Exposure assessment in hypersensitivity pneumonitis: a comprehensive review and proposed screening questionnaire

Immunopathological characteristics and therapeutic effects of UC-MSCs in a pigeon breeder's lung mouse model

Hypersensitivity pneumonitis (HP), including pigeon breeder's lung (PBL), often progresses from acute inflammation to fibrosis, impairing lung function and limiting targeted therapeutic strategies. Mechanistic studies on PBL progression are limited by the lack of preclinical animal models and a predominant focus on patient data. This study explores the immunopathological characteristics of all stages of PBL in mice and evaluates the therapeutic potential of human umbilical cord-derived mesenchymal stem cells (UC-MSCs) during the non-fibrotic stage. PBL models are created in A/J mice through tracheal instillation of pigeon dropping extract (PDE) protein powder. Different doses (0.4 × 10 6, 0.8 × 10 6, and 1.6 × 10 6 cells per animal) and frequencies (1-2 times) are administered to the model. The immunopathological characteristics of PBL and the therapeutic effects of UC-MSCs are assessed using micro-CT, pulmonary function, histopathology, cell counts in BALF, HYP levels, inflammatory factor levels, immunohistochemistry, and fibrosis marker expression in lung tissues. The results show that PDE exposure consistently impairs pulmonary function and increases the levels of inflammation and fibrosis markers as the disease progresses. Model mice experience non-fibrotic stages (acute inflammation) from days 0-36, mild fibrosis from days 37-77, and severe fibrosis from day 78 onwards. UC-MSCs, particularly at the highest dose (1.6 × 10 6 cells), effectively treat non-fibrotic PBL by improving pulmonary function (lung ventilation area recovers) and reducing inflammation and fibrosis. This study successfully establishes PBL mouse models reflecting both the acute (inflammatory) and chronic (fibrotic) stages, and UC-MSCs have the potential to delay fibrosis, providing new therapeutic options for PBL and other inflammation-induced lung fibrotic diseases.

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.

[Medical clinical diagnostics for indoor mould exposure - Update 2023 (AWMF Register No. 161/001)]

This article is an abridged version of the updated AWMF mould guideline "Medical clinical diagnostics in case of indoor mould exposure - Update 2023", presented in July 2023 by the German Society of Hygiene, Environmental Medicine and Preventive Medicine (Gesellschaft für Hygiene, Umweltmedizin und Präventivmedizin, GHUP), in collaboration with German and Austrian scientific medical societies, and experts. Indoor mould growth is a potential health risk, even if a quantitative and/or causal relationship between the occurrence of individual mould species and health problems has yet to be established. There is no evidence for a causal relationship between moisture/mould damage and human diseases, mainly because of the ubiquitous presence of fungi and hitherto inadequate diagnostic methods. Sufficient evidence for an association between moisture/mould damage and the following health effects has been established for: allergic respiratory diseases, allergic rhinitis, allergic rhino-conjunctivitis, allergic bronchopulmonary aspergillosis (ABPA), other allergic bronchopulmonary mycosis (ABPM), aspergilloma, Aspergillus bronchitis, asthma (manifestation, progression, exacerbation), bronchitis (acute, chronic), community-acquired Aspergillus pneumonia, hypersensitivity pneumonitis (HP; extrinsic allergic alveolitis (EEA)), invasive Aspergillosis, mycoses, organic dust toxic syndrome (ODTS) [workplace exposure], promotion of respiratory infections, pulmonary aspergillosis (subacute, chronic), and rhinosinusitis (acute, chronically invasive, or granulomatous, allergic). In this context the sensitizing potential of moulds is obviously low compared to other environmental allergens. Recent studies show a comparatively low sensitization prevalence of 3-22,5 % in the general population across Europe. Limited or suspected evidence for an association exist with respect to atopic eczema (atopic dermatitis, neurodermatitis; manifestation), chronic obstructive pulmonary disease (COPD), mood disorders, mucous membrane irritation (MMI), odor effects, and sarcoidosis. (iv) Inadequate or insufficient evidence for an association exist for acute idiopathic pulmonary hemorrhage in infants, airborne transmitted mycotoxicosis, arthritis, autoimmune diseases, cancer, chronic fatigue syndrome (CFS), endocrinopathies, gastrointestinal effects, multiple chemical sensitivity (MCS), multiple sclerosis, neuropsychological effects, neurotoxic effects, renal effects, reproductive disorders, rheumatism, sick building syndrome (SBS), sudden infant death syndrome, teratogenicity, thyroid diseases, and urticaria.The risk of infection posed by moulds regularly occurring indoors is low for healthy persons; most species are in risk group 1 and a few in risk group 2 (Aspergillus fumigatus, A. flavus) of the German Biological Agents Act (Biostoffverordnung). Only moulds that are potentially able to form toxins can be triggers of toxic reactions. Whether or not toxin formation occurs in individual cases is determined by environmental and growth conditions, water activity, temperature and above all the growth substrates.In case of indoor moisture/mould damage, everyone can be affected by odor effects and/or mood disorders.However, this is not an acute health hazard. Predisposing factors for odor effects can include genetic and hormonal influences, imprinting, context and adaptation effects. Predisposing factors for mood disorders may include environmental concerns, anxiety, condition, and attribution, as well as various diseases. Risk groups to be protected particularly regarding infection risk are immunocompromised persons according to the classification of the German Commission for Hospital Hygiene and Infection Prevention (Kommission für Krankenhaushygiene und Infektionsprävention, KRINKO) at the Robert Koch-Institute (RKI), persons suffering from severe influenza, persons suffering from severe COVID-19, and persons with cystic fibrosis (mucoviscidosis); with regard to allergic risk, persons with cystic fibrosis (mucoviscidosis) and patients with bronchial asthma must be protected. The rational diagnostics include the medical history, physical examination, and conventional allergy diagnostics including provocation tests if necessary; sometimes cellular test systems are indicated. In the case of mould infections, the reader is referred to the specific guidelines. Regarding mycotoxins, there are currently no useful and validated test procedures for clinical diagnostics. From a preventive medical point of view, it is important that indoor mould infestation in relevant magnitudes cannot be tolerated for precautionary reasons.For evaluation of mould damage in the indoor environment and appropriate remedial procedures, the reader is referred to the mould guideline issued by the German Federal Environment Agency (Umweltbundesamt, UBA).

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.

Notch Signaling Is Associated with Pulmonary Fibrosis in Patients with Pigeon Breeder's Lung by Regulating Oxidative Stress

This study explored the molecular mechanism underlying the association of Notch signaling and oxidative stress with the occurrence of pulmonary fibrosis in patients with pigeon breeder's lung (PBL). Rat models of fibrotic PBL were constructed with freeze-dried protein powder, and the animals were divided into the control (intratracheal instillation of normal saline; n = 9), M (PBL model; intratracheal instillation of freeze-dried protein powder; n = 9), and M + D (PBL+ the Notch inhibitor DAPT; n = 9) groups. Immunohistochemistry was employed to observe the protein levels of pathway factors and α-SMA, and the levels of ROS, GSH-PX, SOD, and MDA were observed using ELISA. To verify the results of the animal experiment, cytological models were constructed. The M group and the M + D group had significantly increased α-SMA levels (P < 0.05). Although both groups had significantly higher key protein levels in the Notch channel, the M + D group had significantly lower levels relative to the M group (P < 0.05). Oxidative stress products were examined, and the levels of MDA and ROS were significantly increased, while those of GSH-PX and SOD were significantly decreased in the M and M + D groups as compared to the control, but the M group and the M + D group significantly differed (P <  0.05). These findings were further validated by the cytological experiment. Notch signaling is associated with pulmonary fibrosis in PBL by regulating cellular oxidative stress, and inhibiting this pathway can slow down pulmonary fibrosis progression.

Scoping review of exposure questionnaires and surveys in interstitial lung disease

BACKGROUND

Many interstitial lung diseases (ILDs) have clear causal relationships with environmental and occupational exposures. Exposure identification can assist with diagnosis, understanding disease pathogenesis, prognostication and prevention of disease progression and occurrence in others at risk. Despite the importance of exposure identification in ILD, there is no standardised assessment approach. Many questionnaires are in clinical and research use, yet their utility, applicability, relevance and performance characteristics are unknown.

OBJECTIVES

This scoping review aimed to summarise the available evidence relating to ILD exposure assessment questionnaires, identify research gaps and inform the content for a future single evidence-based ILD questionnaire.

METHODS

A scoping review based on Arksey and O'Malley's methodological framework was conducted.

ELIGIBILITY CRITERIA

Any questionnaire that elicited exposures specific to ILD was included. A modified COSMIN Risk of Bias Framework was used to assess quality.

SOURCES OF EVIDENCE

Relevant articles were identified from MEDLINE and EMBASE up to 23 July 2023.

RESULTS

22 exposure questionnaires were identified, including 15 generally pertaining to ILD, along with several disease-specific questionnaires for hypersensitivity pneumonitis (n=4), chronic beryllium disease, sarcoidosis and silicosis (1 questionnaire each). For most questionnaires, quality was low, whereby the methods used to determine exposure inclusion and questionnaire validation were not reported or not performed. Collectively the questionnaires covered 158 unique exposures and at-risk occupations, most commonly birds, mould/water damage, wood dust, asbestos, farming, automotive mechanic and miners. Only five questionnaires also provided free-text fields, and 13 queried qualifiers such as temporality or respiratory protection.

CONCLUSIONS

Designing a robust ILD-specific questionnaire should include an evidence-based and relevance-based approach to exposure derivation, with clinicians and patients involved in its development and tested to ensure relevance and feasibility.

AWMF mold guideline "Medical clinical diagnostics for indoor mold exposure" - Update 2023 AWMF Register No. 161/001

None.

Hypersensitivity Pneumonitis: Challenges of a Complex Disease

Hypersensitivity pneumonitis (HP) is a complex interstitial lung disease caused by chronic inhalation of a wide variety of antigens in susceptible and sensitized individuals, commonly associated with an occupational exposure. An impressive number of inciting antigens causing hypersensitivity pneumonitis have been found to cover a wide range of occupations. As working practices have changed over time, especially in industrialized countries, new names for occupational HP have emerged. This review emphasizes the main diagnostic issues arising from the high variability of clinical presentation and the broad spectrum of causal antigens. Furthermore, it provides an overview of current methods to unveil possible causes of hypersensitivity pneumonitis, highlights HP's current diagnostic and treatment challenges and the remaining areas of uncertainty, and presents prevention strategies.

Concurrent features of sarcoidosis and hypersensitivity pneumonitis in two patients exposed to fungal antigens

BACKGROUND

Sarcoidosis and hypersensitivity pneumonitis (HP) are two distinct clinical entities that share granulomatous inflammation, although each of them has specific clinical, radiologic and pathologic profiles. Coexistence of the two diseases have been described, suggesting, at least in some cases, a common biologic background.

CASE PRESENTATION

We describe two patients showing the concurrent diagnosis of sarcoidosis and hypersensitivity pneumonitis. Case 1: a 51-year old never smoker man had a history of occupational exposure, episodes of acute exacerbations and positive serum precipitins to Penicillium spp suggestive of HP, while the positivity of serum angiotensin converting enzyme (ACE) favored sarcoidosis. Case 2: a 42-year old non-smoker woman with occasional finding of enlarged mediastinal lymph nodes had a history of domestic exposure to molds and positive serum precipitins to Aspergillus spp suggestive of HP. In both cases high resolution computed tomography (HRCT) together with broncoscopy findings allowed to maintain both the diagnoses: HRCT showed both enlarged hilar/mediastinal limph nodes and intersitial lung involvement typical of HP; bronchoalveolar lavage presented marked lymphocytosis and granulomatous nodal lesions were observed at transbronchial needle aspiration.

CONCLUSIONS

Sarcoidosis and HP share some clinical findings and the differential diagnosis may be difficult. Our cases suggest that a common trait may be responsible for the concurrent diagnosis of sarcoidosis and hypersensitivity pneumonitis in the same patient.

Genetic and environmental factors in interstitial lung diseases: current and future perspectives on early diagnosis of high-risk cohorts

Within the wide scope of interstitial lung diseases (ILDs), familial pulmonary fibrosis (FPF) is being increasingly recognized as a specific entity, with earlier onset, faster progression, and suboptimal responses to immunosuppression. FPF is linked to heritable pathogenic variants in telomere-related genes (TRGs), surfactant-related genes (SRGs), telomere shortening (TS), and early cellular senescence. Telomere abnormalities have also been identified in some sporadic cases of fibrotic ILD. Air pollution and other environmental exposures carry additive risk to genetic predisposition in pulmonary fibrosis. We provide a perspective on how these features impact on screening strategies for relatives of FPF patients, interstitial lung abnormalities, ILD multi-disciplinary team (MDT) discussion, and disparities and barriers to genomic testing. We also describe our experience with establishing a familial interstitial pneumonia (FIP) clinic and provide guidance on how to identify patients with telomere dysfunction who would benefit most from genomic testing.

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.

Challenges in the Diagnosis and Management of Fibrotic Hypersensitivity Pneumonitis: A Practical Review of Current Approaches

Recent advances in fibrotic hypersensitivity pneumonitis include improved diagnostic guidance, systematic assessments of immunosuppressive therapy, and the recent availability of antifibrotic therapy (nintedanib) for those with progressive disease. A standardized approach to diagnosis may lead to better inclusion criteria for future therapeutic protocols and delineation of disease or treatment response predictors for real-world management. This review will highlight current diagnostic and treatment challenges and remaining knowledge gaps or areas of uncertainty, with a practical overview of supporting evidence and its clinical implications. Exposure history, serologic testing for antigen sensitivity, bronchoalveolar lavage lymphocytosis, histopathology, and radiologic findings will be covered in the diagnosis section, with immunosuppression, antifibrotic therapy, lung transplantation, and disease prognosis in the treatment and management section.

Hypersensitivity pneumonitis: Current concepts in pathogenesis, diagnosis, and treatment

Hypersensitivity pneumonitis is an immune-mediated interstitial lung disease caused by an aberrant response to an inhaled exposure, which results in mostly T cell-mediated inflammation, granuloma formation, and fibrosis in some cases. HP is diagnosed by exposure identification, HRCT findings of ground-glass opacities, centrilobular nodules, and mosaic attenuation, with traction bronchiectasis and honeycombing in fibrotic cases. Additional testing including serum IgG testing for the presence of antigen exposure, bronchoalveolar lavage lymphocytosis, and lung biopsy demonstrating granulomas, inflammation, and fibrosis, increases the diagnostic confidence. Treatment for HP includes avoidance of the implicated exposure, immunosuppression, and anti-fibrotic therapy in select cases. This narrative review presents the recent literature in the understanding of the immunopathological mechanisms, diagnosis, and treatment of HP.

Exposures and associations with clinical phenotypes in hypersensitivity pneumonitis: A scoping review

Antigen identification is important for establishing a confident diagnosis of hypersensitivity pneumonitis (HP). There are no systematically curated lists of HP-associated exposures that inform clinical relevance or disease phenotype. We sought to systematically identify all reported causes of HP in the literature and evaluate their clinical relevance. A scoping review was performed to identify all publications describing HP cases and their associated exposures (even if unknown) from Jan 1990-June 2020. Frequencies of exposures and meta-analysis of proportions for registry-based studies were determined for specific exposure categories, and associations with fibrotic and non-fibrotic HP were assessed. 24,138 publications were identified, with 967 publications included in the final analysis, representing 62 unique exposures associated with HP. Certain exposures were more frequently reported than others, including birds (comprising 32% of HP cases in registry-based studies) and mould (17% registry study HP cases). Antigen-indeterminate HP comprised 15-24% of registry-based studies. Limited data found contaminated metal-working fluids, isocyanate exposure, and hot tub lung were rarely associated with fibrotic features, whereas antigen-indeterminate HP cases were more frequently associated with fibrosis. There was heterogeneity in HP case definition and how causative exposures were identified. We identified 62 unique exposures associated with HP, with specific exposures associated with clinical phenotypes. These data may inform clinical assessment and the development of questionnaires to identify antigens in the diagnostic evaluation of suspected HP. OPEN SCIENCES FRAMEWORK REGISTRATION: osf.io/4aq5m.

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.