Diagnosis of Hypersensitivity Pneumonitis in Adults. An Official ATS/JRS/ALAT Clinical Practice Guideline

Estimated prevalence and incidence of hypersensitivity pneumonitis in Japan

BACKGROUND

The latest guidelines on hypersensitivity pneumonitis (HP) categorise the disease as either fibrotic or non-fibrotic because of the greater clinical utility of this stratification. However, the prevalence and incidence of fibrotic and non-fibrotic HP are unknown. This study assessed the exact prevalence and incidence of fibrotic and non-fibrotic HP in Japan in 2021.

METHODS

For adults, the study hospitals were selected by stratified random sampling according to numbers of beds. The sampling rate was set at about 20%. The questionnaire survey was submitted to the target hospitals. For pediatric cases, a survey was distributed to all members of the Japanese Society of Pediatric Pulmonology and Japanese Society of Pediatric Allergy and Clinical Immunology.

RESULTS

Regarding adult cases, in total, 575 facilities responded to the survey, resulting in a response rate of 36.4%. The estimated prevalence and incidence of fibrotic HP were 6.3 and 2.5 per 100,000 population, respectively, versus 3.6 and 2.0 per 100,000 population, respectively, for non-fibrotic HP. Both fibrotic and non-fibrotic HP were more prevalent in southern Japan (Kyushu) and less prevalent in northern Japan (Hokkaido). The incidence of non-fibrotic HP was significantly lower in December than in the other months (relative risk ratio = 0.36, p < 0.001). Three cases of fibrotic HP and five cases of non-fibrotic HP were identified in children.

CONCLUSIONS

This study determined the prevalence and incidence of fibrotic and non-fibrotic HP in Japan for the first time.

Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report

Bird fancier's lung (BFL) is a subtype of hypersensitivity pneumonitis (HP), an immune-mediated interstitial lung disease (ILD) resulting from the repeated inhalation of avian proteins found in bird droppings, feathers, and serum. Diagnosing BFL is challenging due to nonspecific symptoms that overlap with other ILDs like idiopathic pulmonary fibrosis and sarcoidosis. This complexity is heightened during pandemics such as coronavirus disease 2019 (COVID-19), where respiratory symptoms may be misattributed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, leading to diagnostic anchoring and delays in appropriate management. High-resolution computed tomography (HRCT) is pivotal in detecting subtle pulmonary changes, characteristic of HP, surpassing standard chest radiographs. We present the case of a 43-year-old male pigeon keeper with an eight-week history of progressive dyspnea on exertion and intermittent chest pain. Despite unremarkable chest X-rays, HRCT revealed bilateral diffuse centrilobular nodules, patchy ground-glass opacities, and a mosaic attenuation pattern without fibrosis, consistent with acute HP. A thorough occupational history uncovered significant avian antigen exposure, and a family history suggested genetic susceptibility. The patient was diagnosed with BFL and treated with a tapering regimen of oral corticosteroids, starting at 40 mg/day. He was advised to cease pigeon keeping and avoid future avian exposure. Significant symptomatic improvement occurred within three months. Follow-up imaging over one year confirmed stable lung parenchyma with no disease progression or recurrence. This case underscores the importance of incorporating detailed occupational histories and utilizing advanced imaging modalities like HRCT when standard imaging is inconclusive. Early identification and intervention are crucial to prevent progression to chronic HP and irreversible fibrosis. Management should focus on reducing inflammation with corticosteroids and implementing strict environmental controls to prevent re-exposure. Long-term follow-up is essential to monitor for recurrence and maintain remission. Clinicians should remain vigilant for alternative diagnoses during pandemics to avoid diagnostic anchoring. This case contributes to the evidence supporting HRCT's critical role in early HP detection and emphasizes heightened clinical awareness of occupational lung diseases. A multidisciplinary approach involving pulmonologists, radiologists, and occupational medicine specialists is key to optimizing outcomes in HP and other ILDs.

House dust protein level of pigeon drooping and feather in environmental bird exposure-related hypersensitivity pneumonitis "A pilot study"

BACKGROUND

Bird fancier's disease is a type of HP occurring due to exposure to bird's antigen. The diagnosis is quite difficult as it requires the identification of an inciting agent with findings of HRCT and lung biopsy. The exposure is usually done by history with antigen-specific IgG and/or specific inhalational challenge testing. The study aimed to investigate the role of pigeon allergens in house dust in bird exposure-related HP patients.

METHODS

This was a descriptive, mixed-method observational study. We retrospectively screened all the files of HP patients for exposure history and pigeon-specific IgG of one-year duration. Finally, Finally house dust from 18 cases with HP was collected for analysis of concentration of pigeon droppings and feather proteins.

RESULTS

The mean age was 47.8 ± 11.5 years with 78% being female. The median duration of symptoms was 1.75 years with a median exposure history to pigeons of 7 years. The level of specific IgG was raised in 11 (60%) patients with a mean level of 50.6 ± 39.5. The concentration of pigeon-drooping protein was present in all the dust samples with a mean of 17.6 ± 5.6 μg/mg. The highest concentration was 27 μg/mg and the lowest of 9 μg/mg. The concentration of pigeon father protein was present in nearly 50% of the dust sample with a mean of 5.6 ± 6.7 μg/mg and the highest concentration was 15.8 μg/mg.

CONCLUSION

The confirmation history of exposure in bird exposure-related HP is difficult because bird antigen exposure can be presents anywhere. The house dust bird protein concentration measurement is a simple, non-invasive, adjunct test for confirmation of bird exposure.

Effects of immunosuppressants in patients with mild fibrotic hypersensitivity pneumonitis

BACKGROUND

The efficacy of immunosuppressants in patients with fibrotic hypersensitivity pneumonitis (HP) is controversial. We hypothesized that pretreatment and posttreatment disease progression in immunosuppressant with prednisolone group and the immunosuppressant-naive prednisolone group would show a significant difference.

METHODS

This was a single-center, retrospective, observational study. Patients with histopathological examination between January 2005 and March 2021, a diagnosis of fibrotic HP at multidisciplinary discussion and a diagnosis of fibrotic HP according to international guidelines were investigated. Propensity score matching which had covariates: age, gender, and forced vital capacity, was performed, and disease progression between the two groups was compared.

RESULTS

Forty-two patients were included in this study. The mean change in forced vital capacity (FVC) in the 12 months prior to treatment was significantly decreased in the immunosuppressant with prednisolone group compared with the immunosuppressant-naive prednisolone (-8.2% and -2.7%, respectively, P = 0.033). During 12 months of treatment, the two groups did not differ significantly with regards to FVC change (-1.1% and 0.5%, respectively, P = 0.675). Between the two groups, the annual change in Krebs von den Lungen-6 before treatment and after treatment were not significantly different (P = 0.626 and 0.844, respectively). Transplant-free survival from the treatment in the two groups did not differ significantly (HR: 1.09, 95%CI (0.41-2.88), P = 0.873).

CONCLUSIONS

No significant differences were observed in FVC changes between the two groups following treatment, although the immunosuppressant with prednisolone group exhibited a greater decrease in FVC before treatment.

Hypersensitivity pneumonitis: A high index of clinical suspicion is key for early diagnosis and successful treatment

See related article

Use of mycophenolate mofetil for the treatment of fibrotic hypersensitivity pneumonitis

INTRODUCTION

The optimal treatment of fibrosing hypersensitivity pneumonitis (fHP) is not well understood. The aim of the study was to obtain information about the usefulness of mycophenolate mofetil (MMF) in its treatment.

MATERIAL AND METHODS

Quasi-experimental analysis of patients diagnosed with fHP and treated with MMF for one year, in a single centre. From the start of treatment, data collection was prospective.

RESULTS

73 were included and 58 completed the study. FVC% and DLCO% decreased until starting MMF (year -1 to year 0). After completion of treatment (year 1), FVC% stabilised (p=0.336) and DLCO% improved significantly (p=0.004) compared to year 0. Dyspnoea, number of patients without corticosteroids and mean corticosteroid dose also improved significantly (p<0.001 in all cases). Being male and having a history of tuberculosis were predictors of poor drug response [AUC = 0.89 (95% CI: 0.80-0.98)]. 45 adverse effects were observed in 34 patients (46.6%). In 4 cases (5.5%), the adverse effect was severe and required discontinuation of treatment.

CONCLUSIONS

In patients with fHP, MMF improves lung function and dyspnoea and reduces both the number of patients requiring oral corticosteroids and their mean dose in those who completed 1 year of treatment. The model constructed predicts which patients will respond poorly to treatment, with good discriminative ability and only a small percentage of patients will not tolerate treatment. Further prospective, randomised clinical trials are needed to define the role of this treatment in fHP.

Pressed for understanding: Interstitial lung disease in dry-cleaning workers

Interstitial lung disease (ILD) represents a heterogeneous group of disorders characterized by inflammation and fibrosis of the pulmonary interstitium. Risk factors for ILD include various environmental exposures and identifying specific exposures offers a point of intervention for preventing disease. Here, we present several cases of patients who worked in the dry-cleaning business and have ILD or abnormalities consistent with early ILD on chest CT imaging. While this report does not attempt to establish causality, we hypothesize that exposure to the industrial solvent tetrachloroethylene may serve as a contributing factor given its links to epithelial injury, inflammation, redox imbalance and apoptosis. We hope that this report serves to not only inform readers of this possible connection between dry cleaning and ILD but also lay the foundation for additional studies examining the effects of tetrachloroethylene on the lung.

Aspergillus IgG antibody testing in the diagnosis of hypersensitivity pneumonitis: A scoping review

BackgroundDiagnosis of hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis requires a combination of tests with antibody testing playing a supportive role to identify exposures.ObjectivesWe conducted a scoping review on Aspergillus antibody testing in Aspergillus-related HP to identify the utility and diagnostic cutoffs proposed in the literature. We compared these cutoffs with studies of chronic pulmonary aspergillosis (CPA) and manufacturers' cutoffs.Eligibility criteriaOnly studies addressing the diagnostic value of Aspergillus IgG or precipitins for HP were included. Separately papers defining cutoffs for CPA were tabulated.Sources of evidencePublished papers were identified in literature searches in Embase, Web of Science, and Medline.ResultsWe identified 414 papers, of which 12 were included, all published between 1965 and 2005. Occupational HP linked to Aspergillus spp. exposure included Farmer's Lung, Malt-Worker's Lung, Esparto Worker's Lung, and Woodworker's lung (Sawmill-workers). No studies directly addressed serological testing in Tobacco Worker's lung, Compost Lung, or poultry workers. Among Aspergillus species exposure, A. fumigatus was most commonly described; others included A. umbrosus (now A. glaucus), A. clavatus, and A. niger. Antibody tests included ELISA, BALISA, precipitin tests and ImmunoCAP, with a higher sensitivity of ELISA and ImmunoCAP tests compared to precipitin tests. Patients with HP linked to Aspergillus exposures, were positive in 156/290 (53.8%) compared to 96/615 (15.6%) in those with similar occupational exposures without HP. In malt workers with HP 35/53 (66%) had detectable A. clavatus IgG antibody compared to 0/53 A. fumigatus IgG, and 13/74 (18%) exposed but unaffected workers, but are not commercially available.ConclusionsImproved means of establishing or ruling out Aspergillus exposure are required, given the negative consequences for patients of continued Aspergillus inhalation. Modern studies with commercially available Aspergillus IgG antibody assays are required to define appropriate cutoffs for HP, given numerous studies published for chronic pulmonary aspergillosis.

Predictive factors of progression in mild fibrosing interstitial lung disease patients with gender-age-physiology score of 3 or less

BACKGROUND

The prognostic factors in mild fibrosing interstitial lung disease (FILD) have not been established.

METHODS

We retrospectively attempted to identify predictive factors of annual progression in mild FILD with gender-age-physiology (GAP) score of 3 or less using logistic regression analysis. Annual FILD progression was defined as meeting any two or more of the following conditions: 1, more than 10% decrease in forced vital capacity (FVC) or 15% decrease in diffusing capacity of the lungs for carbon monoxide (DLCO); 2, worsening of dyspnea; 3, worsening of fibrotic change on CT at 1 year after admission.

RESULTS

Univariate analysis showed that diagnosis of connective tissue disease-associated ILD, CT-definite usual interstitial pneumonia (UIP) pattern, composite physiologic index, FVC, DLCO, lowest SpO2 and decrease in SpO2, and walk distance in the 6-minutes walk test (6MWT), chronic pulmonary emphysema assessment test (CAT) score, and some variables in Short-Form 36 were significantly associated with incidence of annual progression. Multivariate analysis showed that independent predictive factors were diagnosis of idiopathic pulmonary fibrosis (IPF) and fibrotic hypersensitivity pneumonitis (HP), CT-definite UIP pattern, lowest SpO2 and decrease in SpO2 in the 6MWT, and CAT score. In logistic regression analysis among 63 patients with non-IPF-ILD, diagnosis with fibrotic HP, lowest SpO2 and decrease in SpO2 in the 6MWT, and CAT score were also independent risk factors for annual FILD progression.

CONCLUSIONS

Exercise-induced hypoxia, patient-reported outcome, radiological UIP pattern, and diagnosis with fibrotic HP are independent predictors of annual progression in mild FILD.

3D-CT-derived lung volumes and mortality risk in patients with fibrotic hypersensitivity pneumonitis

BACKGROUND

Hypersensitivity pneumonitis (HP) is a complex and heterogenous interstitial lung disease (ILD) that occurs in susceptible individuals due to certain inhaled antigens. Fibrotic-HP is a major underlying disease of progressive pulmonary fibrosis. Therefore, in addition to the radiological features of HP, quantitatively measuring fibrosis is important to evaluate disease severity and progression. The present study aimed to compare three-dimensional computed tomography (3D-CT)-derived lung volumes (LVs) of patients with HP and determine its association with mortality risk.

METHODS

In this retrospective and multicenter cohort study, 126 patients diagnosed with HP (fibrotic, n = 72 and non-fibrotic, n = 54) with a confidence level higher than moderate were enrolled. Each lobe LV was measured using 3D-CT at the time of diagnosis and standardized using predicted forced vital capacity. The 3D-CT LV was compared with those of 42 controls and 140 patients with idiopathic pulmonary fibrosis (IPF).

RESULTS

Compared to patients with fibrotic-HP, the standardized total LV was significantly higher in controls and patients with non-fibrotic-HP and was similar in patients with IPF. Longitudinal analyses demonstrated that approximately half of the patients with fibrotic-HP had an annual decrease in total LV. Decreased total and lower-lobe LVs were associated with shorter survival, and were independently associated with mortality together with ongoing exposure to inciting antigens. A composite model consisting of ongoing exposure to inciting antigens and total or lower-lobe LV successfully classified mortality risk into three groups.

CONCLUSIONS

Quantitatively measuring standardized LV can help determine disease severity, progression, and mortality risk in patients with fibrotic-HP.

Hypersensitivity pneumonitis radiologic features in interstitial lung diseases

BACKGROUND

The radiologic criteria of hypersensitivity pneumonitis (HP) guidelines focus on four HP compatible features (HPCF) in high-resolution computed tomography (HRCT): ground glass opacities, mosaic attenuation, air-trapping, and centrilobular nodules. However, evidence to support these criteria are limited.

METHODS

Consecutive interstitial lung disease (ILD) patients who underwent HRCT between 2016 and 2021 in three medical centers were included. We assessed the prevalence of HPCF in each ILD and their association with HP diagnosis. We evaluated the impact of HPCF amount for HP diagnosis and the performance of the radiologic criteria by the ATS/JRS/ALAT and CHEST HP guidelines.

RESULTS

436 patients with ILD were included (mean age 66, 48 % females), of them, 56 (13 %) with HP. All four HPCF were more prevalent in HP than in non-HP ILD (p < 0.001 for all). In multivariate analysis, air-trapping was the strongest independent predictor (AOR 4.1, 95 % CI 2-8.4, p < 0.001). Centrilobular nodules were present almost exclusively in HP and smoking-related ILD. The amount of HPCF in HRCT had an excellent predictive ability for HP diagnosis (receiver operating characteristic AUC 0.85, 95 % CI 0.80-0.90). The radiologic criteria of both guidelines had high specificity for "typical HP" and high sensitivity for "compatible with HP", although with low positive predictive values. Our findings remained robust even when including only patients that had a diagnostic biopsy.

CONCLUSION

The presence and amount of HPCF in HRCT predicted HP diagnosis in real-life settings. While current HP radiologic criteria demonstrated good diagnostic performance, our findings highlight areas for future improvement.

Cryoprobe biopsy versus mechanical biopsies in pulmonary diagnostics

PURPOSE OF REVIEW

Biopsy tools have been essential in improving the diagnostic accuracy of bronchoscopic procedures. Of these tools, cryobiopsy has emerged as a promising technique for diagnosing thoracic diseases. This review summarizes the existing data comparing cryobiopsies to other mechanical biopsy methods for sampling endobronchial, parenchymal, and mediastinal targets.

RECENT FINDINGS

Initially adopted for managing airway stenoses, the use of cryoprobes has expanded to diagnosing endobronchial lesions, parenchymal opacities, and mediastinal lymph node pathologies. Studies have demonstrated that cryobiopsy offers a higher diagnostic yield than forceps biopsy alone. By leveraging the Joule-Thomson effect to freeze and collect larger tissue samples compared to traditional methods, cryobiopsy improves diagnostic accuracy and helps in better characterizing the nature of the lesions. While the risk of complications, such as pneumothorax and hemorrhage are comparable to, or higher than traditional biopsy methods, cryobiopsy's enhanced diagnostic capabilities make it a valuable tool in the assessment of pulmonary disease.

SUMMARY

Compared with other mechanical biopsy techniques, cryoprobe biopsies significantly enhance the diagnostic yield for endobronchial lesions, interstitial lung disease, pulmonary nodules, and mediastinal lymph nodes.

BAL Fluid Cellular Analysis and Radiologic Patterns in Patients With Fibrotic Interstitial Lung Disease

BACKGROUND

BAL cellular analysis is often recommended during the initial diagnostic evaluation of fibrotic interstitial lung disease (ILD). Despite recommendation for its use, between-center heterogeneity exists and supportive data concerning the clinical utility and correlation of BAL findings with radiologic features or patterns remain sparse.

RESEARCH QUESTION

In patients with fibrotic ILD, are BAL findings associated with radiologic features, patterns, and clinical diagnoses?

STUDY DESIGN AND METHODS

Patients with fibrotic ILD who underwent BAL for diagnostic evaluation and who were enrolled in the prospective Canadian Registry for Pulmonary Fibrosis were re-reviewed in a standardized multidisciplinary discussion (MDD). BAL was categorized according to guideline-recommended thresholds, and using thresholds of lymphocytosis > 20% and neutrophils > 4.5%. High-resolution CT (HRCT) scans were scored (anonymized to clinical data) for specific features and percentage lung involvement. Radiologists classified HRCT scans according to guideline-defined patterns for idiopathic pulmonary fibrosis and fibrotic hypersensitivity pneumonitis; then, MDD diagnoses were assigned, considering all available data.

RESULTS

Bronchoscopy with cellular analysis was performed in 209 of 1,593 patients (13%). Lymphocyte % was weakly negatively correlated with total fibrosis % (r = -0.16, P = .023) but not statistically significantly correlated with ground glass opacity % (r = 0.01, P = .94). A mixed BAL pattern was the most frequent in all radiologic patterns (range, 45%-69%), with a minority classifiable according to BAL guidelines. BAL lymphocytosis appeared with similar frequency across HRCT patterns of fibrotic hypersensitivity pneumonitis (21%) and usual interstitial pneumonia (18%). Only 5% of patients with MDD-based fibrotic hypersensitivity pneumonitis had a guideline-defined isolated lymphocytosis > 15%.

INTERPRETATION

BAL cellular analyses did not significantly correlate with radiologic features, guideline patterns, or MDD-based diagnoses. Ground glass opacities are often interpreted to represent pulmonary inflammation, but were not associated with BAL lymphocytosis in this cohort.

Treatable traits in interstitial lung disease: a narrative review

The interstitial lung diseases (ILDs) are a heterogeneous and complex group of diseases. The treatable trait (TT) model represents a shift in ILD management, away from traditional diagnostic labels towards a more individualised, trait-focused approach. This review explores the application of the TT paradigm to ILD, identifying key traits across the aetiological, pulmonary, extrapulmonary and behavioural domains. By addressing these traits, the TT model offers a framework to improve outcomes in ILD through multidisciplinary management with a precision medicine focus. Further research is necessary to evaluate the overall impact of this TT model on ILD care.

Pathological features of connective tissue disease-associated interstitial lung disease in transbronchial cryobiopsies

AIM

Transbronchial cryobiopsies are increasingly used for the diagnosis of interstitial lung disease (ILD), but there is a lack of published information on the features of specific ILD in cryobiopsies. Here we attempt to provide pathological guidelines for separating usual interstitial pneumonia (UIP) of idiopathic pulmonary fibrosis (IPF), fibrotic hypersensitivity pneumonitis (FHP) and connective tissue disease-associated ILD (CTD-ILD) in cryobiopsies.

METHODS

We examined 120 cryobiopsies from patients with multidisciplinary discussion (MDD)-established CTD-ILD and compared them to a prior series of 121 biopsies from patients with MDD-established IPF or FHP.

RESULTS

A non-specific interstitial pneumonia (NSIP) pattern alone was seen in 36 of 120 (30%) CTD-ILD, three of 83 (3.6%) FHP and two of 38 (5.2%) IPF cases, statistically favouring a diagnosis of CTD-ILD. The combination of NSIP + OP was present in 29 of 120 (24%) CTD-ILD, two of 83 (2.4%) FHP and none of 38 (0%) IPF cases, favouring a diagnosis of CTD-ILD. A UIP pattern, defined as fibroblast foci plus any of patchy old fibrosis/fibrosis with architectural distortion/honeycombing, was identified in 28 of 120 (23%) CTD-ILD, 45 of 83 (54%) FHP and 27 of 38 (71%) IPF cases and supported a diagnosis of FHP or IPF. The number of lymphoid aggregates/mm2 and fibroblast foci/mm2 was not different in IPF, CTD-ILD or FHP cases with a UIP pattern. Interstitial giant cells supported a diagnosis of FHP or CTD-ILD over IPF, but were infrequent.

CONCLUSIONS

In the correct clinical/radiological context the pathological findings of NSIP, and particularly NSIP plus OP, favour a diagnosis of CTD-ILD in a cryobiopsy, but CTD-ILD with a UIP pattern, FHP with a UIP pattern and IPF generally cannot be distinguished.

The role of vascularity and the fibrovascular interface in interstitial lung diseases

Interstitial lung disease (ILD) is a clinical term that refers to a diverse group of non-neoplastic lung diseases. This group includes idiopathic and secondary pulmonary entities that are often associated with progressive pulmonary fibrosis. Currently, therapeutic approaches based on specific structural targeting of pulmonary fibrosis are limited to nintedanib and pirfenidone, which can only slow down disease progression leading to a lower mortality rate. Lung transplantation is currently the only available curative treatment, but it is associated with high perioperative mortality. The pulmonary vasculature plays a central role in physiological lung function, and vascular remodelling is considered a hallmark of the initiation and progression of pulmonary fibrosis. Different patterns of pulmonary fibrosis commonly exhibit detectable pathological features such as morphomolecular changes, including intussusceptive and sprouting angiogenesis, vascular morphometry, broncho-systemic anastomoses, and aberrant angiogenesis-related gene expression patterns. Dynamic cellular interactions within the fibrovascular interface, such as endothelial activation and endothelial-mesenchymal transition, are also observed. This review aims to summarise the current clinical, radiological and pathological diagnostic algorithm for different ILDs, including usual interstitial pneumonia/idiopathic pulmonary fibrosis, non-specific interstitial pneumonia, alveolar fibroelastosis/pleuroparenchymal fibroelastosis, hypersensitivity pneumonitis, systemic sclerosis-related ILD and coronavirus disease 2019 injury. It emphasises an interdisciplinary clinicopathological perspective. Additionally, the review covers current therapeutic strategies and knowledge about associated vascular abnormalities.

Circulating MicroRNAs in Idiopathic Pulmonary Fibrosis: A Narrative Review

Idiopathic pulmonary fibrosis (IPF) is a chronic, deathly disease with no recognized effective cure as yet. Furthermore, its diagnosis and differentiation from other diffuse interstitial diseases remain a challenge. Circulating miRNAs have been measured in IPF and have proven to be an adequate option as biomarkers for this disease. These miRNAs, released into the circulation outside the cell through exosomes and proteins, play a crucial role in the pathogenic pathways and mechanisms involved in IPF development. This review focuses on the serum/plasma miRNAs reported in IPF that have been validated by real-time PCR and the published evidence regarding the fibrotic process. First, we describe the mechanisms by which miRNAs travel through the circulation (contained in exosomes and bound to proteins), as well as the mechanism by which miRNAs perform their function within the cell. Subsequently, we summarize the evidence concerning miRNAs reported in serum/plasma, where we find contradictory functions in some miRNAs (dual functions in IPF) when comparing the findings in vitro vs. in vivo. The most relevant finding, for instance, the levels of miRNAs let-7d and miR-21 reported in the serum/plasma in IPF, correspond to those found in studies in lung fibroblasts and the murine bleomycin model, reinforcing the usefulness of these miRNAs as future biomarkers in IPF.

[Diagnosis and Treatment of Hypersensitivity Pneumonitis - S2k Guideline of the German Respiratory Society and the German Society for Allergology and Clinical Immunology]

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease (ILD) in sensitized individuals caused by a large variety of inhaled antigens. The clinical form of acute HP is often misdiagnosed, while the chronic form, especially the chronic fibrotic HP, is difficult to differentiate from other fibrotic ILDs. The present guideline for the diagnosis and treatment of HP replaces the former German recommendations for the diagnosis of HP from 2007 and is amended explicitly by the issue of the chronic fibrotic form, as well as by treatment recommendations for the first time. The evidence was discussed by a multidisciplinary committee of experts. Then, recommendations were formulated for twelve questions on important issues of diagnosis and treatment strategies. Recently published national and international guidelines for ILDs and HP were considered. Detailed background information on HP is useful for a deeper insight into HP and the handling of the guideline.

Diagnosis and management of hypersensitivity pneumonitis in adults: A position statement from the Thoracic Society of Australia and New Zealand

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease (ILD) relating to specific occupational, environmental or medication exposures. Disease behaviour is influenced by the nature of exposure and the host response, with varying degrees of lung inflammation and fibrosis seen within individuals. The differentiation of HP from other ILDs is important due to distinct causes, pathophysiology, prognosis and management implications. This Thoracic Society of Australia and New Zealand (TSANZ) position statement aims to provide an up-to-date summary of the evidence for clinicians relating to the diagnosis and management of HP in adults, in the Australian and New Zealand context. This document highlights recent relevant findings and gaps in the literature for which further research is required.

Acute exacerbation of progressive pulmonary fibrosis: incidence and outcomes

BACKGROUND

Few data are available on acute exacerbation (AE) in patients with progressive pulmonary fibrosis (PPF) besides idiopathic pulmonary fibrosis (IPF). This study aimed to investigate the AE incidence and outcomes among patients with PPF.

METHODS

Clinical data of patients with PPF (n = 133) were retrospectively collected at a single center. PPF was defined based on the criteria used in the INBUILD trial. AE was defined as a worsening of dyspnea typically within 30 days with new bilateral lung infiltration and no evidence of cardiac failure or fluid overload.

RESULTS

Among patients with PPF, the mean age was 60.6 years old, 57.1% were females, and the most common etiology was connective tissue disease-related ILDs (63%). During the follow-up (median: 38.0 months) after PPF diagnosis, 42 patients (31.6%) experienced AE. The 1-, 3-, and 5-year AE incidences were 12.5%, 30.3%, and 38.0%, respectively. Older age, rheumatoid arthritis associated ILD, fibrotic hypersensitivity pneumonitis, and lower lung diffusing capacity for carbon monoxide were AE risk factors. Patients with AE demonstrated worse survival (median survival: 30 months vs. not reached; p < 0.001) after PPF diagnosis than those without. AE was independently associated with mortality in patients with PPF (hazard ratio [HR], 2.194; 95% confidence interval [CI], 1.285-3.747; p = 0.004) in the multivariable Cox analysis, along with older age, lower lung diffusing capacity for carbon monoxide, and the usual interstitial pneumonia-like pattern on high-resolution computed tomography.

CONCLUSIONS

Our results suggest AE is not uncommon and significantly impacts on survival in patients with PPF.

Clinical predictors of physiologic change after treatment with immunosuppression in hypersensitivity pneumonitis

INTRODUCTION

Treatment of hypersensitivity pneumonitis involves removal of the antigen and may include the use of immunosuppression or antifibrotic therapy. It remains unclear whether antifibrotic or immunosuppressive therapy is more beneficial in fibrotic hypersensitivity pneumonitis or if clinical markers can predict a patient's response to therapy.

METHODS

We evaluated a retrospective cohort in order to determine if certain clinical characteristics can predict physiologic improvement with immunosuppressive treatment in patients with chronic hypersensitivity pneumonitis. Patients with a diagnosis of hypersensitivity pneumonitis with a moderate, high, or definite confidence according to the American Thoracic Society criteria were included in the study.

RESULTS

Overall immunosuppression did not lead to improvement in % predicted forced vital capacity (FVC%) and % predicted diffusion capacity (DLCO%). Patients with fibrotic hypersensitivity pneumonitis and those with familial interstitial lung disease demonstrated a decline in FVC% predicted as well as DLCO% predicted over one year and the use of immunosuppression does not modify that risk. In contrast, patients with extensive ground glass demonstrated improvement in DLCO% predicted but not FVC% predicted over one year with or without the use of immunosuppression.

CONCLUSION

Our study demonstrates that certain radiographic variables trend toward a significant impact on FVC% predicted as well as DLCO% predicted and suggests that antifibrotic therapy may be a better initial choice of therapy in patients with fibrotic hypersensitivity pneumonitis as decline occurred with or without the use of immunosuppression.

Single-Cell Analysis Reveals Novel Immune Perturbations in Fibrotic Hypersensitivity Pneumonitis

Rationale: Fibrotic hypersensitivity pneumonitis (FHP) is a debilitating interstitial lung disease driven by incompletely understood immune mechanisms. Objectives: To elucidate immune aberrations in FHP in single-cell resolution. Methods: Single-cell 5' RNA sequencing was conducted on peripheral blood mononuclear cells and BAL cells obtained from 45 patients with FHP, 63 patients with idiopathic pulmonary fibrosis (IPF), 4 patients with nonfibrotic hypersensitivity pneumonitis, and 36 healthy control subjects in the United States and Mexico. Analyses included differential gene expression (Seurat), TF (transcription factor) activity imputation (DoRothEA-VIPER), and trajectory analyses (Monocle3 and Velocyto-scVelo-CellRank). Measurements and Main Results: Overall, 501,534 peripheral blood mononuclear cells from 110 patients and control subjects and 88,336 BAL cells from 19 patients were profiled. Compared with control samples, FHP has elevated classical monocytes (adjusted-P = 2.5 × 10-3) and is enriched in CCL3hi/CCL4hi and S100Ahi classical monocytes (adjusted-P < 2.2 × 10-16). Trajectory analyses demonstrate that S100Ahi classical monocytes differentiate into SPP1hi lung macrophages associated with fibrosis. Compared with both control subjects and IPF, cells from patients with FHP are significantly enriched in GZMhi cytotoxic T cells. These cells exhibit TF activities indicative of TGFβ and TNFα and NFκB pathways. These results are publicly available at http://ildimmunecellatlas.com. Conclusions: Single-cell transcriptomics of patients with FHP uncovered novel immune perturbations, including previously undescribed increases in GZMhi cytotoxic CD4+ and CD8+ T cells-reflecting this disease's unique inflammatory T cell-driven nature-as well as increased S100Ahi and CCL3hi/CCL4hi classical monocytes also observed in IPF. Both cell populations may guide the development of new biomarkers and therapeutic interventions.

Repeated inhalation of GM-CSF by nonhuman primates induces bronchus-associated lymphoid tissue along the lower respiratory tract

BACKGROUND

Repeated inhalation of granulocyte-macrophage colony-stimulating factor (GM-CSF) was recently approved in Japan as a treatment for autoimmune pulmonary alveolar proteinosis. However, the detailed physiological and pathological effects of repeated inhalation in the long term, especially at increasing doses, remain unclear.

METHODS

In this chronic safety study, we administered 24 cynomolgus monkeys (Macaca fascicularis) aged 2-3 years with aerosolized sargramostim (a yeast-derived recombinant human GM-CSF [rhGM-CSF]) biweekly for 26 weeks across four dosing groups (0, 5, 100, and 500 µg/kg/day). We measured the serum GM-CSF antibody (GM-Ab) concentration by an ELISA and assessed the neutralizing capacity of GM-Ab using the GM-CSF-dependent cell line TF-1. We subjected lung tissue samples taken from all monkeys at 27 weeks to histopathological assessment using a sargramostim-specific monoclonal antibody to detect localization of residual sargramostim.

RESULTS

All the animals maintained good body condition and showed steady weight gain throughout the study. The pathological analyses of the lung revealed the formation of induced bronchus-associated lymphoid tissue (iBALT) in the lower respiratory tract, even at the clinical dose of 5 µg/kg/day. There was a relationship between the number or size of BALT and sargramostim dose or the serum GM-Ab levels. Immunohistochemical analyses revealed GM-Ab-producing cells in the follicular region of iBALT, with residual sargramostim in the follicles. Leucocyte counts were inversely correlated with GM-Ab levels in the high-dose groups. Additionally, serum GM-Ab from the treated animals significantly suppressed the alveolar macrophage proliferation activity of both Cynomolgus recombinant and rhGM-CSF in vitro.

CONCLUSION

Long-term repeated inhalation of sargramostim led to iBALT formation in the lower respiratory tract, even at the clinical dose of 5 µg/kg/day, with the extent of iBALT formation increasing in a dose-dependent manner. Inhaled sargramostim was localized to the follicular region of iBALT nodules, which may induce the production of GM-Ab.

Spatially resolved gene expression profiles of fibrosing interstitial lung diseases

Fibrosing interstitial lung diseases (ILDs) encompass a diverse range of scarring disorders that lead to progressive lung failure. Previous gene expression profiling studies focused on idiopathic pulmonary fibrosis (IPF) and bulk tissue samples. We employed digital spatial profiling to gain new insights into the spatial resolution of gene expression across distinct lung microenvironments (LMEs) in IPF, chronic hypersensitivity pneumonitis (CHP) and non-specific interstitial pneumonia (NSIP). We identified differentially expressed genes between LMEs within each condition, and across histologically similar regions between conditions. Uninvolved regions in IPF and CHP were distinct from normal controls, and displayed potential therapeutic targets. Hallmark LMEs of each condition retained distinct gene signatures, but these could not be reproduced in matched lung tissue samples. Based on these profiles and unsupervised clustering, we grouped previously unclassified ILD cases into NSIP or CHP. Overall, our work uniquely dissects gene expression profiles between LMEs within and across different types of fibrosing ILDs.

Serum metalloproteinase-7 as a biomarker of progressive pulmonary fibrosis

Introduction

Progressive pulmonary fibrosis (PPF) corresponds to any fibrotic interstitial lung disease (ILD) other than idiopathic pulmonary fibrosis (IPF) that presents clinical, physiological and/or radiological evidence of disease progression similar to IPF. Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of pulmonary fibrosis and are associated with disease progression and reduced survival in IPF and other fibrotic ILDs. This study aimed to investigate the role of serum levels of MMP-1 and MMP-7 in patients with fibrotic non-IPF ILD as possible biomarkers of patients at risk of developing PPF.

Methods

Newly diagnosed patients with fibrotic non-IPF ILD were included in this study. Serum levels of MMP-1 and MMP-7 were quantified at baseline and disease progression was monitored. PPF was defined according to the recent European Respiratory Society, American Thoracic Society, Japanese Respiratory Society and the Latin American Thoracic Society Clinical Practice Guidelines.

Results

79 patients with fibrotic non-IPF ILDs were included and classified as having PPF or non-PPF. Significantly higher levels of MMP-7, but not MMP-1, were detected in the PPF group (p=0.01). MMP-7 was independently associated with PPF (adjusted OR 1.263, 95% CI 1.029-1.551; p=0.026) after adjustment for sex, age and smoking history. A cut-off value of 3.53 ng·mL-1 for serum MMP-7 levels had a sensitivity of 61% and a specificity of 74% for predicting PPF in non-IPF ILDs.

Conclusions

In patients with fibrotic non-IPF ILDs, serum MMP-7 levels were significantly greater in the subgroup of patients meeting the PPF criteria at follow-up. This can be considered and further investigated as a possible biomarker to identify fibrotic ILD patients at risk of PPF.

The 1-minute sit-to-stand test to evaluate fibrotic interstitial lung disease

INTRODUCTION

Fibrotic interstitial lung diseases (ILD) are a heterogeneous group of conditions. Progression criteria include clinical, imaging, and/or lung functional decline. Currently, the 6-min walk test (6MWT) is considered the gold standard for assessing exercise-induced desaturation. The 1-min sit-to-stand test (1STST) has the advantage of being easy to perform, making it feasible for use during clinical consultations. The aim of this study was to compare the 1STST with the 6MWT in patients with fibrotic ILD to detect exercise-induced desaturation.

METHODS

A multicenter cross-sectional involved patients with fibrotic ILDs from two centers. The 6MWT and 1STST were performed with a 30-min rest period between the tests. The modified Borg scale was used to assess dyspnea and lower limb fatigue and continuous SpO2 and heart rate were monitored. Desaturation was defined as SpO2 < 90 % or decline >3 %.

RESULTS

Ninety patients were included. The median walking distance in the 6MWT was 432 m and the median number of repetitions in the 1STST was 22, with a significant correlation (p < 0.001, ρ = 0.383). In addition, the minimum SpO2 and the desaturation levels recorded during the tests exhibited a moderate significant correlation (p < 0.001, ρ = 0.502 and p < 0.001, ρ = 0.537, respectively). There was a strong association between the increase in Borg score for dyspnea and a moderate association between the increase in Borg score for lower limb fatigue after both tests (p < 0.001, ρ = 0.706 and p < 0.001, ρ = 0.656, respectively).

CONCLUSIONS

This study demonstrates a significant correlation between the 6MWT and the 1STST in detecting exercise-induced desaturation.

A Low Forced Vital Capacity (FVC)/Diffusing Capacity of the Lung for Carbon Monoxide (DLCO) Ratio Increases Clinical Suspicion for Fibrotic Hypersensitivity Pneumonitis (FHP) Over Idiopathic Pulmonary Fibrosis (IPF)

Background and objective Fibrotic Hypersensitivity Pneumonitis (FHP) and idiopathic pulmonary fibrosis (IPF) are interstitial lung diseases (ILDs) that are challenging to differentiate with prognostic and therapeutic implications. Clinical observations suggest that patients with FHP may have a lower baseline ratio of forced vital capacity (FVC) to the diffusing capacity of the lung for carbon monoxide (DLCO), or FVC/DLCO (F/D) ratio, than patients with IPF. In light of this, we aimed to determine whether patients with FHP have a significantly lower baseline F/D ratio than patients with IPF. Methods A retrospective chart review was performed at a single academic ILD center. Patients with a probable or definite diagnosis of FHP or IPF were considered for inclusion, while patients with poor-quality pulmonary function tests (PFTs) were excluded. The data collected included demographics, diagnosis modality, FVC and DLCO values within six months of diagnosis, as well as hemoglobin levels within three months of PFTs. Baseline F/D ratios were calculated using each patient's FVC percentage of predicted value divided by the DLCO percentage of predicted value adjusted for hemoglobin when available. One-tailed independent two-sample T-tests were performed. Results Eighty-nine patients met the inclusion criteria: 39 (44%) with FHP and 50 (56%) with IPF. The mean baseline F/D ratio was significantly lower for patients with FHP (M = 1.24, 95% CI: 1.14, 1.33) than for patients with IPF (M = 1.44, 95% CI: 1.31, 1.57, T(87) = 2.23, p = 0.014). A secondary analysis excluding patients with pulmonary hypertension and resting hypoxemia was performed, yielding 72 patients: 32 (44%) with FHP and 40 (56%) with IPF. The mean baseline F/D ratio was significantly lower for patients with FHP (M = 1.22, 95% CI: 1.12, 1.31) compared to patients with IPF (M = 1.37, 95% CI: 1.27, 1.46, T (70) = 2.37, p = 0.01). Conclusions In patients with probable to definite FHP versus IPF, the baseline F/D ratio was significantly lower in patients with FHP, even after excluding patients with coexisting pulmonary hypertension and resting hypoxemia. A lower baseline F/D ratio may be a novel, clinic-ready index to heighten clinical suspicion for FHP compared to IPF. Further larger prospective studies are needed to validate our findings.

Reevaluating diagnosis in interstitial lung disease with a second multidisciplinary discussion

BACKGROUND

The importance of multidisciplinary discussion (MDD) for diagnosing interstitial lung disease (ILD) is emphasized by several international guidelines. While initial diagnoses are often provisional and require periodic re-evaluation, there is a lack of literature regarding the role of follow-up MDD in clinical practice.

METHODS

From September 2020 to January 2022, patients underwent an initial MDD (MDD1) based on clinical, radiological, and pathological evaluations. Each diagnosis was assigned a confidence level. One year later, a second MDD (MDD2) was conducted for re-evaluation, based on subsequent clinical and radiological information. Changes in diagnosis and confidence levels between MDD1 and MDD2 were assessed.

RESULTS

Among 52 patients enrolled in both MDDs, the diagnosis for 13 (25%) was revised at MDD2. Of these, 10 patients were initially diagnosed with unclassifiable ILD, and 3 received a low confidence diagnosis of either idiopathic pulmonary fibrosis or idiopathic nonspecific interstitial pneumonia. The most common diagnostic revision was due to the deterioration after antigen exposure or improvement after antigen avoidance, which resulted in a revised diagnosis of HP at MDD2.

CONCLUSIONS

Our findings underscore the importance of periodic reassessment of MDD to improve the accuracy of ILD diagnosis. This study highlights the significance of longitudinal clinical and radiological evaluation for diagnostic revision, even in situations when rebiopsy is not feasible.

Pulmonary fibrosis in pulmonary alveolar proteinosis evaluated by transbronchial lung cryobiopsy: A single-center retrospective study

BACKGROUND

Approximately 20% of patients with pulmonary alveolar proteinosis (PAP) present with pulmonary fibrosis on high-resolution computed tomography (HRCT). Although transbronchial lung cryobiopsy (TBLC) has recently been used to diagnose fibrotic interstitial lung disease, no studies have investigated whether TBLC is useful for the histopathological detection of pulmonary fibrosis coexisting with PAP. Therefore, the present study aimed to investigate the utility of TBLC for evaluating pulmonary fibrosis in patients with PAP.

METHODS

We retrospectively reviewed patients diagnosed with PAP who underwent TBLC at our hospital between May 2021 and March 2023. We collected data including patient background, HRCT findings, and histopathological findings of the TBLC samples.

RESULTS

Seven patients met the inclusion criteria, with a median age was 69 years; 5 patients were male. Six patients were diagnosed with autoimmune PAP, and one was diagnosed with unclassified PAP. Periodic acid-Schiff staining-positive materials in the alveoli were observed in six out of seven patients. Pulmonary fibrosis, defined as fibrosis with architectural distortion, was found in two patients. Fibroblastic foci and airway-centered fibrosis were presented in two and one patient, respectively. As a result of a multidisciplinary discussion, we diagnosed one each with fibrotic HP coexisting with PAP and PAP-associated fibrosis.

CONCLUSION

Two of the seven patients with PAP presented histopathologically with pulmonary fibrosis in samples obtained through TBLC. Thus, TBLC should be considered when the coexistence of pulmonary fibrosis is suspected.

Correlation between CT-based phenotypes and serum biomarker in interstitial lung diseases

BACKGROUND

The quantitative analysis of computed tomography (CT) and Krebs von den Lungen-6 (KL-6) serum level has gained importance in the diagnosis, monitoring, and prognostication of interstitial lung disease (ILD). However, the associations between quantitative analysis of CT and serum KL-6 level remain poorly understood.

METHODS

In this retrospective observational study conducted at tertiary hospital between June 2020 and March 2022, quantitative analysis of CT was performed using the deep learning-based method including reticulation, ground glass opacity (GGO), honeycombing, and consolidation. We investigated the associations between CT-based phenotypes and serum KL-6 measured within three months of the CT scan. Furthermore, we evaluated the performance of the combined CT-based phenotypes and KL-6 levels in predicting hospitalizations due to respiratory reasons of ILD patients.

RESULTS

A total of 131 ILD patients (104 males) with a median age of 67 years were included in this study. Reticulation, GGO, honeycombing, and consolidation extents showed a positive correlation with KL-6 levels. [Reticulation, correlation coefficient (r) = 0.567, p < 0.001; GGO, r = 0.355, p < 0.001; honeycombing, r = 0.174, p = 0.046; and consolidation, r = 0.446, p < 0.001]. Additionally, the area under the ROC of the combined reticulation and KL-6 for hospitalizations due to respiratory reasons was 0.810 (p < 0.001).

CONCLUSIONS

Quantitative analysis of CT features and serum KL-6 levels ascertained a positive correlation between the two. In addition, the combination of reticulation and KL-6 shows potential for predicting hospitalizations of ILD patients due to respiratory causes. The combination of reticulation, focusing on phenotypic change in lung parenchyma, and KL-6, as an indicator of lung injury extent, could be helpful for monitoring and predicting the prognosis of various types of ILD.

Development and evaluation of a questionnaire to capture environmental and occupational inhalational exposures in adults with fibrotic interstitial lung disease

BACKGROUND

Identification of exposures in patients with interstitial lung diseases (ILDs) is essential for diagnosis and management and can be facilitated through the use of exposure questionnaires. However, for most ILDs, a patient-focused questionnaire is lacking. Cognitive interviewing is a methodology used to evaluate sources of understanding and misunderstanding in a questionnaire and to provide evidence of content validity. We developed and refined a new exposure questionnaire for patients with fibrotic ILDs by using cognitive interviewing to establish its understandability and content validity.

METHODS

An exposure assessment questionnaire was developed by a multidisciplinary team. Cognitive interviews with 24 patients with fibrosing ILDs were conducted by trained interviewers over the phone or Zoom using a semi-structured interview guide. The questionnaire was amended based on the interviewers' interpretation of sources of misunderstanding. The revised questionnaire was tested in a second round of cognitive interviews with a different group of 24 patients.

RESULTS

Among the 48 patients who completed interviews, mean age was 61 years, 58.3% were male and 75.0% were white. Based on the first round of cognitive interviews, the multidisciplinary team modified the questions, organization, and instructions of the questionnaire to facilitate recall, adjust for exposures that were frequently misunderstood or required clarification, and focus on clinically relevant exposures. The revised questionnaire performed well in the second round of interviews.

CONCLUSION

An exposure questionnaire, developed with input from patients, can be used to assess clinically relevant exposures in adults with fibrosing ILDs. This is the first questionnaire for all types of fibrosing ILD to have undergone content validation.

The providing multidisciplinary ILD diagnoses (PROMISE) study - study design of the national registry of Japan facilitating interactive online multidisciplinary discussion diagnosis

BACKGROUND

Multidisciplinary discussion (MDD), in which physicians, radiologists, and pathologists communicate and diagnose together, has been reported to improve diagnostic accuracy compared to diagnoses made solely by physicians. However, even among experts, diagnostic concordance of MDD is not always good, and some patients may not receive a specific diagnosis due to insufficient findings. A provisional diagnosis based on the ontology with a diagnostic confidence level has recently been proposed. Additionally, we developed an artificial intelligence model to differentiate idiopathic pulmonary fibrosis (IPF) from other chronic interstitial lung diseases (ILD)s, which needs validation in a broader population.

METHODS

This prospective nationwide ILD registry has recruited patients with newly diagnosed ILD at the referral respiratory hospitals in Japan and provides rapid MDD diagnoses and treatment recommendations through a central online MDD platform with a 3-year follow-up period. A modified diagnostic ontology is used. If no diagnosis reaches more than 50% certainty, the diagnosis is unclassifiable ILD. If multiple diseases are expected, the diagnosis with a high probability takes precedence. If the confidence levels for the top two possible diagnoses are equal, the diagnosis can be unclassifiable. The registry uses tentative diagnostic criteria for nonspecific interstitial pneumonia with organising pneumonia and smoking-related ILD not otherwise specified as possible new entities. Central MDD diagnosticians review the clinical data, test results, radiology images, and pathological specimens on a dedicated website and conduct MDD diagnoses using online meetings with a cloud-based reporting system. This study aims to (1) provide MDD diagnoses with treatment recommendations; (2) determine the overall ILD rates in Japan; (3) clarify the reasons for unclassifiable ILDs; (4) evaluate possible new disease entities; (5) identify progressive phenotypes and create a clinical prediction model; (6) measure the agreement rate between institutional and central diagnoses in ILD referral and non-referral centres; (7) identify key factors for each specific ILD diagnosis; and (8) create a new disease classification system based on treatment strategies, including the use of antifibrotic drugs.

DISCUSSION

This study will provide ILD frequencies, including new entities, using central MDD on dedicated online systems, and develop a machine learning model for ILD diagnosis and prognosis prediction.

TRIAL REGISTRATION

UMIN-CTR Clinical Trial Registry (UMIN000040678).

Altered expression pattern of immune response-related genes and isoforms in hypersensitivity pneumonitis lung fibroblasts

Hypersensitivity pneumonitis (HP) is an immune-mediated inflammatory interstitial lung disease that may evolve to pulmonary fibrosis, a progressive disorder with a poor prognosis characterized by fibroblast activation and extracellular matrix accumulation. In HP lung fibroblasts, the gene expression of proteins involved in the interaction with the immune response, their isoforms, and how they influence their phenotype have yet to be elucidated. We analyzed the expression and splicing variants of 16 target genes involved in the interaction between HP fibroblasts and immune signaling and evaluated possible correlations with clinical data. The comparison of HP and control fibroblasts revealed distinct gene expression patterns. HP lung fibroblasts displayed an increased expression of IFI27 and PDFGRA and a downregulation of IL17RC and TGFBR3. IFI27 immunoreactive protein was markedly increased in HP lung tissues and normal fibroblasts treated with TGF-β. Furthermore, IFI27 overexpression in normal fibroblasts increased α-SMA and decreased cell number over time. The isoform analysis showed similar expression patterns for most genes, except for the AGER receptor with increased soluble variants relative to full-length AGER in HP fibroblasts. These findings indicate important differences in the expression of genes related to the immune response by HP fibroblasts, highlighting their unique characteristics and providing further insight into a possible profibrotic role of IFI27 in the disease.

Sarcopenia in interstitial lung disease

BACKGROUND

Interstitial lung disease (ILD) encompasses a heterogeneous group of chronic lung conditions with considerable variability in prognosis and response to treatment. People with reduced muscle mass and function, known as sarcopenia, have a higher risk of mortality and adverse clinical outcomes both in the general population and in other chronic disease states. The importance of sarcopenia across the spectrum of patients with ILD is not well established.

OBJECTIVES

In this narrative review, we explore the prevalence and clinical implications of sarcopenia in patients with ILD, evaluate the optimal methods to diagnose sarcopenia in this patient population and review treatment interventions.

FINDINGS

Almost one third of patients with chronic forms of ILD have evidence of sarcopenia. Sarcopenia is associated with adverse clinical outcomes and increased risk of mortality in select populations with ILD. Screening tests such as the SARC-F (strength, assistance walking, rise from a chair, climb stairs, falls) questionnaire and clinical assessment tools (including grip strength dynamometry) are well validated. Medical imaging modalities, including computed tomography, are hampered by lack of a gold standard and normative values, but have been used in patients with ILD in acute care and research settings. If sarcopenia is identified, multidimensional interventions such as pulmonary rehabilitation are beneficial.

CONCLUSION

Sarcopenia is common in patients with ILD and is associated with poorer outcomes. Accordingly, if identified, targeted interventions should be considered. Validated diagnostic criteria exist, but the optimal use of medical imaging techniques in this patient cohort remains an area of uncertainty.

Correlation of CT-based radiomics analysis with pathological cellular infiltration in fibrosing interstitial lung diseases

PURPOSE

We aimed to identify computed tomography (CT) radiomics features that are associated with cellular infiltration and construct CT radiomics models predictive of cellular infiltration in patients with fibrotic ILD.

MATERIALS AND METHODS

CT images of patients with ILD who underwent surgical lung biopsy (SLB) were analyzed. Radiomics features were extracted using artificial intelligence-based software and PyRadiomics. We constructed a model predicting cell counts in histological specimens, and another model predicting two classifications of higher or lower cellularity. We tested these models using external validation.

RESULTS

Overall, 100 patients (mean age: 62 ± 8.9 [standard deviation] years; 61 men) were included. The CT radiomics model used to predict cell count in 140 histological specimens predicted the actual cell count in 59 external validation specimens (root-mean-square error: 0.797). The two-classification model's accuracy was 70% and the F1 score was 0.73 in the external validation dataset including 30 patients.

CONCLUSION

The CT radiomics-based model developed in this study provided useful information regarding the cellular infiltration in the ILD with good correlation with SLB specimens.

The Diagnostic Efficiency and Safety of Transbronchial Lung Cryobiopsy Using 1.1-mm Cryoprobe in Diagnosing Interstitial Lung Disease

INTRODUCTION

Transbronchial lung cryobiopsy (TBLC) is increasingly used to diagnose interstitial lung disease (ILD). The 1.1-mm cryoprobe has recently been available in clinical practice. The diagnostic yield and safety of TBLC using a 1.1-mm cryoprobe need to be confirmed.

METHODS

A prospective, randomized controlled trial was conducted in patients with suspected ILD and randomly assigned to 1.1-mm and 1.9-mm cryoprobe groups. The primary outcome was the diagnostic yield of multidisciplinary discussion. Secondary outcomes were sample quality and incidence of complications. The tension and stress effects during TBLC onto the target lobe caused by 1.1-mm and 1.9-mm cryoprobes were also evaluated using finite element analysis.

RESULTS

A total of 224 patients were enrolled. No significant differences were observed in the diagnostic yield (80.4% vs. 79.5%, p = 0.845) and sample quality scores (5.73 ± 0.64 vs. 5.66 ± 0.77; p = 0.324) between the 1.9-mm cryoprobe group and 1.1-mm cryoprobe group. The average surface areas of samples in 1.1-mm cryoprobe group were smaller, while no difference in sample weights was observed. A decreased incidence of moderate bleeding was found in the 1.1-mm cryoprobe group (17.0% vs. 6.2%, p = 0.027), while there was no difference in the incidence of the pneumothorax, there was a trend to higher rate of pneumothorax in 1.1-mm group. In finite element analysis, the 1.1-mm cryoprobe required the largest tension and produced the largest stress.

CONCLUSION

Compared with a 1.9-mm cryoprobe, there was no difference in specimen quality or diagnostic rate but smaller sample size with a 1.1-mm cryoprobe. There was a decreased risk of moderate bleeding, but a trend towards increased risk for pneumothorax with 1.1-mm cryoprobe.

TRAIL REGISTRATION

Clinicaltrials.gov identifier NCT04047667; registered August 4, 2019.

Krebs von den Lungen-6 as biomarker of the new progressive fibrotic phenotype of interstitial lung disease

BACKGROUND

Novel progressive fibrotic phenotype has recently been proposed characterized by progressive and inexorable worsening of the disease. Krebs von den Lungen-6 (KL-6) has been proposed as fibrotic-ILD biomarker. We aimed to assess the role of KL-6 in fibrotic-ILD and the progressive phenotype in accordance with serial serum KL-6.

METHODS

107 patients were enrolled in the study (median age,IQR, 65(54-71)y/o) followed at respiratory diseases and rheumatology units of University of Siena. Thirty-five had diagnoses of IPF, 18 sarcoidosis, 10 PLCH, 5 LAM, 24 fibrotic HP(fHP), 13 RA (4/13 RA-ILD) and 22 SSc (18/22 SSc-ILD). Serial serum samples were collected before therapy (t0) and 24 months later (t1) from IPF, SSc- and RA-ILD patients. Twenty-two healthy controls (HC) were enrolled. Serum samples were assayed for KL-6 concentrations (Fujirebio Europe, Gent, Belgium).

RESULTS

Higher KL-6 concentrations were reported in IPF, fHP and SSc-ILD patients than HC (p<0.0001). KL-6 cut-off value of 885 U/mL identified fibrotic-ILD patients. Logistic regression analysis indicated KL-6 (p=0.004) and smoking-habit (p=0.005) affected the ILD diagnosis. The decision tree model showed KL-6>1145 U/mL, DLco≤60.15 %, FVC≤86 % to classify 86 % IPF patients. Inverse correlation between T0-KL-6 and T1-FVC%(r=-0.314, p=0.046) and T1-DLco%(r=-0.327, p=0.038) in the progressive group.

CONCLUSION

KL-6 proved to be a reliable marker for diagnosis and prognosis of fibrotic ILD patients with predictive value in progressive fibrotic patients and a useful marker to identify the new and similar progressive phenotype of IPF and SSc-ILD patients assessing the functional progression in accordance with serial serum KL-6 measurements.

Diseases Involving the Lung Peribronchovascular Region: A CT Imaging Pathologic Classification

TOPIC IMPORTANCE

Chest CT imaging holds a major role in the diagnosis of lung diseases, many of which affect the peribronchovascular region. Identification and categorization of peribronchovascular abnormalities on CT imaging can assist in formulating a differential diagnosis and directing further diagnostic evaluation.

REVIEW FINDINGS

The peribronchovascular region of the lung encompasses the pulmonary arteries, airways, and lung interstitium. Understanding disease processes associated with structures of the peribronchovascular region and their appearances on CT imaging aids in prompt diagnosis. This article reviews current knowledge in anatomic and pathologic features of the lung interstitium composed of intercommunicating prelymphatic spaces, lymphatics, collagen bundles, lymph nodes, and bronchial arteries; diffuse lung diseases that present in a peribronchovascular distribution; and an approach to classifying diseases according to patterns of imaging presentations. Lung peribronchovascular diseases can appear on CT imaging as diffuse thickening, fibrosis, masses or masslike consolidation, ground-glass or air space consolidation, and cysts, acknowledging that some diseases may have multiple presentations.

SUMMARY

A category approach to peribronchovascular diseases on CT imaging can be integrated with clinical features as part of a multidisciplinary approach for disease diagnosis.

[Highlights 57th SEPAR Congress]

The Spanish Society of Pneumology and Thoracic Surgery (SEPAR) has held its 57th Congress in Valencia from 6 to 8 of June 2024. The SEPAR Congress is the leading meeting for the entire respiratory scientific community, which allows learning about the main scientific advances in this area and provides the ideal situation to create and strengthen ties. This year, under the title "Respiratory Health for everybody", the SEPAR Congress stressed the importance of raising awareness about the importance of caring for and protecting our respiratory system. In this review, we offer a summary of some notable issues addressed in six selected areas of interest: chronic obstructive pulmonary disease (COPD), asthma, interstitial lung diseases (ILDs), pulmonary vascular diseases, sleep and breathing disorders and respiratory physiotherapy.

Lung imaging patterns in connective tissue disease-associated interstitial lung disease impact prognosis and immunosuppression response

OBJECTIVES

Interstitial lung disease (ILD) in CTDs has highly variable morphology. We aimed to identify imaging features and their impact on ILD progression, mortality, and immunosuppression response.

METHODS

Patients with CTD-ILD had high-resolution chest CT (HRCT) reviewed by expert radiologists blinded to clinical data for overall imaging pattern [usual interstitial pneumonia (UIP); non-specific interstitial pneumonia (NSIP); organizing pneumonia (OP); fibrotic hypersensitivity pneumonitis (fHP); and other]. Transplant-free survival and change in percent-predicted forced vital capacity (FVC) were compared using Cox and linear mixed-effects models adjusted for age, sex, smoking, and baseline FVC. FVC decline after immunosuppression was compared with pre-treatment.

RESULTS

Among 645 CTD-ILD patients, the most frequent CTDs were SSc (n = 215), RA (n = 127), and inflammatory myopathies (n = 100). NSIP was the most common pattern (54%), followed by UIP (20%), fHP (9%), and OP (5%). Compared with the case for patients with UIP, FVC decline was slower in patients with NSIP (by 1.1%/year, 95% CI 0.2, 1.9) or OP (by 3.5%/year, 95% CI 2.0, 4.9), and mortality was lower in patients with NSIP [hazard ratio (HR) 0.65, 95% CI 0.45, 0.93] or OP (HR 0.18, 95% CI 0.05, 0.57), but higher in fHP (HR 1.58, 95% CI 1.01, 2.40). The extent of fibrosis also predicted FVC decline and mortality. After immunosuppression, FVC decline was slower compared with pre-treatment in NSIP (by 2.1%/year, 95% CI 1.4, 2.8), with no change for UIP or fHP.

CONCLUSION

Multiple radiologic patterns are possible in CTD-ILD, including a fHP pattern. NSIP and OP were associated with better outcomes and response to immunosuppression, while fHP had worse survival compared with UIP.

Solitary Pure Ground-glass Opacity Suspected of Being the Initial Presentation of Nonfibrotic Hypersensitivity Pneumonitis

We herein report a rare case of hypersensitivity pneumonitis (HP) that was initially demonstrated as solitary pure ground-glass opacity (GGO) on chest computed tomography (CT). A 51-year-old woman with a history of breast cancer underwent follow-up CT, which revealed solitary pure GGO. The patient developed exertional dyspnea after two years, and CT revealed diffuse centrilobular nodules in addition to GGO, which had increased in size. An antigen avoidance test was performed to diagnose HP, leading to the resolution of CT abnormalities, including the GGO. Our findings suggested that nonfibrotic HP can present as solitary pure GGO.

May Small Airways Dysfunction (SAD) Play a Role in the Idiopathic Pulmonary Fibrosis (IPF) and May SAD Be a Therapeutic Target?

Small airway dysfunction (SAD) is a pathological process that affects the bronchioles and non-cartilaginous airways below 2 mm in diameter. This short review presents a link between SAD and IPF. Pathomorphological changes of small airways in fibrotic lungs are discussed. Additionally, functional abnormalities related to SAD measured by spirometry and oscillometry are presented. The problem of early detection and treatment of SAD as a procedure potentially capable of mitigating fibrosis is mentioned.

Hypersensitivity Pneumonitis: An Interesting Case of Acute Shortness of Breath in a Young Patient

Hypersensitivity pneumonitis (HP) is a rare disease caused by an inflammation of the distal airway caused by an immune response to inhaled allergens. The clinical presentation and radiological and histological findings can overlap with other pulmonary conditions such as idiopathic pulmonary fibrosis. Therefore, it is essential to consider focused assessment for the patient if a diagnosis of HP is suspected. We present a case involving a young female patient who presented with symptoms of cough, flu-like illness, and dyspnea. Subsequent investigations revealed a diagnosis of nonfibrotic HP. The patient experienced acute respiratory failure and was managed with high-flow oxygen therapy. A detailed investigation determined that the patient's prior exposure to pet parrots at home was a significant factor. Following treatment with steroids and counseling regarding the removal of parrots from the home environment, the patient's condition improved, and she was successfully weaned off of oxygen therapy. This case underscores the importance of a comprehensive social history in evaluating common complaints such as dyspnea. The rarity of parrot-induced HP related to the patient's age, and exposure warrants attention.

Validation of a computed tomography diagnostic model for differentiating fibrotic hypersensitivity pneumonitis from idiopathic pulmonary fibrosis

BACKGROUND

The diagnosis of fibrotic hypersensitivity pneumonitis (fHP) from other interstitial lung diseases, particularly idiopathic pulmonary fibrosis (IPF), is often difficult. This study aimed to examine computed tomography (CT) findings that were useful for differentiating between fHP and IPF and to develop and validate a radiological diagnostic model.

METHODS

In this study, 246 patients (fHP, n = 104; IPF, n = 142) from two institutions were included and randomly divided into the test (n = 164) and validation (n = 82) groups (at a 2:1 ratio). Three radiologists evaluated CT findings, such as pulmonary fibrosis, small airway disease, and predominant distribution, and compared them between fHP and IPF using binomial logistic regression and multivariate analysis. A prognostic model was developed from the test group and validated with the validation group.

RESULTS

Ground-glass opacity (GGO) with traction bronchiectasis (TB), honeycombing, hypoattenuation area, three-density pattern, diffuse craniocaudal distribution, peribronchovascular opacities in the upper lung, and random distribution were more common in fHP than in IPF. In multivariate analysis, GGO with TB, peribronchovascular opacities in the upper lung, and random distribution were significant features. The area under the curve of the fHP diagnostic model with the three aforementioned CT features was 0.733 (95% confidence interval [CI], 0.655-0.811, p < 0.001) in the test group and 0.630 (95% CI, 0.504-0.755, p < 0.047) in the validation group.

CONCLUSION

GGO with TB, peribronchovascular opacities in the upper lung, and random distribution were important CT features for differentiating fHP from IPF.

Mir-155-5p targets TP53INP1 to promote proliferative phenotype in hypersensitivity pneumonitis lung fibroblasts

Background

Hypersensitivity pneumonitis (HP) is an inflammatory disorder affecting lung parenchyma and often evolves into fibrosis (fHP). The altered regulation of genes involved in the pathogenesis of the disease is not well comprehended, while the role of microRNAs in lung fibroblasts remains unexplored.

Methods

We used integrated bulk RNA-Seq and enrichment pathway bioinformatic analyses to identify differentially expressed (DE)-miRNAs and genes (DEGs) associated with HP lungs. In vitro, we evaluated the expression and potential role of miR-155-5p in the phenotype of fHP lung fibroblasts. Loss and gain assays were used to demonstrate the impact of miR-155-5p on fibroblast functions. In addition, mir-155-5p and its target TP53INP1 were analyzed after treatment with TGF-β, IL-4, and IL-17A.

Results

We found around 50 DEGs shared by several databases that differentiate HP from control and IPF lungs, constituting a unique HP lung transcriptional signature. Additionally, we reveal 18 DE-miRNAs that may regulate these DEGs. Among the candidates likely associated with HP pathogenesis was miR-155-5p. Our findings indicate that increased miR-155-5p in fHP fibroblasts coincides with reduced TP53INP1 expression, high proliferative capacity, and a lack of senescence markers compared to IPF fibroblasts. Induced overexpression of miR-155-5p in normal fibroblasts remarkably increases the proliferation rate and decreases TP53INP1 expression. Conversely, miR-155-5p inhibition reduces proliferation and increases senescence markers. TGF-β, IL-4, and IL-17A stimulated miR-155-5p overexpression in HP lung fibroblasts.

Conclusion

Our findings suggest a distinctive signature of 53 DEGs in HP, including CLDN18, EEF2, CXCL9, PLA2G2D, and ZNF683, as potential targets for future studies. Likewise, 18 miRNAs, including miR-155-5p, could be helpful to establish differences between these two pathologies. The overexpression of miR-155-5p and downregulation of TP53INP1 in fHP lung fibroblasts may be involved in his proliferative and profibrotic phenotype. These findings may help differentiate and characterize their pathogenic features and understand their role in the disease.

Remission of hypersensitivity pneumonitis after allogeneic hematopoietic stem cell transplantation

A 50-year-old man was diagnosed with hypersensitivity pneumonitis caused by the environment of his bar owing to worsening symptoms, laboratory test results, and computed tomography images after an environmental inhalation challenge test. His hypersensitivity pneumonitis exacerbated despite receiving prednisolone 20 mg/day. The patient underwent allogeneic hematopoietic stem cell transplantation (HSCT) from a human leukocyte antigen-matched unrelated donor for myelodysplastic syndrome. No exacerbation of hypersensitivity pneumonitis was observed after HSCT. An environmental inhalation challenge test involving exposure to his bar confirmed the remission of hypersensitivity pneumonitis after HSCT. This case demonstrates that hypersensitivity pneumonitis can be remitted by HSCT.

Impact of an expert-derived, quick hands-on tool on classifying pulmonary hypertension in chest computed tomography: a study on inexperienced readers using RAPID-CT-PH

PURPOSE

To test the inter-reader agreement in classifying pulmonary hypertension (PH) on chest contrast-enhanced computed tomography (CECT) between a consensus of two cardio-pulmonary-devoted radiologists (CRc) and inexperienced readers (radiology residents, RRs) when using a CECT-based quick hands-on tool built upon PH imaging literature, i.e., the "Rapid Access and Practical Information Digest on Computed Tomography for PH-RAPID-CT-PH".

MATERIAL AND METHODS

The observational study retrospectively included 60 PH patients who underwent CECT between 2015 and 2022. Four RRs independently reviewed all CECTs and classified each case into one of the five PH groups per the 2022 ESC/ERS guidelines. While RR3 and RR4 (RAPID-CT-PH group) used RAPID-CT-PH, RR1 and RR2 (control group) did not. RAPID-CT-PH and control groups' reports were compared with CRc using unweighted Cohen's Kappa (k) statistics. RRs' report completeness and reporting time were also compared using the Wilcoxon-Mann-Whitney test.

RESULTS

The inter-reader agreement in classifying PH between the RAPID-CT-PH group and CRc was substantial (k = 0.75 for RR3 and k = 0.65 for RR4); while, it was only moderate for the control group (k = 0.57 for RR1 and k = 0.49 for RR2). Using RAPID-CT-PH resulted in significantly higher report completeness (all p < 0.0001) and significantly lower reporting time (p < 0.0001) compared to the control group.

CONCLUSION

RRs using RAPID-CT-PH showed a substantial agreement with CRc on CECT-based PH classification. RAPID-CT-PH improved report completeness and reduced reporting time. A quick hands-on tool for classifying PH on chest CECT may help inexperienced radiologists effectively contribute to the PH multidisciplinary team.