regression analysis, TA, HAA, and %HAA ratios at 20-mm showed significant correlations with physiologically progressive ILD. 3D-cHRCT imaging performed in parallel with the chest wall offers novel quantitative parameters that are useful for following ILD.

Management of Idiopathic Pulmonary Fibrosis

Objective: Provide information for pharmacists on idiopathic pulmonary fibrosis (IPF) and its treatment. Study Selection and Data Extraction: All articles with data from randomized controlled trials of nintedanib or pirfenidone were reviewed. Data Synthesis: IPF is a progressive and ultimately fatal interstitial lung disease characterized by decline in lung function and worsening dyspnea. It is uncommon and mainly occurs in individuals aged >60 years, particularly men with a history of smoking. Nintedanib and pirfenidone were approved in the United States for the treatment of IPF in 2014 and received conditional recommendations in the 2015 American Thoracic Society/European Respiratory Society/Japanese Respiratory Society/Latin American Thoracic Association treatment guidelines. These drugs slow the progression of IPF by reducing the rate of decline in lung function. Their adverse event profile is characterized mainly by gastrointestinal events, which can be managed through dose adjustment and symptom management. Management of IPF should also include smoking cessation, vaccinations, and supportive care such as patient education, pulmonary rehabilitation, and the use of supplemental oxygen as well as optimizing the management of comorbidities. Relevance to Patient Care and Clinical Practice: This review provides clinical pharmacists with information on the course of IPF, what can be expected of current treatments, and how to help patients manage their drug therapy. Conclusions: IPF is a progressive disease, but treatments are available that can slow the progression of the disease. Clinical pharmacists can play an important role in the care of patients with IPF through patient education, monitoring medication compliance and safety, ensuring drugs for comorbidities are optimized, and preventive strategies such as immunizations.

Ultrasound evaluation of diaphragmatic mobility in patients with idiopathic lung fibrosis: a pilot study

Background

Some previous works have tested LUS use in diagnosing and monitoring interstitial lung diseases. B-lines are main sonographic signs for interstitial diseases. Increasing evidences suggest that dyspnea and impaired exercise capacity in IPF patients can be related, at least in part, to respiratory muscle dysfunction, in particular to diaphragm functionality. Both B-mode and M-mode ultrasound techniques have been employed to assess diaphragm excursion (DE), which measures the distance that the diaphragm is able to move during the respiratory cycle.

Methods

The main objective of this case-control study was to evaluate if differences exist between diaphragmatic excursions in IPF patients and in a control group of healthy subjects. Secondary objectives were to evaluate possible correlations among respiratory excursions, anthropometric parameters and respiratory function parameters. All patients performed spirometry and body plethysmography (PC). Diaphragm was examined by ultrasound imaging in B-MODE, and respiratory excursions were evaluated in M-MODE. Examination consisted of 3 measurements of the inspiratory phase at rest and after deep inspiration.

Results

Twelve patients with IPF and 12 healthy subjects were enrolled. There were no significant differences between respiratory excursions in patients and controls during spontaneous breathing, while there was a statistically significant difference between the mean values of the deep respiratory excursion in the two groups (p value < 0.001). There was a positive correlation between respiratory excursion with normal breath and chest circumference in controls (p = 0.034; R = 0.614) and in patients (p = 0.032; R = 0.37), but this relationship was not found even in subjects in deep breathing. A positive correlation was found between FVC values and diaphragmatic motility both at rest and in deep breathing in fibrotic patients.

Conclusions

Diaphragmatic mobility is lower in IPF patients than in healthy controls, especially during deep inspiration. The correlation between reduced FVC and diaphragmatic excursion values in IPF patients can be of interest, since it could represent an index of functional respiratory function performed by a non-invasive, low-cost, simple and reliable imaging technique, such as LUS.

Interstitial Lung Disease and Pulmonary Fibrosis: A Practical Approach for General Medicine Physicians with Focus on the Medical History

Interstitial lung disease (ILD) and pulmonary fibrosis comprise a wide array of inflammatory and fibrotic lung diseases which are often confusing to general medicine and pulmonary physicians alike. In addition to the myriad of clinical and radiologic nomenclature used in ILD, histopathologic descriptors may be particularly confusing, and are often extrapolated to radiologic imaging patterns which may further add to the confusion. We propose that rather than focusing on precise histologic findings, focus should be on identifying an accurate etiology of ILD through a comprehensive and detailed medical history. Histopathologic patterns from lung biopsy should not be dismissed, but are often nonspecific, and overall treatment strategy and prognosis are likely to be determined more by the specific etiology of ILD rather than any particular histologic pattern. In this review, we outline a practical approach to common ILDs, highlight important aspects in obtaining an exposure history, clarify terminology and nomenclature, and discuss six common subgroups of ILD likely to be encountered by general medicine physicians in the inpatient or outpatient setting: Smoking-related, hypersensitivity pneumonitis, connective tissue disease-related, occupation-related, medication-induced, and idiopathic pulmonary fibrosis. Accurate diagnosis of these forms of ILD does require supplementing the medical history with results of the physical examination, autoimmune serologic testing, and chest radiographic imaging, but the importance of a comprehensive environmental, avocational, occupational, and medication-use history cannot be overstated and is likely the single most important factor responsible for achieving the best possible outcomes for patients.

Lung function outcomes in the INPULSIS® trials of nintedanib in idiopathic pulmonary fibrosis

BACKGROUND

In the INPULSIS^® trials, nintedanib reduced the annual rate of decline in forced vital capacity (FVC) versus placebo, consistent with slowing of disease progression. We characterised the effects of nintedanib on physiologic outcomes using pooled data from the INPULSIS^® trials.

METHODS

Post-hoc analyses included changes in FVC over time, cumulative distribution of patients by change in FVC % predicted, and annual rate of decline in FVC in subgroups by diffusing capacity of the lung for carbon monoxide (DLco) and composite physiologic index (CPI) at baseline. Changes from baseline in DLco and oxygen saturation by pulse oximetry (SpO₂) were pre-specified.

RESULTS

Nintedanib significantly reduced FVC decline versus placebo from week 12. A higher proportion of patients treated with nintedanib than placebo had an improvement or no decline in FVC % predicted, whereas a smaller proportion had absolute declines in FVC ≥5% or ≥10% predicted from baseline to week 52. The effect of nintedanib on FVC decline was similar in patients with baseline DLco >40% versus ≤40% predicted or CPI ≤45 versus >45. There were no significant differences between nintedanib and placebo in change from baseline in DLco % predicted, CPI, or SpO₂ at week 52. However, change (deterioration) in CPI was significantly lower with nintedanib versus placebo in patients with CPI > 45 at baseline (1.0 versus 2.9) and CPI >55 at baseline (-1.2 versus 3.3).

CONCLUSIONS

A range of physiologic outcome measures in the INPULSIS^® trials support the effect of nintedanib on reducing disease progression in patients with IPF.

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.

Matrix abnormalities in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating, progressive disease, marked by excessive scarring, which leads to increased tissue stiffness, loss in lung function and ultimately death. IPF is characterised by progressive fibroblast and myofibroblast proliferation, and extensive deposition of extracellular matrix (ECM). Myofibroblasts play a key role in ECM deposition. Transforming growth factor (TGF)-β1 is a major growth factor involved in myofibroblast differentiation, and the creation of a profibrotic microenvironment. There is a strong link between increased ECM stiffness and profibrotic changes in cell phenotype and differentiation. The activation of TGF-β1 in response to mechanical stress from a stiff ECM explains some of the influence of the tissue microenvironment on cell phenotype and function. Understanding the close relationship between cells and their surrounding microenvironment will ultimately facilitate better management strategies for IPF.