Fibrotic Hypersensitivity Pneumonitis: Key Issues in Diagnosis and Management

Increased ER Stress and Unfolded Protein Response Activation in Epithelial and Inflammatory Cells in Hypersensitivity Pneumonitis

Several types of cytotoxic insults disrupt endoplasmic reticulum (ER) homeostasis, cause ER stress, and activate the unfolded protein response (UPR). The role of ER stress and UPR activation in hypersensitivity pneumonitis (HP) has not been described. HP is an immune-mediated interstitial lung disease that develops following repeated inhalation of various antigens in susceptible and sensitized individuals. The aim of this study was to investigate the lung expression and localization of the key effectors of the UPR, BiP/GRP78, CHOP, and sXBP1 in HP patients compared with control subjects. Furthermore, we developed a mouse model of HP to determine whether ER stress and UPR pathway are induced during this pathogenesis. In human control lungs, we observed weak positive staining for BiP in some epithelial cells and macrophages, while sXBP1 and CHOP were negative. Conversely, strong BiP, sXBP1- and CHOP-positive alveolar and bronchial epithelial, and inflammatory cells were identified in HP lungs. We also found apoptosis and autophagy markers colocalization with UPR proteins in HP lungs. Similar results were obtained in lungs from an HP mouse model. Our findings suggest that the UPR pathway is associated with the pathogenesis of HP.

Thin-Section CT in the Categorization and Management of Pulmonary Fibrosis including Recently Defined Progressive Pulmonary Fibrosis

While idiopathic pulmonary fibrosis (IPF) is the most common type of fibrotic lung disease, there are numerous other causes of pulmonary fibrosis that are often characterized by lung injury and inflammation. Although often gradually progressive and responsive to immune modulation, some cases may progress rapidly with reduced survival rates (similar to IPF) and with imaging features that overlap with IPF, including usual interstitial pneumonia (UIP)-pattern disease characterized by peripheral and basilar predominant reticulation, honeycombing, and traction bronchiectasis or bronchiolectasis. Recently, the term progressive pulmonary fibrosis has been used to describe non-IPF lung disease that over the course of a year demonstrates clinical, physiologic, and/or radiologic progression and may be treated with antifibrotic therapy. As such, appropriate categorization of the patient with fibrosis has implications for therapy and prognosis and may be facilitated by considering the following categories: (a) radiologic UIP pattern and IPF diagnosis, (b) radiologic UIP pattern and non-IPF diagnosis, and (c) radiologic non-UIP pattern and non-IPF diagnosis. By noting increasing fibrosis, the radiologist contributes to the selection of patients in which therapy with antifibrotics can improve survival. As the radiologist may be first to identify developing fibrosis and overall progression, this article reviews imaging features of pulmonary fibrosis and their significance in non-IPF-pattern fibrosis, progressive pulmonary fibrosis, and implications for therapy. Keywords: Idiopathic Pulmonary Fibrosis, Progressive Pulmonary Fibrosis, Thin-Section CT, Usual Interstitial Pneumonia © RSNA, 2024.

Prognostic factors of progressive fibrotic hypersensitivity pneumonitis: a large, retrospective, multicentre, observational cohort study

Background

Fibrotic hypersensitivity pneumonitis (fHP) is an immune-mediated interstitial lung disease caused by sensitisation to chronic allergen inhalation. This study aimed to determine prognostic indicators of progression and mortality in fHP.

Methods

This was a retrospective, multicentre, observational, cross-sectional cohort study of consecutive patients diagnosed with fHP from 1 January 2012 to 31 December 2021. Multivariate Cox regression analyses were used to calculate hazard ratios (HRs) with 95% confidence intervals for predictors of progression and survival.

Results

A total of 403 patients were diagnosed with fHP: median (interquartile range) age 66.5 (14.0) years, 51.9% females and 55.1% never-smokers. The cause of fHP was mainly fungal (39.7%) or avian (41.4%). Lung biopsy was performed in 269 cases (66.7%). In the whole cohort the variables that were related to mortality or lung transplant were older age (HR 1.08; p<0.001), percentage predicted forced vital capacity (HR 0.96; p=0.001), lymphocytosis in bronchoalveolar lavage (BAL) (HR 0.93; p=0.001), presence of acute exacerbation during follow-up (HR 3.04; p=0.001) and GAP (gender, age and lung physiology) index (HR 1.96; p<0.01). In the group of biopsied patients, the presence of fibroblastic foci at biopsy (HR 8.39; p<0.001) stands out in multivariate Cox regression analyses as a highly significant predictor for increased mortality or lung transplant. GAP index (HR 1.26; p=0.009), lymphocytosis in BAL (HR 0.97; p=0.018) and age (HR 1.03; p=0.018) are also predictors of progression.

Conclusions

The study identified several prognostic factors for progression and/or survival in fHP. The presence of fibroblastic foci at biopsy was a consistent predictor for increased mortality and the presence of lymphocytosis in BAL was inversely related to mortality.

Evaluation of cases with hypersensitivity pneumonia: 10 year analysis

INTRODUCTION

The aim of this study was to examine the clinical features of hypersensitivity pneumonia (HP) cases, diagnostic methods, and related conditions in our hospital, which is a reference clinic in Turkey for chest disease.

METHODS

The population of this retrospective cross-sectional study consists of all hypersensitivity pneumonia patients followed in a tertiary hospital between 2010 and 2019. The data of 78 patients were included in the analysis. Data were grouped by source of exposure (occupational, environmental, and cryptogenic) by examining the files of the patients.

RESULTS

Occupational risk factors were detected in 29 (37.2%) of the cases, environmental risk factors were found in 24 (30.8%) cases, neither occupational nor environmental risk factors were detected in 25 (32%) cases, and they were evaluated as cryptogenic. The time from the onset of symptoms to diagnosis was 15.8 ± 26.6 months. The time from the onset of symptoms to diagnosis was found to be longer in the group with occupational risk factors compared with the other groups and was statistically significant (0.044).

CONCLUSION

HP is a immune-mediated interstitial lung disease induced by repeated exposure to environmental and occupational antigens. Etiological agent can be detected in HP patients by detailed questioning of occupational and environmental exposure that may be associated with the onset of symptoms in cases with suspected HP.

Impact of diagnostic guidelines on the diagnosis of hypersensitivity pneumonitis

Introduction

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease from exposure to environmental antigens. Diagnosing HP could be challenging. The American College of Chest Physicians (CHEST) and American Thoracic Society/Japanese Respiratory Society/and Asociación Latinoamericana del Tórax (ATS/JRS/ALAT) have published diagnostic guidelines in 2021 and 2020 respectively. The CHEST guideline uses four grades of confidence: confident (>90%), provisional high (70-89%), provisional low (51-69%), and unlikely (≤50%). The ATS/JRS/ALAT guideline uses five grades of confidence: definite (>90%), high (80-89%), moderate (70-79%), low (51-69%) and not excluded (≤50%). In this study, we determined how these two guidelines could have affected the diagnosis of HP made before the guidelines.

Methods

Two hundred and fifty-nine adult patients from a previous cohort with HP (ICD-9:495) made between Jan. 1, 2008, and Dec. 31, 2013, at Duke University Medical Center were included. We simplified the diagnostic confidence into three categories so we could compare the guidelines: high (≥90%), intermediate (51-89%), and low (≤50%).

Results

There were 156 female and 103 male. Mean age was 58 (range: 20-90). 68.8% of the patients had restrictive defects (FVC < 80% pred) and 48.6% had lung biopsy. The CHEST guideline classified 33.6% of the patients into high, 59.5% into intermediate and 6.9% into low confidence categories. The ATS/JRS/ALAT guideline classified 29.7% of the patients into high, 21.2% into intermediate and 49.0% into low confidence categories (p < 0.0001 vs. CHEST). Cohen's kappa was 0.331. In patients with identifiable inciting agents (IAs) (N = 168), the CHEST guideline classified 32.1% of the patients into high, 64.3% into intermediate and 3.6% into low confidence categories. The ATS/JRS/ALAT guideline classified 29.2% of the patients into high, 20.8% into intermediate, and 50.0% into low confidence categories. Cohen's kappa was 0.314.

Discussion

In our HP cohort with two-thirds of the patients with restrictive defects, we found the two guidelines had fair agreement in diagnosing HP with or without identifiable IAs. They agreed more when the diagnostic confidence was high. When the diagnostic confidence was lower, however, the ATS/JRS/ALAT guideline was more stringent. Clinicians should be aware of the differences between the two guidelines when evaluating patients suspicious of HP.

Hypersensitivity Pneumonitis: A Pictorial Review Based on the New ATS/JRS/ALAT Clinical Practice Guideline for Radiologists and Pulmonologists

Hypersensitivity pneumonitis (HP) is a complicated and heterogeneous interstitial lung disease (ILD) caused by an excessive immune response to an inhaled antigen in susceptible individuals. Accurate diagnosis of HP is difficult and necessitates a detailed exposure history, as well as a multidisciplinary discussion of clinical, histopathologic, and radiologic data. We provide a pictorial review based on the latest American Thoracic Society (ATS)/Japanese Respiratory Society (JRS)/Asociación Latinoamericana del Tórax (ALAT) guidelines for diagnosing HP through demonstrating new radiologic terms, features, and a new classification of HP which will benefit radiologists and pulmonologists.

Characterizing Subjects Exposed to Humidifier Disinfectants Using Computed-Tomography-Based Latent Traits: A Deep Learning Approach

Around nine million people have been exposed to toxic humidifier disinfectants (HDs) in Korea. HD exposure may lead to HD-associated lung injuries (HDLI). However, many people who have claimed that they experienced HD exposure were not diagnosed with HDLI but still felt discomfort, possibly due to the unknown effects of HD. Therefore, this study examined HD-exposed subjects with normal-appearing lungs, as well as unexposed subjects, in clusters (subgroups) with distinct characteristics, classified by deep-learning-derived computed-tomography (CT)-based tissue pattern latent traits. Among the major clusters, cluster 0 (C0) and cluster 5 (C5) were dominated by HD-exposed and unexposed subjects, respectively. C0 was characterized by features attributable to lung inflammation or fibrosis in contrast with C5. The computational fluid and particle dynamics (CFPD) analysis suggested that the smaller airway sizes observed in the C0 subjects led to greater airway resistance and particle deposition in the airways. Accordingly, women appeared more vulnerable to HD-associated lung abnormalities than men.

Short-term lung function changes predict mortality in patients with fibrotic hypersensitivity pneumonitis

Background and objective

A proportion of patients with fibrotic hypersensitivity pneumonitis (fHP) follow a progressive disease course despite immunosuppressive treatment. Little is known about predictors of mortality in fHP. We aimed to investigate the impact of short‐term lung function changes in fHP on mortality.

Methods

Baseline demographics for 145 consecutive patients with a multi‐disciplinary team diagnosis of fHP, as well as baseline and 1‐year follow‐up of lung function, baseline echocardiographic findings, bronchoalveolar lavage (BAL) cellularity and all‐cause mortality were recorded. Changes in forced vital capacity (FVC) ≥ 5% and ≥10%, and diffusion capacity of the lung for carbon monoxide (DLCO) ≥ 10% and ≥15% at 1 year were calculated. Cox proportional hazards analysis was performed to test for associations with mortality.

Results

Baseline lung function severity, age, presence of honeycombing on computed tomography (CT) and echocardiographic pulmonary arterial systolic pressure (PASP) ≥ 40 mm Hg were associated with early mortality, while BAL lymphocytosis was associated with improved survival. A decline in FVC ≥ 5% (hazard ratio [HR]: 3.10, 95% CI: 2.00–4.81, p < 0.001), FVC ≥ 10% (HR: 3.11, 95% CI: 1.94–4.99, p < 0.001), DLCO ≥ 10% (HR: 2.80, 95% CI: 1.78–4.42, p < 0.001) and DLCO ≥ 15% (HR: 2.92, 95% CI: 1.18–4.72, p < 0.001) at 1 year was associated with markedly reduced survival on univariable and multivariable analyses after correcting for demographic variables, disease severity, honeycombing on CT and treatment, as well as BAL lymphocytosis and PASP ≥ 40 mm Hg on echocardiography, in separate models.

Conclusion

Worsening in FVC and DLCO at 1 year, including a marginal decline in FVC ≥ 5% and DLCO ≥ 10%, is predictive of markedly reduced survival in fHP.

Misalignment between Clinical Mold Antigen Extracts and Airborne Molds Found in Water-Damaged Homes

RATIONALE

Epidemiologic studies have demonstrated that exposure to molds and other fungi can play a role in a variety of allergic and pulmonary diseases in susceptible individuals. Species-specific mold antigen extracts are used in the clinical evaluation of suspected mold-related conditions, however alignment between these extracts and the species of molds identified in the indoor environment of water-damaged homes has not been rigorously evaluated.

OBJECTIVES

To identify the predominant genera and species of mold in the air of homes with water damage, mold growth, and/or occupants with respiratory complaints (complaint homes), and to assess their alignment with the mold antigen extracts used in clinical practice.

METHODS

The genera and species of molds identified in culture-type outdoor and indoor air samples collected from complaint homes throughout the U.S. and Canada from 2002-2017 were examined. Mold antigen extracts available and utilized for skin and serum testing in clinical practice were assessed and alignment between these data were evaluated.

RESULTS

Culture data from 24,455 indoor air samples from 7,547 complaint homes and 29,493 outdoor samples was evaluated. Mean exposure values (CFU/m3) were calculated for each genus and species, and indoor vs outdoor values compared. Penicillium was the predominant genus identified in water-damaged homes, with a mean exposure (233.3 CFU/m3) 2.9 times higher than that of the Aspergillus genus (81.4 CFU/m3). Five Penicillium (P. aurantiogriseum, P. brevicompactum, P. citrinum, P. crustosum, and P. variabile) and three Aspergillus (A. versicolor, A. sydowii, and A. niger) species were identified as the predominant indoor water-damage related fungi. However, none of these Penicillium species and only one of the Aspergillus species is currently available as an antigen extract for use in skin testing or serum testing panels.

CONCLUSIONS

Significant misalignment exists between the currently available mold antigen extracts and the predominant species of molds found in water-damaged homes. Improving alignment has the potential to enhance diagnosis of mold-related diseases including allergic asthma and hypersensitivity pneumonitis and to improve patient outcomes via interventions including antigen avoidance through building remediation and occupant relocation, consistent with the findings of a recent ATS Workshop Report.

Use of peripheral neutrophil to lymphocyte ratio and peripheral monocyte levels to predict survival in fibrotic hypersensitivity pneumonitis (fHP): a multicentre retrospective cohort study

The factors determining disease course and survival in fibrotic hypersensitivity pneumonitis (fHP) have not been fully elucidated.The aim of this study was to describe the characteristics of patients with fHP in a real-world cohort and investigate factors associated with worse outcomes. We aimed to explore the use of neutrophil to lymphocyte ratio (NLR) and peripheral blood monocyte levels in predicting mortality.

METHODS

A retrospective, multicentre, observational UK cohort study.

RESULTS

Patients with fHP were significantly younger than those with idiopathic pulmonary fibrosis (IPF) (median age fHP 73 vs IPF 75 years) and were much more likely to be woman (fHP 61% vs IPF 26%). In almost half of all fHP cases (49%, n=104/211), no causative antigen was identified from either the history or specific antigen testing. Overall, fHP was associated with a better survival than IPF, although median survival of both groups was poor (fHP 62 months vs IPF 52 months).IPF survival in patients with a high NLR was significantly lower than those with a low NLR (44 vs 83 months). A monocyte count ≥0.95 K/uL also predicted significantly poorer outcomes for patients with IPF compared with <0.95 K/uL (33 vs 57 months). In contrast, NLR and monocyte count did not predict survival in the fHP cohort.

CONCLUSIONS

Although fHP has a statistically lower mortality than IPF, absolute survival time of both conditions is poor. High baseline NLR and absolute monocyte counts predict worse survival in IPF but not in fHP, highlighting the potential for divergence in their pathogenic mechanisms.

Hypersensitivity Pneumonitis: Diagnostic and Therapeutic Challenges

Hypersensitivity pneumonitis (HP) is one of the most common interstitial lung diseases (ILD), that presents unique challenges for a confident diagnosis and limited therapeutic options. The disease is triggered by exposure to a wide variety of inciting antigens in susceptible individuals which results in T-cell hyperactivation and bronchioloalveolar inflammation. However, the genetic risk and the pathogenic mechanisms remain incompletely elucidated. Revised diagnostic criteria have recently been proposed, recommending to classify the disease in fibrotic and non-fibrotic HP which has strong therapeutic and outcome consequences. Confident diagnosis depends on the presence of clinical features of ILD, identification of the antigen(s), typical images on high-resolution computed tomography (HRCT), characteristic histopathological features, and lymphocytosis in the bronchoalveolar lavage. However, identifying the source of antigen is usually challenging, and HRCT and histopathology are often heterogeneous and not typical, supporting the notion that diagnosis should include a multidisciplinary assessment. Antigen removal and treating the inflammatory process is crucial in the progression of the disease since chronic persistent inflammation seems to be one of the mechanisms leading to lung fibrotic remodeling. Fibrotic HP has a few therapeutic options but evidence of efficacy is still scanty. Deciphering the molecular pathobiology of HP will contribute to open new therapeutic avenues and will provide vital insights in the search for novel diagnostic and prognostic biomarkers.

Chronic hypersensitivity pneumonitis: real world diagnostic criteria

PURPOSE OF REVIEW

Establishing a diagnosis of hypersensitivity pneumonitis (HP) and distinguishing it from other forms of interstitial lung diseases represents a common challenge in clinical practice. This review summarizes the latest literature and guidelines on HP while integrating some real-life conundrums.

RECENT FINDINGS

Advances in the understanding of the pathobiology of fibrotic HP and other progressive pulmonary fibrosis have changed how we approach the diagnosis and treatment of interstitial lung disease. Classifications now embrace distinguishing two clinical phenotypes: nonfibrotic and fibrotic HP because of distinct disease behavior and prognosis implications. International guidelines on HP were recently published and proposed a framework and algorithm to guide the diagnostic process.

SUMMARY

The diagnosis of HP relies on the integration of multiples domains: clinical assessment of exposure, imaging, bronchoalveolar lavage lymphocytosis and histopathological findings. These features are reviewed in multidisciplinary discussion and lead to an estimation of the degree of confidence for HP diagnosis. Further research is warranted to improve knowledge on the pathophysiology of HP and ultimately improve its diagnostic approaches.

Effect of Oral Methyl Prednisolone on Different Radiological Patterns of Hypersensitivity Pneumonitis

Background

Hypersensitivity pneumonitis (HP) is an immune-mediated disorder that causes inflammation of interstitial lung, bronchioles, and alveoli. Although corticosteroids have been used as first line treatment for HP for many years, it does not provide satisfactory results in all patients. The aim of this study is to compare the effect of oral methylprednisolone on different radiological patterns of HP to identify the most adequate candidates for corticosteroids.

Patients and Methods

Fifty-three patients with confirmed diagnosis of HP were divided into two groups according to their radiological patterns based on high resolution computed tomography (HRCT) findings. The first group included 21 patients with fibrotic HP (fHP), the second group included 32 patients without fibrosis; non-fibrotic HP patients (nfHP). The second group is divided into 3 subgroups: mosaic, attenuation, centrilobular nodules and finally, ground-glass opacities. All patients were administered methylprednisolone by dose 0.5mg/kg/day for eight consecutive weeks. HRCT was performed at the beginning of the study. Spirometry, six-minute walk and oximetry were performed periodically to assess the patients' progress.

Results

Upon finalizing the treatment process, a significant improvement was noticed in FEV1 (p < 0.001), FVC (p <0.001), six-minute walk test (p =0.001) and oximetry (p <0.05) in nfHP compared to the fHP patients. However, there was a significant improvement in (p <0.01), FVC (p <0.01), oximetry (p <0.01) and six-minute walk test (p <0.01) in fibrotic patients after receiving the treatment. There was no significant difference in the response of FEV1 (p =0.82), FVC (p =0.15), six-minute walk test (p =0.36) and oximetry (p =0.27) among the subgroups of nfHP patients.

Conclusion

It was accordingly concluded that corticosteroid treatment is more effective in treatment of nfHP than fHP patients but still has effect on fibrotic patients. There is no significant difference in the response to corticosteroids among nfHP patients' subgroups.

Changes in serum KL-6 levels during short-term strict antigen avoidance are associated with the prognosis of patients with fibrotic hypersensitivity pneumonitis caused by avian antigens

BACKGROUND

Bird-related hypersensitivity pneumonitis (BRHP) is the most common type of fibrotic hypersensitivity pneumonitis (HP). Antigen avoidance (AA) is a key step in the diagnosis and management of HP, but not all fibrotic HP patients improve through AA. Because of the poor prognosis of fibrotic HP, predictive biomarkers to identify patients showing rapid progression during AA are urgently needed.

METHODS

From a retrospective review of the medical records of 1941 patients with interstitial lung disease, 75 cases of fibrotic BRHP confirmed by a provocation test or surgical lung biopsy were identified. To identify potential prognostic markers obtained at or around diagnosis, physiological and serological variables at diagnosis and the relative changes in those variables during strict AA were evaluated. Cox proportional hazards models with log-rank testing were used to compare the associations between these variables and survival.

RESULTS

Univariate analyses showed that gender, smoking status, and the relative change in the serum levels of Krebs von den Lungen-6 (KL-6) were associated with prognosis (P = 0.02, 0.04, and 0.02, respectively), but the presence of honeycombing and the forced vital capacity were not associated with survival. The relative change in KL-6 levels (greater than vs. less than a 10% decrease) was significantly associated with survival in a stratified analysis (73.9 vs. 34.9 months; P = 0.04).

CONCLUSIONS

The relative change in KL-6 levels is associated with the prognosis of patients with fibrotic BRHP independent of previously identified prognostic biomarkers. This finding could help pulmonologists identify fibrotic BRHP patients that are likely to show rapid progression.

Nontransient third-degree heart block and persistent respiratory findings as sequelae of acute occupational exposure to pyrethroids insecticide

We present the case of a worker with occupational exposure to a pyrethroid insecticide who acutely developed nontransient third-degree heart block. In 2000, a 57-year-old male truck driver on his delivery route was accidentally exposed to pyrethroid insecticide being sprayed for West Nile virus containment. Both the driver and his vehicle were coated with the spray. The exposure was prolonged because he did not change his clothes until after his shift ended and he used the same contaminated truck for a week. Within days, he presented with a third-degree heart block, for which he was emergently treated, and a pacemaker was placed. He had no past history of arrhythmias. In the weeks thereafter, he also developed reactive airway dysfunction syndrome (RADS). In the second decade following the exposure, the patient replaced his pacemaker, confirming the permanent nature of his heart block. In addition to the persistence of his exposure-related RADS, he developed restrictive lung disease and was diagnosed with pulmonary interstitial fibrosis in the absence of established risk factors. The patient died in October 2019 from respiratory illness. Most previous reports of pyrethroid-related disorders are limited to acute exposures, in which transient symptoms predominate. To our knowledge, this is the first report of an exposed worker experiencing permanent third-degree heart block, as well as persistent respiratory findings, as possible short- and long-term sequelae of pyrethroid exposure.

BAL and serum multiplex lipid profiling in idiopathic pulmonary fibrosis and fibrotic hypersensitivity pneumonitis

BACKGROUND

Differential diagnosis between IPF and fibrotic HP (fHP) can be challenging: these two ILDs share many common features but call for different therapeutic approaches. In the present study, differential lipid mediator profiles were analysed by a new method in BAL and serum from HP and IPF patients.

MATERIALS AND METHODS

76 patients were enrolled retrospectively in the study. Median age (IQR) was 67 years (51-74); 63% were males, 30 had fHP and 46 had IPF. Serum and BAL samples were collected at initial diagnosis. For quantification of serum and BAL lipid mediators was used bead-based multiplex LEGENDPlex™ analysis (Biolegend).

RESULTS

Serum Apo A1 levels were significantly higher in IPF than fHP patients (p = 0.314); indeed, serum levels of CCL2 and Apo C3 were lower in HP than in IPF patients (p = 0.013 and p = 0.041, respectively). BAL concentrations of Apo A1, adipsin, Apo C3 and APN were significantly lower in IPF than in fHP patients (p < 0.0001, p < 0.0001, p = 0.007 and p = 0.023, respectively). In the logistic regression, IPF was tested as dependent variable. Serum levels of Apo A1, CCL2 and Apo C3 were tested as independent variables and ROC curve analysis of model performance showed AUC 93% (p < 0.0001); on the other hand, BAL concentrations of Apo A1, adipsin, Apo C3 and APN showed AUC 81% (p < 0.0001).

DISCUSSION

Lipid biomarkers evaluated in BAL in our study confirm the hypothesis that fHP and IPF have different lung fibrosis phenotypes. The former is a post-inflammatory cell-regulated ILD and the second is more related to tissue remodeling and repair.

Identifying causation in hypersensitivity pneumonitis: a British perspective

Background

Establishing whether patients are exposed to a ‘known cause’ is a key element in both the diagnostic assessment and the subsequent management of hypersensitivity pneumonitis (HP).

Objective

This study surveyed British interstitial lung disease (ILD) specialists to document current practice and opinion in relation to establishing causation in HP.

Methods

British ILD consultants (pulmonologists) were invited by email to take part in a structured questionnaire survey, to provide estimates of demographic data relating to their service and to rate their level of agreement with a series of statements. A priori ‘consensus agreement’ was defined as at least 70% of participants replying that they ‘Strongly agree’ or ‘Tend to agree’.

Results

54 consultants took part in the survey from 27 ILD multidisciplinary teams. Participants estimated that 20% of the patients in their ILD service have HP, and of these, a cause is identifiable in 32% of cases. For patients with confirmed HP, an estimated 40% have had a bronchoalveolar lavage for differential cell counts, and 10% a surgical biopsy. Consensus agreement was reached for 25 of 33 statements relating to causation and either the assessment of unexplained ILD or management of confirmed HP.

Conclusions

This survey has demonstrated that although there is a degree of variation in the diagnostic approach for patients with suspected HP in Britain, there is consensus opinion for some key areas of practice. There are several factors in clinical practice that currently act as potential barriers to identifying the cause for British HP patients.

An Open-label Study With Pirfenidone on Chronic Hypersensitivity Pneumonitis

BACKGROUND

Chronic hypersensitivity pneumonitis (cHP) represents a severe lung disease often evolving to fibrosis with the subsequent destruction of the lung parenchyma. There are no approved therapies with confirmed efficacy to deal with this disease.

METHODS

We performed an open-label, proof of concept study, to evaluate the efficacy and safety of pirfenidone added to immunosuppressive drugs on the treatment of cHP. We included 22 patients assigned to two groups: Group 1, nine patients that received prednisone plus azathioprine and Group 2, thirteen patients, received prednisone plus azathioprine and pirfenidone (ClinicalTrials.gov identifier NCT02496182). There were no significant imbalances in clinically relevant baseline characteristics between two study groups.

RESULTS

After 1 year of treatment, inclusion of pirfenidone was not associated with improved forced vital capacity (primary end-point). A not significant tendency to show higher improvement of diffusion capacity of the lung for carbon monoxide (D_LCO) was observed in the group receiving pirfenidone (p=0.06). Likewise, a significant improvement in the total score on the SGRQ was found in the group 2 (p=0.02) without differences in other two questionnaires related to quality of life (ATAQ-IPF and EQ-5D-3L). HRCT showed a decrease of the ground glass attenuation without changes in the fibrotic lesions and without differences between both groups.

CONCLUSIONS

These findings suggest that the addition of pirfenidone to the anti-inflammatory treatment in patients with chronic HP may improve the outcome with acceptable safety profile. However, prospective randomized double-blind, placebo-controlled trials in largest cohorts are needed to validate its efficacy.

Usefulness of new diagnostic criteria for chronic hypersensitivity pneumonitis established on the basis of a Delphi survey: A Japanese cohort study

BACKGROUND

Chronic hypersensitivity pneumonitis (CHP) is a fibrotic interstitial lung disease (ILD) caused by repeated exposure to a variety of organic particles. In November 2017, new criteria for CHP diagnosis were proposed by Morisset et al. based on a modified Delphi survey of ILD experts. However, it remains unclear whether these criteria are useful to accurately diagnose CHP. We aimed to evaluate the newly proposed CHP diagnostic criteria.

METHODS

We retrospectively applied Morisset's CHP diagnostic criteria to consecutive Japanese patients who underwent surgical lung biopsy for diagnosis of ILD from 2008 to 2015. All patients underwent bronchoalveolar lavage and pulmonary function testing. Patients who had connective tissue disease complications or showed an acute or subacute disease onset were excluded.

RESULTS

A total of 251 patients were included. The diagnoses based on multidisciplinary discussion (MDD) were CHP (n = 27), idiopathic pulmonary fibrosis (n = 117), unclassifiable interstitial pneumonia (IP) (n = 65), and other diagnoses (n = 42). Of the 27 MDD-CHP patients, 14 were classified as a CHP group with diagnostic confidence >50% and 13 were not categorized (sensitivity, 51.9%; specificity, 77.7%). Morisset's CHP diagnostic criteria could help avoid SLB for the diagnosis of CHP in seven patients. Of the 13 MDD-CHP patients who were not categorized in the CHP group with diagnostic confidence >50%, the reason for the exclusion was an inconsistent with UIP pattern without CHP features.

CONCLUSIONS

Half of the MDD-CHP patients were diagnosed with CHP using Morisset's CHP diagnostic criteria. Further investigation will be important for developing improved diagnostic criteria for CHP.

Hypersensitivity pneumonitis: Main features characterization in a Portuguese cohort

Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) which varies in prevalence across the world, depending on disease definition, diagnostic methods, exposure type and intensity, geographical environments, agricultural and industrial practices, and host risk factors. This study aimed to deepen knowledge about HP's clinical characteristics, diagnosis and functional and imaging features in a cohort of HP patients from the North of Portugal. To achieve this goal, a retrospective assessment of the clinical and diagnostic data was carried out, and patients were classified and compared according to disease presentation (acute, sub-acute and chronic HP forms). Of the 209 HP patients included (mean age 58.3 ± 16.0 years), 52.6% were female and 73.7% presented a chronic form. Most patients had prior exposure to birds (76.6%). Dyspnoea and cough were the most frequently experienced symptoms, but no statistically significant differences were found between groups (p = 0.089, p = 0.418, respectively). Fever was most common in acute HP form (p < 0.001). The most common patterns found in Chest CT were ground glass (p = 0.002) in acute/subacute presentation, and reticulation (p < 0.001) in chronic form, while mosaic attenuation, although was also frequently observed, no statistically significant differences were found between groups (p = 0.512). The most common functional pattern was restrictive (38% of patients, 73.7% with chronic HP form). Bronchoalveolar lavage lymphocytes were higher in acute and subacute forms although not reaching statistical significance (p = 0.072), with lowest CD4/CD8 ratio (p = 0.001) in acute forms. Thus, given the significant disease heterogeneity, further studies with different populations and ambient exposures are needed to achieve a better stratification of the exposure risk, to provide proper implementation of avoidance methods and a precise diagnostic and therapeutic approach.

Clinical features of chronic summer-type hypersensitivity pneumonitis and proposition of diagnostic criteria

BACKGROUND

Trichosporon asahii (T. asahii) causes chronic summer-type hypersensitivity pneumonitis (C-SHP); however, little is known about the clinical features of this condition. We aimed to elucidate the clinical features of C-SHP and propose practical diagnostic criteria for C-SHP based on the presence of serum anti-T. asahii antibody (TaAb).

METHODS

Patients diagnosed with C-SHP and idiopathic pulmonary fibrosis (IPF) between January 2010 and May 2017 were reviewed retrospectively. Clinical findings were compared between the two groups. Criteria for C-SHP were proposed on the basis of significant characteristics and applied to the development and validation cohorts.

RESULTS

Thirty-one patients with C-SHP and 26 with TaAb-negative IPF were identified. C-SHP patients were more likely to live in wooden houses; their serum Krebs von den Lungen-6 (KL-6) and serum surfactant protein-D (SP-D) levels were higher than those of IPF patients. C-SHP patients were more likely to have subpleural consolidation, micronodules, and extensive ground-glass opacification on high-resolution computed tomography (HRCT). The following 3 items were considered to have diagnostic value: I) TaAb positivity; II) an HRCT pattern consistent with chronic hypersensitivity pneumonitis, including mosaic attenuation or micronodules; and III) elevated serum biomarker levels (KL-6 > 1500 U/mL or SP-D > 250 ng/mL). We defined cases satisfying I) and II) as "probable C-SHP" and those satisfying all 3 criteria as "confident clinical diagnosis of C-SHP". The areas under the receiver-operating curve were 0.965 and 0.993 in the development and validation cohorts, respectively, which suggested that these criteria had good discriminative ability in clinical evaluations.

CONCLUSIONS

Clinical features could be useful for distinguishing C-SHP from IPF and other etiologies of ILDs.

Presentation, diagnosis and clinical course of the spectrum of progressive-fibrosing interstitial lung diseases

Although these conditions are rare, a proportion of patients with interstitial lung diseases (ILDs) may develop a progressive-fibrosing phenotype. Progressive fibrosis is associated with worsening respiratory symptoms, lung function decline, limited response to immunomodulatory therapies, decreased quality of life and, potentially, early death. Idiopathic pulmonary fibrosis may be regarded as a model for other progressive-fibrosing ILDs. Here we focus on other ILDs that may present a progressive-fibrosing phenotype, namely idiopathic nonspecific interstitial pneumonia, unclassifiable idiopathic interstitial pneumonia, connective tissue disease-associated ILDs (e.g. rheumatoid arthritis-related ILD), fibrotic chronic hypersensitivity pneumonitis, fibrotic chronic sarcoidosis and ILDs related to other occupational exposures. Differential diagnosis of these ILDs can be challenging, and requires detailed consideration of clinical, radiological and histopathological features. Accurate and early diagnosis is crucial to ensure that patients are treated optimally.

Healthcare utilisation and costs in the diagnosis and treatment of progressive-fibrosing interstitial lung diseases

There are over 200 interstitial lung diseases (ILDs). In addition to patients with idiopathic pulmonary fibrosis (IPF), a percentage of patients with other ILDs also develop progressive fibrosis of the lung during their disease course. Patients with progressive-fibrosing ILDs may show limited response to immunomodulatory therapy, worsening symptoms and lung function and, ultimately, early mortality. There are few data for ILDs that may present a progressive fibrosing phenotype specifically, but we believe the burden and healthcare costs associated with these conditions may be comparable to those reported in IPF. This review discusses the burden of ILDs that may present a progressive fibrosing phenotype and the factors impacting healthcare utilisation.

Idiopathic pulmonary fibrosis in West Highland white terriers: An update

Canine idiopathic pulmonary fibrosis (CIPF) affects middle-aged to older dogs of a single breed, mainly the West Highland white terrier (WHWT), which is suggestive of a genetic predisposition. CIPF causes exercise intolerance, restrictive dyspnoea and coughing. Coarse crackles are heard on thoracic auscultation. Abnormal blood gas parameters and a shortened '6-min-walking test' distance are common; secondarily induced pulmonary hypertension and/or airway collapse are frequent. These features of CIPF mimic those of idiopathic pulmonary fibrosis (IPF) in humans and therefore identify CIPF as a possible spontaneously arising model for study of human IPF. However, computed tomographic and histopathological findings of CIPF are not identical to those of human IPF. As in human IPF, the aetiology of CIPF is not yet fully elucidated. There are no curative treatments and the prognosis is poor. This paper reviews advances in understanding of the clinical description and natural history of CIPF, the investigation of biomarkers and the exploration of possible aetiologies and mechanistic hypotheses.

Hypersensitivity pneumonitis: Antigen diversity and disease implications

Hypersensitivity pneumonitis (HP) is an immune-mediated syndrome triggered by inhalation of a wide variety of allergens, to which an individual has previously been sensitized. More than 200 agents responsible for the disease have already been identified; however, HP occurs only in a small number of individuals exposed to causal antigens. The present report provides an overview of the role of antigen role in HP, highlighting its diversity, research methods, and prevention strategies, as well as the impact on disease prognosis following elimination of antigen. HP is an underdiagnosed disease and, therefore, it is difficult to accurately estimate its incidence. Triggering antigens can be divided into six broad categories: bacteria, fungi, mycobacteria, animal and plant proteins, chemicals, and metals, represented by disease prototypes. The identification of causal antigen is a major challenge; it is impossible to obtain in about 30-60% of cases. The acute form of HP, with early detection and immediate eviction of causal antigen, tends to have an excellent prognosis. In the chronic form, partial recovery of disease is still possible; however, some cases tend to progress to fibrosis, even after removal from exposure. In conclusion, HP diagnosis should be based on a proactive search for potential antigen sources, although their identification is hampered by the lack of standardized methods of demonstrating the specific antigen sensitization. Antigen avoidance is a critical determinant in disease prognosis.

Identification of Diagnostic Criteria for Chronic Hypersensitivity Pneumonitis: An International Modified Delphi Survey

RATIONALE

Current diagnosis of chronic hypersensitivity pneumonitis (cHP) involves considering a combination of clinical, radiological, and pathological information in multidisciplinary team discussions. However, this approach is highly variable with poor agreement between centers.

OBJECTIVES

We aimed to identify diagnostic criteria for cHP that reach consensus among international experts.

METHODS

A 3-round modified Delphi survey was conducted between April and August 2017. Forty-five experts in interstitial lung disease from 14 countries participated in the online survey. Diagnostic items included in round 1 were generated using expert interviews and literature review. During rounds 1 and 2, experts rated the importance of each diagnostic item on a 5-point Likert scale. The a priori threshold of consensus was ≥ 75% of experts rating a diagnostic item as very important or important. In the third round, experts graded the items that met consensus as important and provided their level of diagnostic confidence for a series of clinical scenarios.

MEASUREMENTS AND MAIN RESULTS

Consensus was achieved on 18 of the 40 diagnostic items. Among these, experts gave the highest level of importance to the identification of a causative antigen, time relation between exposure and disease, mosaic attenuation on chest imaging, and poorly formed non-necrotizing granulomas on pathology. In clinical scenarios, the diagnostic confidence of experts in cHP was heightened by the presence of these diagnostic items.

CONCLUSION

This consensus-based approach for the diagnosis of cHP represents a first step towards the development of international guidelines for the diagnosis of cHP.